Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/fs/io_uring.c b/fs/io_uring.c
new file mode 100644
index 0000000..cbe8dab
--- /dev/null
+++ b/fs/io_uring.c
@@ -0,0 +1,4040 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Shared application/kernel submission and completion ring pairs, for
+ * supporting fast/efficient IO.
+ *
+ * A note on the read/write ordering memory barriers that are matched between
+ * the application and kernel side.
+ *
+ * After the application reads the CQ ring tail, it must use an
+ * appropriate smp_rmb() to pair with the smp_wmb() the kernel uses
+ * before writing the tail (using smp_load_acquire to read the tail will
+ * do). It also needs a smp_mb() before updating CQ head (ordering the
+ * entry load(s) with the head store), pairing with an implicit barrier
+ * through a control-dependency in io_get_cqring (smp_store_release to
+ * store head will do). Failure to do so could lead to reading invalid
+ * CQ entries.
+ *
+ * Likewise, the application must use an appropriate smp_wmb() before
+ * writing the SQ tail (ordering SQ entry stores with the tail store),
+ * which pairs with smp_load_acquire in io_get_sqring (smp_store_release
+ * to store the tail will do). And it needs a barrier ordering the SQ
+ * head load before writing new SQ entries (smp_load_acquire to read
+ * head will do).
+ *
+ * When using the SQ poll thread (IORING_SETUP_SQPOLL), the application
+ * needs to check the SQ flags for IORING_SQ_NEED_WAKEUP *after*
+ * updating the SQ tail; a full memory barrier smp_mb() is needed
+ * between.
+ *
+ * Also see the examples in the liburing library:
+ *
+ * git://git.kernel.dk/liburing
+ *
+ * io_uring also uses READ/WRITE_ONCE() for _any_ store or load that happens
+ * from data shared between the kernel and application. This is done both
+ * for ordering purposes, but also to ensure that once a value is loaded from
+ * data that the application could potentially modify, it remains stable.
+ *
+ * Copyright (C) 2018-2019 Jens Axboe
+ * Copyright (c) 2018-2019 Christoph Hellwig
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <linux/refcount.h>
+#include <linux/uio.h>
+
+#include <linux/sched/signal.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/mmu_context.h>
+#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>
+#include <net/sock.h>
+#include <net/af_unix.h>
+#include <net/scm.h>
+#include <linux/anon_inodes.h>
+#include <linux/sched/mm.h>
+#include <linux/uaccess.h>
+#include <linux/nospec.h>
+#include <linux/sizes.h>
+#include <linux/hugetlb.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "internal.h"
+
+#define IORING_MAX_ENTRIES 32768
+#define IORING_MAX_FIXED_FILES 1024
+
+struct io_uring {
+ u32 head ____cacheline_aligned_in_smp;
+ u32 tail ____cacheline_aligned_in_smp;
+};
+
+/*
+ * This data is shared with the application through the mmap at offsets
+ * IORING_OFF_SQ_RING and IORING_OFF_CQ_RING.
+ *
+ * The offsets to the member fields are published through struct
+ * io_sqring_offsets when calling io_uring_setup.
+ */
+struct io_rings {
+ /*
+ * Head and tail offsets into the ring; the offsets need to be
+ * masked to get valid indices.
+ *
+ * The kernel controls head of the sq ring and the tail of the cq ring,
+ * and the application controls tail of the sq ring and the head of the
+ * cq ring.
+ */
+ struct io_uring sq, cq;
+ /*
+ * Bitmasks to apply to head and tail offsets (constant, equals
+ * ring_entries - 1)
+ */
+ u32 sq_ring_mask, cq_ring_mask;
+ /* Ring sizes (constant, power of 2) */
+ u32 sq_ring_entries, cq_ring_entries;
+ /*
+ * Number of invalid entries dropped by the kernel due to
+ * invalid index stored in array
+ *
+ * Written by the kernel, shouldn't be modified by the
+ * application (i.e. get number of "new events" by comparing to
+ * cached value).
+ *
+ * After a new SQ head value was read by the application this
+ * counter includes all submissions that were dropped reaching
+ * the new SQ head (and possibly more).
+ */
+ u32 sq_dropped;
+ /*
+ * Runtime flags
+ *
+ * Written by the kernel, shouldn't be modified by the
+ * application.
+ *
+ * The application needs a full memory barrier before checking
+ * for IORING_SQ_NEED_WAKEUP after updating the sq tail.
+ */
+ u32 sq_flags;
+ /*
+ * Number of completion events lost because the queue was full;
+ * this should be avoided by the application by making sure
+ * there are not more requests pending thatn there is space in
+ * the completion queue.
+ *
+ * Written by the kernel, shouldn't be modified by the
+ * application (i.e. get number of "new events" by comparing to
+ * cached value).
+ *
+ * As completion events come in out of order this counter is not
+ * ordered with any other data.
+ */
+ u32 cq_overflow;
+ /*
+ * Ring buffer of completion events.
+ *
+ * The kernel writes completion events fresh every time they are
+ * produced, so the application is allowed to modify pending
+ * entries.
+ */
+ struct io_uring_cqe cqes[] ____cacheline_aligned_in_smp;
+};
+
+struct io_mapped_ubuf {
+ u64 ubuf;
+ size_t len;
+ struct bio_vec *bvec;
+ unsigned int nr_bvecs;
+};
+
+struct async_list {
+ spinlock_t lock;
+ atomic_t cnt;
+ struct list_head list;
+
+ struct file *file;
+ off_t io_start;
+ size_t io_len;
+};
+
+struct io_ring_ctx {
+ struct {
+ struct percpu_ref refs;
+ } ____cacheline_aligned_in_smp;
+
+ struct {
+ unsigned int flags;
+ bool compat;
+ bool account_mem;
+
+ /*
+ * Ring buffer of indices into array of io_uring_sqe, which is
+ * mmapped by the application using the IORING_OFF_SQES offset.
+ *
+ * This indirection could e.g. be used to assign fixed
+ * io_uring_sqe entries to operations and only submit them to
+ * the queue when needed.
+ *
+ * The kernel modifies neither the indices array nor the entries
+ * array.
+ */
+ u32 *sq_array;
+ unsigned cached_sq_head;
+ unsigned sq_entries;
+ unsigned sq_mask;
+ unsigned sq_thread_idle;
+ unsigned cached_sq_dropped;
+ struct io_uring_sqe *sq_sqes;
+
+ struct list_head defer_list;
+ struct list_head timeout_list;
+ } ____cacheline_aligned_in_smp;
+
+ /* IO offload */
+ struct workqueue_struct *sqo_wq[2];
+ struct task_struct *sqo_thread; /* if using sq thread polling */
+ struct mm_struct *sqo_mm;
+ wait_queue_head_t sqo_wait;
+ struct completion sqo_thread_started;
+
+ struct {
+ unsigned cached_cq_tail;
+ atomic_t cached_cq_overflow;
+ unsigned cq_entries;
+ unsigned cq_mask;
+ struct wait_queue_head cq_wait;
+ struct fasync_struct *cq_fasync;
+ struct eventfd_ctx *cq_ev_fd;
+ atomic_t cq_timeouts;
+ } ____cacheline_aligned_in_smp;
+
+ struct io_rings *rings;
+
+ /*
+ * If used, fixed file set. Writers must ensure that ->refs is dead,
+ * readers must ensure that ->refs is alive as long as the file* is
+ * used. Only updated through io_uring_register(2).
+ */
+ struct file **user_files;
+ unsigned nr_user_files;
+
+ /* if used, fixed mapped user buffers */
+ unsigned nr_user_bufs;
+ struct io_mapped_ubuf *user_bufs;
+
+ struct user_struct *user;
+
+ struct cred *creds;
+
+ struct completion ctx_done;
+
+ struct {
+ struct mutex uring_lock;
+ wait_queue_head_t wait;
+ } ____cacheline_aligned_in_smp;
+
+ struct {
+ spinlock_t completion_lock;
+ bool poll_multi_file;
+ /*
+ * ->poll_list is protected by the ctx->uring_lock for
+ * io_uring instances that don't use IORING_SETUP_SQPOLL.
+ * For SQPOLL, only the single threaded io_sq_thread() will
+ * manipulate the list, hence no extra locking is needed there.
+ */
+ struct list_head poll_list;
+ struct list_head cancel_list;
+ } ____cacheline_aligned_in_smp;
+
+ struct async_list pending_async[2];
+
+#if defined(CONFIG_UNIX)
+ struct socket *ring_sock;
+#endif
+};
+
+struct sqe_submit {
+ const struct io_uring_sqe *sqe;
+ unsigned short index;
+ u32 sequence;
+ bool has_user;
+ bool needs_lock;
+ bool needs_fixed_file;
+};
+
+/*
+ * First field must be the file pointer in all the
+ * iocb unions! See also 'struct kiocb' in <linux/fs.h>
+ */
+struct io_poll_iocb {
+ struct file *file;
+ struct wait_queue_head *head;
+ __poll_t events;
+ bool done;
+ bool canceled;
+ struct wait_queue_entry wait;
+};
+
+struct io_timeout {
+ struct file *file;
+ struct hrtimer timer;
+};
+
+/*
+ * NOTE! Each of the iocb union members has the file pointer
+ * as the first entry in their struct definition. So you can
+ * access the file pointer through any of the sub-structs,
+ * or directly as just 'ki_filp' in this struct.
+ */
+struct io_kiocb {
+ union {
+ struct file *file;
+ struct kiocb rw;
+ struct io_poll_iocb poll;
+ struct io_timeout timeout;
+ };
+
+ struct sqe_submit submit;
+
+ struct io_ring_ctx *ctx;
+ struct list_head list;
+ struct list_head link_list;
+ unsigned int flags;
+ refcount_t refs;
+#define REQ_F_NOWAIT 1 /* must not punt to workers */
+#define REQ_F_IOPOLL_COMPLETED 2 /* polled IO has completed */
+#define REQ_F_FIXED_FILE 4 /* ctx owns file */
+#define REQ_F_SEQ_PREV 8 /* sequential with previous */
+#define REQ_F_IO_DRAIN 16 /* drain existing IO first */
+#define REQ_F_IO_DRAINED 32 /* drain done */
+#define REQ_F_LINK 64 /* linked sqes */
+#define REQ_F_LINK_DONE 128 /* linked sqes done */
+#define REQ_F_FAIL_LINK 256 /* fail rest of links */
+#define REQ_F_SHADOW_DRAIN 512 /* link-drain shadow req */
+#define REQ_F_TIMEOUT 1024 /* timeout request */
+#define REQ_F_ISREG 2048 /* regular file */
+#define REQ_F_MUST_PUNT 4096 /* must be punted even for NONBLOCK */
+#define REQ_F_TIMEOUT_NOSEQ 8192 /* no timeout sequence */
+ u64 user_data;
+ u32 result;
+ u32 sequence;
+
+ struct work_struct work;
+};
+
+#define IO_PLUG_THRESHOLD 2
+#define IO_IOPOLL_BATCH 8
+
+struct io_submit_state {
+ struct blk_plug plug;
+
+ /*
+ * io_kiocb alloc cache
+ */
+ void *reqs[IO_IOPOLL_BATCH];
+ unsigned int free_reqs;
+ unsigned int cur_req;
+
+ /*
+ * File reference cache
+ */
+ struct file *file;
+ unsigned int fd;
+ unsigned int has_refs;
+ unsigned int used_refs;
+ unsigned int ios_left;
+};
+
+static void io_sq_wq_submit_work(struct work_struct *work);
+static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
+ long res);
+static void __io_free_req(struct io_kiocb *req);
+
+static struct kmem_cache *req_cachep;
+
+static const struct file_operations io_uring_fops;
+
+struct sock *io_uring_get_socket(struct file *file)
+{
+#if defined(CONFIG_UNIX)
+ if (file->f_op == &io_uring_fops) {
+ struct io_ring_ctx *ctx = file->private_data;
+
+ return ctx->ring_sock->sk;
+ }
+#endif
+ return NULL;
+}
+EXPORT_SYMBOL(io_uring_get_socket);
+
+static void io_ring_ctx_ref_free(struct percpu_ref *ref)
+{
+ struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
+
+ complete(&ctx->ctx_done);
+}
+
+static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
+{
+ struct io_ring_ctx *ctx;
+ int i;
+
+ ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+ if (!ctx)
+ return NULL;
+
+ if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
+ PERCPU_REF_ALLOW_REINIT, GFP_KERNEL)) {
+ kfree(ctx);
+ return NULL;
+ }
+
+ ctx->flags = p->flags;
+ init_waitqueue_head(&ctx->cq_wait);
+ init_completion(&ctx->ctx_done);
+ init_completion(&ctx->sqo_thread_started);
+ mutex_init(&ctx->uring_lock);
+ init_waitqueue_head(&ctx->wait);
+ for (i = 0; i < ARRAY_SIZE(ctx->pending_async); i++) {
+ spin_lock_init(&ctx->pending_async[i].lock);
+ INIT_LIST_HEAD(&ctx->pending_async[i].list);
+ atomic_set(&ctx->pending_async[i].cnt, 0);
+ }
+ spin_lock_init(&ctx->completion_lock);
+ INIT_LIST_HEAD(&ctx->poll_list);
+ INIT_LIST_HEAD(&ctx->cancel_list);
+ INIT_LIST_HEAD(&ctx->defer_list);
+ INIT_LIST_HEAD(&ctx->timeout_list);
+ return ctx;
+}
+
+static inline bool __io_sequence_defer(struct io_ring_ctx *ctx,
+ struct io_kiocb *req)
+{
+ return req->sequence != ctx->cached_cq_tail + ctx->cached_sq_dropped
+ + atomic_read(&ctx->cached_cq_overflow);
+}
+
+static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
+ struct io_kiocb *req)
+{
+ if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
+ return false;
+
+ return __io_sequence_defer(ctx, req);
+}
+
+static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
+{
+ struct io_kiocb *req;
+
+ req = list_first_entry_or_null(&ctx->defer_list, struct io_kiocb, list);
+ if (req && !io_sequence_defer(ctx, req)) {
+ list_del_init(&req->list);
+ return req;
+ }
+
+ return NULL;
+}
+
+static struct io_kiocb *io_get_timeout_req(struct io_ring_ctx *ctx)
+{
+ struct io_kiocb *req;
+
+ req = list_first_entry_or_null(&ctx->timeout_list, struct io_kiocb, list);
+ if (req) {
+ if (req->flags & REQ_F_TIMEOUT_NOSEQ)
+ return NULL;
+ if (!__io_sequence_defer(ctx, req)) {
+ list_del_init(&req->list);
+ return req;
+ }
+ }
+
+ return NULL;
+}
+
+static void __io_commit_cqring(struct io_ring_ctx *ctx)
+{
+ struct io_rings *rings = ctx->rings;
+
+ if (ctx->cached_cq_tail != READ_ONCE(rings->cq.tail)) {
+ /* order cqe stores with ring update */
+ smp_store_release(&rings->cq.tail, ctx->cached_cq_tail);
+
+ if (wq_has_sleeper(&ctx->cq_wait)) {
+ wake_up_interruptible(&ctx->cq_wait);
+ kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
+ }
+ }
+}
+
+static inline void io_queue_async_work(struct io_ring_ctx *ctx,
+ struct io_kiocb *req)
+{
+ int rw = 0;
+
+ if (req->submit.sqe) {
+ switch (req->submit.sqe->opcode) {
+ case IORING_OP_WRITEV:
+ case IORING_OP_WRITE_FIXED:
+ rw = !(req->rw.ki_flags & IOCB_DIRECT);
+ break;
+ }
+ }
+
+ queue_work(ctx->sqo_wq[rw], &req->work);
+}
+
+static void io_kill_timeout(struct io_kiocb *req)
+{
+ int ret;
+
+ ret = hrtimer_try_to_cancel(&req->timeout.timer);
+ if (ret != -1) {
+ atomic_inc(&req->ctx->cq_timeouts);
+ list_del(&req->list);
+ io_cqring_fill_event(req->ctx, req->user_data, 0);
+ __io_free_req(req);
+ }
+}
+
+static void io_kill_timeouts(struct io_ring_ctx *ctx)
+{
+ struct io_kiocb *req, *tmp;
+
+ spin_lock_irq(&ctx->completion_lock);
+ list_for_each_entry_safe(req, tmp, &ctx->timeout_list, list)
+ io_kill_timeout(req);
+ spin_unlock_irq(&ctx->completion_lock);
+}
+
+static void io_commit_cqring(struct io_ring_ctx *ctx)
+{
+ struct io_kiocb *req;
+
+ while ((req = io_get_timeout_req(ctx)) != NULL)
+ io_kill_timeout(req);
+
+ __io_commit_cqring(ctx);
+
+ while ((req = io_get_deferred_req(ctx)) != NULL) {
+ if (req->flags & REQ_F_SHADOW_DRAIN) {
+ /* Just for drain, free it. */
+ __io_free_req(req);
+ continue;
+ }
+ req->flags |= REQ_F_IO_DRAINED;
+ io_queue_async_work(ctx, req);
+ }
+}
+
+static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
+{
+ struct io_rings *rings = ctx->rings;
+ unsigned tail;
+
+ tail = ctx->cached_cq_tail;
+ /*
+ * writes to the cq entry need to come after reading head; the
+ * control dependency is enough as we're using WRITE_ONCE to
+ * fill the cq entry
+ */
+ if (tail - READ_ONCE(rings->cq.head) == rings->cq_ring_entries)
+ return NULL;
+
+ ctx->cached_cq_tail++;
+ return &rings->cqes[tail & ctx->cq_mask];
+}
+
+static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
+ long res)
+{
+ struct io_uring_cqe *cqe;
+
+ /*
+ * If we can't get a cq entry, userspace overflowed the
+ * submission (by quite a lot). Increment the overflow count in
+ * the ring.
+ */
+ cqe = io_get_cqring(ctx);
+ if (cqe) {
+ WRITE_ONCE(cqe->user_data, ki_user_data);
+ WRITE_ONCE(cqe->res, res);
+ WRITE_ONCE(cqe->flags, 0);
+ } else {
+ WRITE_ONCE(ctx->rings->cq_overflow,
+ atomic_inc_return(&ctx->cached_cq_overflow));
+ }
+}
+
+static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
+{
+ if (waitqueue_active(&ctx->wait))
+ wake_up(&ctx->wait);
+ if (waitqueue_active(&ctx->sqo_wait))
+ wake_up(&ctx->sqo_wait);
+ if (ctx->cq_ev_fd)
+ eventfd_signal(ctx->cq_ev_fd, 1);
+}
+
+static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 user_data,
+ long res)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&ctx->completion_lock, flags);
+ io_cqring_fill_event(ctx, user_data, res);
+ io_commit_cqring(ctx);
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+ io_cqring_ev_posted(ctx);
+}
+
+static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
+ struct io_submit_state *state)
+{
+ gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
+ struct io_kiocb *req;
+
+ if (!percpu_ref_tryget(&ctx->refs))
+ return NULL;
+
+ if (!state) {
+ req = kmem_cache_alloc(req_cachep, gfp);
+ if (unlikely(!req))
+ goto out;
+ } else if (!state->free_reqs) {
+ size_t sz;
+ int ret;
+
+ sz = min_t(size_t, state->ios_left, ARRAY_SIZE(state->reqs));
+ ret = kmem_cache_alloc_bulk(req_cachep, gfp, sz, state->reqs);
+
+ /*
+ * Bulk alloc is all-or-nothing. If we fail to get a batch,
+ * retry single alloc to be on the safe side.
+ */
+ if (unlikely(ret <= 0)) {
+ state->reqs[0] = kmem_cache_alloc(req_cachep, gfp);
+ if (!state->reqs[0])
+ goto out;
+ ret = 1;
+ }
+ state->free_reqs = ret - 1;
+ state->cur_req = 1;
+ req = state->reqs[0];
+ } else {
+ req = state->reqs[state->cur_req];
+ state->free_reqs--;
+ state->cur_req++;
+ }
+
+ req->file = NULL;
+ req->ctx = ctx;
+ req->flags = 0;
+ /* one is dropped after submission, the other at completion */
+ refcount_set(&req->refs, 2);
+ req->result = 0;
+ return req;
+out:
+ percpu_ref_put(&ctx->refs);
+ return NULL;
+}
+
+static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
+{
+ if (*nr) {
+ kmem_cache_free_bulk(req_cachep, *nr, reqs);
+ percpu_ref_put_many(&ctx->refs, *nr);
+ *nr = 0;
+ }
+}
+
+static void __io_free_req(struct io_kiocb *req)
+{
+ if (req->file && !(req->flags & REQ_F_FIXED_FILE))
+ fput(req->file);
+ percpu_ref_put(&req->ctx->refs);
+ kmem_cache_free(req_cachep, req);
+}
+
+static void io_req_link_next(struct io_kiocb *req)
+{
+ struct io_kiocb *nxt;
+
+ /*
+ * The list should never be empty when we are called here. But could
+ * potentially happen if the chain is messed up, check to be on the
+ * safe side.
+ */
+ nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, list);
+ if (nxt) {
+ list_del(&nxt->list);
+ if (!list_empty(&req->link_list)) {
+ INIT_LIST_HEAD(&nxt->link_list);
+ list_splice(&req->link_list, &nxt->link_list);
+ nxt->flags |= REQ_F_LINK;
+ }
+
+ nxt->flags |= REQ_F_LINK_DONE;
+ INIT_WORK(&nxt->work, io_sq_wq_submit_work);
+ io_queue_async_work(req->ctx, nxt);
+ }
+}
+
+/*
+ * Called if REQ_F_LINK is set, and we fail the head request
+ */
+static void io_fail_links(struct io_kiocb *req)
+{
+ struct io_kiocb *link;
+
+ while (!list_empty(&req->link_list)) {
+ link = list_first_entry(&req->link_list, struct io_kiocb, list);
+ list_del(&link->list);
+
+ io_cqring_add_event(req->ctx, link->user_data, -ECANCELED);
+ __io_free_req(link);
+ }
+}
+
+static void io_free_req(struct io_kiocb *req)
+{
+ /*
+ * 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
+ * dependencies to the next request. In case of failure, fail the rest
+ * of the chain.
+ */
+ if (req->flags & REQ_F_LINK) {
+ if (req->flags & REQ_F_FAIL_LINK)
+ io_fail_links(req);
+ else
+ io_req_link_next(req);
+ }
+
+ __io_free_req(req);
+}
+
+static void io_put_req(struct io_kiocb *req)
+{
+ if (refcount_dec_and_test(&req->refs))
+ io_free_req(req);
+}
+
+static unsigned io_cqring_events(struct io_rings *rings)
+{
+ /* See comment at the top of this file */
+ smp_rmb();
+ return READ_ONCE(rings->cq.tail) - READ_ONCE(rings->cq.head);
+}
+
+static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
+{
+ struct io_rings *rings = ctx->rings;
+
+ /* make sure SQ entry isn't read before tail */
+ return smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
+}
+
+/*
+ * Find and free completed poll iocbs
+ */
+static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
+ struct list_head *done)
+{
+ void *reqs[IO_IOPOLL_BATCH];
+ struct io_kiocb *req;
+ int to_free;
+
+ to_free = 0;
+ while (!list_empty(done)) {
+ req = list_first_entry(done, struct io_kiocb, list);
+ list_del(&req->list);
+
+ io_cqring_fill_event(ctx, req->user_data, req->result);
+ (*nr_events)++;
+
+ if (refcount_dec_and_test(&req->refs)) {
+ /* If we're not using fixed files, we have to pair the
+ * completion part with the file put. Use regular
+ * completions for those, only batch free for fixed
+ * file and non-linked commands.
+ */
+ if ((req->flags & (REQ_F_FIXED_FILE|REQ_F_LINK)) ==
+ REQ_F_FIXED_FILE) {
+ reqs[to_free++] = req;
+ if (to_free == ARRAY_SIZE(reqs))
+ io_free_req_many(ctx, reqs, &to_free);
+ } else {
+ io_free_req(req);
+ }
+ }
+ }
+
+ io_commit_cqring(ctx);
+ io_free_req_many(ctx, reqs, &to_free);
+}
+
+static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
+ long min)
+{
+ struct io_kiocb *req, *tmp;
+ LIST_HEAD(done);
+ bool spin;
+ int ret;
+
+ /*
+ * Only spin for completions if we don't have multiple devices hanging
+ * off our complete list, and we're under the requested amount.
+ */
+ spin = !ctx->poll_multi_file && *nr_events < min;
+
+ ret = 0;
+ list_for_each_entry_safe(req, tmp, &ctx->poll_list, list) {
+ struct kiocb *kiocb = &req->rw;
+
+ /*
+ * Move completed entries to our local list. If we find a
+ * request that requires polling, break out and complete
+ * the done list first, if we have entries there.
+ */
+ if (req->flags & REQ_F_IOPOLL_COMPLETED) {
+ list_move_tail(&req->list, &done);
+ continue;
+ }
+ if (!list_empty(&done))
+ break;
+
+ ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
+ if (ret < 0)
+ break;
+
+ if (ret && spin)
+ spin = false;
+ ret = 0;
+ }
+
+ if (!list_empty(&done))
+ io_iopoll_complete(ctx, nr_events, &done);
+
+ return ret;
+}
+
+/*
+ * Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
+ * non-spinning poll check - we'll still enter the driver poll loop, but only
+ * as a non-spinning completion check.
+ */
+static int io_iopoll_getevents(struct io_ring_ctx *ctx, unsigned int *nr_events,
+ long min)
+{
+ while (!list_empty(&ctx->poll_list) && !need_resched()) {
+ int ret;
+
+ ret = io_do_iopoll(ctx, nr_events, min);
+ if (ret < 0)
+ return ret;
+ if (!min || *nr_events >= min)
+ return 0;
+ }
+
+ return 1;
+}
+
+/*
+ * We can't just wait for polled events to come to us, we have to actively
+ * find and complete them.
+ */
+static void io_iopoll_reap_events(struct io_ring_ctx *ctx)
+{
+ if (!(ctx->flags & IORING_SETUP_IOPOLL))
+ return;
+
+ mutex_lock(&ctx->uring_lock);
+ while (!list_empty(&ctx->poll_list)) {
+ unsigned int nr_events = 0;
+
+ io_iopoll_getevents(ctx, &nr_events, 1);
+
+ /*
+ * Ensure we allow local-to-the-cpu processing to take place,
+ * in this case we need to ensure that we reap all events.
+ */
+ cond_resched();
+ }
+ mutex_unlock(&ctx->uring_lock);
+}
+
+static int __io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
+ long min)
+{
+ int iters = 0, ret = 0;
+
+ do {
+ int tmin = 0;
+
+ /*
+ * Don't enter poll loop if we already have events pending.
+ * If we do, we can potentially be spinning for commands that
+ * already triggered a CQE (eg in error).
+ */
+ if (io_cqring_events(ctx->rings))
+ break;
+
+ /*
+ * If a submit got punted to a workqueue, we can have the
+ * application entering polling for a command before it gets
+ * issued. That app will hold the uring_lock for the duration
+ * of the poll right here, so we need to take a breather every
+ * now and then to ensure that the issue has a chance to add
+ * the poll to the issued list. Otherwise we can spin here
+ * forever, while the workqueue is stuck trying to acquire the
+ * very same mutex.
+ */
+ if (!(++iters & 7)) {
+ mutex_unlock(&ctx->uring_lock);
+ mutex_lock(&ctx->uring_lock);
+ }
+
+ if (*nr_events < min)
+ tmin = min - *nr_events;
+
+ ret = io_iopoll_getevents(ctx, nr_events, tmin);
+ if (ret <= 0)
+ break;
+ ret = 0;
+ } while (min && !*nr_events && !need_resched());
+
+ return ret;
+}
+
+static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
+ long min)
+{
+ int ret;
+
+ /*
+ * 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);
+ ret = __io_iopoll_check(ctx, nr_events, min);
+ mutex_unlock(&ctx->uring_lock);
+ return ret;
+}
+
+static void kiocb_end_write(struct io_kiocb *req)
+{
+ /*
+ * Tell lockdep we inherited freeze protection from submission
+ * thread.
+ */
+ if (req->flags & REQ_F_ISREG) {
+ struct inode *inode = file_inode(req->file);
+
+ __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+ }
+ file_end_write(req->file);
+}
+
+static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
+{
+ struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
+
+ if (kiocb->ki_flags & IOCB_WRITE)
+ kiocb_end_write(req);
+
+ 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_iopoll(struct kiocb *kiocb, long res, long res2)
+{
+ struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
+
+ if (kiocb->ki_flags & IOCB_WRITE)
+ kiocb_end_write(req);
+
+ if ((req->flags & REQ_F_LINK) && res != req->result)
+ req->flags |= REQ_F_FAIL_LINK;
+ req->result = res;
+ if (res != -EAGAIN)
+ req->flags |= REQ_F_IOPOLL_COMPLETED;
+}
+
+/*
+ * 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_iopoll_getevents() thread before the issuer is done
+ * accessing the kiocb cookie.
+ */
+static void io_iopoll_req_issued(struct io_kiocb *req)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+
+ /*
+ * Track whether we have multiple files in our lists. This will impact
+ * how we do polling eventually, not spinning if we're on potentially
+ * different devices.
+ */
+ if (list_empty(&ctx->poll_list)) {
+ ctx->poll_multi_file = false;
+ } else if (!ctx->poll_multi_file) {
+ struct io_kiocb *list_req;
+
+ list_req = list_first_entry(&ctx->poll_list, struct io_kiocb,
+ list);
+ if (list_req->rw.ki_filp != req->rw.ki_filp)
+ ctx->poll_multi_file = true;
+ }
+
+ /*
+ * For fast devices, IO may have already completed. If it has, add
+ * it to the front so we find it first.
+ */
+ if (req->flags & REQ_F_IOPOLL_COMPLETED)
+ list_add(&req->list, &ctx->poll_list);
+ else
+ list_add_tail(&req->list, &ctx->poll_list);
+}
+
+static void io_file_put(struct io_submit_state *state)
+{
+ if (state->file) {
+ int diff = state->has_refs - state->used_refs;
+
+ if (diff)
+ fput_many(state->file, diff);
+ state->file = NULL;
+ }
+}
+
+/*
+ * Get as many references to a file as we have IOs left in this submission,
+ * assuming most submissions are for one file, or at least that each file
+ * has more than one submission.
+ */
+static struct file *io_file_get(struct io_submit_state *state, int fd)
+{
+ if (!state)
+ return fget(fd);
+
+ if (state->file) {
+ if (state->fd == fd) {
+ state->used_refs++;
+ state->ios_left--;
+ return state->file;
+ }
+ io_file_put(state);
+ }
+ state->file = fget_many(fd, state->ios_left);
+ if (!state->file)
+ return NULL;
+
+ state->fd = fd;
+ state->has_refs = state->ios_left;
+ state->used_refs = 1;
+ state->ios_left--;
+ return state->file;
+}
+
+/*
+ * If we tracked the file through the SCM inflight mechanism, we could support
+ * any file. For now, just ensure that anything potentially problematic is done
+ * inline.
+ */
+static bool io_file_supports_async(struct file *file)
+{
+ umode_t mode = file_inode(file)->i_mode;
+
+ if (S_ISBLK(mode) || S_ISCHR(mode))
+ return true;
+ if (S_ISREG(mode) && file->f_op != &io_uring_fops)
+ return true;
+
+ return false;
+}
+
+static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
+ bool force_nonblock)
+{
+ const struct io_uring_sqe *sqe = s->sqe;
+ struct io_ring_ctx *ctx = req->ctx;
+ struct kiocb *kiocb = &req->rw;
+ unsigned ioprio;
+ int ret;
+
+ if (!req->file)
+ return -EBADF;
+
+ if (S_ISREG(file_inode(req->file)->i_mode))
+ req->flags |= REQ_F_ISREG;
+
+ /*
+ * If the file doesn't support async, mark it as REQ_F_MUST_PUNT so
+ * we know to async punt it even if it was opened O_NONBLOCK
+ */
+ if (force_nonblock && !io_file_supports_async(req->file)) {
+ req->flags |= REQ_F_MUST_PUNT;
+ return -EAGAIN;
+ }
+
+ kiocb->ki_pos = READ_ONCE(sqe->off);
+ kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
+ kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
+
+ ioprio = READ_ONCE(sqe->ioprio);
+ if (ioprio) {
+ ret = ioprio_check_cap(ioprio);
+ if (ret)
+ return ret;
+
+ kiocb->ki_ioprio = ioprio;
+ } else
+ kiocb->ki_ioprio = get_current_ioprio();
+
+ ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
+ if (unlikely(ret))
+ return ret;
+
+ /* don't allow async punt if RWF_NOWAIT was requested */
+ if ((kiocb->ki_flags & IOCB_NOWAIT) ||
+ (req->file->f_flags & O_NONBLOCK))
+ req->flags |= REQ_F_NOWAIT;
+
+ if (force_nonblock)
+ kiocb->ki_flags |= IOCB_NOWAIT;
+
+ if (ctx->flags & IORING_SETUP_IOPOLL) {
+ if (!(kiocb->ki_flags & IOCB_DIRECT) ||
+ !kiocb->ki_filp->f_op->iopoll)
+ return -EOPNOTSUPP;
+
+ kiocb->ki_flags |= IOCB_HIPRI;
+ kiocb->ki_complete = io_complete_rw_iopoll;
+ req->result = 0;
+ } else {
+ if (kiocb->ki_flags & IOCB_HIPRI)
+ return -EINVAL;
+ kiocb->ki_complete = io_complete_rw;
+ }
+ return 0;
+}
+
+static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
+{
+ switch (ret) {
+ case -EIOCBQUEUED:
+ break;
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
+ case -ERESTARTNOHAND:
+ case -ERESTART_RESTARTBLOCK:
+ /*
+ * We can't just restart the syscall, since previously
+ * submitted sqes may already be in progress. Just fail this
+ * IO with EINTR.
+ */
+ ret = -EINTR;
+ /* fall through */
+ default:
+ kiocb->ki_complete(kiocb, ret, 0);
+ }
+}
+
+static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
+ const struct io_uring_sqe *sqe,
+ struct iov_iter *iter)
+{
+ size_t len = READ_ONCE(sqe->len);
+ struct io_mapped_ubuf *imu;
+ unsigned index, buf_index;
+ size_t offset;
+ u64 buf_addr;
+
+ /* attempt to use fixed buffers without having provided iovecs */
+ if (unlikely(!ctx->user_bufs))
+ return -EFAULT;
+
+ buf_index = READ_ONCE(sqe->buf_index);
+ if (unlikely(buf_index >= ctx->nr_user_bufs))
+ return -EFAULT;
+
+ index = array_index_nospec(buf_index, ctx->nr_user_bufs);
+ imu = &ctx->user_bufs[index];
+ buf_addr = READ_ONCE(sqe->addr);
+
+ /* overflow */
+ if (buf_addr + len < buf_addr)
+ return -EFAULT;
+ /* not inside the mapped region */
+ if (buf_addr < imu->ubuf || buf_addr + len > imu->ubuf + imu->len)
+ return -EFAULT;
+
+ /*
+ * May not be a start of buffer, set size appropriately
+ * and advance us to the beginning.
+ */
+ offset = buf_addr - imu->ubuf;
+ iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
+
+ if (offset) {
+ /*
+ * Don't use iov_iter_advance() here, as it's really slow for
+ * using the latter parts of a big fixed buffer - it iterates
+ * over each segment manually. We can cheat a bit here, because
+ * we know that:
+ *
+ * 1) it's a BVEC iter, we set it up
+ * 2) all bvecs are PAGE_SIZE in size, except potentially the
+ * first and last bvec
+ *
+ * So just find our index, and adjust the iterator afterwards.
+ * If the offset is within the first bvec (or the whole first
+ * bvec, just use iov_iter_advance(). This makes it easier
+ * since we can just skip the first segment, which may not
+ * be PAGE_SIZE aligned.
+ */
+ const struct bio_vec *bvec = imu->bvec;
+
+ if (offset <= bvec->bv_len) {
+ iov_iter_advance(iter, offset);
+ } else {
+ unsigned long seg_skip;
+
+ /* skip first vec */
+ offset -= bvec->bv_len;
+ seg_skip = 1 + (offset >> PAGE_SHIFT);
+
+ iter->bvec = bvec + seg_skip;
+ iter->nr_segs -= seg_skip;
+ iter->count -= bvec->bv_len + offset;
+ iter->iov_offset = offset & ~PAGE_MASK;
+ }
+ }
+
+ return len;
+}
+
+static ssize_t io_import_iovec(struct io_ring_ctx *ctx, int rw,
+ const struct sqe_submit *s, struct iovec **iovec,
+ struct iov_iter *iter)
+{
+ const struct io_uring_sqe *sqe = s->sqe;
+ void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
+ size_t sqe_len = READ_ONCE(sqe->len);
+ u8 opcode;
+
+ /*
+ * We're reading ->opcode for the second time, but the first read
+ * doesn't care whether it's _FIXED or not, so it doesn't matter
+ * whether ->opcode changes concurrently. The first read does care
+ * about whether it is a READ or a WRITE, so we don't trust this read
+ * for that purpose and instead let the caller pass in the read/write
+ * flag.
+ */
+ opcode = READ_ONCE(sqe->opcode);
+ if (opcode == IORING_OP_READ_FIXED ||
+ opcode == IORING_OP_WRITE_FIXED) {
+ ssize_t ret = io_import_fixed(ctx, rw, sqe, iter);
+ *iovec = NULL;
+ return ret;
+ }
+
+ if (!s->has_user)
+ return -EFAULT;
+
+#ifdef CONFIG_COMPAT
+ if (ctx->compat)
+ return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
+ iovec, iter);
+#endif
+
+ return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
+}
+
+static inline bool io_should_merge(struct async_list *al, struct kiocb *kiocb)
+{
+ if (al->file == kiocb->ki_filp) {
+ off_t start, end;
+
+ /*
+ * Allow merging if we're anywhere in the range of the same
+ * page. Generally this happens for sub-page reads or writes,
+ * and it's beneficial to allow the first worker to bring the
+ * page in and the piggy backed work can then work on the
+ * cached page.
+ */
+ start = al->io_start & PAGE_MASK;
+ end = (al->io_start + al->io_len + PAGE_SIZE - 1) & PAGE_MASK;
+ if (kiocb->ki_pos >= start && kiocb->ki_pos <= end)
+ return true;
+ }
+
+ al->file = NULL;
+ return false;
+}
+
+/*
+ * Make a note of the last file/offset/direction we punted to async
+ * context. We'll use this information to see if we can piggy back a
+ * sequential request onto the previous one, if it's still hasn't been
+ * completed by the async worker.
+ */
+static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
+{
+ struct async_list *async_list = &req->ctx->pending_async[rw];
+ struct kiocb *kiocb = &req->rw;
+ struct file *filp = kiocb->ki_filp;
+
+ if (io_should_merge(async_list, kiocb)) {
+ unsigned long max_bytes;
+
+ /* Use 8x RA size as a decent limiter for both reads/writes */
+ max_bytes = filp->f_ra.ra_pages << (PAGE_SHIFT + 3);
+ if (!max_bytes)
+ max_bytes = VM_READAHEAD_PAGES << (PAGE_SHIFT + 3);
+
+ /* If max len are exceeded, reset the state */
+ if (async_list->io_len + len <= max_bytes) {
+ req->flags |= REQ_F_SEQ_PREV;
+ async_list->io_len += len;
+ } else {
+ async_list->file = NULL;
+ }
+ }
+
+ /* New file? Reset state. */
+ if (async_list->file != filp) {
+ async_list->io_start = kiocb->ki_pos;
+ async_list->io_len = len;
+ async_list->file = filp;
+ }
+}
+
+/*
+ * For files that don't have ->read_iter() and ->write_iter(), handle them
+ * by looping over ->read() or ->write() manually.
+ */
+static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
+ struct iov_iter *iter)
+{
+ ssize_t ret = 0;
+
+ /*
+ * Don't support polled IO through this interface, and we can't
+ * support non-blocking either. For the latter, this just causes
+ * the kiocb to be handled from an async context.
+ */
+ if (kiocb->ki_flags & IOCB_HIPRI)
+ return -EOPNOTSUPP;
+ if (kiocb->ki_flags & IOCB_NOWAIT)
+ return -EAGAIN;
+
+ while (iov_iter_count(iter)) {
+ struct iovec iovec = iov_iter_iovec(iter);
+ ssize_t nr;
+
+ if (rw == READ) {
+ nr = file->f_op->read(file, iovec.iov_base,
+ iovec.iov_len, &kiocb->ki_pos);
+ } else {
+ nr = file->f_op->write(file, iovec.iov_base,
+ iovec.iov_len, &kiocb->ki_pos);
+ }
+
+ if (nr < 0) {
+ if (!ret)
+ ret = nr;
+ break;
+ }
+ ret += nr;
+ if (nr != iovec.iov_len)
+ break;
+ iov_iter_advance(iter, nr);
+ }
+
+ return ret;
+}
+
+static int io_read(struct io_kiocb *req, const struct sqe_submit *s,
+ bool force_nonblock)
+{
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct kiocb *kiocb = &req->rw;
+ struct iov_iter iter;
+ struct file *file;
+ size_t iov_count;
+ ssize_t read_size, ret;
+
+ ret = io_prep_rw(req, s, force_nonblock);
+ if (ret)
+ return ret;
+ file = kiocb->ki_filp;
+
+ if (unlikely(!(file->f_mode & FMODE_READ)))
+ return -EBADF;
+
+ ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
+ if (ret < 0)
+ return ret;
+
+ read_size = ret;
+ if (req->flags & REQ_F_LINK)
+ req->result = read_size;
+
+ iov_count = iov_iter_count(&iter);
+ ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
+ if (!ret) {
+ ssize_t ret2;
+
+ if (file->f_op->read_iter)
+ ret2 = call_read_iter(file, kiocb, &iter);
+ else
+ ret2 = loop_rw_iter(READ, file, kiocb, &iter);
+
+ /*
+ * In case of a short read, punt to async. This can happen
+ * if we have data partially cached. Alternatively we can
+ * return the short read, in which case the application will
+ * need to issue another SQE and wait for it. That SQE will
+ * need async punt anyway, so it's more efficient to do it
+ * here.
+ */
+ if (force_nonblock && !(req->flags & REQ_F_NOWAIT) &&
+ (req->flags & REQ_F_ISREG) &&
+ ret2 > 0 && ret2 < read_size)
+ ret2 = -EAGAIN;
+ /* Catch -EAGAIN return for forced non-blocking submission */
+ if (!force_nonblock || ret2 != -EAGAIN) {
+ io_rw_done(kiocb, ret2);
+ } else {
+ /*
+ * If ->needs_lock is true, we're already in async
+ * context.
+ */
+ if (!s->needs_lock)
+ io_async_list_note(READ, req, iov_count);
+ ret = -EAGAIN;
+ }
+ }
+ kfree(iovec);
+ return ret;
+}
+
+static int io_write(struct io_kiocb *req, const struct sqe_submit *s,
+ bool force_nonblock)
+{
+ struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+ struct kiocb *kiocb = &req->rw;
+ struct iov_iter iter;
+ struct file *file;
+ size_t iov_count;
+ ssize_t ret;
+
+ ret = io_prep_rw(req, s, force_nonblock);
+ if (ret)
+ return ret;
+
+ file = kiocb->ki_filp;
+ if (unlikely(!(file->f_mode & FMODE_WRITE)))
+ return -EBADF;
+
+ ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
+ if (ret < 0)
+ return ret;
+
+ if (req->flags & REQ_F_LINK)
+ req->result = ret;
+
+ iov_count = iov_iter_count(&iter);
+
+ ret = -EAGAIN;
+ if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT)) {
+ /* If ->needs_lock is true, we're already in async context. */
+ if (!s->needs_lock)
+ io_async_list_note(WRITE, req, iov_count);
+ goto out_free;
+ }
+
+ ret = rw_verify_area(WRITE, file, &kiocb->ki_pos, iov_count);
+ if (!ret) {
+ ssize_t ret2;
+
+ /*
+ * Open-code file_start_write here to grab freeze protection,
+ * which will be released by another thread in
+ * io_complete_rw(). Fool lockdep by telling it the lock got
+ * released so that it doesn't complain about the held lock when
+ * we return to userspace.
+ */
+ if (req->flags & REQ_F_ISREG) {
+ __sb_start_write(file_inode(file)->i_sb,
+ SB_FREEZE_WRITE, true);
+ __sb_writers_release(file_inode(file)->i_sb,
+ SB_FREEZE_WRITE);
+ }
+ kiocb->ki_flags |= IOCB_WRITE;
+
+ if (file->f_op->write_iter)
+ ret2 = call_write_iter(file, kiocb, &iter);
+ else
+ ret2 = loop_rw_iter(WRITE, file, kiocb, &iter);
+ if (!force_nonblock || ret2 != -EAGAIN) {
+ io_rw_done(kiocb, ret2);
+ } else {
+ /*
+ * If ->needs_lock is true, we're already in async
+ * context.
+ */
+ if (!s->needs_lock)
+ io_async_list_note(WRITE, req, iov_count);
+ ret = -EAGAIN;
+ }
+ }
+out_free:
+ kfree(iovec);
+ return ret;
+}
+
+/*
+ * IORING_OP_NOP just posts a completion event, nothing else.
+ */
+static int io_nop(struct io_kiocb *req, u64 user_data)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ long err = 0;
+
+ if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+
+ io_cqring_add_event(ctx, user_data, err);
+ io_put_req(req);
+ return 0;
+}
+
+static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+
+ if (!req->file)
+ return -EBADF;
+
+ if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+ if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+ bool force_nonblock)
+{
+ loff_t sqe_off = READ_ONCE(sqe->off);
+ loff_t sqe_len = READ_ONCE(sqe->len);
+ loff_t end = sqe_off + sqe_len;
+ unsigned fsync_flags;
+ int ret;
+
+ fsync_flags = READ_ONCE(sqe->fsync_flags);
+ if (unlikely(fsync_flags & ~IORING_FSYNC_DATASYNC))
+ return -EINVAL;
+
+ ret = io_prep_fsync(req, sqe);
+ if (ret)
+ return ret;
+
+ /* fsync always requires a blocking context */
+ if (force_nonblock)
+ return -EAGAIN;
+
+ ret = vfs_fsync_range(req->rw.ki_filp, sqe_off,
+ end > 0 ? end : LLONG_MAX,
+ fsync_flags & IORING_FSYNC_DATASYNC);
+
+ 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);
+ return 0;
+}
+
+static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ int ret = 0;
+
+ if (!req->file)
+ return -EBADF;
+
+ if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+ if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
+ return -EINVAL;
+
+ return ret;
+}
+
+static int io_sync_file_range(struct io_kiocb *req,
+ const struct io_uring_sqe *sqe,
+ bool force_nonblock)
+{
+ loff_t sqe_off;
+ loff_t sqe_len;
+ unsigned flags;
+ int ret;
+
+ ret = io_prep_sfr(req, sqe);
+ if (ret)
+ return ret;
+
+ /* sync_file_range always requires a blocking context */
+ if (force_nonblock)
+ return -EAGAIN;
+
+ sqe_off = READ_ONCE(sqe->off);
+ sqe_len = READ_ONCE(sqe->len);
+ flags = READ_ONCE(sqe->sync_range_flags);
+
+ ret = sync_file_range(req->rw.ki_filp, sqe_off, sqe_len, flags);
+
+ 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);
+ return 0;
+}
+
+#if defined(CONFIG_NET)
+static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+ bool force_nonblock,
+ long (*fn)(struct socket *, struct user_msghdr __user *,
+ unsigned int))
+{
+ struct socket *sock;
+ int ret;
+
+ if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+
+ sock = sock_from_file(req->file, &ret);
+ if (sock) {
+ struct user_msghdr __user *msg;
+ unsigned flags;
+
+ flags = READ_ONCE(sqe->msg_flags);
+ if (flags & MSG_DONTWAIT)
+ req->flags |= REQ_F_NOWAIT;
+ else if (force_nonblock)
+ flags |= MSG_DONTWAIT;
+
+ msg = (struct user_msghdr __user *) (unsigned long)
+ READ_ONCE(sqe->addr);
+
+ ret = fn(sock, msg, flags);
+ if (force_nonblock && ret == -EAGAIN)
+ return ret;
+ }
+
+ io_cqring_add_event(req->ctx, sqe->user_data, ret);
+ io_put_req(req);
+ return 0;
+}
+#endif
+
+static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+ bool force_nonblock)
+{
+#if defined(CONFIG_NET)
+ return io_send_recvmsg(req, sqe, 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)
+{
+#if defined(CONFIG_NET)
+ return io_send_recvmsg(req, sqe, force_nonblock, __sys_recvmsg_sock);
+#else
+ return -EOPNOTSUPP;
+#endif
+}
+
+static void io_poll_remove_one(struct io_kiocb *req)
+{
+ struct io_poll_iocb *poll = &req->poll;
+
+ spin_lock(&poll->head->lock);
+ WRITE_ONCE(poll->canceled, true);
+ if (!list_empty(&poll->wait.entry)) {
+ list_del_init(&poll->wait.entry);
+ io_queue_async_work(req->ctx, req);
+ }
+ spin_unlock(&poll->head->lock);
+
+ list_del_init(&req->list);
+}
+
+static void io_poll_remove_all(struct io_ring_ctx *ctx)
+{
+ struct io_kiocb *req;
+
+ spin_lock_irq(&ctx->completion_lock);
+ while (!list_empty(&ctx->cancel_list)) {
+ req = list_first_entry(&ctx->cancel_list, struct io_kiocb,list);
+ io_poll_remove_one(req);
+ }
+ spin_unlock_irq(&ctx->completion_lock);
+}
+
+/*
+ * Find a running poll command that matches one specified in sqe->addr,
+ * and remove it if found.
+ */
+static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_kiocb *poll_req, *next;
+ int ret = -ENOENT;
+
+ if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+ if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
+ sqe->poll_events)
+ return -EINVAL;
+
+ spin_lock_irq(&ctx->completion_lock);
+ list_for_each_entry_safe(poll_req, next, &ctx->cancel_list, list) {
+ if (READ_ONCE(sqe->addr) == poll_req->user_data) {
+ io_poll_remove_one(poll_req);
+ ret = 0;
+ break;
+ }
+ }
+ spin_unlock_irq(&ctx->completion_lock);
+
+ io_cqring_add_event(req->ctx, sqe->user_data, ret);
+ io_put_req(req);
+ return 0;
+}
+
+static void io_poll_complete(struct io_ring_ctx *ctx, struct io_kiocb *req,
+ __poll_t mask)
+{
+ req->poll.done = true;
+ io_cqring_fill_event(ctx, req->user_data, mangle_poll(mask));
+ io_commit_cqring(ctx);
+}
+
+static void io_poll_complete_work(struct work_struct *work)
+{
+ struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+ struct io_poll_iocb *poll = &req->poll;
+ struct poll_table_struct pt = { ._key = poll->events };
+ struct io_ring_ctx *ctx = req->ctx;
+ const struct cred *old_cred;
+ __poll_t mask = 0;
+
+ old_cred = override_creds(ctx->creds);
+
+ if (!READ_ONCE(poll->canceled))
+ mask = vfs_poll(poll->file, &pt) & poll->events;
+
+ /*
+ * Note that ->ki_cancel callers also delete iocb from active_reqs after
+ * calling ->ki_cancel. We need the ctx_lock roundtrip here to
+ * synchronize with them. In the cancellation case the list_del_init
+ * itself is not actually needed, but harmless so we keep it in to
+ * avoid further branches in the fast path.
+ */
+ spin_lock_irq(&ctx->completion_lock);
+ if (!mask && !READ_ONCE(poll->canceled)) {
+ add_wait_queue(poll->head, &poll->wait);
+ spin_unlock_irq(&ctx->completion_lock);
+ goto out;
+ }
+ list_del_init(&req->list);
+ io_poll_complete(ctx, req, mask);
+ spin_unlock_irq(&ctx->completion_lock);
+
+ io_cqring_ev_posted(ctx);
+ io_put_req(req);
+out:
+ revert_creds(old_cred);
+}
+
+static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
+ void *key)
+{
+ struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
+ wait);
+ struct io_kiocb *req = container_of(poll, struct io_kiocb, poll);
+ struct io_ring_ctx *ctx = req->ctx;
+ __poll_t mask = key_to_poll(key);
+ unsigned long flags;
+
+ /* for instances that support it check for an event match first: */
+ if (mask && !(mask & poll->events))
+ return 0;
+
+ list_del_init(&poll->wait.entry);
+
+ if (mask && spin_trylock_irqsave(&ctx->completion_lock, flags)) {
+ list_del(&req->list);
+ io_poll_complete(ctx, req, mask);
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+ io_cqring_ev_posted(ctx);
+ io_put_req(req);
+ } else {
+ io_queue_async_work(ctx, req);
+ }
+
+ return 1;
+}
+
+struct io_poll_table {
+ struct poll_table_struct pt;
+ struct io_kiocb *req;
+ int error;
+};
+
+static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
+ struct poll_table_struct *p)
+{
+ struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);
+
+ if (unlikely(pt->req->poll.head)) {
+ pt->error = -EINVAL;
+ return;
+ }
+
+ pt->error = 0;
+ pt->req->poll.head = head;
+ add_wait_queue(head, &pt->req->poll.wait);
+}
+
+static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ struct io_poll_iocb *poll = &req->poll;
+ struct io_ring_ctx *ctx = req->ctx;
+ struct io_poll_table ipt;
+ bool cancel = false;
+ __poll_t mask;
+ u16 events;
+
+ if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+ if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
+ return -EINVAL;
+ if (!poll->file)
+ return -EBADF;
+
+ req->submit.sqe = NULL;
+ INIT_WORK(&req->work, io_poll_complete_work);
+ events = READ_ONCE(sqe->poll_events);
+ poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
+
+ poll->head = NULL;
+ poll->done = false;
+ poll->canceled = false;
+
+ ipt.pt._qproc = io_poll_queue_proc;
+ ipt.pt._key = poll->events;
+ ipt.req = req;
+ ipt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
+
+ /* initialized the list so that we can do list_empty checks */
+ INIT_LIST_HEAD(&poll->wait.entry);
+ init_waitqueue_func_entry(&poll->wait, io_poll_wake);
+
+ INIT_LIST_HEAD(&req->list);
+
+ mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
+
+ spin_lock_irq(&ctx->completion_lock);
+ if (likely(poll->head)) {
+ spin_lock(&poll->head->lock);
+ if (unlikely(list_empty(&poll->wait.entry))) {
+ if (ipt.error)
+ cancel = true;
+ ipt.error = 0;
+ mask = 0;
+ }
+ if (mask || ipt.error)
+ list_del_init(&poll->wait.entry);
+ else if (cancel)
+ WRITE_ONCE(poll->canceled, true);
+ else if (!poll->done) /* actually waiting for an event */
+ list_add_tail(&req->list, &ctx->cancel_list);
+ spin_unlock(&poll->head->lock);
+ }
+ if (mask) { /* no async, we'd stolen it */
+ ipt.error = 0;
+ io_poll_complete(ctx, req, mask);
+ }
+ spin_unlock_irq(&ctx->completion_lock);
+
+ if (mask) {
+ io_cqring_ev_posted(ctx);
+ io_put_req(req);
+ }
+ return ipt.error;
+}
+
+static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
+{
+ struct io_ring_ctx *ctx;
+ struct io_kiocb *req, *prev;
+ unsigned long flags;
+
+ req = container_of(timer, struct io_kiocb, timeout.timer);
+ ctx = req->ctx;
+ atomic_inc(&ctx->cq_timeouts);
+
+ spin_lock_irqsave(&ctx->completion_lock, flags);
+ /*
+ * Adjust the reqs sequence before the current one because it
+ * will consume a slot in the cq_ring and the the cq_tail pointer
+ * will be increased, otherwise other timeout reqs may return in
+ * advance without waiting for enough wait_nr.
+ */
+ prev = req;
+ list_for_each_entry_continue_reverse(prev, &ctx->timeout_list, list)
+ prev->sequence++;
+ list_del(&req->list);
+
+ io_cqring_fill_event(ctx, req->user_data, -ETIME);
+ io_commit_cqring(ctx);
+ spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+ io_cqring_ev_posted(ctx);
+
+ io_put_req(req);
+ return HRTIMER_NORESTART;
+}
+
+static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+ unsigned count;
+ struct io_ring_ctx *ctx = req->ctx;
+ struct list_head *entry;
+ struct timespec64 ts;
+ unsigned span = 0;
+
+ if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+ return -EINVAL;
+ if (sqe->flags || sqe->ioprio || sqe->buf_index || sqe->timeout_flags ||
+ sqe->len != 1)
+ return -EINVAL;
+
+ if (get_timespec64(&ts, u64_to_user_ptr(sqe->addr)))
+ return -EFAULT;
+
+ req->flags |= REQ_F_TIMEOUT;
+
+ /*
+ * sqe->off holds how many events that need to occur for this
+ * timeout event to be satisfied. If it isn't set, then this is
+ * a pure timeout request, sequence isn't used.
+ */
+ count = READ_ONCE(sqe->off);
+ if (!count) {
+ req->flags |= REQ_F_TIMEOUT_NOSEQ;
+ spin_lock_irq(&ctx->completion_lock);
+ entry = ctx->timeout_list.prev;
+ goto add;
+ }
+
+ req->sequence = ctx->cached_sq_head + count - 1;
+ /* reuse it to store the count */
+ req->submit.sequence = count;
+
+ /*
+ * Insertion sort, ensuring the first entry in the list is always
+ * the one we need first.
+ */
+ spin_lock_irq(&ctx->completion_lock);
+ list_for_each_prev(entry, &ctx->timeout_list) {
+ struct io_kiocb *nxt = list_entry(entry, struct io_kiocb, list);
+ unsigned nxt_sq_head;
+ long long tmp, tmp_nxt;
+
+ if (nxt->flags & REQ_F_TIMEOUT_NOSEQ)
+ continue;
+
+ /*
+ * Since cached_sq_head + count - 1 can overflow, use type long
+ * long to store it.
+ */
+ tmp = (long long)ctx->cached_sq_head + count - 1;
+ nxt_sq_head = nxt->sequence - nxt->submit.sequence + 1;
+ tmp_nxt = (long long)nxt_sq_head + nxt->submit.sequence - 1;
+
+ /*
+ * cached_sq_head may overflow, and it will never overflow twice
+ * once there is some timeout req still be valid.
+ */
+ if (ctx->cached_sq_head < nxt_sq_head)
+ tmp += UINT_MAX;
+
+ if (tmp > tmp_nxt)
+ break;
+
+ /*
+ * Sequence of reqs after the insert one and itself should
+ * be adjusted because each timeout req consumes a slot.
+ */
+ span++;
+ nxt->sequence++;
+ }
+ req->sequence -= span;
+add:
+ list_add(&req->list, entry);
+ spin_unlock_irq(&ctx->completion_lock);
+
+ hrtimer_init(&req->timeout.timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+ req->timeout.timer.function = io_timeout_fn;
+ hrtimer_start(&req->timeout.timer, timespec64_to_ktime(ts),
+ HRTIMER_MODE_REL);
+ return 0;
+}
+
+static int io_req_defer(struct io_ring_ctx *ctx, struct io_kiocb *req,
+ const struct io_uring_sqe *sqe)
+{
+ struct io_uring_sqe *sqe_copy;
+
+ if (!io_sequence_defer(ctx, req) && list_empty(&ctx->defer_list))
+ return 0;
+
+ sqe_copy = kmalloc(sizeof(*sqe_copy), GFP_KERNEL);
+ if (!sqe_copy)
+ return -EAGAIN;
+
+ spin_lock_irq(&ctx->completion_lock);
+ if (!io_sequence_defer(ctx, req) && list_empty(&ctx->defer_list)) {
+ spin_unlock_irq(&ctx->completion_lock);
+ kfree(sqe_copy);
+ return 0;
+ }
+
+ memcpy(sqe_copy, sqe, sizeof(*sqe_copy));
+ req->submit.sqe = sqe_copy;
+
+ INIT_WORK(&req->work, io_sq_wq_submit_work);
+ list_add_tail(&req->list, &ctx->defer_list);
+ spin_unlock_irq(&ctx->completion_lock);
+ return -EIOCBQUEUED;
+}
+
+static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
+ const struct sqe_submit *s, bool force_nonblock)
+{
+ int ret, opcode;
+
+ req->user_data = READ_ONCE(s->sqe->user_data);
+
+ if (unlikely(s->index >= ctx->sq_entries))
+ return -EINVAL;
+
+ opcode = READ_ONCE(s->sqe->opcode);
+ switch (opcode) {
+ case IORING_OP_NOP:
+ ret = io_nop(req, req->user_data);
+ break;
+ case IORING_OP_READV:
+ if (unlikely(s->sqe->buf_index))
+ return -EINVAL;
+ ret = io_read(req, s, force_nonblock);
+ break;
+ case IORING_OP_WRITEV:
+ if (unlikely(s->sqe->buf_index))
+ return -EINVAL;
+ ret = io_write(req, s, force_nonblock);
+ break;
+ case IORING_OP_READ_FIXED:
+ ret = io_read(req, s, force_nonblock);
+ break;
+ case IORING_OP_WRITE_FIXED:
+ ret = io_write(req, s, force_nonblock);
+ break;
+ case IORING_OP_FSYNC:
+ ret = io_fsync(req, s->sqe, force_nonblock);
+ break;
+ case IORING_OP_POLL_ADD:
+ ret = io_poll_add(req, s->sqe);
+ break;
+ case IORING_OP_POLL_REMOVE:
+ ret = io_poll_remove(req, s->sqe);
+ break;
+ case IORING_OP_SYNC_FILE_RANGE:
+ ret = io_sync_file_range(req, s->sqe, force_nonblock);
+ break;
+ case IORING_OP_SENDMSG:
+ ret = io_sendmsg(req, s->sqe, force_nonblock);
+ break;
+ case IORING_OP_RECVMSG:
+ ret = io_recvmsg(req, s->sqe, force_nonblock);
+ break;
+ case IORING_OP_TIMEOUT:
+ ret = io_timeout(req, s->sqe);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ if (ret)
+ return ret;
+
+ if (ctx->flags & IORING_SETUP_IOPOLL) {
+ if (req->result == -EAGAIN)
+ return -EAGAIN;
+
+ /* workqueue context doesn't hold uring_lock, grab it now */
+ if (s->needs_lock)
+ mutex_lock(&ctx->uring_lock);
+ io_iopoll_req_issued(req);
+ if (s->needs_lock)
+ mutex_unlock(&ctx->uring_lock);
+ }
+
+ return 0;
+}
+
+static struct async_list *io_async_list_from_sqe(struct io_ring_ctx *ctx,
+ const struct io_uring_sqe *sqe)
+{
+ switch (sqe->opcode) {
+ case IORING_OP_READV:
+ case IORING_OP_READ_FIXED:
+ return &ctx->pending_async[READ];
+ case IORING_OP_WRITEV:
+ case IORING_OP_WRITE_FIXED:
+ return &ctx->pending_async[WRITE];
+ default:
+ return NULL;
+ }
+}
+
+static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
+{
+ u8 opcode = READ_ONCE(sqe->opcode);
+
+ return !(opcode == IORING_OP_READ_FIXED ||
+ opcode == IORING_OP_WRITE_FIXED);
+}
+
+static void io_sq_wq_submit_work(struct work_struct *work)
+{
+ struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+ struct io_ring_ctx *ctx = req->ctx;
+ struct mm_struct *cur_mm = NULL;
+ struct async_list *async_list;
+ const struct cred *old_cred;
+ LIST_HEAD(req_list);
+ mm_segment_t old_fs;
+ int ret;
+
+ old_cred = override_creds(ctx->creds);
+ async_list = io_async_list_from_sqe(ctx, req->submit.sqe);
+restart:
+ do {
+ struct sqe_submit *s = &req->submit;
+ const struct io_uring_sqe *sqe = s->sqe;
+ unsigned int flags = req->flags;
+
+ /* Ensure we clear previously set non-block flag */
+ req->rw.ki_flags &= ~IOCB_NOWAIT;
+
+ ret = 0;
+ if (io_sqe_needs_user(sqe) && !cur_mm) {
+ if (!mmget_not_zero(ctx->sqo_mm)) {
+ ret = -EFAULT;
+ } else {
+ cur_mm = ctx->sqo_mm;
+ use_mm(cur_mm);
+ old_fs = get_fs();
+ set_fs(USER_DS);
+ }
+ }
+
+ if (!ret) {
+ s->has_user = cur_mm != NULL;
+ s->needs_lock = true;
+ do {
+ ret = __io_submit_sqe(ctx, req, s, false);
+ /*
+ * We can get EAGAIN for polled IO even though
+ * we're forcing a sync submission from here,
+ * since we can't wait for request slots on the
+ * block side.
+ */
+ if (ret != -EAGAIN)
+ break;
+ cond_resched();
+ } while (1);
+ }
+
+ /* drop submission reference */
+ io_put_req(req);
+
+ if (ret) {
+ io_cqring_add_event(ctx, sqe->user_data, ret);
+ io_put_req(req);
+ }
+
+ /* async context always use a copy of the sqe */
+ kfree(sqe);
+
+ /* req from defer and link list needn't decrease async cnt */
+ if (flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE))
+ goto out;
+
+ if (!async_list)
+ break;
+ if (!list_empty(&req_list)) {
+ req = list_first_entry(&req_list, struct io_kiocb,
+ list);
+ list_del(&req->list);
+ continue;
+ }
+ if (list_empty(&async_list->list))
+ break;
+
+ req = NULL;
+ spin_lock(&async_list->lock);
+ if (list_empty(&async_list->list)) {
+ spin_unlock(&async_list->lock);
+ break;
+ }
+ list_splice_init(&async_list->list, &req_list);
+ spin_unlock(&async_list->lock);
+
+ req = list_first_entry(&req_list, struct io_kiocb, list);
+ list_del(&req->list);
+ } while (req);
+
+ /*
+ * Rare case of racing with a submitter. If we find the count has
+ * dropped to zero AND we have pending work items, then restart
+ * the processing. This is a tiny race window.
+ */
+ if (async_list) {
+ ret = atomic_dec_return(&async_list->cnt);
+ while (!ret && !list_empty(&async_list->list)) {
+ spin_lock(&async_list->lock);
+ atomic_inc(&async_list->cnt);
+ list_splice_init(&async_list->list, &req_list);
+ spin_unlock(&async_list->lock);
+
+ if (!list_empty(&req_list)) {
+ req = list_first_entry(&req_list,
+ struct io_kiocb, list);
+ list_del(&req->list);
+ goto restart;
+ }
+ ret = atomic_dec_return(&async_list->cnt);
+ }
+ }
+
+out:
+ if (cur_mm) {
+ set_fs(old_fs);
+ unuse_mm(cur_mm);
+ mmput(cur_mm);
+ }
+ revert_creds(old_cred);
+}
+
+/*
+ * See if we can piggy back onto previously submitted work, that is still
+ * running. We currently only allow this if the new request is sequential
+ * to the previous one we punted.
+ */
+static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
+{
+ bool ret;
+
+ if (!list)
+ return false;
+ if (!(req->flags & REQ_F_SEQ_PREV))
+ return false;
+ if (!atomic_read(&list->cnt))
+ return false;
+
+ ret = true;
+ spin_lock(&list->lock);
+ list_add_tail(&req->list, &list->list);
+ /*
+ * Ensure we see a simultaneous modification from io_sq_wq_submit_work()
+ */
+ smp_mb();
+ if (!atomic_read(&list->cnt)) {
+ list_del_init(&req->list);
+ ret = false;
+ }
+ spin_unlock(&list->lock);
+ return ret;
+}
+
+static bool io_op_needs_file(const struct io_uring_sqe *sqe)
+{
+ int op = READ_ONCE(sqe->opcode);
+
+ switch (op) {
+ case IORING_OP_NOP:
+ case IORING_OP_POLL_REMOVE:
+ case IORING_OP_TIMEOUT:
+ return false;
+ default:
+ return true;
+ }
+}
+
+static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
+ struct io_submit_state *state, struct io_kiocb *req)
+{
+ unsigned flags;
+ int fd;
+
+ flags = READ_ONCE(s->sqe->flags);
+ fd = READ_ONCE(s->sqe->fd);
+
+ if (flags & IOSQE_IO_DRAIN)
+ req->flags |= REQ_F_IO_DRAIN;
+ /*
+ * All io need record the previous position, if LINK vs DARIN,
+ * it can be used to mark the position of the first IO in the
+ * link list.
+ */
+ req->sequence = s->sequence;
+
+ if (!io_op_needs_file(s->sqe))
+ return 0;
+
+ if (flags & IOSQE_FIXED_FILE) {
+ if (unlikely(!ctx->user_files ||
+ (unsigned) fd >= ctx->nr_user_files))
+ return -EBADF;
+ req->file = ctx->user_files[fd];
+ req->flags |= REQ_F_FIXED_FILE;
+ } else {
+ if (s->needs_fixed_file)
+ return -EBADF;
+ req->file = io_file_get(state, fd);
+ if (unlikely(!req->file))
+ return -EBADF;
+ }
+
+ return 0;
+}
+
+static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
+ struct sqe_submit *s)
+{
+ int ret;
+
+ ret = __io_submit_sqe(ctx, req, s, true);
+
+ /*
+ * We async punt it if the file wasn't marked NOWAIT, or if the file
+ * doesn't support non-blocking read/write attempts
+ */
+ if (ret == -EAGAIN && (!(req->flags & REQ_F_NOWAIT) ||
+ (req->flags & REQ_F_MUST_PUNT))) {
+ struct io_uring_sqe *sqe_copy;
+
+ sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
+ if (sqe_copy) {
+ struct async_list *list;
+
+ s->sqe = sqe_copy;
+ memcpy(&req->submit, s, sizeof(*s));
+ list = io_async_list_from_sqe(ctx, s->sqe);
+ if (!io_add_to_prev_work(list, req)) {
+ if (list)
+ atomic_inc(&list->cnt);
+ INIT_WORK(&req->work, io_sq_wq_submit_work);
+ io_queue_async_work(ctx, req);
+ }
+
+ /*
+ * Queued up for async execution, worker will release
+ * submit reference when the iocb is actually submitted.
+ */
+ return 0;
+ }
+ }
+
+ /* drop submission reference */
+ io_put_req(req);
+
+ /* 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);
+ }
+
+ return ret;
+}
+
+static int io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
+ struct sqe_submit *s)
+{
+ int ret;
+
+ ret = io_req_defer(ctx, req, s->sqe);
+ if (ret) {
+ if (ret != -EIOCBQUEUED) {
+ io_free_req(req);
+ io_cqring_add_event(ctx, s->sqe->user_data, ret);
+ }
+ return 0;
+ }
+
+ return __io_queue_sqe(ctx, req, s);
+}
+
+static int io_queue_link_head(struct io_ring_ctx *ctx, struct io_kiocb *req,
+ struct sqe_submit *s, struct io_kiocb *shadow)
+{
+ int ret;
+ int need_submit = false;
+
+ if (!shadow)
+ return io_queue_sqe(ctx, req, s);
+
+ /*
+ * Mark the first IO in link list as DRAIN, let all the following
+ * IOs enter the defer list. all IO needs to be completed before link
+ * list.
+ */
+ req->flags |= REQ_F_IO_DRAIN;
+ ret = io_req_defer(ctx, req, s->sqe);
+ if (ret) {
+ if (ret != -EIOCBQUEUED) {
+ io_free_req(req);
+ __io_free_req(shadow);
+ io_cqring_add_event(ctx, s->sqe->user_data, ret);
+ return 0;
+ }
+ } else {
+ /*
+ * If ret == 0 means that all IOs in front of link io are
+ * running done. let's queue link head.
+ */
+ need_submit = true;
+ }
+
+ /* Insert shadow req to defer_list, blocking next IOs */
+ spin_lock_irq(&ctx->completion_lock);
+ list_add_tail(&shadow->list, &ctx->defer_list);
+ spin_unlock_irq(&ctx->completion_lock);
+
+ if (need_submit)
+ return __io_queue_sqe(ctx, req, s);
+
+ return 0;
+}
+
+#define SQE_VALID_FLAGS (IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK)
+
+static void io_submit_sqe(struct io_ring_ctx *ctx, struct sqe_submit *s,
+ struct io_submit_state *state, struct io_kiocb **link)
+{
+ struct io_uring_sqe *sqe_copy;
+ struct io_kiocb *req;
+ int ret;
+
+ /* enforce forwards compatibility on users */
+ if (unlikely(s->sqe->flags & ~SQE_VALID_FLAGS)) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ req = io_get_req(ctx, state);
+ if (unlikely(!req)) {
+ ret = -EAGAIN;
+ goto err;
+ }
+
+ ret = io_req_set_file(ctx, s, state, req);
+ if (unlikely(ret)) {
+err_req:
+ io_free_req(req);
+err:
+ io_cqring_add_event(ctx, s->sqe->user_data, ret);
+ return;
+ }
+
+ req->user_data = s->sqe->user_data;
+
+ /*
+ * If we already have a head request, queue this one for async
+ * submittal once the head completes. If we don't have a head but
+ * IOSQE_IO_LINK is set in the sqe, start a new head. This one will be
+ * submitted sync once the chain is complete. If none of those
+ * conditions are true (normal request), then just queue it.
+ */
+ if (*link) {
+ struct io_kiocb *prev = *link;
+
+ sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL);
+ if (!sqe_copy) {
+ ret = -EAGAIN;
+ goto err_req;
+ }
+
+ s->sqe = sqe_copy;
+ memcpy(&req->submit, s, sizeof(*s));
+ list_add_tail(&req->list, &prev->link_list);
+ } else if (s->sqe->flags & IOSQE_IO_LINK) {
+ req->flags |= REQ_F_LINK;
+
+ memcpy(&req->submit, s, sizeof(*s));
+ INIT_LIST_HEAD(&req->link_list);
+ *link = req;
+ } else {
+ io_queue_sqe(ctx, req, s);
+ }
+}
+
+/*
+ * 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);
+ io_file_put(state);
+ if (state->free_reqs)
+ kmem_cache_free_bulk(req_cachep, state->free_reqs,
+ &state->reqs[state->cur_req]);
+}
+
+/*
+ * Start submission side cache.
+ */
+static void io_submit_state_start(struct io_submit_state *state,
+ struct io_ring_ctx *ctx, unsigned max_ios)
+{
+ blk_start_plug(&state->plug);
+ state->free_reqs = 0;
+ state->file = NULL;
+ state->ios_left = max_ios;
+}
+
+static void io_commit_sqring(struct io_ring_ctx *ctx)
+{
+ struct io_rings *rings = ctx->rings;
+
+ if (ctx->cached_sq_head != READ_ONCE(rings->sq.head)) {
+ /*
+ * Ensure any loads from the SQEs are done at this point,
+ * since once we write the new head, the application could
+ * write new data to them.
+ */
+ smp_store_release(&rings->sq.head, ctx->cached_sq_head);
+ }
+}
+
+/*
+ * Fetch an sqe, if one is available. Note that s->sqe will point to memory
+ * that is mapped by userspace. This means that care needs to be taken to
+ * ensure that reads are stable, as we cannot rely on userspace always
+ * being a good citizen. If members of the sqe are validated and then later
+ * used, it's important that those reads are done through READ_ONCE() to
+ * prevent a re-load down the line.
+ */
+static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
+{
+ struct io_rings *rings = ctx->rings;
+ u32 *sq_array = ctx->sq_array;
+ unsigned head;
+
+ /*
+ * The cached sq head (or cq tail) serves two purposes:
+ *
+ * 1) allows us to batch the cost of updating the user visible
+ * head updates.
+ * 2) allows the kernel side to track the head on its own, even
+ * though the application is the one updating it.
+ */
+ head = ctx->cached_sq_head;
+ /* make sure SQ entry isn't read before tail */
+ if (head == smp_load_acquire(&rings->sq.tail))
+ return false;
+
+ head = READ_ONCE(sq_array[head & ctx->sq_mask]);
+ if (head < ctx->sq_entries) {
+ s->index = head;
+ s->sqe = &ctx->sq_sqes[head];
+ s->sequence = ctx->cached_sq_head;
+ ctx->cached_sq_head++;
+ return true;
+ }
+
+ /* drop invalid entries */
+ ctx->cached_sq_head++;
+ ctx->cached_sq_dropped++;
+ WRITE_ONCE(rings->sq_dropped, ctx->cached_sq_dropped);
+ return false;
+}
+
+static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
+ bool has_user, bool mm_fault)
+{
+ struct io_submit_state state, *statep = NULL;
+ struct io_kiocb *link = NULL;
+ struct io_kiocb *shadow_req = NULL;
+ bool prev_was_link = false;
+ int i, submitted = 0;
+
+ if (nr > IO_PLUG_THRESHOLD) {
+ io_submit_state_start(&state, ctx, nr);
+ statep = &state;
+ }
+
+ for (i = 0; i < nr; i++) {
+ struct sqe_submit s;
+
+ if (!io_get_sqring(ctx, &s))
+ break;
+
+ /*
+ * If previous wasn't linked and we have a linked command,
+ * that's the end of the chain. Submit the previous link.
+ */
+ if (!prev_was_link && link) {
+ io_queue_link_head(ctx, link, &link->submit, shadow_req);
+ link = NULL;
+ shadow_req = NULL;
+ }
+ prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
+
+ if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
+ if (!shadow_req) {
+ shadow_req = io_get_req(ctx, NULL);
+ if (unlikely(!shadow_req))
+ goto out;
+ shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
+ refcount_dec(&shadow_req->refs);
+ }
+ shadow_req->sequence = s.sequence;
+ }
+
+out:
+ if (unlikely(mm_fault)) {
+ io_cqring_add_event(ctx, s.sqe->user_data,
+ -EFAULT);
+ } else {
+ s.has_user = has_user;
+ s.needs_lock = true;
+ s.needs_fixed_file = true;
+ io_submit_sqe(ctx, &s, statep, &link);
+ submitted++;
+ }
+ }
+
+ if (link)
+ io_queue_link_head(ctx, link, &link->submit, shadow_req);
+ if (statep)
+ io_submit_state_end(&state);
+
+ return submitted;
+}
+
+static int io_sq_thread(void *data)
+{
+ struct io_ring_ctx *ctx = data;
+ struct mm_struct *cur_mm = NULL;
+ const struct cred *old_cred;
+ mm_segment_t old_fs;
+ DEFINE_WAIT(wait);
+ unsigned inflight;
+ unsigned long timeout;
+
+ complete(&ctx->sqo_thread_started);
+
+ old_fs = get_fs();
+ set_fs(USER_DS);
+ old_cred = override_creds(ctx->creds);
+
+ timeout = inflight = 0;
+ while (!kthread_should_park()) {
+ bool mm_fault = false;
+ unsigned int to_submit;
+
+ if (inflight) {
+ unsigned nr_events = 0;
+
+ if (ctx->flags & IORING_SETUP_IOPOLL) {
+ /*
+ * inflight is the count of the maximum possible
+ * entries we submitted, but it can be smaller
+ * if we dropped some of them. If we don't have
+ * poll entries available, then we know that we
+ * have nothing left to poll for. Reset the
+ * inflight count to zero in that case.
+ */
+ mutex_lock(&ctx->uring_lock);
+ if (!list_empty(&ctx->poll_list))
+ __io_iopoll_check(ctx, &nr_events, 0);
+ else
+ inflight = 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;
+ }
+
+ to_submit = io_sqring_entries(ctx);
+ if (!to_submit) {
+ /*
+ * 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)) {
+ cond_resched();
+ 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->rings->sq_flags |= IORING_SQ_NEED_WAKEUP;
+ /* make sure to read SQ tail after writing flags */
+ smp_mb();
+
+ to_submit = io_sqring_entries(ctx);
+ if (!to_submit) {
+ if (kthread_should_park()) {
+ finish_wait(&ctx->sqo_wait, &wait);
+ break;
+ }
+ if (signal_pending(current))
+ flush_signals(current);
+ schedule();
+ finish_wait(&ctx->sqo_wait, &wait);
+
+ ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
+ continue;
+ }
+ finish_wait(&ctx->sqo_wait, &wait);
+
+ ctx->rings->sq_flags &= ~IORING_SQ_NEED_WAKEUP;
+ }
+
+ /* Unless all new commands are FIXED regions, grab mm */
+ if (!cur_mm) {
+ mm_fault = !mmget_not_zero(ctx->sqo_mm);
+ if (!mm_fault) {
+ use_mm(ctx->sqo_mm);
+ cur_mm = ctx->sqo_mm;
+ }
+ }
+
+ to_submit = min(to_submit, ctx->sq_entries);
+ inflight += io_submit_sqes(ctx, to_submit, 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);
+ }
+ revert_creds(old_cred);
+
+ kthread_parkme();
+
+ return 0;
+}
+
+static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
+{
+ struct io_submit_state state, *statep = NULL;
+ struct io_kiocb *link = NULL;
+ struct io_kiocb *shadow_req = NULL;
+ bool prev_was_link = false;
+ int i, submit = 0;
+
+ if (to_submit > IO_PLUG_THRESHOLD) {
+ io_submit_state_start(&state, ctx, to_submit);
+ statep = &state;
+ }
+
+ for (i = 0; i < to_submit; i++) {
+ struct sqe_submit s;
+
+ if (!io_get_sqring(ctx, &s))
+ break;
+
+ /*
+ * If previous wasn't linked and we have a linked command,
+ * that's the end of the chain. Submit the previous link.
+ */
+ if (!prev_was_link && link) {
+ io_queue_link_head(ctx, link, &link->submit, shadow_req);
+ link = NULL;
+ shadow_req = NULL;
+ }
+ prev_was_link = (s.sqe->flags & IOSQE_IO_LINK) != 0;
+
+ if (link && (s.sqe->flags & IOSQE_IO_DRAIN)) {
+ if (!shadow_req) {
+ shadow_req = io_get_req(ctx, NULL);
+ if (unlikely(!shadow_req))
+ goto out;
+ shadow_req->flags |= (REQ_F_IO_DRAIN | REQ_F_SHADOW_DRAIN);
+ refcount_dec(&shadow_req->refs);
+ }
+ shadow_req->sequence = s.sequence;
+ }
+
+out:
+ s.has_user = true;
+ s.needs_lock = false;
+ s.needs_fixed_file = false;
+ submit++;
+ io_submit_sqe(ctx, &s, statep, &link);
+ }
+
+ if (link)
+ io_queue_link_head(ctx, link, &link->submit, shadow_req);
+ if (statep)
+ io_submit_state_end(statep);
+
+ io_commit_sqring(ctx);
+
+ return submit;
+}
+
+struct io_wait_queue {
+ struct wait_queue_entry wq;
+ struct io_ring_ctx *ctx;
+ unsigned to_wait;
+ unsigned nr_timeouts;
+};
+
+static inline bool io_should_wake(struct io_wait_queue *iowq)
+{
+ struct io_ring_ctx *ctx = iowq->ctx;
+
+ /*
+ * Wake up if we have enough events, or if a timeout occured since we
+ * started waiting. For timeouts, we always want to return to userspace,
+ * regardless of event count.
+ */
+ return io_cqring_events(ctx->rings) >= iowq->to_wait ||
+ atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
+}
+
+static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
+ int wake_flags, void *key)
+{
+ struct io_wait_queue *iowq = container_of(curr, struct io_wait_queue,
+ wq);
+
+ if (!io_should_wake(iowq))
+ return -1;
+
+ return autoremove_wake_function(curr, mode, wake_flags, key);
+}
+
+/*
+ * Wait until events become available, if we don't already have some. The
+ * application must reap them itself, as they reside on the shared cq ring.
+ */
+static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
+ const sigset_t __user *sig, size_t sigsz)
+{
+ struct io_wait_queue iowq = {
+ .wq = {
+ .private = current,
+ .func = io_wake_function,
+ .entry = LIST_HEAD_INIT(iowq.wq.entry),
+ },
+ .ctx = ctx,
+ .to_wait = min_events,
+ };
+ struct io_rings *rings = ctx->rings;
+ int ret;
+
+ if (io_cqring_events(rings) >= min_events)
+ return 0;
+
+ if (sig) {
+#ifdef CONFIG_COMPAT
+ if (in_compat_syscall())
+ ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
+ sigsz);
+ else
+#endif
+ ret = set_user_sigmask(sig, sigsz);
+
+ if (ret)
+ return ret;
+ }
+
+ ret = 0;
+ iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
+ do {
+ prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
+ TASK_INTERRUPTIBLE);
+ if (io_should_wake(&iowq))
+ break;
+ schedule();
+ if (signal_pending(current)) {
+ ret = -ERESTARTSYS;
+ break;
+ }
+ } while (1);
+ finish_wait(&ctx->wait, &iowq.wq);
+
+ restore_saved_sigmask_unless(ret == -ERESTARTSYS);
+ if (ret == -ERESTARTSYS)
+ ret = -EINTR;
+
+ return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
+}
+
+static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
+{
+#if defined(CONFIG_UNIX)
+ if (ctx->ring_sock) {
+ struct sock *sock = ctx->ring_sock->sk;
+ struct sk_buff *skb;
+
+ while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
+ kfree_skb(skb);
+ }
+#else
+ int i;
+
+ for (i = 0; i < ctx->nr_user_files; i++)
+ fput(ctx->user_files[i]);
+#endif
+}
+
+static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
+{
+ if (!ctx->user_files)
+ return -ENXIO;
+
+ __io_sqe_files_unregister(ctx);
+ kfree(ctx->user_files);
+ ctx->user_files = NULL;
+ ctx->nr_user_files = 0;
+ return 0;
+}
+
+static void io_sq_thread_stop(struct io_ring_ctx *ctx)
+{
+ if (ctx->sqo_thread) {
+ wait_for_completion(&ctx->sqo_thread_started);
+ /*
+ * The park is a bit of a work-around, without it we get
+ * warning spews on shutdown with SQPOLL set and affinity
+ * set to a single CPU.
+ */
+ kthread_park(ctx->sqo_thread);
+ kthread_stop(ctx->sqo_thread);
+ ctx->sqo_thread = NULL;
+ }
+}
+
+static void io_finish_async(struct io_ring_ctx *ctx)
+{
+ int i;
+
+ io_sq_thread_stop(ctx);
+
+ for (i = 0; i < ARRAY_SIZE(ctx->sqo_wq); i++) {
+ if (ctx->sqo_wq[i]) {
+ destroy_workqueue(ctx->sqo_wq[i]);
+ ctx->sqo_wq[i] = NULL;
+ }
+ }
+}
+
+#if defined(CONFIG_UNIX)
+static void io_destruct_skb(struct sk_buff *skb)
+{
+ struct io_ring_ctx *ctx = skb->sk->sk_user_data;
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ctx->sqo_wq); i++)
+ if (ctx->sqo_wq[i])
+ flush_workqueue(ctx->sqo_wq[i]);
+
+ unix_destruct_scm(skb);
+}
+
+/*
+ * Ensure the UNIX gc is aware of our file set, so we are certain that
+ * the io_uring can be safely unregistered on process exit, even if we have
+ * loops in the file referencing.
+ */
+static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
+{
+ struct sock *sk = ctx->ring_sock->sk;
+ struct scm_fp_list *fpl;
+ struct sk_buff *skb;
+ int i;
+
+ if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
+ unsigned long inflight = ctx->user->unix_inflight + nr;
+
+ if (inflight > task_rlimit(current, RLIMIT_NOFILE))
+ return -EMFILE;
+ }
+
+ fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
+ if (!fpl)
+ return -ENOMEM;
+
+ skb = alloc_skb(0, GFP_KERNEL);
+ if (!skb) {
+ kfree(fpl);
+ return -ENOMEM;
+ }
+
+ skb->sk = sk;
+ skb->destructor = io_destruct_skb;
+
+ fpl->user = get_uid(ctx->user);
+ for (i = 0; i < nr; i++) {
+ fpl->fp[i] = get_file(ctx->user_files[i + offset]);
+ unix_inflight(fpl->user, fpl->fp[i]);
+ }
+
+ fpl->max = fpl->count = nr;
+ UNIXCB(skb).fp = fpl;
+ refcount_add(skb->truesize, &sk->sk_wmem_alloc);
+ skb_queue_head(&sk->sk_receive_queue, skb);
+
+ for (i = 0; i < nr; i++)
+ fput(fpl->fp[i]);
+
+ return 0;
+}
+
+/*
+ * If UNIX sockets are enabled, fd passing can cause a reference cycle which
+ * causes regular reference counting to break down. We rely on the UNIX
+ * garbage collection to take care of this problem for us.
+ */
+static int io_sqe_files_scm(struct io_ring_ctx *ctx)
+{
+ unsigned left, total;
+ int ret = 0;
+
+ total = 0;
+ left = ctx->nr_user_files;
+ while (left) {
+ unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
+
+ ret = __io_sqe_files_scm(ctx, this_files, total);
+ if (ret)
+ break;
+ left -= this_files;
+ total += this_files;
+ }
+
+ if (!ret)
+ return 0;
+
+ while (total < ctx->nr_user_files) {
+ fput(ctx->user_files[total]);
+ total++;
+ }
+
+ return ret;
+}
+#else
+static int io_sqe_files_scm(struct io_ring_ctx *ctx)
+{
+ return 0;
+}
+#endif
+
+static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
+ unsigned nr_args)
+{
+ __s32 __user *fds = (__s32 __user *) arg;
+ int fd, ret = 0;
+ unsigned i;
+
+ if (ctx->user_files)
+ return -EBUSY;
+ if (!nr_args)
+ return -EINVAL;
+ if (nr_args > IORING_MAX_FIXED_FILES)
+ return -EMFILE;
+
+ ctx->user_files = kcalloc(nr_args, sizeof(struct file *), GFP_KERNEL);
+ if (!ctx->user_files)
+ return -ENOMEM;
+
+ for (i = 0; i < nr_args; i++) {
+ ret = -EFAULT;
+ if (copy_from_user(&fd, &fds[i], sizeof(fd)))
+ break;
+
+ ctx->user_files[i] = fget(fd);
+
+ ret = -EBADF;
+ if (!ctx->user_files[i])
+ break;
+ /*
+ * Don't allow io_uring instances to be registered. If UNIX
+ * isn't enabled, then this causes a reference cycle and this
+ * instance can never get freed. If UNIX is enabled we'll
+ * handle it just fine, but there's still no point in allowing
+ * a ring fd as it doesn't support regular read/write anyway.
+ */
+ if (ctx->user_files[i]->f_op == &io_uring_fops) {
+ fput(ctx->user_files[i]);
+ break;
+ }
+ ctx->nr_user_files++;
+ ret = 0;
+ }
+
+ if (ret) {
+ for (i = 0; i < ctx->nr_user_files; i++)
+ fput(ctx->user_files[i]);
+
+ kfree(ctx->user_files);
+ ctx->user_files = NULL;
+ ctx->nr_user_files = 0;
+ return ret;
+ }
+
+ ret = io_sqe_files_scm(ctx);
+ if (ret)
+ io_sqe_files_unregister(ctx);
+
+ return ret;
+}
+
+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;
+
+ if (ctx->flags & IORING_SETUP_SQPOLL) {
+ ret = -EPERM;
+ if (!capable(CAP_SYS_ADMIN))
+ goto err;
+
+ ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
+ if (!ctx->sq_thread_idle)
+ ctx->sq_thread_idle = HZ;
+
+ if (p->flags & IORING_SETUP_SQ_AFF) {
+ int cpu = p->sq_thread_cpu;
+
+ ret = -EINVAL;
+ if (cpu >= nr_cpu_ids)
+ goto err;
+ if (!cpu_online(cpu))
+ goto err;
+
+ 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[0] = alloc_workqueue("io_ring-wq",
+ WQ_UNBOUND | WQ_FREEZABLE,
+ min(ctx->sq_entries - 1, 2 * num_online_cpus()));
+ if (!ctx->sqo_wq[0]) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ /*
+ * This is for buffered writes, where we want to limit the parallelism
+ * due to file locking in file systems. As "normal" buffered writes
+ * should parellelize on writeout quite nicely, limit us to having 2
+ * pending. This avoids massive contention on the inode when doing
+ * buffered async writes.
+ */
+ ctx->sqo_wq[1] = alloc_workqueue("io_ring-write-wq",
+ WQ_UNBOUND | WQ_FREEZABLE, 2);
+ if (!ctx->sqo_wq[1]) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ return 0;
+err:
+ io_finish_async(ctx);
+ mmdrop(ctx->sqo_mm);
+ ctx->sqo_mm = NULL;
+ return ret;
+}
+
+static void io_unaccount_mem(struct user_struct *user, unsigned long nr_pages)
+{
+ atomic_long_sub(nr_pages, &user->locked_vm);
+}
+
+static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
+{
+ unsigned long page_limit, cur_pages, new_pages;
+
+ /* Don't allow more pages than we can safely lock */
+ page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+
+ do {
+ cur_pages = atomic_long_read(&user->locked_vm);
+ new_pages = cur_pages + nr_pages;
+ if (new_pages > page_limit)
+ return -ENOMEM;
+ } while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
+ new_pages) != cur_pages);
+
+ return 0;
+}
+
+static void io_mem_free(void *ptr)
+{
+ struct page *page;
+
+ if (!ptr)
+ return;
+
+ page = virt_to_head_page(ptr);
+ if (put_page_testzero(page))
+ free_compound_page(page);
+}
+
+static void *io_mem_alloc(size_t size)
+{
+ gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP |
+ __GFP_NORETRY;
+
+ return (void *) __get_free_pages(gfp_flags, get_order(size));
+}
+
+static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
+ size_t *sq_offset)
+{
+ struct io_rings *rings;
+ size_t off, sq_array_size;
+
+ off = struct_size(rings, cqes, cq_entries);
+ if (off == SIZE_MAX)
+ return SIZE_MAX;
+
+#ifdef CONFIG_SMP
+ off = ALIGN(off, SMP_CACHE_BYTES);
+ if (off == 0)
+ return SIZE_MAX;
+#endif
+
+ sq_array_size = array_size(sizeof(u32), sq_entries);
+ if (sq_array_size == SIZE_MAX)
+ return SIZE_MAX;
+
+ if (check_add_overflow(off, sq_array_size, &off))
+ return SIZE_MAX;
+
+ if (sq_offset)
+ *sq_offset = off;
+
+ return off;
+}
+
+static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
+{
+ size_t pages;
+
+ pages = (size_t)1 << get_order(
+ rings_size(sq_entries, cq_entries, NULL));
+ pages += (size_t)1 << get_order(
+ array_size(sizeof(struct io_uring_sqe), sq_entries));
+
+ return pages;
+}
+
+static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
+{
+ int i, j;
+
+ if (!ctx->user_bufs)
+ return -ENXIO;
+
+ for (i = 0; i < ctx->nr_user_bufs; i++) {
+ struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
+
+ for (j = 0; j < imu->nr_bvecs; j++)
+ put_user_page(imu->bvec[j].bv_page);
+
+ if (ctx->account_mem)
+ io_unaccount_mem(ctx->user, imu->nr_bvecs);
+ kvfree(imu->bvec);
+ imu->nr_bvecs = 0;
+ }
+
+ kfree(ctx->user_bufs);
+ ctx->user_bufs = NULL;
+ ctx->nr_user_bufs = 0;
+ return 0;
+}
+
+static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
+ void __user *arg, unsigned index)
+{
+ struct iovec __user *src;
+
+#ifdef CONFIG_COMPAT
+ if (ctx->compat) {
+ struct compat_iovec __user *ciovs;
+ struct compat_iovec ciov;
+
+ ciovs = (struct compat_iovec __user *) arg;
+ if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
+ return -EFAULT;
+
+ dst->iov_base = (void __user *) (unsigned long) ciov.iov_base;
+ dst->iov_len = ciov.iov_len;
+ return 0;
+ }
+#endif
+ src = (struct iovec __user *) arg;
+ if (copy_from_user(dst, &src[index], sizeof(*dst)))
+ return -EFAULT;
+ return 0;
+}
+
+static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
+ unsigned nr_args)
+{
+ struct vm_area_struct **vmas = NULL;
+ struct page **pages = NULL;
+ int i, j, got_pages = 0;
+ int ret = -EINVAL;
+
+ if (ctx->user_bufs)
+ return -EBUSY;
+ if (!nr_args || nr_args > UIO_MAXIOV)
+ return -EINVAL;
+
+ ctx->user_bufs = kcalloc(nr_args, sizeof(struct io_mapped_ubuf),
+ GFP_KERNEL);
+ if (!ctx->user_bufs)
+ return -ENOMEM;
+
+ for (i = 0; i < nr_args; i++) {
+ struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
+ unsigned long off, start, end, ubuf;
+ int pret, nr_pages;
+ struct iovec iov;
+ size_t size;
+
+ ret = io_copy_iov(ctx, &iov, arg, i);
+ if (ret)
+ goto err;
+
+ /*
+ * Don't impose further limits on the size and buffer
+ * constraints here, we'll -EINVAL later when IO is
+ * submitted if they are wrong.
+ */
+ ret = -EFAULT;
+ if (!iov.iov_base || !iov.iov_len)
+ goto err;
+
+ /* arbitrary limit, but we need something */
+ if (iov.iov_len > SZ_1G)
+ goto err;
+
+ ubuf = (unsigned long) iov.iov_base;
+ end = (ubuf + iov.iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+ start = ubuf >> PAGE_SHIFT;
+ nr_pages = end - start;
+
+ if (ctx->account_mem) {
+ ret = io_account_mem(ctx->user, nr_pages);
+ if (ret)
+ goto err;
+ }
+
+ ret = 0;
+ if (!pages || nr_pages > got_pages) {
+ kfree(vmas);
+ kfree(pages);
+ pages = kvmalloc_array(nr_pages, sizeof(struct page *),
+ GFP_KERNEL);
+ vmas = kvmalloc_array(nr_pages,
+ sizeof(struct vm_area_struct *),
+ GFP_KERNEL);
+ if (!pages || !vmas) {
+ ret = -ENOMEM;
+ if (ctx->account_mem)
+ io_unaccount_mem(ctx->user, nr_pages);
+ goto err;
+ }
+ got_pages = nr_pages;
+ }
+
+ imu->bvec = kvmalloc_array(nr_pages, sizeof(struct bio_vec),
+ GFP_KERNEL);
+ ret = -ENOMEM;
+ if (!imu->bvec) {
+ if (ctx->account_mem)
+ io_unaccount_mem(ctx->user, nr_pages);
+ goto err;
+ }
+
+ ret = 0;
+ down_read(¤t->mm->mmap_sem);
+ pret = get_user_pages(ubuf, nr_pages,
+ FOLL_WRITE | FOLL_LONGTERM,
+ pages, vmas);
+ if (pret == nr_pages) {
+ /* don't support file backed memory */
+ for (j = 0; j < nr_pages; j++) {
+ struct vm_area_struct *vma = vmas[j];
+
+ if (vma->vm_file &&
+ !is_file_hugepages(vma->vm_file)) {
+ ret = -EOPNOTSUPP;
+ break;
+ }
+ }
+ } else {
+ ret = pret < 0 ? pret : -EFAULT;
+ }
+ up_read(¤t->mm->mmap_sem);
+ if (ret) {
+ /*
+ * if we did partial map, or found file backed vmas,
+ * release any pages we did get
+ */
+ if (pret > 0)
+ put_user_pages(pages, pret);
+ if (ctx->account_mem)
+ io_unaccount_mem(ctx->user, nr_pages);
+ kvfree(imu->bvec);
+ goto err;
+ }
+
+ off = ubuf & ~PAGE_MASK;
+ size = iov.iov_len;
+ for (j = 0; j < nr_pages; j++) {
+ size_t vec_len;
+
+ vec_len = min_t(size_t, size, PAGE_SIZE - off);
+ imu->bvec[j].bv_page = pages[j];
+ imu->bvec[j].bv_len = vec_len;
+ imu->bvec[j].bv_offset = off;
+ off = 0;
+ size -= vec_len;
+ }
+ /* store original address for later verification */
+ imu->ubuf = ubuf;
+ imu->len = iov.iov_len;
+ imu->nr_bvecs = nr_pages;
+
+ ctx->nr_user_bufs++;
+ }
+ kvfree(pages);
+ kvfree(vmas);
+ return 0;
+err:
+ kvfree(pages);
+ kvfree(vmas);
+ io_sqe_buffer_unregister(ctx);
+ return ret;
+}
+
+static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg)
+{
+ __s32 __user *fds = arg;
+ int fd;
+
+ if (ctx->cq_ev_fd)
+ return -EBUSY;
+
+ if (copy_from_user(&fd, fds, sizeof(*fds)))
+ return -EFAULT;
+
+ ctx->cq_ev_fd = eventfd_ctx_fdget(fd);
+ if (IS_ERR(ctx->cq_ev_fd)) {
+ int ret = PTR_ERR(ctx->cq_ev_fd);
+ ctx->cq_ev_fd = NULL;
+ return ret;
+ }
+
+ return 0;
+}
+
+static int io_eventfd_unregister(struct io_ring_ctx *ctx)
+{
+ if (ctx->cq_ev_fd) {
+ eventfd_ctx_put(ctx->cq_ev_fd);
+ ctx->cq_ev_fd = NULL;
+ return 0;
+ }
+
+ return -ENXIO;
+}
+
+static void io_ring_ctx_free(struct io_ring_ctx *ctx)
+{
+ io_finish_async(ctx);
+ if (ctx->sqo_mm)
+ mmdrop(ctx->sqo_mm);
+
+ io_iopoll_reap_events(ctx);
+ io_sqe_buffer_unregister(ctx);
+ io_sqe_files_unregister(ctx);
+ io_eventfd_unregister(ctx);
+
+#if defined(CONFIG_UNIX)
+ if (ctx->ring_sock) {
+ ctx->ring_sock->file = NULL; /* so that iput() is called */
+ sock_release(ctx->ring_sock);
+ }
+#endif
+
+ io_mem_free(ctx->rings);
+ io_mem_free(ctx->sq_sqes);
+
+ percpu_ref_exit(&ctx->refs);
+ if (ctx->account_mem)
+ io_unaccount_mem(ctx->user,
+ ring_pages(ctx->sq_entries, ctx->cq_entries));
+ free_uid(ctx->user);
+ if (ctx->creds)
+ put_cred(ctx->creds);
+ kfree(ctx);
+}
+
+static __poll_t io_uring_poll(struct file *file, poll_table *wait)
+{
+ struct io_ring_ctx *ctx = file->private_data;
+ __poll_t mask = 0;
+
+ poll_wait(file, &ctx->cq_wait, wait);
+ /*
+ * synchronizes with barrier from wq_has_sleeper call in
+ * io_commit_cqring
+ */
+ smp_rmb();
+ if (READ_ONCE(ctx->rings->sq.tail) - ctx->cached_sq_head !=
+ ctx->rings->sq_ring_entries)
+ mask |= EPOLLOUT | EPOLLWRNORM;
+ if (READ_ONCE(ctx->rings->cq.head) != ctx->cached_cq_tail)
+ mask |= EPOLLIN | EPOLLRDNORM;
+
+ return mask;
+}
+
+static int io_uring_fasync(int fd, struct file *file, int on)
+{
+ struct io_ring_ctx *ctx = file->private_data;
+
+ return fasync_helper(fd, file, on, &ctx->cq_fasync);
+}
+
+static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
+{
+ mutex_lock(&ctx->uring_lock);
+ percpu_ref_kill(&ctx->refs);
+ mutex_unlock(&ctx->uring_lock);
+
+ io_kill_timeouts(ctx);
+ io_poll_remove_all(ctx);
+ io_iopoll_reap_events(ctx);
+ wait_for_completion(&ctx->ctx_done);
+ io_ring_ctx_free(ctx);
+}
+
+static int io_uring_release(struct inode *inode, struct file *file)
+{
+ struct io_ring_ctx *ctx = file->private_data;
+
+ file->private_data = NULL;
+ io_ring_ctx_wait_and_kill(ctx);
+ return 0;
+}
+
+static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+ loff_t offset = (loff_t) vma->vm_pgoff << PAGE_SHIFT;
+ unsigned long sz = vma->vm_end - vma->vm_start;
+ struct io_ring_ctx *ctx = file->private_data;
+ unsigned long pfn;
+ struct page *page;
+ void *ptr;
+
+ switch (offset) {
+ case IORING_OFF_SQ_RING:
+ case IORING_OFF_CQ_RING:
+ ptr = ctx->rings;
+ break;
+ case IORING_OFF_SQES:
+ ptr = ctx->sq_sqes;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ page = virt_to_head_page(ptr);
+ if (sz > page_size(page))
+ return -EINVAL;
+
+ pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
+ return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
+}
+
+SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
+ u32, min_complete, u32, flags, const sigset_t __user *, sig,
+ size_t, sigsz)
+{
+ struct io_ring_ctx *ctx;
+ long ret = -EBADF;
+ int submitted = 0;
+ struct fd f;
+
+ if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP))
+ return -EINVAL;
+
+ f = fdget(fd);
+ if (!f.file)
+ return -EBADF;
+
+ ret = -EOPNOTSUPP;
+ if (f.file->f_op != &io_uring_fops)
+ goto out_fput;
+
+ ret = -ENXIO;
+ ctx = f.file->private_data;
+ 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.
+ */
+ ret = 0;
+ if (ctx->flags & IORING_SETUP_SQPOLL) {
+ if (flags & IORING_ENTER_SQ_WAKEUP)
+ wake_up(&ctx->sqo_wait);
+ submitted = to_submit;
+ } else if (to_submit) {
+ to_submit = min(to_submit, ctx->sq_entries);
+
+ mutex_lock(&ctx->uring_lock);
+ submitted = io_ring_submit(ctx, to_submit);
+ mutex_unlock(&ctx->uring_lock);
+ }
+ if (flags & IORING_ENTER_GETEVENTS) {
+ unsigned nr_events = 0;
+
+ min_complete = min(min_complete, ctx->cq_entries);
+
+ if (ctx->flags & IORING_SETUP_IOPOLL) {
+ ret = io_iopoll_check(ctx, &nr_events, min_complete);
+ } else {
+ ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
+ }
+ }
+
+ percpu_ref_put(&ctx->refs);
+out_fput:
+ fdput(f);
+ return submitted ? submitted : ret;
+}
+
+static const struct file_operations io_uring_fops = {
+ .release = io_uring_release,
+ .mmap = io_uring_mmap,
+ .poll = io_uring_poll,
+ .fasync = io_uring_fasync,
+};
+
+static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
+ struct io_uring_params *p)
+{
+ struct io_rings *rings;
+ size_t size, sq_array_offset;
+
+ size = rings_size(p->sq_entries, p->cq_entries, &sq_array_offset);
+ if (size == SIZE_MAX)
+ return -EOVERFLOW;
+
+ rings = io_mem_alloc(size);
+ if (!rings)
+ return -ENOMEM;
+
+ ctx->rings = rings;
+ ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
+ rings->sq_ring_mask = p->sq_entries - 1;
+ rings->cq_ring_mask = p->cq_entries - 1;
+ rings->sq_ring_entries = p->sq_entries;
+ rings->cq_ring_entries = p->cq_entries;
+ ctx->sq_mask = rings->sq_ring_mask;
+ ctx->cq_mask = rings->cq_ring_mask;
+ ctx->sq_entries = rings->sq_ring_entries;
+ ctx->cq_entries = rings->cq_ring_entries;
+
+ size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
+ if (size == SIZE_MAX)
+ return -EOVERFLOW;
+
+ ctx->sq_sqes = io_mem_alloc(size);
+ if (!ctx->sq_sqes)
+ return -ENOMEM;
+
+ return 0;
+}
+
+/*
+ * Allocate an anonymous fd, this is what constitutes the application
+ * visible backing of an io_uring instance. The application mmaps this
+ * fd to gain access to the SQ/CQ ring details. If UNIX sockets are enabled,
+ * we have to tie this fd to a socket for file garbage collection purposes.
+ */
+static int io_uring_get_fd(struct io_ring_ctx *ctx)
+{
+ struct file *file;
+ int ret;
+
+#if defined(CONFIG_UNIX)
+ ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
+ &ctx->ring_sock);
+ if (ret)
+ return ret;
+#endif
+
+ ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+ if (ret < 0)
+ goto err;
+
+ file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
+ O_RDWR | O_CLOEXEC);
+ if (IS_ERR(file)) {
+ put_unused_fd(ret);
+ ret = PTR_ERR(file);
+ goto err;
+ }
+
+#if defined(CONFIG_UNIX)
+ ctx->ring_sock->file = file;
+ ctx->ring_sock->sk->sk_user_data = ctx;
+#endif
+ fd_install(ret, file);
+ return ret;
+err:
+#if defined(CONFIG_UNIX)
+ sock_release(ctx->ring_sock);
+ ctx->ring_sock = NULL;
+#endif
+ return ret;
+}
+
+static int io_uring_create(unsigned entries, struct io_uring_params *p)
+{
+ struct user_struct *user = NULL;
+ struct io_ring_ctx *ctx;
+ bool account_mem;
+ int ret;
+
+ if (!entries || entries > IORING_MAX_ENTRIES)
+ return -EINVAL;
+
+ /*
+ * Use twice as many entries for the CQ ring. It's possible for the
+ * application to drive a higher depth than the size of the SQ ring,
+ * since the sqes are only used at submission time. This allows for
+ * some flexibility in overcommitting a bit.
+ */
+ p->sq_entries = roundup_pow_of_two(entries);
+ p->cq_entries = 2 * p->sq_entries;
+
+ user = get_uid(current_user());
+ account_mem = !capable(CAP_IPC_LOCK);
+
+ if (account_mem) {
+ ret = io_account_mem(user,
+ ring_pages(p->sq_entries, p->cq_entries));
+ if (ret) {
+ free_uid(user);
+ return ret;
+ }
+ }
+
+ ctx = io_ring_ctx_alloc(p);
+ if (!ctx) {
+ if (account_mem)
+ io_unaccount_mem(user, ring_pages(p->sq_entries,
+ p->cq_entries));
+ free_uid(user);
+ return -ENOMEM;
+ }
+ ctx->compat = in_compat_syscall();
+ ctx->account_mem = account_mem;
+ ctx->user = user;
+
+ ctx->creds = prepare_creds();
+ if (!ctx->creds) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ ret = io_allocate_scq_urings(ctx, p);
+ if (ret)
+ goto err;
+
+ ret = io_sq_offload_start(ctx, p);
+ if (ret)
+ goto err;
+
+ memset(&p->sq_off, 0, sizeof(p->sq_off));
+ p->sq_off.head = offsetof(struct io_rings, sq.head);
+ p->sq_off.tail = offsetof(struct io_rings, sq.tail);
+ p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
+ p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
+ p->sq_off.flags = offsetof(struct io_rings, sq_flags);
+ p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
+ p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
+
+ memset(&p->cq_off, 0, sizeof(p->cq_off));
+ p->cq_off.head = offsetof(struct io_rings, cq.head);
+ p->cq_off.tail = offsetof(struct io_rings, cq.tail);
+ p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
+ p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
+ p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
+ p->cq_off.cqes = offsetof(struct io_rings, cqes);
+
+ /*
+ * Install ring fd as the very last thing, so we don't risk someone
+ * having closed it before we finish setup
+ */
+ ret = io_uring_get_fd(ctx);
+ if (ret < 0)
+ goto err;
+
+ p->features = IORING_FEAT_SINGLE_MMAP;
+ return ret;
+err:
+ io_ring_ctx_wait_and_kill(ctx);
+ return ret;
+}
+
+/*
+ * Sets up an aio uring context, and returns the fd. Applications asks for a
+ * ring size, we return the actual sq/cq ring sizes (among other things) in the
+ * params structure passed in.
+ */
+static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
+{
+ struct io_uring_params p;
+ long ret;
+ int i;
+
+ if (copy_from_user(&p, params, sizeof(p)))
+ return -EFAULT;
+ for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
+ if (p.resv[i])
+ return -EINVAL;
+ }
+
+ if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
+ IORING_SETUP_SQ_AFF))
+ return -EINVAL;
+
+ ret = io_uring_create(entries, &p);
+ if (ret < 0)
+ return ret;
+
+ if (copy_to_user(params, &p, sizeof(p)))
+ return -EFAULT;
+
+ return ret;
+}
+
+SYSCALL_DEFINE2(io_uring_setup, u32, entries,
+ struct io_uring_params __user *, params)
+{
+ return io_uring_setup(entries, params);
+}
+
+static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
+ void __user *arg, unsigned nr_args)
+ __releases(ctx->uring_lock)
+ __acquires(ctx->uring_lock)
+{
+ int ret;
+
+ /*
+ * We're inside the ring mutex, if the ref is already dying, then
+ * someone else killed the ctx or is already going through
+ * io_uring_register().
+ */
+ if (percpu_ref_is_dying(&ctx->refs))
+ return -ENXIO;
+
+ percpu_ref_kill(&ctx->refs);
+
+ /*
+ * Drop uring mutex before waiting for references to exit. If another
+ * thread is currently inside io_uring_enter() it might need to grab
+ * the uring_lock to make progress. If we hold it here across the drain
+ * wait, then we can deadlock. It's safe to drop the mutex here, since
+ * no new references will come in after we've killed the percpu ref.
+ */
+ mutex_unlock(&ctx->uring_lock);
+ wait_for_completion(&ctx->ctx_done);
+ mutex_lock(&ctx->uring_lock);
+
+ switch (opcode) {
+ case IORING_REGISTER_BUFFERS:
+ ret = io_sqe_buffer_register(ctx, arg, nr_args);
+ break;
+ case IORING_UNREGISTER_BUFFERS:
+ ret = -EINVAL;
+ if (arg || nr_args)
+ break;
+ ret = io_sqe_buffer_unregister(ctx);
+ break;
+ case IORING_REGISTER_FILES:
+ ret = io_sqe_files_register(ctx, arg, nr_args);
+ break;
+ case IORING_UNREGISTER_FILES:
+ ret = -EINVAL;
+ if (arg || nr_args)
+ break;
+ ret = io_sqe_files_unregister(ctx);
+ break;
+ case IORING_REGISTER_EVENTFD:
+ ret = -EINVAL;
+ if (nr_args != 1)
+ break;
+ ret = io_eventfd_register(ctx, arg);
+ break;
+ case IORING_UNREGISTER_EVENTFD:
+ ret = -EINVAL;
+ if (arg || nr_args)
+ break;
+ ret = io_eventfd_unregister(ctx);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ /* bring the ctx back to life */
+ reinit_completion(&ctx->ctx_done);
+ percpu_ref_reinit(&ctx->refs);
+ return ret;
+}
+
+SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
+ void __user *, arg, unsigned int, nr_args)
+{
+ struct io_ring_ctx *ctx;
+ long ret = -EBADF;
+ struct fd f;
+
+ f = fdget(fd);
+ if (!f.file)
+ return -EBADF;
+
+ ret = -EOPNOTSUPP;
+ if (f.file->f_op != &io_uring_fops)
+ goto out_fput;
+
+ ctx = f.file->private_data;
+
+ mutex_lock(&ctx->uring_lock);
+ ret = __io_uring_register(ctx, opcode, arg, nr_args);
+ mutex_unlock(&ctx->uring_lock);
+out_fput:
+ fdput(f);
+ return ret;
+}
+
+static int __init io_uring_init(void)
+{
+ req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
+ return 0;
+};
+__initcall(io_uring_init);