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

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 656ce522a218..37b5afdaf698 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1239,13 +1239,13 @@ ascend:
                 /* 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;
         }