dm flakey: add support for zoned block devices

With the development of file system support for zoned block devices
(e.g. f2fs), having dm-flakey support these devices is interesting
to improve testing.

Add host-aware and host-managed zoned block devices support to in
dm-flakey. The target type feature is set to DM_TARGET_ZONED_HM to
indicate support for host-managed models. Also add hooks for remapping
of REQ_OP_ZONE_RESET and REQ_OP_ZONE_REPORT bios. Additionally, in the
bio completion path, (backward) remapping of a zone report reply is
added.

Signed-off-by: Damien Le Moal <[e-mail]>
Reviewed-by: Hannes Reinecke <[e-mail]>
Reviewed-by: Bart Van Assche <[e-mail]>
Signed-off-by: Mike Snitzer <[e-mail]>

drivers/md/dm-flakey.c

···
 	struct flakey_c *fc = ti->private;
 
 	bio->bi_bdev = fc->dev->bdev;
-	if (bio_sectors(bio))
+	if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET)
 		bio->bi_iter.bi_sector =
 			flakey_map_sector(ti, bio->bi_iter.bi_sector);
 }
···
 	unsigned elapsed;
 	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
 	pb->bio_submitted = false;
+
+	/* Do not fail reset zone */
+	if (bio_op(bio) == REQ_OP_ZONE_RESET)
+		goto map_bio;
+
+	/* We need to remap reported zones, so remember the BIO iter */
+	if (bio_op(bio) == REQ_OP_ZONE_REPORT)
+		goto map_bio;
 
 	/* Are we alive ? */
 	elapsed = (jiffies - fc->start_time) / HZ;
···
 }
 
 static int flakey_end_io(struct dm_target *ti, struct bio *bio,
-		blk_status_t *error)
+			 blk_status_t *error)
 {
 	struct flakey_c *fc = ti->private;
 	struct per_bio_data *pb = dm_per_bio_data(bio, sizeof(struct per_bio_data));
+
+	if (bio_op(bio) == REQ_OP_ZONE_RESET)
+		return DM_ENDIO_DONE;
+
+	if (bio_op(bio) == REQ_OP_ZONE_REPORT) {
+		dm_remap_zone_report(ti, bio, fc->start);
+		return DM_ENDIO_DONE;
+	}
 
 	if (!*error && pb->bio_submitted && (bio_data_dir(bio) == READ)) {
 		if (fc->corrupt_bio_byte && (fc->corrupt_bio_rw == READ) &&
···
 
 static struct target_type flakey_target = {
 	.name   = "flakey",
-	.version = {1, 4, 0},
+	.version = {1, 5, 0},
+	.features = DM_TARGET_ZONED_HM,
 	.module = THIS_MODULE,
 	.ctr    = flakey_ctr,
 	.dtr    = flakey_dtr,