On 2/16/22 18:30, Chaitanya Kulkarni wrote:
> Follow the pattern what we have in bio_alloc() to set the structure
s/what/that
> members in the structure allocation function in alloc_cmd() and pass
> bio to initialize newly allocated cmd->bio member.
>
> Follow the pattern in copy_to_nullb() to use result of one function call
> (null_cache_active()) to be used as a parameter to another function call
> (null_insert_page()), use result of alloc_cmd() as a first parameter to
> the null_handle_cmd() in null_submit_bio() function. This allow us to
> remove the local variable cmd on stack in null_submit_bio() that is in
> fast path.
>
> Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
> ---
> drivers/block/null_blk/main.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index d78fc3edb22e..e19340f686a8 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -719,7 +719,7 @@ static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
> return NULL;
> }
>
> -static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq)
> +static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq, struct bio *bio)
> {
> struct nullb_cmd *cmd;
> DEFINE_WAIT(wait);
> @@ -730,8 +730,10 @@ static struct nullb_cmd *alloc_cmd(struct nullb_queue *nq)
> * __alloc_cmd() and a fast path call to prepare_to_wait().
> */
> cmd = __alloc_cmd(nq);
> - if (cmd)
> + if (cmd) {
> + cmd->bio = bio;
> return cmd;
> + }
> prepare_to_wait(&nq->wait, &wait, TASK_UNINTERRUPTIBLE);
> io_schedule();
> finish_wait(&nq->wait, &wait);
> @@ -1473,12 +1475,8 @@ static void null_submit_bio(struct bio *bio)
> sector_t nr_sectors = bio_sectors(bio);
> struct nullb *nullb = bio->bi_bdev->bd_disk->private_data;
> struct nullb_queue *nq = nullb_to_queue(nullb);
> - struct nullb_cmd *cmd;
> -
> - cmd = alloc_cmd(nq);
> - cmd->bio = bio;
>
> - null_handle_cmd(cmd, sector, nr_sectors, bio_op(bio));
> + null_handle_cmd(alloc_cmd(nq, bio), sector, nr_sectors, bio_op(bio));
> }
>
> static bool should_timeout_request(struct request *rq)
Since patch 1 rewrite this function already, you could squash this patch
into it, replacing the can_wait argument with the bio argument.
--
Damien Le Moal
Western Digital Research
