From: Alasdair G Kergon 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 23508a96cd2e857d57044a2ed7d305f2d9daf441 ("dm: add WRITE SAME support"). Signed-off-by: Alasdair G Kergon Acked-by: Mike Snitzer --- drivers/md/dm.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) Index: linux/drivers/md/dm.c =================================================================== --- linux.orig/drivers/md/dm.c +++ linux/drivers/md/dm.c @@ -1188,6 +1188,7 @@ static int __clone_and_map_changing_exte { struct dm_target *ti; sector_t len; + unsigned num_requests; do { ti = dm_table_find_target(ci->map, ci->sector); @@ -1200,7 +1201,8 @@ static int __clone_and_map_changing_exte * 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)) @@ -1208,7 +1210,7 @@ static int __clone_and_map_changing_exte 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);