We have to add each submitted polled request to the io_ring_ctx poll_submitted list, which means we have to grab the poll_lock. We already use the block plug to batch submissions if we're doing a batch of IO submissions, extend that to cover the poll requests internally as well.
Signed-off-by: Jens Axboe <[email protected]> --- fs/io_uring.c | 122 +++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 106 insertions(+), 16 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index c872bfb32a03..f7938156552f 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -113,6 +113,21 @@ struct sqe_submit { unsigned index; }; +struct io_submit_state { + struct io_ring_ctx *ctx; + + struct blk_plug plug; +#ifdef CONFIG_BLOCK + struct blk_plug_cb plug_cb; +#endif + + /* + * Polled iocbs that have been submitted, but not added to the ctx yet + */ + struct list_head req_list; + unsigned int req_count; +}; + static struct kmem_cache *kiocb_cachep; static const struct file_operations io_scqring_fops; @@ -480,21 +495,29 @@ static inline void io_rw_done(struct kiocb *req, ssize_t ret) } /* - * After the iocb has been issued, it's safe to be found on the poll list. - * Adding the kiocb to the list AFTER submission ensures that we don't - * find it from a io_getevents() thread before the issuer is done accessing - * the kiocb cookie. + * Called either at the end of IO submission, or through a plug callback + * because we're going to schedule. Moves out local batch of requests to + * the ctx poll list, so they can be found for polling + reaping. */ -static void io_iopoll_kiocb_issued(struct io_kiocb *kiocb) +static void io_flush_state_reqs(struct io_ring_ctx *ctx, + struct io_submit_state *state) { + spin_lock(&ctx->poll_lock); + list_splice_tail_init(&state->req_list, &ctx->poll_submitted); + spin_unlock(&ctx->poll_lock); + state->req_count = 0; +} + +static void io_iopoll_iocb_add_list(struct io_kiocb *kiocb) +{ + const int front = test_bit(KIOCB_F_IOPOLL_COMPLETED, &kiocb->ki_flags); + struct io_ring_ctx *ctx = kiocb->ki_ctx; + /* * For fast devices, IO may have already completed. If it has, add * it to the front so we find it first. We can't add to the poll_done * list as that's unlocked from the completion side. */ - const int front = test_bit(KIOCB_F_IOPOLL_COMPLETED, &kiocb->ki_flags); - struct io_ring_ctx *ctx = kiocb->ki_ctx; - spin_lock(&ctx->poll_lock); if (front) list_add(&kiocb->ki_list, &ctx->poll_submitted); @@ -503,6 +526,33 @@ static void io_iopoll_kiocb_issued(struct io_kiocb *kiocb) spin_unlock(&ctx->poll_lock); } +static void io_iopoll_iocb_add_state(struct io_submit_state *state, + struct io_kiocb *kiocb) +{ + if (test_bit(KIOCB_F_IOPOLL_COMPLETED, &kiocb->ki_flags)) + list_add(&kiocb->ki_list, &state->req_list); + else + list_add_tail(&kiocb->ki_list, &state->req_list); + + if (++state->req_count >= IO_IOPOLL_BATCH) + io_flush_state_reqs(state->ctx, state); +} + +/* + * After the iocb has been issued, it's safe to be found on the poll list. + * Adding the kiocb to the list AFTER submission ensures that we don't + * find it from a io_getevents() thread before the issuer is done accessing + * the kiocb cookie. + */ +static void io_iopoll_kiocb_issued(struct io_submit_state *state, + struct io_kiocb *kiocb) +{ + if (!state || !IS_ENABLED(CONFIG_BLOCK)) + io_iopoll_iocb_add_list(kiocb); + else + io_iopoll_iocb_add_state(state, kiocb); +} + static ssize_t io_read(struct io_kiocb *kiocb, const struct io_uring_sqe *sqe) { struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; @@ -624,7 +674,8 @@ static int io_fsync(struct io_kiocb *kiocb, const struct io_uring_sqe *sqe, return 0; } -static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s) +static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s, + struct io_submit_state *state) { const struct io_uring_sqe *sqe = s->sqe; struct io_kiocb *req; @@ -673,7 +724,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s) ret = -EAGAIN; goto out_put_req; } - io_iopoll_kiocb_issued(req); + io_iopoll_kiocb_issued(state, req); } return 0; out_put_req: @@ -681,6 +732,43 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s) return ret; } +#ifdef CONFIG_BLOCK +static void io_state_unplug(struct blk_plug_cb *cb, bool from_schedule) +{ + struct io_submit_state *state; + + state = container_of(cb, struct io_submit_state, plug_cb); + if (!list_empty(&state->req_list)) + io_flush_state_reqs(state->ctx, state); +} +#endif + +/* + * Batched submission is done, ensure local IO is flushed out. + */ +static void io_submit_state_end(struct io_submit_state *state) +{ + blk_finish_plug(&state->plug); + if (!list_empty(&state->req_list)) + io_flush_state_reqs(state->ctx, state); +} + +/* + * Start submission side cache. + */ +static void io_submit_state_start(struct io_submit_state *state, + struct io_ring_ctx *ctx) +{ + state->ctx = ctx; + INIT_LIST_HEAD(&state->req_list); + state->req_count = 0; +#ifdef CONFIG_BLOCK + state->plug_cb.callback = io_state_unplug; + blk_start_plug(&state->plug); + list_add(&state->plug_cb.list, &state->plug.cb_list); +#endif +} + static void io_inc_sqring(struct io_ring_ctx *ctx) { struct io_sq_ring *ring = ctx->sq_ring; @@ -715,11 +803,13 @@ static bool io_peek_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s) static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit) { + struct io_submit_state state, *statep = NULL; int i, ret = 0, submit = 0; - struct blk_plug plug; - if (to_submit > IO_PLUG_THRESHOLD) - blk_start_plug(&plug); + if (to_submit > IO_PLUG_THRESHOLD) { + io_submit_state_start(&state, ctx); + statep = &state; + } for (i = 0; i < to_submit; i++) { struct sqe_submit s; @@ -727,7 +817,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit) if (!io_peek_sqring(ctx, &s)) break; - ret = io_submit_sqe(ctx, &s); + ret = io_submit_sqe(ctx, &s, statep); if (ret) break; @@ -735,8 +825,8 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit) io_inc_sqring(ctx); } - if (to_submit > IO_PLUG_THRESHOLD) - blk_finish_plug(&plug); + if (statep) + io_submit_state_end(statep); return submit ? submit : ret; } -- 2.17.1
