xfs: reset b_first_retry_time when clear the retry status of xfs_buf_t

After successful IO or permanent error, b_first_retry_time also
needs to be cleared, else the invalid first retry time will be
used by the next retry check.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_buf_item.c

@@ -1162,6 +1162,7 @@ xfs_buf_iodone_callbacks(
 	 */
 	bp->b_last_error = 0;
 	bp->b_retries = 0;
+	bp->b_first_retry_time = 0;
 
 	xfs_buf_do_callbacks(bp);
 	bp->b_fspriv = NULL;