xen/blkback: Convert to bdev_open_by_dev()

mainline inclusion
from mainline-v6.7-rc1
commit 436d3705bfee5dc748cdf4ffdb40ac17183307c2
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I8KPBR
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h=v6.7-rc3&id=436d3705bfee5dc748cdf4ffdb40ac17183307c2



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

Convert xen/blkback to use bdev_open_by_dev() and pass the
handle around.

CC: xen-devel@lists.xenproject.org
Acked-by: Christoph Hellwig <hch@lst.de>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-7-jack@suse.cz


Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com>