Commit Graph

14612 Commits

Author SHA1 Message Date
Amerigo Wang
e2dbe12557 elf: fix one check-after-use
Check before use it.

Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-07-01 11:14:28 -07:00
Martin K. Petersen
7878cba9f0 block: Create bip slabs with embedded integrity vectors
This patch restores stacking ability to the block layer integrity
infrastructure by creating a set of dedicated bip slabs.  Each bip slab
has an embedded bio_vec array at the end.  This cuts down on memory
allocations and also simplifies the code compared to the original bvec
version.  Only the largest bip slab is backed by a mempool.  The pool is
contained in the bio_set so stacking drivers can ensure forward
progress.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <axboe@carl.(none)>
2009-07-01 10:56:25 +02:00
Wolfgang Illmeyer
752fa51e4c hostfs: set maximum filesize in superblock for proper LFS support
Maximum file size for hostfs mounts defaults to 2GB, so bigger files cannot be
read/written through hostfs. This patch initializes the maximum file size to
MAX_LFS_SIZE.

Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13531

Signed-off-by: Wolfgang Illmeyer <wolfgang@illmeyer.com>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-30 18:56:03 -07:00
Bryan Donlan
4d6c13f87d ext2: return -EIO not -ESTALE on directory traversal through deleted inode
ext2_iget() returns -ESTALE if invoked on a deleted inode, in order to
report errors to NFS properly.  However, in ext[234]_lookup(), this
-ESTALE can be propagated to userspace if the filesystem is corrupted such
that a directory entry references a deleted inode.  This leads to a
misleading error message - "Stale NFS file handle" - and confusion on the
part of the admin.

The bug can be easily reproduced by creating a new filesystem, making a
link to an unused inode using debugfs, then mounting and attempting to ls
-l said link.

This patch thus changes ext2_lookup to return -EIO if it receives -ESTALE
from ext2_iget(), as ext2 does for other filesystem metadata corruption;
and also invokes the appropriate ext*_error functions when this case is
detected.

Signed-off-by: Bryan Donlan <bdonlan@gmail.com>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-30 18:56:00 -07:00
KAMEZAWA Hiroyuki
341c87bf34 elf: limit max map count to safe value
With ELF, at generating coredump, some more headers other than used
vmas are added.

When max_map_count == 65536, a core generated by following kinds of
code can be unreadable because the number of ELF's program header is
written in 16bit in Ehdr (please see elf.h) and the number overflows.

==
	... = mmap(); (munmap, mprotect, etc...)
	if (failed)
		abort();
==

This can happen in mmap/munmap/mprotect/etc...which calls split_vma().

I think 65536 is not safe as _default_ and reduce it to 65530 is good
for avoiding unexpected corrupted core.

Anyway, max_map_count can be enlarged by sysctl if a user is brave..

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Jakub Jelinek <jakub@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-30 18:55:59 -07:00
Davide Libenzi
133890103b eventfd: revised interface and cleanups
Change the eventfd interface to de-couple the eventfd memory context, from
the file pointer instance.

Without such change, there is no clean way to racely free handle the
POLLHUP event sent when the last instance of the file* goes away.  Also,
now the internal eventfd APIs are using the eventfd context instead of the
file*.

This patch is required by KVM's IRQfd code, which is still under
development.

Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Gregory Haskins <ghaskins@novell.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-30 18:55:58 -07:00
Jiri Slaby
f7c2df9b55 AFS: Fix lock imbalance
Don't unlock on vfs_rejected_lock path in afs_do_setlk, since the lock
is unlocked after abort_attempt label.

Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-30 13:30:44 -07:00
Mimi Zohar
94e5d714f6 integrity: add ima_counts_put (updated)
This patch fixes an imbalance message as reported by J.R. Okajima.
The IMA file counters are incremented in ima_path_check. If the
actual open fails, such as ETXTBSY, decrement the counters to
prevent unnecessary imbalance messages.

Reported-by: J.R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-06-29 08:59:10 +10:00
Jeff Layton
f0a71eb820 cifs: fix fh_mutex locking in cifs_reopen_file
Fixes a regression caused by commit a6ce4932fb

When this lock was converted to a mutex, the locks were turned into
unlocks and vice-versa.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: Shirish Pargaonkar <shirishp@us.ibm.com>
Cc: Stable Tree <stable@kernel.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-27 23:46:43 +00:00
Linus Torvalds
aada1bc927 Merge git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/sfrench/cifs-2.6:
  [CIFS] remove unknown mount option warning message
  [CIFS] remove bkl usage from umount begin
  cifs: Fix incorrect return code being printed in cFYI messages
  [CIFS] cleanup asn handling for ntlmssp
  [CIFS] Copy struct *after* setting the port, instead of before.
  cifs: remove rw/ro options
  cifs: fix problems with earlier patches
  cifs: have cifs parse scope_id out of IPv6 addresses and use it
  [CIFS] Do not send tree disconnect if session is already disconnected
  [CIFS] Fix build break
  cifs: display scopeid in /proc/mounts
  cifs: add new routine for converting AF_INET and AF_INET6 addrs
  cifs: have cifs_show_options show forceuid/forcegid options
  cifs: remove unneeded NULL checks from cifs_show_options
2009-06-26 09:37:19 -07:00
Steve French
71a394faaa [CIFS] remove unknown mount option warning message
Jeff's previous patch which removed the unneeded rw/ro
parsing can cause a minor warning in dmesg (about the
unknown rw or ro mount option) at mount time. This
patch makes cifs ignore them in kernel to remove the warning
(they are already handled in the mount helper and VFS).

Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-26 04:07:18 +00:00
Steve French
ad8034f197 [CIFS] remove bkl usage from umount begin
The lock_kernel call moved into the fs for umount_begin
is not needed.  This adds a check to make sure we don't
call umount_begin twice on the same fs.

umount_begin for cifs is probably not needed and
may eventually be able to be removed, but in
the meantime this smaller patch is safe and
gets rid of the bkl from this path which provides
some benefit.

Acked-by: Jeff Layton <redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-26 03:25:49 +00:00
Suresh Jayaraman
0f3bc09ee1 cifs: Fix incorrect return code being printed in cFYI messages
FreeXid() along with freeing Xid does add a cifsFYI debug message that
prints rc (return code) as well. In some code paths where we set/return
error code after calling FreeXid(), incorrect error code is being
printed when cifsFYI is enabled.

This could be misleading in few cases. For eg.
In cifs_open() if cifs_fill_filedata() returns a valid pointer to
cifsFileInfo, FreeXid() prints rc=-13 whereas 0 is actually being
returned. Fix this by setting rc before calling FreeXid().

Basically convert

FreeXid(xid);			rc = -ERR;
return -ERR;		=>	FreeXid(xid);
				return rc;

[Note that Christoph would like to replace the GetXid/FreeXid
calls, which are primarily used for debugging.  This seems
like a good longer term goal, but although there is an
alternative tracing facility, there are no examples yet
available that I know of that we can use (yet) to
convert this cifs function entry/exit logging, and for
creating an identifier that we can use to correlate
all dmesg log entries for a particular vfs operation
(ie identify all log entries for a particular vfs
request to cifs: e.g. a particular close or read or write
or byte range lock call ... and just using the thread id
is harder).  Eventually when a replacement
for this is available (e.g. when NFS switches over and various
samples to look at in other file systems) we can remove the
GetXid/FreeXid macro but in the meantime multiple people
use this run time configurable logging all the time
for debugging, and Suresh's patch fixes a problem
which made it harder to notice some low
memory problems in the log so it is worthwhile
to fix this problem until a better logging
approach is able to be used]

Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 19:12:57 +00:00
Steve French
f46c7234e4 [CIFS] cleanup asn handling for ntlmssp
Also removes obsolete distinction between rawntlmssp and ntlmssp (in asn/SPNEGO)
since as jra noted we can always send raw ntlmssp in session setup now.

remove check for experimental runtime flag (/proc/fs/cifs/Experimental) in
ntlmssp path.

Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 03:07:48 +00:00
Simo Leone
6debdbc0ba [CIFS] Copy struct *after* setting the port, instead of before.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Simo Leone <simo@archlinux.org>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 02:44:43 +00:00
Jeff Layton
6459340cfc cifs: remove rw/ro options
cifs: remove rw/ro options

These options are handled at the VFS layer. They only ever set the
option in the smb_vol struct. Nothing was ever done with them afterward
anyway.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 02:33:01 +00:00
Jeff Layton
b48a485884 cifs: fix problems with earlier patches
cifs: fix problems with earlier patches

cifs_show_address hasn't been introduced yet, and fix a typo that was
silently fixed by a later patch in the series.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 02:32:57 +00:00
Jeff Layton
681bf72e48 cifs: have cifs parse scope_id out of IPv6 addresses and use it
This patch has CIFS look for a '%' in an IPv6 address. If one is
present then it will try to treat that value as a numeric interface
index suitable for stuffing into the sin6_scope_id field.

This should allow people to mount servers on IPv6 link-local addresses.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: David Holder <david@erion.co.uk>
Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 01:14:36 +00:00
Steve French
268875b9d1 [CIFS] Do not send tree disconnect if session is already disconnected
Noticed this when tree connect timed out (due to Samba server crash) -
we try to send a tree disconnect for a tid that does not exist
since we don't have a valid tree id yet. This checks that the
session is valid before sending the tree disconnect to handle
this case.

Signed-off-by: Steve French <sfrench@us.ibm.com>
2009-06-25 00:29:21 +00:00
Al Viro
d5bb68adda another race fix in jfs_check_acl()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 17:02:42 -04:00
Al Viro
72c04902d1 Get "no acls for this inode" right, fix shmem breakage
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 16:58:48 -04:00
Linus Torvalds
936940a9c7 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (23 commits)
  switch xfs to generic acl caching helpers
  helpers for acl caching + switch to those
  switch shmem to inode->i_acl
  switch reiserfs to inode->i_acl
  switch reiserfs to usual conventions for caching ACLs
  reiserfs: minimal fix for ACL caching
  switch nilfs2 to inode->i_acl
  switch btrfs to inode->i_acl
  switch jffs2 to inode->i_acl
  switch jfs to inode->i_acl
  switch ext4 to inode->i_acl
  switch ext3 to inode->i_acl
  switch ext2 to inode->i_acl
  add caching of ACLs in struct inode
  fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls
  cleanup __writeback_single_inode
  ... and the same for vfsmount id/mount group id
  Make allocation of anon devices cheaper
  update Documentation/filesystems/Locking
  devpts: remove module-related code
  ...
2009-06-24 10:03:12 -07:00
Linus Torvalds
d7ed9c05eb Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-udf-2.6:
  udf: remove redundant tests on unsigned
  udf: Use device size when drive reported bogus number of written blocks
2009-06-24 09:57:10 -07:00
Al Viro
1cbd20d820 switch xfs to generic acl caching helpers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:07 -04:00
Al Viro
073aaa1b14 helpers for acl caching + switch to those
helpers: get_cached_acl(inode, type), set_cached_acl(inode, type, acl),
forget_cached_acl(inode, type).

ubifs/xattr.c needed includes reordered, the rest is a plain switchover.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:07 -04:00
Al Viro
281eede032 switch reiserfs to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:06 -04:00
Al Viro
7a77b15d92 switch reiserfs to usual conventions for caching ACLs
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:06 -04:00
Al Viro
e68888bcb6 reiserfs: minimal fix for ACL caching
reiserfs uses NULL as "unknown" and ERR_PTR(-ENODATA) as "no ACL";
several codepaths store the former instead of the latter.

All those codepaths go through iset_acl() and all cases when it's
called with NULL acl are for the second variety, so the minimal
fix is to teach iset_acl() to deal with that.

Proper fix is to switch to more usual conventions and avoid back
and forth between internally used ERR_PTR(-ENODATA) and NULL
expected by the rest of the kernel.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:05 -04:00
Al Viro
d441b1c293 switch nilfs2 to inode->i_acl
Actually, get rid of private analog, since nothing in there is
using ACLs at all so far.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:05 -04:00
Al Viro
5affd88a10 switch btrfs to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:05 -04:00
Al Viro
290c263bf8 switch jffs2 to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:05 -04:00
Al Viro
05fc0790b6 switch jfs to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:04 -04:00
Al Viro
d4bfe2f76d switch ext4 to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:04 -04:00
Al Viro
6582a0e6f6 switch ext3 to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:17:04 -04:00
Al Viro
5e78b43568 switch ext2 to inode->i_acl
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:28 -04:00
Al Viro
f19d4a8fa6 add caching of ACLs in struct inode
No helpers, no conversions yet.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:27 -04:00
Ankit Jain
3e63cbb1ef fs: Add new pre-allocation ioctls to vfs for compatibility with legacy xfs ioctls
This patch adds ioctls to vfs for compatibility with legacy XFS
pre-allocation ioctls (XFS_IOC_*RESVP*). The implementation
effectively invokes sys_fallocate for the new ioctls.
Also handles the compat_ioctl case.
Note: These legacy ioctls are also implemented by OCFS2.

[AV: folded fixes from hch]

Signed-off-by: Ankit Jain <me@ankitjain.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:27 -04:00
Christoph Hellwig
01c031945f cleanup __writeback_single_inode
There is no reason to for the split between __writeback_single_inode and
__sync_single_inode, the former just does a couple of checks before
tail-calling the latter.  So merge the two, and while we're at it split
out the I_SYNC waiting case for data integrity writers, as it's
logically separate function.  Finally rename __writeback_single_inode to
writeback_single_inode.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:26 -04:00
Al Viro
f21f62208a ... and the same for vfsmount id/mount group id
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:26 -04:00
Al Viro
c63e09eccc Make allocation of anon devices cheaper
Standard trick - add a new variable (start) such that
for each n < start n is known to be busy.  Allocation can
skip checking everything in [0..start) and if it returns
n, we can set start to n + 1.  Freeing below start sets
start to what we'd just freed.

Of course, it still sucks if we do something like
	free 0
	allocate
	allocate
in a loop - still O(n^2) time.  However, on saner loads it
improves the things a lot and the entire thing is not worth
the trouble of switching to something with better worst-case
behaviour.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:25 -04:00
H. Peter Anvin
f6cc746bbb devpts: remove module-related code
These days, the devpts filesystem is closely integrated with the pty
memory management, and cannot be built as a module, even less removed
from the kernel.  Accordingly, remove all module-related stuff from
this filesystem.

[ v2: only remove code that's actually dead ]

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:24 -04:00
Trond Myklebust
3b22edc573 VFS: Switch init_mount_tree() to use the new create_mnt_ns() helper
Eliminates some duplicated code...

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:24 -04:00
J. R. Okajima
654f562c52 vfs: fix nd->root leak in do_filp_open()
commit 2a73787110 "Cache root in nameidata"
introduced a new member nd->root, but forgot to put it in do_filp_open().

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:24 -04:00
Christoph Hellwig
b5450d9c84 reiserfs: remove stray unlock_super in reiserfs_resize
Reiserfs doesn't use lock_super anywhere internally, and ->remount_fs
which calls reiserfs_resize does have it currently but also expects it
to be held on return, so there's no business for the unlock_super here.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked by Edward Shishkin <edward.shishkin@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-06-24 08:15:24 -04:00
Roel Kluin
3391faa4f1 udf: remove redundant tests on unsigned
first_block and goal are unsigned. When negative they are wrapped and caught by
the other test.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
2009-06-24 13:48:28 +02:00
Linus Torvalds
cf5434e894 Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec/ocfs2:
  ocfs2/trivial: Wrap ocfs2_sysfile_cluster_lock_key within define.
  ocfs2: Add lockdep annotations
  vfs: Set special lockdep map for dirs only if not set by fs
  ocfs2: Disable orphan scanning for local and hard-ro mounts
  ocfs2: Do not initialize lvb in ocfs2_orphan_scan_lock_res_init()
  ocfs2: Stop orphan scan as early as possible during umount
  ocfs2: Fix ocfs2_osb_dump()
  ocfs2: Pin journal head before accessing jh->b_committed_data
  ocfs2: Update atime in splice read if necessary.
  ocfs2: Provide the ocfs2_dlm_lvb_valid() stack API.
2009-06-23 19:36:02 -07:00
Trond Myklebust
b88f8a546f NFS: Correct the NFS mount path when following a referral
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-22 21:28:25 -07:00
Trond Myklebust
0b75b35c7c NFS: Fix nfs_path() to always return a '/' at the beginning of the path
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-22 21:28:25 -07:00
Trond Myklebust
c02d7adf8c NFSv4: Replace nfs4_path_walk() with VFS path lookup in a private namespace
As noted in the previous patch, the NFSv4 client mount code currently
has several limitations. If the mount path contains symlinks, or
referrals, or even if it just contains a '..', then the client code in
nfs4_path_walk() will fail with an error.

This patch replaces the nfs4_path_walk()-based lookup with a helper
function that sets up a private namespace to represent the namespace on the
server, then uses the ordinary VFS and NFS path lookup code to walk down the
mount path in that namespace.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-22 21:28:25 -07:00
Trond Myklebust
cf8d2c11cb VFS: Add VFS helper functions for setting up private namespaces
The purpose of this patch is to improve the remote mount path lookup
support for distributed filesystems such as the NFSv4 client.

When given a mount command of the form "mount server:/foo/bar /mnt", the
NFSv4 client is required to look up the filehandle for "server:/", and
then look up each component of the remote mount path "foo/bar" in order
to find the directory that is actually going to be mounted on /mnt.
Following that remote mount path may involve following symlinks,
crossing server-side mount points and even following referrals to
filesystem volumes on other servers.

Since the standard VFS path lookup code already supports walking paths
that contain all these features (using in-kernel automounts for
following referrals) we would like to be able to reuse that rather than
duplicate the full path traversal functionality in the NFSv4 client code.

This patch therefore defines a VFS helper function create_mnt_ns(), that
sets up a temporary filesystem namespace and attaches a root filesystem to
it. It exports the create_mnt_ns() and put_mnt_ns() function for use by
filesystem modules.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-06-22 21:28:25 -07:00