dm: allow targets to require splitting WRITE_ZEROES and SECURE_ERASE

Introduce max_write_zeroes_granularity and
max_secure_erase_granularity flags in the dm_target struct.

If a target sets these then DM core will split IO of these operation
types accordingly (in terms of max_write_zeroes_sectors and
max_secure_erase_sectors respectively).

Signed-off-by: Mike Snitzer <snitzer@kernel.org>

Author: Mike Snitzer

drivers/md/dm.c

@@ -1614,21 +1614,23 @@ static blk_status_t __process_abnormal_io(struct clone_info *ci,
 {
 	unsigned int num_bios = 0;
 	unsigned int max_granularity = 0;
+	struct queue_limits *limits = dm_get_queue_limits(ti->table->md);
 
 	switch (bio_op(ci->bio)) {
 	case REQ_OP_DISCARD:
 		num_bios = ti->num_discard_bios;
-		if (ti->max_discard_granularity) {
-			struct queue_limits *limits =
-				dm_get_queue_limits(ti->table->md);
+		if (ti->max_discard_granularity)
 			max_granularity = limits->max_discard_sectors;
-		}
 		break;
 	case REQ_OP_SECURE_ERASE:
 		num_bios = ti->num_secure_erase_bios;
+		if (ti->max_secure_erase_granularity)
+			max_granularity = limits->max_secure_erase_sectors;
 		break;
 	case REQ_OP_WRITE_ZEROES:
 		num_bios = ti->num_write_zeroes_bios;
+		if (ti->max_write_zeroes_granularity)
+			max_granularity = limits->max_write_zeroes_sectors;
 		break;
 	default:
 		break;

include/linux/device-mapper.h

@@ -359,11 +359,23 @@ struct dm_target {
 	bool discards_supported:1;
 
 	/*
-	 * Set if this target requires that discards be split on both
-	 * 'discard_granularity' and 'max_discard_sectors' boundaries.
+	 * Set if this target requires that discards be split on
+	 * 'max_discard_sectors' boundaries.
 	 */
 	bool max_discard_granularity:1;
 
+	/*
+	 * Set if this target requires that secure_erases be split on
+	 * 'max_secure_erase_sectors' boundaries.
+	 */
+	bool max_secure_erase_granularity:1;
+
+	/*
+	 * Set if this target requires that write_zeroes be split on
+	 * 'max_write_zeroes_sectors' boundaries.
+	 */
+	bool max_write_zeroes_granularity:1;
+
 	/*
 	 * Set if we need to limit the number of in-flight bios when swapping.
 	 */