dm: fix write same requests counting

kergon · kergon · commit fe7af2d3babe · 2013-01-31T14:23:36.000Z
When processing write same requests, fix dm to send the configured number of WRITE SAME requests to the target rather than the number of discards, which is not always the same. Device-mapper WRITE SAME support was introduced by commit 23508a9 ("dm: add WRITE SAME support"). Signed-off-by: Alasdair G Kergon <agk@redhat.com> Acked-by: Mike Snitzer <snitzer@redhat.com>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
@@ -1188,6 +1188,7 @@ static int __clone_and_map_changing_extent_only(struct clone_info *ci,
 {
 	struct dm_target *ti;
 	sector_t len;
+	unsigned num_requests;
 
 	do {
 		ti = dm_table_find_target(ci->map, ci->sector);
@@ -1200,15 +1201,16 @@ static int __clone_and_map_changing_extent_only(struct clone_info *ci,
 		 * reconfiguration might also have changed that since the
 		 * check was performed.
 		 */
-		if (!get_num_requests || !get_num_requests(ti))
+		num_requests = get_num_requests ? get_num_requests(ti) : 0;
+		if (!num_requests)
 			return -EOPNOTSUPP;
 
 		if (is_split_required && !is_split_required(ti))
 			len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
 		else
 			len = min(ci->sector_count, max_io_len(ci->sector, ti));
 
-		__issue_target_requests(ci, ti, ti->num_discard_requests, len);
+		__issue_target_requests(ci, ti, num_requests, len);
 
 		ci->sector += len;
 	} while (ci->sector_count -= len);
