From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753433AbbHBALe (ORCPT ); Sat, 1 Aug 2015 20:11:34 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:36040 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751849AbbHBAJt (ORCPT ); Sat, 1 Aug 2015 20:09:49 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Al Viro" Date: Sun, 02 Aug 2015 01:02:37 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 106/164] d_walk() might skip too much In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.70-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro 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 [bwh: Backported to 3.2: apply to the 3 copies of this logic we ended up with] Signed-off-by: Ben Hutchings --- fs/dcache.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1016,13 +1016,13 @@ ascend: /* might go back up the wrong parent if we have had a rename */ if (!locked && read_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; } @@ -1142,13 +1142,13 @@ ascend: /* might go back up the wrong parent if we have had a rename */ if (!locked && read_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; } @@ -2938,13 +2938,13 @@ ascend: /* might go back up the wrong parent if we have had a rename */ if (!locked && read_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; }