[XFS] Barriers need to be dynamically checked and switched off
If the underlying block device suddenly stops supporting barriers, we need
to handle the -EOPNOTSUPP error in a sane manner rather than shutting
down the filesystem. If we get this error, clear the barrier flag, reissue
the I/O, and tell the world bad things are occurring.
SGI-PV: 964544
SGI-Modid: xfs-linux-melb:xfs-kern:28568a
Signed-off-by: David Chinner <dgc@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Tim Shimmin <tes@sgi.com>
diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 9bfb69e..db09e1e 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -949,6 +949,19 @@
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,