On Wed, Jul 2, 2025 at 12:04 AM Ming Lei <ming.lei@xxxxxxxxxx> wrote:
>
> Remove ublk_commit_and_fetch() and open code request completion.
>
> Now request reference is stored in 'ublk_io', which becomes one global
> variable, the motivation is to centralize access 'struct ublk_io' reference,
> then we can introduce lock to protect `ublk_io` in future for supporting
> io batch.
I didn't follow this. What do you mean by "global variable"?
>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
> ---
> drivers/block/ublk_drv.c | 36 ++++++++++++++++++------------------
> 1 file changed, 18 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 7fd2fa493d6a..13c6b1e0e1ef 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -711,13 +711,12 @@ static inline void ublk_put_req_ref(struct ublk_io *io, struct request *req)
> __ublk_complete_rq(req);
> }
>
> -static inline void ublk_sub_req_ref(struct ublk_io *io, struct request *req)
> +static inline bool ublk_sub_req_ref(struct ublk_io *io, struct request *req)
> {
> unsigned sub_refs = UBLK_REFCOUNT_INIT - io->task_registered_buffers;
>
> io->task_registered_buffers = 0;
> - if (refcount_sub_and_test(sub_refs, &io->ref))
> - __ublk_complete_rq(req);
> + return refcount_sub_and_test(sub_refs, &io->ref);
The struct request *req parameter can be removed now. Looks like it
can be removed from ublk_need_complete_req() too.
> }
>
> static inline bool ublk_need_get_data(const struct ublk_queue *ubq)
> @@ -2224,21 +2223,13 @@ static int ublk_check_commit_and_fetch(const struct ublk_queue *ubq,
> return 0;
> }
>
> -static void ublk_commit_and_fetch(const struct ublk_queue *ubq,
> - struct ublk_io *io, struct io_uring_cmd *cmd,
> - struct request *req, unsigned int issue_flags,
> - __u64 zone_append_lba, u16 buf_idx)
> +static bool ublk_need_complete_req(const struct ublk_queue *ubq,
> + struct ublk_io *io,
> + struct request *req)
> {
> - if (buf_idx != UBLK_INVALID_BUF_IDX)
> - io_buffer_unregister_bvec(cmd, buf_idx, issue_flags);
> -
> - if (req_op(req) == REQ_OP_ZONE_APPEND)
> - req->__sector = zone_append_lba;
> -
> if (ublk_need_req_ref(ubq))
> - ublk_sub_req_ref(io, req);
> - else
> - __ublk_complete_rq(req);
> + return ublk_sub_req_ref(io, req);
> + return true;
> }
>
> static bool ublk_get_data(const struct ublk_queue *ubq, struct ublk_io *io,
> @@ -2271,6 +2262,7 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
> unsigned tag = ub_cmd->tag;
> struct request *req;
> int ret;
> + bool compl;
>
> pr_devel("%s: received: cmd op %d queue %d tag %d result %d\n",
> __func__, cmd->cmd_op, ub_cmd->q_id, tag,
> @@ -2347,8 +2339,16 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
> goto out;
> req = ublk_fill_io_cmd(io, cmd, ub_cmd->result);
> ret = ublk_config_io_buf(ubq, io, cmd, ub_cmd->addr, &buf_idx);
> - ublk_commit_and_fetch(ubq, io, cmd, req, issue_flags,
> - ub_cmd->zone_append_lba, buf_idx);
> + compl = ublk_need_complete_req(ubq, io, req);
> +
> + /* can't touch 'ublk_io' any more */
> + if (buf_idx != UBLK_INVALID_BUF_IDX)
> + io_buffer_unregister_bvec(cmd, buf_idx, issue_flags);
> + if (req_op(req) == REQ_OP_ZONE_APPEND)
> + req->__sector = ub_cmd->zone_append_lba;
> + if (compl)
> + __ublk_complete_rq(req);
What is the benefit of separating the reference count decrement from
the call to __ublk_complete_rq()? I can understand if you want to keep
the code manipulating ublk_io separate from the code dispatching the
completed request. But it seems like this could be written more simply
as
if (ublk_need_complete_req(ubq, io, req))
__ublk_complete_rq(req);
Best,
Caleb
> +
> if (ret)
> goto out;
> break;
> --
> 2.47.0
>
