Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs fix from Al Viro:
"Off-by-one in d_walk()/__dentry_kill() race fix.
It's very hard to hit; possible in the same conditions as the original
bug, except that you need the skipped branch to contain all the
remaining evictables, so that the d_walk()-calling loop in
d_invalidate() decides there's nothing more to do and doesn't go for
another pass - otherwise that next pass will sweep the sucker.
So it's not too urgent, but seeing that the fix is obvious and the
original commit has spread into all -stable branches..."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
d_walk() might skip too much
diff --git a/fs/dcache.c b/fs/dcache.c
index 656ce52..37b5afd 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1239,13 +1239,13 @@
/* might go back up the wrong parent if we have had a rename. */
if (need_seqretry(&rename_lock, seq))
goto rename_retry;
- next = child->d_child.next;
- while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED)) {
+ /* go into the first sibling still alive */
+ do {
+ next = child->d_child.next;
if (next == &this_parent->d_subdirs)
goto ascend;
child = list_entry(next, struct dentry, d_child);
- next = next->next;
- }
+ } while (unlikely(child->d_flags & DCACHE_DENTRY_KILLED));
rcu_read_unlock();
goto resume;
}
