On 4/8/23 08:58, Bart Van Assche wrote:
> Prevent that zoned writes with the FUA flag set are reordered against each
> other or against other zoned writes. Separate the I/O scheduler members
> from the flush members in struct request since with this patch applied a
> request may pass through both an I/O scheduler and the flush machinery.
>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
> Cc: Ming Lei <ming.lei@xxxxxxxxxx>
> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
> Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
> ---
> block/blk-flush.c | 3 ++-
> block/blk-mq.c | 11 ++++-------
> block/mq-deadline.c | 2 +-
> include/linux/blk-mq.h | 27 +++++++++++----------------
> 4 files changed, 18 insertions(+), 25 deletions(-)
>
> diff --git a/block/blk-flush.c b/block/blk-flush.c
> index 53202eff545e..e0cf153388d8 100644
> --- a/block/blk-flush.c
> +++ b/block/blk-flush.c
> @@ -432,7 +432,8 @@ void blk_insert_flush(struct request *rq)
> */
> if ((policy & REQ_FSEQ_DATA) &&
> !(policy & (REQ_FSEQ_PREFLUSH | REQ_FSEQ_POSTFLUSH))) {
> - blk_mq_request_bypass_insert(rq, false, true);
> + blk_mq_sched_insert_request(rq, /*at_head=*/false,
> + /*run_queue=*/true, /*async=*/true);
> return;
> }
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index fefc9a728e0e..250556546bbf 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -390,8 +390,7 @@ static struct request *blk_mq_rq_ctx_init(struct blk_mq_alloc_data *data,
> INIT_HLIST_NODE(&rq->hash);
> RB_CLEAR_NODE(&rq->rb_node);
>
> - if (!op_is_flush(data->cmd_flags) &&
> - e->type->ops.prepare_request) {
> + if (e->type->ops.prepare_request) {
> e->type->ops.prepare_request(rq);
> rq->rq_flags |= RQF_ELVPRIV;
> }
> @@ -452,13 +451,11 @@ static struct request *__blk_mq_alloc_requests(struct blk_mq_alloc_data *data)
> data->rq_flags |= RQF_ELV;
>
> /*
> - * Flush/passthrough requests are special and go directly to the
> - * dispatch list. Don't include reserved tags in the
> - * limiting, as it isn't useful.
> + * Do not limit the depth for passthrough requests nor for
> + * requests with a reserved tag.
> */
> - if (!op_is_flush(data->cmd_flags) &&
> + if (e->type->ops.limit_depth &&
> !blk_op_is_passthrough(data->cmd_flags) &&
> - e->type->ops.limit_depth &&
> !(data->flags & BLK_MQ_REQ_RESERVED))
> e->type->ops.limit_depth(data->cmd_flags, data);
> }
> diff --git a/block/mq-deadline.c b/block/mq-deadline.c
> index f10c2a0d18d4..d885ccf49170 100644
> --- a/block/mq-deadline.c
> +++ b/block/mq-deadline.c
> @@ -789,7 +789,7 @@ static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
>
> prio = ioprio_class_to_prio[ioprio_class];
> per_prio = &dd->per_prio[prio];
> - if (!rq->elv.priv[0]) {
> + if (!rq->elv.priv[0] && !(rq->rq_flags & RQF_FLUSH_SEQ)) {
> per_prio->stats.inserted++;
> rq->elv.priv[0] = (void *)(uintptr_t)1;
> }
Given that this change has nothing specific to zoned devices, you could rewrite
the commit message to mention that. And are bfq and kyber OK with this change as
well ?
Also, to be consistent with this change, shouldn't blk_mq_sched_bypass_insert()
be updated as well ? That function is called from blk_mq_sched_insert_request().
> diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
> index 06caacd77ed6..5e6c79ad83d2 100644
> --- a/include/linux/blk-mq.h
> +++ b/include/linux/blk-mq.h
> @@ -169,25 +169,20 @@ struct request {
> void *completion_data;
> };
>
> -
> /*
> * Three pointers are available for the IO schedulers, if they need
> - * more they have to dynamically allocate it. Flush requests are
> - * never put on the IO scheduler. So let the flush fields share
> - * space with the elevator data.
> + * more they have to dynamically allocate it.
> */
> - union {
> - struct {
> - struct io_cq *icq;
> - void *priv[2];
> - } elv;
> -
> - struct {
> - unsigned int seq;
> - struct list_head list;
> - rq_end_io_fn *saved_end_io;
> - } flush;
> - };
> + struct {
> + struct io_cq *icq;
> + void *priv[2];
> + } elv;
> +
> + struct {
> + unsigned int seq;
> + struct list_head list;
> + rq_end_io_fn *saved_end_io;
> + } flush;
>
> union {
> struct __call_single_data csd;
