drbd: cleanup decide_on_discard_support

Sanitize the calling conventions and use a goto label to cleanup the
code flow.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Link: https://lore.kernel.org/r/20220415045258.199825-8-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/drbd/drbd_nl.c

@@ -1204,38 +1204,42 @@ static unsigned int drbd_max_discard_sectors(struct drbd_connection *connection)
 }
 
 static void decide_on_discard_support(struct drbd_device *device,
-			struct request_queue *q,
-			struct request_queue *b,
-			bool discard_zeroes_if_aligned)
+		struct drbd_backing_dev *bdev)
 {
-	/* q = drbd device queue (device->rq_queue)
-	 * b = backing device queue (device->ldev->backing_bdev->bd_disk->queue),
-	 *     or NULL if diskless
-	 */
-	struct drbd_connection *connection = first_peer_device(device)->connection;
-	bool can_do = b ? blk_queue_discard(b) : true;
-
-	if (can_do && connection->cstate >= C_CONNECTED && !(connection->agreed_features & DRBD_FF_TRIM)) {
-		can_do = false;
-		drbd_info(connection, "peer DRBD too old, does not support TRIM: disabling discards\n");
-	}
-	if (can_do) {
-		/* We don't care for the granularity, really.
-		 * Stacking limits below should fix it for the local
-		 * device.  Whether or not it is a suitable granularity
-		 * on the remote device is not our problem, really. If
-		 * you care, you need to use devices with similar
-		 * topology on all peers. */
-		blk_queue_discard_granularity(q, 512);
-		q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
-		blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
-		q->limits.max_write_zeroes_sectors = drbd_max_discard_sectors(connection);
-	} else {
-		blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
-		blk_queue_discard_granularity(q, 0);
-		q->limits.max_discard_sectors = 0;
-		q->limits.max_write_zeroes_sectors = 0;
+	struct drbd_connection *connection =
+		first_peer_device(device)->connection;
+	struct request_queue *q = device->rq_queue;
+
+	if (bdev && !blk_queue_discard(bdev->backing_bdev->bd_disk->queue))
+		goto not_supported;
+
+	if (connection->cstate >= C_CONNECTED &&
+	    !(connection->agreed_features & DRBD_FF_TRIM)) {
+		drbd_info(connection,
+			"peer DRBD too old, does not support TRIM: disabling discards\n");
+		goto not_supported;
 	}
+
+	/*
+	 * We don't care for the granularity, really.
+	 *
+	 * Stacking limits below should fix it for the local device.  Whether or
+	 * not it is a suitable granularity on the remote device is not our
+	 * problem, really. If you care, you need to use devices with similar
+	 * topology on all peers.
+	 */
+	blk_queue_discard_granularity(q, 512);
+	q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
+	blk_queue_flag_set(QUEUE_FLAG_DISCARD, q);
+	q->limits.max_write_zeroes_sectors =
+		drbd_max_discard_sectors(connection);
+	return;
+
+not_supported:
+	blk_queue_flag_clear(QUEUE_FLAG_DISCARD, q);
+	blk_queue_discard_granularity(q, 0);
+	q->limits.max_discard_sectors = 0;
+	q->limits.max_write_zeroes_sectors = 0;
 }
 
 static void fixup_discard_if_not_supported(struct request_queue *q)
@@ -1273,7 +1277,6 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 	unsigned int max_segments = 0;
 	struct request_queue *b = NULL;
 	struct disk_conf *dc;
-	bool discard_zeroes_if_aligned = true;
 
 	if (bdev) {
 		b = bdev->backing_bdev->bd_disk->queue;
@@ -1282,7 +1285,6 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 		rcu_read_lock();
 		dc = rcu_dereference(device->ldev->disk_conf);
 		max_segments = dc->max_bio_bvecs;
-		discard_zeroes_if_aligned = dc->discard_zeroes_if_aligned;
 		rcu_read_unlock();
 
 		blk_set_stacking_limits(&q->limits);
@@ -1292,7 +1294,7 @@ static void drbd_setup_queue_param(struct drbd_device *device, struct drbd_backi
 	/* This is the workaround for "bio would need to, but cannot, be split" */
 	blk_queue_max_segments(q, max_segments ? max_segments : BLK_MAX_SEGMENTS);
 	blk_queue_segment_boundary(q, PAGE_SIZE-1);
-	decide_on_discard_support(device, q, b, discard_zeroes_if_aligned);
+	decide_on_discard_support(device, bdev);
 
 	if (b) {
 		blk_stack_limits(&q->limits, &b->limits, 0);