block: update the stable_writes flag in bdev_add

Propagate the per-queue stable_write flags into each bdev inode in bdev_add.
This makes sure devices that require stable writes have it set for I/O
on the block device node as well.

Note that this doesn't cover the case of a flag changing on a live device
yet.  We should handle that as well, but I plan to cover it as part of a
more general rework of how changing runtime paramters on block devices
works.

Fixes: 1cb039f3 ("bdi: replace BDI_CAP_STABLE_WRITES with a queue and a sb flag")
Reported-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20231025141020.192413-3-hch@lst.de


Tested-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>