diff options
Diffstat (limited to 'fs/io_uring.c')
| -rw-r--r-- | fs/io_uring.c | 249 |
1 files changed, 242 insertions, 7 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c index 5eaa1c4a3f7c..0a4caedf82c1 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -44,6 +44,7 @@ #include <linux/percpu.h> #include <linux/slab.h> #include <linux/workqueue.h> +#include <linux/kthread.h> #include <linux/blkdev.h> #include <linux/bvec.h> #include <linux/net.h> @@ -108,12 +109,16 @@ struct io_ring_ctx { unsigned cached_sq_head; unsigned sq_entries; unsigned sq_mask; + unsigned sq_thread_idle; struct io_uring_sqe *sq_sqes; } ____cacheline_aligned_in_smp; /* IO offload */ struct workqueue_struct *sqo_wq; + struct task_struct *sqo_thread; /* if using sq thread polling */ struct mm_struct *sqo_mm; + wait_queue_head_t sqo_wait; + unsigned sqo_stop; struct { /* CQ ring */ @@ -168,6 +173,7 @@ struct sqe_submit { unsigned short index; bool has_user; bool needs_lock; + bool needs_fixed_file; }; struct io_kiocb { @@ -327,6 +333,8 @@ static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 ki_user_data, if (waitqueue_active(&ctx->wait)) wake_up(&ctx->wait); + if (waitqueue_active(&ctx->sqo_wait)) + wake_up(&ctx->sqo_wait); } static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs) @@ -680,9 +688,10 @@ static bool io_file_supports_async(struct file *file) return false; } -static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, +static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, bool force_nonblock, struct io_submit_state *state) { + const struct io_uring_sqe *sqe = s->sqe; struct io_ring_ctx *ctx = req->ctx; struct kiocb *kiocb = &req->rw; unsigned ioprio, flags; @@ -702,6 +711,8 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe, kiocb->ki_filp = ctx->user_files[fd]; req->flags |= REQ_F_FIXED_FILE; } else { + if (s->needs_fixed_file) + return -EBADF; kiocb->ki_filp = io_file_get(state, fd); if (unlikely(!kiocb->ki_filp)) return -EBADF; @@ -865,7 +876,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s, struct file *file; ssize_t ret; - ret = io_prep_rw(req, s->sqe, force_nonblock, state); + ret = io_prep_rw(req, s, force_nonblock, state); if (ret) return ret; file = kiocb->ki_filp; @@ -909,7 +920,7 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s, struct file *file; ssize_t ret; - ret = io_prep_rw(req, s->sqe, force_nonblock, state); + ret = io_prep_rw(req, s, force_nonblock, state); if (ret) return ret; /* Hold on to the file for -EAGAIN */ @@ -1301,6 +1312,169 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s) return false; } +static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes, + unsigned int nr, bool has_user, bool mm_fault) +{ + struct io_submit_state state, *statep = NULL; + int ret, i, submitted = 0; + + if (nr > IO_PLUG_THRESHOLD) { + io_submit_state_start(&state, ctx, nr); + statep = &state; + } + + for (i = 0; i < nr; i++) { + if (unlikely(mm_fault)) { + ret = -EFAULT; + } else { + sqes[i].has_user = has_user; + sqes[i].needs_lock = true; + sqes[i].needs_fixed_file = true; + ret = io_submit_sqe(ctx, &sqes[i], statep); + } + if (!ret) { + submitted++; + continue; + } + + io_cqring_add_event(ctx, sqes[i].sqe->user_data, ret, 0); + } + + if (statep) + io_submit_state_end(&state); + + return submitted; +} + +static int io_sq_thread(void *data) +{ + struct sqe_submit sqes[IO_IOPOLL_BATCH]; + struct io_ring_ctx *ctx = data; + struct mm_struct *cur_mm = NULL; + mm_segment_t old_fs; + DEFINE_WAIT(wait); + unsigned inflight; + unsigned long timeout; + + old_fs = get_fs(); + set_fs(USER_DS); + + timeout = inflight = 0; + while (!kthread_should_stop() && !ctx->sqo_stop) { + bool all_fixed, mm_fault = false; + int i; + + if (inflight) { + unsigned nr_events = 0; + + if (ctx->flags & IORING_SETUP_IOPOLL) { + /* + * We disallow the app entering submit/complete + * with polling, but we still need to lock the + * ring to prevent racing with polled issue + * that got punted to a workqueue. + */ + mutex_lock(&ctx->uring_lock); + io_iopoll_check(ctx, &nr_events, 0); + mutex_unlock(&ctx->uring_lock); + } else { + /* + * Normal IO, just pretend everything completed. + * We don't have to poll completions for that. + */ + nr_events = inflight; + } + + inflight -= nr_events; + if (!inflight) + timeout = jiffies + ctx->sq_thread_idle; + } + + if (!io_get_sqring(ctx, &sqes[0])) { + /* + * We're polling. If we're within the defined idle + * period, then let us spin without work before going + * to sleep. + */ + if (inflight || !time_after(jiffies, timeout)) { + cpu_relax(); + continue; + } + + /* + * Drop cur_mm before scheduling, we can't hold it for + * long periods (or over schedule()). Do this before + * adding ourselves to the waitqueue, as the unuse/drop + * may sleep. + */ + if (cur_mm) { + unuse_mm(cur_mm); + mmput(cur_mm); + cur_mm = NULL; + } + + prepare_to_wait(&ctx->sqo_wait, &wait, + TASK_INTERRUPTIBLE); + + /* Tell userspace we may need a wakeup call */ + ctx->sq_ring->flags |= IORING_SQ_NEED_WAKEUP; + smp_wmb(); + + if (!io_get_sqring(ctx, &sqes[0])) { + if (kthread_should_stop()) { + finish_wait(&ctx->sqo_wait, &wait); + break; + } + if (signal_pending(current)) + flush_signals(current); + schedule(); + finish_wait(&ctx->sqo_wait, &wait); + + ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP; + smp_wmb(); + continue; + } + finish_wait(&ctx->sqo_wait, &wait); + + ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP; + smp_wmb(); + } + + i = 0; + all_fixed = true; + do { + if (all_fixed && io_sqe_needs_user(sqes[i].sqe)) + all_fixed = false; + + i++; + if (i == ARRAY_SIZE(sqes)) + break; + } while (io_get_sqring(ctx, &sqes[i])); + + /* Unless all new commands are FIXED regions, grab mm */ + if (!all_fixed && !cur_mm) { + mm_fault = !mmget_not_zero(ctx->sqo_mm); + if (!mm_fault) { + use_mm(ctx->sqo_mm); + cur_mm = ctx->sqo_mm; + } + } + + inflight += io_submit_sqes(ctx, sqes, i, cur_mm != NULL, + mm_fault); + + /* Commit SQ ring head once we've consumed all SQEs */ + io_commit_sqring(ctx); + } + + set_fs(old_fs); + if (cur_mm) { + unuse_mm(cur_mm); + mmput(cur_mm); + } + return 0; +} + static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit) { struct io_submit_state state, *statep = NULL; @@ -1319,6 +1493,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit) s.has_user = true; s.needs_lock = false; + s.needs_fixed_file = false; ret = io_submit_sqe(ctx, &s, statep); if (ret) { @@ -1418,8 +1593,20 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx) return 0; } +static void io_sq_thread_stop(struct io_ring_ctx *ctx) +{ + if (ctx->sqo_thread) { + ctx->sqo_stop = 1; + mb(); + kthread_stop(ctx->sqo_thread); + ctx->sqo_thread = NULL; + } +} + static void io_finish_async(struct io_ring_ctx *ctx) { + io_sq_thread_stop(ctx); + if (ctx->sqo_wq) { destroy_workqueue(ctx->sqo_wq); ctx->sqo_wq = NULL; @@ -1583,13 +1770,47 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg, return ret; } -static int io_sq_offload_start(struct io_ring_ctx *ctx) +static int io_sq_offload_start(struct io_ring_ctx *ctx, + struct io_uring_params *p) { int ret; + init_waitqueue_head(&ctx->sqo_wait); mmgrab(current->mm); ctx->sqo_mm = current->mm; + ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle); + if (!ctx->sq_thread_idle) + ctx->sq_thread_idle = HZ; + + ret = -EINVAL; + if (!cpu_possible(p->sq_thread_cpu)) + goto err; + + if (ctx->flags & IORING_SETUP_SQPOLL) { + if (p->flags & IORING_SETUP_SQ_AFF) { + int cpu; + + cpu = array_index_nospec(p->sq_thread_cpu, NR_CPUS); + ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread, + ctx, cpu, + "io_uring-sq"); + } else { + ctx->sqo_thread = kthread_create(io_sq_thread, ctx, + "io_uring-sq"); + } + if (IS_ERR(ctx->sqo_thread)) { + ret = PTR_ERR(ctx->sqo_thread); + ctx->sqo_thread = NULL; + goto err; + } + wake_up_process(ctx->sqo_thread); + } else if (p->flags & IORING_SETUP_SQ_AFF) { + /* Can't have SQ_AFF without SQPOLL */ + ret = -EINVAL; + goto err; + } + /* Do QD, or 2 * CPUS, whatever is smallest */ ctx->sqo_wq = alloc_workqueue("io_ring-wq", WQ_UNBOUND | WQ_FREEZABLE, min(ctx->sq_entries - 1, 2 * num_online_cpus())); @@ -1600,6 +1821,7 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx) return 0; err: + io_sq_thread_stop(ctx); mmdrop(ctx->sqo_mm); ctx->sqo_mm = NULL; return ret; @@ -1959,7 +2181,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, int submitted = 0; struct fd f; - if (flags & ~IORING_ENTER_GETEVENTS) + if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP)) return -EINVAL; f = fdget(fd); @@ -1975,6 +2197,18 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, if (!percpu_ref_tryget(&ctx->refs)) goto out_fput; + /* + * For SQ polling, the thread will do all submissions and completions. + * Just return the requested submit count, and wake the thread if + * we were asked to. + */ + if (ctx->flags & IORING_SETUP_SQPOLL) { + if (flags & IORING_ENTER_SQ_WAKEUP) + wake_up(&ctx->sqo_wait); + submitted = to_submit; + goto out_ctx; + } + ret = 0; if (to_submit) { to_submit = min(to_submit, ctx->sq_entries); @@ -2156,7 +2390,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p) if (ret) goto err; - ret = io_sq_offload_start(ctx); + ret = io_sq_offload_start(ctx, p); if (ret) goto err; @@ -2204,7 +2438,8 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params) return -EINVAL; } - if (p.flags & ~IORING_SETUP_IOPOLL) + if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL | + IORING_SETUP_SQ_AFF)) return -EINVAL; ret = io_uring_create(entries, &p); |