On 1/15/25 1:29 PM, Shin'ichiro Kawasaki wrote:
> As preparation to support partial data transfer, add a new argument to
> null_handle_rq() to pass the number of sectors to transfer. This commit
> does not change the behavior.
>
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@xxxxxxx>
Looks good. As a nit, I would suggest renaming null_handle_rq() to the less
generic name null_handle_rw(), or may be, null_handle_data_transfer().
Regardless,
Reviewed-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
> ---
> drivers/block/null_blk/main.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/block/null_blk/main.c b/drivers/block/null_blk/main.c
> index 87037cb375c9..71c86775354e 100644
> --- a/drivers/block/null_blk/main.c
> +++ b/drivers/block/null_blk/main.c
> @@ -1263,25 +1263,36 @@ static int null_transfer(struct nullb *nullb, struct page *page,
> return err;
> }
>
> -static blk_status_t null_handle_rq(struct nullb_cmd *cmd)
> +/*
> + * Transfer data for the given request. The transfer size is capped with the
> + * nr_sectors argument.
> + */
> +static blk_status_t null_handle_rq(struct nullb_cmd *cmd, sector_t nr_sectors)
> {
> struct request *rq = blk_mq_rq_from_pdu(cmd);
> struct nullb *nullb = cmd->nq->dev->nullb;
> int err = 0;
> unsigned int len;
> sector_t sector = blk_rq_pos(rq);
> + unsigned int max_bytes = nr_sectors << SECTOR_SHIFT;
> + unsigned int transferred_bytes = 0;
> struct req_iterator iter;
> struct bio_vec bvec;
>
> spin_lock_irq(&nullb->lock);
> rq_for_each_segment(bvec, rq, iter) {
> len = bvec.bv_len;
> + if (transferred_bytes + len > max_bytes)
> + len = max_bytes - transferred_bytes;
> err = null_transfer(nullb, bvec.bv_page, len, bvec.bv_offset,
> op_is_write(req_op(rq)), sector,
> rq->cmd_flags & REQ_FUA);
> if (err)
> break;
> sector += len >> SECTOR_SHIFT;
> + transferred_bytes += len;
> + if (transferred_bytes >= max_bytes)
> + break;
> }
> spin_unlock_irq(&nullb->lock);
>
> @@ -1333,7 +1344,7 @@ blk_status_t null_handle_memory_backed(struct nullb_cmd *cmd, enum req_op op,
> if (op == REQ_OP_DISCARD)
> return null_handle_discard(dev, sector, nr_sectors);
>
> - return null_handle_rq(cmd);
> + return null_handle_rq(cmd, nr_sectors);
> }
>
> static void nullb_zero_read_cmd_buffer(struct nullb_cmd *cmd)
--
Damien Le Moal
Western Digital Research
