nbd: correct the maximum value for discard sectors

The version of the NBD protocol implemented by the kernel driver
currently has a 32 bit field for length values. As the NBD protocol uses
bytes as a unit of length, length values larger than 2^32 bytes cannot
be expressed.

Update the max_hw_discard_sectors field to match that.

Signed-off-by: Wouter Verhelst <w@uter.be>
Fixes: 2682832 ("nbd: use the atomic queue limits API in nbd_set_size")
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: Eric Blake <eblake@redhat.Com>
Link: https://lore.kernel.org/r/20240812133032.115134-8-w@uter.be
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: yoe

drivers/block/nbd.c

@@ -350,7 +350,7 @@ static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 
 	lim = queue_limits_start_update(nbd->disk->queue);
 	if (nbd->config->flags & NBD_FLAG_SEND_TRIM)
-		lim.max_hw_discard_sectors = UINT_MAX;
+		lim.max_hw_discard_sectors = UINT_MAX >> SECTOR_SHIFT;
 	else
 		lim.max_hw_discard_sectors = 0;
 	if (!(nbd->config->flags & NBD_FLAG_SEND_FLUSH)) {