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 (Postfix) with ESMTP id EAE3D7F37 for ; Thu, 23 Apr 2015 11:42:51 -0500 (CDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by relay3.corp.sgi.com (Postfix) with ESMTP id 7A59BAC004 for ; Thu, 23 Apr 2015 09:42:48 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id 7BaUgCkY420B4lUS (version=TLSv1 cipher=AES256-SHA bits=256 verify=NO) for ; Thu, 23 Apr 2015 09:42:47 -0700 (PDT) Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t3NGgkxd024449 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Thu, 23 Apr 2015 12:42:46 -0400 Received: from bfoster.bfoster (dhcp-41-237.bos.redhat.com [10.18.41.237]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t3NGgkf6014419 for ; Thu, 23 Apr 2015 12:42:46 -0400 From: Brian Foster Subject: [PATCH v2] xfs: always log the inode on unwritten extent conversion Date: Thu, 23 Apr 2015 12:42:44 -0400 Message-Id: <1429807364-33943-1-git-send-email-bfoster@redhat.com> 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 Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: xfs@oss.sgi.com The fsync() requirements for crash consistency on XFS are to flush file data and force any in-core inode updates to the log. We currently check whether the inode is pinned to identify whether the log needs to be forced, since a non-zero pin count generally represents an inode that has transactions awaiting a flush to the on-disk log. This is not sufficient in all cases, however. Reports of xfstests test generic/311 failures on ppc64/s390x hosts have identified failures to fsync outstanding inode modifications due to the inode not being pinned at the time of the fsync. This occurs because certain bmap updates can complete by logging bmapbt buffers but without ever dirtying (and thus pinning) the core inode. The following is a specific incarnation of this problem: $ mount $dev /mnt -o noatime,nobarrier $ for i in $(seq 0 2 31); do \ xfs_io -f -c "falloc $((i * 32768)) 32k" -c fsync /mnt/file; \ done $ xfs_io -c "pwrite -S 0 80k 16k" -c fsync -c "pwrite 76k 4k" -c fsync /mnt/file; \ hexdump /mnt/file; \ ./xfstests-dev/src/godown /mnt ... 0000000 0000 0000 0000 0000 0000 0000 0000 0000 * 0013000 cdcd cdcd cdcd cdcd cdcd cdcd cdcd cdcd * 0014000 0000 0000 0000 0000 0000 0000 0000 0000 * 00f8000 $ umount /mnt; mount ... $ hexdump /mnt/file 0000000 0000 0000 0000 0000 0000 0000 0000 0000 * 00f8000 In short, the unwritten extent conversion for the last write is lost despite the fact that an fsync executed before the filesystem was shutdown. Note that this is impossible to reproduce on v5 supers due to unconditional time callbacks for di_changecount and highly difficult to reproduce on CONFIG_HZ=1000 kernels due to those same callbacks frequently updating cmtime prior to the bmap update. CONFIG_HZ=100 reduces timer granularity enough to increase the odds that time updates are skipped and allows this to reproduce within a handful of attempts. To deal with this problem, make sure that the inode is logged in the unwritten extent conversion path. Fix up the logflags, if necessary, after the extent conversion to keep the extent update code consistent with the other extent update helpers. This fixup is not necessary for the other (hole, delay) extent helpers because they execute in the block allocation codepath, which already logs the inode for other reasons (e.g., for di_nblocks). Signed-off-by: Brian Foster --- v2: - Log inode unconditionally on unwritten extent conversion and retain the fsync pincount check. v1: http://oss.sgi.com/pipermail/xfs/2015-April/041468.html fs/xfs/libxfs/xfs_bmap.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c index aeffeaa..e74e42bf 100644 --- a/fs/xfs/libxfs/xfs_bmap.c +++ b/fs/xfs/libxfs/xfs_bmap.c @@ -4417,6 +4417,21 @@ xfs_bmapi_convert_unwritten( error = xfs_bmap_add_extent_unwritten_real(bma->tp, bma->ip, &bma->idx, &bma->cur, mval, bma->firstblock, bma->flist, &tmp_logflags); + /* + * Unwritten extent conversion might not have dirtied the inode + * depending on the extent state. Unlike block allocation (e.g., + * di_nblocks), there may be no other reason to log the inode in the + * unwritten extent conversion path. + * + * We need to make sure the inode is dirty in the transaction for the + * sake of fsync(), which will not force the log for this transaction + * unless it sees the inode pinned. This can only happen for btree + * format inodes so use XFS_ILOG_CORE. + */ + if (!error && !tmp_logflags) { + ASSERT(bma->cur); + tmp_logflags |= XFS_ILOG_CORE; + } bma->logflags |= tmp_logflags; if (error) return error; -- 1.9.3 _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs