On 2022/7/28 18:41, Ming Lei wrote: > On Thu, Jul 28, 2022 at 05:31:24PM +0800, ZiyangZhang wrote: >> UBLK_IO_NEED_GET_DATA is one ublk IO command. It is designed for a user >> application who wants to allocate IO buffer and set IO buffer address >> only after it receives an IO request from ublksrv. This is a reasonable >> scenario because these users may use a RPC framework as one IO backend >> to handle IO requests passed from ublksrv. And a RPC framework may >> allocate its own buffer(or memory pool). >> >> This new feature (UBLK_F_NEED_GET_DATA) is optional for ublk users. >> Related userspace code has been added in ublksrv[1] as one pull request. >> >> Test cases for this feature are added in ublksrv and all the tests pass. >> The performance result shows that this new feature does bring additional >> latency because one IO is issued back to ublk_drv once again to copy data >> from bio vectors to user-provided data buffer. UBLK_IO_NEED_GET_DATA is >> suitable for bigger block size such as 512B or 1MB. >> >> [1] https://github.com/ming1/ubdsrv >> >> Signed-off-by: ZiyangZhang <ZiyangZhang@xxxxxxxxxxxxxxxxx> >> --- >> drivers/block/ublk_drv.c | 96 ++++++++++++++++++++++++++++++++++++---- >> 1 file changed, 87 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >> index 255b2de46a24..ea60853d80a1 100644 >> --- a/drivers/block/ublk_drv.c >> +++ b/drivers/block/ublk_drv.c >> @@ -47,7 +47,9 @@ >> #define UBLK_MINORS (1U << MINORBITS) >> >> /* All UBLK_F_* have to be included into UBLK_F_ALL */ >> -#define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY | UBLK_F_URING_CMD_COMP_IN_TASK) >> +#define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY \ >> + | UBLK_F_URING_CMD_COMP_IN_TASK \ >> + | UBLK_F_NEED_GET_DATA) >> >> struct ublk_rq_data { >> struct callback_head work; >> @@ -86,6 +88,15 @@ struct ublk_uring_cmd_pdu { >> */ >> #define UBLK_IO_FLAG_ABORTED 0x04 >> >> +/* >> + * UBLK_IO_FLAG_NEED_GET_DATA is set because IO command requires >> + * get data buffer address from ublksrv. >> + * >> + * Then, bio data could be copied into this data buffer for a WRITE request >> + * after the IO command is issued again and UBLK_IO_FLAG_NEED_GET_DATA is unset. >> + */ >> +#define UBLK_IO_FLAG_NEED_GET_DATA 0x08 >> + >> struct ublk_io { >> /* userspace buffer address from io cmd */ >> __u64 addr; >> @@ -168,6 +179,13 @@ static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq) >> return false; >> } >> >> +static inline bool ublk_need_get_data(const struct ublk_queue *ubq) >> +{ >> + if (ubq->flags & UBLK_F_NEED_GET_DATA) >> + return true; >> + return false; >> +} >> + >> static struct ublk_device *ublk_get_device(struct ublk_device *ub) >> { >> if (kobject_get_unless_zero(&ub->cdev_dev.kobj)) >> @@ -509,6 +527,21 @@ static void __ublk_fail_req(struct ublk_io *io, struct request *req) >> } >> } >> >> +static void ubq_complete_io_cmd(struct ublk_io *io, int res) >> +{ >> + /* mark this cmd owned by ublksrv */ >> + io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV; >> + >> + /* >> + * clear ACTIVE since we are done with this sqe/cmd slot >> + * We can only accept io cmd in case of being not active. >> + */ >> + io->flags &= ~UBLK_IO_FLAG_ACTIVE; >> + >> + /* tell ublksrv one io request is coming */ >> + io_uring_cmd_done(io->cmd, res, 0); >> +} >> + >> #define UBLK_REQUEUE_DELAY_MS 3 >> >> static inline void __ublk_rq_task_work(struct request *req) >> @@ -531,6 +564,20 @@ static inline void __ublk_rq_task_work(struct request *req) >> return; >> } >> >> + if (ublk_need_get_data(ubq) && >> + (req_op(req) == REQ_OP_WRITE || >> + req_op(req) == REQ_OP_FLUSH) && >> + !(io->flags & UBLK_IO_FLAG_NEED_GET_DATA)) { >> + >> + io->flags |= UBLK_IO_FLAG_NEED_GET_DATA; >> + >> + pr_devel("%s: ublk_need_get_data. op %d, qid %d tag %d io_flags %x\n", >> + __func__, io->cmd->cmd_op, ubq->q_id, req->tag, io->flags); >> + >> + ubq_complete_io_cmd(io, UBLK_IO_RES_NEED_GET_DATA); >> + return; >> + } >> + >> mapped_bytes = ublk_map_io(ubq, req, io); >> >> /* partially mapped, update io descriptor */ >> @@ -553,17 +600,13 @@ static inline void __ublk_rq_task_work(struct request *req) >> mapped_bytes >> 9; >> } >> >> - /* mark this cmd owned by ublksrv */ >> - io->flags |= UBLK_IO_FLAG_OWNED_BY_SRV; >> - >> /* >> - * clear ACTIVE since we are done with this sqe/cmd slot >> - * We can only accept io cmd in case of being not active. >> + * Anyway, we have handled UBLK_IO_NEED_GET_DATA for WRITE/FLUSH requests, >> + * or we did nothing for other types requests. >> */ >> - io->flags &= ~UBLK_IO_FLAG_ACTIVE; >> + io->flags &= ~UBLK_IO_FLAG_NEED_GET_DATA; > > Please move clearing UBLK_IO_FLAG_NEED_GET_DATA into ublk_handle_need_get_data(). > > UBLK_IO_FLAG_NEED_GET_DATA should only be touched in case that UBLK_F_NEED_GET_DATA > is set, also it becomes more readable. > > Otherwise, this patch looks fine. > Ok, it will be fixed in V4. Thanks, Zhang
