Revert "block: nbd: add sanity check for first_minor"

stable inclusion
from stable-5.10.66
commit 0daa75bf750c400af0a0127fae37cd959d36dee7
bugzilla: 182374 https://gitee.com/openeuler/kernel/issues/I4EH73

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0daa75bf750c400af0a0127fae37cd959d36dee7

--------------------------------

This reverts commit 4b21d4e820bb9a1415ec76dfe565e4c5937337dd which is
commit b1a81163 upstream.

The backport of this is reported to be causing some problems, so revert
this for now until they are worked out.

Link: https://lore.kernel.org/r/CACPK8XfUWoOHr-0RwRoYoskia4fbAbZ7DYf5wWBnv6qUnGq18w@mail.gmail.comReported-by: NJoel Stanley <joel@jms.id.au>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Pavel Skripkin <paskripkin@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/block/nbd.c

@@ -1759,17 +1759,7 @@ static int nbd_dev_add(int index)
 	refcount_set(&nbd->refs, 1);
 	INIT_LIST_HEAD(&nbd->list);
 	disk->major = NBD_MAJOR;
-
-	/* Too big first_minor can cause duplicate creation of
-	 * sysfs files/links, since first_minor will be truncated to
-	 * byte in __device_add_disk().
-	 */
 	disk->first_minor = index << part_shift;
-	if (disk->first_minor > 0xff) {
-		err = -EINVAL;
-		goto out_free_idr;
-	}
-
 	disk->fops = &nbd_fops;
 	disk->private_data = nbd;
 	sprintf(disk->disk_name, "nbd%d", index);