Re: [PATCH 2/3] block: update the stable_writes flag in bdev_add

[Ilya Dryomov <idryomov@gmail.com>]

On Tue, Oct 24, 2023 at 8:44 AM Christoph Hellwig <hch@lst.de> wrote:
>
> 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: 1cb039f3dc16 ("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>
> ---
>  block/bdev.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/block/bdev.c b/block/bdev.c
> index f3b13aa1b7d428..04dba25b0019eb 100644
> --- a/block/bdev.c
> +++ b/block/bdev.c
> @@ -425,6 +425,8 @@ void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors)
>
>  void bdev_add(struct block_device *bdev, dev_t dev)
>  {
> +       if (bdev_stable_writes(bdev))
> +               mapping_set_stable_writes(bdev->bd_inode->i_mapping);
>         bdev->bd_dev = dev;
>         bdev->bd_inode->i_rdev = dev;
>         bdev->bd_inode->i_ino = dev;
> --
> 2.39.2
>

Tested with RBD which behaves like a DIF/DIX device (i.e. requires
stable pages):

Tested-by: Ilya Dryomov <idryomov@gmail.com>

Thanks,

                Ilya