dm raid: fix discard limits for raid1 and raid10

Block core warned that discard_granularity was 0 for dm-raid with
personality of raid1.  Reason is that raid_io_hints() was incorrectly
special-casing raid1 rather than raid0.

But since commit 29efc390b9462 ("md/md0: optimize raid0 discard
handling") even raid0 properly handles large discards.

Fix raid_io_hints() by removing discard limits settings for raid1.
Also, fix limits for raid10 by properly stacking underlying limits as
done in blk_stack_limits().

Depends-on: 29efc390b9462 ("md/md0: optimize raid0 discard handling")
Fixes: 61697a6abd24a ("dm: eliminate 'split_discard_bios' flag from DM target interface")
Cc: stable@vger.kernel.org
Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 56b723d..dc8568a 100644 (file)
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3730,12 +3730,14 @@ static void raid_io_hints(struct dm_target *ti, struct queue_limits *limits)
        blk_limits_io_opt(limits, chunk_size_bytes * mddev_data_stripes(rs));
 
        /*
-        * RAID1 and RAID10 personalities require bio splitting,
-        * RAID0/4/5/6 don't and process large discard bios properly.
+        * RAID10 personality requires bio splitting,
+        * RAID0/1/4/5/6 don't and process large discard bios properly.
         */
-       if (rs_is_raid1(rs) || rs_is_raid10(rs)) {
-               limits->discard_granularity = chunk_size_bytes;
-               limits->max_discard_sectors = rs->md.chunk_sectors;
+       if (rs_is_raid10(rs)) {
+               limits->discard_granularity = max(chunk_size_bytes,
+                                                 limits->discard_granularity);
+               limits->max_discard_sectors = min_not_zero(rs->md.chunk_sectors,
+                                                          limits->max_discard_sectors);
        }
 }