d_walk() might skip too much

when we find that a child has died while we'd been trying to ascend,
we should go into the first live sibling itself, rather than its sibling.

Off-by-one in question had been introduced in "deal with deadlock in
d_walk()" and the fix needs to be backported to all branches this one
has been backported to.

Cc: stable@vger.kernel.org # 3.2 and later
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

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;
         }