[dm-devel] [PATCH v4 04/11] dm: Fix dm_accept_partial_bio()

[Himanshu Madhani]

On 5/24/21 9:25 PM, Damien Le Moal wrote:
> Fix dm_accept_partial_bio() to actually check that zone management
> commands are not passed as explained in the function documentation
> comment. Also, since a zone append operation cannot be split, add
> REQ_OP_ZONE_APPEND as a forbidden command.
> 
> White lines are added around the group of BUG_ON() calls to make the
> code more legible.
> 
> Signed-off-by: Damien Le Moal <damien.lemoal at wdc.com>
> Reviewed-by: Johannes Thumshirn <johannes.thumshirn at wdc.com>
> Reviewed-by: Hannes Reinecke <hare at suse.de>
> ---
>   drivers/md/dm.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/md/dm.c b/drivers/md/dm.c
> index ca2aedd8ee7d..a9211575bfed 100644
> --- a/drivers/md/dm.c
> +++ b/drivers/md/dm.c
> @@ -1237,8 +1237,9 @@ static int dm_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
>   
>   /*
>    * A target may call dm_accept_partial_bio only from the map routine.  It is
> - * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_RESET,
> - * REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and REQ_OP_ZONE_FINISH.
> + * allowed for all bio types except REQ_PREFLUSH, zone management operations
> + * (REQ_OP_ZONE_RESET, REQ_OP_ZONE_OPEN, REQ_OP_ZONE_CLOSE and
> + * REQ_OP_ZONE_FINISH) and zone append writes.
>    *
>    * dm_accept_partial_bio informs the dm that the target only wants to process
>    * additional n_sectors sectors of the bio and the rest of the data should be
> @@ -1268,9 +1269,13 @@ void dm_accept_partial_bio(struct bio *bio, unsigned n_sectors)
>   {
>   	struct dm_target_io *tio = container_of(bio, struct dm_target_io, clone);
>   	unsigned bi_size = bio->bi_iter.bi_size >> SECTOR_SHIFT;
> +
>   	BUG_ON(bio->bi_opf & REQ_PREFLUSH);
> +	BUG_ON(op_is_zone_mgmt(bio_op(bio)));
> +	BUG_ON(bio_op(bio) == REQ_OP_ZONE_APPEND);
>   	BUG_ON(bi_size > *tio->len_ptr);
>   	BUG_ON(n_sectors > bi_size);
> +
>   	*tio->len_ptr -= bi_size - n_sectors;
>   	bio->bi_iter.bi_size = n_sectors << SECTOR_SHIFT;
>   }
> 

Reviewed-by: Himanshu Madhani <himanshu.madhani at oracle.com>

-- 
Himanshu Madhani                                Oracle Linux Engineering