From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:56658 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932463AbdIRJRA (ORCPT ); Mon, 18 Sep 2017 05:17:00 -0400 From: Greg Kroah-Hartman Subject: [PATCH 4.9 45/78] xfs: fix multi-AG deadlock in xfs_bunmapi Date: Mon, 18 Sep 2017 11:11:54 +0200 Message-Id: <20170918091133.088816511@linuxfoundation.org> In-Reply-To: <20170918091126.077483037@linuxfoundation.org> References: <20170918091126.077483037@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , linux-xfs@vger.kernel.org, "Darrick J . Wong" , Christoph Hellwig , Nikolay Borisov 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ commit 5b094d6dac0451ad89b1dc088395c7b399b7e9e8 upstream. Just like in the allocator we must avoid touching multiple AGs out of order when freeing blocks, as freeing still locks the AGF and can cause the same AB-BA deadlocks as in the allocation path. Signed-off-by: Christoph Hellwig Reported-by: Nikolay Borisov Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Greg Kroah-Hartman --- fs/xfs/libxfs/xfs_bmap.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -5556,6 +5556,7 @@ __xfs_bunmapi( xfs_fsblock_t sum; xfs_filblks_t len = *rlen; /* length to unmap in file */ xfs_fileoff_t max_len; + xfs_agnumber_t prev_agno = NULLAGNUMBER, agno; trace_xfs_bunmap(ip, bno, len, flags, _RET_IP_); @@ -5658,6 +5659,17 @@ __xfs_bunmapi( ASSERT(ep != NULL); del = got; wasdel = isnullstartblock(del.br_startblock); + + /* + * Make sure we don't touch multiple AGF headers out of order + * in a single transaction, as that could cause AB-BA deadlocks. + */ + if (!wasdel) { + agno = XFS_FSB_TO_AGNO(mp, del.br_startblock); + if (prev_agno != NULLAGNUMBER && prev_agno > agno) + break; + prev_agno = agno; + } if (got.br_startoff < start) { del.br_startoff = start; del.br_blockcount -= start - got.br_startoff;