drbd: Enable QUEUE_FLAG_DISCARD only if the peer can recieve P_TRIM
Allow the user of REQ_DISCARD.
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 bb36792..2364b78 100644
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1133,6 +1133,26 @@
if (get_ldev_if_state(device, D_ATTACHING)) {
struct request_queue * const b = device->ldev->backing_bdev->bd_disk->queue;
+ struct drbd_connection *connection = first_peer_device(device)->connection;
+
+ if (blk_queue_discard(b) &&
+ (connection->cstate < C_CONNECTED || connection->agreed_features & FF_TRIM)) {
+ /* inherit from backing queue */
+ q->limits.discard_zeroes_data = 1;
+ /* For now, don't allow more than one activity log extent worth of data
+ * to be discarded in one go. We may need to rework drbd_al_begin_io()
+ * to allow for even larger discard ranges */
+ q->limits.max_discard_sectors = DRBD_MAX_DISCARD_SECTORS;
+
+ queue_flag_set_unlocked(QUEUE_FLAG_DISCARD, q);
+ /* REALLY? Is stacking secdiscard "legal"? */
+ if (blk_queue_secdiscard(b))
+ queue_flag_set_unlocked(QUEUE_FLAG_SECDISCARD, q);
+ } else {
+ q->limits.max_discard_sectors = 0;
+ queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, q);
+ queue_flag_clear_unlocked(QUEUE_FLAG_SECDISCARD, q);
+ }
blk_queue_stack_limits(q, b);
