inotify: fix race
authorNick Piggin <npiggin@suse.de>
Wed, 6 Feb 2008 09:37:28 +0000 (01:37 -0800)
committerLinus Torvalds <torvalds@woody.linux-foundation.org>
Wed, 6 Feb 2008 18:41:06 +0000 (10:41 -0800)
commitd599e36a9ea85432587f4550acc113cd7549d12a
tree2baec196271ccafac682b4bdbef3690cca686221
parenteea63e0e8a60d00485b47fb6e75d9aa2566b989b
inotify: fix race

There is a race between setting an inode's children's "parent watched" flag
when placing the first watch on a parent, and instantiating new children of
that parent: a child could miss having its flags set by
set_dentry_child_flags, but then inotify_d_instantiate might still see
!inotify_inode_watched.

The solution is to set_dentry_child_flags after adding the watch.  Locking is
taken care of, because both set_dentry_child_flags and inotify_d_instantiate
hold dcache_lock and child->d_locks.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Robert Love <rlove@google.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Jan Kara <jack@ucw.cz>
Cc: Yan Zheng <yanzheng@21cn.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/inotify.c