[Devel] [PATCH 0/7] drivers/md/dm-qcow2: per-qio fast path

[Alexander Ivanov]

LGTM with minor notes.

Reviewed-by: Alexander Ivanov <alexander.ivanov at virtuozzo.com>

On 10/29/26 15:03, Andrey Zhadchenko wrote:
> dm-qcow2 processes every request consequentially in a single kwork.
> Unfortunately this introduces latency and cpu-bound limits. This
> patchset addresses the problem by laying per-qio tasks foundation:
> qios can be executed in parallel on the same workqueue. For now cover
> only requests with metadata fully allocated.
>
> https://virtuozzo.atlassian.net/browse/VSTOR-95494
>
> Andrey Zhadchenko (7):
>    drivers/md/dm-qcow2: repeat md page lookup if it was inserted in
>      parallel
>    drivers/md/dm-qcow2: check MD_DIRTY and md->wbd under lock in
>      perform_rw_mapped()
>    drivers/md/dm-qcow2: prepare process_one_qio() for fastpath
>    drivers/md/dm-qcow2: add per-qio work infrastructure
>    drivers/md/dm-qcow2: implement per-qio fast processing
>    drivers/md/dm-qcow2: declare DM_TARGET_NOWAIT
>    drivers/md/dm-qcow2: process fast path qios in per-cpu batches on a
>      workqueue
>
>   drivers/md/dm-qcow2-map.c    | 214 +++++++++++++++++++++++++++++------
>   drivers/md/dm-qcow2-target.c |  12 +-
>   drivers/md/dm-qcow2.h        |  10 ++
>   3 files changed, 197 insertions(+), 39 deletions(-)
>