Re: [PATCH 12/78] dm: use set_capacity_and_notify

[Mike Snitzer <snitzer@xxxxxxxxxx>]

On Mon, Nov 16, 2020 at 10:05 AM Christoph Hellwig <hch@xxxxxx> wrote:
>
> Use set_capacity_and_notify to set the size of both the disk and block
> device.  This also gets the uevent notifications for the resize for free.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
> ---
>  drivers/md/dm.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index c18fc25485186d..62ad44925e73ec 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1971,8 +1971,7 @@ static struct dm_table *__bind(struct mapped_device 
> *md, struct dm_table *t,
>         if (size != dm_get_size(md))
>                 memset(&md->geometry, 0, sizeof(md->geometry));
>
> -       set_capacity(md->disk, size);
> -       bd_set_nr_sectors(md->bdev, size);
> +       set_capacity_and_notify(md->disk, size);
>
>         dm_table_event_callback(t, event_callback, md);
>

Not yet pinned down _why_ DM is calling set_capacity_and_notify() with
a size of 0 but, when running various DM regression tests, I'm seeing
a lot of noise like:

[  689.240037] dm-2: detected capacity change from 2097152 to 0

Is this pr_info really useful?  Should it be moved to below: if
(!capacity || !size) so that it only prints if a uevent is sent?

Mike