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unionfs: apply unionfs patch

This commit is contained in:
Nobody 2020-10-14 01:17:03 +03:00
parent ad44f5675c
commit 3878bb6f09
39 changed files with 11036 additions and 10 deletions
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2
Documentation/filesystems/00-INDEX
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@ -144,6 +144,8 @@ udf.txt
- info and mount options for the UDF filesystem.
ufs.txt
- info on the ufs filesystem.
unionfs/
- info on the unionfs filesystem
vfat.txt
- info on using the VFAT filesystem used in Windows NT and Windows 95.
vfs.txt

10
Documentation/filesystems/unionfs/00-INDEX Normal file
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@ -0,0 +1,10 @@
00-INDEX
- this file.
concepts.txt
- A brief introduction of concepts.
issues.txt
- A summary of known issues with unionfs.
rename.txt
- Information regarding rename operations.
usage.txt
- Usage information and examples.

287
Documentation/filesystems/unionfs/concepts.txt Normal file
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@ -0,0 +1,287 @@
Unionfs 2.x CONCEPTS:
=====================
This file describes the concepts needed by a namespace unification file
system.
Branch Priority:
================
Each branch is assigned a unique priority - starting from 0 (highest
priority). No two branches can have the same priority.
Branch Mode:
============
Each branch is assigned a mode - read-write or read-only. This allows
directories on media mounted read-write to be used in a read-only manner.
Whiteouts:
==========
A whiteout removes a file name from the namespace. Whiteouts are needed when
one attempts to remove a file on a read-only branch.
Suppose we have a two-branch union, where branch 0 is read-write and branch
1 is read-only. And a file 'foo' on branch 1:
./b0/
./b1/
./b1/foo
The unified view would simply be:
./union/
./union/foo
Since 'foo' is stored on a read-only branch, it cannot be removed. A
whiteout is used to remove the name 'foo' from the unified namespace. Again,
since branch 1 is read-only, the whiteout cannot be created there. So, we
try on a higher priority (lower numerically) branch and create the whiteout
there.
./b0/
./b0/.wh.foo
./b1/
./b1/foo
Later, when Unionfs traverses branches (due to lookup or readdir), it
eliminate 'foo' from the namespace (as well as the whiteout itself.)
Opaque Directories:
===================
Assume we have a unionfs mount comprising of two branches. Branch 0 is
empty; branch 1 has the directory /a and file /a/f. Let's say we mount a
union of branch 0 as read-write and branch 1 as read-only. Now, let's say
we try to perform the following operation in the union:
rm -fr a
Because branch 1 is not writable, we cannot physically remove the file /a/f
or the directory /a. So instead, we will create a whiteout in branch 0
named /.wh.a, masking out the name "a" from branch 1. Next, let's say we
try to create a directory named "a" as follows:
mkdir a
Because we have a whiteout for "a" already, Unionfs behaves as if "a"
doesn't exist, and thus will delete the whiteout and replace it with an
actual directory named "a".
The problem now is that if you try to "ls" in the union, Unionfs will
perform is normal directory name unification, for *all* directories named
"a" in all branches. This will cause the file /a/f from branch 1 to
re-appear in the union's namespace, which violates Unix semantics.
To avoid this problem, we have a different form of whiteouts for
directories, called "opaque directories" (same as BSD Union Mount does).
Whenever we replace a whiteout with a directory, that directory is marked as
opaque. In Unionfs 2.x, it means that we create a file named
/a/.wh.__dir_opaque in branch 0, after having created directory /a there.
When unionfs notices that a directory is opaque, it stops all namespace
operations (including merging readdir contents) at that opaque directory.
This prevents re-exposing names from masked out directories.
Duplicate Elimination:
======================
It is possible for files on different branches to have the same name.
Unionfs then has to select which instance of the file to show to the user.
Given the fact that each branch has a priority associated with it, the
simplest solution is to take the instance from the highest priority
(numerically lowest value) and "hide" the others.
Unlinking:
=========
Unlink operation on non-directory instances is optimized to remove the
maximum possible objects in case multiple underlying branches have the same
file name. The unlink operation will first try to delete file instances
from highest priority branch and then move further to delete from remaining
branches in order of their decreasing priority. Consider a case (F..D..F),
where F is a file and D is a directory of the same name; here, some
intermediate branch could have an empty directory instance with the same
name, so this operation also tries to delete this directory instance and
proceed further to delete from next possible lower priority branch. The
unionfs unlink operation will smoothly delete the files with same name from
all possible underlying branches. In case if some error occurs, it creates
whiteout in highest priority branch that will hide file instance in rest of
the branches. An error could occur either if an unlink operations in any of
the underlying branch failed or if a branch has no write permission.
This unlinking policy is known as "delete all" and it has the benefit of
overall reducing the number of inodes used by duplicate files, and further
reducing the total number of inodes consumed by whiteouts. The cost is of
extra processing, but testing shows this extra processing is well worth the
savings.
Copyup:
=======
When a change is made to the contents of a file's data or meta-data, they
have to be stored somewhere. The best way is to create a copy of the
original file on a branch that is writable, and then redirect the write
though to this copy. The copy must be made on a higher priority branch so
that lookup and readdir return this newer "version" of the file rather than
the original (see duplicate elimination).
An entire unionfs mount can be read-only or read-write. If it's read-only,
then none of the branches will be written to, even if some of the branches
are physically writeable. If the unionfs mount is read-write, then the
leftmost (highest priority) branch must be writeable (for copyup to take
place); the remaining branches can be any mix of read-write and read-only.
In a writeable mount, unionfs will create new files/dir in the leftmost
branch. If one tries to modify a file in a read-only branch/media, unionfs
will copyup the file to the leftmost branch and modify it there. If you try
to modify a file from a writeable branch which is not the leftmost branch,
then unionfs will modify it in that branch; this is useful if you, say,
unify differnet packages (e.g., apache, sendmail, ftpd, etc.) and you want
changes to specific package files to remain logically in the directory where
they came from.
Cache Coherency:
================
Unionfs users often want to be able to modify files and directories directly
on the lower branches, and have those changes be visible at the Unionfs
level. This means that data (e.g., pages) and meta-data (dentries, inodes,
open files, etc.) have to be synchronized between the upper and lower
layers. In other words, the newest changes from a layer below have to be
propagated to the Unionfs layer above. If the two layers are not in sync, a
cache incoherency ensues, which could lead to application failures and even
oopses. The Linux kernel, however, has a rather limited set of mechanisms
to ensure this inter-layer cache coherency---so Unionfs has to do most of
the hard work on its own.
Maintaining Invariants:
The way Unionfs ensures cache coherency is as follows. At each entry point
to a Unionfs file system method, we call a utility function to validate the
primary objects of this method. Generally, we call unionfs_file_revalidate
on open files, and __unionfs_d_revalidate_chain on dentries (which also
validates inodes). These utility functions check to see whether the upper
Unionfs object is in sync with any of the lower objects that it represents.
The checks we perform include whether the Unionfs superblock has a newer
generation number, or if any of the lower objects mtime's or ctime's are
newer. (Note: generation numbers change when branch-management commands are
issued, so in a way, maintaining cache coherency is also very important for
branch-management.) If indeed we determine that any Unionfs object is no
longer in sync with its lower counterparts, then we rebuild that object
similarly to how we do so for branch-management.
While rebuilding Unionfs's objects, we also purge any page mappings and
truncate inode pages (see fs/unionfs/dentry.c:purge_inode_data). This is to
ensure that Unionfs will re-get the newer data from the lower branches. We
perform this purging only if the Unionfs operation in question is a reading
operation; if Unionfs is performing a data writing operation (e.g., ->write,
->commit_write, etc.) then we do NOT flush the lower mappings/pages: this is
because (1) a self-deadlock could occur and (2) the upper Unionfs pages are
considered more authoritative anyway, as they are newer and will overwrite
any lower pages.
Unionfs maintains the following important invariant regarding mtime's,
ctime's, and atime's: the upper inode object's times are the max() of all of
the lower ones. For non-directory objects, there's only one object below,
so the mapping is simple; for directory objects, there could me multiple
lower objects and we have to sync up with the newest one of all the lower
ones. This invariant is important to maintain, especially for directories
(besides, we need this to be POSIX compliant). A union could comprise
multiple writable branches, each of which could change. If we don't reflect
the newest possible mtime/ctime, some applications could fail. For example,
NFSv2/v3 exports check for newer directory mtimes on the server to determine
if the client-side attribute cache should be purged.
To maintain these important invariants, of course, Unionfs carefully
synchronizes upper and lower times in various places. For example, if we
copy-up a file to a top-level branch, the parent directory where the file
was copied up to will now have a new mtime: so after a successful copy-up,
we sync up with the new top-level branch's parent directory mtime.
Implementation:
This cache-coherency implementation is efficient because it defers any
synchronizing between the upper and lower layers until absolutely needed.
Consider the example a common situation where users perform a lot of lower
changes, such as untarring a whole package. While these take place,
typically the user doesn't access the files via Unionfs; only after the
lower changes are done, does the user try to access the lower files. With
our cache-coherency implementation, the entirety of the changes to the lower
branches will not result in a single CPU cycle spent at the Unionfs level
until the user invokes a system call that goes through Unionfs.
We have considered two alternate cache-coherency designs. (1) Using the
dentry/inode notify functionality to register interest in finding out about
any lower changes. This is a somewhat limited and also a heavy-handed
approach which could result in many notifications to the Unionfs layer upon
each small change at the lower layer (imagine a file being modified multiple
times in rapid succession). (2) Rewriting the VFS to support explicit
callbacks from lower objects to upper objects. We began exploring such an
implementation, but found it to be very complicated--it would have resulted
in massive VFS/MM changes which are unlikely to be accepted by the LKML
community. We therefore believe that our current cache-coherency design and
implementation represent the best approach at this time.
Limitations:
Our implementation works in that as long as a user process will have caused
Unionfs to be called, directly or indirectly, even to just do
->d_revalidate; then we will have purged the current Unionfs data and the
process will see the new data. For example, a process that continually
re-reads the same file's data will see the NEW data as soon as the lower
file had changed, upon the next read(2) syscall (even if the file is still
open!) However, this doesn't work when the process re-reads the open file's
data via mmap(2) (unless the user unmaps/closes the file and remaps/reopens
it). Once we respond to ->readpage(s), then the kernel maps the page into
the process's address space and there doesn't appear to be a way to force
the kernel to invalidate those pages/mappings, and force the process to
re-issue ->readpage. If there's a way to invalidate active mappings and
force a ->readpage, let us know please (invalidate_inode_pages2 doesn't do
the trick).
Our current Unionfs code has to perform many file-revalidation calls. It
would be really nice if the VFS would export an optional file system hook
->file_revalidate (similarly to dentry->d_revalidate) that will be called
before each VFS op that has a "struct file" in it.
Certain file systems have micro-second granularity (or better) for inode
times, and asynchronous actions could cause those times to change with some
small delay. In such cases, Unionfs may see a changed inode time that only
differs by a tiny fraction of a second: such a change may be a false
positive indication that the lower object has changed, whereas if unionfs
waits a little longer, that false indication will not be seen. (These false
positives are harmless, because they would at most cause unionfs to
re-validate an object that may need no revalidation, and print a debugging
message that clutters the console/logs.) Therefore, to minimize the chances
of these situations, we delay the detection of changed times by a small
factor of a few seconds, called UNIONFS_MIN_CC_TIME (which defaults to 3
seconds, as does NFS). This means that we will detect the change, only a
couple of seconds later, if indeed the time change persists in the lower
file object. This delayed detection has an added performance benefit: we
reduce the number of times that unionfs has to revalidate objects, in case
there's a lot of concurrent activity on both the upper and lower objects,
for the same file(s). Lastly, this delayed time attribute detection is
similar to how NFS clients operate (e.g., acregmin).
Finally, there is no way currently in Linux to prevent lower directories
from being moved around (i.e., topology changes); there's no way to prevent
modifications to directory sub-trees of whole file systems which are mounted
read-write. It is therefore possible for in-flight operations in unionfs to
take place, while a lower directory is being moved around. Therefore, if
you try to, say, create a new file in a directory through unionfs, while the
directory is being moved around directly, then the new file may get created
in the new location where that directory was moved to. This is a somewhat
similar behaviour in NFS: an NFS client could be creating a new file while
th NFS server is moving th directory around; the file will get successfully
created in the new location. (The one exception in unionfs is that if the
branch is marked read-only by unionfs, then a copyup will take place.)
For more information, see <http://unionfs.filesystems.org/>.

28
Documentation/filesystems/unionfs/issues.txt Normal file
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@ -0,0 +1,28 @@
KNOWN Unionfs 2.x ISSUES:
=========================
1. Unionfs should not use lookup_one_len() on the underlying f/s as it
confuses NFSv4. Currently, unionfs_lookup() passes lookup intents to the
lower file-system, this eliminates part of the problem. The remaining
calls to lookup_one_len may need to be changed to pass an intent. We are
currently introducing VFS changes to fs/namei.c's do_path_lookup() to
allow proper file lookup and opening in stackable file systems.
2. Lockdep (a debugging feature) isn't aware of stacking, and so it
incorrectly complains about locking problems. The problem boils down to
this: Lockdep considers all objects of a certain type to be in the same
class, for example, all inodes. Lockdep doesn't like to see a lock held
on two inodes within the same task, and warns that it could lead to a
deadlock. However, stackable file systems do precisely that: they lock
an upper object, and then a lower object, in a strict order to avoid
locking problems; in addition, Unionfs, as a fan-out file system, may
have to lock several lower inodes. We are currently looking into Lockdep
to see how to make it aware of stackable file systems. For now, we
temporarily disable lockdep when calling vfs methods on lower objects,
but only for those places where lockdep complained. While this solution
may seem unclean, it is not without precedent: other places in the kernel
also do similar temporary disabling, of course after carefully having
checked that it is the right thing to do. Anyway, you get any warnings
from Lockdep, please report them to the Unionfs maintainers.
For more information, see <http://unionfs.filesystems.org/>.

31
Documentation/filesystems/unionfs/rename.txt Normal file
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@ -0,0 +1,31 @@
Rename is a complex beast. The following table shows which rename(2) operations
should succeed and which should fail.
o: success
E: error (either unionfs or vfs)
X: EXDEV
none = file does not exist
file = file is a file
dir = file is a empty directory
child= file is a non-empty directory
wh = file is a directory containing only whiteouts; this makes it logically
empty
none file dir child wh
file o o E E E
dir o E o E o
child X E X E X
wh o E o E o
Renaming directories:
=====================
Whenever a empty (either physically or logically) directory is being renamed,
the following sequence of events should take place:
1) Remove whiteouts from both source and destination directory
2) Rename source to destination
3) Make destination opaque to prevent anything under it from showing up

134
Documentation/filesystems/unionfs/usage.txt Normal file
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@ -0,0 +1,134 @@
Unionfs is a stackable unification file system, which can appear to merge
the contents of several directories (branches), while keeping their physical
content separate. Unionfs is useful for unified source tree management,
merged contents of split CD-ROM, merged separate software package
directories, data grids, and more. Unionfs allows any mix of read-only and
read-write branches, as well as insertion and deletion of branches anywhere
in the fan-out. To maintain Unix semantics, Unionfs handles elimination of
duplicates, partial-error conditions, and more.
GENERAL SYNTAX
==============
# mount -t unionfs -o <OPTIONS>,<BRANCH-OPTIONS> none MOUNTPOINT
OPTIONS can be any legal combination of:
- ro # mount file system read-only
- rw # mount file system read-write
- remount # remount the file system (see Branch Management below)
- incgen # increment generation no. (see Cache Consistency below)
BRANCH-OPTIONS can be either (1) a list of branches given to the "dirs="
option, or (2) a list of individual branch manipulation commands, combined
with the "remount" option, and is further described in the "Branch
Management" section below.
The syntax for the "dirs=" mount option is:
dirs=branch[=ro|=rw][:...]
The "dirs=" option takes a colon-delimited list of directories to compose
the union, with an optional branch mode for each of those directories.
Directories that come earlier (specified first, on the left) in the list
have a higher precedence than those which come later. Additionally,
read-only or read-write permissions of the branch can be specified by
appending =ro or =rw (default) to each directory. See the Copyup section in
concepts.txt, for a description of Unionfs's behavior when mixing read-only
and read-write branches and mounts.
Syntax:
dirs=/branch1[=ro|=rw]:/branch2[=ro|=rw]:...:/branchN[=ro|=rw]
Example:
dirs=/writable_branch=rw:/read-only_branch=ro
BRANCH MANAGEMENT
=================
Once you mount your union for the first time, using the "dirs=" option, you
can then change the union's overall mode or reconfigure the branches, using
the remount option, as follows.
To downgrade a union from read-write to read-only:
# mount -t unionfs -o remount,ro none MOUNTPOINT
To upgrade a union from read-only to read-write:
# mount -t unionfs -o remount,rw none MOUNTPOINT
To delete a branch /foo, regardless where it is in the current union:
# mount -t unionfs -o remount,del=/foo none MOUNTPOINT
To insert (add) a branch /foo before /bar:
# mount -t unionfs -o remount,add=/bar:/foo none MOUNTPOINT
To insert (add) a branch /foo (with the "rw" mode flag) before /bar:
# mount -t unionfs -o remount,add=/bar:/foo=rw none MOUNTPOINT
To insert (add) a branch /foo (in "rw" mode) at the very beginning (i.e., a
new highest-priority branch), you can use the above syntax, or use a short
hand version as follows:
# mount -t unionfs -o remount,add=/foo none MOUNTPOINT
To append a branch to the very end (new lowest-priority branch):
# mount -t unionfs -o remount,add=:/foo none MOUNTPOINT
To append a branch to the very end (new lowest-priority branch), in
read-only mode:
# mount -t unionfs -o remount,add=:/foo=ro none MOUNTPOINT
Finally, to change the mode of one existing branch, say /foo, from read-only
to read-write, and change /bar from read-write to read-only:
# mount -t unionfs -o remount,mode=/foo=rw,mode=/bar=ro none MOUNTPOINT
Note: in Unionfs 2.x, you cannot set the leftmost branch to readonly because
then Unionfs won't have any writable place for copyups to take place.
Moreover, the VFS can get confused when it tries to modify something in a
file system mounted read-write, but isn't permitted to write to it.
Instead, you should set the whole union as readonly, as described above.
If, however, you must set the leftmost branch as readonly, perhaps so you
can get a snapshot of it at a point in time, then you should insert a new
writable top-level branch, and mark the one you want as readonly. This can
be accomplished as follows, assuming that /foo is your current leftmost
branch:
# mount -t tmpfs -o size=NNN /new
# mount -t unionfs -o remount,add=/new,mode=/foo=ro none MOUNTPOINT
<do what you want safely in /foo>
# mount -t unionfs -o remount,del=/new,mode=/foo=rw none MOUNTPOINT
<check if there's anything in /new you want to preserve>
# umount /new
CACHE CONSISTENCY
=================
If you modify any file on any of the lower branches directly, while there is
a Unionfs 2.x mounted above any of those branches, you should tell Unionfs
to purge its caches and re-get the objects. To do that, you have to
increment the generation number of the superblock using the following
command:
# mount -t unionfs -o remount,incgen none MOUNTPOINT
Note that the older way of incrementing the generation number using an
ioctl, is no longer supported in Unionfs 2.0 and newer. Ioctls in general
are not encouraged. Plus, an ioctl is per-file concept, whereas the
generation number is a per-file-system concept. Worse, such an ioctl
requires an open file, which then has to be invalidated by the very nature
of the generation number increase (read: the old generation increase ioctl
was pretty racy).
For more information, see <http://unionfs.filesystems.org/>.

9
MAINTAINERS
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@ -9040,6 +9040,15 @@ F: drivers/cdrom/cdrom.c
F: include/linux/cdrom.h
F: include/uapi/linux/cdrom.h
UNION FILE SYSTEM
M: Erez Zadok <ezk@cs.sunysb.edu>
L: unionfs@filesystems.org
W: http://unionfs.filesystems.org/
T: git git://git.fsl.cs.sunysb.edu/unionfs-latest.git
S: Maintained
F: Documentation/filesystems/unionfs/
F: fs/unionfs/
UNIVERSAL FLASH STORAGE HOST CONTROLLER DRIVER
M: Vinayak Holikatti <vinholikatti@gmail.com>
M: Santosh Y <santoshsy@gmail.com>

1
fs/Kconfig
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@ -184,6 +184,7 @@ if MISC_FILESYSTEMS
source "fs/adfs/Kconfig"
source "fs/affs/Kconfig"
source "fs/ecryptfs/Kconfig"
source "fs/unionfs/Kconfig"
source "fs/hfs/Kconfig"
source "fs/hfsplus/Kconfig"
source "fs/befs/Kconfig"

1
fs/Makefile
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@ -81,6 +81,7 @@ obj-$(CONFIG_ISO9660_FS) += isofs/
obj-$(CONFIG_HFSPLUS_FS) += hfsplus/ # Before hfs to find wrapped HFS+
obj-$(CONFIG_HFS_FS) += hfs/
obj-$(CONFIG_ECRYPT_FS) += ecryptfs/
obj-$(CONFIG_UNION_FS) += unionfs/
obj-$(CONFIG_VXFS_FS) += freevxfs/
obj-$(CONFIG_NFS_FS) += nfs/
obj-$(CONFIG_EXPORTFS) += exportfs/

22
fs/splice.c
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@ -1111,8 +1111,8 @@ EXPORT_SYMBOL(generic_splice_sendpage);
/*
* Attempt to initiate a splice from pipe to file.
*/
static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
long vfs_splice_from(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags)
{
ssize_t (*splice_write)(struct pipe_inode_info *, struct file *,
loff_t *, size_t, unsigned int);
@ -1124,13 +1124,14 @@ static long do_splice_from(struct pipe_inode_info *pipe, struct file *out,
return splice_write(pipe, out, ppos, len, flags);
}
EXPORT_SYMBOL_GPL(vfs_splice_from);
/*
* Attempt to initiate a splice from a file to a pipe.
*/
static long do_splice_to(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
long vfs_splice_to(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
ssize_t (*splice_read)(struct file *, loff_t *,
struct pipe_inode_info *, size_t, unsigned int);
@ -1150,6 +1151,7 @@ static long do_splice_to(struct file *in, loff_t *ppos,
return splice_read(in, ppos, pipe, len, flags);
}
EXPORT_SYMBOL_GPL(vfs_splice_to);
/**
* splice_direct_to_actor - splices data directly between two non-pipes
@ -1219,7 +1221,7 @@ ssize_t splice_direct_to_actor(struct file *in, struct splice_desc *sd,
size_t read_len;
loff_t pos = sd->pos, prev_pos = pos;
ret = do_splice_to(in, &pos, pipe, len, flags);
ret = vfs_splice_to(in, &pos, pipe, len, flags);
if (unlikely(ret <= 0))
goto out_release;
@ -1278,8 +1280,8 @@ static int direct_splice_actor(struct pipe_inode_info *pipe,
{
struct file *file = sd->u.file;
return do_splice_from(pipe, file, sd->opos, sd->total_len,
sd->flags);
return vfs_splice_from(pipe, file, sd->opos, sd->total_len,
sd->flags);
}
/**
@ -1387,7 +1389,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
return ret;
file_start_write(out);
ret = do_splice_from(ipipe, out, &offset, len, flags);
ret = vfs_splice_from(ipipe, out, &offset, len, flags);
file_end_write(out);
if (!off_out)
@ -1410,7 +1412,7 @@ static long do_splice(struct file *in, loff_t __user *off_in,
offset = in->f_pos;
}
ret = do_splice_to(in, &offset, opipe, len, flags);
ret = vfs_splice_to(in, &offset, opipe, len, flags);
if (!off_in)
in->f_pos = offset;

23
fs/unionfs/Kconfig Normal file
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@ -0,0 +1,23 @@
config UNION_FS
tristate "Union file system"
help
Unionfs is a stackable unification file system, which appears to
merge the contents of several directories (branches), while keeping
their physical content separate.
See <http://unionfs.filesystems.org> for details
config UNION_FS_XATTR
bool "Unionfs extended attributes"
depends on UNION_FS
help
Extended attributes are name:value pairs associated with inodes by
the kernel or by users (see the attr(5) manual page).
If unsure, say N.
config UNION_FS_DEBUG
bool "Debug Unionfs"
depends on UNION_FS
help
If you say Y here, you can turn on debugging output from Unionfs.

17
fs/unionfs/Makefile Normal file
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@ -0,0 +1,17 @@
UNIONFS_VERSION="2.6 (for 3.14.17)"
EXTRA_CFLAGS += -DUNIONFS_VERSION=\"$(UNIONFS_VERSION)\"
obj-$(CONFIG_UNION_FS) += unionfs.o
unionfs-y := subr.o dentry.o file.o inode.o main.o super.o \
rdstate.o copyup.o dirhelper.o rename.o unlink.o \
lookup.o commonfops.o dirfops.o sioq.o mmap.o whiteout.o
unionfs-$(CONFIG_UNION_FS_XATTR) += xattr.o
unionfs-$(CONFIG_UNION_FS_DEBUG) += debug.o
ifeq ($(CONFIG_UNION_FS_DEBUG),y)
EXTRA_CFLAGS += -DDEBUG
endif

957
fs/unionfs/commonfops.c Normal file
View File

@ -0,0 +1,957 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
#define __NFDBITS (8 * sizeof(unsigned long))
#define __FDSET_LONGS (__FD_SETSIZE/__NFDBITS)
static inline void __FD_SET(unsigned long __fd, __kernel_fd_set *__fdsetp)
{
unsigned long __tmp = __fd / __NFDBITS;
unsigned long __rem = __fd % __NFDBITS;
__fdsetp->fds_bits[__tmp] |= (1UL<<__rem);
}
static inline void __FD_ZERO(__kernel_fd_set *__p)
{
unsigned long *__tmp = __p->fds_bits;
int __i;
if (__builtin_constant_p(__FDSET_LONGS)) {
switch (__FDSET_LONGS) {
case 16:
__tmp[ 0] = 0; __tmp[ 1] = 0;
__tmp[ 2] = 0; __tmp[ 3] = 0;
__tmp[ 4] = 0; __tmp[ 5] = 0;
__tmp[ 6] = 0; __tmp[ 7] = 0;
__tmp[ 8] = 0; __tmp[ 9] = 0;
__tmp[10] = 0; __tmp[11] = 0;
__tmp[12] = 0; __tmp[13] = 0;
__tmp[14] = 0; __tmp[15] = 0;
return;
case 8:
__tmp[ 0] = 0; __tmp[ 1] = 0;
__tmp[ 2] = 0; __tmp[ 3] = 0;
__tmp[ 4] = 0; __tmp[ 5] = 0;
__tmp[ 6] = 0; __tmp[ 7] = 0;
return;
case 4:
__tmp[ 0] = 0; __tmp[ 1] = 0;
__tmp[ 2] = 0; __tmp[ 3] = 0;
return;
}
}
__i = __FDSET_LONGS;
while (__i) {
__i--;
*__tmp = 0;
__tmp++;
}
}
/*
* 1) Copyup the file
* 2) Rename the file to '.unionfs<original inode#><counter>' - obviously
* stolen from NFS's silly rename
*/
static int copyup_deleted_file(struct file *file, struct dentry *dentry,
struct dentry *parent, int bstart, int bindex)
{
static unsigned int counter;
const int i_inosize = sizeof(dentry->d_inode->i_ino) * 2;
const int countersize = sizeof(counter) * 2;
const int nlen = sizeof(".unionfs") + i_inosize + countersize - 1;
char name[nlen + 1];
int err;
struct dentry *tmp_dentry = NULL;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry = NULL;
lower_dentry = unionfs_lower_dentry_idx(dentry, bstart);
sprintf(name, ".unionfs%*.*lx",
i_inosize, i_inosize, lower_dentry->d_inode->i_ino);
/*
* Loop, looking for an unused temp name to copyup to.
*
* It's somewhat silly that we look for a free temp tmp name in the
* source branch (bstart) instead of the dest branch (bindex), where
* the final name will be created. We _will_ catch it if somehow
* the name exists in the dest branch, but it'd be nice to catch it
* sooner than later.
*/
retry:
tmp_dentry = NULL;
do {
char *suffix = name + nlen - countersize;
dput(tmp_dentry);
counter++;
sprintf(suffix, "%*.*x", countersize, countersize, counter);
pr_debug("unionfs: trying to rename %pd to %s\n",
dentry, name);
tmp_dentry = lookup_lck_len(name, lower_dentry->d_parent,
nlen);
if (IS_ERR(tmp_dentry)) {
err = PTR_ERR(tmp_dentry);
goto out;
}
} while (tmp_dentry->d_inode != NULL); /* need negative dentry */
dput(tmp_dentry);
err = copyup_named_file(parent->d_inode, file, name, bstart, bindex,
i_size_read(file_inode(file)));
if (err) {
if (unlikely(err == -EEXIST))
goto retry;
goto out;
}
/* bring it to the same state as an unlinked file */
lower_dentry = unionfs_lower_dentry_idx(dentry, dbstart(dentry));
if (!unionfs_lower_inode_idx(dentry->d_inode, bindex)) {
atomic_inc(&lower_dentry->d_inode->i_count);
unionfs_set_lower_inode_idx(dentry->d_inode, bindex,
lower_dentry->d_inode);
}
lower_dir_dentry = lock_parent(lower_dentry);
err = vfs_unlink(lower_dir_dentry->d_inode, lower_dentry, NULL);
unlock_dir(lower_dir_dentry);
out:
if (!err)
unionfs_check_dentry(dentry);
return err;
}
/*
* put all references held by upper struct file and free lower file pointer
* array
*/
static void cleanup_file(struct file *file)
{
int bindex, bstart, bend;
struct file **lower_files;
struct file *lower_file;
struct super_block *sb = file->f_path.dentry->d_sb;
lower_files = UNIONFS_F(file)->lower_files;
bstart = fbstart(file);
bend = fbend(file);
for (bindex = bstart; bindex <= bend; bindex++) {
int i; /* holds (possibly) updated branch index */
int old_bid;
lower_file = unionfs_lower_file_idx(file, bindex);
if (!lower_file)
continue;
/*
* Find new index of matching branch with an open
* file, since branches could have been added or
* deleted causing the one with open files to shift.
*/
old_bid = UNIONFS_F(file)->saved_branch_ids[bindex];
i = branch_id_to_idx(sb, old_bid);
if (unlikely(i < 0)) {
printk(KERN_ERR "unionfs: no superblock for "
"file %p\n", file);
continue;
}
/* decrement count of open files */
branchput(sb, i);
/*
* fput will perform an mntput for us on the correct branch.
* Although we're using the file's old branch configuration,
* bindex, which is the old index, correctly points to the
* right branch in the file's branch list. In other words,
* we're going to mntput the correct branch even if branches
* have been added/removed.
*/
fput(lower_file);
UNIONFS_F(file)->lower_files[bindex] = NULL;
UNIONFS_F(file)->saved_branch_ids[bindex] = -1;
}
UNIONFS_F(file)->lower_files = NULL;
kfree(lower_files);
kfree(UNIONFS_F(file)->saved_branch_ids);
/* set to NULL because caller needs to know if to kfree on error */
UNIONFS_F(file)->saved_branch_ids = NULL;
}
/* open all lower files for a given file */
static int open_all_files(struct file *file)
{
int bindex, bstart, bend, err = 0;
struct file *lower_file;
struct dentry *lower_dentry;
struct dentry *dentry = file->f_path.dentry;
struct super_block *sb = dentry->d_sb;
struct path path;
bstart = dbstart(dentry);
bend = dbend(dentry);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
dget(lower_dentry);
unionfs_mntget(dentry, bindex);
branchget(sb, bindex);
path.dentry = lower_dentry;
path.mnt = unionfs_lower_mnt_idx(dentry, bindex);
lower_file = dentry_open(&path, file->f_flags, current_cred());
path_put(&path);
if (IS_ERR(lower_file)) {
branchput(sb, bindex);
err = PTR_ERR(lower_file);
goto out;
} else {
unionfs_set_lower_file_idx(file, bindex, lower_file);
}
}
out:
return err;
}
/* open the highest priority file for a given upper file */
static int open_highest_file(struct file *file, bool willwrite)
{
int bindex, bstart, bend, err = 0;
struct file *lower_file;
struct dentry *lower_dentry;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent = dget_parent(dentry);
struct inode *parent_inode = parent->d_inode;
struct super_block *sb = dentry->d_sb;
struct path path;
bstart = dbstart(dentry);
bend = dbend(dentry);
lower_dentry = unionfs_lower_dentry(dentry);
if (willwrite && IS_WRITE_FLAG(file->f_flags) && is_robranch(dentry)) {
for (bindex = bstart - 1; bindex >= 0; bindex--) {
err = copyup_file(parent_inode, file, bstart, bindex,
i_size_read(dentry->d_inode));
if (!err)
break;
}
atomic_set(&UNIONFS_F(file)->generation,
atomic_read(&UNIONFS_I(dentry->d_inode)->
generation));
goto out;
}
dget(lower_dentry);
unionfs_mntget(dentry, bstart);
path.dentry = lower_dentry;
path.mnt = unionfs_lower_mnt_idx(dentry, bstart);
lower_file = dentry_open(&path, file->f_flags, current_cred());
path_put(&path);
if (IS_ERR(lower_file)) {
err = PTR_ERR(lower_file);
goto out;
}
branchget(sb, bstart);
unionfs_set_lower_file(file, lower_file);
/* Fix up the position. */
lower_file->f_pos = file->f_pos;
memcpy(&lower_file->f_ra, &file->f_ra, sizeof(struct file_ra_state));
out:
dput(parent);
return err;
}
/* perform a delayed copyup of a read-write file on a read-only branch */
static int do_delayed_copyup(struct file *file, struct dentry *parent)
{
int bindex, bstart, bend, err = 0;
struct dentry *dentry = file->f_path.dentry;
struct inode *parent_inode = parent->d_inode;
bstart = fbstart(file);
bend = fbend(file);
BUG_ON(!S_ISREG(dentry->d_inode->i_mode));
unionfs_check_file(file);
for (bindex = bstart - 1; bindex >= 0; bindex--) {
if (!d_deleted(dentry))
err = copyup_file(parent_inode, file, bstart,
bindex,
i_size_read(dentry->d_inode));
else
err = copyup_deleted_file(file, dentry, parent,
bstart, bindex);
/* if succeeded, set lower open-file flags and break */
if (!err) {
struct file *lower_file;
lower_file = unionfs_lower_file_idx(file, bindex);
lower_file->f_flags = file->f_flags;
break;
}
}
if (err || (bstart <= fbstart(file)))
goto out;
bend = fbend(file);
for (bindex = bstart; bindex <= bend; bindex++) {
if (unionfs_lower_file_idx(file, bindex)) {
branchput(dentry->d_sb, bindex);
fput(unionfs_lower_file_idx(file, bindex));
unionfs_set_lower_file_idx(file, bindex, NULL);
}
}
path_put_lowers(dentry, bstart, bend, false);
iput_lowers(dentry->d_inode, bstart, bend, false);
/* for reg file, we only open it "once" */
fbend(file) = fbstart(file);
dbend(dentry) = dbstart(dentry);
ibend(dentry->d_inode) = ibstart(dentry->d_inode);
out:
unionfs_check_file(file);
return err;
}
/*
* Helper function for unionfs_file_revalidate/locked.
* Expects dentry/parent to be locked already, and revalidated.
*/
static int __unionfs_file_revalidate(struct file *file, struct dentry *dentry,
struct dentry *parent,
struct super_block *sb, int sbgen,
int dgen, bool willwrite)
{
int fgen;
int bstart, bend, orig_brid;
int size;
int err = 0;
fgen = atomic_read(&UNIONFS_F(file)->generation);
/*
* There are two cases we are interested in. The first is if the
* generation is lower than the super-block. The second is if
* someone has copied up this file from underneath us, we also need
* to refresh things.
*/
if (d_deleted(dentry) ||
(sbgen <= fgen &&
dbstart(dentry) == fbstart(file) &&
unionfs_lower_file(file)))
goto out_may_copyup;
/* save orig branch ID */
orig_brid = UNIONFS_F(file)->saved_branch_ids[fbstart(file)];
/* First we throw out the existing files. */
cleanup_file(file);
/* Now we reopen the file(s) as in unionfs_open. */
bstart = fbstart(file) = dbstart(dentry);
bend = fbend(file) = dbend(dentry);
size = sizeof(struct file *) * sbmax(sb);
UNIONFS_F(file)->lower_files = kzalloc(size, GFP_KERNEL);
if (unlikely(!UNIONFS_F(file)->lower_files)) {
err = -ENOMEM;
goto out;
}
size = sizeof(int) * sbmax(sb);
UNIONFS_F(file)->saved_branch_ids = kzalloc(size, GFP_KERNEL);
if (unlikely(!UNIONFS_F(file)->saved_branch_ids)) {
err = -ENOMEM;
goto out;
}
if (S_ISDIR(dentry->d_inode->i_mode)) {
/* We need to open all the files. */
err = open_all_files(file);
if (err)
goto out;
} else {
int new_brid;
/* We only open the highest priority branch. */
err = open_highest_file(file, willwrite);
if (err)
goto out;
new_brid = UNIONFS_F(file)->saved_branch_ids[fbstart(file)];
if (unlikely(new_brid != orig_brid && sbgen > fgen)) {
/*
* If we re-opened the file on a different branch
* than the original one, and this was due to a new
* branch inserted, then update the mnt counts of
* the old and new branches accordingly.
*/
unionfs_mntget(dentry, bstart);
unionfs_mntput(sb->s_root,
branch_id_to_idx(sb, orig_brid));
}
/* regular files have only one open lower file */
fbend(file) = fbstart(file);
}
atomic_set(&UNIONFS_F(file)->generation,
atomic_read(&UNIONFS_I(dentry->d_inode)->generation));
out_may_copyup:
/* Copyup on the first write to a file on a readonly branch. */
if (willwrite && IS_WRITE_FLAG(file->f_flags) &&
!IS_WRITE_FLAG(unionfs_lower_file(file)->f_flags) &&
is_robranch(dentry)) {
pr_debug("unionfs: do delay copyup of \"%pd\"\n", dentry);
err = do_delayed_copyup(file, parent);
/* regular files have only one open lower file */
if (!err && !S_ISDIR(dentry->d_inode->i_mode))
fbend(file) = fbstart(file);
}
out:
if (err) {
kfree(UNIONFS_F(file)->lower_files);
kfree(UNIONFS_F(file)->saved_branch_ids);
}
return err;
}
/*
* Revalidate the struct file
* @file: file to revalidate
* @parent: parent dentry (locked by caller)
* @willwrite: true if caller may cause changes to the file; false otherwise.
* Caller must lock/unlock dentry's branch configuration.
*/
int unionfs_file_revalidate(struct file *file, struct dentry *parent,
bool willwrite)
{
struct super_block *sb;
struct dentry *dentry;
int sbgen, dgen;
int err = 0;
dentry = file->f_path.dentry;
sb = dentry->d_sb;
verify_locked(dentry);
verify_locked(parent);
/*
* First revalidate the dentry inside struct file,
* but not unhashed dentries.
*/
if (!d_deleted(dentry) &&
!__unionfs_d_revalidate(dentry, parent, willwrite, 0)) {
err = -ESTALE;
goto out;
}
sbgen = atomic_read(&UNIONFS_SB(sb)->generation);
dgen = atomic_read(&UNIONFS_D(dentry)->generation);
if (unlikely(sbgen > dgen)) { /* XXX: should never happen */
pr_debug("unionfs: failed to revalidate dentry (%pd)\n",
dentry);
err = -ESTALE;
goto out;
}
err = __unionfs_file_revalidate(file, dentry, parent, sb,
sbgen, dgen, willwrite);
out:
return err;
}
/* unionfs_open helper function: open a directory */
static int __open_dir(struct inode *inode, struct file *file,
struct dentry *parent)
{
struct dentry *lower_dentry;
struct file *lower_file;
int bindex, bstart, bend;
struct vfsmount *lower_mnt;
struct dentry *dentry = file->f_path.dentry;
struct path path;
bstart = fbstart(file) = dbstart(dentry);
bend = fbend(file) = dbend(dentry);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry =
unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
dget(lower_dentry);
lower_mnt = unionfs_mntget(dentry, bindex);
if (!lower_mnt)
lower_mnt = unionfs_mntget(parent, bindex);
path.dentry = lower_dentry;
path.mnt = lower_mnt;
lower_file = dentry_open(&path, file->f_flags, current_cred());
path_put(&path);
if (IS_ERR(lower_file))
return PTR_ERR(lower_file);
unionfs_set_lower_file_idx(file, bindex, lower_file);
if (!unionfs_lower_mnt_idx(dentry, bindex))
unionfs_set_lower_mnt_idx(dentry, bindex, lower_mnt);
/*
* The branchget goes after the open, because otherwise
* we would miss the reference on release.
*/
branchget(inode->i_sb, bindex);
}
return 0;
}
/* unionfs_open helper function: open a file */
static int __open_file(struct inode *inode, struct file *file,
struct dentry *parent)
{
struct dentry *lower_dentry;
struct file *lower_file;
int lower_flags;
int bindex, bstart, bend;
struct dentry *dentry = file->f_path.dentry;
struct vfsmount *lower_mnt;
struct path path;
lower_dentry = unionfs_lower_dentry(dentry);
lower_flags = file->f_flags;
bstart = fbstart(file) = dbstart(dentry);
bend = fbend(file) = dbend(dentry);
/*
* check for the permission for lower file. If the error is
* COPYUP_ERR, copyup the file.
*/
if (lower_dentry->d_inode && is_robranch(dentry)) {
/*
* if the open will change the file, copy it up otherwise
* defer it.
*/
if (lower_flags & O_TRUNC) {
int size = 0;
int err = -EROFS;
/* copyup the file */
for (bindex = bstart - 1; bindex >= 0; bindex--) {
err = copyup_file(parent->d_inode, file,
bstart, bindex, size);
if (!err) {
/* only one regular file open */
fbend(file) = fbstart(file);
break;
}
}
return err;
} else {
/*
* turn off writeable flags, to force delayed copyup
* by caller.
*/
lower_flags &= ~(OPEN_WRITE_FLAGS);
}
}
dget(lower_dentry);
/*
* dentry_open used to decrement mnt refcnt if err.
* otherwise fput() will do an mntput() for us upon file close.
*/
lower_mnt = unionfs_mntget(dentry, bstart);
path.dentry = lower_dentry;
path.mnt = lower_mnt;
lower_file = dentry_open(&path, lower_flags, current_cred());
path_put(&path);
if (IS_ERR(lower_file))
return PTR_ERR(lower_file);
unionfs_set_lower_file(file, lower_file);
branchget(inode->i_sb, bstart);
return 0;
}
int unionfs_open(struct inode *inode, struct file *file)
{
int err = 0;
struct file *lower_file = NULL;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
int bindex = 0, bstart = 0, bend = 0;
int size;
int valid = 0;
unionfs_read_lock(inode->i_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
/* don't open unhashed/deleted files */
if (d_deleted(dentry)) {
err = -ENOENT;
goto out_nofree;
}
/* XXX: should I change 'false' below to the 'willwrite' flag? */
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out_nofree;
}
file->private_data =
kzalloc(sizeof(struct unionfs_file_info), GFP_KERNEL);
if (unlikely(!UNIONFS_F(file))) {
err = -ENOMEM;
goto out_nofree;
}
fbstart(file) = -1;
fbend(file) = -1;
atomic_set(&UNIONFS_F(file)->generation,
atomic_read(&UNIONFS_I(inode)->generation));
size = sizeof(struct file *) * sbmax(inode->i_sb);
UNIONFS_F(file)->lower_files = kzalloc(size, GFP_KERNEL);
if (unlikely(!UNIONFS_F(file)->lower_files)) {
err = -ENOMEM;
goto out;
}
size = sizeof(int) * sbmax(inode->i_sb);
UNIONFS_F(file)->saved_branch_ids = kzalloc(size, GFP_KERNEL);
if (unlikely(!UNIONFS_F(file)->saved_branch_ids)) {
err = -ENOMEM;
goto out;
}
bstart = fbstart(file) = dbstart(dentry);
bend = fbend(file) = dbend(dentry);
/*
* open all directories and make the unionfs file struct point to
* these lower file structs
*/
if (S_ISDIR(inode->i_mode))
err = __open_dir(inode, file, parent); /* open a dir */
else
err = __open_file(inode, file, parent); /* open a file */
/* freeing the allocated resources, and fput the opened files */
if (err) {
for (bindex = bstart; bindex <= bend; bindex++) {
lower_file = unionfs_lower_file_idx(file, bindex);
if (!lower_file)
continue;
branchput(dentry->d_sb, bindex);
/* fput calls dput for lower_dentry */
fput(lower_file);
}
}
out:
if (err) {
kfree(UNIONFS_F(file)->lower_files);
kfree(UNIONFS_F(file)->saved_branch_ids);
kfree(UNIONFS_F(file));
}
out_nofree:
if (!err) {
unionfs_postcopyup_setmnt(dentry);
unionfs_copy_attr_times(inode);
unionfs_check_file(file);
unionfs_check_inode(inode);
}
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(inode->i_sb);
return err;
}
/*
* release all lower object references & free the file info structure
*
* No need to grab sb info's rwsem.
*/
int unionfs_file_release(struct inode *inode, struct file *file)
{
struct file *lower_file = NULL;
struct unionfs_file_info *fileinfo;
struct unionfs_inode_info *inodeinfo;
struct super_block *sb = inode->i_sb;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
int bindex, bstart, bend;
int err = 0;
/*
* Since mm/memory.c:might_fault() (under PROVE_LOCKING) was
* modified in 2.6.29-rc1 to call might_lock_read on mmap_sem, this
* has been causing false positives in file system stacking layers.
* In particular, our ->mmap is called after sys_mmap2 already holds
* mmap_sem, then we lock our own mutexes; but earlier, it's
* possible for lockdep to have locked our mutexes first, and then
* we call a lower ->readdir which could call might_fault. The
* different ordering of the locks is what lockdep complains about
* -- unnecessarily. Therefore, we have no choice but to tell
* lockdep to temporarily turn off lockdep here. Note: the comments
* inside might_sleep also suggest that it would have been
* nicer to only annotate paths that needs that might_lock_read.
*/
lockdep_off();
unionfs_read_lock(sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
/*
* We try to revalidate, but the VFS ignores return return values
* from file->release, so we must always try to succeed here,
* including to do the kfree and dput below. So if revalidation
* failed, all we can do is print some message and keep going.
*/
err = unionfs_file_revalidate(file, parent,
UNIONFS_F(file)->wrote_to_file);
if (!err)
unionfs_check_file(file);
fileinfo = UNIONFS_F(file);
BUG_ON(file_inode(file) != inode);
inodeinfo = UNIONFS_I(inode);
/* fput all the lower files */
bstart = fbstart(file);
bend = fbend(file);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_file = unionfs_lower_file_idx(file, bindex);
if (lower_file) {
unionfs_set_lower_file_idx(file, bindex, NULL);
fput(lower_file);
branchput(sb, bindex);
}
/* if there are no more refs to the dentry, dput it */
if (d_deleted(dentry)) {
dput(unionfs_lower_dentry_idx(dentry, bindex));
unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
}
}
kfree(fileinfo->lower_files);
kfree(fileinfo->saved_branch_ids);
if (fileinfo->rdstate) {
fileinfo->rdstate->access = jiffies;
spin_lock(&inodeinfo->rdlock);
inodeinfo->rdcount++;
list_add_tail(&fileinfo->rdstate->cache,
&inodeinfo->readdircache);
mark_inode_dirty(inode);
spin_unlock(&inodeinfo->rdlock);
fileinfo->rdstate = NULL;
}
kfree(fileinfo);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(sb);
lockdep_on();
return err;
}
/* pass the ioctl to the lower fs */
static long do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct file *lower_file;
int err;
lower_file = unionfs_lower_file(file);
err = -ENOTTY;
if (!lower_file || !lower_file->f_op)
goto out;
if (lower_file->f_op->unlocked_ioctl) {
err = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
#ifdef CONFIG_COMPAT
} else if (lower_file->f_op->compat_ioctl) {
err = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
#endif
}
out:
return err;
}
/*
* return to user-space the branch indices containing the file in question
*
* We use fd_set and therefore we are limited to the number of the branches
* to FD_SETSIZE, which is currently 1024 - plenty for most people
*/
static int unionfs_ioctl_queryfile(struct file *file, struct dentry *parent,
unsigned int cmd, unsigned long arg)
{
int err = 0;
fd_set branchlist;
int bstart = 0, bend = 0, bindex = 0;
int orig_bstart, orig_bend;
struct dentry *dentry, *lower_dentry;
struct vfsmount *mnt;
dentry = file->f_path.dentry;
orig_bstart = dbstart(dentry);
orig_bend = dbend(dentry);
err = unionfs_partial_lookup(dentry, parent);
if (err)
goto out;
bstart = dbstart(dentry);
bend = dbend(dentry);
__FD_ZERO(&branchlist);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
if (likely(lower_dentry->d_inode))
__FD_SET(bindex, &branchlist);
/* purge any lower objects after partial_lookup */
if (bindex < orig_bstart || bindex > orig_bend) {
dput(lower_dentry);
unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
iput(unionfs_lower_inode_idx(dentry->d_inode, bindex));
unionfs_set_lower_inode_idx(dentry->d_inode, bindex,
NULL);
mnt = unionfs_lower_mnt_idx(dentry, bindex);
if (!mnt)
continue;
unionfs_mntput(dentry, bindex);
unionfs_set_lower_mnt_idx(dentry, bindex, NULL);
}
}
/* restore original dentry's offsets */
dbstart(dentry) = orig_bstart;
dbend(dentry) = orig_bend;
ibstart(dentry->d_inode) = orig_bstart;
ibend(dentry->d_inode) = orig_bend;
err = copy_to_user((void __user *)arg, &branchlist, sizeof(fd_set));
if (unlikely(err))
err = -EFAULT;
out:
return err < 0 ? err : bend;
}
long unionfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
long err;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
/* check if asked for local commands */
switch (cmd) {
case UNIONFS_IOCTL_INCGEN:
/* Increment the superblock generation count */
pr_info("unionfs: incgen ioctl deprecated; "
"use \"-o remount,incgen\"\n");
err = -ENOSYS;
break;
case UNIONFS_IOCTL_QUERYFILE:
/* Return list of branches containing the given file */
err = unionfs_ioctl_queryfile(file, parent, cmd, arg);
break;
default:
/* pass the ioctl down */
err = do_ioctl(file, cmd, arg);
break;
}
out:
unionfs_check_file(file);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
int unionfs_flush(struct file *file, fl_owner_t id)
{
int err = 0;
struct file *lower_file = NULL;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
int bindex, bstart, bend;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent,
UNIONFS_F(file)->wrote_to_file);
if (unlikely(err))
goto out;
unionfs_check_file(file);
bstart = fbstart(file);
bend = fbend(file);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_file = unionfs_lower_file_idx(file, bindex);
if (lower_file && lower_file->f_op &&
lower_file->f_op->flush) {
err = lower_file->f_op->flush(lower_file, id);
if (err)
goto out;
}
}
out:
if (!err)
unionfs_check_file(file);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}

899
fs/unionfs/copyup.c Normal file
View File

@ -0,0 +1,899 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* For detailed explanation of copyup see:
* Documentation/filesystems/unionfs/concepts.txt
*/
#ifdef CONFIG_UNION_FS_XATTR
/* copyup all extended attrs for a given dentry */
static int copyup_xattrs(struct dentry *old_lower_dentry,
struct dentry *new_lower_dentry)
{
int err = 0;
ssize_t list_size = -1;
char *name_list = NULL;
char *attr_value = NULL;
char *name_list_buf = NULL;
/* query the actual size of the xattr list */
list_size = vfs_listxattr(old_lower_dentry, NULL, 0);
if (list_size <= 0) {
err = list_size;
goto out;
}
/* allocate space for the actual list */
name_list = unionfs_xattr_alloc(list_size + 1, XATTR_LIST_MAX);
if (unlikely(!name_list || IS_ERR(name_list))) {
err = PTR_ERR(name_list);
goto out;
}
name_list_buf = name_list; /* save for kfree at end */
/* now get the actual xattr list of the source file */
list_size = vfs_listxattr(old_lower_dentry, name_list, list_size);
if (list_size <= 0) {
err = list_size;
goto out;
}
/* allocate space to hold each xattr's value */
attr_value = unionfs_xattr_alloc(XATTR_SIZE_MAX, XATTR_SIZE_MAX);
if (unlikely(!attr_value || IS_ERR(attr_value))) {
err = PTR_ERR(name_list);
goto out;
}
/* in a loop, get and set each xattr from src to dst file */
while (*name_list) {
ssize_t size;
/* Lock here since vfs_getxattr doesn't lock for us */
mutex_lock(&old_lower_dentry->d_inode->i_mutex);
size = vfs_getxattr(old_lower_dentry, name_list,
attr_value, XATTR_SIZE_MAX);
mutex_unlock(&old_lower_dentry->d_inode->i_mutex);
if (size < 0) {
err = size;
goto out;
}
if (size > XATTR_SIZE_MAX) {
err = -E2BIG;
goto out;
}
/* Don't lock here since vfs_setxattr does it for us. */
err = vfs_setxattr(new_lower_dentry, name_list, attr_value,
size, 0);
/*
* Selinux depends on "security.*" xattrs, so to maintain
* the security of copied-up files, if Selinux is active,
* then we must copy these xattrs as well. So we need to
* temporarily get FOWNER privileges.
* XXX: move entire copyup code to SIOQ.
*/
if (err == -EPERM && !capable(CAP_FOWNER)) {
const struct cred *old_creds;
struct cred *new_creds;
new_creds = prepare_creds();
if (unlikely(!new_creds)) {
err = -ENOMEM;
goto out;
}
cap_raise(new_creds->cap_effective, CAP_FOWNER);
old_creds = override_creds(new_creds);
err = vfs_setxattr(new_lower_dentry, name_list,
attr_value, size, 0);
revert_creds(old_creds);
}
if (err < 0)
goto out;
name_list += strlen(name_list) + 1;
}
out:
unionfs_xattr_kfree(name_list_buf);
unionfs_xattr_kfree(attr_value);
/* Ignore if xattr isn't supported */
if (err == -ENOTSUPP || err == -EOPNOTSUPP)
err = 0;
return err;
}
#endif /* CONFIG_UNION_FS_XATTR */
/*
* Determine the mode based on the copyup flags, and the existing dentry.
*
* Handle file systems which may not support certain options. For example
* jffs2 doesn't allow one to chmod a symlink. So we ignore such harmless
* errors, rather than propagating them up, which results in copyup errors
* and errors returned back to users.
*/
static int copyup_permissions(struct super_block *sb,
struct dentry *old_lower_dentry,
struct dentry *new_lower_dentry)
{
struct inode *i = old_lower_dentry->d_inode;
struct iattr newattrs;
int err;
newattrs.ia_atime = i->i_atime;
newattrs.ia_mtime = i->i_mtime;
newattrs.ia_ctime = i->i_ctime;
newattrs.ia_gid = i->i_gid;
newattrs.ia_uid = i->i_uid;
newattrs.ia_valid = ATTR_CTIME | ATTR_ATIME | ATTR_MTIME |
ATTR_ATIME_SET | ATTR_MTIME_SET | ATTR_FORCE |
ATTR_GID | ATTR_UID;
mutex_lock(&new_lower_dentry->d_inode->i_mutex);
err = notify_change(new_lower_dentry, &newattrs, NULL);
if (err)
goto out;
/* now try to change the mode and ignore EOPNOTSUPP on symlinks */
newattrs.ia_mode = i->i_mode;
newattrs.ia_valid = ATTR_MODE | ATTR_FORCE;
err = notify_change(new_lower_dentry, &newattrs, NULL);
if (err == -EOPNOTSUPP &&
S_ISLNK(new_lower_dentry->d_inode->i_mode)) {
printk(KERN_WARNING
"unionfs: changing \"%pd\" symlink mode unsupported\n",
new_lower_dentry);
err = 0;
}
out:
mutex_unlock(&new_lower_dentry->d_inode->i_mutex);
return err;
}
/*
* create the new device/file/directory - use copyup_permission to copyup
* times, and mode
*
* if the object being copied up is a regular file, the file is only created,
* the contents have to be copied up separately
*/
static int __copyup_ndentry(struct dentry *old_lower_dentry,
struct dentry *new_lower_dentry,
struct dentry *new_lower_parent_dentry,
char *symbuf)
{
int err = 0;
umode_t old_mode = old_lower_dentry->d_inode->i_mode;
struct sioq_args args;
if (S_ISDIR(old_mode)) {
args.mkdir.parent = new_lower_parent_dentry->d_inode;
args.mkdir.dentry = new_lower_dentry;
args.mkdir.mode = old_mode;
run_sioq(__unionfs_mkdir, &args);
err = args.err;
} else if (S_ISLNK(old_mode)) {
args.symlink.parent = new_lower_parent_dentry->d_inode;
args.symlink.dentry = new_lower_dentry;
args.symlink.symbuf = symbuf;
run_sioq(__unionfs_symlink, &args);
err = args.err;
} else if (S_ISBLK(old_mode) || S_ISCHR(old_mode) ||
S_ISFIFO(old_mode) || S_ISSOCK(old_mode)) {
args.mknod.parent = new_lower_parent_dentry->d_inode;
args.mknod.dentry = new_lower_dentry;
args.mknod.mode = old_mode;
args.mknod.dev = old_lower_dentry->d_inode->i_rdev;
run_sioq(__unionfs_mknod, &args);
err = args.err;
} else if (S_ISREG(old_mode)) {
args.create.parent = new_lower_parent_dentry->d_inode;
args.create.dentry = new_lower_dentry;
args.create.mode = old_mode;
args.create.want_excl = false; /* XXX: pass to this fxn */
run_sioq(__unionfs_create, &args);
err = args.err;
} else {
printk(KERN_CRIT "unionfs: unknown inode type %d\n",
old_mode);
BUG();
}
return err;
}
static int __copyup_reg_data(struct dentry *dentry,
struct dentry *new_lower_dentry, int new_bindex,
struct dentry *old_lower_dentry, int old_bindex,
struct file **copyup_file, loff_t len)
{
struct super_block *sb = dentry->d_sb;
struct file *input_file;
struct file *output_file;
struct vfsmount *output_mnt;
mm_segment_t old_fs;
char *buf = NULL;
ssize_t read_bytes, write_bytes;
loff_t size;
int err = 0;
struct path input_path, output_path;
/* open old file */
unionfs_mntget(dentry, old_bindex);
branchget(sb, old_bindex);
/* dentry_open used to call dput and mntput if it returns an error */
input_path.dentry = old_lower_dentry;
input_path.mnt = unionfs_lower_mnt_idx(dentry, old_bindex);
input_file = dentry_open(&input_path,
O_RDONLY | O_LARGEFILE, current_cred());
path_put(&input_path);
if (IS_ERR(input_file)) {
dput(old_lower_dentry);
err = PTR_ERR(input_file);
goto out;
}
if (unlikely(!input_file->f_op || !input_file->f_op->read)) {
err = -EINVAL;
goto out_close_in;
}
/* open new file */
dget(new_lower_dentry);
output_mnt = unionfs_mntget(sb->s_root, new_bindex);
branchget(sb, new_bindex);
output_path.dentry = new_lower_dentry;
output_path.mnt = output_mnt;
output_file = dentry_open(&output_path,
O_RDWR | O_LARGEFILE, current_cred());
path_put(&output_path);
if (IS_ERR(output_file)) {
err = PTR_ERR(output_file);
goto out_close_in2;
}
if (unlikely(!output_file->f_op || !output_file->f_op->write)) {
err = -EINVAL;
goto out_close_out;
}
/* allocating a buffer */
buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
if (unlikely(!buf)) {
err = -ENOMEM;
goto out_close_out;
}
input_file->f_pos = 0;
output_file->f_pos = 0;
old_fs = get_fs();
set_fs(KERNEL_DS);
size = len;
err = 0;
do {
if (len >= PAGE_SIZE)
size = PAGE_SIZE;
else if ((len < PAGE_SIZE) && (len > 0))
size = len;
len -= PAGE_SIZE;
read_bytes =
input_file->f_op->read(input_file,
(char __user *)buf, size,
&input_file->f_pos);
if (read_bytes <= 0) {
err = read_bytes;
break;
}
/* see Documentation/filesystems/unionfs/issues.txt */
lockdep_off();
write_bytes =
output_file->f_op->write(output_file,
(char __user *)buf,
read_bytes,
&output_file->f_pos);
lockdep_on();
if ((write_bytes < 0) || (write_bytes < read_bytes)) {
err = write_bytes;
break;
}
} while ((read_bytes > 0) && (len > 0));
set_fs(old_fs);
kfree(buf);
#if 0
/* XXX: code no longer needed? */
if (!err)
err = output_file->f_op->fsync(output_file, 0);
#endif
if (err)
goto out_close_out;
if (copyup_file) {
*copyup_file = output_file;
goto out_close_in;
}
out_close_out:
fput(output_file);
out_close_in2:
branchput(sb, new_bindex);
out_close_in:
fput(input_file);
out:
branchput(sb, old_bindex);
return err;
}
/*
* dput the lower references for old and new dentry & clear a lower dentry
* pointer
*/
static void __clear(struct dentry *dentry, struct dentry *old_lower_dentry,
int old_bstart, int old_bend,
struct dentry *new_lower_dentry, int new_bindex)
{
/* get rid of the lower dentry and all its traces */
unionfs_set_lower_dentry_idx(dentry, new_bindex, NULL);
dbstart(dentry) = old_bstart;
dbend(dentry) = old_bend;
dput(new_lower_dentry);
dput(old_lower_dentry);
}
/*
* Copy up a dentry to a file of specified name.
*
* @dir: used to pull the ->i_sb to access other branches
* @dentry: the non-negative dentry whose lower_inode we should copy
* @bstart: the branch of the lower_inode to copy from
* @new_bindex: the branch to create the new file in
* @name: the name of the file to create
* @namelen: length of @name
* @copyup_file: the "struct file" to return (optional)
* @len: how many bytes to copy-up?
*/
int copyup_dentry(struct inode *dir, struct dentry *dentry, int bstart,
int new_bindex, const char *name, int namelen,
struct file **copyup_file, loff_t len)
{
struct dentry *new_lower_dentry;
struct dentry *old_lower_dentry = NULL;
struct super_block *sb;
int err = 0;
int old_bindex;
int old_bstart;
int old_bend;
struct dentry *new_lower_parent_dentry = NULL;
mm_segment_t oldfs;
char *symbuf = NULL;
verify_locked(dentry);
old_bindex = bstart;
old_bstart = dbstart(dentry);
old_bend = dbend(dentry);
BUG_ON(new_bindex < 0);
BUG_ON(new_bindex >= old_bindex);
sb = dir->i_sb;
err = is_robranch_super(sb, new_bindex);
if (err)
goto out;
/* Create the directory structure above this dentry. */
new_lower_dentry = create_parents(dir, dentry, name, new_bindex);
if (IS_ERR(new_lower_dentry)) {
err = PTR_ERR(new_lower_dentry);
goto out;
}
old_lower_dentry = unionfs_lower_dentry_idx(dentry, old_bindex);
/* we conditionally dput this old_lower_dentry at end of function */
dget(old_lower_dentry);
/* For symlinks, we must read the link before we lock the directory. */
if (S_ISLNK(old_lower_dentry->d_inode->i_mode)) {
symbuf = kmalloc(PATH_MAX, GFP_KERNEL);
if (unlikely(!symbuf)) {
__clear(dentry, old_lower_dentry,
old_bstart, old_bend,
new_lower_dentry, new_bindex);
err = -ENOMEM;
goto out_free;
}
oldfs = get_fs();
set_fs(KERNEL_DS);
err = old_lower_dentry->d_inode->i_op->readlink(
old_lower_dentry,
(char __user *)symbuf,
PATH_MAX);
set_fs(oldfs);
if (err < 0) {
__clear(dentry, old_lower_dentry,
old_bstart, old_bend,
new_lower_dentry, new_bindex);
goto out_free;
}
symbuf[err] = '\0';
}
/* Now we lock the parent, and create the object in the new branch. */
new_lower_parent_dentry = lock_parent(new_lower_dentry);
/* create the new inode */
err = __copyup_ndentry(old_lower_dentry, new_lower_dentry,
new_lower_parent_dentry, symbuf);
if (err) {
__clear(dentry, old_lower_dentry,
old_bstart, old_bend,
new_lower_dentry, new_bindex);
goto out_unlock;
}
/* We actually copyup the file here. */
if (S_ISREG(old_lower_dentry->d_inode->i_mode))
err = __copyup_reg_data(dentry, new_lower_dentry, new_bindex,
old_lower_dentry, old_bindex,
copyup_file, len);
if (err)
goto out_unlink;
/* Set permissions. */
err = copyup_permissions(sb, old_lower_dentry, new_lower_dentry);
if (err)
goto out_unlink;
#ifdef CONFIG_UNION_FS_XATTR
/* Selinux uses extended attributes for permissions. */
err = copyup_xattrs(old_lower_dentry, new_lower_dentry);
if (err)
goto out_unlink;
#endif /* CONFIG_UNION_FS_XATTR */
/* do not allow files getting deleted to be re-interposed */
if (!d_deleted(dentry))
unionfs_reinterpose(dentry);
goto out_unlock;
out_unlink:
/*
* copyup failed, because we possibly ran out of space or
* quota, or something else happened so let's unlink; we don't
* really care about the return value of vfs_unlink
*/
vfs_unlink(new_lower_parent_dentry->d_inode, new_lower_dentry, NULL);
if (copyup_file) {
/* need to close the file */
fput(*copyup_file);
branchput(sb, new_bindex);
}
/*
* TODO: should we reset the error to something like -EIO?
*
* If we don't reset, the user may get some nonsensical errors, but
* on the other hand, if we reset to EIO, we guarantee that the user
* will get a "confusing" error message.
*/
out_unlock:
unlock_dir(new_lower_parent_dentry);
out_free:
/*
* If old_lower_dentry was not a file, then we need to dput it. If
* it was a file, then it was already dput indirectly by other
* functions we call above which operate on regular files.
*/
if (old_lower_dentry && old_lower_dentry->d_inode &&
!S_ISREG(old_lower_dentry->d_inode->i_mode))
dput(old_lower_dentry);
kfree(symbuf);
if (err) {
/*
* if directory creation succeeded, but inode copyup failed,
* then purge new dentries.
*/
if (dbstart(dentry) < old_bstart &&
ibstart(dentry->d_inode) > dbstart(dentry))
__clear(dentry, NULL, old_bstart, old_bend,
unionfs_lower_dentry(dentry), dbstart(dentry));
goto out;
}
if (!S_ISDIR(dentry->d_inode->i_mode)) {
unionfs_postcopyup_release(dentry);
if (!unionfs_lower_inode(dentry->d_inode)) {
/*
* If we got here, then we copied up to an
* unlinked-open file, whose name is .unionfsXXXXX.
*/
struct inode *inode = new_lower_dentry->d_inode;
atomic_inc(&inode->i_count);
unionfs_set_lower_inode_idx(dentry->d_inode,
ibstart(dentry->d_inode),
inode);
}
}
unionfs_postcopyup_setmnt(dentry);
/* sync inode times from copied-up inode to our inode */
unionfs_copy_attr_times(dentry->d_inode);
unionfs_check_inode(dir);
unionfs_check_dentry(dentry);
out:
return err;
}
/*
* This function creates a copy of a file represented by 'file' which
* currently resides in branch 'bstart' to branch 'new_bindex.' The copy
* will be named "name".
*/
int copyup_named_file(struct inode *dir, struct file *file, char *name,
int bstart, int new_bindex, loff_t len)
{
int err = 0;
struct file *output_file = NULL;
err = copyup_dentry(dir, file->f_path.dentry, bstart, new_bindex,
name, strlen(name), &output_file, len);
if (!err) {
fbstart(file) = new_bindex;
unionfs_set_lower_file_idx(file, new_bindex, output_file);
}
return err;
}
/*
* This function creates a copy of a file represented by 'file' which
* currently resides in branch 'bstart' to branch 'new_bindex'.
*/
int copyup_file(struct inode *dir, struct file *file, int bstart,
int new_bindex, loff_t len)
{
int err = 0;
struct file *output_file = NULL;
struct dentry *dentry = file->f_path.dentry;
err = copyup_dentry(dir, dentry, bstart, new_bindex,
dentry->d_name.name, dentry->d_name.len,
&output_file, len);
if (!err) {
fbstart(file) = new_bindex;
unionfs_set_lower_file_idx(file, new_bindex, output_file);
}
return err;
}
/* purge a dentry's lower-branch states (dput/mntput, etc.) */
static void __cleanup_dentry(struct dentry *dentry, int bindex,
int old_bstart, int old_bend)
{
int loop_start;
int loop_end;
int new_bstart = -1;
int new_bend = -1;
int i;
loop_start = min(old_bstart, bindex);
loop_end = max(old_bend, bindex);
/*
* This loop sets the bstart and bend for the new dentry by
* traversing from left to right. It also dputs all negative
* dentries except bindex
*/
for (i = loop_start; i <= loop_end; i++) {
if (!unionfs_lower_dentry_idx(dentry, i))
continue;
if (i == bindex) {
new_bend = i;
if (new_bstart < 0)
new_bstart = i;
continue;
}
if (!unionfs_lower_dentry_idx(dentry, i)->d_inode) {
dput(unionfs_lower_dentry_idx(dentry, i));
unionfs_set_lower_dentry_idx(dentry, i, NULL);
unionfs_mntput(dentry, i);
unionfs_set_lower_mnt_idx(dentry, i, NULL);
} else {
if (new_bstart < 0)
new_bstart = i;
new_bend = i;
}
}
if (new_bstart < 0)
new_bstart = bindex;
if (new_bend < 0)
new_bend = bindex;
dbstart(dentry) = new_bstart;
dbend(dentry) = new_bend;
}
/* set lower inode ptr and update bstart & bend if necessary */
static void __set_inode(struct dentry *upper, struct dentry *lower,
int bindex)
{
unionfs_set_lower_inode_idx(upper->d_inode, bindex,
igrab(lower->d_inode));
if (likely(ibstart(upper->d_inode) > bindex))
ibstart(upper->d_inode) = bindex;
if (likely(ibend(upper->d_inode) < bindex))
ibend(upper->d_inode) = bindex;
}
/* set lower dentry ptr and update bstart & bend if necessary */
static void __set_dentry(struct dentry *upper, struct dentry *lower,
int bindex)
{
unionfs_set_lower_dentry_idx(upper, bindex, lower);
if (likely(dbstart(upper) > bindex))
dbstart(upper) = bindex;
if (likely(dbend(upper) < bindex))
dbend(upper) = bindex;
}
/*
* This function replicates the directory structure up-to given dentry
* in the bindex branch.
*/
struct dentry *create_parents(struct inode *dir, struct dentry *dentry,
const char *name, int bindex)
{
int err;
struct dentry *child_dentry;
struct dentry *parent_dentry;
struct dentry *lower_parent_dentry = NULL;
struct dentry *lower_dentry = NULL;
const char *childname;
unsigned int childnamelen;
int nr_dentry;
int count = 0;
int old_bstart;
int old_bend;
struct dentry **path = NULL;
struct super_block *sb;
verify_locked(dentry);
err = is_robranch_super(dir->i_sb, bindex);
if (err) {
lower_dentry = ERR_PTR(err);
goto out;
}
old_bstart = dbstart(dentry);
old_bend = dbend(dentry);
lower_dentry = ERR_PTR(-ENOMEM);
/* There is no sense allocating any less than the minimum. */
nr_dentry = 1;
path = kmalloc(nr_dentry * sizeof(struct dentry *), GFP_KERNEL);
if (unlikely(!path))
goto out;
/* assume the negative dentry of unionfs as the parent dentry */
parent_dentry = dentry;
/*
* This loop finds the first parent that exists in the given branch.
* We start building the directory structure from there. At the end
* of the loop, the following should hold:
* - child_dentry is the first nonexistent child
* - parent_dentry is the first existent parent
* - path[0] is the = deepest child
* - path[count] is the first child to create
*/
do {
child_dentry = parent_dentry;
/* find the parent directory dentry in unionfs */
parent_dentry = dget_parent(child_dentry);
/* find out the lower_parent_dentry in the given branch */
lower_parent_dentry =
unionfs_lower_dentry_idx(parent_dentry, bindex);
/* grow path table */
if (count == nr_dentry) {
void *p;
nr_dentry *= 2;
p = krealloc(path, nr_dentry * sizeof(struct dentry *),
GFP_KERNEL);
if (unlikely(!p)) {
lower_dentry = ERR_PTR(-ENOMEM);
goto out;
}
path = p;
}
/* store the child dentry */
path[count++] = child_dentry;
} while (!lower_parent_dentry);
count--;
sb = dentry->d_sb;
/*
* This code goes between the begin/end labels and basically
* emulates a while(child_dentry != dentry), only cleaner and
* shorter than what would be a much longer while loop.
*/
begin:
/* get lower parent dir in the current branch */
lower_parent_dentry = unionfs_lower_dentry_idx(parent_dentry, bindex);
dput(parent_dentry);
/* init the values to lookup */
childname = child_dentry->d_name.name;
childnamelen = child_dentry->d_name.len;
if (child_dentry != dentry) {
/* lookup child in the underlying file system */
lower_dentry = lookup_lck_len(childname, lower_parent_dentry,
childnamelen);
if (IS_ERR(lower_dentry))
goto out;
} else {
/*
* Is the name a whiteout of the child name ? lookup the
* whiteout child in the underlying file system
*/
lower_dentry = lookup_lck_len(name, lower_parent_dentry,
strlen(name));
if (IS_ERR(lower_dentry))
goto out;
/* Replace the current dentry (if any) with the new one */
dput(unionfs_lower_dentry_idx(dentry, bindex));
unionfs_set_lower_dentry_idx(dentry, bindex,
lower_dentry);
__cleanup_dentry(dentry, bindex, old_bstart, old_bend);
goto out;
}
if (lower_dentry->d_inode) {
/*
* since this already exists we dput to avoid
* multiple references on the same dentry
*/
dput(lower_dentry);
} else {
struct sioq_args args;
/* it's a negative dentry, create a new dir */
lower_parent_dentry = lock_parent(lower_dentry);
args.mkdir.parent = lower_parent_dentry->d_inode;
args.mkdir.dentry = lower_dentry;
args.mkdir.mode = child_dentry->d_inode->i_mode;
run_sioq(__unionfs_mkdir, &args);
err = args.err;
if (!err)
err = copyup_permissions(dir->i_sb, child_dentry,
lower_dentry);
unlock_dir(lower_parent_dentry);
if (err) {
dput(lower_dentry);
lower_dentry = ERR_PTR(err);
goto out;
}
}
__set_inode(child_dentry, lower_dentry, bindex);
__set_dentry(child_dentry, lower_dentry, bindex);
/*
* update times of this dentry, but also the parent, because if
* we changed, the parent may have changed too.
*/
fsstack_copy_attr_times(parent_dentry->d_inode,
lower_parent_dentry->d_inode);
unionfs_copy_attr_times(child_dentry->d_inode);
parent_dentry = child_dentry;
child_dentry = path[--count];
goto begin;
out:
/* cleanup any leftover locks from the do/while loop above */
if (IS_ERR(lower_dentry))
while (count)
dput(path[count--]);
kfree(path);
return lower_dentry;
}
/*
* Post-copyup helper to ensure we have valid mnts: set lower mnt of
* dentry+parents to the first parent node that has an mnt.
*/
void unionfs_postcopyup_setmnt(struct dentry *dentry)
{
struct dentry *parent, *hasone;
int bindex = dbstart(dentry);
if (unionfs_lower_mnt_idx(dentry, bindex))
return;
hasone = dentry->d_parent;
/* this loop should stop at root dentry */
while (!unionfs_lower_mnt_idx(hasone, bindex))
hasone = hasone->d_parent;
parent = dentry;
while (!unionfs_lower_mnt_idx(parent, bindex)) {
unionfs_set_lower_mnt_idx(parent, bindex,
unionfs_mntget(hasone, bindex));
parent = parent->d_parent;
}
}
/*
* Post-copyup helper to release all non-directory source objects of a
* copied-up file. Regular files should have only one lower object.
*/
void unionfs_postcopyup_release(struct dentry *dentry)
{
int bstart, bend;
BUG_ON(S_ISDIR(dentry->d_inode->i_mode));
bstart = dbstart(dentry);
bend = dbend(dentry);
path_put_lowers(dentry, bstart + 1, bend, false);
iput_lowers(dentry->d_inode, bstart + 1, bend, false);
dbend(dentry) = bstart;
ibend(dentry->d_inode) = ibstart(dentry->d_inode) = bstart;
}

531
fs/unionfs/debug.c Normal file
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@ -0,0 +1,531 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
#include "../mount.h"
/*
* Helper debugging functions for maintainers (and for users to report back
* useful information back to maintainers)
*/
/* it's always useful to know what part of the code called us */
#define PRINT_CALLER(fname, fxn, line) \
do { \
if (!printed_caller) { \
pr_debug("PC:%s:%s:%d\n", (fname), (fxn), (line)); \
printed_caller = 1; \
} \
} while (0)
/*
* __unionfs_check_{inode,dentry,file} perform exhaustive sanity checking on
* the fan-out of various Unionfs objects. We check that no lower objects
* exist outside the start/end branch range; that all objects within are
* non-NULL (with some allowed exceptions); that for every lower file
* there's a lower dentry+inode; that the start/end ranges match for all
* corresponding lower objects; that open files/symlinks have only one lower
* objects, but directories can have several; and more.
*/
void __unionfs_check_inode(const struct inode *inode,
const char *fname, const char *fxn, int line)
{
int bindex;
int istart, iend;
struct inode *lower_inode;
struct super_block *sb;
int printed_caller = 0;
void *poison_ptr;
/* for inodes now */
BUG_ON(!inode);
sb = inode->i_sb;
istart = ibstart(inode);
iend = ibend(inode);
/* don't check inode if no lower branches */
if (istart < 0 && iend < 0)
return;
if (unlikely(istart > iend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci0: inode=%p istart/end=%d:%d\n",
inode, istart, iend);
}
if (unlikely((istart == -1 && iend != -1) ||
(istart != -1 && iend == -1))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci1: inode=%p istart/end=%d:%d\n",
inode, istart, iend);
}
if (!S_ISDIR(inode->i_mode)) {
if (unlikely(iend != istart)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci2: inode=%p istart=%d iend=%d\n",
inode, istart, iend);
}
}
for (bindex = sbstart(sb); bindex < sbmax(sb); bindex++) {
if (unlikely(!UNIONFS_I(inode))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci3: no inode_info %p\n", inode);
return;
}
if (unlikely(!UNIONFS_I(inode)->lower_inodes)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci4: no lower_inodes %p\n", inode);
return;
}
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (lower_inode) {
memset(&poison_ptr, POISON_INUSE, sizeof(void *));
if (unlikely(bindex < istart || bindex > iend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci5: inode/linode=%p:%p bindex=%d "
"istart/end=%d:%d\n", inode,
lower_inode, bindex, istart, iend);
} else if (unlikely(lower_inode == poison_ptr)) {
/* freed inode! */
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci6: inode/linode=%p:%p bindex=%d "
"istart/end=%d:%d\n", inode,
lower_inode, bindex, istart, iend);
}
continue;
}
/* if we get here, then lower_inode == NULL */
if (bindex < istart || bindex > iend)
continue;
/*
* directories can have NULL lower inodes in b/t start/end,
* but NOT if at the start/end range.
*/
if (unlikely(S_ISDIR(inode->i_mode) &&
bindex > istart && bindex < iend))
continue;
PRINT_CALLER(fname, fxn, line);
pr_debug(" Ci7: inode/linode=%p:%p "
"bindex=%d istart/end=%d:%d\n",
inode, lower_inode, bindex, istart, iend);
}
}
void __unionfs_check_dentry(const struct dentry *dentry,
const char *fname, const char *fxn, int line)
{
int bindex;
int dstart, dend, istart, iend;
struct dentry *lower_dentry;
struct inode *inode, *lower_inode;
struct super_block *sb;
struct vfsmount *lower_mnt;
int printed_caller = 0;
void *poison_ptr;
BUG_ON(!dentry);
sb = dentry->d_sb;
inode = dentry->d_inode;
dstart = dbstart(dentry);
dend = dbend(dentry);
/* don't check dentry/mnt if no lower branches */
if (dstart < 0 && dend < 0)
goto check_inode;
BUG_ON(dstart > dend);
if (unlikely((dstart == -1 && dend != -1) ||
(dstart != -1 && dend == -1))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CD0: dentry=%p dstart/end=%d:%d\n",
dentry, dstart, dend);
}
/*
* check for NULL dentries inside the start/end range, or
* non-NULL dentries outside the start/end range.
*/
for (bindex = sbstart(sb); bindex < sbmax(sb); bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (lower_dentry) {
if (unlikely(bindex < dstart || bindex > dend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CD1: dentry/lower=%p:%p(%p) "
"bindex=%d dstart/end=%d:%d\n",
dentry, lower_dentry,
(lower_dentry ? lower_dentry->d_inode :
(void *) -1L),
bindex, dstart, dend);
}
} else { /* lower_dentry == NULL */
if (bindex < dstart || bindex > dend)
continue;
/*
* Directories can have NULL lower inodes in b/t
* start/end, but NOT if at the start/end range.
* Ignore this rule, however, if this is a NULL
* dentry or a deleted dentry.
*/
if (unlikely(!d_deleted((struct dentry *) dentry) &&
inode &&
!(inode && S_ISDIR(inode->i_mode) &&
bindex > dstart && bindex < dend))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CD2: dentry/lower=%p:%p(%p) "
"bindex=%d dstart/end=%d:%d\n",
dentry, lower_dentry,
(lower_dentry ?
lower_dentry->d_inode :
(void *) -1L),
bindex, dstart, dend);
}
}
}
/* check for vfsmounts same as for dentries */
for (bindex = sbstart(sb); bindex < sbmax(sb); bindex++) {
lower_mnt = unionfs_lower_mnt_idx(dentry, bindex);
if (lower_mnt) {
if (unlikely(bindex < dstart || bindex > dend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CM0: dentry/lmnt=%p:%p bindex=%d "
"dstart/end=%d:%d\n", dentry,
lower_mnt, bindex, dstart, dend);
}
} else { /* lower_mnt == NULL */
if (bindex < dstart || bindex > dend)
continue;
/*
* Directories can have NULL lower inodes in b/t
* start/end, but NOT if at the start/end range.
* Ignore this rule, however, if this is a NULL
* dentry.
*/
if (unlikely(inode &&
!(inode && S_ISDIR(inode->i_mode) &&
bindex > dstart && bindex < dend))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CM1: dentry/lmnt=%p:%p "
"bindex=%d dstart/end=%d:%d\n",
dentry, lower_mnt, bindex,
dstart, dend);
}
}
}
check_inode:
/* for inodes now */
if (!inode)
return;
istart = ibstart(inode);
iend = ibend(inode);
/* don't check inode if no lower branches */
if (istart < 0 && iend < 0)
return;
BUG_ON(istart > iend);
if (unlikely((istart == -1 && iend != -1) ||
(istart != -1 && iend == -1))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI0: dentry/inode=%p:%p istart/end=%d:%d\n",
dentry, inode, istart, iend);
}
if (unlikely(istart != dstart)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI1: dentry/inode=%p:%p istart=%d dstart=%d\n",
dentry, inode, istart, dstart);
}
if (unlikely(iend != dend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI2: dentry/inode=%p:%p iend=%d dend=%d\n",
dentry, inode, iend, dend);
}
if (!S_ISDIR(inode->i_mode)) {
if (unlikely(dend != dstart)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI3: dentry/inode=%p:%p dstart=%d dend=%d\n",
dentry, inode, dstart, dend);
}
if (unlikely(iend != istart)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI4: dentry/inode=%p:%p istart=%d iend=%d\n",
dentry, inode, istart, iend);
}
}
for (bindex = sbstart(sb); bindex < sbmax(sb); bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (lower_inode) {
memset(&poison_ptr, POISON_INUSE, sizeof(void *));
if (unlikely(bindex < istart || bindex > iend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI5: dentry/linode=%p:%p bindex=%d "
"istart/end=%d:%d\n", dentry,
lower_inode, bindex, istart, iend);
} else if (unlikely(lower_inode == poison_ptr)) {
/* freed inode! */
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI6: dentry/linode=%p:%p bindex=%d "
"istart/end=%d:%d\n", dentry,
lower_inode, bindex, istart, iend);
}
continue;
}
/* if we get here, then lower_inode == NULL */
if (bindex < istart || bindex > iend)
continue;
/*
* directories can have NULL lower inodes in b/t start/end,
* but NOT if at the start/end range.
*/
if (unlikely(S_ISDIR(inode->i_mode) &&
bindex > istart && bindex < iend))
continue;
PRINT_CALLER(fname, fxn, line);
pr_debug(" CI7: dentry/linode=%p:%p "
"bindex=%d istart/end=%d:%d\n",
dentry, lower_inode, bindex, istart, iend);
}
/*
* If it's a directory, then intermediate objects b/t start/end can
* be NULL. But, check that all three are NULL: lower dentry, mnt,
* and inode.
*/
if (dstart >= 0 && dend >= 0 && S_ISDIR(inode->i_mode))
for (bindex = dstart+1; bindex < dend; bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
lower_dentry = unionfs_lower_dentry_idx(dentry,
bindex);
lower_mnt = unionfs_lower_mnt_idx(dentry, bindex);
if (unlikely(!((lower_inode && lower_dentry &&
lower_mnt) ||
(!lower_inode &&
!lower_dentry && !lower_mnt)))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" Cx: lmnt/ldentry/linode=%p:%p:%p "
"bindex=%d dstart/end=%d:%d\n",
lower_mnt, lower_dentry, lower_inode,
bindex, dstart, dend);
}
}
/* check if lower inode is newer than upper one (it shouldn't) */
if (unlikely(is_newer_lower(dentry) && !is_negative_lower(dentry))) {
PRINT_CALLER(fname, fxn, line);
for (bindex = ibstart(inode); bindex <= ibend(inode);
bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (unlikely(!lower_inode))
continue;
pr_debug(" CI8: bindex=%d mtime/lmtime=%lu.%lu/%lu.%lu "
"ctime/lctime=%lu.%lu/%lu.%lu\n",
bindex,
inode->i_mtime.tv_sec,
inode->i_mtime.tv_nsec,
lower_inode->i_mtime.tv_sec,
lower_inode->i_mtime.tv_nsec,
inode->i_ctime.tv_sec,
inode->i_ctime.tv_nsec,
lower_inode->i_ctime.tv_sec,
lower_inode->i_ctime.tv_nsec);
}
}
}
void __unionfs_check_file(const struct file *file,
const char *fname, const char *fxn, int line)
{
int bindex;
int dstart, dend, fstart, fend;
struct dentry *dentry;
struct file *lower_file;
struct inode *inode;
struct super_block *sb;
int printed_caller = 0;
BUG_ON(!file);
dentry = file->f_path.dentry;
sb = dentry->d_sb;
dstart = dbstart(dentry);
dend = dbend(dentry);
BUG_ON(dstart > dend);
fstart = fbstart(file);
fend = fbend(file);
BUG_ON(fstart > fend);
if (unlikely((fstart == -1 && fend != -1) ||
(fstart != -1 && fend == -1))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF0: file/dentry=%p:%p fstart/end=%d:%d\n",
file, dentry, fstart, fend);
}
/* d_deleted dentries can be ignored for this test */
if (unlikely(fstart != dstart) && !d_deleted(dentry)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF1: file/dentry=%p:%p fstart=%d dstart=%d\n",
file, dentry, fstart, dstart);
}
if (unlikely(fend != dend) && !d_deleted(dentry)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF2: file/dentry=%p:%p fend=%d dend=%d\n",
file, dentry, fend, dend);
}
inode = dentry->d_inode;
if (!S_ISDIR(inode->i_mode)) {
if (unlikely(fend != fstart)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF3: file/inode=%p:%p fstart=%d fend=%d\n",
file, inode, fstart, fend);
}
if (unlikely(dend != dstart)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF4: file/dentry=%p:%p dstart=%d dend=%d\n",
file, dentry, dstart, dend);
}
}
/*
* check for NULL dentries inside the start/end range, or
* non-NULL dentries outside the start/end range.
*/
for (bindex = sbstart(sb); bindex < sbmax(sb); bindex++) {
lower_file = unionfs_lower_file_idx(file, bindex);
if (lower_file) {
if (unlikely(bindex < fstart || bindex > fend)) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF5: file/lower=%p:%p bindex=%d "
"fstart/end=%d:%d\n", file,
lower_file, bindex, fstart, fend);
}
} else { /* lower_file == NULL */
if (bindex >= fstart && bindex <= fend) {
/*
* directories can have NULL lower inodes in
* b/t start/end, but NOT if at the
* start/end range.
*/
if (unlikely(!(S_ISDIR(inode->i_mode) &&
bindex > fstart &&
bindex < fend))) {
PRINT_CALLER(fname, fxn, line);
pr_debug(" CF6: file/lower=%p:%p "
"bindex=%d fstart/end=%d:%d\n",
file, lower_file, bindex,
fstart, fend);
}
}
}
}
__unionfs_check_dentry(dentry, fname, fxn, line);
}
static unsigned int __mnt_get_count(struct vfsmount *mnt)
{
struct mount *m = real_mount(mnt);
#ifdef CONFIG_SMP
unsigned int count = 0;
int cpu;
for_each_possible_cpu(cpu) {
count += per_cpu_ptr(m->mnt_pcp, cpu)->mnt_count;
}
return count;
#else
return m->mnt_count;
#endif
}
/* useful to track vfsmount leaks that could cause EBUSY on unmount */
void __show_branch_counts(const struct super_block *sb,
const char *file, const char *fxn, int line)
{
int i;
struct vfsmount *mnt;
pr_debug("BC:");
for (i = 0; i < sbmax(sb); i++) {
if (likely(sb->s_root))
mnt = UNIONFS_D(sb->s_root)->lower_paths[i].mnt;
else
mnt = NULL;
printk(KERN_CONT "%d:",
(mnt ? __mnt_get_count(mnt) : -99));
}
printk(KERN_CONT "%s:%s:%d\n", file, fxn, line);
}
void __show_inode_times(const struct inode *inode,
const char *file, const char *fxn, int line)
{
struct inode *lower_inode;
int bindex;
for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (unlikely(!lower_inode))
continue;
pr_debug("IT(%lu:%d): %s:%s:%d "
"um=%lu/%lu lm=%lu/%lu uc=%lu/%lu lc=%lu/%lu\n",
inode->i_ino, bindex,
file, fxn, line,
inode->i_mtime.tv_sec, inode->i_mtime.tv_nsec,
lower_inode->i_mtime.tv_sec,
lower_inode->i_mtime.tv_nsec,
inode->i_ctime.tv_sec, inode->i_ctime.tv_nsec,
lower_inode->i_ctime.tv_sec,
lower_inode->i_ctime.tv_nsec);
}
}
void __show_dinode_times(const struct dentry *dentry,
const char *file, const char *fxn, int line)
{
struct inode *inode = dentry->d_inode;
struct inode *lower_inode;
int bindex;
for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (!lower_inode)
continue;
pr_debug("DT(%pd:%lu:%d): %s:%s:%d "
"um=%lu/%lu lm=%lu/%lu uc=%lu/%lu lc=%lu/%lu\n",
dentry, inode->i_ino, bindex,
file, fxn, line,
inode->i_mtime.tv_sec, inode->i_mtime.tv_nsec,
lower_inode->i_mtime.tv_sec,
lower_inode->i_mtime.tv_nsec,
inode->i_ctime.tv_sec, inode->i_ctime.tv_nsec,
lower_inode->i_ctime.tv_sec,
lower_inode->i_ctime.tv_nsec);
}
}
void __show_inode_counts(const struct inode *inode,
const char *file, const char *fxn, int line)
{
struct inode *lower_inode;
int bindex;
if (unlikely(!inode)) {
pr_debug("SiC: Null inode\n");
return;
}
for (bindex = sbstart(inode->i_sb); bindex <= sbend(inode->i_sb);
bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (unlikely(!lower_inode))
continue;
pr_debug("SIC(%lu:%d:%d): lc=%d %s:%s:%d\n",
inode->i_ino, bindex,
atomic_read(&(inode)->i_count),
atomic_read(&(lower_inode)->i_count),
file, fxn, line);
}
}

402
fs/unionfs/dentry.c Normal file
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@ -0,0 +1,402 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
bool is_negative_lower(const struct dentry *dentry)
{
int bindex;
struct dentry *lower_dentry;
BUG_ON(!dentry);
/* cache coherency: check if file was deleted on lower branch */
if (dbstart(dentry) < 0)
return true;
for (bindex = dbstart(dentry); bindex <= dbend(dentry); bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
/* unhashed (i.e., unlinked) lower dentries don't count */
if (lower_dentry && lower_dentry->d_inode &&
!d_deleted(lower_dentry) &&
!(lower_dentry->d_flags & DCACHE_NFSFS_RENAMED))
return false;
}
return true;
}
static inline void __dput_lowers(struct dentry *dentry, int start, int end)
{
struct dentry *lower_dentry;
int bindex;
if (start < 0)
return;
for (bindex = start; bindex <= end; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
dput(lower_dentry);
}
}
/*
* Purge and invalidate as many data pages of a unionfs inode. This is
* called when the lower inode has changed, and we want to force processes
* to re-get the new data.
*/
static inline void purge_inode_data(struct inode *inode)
{
/* remove all non-private mappings */
unmap_mapping_range(inode->i_mapping, 0, 0, 0);
/* invalidate as many pages as possible */
invalidate_mapping_pages(inode->i_mapping, 0, -1);
/*
* Don't try to truncate_inode_pages here, because this could lead
* to a deadlock between some of address_space ops and dentry
* revalidation: the address space op is invoked with a lock on our
* own page, and truncate_inode_pages will block on locked pages.
*/
}
/*
* Revalidate a single file/symlink/special dentry. Assume that info nodes
* of the @dentry and its @parent are locked. Assume parent is valid,
* otherwise return false (and let's hope the VFS will try to re-lookup this
* dentry). Returns true if valid, false otherwise.
*/
bool __unionfs_d_revalidate(struct dentry *dentry, struct dentry *parent,
bool willwrite, unsigned int flags)
{
bool valid = true; /* default is valid */
struct dentry *lower_dentry;
struct dentry *result;
int bindex, bstart, bend;
int sbgen, dgen, pdgen;
int positive = 0;
int interpose_flag;
verify_locked(dentry);
verify_locked(parent);
/* if the dentry is unhashed, do NOT revalidate */
if (d_deleted(dentry))
goto out;
dgen = atomic_read(&UNIONFS_D(dentry)->generation);
if (is_newer_lower(dentry)) {
/* root dentry is always valid */
if (IS_ROOT(dentry)) {
unionfs_copy_attr_times(dentry->d_inode);
} else {
/*
* reset generation number to zero, guaranteed to be
* "old"
*/
dgen = 0;
atomic_set(&UNIONFS_D(dentry)->generation, dgen);
}
if (!willwrite)
purge_inode_data(dentry->d_inode);
}
sbgen = atomic_read(&UNIONFS_SB(dentry->d_sb)->generation);
BUG_ON(dbstart(dentry) == -1);
if (dentry->d_inode)
positive = 1;
/* if our dentry is valid, then validate all lower ones */
if (sbgen == dgen)
goto validate_lowers;
/* The root entry should always be valid */
BUG_ON(IS_ROOT(dentry));
/* We can't work correctly if our parent isn't valid. */
pdgen = atomic_read(&UNIONFS_D(parent)->generation);
/* Free the pointers for our inodes and this dentry. */
path_put_lowers_all(dentry, false);
interpose_flag = INTERPOSE_REVAL_NEG;
if (positive) {
interpose_flag = INTERPOSE_REVAL;
iput_lowers_all(dentry->d_inode, true);
}
if (realloc_dentry_private_data(dentry) != 0) {
valid = false;
goto out;
}
result = unionfs_lookup_full(dentry, parent, interpose_flag);
if (result) {
if (IS_ERR(result)) {
valid = false;
goto out;
}
/*
* current unionfs_lookup_backend() doesn't return
* a valid dentry
*/
dput(dentry);
dentry = result;
}
if (unlikely(positive && is_negative_lower(dentry))) {
/* call make_bad_inode here ? */
d_drop(dentry);
valid = false;
goto out;
}
/*
* if we got here then we have revalidated our dentry and all lower
* ones, so we can return safely.
*/
if (!valid) /* lower dentry revalidation failed */
goto out;
/*
* If the parent's gen no. matches the superblock's gen no., then
* we can update our denty's gen no. If they didn't match, then it
* was OK to revalidate this dentry with a stale parent, but we'll
* purposely not update our dentry's gen no. (so it can be redone);
* and, we'll mark our parent dentry as invalid so it'll force it
* (and our dentry) to be revalidated.
*/
if (pdgen == sbgen)
atomic_set(&UNIONFS_D(dentry)->generation, sbgen);
goto out;
validate_lowers:
/* The revalidation must occur across all branches */
bstart = dbstart(dentry);
bend = dbend(dentry);
BUG_ON(bstart == -1);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry || !lower_dentry->d_op
|| !lower_dentry->d_op->d_revalidate)
continue;
if (!lower_dentry->d_op->d_revalidate(lower_dentry, flags))
valid = false;
}
if (!dentry->d_inode ||
ibstart(dentry->d_inode) < 0 ||
ibend(dentry->d_inode) < 0) {
valid = false;
goto out;
}
if (valid) {
/*
* If we get here, and we copy the meta-data from the lower
* inode to our inode, then it is vital that we have already
* purged all unionfs-level file data. We do that in the
* caller (__unionfs_d_revalidate) by calling
* purge_inode_data.
*/
unionfs_copy_attr_all(dentry->d_inode,
unionfs_lower_inode(dentry->d_inode));
fsstack_copy_inode_size(dentry->d_inode,
unionfs_lower_inode(dentry->d_inode));
}
out:
return valid;
}
/*
* Determine if the lower inode objects have changed from below the unionfs
* inode. Return true if changed, false otherwise.
*
* We check if the mtime or ctime have changed. However, the inode times
* can be changed by anyone without much protection, including
* asynchronously. This can sometimes cause unionfs to find that the lower
* file system doesn't change its inode times quick enough, resulting in a
* false positive indication (which is harmless, it just makes unionfs do
* extra work in re-validating the objects). To minimize the chances of
* these situations, we still consider such small time changes valid, but we
* don't print debugging messages unless the time changes are greater than
* UNIONFS_MIN_CC_TIME (which defaults to 3 seconds, as with NFS's acregmin)
* because significant changes are more likely due to users manually
* touching lower files.
*/
bool is_newer_lower(const struct dentry *dentry)
{
int bindex;
struct inode *inode;
struct inode *lower_inode;
/* ignore if we're called on semi-initialized dentries/inodes */
if (!dentry || !UNIONFS_D(dentry))
return false;
inode = dentry->d_inode;
if (!inode || !UNIONFS_I(inode)->lower_inodes ||
ibstart(inode) < 0 || ibend(inode) < 0)
return false;
for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (!lower_inode)
continue;
/* check if mtime/ctime have changed */
if (unlikely(timespec_compare(&inode->i_mtime,
&lower_inode->i_mtime) < 0)) {
if ((lower_inode->i_mtime.tv_sec -
inode->i_mtime.tv_sec) > UNIONFS_MIN_CC_TIME) {
pr_info("unionfs: new lower inode mtime "
"(bindex=%d, name=%pd)\n", bindex,
dentry);
show_dinode_times(dentry);
}
return true;
}
if (unlikely(timespec_compare(&inode->i_ctime,
&lower_inode->i_ctime) < 0)) {
if ((lower_inode->i_ctime.tv_sec -
inode->i_ctime.tv_sec) > UNIONFS_MIN_CC_TIME) {
pr_info("unionfs: new lower inode ctime "
"(bindex=%d, name=%pd)\n", bindex,
dentry);
show_dinode_times(dentry);
}
return true;
}
}
/*
* Last check: if this is a positive dentry, but somehow all lower
* dentries are negative or unhashed, then this dentry needs to be
* revalidated, because someone probably deleted the objects from
* the lower branches directly.
*/
if (is_negative_lower(dentry))
return true;
return false; /* default: lower is not newer */
}
static int unionfs_d_revalidate(struct dentry *dentry, unsigned int flags)
{
bool valid = true;
int err = 1; /* 1 means valid for the VFS */
struct dentry *parent;
struct dentry *lower_dentry;
if (flags & LOOKUP_RCU)
return -ECHILD;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
lower_dentry = unionfs_lower_dentry(dentry);
if (!lower_dentry) {
err = 0;
goto out;
}
if (!(lower_dentry->d_flags & DCACHE_OP_REVALIDATE))
goto out;
valid = __unionfs_d_revalidate(dentry, parent, false, flags);
if (valid) {
unionfs_postcopyup_setmnt(dentry);
unionfs_check_dentry(dentry);
} else {
d_drop(dentry);
err = valid;
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static void unionfs_d_release(struct dentry *dentry)
{
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
if (unlikely(!UNIONFS_D(dentry)))
goto out; /* skip if no lower branches */
/* must lock our branch configuration here */
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
unionfs_check_dentry(dentry);
/* this could be a negative dentry, so check first */
if (dbstart(dentry) < 0) {
unionfs_unlock_dentry(dentry);
goto out; /* due to a (normal) failed lookup */
}
/* Release all the lower dentries */
path_put_lowers_all(dentry, true);
unionfs_unlock_dentry(dentry);
out:
free_dentry_private_data(dentry);
unionfs_read_unlock(dentry->d_sb);
return;
}
/*
* Called when we're removing the last reference to our dentry. So we
* should drop all lower references too.
*/
static void unionfs_d_iput(struct dentry *dentry, struct inode *inode)
{
int rc;
BUG_ON(!dentry);
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
if (!UNIONFS_D(dentry) || dbstart(dentry) < 0)
goto drop_lower_inodes;
path_put_lowers_all(dentry, false);
drop_lower_inodes:
rc = atomic_read(&inode->i_count);
if (rc == 1 && inode->i_nlink == 1 && ibstart(inode) >= 0) {
/* see Documentation/filesystems/unionfs/issues.txt */
lockdep_off();
iput(unionfs_lower_inode(inode));
lockdep_on();
unionfs_set_lower_inode(inode, NULL);
/* XXX: may need to set start/end to -1? */
}
iput(inode);
unionfs_unlock_dentry(dentry);
unionfs_read_unlock(dentry->d_sb);
}
struct dentry_operations unionfs_dops = {
.d_revalidate = unionfs_d_revalidate,
.d_release = unionfs_d_release,
.d_iput = unionfs_d_iput,
};

306
fs/unionfs/dirfops.c Normal file
View File

@ -0,0 +1,306 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/* Make sure our rdstate is playing by the rules. */
static void verify_rdstate_offset(struct unionfs_dir_state *rdstate)
{
BUG_ON(rdstate->offset >= DIREOF);
BUG_ON(rdstate->cookie >= MAXRDCOOKIE);
}
struct unionfs_getdents_callback {
struct dir_context ctx; /* must be first field */
struct dir_context *caller;
struct unionfs_dir_state *rdstate;
int entries_written;
int filldir_called;
int filldir_error;
struct super_block *sb;
};
/* based on generic filldir in fs/readir.c */
static int unionfs_filldir(void *__buf, const char *oname, int namelen,
loff_t offset, u64 ino, unsigned int d_type)
{
struct unionfs_getdents_callback *buf =
(struct unionfs_getdents_callback *) __buf;
struct filldir_node *found = NULL;
int err = 0;
int is_whiteout;
char *name = (char *) oname;
buf->filldir_called++;
is_whiteout = is_whiteout_name(&name, &namelen);
found = find_filldir_node(buf->rdstate, name, namelen, is_whiteout);
if (found) {
/*
* If we had non-whiteout entry in dir cache, then mark it
* as a whiteout and but leave it in the dir cache.
*/
if (is_whiteout && !found->whiteout)
found->whiteout = is_whiteout;
goto out;
}
/* if 'name' isn't a whiteout, filldir it. */
if (!is_whiteout) {
#if 0
// XXX: old code, not sure if needed
off_t pos = rdstate2offset(buf->rdstate);
#endif
buf->caller->pos = buf->ctx.pos;
err = !dir_emit(buf->caller, name, namelen, ino, d_type);
buf->rdstate->offset++;
verify_rdstate_offset(buf->rdstate);
}
/*
* If we did fill it, stuff it in our hash, otherwise return an
* error.
*/
if (err) {
buf->filldir_error = err;
goto out;
}
buf->entries_written++;
err = add_filldir_node(buf->rdstate, name, namelen,
buf->rdstate->bindex, is_whiteout);
if (err)
buf->filldir_error = err;
out:
return err;
}
static int unionfs_readdir(struct file *file, struct dir_context *ctx)
{
int err = 0;
struct file *lower_file = NULL;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
struct inode *inode = NULL;
struct unionfs_getdents_callback buf = {
.ctx.actor = unionfs_filldir,
};
struct unionfs_dir_state *uds;
int bend;
loff_t offset;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, false);
if (unlikely(err))
goto out;
inode = dentry->d_inode;
uds = UNIONFS_F(file)->rdstate;
if (!uds) {
if (file->f_pos == DIREOF) {
goto out;
} else if (file->f_pos > 0) {
uds = find_rdstate(inode, file->f_pos);
if (unlikely(!uds)) {
err = -ESTALE;
goto out;
}
UNIONFS_F(file)->rdstate = uds;
} else {
init_rdstate(file);
uds = UNIONFS_F(file)->rdstate;
}
}
bend = fbend(file);
while (uds->bindex <= bend) {
lower_file = unionfs_lower_file_idx(file, uds->bindex);
if (!lower_file) {
uds->bindex++;
uds->dirpos = 0;
continue;
}
/* prepare callback buffer */
buf.filldir_called = 0;
buf.filldir_error = 0;
buf.entries_written = 0;
buf.rdstate = uds;
buf.sb = inode->i_sb;
buf.caller = ctx;
/* Read starting from where we last left off. */
offset = vfs_llseek(lower_file, uds->dirpos, SEEK_SET);
if (offset < 0) {
err = offset;
goto out;
}
err = iterate_dir(lower_file, &buf.ctx);
ctx->pos = buf.ctx.pos; /* XXX: not sure if needed (cf. ecryptfs) */
/* Save the position for when we continue. */
offset = vfs_llseek(lower_file, 0, SEEK_CUR);
if (offset < 0) {
err = offset;
goto out;
}
uds->dirpos = offset;
/* Copy the atime. */
fsstack_copy_attr_atime(inode, file_inode(lower_file));
if (err < 0)
goto out;
if (buf.filldir_error)
break;
if (!buf.entries_written) {
uds->bindex++;
uds->dirpos = 0;
}
}
if (!buf.filldir_error && uds->bindex >= bend) {
/* Save the number of hash entries for next time. */
UNIONFS_I(inode)->hashsize = uds->hashentries;
free_rdstate(uds);
UNIONFS_F(file)->rdstate = NULL;
ctx->pos = DIREOF;
} else {
ctx->pos = rdstate2offset(uds);
}
out:
if (!err)
unionfs_check_file(file);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
/*
* This is not meant to be a generic repositioning function. If you do
* things that aren't supported, then we return EINVAL.
*
* What is allowed:
* (1) seeking to the same position that you are currently at
* This really has no effect, but returns where you are.
* (2) seeking to the beginning of the file
* This throws out all state, and lets you begin again.
*/
static loff_t unionfs_dir_llseek(struct file *file, loff_t offset, int origin)
{
struct unionfs_dir_state *rdstate;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
loff_t err;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, false);
if (unlikely(err))
goto out;
rdstate = UNIONFS_F(file)->rdstate;
/*
* we let users seek to their current position, but not anywhere
* else.
*/
if (!offset) {
switch (origin) {
case SEEK_SET:
if (rdstate) {
free_rdstate(rdstate);
UNIONFS_F(file)->rdstate = NULL;
}
init_rdstate(file);
err = 0;
break;
case SEEK_CUR:
err = file->f_pos;
break;
case SEEK_END:
/* Unsupported, because we would break everything. */
err = -EINVAL;
break;
}
} else {
switch (origin) {
case SEEK_SET:
if (rdstate) {
if (offset == rdstate2offset(rdstate))
err = offset;
else if (file->f_pos == DIREOF)
err = DIREOF;
else
err = -EINVAL;
} else {
struct inode *inode;
inode = dentry->d_inode;
rdstate = find_rdstate(inode, offset);
if (rdstate) {
UNIONFS_F(file)->rdstate = rdstate;
err = rdstate->offset;
} else {
err = -EINVAL;
}
}
break;
case SEEK_CUR:
case SEEK_END:
/* Unsupported, because we would break everything. */
err = -EINVAL;
break;
}
}
out:
if (!err)
unionfs_check_file(file);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
/*
* Trimmed directory options, we shouldn't pass everything down since
* we don't want to operate on partial directories.
*/
struct file_operations unionfs_dir_fops = {
.llseek = unionfs_dir_llseek,
.read = generic_read_dir,
.iterate = unionfs_readdir,
.unlocked_ioctl = unionfs_ioctl,
.open = unionfs_open,
.release = unionfs_file_release,
.flush = unionfs_flush,
.fsync = unionfs_fsync,
.fasync = unionfs_fasync,
};

157
fs/unionfs/dirhelper.c Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
#define RD_NONE 0
#define RD_CHECK_EMPTY 1
/* The callback structure for check_empty. */
struct unionfs_rdutil_callback {
struct dir_context ctx; // NEW: must be first in callback struct
int err;
int filldir_called;
struct unionfs_dir_state *rdstate;
int mode;
};
/* This filldir function makes sure only whiteouts exist within a directory. */
static int readdir_util_callback(void *dirent, const char *oname, int namelen,
loff_t offset, u64 ino, unsigned int d_type)
{
int err = 0;
struct unionfs_rdutil_callback *buf = dirent;
int is_whiteout;
struct filldir_node *found;
char *name = (char *) oname;
buf->filldir_called = 1;
if (name[0] == '.' && (namelen == 1 ||
(name[1] == '.' && namelen == 2)))
goto out;
is_whiteout = is_whiteout_name(&name, &namelen);
found = find_filldir_node(buf->rdstate, name, namelen, is_whiteout);
/* If it was found in the table there was a previous whiteout. */
if (found)
goto out;
/*
* if it wasn't found and isn't a whiteout, the directory isn't
* empty.
*/
err = -ENOTEMPTY;
if ((buf->mode == RD_CHECK_EMPTY) && !is_whiteout)
goto out;
err = add_filldir_node(buf->rdstate, name, namelen,
buf->rdstate->bindex, is_whiteout);
out:
buf->err = err;
return err;
}
/* Is a directory logically empty? */
int check_empty(struct dentry *dentry, struct dentry *parent,
struct unionfs_dir_state **namelist)
{
int err = 0;
struct dentry *lower_dentry = NULL;
struct vfsmount *mnt;
struct super_block *sb;
struct file *lower_file;
struct unionfs_rdutil_callback buf = {
.ctx.actor = readdir_util_callback,
};
int bindex, bstart, bend, bopaque;
struct path path;
sb = dentry->d_sb;
BUG_ON(!S_ISDIR(dentry->d_inode->i_mode));
err = unionfs_partial_lookup(dentry, parent);
if (err)
goto out;
bstart = dbstart(dentry);
bend = dbend(dentry);
bopaque = dbopaque(dentry);
if (0 <= bopaque && bopaque < bend)
bend = bopaque;
buf.err = 0;
buf.filldir_called = 0;
buf.mode = RD_CHECK_EMPTY;
buf.ctx.pos = 0; /* XXX: needed?! */
buf.rdstate = alloc_rdstate(dentry->d_inode, bstart);
if (unlikely(!buf.rdstate)) {
err = -ENOMEM;
goto out;
}
/* Process the lower directories with rdutil_callback as a filldir. */
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
if (!lower_dentry->d_inode)
continue;
if (!S_ISDIR(lower_dentry->d_inode->i_mode))
continue;
dget(lower_dentry);
mnt = unionfs_mntget(dentry, bindex);
branchget(sb, bindex);
path.dentry = lower_dentry;
path.mnt = mnt;
lower_file = dentry_open(&path, O_RDONLY, current_cred());
path_put(&path);
if (IS_ERR(lower_file)) {
err = PTR_ERR(lower_file);
branchput(sb, bindex);
goto out;
}
do {
buf.filldir_called = 0;
buf.rdstate->bindex = bindex;
err = iterate_dir(lower_file, &buf.ctx);
if (buf.err)
err = buf.err;
} while ((err >= 0) && buf.filldir_called);
/* fput calls dput for lower_dentry */
fput(lower_file);
branchput(sb, bindex);
if (err < 0)
goto out;
}
out:
if (namelist && !err)
*namelist = buf.rdstate;
else if (buf.rdstate)
free_rdstate(buf.rdstate);
return err;
}

407
fs/unionfs/fanout.h Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _FANOUT_H_
#define _FANOUT_H_
/*
* Inode to private data
*
* Since we use containers and the struct inode is _inside_ the
* unionfs_inode_info structure, UNIONFS_I will always (given a non-NULL
* inode pointer), return a valid non-NULL pointer.
*/
static inline struct unionfs_inode_info *UNIONFS_I(const struct inode *inode)
{
return container_of(inode, struct unionfs_inode_info, vfs_inode);
}
#define ibstart(ino) (UNIONFS_I(ino)->bstart)
#define ibend(ino) (UNIONFS_I(ino)->bend)
/* Dentry to private data */
#define UNIONFS_D(dent) ((struct unionfs_dentry_info *)(dent)->d_fsdata)
#define dbstart(dent) (UNIONFS_D(dent)->bstart)
#define dbend(dent) (UNIONFS_D(dent)->bend)
#define dbopaque(dent) (UNIONFS_D(dent)->bopaque)
/* Superblock to private data */
#define UNIONFS_SB(super) ((struct unionfs_sb_info *)(super)->s_fs_info)
#define sbstart(sb) 0
#define sbend(sb) (UNIONFS_SB(sb)->bend)
#define sbmax(sb) (UNIONFS_SB(sb)->bend + 1)
#define sbhbid(sb) (UNIONFS_SB(sb)->high_branch_id)
/* File to private Data */
#define UNIONFS_F(file) ((struct unionfs_file_info *)((file)->private_data))
#define fbstart(file) (UNIONFS_F(file)->bstart)
#define fbend(file) (UNIONFS_F(file)->bend)
/* macros to manipulate branch IDs in stored in our superblock */
static inline int branch_id(struct super_block *sb, int index)
{
BUG_ON(!sb || index < 0);
return UNIONFS_SB(sb)->data[index].branch_id;
}
static inline void set_branch_id(struct super_block *sb, int index, int val)
{
BUG_ON(!sb || index < 0);
UNIONFS_SB(sb)->data[index].branch_id = val;
}
static inline void new_branch_id(struct super_block *sb, int index)
{
BUG_ON(!sb || index < 0);
set_branch_id(sb, index, ++UNIONFS_SB(sb)->high_branch_id);
}
/*
* Find new index of matching branch with an existing superblock of a known
* (possibly old) id. This is needed because branches could have been
* added/deleted causing the branches of any open files to shift.
*
* @sb: the new superblock which may have new/different branch IDs
* @id: the old/existing id we're looking for
* Returns index of newly found branch (0 or greater), -1 otherwise.
*/
static inline int branch_id_to_idx(struct super_block *sb, int id)
{
int i;
for (i = 0; i < sbmax(sb); i++) {
if (branch_id(sb, i) == id)
return i;
}
/* in the non-ODF code, this should really never happen */
printk(KERN_WARNING "unionfs: cannot find branch with id %d\n", id);
return -1;
}
/* File to lower file. */
static inline struct file *unionfs_lower_file(const struct file *f)
{
BUG_ON(!f);
return UNIONFS_F(f)->lower_files[fbstart(f)];
}
static inline struct file *unionfs_lower_file_idx(const struct file *f,
int index)
{
BUG_ON(!f || index < 0);
return UNIONFS_F(f)->lower_files[index];
}
static inline void unionfs_set_lower_file_idx(struct file *f, int index,
struct file *val)
{
BUG_ON(!f || index < 0);
UNIONFS_F(f)->lower_files[index] = val;
/* save branch ID (may be redundant?) */
UNIONFS_F(f)->saved_branch_ids[index] =
branch_id((f)->f_path.dentry->d_sb, index);
}
static inline void unionfs_set_lower_file(struct file *f, struct file *val)
{
BUG_ON(!f);
unionfs_set_lower_file_idx((f), fbstart(f), (val));
}
/* Inode to lower inode. */
static inline struct inode *unionfs_lower_inode(const struct inode *i)
{
BUG_ON(!i);
return UNIONFS_I(i)->lower_inodes[ibstart(i)];
}
static inline struct inode *unionfs_lower_inode_idx(const struct inode *i,
int index)
{
BUG_ON(!i || index < 0);
return UNIONFS_I(i)->lower_inodes[index];
}
static inline void unionfs_set_lower_inode_idx(struct inode *i, int index,
struct inode *val)
{
BUG_ON(!i || index < 0);
UNIONFS_I(i)->lower_inodes[index] = val;
}
static inline void unionfs_set_lower_inode(struct inode *i, struct inode *val)
{
BUG_ON(!i);
UNIONFS_I(i)->lower_inodes[ibstart(i)] = val;
}
/* Superblock to lower superblock. */
static inline struct super_block *unionfs_lower_super(
const struct super_block *sb)
{
BUG_ON(!sb);
return UNIONFS_SB(sb)->data[sbstart(sb)].sb;
}
static inline struct super_block *unionfs_lower_super_idx(
const struct super_block *sb,
int index)
{
BUG_ON(!sb || index < 0);
return UNIONFS_SB(sb)->data[index].sb;
}
static inline void unionfs_set_lower_super_idx(struct super_block *sb,
int index,
struct super_block *val)
{
BUG_ON(!sb || index < 0);
UNIONFS_SB(sb)->data[index].sb = val;
}
static inline void unionfs_set_lower_super(struct super_block *sb,
struct super_block *val)
{
BUG_ON(!sb);
UNIONFS_SB(sb)->data[sbstart(sb)].sb = val;
}
/* Branch count macros. */
static inline int branch_count(const struct super_block *sb, int index)
{
BUG_ON(!sb || index < 0);
return atomic_read(&UNIONFS_SB(sb)->data[index].open_files);
}
static inline void set_branch_count(struct super_block *sb, int index, int val)
{
BUG_ON(!sb || index < 0);
atomic_set(&UNIONFS_SB(sb)->data[index].open_files, val);
}
static inline void branchget(struct super_block *sb, int index)
{
BUG_ON(!sb || index < 0);
atomic_inc(&UNIONFS_SB(sb)->data[index].open_files);
}
static inline void branchput(struct super_block *sb, int index)
{
BUG_ON(!sb || index < 0);
atomic_dec(&UNIONFS_SB(sb)->data[index].open_files);
}
/* Dentry macros */
static inline void unionfs_set_lower_dentry_idx(struct dentry *dent, int index,
struct dentry *val)
{
BUG_ON(!dent || index < 0);
UNIONFS_D(dent)->lower_paths[index].dentry = val;
}
static inline struct dentry *unionfs_lower_dentry_idx(
const struct dentry *dent,
int index)
{
BUG_ON(!dent || index < 0);
return UNIONFS_D(dent)->lower_paths[index].dentry;
}
static inline struct dentry *unionfs_lower_dentry(const struct dentry *dent)
{
BUG_ON(!dent);
return unionfs_lower_dentry_idx(dent, dbstart(dent));
}
static inline void unionfs_set_lower_mnt_idx(struct dentry *dent, int index,
struct vfsmount *mnt)
{
BUG_ON(!dent || index < 0);
UNIONFS_D(dent)->lower_paths[index].mnt = mnt;
}
static inline struct vfsmount *unionfs_lower_mnt_idx(
const struct dentry *dent,
int index)
{
BUG_ON(!dent || index < 0);
return UNIONFS_D(dent)->lower_paths[index].mnt;
}
static inline struct vfsmount *unionfs_lower_mnt(const struct dentry *dent)
{
BUG_ON(!dent);
return unionfs_lower_mnt_idx(dent, dbstart(dent));
}
/* Macros for locking a dentry. */
enum unionfs_dentry_lock_class {
UNIONFS_DMUTEX_NORMAL,
UNIONFS_DMUTEX_ROOT,
UNIONFS_DMUTEX_PARENT,
UNIONFS_DMUTEX_CHILD,
UNIONFS_DMUTEX_WHITEOUT,
UNIONFS_DMUTEX_REVAL_PARENT, /* for file/dentry revalidate */
UNIONFS_DMUTEX_REVAL_CHILD, /* for file/dentry revalidate */
};
static inline void unionfs_lock_dentry(struct dentry *d,
unsigned int subclass)
{
BUG_ON(!d);
mutex_lock_nested(&UNIONFS_D(d)->lock, subclass);
}
static inline void unionfs_unlock_dentry(struct dentry *d)
{
BUG_ON(!d);
mutex_unlock(&UNIONFS_D(d)->lock);
}
static inline struct dentry *unionfs_lock_parent(struct dentry *d,
unsigned int subclass)
{
struct dentry *p;
BUG_ON(!d);
p = dget_parent(d);
if (p != d)
mutex_lock_nested(&UNIONFS_D(p)->lock, subclass);
return p;
}
static inline void unionfs_unlock_parent(struct dentry *d, struct dentry *p)
{
BUG_ON(!d);
BUG_ON(!p);
if (p != d) {
BUG_ON(!mutex_is_locked(&UNIONFS_D(p)->lock));
mutex_unlock(&UNIONFS_D(p)->lock);
}
dput(p);
}
static inline void verify_locked(struct dentry *d)
{
BUG_ON(!d);
BUG_ON(!mutex_is_locked(&UNIONFS_D(d)->lock));
}
/* macros to put lower objects */
/*
* iput lower inodes of an unionfs dentry, from bstart to bend. If
* @free_lower is true, then also kfree the memory used to hold the lower
* object pointers.
*/
static inline void iput_lowers(struct inode *inode,
int bstart, int bend, bool free_lower)
{
struct inode *lower_inode;
int bindex;
BUG_ON(!inode);
BUG_ON(!UNIONFS_I(inode));
BUG_ON(bstart < 0);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (lower_inode) {
unionfs_set_lower_inode_idx(inode, bindex, NULL);
/* see Documentation/filesystems/unionfs/issues.txt */
lockdep_off();
iput(lower_inode);
lockdep_on();
}
}
if (free_lower) {
kfree(UNIONFS_I(inode)->lower_inodes);
UNIONFS_I(inode)->lower_inodes = NULL;
}
}
/* iput all lower inodes, and reset start/end branch indices to -1 */
static inline void iput_lowers_all(struct inode *inode, bool free_lower)
{
int bstart, bend;
BUG_ON(!inode);
BUG_ON(!UNIONFS_I(inode));
bstart = ibstart(inode);
bend = ibend(inode);
BUG_ON(bstart < 0);
iput_lowers(inode, bstart, bend, free_lower);
ibstart(inode) = ibend(inode) = -1;
}
/*
* dput/mntput all lower dentries and vfsmounts of an unionfs dentry, from
* bstart to bend. If @free_lower is true, then also kfree the memory used
* to hold the lower object pointers.
*
* XXX: implement using path_put VFS macros
*/
static inline void path_put_lowers(struct dentry *dentry,
int bstart, int bend, bool free_lower)
{
struct dentry *lower_dentry;
struct vfsmount *lower_mnt;
int bindex;
BUG_ON(!dentry);
BUG_ON(!UNIONFS_D(dentry));
BUG_ON(bstart < 0);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (lower_dentry) {
unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
dput(lower_dentry);
}
lower_mnt = unionfs_lower_mnt_idx(dentry, bindex);
if (lower_mnt) {
unionfs_set_lower_mnt_idx(dentry, bindex, NULL);
mntput(lower_mnt);
}
}
if (free_lower) {
kfree(UNIONFS_D(dentry)->lower_paths);
UNIONFS_D(dentry)->lower_paths = NULL;
}
}
/*
* dput/mntput all lower dentries and vfsmounts, and reset start/end branch
* indices to -1.
*/
static inline void path_put_lowers_all(struct dentry *dentry, bool free_lower)
{
int bstart, bend;
BUG_ON(!dentry);
BUG_ON(!UNIONFS_D(dentry));
bstart = dbstart(dentry);
bend = dbend(dentry);
BUG_ON(bstart < 0);
path_put_lowers(dentry, bstart, bend, free_lower);
dbstart(dentry) = dbend(dentry) = -1;
}
#endif /* not _FANOUT_H */

471
fs/unionfs/file.c Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
static ssize_t unionfs_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
int err;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, false);
if (unlikely(err))
goto out;
lower_file = unionfs_lower_file(file);
err = vfs_read(lower_file, buf, count, ppos);
/* update our inode atime upon a successful lower read */
if (err >= 0) {
fsstack_copy_attr_atime(dentry->d_inode,
file_inode(lower_file));
unionfs_check_file(file);
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static ssize_t unionfs_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
int err = 0;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
lower_file = unionfs_lower_file(file);
err = vfs_write(lower_file, buf, count, ppos);
/* update our inode times+sizes upon a successful lower write */
if (err >= 0) {
fsstack_copy_inode_size(dentry->d_inode,
file_inode(lower_file));
fsstack_copy_attr_times(dentry->d_inode,
file_inode(lower_file));
UNIONFS_F(file)->wrote_to_file = true; /* for delayed copyup */
unionfs_check_file(file);
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static ssize_t unionfs_aio_read(struct kiocb *iocb, const struct iovec
*iov, unsigned long nr_segs, loff_t pos)
{
int err = -EINVAL;
struct file *file = iocb->ki_filp, *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
lower_file = unionfs_lower_file(file);
if (!lower_file->f_op->aio_read)
goto out;
get_file(lower_file);
iocb->ki_filp = lower_file;
err = lower_file->f_op->aio_read(iocb, iov, nr_segs, pos);
iocb->ki_filp = file;
fput(lower_file);
/* update our inode atime upon a successful lower read */
/* XXX: need to update upper inode atime when AIO completes */
if (err >= 0) {
fsstack_copy_attr_atime(dentry->d_inode,
file_inode(lower_file));
unionfs_check_file(file);
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static ssize_t unionfs_aio_write(struct kiocb *iocb, const struct iovec
*iov, unsigned long nr_segs, loff_t pos)
{
int err = -EINVAL;
struct file *file = iocb->ki_filp, *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
lower_file = unionfs_lower_file(file);
if (!lower_file->f_op->aio_write)
goto out;
get_file(lower_file);
iocb->ki_filp = lower_file;
err = lower_file->f_op->aio_write(iocb, iov, nr_segs, pos);
iocb->ki_filp = file;
fput(lower_file);
/* update our inode times+sizes upon a successful lower write */
/* XXX: need to update upper inode times/sizes when AIO completes */
if (err >= 0) {
fsstack_copy_inode_size(dentry->d_inode,
file_inode(lower_file));
fsstack_copy_attr_times(dentry->d_inode,
file_inode(lower_file));
UNIONFS_F(file)->wrote_to_file = true; /* for delayed copyup */
unionfs_check_file(file);
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static int unionfs_file_readdir(struct file *file, struct dir_context *ctx)
{
return -ENOTDIR;
}
static int unionfs_mmap(struct file *file, struct vm_area_struct *vma)
{
int err = 0;
bool willwrite;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
const struct vm_operations_struct *saved_vm_ops = NULL;
/*
* Since mm/memory.c:might_fault() (under PROVE_LOCKING) was
* modified in 2.6.29-rc1 to call might_lock_read on mmap_sem, this
* has been causing false positives in file system stacking layers.
* In particular, our ->mmap is called after sys_mmap2 already holds
* mmap_sem, then we lock our own mutexes; but earlier, it's
* possible for lockdep to have locked our mutexes first, and then
* we call a lower ->readdir which could call might_fault. The
* different ordering of the locks is what lockdep complains about
* -- unnecessarily. Therefore, we have no choice but to tell
* lockdep to temporarily turn off lockdep here. Note: the comments
* inside might_sleep also suggest that it would have been
* nicer to only annotate paths that needs that might_lock_read.
*/
lockdep_off();
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
/* This might be deferred to mmap's writepage */
willwrite = ((vma->vm_flags | VM_SHARED | VM_WRITE) == vma->vm_flags);
err = unionfs_file_revalidate(file, parent, willwrite);
if (unlikely(err))
goto out;
unionfs_check_file(file);
/*
* File systems which do not implement ->writepage may use
* generic_file_readonly_mmap as their ->mmap op. If you call
* generic_file_readonly_mmap with VM_WRITE, you'd get an -EINVAL.
* But we cannot call the lower ->mmap op, so we can't tell that
* writeable mappings won't work. Therefore, our only choice is to
* check if the lower file system supports the ->writepage, and if
* not, return EINVAL (the same error that
* generic_file_readonly_mmap returns in that case).
*/
lower_file = unionfs_lower_file(file);
if (willwrite && !lower_file->f_mapping->a_ops->writepage) {
err = -EINVAL;
printk(KERN_ERR "unionfs: branch %d file system does not "
"support writeable mmap\n", fbstart(file));
goto out;
}
/*
* find and save lower vm_ops.
*
* XXX: the VFS should have a cleaner way of finding the lower vm_ops
*/
if (!UNIONFS_F(file)->lower_vm_ops) {
err = lower_file->f_op->mmap(lower_file, vma);
if (err) {
printk(KERN_ERR "unionfs: lower mmap failed %d\n", err);
goto out;
}
saved_vm_ops = vma->vm_ops;
up_write(&current->mm->mmap_sem); /* VFS already holds sema... */
err = vm_munmap(vma->vm_start, vma->vm_end - vma->vm_start);
down_write(&current->mm->mmap_sem);
if (err) {
printk(KERN_ERR "unionfs: do_munmap failed %d\n", err);
goto out;
}
}
file->f_mapping->a_ops = &unionfs_dummy_aops;
err = generic_file_mmap(file, vma);
file->f_mapping->a_ops = &unionfs_aops;
if (err) {
printk(KERN_ERR "unionfs: generic_file_mmap failed %d\n", err);
goto out;
}
vma->vm_ops = &unionfs_vm_ops;
if (!UNIONFS_F(file)->lower_vm_ops)
UNIONFS_F(file)->lower_vm_ops = saved_vm_ops;
out:
if (!err) {
/* copyup could cause parent dir times to change */
unionfs_copy_attr_times(parent->d_inode);
unionfs_check_file(file);
}
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
lockdep_on();
return err;
}
int unionfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
int bindex, bstart, bend;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *lower_dentry;
struct dentry *parent;
struct inode *lower_inode, *inode;
int err = -EINVAL;
lockdep_off();
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
unionfs_check_file(file);
err = generic_file_fsync(file, start, end, datasync);
if (err)
goto out;
bstart = fbstart(file);
bend = fbend(file);
if (bstart < 0 || bend < 0)
goto out;
inode = dentry->d_inode;
if (unlikely(!inode)) {
printk(KERN_ERR
"unionfs: null lower inode in unionfs_fsync\n");
goto out;
}
for (bindex = bstart; bindex <= bend; bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (!lower_inode || !lower_inode->i_fop->fsync)
continue;
lower_file = unionfs_lower_file_idx(file, bindex);
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
err = vfs_fsync_range(lower_file, start, end, datasync);
if (!err && bindex == bstart)
fsstack_copy_attr_times(inode, lower_inode);
if (err)
goto out;
}
out:
if (!err)
unionfs_check_file(file);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
lockdep_on();
return err;
}
int unionfs_fasync(int fd, struct file *file, int flag)
{
int bindex, bstart, bend;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
struct inode *lower_inode, *inode;
int err = 0;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
unionfs_check_file(file);
bstart = fbstart(file);
bend = fbend(file);
if (bstart < 0 || bend < 0)
goto out;
inode = dentry->d_inode;
if (unlikely(!inode)) {
printk(KERN_ERR
"unionfs: null lower inode in unionfs_fasync\n");
goto out;
}
for (bindex = bstart; bindex <= bend; bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (!lower_inode || !lower_inode->i_fop->fasync)
continue;
lower_file = unionfs_lower_file_idx(file, bindex);
mutex_lock(&lower_inode->i_mutex);
err = lower_inode->i_fop->fasync(fd, lower_file, flag);
if (!err && bindex == bstart)
fsstack_copy_attr_times(inode, lower_inode);
mutex_unlock(&lower_inode->i_mutex);
if (err)
goto out;
}
out:
if (!err)
unionfs_check_file(file);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static ssize_t unionfs_splice_read(struct file *file, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
ssize_t err;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, false);
if (unlikely(err))
goto out;
lower_file = unionfs_lower_file(file);
err = vfs_splice_to(lower_file, ppos, pipe, len, flags);
/* update our inode atime upon a successful lower splice-read */
if (err >= 0) {
fsstack_copy_attr_atime(dentry->d_inode,
file_inode(lower_file));
unionfs_check_file(file);
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static ssize_t unionfs_splice_write(struct pipe_inode_info *pipe,
struct file *file, loff_t *ppos,
size_t len, unsigned int flags)
{
ssize_t err = 0;
struct file *lower_file;
struct dentry *dentry = file->f_path.dentry;
struct dentry *parent;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_PARENT);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
err = unionfs_file_revalidate(file, parent, true);
if (unlikely(err))
goto out;
lower_file = unionfs_lower_file(file);
err = vfs_splice_from(pipe, lower_file, ppos, len, flags);
/* update our inode times+sizes upon a successful lower write */
if (err >= 0) {
fsstack_copy_inode_size(dentry->d_inode,
file_inode(lower_file));
fsstack_copy_attr_times(dentry->d_inode,
file_inode(lower_file));
unionfs_check_file(file);
}
out:
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
struct file_operations unionfs_main_fops = {
.llseek = generic_file_llseek,
.read = unionfs_read,
.write = unionfs_write,
.aio_read = unionfs_aio_read,
.aio_write = unionfs_aio_write,
.iterate = unionfs_file_readdir,
.unlocked_ioctl = unionfs_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = unionfs_ioctl,
#endif
.mmap = unionfs_mmap,
.open = unionfs_open,
.flush = unionfs_flush,
.release = unionfs_file_release,
.fsync = unionfs_fsync,
.fasync = unionfs_fasync,
.splice_read = unionfs_splice_read,
.splice_write = unionfs_splice_write,
};

1110
fs/unionfs/inode.c Normal file
View File

File diff suppressed because it is too large Load Diff

501
fs/unionfs/lookup.c Normal file
View File

@ -0,0 +1,501 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* Lookup one path component @name relative to a <base,mnt> path pair.
* Behaves nearly the same as lookup_one_len (i.e., return negative dentry
* on ENOENT), but uses the @mnt passed, so it can cross bind mounts and
* other lower mounts properly. If @new_mnt is non-null, will fill in the
* new mnt there. Caller is responsible to dput/mntput/path_put returned
* @dentry and @new_mnt.
*/
struct dentry *__lookup_one(struct dentry *base, struct vfsmount *mnt,
const char *name, struct vfsmount **new_mnt)
{
struct dentry *dentry = NULL;
struct path lower_path = {NULL, NULL};
int err;
/* we use flags=0 to get basic lookup */
err = vfs_path_lookup(base, mnt, name, 0, &lower_path);
switch (err) {
case 0: /* no error */
dentry = lower_path.dentry;
if (new_mnt)
*new_mnt = lower_path.mnt; /* rc already inc'ed */
break;
case -ENOENT:
/*
* We don't consider ENOENT an error, and we want to return
* a negative dentry (ala lookup_one_len). As we know
* there was no inode for this name before (-ENOENT), then
* it's safe to call lookup_one_len (which doesn't take a
* vfsmount).
*/
dentry = lookup_lck_len(name, base, strlen(name));
if (new_mnt)
*new_mnt = mntget(lower_path.mnt);
break;
default: /* all other real errors */
dentry = ERR_PTR(err);
break;
}
return dentry;
}
/*
* This is a utility function that fills in a unionfs dentry.
* Caller must lock this dentry with unionfs_lock_dentry.
*
* Returns: 0 (ok), or -ERRNO if an error occurred.
* XXX: get rid of _partial_lookup and make callers call _lookup_full directly
*/
int unionfs_partial_lookup(struct dentry *dentry, struct dentry *parent)
{
struct dentry *tmp;
int err = -ENOSYS;
tmp = unionfs_lookup_full(dentry, parent, INTERPOSE_PARTIAL);
if (!tmp) {
err = 0;
goto out;
}
if (IS_ERR(tmp)) {
err = PTR_ERR(tmp);
goto out;
}
/* XXX: need to change the interface */
BUG_ON(tmp != dentry);
out:
return err;
}
/* The dentry cache is just so we have properly sized dentries. */
static struct kmem_cache *unionfs_dentry_cachep;
int unionfs_init_dentry_cache(void)
{
unionfs_dentry_cachep =
kmem_cache_create("unionfs_dentry",
sizeof(struct unionfs_dentry_info),
0, SLAB_RECLAIM_ACCOUNT, NULL);
return (unionfs_dentry_cachep ? 0 : -ENOMEM);
}
void unionfs_destroy_dentry_cache(void)
{
if (unionfs_dentry_cachep)
kmem_cache_destroy(unionfs_dentry_cachep);
}
void free_dentry_private_data(struct dentry *dentry)
{
if (!dentry || !dentry->d_fsdata)
return;
kfree(UNIONFS_D(dentry)->lower_paths);
UNIONFS_D(dentry)->lower_paths = NULL;
kmem_cache_free(unionfs_dentry_cachep, dentry->d_fsdata);
dentry->d_fsdata = NULL;
}
static inline int __realloc_dentry_private_data(struct dentry *dentry)
{
struct unionfs_dentry_info *info = UNIONFS_D(dentry);
void *p;
int size;
BUG_ON(!info);
size = sizeof(struct path) * sbmax(dentry->d_sb);
p = krealloc(info->lower_paths, size, GFP_ATOMIC);
if (unlikely(!p))
return -ENOMEM;
info->lower_paths = p;
info->bstart = -1;
info->bend = -1;
info->bopaque = -1;
info->bcount = sbmax(dentry->d_sb);
atomic_set(&info->generation,
atomic_read(&UNIONFS_SB(dentry->d_sb)->generation));
memset(info->lower_paths, 0, size);
return 0;
}
/* UNIONFS_D(dentry)->lock must be locked */
int realloc_dentry_private_data(struct dentry *dentry)
{
if (!__realloc_dentry_private_data(dentry))
return 0;
kfree(UNIONFS_D(dentry)->lower_paths);
free_dentry_private_data(dentry);
return -ENOMEM;
}
/* allocate new dentry private data */
int new_dentry_private_data(struct dentry *dentry, int subclass)
{
struct unionfs_dentry_info *info = UNIONFS_D(dentry);
BUG_ON(info);
info = kmem_cache_alloc(unionfs_dentry_cachep, GFP_ATOMIC);
if (unlikely(!info))
return -ENOMEM;
mutex_init(&info->lock);
mutex_lock_nested(&info->lock, subclass);
info->lower_paths = NULL;
dentry->d_fsdata = info;
if (!__realloc_dentry_private_data(dentry))
return 0;
mutex_unlock(&info->lock);
free_dentry_private_data(dentry);
return -ENOMEM;
}
/*
* scan through the lower dentry objects, and set bstart to reflect the
* starting branch
*/
void update_bstart(struct dentry *dentry)
{
int bindex;
int bstart = dbstart(dentry);
int bend = dbend(dentry);
struct dentry *lower_dentry;
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
if (lower_dentry->d_inode) {
dbstart(dentry) = bindex;
break;
}
dput(lower_dentry);
unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
}
}
/*
* Main (and complex) driver function for Unionfs's lookup
*
* Returns: NULL (ok), ERR_PTR if an error occurred, or a non-null non-error
* PTR if d_splice returned a different dentry.
*
* If lookupmode is INTERPOSE_PARTIAL/REVAL/REVAL_NEG, the passed dentry's
* inode info must be locked. If lookupmode is INTERPOSE_LOOKUP (i.e., a
* newly looked-up dentry), then unionfs_lookup_backend will return a locked
* dentry's info, which the caller must unlock.
*/
struct dentry *unionfs_lookup_full(struct dentry *dentry,
struct dentry *parent, int lookupmode)
{
int err = 0;
struct dentry *lower_dentry = NULL;
struct vfsmount *lower_mnt;
struct vfsmount *lower_dir_mnt;
struct dentry *wh_lower_dentry = NULL;
struct dentry *lower_dir_dentry = NULL;
struct dentry *d_interposed = NULL;
int bindex, bstart, bend, bopaque;
int opaque, num_positive = 0;
const char *name;
int namelen;
int pos_start, pos_end;
/*
* We should already have a lock on this dentry in the case of a
* partial lookup, or a revalidation. Otherwise it is returned from
* new_dentry_private_data already locked.
*/
verify_locked(dentry);
verify_locked(parent);
/* must initialize dentry operations */
if (lookupmode == INTERPOSE_LOOKUP)
d_set_d_op(dentry, &unionfs_dops);
/* We never partial lookup the root directory. */
if (IS_ROOT(dentry))
goto out;
name = dentry->d_name.name;
namelen = dentry->d_name.len;
/* No dentries should get created for possible whiteout names. */
if (!is_validname(name)) {
err = -EPERM;
goto out_free;
}
/* Now start the actual lookup procedure. */
bstart = dbstart(parent);
bend = dbend(parent);
bopaque = dbopaque(parent);
BUG_ON(bstart < 0);
/* adjust bend to bopaque if needed */
if ((bopaque >= 0) && (bopaque < bend))
bend = bopaque;
/* lookup all possible dentries */
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
lower_mnt = unionfs_lower_mnt_idx(dentry, bindex);
/* skip if we already have a positive lower dentry */
if (lower_dentry) {
if (dbstart(dentry) < 0)
dbstart(dentry) = bindex;
if (bindex > dbend(dentry))
dbend(dentry) = bindex;
if (lower_dentry->d_inode)
num_positive++;
continue;
}
lower_dir_dentry =
unionfs_lower_dentry_idx(parent, bindex);
/* if the lower dentry's parent does not exist, skip this */
if (!lower_dir_dentry || !lower_dir_dentry->d_inode)
continue;
/* also skip it if the parent isn't a directory. */
if (!S_ISDIR(lower_dir_dentry->d_inode->i_mode))
continue; /* XXX: should be BUG_ON */
/* check for whiteouts: stop lookup if found */
wh_lower_dentry = lookup_whiteout(name, lower_dir_dentry);
if (IS_ERR(wh_lower_dentry)) {
err = PTR_ERR(wh_lower_dentry);
goto out_free;
}
if (wh_lower_dentry->d_inode) {
dbend(dentry) = dbopaque(dentry) = bindex;
if (dbstart(dentry) < 0)
dbstart(dentry) = bindex;
dput(wh_lower_dentry);
break;
}
dput(wh_lower_dentry);
/* Now do regular lookup; lookup @name */
lower_dir_mnt = unionfs_lower_mnt_idx(parent, bindex);
lower_mnt = NULL; /* XXX: needed? */
lower_dentry = __lookup_one(lower_dir_dentry, lower_dir_mnt,
name, &lower_mnt);
if (IS_ERR(lower_dentry)) {
err = PTR_ERR(lower_dentry);
goto out_free;
}
unionfs_set_lower_dentry_idx(dentry, bindex, lower_dentry);
if (!lower_mnt)
lower_mnt = unionfs_mntget(dentry->d_sb->s_root,
bindex);
unionfs_set_lower_mnt_idx(dentry, bindex, lower_mnt);
/* adjust dbstart/end */
if (dbstart(dentry) < 0)
dbstart(dentry) = bindex;
if (bindex > dbend(dentry))
dbend(dentry) = bindex;
/*
* We always store the lower dentries above, and update
* dbstart/dbend, even if the whole unionfs dentry is
* negative (i.e., no lower inodes).
*/
if (!lower_dentry->d_inode)
continue;
num_positive++;
/*
* check if we just found an opaque directory, if so, stop
* lookups here.
*/
if (!S_ISDIR(lower_dentry->d_inode->i_mode))
continue;
opaque = is_opaque_dir(dentry, bindex);
if (opaque < 0) {
err = opaque;
goto out_free;
} else if (opaque) {
dbend(dentry) = dbopaque(dentry) = bindex;
break;
}
dbend(dentry) = bindex;
/* update parent directory's atime with the bindex */
fsstack_copy_attr_atime(parent->d_inode,
lower_dir_dentry->d_inode);
}
/* sanity checks, then decide if to process a negative dentry */
BUG_ON(dbstart(dentry) < 0 && dbend(dentry) >= 0);
BUG_ON(dbstart(dentry) >= 0 && dbend(dentry) < 0);
if (num_positive > 0)
goto out_positive;
/*** handle NEGATIVE dentries ***/
/*
* If negative, keep only first lower negative dentry, to save on
* memory.
*/
if (dbstart(dentry) < dbend(dentry)) {
path_put_lowers(dentry, dbstart(dentry) + 1,
dbend(dentry), false);
dbend(dentry) = dbstart(dentry);
}
if (lookupmode == INTERPOSE_PARTIAL)
goto out;
if (lookupmode == INTERPOSE_LOOKUP) {
/*
* If all we found was a whiteout in the first available
* branch, then create a negative dentry for a possibly new
* file to be created.
*/
if (dbopaque(dentry) < 0)
goto out;
/* XXX: need to get mnt here */
bindex = dbstart(dentry);
if (unionfs_lower_dentry_idx(dentry, bindex))
goto out;
lower_dir_dentry =
unionfs_lower_dentry_idx(parent, bindex);
if (!lower_dir_dentry || !lower_dir_dentry->d_inode)
goto out;
if (!S_ISDIR(lower_dir_dentry->d_inode->i_mode))
goto out; /* XXX: should be BUG_ON */
/* XXX: do we need to cross bind mounts here? */
lower_dentry = lookup_lck_len(name, lower_dir_dentry, namelen);
if (IS_ERR(lower_dentry)) {
err = PTR_ERR(lower_dentry);
goto out;
}
/* XXX: need to mntget/mntput as needed too! */
unionfs_set_lower_dentry_idx(dentry, bindex, lower_dentry);
/* XXX: wrong mnt for crossing bind mounts! */
lower_mnt = unionfs_mntget(dentry->d_sb->s_root, bindex);
unionfs_set_lower_mnt_idx(dentry, bindex, lower_mnt);
goto out;
}
/* if we're revalidating a positive dentry, don't make it negative */
if (lookupmode != INTERPOSE_REVAL)
d_add(dentry, NULL);
goto out;
out_positive:
/*** handle POSITIVE dentries ***/
/*
* This unionfs dentry is positive (at least one lower inode
* exists), so scan entire dentry from beginning to end, and remove
* any negative lower dentries, if any. Then, update dbstart/dbend
* to reflect the start/end of positive dentries.
*/
pos_start = pos_end = -1;
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry,
bindex);
if (lower_dentry && lower_dentry->d_inode) {
if (pos_start < 0)
pos_start = bindex;
if (bindex > pos_end)
pos_end = bindex;
continue;
}
path_put_lowers(dentry, bindex, bindex, false);
}
if (pos_start >= 0)
dbstart(dentry) = pos_start;
if (pos_end >= 0)
dbend(dentry) = pos_end;
/* Partial lookups need to re-interpose, or throw away older negs. */
if (lookupmode == INTERPOSE_PARTIAL) {
if (dentry->d_inode) {
unionfs_reinterpose(dentry);
goto out;
}
/*
* This dentry was positive, so it is as if we had a
* negative revalidation.
*/
lookupmode = INTERPOSE_REVAL_NEG;
update_bstart(dentry);
}
/*
* Interpose can return a dentry if d_splice returned a different
* dentry.
*/
d_interposed = unionfs_interpose(dentry, dentry->d_sb, lookupmode);
if (IS_ERR(d_interposed))
err = PTR_ERR(d_interposed);
else if (d_interposed)
dentry = d_interposed;
if (!err)
goto out;
d_drop(dentry);
out_free:
/* should dput/mntput all the underlying dentries on error condition */
if (dbstart(dentry) >= 0)
path_put_lowers_all(dentry, false);
/* free lower_paths unconditionally */
kfree(UNIONFS_D(dentry)->lower_paths);
UNIONFS_D(dentry)->lower_paths = NULL;
out:
if (dentry && UNIONFS_D(dentry)) {
BUG_ON(dbstart(dentry) < 0 && dbend(dentry) >= 0);
BUG_ON(dbstart(dentry) >= 0 && dbend(dentry) < 0);
}
if (d_interposed && UNIONFS_D(d_interposed)) {
BUG_ON(dbstart(d_interposed) < 0 && dbend(d_interposed) >= 0);
BUG_ON(dbstart(d_interposed) >= 0 && dbend(d_interposed) < 0);
}
if (!err && d_interposed)
return d_interposed;
return ERR_PTR(err);
}

764
fs/unionfs/main.c Normal file
View File

@ -0,0 +1,764 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
#include <linux/module.h>
#include <linux/moduleparam.h>
static void unionfs_fill_inode(struct dentry *dentry,
struct inode *inode)
{
struct inode *lower_inode;
struct dentry *lower_dentry;
int bindex, bstart, bend;
bstart = dbstart(dentry);
bend = dbend(dentry);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry) {
unionfs_set_lower_inode_idx(inode, bindex, NULL);
continue;
}
/* Initialize the lower inode to the new lower inode. */
if (!lower_dentry->d_inode)
continue;
unionfs_set_lower_inode_idx(inode, bindex,
igrab(lower_dentry->d_inode));
}
ibstart(inode) = dbstart(dentry);
ibend(inode) = dbend(dentry);
/* Use attributes from the first branch. */
lower_inode = unionfs_lower_inode(inode);
/* Use different set of inode ops for symlinks & directories */
if (S_ISLNK(lower_inode->i_mode))
inode->i_op = &unionfs_symlink_iops;
else if (S_ISDIR(lower_inode->i_mode))
inode->i_op = &unionfs_dir_iops;
/* Use different set of file ops for directories */
if (S_ISDIR(lower_inode->i_mode))
inode->i_fop = &unionfs_dir_fops;
/* properly initialize special inodes */
if (S_ISBLK(lower_inode->i_mode) || S_ISCHR(lower_inode->i_mode) ||
S_ISFIFO(lower_inode->i_mode) || S_ISSOCK(lower_inode->i_mode))
init_special_inode(inode, lower_inode->i_mode,
lower_inode->i_rdev);
/* all well, copy inode attributes */
unionfs_copy_attr_all(inode, lower_inode);
fsstack_copy_inode_size(inode, lower_inode);
}
/*
* Connect a unionfs inode dentry/inode with several lower ones. This is
* the classic stackable file system "vnode interposition" action.
*
* @sb: unionfs's super_block
*/
struct dentry *unionfs_interpose(struct dentry *dentry, struct super_block *sb,
int flag)
{
int err = 0;
struct inode *inode;
int need_fill_inode = 1;
struct dentry *spliced = NULL;
verify_locked(dentry);
/*
* We allocate our new inode below by calling unionfs_iget,
* which will initialize some of the new inode's fields
*/
/*
* On revalidate we've already got our own inode and just need
* to fix it up.
*/
if (flag == INTERPOSE_REVAL) {
inode = dentry->d_inode;
UNIONFS_I(inode)->bstart = -1;
UNIONFS_I(inode)->bend = -1;
atomic_set(&UNIONFS_I(inode)->generation,
atomic_read(&UNIONFS_SB(sb)->generation));
UNIONFS_I(inode)->lower_inodes =
kcalloc(sbmax(sb), sizeof(struct inode *), GFP_KERNEL);
if (unlikely(!UNIONFS_I(inode)->lower_inodes)) {
err = -ENOMEM;
goto out;
}
} else {
/* get unique inode number for unionfs */
inode = unionfs_iget(sb, iunique(sb, UNIONFS_ROOT_INO));
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out;
}
if (atomic_read(&inode->i_count) > 1)
goto skip;
}
need_fill_inode = 0;
unionfs_fill_inode(dentry, inode);
skip:
/* only (our) lookup wants to do a d_add */
switch (flag) {
case INTERPOSE_DEFAULT:
/* for operations which create new inodes */
d_add(dentry, inode);
break;
case INTERPOSE_REVAL_NEG:
d_instantiate(dentry, inode);
break;
case INTERPOSE_LOOKUP:
spliced = d_splice_alias(inode, dentry);
if (spliced && spliced != dentry) {
/*
* d_splice can return a dentry if it was
* disconnected and had to be moved. We must ensure
* that the private data of the new dentry is
* correct and that the inode info was filled
* properly. Finally we must return this new
* dentry.
*/
d_set_d_op(spliced, &unionfs_dops);
spliced->d_fsdata = dentry->d_fsdata;
dentry->d_fsdata = NULL;
dentry = spliced;
if (need_fill_inode) {
need_fill_inode = 0;
unionfs_fill_inode(dentry, inode);
}
goto out_spliced;
} else if (!spliced) {
if (need_fill_inode) {
need_fill_inode = 0;
unionfs_fill_inode(dentry, inode);
goto out_spliced;
}
}
break;
case INTERPOSE_REVAL:
/* Do nothing. */
break;
default:
printk(KERN_CRIT "unionfs: invalid interpose flag passed!\n");
BUG();
}
goto out;
out_spliced:
if (!err)
return spliced;
out:
return ERR_PTR(err);
}
/* like interpose above, but for an already existing dentry */
void unionfs_reinterpose(struct dentry *dentry)
{
struct dentry *lower_dentry;
struct inode *inode;
int bindex, bstart, bend;
verify_locked(dentry);
/* This is pre-allocated inode */
inode = dentry->d_inode;
bstart = dbstart(dentry);
bend = dbend(dentry);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry)
continue;
if (!lower_dentry->d_inode)
continue;
if (unionfs_lower_inode_idx(inode, bindex))
continue;
unionfs_set_lower_inode_idx(inode, bindex,
igrab(lower_dentry->d_inode));
}
ibstart(inode) = dbstart(dentry);
ibend(inode) = dbend(dentry);
}
/*
* make sure the branch we just looked up (nd) makes sense:
*
* 1) we're not trying to stack unionfs on top of unionfs
* 2) it exists
* 3) is a directory
*/
int check_branch(const struct path *path)
{
/* XXX: remove in ODF code -- stacking unions allowed there */
if (!strcmp(path->dentry->d_sb->s_type->name, UNIONFS_NAME))
return -EINVAL;
if (!path->dentry->d_inode)
return -ENOENT;
if (!S_ISDIR(path->dentry->d_inode->i_mode))
return -ENOTDIR;
return 0;
}
/* checks if two lower_dentries have overlapping branches */
static int is_branch_overlap(struct dentry *dent1, struct dentry *dent2)
{
struct dentry *dent = NULL;
dent = dent1;
while ((dent != dent2) && (dent->d_parent != dent))
dent = dent->d_parent;
if (dent == dent2)
return 1;
dent = dent2;
while ((dent != dent1) && (dent->d_parent != dent))
dent = dent->d_parent;
return (dent == dent1);
}
/*
* Parse "ro" or "rw" options, but default to "rw" if no mode options was
* specified. Fill the mode bits in @perms. If encounter an unknown
* string, return -EINVAL. Otherwise return 0.
*/
int parse_branch_mode(const char *name, int *perms)
{
if (!name || !strcmp(name, "rw")) {
*perms = MAY_READ | MAY_WRITE;
return 0;
}
if (!strcmp(name, "ro")) {
*perms = MAY_READ;
return 0;
}
return -EINVAL;
}
/*
* parse the dirs= mount argument
*
* We don't need to lock the superblock private data's rwsem, as we get
* called only by unionfs_read_super - it is still a long time before anyone
* can even get a reference to us.
*/
static int parse_dirs_option(struct super_block *sb, struct unionfs_dentry_info
*lower_root_info, char *options)
{
struct path path;
char *name;
int err = 0;
int branches = 1;
int bindex = 0;
int i = 0;
int j = 0;
struct dentry *dent1;
struct dentry *dent2;
if (options[0] == '\0') {
printk(KERN_ERR "unionfs: no branches specified\n");
err = -EINVAL;
goto out_return;
}
/*
* Each colon means we have a separator, this is really just a rough
* guess, since strsep will handle empty fields for us.
*/
for (i = 0; options[i]; i++)
if (options[i] == ':')
branches++;
/* allocate space for underlying pointers to lower dentry */
UNIONFS_SB(sb)->data =
kcalloc(branches, sizeof(struct unionfs_data), GFP_KERNEL);
if (unlikely(!UNIONFS_SB(sb)->data)) {
err = -ENOMEM;
goto out_return;
}
lower_root_info->lower_paths =
kcalloc(branches, sizeof(struct path), GFP_KERNEL);
if (unlikely(!lower_root_info->lower_paths)) {
err = -ENOMEM;
/* free the underlying pointer array */
kfree(UNIONFS_SB(sb)->data);
UNIONFS_SB(sb)->data = NULL;
goto out_return;
}
/* now parsing a string such as "b1:b2=rw:b3=ro:b4" */
branches = 0;
while ((name = strsep(&options, ":")) != NULL) {
int perms;
char *mode = strchr(name, '=');
if (!name)
continue;
if (!*name) { /* bad use of ':' (extra colons) */
err = -EINVAL;
goto out;
}
branches++;
/* strip off '=' if any */
if (mode)
*mode++ = '\0';
err = parse_branch_mode(mode, &perms);
if (err) {
printk(KERN_ERR "unionfs: invalid mode \"%s\" for "
"branch %d\n", mode, bindex);
goto out;
}
/* ensure that leftmost branch is writeable */
if (!bindex && !(perms & MAY_WRITE)) {
printk(KERN_ERR "unionfs: leftmost branch cannot be "
"read-only (use \"-o ro\" to create a "
"read-only union)\n");
err = -EINVAL;
goto out;
}
err = kern_path(name, LOOKUP_FOLLOW, &path);
if (err) {
printk(KERN_ERR "unionfs: error accessing "
"lower directory '%s' (error %d)\n",
name, err);
goto out;
}
err = check_branch(&path);
if (err) {
printk(KERN_ERR "unionfs: lower directory "
"'%s' is not a valid branch\n", name);
path_put(&path);
goto out;
}
lower_root_info->lower_paths[bindex].dentry = path.dentry;
lower_root_info->lower_paths[bindex].mnt = path.mnt;
set_branchperms(sb, bindex, perms);
set_branch_count(sb, bindex, 0);
new_branch_id(sb, bindex);
if (lower_root_info->bstart < 0)
lower_root_info->bstart = bindex;
lower_root_info->bend = bindex;
bindex++;
}
if (branches == 0) {
printk(KERN_ERR "unionfs: no branches specified\n");
err = -EINVAL;
goto out;
}
BUG_ON(branches != (lower_root_info->bend + 1));
/*
* Ensure that no overlaps exist in the branches.
*
* This test is required because the Linux kernel has no support
* currently for ensuring coherency between stackable layers and
* branches. If we were to allow overlapping branches, it would be
* possible, for example, to delete a file via one branch, which
* would not be reflected in another branch. Such incoherency could
* lead to inconsistencies and even kernel oopses. Rather than
* implement hacks to work around some of these cache-coherency
* problems, we prevent branch overlapping, for now. A complete
* solution will involve proper kernel/VFS support for cache
* coherency, at which time we could safely remove this
* branch-overlapping test.
*/
for (i = 0; i < branches; i++) {
dent1 = lower_root_info->lower_paths[i].dentry;
for (j = i + 1; j < branches; j++) {
dent2 = lower_root_info->lower_paths[j].dentry;
if (is_branch_overlap(dent1, dent2)) {
printk(KERN_ERR "unionfs: branches %d and "
"%d overlap\n", i, j);
err = -EINVAL;
goto out;
}
}
}
out:
if (err) {
for (i = 0; i < branches; i++)
path_put(&lower_root_info->lower_paths[i]);
kfree(lower_root_info->lower_paths);
kfree(UNIONFS_SB(sb)->data);
/*
* MUST clear the pointers to prevent potential double free if
* the caller dies later on
*/
lower_root_info->lower_paths = NULL;
UNIONFS_SB(sb)->data = NULL;
}
out_return:
return err;
}
/*
* Parse mount options. See the manual page for usage instructions.
*
* Returns the dentry object of the lower-level (lower) directory;
* We want to mount our stackable file system on top of that lower directory.
*/
static struct unionfs_dentry_info *unionfs_parse_options(
struct super_block *sb,
char *options)
{
struct unionfs_dentry_info *lower_root_info;
char *optname;
int err = 0;
int bindex;
int dirsfound = 0;
/* allocate private data area */
err = -ENOMEM;
lower_root_info =
kzalloc(sizeof(struct unionfs_dentry_info), GFP_KERNEL);
if (unlikely(!lower_root_info))
goto out_error;
lower_root_info->bstart = -1;
lower_root_info->bend = -1;
lower_root_info->bopaque = -1;
while ((optname = strsep(&options, ",")) != NULL) {
char *optarg;
if (!optname || !*optname)
continue;
optarg = strchr(optname, '=');
if (optarg)
*optarg++ = '\0';
/*
* All of our options take an argument now. Insert ones that
* don't, above this check.
*/
if (!optarg) {
printk(KERN_ERR "unionfs: %s requires an argument\n",
optname);
err = -EINVAL;
goto out_error;
}
if (!strcmp("dirs", optname)) {
if (++dirsfound > 1) {
printk(KERN_ERR
"unionfs: multiple dirs specified\n");
err = -EINVAL;
goto out_error;
}
err = parse_dirs_option(sb, lower_root_info, optarg);
if (err)
goto out_error;
continue;
}
err = -EINVAL;
printk(KERN_ERR
"unionfs: unrecognized option '%s'\n", optname);
goto out_error;
}
if (dirsfound != 1) {
printk(KERN_ERR "unionfs: dirs option required\n");
err = -EINVAL;
goto out_error;
}
goto out;
out_error:
if (lower_root_info && lower_root_info->lower_paths) {
for (bindex = lower_root_info->bstart;
bindex >= 0 && bindex <= lower_root_info->bend;
bindex++)
path_put(&lower_root_info->lower_paths[bindex]);
}
kfree(lower_root_info->lower_paths);
kfree(lower_root_info);
kfree(UNIONFS_SB(sb)->data);
UNIONFS_SB(sb)->data = NULL;
lower_root_info = ERR_PTR(err);
out:
return lower_root_info;
}
/*
* There is no need to lock the unionfs_super_info's rwsem as there is no
* way anyone can have a reference to the superblock at this point in time.
*/
static int unionfs_read_super(struct super_block *sb, void *raw_data,
int silent)
{
int err = 0;
struct unionfs_dentry_info *lower_root_info = NULL;
int bindex, bstart, bend;
struct inode *inode = NULL;
if (!raw_data) {
printk(KERN_ERR
"unionfs: read_super: missing data argument\n");
err = -EINVAL;
goto out;
}
/* Allocate superblock private data */
sb->s_fs_info = kzalloc(sizeof(struct unionfs_sb_info), GFP_KERNEL);
if (unlikely(!UNIONFS_SB(sb))) {
printk(KERN_CRIT "unionfs: read_super: out of memory\n");
err = -ENOMEM;
goto out;
}
UNIONFS_SB(sb)->bend = -1;
atomic_set(&UNIONFS_SB(sb)->generation, 1);
init_rwsem(&UNIONFS_SB(sb)->rwsem);
UNIONFS_SB(sb)->high_branch_id = -1; /* -1 == invalid branch ID */
lower_root_info = unionfs_parse_options(sb, raw_data);
if (IS_ERR(lower_root_info)) {
printk(KERN_ERR
"unionfs: read_super: error while parsing options "
"(err = %ld)\n", PTR_ERR(lower_root_info));
err = PTR_ERR(lower_root_info);
lower_root_info = NULL;
goto out_free;
}
if (lower_root_info->bstart == -1) {
err = -ENOENT;
goto out_free;
}
/* set the lower superblock field of upper superblock */
bstart = lower_root_info->bstart;
BUG_ON(bstart != 0);
sbend(sb) = bend = lower_root_info->bend;
for (bindex = bstart; bindex <= bend; bindex++) {
struct dentry *d = lower_root_info->lower_paths[bindex].dentry;
atomic_inc(&d->d_sb->s_active);
unionfs_set_lower_super_idx(sb, bindex, d->d_sb);
}
/* max Bytes is the maximum bytes from highest priority branch */
sb->s_maxbytes = unionfs_lower_super_idx(sb, 0)->s_maxbytes;
/*
* Our c/m/atime granularity is 1 ns because we may stack on file
* systems whose granularity is as good. This is important for our
* time-based cache coherency.
*/
sb->s_time_gran = 1;
sb->s_op = &unionfs_sops;
/* get a new inode and allocate our root dentry */
inode = unionfs_iget(sb, iunique(sb, UNIONFS_ROOT_INO));
if (IS_ERR(inode)) {
err = PTR_ERR(inode);
goto out_dput;
}
/*
* Have to set DIR mode temporarily on inode and dentry, before
* calling make_root, because make_root sets the
* DCACHE_DIRECTORY_TYPE dentry flag only if the inode is of type
* dir. Now, later below, we'll be copying the lower inode
* attributes anyway, which'll set our inode's mode to type==DIR,
* but it's too late for the dentry to have the
* DCACHE_DIRECTORY_TYPE flag set.
*/
inode->i_mode = S_IFDIR | 0755;
sb->s_root = d_make_root(inode);
d_set_type(sb->s_root, DCACHE_DIRECTORY_TYPE);
if (unlikely(!sb->s_root)) {
err = -ENOMEM;
goto out_iput;
}
d_set_d_op(sb->s_root, &unionfs_dops);
/* link the upper and lower dentries */
sb->s_root->d_fsdata = NULL;
err = new_dentry_private_data(sb->s_root, UNIONFS_DMUTEX_ROOT);
if (unlikely(err))
goto out_freedpd;
/* if get here: cannot have error */
/* Set the lower dentries for s_root */
for (bindex = bstart; bindex <= bend; bindex++) {
struct dentry *d;
struct vfsmount *m;
d = lower_root_info->lower_paths[bindex].dentry;
m = lower_root_info->lower_paths[bindex].mnt;
unionfs_set_lower_dentry_idx(sb->s_root, bindex, d);
unionfs_set_lower_mnt_idx(sb->s_root, bindex, m);
}
dbstart(sb->s_root) = bstart;
dbend(sb->s_root) = bend;
/* Set the generation number to one, since this is for the mount. */
atomic_set(&UNIONFS_D(sb->s_root)->generation, 1);
if (atomic_read(&inode->i_count) <= 1)
unionfs_fill_inode(sb->s_root, inode);
/*
* No need to call interpose because we already have a positive
* dentry, which was instantiated by d_alloc_root. Just need to
* d_rehash it.
*/
d_rehash(sb->s_root);
unionfs_unlock_dentry(sb->s_root);
goto out; /* all is well */
out_freedpd:
if (UNIONFS_D(sb->s_root)) {
kfree(UNIONFS_D(sb->s_root)->lower_paths);
free_dentry_private_data(sb->s_root);
}
dput(sb->s_root);
out_iput:
iput(inode);
out_dput:
if (lower_root_info && !IS_ERR(lower_root_info)) {
for (bindex = lower_root_info->bstart;
bindex <= lower_root_info->bend; bindex++) {
struct dentry *d;
d = lower_root_info->lower_paths[bindex].dentry;
/* drop refs we took earlier */
atomic_dec(&d->d_sb->s_active);
path_put(&lower_root_info->lower_paths[bindex]);
}
kfree(lower_root_info->lower_paths);
kfree(lower_root_info);
lower_root_info = NULL;
}
out_free:
kfree(UNIONFS_SB(sb)->data);
kfree(UNIONFS_SB(sb));
sb->s_fs_info = NULL;
out:
if (lower_root_info && !IS_ERR(lower_root_info)) {
kfree(lower_root_info->lower_paths);
kfree(lower_root_info);
}
return err;
}
static struct dentry *unionfs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name,
void *raw_data)
{
struct dentry *dentry;
dentry = mount_nodev(fs_type, flags, raw_data, unionfs_read_super);
if (!IS_ERR(dentry))
UNIONFS_SB(dentry->d_sb)->dev_name =
kstrdup(dev_name, GFP_KERNEL);
return dentry;
}
static struct file_system_type unionfs_fs_type = {
.owner = THIS_MODULE,
.name = UNIONFS_NAME,
.mount = unionfs_mount,
.kill_sb = generic_shutdown_super,
.fs_flags = 0,
};
MODULE_ALIAS_FS(UNIONFS_NAME);
static int __init init_unionfs_fs(void)
{
int err;
pr_info("Registering unionfs " UNIONFS_VERSION "\n");
err = unionfs_init_filldir_cache();
if (unlikely(err))
goto out;
err = unionfs_init_inode_cache();
if (unlikely(err))
goto out;
err = unionfs_init_dentry_cache();
if (unlikely(err))
goto out;
err = init_sioq();
if (unlikely(err))
goto out;
err = register_filesystem(&unionfs_fs_type);
out:
if (unlikely(err)) {
stop_sioq();
unionfs_destroy_filldir_cache();
unionfs_destroy_inode_cache();
unionfs_destroy_dentry_cache();
}
return err;
}
static void __exit exit_unionfs_fs(void)
{
stop_sioq();
unionfs_destroy_filldir_cache();
unionfs_destroy_inode_cache();
unionfs_destroy_dentry_cache();
unregister_filesystem(&unionfs_fs_type);
pr_info("Completed unionfs module unload\n");
}
MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
" (http://www.fsl.cs.sunysb.edu)");
MODULE_DESCRIPTION("Unionfs " UNIONFS_VERSION
" (http://unionfs.filesystems.org)");
MODULE_LICENSE("GPL");
module_init(init_unionfs_fs);
module_exit(exit_unionfs_fs);

131
fs/unionfs/mmap.c Normal file
View File

@ -0,0 +1,131 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2006 Shaya Potter
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* XXX: we need a dummy readpage handler because generic_file_mmap (which we
* use in unionfs_mmap) checks for the existence of
* mapping->a_ops->readpage, else it returns -ENOEXEC. The VFS will need to
* be fixed to allow a file system to define vm_ops->fault without any
* address_space_ops whatsoever.
*
* Otherwise, we don't want to use our readpage method at all.
*/
static int unionfs_readpage(struct file *file, struct page *page)
{
BUG();
return -EINVAL;
}
static int unionfs_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
int err;
struct file *file, *lower_file;
const struct vm_operations_struct *lower_vm_ops;
struct vm_area_struct lower_vma;
BUG_ON(!vma);
memcpy(&lower_vma, vma, sizeof(struct vm_area_struct));
file = lower_vma.vm_file;
lower_vm_ops = UNIONFS_F(file)->lower_vm_ops;
BUG_ON(!lower_vm_ops);
lower_file = unionfs_lower_file(file);
BUG_ON(!lower_file);
/*
* XXX: vm_ops->fault may be called in parallel. Because we have to
* resort to temporarily changing the vma->vm_file to point to the
* lower file, a concurrent invocation of unionfs_fault could see a
* different value. In this workaround, we keep a different copy of
* the vma structure in our stack, so we never expose a different
* value of the vma->vm_file called to us, even temporarily. A
* better fix would be to change the calling semantics of ->fault to
* take an explicit file pointer.
*/
lower_vma.vm_file = lower_file;
err = lower_vm_ops->fault(&lower_vma, vmf);
return err;
}
static int unionfs_page_mkwrite(struct vm_area_struct *vma,
struct vm_fault *vmf)
{
int err = 0;
struct file *file, *lower_file;
const struct vm_operations_struct *lower_vm_ops;
struct vm_area_struct lower_vma;
BUG_ON(!vma);
memcpy(&lower_vma, vma, sizeof(struct vm_area_struct));
file = lower_vma.vm_file;
lower_vm_ops = UNIONFS_F(file)->lower_vm_ops;
BUG_ON(!lower_vm_ops);
if (!lower_vm_ops->page_mkwrite)
goto out;
lower_file = unionfs_lower_file(file);
BUG_ON(!lower_file);
/*
* XXX: vm_ops->page_mkwrite may be called in parallel.
* Because we have to resort to temporarily changing the
* vma->vm_file to point to the lower file, a concurrent
* invocation of unionfs_page_mkwrite could see a different
* value. In this workaround, we keep a different copy of the
* vma structure in our stack, so we never expose a different
* value of the vma->vm_file called to us, even temporarily.
* A better fix would be to change the calling semantics of
* ->page_mkwrite to take an explicit file pointer.
*/
lower_vma.vm_file = lower_file;
err = lower_vm_ops->page_mkwrite(&lower_vma, vmf);
out:
return err;
}
/*
* This function should never be called directly.
* It's here only for the check a_ops->direct_IO during vfs_open.
*/
static ssize_t unionfs_direct_IO(int rw, struct kiocb *iocb,
const struct iovec *iov, loff_t offset,
unsigned long nr_segs)
{
return -EINVAL;
}
struct address_space_operations unionfs_aops = {
.direct_IO = unionfs_direct_IO,
};
/*
* XXX: we need a second, dummy address_space_ops vector, to be used
* temporarily during unionfs_mmap, because the latter calls
* generic_file_mmap, which checks if ->readpage exists, else returns
* -ENOEXEC.
*/
struct address_space_operations unionfs_dummy_aops = {
.readpage = unionfs_readpage,
};
struct vm_operations_struct unionfs_vm_ops = {
.fault = unionfs_fault,
.page_mkwrite = unionfs_page_mkwrite,
};

285
fs/unionfs/rdstate.c Normal file
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@ -0,0 +1,285 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/* This file contains the routines for maintaining readdir state. */
/*
* There are two structures here, rdstate which is a hash table
* of the second structure which is a filldir_node.
*/
/*
* This is a struct kmem_cache for filldir nodes, because we allocate a lot
* of them and they shouldn't waste memory. If the node has a small name
* (as defined by the dentry structure), then we use an inline name to
* preserve kmalloc space.
*/
static struct kmem_cache *unionfs_filldir_cachep;
int unionfs_init_filldir_cache(void)
{
unionfs_filldir_cachep =
kmem_cache_create("unionfs_filldir",
sizeof(struct filldir_node), 0,
SLAB_RECLAIM_ACCOUNT, NULL);
return (unionfs_filldir_cachep ? 0 : -ENOMEM);
}
void unionfs_destroy_filldir_cache(void)
{
if (unionfs_filldir_cachep)
kmem_cache_destroy(unionfs_filldir_cachep);
}
/*
* This is a tuning parameter that tells us roughly how big to make the
* hash table in directory entries per page. This isn't perfect, but
* at least we get a hash table size that shouldn't be too overloaded.
* The following averages are based on my home directory.
* 14.44693 Overall
* 12.29 Single Page Directories
* 117.93 Multi-page directories
*/
#define DENTPAGE 4096
#define DENTPERONEPAGE 12
#define DENTPERPAGE 118
#define MINHASHSIZE 1
static int guesstimate_hash_size(struct inode *inode)
{
struct inode *lower_inode;
int bindex;
int hashsize = MINHASHSIZE;
if (UNIONFS_I(inode)->hashsize > 0)
return UNIONFS_I(inode)->hashsize;
for (bindex = ibstart(inode); bindex <= ibend(inode); bindex++) {
lower_inode = unionfs_lower_inode_idx(inode, bindex);
if (!lower_inode)
continue;
if (i_size_read(lower_inode) == DENTPAGE)
hashsize += DENTPERONEPAGE;
else
hashsize += (i_size_read(lower_inode) / DENTPAGE) *
DENTPERPAGE;
}
return hashsize;
}
int init_rdstate(struct file *file)
{
BUG_ON(sizeof(loff_t) !=
(sizeof(unsigned int) + sizeof(unsigned int)));
BUG_ON(UNIONFS_F(file)->rdstate != NULL);
UNIONFS_F(file)->rdstate = alloc_rdstate(file_inode(file),
fbstart(file));
return (UNIONFS_F(file)->rdstate ? 0 : -ENOMEM);
}
struct unionfs_dir_state *find_rdstate(struct inode *inode, loff_t fpos)
{
struct unionfs_dir_state *rdstate = NULL;
struct list_head *pos;
spin_lock(&UNIONFS_I(inode)->rdlock);
list_for_each(pos, &UNIONFS_I(inode)->readdircache) {
struct unionfs_dir_state *r =
list_entry(pos, struct unionfs_dir_state, cache);
if (fpos == rdstate2offset(r)) {
UNIONFS_I(inode)->rdcount--;
list_del(&r->cache);
rdstate = r;
break;
}
}
spin_unlock(&UNIONFS_I(inode)->rdlock);
return rdstate;
}
struct unionfs_dir_state *alloc_rdstate(struct inode *inode, int bindex)
{
int i = 0;
int hashsize;
unsigned long mallocsize = sizeof(struct unionfs_dir_state);
struct unionfs_dir_state *rdstate;
hashsize = guesstimate_hash_size(inode);
mallocsize += hashsize * sizeof(struct list_head);
mallocsize = __roundup_pow_of_two(mallocsize);
/* This should give us about 500 entries anyway. */
if (mallocsize > PAGE_SIZE)
mallocsize = PAGE_SIZE;
hashsize = (mallocsize - sizeof(struct unionfs_dir_state)) /
sizeof(struct list_head);
rdstate = kmalloc(mallocsize, GFP_KERNEL);
if (unlikely(!rdstate))
return NULL;
spin_lock(&UNIONFS_I(inode)->rdlock);
if (UNIONFS_I(inode)->cookie >= (MAXRDCOOKIE - 1))
UNIONFS_I(inode)->cookie = 1;
else
UNIONFS_I(inode)->cookie++;
rdstate->cookie = UNIONFS_I(inode)->cookie;
spin_unlock(&UNIONFS_I(inode)->rdlock);
rdstate->offset = 1;
rdstate->access = jiffies;
rdstate->bindex = bindex;
rdstate->dirpos = 0;
rdstate->hashentries = 0;
rdstate->size = hashsize;
for (i = 0; i < rdstate->size; i++)
INIT_LIST_HEAD(&rdstate->list[i]);
return rdstate;
}
static void free_filldir_node(struct filldir_node *node)
{
if (node->namelen >= DNAME_INLINE_LEN)
kfree(node->name);
kmem_cache_free(unionfs_filldir_cachep, node);
}
void free_rdstate(struct unionfs_dir_state *state)
{
struct filldir_node *tmp;
int i;
for (i = 0; i < state->size; i++) {
struct list_head *head = &(state->list[i]);
struct list_head *pos, *n;
/* traverse the list and deallocate space */
list_for_each_safe(pos, n, head) {
tmp = list_entry(pos, struct filldir_node, file_list);
list_del(&tmp->file_list);
free_filldir_node(tmp);
}
}
kfree(state);
}
struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
const char *name, int namelen,
int is_whiteout)
{
int index;
unsigned int hash;
struct list_head *head;
struct list_head *pos;
struct filldir_node *cursor = NULL;
int found = 0;
BUG_ON(namelen <= 0);
hash = full_name_hash(name, namelen);
index = hash % rdstate->size;
head = &(rdstate->list[index]);
list_for_each(pos, head) {
cursor = list_entry(pos, struct filldir_node, file_list);
if (cursor->namelen == namelen && cursor->hash == hash &&
!strncmp(cursor->name, name, namelen)) {
/*
* a duplicate exists, and hence no need to create
* entry to the list
*/
found = 1;
/*
* if a duplicate is found in this branch, and is
* not due to the caller looking for an entry to
* whiteout, then the file system may be corrupted.
*/
if (unlikely(!is_whiteout &&
cursor->bindex == rdstate->bindex))
printk(KERN_ERR "unionfs: filldir: possible "
"I/O error: a file is duplicated "
"in the same branch %d: %s\n",
rdstate->bindex, cursor->name);
break;
}
}
if (!found)
cursor = NULL;
return cursor;
}
int add_filldir_node(struct unionfs_dir_state *rdstate, const char *name,
int namelen, int bindex, int whiteout)
{
struct filldir_node *new;
unsigned int hash;
int index;
int err = 0;
struct list_head *head;
BUG_ON(namelen <= 0);
hash = full_name_hash(name, namelen);
index = hash % rdstate->size;
head = &(rdstate->list[index]);
new = kmem_cache_alloc(unionfs_filldir_cachep, GFP_KERNEL);
if (unlikely(!new)) {
err = -ENOMEM;
goto out;
}
INIT_LIST_HEAD(&new->file_list);
new->namelen = namelen;
new->hash = hash;
new->bindex = bindex;
new->whiteout = whiteout;
if (namelen < DNAME_INLINE_LEN) {
new->name = new->iname;
} else {
new->name = kmalloc(namelen + 1, GFP_KERNEL);
if (unlikely(!new->name)) {
kmem_cache_free(unionfs_filldir_cachep, new);
new = NULL;
goto out;
}
}
memcpy(new->name, name, namelen);
new->name[namelen] = '\0';
rdstate->hashentries++;
list_add(&(new->file_list), head);
out:
return err;
}

518
fs/unionfs/rename.c Normal file
View File

@ -0,0 +1,518 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* This is a helper function for rename, used when rename ends up with hosed
* over dentries and we need to revert.
*/
static int unionfs_refresh_lower_dentry(struct dentry *dentry,
struct dentry *parent, int bindex)
{
struct dentry *lower_dentry;
struct dentry *lower_parent;
int err = 0;
verify_locked(dentry);
lower_parent = unionfs_lower_dentry_idx(parent, bindex);
BUG_ON(!S_ISDIR(lower_parent->d_inode->i_mode));
lower_dentry = lookup_one_len(dentry->d_name.name, lower_parent,
dentry->d_name.len); // XXX: pass flags?
if (IS_ERR(lower_dentry)) {
err = PTR_ERR(lower_dentry);
goto out;
}
dput(unionfs_lower_dentry_idx(dentry, bindex));
iput(unionfs_lower_inode_idx(dentry->d_inode, bindex));
unionfs_set_lower_inode_idx(dentry->d_inode, bindex, NULL);
if (!lower_dentry->d_inode) {
dput(lower_dentry);
unionfs_set_lower_dentry_idx(dentry, bindex, NULL);
} else {
unionfs_set_lower_dentry_idx(dentry, bindex, lower_dentry);
unionfs_set_lower_inode_idx(dentry->d_inode, bindex,
igrab(lower_dentry->d_inode));
}
out:
return err;
}
static int __unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct dentry *old_parent,
struct inode *new_dir, struct dentry *new_dentry,
struct dentry *new_parent,
int bindex)
{
int err = 0;
struct dentry *lower_old_dentry;
struct dentry *lower_new_dentry;
struct dentry *lower_old_dir_dentry;
struct dentry *lower_new_dir_dentry;
struct dentry *trap;
lower_new_dentry = unionfs_lower_dentry_idx(new_dentry, bindex);
lower_old_dentry = unionfs_lower_dentry_idx(old_dentry, bindex);
if (!lower_new_dentry) {
lower_new_dentry =
create_parents(new_parent->d_inode,
new_dentry, new_dentry->d_name.name,
bindex);
if (IS_ERR(lower_new_dentry)) {
err = PTR_ERR(lower_new_dentry);
if (IS_COPYUP_ERR(err))
goto out;
printk(KERN_ERR "unionfs: error creating directory "
"tree for rename, bindex=%d err=%d\n",
bindex, err);
goto out;
}
}
/* check for and remove whiteout, if any */
err = check_unlink_whiteout(new_dentry, lower_new_dentry, bindex);
if (err > 0) /* ignore if whiteout found and successfully removed */
err = 0;
if (err)
goto out;
/* check of old_dentry branch is writable */
err = is_robranch_super(old_dentry->d_sb, bindex);
if (err)
goto out;
dget(lower_old_dentry);
dget(lower_new_dentry);
lower_old_dir_dentry = dget_parent(lower_old_dentry);
lower_new_dir_dentry = dget_parent(lower_new_dentry);
trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
/* source should not be ancenstor of target */
if (trap == lower_old_dentry) {
err = -EINVAL;
goto out_err_unlock;
}
/* target should not be ancenstor of source */
if (trap == lower_new_dentry) {
err = -ENOTEMPTY;
goto out_err_unlock;
}
err = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
lower_new_dir_dentry->d_inode, lower_new_dentry,
NULL);
out_err_unlock:
if (!err) {
/* update parent dir times */
fsstack_copy_attr_times(old_dir, lower_old_dir_dentry->d_inode);
fsstack_copy_attr_times(new_dir, lower_new_dir_dentry->d_inode);
}
unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
dput(lower_old_dir_dentry);
dput(lower_new_dir_dentry);
dput(lower_old_dentry);
dput(lower_new_dentry);
out:
if (!err) {
/* Fixup the new_dentry. */
if (bindex < dbstart(new_dentry))
dbstart(new_dentry) = bindex;
else if (bindex > dbend(new_dentry))
dbend(new_dentry) = bindex;
}
return err;
}
/*
* Main rename code. This is sufficiently complex, that it's documented in
* Documentation/filesystems/unionfs/rename.txt. This routine calls
* __unionfs_rename() above to perform some of the work.
*/
static int do_unionfs_rename(struct inode *old_dir,
struct dentry *old_dentry,
struct dentry *old_parent,
struct inode *new_dir,
struct dentry *new_dentry,
struct dentry *new_parent)
{
int err = 0;
int bindex;
int old_bstart, old_bend;
int new_bstart, new_bend;
int do_copyup = -1;
int local_err = 0;
int eio = 0;
int revert = 0;
old_bstart = dbstart(old_dentry);
old_bend = dbend(old_dentry);
new_bstart = dbstart(new_dentry);
new_bend = dbend(new_dentry);
/* Rename source to destination. */
err = __unionfs_rename(old_dir, old_dentry, old_parent,
new_dir, new_dentry, new_parent,
old_bstart);
if (err) {
if (!IS_COPYUP_ERR(err))
goto out;
do_copyup = old_bstart - 1;
} else {
revert = 1;
}
/*
* Unlink all instances of destination that exist to the left of
* bstart of source. On error, revert back, goto out.
*/
for (bindex = old_bstart - 1; bindex >= new_bstart; bindex--) {
struct dentry *unlink_dentry;
struct dentry *unlink_dir_dentry;
BUG_ON(bindex < 0);
unlink_dentry = unionfs_lower_dentry_idx(new_dentry, bindex);
if (!unlink_dentry)
continue;
unlink_dir_dentry = lock_parent(unlink_dentry);
err = is_robranch_super(old_dir->i_sb, bindex);
if (!err)
err = vfs_unlink(unlink_dir_dentry->d_inode,
unlink_dentry, NULL);
fsstack_copy_attr_times(new_parent->d_inode,
unlink_dir_dentry->d_inode);
/* propagate number of hard-links */
set_nlink(new_parent->d_inode,
unionfs_get_nlinks(new_parent->d_inode));
unlock_dir(unlink_dir_dentry);
if (!err) {
if (bindex != new_bstart) {
dput(unlink_dentry);
unionfs_set_lower_dentry_idx(new_dentry,
bindex, NULL);
}
} else if (IS_COPYUP_ERR(err)) {
do_copyup = bindex - 1;
} else if (revert) {
goto revert;
}
}
if (do_copyup != -1) {
for (bindex = do_copyup; bindex >= 0; bindex--) {
/*
* copyup the file into some left directory, so that
* you can rename it
*/
err = copyup_dentry(old_parent->d_inode,
old_dentry, old_bstart, bindex,
old_dentry->d_name.name,
old_dentry->d_name.len, NULL,
i_size_read(old_dentry->d_inode));
/* if copyup failed, try next branch to the left */
if (err)
continue;
/*
* create whiteout before calling __unionfs_rename
* because the latter will change the old_dentry's
* lower name and parent dir, resulting in the
* whiteout getting created in the wrong dir.
*/
err = create_whiteout(old_dentry, bindex);
if (err) {
printk(KERN_ERR "unionfs: can't create a "
"whiteout for %pd in rename (err=%d)\n",
old_dentry, err);
continue;
}
err = __unionfs_rename(old_dir, old_dentry, old_parent,
new_dir, new_dentry, new_parent,
bindex);
break;
}
}
/* make it opaque */
if (S_ISDIR(old_dentry->d_inode->i_mode)) {
err = make_dir_opaque(old_dentry, dbstart(old_dentry));
if (err)
goto revert;
}
/*
* Create whiteout for source, only if:
* (1) There is more than one underlying instance of source.
* (We did a copy_up is taken care of above).
*/
if ((old_bstart != old_bend) && (do_copyup == -1)) {
err = create_whiteout(old_dentry, old_bstart);
if (err) {
/* can't fix anything now, so we exit with -EIO */
printk(KERN_ERR "unionfs: can't create a whiteout for "
"%pd in rename!\n", old_dentry);
err = -EIO;
}
}
out:
return err;
revert:
/* Do revert here. */
local_err = unionfs_refresh_lower_dentry(new_dentry, new_parent,
old_bstart);
if (local_err) {
printk(KERN_ERR "unionfs: revert failed in rename: "
"the new refresh failed\n");
eio = -EIO;
}
local_err = unionfs_refresh_lower_dentry(old_dentry, old_parent,
old_bstart);
if (local_err) {
printk(KERN_ERR "unionfs: revert failed in rename: "
"the old refresh failed\n");
eio = -EIO;
goto revert_out;
}
if (!unionfs_lower_dentry_idx(new_dentry, bindex) ||
!unionfs_lower_dentry_idx(new_dentry, bindex)->d_inode) {
printk(KERN_ERR "unionfs: revert failed in rename: "
"the object disappeared from under us!\n");
eio = -EIO;
goto revert_out;
}
if (unionfs_lower_dentry_idx(old_dentry, bindex) &&
unionfs_lower_dentry_idx(old_dentry, bindex)->d_inode) {
printk(KERN_ERR "unionfs: revert failed in rename: "
"the object was created underneath us!\n");
eio = -EIO;
goto revert_out;
}
local_err = __unionfs_rename(new_dir, new_dentry, new_parent,
old_dir, old_dentry, old_parent,
old_bstart);
/* If we can't fix it, then we cop-out with -EIO. */
if (local_err) {
printk(KERN_ERR "unionfs: revert failed in rename!\n");
eio = -EIO;
}
local_err = unionfs_refresh_lower_dentry(new_dentry, new_parent,
bindex);
if (local_err)
eio = -EIO;
local_err = unionfs_refresh_lower_dentry(old_dentry, old_parent,
bindex);
if (local_err)
eio = -EIO;
revert_out:
if (eio)
err = eio;
return err;
}
/*
* We can't copyup a directory, because it may involve huge numbers of
* children, etc. Doing that in the kernel would be bad, so instead we
* return EXDEV to the user-space utility that caused this, and let the
* user-space recurse and ask us to copy up each file separately.
*/
static int may_rename_dir(struct dentry *dentry, struct dentry *parent)
{
int err, bstart;
err = check_empty(dentry, parent, NULL);
if (err == -ENOTEMPTY) {
if (is_robranch(dentry))
return -EXDEV;
} else if (err) {
return err;
}
bstart = dbstart(dentry);
if (dbend(dentry) == bstart || dbopaque(dentry) == bstart)
return 0;
dbstart(dentry) = bstart + 1;
err = check_empty(dentry, parent, NULL);
dbstart(dentry) = bstart;
if (err == -ENOTEMPTY)
err = -EXDEV;
return err;
}
/*
* The locking rules in unionfs_rename are complex. We could use a simpler
* superblock-level name-space lock for renames and copy-ups.
*/
int unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
int err = 0;
struct dentry *wh_dentry;
struct dentry *old_parent, *new_parent;
int valid = true;
unionfs_read_lock(old_dentry->d_sb, UNIONFS_SMUTEX_CHILD);
old_parent = dget_parent(old_dentry);
new_parent = dget_parent(new_dentry);
/* un/lock parent dentries only if they differ from old/new_dentry */
if (old_parent != old_dentry &&
old_parent != new_dentry)
unionfs_lock_dentry(old_parent, UNIONFS_DMUTEX_REVAL_PARENT);
if (new_parent != old_dentry &&
new_parent != new_dentry &&
new_parent != old_parent)
unionfs_lock_dentry(new_parent, UNIONFS_DMUTEX_REVAL_CHILD);
unionfs_double_lock_dentry(old_dentry, new_dentry);
valid = __unionfs_d_revalidate(old_dentry, old_parent, false, 0);
if (!valid) {
err = -ESTALE;
goto out;
}
if (!d_deleted(new_dentry) && new_dentry->d_inode) {
valid = __unionfs_d_revalidate(new_dentry, new_parent, false, 0);
if (!valid) {
err = -ESTALE;
goto out;
}
}
if (!S_ISDIR(old_dentry->d_inode->i_mode))
err = unionfs_partial_lookup(old_dentry, old_parent);
else
err = may_rename_dir(old_dentry, old_parent);
if (err)
goto out;
err = unionfs_partial_lookup(new_dentry, new_parent);
if (err)
goto out;
/*
* if new_dentry is already lower because of whiteout,
* simply override it even if the whited-out dir is not empty.
*/
wh_dentry = find_first_whiteout(new_dentry);
if (!IS_ERR(wh_dentry)) {
dput(wh_dentry);
} else if (new_dentry->d_inode) {
if (S_ISDIR(old_dentry->d_inode->i_mode) !=
S_ISDIR(new_dentry->d_inode->i_mode)) {
err = S_ISDIR(old_dentry->d_inode->i_mode) ?
-ENOTDIR : -EISDIR;
goto out;
}
if (S_ISDIR(new_dentry->d_inode->i_mode)) {
struct unionfs_dir_state *namelist = NULL;
/* check if this unionfs directory is empty or not */
err = check_empty(new_dentry, new_parent, &namelist);
if (err)
goto out;
if (!is_robranch(new_dentry))
err = delete_whiteouts(new_dentry,
dbstart(new_dentry),
namelist);
free_rdstate(namelist);
if (err)
goto out;
}
}
err = do_unionfs_rename(old_dir, old_dentry, old_parent,
new_dir, new_dentry, new_parent);
if (err)
goto out;
/*
* force re-lookup since the dir on ro branch is not renamed, and
* lower dentries still indicate the un-renamed ones.
*/
if (S_ISDIR(old_dentry->d_inode->i_mode))
atomic_dec(&UNIONFS_D(old_dentry)->generation);
else
unionfs_postcopyup_release(old_dentry);
if (new_dentry->d_inode && !S_ISDIR(new_dentry->d_inode->i_mode)) {
unionfs_postcopyup_release(new_dentry);
unionfs_postcopyup_setmnt(new_dentry);
if (!unionfs_lower_inode(new_dentry->d_inode)) {
/*
* If we get here, it means that no copyup was
* needed, and that a file by the old name already
* existing on the destination branch; that file got
* renamed earlier in this function, so all we need
* to do here is set the lower inode.
*/
struct inode *inode;
inode = unionfs_lower_inode(old_dentry->d_inode);
igrab(inode);
unionfs_set_lower_inode_idx(new_dentry->d_inode,
dbstart(new_dentry),
inode);
}
}
/* if all of this renaming succeeded, update our times */
unionfs_copy_attr_times(old_dentry->d_inode);
unionfs_copy_attr_times(new_dentry->d_inode);
unionfs_check_inode(old_dir);
unionfs_check_inode(new_dir);
unionfs_check_dentry(old_dentry);
unionfs_check_dentry(new_dentry);
out:
if (err) /* clear the new_dentry stuff created */
d_drop(new_dentry);
unionfs_double_unlock_dentry(old_dentry, new_dentry);
if (new_parent != old_dentry &&
new_parent != new_dentry &&
new_parent != old_parent)
unionfs_unlock_dentry(new_parent);
if (old_parent != old_dentry &&
old_parent != new_dentry)
unionfs_unlock_dentry(old_parent);
dput(new_parent);
dput(old_parent);
unionfs_read_unlock(old_dentry->d_sb);
return err;
}

101
fs/unionfs/sioq.c Normal file
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/*
* Copyright (c) 2006-2014 Erez Zadok
* Copyright (c) 2006 Charles P. Wright
* Copyright (c) 2006-2007 Josef 'Jeff' Sipek
* Copyright (c) 2006 Junjiro Okajima
* Copyright (c) 2006 David P. Quigley
* Copyright (c) 2006-2014 Stony Brook University
* Copyright (c) 2006-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* Super-user IO work Queue - sometimes we need to perform actions which
* would fail due to the unix permissions on the parent directory (e.g.,
* rmdir a directory which appears empty, but in reality contains
* whiteouts).
*/
static struct workqueue_struct *superio_workqueue;
int __init init_sioq(void)
{
int err;
superio_workqueue = create_workqueue("unionfs_siod");
if (!IS_ERR(superio_workqueue))
return 0;
err = PTR_ERR(superio_workqueue);
printk(KERN_ERR "unionfs: create_workqueue failed %d\n", err);
superio_workqueue = NULL;
return err;
}
void stop_sioq(void)
{
if (superio_workqueue)
destroy_workqueue(superio_workqueue);
}
void run_sioq(work_func_t func, struct sioq_args *args)
{
INIT_WORK(&args->work, func);
init_completion(&args->comp);
while (!queue_work(superio_workqueue, &args->work)) {
/* TODO: do accounting if needed */
schedule();
}
wait_for_completion(&args->comp);
}
void __unionfs_create(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
struct create_args *c = &args->create;
args->err = vfs_create(c->parent, c->dentry, c->mode, c->want_excl);
complete(&args->comp);
}
void __unionfs_mkdir(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
struct mkdir_args *m = &args->mkdir;
args->err = vfs_mkdir(m->parent, m->dentry, m->mode);
complete(&args->comp);
}
void __unionfs_mknod(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
struct mknod_args *m = &args->mknod;
args->err = vfs_mknod(m->parent, m->dentry, m->mode, m->dev);
complete(&args->comp);
}
void __unionfs_symlink(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
struct symlink_args *s = &args->symlink;
args->err = vfs_symlink(s->parent, s->dentry, s->symbuf);
complete(&args->comp);
}
void __unionfs_unlink(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
struct unlink_args *u = &args->unlink;
args->err = vfs_unlink(u->parent, u->dentry, NULL);
complete(&args->comp);
}

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/*
* Copyright (c) 2006-2014 Erez Zadok
* Copyright (c) 2006 Charles P. Wright
* Copyright (c) 2006-2007 Josef 'Jeff' Sipek
* Copyright (c) 2006 Junjiro Okajima
* Copyright (c) 2006 David P. Quigley
* Copyright (c) 2006-2014 Stony Brook University
* Copyright (c) 2006-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _SIOQ_H
#define _SIOQ_H
struct deletewh_args {
struct unionfs_dir_state *namelist;
struct dentry *dentry;
int bindex;
};
struct is_opaque_args {
struct dentry *dentry;
};
struct create_args {
struct inode *parent;
struct dentry *dentry;
umode_t mode;
bool want_excl;
};
struct mkdir_args {
struct inode *parent;
struct dentry *dentry;
umode_t mode;
};
struct mknod_args {
struct inode *parent;
struct dentry *dentry;
umode_t mode;
dev_t dev;
};
struct symlink_args {
struct inode *parent;
struct dentry *dentry;
char *symbuf;
};
struct unlink_args {
struct inode *parent;
struct dentry *dentry;
};
struct sioq_args {
struct completion comp;
struct work_struct work;
int err;
void *ret;
union {
struct deletewh_args deletewh;
struct is_opaque_args is_opaque;
struct create_args create;
struct mkdir_args mkdir;
struct mknod_args mknod;
struct symlink_args symlink;
struct unlink_args unlink;
};
};
/* Extern definitions for SIOQ functions */
extern int __init init_sioq(void);
extern void stop_sioq(void);
extern void run_sioq(work_func_t func, struct sioq_args *args);
/* Extern definitions for our privilege escalation helpers */
extern void __unionfs_create(struct work_struct *work);
extern void __unionfs_mkdir(struct work_struct *work);
extern void __unionfs_mknod(struct work_struct *work);
extern void __unionfs_symlink(struct work_struct *work);
extern void __unionfs_unlink(struct work_struct *work);
extern void __delete_whiteouts(struct work_struct *work);
extern void __is_opaque_dir(struct work_struct *work);
#endif /* not _SIOQ_H */

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fs/unionfs/subr.c Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* returns the right n_link value based on the inode type
*/
int unionfs_get_nlinks(const struct inode *inode)
{
/* don't bother to do all the work since we're unlinked */
if (inode->i_nlink == 0)
return 0;
if (!S_ISDIR(inode->i_mode))
return unionfs_lower_inode(inode)->i_nlink;
/*
* For directories, we return 1. The only place that could cares
* about links is readdir, and there's d_type there so even that
* doesn't matter.
*/
return 1;
}
/* copy a/m/ctime from the lower branch with the newest times */
void unionfs_copy_attr_times(struct inode *upper)
{
int bindex;
struct inode *lower;
if (!upper)
return;
if (ibstart(upper) < 0) {
#ifdef CONFIG_UNION_FS_DEBUG
WARN_ON(ibstart(upper) < 0);
#endif /* CONFIG_UNION_FS_DEBUG */
return;
}
for (bindex = ibstart(upper); bindex <= ibend(upper); bindex++) {
lower = unionfs_lower_inode_idx(upper, bindex);
if (!lower)
continue; /* not all lower dir objects may exist */
if (unlikely(timespec_compare(&upper->i_mtime,
&lower->i_mtime) < 0))
upper->i_mtime = lower->i_mtime;
if (unlikely(timespec_compare(&upper->i_ctime,
&lower->i_ctime) < 0))
upper->i_ctime = lower->i_ctime;
if (unlikely(timespec_compare(&upper->i_atime,
&lower->i_atime) < 0))
upper->i_atime = lower->i_atime;
}
}
/*
* A unionfs/fanout version of fsstack_copy_attr_all. Uses a
* unionfs_get_nlinks to properly calcluate the number of links to a file.
* Also, copies the max() of all a/m/ctimes for all lower inodes (which is
* important if the lower inode is a directory type)
*/
void unionfs_copy_attr_all(struct inode *dest,
const struct inode *src)
{
dest->i_mode = src->i_mode;
dest->i_uid = src->i_uid;
dest->i_gid = src->i_gid;
dest->i_rdev = src->i_rdev;
unionfs_copy_attr_times(dest);
dest->i_blkbits = src->i_blkbits;
dest->i_flags = src->i_flags;
/*
* Update the nlinks AFTER updating the above fields, because the
* get_links callback may depend on them.
*/
set_nlink(dest, unionfs_get_nlinks(dest));
}

1030
fs/unionfs/super.c Normal file
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669
fs/unionfs/union.h Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _UNION_H_
#define _UNION_H_
#include <linux/dcache.h>
#include <linux/file.h>
#include <linux/list.h>
#include <linux/fs.h>
#include <linux/aio.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/page-flags.h>
#include <linux/pagemap.h>
#include <linux/poll.h>
#include <linux/security.h>
#include <linux/seq_file.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/statfs.h>
#include <linux/string.h>
#include <linux/vmalloc.h>
#include <linux/writeback.h>
#include <linux/buffer_head.h>
#include <linux/xattr.h>
#include <linux/fs_stack.h>
#include <linux/magic.h>
#include <linux/log2.h>
#include <linux/poison.h>
#include <linux/mman.h>
#include <linux/backing-dev.h>
#include <linux/splice.h>
#include <linux/sched.h>
#include <linux/union_fs.h>
/* the file system name */
#define UNIONFS_NAME "unionfs"
/* unionfs root inode number */
#define UNIONFS_ROOT_INO 1
/* number of times we try to get a unique temporary file name */
#define GET_TMPNAM_MAX_RETRY 5
/* maximum number of branches we support, to avoid memory blowup */
#define UNIONFS_MAX_BRANCHES 128
/* minimum time (seconds) required for time-based cache-coherency */
#define UNIONFS_MIN_CC_TIME 3
/* Operations vectors defined in specific files. */
extern struct file_operations unionfs_main_fops;
extern struct file_operations unionfs_dir_fops;
extern struct inode_operations unionfs_main_iops;
extern struct inode_operations unionfs_dir_iops;
extern struct inode_operations unionfs_symlink_iops;
extern struct super_operations unionfs_sops;
extern struct dentry_operations unionfs_dops;
extern struct address_space_operations unionfs_aops, unionfs_dummy_aops;
extern struct vm_operations_struct unionfs_vm_ops;
/* How long should an entry be allowed to persist */
#define RDCACHE_JIFFIES (5*HZ)
/* compatibility with Real-Time patches */
#ifdef CONFIG_PREEMPT_RT
# define unionfs_rw_semaphore compat_rw_semaphore
#else /* not CONFIG_PREEMPT_RT */
# define unionfs_rw_semaphore rw_semaphore
#endif /* not CONFIG_PREEMPT_RT */
/* file private data. */
struct unionfs_file_info {
int bstart;
int bend;
atomic_t generation;
struct unionfs_dir_state *rdstate;
struct file **lower_files;
int *saved_branch_ids; /* IDs of branches when file was opened */
const struct vm_operations_struct *lower_vm_ops;
bool wrote_to_file; /* for delayed copyup */
};
/* unionfs inode data in memory */
struct unionfs_inode_info {
int bstart;
int bend;
atomic_t generation;
/* Stuff for readdir over NFS. */
spinlock_t rdlock;
struct list_head readdircache;
int rdcount;
int hashsize;
int cookie;
/* The lower inodes */
struct inode **lower_inodes;
struct inode vfs_inode;
};
/* unionfs dentry data in memory */
struct unionfs_dentry_info {
/*
* The semaphore is used to lock the dentry as soon as we get into a
* unionfs function from the VFS. Our lock ordering is that children
* go before their parents.
*/
struct mutex lock;
int bstart;
int bend;
int bopaque;
int bcount;
atomic_t generation;
struct path *lower_paths;
};
/* These are the pointers to our various objects. */
struct unionfs_data {
struct super_block *sb; /* lower super_block */
atomic_t open_files; /* number of open files on branch */
int branchperms;
int branch_id; /* unique branch ID at re/mount time */
};
/* unionfs super-block data in memory */
struct unionfs_sb_info {
int bend;
atomic_t generation;
/*
* This rwsem is used to make sure that a branch management
* operation...
* 1) will not begin before all currently in-flight operations
* complete.
* 2) any new operations do not execute until the currently
* running branch management operation completes.
*
* The write_lock_owner records the PID of the task which grabbed
* the rw_sem for writing. If the same task also tries to grab the
* read lock, we allow it. This prevents a self-deadlock when
* branch-management is used on a pivot_root'ed union, because we
* have to ->lookup paths which belong to the same union.
*/
struct unionfs_rw_semaphore rwsem;
pid_t write_lock_owner; /* PID of rw_sem owner (write lock) */
int high_branch_id; /* last unique branch ID given */
char *dev_name; /* to identify different unions in pr_debug */
struct unionfs_data *data;
};
/*
* structure for making the linked list of entries by readdir on left branch
* to compare with entries on right branch
*/
struct filldir_node {
struct list_head file_list; /* list for directory entries */
char *name; /* name entry */
int hash; /* name hash */
int namelen; /* name len since name is not 0 terminated */
/*
* we can check for duplicate whiteouts and files in the same branch
* in order to return -EIO.
*/
int bindex;
/* is this a whiteout entry? */
int whiteout;
/* Inline name, so we don't need to separately kmalloc small ones */
char iname[DNAME_INLINE_LEN];
};
/* Directory hash table. */
struct unionfs_dir_state {
unsigned int cookie; /* the cookie, based off of rdversion */
unsigned int offset; /* The entry we have returned. */
int bindex;
loff_t dirpos; /* offset within the lower level directory */
int size; /* How big is the hash table? */
int hashentries; /* How many entries have been inserted? */
unsigned long access;
/* This cache list is used when the inode keeps us around. */
struct list_head cache;
struct list_head list[0];
};
/* externs needed for fanout.h or sioq.h */
extern int unionfs_get_nlinks(const struct inode *inode);
extern void unionfs_copy_attr_times(struct inode *upper);
extern void unionfs_copy_attr_all(struct inode *dest, const struct inode *src);
/* include miscellaneous macros */
#include "fanout.h"
#include "sioq.h"
/* externs for cache creation/deletion routines */
extern void unionfs_destroy_filldir_cache(void);
extern int unionfs_init_filldir_cache(void);
extern int unionfs_init_inode_cache(void);
extern void unionfs_destroy_inode_cache(void);
extern int unionfs_init_dentry_cache(void);
extern void unionfs_destroy_dentry_cache(void);
/* Initialize and free readdir-specific state. */
extern int init_rdstate(struct file *file);
extern struct unionfs_dir_state *alloc_rdstate(struct inode *inode,
int bindex);
extern struct unionfs_dir_state *find_rdstate(struct inode *inode,
loff_t fpos);
extern void free_rdstate(struct unionfs_dir_state *state);
extern int add_filldir_node(struct unionfs_dir_state *rdstate,
const char *name, int namelen, int bindex,
int whiteout);
extern struct filldir_node *find_filldir_node(struct unionfs_dir_state *rdstate,
const char *name, int namelen,
int is_whiteout);
extern struct dentry **alloc_new_dentries(int objs);
extern struct unionfs_data *alloc_new_data(int objs);
/* We can only use 32-bits of offset for rdstate --- blech! */
#define DIREOF (0xfffff)
#define RDOFFBITS 20 /* This is the number of bits in DIREOF. */
#define MAXRDCOOKIE (0xfff)
/* Turn an rdstate into an offset. */
static inline off_t rdstate2offset(struct unionfs_dir_state *buf)
{
off_t tmp;
tmp = ((buf->cookie & MAXRDCOOKIE) << RDOFFBITS)
| (buf->offset & DIREOF);
return tmp;
}
/* Macros for locking a super_block. */
enum unionfs_super_lock_class {
UNIONFS_SMUTEX_NORMAL,
UNIONFS_SMUTEX_PARENT, /* when locking on behalf of file */
UNIONFS_SMUTEX_CHILD, /* when locking on behalf of dentry */
};
static inline void unionfs_read_lock(struct super_block *sb, int subclass)
{
if (UNIONFS_SB(sb)->write_lock_owner &&
UNIONFS_SB(sb)->write_lock_owner == current->pid)
return;
down_read_nested(&UNIONFS_SB(sb)->rwsem, subclass);
}
static inline void unionfs_read_unlock(struct super_block *sb)
{
if (UNIONFS_SB(sb)->write_lock_owner &&
UNIONFS_SB(sb)->write_lock_owner == current->pid)
return;
up_read(&UNIONFS_SB(sb)->rwsem);
}
static inline void unionfs_write_lock(struct super_block *sb)
{
down_write(&UNIONFS_SB(sb)->rwsem);
UNIONFS_SB(sb)->write_lock_owner = current->pid;
}
static inline void unionfs_write_unlock(struct super_block *sb)
{
up_write(&UNIONFS_SB(sb)->rwsem);
UNIONFS_SB(sb)->write_lock_owner = 0;
}
static inline void unionfs_double_lock_dentry(struct dentry *d1,
struct dentry *d2)
{
BUG_ON(d1 == d2);
if (d1 < d2) {
unionfs_lock_dentry(d1, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(d2, UNIONFS_DMUTEX_CHILD);
} else {
unionfs_lock_dentry(d2, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(d1, UNIONFS_DMUTEX_CHILD);
}
}
static inline void unionfs_double_unlock_dentry(struct dentry *d1,
struct dentry *d2)
{
BUG_ON(d1 == d2);
if (d1 < d2) { /* unlock in reverse order than double_lock_dentry */
unionfs_unlock_dentry(d1);
unionfs_unlock_dentry(d2);
} else {
unionfs_unlock_dentry(d2);
unionfs_unlock_dentry(d1);
}
}
static inline void unionfs_double_lock_parents(struct dentry *p1,
struct dentry *p2)
{
if (p1 == p2) {
unionfs_lock_dentry(p1, UNIONFS_DMUTEX_REVAL_PARENT);
return;
}
if (p1 < p2) {
unionfs_lock_dentry(p1, UNIONFS_DMUTEX_REVAL_PARENT);
unionfs_lock_dentry(p2, UNIONFS_DMUTEX_REVAL_CHILD);
} else {
unionfs_lock_dentry(p2, UNIONFS_DMUTEX_REVAL_PARENT);
unionfs_lock_dentry(p1, UNIONFS_DMUTEX_REVAL_CHILD);
}
}
static inline void unionfs_double_unlock_parents(struct dentry *p1,
struct dentry *p2)
{
if (p1 == p2) {
unionfs_unlock_dentry(p1);
return;
}
if (p1 < p2) { /* unlock in reverse order of double_lock_parents */
unionfs_unlock_dentry(p1);
unionfs_unlock_dentry(p2);
} else {
unionfs_unlock_dentry(p2);
unionfs_unlock_dentry(p1);
}
}
extern int new_dentry_private_data(struct dentry *dentry, int subclass);
extern int realloc_dentry_private_data(struct dentry *dentry);
extern void free_dentry_private_data(struct dentry *dentry);
extern void update_bstart(struct dentry *dentry);
/*
* EXTERNALS:
*/
/* replicates the directory structure up to given dentry in given branch */
extern struct dentry *create_parents(struct inode *dir, struct dentry *dentry,
const char *name, int bindex);
/* partial lookup */
extern int unionfs_partial_lookup(struct dentry *dentry,
struct dentry *parent);
extern struct dentry *unionfs_lookup_full(struct dentry *dentry,
struct dentry *parent,
int lookupmode);
/* copies a file from dbstart to newbindex branch */
extern int copyup_file(struct inode *dir, struct file *file, int bstart,
int newbindex, loff_t size);
extern int copyup_named_file(struct inode *dir, struct file *file,
char *name, int bstart, int new_bindex,
loff_t len);
/* copies a dentry from dbstart to newbindex branch */
extern int copyup_dentry(struct inode *dir, struct dentry *dentry,
int bstart, int new_bindex, const char *name,
int namelen, struct file **copyup_file, loff_t len);
/* helper functions for post-copyup actions */
extern void unionfs_postcopyup_setmnt(struct dentry *dentry);
extern void unionfs_postcopyup_release(struct dentry *dentry);
/* Is this directory empty: 0 if it is empty, -ENOTEMPTY if not. */
extern int check_empty(struct dentry *dentry, struct dentry *parent,
struct unionfs_dir_state **namelist);
/* whiteout and opaque directory helpers */
extern char *alloc_whname(const char *name, int len);
extern bool is_whiteout_name(char **namep, int *namelenp);
extern bool is_validname(const char *name);
extern struct dentry *lookup_whiteout(const char *name,
struct dentry *lower_parent);
extern struct dentry *find_first_whiteout(struct dentry *dentry);
extern int unlink_whiteout(struct dentry *wh_dentry);
extern int check_unlink_whiteout(struct dentry *dentry,
struct dentry *lower_dentry, int bindex);
extern int create_whiteout(struct dentry *dentry, int start);
extern int delete_whiteouts(struct dentry *dentry, int bindex,
struct unionfs_dir_state *namelist);
extern int is_opaque_dir(struct dentry *dentry, int bindex);
extern int make_dir_opaque(struct dentry *dir, int bindex);
extern void unionfs_set_max_namelen(long *namelen);
extern void unionfs_reinterpose(struct dentry *this_dentry);
extern struct super_block *unionfs_duplicate_super(struct super_block *sb);
/* Locking functions. */
extern int unionfs_setlk(struct file *file, int cmd, struct file_lock *fl);
extern int unionfs_getlk(struct file *file, struct file_lock *fl);
/* Common file operations. */
extern int unionfs_file_revalidate(struct file *file, struct dentry *parent,
bool willwrite);
extern int unionfs_open(struct inode *inode, struct file *file);
extern int unionfs_file_release(struct inode *inode, struct file *file);
extern int unionfs_flush(struct file *file, fl_owner_t id);
extern long unionfs_ioctl(struct file *file, unsigned int cmd,
unsigned long arg);
extern int unionfs_fsync(struct file *file, loff_t start, loff_t end,
int datasync);
extern int unionfs_fasync(int fd, struct file *file, int flag);
/* Inode operations */
extern struct inode *unionfs_iget(struct super_block *sb, unsigned long ino);
extern int unionfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry);
extern int unionfs_unlink(struct inode *dir, struct dentry *dentry);
extern int unionfs_rmdir(struct inode *dir, struct dentry *dentry);
extern bool __unionfs_d_revalidate(struct dentry *dentry,
struct dentry *parent, bool willwrite,
unsigned int flags);
extern bool is_negative_lower(const struct dentry *dentry);
extern bool is_newer_lower(const struct dentry *dentry);
extern void purge_sb_data(struct super_block *sb);
/* The values for unionfs_interpose's flag. */
#define INTERPOSE_DEFAULT 0
#define INTERPOSE_LOOKUP 1
#define INTERPOSE_REVAL 2
#define INTERPOSE_REVAL_NEG 3
#define INTERPOSE_PARTIAL 4
extern struct dentry *unionfs_interpose(struct dentry *this_dentry,
struct super_block *sb, int flag);
#ifdef CONFIG_UNION_FS_XATTR
/* Extended attribute functions. */
extern void *unionfs_xattr_alloc(size_t size, size_t limit);
static inline void unionfs_xattr_kfree(const void *p)
{
kfree(p);
}
extern ssize_t unionfs_getxattr(struct dentry *dentry, const char *name,
void *value, size_t size);
extern int unionfs_removexattr(struct dentry *dentry, const char *name);
extern ssize_t unionfs_listxattr(struct dentry *dentry, char *list,
size_t size);
extern int unionfs_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags);
#endif /* CONFIG_UNION_FS_XATTR */
/* The root directory is unhashed, but isn't deleted. */
static inline int d_deleted(struct dentry *d)
{
return d_unhashed(d) && (d != d->d_sb->s_root);
}
/* unionfs_permission, check if we should bypass error to facilitate copyup */
#define IS_COPYUP_ERR(err) ((err) == -EROFS)
/* unionfs_open, check if we need to copyup the file */
#define OPEN_WRITE_FLAGS (O_WRONLY | O_RDWR | O_APPEND)
#define IS_WRITE_FLAG(flag) ((flag) & OPEN_WRITE_FLAGS)
static inline int branchperms(const struct super_block *sb, int index)
{
BUG_ON(index < 0);
return UNIONFS_SB(sb)->data[index].branchperms;
}
static inline int set_branchperms(struct super_block *sb, int index, int perms)
{
BUG_ON(index < 0);
UNIONFS_SB(sb)->data[index].branchperms = perms;
return perms;
}
/* check if readonly lower inode, but possibly unlinked (no inode->i_sb) */
static inline int __is_rdonly(const struct inode *inode)
{
/* if unlinked, can't be readonly (?) */
if (!inode->i_sb)
return 0;
return IS_RDONLY(inode);
}
/* Is this file on a read-only branch? */
static inline int is_robranch_super(const struct super_block *sb, int index)
{
int ret;
ret = (!(branchperms(sb, index) & MAY_WRITE)) ? -EROFS : 0;
return ret;
}
/* Is this file on a read-only branch? */
static inline int is_robranch_idx(const struct dentry *dentry, int index)
{
struct super_block *lower_sb;
BUG_ON(index < 0);
if (!(branchperms(dentry->d_sb, index) & MAY_WRITE))
return -EROFS;
lower_sb = unionfs_lower_super_idx(dentry->d_sb, index);
BUG_ON(lower_sb == NULL);
/*
* test sb flags directly, not IS_RDONLY(lower_inode) because the
* lower_dentry could be a negative.
*/
if (lower_sb->s_flags & MS_RDONLY)
return -EROFS;
return 0;
}
static inline int is_robranch(const struct dentry *dentry)
{
int index;
index = UNIONFS_D(dentry)->bstart;
BUG_ON(index < 0);
return is_robranch_idx(dentry, index);
}
/*
* EXTERNALS:
*/
extern int check_branch(const struct path *path);
extern int parse_branch_mode(const char *name, int *perms);
/* locking helpers */
static inline struct dentry *lock_parent(struct dentry *dentry)
{
struct dentry *dir = dget_parent(dentry);
mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
return dir;
}
static inline struct dentry *lock_parent_wh(struct dentry *dentry)
{
struct dentry *dir = dget_parent(dentry);
mutex_lock_nested(&dir->d_inode->i_mutex, UNIONFS_DMUTEX_WHITEOUT);
return dir;
}
static inline void unlock_dir(struct dentry *dir)
{
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
}
/* lock base inode mutex before calling lookup_one_len */
static inline struct dentry *lookup_lck_len(const char *name,
struct dentry *base, int len)
{
struct dentry *d;
mutex_lock(&base->d_inode->i_mutex);
d = lookup_one_len(name, base, len); // XXX: pass flags?
mutex_unlock(&base->d_inode->i_mutex);
return d;
}
static inline struct vfsmount *unionfs_mntget(struct dentry *dentry,
int bindex)
{
struct vfsmount *mnt;
BUG_ON(!dentry || bindex < 0);
mnt = mntget(unionfs_lower_mnt_idx(dentry, bindex));
#ifdef CONFIG_UNION_FS_DEBUG
if (!mnt)
pr_debug("unionfs: mntget: mnt=%p bindex=%d\n",
mnt, bindex);
#endif /* CONFIG_UNION_FS_DEBUG */
return mnt;
}
static inline void unionfs_mntput(struct dentry *dentry, int bindex)
{
struct vfsmount *mnt;
if (!dentry && bindex < 0)
return;
BUG_ON(!dentry || bindex < 0);
mnt = unionfs_lower_mnt_idx(dentry, bindex);
#ifdef CONFIG_UNION_FS_DEBUG
/*
* Directories can have NULL lower objects in between start/end, but
* NOT if at the start/end range. We cannot verify that this dentry
* is a type=DIR, because it may already be a negative dentry. But
* if dbstart is greater than dbend, we know that this couldn't have
* been a regular file: it had to have been a directory.
*/
if (!mnt && !(bindex > dbstart(dentry) && bindex < dbend(dentry)))
pr_debug("unionfs: mntput: mnt=%p bindex=%d\n", mnt, bindex);
#endif /* CONFIG_UNION_FS_DEBUG */
mntput(mnt);
}
#ifdef CONFIG_UNION_FS_DEBUG
/* useful for tracking code reachability */
#define UDBG pr_debug("DBG:%s:%s:%d\n", __FILE__, __func__, __LINE__)
#define unionfs_check_inode(i) __unionfs_check_inode((i), \
__FILE__, __func__, __LINE__)
#define unionfs_check_dentry(d) __unionfs_check_dentry((d), \
__FILE__, __func__, __LINE__)
#define unionfs_check_file(f) __unionfs_check_file((f), \
__FILE__, __func__, __LINE__)
#define unionfs_check_nd(n) __unionfs_check_nd((n), \
__FILE__, __func__, __LINE__)
#define show_branch_counts(sb) __show_branch_counts((sb), \
__FILE__, __func__, __LINE__)
#define show_inode_times(i) __show_inode_times((i), \
__FILE__, __func__, __LINE__)
#define show_dinode_times(d) __show_dinode_times((d), \
__FILE__, __func__, __LINE__)
#define show_inode_counts(i) __show_inode_counts((i), \
__FILE__, __func__, __LINE__)
extern void __unionfs_check_inode(const struct inode *inode, const char *fname,
const char *fxn, int line);
extern void __unionfs_check_dentry(const struct dentry *dentry,
const char *fname, const char *fxn,
int line);
extern void __unionfs_check_file(const struct file *file,
const char *fname, const char *fxn, int line);
extern void __show_branch_counts(const struct super_block *sb,
const char *file, const char *fxn, int line);
extern void __show_inode_times(const struct inode *inode,
const char *file, const char *fxn, int line);
extern void __show_dinode_times(const struct dentry *dentry,
const char *file, const char *fxn, int line);
extern void __show_inode_counts(const struct inode *inode,
const char *file, const char *fxn, int line);
#else /* not CONFIG_UNION_FS_DEBUG */
/* we leave useful hooks for these check functions throughout the code */
#define unionfs_check_inode(i) do { } while (0)
#define unionfs_check_dentry(d) do { } while (0)
#define unionfs_check_file(f) do { } while (0)
#define unionfs_check_nd(n) do { } while (0)
#define show_branch_counts(sb) do { } while (0)
#define show_inode_times(i) do { } while (0)
#define show_dinode_times(d) do { } while (0)
#define show_inode_counts(i) do { } while (0)
#define UDBG do { } while (0)
#endif /* not CONFIG_UNION_FS_DEBUG */
#endif /* not _UNION_H_ */

278
fs/unionfs/unlink.c Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* Helper function for Unionfs's unlink operation.
*
* The main goal of this function is to optimize the unlinking of non-dir
* objects in unionfs by deleting all possible lower inode objects from the
* underlying branches having same dentry name as the non-dir dentry on
* which this unlink operation is called. This way we delete as many lower
* inodes as possible, and save space. Whiteouts need to be created in
* branch0 only if unlinking fails on any of the lower branch other than
* branch0, or if a lower branch is marked read-only.
*
* Also, while unlinking a file, if we encounter any dir type entry in any
* intermediate branch, then we remove the directory by calling vfs_rmdir.
* The following special cases are also handled:
* (1) If an error occurs in branch0 during vfs_unlink, then we return
* appropriate error.
*
* (2) If we get an error during unlink in any of other lower branch other
* than branch0, then we create a whiteout in branch0.
*
* (3) If a whiteout already exists in any intermediate branch, we delete
* all possible inodes only up to that branch (this is an "opaqueness"
* as as per Documentation/filesystems/unionfs/concepts.txt).
*
*/
static int unionfs_unlink_whiteout(struct inode *dir, struct dentry *dentry,
struct dentry *parent)
{
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
int bindex;
int err = 0;
err = unionfs_partial_lookup(dentry, parent);
if (err)
goto out;
/* trying to unlink all possible valid instances */
for (bindex = dbstart(dentry); bindex <= dbend(dentry); bindex++) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry || !lower_dentry->d_inode)
continue;
lower_dir_dentry = lock_parent(lower_dentry);
/* avoid destroying the lower inode if the object is in use */
dget(lower_dentry);
err = is_robranch_super(dentry->d_sb, bindex);
if (!err) {
/* see Documentation/filesystems/unionfs/issues.txt */
lockdep_off();
if (!S_ISDIR(lower_dentry->d_inode->i_mode))
err = vfs_unlink(lower_dir_dentry->d_inode,
lower_dentry, NULL);
else
err = vfs_rmdir(lower_dir_dentry->d_inode,
lower_dentry);
lockdep_on();
}
/* if lower object deletion succeeds, update inode's times */
if (!err)
unionfs_copy_attr_times(dentry->d_inode);
dput(lower_dentry);
fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
unlock_dir(lower_dir_dentry);
if (err)
break;
}
/*
* Create the whiteout in branch 0 (highest priority) only if (a)
* there was an error in any intermediate branch other than branch 0
* due to failure of vfs_unlink/vfs_rmdir or (b) a branch marked or
* mounted read-only.
*/
if (err) {
if ((bindex == 0) ||
((bindex == dbstart(dentry)) &&
(!IS_COPYUP_ERR(err))))
goto out;
else {
if (!IS_COPYUP_ERR(err))
pr_debug("unionfs: lower object deletion "
"failed in branch:%d\n", bindex);
err = create_whiteout(dentry, sbstart(dentry->d_sb));
}
}
out:
if (!err)
inode_dec_link_count(dentry->d_inode);
/* We don't want to leave negative leftover dentries for revalidate. */
if (!err && (dbopaque(dentry) != -1))
update_bstart(dentry);
return err;
}
int unionfs_unlink(struct inode *dir, struct dentry *dentry)
{
int err = 0;
struct inode *inode = dentry->d_inode;
struct dentry *parent;
int valid;
BUG_ON(S_ISDIR(inode->i_mode));
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out;
}
unionfs_check_dentry(dentry);
err = unionfs_unlink_whiteout(dir, dentry, parent);
/* call d_drop so the system "forgets" about us */
if (!err) {
unionfs_postcopyup_release(dentry);
unionfs_postcopyup_setmnt(parent);
if (inode->i_nlink == 0) /* drop lower inodes */
iput_lowers_all(inode, false);
d_drop(dentry);
/*
* if unlink/whiteout succeeded, parent dir mtime has
* changed
*/
unionfs_copy_attr_times(dir);
}
out:
if (!err) {
unionfs_check_dentry(dentry);
unionfs_check_inode(dir);
}
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
static int unionfs_rmdir_first(struct inode *dir, struct dentry *dentry,
struct unionfs_dir_state *namelist)
{
int err;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry = NULL;
/* Here we need to remove whiteout entries. */
err = delete_whiteouts(dentry, dbstart(dentry), namelist);
if (err)
goto out;
lower_dentry = unionfs_lower_dentry(dentry);
lower_dir_dentry = lock_parent(lower_dentry);
/* avoid destroying the lower inode if the file is in use */
dget(lower_dentry);
err = is_robranch(dentry);
if (!err)
err = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
dput(lower_dentry);
fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
/* propagate number of hard-links */
set_nlink(dentry->d_inode, unionfs_get_nlinks(dentry->d_inode));
out:
if (lower_dir_dentry)
unlock_dir(lower_dir_dentry);
return err;
}
int unionfs_rmdir(struct inode *dir, struct dentry *dentry)
{
int err = 0;
struct unionfs_dir_state *namelist = NULL;
struct dentry *parent;
int dstart, dend;
bool valid;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out;
}
unionfs_check_dentry(dentry);
/* check if this unionfs directory is empty or not */
err = check_empty(dentry, parent, &namelist);
if (err)
goto out;
err = unionfs_rmdir_first(dir, dentry, namelist);
dstart = dbstart(dentry);
dend = dbend(dentry);
/*
* We create a whiteout for the directory if there was an error to
* rmdir the first directory entry in the union. Otherwise, we
* create a whiteout only if there is no chance that a lower
* priority branch might also have the same named directory. IOW,
* if there is not another same-named directory at a lower priority
* branch, then we don't need to create a whiteout for it.
*/
if (!err) {
if (dstart < dend)
err = create_whiteout(dentry, dstart);
} else {
int new_err;
if (dstart == 0)
goto out;
/* exit if the error returned was NOT -EROFS */
if (!IS_COPYUP_ERR(err))
goto out;
new_err = create_whiteout(dentry, dstart - 1);
if (new_err != -EEXIST)
err = new_err;
}
out:
/*
* Drop references to lower dentry/inode so storage space for them
* can be reclaimed. Then, call d_drop so the system "forgets"
* about us.
*/
if (!err) {
iput_lowers_all(dentry->d_inode, false);
dput(unionfs_lower_dentry_idx(dentry, dstart));
unionfs_set_lower_dentry_idx(dentry, dstart, NULL);
d_drop(dentry);
/* update our lower vfsmnts, in case a copyup took place */
unionfs_postcopyup_setmnt(dentry);
unionfs_check_dentry(dentry);
unionfs_check_inode(dir);
}
if (namelist)
free_rdstate(namelist);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}

573
fs/unionfs/whiteout.c Normal file
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/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/*
* whiteout and opaque directory helpers
*/
/* What do we use for whiteouts. */
#define UNIONFS_WHPFX ".wh."
#define UNIONFS_WHLEN 4
/*
* If a directory contains this file, then it is opaque. We start with the
* .wh. flag so that it is blocked by lookup.
*/
#define UNIONFS_DIR_OPAQUE_NAME "__dir_opaque"
#define UNIONFS_DIR_OPAQUE UNIONFS_WHPFX UNIONFS_DIR_OPAQUE_NAME
/* construct whiteout filename */
char *alloc_whname(const char *name, int len)
{
char *buf;
buf = kmalloc(len + UNIONFS_WHLEN + 1, GFP_KERNEL);
if (unlikely(!buf))
return ERR_PTR(-ENOMEM);
strcpy(buf, UNIONFS_WHPFX);
strlcat(buf, name, len + UNIONFS_WHLEN + 1);
return buf;
}
/*
* XXX: this can be inline or CPP macro, but is here to keep all whiteout
* code in one place.
*/
void unionfs_set_max_namelen(long *namelen)
{
*namelen -= UNIONFS_WHLEN;
}
/* check if @namep is a whiteout, update @namep and @namelenp accordingly */
bool is_whiteout_name(char **namep, int *namelenp)
{
if (*namelenp > UNIONFS_WHLEN &&
!strncmp(*namep, UNIONFS_WHPFX, UNIONFS_WHLEN)) {
*namep += UNIONFS_WHLEN;
*namelenp -= UNIONFS_WHLEN;
return true;
}
return false;
}
/* is the filename valid == !(whiteout for a file or opaque dir marker) */
bool is_validname(const char *name)
{
if (!strncmp(name, UNIONFS_WHPFX, UNIONFS_WHLEN))
return false;
if (!strncmp(name, UNIONFS_DIR_OPAQUE_NAME,
sizeof(UNIONFS_DIR_OPAQUE_NAME) - 1))
return false;
return true;
}
/*
* Look for a whiteout @name in @lower_parent directory. If error, return
* ERR_PTR. Caller must dput() the returned dentry if not an error.
*
* XXX: some callers can reuse the whname allocated buffer to avoid repeated
* free then re-malloc calls. Need to provide a different API for those
* callers.
*/
struct dentry *lookup_whiteout(const char *name, struct dentry *lower_parent)
{
char *whname = NULL;
int err = 0, namelen;
struct dentry *wh_dentry = NULL;
namelen = strlen(name);
whname = alloc_whname(name, namelen);
if (unlikely(IS_ERR(whname))) {
err = PTR_ERR(whname);
goto out;
}
/* check if whiteout exists in this branch: lookup .wh.foo */
wh_dentry = lookup_lck_len(whname, lower_parent, strlen(whname));
if (IS_ERR(wh_dentry)) {
err = PTR_ERR(wh_dentry);
goto out;
}
/* check if negative dentry (ENOENT) */
if (!wh_dentry->d_inode)
goto out;
/* whiteout found: check if valid type */
if (!S_ISREG(wh_dentry->d_inode->i_mode)) {
printk(KERN_ERR "unionfs: invalid whiteout %s entry type %d\n",
whname, wh_dentry->d_inode->i_mode);
dput(wh_dentry);
err = -EIO;
goto out;
}
out:
kfree(whname);
if (err)
wh_dentry = ERR_PTR(err);
return wh_dentry;
}
/* find and return first whiteout in parent directory, else ENOENT */
struct dentry *find_first_whiteout(struct dentry *dentry)
{
int bindex, bstart, bend;
struct dentry *parent, *lower_parent, *wh_dentry;
parent = dget_parent(dentry);
bstart = dbstart(parent);
bend = dbend(parent);
wh_dentry = ERR_PTR(-ENOENT);
for (bindex = bstart; bindex <= bend; bindex++) {
lower_parent = unionfs_lower_dentry_idx(parent, bindex);
if (!lower_parent)
continue;
wh_dentry = lookup_whiteout(dentry->d_name.name, lower_parent);
if (IS_ERR(wh_dentry))
continue;
if (wh_dentry->d_inode)
break;
dput(wh_dentry);
wh_dentry = ERR_PTR(-ENOENT);
}
dput(parent);
return wh_dentry;
}
/*
* Unlink a whiteout dentry. Returns 0 or -errno. Caller must hold and
* release dentry reference.
*/
int unlink_whiteout(struct dentry *wh_dentry)
{
int err;
struct dentry *lower_dir_dentry;
/* dget and lock parent dentry */
lower_dir_dentry = lock_parent_wh(wh_dentry);
/* see Documentation/filesystems/unionfs/issues.txt */
lockdep_off();
err = vfs_unlink(lower_dir_dentry->d_inode, wh_dentry, NULL);
lockdep_on();
unlock_dir(lower_dir_dentry);
/*
* Whiteouts are special files and should be deleted no matter what
* (as if they never existed), in order to allow this create
* operation to succeed. This is especially important in sticky
* directories: a whiteout may have been created by one user, but
* the newly created file may be created by another user.
* Therefore, in order to maintain Unix semantics, if the vfs_unlink
* above failed, then we have to try to directly unlink the
* whiteout. Note: in the ODF version of unionfs, whiteout are
* handled much more cleanly.
*/
if (err == -EPERM) {
struct inode *inode = lower_dir_dentry->d_inode;
err = inode->i_op->unlink(inode, wh_dentry);
}
if (err)
printk(KERN_ERR "unionfs: could not unlink whiteout %pd, "
"err = %d\n", wh_dentry, err);
return err;
}
/*
* Helper function when creating new objects (create, symlink, mknod, etc.).
* Checks to see if there's a whiteout in @lower_dentry's parent directory,
* whose name is taken from @dentry. Then tries to remove that whiteout, if
* found. If <dentry,bindex> is a branch marked readonly, return -EROFS.
* If it finds both a regular file and a whiteout, delete whiteout (this
* should never happen).
*
* Return 0 if no whiteout was found. Return 1 if one was found and
* successfully removed. Therefore a value >= 0 tells the caller that
* @lower_dentry belongs to a good branch to create the new object in).
* Return -ERRNO if an error occurred during whiteout lookup or in trying to
* unlink the whiteout.
*/
int check_unlink_whiteout(struct dentry *dentry, struct dentry *lower_dentry,
int bindex)
{
int err;
struct dentry *wh_dentry = NULL;
struct dentry *lower_dir_dentry = NULL;
/* look for whiteout dentry first */
lower_dir_dentry = dget_parent(lower_dentry);
wh_dentry = lookup_whiteout(dentry->d_name.name, lower_dir_dentry);
dput(lower_dir_dentry);
if (IS_ERR(wh_dentry)) {
err = PTR_ERR(wh_dentry);
goto out;
}
if (!wh_dentry->d_inode) { /* no whiteout exists*/
err = 0;
goto out_dput;
}
/* check if regular file and whiteout were both found */
if (unlikely(lower_dentry->d_inode))
printk(KERN_WARNING "unionfs: removing whiteout; regular "
"file exists in directory %pd (branch %d)\n",
lower_dir_dentry, bindex);
/* check if branch is writeable */
err = is_robranch_super(dentry->d_sb, bindex);
if (err)
goto out_dput;
/* .wh.foo has been found, so let's unlink it */
err = unlink_whiteout(wh_dentry);
if (!err)
err = 1; /* a whiteout was found and successfully removed */
out_dput:
dput(wh_dentry);
out:
return err;
}
/*
* Pass an unionfs dentry and an index. It will try to create a whiteout
* for the filename in dentry, and will try in branch 'index'. On error,
* it will proceed to a branch to the left.
*/
int create_whiteout(struct dentry *dentry, int start)
{
int bstart, bend, bindex;
struct dentry *lower_dir_dentry;
struct dentry *lower_dentry;
struct dentry *lower_wh_dentry;
char *name = NULL;
int err = -EINVAL;
verify_locked(dentry);
bstart = dbstart(dentry);
bend = dbend(dentry);
/* create dentry's whiteout equivalent */
name = alloc_whname(dentry->d_name.name, dentry->d_name.len);
if (unlikely(IS_ERR(name))) {
err = PTR_ERR(name);
goto out;
}
for (bindex = start; bindex >= 0; bindex--) {
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
if (!lower_dentry) {
/*
* if lower dentry is not present, create the
* entire lower dentry directory structure and go
* ahead. Since we want to just create whiteout, we
* only want the parent dentry, and hence get rid of
* this dentry.
*/
lower_dentry = create_parents(dentry->d_inode,
dentry,
dentry->d_name.name,
bindex);
if (!lower_dentry || IS_ERR(lower_dentry)) {
int ret = PTR_ERR(lower_dentry);
if (!IS_COPYUP_ERR(ret))
printk(KERN_ERR
"unionfs: create_parents for "
"whiteout failed: bindex=%d "
"err=%d\n", bindex, ret);
continue;
}
}
lower_wh_dentry =
lookup_lck_len(name, lower_dentry->d_parent,
dentry->d_name.len + UNIONFS_WHLEN);
if (IS_ERR(lower_wh_dentry))
continue;
/*
* The whiteout already exists. This used to be impossible,
* but now is possible because of opaqueness.
*/
if (lower_wh_dentry->d_inode) {
dput(lower_wh_dentry);
err = 0;
goto out;
}
lower_dir_dentry = lock_parent_wh(lower_wh_dentry);
err = is_robranch_super(dentry->d_sb, bindex);
if (!err)
err = vfs_create(lower_dir_dentry->d_inode,
lower_wh_dentry,
current_umask() & S_IRUGO,
0); // XXX: pass want_excl?
unlock_dir(lower_dir_dentry);
dput(lower_wh_dentry);
if (!err || !IS_COPYUP_ERR(err))
break;
}
/* set dbopaque so that lookup will not proceed after this branch */
if (!err)
dbopaque(dentry) = bindex;
out:
kfree(name);
return err;
}
/*
* Delete all of the whiteouts in a given directory for rmdir.
*
* lower directory inode should be locked
*/
static int do_delete_whiteouts(struct dentry *dentry, int bindex,
struct unionfs_dir_state *namelist)
{
int err = 0;
struct dentry *lower_dir_dentry = NULL;
struct dentry *lower_dentry;
char *name = NULL, *p;
struct inode *lower_dir;
int i;
struct list_head *pos;
struct filldir_node *cursor;
/* Find out lower parent dentry */
lower_dir_dentry = unionfs_lower_dentry_idx(dentry, bindex);
BUG_ON(!S_ISDIR(lower_dir_dentry->d_inode->i_mode));
lower_dir = lower_dir_dentry->d_inode;
BUG_ON(!S_ISDIR(lower_dir->i_mode));
err = -ENOMEM;
name = __getname();
if (unlikely(!name))
goto out;
strcpy(name, UNIONFS_WHPFX);
p = name + UNIONFS_WHLEN;
err = 0;
for (i = 0; !err && i < namelist->size; i++) {
list_for_each(pos, &namelist->list[i]) {
cursor =
list_entry(pos, struct filldir_node,
file_list);
/* Only operate on whiteouts in this branch. */
if (cursor->bindex != bindex)
continue;
if (!cursor->whiteout)
continue;
strlcpy(p, cursor->name, PATH_MAX - UNIONFS_WHLEN);
lower_dentry =
lookup_lck_len(name, lower_dir_dentry,
cursor->namelen +
UNIONFS_WHLEN);
if (IS_ERR(lower_dentry)) {
err = PTR_ERR(lower_dentry);
break;
}
if (lower_dentry->d_inode)
err = vfs_unlink(lower_dir, lower_dentry,
NULL);
dput(lower_dentry);
if (err)
break;
}
}
__putname(name);
/* After all of the removals, we should copy the attributes once. */
fsstack_copy_attr_times(dentry->d_inode, lower_dir_dentry->d_inode);
out:
return err;
}
void __delete_whiteouts(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
struct deletewh_args *d = &args->deletewh;
args->err = do_delete_whiteouts(d->dentry, d->bindex, d->namelist);
complete(&args->comp);
}
/* delete whiteouts in a dir (for rmdir operation) using sioq if necessary */
int delete_whiteouts(struct dentry *dentry, int bindex,
struct unionfs_dir_state *namelist)
{
int err;
struct super_block *sb;
struct dentry *lower_dir_dentry;
struct inode *lower_dir;
struct sioq_args args;
sb = dentry->d_sb;
BUG_ON(!S_ISDIR(dentry->d_inode->i_mode));
BUG_ON(bindex < dbstart(dentry));
BUG_ON(bindex > dbend(dentry));
err = is_robranch_super(sb, bindex);
if (err)
goto out;
lower_dir_dentry = unionfs_lower_dentry_idx(dentry, bindex);
BUG_ON(!S_ISDIR(lower_dir_dentry->d_inode->i_mode));
lower_dir = lower_dir_dentry->d_inode;
BUG_ON(!S_ISDIR(lower_dir->i_mode));
if (!inode_permission(lower_dir, MAY_WRITE | MAY_EXEC)) {
err = do_delete_whiteouts(dentry, bindex, namelist);
} else {
args.deletewh.namelist = namelist;
args.deletewh.dentry = dentry;
args.deletewh.bindex = bindex;
run_sioq(__delete_whiteouts, &args);
err = args.err;
}
out:
return err;
}
/****************************************************************************
* Opaque directory helpers *
****************************************************************************/
/*
* is_opaque_dir: returns 0 if it is NOT an opaque dir, 1 if it is, and
* -errno if an error occurred trying to figure this out.
*/
int is_opaque_dir(struct dentry *dentry, int bindex)
{
int err = 0;
struct dentry *lower_dentry;
struct dentry *wh_lower_dentry;
struct inode *lower_inode;
struct sioq_args args;
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
lower_inode = lower_dentry->d_inode;
BUG_ON(!S_ISDIR(lower_inode->i_mode));
mutex_lock(&lower_inode->i_mutex);
if (!inode_permission(lower_inode, MAY_EXEC)) {
wh_lower_dentry =
lookup_one_len(UNIONFS_DIR_OPAQUE, lower_dentry,
sizeof(UNIONFS_DIR_OPAQUE) - 1); // XXX: pass flags?
} else {
args.is_opaque.dentry = lower_dentry;
run_sioq(__is_opaque_dir, &args);
wh_lower_dentry = args.ret;
}
mutex_unlock(&lower_inode->i_mutex);
if (IS_ERR(wh_lower_dentry)) {
err = PTR_ERR(wh_lower_dentry);
goto out;
}
/* This is an opaque dir iff wh_lower_dentry is positive */
err = !!wh_lower_dentry->d_inode;
dput(wh_lower_dentry);
out:
return err;
}
void __is_opaque_dir(struct work_struct *work)
{
struct sioq_args *args = container_of(work, struct sioq_args, work);
args->ret = lookup_one_len(UNIONFS_DIR_OPAQUE,
args->is_opaque.dentry,
sizeof(UNIONFS_DIR_OPAQUE) - 1); // XXX: pass flags?
complete(&args->comp);
}
int make_dir_opaque(struct dentry *dentry, int bindex)
{
int err = 0;
struct dentry *lower_dentry, *diropq;
struct inode *lower_dir;
const struct cred *old_creds;
struct cred *new_creds;
/*
* Opaque directory whiteout markers are special files (like regular
* whiteouts), and should appear to the users as if they don't
* exist. They should be created/deleted regardless of directory
* search/create permissions, but only for the duration of this
* creation of the .wh.__dir_opaque: file. Note, this does not
* circumvent normal ->permission).
*/
new_creds = prepare_creds();
if (unlikely(!new_creds)) {
err = -ENOMEM;
goto out_err;
}
cap_raise(new_creds->cap_effective, CAP_DAC_READ_SEARCH);
cap_raise(new_creds->cap_effective, CAP_DAC_OVERRIDE);
old_creds = override_creds(new_creds);
lower_dentry = unionfs_lower_dentry_idx(dentry, bindex);
lower_dir = lower_dentry->d_inode;
BUG_ON(!S_ISDIR(dentry->d_inode->i_mode) ||
!S_ISDIR(lower_dir->i_mode));
mutex_lock(&lower_dir->i_mutex);
diropq = lookup_one_len(UNIONFS_DIR_OPAQUE, lower_dentry,
sizeof(UNIONFS_DIR_OPAQUE) - 1); // XXX: pass flags?
if (IS_ERR(diropq)) {
err = PTR_ERR(diropq);
goto out;
}
if (!diropq->d_inode)
err = vfs_create(lower_dir, diropq, S_IRUGO, 0); // XXX: pass want_excl?
if (!err)
dbopaque(dentry) = bindex;
dput(diropq);
out:
mutex_unlock(&lower_dir->i_mutex);
revert_creds(old_creds);
out_err:
return err;
}

173
fs/unionfs/xattr.c Normal file
View File

@ -0,0 +1,173 @@
/*
* Copyright (c) 2003-2014 Erez Zadok
* Copyright (c) 2003-2006 Charles P. Wright
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2005-2006 Junjiro Okajima
* Copyright (c) 2005 Arun M. Krishnakumar
* Copyright (c) 2004-2006 David P. Quigley
* Copyright (c) 2003-2004 Mohammad Nayyer Zubair
* Copyright (c) 2003 Puja Gupta
* Copyright (c) 2003 Harikesavan Krishnan
* Copyright (c) 2003-2014 Stony Brook University
* Copyright (c) 2003-2014 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include "union.h"
/* This is lifted from fs/xattr.c */
void *unionfs_xattr_alloc(size_t size, size_t limit)
{
void *ptr;
if (size > limit)
return ERR_PTR(-E2BIG);
if (!size) /* size request, no buffer is needed */
return NULL;
ptr = kmalloc(size, GFP_KERNEL);
if (unlikely(!ptr))
return ERR_PTR(-ENOMEM);
return ptr;
}
/*
* BKL held by caller.
* dentry->d_inode->i_mutex locked
*/
ssize_t unionfs_getxattr(struct dentry *dentry, const char *name, void *value,
size_t size)
{
struct dentry *lower_dentry = NULL;
struct dentry *parent;
int err = -EOPNOTSUPP;
bool valid;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out;
}
lower_dentry = unionfs_lower_dentry(dentry);
err = vfs_getxattr(lower_dentry, (char *) name, value, size);
out:
unionfs_check_dentry(dentry);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
/*
* BKL held by caller.
* dentry->d_inode->i_mutex locked
*/
int unionfs_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
struct dentry *lower_dentry = NULL;
struct dentry *parent;
int err = -EOPNOTSUPP;
bool valid;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out;
}
lower_dentry = unionfs_lower_dentry(dentry);
err = vfs_setxattr(lower_dentry, (char *) name, (void *) value,
size, flags);
out:
unionfs_check_dentry(dentry);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
/*
* BKL held by caller.
* dentry->d_inode->i_mutex locked
*/
int unionfs_removexattr(struct dentry *dentry, const char *name)
{
struct dentry *lower_dentry = NULL;
struct dentry *parent;
int err = -EOPNOTSUPP;
bool valid;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out;
}
lower_dentry = unionfs_lower_dentry(dentry);
err = vfs_removexattr(lower_dentry, (char *) name);
out:
unionfs_check_dentry(dentry);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}
/*
* BKL held by caller.
* dentry->d_inode->i_mutex locked
*/
ssize_t unionfs_listxattr(struct dentry *dentry, char *list, size_t size)
{
struct dentry *lower_dentry = NULL;
struct dentry *parent;
int err = -EOPNOTSUPP;
char *encoded_list = NULL;
bool valid;
unionfs_read_lock(dentry->d_sb, UNIONFS_SMUTEX_CHILD);
parent = unionfs_lock_parent(dentry, UNIONFS_DMUTEX_PARENT);
unionfs_lock_dentry(dentry, UNIONFS_DMUTEX_CHILD);
valid = __unionfs_d_revalidate(dentry, parent, false, 0);
if (unlikely(!valid)) {
err = -ESTALE;
goto out;
}
lower_dentry = unionfs_lower_dentry(dentry);
encoded_list = list;
err = vfs_listxattr(lower_dentry, encoded_list, size);
out:
unionfs_check_dentry(dentry);
unionfs_unlock_dentry(dentry);
unionfs_unlock_parent(dentry, parent);
unionfs_read_unlock(dentry->d_sb);
return err;
}

2
include/linux/namei.h
View File

@ -71,6 +71,8 @@ extern struct dentry *user_path_create(int, const char __user *, struct path *,
extern void done_path_create(struct path *, struct dentry *);
extern struct dentry *kern_path_locked(const char *, struct path *);
extern int kern_path_mountpoint(int, const char *, struct path *, unsigned int);
extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
const char *, unsigned int, struct path *);
extern struct dentry *lookup_one_len(const char *, struct dentry *, int);

5
include/linux/splice.h
View File

@ -84,6 +84,11 @@ extern ssize_t splice_to_pipe(struct pipe_inode_info *,
struct splice_pipe_desc *);
extern ssize_t splice_direct_to_actor(struct file *, struct splice_desc *,
splice_direct_actor *);
extern long vfs_splice_from(struct pipe_inode_info *pipe, struct file *out,
loff_t *ppos, size_t len, unsigned int flags);
extern long vfs_splice_to(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags);
/*
* for dynamic pipe sizing

22
include/linux/union_fs.h Normal file
View File

@ -0,0 +1,22 @@
/*
* Copyright (c) 2003-2013 Erez Zadok
* Copyright (c) 2005-2007 Josef 'Jeff' Sipek
* Copyright (c) 2003-2013 Stony Brook University
* Copyright (c) 2003-2013 The Research Foundation of SUNY
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#ifndef _LINUX_UNION_FS_H
#define _LINUX_UNION_FS_H
/*
* DEFINITIONS FOR USER AND KERNEL CODE:
*/
# define UNIONFS_IOCTL_INCGEN _IOR(0x15, 11, int)
# define UNIONFS_IOCTL_QUERYFILE _IOR(0x15, 15, int)
#endif /* _LINUX_UNIONFS_H */

2
include/uapi/linux/magic.h
View File

@ -52,6 +52,8 @@
#define REISER2FS_SUPER_MAGIC_STRING "ReIsEr2Fs"
#define REISER2FS_JR_SUPER_MAGIC_STRING "ReIsEr3Fs"
#define UNIONFS_SUPER_MAGIC 0xf15f083d
#define SMB_SUPER_MAGIC 0x517B
#define CGROUP_SUPER_MAGIC 0x27e0eb

1
security/security.c
View File

@ -553,6 +553,7 @@ int security_inode_permission(struct inode *inode, int mask)
return 0;
return security_ops->inode_permission(inode, mask);
}
EXPORT_SYMBOL(security_inode_permission);
int security_inode_setattr(struct dentry *dentry, struct iattr *attr)
{