rbd: decouple header read-in from updating rbd_dev->header

stable inclusion
from stable-v5.10.198
commit 3ceb306f9b2d2e7a8c8d36f6815417cb056072cd
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I987V5

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=3ceb306f9b2d2e7a8c8d36f6815417cb056072cd



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

commit 510a7330 upstream.

Make rbd_dev_header_info() populate a passed struct rbd_image_header
instead of rbd_dev->header and introduce rbd_dev_update_header() for
updating mutable fields in rbd_dev->header upon refresh.  The initial
read-in of both mutable and immutable fields in rbd_dev_image_probe()
passes in rbd_dev->header so no update step is required there.

rbd_init_layout() is now called directly from rbd_dev_image_probe()
instead of individually in format 1 and format 2 implementations.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>