From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mort.rzone.de ([81.169.144.234]:50160 "EHLO mort.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752265Ab2HIGQz (ORCPT ); Thu, 9 Aug 2012 02:16:55 -0400 From: Arne Jansen To: chris.mason@fusionio.com, linux-btrfs@vger.kernel.org Cc: mitch.harder@sabayonlinux.org, jbacik@fusionio.com Subject: [PATCH v2] Btrfs: fix race in run_clustered_refs Date: Thu, 9 Aug 2012 08:16:53 +0200 Message-Id: <1344493013-8637-1-git-send-email-sensille@gmx.net> Sender: linux-btrfs-owner@vger.kernel.org List-ID: With commit commit d1270cd91f308c9d22b2804720c36ccd32dbc35e Author: Arne Jansen Date: Tue Sep 13 15:16:43 2011 +0200 Btrfs: put back delayed refs that are too new I added a window where the delayed_ref's head->ref_mod code can diverge from the sum of the remaining refs, because we release the head->mutex in the middle. This leads to btrfs_lookup_extent_info returning wrong numbers. This patch fixes this by adjusting the head's ref_mod with each delayed ref we run. Signed-off-by: Arne Jansen --- Changes v1->v2: Changed commit message. As Josef pointed out the race is new and has not been present before d1270cd9. The code is unchanged. --- fs/btrfs/extent-tree.c | 17 +++++++++++++++++ 1 files changed, 17 insertions(+), 0 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index e66dc9a..60d175a 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2318,6 +2318,23 @@ static noinline int run_clustered_refs(struct btrfs_trans_handle *trans, ref->in_tree = 0; rb_erase(&ref->rb_node, &delayed_refs->root); delayed_refs->num_entries--; + if (locked_ref) { + /* + * when we play the delayed ref, also correct the + * ref_mod on head + */ + switch (ref->action) { + case BTRFS_ADD_DELAYED_REF: + case BTRFS_ADD_DELAYED_EXTENT: + locked_ref->node.ref_mod -= ref->ref_mod; + break; + case BTRFS_DROP_DELAYED_REF: + locked_ref->node.ref_mod += ref->ref_mod; + break; + default: + WARN_ON(1); + } + } spin_unlock(&delayed_refs->lock); ret = run_one_delayed_ref(trans, root, ref, extent_op, -- 1.7.7.3