[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/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index b0f0e58..8d9298c 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -997,7 +997,18 @@
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);