dm: support REQ_OP_WRITE_ZEROES

Copy & paste from the REQ_OP_WRITE_SAME code.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

drivers/md/dm-core.h

@@ -132,6 +132,7 @@ void dm_init_md_queue(struct mapped_device *md);
 void dm_init_normal_md_queue(struct mapped_device *md);
 int md_in_flight(struct mapped_device *md);
 void disable_write_same(struct mapped_device *md);
+void disable_write_zeroes(struct mapped_device *md);
 
 static inline struct completion *dm_get_completion_from_kobject(struct kobject *kobj)
 {

drivers/md/dm-io.c

@@ -312,9 +312,12 @@ static void do_region(int op, int op_flags, unsigned region,
 	 */
 	if (op == REQ_OP_DISCARD)
 		special_cmd_max_sectors = q->limits.max_discard_sectors;
+	else if (op == REQ_OP_WRITE_ZEROES)
+		special_cmd_max_sectors = q->limits.max_write_zeroes_sectors;
 	else if (op == REQ_OP_WRITE_SAME)
 		special_cmd_max_sectors = q->limits.max_write_same_sectors;
-	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_SAME) &&
+	if ((op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES ||
+	     op == REQ_OP_WRITE_SAME)  &&
 	    special_cmd_max_sectors == 0) {
 		dec_count(io, region, -EOPNOTSUPP);
 		return;
@@ -330,6 +333,7 @@ static void do_region(int op, int op_flags, unsigned region,
 		 */
 		switch (op) {
 		case REQ_OP_DISCARD:
+		case REQ_OP_WRITE_ZEROES:
 			num_bvecs = 0;
 			break;
 		case REQ_OP_WRITE_SAME:
@@ -347,7 +351,7 @@ static void do_region(int op, int op_flags, unsigned region,
 		bio_set_op_attrs(bio, op, op_flags);
 		store_io_and_region_in_bio(bio, io, region);
 
-		if (op == REQ_OP_DISCARD) {
+		if (op == REQ_OP_DISCARD || op == REQ_OP_WRITE_ZEROES) {
 			num_sectors = min_t(sector_t, special_cmd_max_sectors, remaining);
 			bio->bi_iter.bi_size = num_sectors << SECTOR_SHIFT;
 			remaining -= num_sectors;

drivers/md/dm-linear.c

@@ -59,6 +59,7 @@ static int linear_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
+	ti->num_write_zeroes_bios = 1;
 	ti->private = lc;
 	return 0;
 

drivers/md/dm-mpath.c

@@ -1103,6 +1103,7 @@ static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
 	ti->num_flush_bios = 1;
 	ti->num_discard_bios = 1;
 	ti->num_write_same_bios = 1;
+	ti->num_write_zeroes_bios = 1;
 	if (m->queue_mode == DM_TYPE_BIO_BASED)
 		ti->per_io_data_size = multipath_per_bio_data_size();
 	else

drivers/md/dm-rq.c

@@ -298,9 +298,14 @@ static void dm_done(struct request *clone, int error, bool mapped)
 			r = rq_end_io(tio->ti, clone, error, &tio->info);
 	}
 
-	if (unlikely(r == -EREMOTEIO && (req_op(clone) == REQ_OP_WRITE_SAME) &&
-		     !clone->q->limits.max_write_same_sectors))
+	if (unlikely(r == -EREMOTEIO)) {
+		if (req_op(clone) == REQ_OP_WRITE_SAME &&
+		    !clone->q->limits.max_write_same_sectors)
 			disable_write_same(tio->md);
+		if (req_op(clone) == REQ_OP_WRITE_ZEROES &&
+		    !clone->q->limits.max_write_zeroes_sectors)
+			disable_write_zeroes(tio->md);
+	}
 
 	if (r <= 0)
 		/* The target wants to complete the I/O */

drivers/md/dm-stripe.c

@@ -169,6 +169,7 @@ static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	ti->num_flush_bios = stripes;
 	ti->num_discard_bios = stripes;
 	ti->num_write_same_bios = stripes;
+	ti->num_write_zeroes_bios = stripes;
 
 	sc->chunk_size = chunk_size;
 	if (chunk_size & (chunk_size - 1))
@@ -293,6 +294,7 @@ static int stripe_map(struct dm_target *ti, struct bio *bio)
 		return DM_MAPIO_REMAPPED;
 	}
 	if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
+	    unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) ||
 	    unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
 		target_bio_nr = dm_bio_get_target_bio_nr(bio);
 		BUG_ON(target_bio_nr >= sc->stripes);

drivers/md/dm-table.c

@@ -1533,6 +1533,34 @@ static bool dm_table_supports_write_same(struct dm_table *t)
 	return true;
 }
 
+static int device_not_write_zeroes_capable(struct dm_target *ti, struct dm_dev *dev,
+					   sector_t start, sector_t len, void *data)
+{
+	struct request_queue *q = bdev_get_queue(dev->bdev);
+
+	return q && !q->limits.max_write_zeroes_sectors;
+}
+
+static bool dm_table_supports_write_zeroes(struct dm_table *t)
+{
+	struct dm_target *ti;
+	unsigned i = 0;
+
+	while (i < dm_table_get_num_targets(t)) {
+		ti = dm_table_get_target(t, i++);
+
+		if (!ti->num_write_zeroes_bios)
+			return false;
+
+		if (!ti->type->iterate_devices ||
+		    ti->type->iterate_devices(ti, device_not_write_zeroes_capable, NULL))
+			return false;
+	}
+
+	return true;
+}
+
+
 static int device_discard_capable(struct dm_target *ti, struct dm_dev *dev,
 				  sector_t start, sector_t len, void *data)
 {
@@ -1603,6 +1631,8 @@ void dm_table_set_restrictions(struct dm_table *t, struct request_queue *q,
 
 	if (!dm_table_supports_write_same(t))
 		q->limits.max_write_same_sectors = 0;
+	if (!dm_table_supports_write_zeroes(t))
+		q->limits.max_write_zeroes_sectors = 0;
 
 	if (dm_table_all_devices_attribute(t, queue_supports_sg_merge))
 		queue_flag_clear_unlocked(QUEUE_FLAG_NO_SG_MERGE, q);

drivers/md/dm.c

@@ -824,6 +824,14 @@ void disable_write_same(struct mapped_device *md)
 	limits->max_write_same_sectors = 0;
 }
 
+void disable_write_zeroes(struct mapped_device *md)
+{
+	struct queue_limits *limits = dm_get_queue_limits(md);
+
+	/* device doesn't really support WRITE ZEROES, disable it */
+	limits->max_write_zeroes_sectors = 0;
+}
+
 static void clone_endio(struct bio *bio)
 {
 	int error = bio->bi_error;
@@ -850,9 +858,14 @@ static void clone_endio(struct bio *bio)
 		}
 	}
 
-	if (unlikely(r == -EREMOTEIO && (bio_op(bio) == REQ_OP_WRITE_SAME) &&
-		     !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors))
+	if (unlikely(r == -EREMOTEIO)) {
+		if (bio_op(bio) == REQ_OP_WRITE_SAME &&
+		    !bdev_get_queue(bio->bi_bdev)->limits.max_write_same_sectors)
 			disable_write_same(md);
+		if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
+		    !bdev_get_queue(bio->bi_bdev)->limits.max_write_zeroes_sectors)
+			disable_write_zeroes(md);
+	}
 
 	free_tio(tio);
 	dec_pending(io, error);
@@ -1201,6 +1214,11 @@ static unsigned get_num_write_same_bios(struct dm_target *ti)
 	return ti->num_write_same_bios;
 }
 
+static unsigned get_num_write_zeroes_bios(struct dm_target *ti)
+{
+	return ti->num_write_zeroes_bios;
+}
+
 typedef bool (*is_split_required_fn)(struct dm_target *ti);
 
 static bool is_split_required_for_discard(struct dm_target *ti)
@@ -1255,6 +1273,11 @@ static int __send_write_same(struct clone_info *ci)
 	return __send_changing_extent_only(ci, get_num_write_same_bios, NULL);
 }
 
+static int __send_write_zeroes(struct clone_info *ci)
+{
+	return __send_changing_extent_only(ci, get_num_write_zeroes_bios, NULL);
+}
+
 /*
  * Select the correct strategy for processing a non-flush bio.
  */
@@ -1269,6 +1292,8 @@ static int __split_and_process_non_flush(struct clone_info *ci)
 		return __send_discard(ci);
 	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
 		return __send_write_same(ci);
+	else if (unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES))
+		return __send_write_zeroes(ci);
 
 	ti = dm_table_find_target(ci->map, ci->sector);
 	if (!dm_target_is_valid(ti))

include/linux/device-mapper.h

@@ -254,6 +254,12 @@ struct dm_target {
 	 */
 	unsigned num_write_same_bios;
 
+	/*
+	 * The number of WRITE ZEROES bios that will be submitted to the target.
+	 * The bio number can be accessed with dm_bio_get_target_bio_nr.
+	 */
+	unsigned num_write_zeroes_bios;
+
 	/*
 	 * The minimum number of extra bytes allocated in each io for the
 	 * target to use.