[dm-devel] dm-zoned: Fix overflow in exposed capacity

[Mike Snitzer]

On Fri, Jun 09 2017 at 12:06am -0400,
Damien Le Moal <damien.lemoal at wdc.com> wrote:

> Cast unsigned int to sector_t before shifting. Otherwise, the target
> length overflows and becomes incorrect.
> 
> Also fix an incorrect setting of the target suspend
> operation.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal at wdc.com>
> ---
>  drivers/md/dm-zoned-target.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm-zoned-target.c b/drivers/md/dm-zoned-target.c
> index 4438f30..f947166 100644
> --- a/drivers/md/dm-zoned-target.c
> +++ b/drivers/md/dm-zoned-target.c
> @@ -773,7 +773,7 @@ static int dmz_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>  	ti->split_discard_bios = true;
>  
>  	/* The exposed capacity is the number of chunks that can be mapped */
> -	ti->len = dmz_nr_chunks(dmz->metadata) << dev->zone_nr_sectors_shift;
> +	ti->len = (sector_t)dmz_nr_chunks(dmz->metadata) << dev->zone_nr_sectors_shift;
>  
>  	/* Zone BIO */
>  	dmz->bio_set = bioset_create_nobvec(DMZ_MIN_BIOS, 0);

I folded this in, thanks.

> @@ -944,7 +944,8 @@ static struct target_type dmz_type = {
>  	.end_io		 = dmz_end_io,
>  	.io_hints	 = dmz_io_hints,
>  	.prepare_ioctl	 = dmz_prepare_ioctl,
> -	.suspend	 = dmz_suspend,
> +	.presuspend	 = dmz_suspend,
> +	.presuspend_undo = dmz_resume,
>  	.resume		 = dmz_resume,
>  	.iterate_devices = dmz_iterate_devices,
>  };

I've switched from .presuspend to .postsuspend, and eliminated the
.presuspend_undo

I'm not seeing any reason for .presuspend_undo

See dm-cache-target.c for a .postsuspend that is pretty comparable to
what dm-zoned's is doing.

As for .presuspend_undo, dm-thinp has a need for it but most target do
not.  And I'm not seeing why dm-zoned needs it.

I've pushed to linux-dm.git's 'for-next' to get more test coverage;
doesn't mean that I consider dm-zoned's review complete.

Thanks,
Mike