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2576737873
kernel-ark/fs
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Ian Kent 2576737873 autofs4: use look aside list for lookups 
A while ago a patch to resolve a deadlock during directory creation was
merged.  This delayed the hashing of lookup dentrys until the ->mkdir()
(or ->symlink()) operation completed to ensure we always went through
->lookup() instead of also having processes go through ->revalidate() so
our VFS locking remained consistent.

Now we are seeing a couple of side affects of that change in situations
with heavy mount activity.

Two cases have been identified:

1) When a mount request is triggered, due to the delayed hashing, the
   directory created by user space for the mount point doesn't have the
   DCACHE_AUTOFS_PENDING flag set.  In the case of an autofs multi-mount
   where a tree of mount point directories are created this can lead to
   the path walk continuing rather than the dentry being sent to the wait
   queue to wait for request completion.  This is because, if the pending
   flag isn't set, the criteria for deciding this is a mount in progress
   fails to hold, namely that the dentry is not a mount point and has no
   subdirectories.

2) A mount request dentry is initially created negative and unhashed.
   It remains this way until the ->mkdir() callback completes.  Since it
   is unhashed a fresh dentry is used when the user space mount request
   creates the mount point directory.  This leaves the original dentry
   negative and unhashed.  But revalidate has no way to tell the VFS that
   the dentry has changed, other than to force another ->lookup() by
   returning false, which is at best wastefull and at worst not possible.
   This results in an -ENOENT return from the original path walk when in
   fact the mount succeeded.

To resolve this we need to ensure that the same dentry is used in all
calls to ->lookup() during the course of a mount request.  This patch
achieves that by adding the initial dentry to a look aside list and
removes it at ->mkdir() or ->symlink() completion (or when the dentry is
released), since these are the only create operations autofs4 supports.

Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 10:47:31 -07:00
..
9p 9p: fix O_APPEND in legacy mode 2008-07-03 09:59:03 -05:00
adfs fs: replace remaining __FUNCTION__ occurrences 2008-04-30 08:29:54 -07:00
affs [PATCH] fix reservation discarding in affs 2008-05-06 13:45:33 -04:00
afs Fix various old email addresses for dwmw2 2008-06-06 11:29:10 -07:00
autofs mount options: fix autofs 2008-02-08 09:22:40 -08:00
autofs4 autofs4: use look aside list for lookups 2008-07-24 10:47:31 -07:00
befs byteorder: don't directly include linux/byteorder/generic.h 2008-05-16 12:01:45 -07:00
bfs fs: replace remaining __FUNCTION__ occurrences 2008-04-30 08:29:54 -07:00
cifs Merge commit 'v2.6.26' into bkl-removal 2008-07-14 15:29:34 -06:00
coda device create: coda: convert device_create to device_create_drvdata 2008-07-21 21:54:41 -07:00
configfs configfs: Allow ->make_item() and ->make_group() to return detailed errors. 2008-07-17 15:21:29 -07:00
cramfs fs: Remove unnecessary inclusions of asm/semaphore.h 2008-04-18 22:16:44 -04:00
debugfs debugfs: Implement debugfs_remove_recursive() 2008-07-21 21:54:59 -07:00
devpts devpts: factor out PTY index allocation 2008-04-30 08:29:48 -07:00
dlm configfs: Allow ->make_item() and ->make_group() to return detailed errors. 2008-07-17 15:21:29 -07:00
ecryptfs eCryptfs: Make all persistent file opens delayed 2008-07-24 10:47:31 -07:00
efs efs: update error msg to not refer to deleted read_inode() 2008-04-02 15:28:19 -07:00
exportfs fs: replace remaining __FUNCTION__ occurrences 2008-04-30 08:29:54 -07:00
ext2 ext2: retry block allocation if new blocks are allocated from system zone 2008-04-28 08:58:43 -07:00
ext3 ext3: add missing unlock to error path in ext3_quota_write() 2008-07-04 10:40:05 -07:00
ext4 ext4: do not set extents feature from the kernel 2008-07-11 19:27:31 -04:00
fat Merge commit 'v2.6.26' into bkl-removal 2008-07-14 15:29:34 -06:00
freevxfs fs/freevxfs/: proper externs 2008-04-29 08:06:00 -07:00
fuse fuse: fix thinko in max I/O size calucation 2008-06-17 18:08:10 -07:00
gfs2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-nmw 2008-07-15 10:38:46 -07:00
hfs hfs: fix warning with 64k PAGE_SIZE 2008-04-30 08:29:52 -07:00
hfsplus Fix hfsplus oops on image without extents 2008-05-13 08:02:24 -07:00
hostfs uml: fix hostfs tv_usec calculations 2008-02-05 09:44:30 -08:00
hpfs mount options: fix hpfs 2008-02-08 09:22:40 -08:00
hppfs fix hppfs Makefile breakage 2008-05-21 16:55:58 -07:00
hugetlbfs hugetlbfs: per mount huge page sizes 2008-07-24 10:47:17 -07:00
isofs isofs: fix access to unallocated memory when reading corrupted filesystem 2008-04-30 08:29:33 -07:00
jbd jbd: need to hold j_state_lock to updates to transaction t_state to T_COMMIT 2008-05-14 19:11:14 -07:00
jbd2 ext4: Add ordered mode support for delalloc 2008-07-11 19:27:31 -04:00
jffs2 Merge git://git.infradead.org/mtd-2.6 2008-05-01 11:15:28 -07:00
jfs jfs: remove DIRENTSIZ 2008-06-10 15:12:58 -05:00
lockd Merge branch 'for-2.6.27' of git://linux-nfs.org/~bfields/linux 2008-07-20 21:21:46 -07:00
minix iget: stop the MINIX filesystem from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
msdos Replace BKL with superblock lock in fat/msdos/vfat 2008-06-20 14:05:54 -06:00
ncpfs Remove BKL from remote_llseek v2 2008-07-02 15:06:27 -06:00
nfs Merge branch 'bkl-removal' into next 2008-07-15 18:34:58 -04:00
nfs_common
nfsd Merge branch 'for-2.6.27' of git://linux-nfs.org/~bfields/linux 2008-07-20 21:21:46 -07:00
nls
ntfs ntfs: le*_add_cpu conversion 2008-05-24 09:56:08 -07:00
ocfs2 configfs: Allow ->make_item() and ->make_group() to return detailed errors. 2008-07-17 15:21:29 -07:00
openpromfs iget: stop OPENPROMFS from using iget() and read_inode() 2008-02-07 08:42:29 -08:00
partitions driver core: remove KOBJ_NAME_LEN define 2008-07-21 21:54:52 -07:00
proc vmallocinfo: add NUMA information 2008-07-24 10:47:17 -07:00
qnx4 iget: stop QNX4 from using iget() and read_inode() 2008-02-07 08:42:28 -08:00
ramfs ramfs: enable splice write 2008-07-04 09:52:14 +02:00
reiserfs reiserfs: discard prealloc in reiserfs_delete_inode 2008-07-08 12:39:31 -07:00
romfs ROMFS: Fix up an error in iget removal 2008-03-19 18:53:36 -07:00
smbfs Remove BKL from remote_llseek v2 2008-07-02 15:06:27 -06:00
sysfs driver core: Suppress sysfs warnings for device_rename(). 2008-07-21 21:55:01 -07:00
sysv sysv: [bl]e*_add_cpu conversion 2008-04-30 08:29:52 -07:00
ubifs UBIFS: include to compilation 2008-07-15 17:35:24 +03:00
udf udf: Fix regression in UDF anchor block detection 2008-06-24 11:38:03 +02:00
ufs ufs: remove unneeded ufs_put_inode prototype 2008-05-13 08:02:23 -07:00
vfat Replace BKL with superblock lock in fat/msdos/vfat 2008-06-20 14:05:54 -06:00
xfs Fix reference counting race on log buffers 2008-07-11 11:37:18 -07:00
aio.c uml: activate_mm: remove the dead PF_BORROWED_MM check 2008-06-06 11:36:22 -07:00
anon_inodes.c flag parameters: NONBLOCK in anon_inode_getfd 2008-07-24 10:47:28 -07:00
attr.c
bad_inode.c iget: introduce a function to register iget failure 2008-02-07 08:42:26 -08:00
binfmt_aout.c fs/binfmt_aout.c: use printk_ratelimit() 2008-04-29 08:06:04 -07:00
binfmt_elf_fdpic.c nommu: fix ksize() abuse 2008-06-06 11:29:13 -07:00
binfmt_elf.c execve filename: document and export via auxiliary vector 2008-07-22 09:59:40 -07:00
binfmt_em86.c binfmt_misc.c: avoid potential kernel stack overflow 2008-04-29 08:06:04 -07:00
binfmt_flat.c nommu: fix ksize() abuse 2008-06-06 11:29:13 -07:00
binfmt_misc.c binfmt_misc: use simple_read_from_buffer() 2008-07-24 10:47:27 -07:00
binfmt_script.c binfmt_misc.c: avoid potential kernel stack overflow 2008-04-29 08:06:04 -07:00
binfmt_som.c [PATCH] sanitize handling of shared descriptor tables in failing execve() 2008-04-25 09:23:53 -04:00
bio-integrity.c block: integrity checkpatch cleanups 2008-07-03 13:21:13 +02:00
bio.c Add bvec_merge_data to handle stacked devices and ->merge_bvec() 2008-07-03 13:21:15 +02:00
block_dev.c [PATCH] fix cgroup-inflicted breakage in block_dev.c 2008-06-23 08:30:55 -04:00
buffer.c Merge branch 'generic-ipi' into generic-ipi-for-linus 2008-07-15 21:55:59 +02:00
char_dev.c Remove the lock_kernel() call from chrdev_open() 2008-06-20 14:05:53 -06:00
compat_binfmt_elf.c x86: compat_binfmt_elf 2008-01-30 13:31:46 +01:00
compat_ioctl.c Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/holtmann/bluetooth-2.6 2008-07-19 00:30:39 -07:00
compat.c flag parameters: signalfd 2008-07-24 10:47:27 -07:00
dcache.c fix soft lock up at NFS mount via per-SB LRU-list of unused dentries 2008-07-24 10:47:15 -07:00
dcookies.c d_path: Make d_path() use a struct path 2008-02-14 21:17:09 -08:00
direct-io.c Pagecache zeroing: zero_user_segment, zero_user_segments and zero_user 2008-02-05 09:44:13 -08:00
dnotify.c [PATCH] split linux/file.h 2008-05-01 13:08:16 -04:00
dquot.c quota: don't call sync_fs() from vfs_quota_off() when there's no quota turn off 2008-05-13 08:02:23 -07:00
drop_caches.c vfs: skip inodes without pages to free in drop_pagecache_sb() 2008-04-29 08:06:05 -07:00
eventfd.c flag parameters: check magic constants 2008-07-24 10:47:29 -07:00
eventpoll.c flag parameters add-on: remove epoll_create size param 2008-07-24 10:47:29 -07:00
exec.c mm: remove double indirection on tlb parameter to free_pgd_range() & Co 2008-07-24 10:47:15 -07:00
fcntl.c flag parameters: dup2 2008-07-24 10:47:28 -07:00
fifo.c
file_table.c [PATCH] split linux/file.h 2008-05-01 13:08:16 -04:00
file.c [PATCH] avoid multiplication overflows and signedness issues for max_fds 2008-05-16 17:22:52 -04:00
filesystems.c
fs-writeback.c VFS: export sync_sb_inodes 2008-07-14 19:10:52 +03:00
generic_acl.c
inode.c VFS: fix unused variable warning 2008-05-06 13:13:37 -07:00
inotify_user.c flag parameters: check magic constants 2008-07-24 10:47:29 -07:00
inotify.c inotify: remove debug code 2008-02-06 10:41:07 -08:00
internal.h [PATCH] move a bunch of declarations to fs/internal.h 2008-04-21 23:11:01 -04:00
ioctl.c make vfs_ioctl() static 2008-04-29 08:06:00 -07:00
ioprio.c cfq-iosched: relax IOPRIO_CLASS_IDLE restrictions 2008-01-28 11:38:15 +01:00
Kconfig Merge branch 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mfasheh/ocfs2 2008-07-17 10:55:51 -07:00
Kconfig.binfmt frv: don't offer BINFMT_FLAT 2008-06-06 11:29:08 -07:00
libfs.c add kernel-doc for simple_read_from_buffer and memory_read_from_buffer 2008-07-04 10:40:07 -07:00
locks.c [patch 4/4] flock: remove unused fields from file_lock_operations 2008-06-23 11:52:30 -04:00
Makefile Merge branch 'for_linus' of git://git.infradead.org/~dedekind/ubifs-2.6 2008-07-16 15:02:57 -07:00
mbcache.c vfs: fix possible deadlock in ext2, ext3, ext4 when using xattrs 2008-04-15 19:35:41 -07:00
mpage.c vfs: add hooks for ext4's delayed allocation support 2008-07-11 19:27:31 -04:00
namei.c [patch 3/4] vfs: fix ERR_PTR abuse in generic_readlink 2008-06-23 11:52:30 -04:00
namespace.c LSM/SELinux: show LSM mount options in /proc/mounts 2008-07-14 15:02:05 +10:00
nfsctl.c Introduce path_put() 2008-02-14 21:13:33 -08:00
no-block.c
open.c fs: check for statfs overflow 2008-07-24 10:47:19 -07:00
pipe.c flag parameters: NONBLOCK in pipe 2008-07-24 10:47:29 -07:00
pnode.c [patch 7/7] vfs: mountinfo: show dominating group id 2008-04-23 00:05:09 -04:00
pnode.h [patch 7/7] vfs: mountinfo: show dominating group id 2008-04-23 00:05:09 -04:00
posix_acl.c
quota_v1.c quota: do not allow setting of quota limits to too high values 2008-04-28 08:58:32 -07:00
quota_v2.c quota: le*_add_cpu conversion 2008-04-30 08:29:51 -07:00
quota.c quota: quota core changes for quotaon on remount 2008-04-28 08:58:33 -07:00
read_write.c Remove BKL from remote_llseek v2 2008-07-02 15:06:27 -06:00
read_write.h
readdir.c
select.c Fix performance regression on lmbench select benchmark 2008-06-22 12:23:15 -07:00
seq_file.c [patch 2/7] vfs: mountinfo: add seq_file_root() 2008-04-23 00:04:38 -04:00
signalfd.c flag parameters: check magic constants 2008-07-24 10:47:29 -07:00
splice.c splice: fix generic_file_splice_read() race with page invalidation 2008-07-04 09:52:14 +02:00
stack.c
stat.c Introduce path_put() 2008-02-14 21:13:33 -08:00
super.c fix soft lock up at NFS mount via per-SB LRU-list of unused dentries 2008-07-24 10:47:15 -07:00
sync.c SYNC_FILE_RANGE_WRITE may and will block. Document that. 2008-07-24 10:47:17 -07:00
timerfd.c flag parameters: check magic constants 2008-07-24 10:47:29 -07:00
utimes.c [patch for 2.6.26 4/4] vfs: utimensat(): fix write access check for futimens() 2008-06-23 08:43:52 -04:00
xattr_acl.c
xattr.c xattr: add missing consts to function arguments 2008-04-29 08:06:06 -07:00