md: disable WRITE SAME if it fails in underlayer disks

This makes md do the same thing as dm for write same IO failure. Please
see 7eee4ae(dm: disable WRITE SAME if it fails) for details why we need
this.

We did a little bit different than dm. Instead of disabling writesame in
the first IO error, we disable it till next writesame IO coming after
the first IO error. This way we don't need to clone a bio.

Also reported here: https://bugzilla.kernel.org/show_bug.cgi?id=118581

Suggested-by: NeilBrown <neilb@suse.com>
Acked-by: NeilBrown <neilb@suse.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/linear.c

@@ -291,6 +291,7 @@ static void linear_make_request(struct mddev *mddev, struct bio *bio)
 				trace_block_bio_remap(bdev_get_queue(split->bi_bdev),
 						      split, disk_devt(mddev->gendisk),
 						      bio_sector);
+			mddev_check_writesame(mddev, split);
 			generic_make_request(split);
 		}
 	} while (split != bio);

drivers/md/md.h

@@ -710,4 +710,11 @@ static inline void mddev_clear_unsupported_flags(struct mddev *mddev,
 {
 	mddev->flags &= ~unsupported_flags;
 }
+
+static inline void mddev_check_writesame(struct mddev *mddev, struct bio *bio)
+{
+	if (bio_op(bio) == REQ_OP_WRITE_SAME &&
+	    !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors)
+		mddev->queue->limits.max_write_same_sectors = 0;
+}
 #endif /* _MD_MD_H */

drivers/md/multipath.c

@@ -138,6 +138,7 @@ static void multipath_make_request(struct mddev *mddev, struct bio * bio)
 	mp_bh->bio.bi_opf |= REQ_FAILFAST_TRANSPORT;
 	mp_bh->bio.bi_end_io = multipath_end_request;
 	mp_bh->bio.bi_private = mp_bh;
+	mddev_check_writesame(mddev, &mp_bh->bio);
 	generic_make_request(&mp_bh->bio);
 	return;
 }

drivers/md/raid0.c

@@ -503,6 +503,7 @@ static void raid0_make_request(struct mddev *mddev, struct bio *bio)
 				trace_block_bio_remap(bdev_get_queue(split->bi_bdev),
 						      split, disk_devt(mddev->gendisk),
 						      bio_sector);
+			mddev_check_writesame(mddev, split);
 			generic_make_request(split);
 		}
 	} while (split != bio);