[RFC PATCH v2 7/9] xfs: Add device retry

[Bob Liu <bob.liu@oracle.com>]

From: Allison Henderson <allison.henderson@oracle.com>

Check to see if the _xfs_buf_read fails.  If so loop over the
available mirrors and retry the read

Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
---
 fs/xfs/xfs_buf.c | 26 +++++++++++++++++++++++++-
 1 file changed, 25 insertions(+), 1 deletion(-)

diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index 6098195ecaf4..2c250221cb78 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -21,6 +21,7 @@
 #include <linux/migrate.h>
 #include <linux/backing-dev.h>
 #include <linux/freezer.h>
+#include <linux/blkdev.h>
 
 #include "xfs_format.h"
 #include "xfs_log_format.h"
@@ -824,6 +825,9 @@ xfs_buf_read_map(
 	const struct xfs_buf_ops *ops)
 {
 	struct xfs_buf		*bp;
+	struct request_queue	*q;
+	unsigned long		i;
+	int			retries = 0;
 
 	flags |= XBF_READ;
 
@@ -836,7 +840,27 @@ xfs_buf_read_map(
 	if (!(bp->b_flags & XBF_DONE)) {
 		XFS_STATS_INC(target->bt_mount, xb_get_read);
 		bp->b_ops = ops;
-		_xfs_buf_read(bp, flags);
+		q = bdev_get_queue(bp->b_target->bt_bdev);
+
+		if (bp->b_alt_retry)
+			retries = blk_queue_get_mirrors(q);
+
+		for (i = 0; i <= retries; i++) {
+			bp->b_error = 0;
+			_xfs_buf_read(bp, flags);
+
+			switch (bp->b_error) {
+			case -EIO:
+			case -EFSCORRUPTED:
+			case -EFSBADCRC:
+				/* loop again */
+				continue;
+			default:
+				goto retry_done;
+			}
+
+		}
+retry_done:
 		return bp;
 	}
 
-- 
2.17.1