Thanks to Dan Carpenter for extending smatch to find bugs like this.
(This was found using a development version of smatch.)
Fixes: 36de928641
Reported-by: Dan Carpenter <dan.carpenter@oracle.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
When performing a same-directory rename, it's possible that adding or
setting the new directory entry will cause the directory to overflow
the inline data area, which causes the directory to be converted to an
extent-based directory. Under this circumstance it is necessary to
re-read the directory when deleting the old dirent because the "old
directory" context still points to i_block in the inode table, which
is now an extent tree root! The delete fails with an FS error, and
the subsequent fsck complains about incorrect link counts and
hardlinked directories.
Test case (originally found with flat_dir_test in the metadata_csum
test program):
# mkfs.ext4 -O inline_data /dev/sda
# mount /dev/sda /mnt
# mkdir /mnt/x
# touch /mnt/x/changelog.gz /mnt/x/copyright /mnt/x/README.Debian
# sync
# for i in /mnt/x/*; do mv $i $i.longer; done
# ls -la /mnt/x/
total 0
-rw-r--r-- 1 root root 0 Aug 25 12:03 changelog.gz.longer
-rw-r--r-- 1 root root 0 Aug 25 12:03 copyright
-rw-r--r-- 1 root root 0 Aug 25 12:03 copyright.longer
-rw-r--r-- 1 root root 0 Aug 25 12:03 README.Debian.longer
(Hey! Why are there four files now??)
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
If we run into some kind of error, such as ENOMEM, while calling
ext4_getblk() or ext4_dx_find_entry(), we need to make sure this error
gets propagated up to ext4_find_entry() and then to its callers. This
way, transient errors such as ENOMEM can get propagated to the VFS.
This is important so that the system calls return the appropriate
error, and also so that in the case of ext4_lookup(), we return an
error instead of a NULL inode, since that will result in a negative
dentry cache entry that will stick around long past the OOM condition
which caused a transient ENOMEM error.
Google-Bug-Id: #17142205
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@vger.kernel.org
Christoph Hellwig suggests:
1) make vfs_rename call ->rename2 if it exists instead of ->rename
2) switch all filesystems that you're adding NOREPLACE support for to
use ->rename2
3) see how many ->rename instances we'll have left after a few
iterations of 2.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Shuffle code around in ext4_orphan_add() and ext4_orphan_del() so that
we avoid taking global s_orphan_lock in some cases and hold it for
shorter time in other cases.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Use sbi pointer consistently in ext4_orphan_del() instead of opencoding
it sometimes. Also ext4_orphan_add() uses EXT4_SB(sb) often so create
sbi variable for it as well and use it.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
BH can not be NULL at this point, ext4_read_dirblock() always return
non null value, and we already have done all necessery checks.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cross rename (exchange source and dest) will need to call some of these
helpers for both source and dest, while overwriting rename currently only
calls them for one or the other. This also makes the code easier to
follow.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Move checking i_nlink from after ext4_get_first_dir_block() to before. The
check doesn't rely on the result of that function and the function only
fails on fs corruption, so the order shouldn't matter.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Need to split up ext4_rename() into helpers but there are too many local
variables involved, so create a new structure. This also, apparently,
makes the generated code size slightly smaller.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
If this flag is specified and the target of the rename exists then the
rename syscall fails with EEXIST.
The VFS does the existence checking, so it is trivial to enable for most
local filesystems. This patch only enables it in ext4.
For network filesystems the VFS check is not enough as there may be a race
between a remote create and the rename, so these filesystems need to handle
this flag in their ->rename() implementations to ensure atomicity.
Andy writes about why this is useful:
"The trivial answer: to eliminate the race condition from 'mv -i'.
Another answer: there's a common pattern to atomically create a file
with contents: open a temporary file, write to it, optionally fsync
it, close it, then link(2) it to the final name, then unlink the
temporary file.
The reason to use link(2) is because it won't silently clobber the destination.
This is annoying:
- It requires an extra system call that shouldn't be necessary.
- It doesn't work on (IMO sensible) filesystems that don't support
hard links (e.g. vfat).
- It's not atomic -- there's an intermediate state where both files exist.
- It's ugly.
The new rename flag will make this totally sensible.
To be fair, on new enough kernels, you can also use O_TMPFILE and
linkat to achieve the same thing even more cleanly."
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
functionality for bigalloc file systems.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 update from Ted Ts'o:
"Bug fixes and cleanups for ext4. We also enable the punch hole
functionality for bigalloc file systems"
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
ext4: delete "set but not used" variables
ext4: don't pass freed handle to ext4_walk_page_buffers
ext4: avoid clearing beyond i_blocks when truncating an inline data file
ext4: ext4_inode_is_fast_symlink should use EXT4_CLUSTER_SIZE
ext4: fix a typo in extents.c
ext4: use %pd printk specificer
ext4: standardize error handling in ext4_da_write_inline_data_begin()
ext4: retry allocation when inline->extent conversion failed
ext4: enable punch hole for bigalloc
Use the new %pd printk() specifier in Ext4 to replace passing of
dentry name or dentry name and name length * 2 with just passing the
dentry.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
cc: Andreas Dilger <adilger.kernel@dilger.ca>
cc: linux-ext4@vger.kernel.org
When ext4_rename() overwrites an already existing file, call
ext4_alloc_da_blocks() before starting the journal handle which
actually does the rename, instead of doing this afterwards. This
improves the likelihood that the contents will survive a crash if an
application replaces a file using the sequence:
1) write replacement contents to foo.new
2) <omit fsync of foo.new>
3) rename foo.new to foo
It is still not a guarantee, since ext4_alloc_da_blocks() is *not*
doing a file integrity sync; this means if foo.new is a very large
file, it may not be completely flushed out to disk.
However, for files smaller than a megabyte or so, any dirty pages
should be flushed out before we do the rename operation, and so at the
next journal commit, the CACHE FLUSH command will make sure al of
these pages are safely on the disk platter.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In ext4_rename(), don't start the journal handle until the the
directory entries have been successfully looked up.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Pull second set of VFS changes from Al Viro:
"Assorted f_pos race fixes, making do_splice_direct() safe to call with
i_mutex on parent, O_TMPFILE support, Jeff's locks.c series,
->d_hash/->d_compare calling conventions changes from Linus, misc
stuff all over the place."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
Document ->tmpfile()
ext4: ->tmpfile() support
vfs: export lseek_execute() to modules
lseek_execute() doesn't need an inode passed to it
block_dev: switch to fixed_size_llseek()
cpqphp_sysfs: switch to fixed_size_llseek()
tile-srom: switch to fixed_size_llseek()
proc_powerpc: switch to fixed_size_llseek()
ubi/cdev: switch to fixed_size_llseek()
pci/proc: switch to fixed_size_llseek()
isapnp: switch to fixed_size_llseek()
lpfc: switch to fixed_size_llseek()
locks: give the blocked_hash its own spinlock
locks: add a new "lm_owner_key" lock operation
locks: turn the blocked_list into a hashtable
locks: convert fl_link to a hlist_node
locks: avoid taking global lock if possible when waking up blocked waiters
locks: protect most of the file_lock handling with i_lock
locks: encapsulate the fl_link list handling
locks: make "added" in __posix_lock_file a bool
...
Both ext3 and ext4 htree_dirblock_to_tree() is just filling the
in-core rbtree for use by call_filldir(). All updates of ->f_pos are
done by the latter; bumping it here (on error) is obviously wrong - we
might very well have it nowhere near the block we'd found an error in.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
Zach reported a problem that if inline data is enabled, we don't
tell the difference between the offset of '.' and '..'. And a
getdents will fail if the user only want to get '.' and what's worse,
if there is a conversion happens when the user calls getdents
many times, he/she may get the same entry twice.
In theory, a dir block would also fail if it is converted to a
hashed-index based dir since f_pos will become a hash value, not the
real one, but it doesn't happen. And a deep investigation shows that
we uses a hash based solution even for a normal dir if the dir_index
feature is enabled.
So this patch just adds a new htree_inlinedir_to_tree for inline dir,
and if we find that the hash index is supported, we will do like what
we do for a dir block.
Reported-by: Zach Brown <zab@redhat.com>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Inode allocation transaction is pretty heavy (246 credits with quotas
and extents before previous patch, still around 200 after it). This is
mostly due to credits required for allocation of quota structures
(credits there are heavily overestimated but it's difficult to make
better estimates if we don't want to wire non-trivial assumptions about
quota format into filesystem).
So move quota initialization out of allocation transaction. That way
transaction for quota structure allocation will be started only if we
need to look up quota structure on disk (rare) and furthermore it will
be started for each quota type separately, not for all of them at once.
This reduces maximum transaction size to 34 is most cases and to 73 in
the worst case.
[ Modified by tytso to clean up the cleanup paths for error handling.
Also use a separate call to ext4_std_error() for each failure so it
is easier for someone who is debugging a problem in this function to
determine which function call failed. ]
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Pull vfs pile (part one) from Al Viro:
"Assorted stuff - cleaning namei.c up a bit, fixing ->d_name/->d_parent
locking violations, etc.
The most visible changes here are death of FS_REVAL_DOT (replaced with
"has ->d_weak_revalidate()") and a new helper getting from struct file
to inode. Some bits of preparation to xattr method interface changes.
Misc patches by various people sent this cycle *and* ocfs2 fixes from
several cycles ago that should've been upstream right then.
PS: the next vfs pile will be xattr stuff."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (46 commits)
saner proc_get_inode() calling conventions
proc: avoid extra pde_put() in proc_fill_super()
fs: change return values from -EACCES to -EPERM
fs/exec.c: make bprm_mm_init() static
ocfs2/dlm: use GFP_ATOMIC inside a spin_lock
ocfs2: fix possible use-after-free with AIO
ocfs2: Fix oops in ocfs2_fast_symlink_readpage() code path
get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero
target: writev() on single-element vector is pointless
export kernel_write(), convert open-coded instances
fs: encode_fh: return FILEID_INVALID if invalid fid_type
kill f_vfsmnt
vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op
nfsd: handle vfs_getattr errors in acl protocol
switch vfs_getattr() to struct path
default SET_PERSONALITY() in linux/elf.h
ceph: prepopulate inodes only when request is aborted
d_hash_and_lookup(): export, switch open-coded instances
9p: switch v9fs_set_create_acl() to inode+fid, do it before d_instantiate()
9p: split dropping the acls from v9fs_set_create_acl()
...
the "punch hole" functionality for inodes that are not using extent
maps.
In the bug fix category, we fixed some races in the AIO and fstrim
code, and some potential NULL pointer dereferences and memory leaks in
error handling code paths.
In the optimization category, we fixed a performance regression in the
jbd2 layer introduced by commit d9b0193 (introduced in v3.0) which
shows up in the AIM7 benchmark. We also further optimized jbd2 by
minimize the amount of time that transaction handles are held active.
This patch series also features some additional enhancement of the
extent status tree, which is now used to cache extent information in a
more efficient/compact form than what we use on-disk.
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Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Theodore Ts'o:
"The one new feature added in this patch series is the ability to use
the "punch hole" functionality for inodes that are not using extent
maps.
In the bug fix category, we fixed some races in the AIO and fstrim
code, and some potential NULL pointer dereferences and memory leaks in
error handling code paths.
In the optimization category, we fixed a performance regression in the
jbd2 layer introduced by commit d9b01934d5 ("jbd: fix fsync() tid
wraparound bug", introduced in v3.0) which shows up in the AIM7
benchmark. We also further optimized jbd2 by minimize the amount of
time that transaction handles are held active.
This patch series also features some additional enhancement of the
extent status tree, which is now used to cache extent information in a
more efficient/compact form than what we use on-disk."
* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (65 commits)
ext4: fix free clusters calculation in bigalloc filesystem
ext4: no need to remove extent if len is 0 in ext4_es_remove_extent()
ext4: fix xattr block allocation/release with bigalloc
ext4: reclaim extents from extent status tree
ext4: adjust some functions for reclaiming extents from extent status tree
ext4: remove single extent cache
ext4: lookup block mapping in extent status tree
ext4: track all extent status in extent status tree
ext4: let ext4_ext_map_blocks return EXT4_MAP_UNWRITTEN flag
ext4: rename and improbe ext4_es_find_extent()
ext4: add physical block and status member into extent status tree
ext4: refine extent status tree
ext4: use ERR_PTR() abstraction for ext4_append()
ext4: refactor code to read directory blocks into ext4_read_dirblock()
ext4: add debugging context for warning in ext4_da_update_reserve_space()
ext4: use KERN_WARNING for warning messages
jbd2: use module parameters instead of debugfs for jbd_debug
ext4: use module parameters instead of debugfs for mballoc_debug
ext4: start handle at the last possible moment when creating inodes
ext4: fix the number of credits needed for acl ops with inline data
...
Use ERR_PTR()/IS_ERR() abstraction instead of passing in a separate
pointer to an integer for the error code, as a code cleanup.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The code to read in directory blocks and verify their metadata
checksums was replicated in ten different places across
fs/ext4/namei.c, and the code was buggy in subtle ways in a number of
those replicated sites. In some cases, ext4_error() was called with a
training newline. In others, in particularly in empty_dir(), it was
possible to call ext4_dirent_csum_verify() on an index block, which
would trigger false warnings requesting the system adminsitrator to
run e2fsck.
By refactoring the code, we make the code more readable, as well as
shrinking the compiled object file by over 700 bytes and 50 lines of
code.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In ext4_{create,mknod,mkdir,symlink}(), don't start the journal handle
until the inode has been succesfully allocated. In order to do this,
we need to start the handle in the ext4_new_inode(). So create a new
variant of this function, ext4_new_inode_start_handle(), so the handle
can be created at the last possible minute, before we need to modify
the inode allocation bitmap block.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
The ext4_unlink() and ext4_rmdir() don't actually release the blocks
associated with the file/directory. This gets done in a separate jbd2
handle called via ext4_evict_inode(). Thus, we don't need to reserve
lots of journal credits for the truncate.
Note that using too many journal credits is non-optimal because it can
leading to the journal transmit getting closed too early, before it is
strictly necessary.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Don't start the jbd2 transaction handle until after the directory
entry has been found, to minimize the amount of time that a handle is
held active.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Don't start the jbd2 transaction handle until after the directory
entry has been found, to minimize the amount of time that a handle is
held active.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
So we can better understand what bits of ext4 are responsible for
long-running jbd2 handles, use jbd2__journal_start() so we can pass
context information for logging purposes.
The recommended way for finding the longer-running handles is:
T=/sys/kernel/debug/tracing
EVENT=$T/events/jbd2/jbd2_handle_stats
echo "interval > 5" > $EVENT/filter
echo 1 > $EVENT/enable
./run-my-fs-benchmark
cat $T/trace > /tmp/problem-handles
This will list handles that were active for longer than 20ms. Having
longer-running handles is bad, because a commit started at the wrong
time could stall for those 20+ milliseconds, which could delay an
fsync() or an O_SYNC operation. Here is an example line from the
trace file describing a handle which lived on for 311 jiffies, or over
1.2 seconds:
postmark-2917 [000] .... 196.435786: jbd2_handle_stats: dev 254,32
tid 570 type 2 line_no 2541 interval 311 sync 0 requested_blocks 1
dirtied_blocks 0
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
brelse() and ext4_journal_force_commit() are both inlined and able
to handle NULL.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
After commit 978fef9 (create __ext4_insert_dentry for dir entry
insertion), 'reclen' is not used anymore.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Commit b0336e8d (ext4: calculate and verify checksums of directory
leaf blocks) and commit dbe89444 (ext4: Calculate and verify checksums
for htree nodes) forget to release buffer when checksum failed, at
some places.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
This macro, initially introduced by ext2 in v0.99.15, does not
have any users from the beginning. It has been removed in later
ext2 version but still remains in the code of ext3, ext4, ocfs2.
Remove this macro there.
Cc: Jan Kara <jack@suse.cz>
Cc: linux-ext4@vger.kernel.org
Cc: ocfs2-devel@oss.oracle.com
Acked-by: Mark Fasheh <mfasheh@suse.de>
Acked-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This fixes a buffer cache leak when creating a directory, introduced
in commit a774f9c20.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Tao Ma <boyu.mt@taobao.com>
If checksum fails, we should also release the buffer
read from previous iteration.
Signed-off-by: Guo Chao <yan@linux.vnet.ibm.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>-
Cc: stable@vger.kernel.org
--
fs/ext4/namei.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
When trying to mount a file system which does not contain a journal,
but which does have a orphan list containing an inode which needs to
be truncated, the mount call with hang forever in
ext4_orphan_cleanup() because ext4_orphan_del() will return
immediately without removing the inode from the orphan list, leading
to an uninterruptible loop in kernel code which will busy out one of
the CPU's on the system.
This can be trivially reproduced by trying to mount the file system
found in tests/f_orphan_extents_inode/image.gz from the e2fsprogs
source tree. If a malicious user were to put this on a USB stick, and
mount it on a Linux desktop which has automatic mounts enabled, this
could be considered a potential denial of service attack. (Not a big
deal in practice, but professional paranoids worry about such things,
and have even been known to allocate CVE numbers for such problems.)
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
Cc: stable@vger.kernel.org
Ted has sent out a RFC about removing this feature. Eric and Jan
confirmed that both RedHat and SUSE enable this feature in all their
product. David also said that "As far as I know, it's enabled in all
Android kernels that use ext4." So it seems OK for us.
And what's more, as inline data depends its implementation on xattr,
and to be frank, I don't run any test again inline data enabled while
xattr disabled. So I think we should add inline data and remove this
config option in the same release.
[ The savings if you disable CONFIG_EXT4_FS_XATTR is only 27k, which
isn't much in the grand scheme of things. Since no one seems to be
testing this configuration except for some automated compile farms, on
balance we are better removing this config option, and so that it is
effectively always enabled. -- tytso ]
Cc: David Brown <davidb@codeaurora.org>
Cc: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
In case we rename a directory, ext4_rename has to read the dir block
and change its dotdot's information. The old ext4_rename encapsulated
the dir_block read into itself. So this patch adds a new function
ext4_get_first_dir_block() which gets the dir buffer information so
the ext4_rename can handle it properly. As it will also change the
parent inode number, we return the parent_de so that ext4_rename() can
handle it more easily.
ext4_find_entry is also changed so that the caller(rename) can tell
whether the found entry is an inlined one or not and journaling the
corresponding buffer head.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
empty_dir is used when deleting a dir. So it should handle inline dir
properly.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Currently ext4_delete_entry() is used only for dir entry removing from
a dir block. So let us create a new function
ext4_generic_delete_entry and this function takes a entry_buf and a
buf_size so that it can be used for inline data.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Create a new function ext4_find_inline_entry() to handle the case of
inline data.
Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Theodore Ts'o
Darrick J. Wong
Miklos Szeredi
Jan Kara
liang xie
Dmitry Monakhov
Linus Torvalds
Christoph Hellwig
David Howells
Zheng Liu
Al Viro
Tao Ma
Guo Chao