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 | 121 +++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 106 insertions(+), 15 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index fb1b04ccc12a..62f31f20f3d5 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -126,6 +126,21 @@ struct io_kiocb { #define IO_PLUG_THRESHOLD 2 #define IO_IOPOLL_BATCH 8 +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_multi req_list; + unsigned int req_count; +}; + static struct kmem_cache *req_cachep; static const struct file_operations io_uring_fops; @@ -288,6 +303,12 @@ static void io_multi_list_add(struct io_kiocb *req, struct list_multi *list) list_add_tail(&req->list, &list->list); } +static void io_multi_list_splice(struct list_multi *src, struct list_multi *dst) +{ + list_splice_tail_init(&src->list, &dst->list); + dst->multi |= src->multi; +} + /* * Find and free completed poll iocbs */ @@ -459,17 +480,46 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) } } +/* + * 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_flush_state_reqs(struct io_ring_ctx *ctx, + struct io_submit_state *state) +{ + io_multi_list_splice(&state->req_list, &ctx->poll_list); + state->req_count = 0; +} + +static void io_iopoll_req_add_list(struct io_kiocb *req) +{ + struct io_ring_ctx *ctx = req->ctx; + + io_multi_list_add(req, &ctx->poll_list); +} + +static void io_iopoll_req_add_state(struct io_submit_state *state, + struct io_kiocb *req) +{ + io_multi_list_add(req, &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_req_issued(struct io_kiocb *req) +static void io_iopoll_req_issued(struct io_submit_state *state, + struct io_kiocb *req) { - struct io_ring_ctx *ctx = req->ctx; - - io_multi_list_add(req, &ctx->poll_list); + if (!state || !IS_ENABLED(CONFIG_BLOCK)) + io_iopoll_req_add_list(req); + else + io_iopoll_req_add_state(state, req); } static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, @@ -701,7 +751,8 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe, } static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, - struct sqe_submit *s, bool force_nonblock) + struct sqe_submit *s, bool force_nonblock, + struct io_submit_state *state) { const struct io_uring_sqe *sqe = s->sqe; ssize_t ret; @@ -739,7 +790,7 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, if (ctx->flags & IORING_SETUP_IOPOLL) { if (req->flags & REQ_F_IOPOLL_EAGAIN) return -EAGAIN; - io_iopoll_req_issued(req); + io_iopoll_req_issued(state, req); } return 0; @@ -771,7 +822,7 @@ static void io_sq_wq_submit_work(struct work_struct *work) use_mm(ctx->sqo_mm); set_fs(USER_DS); - ret = __io_submit_sqe(ctx, req, &req->work.submit, false); + ret = __io_submit_sqe(ctx, req, &req->work.submit, false, NULL); set_fs(old_fs); unuse_mm(ctx->sqo_mm); @@ -784,7 +835,8 @@ static void io_sq_wq_submit_work(struct work_struct *work) current->files = old_files; } -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) { struct io_kiocb *req; ssize_t ret; @@ -793,7 +845,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s) if (unlikely(!req)) return -EAGAIN; - ret = __io_submit_sqe(ctx, req, s, true); + ret = __io_submit_sqe(ctx, req, s, true, state); if (ret == -EAGAIN) { memcpy(&req->work.submit, s, sizeof(*s)); INIT_WORK(&req->work.work, io_sq_wq_submit_work); @@ -806,6 +858,43 @@ 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.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.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.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; @@ -840,11 +929,13 @@ 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; @@ -852,7 +943,7 @@ 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; @@ -860,8 +951,8 @@ 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
