linux-kernel - [PATCH 3.12 047/111] d_walk() might skip too much

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Message-Id: <7ab65a19e352f341efaa56a4ee4c5ac34dfc29fc.1433943052.git.jslaby@suse.cz>
Date:	Wed, 10 Jun 2015 17:26:36 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 047/111] d_walk() might skip too much

From: Al Viro <viro@...iv.linux.org.uk>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 2159184ea01e4ae7d15f2017e296d4bc82d5aeb0 upstream.

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.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 fs/dcache.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index eb540b00d027..e619730ade4c 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1154,13 +1154,13 @@ 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;
 	}
-- 
2.4.2

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