block: return ELEVATOR_DISCARD_MERGE if possible
commit 866663b7b52d2da267b28e12eed89ee781b8fed1 upstream.
When merging one bio to request, if they are discard IO and the queue
supports multi-range discard, we need to return ELEVATOR_DISCARD_MERGE
because both block core and related drivers(nvme, virtio-blk) doesn't
handle mixed discard io merge(traditional IO merge together with
discard merge) well.
Fix the issue by returning ELEVATOR_DISCARD_MERGE in this situation,
so both blk-mq and drivers just need to handle multi-range discard.
Reported-by: Oleksandr Natalenko <email@example.com>
Signed-off-by: Ming Lei <firstname.lastname@example.org>
Tested-by: Oleksandr Natalenko <email@example.com>
Fixes: 2705dfb20947 ("block: fix discard request merge")
Signed-off-by: Jens Axboe <firstname.lastname@example.org>
Signed-off-by: Gwendal Grignou <email@example.com>
Signed-off-by: Greg Kroah-Hartman <firstname.lastname@example.org>
5 files changed