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Ian Kent 8f63aaa8b9 autofs4: fix lookup deadlock 
A deadlock can occur when user space uses a signal (autofs version 4 uses
SIGCHLD for this) to effect expire completion.

The order of events is:

Expire process completes, but before being able to send SIGCHLD to it's parent
...

Another process walks onto a different mount point and drops the directory
inode semaphore prior to sending the request to the daemon as it must ...

A third process does an lstat on on the expired mount point causing it to wait
on expire completion (unfortunately) holding the directory semaphore.

The mount request then arrives at the daemon which does an lstat and,
deadlock.

For some time I was concerned about releasing the directory semaphore around
the expire wait in autofs4_lookup as well as for the mount call back.  I
finally realized that the last round of changes in this function made the
expiring dentry and the lookup dentry separate and distinct so the check and
possible wait can be done anywhere prior to the mount call back.  This patch
moves the check to just before the mount call back and inside the directory
inode mutex release.

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>
 		2009-04-01 08:59:23 -07:00
..
9p vfs: simple_set_mnt() should return void 2009-03-27 14:44:03 -04:00
adfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
affs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
afs proc 2/2: remove struct proc_dir_entry::owner 2009-03-31 01:14:44 +04:00
autofs constify dentry_operations: autofs, autofs4 2009-03-27 14:44:00 -04:00
autofs4 autofs4: fix lookup deadlock 2009-04-01 08:59:23 -07:00
befs
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bfs
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btrfs fs: fix page_mkwrite error cases in core code and btrfs 2009-04-01 08:59:14 -07:00
cifs proc 2/2: remove struct proc_dir_entry::owner 2009-03-31 01:14:44 +04:00
coda constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
configfs constify dentry_operations: configfs 2009-03-27 14:44:03 -04:00
cramfs
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debugfs
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devpts Merge code for single and multiple-instance mounts 2009-03-27 14:44:04 -04:00
dlm dlm: fix length calculation in compat code 2009-03-11 12:23:59 -05:00
ecryptfs ecryptfs: use kzfree() 2009-04-01 08:59:23 -07:00
efs
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exportfs
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ext2 ext2: Zero our b_size in ext2_quota_read() 2009-03-26 02:18:38 +01:00
ext3 Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-quota-2.6 2009-03-27 14:48:34 -07:00
ext4 mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
fat constify dentry_operations: FAT 2009-03-27 14:44:01 -04:00
freevxfs fs/Kconfig: move vxfs out 2009-01-22 13:15:58 +03:00
fuse mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
gfs2 mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
hfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
hfsplus constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
hostfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
hpfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
hppfs
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hugetlbfs mm: reintroduce and deprecate rlimit based access for SHM_HUGETLB 2009-04-01 08:59:12 -07:00
isofs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
jbd jbd: fix return value of journal_start_commit() 2009-02-11 14:25:35 -08:00
jbd2 jbd2: Avoid possible NULL dereference in jbd2_journal_begin_ordered_truncate() 2009-02-10 11:15:34 -05:00
jffs2 [JFFS2] fix mount crash caused by removed nodes 2009-02-21 11:09:29 +01:00
jfs proc 2/2: remove struct proc_dir_entry::owner 2009-03-31 01:14:44 +04:00
lockd NLM: Fix GRANT callback address comparison when IPv6 is enabled 2009-03-10 20:33:20 -04:00
minix Update my email address 2009-03-22 11:28:37 -07:00
ncpfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
nfs mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
nfs_common
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nfsd Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-quota-2.6 2009-03-27 14:48:34 -07:00
nls
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notify fs: avoid I_NEW inodes 2009-03-27 14:44:05 -04:00
ntfs ntfs: remove private wrapper of endian helpers 2009-04-01 08:59:18 -07:00
ocfs2 mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
omfs fs/Kconfig: move omfs out 2009-01-22 13:15:58 +03:00
openpromfs
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partitions Merge branch 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6 2009-03-26 16:04:22 -07:00
proc proc tty: remove struct tty_operations::read_proc 2009-04-01 08:59:10 -07:00
qnx4 fs/Kconfig: move qnx4 out 2009-01-22 13:15:59 +03:00
quota Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
ramfs ramfs: add support for "mode=" mount option 2009-04-01 08:59:22 -07:00
reiserfs Merge branch 'proc-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/adobriyan/proc 2009-03-30 16:06:04 -07:00
romfs fs/Kconfig: move romfs out 2009-01-22 13:15:59 +03:00
smbfs constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
squashfs Squashfs: Valid filesystems are flagged as bad by the corrupted fs patch 2009-03-12 03:23:48 +00:00
sysfs mm: page_mkwrite change prototype to match fault: fix sysfs 2009-04-01 08:59:14 -07:00
sysv constify dentry_operations: misc filesystems 2009-03-27 14:44:00 -04:00
ubifs mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
udf udf: Use lowercase names of quota functions 2009-03-26 02:18:36 +01:00
ufs Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
xfs mm: page_mkwrite change prototype to match fault 2009-04-01 08:59:14 -07:00
Kconfig quota: Move quota files into separate directory 2009-03-26 02:18:35 +01:00
Kconfig.binfmt
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Makefile quota: Move quota files into separate directory 2009-03-26 02:18:35 +01:00
aio.c aio: lookup_ioctx can return the wrong value when looking up a bogus context 2009-03-19 15:57:18 -07:00
anon_inodes.c constify dentry_operations: rest 2009-03-27 14:44:03 -04:00
attr.c vfs: Use lowercase names of quota functions 2009-03-26 02:18:35 +01:00
bad_inode.c
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binfmt_aout.c
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binfmt_elf.c elf core dump: fix get_user use 2009-02-06 17:34:07 -08:00
binfmt_elf_fdpic.c
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binfmt_em86.c
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binfmt_flat.c
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binfmt_misc.c
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binfmt_script.c
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binfmt_som.c
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bio-integrity.c block: add private bio_set for bio integrity allocations 2009-03-24 12:35:17 +01:00
bio.c block: add private bio_set for bio integrity allocations 2009-03-24 12:35:17 +01:00
block_dev.c fs: move bdev code out of buffer.c 2009-03-27 14:44:03 -04:00
buffer.c filesystem freeze: allow SysRq emergency thaw to thaw frozen filesystems 2009-04-01 08:59:17 -07:00
char_dev.c
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compat.c fix setuid sometimes doesn't 2009-03-28 17:30:00 -07:00
compat_binfmt_elf.c
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compat_ioctl.c Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6 2009-03-01 21:35:16 -08:00
dcache.c cleanup d_add_ci 2009-03-27 14:43:57 -04:00
dcookies.c
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direct-io.c
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drop_caches.c fs: avoid I_NEW inodes 2009-03-27 14:44:05 -04:00
eventfd.c epoll keyed wakeups: make eventfd use keyed wakeups 2009-04-01 08:59:20 -07:00
eventpoll.c epoll keyed wakeups: teach epoll about hints coming with the wakeup key 2009-04-01 08:59:20 -07:00
exec.c fix setuid sometimes doesn't 2009-03-28 17:30:00 -07:00
fcntl.c Fix a lockdep warning in fasync_helper() 2009-03-30 08:00:24 -06:00
fifo.c
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file.c
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file_table.c Merge branch 'bkl-removal' of git://git.lwn.net/linux-2.6 2009-03-26 16:14:02 -07:00
filesystems.c
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fs-writeback.c fs: new inode i_state corruption fix 2009-03-12 16:20:24 -07:00
generic_acl.c
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inode.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
internal.h fix setuid sometimes doesn't 2009-03-28 17:30:00 -07:00
ioctl.c Rationalize fasync return values 2009-03-16 08:34:35 -06:00
ioprio.c
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libfs.c vfs: simple_set_mnt() should return void 2009-03-27 14:44:03 -04:00
locks.c
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mbcache.c
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mpage.c
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namei.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
nfsctl.c
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no-block.c
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open.c vfs: Use lowercase names of quota functions 2009-03-26 02:18:35 +01:00
pipe.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
pnode.c
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pnode.h
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posix_acl.c
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read_write.c
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read_write.h
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readdir.c
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select.c
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seq_file.c cpumask: fix seq_bitmap_*() functions. 2009-03-30 22:05:11 +10:30
signalfd.c
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splice.c
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stack.c
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stat.c
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super.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6 2009-03-27 16:23:12 -07:00
sync.c Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-quota-2.6 2009-03-27 14:48:34 -07:00
timerfd.c timerfd: add flags check 2009-02-18 15:37:53 -08:00
utimes.c
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xattr.c
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xattr_acl.c
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