drbd: discard_zeroes_if_aligned allows "thin" resync for discard_zeroes_data=0

Even if discard_zeroes_data != 0,
if discard_zeroes_if_aligned is set, we assume we can reliably
zero-out/discard using the drbd_issue_peer_discard() helper.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index e5fdcc6c2e672e77be031c2cb41d73084a76395a..169e3e15a30efa1cf60be052ddac2dac97ea97e4 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1408,9 +1408,12 @@ static void sanitize_disk_conf(struct drbd_device *device, struct disk_conf *dis
        if (disk_conf->al_extents > drbd_al_extents_max(nbc))
                disk_conf->al_extents = drbd_al_extents_max(nbc);
 
-       if (!blk_queue_discard(q) || !q->limits.discard_zeroes_data) {
-               disk_conf->rs_discard_granularity = 0; /* disable feature */
-               drbd_info(device, "rs_discard_granularity feature disabled\n");
+       if (!blk_queue_discard(q)
+           || (!q->limits.discard_zeroes_data && !disk_conf->discard_zeroes_if_aligned)) {
+               if (disk_conf->rs_discard_granularity) {
+                       disk_conf->rs_discard_granularity = 0; /* disable feature */
+                       drbd_info(device, "rs_discard_granularity feature disabled\n");
+               }
        }
 
        if (disk_conf->rs_discard_granularity) {