On 9/30/19 2:37 AM, Jackie Liu wrote: > > >> 在 2019年9月29日，22:54，Jens Axboe <[email protected]> 写道： >> >> Currently any dependent link is executed from a new workqueue context, >> which means that we'll be doing a context switch per link in the chain. >> If we are running the completion of the current request from our async >> workqueue and find that the next request is a link, then run it directly >> from the workqueue context instead of forcing another switch. >> >> This improves the performance of linked SQEs, and reduces the CPU >> overhead. >> >> Signed-off-by: Jens Axboe <[email protected]> >> >> --- >> >> v2: >> - Improve naming >> - Improve async detection >> - Harden cases where we could miss req return >> - Add support for fsync/sync_file_range/recvmsg/sendmsg >> >> 2-3x speedup doing read-write links, where the read often ends up >> blocking. Tested with examples/link-cp.c >> >> diff --git a/fs/io_uring.c b/fs/io_uring.c >> index aa8ac557493c..742d95563a54 100644 >> --- a/fs/io_uring.c >> +++ b/fs/io_uring.c >> @@ -667,7 +667,7 @@ static void __io_free_req(struct io_kiocb *req) >> kmem_cache_free(req_cachep, req); >> } >> >> -static void io_req_link_next(struct io_kiocb *req) >> +struct io_kiocb *io_req_link_next(struct io_kiocb *req) >> { >> struct io_kiocb *nxt; >> >> @@ -686,9 +686,19 @@ static void io_req_link_next(struct io_kiocb *req) >> } >> >> nxt->flags |= REQ_F_LINK_DONE; >> + /* >> + * If we're in async work, we can continue processing this, >> + * we can continue processing the chain in this context instead >> + * of having to queue up new async work. >> + */ >> + if (current_work()) >> + return nxt; >> INIT_WORK(&nxt->work, io_sq_wq_submit_work); >> io_queue_async_work(req->ctx, nxt); >> + nxt = NULL; >> } >> + >> + return nxt; >> } >> >> /* >> @@ -707,8 +717,10 @@ static void io_fail_links(struct io_kiocb *req) >> } >> } >> >> -static void io_free_req(struct io_kiocb *req) >> +static struct io_kiocb *io_free_req(struct io_kiocb *req) >> { >> + struct io_kiocb *nxt = NULL; >> + >> /* >> * If LINK is set, we have dependent requests in this chain. If we >> * didn't fail this request, queue the first one up, moving any other >> @@ -719,16 +731,30 @@ static void io_free_req(struct io_kiocb *req) >> if (req->flags & REQ_F_FAIL_LINK) >> io_fail_links(req); >> else >> - io_req_link_next(req); >> + nxt = io_req_link_next(req); >> } >> >> __io_free_req(req); >> + return nxt; >> } >> >> -static void io_put_req(struct io_kiocb *req) >> +static struct io_kiocb *__io_put_req(struct io_kiocb *req) >> { >> if (refcount_dec_and_test(&req->refs)) >> - io_free_req(req); >> + return io_free_req(req); >> + >> + return NULL; >> +} >> + >> +static void io_put_req(struct io_kiocb *req) >> +{ >> + struct io_kiocb *nxt; >> + >> + nxt = __io_put_req(req); >> + if (nxt) { >> + INIT_WORK(&nxt->work, io_sq_wq_submit_work); >> + io_queue_async_work(nxt->ctx, nxt); >> + } >> } >> >> static unsigned io_cqring_events(struct io_rings *rings) >> @@ -934,7 +960,7 @@ static void kiocb_end_write(struct kiocb *kiocb) >> } >> } >> >> -static void io_complete_rw(struct kiocb *kiocb, long res, long res2) >> +static void io_complete_rw_common(struct kiocb *kiocb, long res) >> { >> struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); >> >> @@ -943,9 +969,24 @@ static void io_complete_rw(struct kiocb *kiocb, long >> res, long res2) >> if ((req->flags & REQ_F_LINK) && res != req->result) >> req->flags |= REQ_F_FAIL_LINK; >> io_cqring_add_event(req->ctx, req->user_data, res); >> +} >> + >> +static void io_complete_rw(struct kiocb *kiocb, long res, long res2) >> +{ >> + struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); >> + >> + io_complete_rw_common(kiocb, res); >> io_put_req(req); >> } >> >> +static struct io_kiocb *__io_complete_rw(struct kiocb *kiocb, long res) >> +{ >> + struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); >> + >> + io_complete_rw_common(kiocb, res); >> + return __io_put_req(req); >> +} >> + >> static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) >> { >> struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); >> @@ -1128,6 +1169,15 @@ static inline void io_rw_done(struct kiocb *kiocb, >> ssize_t ret) >> } >> } >> >> +static void call_io_rw_done(struct kiocb *kiocb, ssize_t ret, >> + struct io_kiocb **nxt, bool in_async) >> +{ >> + if (in_async && ret >= 0 && nxt && kiocb->ki_complete == io_complete_rw) >> + *nxt = __io_complete_rw(kiocb, ret); >> + else >> + io_rw_done(kiocb, ret); >> +} >> + >> static int io_import_fixed(struct io_ring_ctx *ctx, int rw, >> const struct io_uring_sqe *sqe, >> struct iov_iter *iter) >> @@ -1344,7 +1394,7 @@ static ssize_t loop_rw_iter(int rw, struct file *file, >> struct kiocb *kiocb, >> } >> >> static int io_read(struct io_kiocb *req, const struct sqe_submit *s, >> - bool force_nonblock) >> + bool force_nonblock, struct io_kiocb **nxt) >> { >> struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; >> struct kiocb *kiocb = &req->rw; >> @@ -1391,7 +1441,7 @@ static int io_read(struct io_kiocb *req, const struct >> sqe_submit *s, >> ret2 = -EAGAIN; >> /* Catch -EAGAIN return for forced non-blocking submission */ >> if (!force_nonblock || ret2 != -EAGAIN) { >> - io_rw_done(kiocb, ret2); >> + call_io_rw_done(kiocb, ret2, nxt, s->needs_lock); >> } else { >> /* >> * If ->needs_lock is true, we're already in async >> @@ -1407,7 +1457,7 @@ static int io_read(struct io_kiocb *req, const struct >> sqe_submit *s, >> } >> >> static int io_write(struct io_kiocb *req, const struct sqe_submit *s, >> - bool force_nonblock) >> + bool force_nonblock, struct io_kiocb **nxt) >> { >> struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; >> struct kiocb *kiocb = &req->rw; >> @@ -1465,7 +1515,7 @@ static int io_write(struct io_kiocb *req, const struct >> sqe_submit *s, >> else >> ret2 = loop_rw_iter(WRITE, file, kiocb, &iter); >> if (!force_nonblock || ret2 != -EAGAIN) { >> - io_rw_done(kiocb, ret2); >> + call_io_rw_done(kiocb, ret2, nxt, s->needs_lock); >> } else { >> /* >> * If ->needs_lock is true, we're already in async >> @@ -1968,7 +2018,8 @@ static int io_req_defer(struct io_ring_ctx *ctx, >> struct io_kiocb *req, >> } >> >> static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, >> - const struct sqe_submit *s, bool force_nonblock) >> + const struct sqe_submit *s, bool force_nonblock, >> + struct io_kiocb **nxt) >> { >> int ret, opcode; >> >> @@ -1985,18 +2036,18 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, >> struct io_kiocb *req, >> case IORING_OP_READV: >> if (unlikely(s->sqe->buf_index)) >> return -EINVAL; >> - ret = io_read(req, s, force_nonblock); >> + ret = io_read(req, s, force_nonblock, nxt); >> break; >> case IORING_OP_WRITEV: >> if (unlikely(s->sqe->buf_index)) >> return -EINVAL; >> - ret = io_write(req, s, force_nonblock); >> + ret = io_write(req, s, force_nonblock, nxt); >> break; >> case IORING_OP_READ_FIXED: >> - ret = io_read(req, s, force_nonblock); >> + ret = io_read(req, s, force_nonblock, nxt); >> break; >> case IORING_OP_WRITE_FIXED: >> - ret = io_write(req, s, force_nonblock); >> + ret = io_write(req, s, force_nonblock, nxt); >> break; >> case IORING_OP_FSYNC: >> ret = io_fsync(req, s->sqe, force_nonblock); >> @@ -2081,6 +2132,7 @@ static void io_sq_wq_submit_work(struct work_struct >> *work) >> struct sqe_submit *s = &req->submit; >> const struct io_uring_sqe *sqe = s->sqe; >> unsigned int flags = req->flags; >> + struct io_kiocb *nxt = NULL; >> >> /* Ensure we clear previously set non-block flag */ >> req->rw.ki_flags &= ~IOCB_NOWAIT; >> @@ -2101,7 +2153,7 @@ static void io_sq_wq_submit_work(struct work_struct >> *work) >> s->has_user = cur_mm != NULL; >> s->needs_lock = true; >> do { >> - ret = __io_submit_sqe(ctx, req, s, false); >> + ret = __io_submit_sqe(ctx, req, s, false, &nxt); >> /* >> * We can get EAGAIN for polled IO even though >> * we're forcing a sync submission from here, >> @@ -2125,6 +2177,12 @@ static void io_sq_wq_submit_work(struct work_struct >> *work) >> /* async context always use a copy of the sqe */ >> kfree(sqe); >> >> + /* if a dependent link is ready, do that as the next one */ >> + if (!ret && nxt) { >> + req = nxt; >> + continue; >> + } >> + >> /* req from defer and link list needn't decrease async cnt */ >> if (flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE)) >> goto out; >> @@ -2271,7 +2329,7 @@ static int __io_queue_sqe(struct io_ring_ctx *ctx, >> struct io_kiocb *req, >> { >> int ret; >> >> - ret = __io_submit_sqe(ctx, req, s, force_nonblock); >> + ret = __io_submit_sqe(ctx, req, s, force_nonblock, NULL); >> if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) { >> struct io_uring_sqe *sqe_copy; >> >> -- >> Jens Axboe >> >> > > Hi Jens, are you sure this is version 2, why is it the same as v1? > Is Link [1] is the correct one? > > Link: [1] > http://git.kernel.dk/cgit/linux-block/patch/?id=39b0f9f8e295b98bbcfd448709fa298f5545e28c
Yeah the link is the right one, that's odd. Below for reference! commit 98bb8de9e72fc61210976db3368dd3ad2549fa3c Author: Jens Axboe <[email protected]> Date: Sat Sep 28 11:36:45 2019 -0600 io_uring: run dependent links inline if possible Currently any dependent link is executed from a new workqueue context, which means that we'll be doing a context switch per link in the chain. If we are running the completion of the current request from our async workqueue and find that the next request is a link, then run it directly from the workqueue context instead of forcing another switch. This improves the performance of linked SQEs, and reduces the CPU overhead. Signed-off-by: Jens Axboe <[email protected]> diff --git a/fs/io_uring.c b/fs/io_uring.c index aa8ac557493c..83a07a47683d 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -667,7 +667,7 @@ static void __io_free_req(struct io_kiocb *req) kmem_cache_free(req_cachep, req); } -static void io_req_link_next(struct io_kiocb *req) +static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr) { struct io_kiocb *nxt; @@ -686,8 +686,16 @@ static void io_req_link_next(struct io_kiocb *req) } nxt->flags |= REQ_F_LINK_DONE; - INIT_WORK(&nxt->work, io_sq_wq_submit_work); - io_queue_async_work(req->ctx, nxt); + /* + * If we're in async work, we can continue processing the chain + * in this context instead of having to queue up new async work. + */ + if (nxtptr && current_work()) { + *nxtptr = nxt; + } else { + INIT_WORK(&nxt->work, io_sq_wq_submit_work); + io_queue_async_work(req->ctx, nxt); + } } } @@ -707,7 +715,7 @@ static void io_fail_links(struct io_kiocb *req) } } -static void io_free_req(struct io_kiocb *req) +static void io_free_req(struct io_kiocb *req, struct io_kiocb **nxt) { /* * If LINK is set, we have dependent requests in this chain. If we @@ -719,16 +727,39 @@ static void io_free_req(struct io_kiocb *req) if (req->flags & REQ_F_FAIL_LINK) io_fail_links(req); else - io_req_link_next(req); + io_req_link_next(req, nxt); } __io_free_req(req); } -static void io_put_req(struct io_kiocb *req) +/* + * Drop reference to request, return next in chain (if there is one) if this + * was the last reference to this request. + */ +static struct io_kiocb *io_put_req_find_next(struct io_kiocb *req) { + struct io_kiocb *nxt = NULL; + if (refcount_dec_and_test(&req->refs)) - io_free_req(req); + io_free_req(req, &nxt); + + return nxt; +} + +static void io_put_req(struct io_kiocb *req, struct io_kiocb **nxtptr) +{ + struct io_kiocb *nxt; + + nxt = io_put_req_find_next(req); + if (nxt) { + if (nxtptr) { + *nxtptr = nxt; + } else { + INIT_WORK(&nxt->work, io_sq_wq_submit_work); + io_queue_async_work(nxt->ctx, nxt); + } + } } static unsigned io_cqring_events(struct io_rings *rings) @@ -768,7 +799,7 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events, if (to_free == ARRAY_SIZE(reqs)) io_free_req_many(ctx, reqs, &to_free); } else { - io_free_req(req); + io_free_req(req, NULL); } } } @@ -934,7 +965,7 @@ static void kiocb_end_write(struct kiocb *kiocb) } } -static void io_complete_rw(struct kiocb *kiocb, long res, long res2) +static void io_complete_rw_common(struct kiocb *kiocb, long res) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); @@ -943,7 +974,22 @@ static void io_complete_rw(struct kiocb *kiocb, long res, long res2) if ((req->flags & REQ_F_LINK) && res != req->result) req->flags |= REQ_F_FAIL_LINK; io_cqring_add_event(req->ctx, req->user_data, res); - io_put_req(req); +} + +static void io_complete_rw(struct kiocb *kiocb, long res, long res2) +{ + struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); + + io_complete_rw_common(kiocb, res); + io_put_req(req, NULL); +} + +static struct io_kiocb *__io_complete_rw(struct kiocb *kiocb, long res) +{ + struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); + + io_complete_rw_common(kiocb, res); + return io_put_req_find_next(req); } static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) @@ -1128,6 +1174,15 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret) } } +static void kiocb_done(struct kiocb *kiocb, ssize_t ret, struct io_kiocb **nxt, + bool in_async) +{ + if (in_async && ret >= 0 && nxt && kiocb->ki_complete == io_complete_rw) + *nxt = __io_complete_rw(kiocb, ret); + else + io_rw_done(kiocb, ret); +} + static int io_import_fixed(struct io_ring_ctx *ctx, int rw, const struct io_uring_sqe *sqe, struct iov_iter *iter) @@ -1344,7 +1399,7 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb, } static int io_read(struct io_kiocb *req, const struct sqe_submit *s, - bool force_nonblock) + struct io_kiocb **nxt, bool force_nonblock) { struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; struct kiocb *kiocb = &req->rw; @@ -1391,7 +1446,7 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s, ret2 = -EAGAIN; /* Catch -EAGAIN return for forced non-blocking submission */ if (!force_nonblock || ret2 != -EAGAIN) { - io_rw_done(kiocb, ret2); + kiocb_done(kiocb, ret2, nxt, s->needs_lock); } else { /* * If ->needs_lock is true, we're already in async @@ -1407,7 +1462,7 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s, } static int io_write(struct io_kiocb *req, const struct sqe_submit *s, - bool force_nonblock) + struct io_kiocb **nxt, bool force_nonblock) { struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs; struct kiocb *kiocb = &req->rw; @@ -1465,7 +1520,7 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s, else ret2 = loop_rw_iter(WRITE, file, kiocb, &iter); if (!force_nonblock || ret2 != -EAGAIN) { - io_rw_done(kiocb, ret2); + kiocb_done(kiocb, ret2, nxt, s->needs_lock); } else { /* * If ->needs_lock is true, we're already in async @@ -1493,7 +1548,7 @@ static int io_nop(struct io_kiocb *req, u64 user_data) return -EINVAL; io_cqring_add_event(ctx, user_data, err); - io_put_req(req); + io_put_req(req, NULL); return 0; } @@ -1513,7 +1568,7 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe) } static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe, - bool force_nonblock) + struct io_kiocb **nxt, bool force_nonblock) { loff_t sqe_off = READ_ONCE(sqe->off); loff_t sqe_len = READ_ONCE(sqe->len); @@ -1540,7 +1595,7 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe, if (ret < 0 && (req->flags & REQ_F_LINK)) req->flags |= REQ_F_FAIL_LINK; io_cqring_add_event(req->ctx, sqe->user_data, ret); - io_put_req(req); + io_put_req(req, nxt); return 0; } @@ -1562,6 +1617,7 @@ static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe) static int io_sync_file_range(struct io_kiocb *req, const struct io_uring_sqe *sqe, + struct io_kiocb **nxt, bool force_nonblock) { loff_t sqe_off; @@ -1586,13 +1642,13 @@ static int io_sync_file_range(struct io_kiocb *req, if (ret < 0 && (req->flags & REQ_F_LINK)) req->flags |= REQ_F_FAIL_LINK; io_cqring_add_event(req->ctx, sqe->user_data, ret); - io_put_req(req); + io_put_req(req, nxt); return 0; } #if defined(CONFIG_NET) static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe, - bool force_nonblock, + struct io_kiocb **nxt, bool force_nonblock, long (*fn)(struct socket *, struct user_msghdr __user *, unsigned int)) { @@ -1622,26 +1678,28 @@ static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe, } io_cqring_add_event(req->ctx, sqe->user_data, ret); - io_put_req(req); + io_put_req(req, nxt); return 0; } #endif static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe, - bool force_nonblock) + struct io_kiocb **nxt, bool force_nonblock) { #if defined(CONFIG_NET) - return io_send_recvmsg(req, sqe, force_nonblock, __sys_sendmsg_sock); + return io_send_recvmsg(req, sqe, nxt, force_nonblock, + __sys_sendmsg_sock); #else return -EOPNOTSUPP; #endif } static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe, - bool force_nonblock) + struct io_kiocb **nxt, bool force_nonblock) { #if defined(CONFIG_NET) - return io_send_recvmsg(req, sqe, force_nonblock, __sys_recvmsg_sock); + return io_send_recvmsg(req, sqe, nxt, force_nonblock, + __sys_recvmsg_sock); #else return -EOPNOTSUPP; #endif @@ -1701,7 +1759,7 @@ static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe) spin_unlock_irq(&ctx->completion_lock); io_cqring_add_event(req->ctx, sqe->user_data, ret); - io_put_req(req); + io_put_req(req, NULL); return 0; } @@ -1742,7 +1800,7 @@ static void io_poll_complete_work(struct work_struct *work) spin_unlock_irq(&ctx->completion_lock); io_cqring_ev_posted(ctx); - io_put_req(req); + io_put_req(req, NULL); } static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, @@ -1767,7 +1825,7 @@ static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync, spin_unlock_irqrestore(&ctx->completion_lock, flags); io_cqring_ev_posted(ctx); - io_put_req(req); + io_put_req(req, NULL); } else { io_queue_async_work(ctx, req); } @@ -1859,7 +1917,7 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe) if (mask) { io_cqring_ev_posted(ctx); - io_put_req(req); + io_put_req(req, NULL); } return ipt.error; } @@ -1883,7 +1941,7 @@ static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer) io_cqring_ev_posted(ctx); - io_put_req(req); + io_put_req(req, NULL); return HRTIMER_NORESTART; } @@ -1968,7 +2026,8 @@ static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req, } static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, - const struct sqe_submit *s, bool force_nonblock) + const struct sqe_submit *s, struct io_kiocb **nxt, + bool force_nonblock) { int ret, opcode; @@ -1985,21 +2044,21 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, case IORING_OP_READV: if (unlikely(s->sqe->buf_index)) return -EINVAL; - ret = io_read(req, s, force_nonblock); + ret = io_read(req, s, nxt, force_nonblock); break; case IORING_OP_WRITEV: if (unlikely(s->sqe->buf_index)) return -EINVAL; - ret = io_write(req, s, force_nonblock); + ret = io_write(req, s, nxt, force_nonblock); break; case IORING_OP_READ_FIXED: - ret = io_read(req, s, force_nonblock); + ret = io_read(req, s, nxt, force_nonblock); break; case IORING_OP_WRITE_FIXED: - ret = io_write(req, s, force_nonblock); + ret = io_write(req, s, nxt, force_nonblock); break; case IORING_OP_FSYNC: - ret = io_fsync(req, s->sqe, force_nonblock); + ret = io_fsync(req, s->sqe, nxt, force_nonblock); break; case IORING_OP_POLL_ADD: ret = io_poll_add(req, s->sqe); @@ -2008,13 +2067,13 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, ret = io_poll_remove(req, s->sqe); break; case IORING_OP_SYNC_FILE_RANGE: - ret = io_sync_file_range(req, s->sqe, force_nonblock); + ret = io_sync_file_range(req, s->sqe, nxt, force_nonblock); break; case IORING_OP_SENDMSG: - ret = io_sendmsg(req, s->sqe, force_nonblock); + ret = io_sendmsg(req, s->sqe, nxt, force_nonblock); break; case IORING_OP_RECVMSG: - ret = io_recvmsg(req, s->sqe, force_nonblock); + ret = io_recvmsg(req, s->sqe, nxt, force_nonblock); break; case IORING_OP_TIMEOUT: ret = io_timeout(req, s->sqe); @@ -2081,6 +2140,7 @@ static void io_sq_wq_submit_work(struct work_struct *work) struct sqe_submit *s = &req->submit; const struct io_uring_sqe *sqe = s->sqe; unsigned int flags = req->flags; + struct io_kiocb *nxt = NULL; /* Ensure we clear previously set non-block flag */ req->rw.ki_flags &= ~IOCB_NOWAIT; @@ -2101,7 +2161,7 @@ static void io_sq_wq_submit_work(struct work_struct *work) s->has_user = cur_mm != NULL; s->needs_lock = true; do { - ret = __io_submit_sqe(ctx, req, s, false); + ret = __io_submit_sqe(ctx, req, s, &nxt, false); /* * We can get EAGAIN for polled IO even though * we're forcing a sync submission from here, @@ -2115,16 +2175,22 @@ static void io_sq_wq_submit_work(struct work_struct *work) } /* drop submission reference */ - io_put_req(req); + io_put_req(req, NULL); if (ret) { io_cqring_add_event(ctx, sqe->user_data, ret); - io_put_req(req); + io_put_req(req, NULL); } /* async context always use a copy of the sqe */ kfree(sqe); + /* if a dependent link is ready, do that as the next one */ + if (!ret && nxt) { + req = nxt; + continue; + } + /* req from defer and link list needn't decrease async cnt */ if (flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE)) goto out; @@ -2271,7 +2337,7 @@ static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, { int ret; - ret = __io_submit_sqe(ctx, req, s, force_nonblock); + ret = __io_submit_sqe(ctx, req, s, NULL, force_nonblock); if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) { struct io_uring_sqe *sqe_copy; @@ -2298,14 +2364,14 @@ static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, } /* drop submission reference */ - io_put_req(req); + io_put_req(req, NULL); /* and drop final reference, if we failed */ if (ret) { io_cqring_add_event(ctx, req->user_data, ret); if (req->flags & REQ_F_LINK) req->flags |= REQ_F_FAIL_LINK; - io_put_req(req); + io_put_req(req, NULL); } return ret; @@ -2319,7 +2385,7 @@ static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, ret = io_req_defer(ctx, req, s->sqe); if (ret) { if (ret != -EIOCBQUEUED) { - io_free_req(req); + io_free_req(req, NULL); io_cqring_add_event(ctx, s->sqe->user_data, ret); } return 0; @@ -2347,7 +2413,7 @@ static int io_queue_link_head(struct io_ring_ctx *ctx, struct io_kiocb *req, ret = io_req_defer(ctx, req, s->sqe); if (ret) { if (ret != -EIOCBQUEUED) { - io_free_req(req); + io_free_req(req, NULL); io_cqring_add_event(ctx, s->sqe->user_data, ret); return 0; } @@ -2395,7 +2461,7 @@ static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s, ret = io_req_set_file(ctx, s, state, req); if (unlikely(ret)) { err_req: - io_free_req(req); + io_free_req(req, NULL); err: io_cqring_add_event(ctx, s->sqe->user_data, ret); return; -- Jens Axboe
