nbd: Remove a local variable from nbd_send_cmd()

blk_rq_bytes() returns an unsigned int while 'size' has type unsigned long.
This is confusing. Improve code readability by removing the local variable
'size'.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Yu Kuai <yukuai3@huawei.com>
Cc: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240510202313.25209-5-bvanassche@acm.orgSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/nbd.c

@@ -597,7 +597,6 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 	struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
 	struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
 	struct iov_iter from;
-	unsigned long size = blk_rq_bytes(req);
 	struct bio *bio;
 	u64 handle;
 	u32 type;
@@ -646,7 +645,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
 	request.type = htonl(type | nbd_cmd_flags);
 	if (type != NBD_CMD_FLUSH) {
 		request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
-		request.len = htonl(size);
+		request.len = htonl(blk_rq_bytes(req));
 	}
 	handle = nbd_cmd_handle(cmd);
 	request.cookie = cpu_to_be64(handle);