From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id qB3NefNt067622 for ; Mon, 3 Dec 2012 17:40:41 -0600 Message-Id: <20121203144309.729176306@sgi.com> Date: Mon, 03 Dec 2012 17:42:18 -0600 From: Mark Tinguely Subject: [3.0-stable PATCH 10/36] xfs: Account log unmount transaction correctly References: <20121203144208.143464631@sgi.com> Content-Disposition: inline; filename=063 List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: stable@vger.kernel.org Cc: xfs@oss.sgi.com From: Dave Chinner Upstream commit: 3948659e30808fbaa7673bbe89de2ae9769e20a7 There have been a few reports of this warning appearing recently: XFS (dm-4): xlog_space_left: head behind tail tail_cycle = 129, tail_bytes = 20163072 GH cycle = 129, GH bytes = 20162880 The common cause appears to be lots of freeze and unfreeze cycles, and the output from the warnings indicates that we are leaking around 8 bytes of log space per freeze/unfreeze cycle. When we freeze the filesystem, we write an unmount record and that uses xlog_write directly - a special type of transaction, effectively. What it doesn't do, however, is correctly account for the log space it uses. The unmount record writes an 8 byte structure with a special magic number into the log, and the space this consumes is not accounted for in the log ticket tracking the operation. Hence we leak 8 bytes every unmount record that is written. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Ben Myers --- fs/xfs/xfs_log.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) Index: b/fs/xfs/xfs_log.c =================================================================== --- a/fs/xfs/xfs_log.c +++ b/fs/xfs/xfs_log.c @@ -531,8 +531,9 @@ xfs_log_unmount_write(xfs_mount_t *mp) .lv_iovecp = ®, }; - /* remove inited flag */ + /* remove inited flag, and account for space used */ tic->t_flags = 0; + tic->t_curr_res -= sizeof(magic); error = xlog_write(log, &vec, tic, &lsn, NULL, XLOG_UNMOUNT_TRANS); /* _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs