On Fri, Jun 13, 2025 at 07:08:52PM -0400, Benjamin Marzinski wrote:
> Due to the semantics of iterate_devices(), the current code allows a
> request-based dm table as long as it includes one request-stackable
> device. It is supposed to only allow tables where there are no
> non-request-stackable devices.
>
> Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
Amazing this type of bug is still lurking, thought I audited all of
the iterate_devices callout functions.. anyway, thanks for fixing it!
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
> ---
> drivers/md/dm-table.c | 10 +++++-----
> 1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index 9f95f77687ef..d91207b2d77f 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -898,17 +898,17 @@ static bool dm_table_supports_dax(struct dm_table *t,
> return true;
> }
>
> -static int device_is_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
> - sector_t start, sector_t len, void *data)
> +static int device_is_not_rq_stackable(struct dm_target *ti, struct dm_dev *dev,
> + sector_t start, sector_t len, void *data)
> {
> struct block_device *bdev = dev->bdev;
> struct request_queue *q = bdev_get_queue(bdev);
>
> /* request-based cannot stack on partitions! */
> if (bdev_is_partition(bdev))
> - return false;
> + return true;
>
> - return queue_is_mq(q);
> + return !queue_is_mq(q);
> }
>
> static int dm_table_determine_type(struct dm_table *t)
> @@ -1004,7 +1004,7 @@ static int dm_table_determine_type(struct dm_table *t)
>
> /* Non-request-stackable devices can't be used for request-based dm */
> if (!ti->type->iterate_devices ||
> - !ti->type->iterate_devices(ti, device_is_rq_stackable, NULL)) {
> + ti->type->iterate_devices(ti, device_is_not_rq_stackable, NULL)) {
> DMERR("table load rejected: including non-request-stackable devices");
> return -EINVAL;
> }
> --
> 2.48.1
>
>
