drbd: use blk_queue_max_discard_sectors helper

We currently only set q->limits.max_discard_sectors, but that is not
enough. Another field, max_hw_discard_sectors, was introduced in
commit 0034af036554 ("block: make /sys/block/<dev>/queue/discard_max_bytes
writeable").

The difference is that max_discard_sectors can be changed from user
space via sysfs, while max_hw_discard_sectors is the "hardware" upper
limit.

So use this helper, which sets both.

This is also a fixup for commit 998e9cbcd615 ("drbd: cleanup
decide_on_discard_support"): if discards are not supported, that does
not necessarily mean we also want to disable write_zeroes.

Fixes: 998e9cbcd615 ("drbd: cleanup decide_on_discard_support")
Reviewed-by: Joel Colledge <joel.colledge@linbit.com>
Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Link: https://lore.kernel.org/r/20221109133453.51652-2-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
index 864c98e..249eba7 100644 (file)
--- a/drivers/block/drbd/drbd_nl.c
+++ b/drivers/block/drbd/drbd_nl.c
@@ -1210,6 +1210,7 @@ static void decide_on_discard_support(struct drbd_device *device,
        struct drbd_connection *connection =
                first_peer_device(device)->connection;
        struct request_queue *q = device->rq_queue;
+       unsigned int max_discard_sectors;
 
        if (bdev && !bdev_max_discard_sectors(bdev->backing_bdev))
                goto not_supported;
@@ -1230,15 +1231,14 @@ static void decide_on_discard_support(struct drbd_device *device,
         * topology on all peers.
         */
        blk_queue_discard_granularity(q, 512);
-       q->limits.max_discard_sectors = drbd_max_discard_sectors(connection);
-       q->limits.max_write_zeroes_sectors =
-               drbd_max_discard_sectors(connection);
+       max_discard_sectors = drbd_max_discard_sectors(connection);
+       blk_queue_max_discard_sectors(q, max_discard_sectors);
+       blk_queue_max_write_zeroes_sectors(q, max_discard_sectors);
        return;
 
 not_supported:
        blk_queue_discard_granularity(q, 0);
-       q->limits.max_discard_sectors = 0;
-       q->limits.max_write_zeroes_sectors = 0;
+       blk_queue_max_discard_sectors(q, 0);
 }
 
 static void fixup_write_zeroes(struct drbd_device *device, struct request_queue *q)