From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Thu, 19 Apr 2007 00:37:26 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id l3J7bLfB009730 for ; Thu, 19 Apr 2007 00:37:23 -0700 Date: Thu, 19 Apr 2007 17:37:14 +1000 From: David Chinner Subject: review: handle barriers being switched off dynamically. Message-ID: <20070419073714.GU48531920@melbourne.sgi.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: xfs-dev Cc: xfs-oss As pointed out by Neil Brown, MD can switch barriers off dynamically underneath a mounted filesystem. If this happens to XFS, it will shutdown the filesystem immediately. Handle this more sanely by yelling into the syslog, retrying the I/O without barriers and if that is successful, turn off barriers. Also remove an unnecessary check when first checking to see if the underlying device supports barriers. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group --- fs/xfs/linux-2.6/xfs_buf.c | 13 ++++++++++++- fs/xfs/linux-2.6/xfs_super.c | 8 -------- fs/xfs/xfs_log.c | 13 +++++++++++++ 3 files changed, 25 insertions(+), 9 deletions(-) Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_buf.c =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_buf.c 2007-04-19 13:26:49.000000000 +1000 +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_buf.c 2007-04-19 13:27:01.733786992 +1000 @@ -1000,7 +1000,18 @@ xfs_buf_iodone_work( xfs_buf_t *bp = container_of(work, xfs_buf_t, b_iodone_work); - if (bp->b_iodone) + /* + * We can get an EOPNOTSUPP to ordered writes. Here we clear the + * ordered flag and reissue them. Because we can't tell the higher + * layers directly that they should not issue ordered I/O anymore, they + * need to check if the ordered flag was cleared during I/O completion. + */ + if ((bp->b_error == EOPNOTSUPP) && + (bp->b_flags & (XBF_ORDERED|XBF_ASYNC)) == (XBF_ORDERED|XBF_ASYNC)) { + XB_TRACE(bp, "ordered_retry", bp->b_iodone); + bp->b_flags &= ~XBF_ORDERED; + xfs_buf_iorequest(bp); + } else if (bp->b_iodone) (*(bp->b_iodone))(bp); else if (bp->b_flags & XBF_ASYNC) xfs_buf_relse(bp); Index: 2.6.x-xfs-new/fs/xfs/xfs_log.c =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/xfs_log.c 2007-04-19 13:27:00.245980891 +1000 +++ 2.6.x-xfs-new/fs/xfs/xfs_log.c 2007-04-19 13:27:01.753784386 +1000 @@ -961,6 +961,19 @@ xlog_iodone(xfs_buf_t *bp) l = iclog->ic_log; /* + * If the ordered flag has been removed by a lower + * layer, it means the underlyin device no longer supports + * barrier I/O. Warn loudly and turn off barriers. + */ + if ((l->l_mp->m_flags & XFS_MOUNT_BARRIER) && !XFS_BUF_ORDERED(bp)) { + l->l_mp->m_flags &= ~XFS_MOUNT_BARRIER; + xfs_fs_cmn_err(CE_WARN, l->l_mp, + "xlog_iodone: Barriers are no longer supported" + " by device. Disabling barriers\n"); + xfs_buftrace("XLOG_IODONE BARRIERS OFF", bp); + } + + /* * Race to shutdown the filesystem if we see an error. */ if (XFS_TEST_ERROR((XFS_BUF_GETERROR(bp)), l->l_mp, Index: 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c =================================================================== --- 2.6.x-xfs-new.orig/fs/xfs/linux-2.6/xfs_super.c 2007-04-19 13:27:00.277976721 +1000 +++ 2.6.x-xfs-new/fs/xfs/linux-2.6/xfs_super.c 2007-04-19 13:27:01.757783865 +1000 @@ -314,14 +314,6 @@ xfs_mountfs_check_barriers(xfs_mount_t * return; } - if (mp->m_ddev_targp->bt_bdev->bd_disk->queue->ordered == - QUEUE_ORDERED_NONE) { - xfs_fs_cmn_err(CE_NOTE, mp, - "Disabling barriers, not supported by the underlying device"); - mp->m_flags &= ~XFS_MOUNT_BARRIER; - return; - } - if (xfs_readonly_buftarg(mp->m_ddev_targp)) { xfs_fs_cmn_err(CE_NOTE, mp, "Disabling barriers, underlying device is readonly");