Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d599e36a9ea85432587f4550acc113cd7549d12a Commit: d599e36a9ea85432587f4550acc113cd7549d12a Parent: eea63e0e8a60d00485b47fb6e75d9aa2566b989b Author: Nick Piggin <[EMAIL PROTECTED]> AuthorDate: Wed Feb 6 01:37:28 2008 -0800 Committer: Linus Torvalds <[EMAIL PROTECTED]> CommitDate: Wed Feb 6 10:41:06 2008 -0800
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 <[EMAIL PROTECTED]> Cc: Robert Love <[EMAIL PROTECTED]> Cc: John McCutchan <[EMAIL PROTECTED]> Cc: Jan Kara <[EMAIL PROTECTED]> Cc: Yan Zheng <[EMAIL PROTECTED]> Signed-off-by: Andrew Morton <[EMAIL PROTECTED]> Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]> --- fs/inotify.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/inotify.c b/fs/inotify.c index 2c5b921..b2b109b 100644 --- a/fs/inotify.c +++ b/fs/inotify.c @@ -627,6 +627,7 @@ s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch, struct inode *inode, u32 mask) { int ret = 0; + int newly_watched; /* don't allow invalid bits: we don't want flags set */ mask &= IN_ALL_EVENTS | IN_ONESHOT; @@ -653,12 +654,18 @@ s32 inotify_add_watch(struct inotify_handle *ih, struct inotify_watch *watch, */ watch->inode = igrab(inode); - if (!inotify_inode_watched(inode)) - set_dentry_child_flags(inode, 1); - /* Add the watch to the handle's and the inode's list */ + newly_watched = !inotify_inode_watched(inode); list_add(&watch->h_list, &ih->watches); list_add(&watch->i_list, &inode->inotify_watches); + /* + * Set child flags _after_ adding the watch, so there is no race + * windows where newly instantiated children could miss their parent's + * watched flag. + */ + if (newly_watched) + set_dentry_child_flags(inode, 1); + out: mutex_unlock(&ih->mutex); mutex_unlock(&inode->inotify_mutex); - To unsubscribe from this list: send the line "unsubscribe git-commits-head" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html