rnbd-clt: kill read_only from struct rnbd_clt_dev

The member is not needed since we can call get_disk_ro to achieve the
same goal.

Acked-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Guoqing Jiang <guoqing.jiang@linux.dev>
Link: https://lore.kernel.org/r/20220706133152.12058-4-guoqing.jiang@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/rnbd/rnbd-clt.c

@@ -949,7 +949,7 @@ static int rnbd_client_open(struct block_device *block_device, fmode_t mode)
 {
 	struct rnbd_clt_dev *dev = block_device->bd_disk->private_data;
 
-	if (dev->read_only && (mode & FMODE_WRITE))
+	if (get_disk_ro(dev->gd) && (mode & FMODE_WRITE))
 		return -EPERM;
 
 	if (dev->dev_state == DEV_STATE_UNMAPPED ||
@@ -1402,12 +1402,8 @@ static int rnbd_clt_setup_gen_disk(struct rnbd_clt_dev *dev, int idx)
 
 	set_capacity(dev->gd, dev->nsectors);
 
-	if (dev->access_mode == RNBD_ACCESS_RO) {
-		dev->read_only = true;
+	if (dev->access_mode == RNBD_ACCESS_RO)
 		set_disk_ro(dev->gd, true);
-	} else {
-		dev->read_only = false;
-	}
 
 	/*
 	 * Network device does not need rotational

drivers/block/rnbd/rnbd-clt.h

@@ -117,7 +117,6 @@ struct rnbd_clt_dev {
 	char			*pathname;
 	enum rnbd_access_mode	access_mode;
 	u32			nr_poll_queues;
-	bool			read_only;
 	bool			wc;
 	bool			fua;
 	u32			max_hw_sectors;