dm: introduce split_discard_requests
This patch introduces a new variable split_discard_requests. It can be
set by targets so that discard requests are split on max_io_len
boundaries.
When split_discard_requests is not set, discard requests are only split on
boundaries between targets, as was the case before this patch.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 415c280..4e09b6f 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1215,7 +1215,10 @@
if (!ti->num_discard_requests)
return -EOPNOTSUPP;
- len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
+ if (!ti->split_discard_requests)
+ 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);