From ace9429bb58fd418f0c81d4c2835699bddf6bde6 Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Thu, 11 Apr 2024 10:27:49 +0200
Subject: Adding upstream version 6.6.15.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 io_uring/io_uring.c | 4729 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 4729 insertions(+)
 create mode 100644 io_uring/io_uring.c

(limited to 'io_uring/io_uring.c')

diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
new file mode 100644
index 000000000..ea772a02c
--- /dev/null
+++ b/io_uring/io_uring.c
@@ -0,0 +1,4729 @@
+// 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_cqe (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 <net/compat.h>
+#include <linux/refcount.h>
+#include <linux/uio.h>
+#include <linux/bits.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/percpu.h>
+#include <linux/slab.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/highmem.h>
+#include <linux/fsnotify.h>
+#include <linux/fadvise.h>
+#include <linux/task_work.h>
+#include <linux/io_uring.h>
+#include <linux/audit.h>
+#include <linux/security.h>
+#include <asm/shmparam.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "io-wq.h"
+
+#include "io_uring.h"
+#include "opdef.h"
+#include "refs.h"
+#include "tctx.h"
+#include "sqpoll.h"
+#include "fdinfo.h"
+#include "kbuf.h"
+#include "rsrc.h"
+#include "cancel.h"
+#include "net.h"
+#include "notif.h"
+
+#include "timeout.h"
+#include "poll.h"
+#include "rw.h"
+#include "alloc_cache.h"
+
+#define IORING_MAX_ENTRIES	32768
+#define IORING_MAX_CQ_ENTRIES	(2 * IORING_MAX_ENTRIES)
+
+#define IORING_MAX_RESTRICTIONS	(IORING_RESTRICTION_LAST + \
+				 IORING_REGISTER_LAST + IORING_OP_LAST)
+
+#define SQE_COMMON_FLAGS (IOSQE_FIXED_FILE | IOSQE_IO_LINK | \
+			  IOSQE_IO_HARDLINK | IOSQE_ASYNC)
+
+#define SQE_VALID_FLAGS	(SQE_COMMON_FLAGS | IOSQE_BUFFER_SELECT | \
+			IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS)
+
+#define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \
+				REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS | \
+				REQ_F_ASYNC_DATA)
+
+#define IO_REQ_CLEAN_SLOW_FLAGS (REQ_F_REFCOUNT | REQ_F_LINK | REQ_F_HARDLINK |\
+				 IO_REQ_CLEAN_FLAGS)
+
+#define IO_TCTX_REFS_CACHE_NR	(1U << 10)
+
+#define IO_COMPL_BATCH			32
+#define IO_REQ_ALLOC_BATCH		8
+
+enum {
+	IO_CHECK_CQ_OVERFLOW_BIT,
+	IO_CHECK_CQ_DROPPED_BIT,
+};
+
+enum {
+	IO_EVENTFD_OP_SIGNAL_BIT,
+	IO_EVENTFD_OP_FREE_BIT,
+};
+
+struct io_defer_entry {
+	struct list_head	list;
+	struct io_kiocb		*req;
+	u32			seq;
+};
+
+/* requests with any of those set should undergo io_disarm_next() */
+#define IO_DISARM_MASK (REQ_F_ARM_LTIMEOUT | REQ_F_LINK_TIMEOUT | REQ_F_FAIL)
+#define IO_REQ_LINK_FLAGS (REQ_F_LINK | REQ_F_HARDLINK)
+
+static bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
+					 struct task_struct *task,
+					 bool cancel_all);
+
+static void io_queue_sqe(struct io_kiocb *req);
+
+struct kmem_cache *req_cachep;
+
+static int __read_mostly sysctl_io_uring_disabled;
+static int __read_mostly sysctl_io_uring_group = -1;
+
+#ifdef CONFIG_SYSCTL
+static struct ctl_table kernel_io_uring_disabled_table[] = {
+	{
+		.procname	= "io_uring_disabled",
+		.data		= &sysctl_io_uring_disabled,
+		.maxlen		= sizeof(sysctl_io_uring_disabled),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_TWO,
+	},
+	{
+		.procname	= "io_uring_group",
+		.data		= &sysctl_io_uring_group,
+		.maxlen		= sizeof(gid_t),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec,
+	},
+	{},
+};
+#endif
+
+struct sock *io_uring_get_socket(struct file *file)
+{
+#if defined(CONFIG_UNIX)
+	if (io_is_uring_fops(file)) {
+		struct io_ring_ctx *ctx = file->private_data;
+
+		return ctx->ring_sock->sk;
+	}
+#endif
+	return NULL;
+}
+EXPORT_SYMBOL(io_uring_get_socket);
+
+static inline void io_submit_flush_completions(struct io_ring_ctx *ctx)
+{
+	if (!wq_list_empty(&ctx->submit_state.compl_reqs) ||
+	    ctx->submit_state.cqes_count)
+		__io_submit_flush_completions(ctx);
+}
+
+static inline unsigned int __io_cqring_events(struct io_ring_ctx *ctx)
+{
+	return ctx->cached_cq_tail - READ_ONCE(ctx->rings->cq.head);
+}
+
+static inline unsigned int __io_cqring_events_user(struct io_ring_ctx *ctx)
+{
+	return READ_ONCE(ctx->rings->cq.tail) - READ_ONCE(ctx->rings->cq.head);
+}
+
+static bool io_match_linked(struct io_kiocb *head)
+{
+	struct io_kiocb *req;
+
+	io_for_each_link(req, head) {
+		if (req->flags & REQ_F_INFLIGHT)
+			return true;
+	}
+	return false;
+}
+
+/*
+ * As io_match_task() but protected against racing with linked timeouts.
+ * User must not hold timeout_lock.
+ */
+bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task,
+			bool cancel_all)
+{
+	bool matched;
+
+	if (task && head->task != task)
+		return false;
+	if (cancel_all)
+		return true;
+
+	if (head->flags & REQ_F_LINK_TIMEOUT) {
+		struct io_ring_ctx *ctx = head->ctx;
+
+		/* protect against races with linked timeouts */
+		spin_lock_irq(&ctx->timeout_lock);
+		matched = io_match_linked(head);
+		spin_unlock_irq(&ctx->timeout_lock);
+	} else {
+		matched = io_match_linked(head);
+	}
+	return matched;
+}
+
+static inline void req_fail_link_node(struct io_kiocb *req, int res)
+{
+	req_set_fail(req);
+	io_req_set_res(req, res, 0);
+}
+
+static inline void io_req_add_to_cache(struct io_kiocb *req, struct io_ring_ctx *ctx)
+{
+	wq_stack_add_head(&req->comp_list, &ctx->submit_state.free_list);
+}
+
+static __cold 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->ref_comp);
+}
+
+static __cold void io_fallback_req_func(struct work_struct *work)
+{
+	struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx,
+						fallback_work.work);
+	struct llist_node *node = llist_del_all(&ctx->fallback_llist);
+	struct io_kiocb *req, *tmp;
+	struct io_tw_state ts = { .locked = true, };
+
+	percpu_ref_get(&ctx->refs);
+	mutex_lock(&ctx->uring_lock);
+	llist_for_each_entry_safe(req, tmp, node, io_task_work.node)
+		req->io_task_work.func(req, &ts);
+	if (WARN_ON_ONCE(!ts.locked))
+		return;
+	io_submit_flush_completions(ctx);
+	mutex_unlock(&ctx->uring_lock);
+	percpu_ref_put(&ctx->refs);
+}
+
+static int io_alloc_hash_table(struct io_hash_table *table, unsigned bits)
+{
+	unsigned hash_buckets = 1U << bits;
+	size_t hash_size = hash_buckets * sizeof(table->hbs[0]);
+
+	table->hbs = kmalloc(hash_size, GFP_KERNEL);
+	if (!table->hbs)
+		return -ENOMEM;
+
+	table->hash_bits = bits;
+	init_hash_table(table, hash_buckets);
+	return 0;
+}
+
+static __cold struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
+{
+	struct io_ring_ctx *ctx;
+	int hash_bits;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	xa_init(&ctx->io_bl_xa);
+
+	/*
+	 * Use 5 bits less than the max cq entries, that should give us around
+	 * 32 entries per hash list if totally full and uniformly spread, but
+	 * don't keep too many buckets to not overconsume memory.
+	 */
+	hash_bits = ilog2(p->cq_entries) - 5;
+	hash_bits = clamp(hash_bits, 1, 8);
+	if (io_alloc_hash_table(&ctx->cancel_table, hash_bits))
+		goto err;
+	if (io_alloc_hash_table(&ctx->cancel_table_locked, hash_bits))
+		goto err;
+	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
+			    0, GFP_KERNEL))
+		goto err;
+
+	ctx->flags = p->flags;
+	init_waitqueue_head(&ctx->sqo_sq_wait);
+	INIT_LIST_HEAD(&ctx->sqd_list);
+	INIT_LIST_HEAD(&ctx->cq_overflow_list);
+	INIT_LIST_HEAD(&ctx->io_buffers_cache);
+	INIT_HLIST_HEAD(&ctx->io_buf_list);
+	io_alloc_cache_init(&ctx->rsrc_node_cache, IO_NODE_ALLOC_CACHE_MAX,
+			    sizeof(struct io_rsrc_node));
+	io_alloc_cache_init(&ctx->apoll_cache, IO_ALLOC_CACHE_MAX,
+			    sizeof(struct async_poll));
+	io_alloc_cache_init(&ctx->netmsg_cache, IO_ALLOC_CACHE_MAX,
+			    sizeof(struct io_async_msghdr));
+	init_completion(&ctx->ref_comp);
+	xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
+	mutex_init(&ctx->uring_lock);
+	init_waitqueue_head(&ctx->cq_wait);
+	init_waitqueue_head(&ctx->poll_wq);
+	init_waitqueue_head(&ctx->rsrc_quiesce_wq);
+	spin_lock_init(&ctx->completion_lock);
+	spin_lock_init(&ctx->timeout_lock);
+	INIT_WQ_LIST(&ctx->iopoll_list);
+	INIT_LIST_HEAD(&ctx->io_buffers_pages);
+	INIT_LIST_HEAD(&ctx->io_buffers_comp);
+	INIT_LIST_HEAD(&ctx->defer_list);
+	INIT_LIST_HEAD(&ctx->timeout_list);
+	INIT_LIST_HEAD(&ctx->ltimeout_list);
+	INIT_LIST_HEAD(&ctx->rsrc_ref_list);
+	init_llist_head(&ctx->work_llist);
+	INIT_LIST_HEAD(&ctx->tctx_list);
+	ctx->submit_state.free_list.next = NULL;
+	INIT_WQ_LIST(&ctx->locked_free_list);
+	INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
+	INIT_WQ_LIST(&ctx->submit_state.compl_reqs);
+	return ctx;
+err:
+	kfree(ctx->cancel_table.hbs);
+	kfree(ctx->cancel_table_locked.hbs);
+	kfree(ctx->io_bl);
+	xa_destroy(&ctx->io_bl_xa);
+	kfree(ctx);
+	return NULL;
+}
+
+static void io_account_cq_overflow(struct io_ring_ctx *ctx)
+{
+	struct io_rings *r = ctx->rings;
+
+	WRITE_ONCE(r->cq_overflow, READ_ONCE(r->cq_overflow) + 1);
+	ctx->cq_extra--;
+}
+
+static bool req_need_defer(struct io_kiocb *req, u32 seq)
+{
+	if (unlikely(req->flags & REQ_F_IO_DRAIN)) {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		return seq + READ_ONCE(ctx->cq_extra) != ctx->cached_cq_tail;
+	}
+
+	return false;
+}
+
+static void io_clean_op(struct io_kiocb *req)
+{
+	if (req->flags & REQ_F_BUFFER_SELECTED) {
+		spin_lock(&req->ctx->completion_lock);
+		io_put_kbuf_comp(req);
+		spin_unlock(&req->ctx->completion_lock);
+	}
+
+	if (req->flags & REQ_F_NEED_CLEANUP) {
+		const struct io_cold_def *def = &io_cold_defs[req->opcode];
+
+		if (def->cleanup)
+			def->cleanup(req);
+	}
+	if ((req->flags & REQ_F_POLLED) && req->apoll) {
+		kfree(req->apoll->double_poll);
+		kfree(req->apoll);
+		req->apoll = NULL;
+	}
+	if (req->flags & REQ_F_INFLIGHT) {
+		struct io_uring_task *tctx = req->task->io_uring;
+
+		atomic_dec(&tctx->inflight_tracked);
+	}
+	if (req->flags & REQ_F_CREDS)
+		put_cred(req->creds);
+	if (req->flags & REQ_F_ASYNC_DATA) {
+		kfree(req->async_data);
+		req->async_data = NULL;
+	}
+	req->flags &= ~IO_REQ_CLEAN_FLAGS;
+}
+
+static inline void io_req_track_inflight(struct io_kiocb *req)
+{
+	if (!(req->flags & REQ_F_INFLIGHT)) {
+		req->flags |= REQ_F_INFLIGHT;
+		atomic_inc(&req->task->io_uring->inflight_tracked);
+	}
+}
+
+static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
+{
+	if (WARN_ON_ONCE(!req->link))
+		return NULL;
+
+	req->flags &= ~REQ_F_ARM_LTIMEOUT;
+	req->flags |= REQ_F_LINK_TIMEOUT;
+
+	/* linked timeouts should have two refs once prep'ed */
+	io_req_set_refcount(req);
+	__io_req_set_refcount(req->link, 2);
+	return req->link;
+}
+
+static inline struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
+{
+	if (likely(!(req->flags & REQ_F_ARM_LTIMEOUT)))
+		return NULL;
+	return __io_prep_linked_timeout(req);
+}
+
+static noinline void __io_arm_ltimeout(struct io_kiocb *req)
+{
+	io_queue_linked_timeout(__io_prep_linked_timeout(req));
+}
+
+static inline void io_arm_ltimeout(struct io_kiocb *req)
+{
+	if (unlikely(req->flags & REQ_F_ARM_LTIMEOUT))
+		__io_arm_ltimeout(req);
+}
+
+static void io_prep_async_work(struct io_kiocb *req)
+{
+	const struct io_issue_def *def = &io_issue_defs[req->opcode];
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (!(req->flags & REQ_F_CREDS)) {
+		req->flags |= REQ_F_CREDS;
+		req->creds = get_current_cred();
+	}
+
+	req->work.list.next = NULL;
+	req->work.flags = 0;
+	req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
+	if (req->flags & REQ_F_FORCE_ASYNC)
+		req->work.flags |= IO_WQ_WORK_CONCURRENT;
+
+	if (req->file && !(req->flags & REQ_F_FIXED_FILE))
+		req->flags |= io_file_get_flags(req->file);
+
+	if (req->file && (req->flags & REQ_F_ISREG)) {
+		bool should_hash = def->hash_reg_file;
+
+		/* don't serialize this request if the fs doesn't need it */
+		if (should_hash && (req->file->f_flags & O_DIRECT) &&
+		    (req->file->f_mode & FMODE_DIO_PARALLEL_WRITE))
+			should_hash = false;
+		if (should_hash || (ctx->flags & IORING_SETUP_IOPOLL))
+			io_wq_hash_work(&req->work, file_inode(req->file));
+	} else if (!req->file || !S_ISBLK(file_inode(req->file)->i_mode)) {
+		if (def->unbound_nonreg_file)
+			req->work.flags |= IO_WQ_WORK_UNBOUND;
+	}
+}
+
+static void io_prep_async_link(struct io_kiocb *req)
+{
+	struct io_kiocb *cur;
+
+	if (req->flags & REQ_F_LINK_TIMEOUT) {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		spin_lock_irq(&ctx->timeout_lock);
+		io_for_each_link(cur, req)
+			io_prep_async_work(cur);
+		spin_unlock_irq(&ctx->timeout_lock);
+	} else {
+		io_for_each_link(cur, req)
+			io_prep_async_work(cur);
+	}
+}
+
+void io_queue_iowq(struct io_kiocb *req, struct io_tw_state *ts_dont_use)
+{
+	struct io_kiocb *link = io_prep_linked_timeout(req);
+	struct io_uring_task *tctx = req->task->io_uring;
+
+	BUG_ON(!tctx);
+	BUG_ON(!tctx->io_wq);
+
+	/* init ->work of the whole link before punting */
+	io_prep_async_link(req);
+
+	/*
+	 * Not expected to happen, but if we do have a bug where this _can_
+	 * happen, catch it here and ensure the request is marked as
+	 * canceled. That will make io-wq go through the usual work cancel
+	 * procedure rather than attempt to run this request (or create a new
+	 * worker for it).
+	 */
+	if (WARN_ON_ONCE(!same_thread_group(req->task, current)))
+		req->work.flags |= IO_WQ_WORK_CANCEL;
+
+	trace_io_uring_queue_async_work(req, io_wq_is_hashed(&req->work));
+	io_wq_enqueue(tctx->io_wq, &req->work);
+	if (link)
+		io_queue_linked_timeout(link);
+}
+
+static __cold void io_queue_deferred(struct io_ring_ctx *ctx)
+{
+	while (!list_empty(&ctx->defer_list)) {
+		struct io_defer_entry *de = list_first_entry(&ctx->defer_list,
+						struct io_defer_entry, list);
+
+		if (req_need_defer(de->req, de->seq))
+			break;
+		list_del_init(&de->list);
+		io_req_task_queue(de->req);
+		kfree(de);
+	}
+}
+
+
+static void io_eventfd_ops(struct rcu_head *rcu)
+{
+	struct io_ev_fd *ev_fd = container_of(rcu, struct io_ev_fd, rcu);
+	int ops = atomic_xchg(&ev_fd->ops, 0);
+
+	if (ops & BIT(IO_EVENTFD_OP_SIGNAL_BIT))
+		eventfd_signal_mask(ev_fd->cq_ev_fd, 1, EPOLL_URING_WAKE);
+
+	/* IO_EVENTFD_OP_FREE_BIT may not be set here depending on callback
+	 * ordering in a race but if references are 0 we know we have to free
+	 * it regardless.
+	 */
+	if (atomic_dec_and_test(&ev_fd->refs)) {
+		eventfd_ctx_put(ev_fd->cq_ev_fd);
+		kfree(ev_fd);
+	}
+}
+
+static void io_eventfd_signal(struct io_ring_ctx *ctx)
+{
+	struct io_ev_fd *ev_fd = NULL;
+
+	rcu_read_lock();
+	/*
+	 * rcu_dereference ctx->io_ev_fd once and use it for both for checking
+	 * and eventfd_signal
+	 */
+	ev_fd = rcu_dereference(ctx->io_ev_fd);
+
+	/*
+	 * Check again if ev_fd exists incase an io_eventfd_unregister call
+	 * completed between the NULL check of ctx->io_ev_fd at the start of
+	 * the function and rcu_read_lock.
+	 */
+	if (unlikely(!ev_fd))
+		goto out;
+	if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
+		goto out;
+	if (ev_fd->eventfd_async && !io_wq_current_is_worker())
+		goto out;
+
+	if (likely(eventfd_signal_allowed())) {
+		eventfd_signal_mask(ev_fd->cq_ev_fd, 1, EPOLL_URING_WAKE);
+	} else {
+		atomic_inc(&ev_fd->refs);
+		if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_SIGNAL_BIT), &ev_fd->ops))
+			call_rcu_hurry(&ev_fd->rcu, io_eventfd_ops);
+		else
+			atomic_dec(&ev_fd->refs);
+	}
+
+out:
+	rcu_read_unlock();
+}
+
+static void io_eventfd_flush_signal(struct io_ring_ctx *ctx)
+{
+	bool skip;
+
+	spin_lock(&ctx->completion_lock);
+
+	/*
+	 * Eventfd should only get triggered when at least one event has been
+	 * posted. Some applications rely on the eventfd notification count
+	 * only changing IFF a new CQE has been added to the CQ ring. There's
+	 * no depedency on 1:1 relationship between how many times this
+	 * function is called (and hence the eventfd count) and number of CQEs
+	 * posted to the CQ ring.
+	 */
+	skip = ctx->cached_cq_tail == ctx->evfd_last_cq_tail;
+	ctx->evfd_last_cq_tail = ctx->cached_cq_tail;
+	spin_unlock(&ctx->completion_lock);
+	if (skip)
+		return;
+
+	io_eventfd_signal(ctx);
+}
+
+void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
+{
+	if (ctx->poll_activated)
+		io_poll_wq_wake(ctx);
+	if (ctx->off_timeout_used)
+		io_flush_timeouts(ctx);
+	if (ctx->drain_active) {
+		spin_lock(&ctx->completion_lock);
+		io_queue_deferred(ctx);
+		spin_unlock(&ctx->completion_lock);
+	}
+	if (ctx->has_evfd)
+		io_eventfd_flush_signal(ctx);
+}
+
+static inline void __io_cq_lock(struct io_ring_ctx *ctx)
+{
+	if (!ctx->lockless_cq)
+		spin_lock(&ctx->completion_lock);
+}
+
+static inline void io_cq_lock(struct io_ring_ctx *ctx)
+	__acquires(ctx->completion_lock)
+{
+	spin_lock(&ctx->completion_lock);
+}
+
+static inline void __io_cq_unlock_post(struct io_ring_ctx *ctx)
+{
+	io_commit_cqring(ctx);
+	if (!ctx->task_complete) {
+		if (!ctx->lockless_cq)
+			spin_unlock(&ctx->completion_lock);
+		/* IOPOLL rings only need to wake up if it's also SQPOLL */
+		if (!ctx->syscall_iopoll)
+			io_cqring_wake(ctx);
+	}
+	io_commit_cqring_flush(ctx);
+}
+
+static void io_cq_unlock_post(struct io_ring_ctx *ctx)
+	__releases(ctx->completion_lock)
+{
+	io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+	io_cqring_wake(ctx);
+	io_commit_cqring_flush(ctx);
+}
+
+/* Returns true if there are no backlogged entries after the flush */
+static void io_cqring_overflow_kill(struct io_ring_ctx *ctx)
+{
+	struct io_overflow_cqe *ocqe;
+	LIST_HEAD(list);
+
+	spin_lock(&ctx->completion_lock);
+	list_splice_init(&ctx->cq_overflow_list, &list);
+	clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
+	spin_unlock(&ctx->completion_lock);
+
+	while (!list_empty(&list)) {
+		ocqe = list_first_entry(&list, struct io_overflow_cqe, list);
+		list_del(&ocqe->list);
+		kfree(ocqe);
+	}
+}
+
+static void __io_cqring_overflow_flush(struct io_ring_ctx *ctx)
+{
+	size_t cqe_size = sizeof(struct io_uring_cqe);
+
+	if (__io_cqring_events(ctx) == ctx->cq_entries)
+		return;
+
+	if (ctx->flags & IORING_SETUP_CQE32)
+		cqe_size <<= 1;
+
+	io_cq_lock(ctx);
+	while (!list_empty(&ctx->cq_overflow_list)) {
+		struct io_uring_cqe *cqe;
+		struct io_overflow_cqe *ocqe;
+
+		if (!io_get_cqe_overflow(ctx, &cqe, true))
+			break;
+		ocqe = list_first_entry(&ctx->cq_overflow_list,
+					struct io_overflow_cqe, list);
+		memcpy(cqe, &ocqe->cqe, cqe_size);
+		list_del(&ocqe->list);
+		kfree(ocqe);
+	}
+
+	if (list_empty(&ctx->cq_overflow_list)) {
+		clear_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
+		atomic_andnot(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
+	}
+	io_cq_unlock_post(ctx);
+}
+
+static void io_cqring_do_overflow_flush(struct io_ring_ctx *ctx)
+{
+	/* iopoll syncs against uring_lock, not completion_lock */
+	if (ctx->flags & IORING_SETUP_IOPOLL)
+		mutex_lock(&ctx->uring_lock);
+	__io_cqring_overflow_flush(ctx);
+	if (ctx->flags & IORING_SETUP_IOPOLL)
+		mutex_unlock(&ctx->uring_lock);
+}
+
+static void io_cqring_overflow_flush(struct io_ring_ctx *ctx)
+{
+	if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
+		io_cqring_do_overflow_flush(ctx);
+}
+
+/* can be called by any task */
+static void io_put_task_remote(struct task_struct *task)
+{
+	struct io_uring_task *tctx = task->io_uring;
+
+	percpu_counter_sub(&tctx->inflight, 1);
+	if (unlikely(atomic_read(&tctx->in_cancel)))
+		wake_up(&tctx->wait);
+	put_task_struct(task);
+}
+
+/* used by a task to put its own references */
+static void io_put_task_local(struct task_struct *task)
+{
+	task->io_uring->cached_refs++;
+}
+
+/* must to be called somewhat shortly after putting a request */
+static inline void io_put_task(struct task_struct *task)
+{
+	if (likely(task == current))
+		io_put_task_local(task);
+	else
+		io_put_task_remote(task);
+}
+
+void io_task_refs_refill(struct io_uring_task *tctx)
+{
+	unsigned int refill = -tctx->cached_refs + IO_TCTX_REFS_CACHE_NR;
+
+	percpu_counter_add(&tctx->inflight, refill);
+	refcount_add(refill, &current->usage);
+	tctx->cached_refs += refill;
+}
+
+static __cold void io_uring_drop_tctx_refs(struct task_struct *task)
+{
+	struct io_uring_task *tctx = task->io_uring;
+	unsigned int refs = tctx->cached_refs;
+
+	if (refs) {
+		tctx->cached_refs = 0;
+		percpu_counter_sub(&tctx->inflight, refs);
+		put_task_struct_many(task, refs);
+	}
+}
+
+static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
+				     s32 res, u32 cflags, u64 extra1, u64 extra2)
+{
+	struct io_overflow_cqe *ocqe;
+	size_t ocq_size = sizeof(struct io_overflow_cqe);
+	bool is_cqe32 = (ctx->flags & IORING_SETUP_CQE32);
+
+	lockdep_assert_held(&ctx->completion_lock);
+
+	if (is_cqe32)
+		ocq_size += sizeof(struct io_uring_cqe);
+
+	ocqe = kmalloc(ocq_size, GFP_ATOMIC | __GFP_ACCOUNT);
+	trace_io_uring_cqe_overflow(ctx, user_data, res, cflags, ocqe);
+	if (!ocqe) {
+		/*
+		 * If we're in ring overflow flush mode, or in task cancel mode,
+		 * or cannot allocate an overflow entry, then we need to drop it
+		 * on the floor.
+		 */
+		io_account_cq_overflow(ctx);
+		set_bit(IO_CHECK_CQ_DROPPED_BIT, &ctx->check_cq);
+		return false;
+	}
+	if (list_empty(&ctx->cq_overflow_list)) {
+		set_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq);
+		atomic_or(IORING_SQ_CQ_OVERFLOW, &ctx->rings->sq_flags);
+
+	}
+	ocqe->cqe.user_data = user_data;
+	ocqe->cqe.res = res;
+	ocqe->cqe.flags = cflags;
+	if (is_cqe32) {
+		ocqe->cqe.big_cqe[0] = extra1;
+		ocqe->cqe.big_cqe[1] = extra2;
+	}
+	list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
+	return true;
+}
+
+void io_req_cqe_overflow(struct io_kiocb *req)
+{
+	io_cqring_event_overflow(req->ctx, req->cqe.user_data,
+				req->cqe.res, req->cqe.flags,
+				req->big_cqe.extra1, req->big_cqe.extra2);
+	memset(&req->big_cqe, 0, sizeof(req->big_cqe));
+}
+
+/*
+ * 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
+ */
+bool io_cqe_cache_refill(struct io_ring_ctx *ctx, bool overflow)
+{
+	struct io_rings *rings = ctx->rings;
+	unsigned int off = ctx->cached_cq_tail & (ctx->cq_entries - 1);
+	unsigned int free, queued, len;
+
+	/*
+	 * Posting into the CQ when there are pending overflowed CQEs may break
+	 * ordering guarantees, which will affect links, F_MORE users and more.
+	 * Force overflow the completion.
+	 */
+	if (!overflow && (ctx->check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT)))
+		return false;
+
+	/* userspace may cheat modifying the tail, be safe and do min */
+	queued = min(__io_cqring_events(ctx), ctx->cq_entries);
+	free = ctx->cq_entries - queued;
+	/* we need a contiguous range, limit based on the current array offset */
+	len = min(free, ctx->cq_entries - off);
+	if (!len)
+		return false;
+
+	if (ctx->flags & IORING_SETUP_CQE32) {
+		off <<= 1;
+		len <<= 1;
+	}
+
+	ctx->cqe_cached = &rings->cqes[off];
+	ctx->cqe_sentinel = ctx->cqe_cached + len;
+	return true;
+}
+
+static bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data, s32 res,
+			      u32 cflags)
+{
+	struct io_uring_cqe *cqe;
+
+	ctx->cq_extra++;
+
+	/*
+	 * If we can't get a cq entry, userspace overflowed the
+	 * submission (by quite a lot). Increment the overflow count in
+	 * the ring.
+	 */
+	if (likely(io_get_cqe(ctx, &cqe))) {
+		trace_io_uring_complete(ctx, NULL, user_data, res, cflags, 0, 0);
+
+		WRITE_ONCE(cqe->user_data, user_data);
+		WRITE_ONCE(cqe->res, res);
+		WRITE_ONCE(cqe->flags, cflags);
+
+		if (ctx->flags & IORING_SETUP_CQE32) {
+			WRITE_ONCE(cqe->big_cqe[0], 0);
+			WRITE_ONCE(cqe->big_cqe[1], 0);
+		}
+		return true;
+	}
+	return false;
+}
+
+static void __io_flush_post_cqes(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+	unsigned int i;
+
+	lockdep_assert_held(&ctx->uring_lock);
+	for (i = 0; i < state->cqes_count; i++) {
+		struct io_uring_cqe *cqe = &ctx->completion_cqes[i];
+
+		if (!io_fill_cqe_aux(ctx, cqe->user_data, cqe->res, cqe->flags)) {
+			if (ctx->lockless_cq) {
+				spin_lock(&ctx->completion_lock);
+				io_cqring_event_overflow(ctx, cqe->user_data,
+							cqe->res, cqe->flags, 0, 0);
+				spin_unlock(&ctx->completion_lock);
+			} else {
+				io_cqring_event_overflow(ctx, cqe->user_data,
+							cqe->res, cqe->flags, 0, 0);
+			}
+		}
+	}
+	state->cqes_count = 0;
+}
+
+static bool __io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags,
+			      bool allow_overflow)
+{
+	bool filled;
+
+	io_cq_lock(ctx);
+	filled = io_fill_cqe_aux(ctx, user_data, res, cflags);
+	if (!filled && allow_overflow)
+		filled = io_cqring_event_overflow(ctx, user_data, res, cflags, 0, 0);
+
+	io_cq_unlock_post(ctx);
+	return filled;
+}
+
+bool io_post_aux_cqe(struct io_ring_ctx *ctx, u64 user_data, s32 res, u32 cflags)
+{
+	return __io_post_aux_cqe(ctx, user_data, res, cflags, true);
+}
+
+/*
+ * A helper for multishot requests posting additional CQEs.
+ * Should only be used from a task_work including IO_URING_F_MULTISHOT.
+ */
+bool io_fill_cqe_req_aux(struct io_kiocb *req, bool defer, s32 res, u32 cflags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	u64 user_data = req->cqe.user_data;
+	struct io_uring_cqe *cqe;
+
+	if (!defer)
+		return __io_post_aux_cqe(ctx, user_data, res, cflags, false);
+
+	lockdep_assert_held(&ctx->uring_lock);
+
+	if (ctx->submit_state.cqes_count == ARRAY_SIZE(ctx->completion_cqes)) {
+		__io_cq_lock(ctx);
+		__io_flush_post_cqes(ctx);
+		/* no need to flush - flush is deferred */
+		__io_cq_unlock_post(ctx);
+	}
+
+	/* For defered completions this is not as strict as it is otherwise,
+	 * however it's main job is to prevent unbounded posted completions,
+	 * and in that it works just as well.
+	 */
+	if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq))
+		return false;
+
+	cqe = &ctx->completion_cqes[ctx->submit_state.cqes_count++];
+	cqe->user_data = user_data;
+	cqe->res = res;
+	cqe->flags = cflags;
+	return true;
+}
+
+static void __io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_rsrc_node *rsrc_node = NULL;
+
+	io_cq_lock(ctx);
+	if (!(req->flags & REQ_F_CQE_SKIP)) {
+		if (!io_fill_cqe_req(ctx, req))
+			io_req_cqe_overflow(req);
+	}
+
+	/*
+	 * If we're the last reference to this request, add to our locked
+	 * free_list cache.
+	 */
+	if (req_ref_put_and_test(req)) {
+		if (req->flags & IO_REQ_LINK_FLAGS) {
+			if (req->flags & IO_DISARM_MASK)
+				io_disarm_next(req);
+			if (req->link) {
+				io_req_task_queue(req->link);
+				req->link = NULL;
+			}
+		}
+		io_put_kbuf_comp(req);
+		if (unlikely(req->flags & IO_REQ_CLEAN_FLAGS))
+			io_clean_op(req);
+		io_put_file(req);
+
+		rsrc_node = req->rsrc_node;
+		/*
+		 * Selected buffer deallocation in io_clean_op() assumes that
+		 * we don't hold ->completion_lock. Clean them here to avoid
+		 * deadlocks.
+		 */
+		io_put_task_remote(req->task);
+		wq_list_add_head(&req->comp_list, &ctx->locked_free_list);
+		ctx->locked_free_nr++;
+	}
+	io_cq_unlock_post(ctx);
+
+	if (rsrc_node) {
+		io_ring_submit_lock(ctx, issue_flags);
+		io_put_rsrc_node(ctx, rsrc_node);
+		io_ring_submit_unlock(ctx, issue_flags);
+	}
+}
+
+void io_req_complete_post(struct io_kiocb *req, unsigned issue_flags)
+{
+	if (req->ctx->task_complete && req->ctx->submitter_task != current) {
+		req->io_task_work.func = io_req_task_complete;
+		io_req_task_work_add(req);
+	} else if (!(issue_flags & IO_URING_F_UNLOCKED) ||
+		   !(req->ctx->flags & IORING_SETUP_IOPOLL)) {
+		__io_req_complete_post(req, issue_flags);
+	} else {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		mutex_lock(&ctx->uring_lock);
+		__io_req_complete_post(req, issue_flags & ~IO_URING_F_UNLOCKED);
+		mutex_unlock(&ctx->uring_lock);
+	}
+}
+
+void io_req_defer_failed(struct io_kiocb *req, s32 res)
+	__must_hold(&ctx->uring_lock)
+{
+	const struct io_cold_def *def = &io_cold_defs[req->opcode];
+
+	lockdep_assert_held(&req->ctx->uring_lock);
+
+	req_set_fail(req);
+	io_req_set_res(req, res, io_put_kbuf(req, IO_URING_F_UNLOCKED));
+	if (def->fail)
+		def->fail(req);
+	io_req_complete_defer(req);
+}
+
+/*
+ * Don't initialise the fields below on every allocation, but do that in
+ * advance and keep them valid across allocations.
+ */
+static void io_preinit_req(struct io_kiocb *req, struct io_ring_ctx *ctx)
+{
+	req->ctx = ctx;
+	req->link = NULL;
+	req->async_data = NULL;
+	/* not necessary, but safer to zero */
+	memset(&req->cqe, 0, sizeof(req->cqe));
+	memset(&req->big_cqe, 0, sizeof(req->big_cqe));
+}
+
+static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
+					struct io_submit_state *state)
+{
+	spin_lock(&ctx->completion_lock);
+	wq_list_splice(&ctx->locked_free_list, &state->free_list);
+	ctx->locked_free_nr = 0;
+	spin_unlock(&ctx->completion_lock);
+}
+
+/*
+ * A request might get retired back into the request caches even before opcode
+ * handlers and io_issue_sqe() are done with it, e.g. inline completion path.
+ * Because of that, io_alloc_req() should be called only under ->uring_lock
+ * and with extra caution to not get a request that is still worked on.
+ */
+__cold bool __io_alloc_req_refill(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
+	void *reqs[IO_REQ_ALLOC_BATCH];
+	int ret, i;
+
+	/*
+	 * If we have more than a batch's worth of requests in our IRQ side
+	 * locked cache, grab the lock and move them over to our submission
+	 * side cache.
+	 */
+	if (data_race(ctx->locked_free_nr) > IO_COMPL_BATCH) {
+		io_flush_cached_locked_reqs(ctx, &ctx->submit_state);
+		if (!io_req_cache_empty(ctx))
+			return true;
+	}
+
+	ret = kmem_cache_alloc_bulk(req_cachep, gfp, ARRAY_SIZE(reqs), 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)) {
+		reqs[0] = kmem_cache_alloc(req_cachep, gfp);
+		if (!reqs[0])
+			return false;
+		ret = 1;
+	}
+
+	percpu_ref_get_many(&ctx->refs, ret);
+	for (i = 0; i < ret; i++) {
+		struct io_kiocb *req = reqs[i];
+
+		io_preinit_req(req, ctx);
+		io_req_add_to_cache(req, ctx);
+	}
+	return true;
+}
+
+__cold void io_free_req(struct io_kiocb *req)
+{
+	/* refs were already put, restore them for io_req_task_complete() */
+	req->flags &= ~REQ_F_REFCOUNT;
+	/* we only want to free it, don't post CQEs */
+	req->flags |= REQ_F_CQE_SKIP;
+	req->io_task_work.func = io_req_task_complete;
+	io_req_task_work_add(req);
+}
+
+static void __io_req_find_next_prep(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	spin_lock(&ctx->completion_lock);
+	io_disarm_next(req);
+	spin_unlock(&ctx->completion_lock);
+}
+
+static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
+{
+	struct io_kiocb *nxt;
+
+	/*
+	 * 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 (unlikely(req->flags & IO_DISARM_MASK))
+		__io_req_find_next_prep(req);
+	nxt = req->link;
+	req->link = NULL;
+	return nxt;
+}
+
+static void ctx_flush_and_put(struct io_ring_ctx *ctx, struct io_tw_state *ts)
+{
+	if (!ctx)
+		return;
+	if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+		atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+	if (ts->locked) {
+		io_submit_flush_completions(ctx);
+		mutex_unlock(&ctx->uring_lock);
+		ts->locked = false;
+	}
+	percpu_ref_put(&ctx->refs);
+}
+
+static unsigned int handle_tw_list(struct llist_node *node,
+				   struct io_ring_ctx **ctx,
+				   struct io_tw_state *ts,
+				   struct llist_node *last)
+{
+	unsigned int count = 0;
+
+	while (node && node != last) {
+		struct llist_node *next = node->next;
+		struct io_kiocb *req = container_of(node, struct io_kiocb,
+						    io_task_work.node);
+
+		prefetch(container_of(next, struct io_kiocb, io_task_work.node));
+
+		if (req->ctx != *ctx) {
+			ctx_flush_and_put(*ctx, ts);
+			*ctx = req->ctx;
+			/* if not contended, grab and improve batching */
+			ts->locked = mutex_trylock(&(*ctx)->uring_lock);
+			percpu_ref_get(&(*ctx)->refs);
+		}
+		INDIRECT_CALL_2(req->io_task_work.func,
+				io_poll_task_func, io_req_rw_complete,
+				req, ts);
+		node = next;
+		count++;
+		if (unlikely(need_resched())) {
+			ctx_flush_and_put(*ctx, ts);
+			*ctx = NULL;
+			cond_resched();
+		}
+	}
+
+	return count;
+}
+
+/**
+ * io_llist_xchg - swap all entries in a lock-less list
+ * @head:	the head of lock-less list to delete all entries
+ * @new:	new entry as the head of the list
+ *
+ * If list is empty, return NULL, otherwise, return the pointer to the first entry.
+ * The order of entries returned is from the newest to the oldest added one.
+ */
+static inline struct llist_node *io_llist_xchg(struct llist_head *head,
+					       struct llist_node *new)
+{
+	return xchg(&head->first, new);
+}
+
+/**
+ * io_llist_cmpxchg - possibly swap all entries in a lock-less list
+ * @head:	the head of lock-less list to delete all entries
+ * @old:	expected old value of the first entry of the list
+ * @new:	new entry as the head of the list
+ *
+ * perform a cmpxchg on the first entry of the list.
+ */
+
+static inline struct llist_node *io_llist_cmpxchg(struct llist_head *head,
+						  struct llist_node *old,
+						  struct llist_node *new)
+{
+	return cmpxchg(&head->first, old, new);
+}
+
+static __cold void io_fallback_tw(struct io_uring_task *tctx, bool sync)
+{
+	struct llist_node *node = llist_del_all(&tctx->task_list);
+	struct io_ring_ctx *last_ctx = NULL;
+	struct io_kiocb *req;
+
+	while (node) {
+		req = container_of(node, struct io_kiocb, io_task_work.node);
+		node = node->next;
+		if (sync && last_ctx != req->ctx) {
+			if (last_ctx) {
+				flush_delayed_work(&last_ctx->fallback_work);
+				percpu_ref_put(&last_ctx->refs);
+			}
+			last_ctx = req->ctx;
+			percpu_ref_get(&last_ctx->refs);
+		}
+		if (llist_add(&req->io_task_work.node,
+			      &req->ctx->fallback_llist))
+			schedule_delayed_work(&req->ctx->fallback_work, 1);
+	}
+
+	if (last_ctx) {
+		flush_delayed_work(&last_ctx->fallback_work);
+		percpu_ref_put(&last_ctx->refs);
+	}
+}
+
+void tctx_task_work(struct callback_head *cb)
+{
+	struct io_tw_state ts = {};
+	struct io_ring_ctx *ctx = NULL;
+	struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
+						  task_work);
+	struct llist_node fake = {};
+	struct llist_node *node;
+	unsigned int loops = 0;
+	unsigned int count = 0;
+
+	if (unlikely(current->flags & PF_EXITING)) {
+		io_fallback_tw(tctx, true);
+		return;
+	}
+
+	do {
+		loops++;
+		node = io_llist_xchg(&tctx->task_list, &fake);
+		count += handle_tw_list(node, &ctx, &ts, &fake);
+
+		/* skip expensive cmpxchg if there are items in the list */
+		if (READ_ONCE(tctx->task_list.first) != &fake)
+			continue;
+		if (ts.locked && !wq_list_empty(&ctx->submit_state.compl_reqs)) {
+			io_submit_flush_completions(ctx);
+			if (READ_ONCE(tctx->task_list.first) != &fake)
+				continue;
+		}
+		node = io_llist_cmpxchg(&tctx->task_list, &fake, NULL);
+	} while (node != &fake);
+
+	ctx_flush_and_put(ctx, &ts);
+
+	/* relaxed read is enough as only the task itself sets ->in_cancel */
+	if (unlikely(atomic_read(&tctx->in_cancel)))
+		io_uring_drop_tctx_refs(current);
+
+	trace_io_uring_task_work_run(tctx, count, loops);
+}
+
+static inline void io_req_local_work_add(struct io_kiocb *req, unsigned flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned nr_wait, nr_tw, nr_tw_prev;
+	struct llist_node *first;
+
+	if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK))
+		flags &= ~IOU_F_TWQ_LAZY_WAKE;
+
+	first = READ_ONCE(ctx->work_llist.first);
+	do {
+		nr_tw_prev = 0;
+		if (first) {
+			struct io_kiocb *first_req = container_of(first,
+							struct io_kiocb,
+							io_task_work.node);
+			/*
+			 * Might be executed at any moment, rely on
+			 * SLAB_TYPESAFE_BY_RCU to keep it alive.
+			 */
+			nr_tw_prev = READ_ONCE(first_req->nr_tw);
+		}
+		nr_tw = nr_tw_prev + 1;
+		/* Large enough to fail the nr_wait comparison below */
+		if (!(flags & IOU_F_TWQ_LAZY_WAKE))
+			nr_tw = INT_MAX;
+
+		req->nr_tw = nr_tw;
+		req->io_task_work.node.next = first;
+	} while (!try_cmpxchg(&ctx->work_llist.first, &first,
+			      &req->io_task_work.node));
+
+	if (!first) {
+		if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+			atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+		if (ctx->has_evfd)
+			io_eventfd_signal(ctx);
+	}
+
+	nr_wait = atomic_read(&ctx->cq_wait_nr);
+	/* no one is waiting */
+	if (!nr_wait)
+		return;
+	/* either not enough or the previous add has already woken it up */
+	if (nr_wait > nr_tw || nr_tw_prev >= nr_wait)
+		return;
+	/* pairs with set_current_state() in io_cqring_wait() */
+	smp_mb__after_atomic();
+	wake_up_state(ctx->submitter_task, TASK_INTERRUPTIBLE);
+}
+
+static void io_req_normal_work_add(struct io_kiocb *req)
+{
+	struct io_uring_task *tctx = req->task->io_uring;
+	struct io_ring_ctx *ctx = req->ctx;
+
+	/* task_work already pending, we're done */
+	if (!llist_add(&req->io_task_work.node, &tctx->task_list))
+		return;
+
+	if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+		atomic_or(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+
+	if (likely(!task_work_add(req->task, &tctx->task_work, ctx->notify_method)))
+		return;
+
+	io_fallback_tw(tctx, false);
+}
+
+void __io_req_task_work_add(struct io_kiocb *req, unsigned flags)
+{
+	if (req->ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
+		rcu_read_lock();
+		io_req_local_work_add(req, flags);
+		rcu_read_unlock();
+	} else {
+		io_req_normal_work_add(req);
+	}
+}
+
+static void __cold io_move_task_work_from_local(struct io_ring_ctx *ctx)
+{
+	struct llist_node *node;
+
+	node = llist_del_all(&ctx->work_llist);
+	while (node) {
+		struct io_kiocb *req = container_of(node, struct io_kiocb,
+						    io_task_work.node);
+
+		node = node->next;
+		io_req_normal_work_add(req);
+	}
+}
+
+static int __io_run_local_work(struct io_ring_ctx *ctx, struct io_tw_state *ts)
+{
+	struct llist_node *node;
+	unsigned int loops = 0;
+	int ret = 0;
+
+	if (WARN_ON_ONCE(ctx->submitter_task != current))
+		return -EEXIST;
+	if (ctx->flags & IORING_SETUP_TASKRUN_FLAG)
+		atomic_andnot(IORING_SQ_TASKRUN, &ctx->rings->sq_flags);
+again:
+	/*
+	 * llists are in reverse order, flip it back the right way before
+	 * running the pending items.
+	 */
+	node = llist_reverse_order(io_llist_xchg(&ctx->work_llist, NULL));
+	while (node) {
+		struct llist_node *next = node->next;
+		struct io_kiocb *req = container_of(node, struct io_kiocb,
+						    io_task_work.node);
+		prefetch(container_of(next, struct io_kiocb, io_task_work.node));
+		INDIRECT_CALL_2(req->io_task_work.func,
+				io_poll_task_func, io_req_rw_complete,
+				req, ts);
+		ret++;
+		node = next;
+	}
+	loops++;
+
+	if (!llist_empty(&ctx->work_llist))
+		goto again;
+	if (ts->locked) {
+		io_submit_flush_completions(ctx);
+		if (!llist_empty(&ctx->work_llist))
+			goto again;
+	}
+	trace_io_uring_local_work_run(ctx, ret, loops);
+	return ret;
+}
+
+static inline int io_run_local_work_locked(struct io_ring_ctx *ctx)
+{
+	struct io_tw_state ts = { .locked = true, };
+	int ret;
+
+	if (llist_empty(&ctx->work_llist))
+		return 0;
+
+	ret = __io_run_local_work(ctx, &ts);
+	/* shouldn't happen! */
+	if (WARN_ON_ONCE(!ts.locked))
+		mutex_lock(&ctx->uring_lock);
+	return ret;
+}
+
+static int io_run_local_work(struct io_ring_ctx *ctx)
+{
+	struct io_tw_state ts = {};
+	int ret;
+
+	ts.locked = mutex_trylock(&ctx->uring_lock);
+	ret = __io_run_local_work(ctx, &ts);
+	if (ts.locked)
+		mutex_unlock(&ctx->uring_lock);
+
+	return ret;
+}
+
+static void io_req_task_cancel(struct io_kiocb *req, struct io_tw_state *ts)
+{
+	io_tw_lock(req->ctx, ts);
+	io_req_defer_failed(req, req->cqe.res);
+}
+
+void io_req_task_submit(struct io_kiocb *req, struct io_tw_state *ts)
+{
+	io_tw_lock(req->ctx, ts);
+	/* req->task == current here, checking PF_EXITING is safe */
+	if (unlikely(req->task->flags & PF_EXITING))
+		io_req_defer_failed(req, -EFAULT);
+	else if (req->flags & REQ_F_FORCE_ASYNC)
+		io_queue_iowq(req, ts);
+	else
+		io_queue_sqe(req);
+}
+
+void io_req_task_queue_fail(struct io_kiocb *req, int ret)
+{
+	io_req_set_res(req, ret, 0);
+	req->io_task_work.func = io_req_task_cancel;
+	io_req_task_work_add(req);
+}
+
+void io_req_task_queue(struct io_kiocb *req)
+{
+	req->io_task_work.func = io_req_task_submit;
+	io_req_task_work_add(req);
+}
+
+void io_queue_next(struct io_kiocb *req)
+{
+	struct io_kiocb *nxt = io_req_find_next(req);
+
+	if (nxt)
+		io_req_task_queue(nxt);
+}
+
+static void io_free_batch_list(struct io_ring_ctx *ctx,
+			       struct io_wq_work_node *node)
+	__must_hold(&ctx->uring_lock)
+{
+	do {
+		struct io_kiocb *req = container_of(node, struct io_kiocb,
+						    comp_list);
+
+		if (unlikely(req->flags & IO_REQ_CLEAN_SLOW_FLAGS)) {
+			if (req->flags & REQ_F_REFCOUNT) {
+				node = req->comp_list.next;
+				if (!req_ref_put_and_test(req))
+					continue;
+			}
+			if ((req->flags & REQ_F_POLLED) && req->apoll) {
+				struct async_poll *apoll = req->apoll;
+
+				if (apoll->double_poll)
+					kfree(apoll->double_poll);
+				if (!io_alloc_cache_put(&ctx->apoll_cache, &apoll->cache))
+					kfree(apoll);
+				req->flags &= ~REQ_F_POLLED;
+			}
+			if (req->flags & IO_REQ_LINK_FLAGS)
+				io_queue_next(req);
+			if (unlikely(req->flags & IO_REQ_CLEAN_FLAGS))
+				io_clean_op(req);
+		}
+		io_put_file(req);
+
+		io_req_put_rsrc_locked(req, ctx);
+
+		io_put_task(req->task);
+		node = req->comp_list.next;
+		io_req_add_to_cache(req, ctx);
+	} while (node);
+}
+
+void __io_submit_flush_completions(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+	struct io_wq_work_node *node;
+
+	__io_cq_lock(ctx);
+	/* must come first to preserve CQE ordering in failure cases */
+	if (state->cqes_count)
+		__io_flush_post_cqes(ctx);
+	__wq_list_for_each(node, &state->compl_reqs) {
+		struct io_kiocb *req = container_of(node, struct io_kiocb,
+					    comp_list);
+
+		if (!(req->flags & REQ_F_CQE_SKIP) &&
+		    unlikely(!io_fill_cqe_req(ctx, req))) {
+			if (ctx->lockless_cq) {
+				spin_lock(&ctx->completion_lock);
+				io_req_cqe_overflow(req);
+				spin_unlock(&ctx->completion_lock);
+			} else {
+				io_req_cqe_overflow(req);
+			}
+		}
+	}
+	__io_cq_unlock_post(ctx);
+
+	if (!wq_list_empty(&ctx->submit_state.compl_reqs)) {
+		io_free_batch_list(ctx, state->compl_reqs.first);
+		INIT_WQ_LIST(&state->compl_reqs);
+	}
+}
+
+static unsigned io_cqring_events(struct io_ring_ctx *ctx)
+{
+	/* See comment at the top of this file */
+	smp_rmb();
+	return __io_cqring_events(ctx);
+}
+
+/*
+ * We can't just wait for polled events to come to us, we have to actively
+ * find and complete them.
+ */
+static __cold void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
+{
+	if (!(ctx->flags & IORING_SETUP_IOPOLL))
+		return;
+
+	mutex_lock(&ctx->uring_lock);
+	while (!wq_list_empty(&ctx->iopoll_list)) {
+		/* let it sleep and repeat later if can't complete a request */
+		if (io_do_iopoll(ctx, true) == 0)
+			break;
+		/*
+		 * Ensure we allow local-to-the-cpu processing to take place,
+		 * in this case we need to ensure that we reap all events.
+		 * Also let task_work, etc. to progress by releasing the mutex
+		 */
+		if (need_resched()) {
+			mutex_unlock(&ctx->uring_lock);
+			cond_resched();
+			mutex_lock(&ctx->uring_lock);
+		}
+	}
+	mutex_unlock(&ctx->uring_lock);
+}
+
+static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
+{
+	unsigned int nr_events = 0;
+	unsigned long check_cq;
+
+	if (!io_allowed_run_tw(ctx))
+		return -EEXIST;
+
+	check_cq = READ_ONCE(ctx->check_cq);
+	if (unlikely(check_cq)) {
+		if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
+			__io_cqring_overflow_flush(ctx);
+		/*
+		 * Similarly do not spin if we have not informed the user of any
+		 * dropped CQE.
+		 */
+		if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT))
+			return -EBADR;
+	}
+	/*
+	 * 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))
+		return 0;
+
+	do {
+		int ret = 0;
+
+		/*
+		 * 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 (wq_list_empty(&ctx->iopoll_list) ||
+		    io_task_work_pending(ctx)) {
+			u32 tail = ctx->cached_cq_tail;
+
+			(void) io_run_local_work_locked(ctx);
+
+			if (task_work_pending(current) ||
+			    wq_list_empty(&ctx->iopoll_list)) {
+				mutex_unlock(&ctx->uring_lock);
+				io_run_task_work();
+				mutex_lock(&ctx->uring_lock);
+			}
+			/* some requests don't go through iopoll_list */
+			if (tail != ctx->cached_cq_tail ||
+			    wq_list_empty(&ctx->iopoll_list))
+				break;
+		}
+		ret = io_do_iopoll(ctx, !min);
+		if (unlikely(ret < 0))
+			return ret;
+
+		if (task_sigpending(current))
+			return -EINTR;
+		if (need_resched())
+			break;
+
+		nr_events += ret;
+	} while (nr_events < min);
+
+	return 0;
+}
+
+void io_req_task_complete(struct io_kiocb *req, struct io_tw_state *ts)
+{
+	if (ts->locked)
+		io_req_complete_defer(req);
+	else
+		io_req_complete_post(req, IO_URING_F_UNLOCKED);
+}
+
+/*
+ * 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_do_iopoll() thread before the issuer is done
+ * accessing the kiocb cookie.
+ */
+static void io_iopoll_req_issued(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	const bool needs_lock = issue_flags & IO_URING_F_UNLOCKED;
+
+	/* workqueue context doesn't hold uring_lock, grab it now */
+	if (unlikely(needs_lock))
+		mutex_lock(&ctx->uring_lock);
+
+	/*
+	 * 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 (wq_list_empty(&ctx->iopoll_list)) {
+		ctx->poll_multi_queue = false;
+	} else if (!ctx->poll_multi_queue) {
+		struct io_kiocb *list_req;
+
+		list_req = container_of(ctx->iopoll_list.first, struct io_kiocb,
+					comp_list);
+		if (list_req->file != req->file)
+			ctx->poll_multi_queue = true;
+	}
+
+	/*
+	 * For fast devices, IO may have already completed. If it has, add
+	 * it to the front so we find it first.
+	 */
+	if (READ_ONCE(req->iopoll_completed))
+		wq_list_add_head(&req->comp_list, &ctx->iopoll_list);
+	else
+		wq_list_add_tail(&req->comp_list, &ctx->iopoll_list);
+
+	if (unlikely(needs_lock)) {
+		/*
+		 * If IORING_SETUP_SQPOLL is enabled, sqes are either handle
+		 * in sq thread task context or in io worker task context. If
+		 * current task context is sq thread, we don't need to check
+		 * whether should wake up sq thread.
+		 */
+		if ((ctx->flags & IORING_SETUP_SQPOLL) &&
+		    wq_has_sleeper(&ctx->sq_data->wait))
+			wake_up(&ctx->sq_data->wait);
+
+		mutex_unlock(&ctx->uring_lock);
+	}
+}
+
+unsigned int io_file_get_flags(struct file *file)
+{
+	unsigned int res = 0;
+
+	if (S_ISREG(file_inode(file)->i_mode))
+		res |= REQ_F_ISREG;
+	if ((file->f_flags & O_NONBLOCK) || (file->f_mode & FMODE_NOWAIT))
+		res |= REQ_F_SUPPORT_NOWAIT;
+	return res;
+}
+
+bool io_alloc_async_data(struct io_kiocb *req)
+{
+	WARN_ON_ONCE(!io_cold_defs[req->opcode].async_size);
+	req->async_data = kmalloc(io_cold_defs[req->opcode].async_size, GFP_KERNEL);
+	if (req->async_data) {
+		req->flags |= REQ_F_ASYNC_DATA;
+		return false;
+	}
+	return true;
+}
+
+int io_req_prep_async(struct io_kiocb *req)
+{
+	const struct io_cold_def *cdef = &io_cold_defs[req->opcode];
+	const struct io_issue_def *def = &io_issue_defs[req->opcode];
+
+	/* assign early for deferred execution for non-fixed file */
+	if (def->needs_file && !(req->flags & REQ_F_FIXED_FILE) && !req->file)
+		req->file = io_file_get_normal(req, req->cqe.fd);
+	if (!cdef->prep_async)
+		return 0;
+	if (WARN_ON_ONCE(req_has_async_data(req)))
+		return -EFAULT;
+	if (!def->manual_alloc) {
+		if (io_alloc_async_data(req))
+			return -EAGAIN;
+	}
+	return cdef->prep_async(req);
+}
+
+static u32 io_get_sequence(struct io_kiocb *req)
+{
+	u32 seq = req->ctx->cached_sq_head;
+	struct io_kiocb *cur;
+
+	/* need original cached_sq_head, but it was increased for each req */
+	io_for_each_link(cur, req)
+		seq--;
+	return seq;
+}
+
+static __cold void io_drain_req(struct io_kiocb *req)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_defer_entry *de;
+	int ret;
+	u32 seq = io_get_sequence(req);
+
+	/* Still need defer if there is pending req in defer list. */
+	spin_lock(&ctx->completion_lock);
+	if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list)) {
+		spin_unlock(&ctx->completion_lock);
+queue:
+		ctx->drain_active = false;
+		io_req_task_queue(req);
+		return;
+	}
+	spin_unlock(&ctx->completion_lock);
+
+	io_prep_async_link(req);
+	de = kmalloc(sizeof(*de), GFP_KERNEL);
+	if (!de) {
+		ret = -ENOMEM;
+		io_req_defer_failed(req, ret);
+		return;
+	}
+
+	spin_lock(&ctx->completion_lock);
+	if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
+		spin_unlock(&ctx->completion_lock);
+		kfree(de);
+		goto queue;
+	}
+
+	trace_io_uring_defer(req);
+	de->req = req;
+	de->seq = seq;
+	list_add_tail(&de->list, &ctx->defer_list);
+	spin_unlock(&ctx->completion_lock);
+}
+
+static bool io_assign_file(struct io_kiocb *req, const struct io_issue_def *def,
+			   unsigned int issue_flags)
+{
+	if (req->file || !def->needs_file)
+		return true;
+
+	if (req->flags & REQ_F_FIXED_FILE)
+		req->file = io_file_get_fixed(req, req->cqe.fd, issue_flags);
+	else
+		req->file = io_file_get_normal(req, req->cqe.fd);
+
+	return !!req->file;
+}
+
+static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
+{
+	const struct io_issue_def *def = &io_issue_defs[req->opcode];
+	const struct cred *creds = NULL;
+	int ret;
+
+	if (unlikely(!io_assign_file(req, def, issue_flags)))
+		return -EBADF;
+
+	if (unlikely((req->flags & REQ_F_CREDS) && req->creds != current_cred()))
+		creds = override_creds(req->creds);
+
+	if (!def->audit_skip)
+		audit_uring_entry(req->opcode);
+
+	ret = def->issue(req, issue_flags);
+
+	if (!def->audit_skip)
+		audit_uring_exit(!ret, ret);
+
+	if (creds)
+		revert_creds(creds);
+
+	if (ret == IOU_OK) {
+		if (issue_flags & IO_URING_F_COMPLETE_DEFER)
+			io_req_complete_defer(req);
+		else
+			io_req_complete_post(req, issue_flags);
+
+		return 0;
+	}
+
+	if (ret != IOU_ISSUE_SKIP_COMPLETE)
+		return ret;
+
+	/* If the op doesn't have a file, we're not polling for it */
+	if ((req->ctx->flags & IORING_SETUP_IOPOLL) && def->iopoll_queue)
+		io_iopoll_req_issued(req, issue_flags);
+
+	return 0;
+}
+
+int io_poll_issue(struct io_kiocb *req, struct io_tw_state *ts)
+{
+	io_tw_lock(req->ctx, ts);
+	return io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_MULTISHOT|
+				 IO_URING_F_COMPLETE_DEFER);
+}
+
+struct io_wq_work *io_wq_free_work(struct io_wq_work *work)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	struct io_kiocb *nxt = NULL;
+
+	if (req_ref_put_and_test(req)) {
+		if (req->flags & IO_REQ_LINK_FLAGS)
+			nxt = io_req_find_next(req);
+		io_free_req(req);
+	}
+	return nxt ? &nxt->work : NULL;
+}
+
+void io_wq_submit_work(struct io_wq_work *work)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	const struct io_issue_def *def = &io_issue_defs[req->opcode];
+	unsigned int issue_flags = IO_URING_F_UNLOCKED | IO_URING_F_IOWQ;
+	bool needs_poll = false;
+	int ret = 0, err = -ECANCELED;
+
+	/* one will be dropped by ->io_wq_free_work() after returning to io-wq */
+	if (!(req->flags & REQ_F_REFCOUNT))
+		__io_req_set_refcount(req, 2);
+	else
+		req_ref_get(req);
+
+	io_arm_ltimeout(req);
+
+	/* either cancelled or io-wq is dying, so don't touch tctx->iowq */
+	if (work->flags & IO_WQ_WORK_CANCEL) {
+fail:
+		io_req_task_queue_fail(req, err);
+		return;
+	}
+	if (!io_assign_file(req, def, issue_flags)) {
+		err = -EBADF;
+		work->flags |= IO_WQ_WORK_CANCEL;
+		goto fail;
+	}
+
+	if (req->flags & REQ_F_FORCE_ASYNC) {
+		bool opcode_poll = def->pollin || def->pollout;
+
+		if (opcode_poll && file_can_poll(req->file)) {
+			needs_poll = true;
+			issue_flags |= IO_URING_F_NONBLOCK;
+		}
+	}
+
+	do {
+		ret = io_issue_sqe(req, issue_flags);
+		if (ret != -EAGAIN)
+			break;
+
+		/*
+		 * If REQ_F_NOWAIT is set, then don't wait or retry with
+		 * poll. -EAGAIN is final for that case.
+		 */
+		if (req->flags & REQ_F_NOWAIT)
+			break;
+
+		/*
+		 * We can get EAGAIN for iopolled IO even though we're
+		 * forcing a sync submission from here, since we can't
+		 * wait for request slots on the block side.
+		 */
+		if (!needs_poll) {
+			if (!(req->ctx->flags & IORING_SETUP_IOPOLL))
+				break;
+			if (io_wq_worker_stopped())
+				break;
+			cond_resched();
+			continue;
+		}
+
+		if (io_arm_poll_handler(req, issue_flags) == IO_APOLL_OK)
+			return;
+		/* aborted or ready, in either case retry blocking */
+		needs_poll = false;
+		issue_flags &= ~IO_URING_F_NONBLOCK;
+	} while (1);
+
+	/* avoid locking problems by failing it from a clean context */
+	if (ret < 0)
+		io_req_task_queue_fail(req, ret);
+}
+
+inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
+				      unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_fixed_file *slot;
+	struct file *file = NULL;
+
+	io_ring_submit_lock(ctx, issue_flags);
+
+	if (unlikely((unsigned int)fd >= ctx->nr_user_files))
+		goto out;
+	fd = array_index_nospec(fd, ctx->nr_user_files);
+	slot = io_fixed_file_slot(&ctx->file_table, fd);
+	file = io_slot_file(slot);
+	req->flags |= io_slot_flags(slot);
+	io_req_set_rsrc_node(req, ctx, 0);
+out:
+	io_ring_submit_unlock(ctx, issue_flags);
+	return file;
+}
+
+struct file *io_file_get_normal(struct io_kiocb *req, int fd)
+{
+	struct file *file = fget(fd);
+
+	trace_io_uring_file_get(req, fd);
+
+	/* we don't allow fixed io_uring files */
+	if (file && io_is_uring_fops(file))
+		io_req_track_inflight(req);
+	return file;
+}
+
+static void io_queue_async(struct io_kiocb *req, int ret)
+	__must_hold(&req->ctx->uring_lock)
+{
+	struct io_kiocb *linked_timeout;
+
+	if (ret != -EAGAIN || (req->flags & REQ_F_NOWAIT)) {
+		io_req_defer_failed(req, ret);
+		return;
+	}
+
+	linked_timeout = io_prep_linked_timeout(req);
+
+	switch (io_arm_poll_handler(req, 0)) {
+	case IO_APOLL_READY:
+		io_kbuf_recycle(req, 0);
+		io_req_task_queue(req);
+		break;
+	case IO_APOLL_ABORTED:
+		io_kbuf_recycle(req, 0);
+		io_queue_iowq(req, NULL);
+		break;
+	case IO_APOLL_OK:
+		break;
+	}
+
+	if (linked_timeout)
+		io_queue_linked_timeout(linked_timeout);
+}
+
+static inline void io_queue_sqe(struct io_kiocb *req)
+	__must_hold(&req->ctx->uring_lock)
+{
+	int ret;
+
+	ret = io_issue_sqe(req, IO_URING_F_NONBLOCK|IO_URING_F_COMPLETE_DEFER);
+
+	/*
+	 * We async punt it if the file wasn't marked NOWAIT, or if the file
+	 * doesn't support non-blocking read/write attempts
+	 */
+	if (likely(!ret))
+		io_arm_ltimeout(req);
+	else
+		io_queue_async(req, ret);
+}
+
+static void io_queue_sqe_fallback(struct io_kiocb *req)
+	__must_hold(&req->ctx->uring_lock)
+{
+	if (unlikely(req->flags & REQ_F_FAIL)) {
+		/*
+		 * We don't submit, fail them all, for that replace hardlinks
+		 * with normal links. Extra REQ_F_LINK is tolerated.
+		 */
+		req->flags &= ~REQ_F_HARDLINK;
+		req->flags |= REQ_F_LINK;
+		io_req_defer_failed(req, req->cqe.res);
+	} else {
+		int ret = io_req_prep_async(req);
+
+		if (unlikely(ret)) {
+			io_req_defer_failed(req, ret);
+			return;
+		}
+
+		if (unlikely(req->ctx->drain_active))
+			io_drain_req(req);
+		else
+			io_queue_iowq(req, NULL);
+	}
+}
+
+/*
+ * Check SQE restrictions (opcode and flags).
+ *
+ * Returns 'true' if SQE is allowed, 'false' otherwise.
+ */
+static inline bool io_check_restriction(struct io_ring_ctx *ctx,
+					struct io_kiocb *req,
+					unsigned int sqe_flags)
+{
+	if (!test_bit(req->opcode, ctx->restrictions.sqe_op))
+		return false;
+
+	if ((sqe_flags & ctx->restrictions.sqe_flags_required) !=
+	    ctx->restrictions.sqe_flags_required)
+		return false;
+
+	if (sqe_flags & ~(ctx->restrictions.sqe_flags_allowed |
+			  ctx->restrictions.sqe_flags_required))
+		return false;
+
+	return true;
+}
+
+static void io_init_req_drain(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_kiocb *head = ctx->submit_state.link.head;
+
+	ctx->drain_active = true;
+	if (head) {
+		/*
+		 * If we need to drain a request in the middle of a link, drain
+		 * the head request and the next request/link after the current
+		 * link. Considering sequential execution of links,
+		 * REQ_F_IO_DRAIN will be maintained for every request of our
+		 * link.
+		 */
+		head->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
+		ctx->drain_next = true;
+	}
+}
+
+static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
+		       const struct io_uring_sqe *sqe)
+	__must_hold(&ctx->uring_lock)
+{
+	const struct io_issue_def *def;
+	unsigned int sqe_flags;
+	int personality;
+	u8 opcode;
+
+	/* req is partially pre-initialised, see io_preinit_req() */
+	req->opcode = opcode = READ_ONCE(sqe->opcode);
+	/* same numerical values with corresponding REQ_F_*, safe to copy */
+	req->flags = sqe_flags = READ_ONCE(sqe->flags);
+	req->cqe.user_data = READ_ONCE(sqe->user_data);
+	req->file = NULL;
+	req->rsrc_node = NULL;
+	req->task = current;
+
+	if (unlikely(opcode >= IORING_OP_LAST)) {
+		req->opcode = 0;
+		return -EINVAL;
+	}
+	def = &io_issue_defs[opcode];
+	if (unlikely(sqe_flags & ~SQE_COMMON_FLAGS)) {
+		/* enforce forwards compatibility on users */
+		if (sqe_flags & ~SQE_VALID_FLAGS)
+			return -EINVAL;
+		if (sqe_flags & IOSQE_BUFFER_SELECT) {
+			if (!def->buffer_select)
+				return -EOPNOTSUPP;
+			req->buf_index = READ_ONCE(sqe->buf_group);
+		}
+		if (sqe_flags & IOSQE_CQE_SKIP_SUCCESS)
+			ctx->drain_disabled = true;
+		if (sqe_flags & IOSQE_IO_DRAIN) {
+			if (ctx->drain_disabled)
+				return -EOPNOTSUPP;
+			io_init_req_drain(req);
+		}
+	}
+	if (unlikely(ctx->restricted || ctx->drain_active || ctx->drain_next)) {
+		if (ctx->restricted && !io_check_restriction(ctx, req, sqe_flags))
+			return -EACCES;
+		/* knock it to the slow queue path, will be drained there */
+		if (ctx->drain_active)
+			req->flags |= REQ_F_FORCE_ASYNC;
+		/* if there is no link, we're at "next" request and need to drain */
+		if (unlikely(ctx->drain_next) && !ctx->submit_state.link.head) {
+			ctx->drain_next = false;
+			ctx->drain_active = true;
+			req->flags |= REQ_F_IO_DRAIN | REQ_F_FORCE_ASYNC;
+		}
+	}
+
+	if (!def->ioprio && sqe->ioprio)
+		return -EINVAL;
+	if (!def->iopoll && (ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	if (def->needs_file) {
+		struct io_submit_state *state = &ctx->submit_state;
+
+		req->cqe.fd = READ_ONCE(sqe->fd);
+
+		/*
+		 * Plug now if we have more than 2 IO left after this, and the
+		 * target is potentially a read/write to block based storage.
+		 */
+		if (state->need_plug && def->plug) {
+			state->plug_started = true;
+			state->need_plug = false;
+			blk_start_plug_nr_ios(&state->plug, state->submit_nr);
+		}
+	}
+
+	personality = READ_ONCE(sqe->personality);
+	if (personality) {
+		int ret;
+
+		req->creds = xa_load(&ctx->personalities, personality);
+		if (!req->creds)
+			return -EINVAL;
+		get_cred(req->creds);
+		ret = security_uring_override_creds(req->creds);
+		if (ret) {
+			put_cred(req->creds);
+			return ret;
+		}
+		req->flags |= REQ_F_CREDS;
+	}
+
+	return def->prep(req, sqe);
+}
+
+static __cold int io_submit_fail_init(const struct io_uring_sqe *sqe,
+				      struct io_kiocb *req, int ret)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_submit_link *link = &ctx->submit_state.link;
+	struct io_kiocb *head = link->head;
+
+	trace_io_uring_req_failed(sqe, req, ret);
+
+	/*
+	 * Avoid breaking links in the middle as it renders links with SQPOLL
+	 * unusable. Instead of failing eagerly, continue assembling the link if
+	 * applicable and mark the head with REQ_F_FAIL. The link flushing code
+	 * should find the flag and handle the rest.
+	 */
+	req_fail_link_node(req, ret);
+	if (head && !(head->flags & REQ_F_FAIL))
+		req_fail_link_node(head, -ECANCELED);
+
+	if (!(req->flags & IO_REQ_LINK_FLAGS)) {
+		if (head) {
+			link->last->link = req;
+			link->head = NULL;
+			req = head;
+		}
+		io_queue_sqe_fallback(req);
+		return ret;
+	}
+
+	if (head)
+		link->last->link = req;
+	else
+		link->head = req;
+	link->last = req;
+	return 0;
+}
+
+static inline int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
+			 const struct io_uring_sqe *sqe)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_link *link = &ctx->submit_state.link;
+	int ret;
+
+	ret = io_init_req(ctx, req, sqe);
+	if (unlikely(ret))
+		return io_submit_fail_init(sqe, req, ret);
+
+	trace_io_uring_submit_req(req);
+
+	/*
+	 * 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 (unlikely(link->head)) {
+		ret = io_req_prep_async(req);
+		if (unlikely(ret))
+			return io_submit_fail_init(sqe, req, ret);
+
+		trace_io_uring_link(req, link->head);
+		link->last->link = req;
+		link->last = req;
+
+		if (req->flags & IO_REQ_LINK_FLAGS)
+			return 0;
+		/* last request of the link, flush it */
+		req = link->head;
+		link->head = NULL;
+		if (req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL))
+			goto fallback;
+
+	} else if (unlikely(req->flags & (IO_REQ_LINK_FLAGS |
+					  REQ_F_FORCE_ASYNC | REQ_F_FAIL))) {
+		if (req->flags & IO_REQ_LINK_FLAGS) {
+			link->head = req;
+			link->last = req;
+		} else {
+fallback:
+			io_queue_sqe_fallback(req);
+		}
+		return 0;
+	}
+
+	io_queue_sqe(req);
+	return 0;
+}
+
+/*
+ * Batched submission is done, ensure local IO is flushed out.
+ */
+static void io_submit_state_end(struct io_ring_ctx *ctx)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+
+	if (unlikely(state->link.head))
+		io_queue_sqe_fallback(state->link.head);
+	/* flush only after queuing links as they can generate completions */
+	io_submit_flush_completions(ctx);
+	if (state->plug_started)
+		blk_finish_plug(&state->plug);
+}
+
+/*
+ * Start submission side cache.
+ */
+static void io_submit_state_start(struct io_submit_state *state,
+				  unsigned int max_ios)
+{
+	state->plug_started = false;
+	state->need_plug = max_ios > 2;
+	state->submit_nr = max_ios;
+	/* set only head, no need to init link_last in advance */
+	state->link.head = NULL;
+}
+
+static void io_commit_sqring(struct io_ring_ctx *ctx)
+{
+	struct io_rings *rings = ctx->rings;
+
+	/*
+	 * 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 this returns a pointer 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_sqe(struct io_ring_ctx *ctx, const struct io_uring_sqe **sqe)
+{
+	unsigned mask = ctx->sq_entries - 1;
+	unsigned head = ctx->cached_sq_head++ & mask;
+
+	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY)) {
+		head = READ_ONCE(ctx->sq_array[head]);
+		if (unlikely(head >= ctx->sq_entries)) {
+			/* drop invalid entries */
+			spin_lock(&ctx->completion_lock);
+			ctx->cq_extra--;
+			spin_unlock(&ctx->completion_lock);
+			WRITE_ONCE(ctx->rings->sq_dropped,
+				   READ_ONCE(ctx->rings->sq_dropped) + 1);
+			return false;
+		}
+	}
+
+	/*
+	 * 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.
+	 */
+
+	/* double index for 128-byte SQEs, twice as long */
+	if (ctx->flags & IORING_SETUP_SQE128)
+		head <<= 1;
+	*sqe = &ctx->sq_sqes[head];
+	return true;
+}
+
+int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
+	__must_hold(&ctx->uring_lock)
+{
+	unsigned int entries = io_sqring_entries(ctx);
+	unsigned int left;
+	int ret;
+
+	if (unlikely(!entries))
+		return 0;
+	/* make sure SQ entry isn't read before tail */
+	ret = left = min(nr, entries);
+	io_get_task_refs(left);
+	io_submit_state_start(&ctx->submit_state, left);
+
+	do {
+		const struct io_uring_sqe *sqe;
+		struct io_kiocb *req;
+
+		if (unlikely(!io_alloc_req(ctx, &req)))
+			break;
+		if (unlikely(!io_get_sqe(ctx, &sqe))) {
+			io_req_add_to_cache(req, ctx);
+			break;
+		}
+
+		/*
+		 * Continue submitting even for sqe failure if the
+		 * ring was setup with IORING_SETUP_SUBMIT_ALL
+		 */
+		if (unlikely(io_submit_sqe(ctx, req, sqe)) &&
+		    !(ctx->flags & IORING_SETUP_SUBMIT_ALL)) {
+			left--;
+			break;
+		}
+	} while (--left);
+
+	if (unlikely(left)) {
+		ret -= left;
+		/* try again if it submitted nothing and can't allocate a req */
+		if (!ret && io_req_cache_empty(ctx))
+			ret = -EAGAIN;
+		current->io_uring->cached_refs += left;
+	}
+
+	io_submit_state_end(ctx);
+	 /* Commit SQ ring head once we've consumed and submitted all SQEs */
+	io_commit_sqring(ctx);
+	return ret;
+}
+
+struct io_wait_queue {
+	struct wait_queue_entry wq;
+	struct io_ring_ctx *ctx;
+	unsigned cq_tail;
+	unsigned nr_timeouts;
+	ktime_t timeout;
+};
+
+static inline bool io_has_work(struct io_ring_ctx *ctx)
+{
+	return test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq) ||
+	       !llist_empty(&ctx->work_llist);
+}
+
+static inline bool io_should_wake(struct io_wait_queue *iowq)
+{
+	struct io_ring_ctx *ctx = iowq->ctx;
+	int dist = READ_ONCE(ctx->rings->cq.tail) - (int) iowq->cq_tail;
+
+	/*
+	 * Wake up if we have enough events, or if a timeout occurred since we
+	 * started waiting. For timeouts, we always want to return to userspace,
+	 * regardless of event count.
+	 */
+	return dist >= 0 || 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);
+
+	/*
+	 * Cannot safely flush overflowed CQEs from here, ensure we wake up
+	 * the task, and the next invocation will do it.
+	 */
+	if (io_should_wake(iowq) || io_has_work(iowq->ctx))
+		return autoremove_wake_function(curr, mode, wake_flags, key);
+	return -1;
+}
+
+int io_run_task_work_sig(struct io_ring_ctx *ctx)
+{
+	if (!llist_empty(&ctx->work_llist)) {
+		__set_current_state(TASK_RUNNING);
+		if (io_run_local_work(ctx) > 0)
+			return 0;
+	}
+	if (io_run_task_work() > 0)
+		return 0;
+	if (task_sigpending(current))
+		return -EINTR;
+	return 0;
+}
+
+static bool current_pending_io(void)
+{
+	struct io_uring_task *tctx = current->io_uring;
+
+	if (!tctx)
+		return false;
+	return percpu_counter_read_positive(&tctx->inflight);
+}
+
+/* when returns >0, the caller should retry */
+static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
+					  struct io_wait_queue *iowq)
+{
+	int io_wait, ret;
+
+	if (unlikely(READ_ONCE(ctx->check_cq)))
+		return 1;
+	if (unlikely(!llist_empty(&ctx->work_llist)))
+		return 1;
+	if (unlikely(test_thread_flag(TIF_NOTIFY_SIGNAL)))
+		return 1;
+	if (unlikely(task_sigpending(current)))
+		return -EINTR;
+	if (unlikely(io_should_wake(iowq)))
+		return 0;
+
+	/*
+	 * Mark us as being in io_wait if we have pending requests, so cpufreq
+	 * can take into account that the task is waiting for IO - turns out
+	 * to be important for low QD IO.
+	 */
+	io_wait = current->in_iowait;
+	if (current_pending_io())
+		current->in_iowait = 1;
+	ret = 0;
+	if (iowq->timeout == KTIME_MAX)
+		schedule();
+	else if (!schedule_hrtimeout(&iowq->timeout, HRTIMER_MODE_ABS))
+		ret = -ETIME;
+	current->in_iowait = io_wait;
+	return ret;
+}
+
+/*
+ * 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 __kernel_timespec __user *uts)
+{
+	struct io_wait_queue iowq;
+	struct io_rings *rings = ctx->rings;
+	int ret;
+
+	if (!io_allowed_run_tw(ctx))
+		return -EEXIST;
+	if (!llist_empty(&ctx->work_llist))
+		io_run_local_work(ctx);
+	io_run_task_work();
+	io_cqring_overflow_flush(ctx);
+	/* if user messes with these they will just get an early return */
+	if (__io_cqring_events_user(ctx) >= 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;
+	}
+
+	init_waitqueue_func_entry(&iowq.wq, io_wake_function);
+	iowq.wq.private = current;
+	INIT_LIST_HEAD(&iowq.wq.entry);
+	iowq.ctx = ctx;
+	iowq.nr_timeouts = atomic_read(&ctx->cq_timeouts);
+	iowq.cq_tail = READ_ONCE(ctx->rings->cq.head) + min_events;
+	iowq.timeout = KTIME_MAX;
+
+	if (uts) {
+		struct timespec64 ts;
+
+		if (get_timespec64(&ts, uts))
+			return -EFAULT;
+		iowq.timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
+	}
+
+	trace_io_uring_cqring_wait(ctx, min_events);
+	do {
+		unsigned long check_cq;
+
+		if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
+			int nr_wait = (int) iowq.cq_tail - READ_ONCE(ctx->rings->cq.tail);
+
+			atomic_set(&ctx->cq_wait_nr, nr_wait);
+			set_current_state(TASK_INTERRUPTIBLE);
+		} else {
+			prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
+							TASK_INTERRUPTIBLE);
+		}
+
+		ret = io_cqring_wait_schedule(ctx, &iowq);
+		__set_current_state(TASK_RUNNING);
+		atomic_set(&ctx->cq_wait_nr, 0);
+
+		/*
+		 * Run task_work after scheduling and before io_should_wake().
+		 * If we got woken because of task_work being processed, run it
+		 * now rather than let the caller do another wait loop.
+		 */
+		io_run_task_work();
+		if (!llist_empty(&ctx->work_llist))
+			io_run_local_work(ctx);
+
+		/*
+		 * Non-local task_work will be run on exit to userspace, but
+		 * if we're using DEFER_TASKRUN, then we could have waited
+		 * with a timeout for a number of requests. If the timeout
+		 * hits, we could have some requests ready to process. Ensure
+		 * this break is _after_ we have run task_work, to avoid
+		 * deferring running potentially pending requests until the
+		 * next time we wait for events.
+		 */
+		if (ret < 0)
+			break;
+
+		check_cq = READ_ONCE(ctx->check_cq);
+		if (unlikely(check_cq)) {
+			/* let the caller flush overflows, retry */
+			if (check_cq & BIT(IO_CHECK_CQ_OVERFLOW_BIT))
+				io_cqring_do_overflow_flush(ctx);
+			if (check_cq & BIT(IO_CHECK_CQ_DROPPED_BIT)) {
+				ret = -EBADR;
+				break;
+			}
+		}
+
+		if (io_should_wake(&iowq)) {
+			ret = 0;
+			break;
+		}
+		cond_resched();
+	} while (1);
+
+	if (!(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
+		finish_wait(&ctx->cq_wait, &iowq.wq);
+	restore_saved_sigmask_unless(ret == -EINTR);
+
+	return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
+}
+
+void io_mem_free(void *ptr)
+{
+	if (!ptr)
+		return;
+
+	folio_put(virt_to_folio(ptr));
+}
+
+static void io_pages_free(struct page ***pages, int npages)
+{
+	struct page **page_array;
+	int i;
+
+	if (!pages)
+		return;
+
+	page_array = *pages;
+	if (!page_array)
+		return;
+
+	for (i = 0; i < npages; i++)
+		unpin_user_page(page_array[i]);
+	kvfree(page_array);
+	*pages = NULL;
+}
+
+static void *__io_uaddr_map(struct page ***pages, unsigned short *npages,
+			    unsigned long uaddr, size_t size)
+{
+	struct page **page_array;
+	unsigned int nr_pages;
+	void *page_addr;
+	int ret, i;
+
+	*npages = 0;
+
+	if (uaddr & (PAGE_SIZE - 1) || !size)
+		return ERR_PTR(-EINVAL);
+
+	nr_pages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	if (nr_pages > USHRT_MAX)
+		return ERR_PTR(-EINVAL);
+	page_array = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
+	if (!page_array)
+		return ERR_PTR(-ENOMEM);
+
+	ret = pin_user_pages_fast(uaddr, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
+					page_array);
+	if (ret != nr_pages) {
+err:
+		io_pages_free(&page_array, ret > 0 ? ret : 0);
+		return ret < 0 ? ERR_PTR(ret) : ERR_PTR(-EFAULT);
+	}
+
+	page_addr = page_address(page_array[0]);
+	for (i = 0; i < nr_pages; i++) {
+		ret = -EINVAL;
+
+		/*
+		 * Can't support mapping user allocated ring memory on 32-bit
+		 * archs where it could potentially reside in highmem. Just
+		 * fail those with -EINVAL, just like we did on kernels that
+		 * didn't support this feature.
+		 */
+		if (PageHighMem(page_array[i]))
+			goto err;
+
+		/*
+		 * No support for discontig pages for now, should either be a
+		 * single normal page, or a huge page. Later on we can add
+		 * support for remapping discontig pages, for now we will
+		 * just fail them with EINVAL.
+		 */
+		if (page_address(page_array[i]) != page_addr)
+			goto err;
+		page_addr += PAGE_SIZE;
+	}
+
+	*pages = page_array;
+	*npages = nr_pages;
+	return page_to_virt(page_array[0]);
+}
+
+static void *io_rings_map(struct io_ring_ctx *ctx, unsigned long uaddr,
+			  size_t size)
+{
+	return __io_uaddr_map(&ctx->ring_pages, &ctx->n_ring_pages, uaddr,
+				size);
+}
+
+static void *io_sqes_map(struct io_ring_ctx *ctx, unsigned long uaddr,
+			 size_t size)
+{
+	return __io_uaddr_map(&ctx->sqe_pages, &ctx->n_sqe_pages, uaddr,
+				size);
+}
+
+static void io_rings_free(struct io_ring_ctx *ctx)
+{
+	if (!(ctx->flags & IORING_SETUP_NO_MMAP)) {
+		io_mem_free(ctx->rings);
+		io_mem_free(ctx->sq_sqes);
+		ctx->rings = NULL;
+		ctx->sq_sqes = NULL;
+	} else {
+		io_pages_free(&ctx->ring_pages, ctx->n_ring_pages);
+		ctx->n_ring_pages = 0;
+		io_pages_free(&ctx->sqe_pages, ctx->n_sqe_pages);
+		ctx->n_sqe_pages = 0;
+	}
+}
+
+void *io_mem_alloc(size_t size)
+{
+	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
+	void *ret;
+
+	ret = (void *) __get_free_pages(gfp, get_order(size));
+	if (ret)
+		return ret;
+	return ERR_PTR(-ENOMEM);
+}
+
+static unsigned long rings_size(struct io_ring_ctx *ctx, unsigned int sq_entries,
+				unsigned int 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;
+	if (ctx->flags & IORING_SETUP_CQE32) {
+		if (check_shl_overflow(off, 1, &off))
+			return SIZE_MAX;
+	}
+
+#ifdef CONFIG_SMP
+	off = ALIGN(off, SMP_CACHE_BYTES);
+	if (off == 0)
+		return SIZE_MAX;
+#endif
+
+	if (ctx->flags & IORING_SETUP_NO_SQARRAY) {
+		if (sq_offset)
+			*sq_offset = SIZE_MAX;
+		return off;
+	}
+
+	if (sq_offset)
+		*sq_offset = off;
+
+	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;
+
+	return off;
+}
+
+static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg,
+			       unsigned int eventfd_async)
+{
+	struct io_ev_fd *ev_fd;
+	__s32 __user *fds = arg;
+	int fd;
+
+	ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
+					lockdep_is_held(&ctx->uring_lock));
+	if (ev_fd)
+		return -EBUSY;
+
+	if (copy_from_user(&fd, fds, sizeof(*fds)))
+		return -EFAULT;
+
+	ev_fd = kmalloc(sizeof(*ev_fd), GFP_KERNEL);
+	if (!ev_fd)
+		return -ENOMEM;
+
+	ev_fd->cq_ev_fd = eventfd_ctx_fdget(fd);
+	if (IS_ERR(ev_fd->cq_ev_fd)) {
+		int ret = PTR_ERR(ev_fd->cq_ev_fd);
+		kfree(ev_fd);
+		return ret;
+	}
+
+	spin_lock(&ctx->completion_lock);
+	ctx->evfd_last_cq_tail = ctx->cached_cq_tail;
+	spin_unlock(&ctx->completion_lock);
+
+	ev_fd->eventfd_async = eventfd_async;
+	ctx->has_evfd = true;
+	rcu_assign_pointer(ctx->io_ev_fd, ev_fd);
+	atomic_set(&ev_fd->refs, 1);
+	atomic_set(&ev_fd->ops, 0);
+	return 0;
+}
+
+static int io_eventfd_unregister(struct io_ring_ctx *ctx)
+{
+	struct io_ev_fd *ev_fd;
+
+	ev_fd = rcu_dereference_protected(ctx->io_ev_fd,
+					lockdep_is_held(&ctx->uring_lock));
+	if (ev_fd) {
+		ctx->has_evfd = false;
+		rcu_assign_pointer(ctx->io_ev_fd, NULL);
+		if (!atomic_fetch_or(BIT(IO_EVENTFD_OP_FREE_BIT), &ev_fd->ops))
+			call_rcu(&ev_fd->rcu, io_eventfd_ops);
+		return 0;
+	}
+
+	return -ENXIO;
+}
+
+static void io_req_caches_free(struct io_ring_ctx *ctx)
+{
+	struct io_kiocb *req;
+	int nr = 0;
+
+	mutex_lock(&ctx->uring_lock);
+	io_flush_cached_locked_reqs(ctx, &ctx->submit_state);
+
+	while (!io_req_cache_empty(ctx)) {
+		req = io_extract_req(ctx);
+		kmem_cache_free(req_cachep, req);
+		nr++;
+	}
+	if (nr)
+		percpu_ref_put_many(&ctx->refs, nr);
+	mutex_unlock(&ctx->uring_lock);
+}
+
+static void io_rsrc_node_cache_free(struct io_cache_entry *entry)
+{
+	kfree(container_of(entry, struct io_rsrc_node, cache));
+}
+
+static __cold void io_ring_ctx_free(struct io_ring_ctx *ctx)
+{
+	io_sq_thread_finish(ctx);
+	/* __io_rsrc_put_work() may need uring_lock to progress, wait w/o it */
+	if (WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list)))
+		return;
+
+	mutex_lock(&ctx->uring_lock);
+	if (ctx->buf_data)
+		__io_sqe_buffers_unregister(ctx);
+	if (ctx->file_data)
+		__io_sqe_files_unregister(ctx);
+	io_cqring_overflow_kill(ctx);
+	io_eventfd_unregister(ctx);
+	io_alloc_cache_free(&ctx->apoll_cache, io_apoll_cache_free);
+	io_alloc_cache_free(&ctx->netmsg_cache, io_netmsg_cache_free);
+	io_destroy_buffers(ctx);
+	mutex_unlock(&ctx->uring_lock);
+	if (ctx->sq_creds)
+		put_cred(ctx->sq_creds);
+	if (ctx->submitter_task)
+		put_task_struct(ctx->submitter_task);
+
+	/* there are no registered resources left, nobody uses it */
+	if (ctx->rsrc_node)
+		io_rsrc_node_destroy(ctx, ctx->rsrc_node);
+
+	WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
+
+#if defined(CONFIG_UNIX)
+	if (ctx->ring_sock) {
+		ctx->ring_sock->file = NULL; /* so that iput() is called */
+		sock_release(ctx->ring_sock);
+	}
+#endif
+	WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
+
+	io_alloc_cache_free(&ctx->rsrc_node_cache, io_rsrc_node_cache_free);
+	if (ctx->mm_account) {
+		mmdrop(ctx->mm_account);
+		ctx->mm_account = NULL;
+	}
+	io_rings_free(ctx);
+	io_kbuf_mmap_list_free(ctx);
+
+	percpu_ref_exit(&ctx->refs);
+	free_uid(ctx->user);
+	io_req_caches_free(ctx);
+	if (ctx->hash_map)
+		io_wq_put_hash(ctx->hash_map);
+	kfree(ctx->cancel_table.hbs);
+	kfree(ctx->cancel_table_locked.hbs);
+	kfree(ctx->io_bl);
+	xa_destroy(&ctx->io_bl_xa);
+	kfree(ctx);
+}
+
+static __cold void io_activate_pollwq_cb(struct callback_head *cb)
+{
+	struct io_ring_ctx *ctx = container_of(cb, struct io_ring_ctx,
+					       poll_wq_task_work);
+
+	mutex_lock(&ctx->uring_lock);
+	ctx->poll_activated = true;
+	mutex_unlock(&ctx->uring_lock);
+
+	/*
+	 * Wake ups for some events between start of polling and activation
+	 * might've been lost due to loose synchronisation.
+	 */
+	wake_up_all(&ctx->poll_wq);
+	percpu_ref_put(&ctx->refs);
+}
+
+static __cold void io_activate_pollwq(struct io_ring_ctx *ctx)
+{
+	spin_lock(&ctx->completion_lock);
+	/* already activated or in progress */
+	if (ctx->poll_activated || ctx->poll_wq_task_work.func)
+		goto out;
+	if (WARN_ON_ONCE(!ctx->task_complete))
+		goto out;
+	if (!ctx->submitter_task)
+		goto out;
+	/*
+	 * with ->submitter_task only the submitter task completes requests, we
+	 * only need to sync with it, which is done by injecting a tw
+	 */
+	init_task_work(&ctx->poll_wq_task_work, io_activate_pollwq_cb);
+	percpu_ref_get(&ctx->refs);
+	if (task_work_add(ctx->submitter_task, &ctx->poll_wq_task_work, TWA_SIGNAL))
+		percpu_ref_put(&ctx->refs);
+out:
+	spin_unlock(&ctx->completion_lock);
+}
+
+static __poll_t io_uring_poll(struct file *file, poll_table *wait)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+	__poll_t mask = 0;
+
+	if (unlikely(!ctx->poll_activated))
+		io_activate_pollwq(ctx);
+
+	poll_wait(file, &ctx->poll_wq, wait);
+	/*
+	 * synchronizes with barrier from wq_has_sleeper call in
+	 * io_commit_cqring
+	 */
+	smp_rmb();
+	if (!io_sqring_full(ctx))
+		mask |= EPOLLOUT | EPOLLWRNORM;
+
+	/*
+	 * Don't flush cqring overflow list here, just do a simple check.
+	 * Otherwise there could possible be ABBA deadlock:
+	 *      CPU0                    CPU1
+	 *      ----                    ----
+	 * lock(&ctx->uring_lock);
+	 *                              lock(&ep->mtx);
+	 *                              lock(&ctx->uring_lock);
+	 * lock(&ep->mtx);
+	 *
+	 * Users may get EPOLLIN meanwhile seeing nothing in cqring, this
+	 * pushes them to do the flush.
+	 */
+
+	if (__io_cqring_events_user(ctx) || io_has_work(ctx))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	return mask;
+}
+
+static int io_unregister_personality(struct io_ring_ctx *ctx, unsigned id)
+{
+	const struct cred *creds;
+
+	creds = xa_erase(&ctx->personalities, id);
+	if (creds) {
+		put_cred(creds);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+struct io_tctx_exit {
+	struct callback_head		task_work;
+	struct completion		completion;
+	struct io_ring_ctx		*ctx;
+};
+
+static __cold void io_tctx_exit_cb(struct callback_head *cb)
+{
+	struct io_uring_task *tctx = current->io_uring;
+	struct io_tctx_exit *work;
+
+	work = container_of(cb, struct io_tctx_exit, task_work);
+	/*
+	 * When @in_cancel, we're in cancellation and it's racy to remove the
+	 * node. It'll be removed by the end of cancellation, just ignore it.
+	 * tctx can be NULL if the queueing of this task_work raced with
+	 * work cancelation off the exec path.
+	 */
+	if (tctx && !atomic_read(&tctx->in_cancel))
+		io_uring_del_tctx_node((unsigned long)work->ctx);
+	complete(&work->completion);
+}
+
+static __cold bool io_cancel_ctx_cb(struct io_wq_work *work, void *data)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+
+	return req->ctx == data;
+}
+
+static __cold void io_ring_exit_work(struct work_struct *work)
+{
+	struct io_ring_ctx *ctx = container_of(work, struct io_ring_ctx, exit_work);
+	unsigned long timeout = jiffies + HZ * 60 * 5;
+	unsigned long interval = HZ / 20;
+	struct io_tctx_exit exit;
+	struct io_tctx_node *node;
+	int ret;
+
+	/*
+	 * If we're doing polled IO and end up having requests being
+	 * submitted async (out-of-line), then completions can come in while
+	 * we're waiting for refs to drop. We need to reap these manually,
+	 * as nobody else will be looking for them.
+	 */
+	do {
+		if (test_bit(IO_CHECK_CQ_OVERFLOW_BIT, &ctx->check_cq)) {
+			mutex_lock(&ctx->uring_lock);
+			io_cqring_overflow_kill(ctx);
+			mutex_unlock(&ctx->uring_lock);
+		}
+
+		if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
+			io_move_task_work_from_local(ctx);
+
+		while (io_uring_try_cancel_requests(ctx, NULL, true))
+			cond_resched();
+
+		if (ctx->sq_data) {
+			struct io_sq_data *sqd = ctx->sq_data;
+			struct task_struct *tsk;
+
+			io_sq_thread_park(sqd);
+			tsk = sqd->thread;
+			if (tsk && tsk->io_uring && tsk->io_uring->io_wq)
+				io_wq_cancel_cb(tsk->io_uring->io_wq,
+						io_cancel_ctx_cb, ctx, true);
+			io_sq_thread_unpark(sqd);
+		}
+
+		io_req_caches_free(ctx);
+
+		if (WARN_ON_ONCE(time_after(jiffies, timeout))) {
+			/* there is little hope left, don't run it too often */
+			interval = HZ * 60;
+		}
+		/*
+		 * This is really an uninterruptible wait, as it has to be
+		 * complete. But it's also run from a kworker, which doesn't
+		 * take signals, so it's fine to make it interruptible. This
+		 * avoids scenarios where we knowingly can wait much longer
+		 * on completions, for example if someone does a SIGSTOP on
+		 * a task that needs to finish task_work to make this loop
+		 * complete. That's a synthetic situation that should not
+		 * cause a stuck task backtrace, and hence a potential panic
+		 * on stuck tasks if that is enabled.
+		 */
+	} while (!wait_for_completion_interruptible_timeout(&ctx->ref_comp, interval));
+
+	init_completion(&exit.completion);
+	init_task_work(&exit.task_work, io_tctx_exit_cb);
+	exit.ctx = ctx;
+
+	mutex_lock(&ctx->uring_lock);
+	while (!list_empty(&ctx->tctx_list)) {
+		WARN_ON_ONCE(time_after(jiffies, timeout));
+
+		node = list_first_entry(&ctx->tctx_list, struct io_tctx_node,
+					ctx_node);
+		/* don't spin on a single task if cancellation failed */
+		list_rotate_left(&ctx->tctx_list);
+		ret = task_work_add(node->task, &exit.task_work, TWA_SIGNAL);
+		if (WARN_ON_ONCE(ret))
+			continue;
+
+		mutex_unlock(&ctx->uring_lock);
+		/*
+		 * See comment above for
+		 * wait_for_completion_interruptible_timeout() on why this
+		 * wait is marked as interruptible.
+		 */
+		wait_for_completion_interruptible(&exit.completion);
+		mutex_lock(&ctx->uring_lock);
+	}
+	mutex_unlock(&ctx->uring_lock);
+	spin_lock(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
+
+	/* pairs with RCU read section in io_req_local_work_add() */
+	if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
+		synchronize_rcu();
+
+	io_ring_ctx_free(ctx);
+}
+
+static __cold void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
+{
+	unsigned long index;
+	struct creds *creds;
+
+	mutex_lock(&ctx->uring_lock);
+	percpu_ref_kill(&ctx->refs);
+	xa_for_each(&ctx->personalities, index, creds)
+		io_unregister_personality(ctx, index);
+	if (ctx->rings)
+		io_poll_remove_all(ctx, NULL, true);
+	mutex_unlock(&ctx->uring_lock);
+
+	/*
+	 * If we failed setting up the ctx, we might not have any rings
+	 * and therefore did not submit any requests
+	 */
+	if (ctx->rings)
+		io_kill_timeouts(ctx, NULL, true);
+
+	flush_delayed_work(&ctx->fallback_work);
+
+	INIT_WORK(&ctx->exit_work, io_ring_exit_work);
+	/*
+	 * Use system_unbound_wq to avoid spawning tons of event kworkers
+	 * if we're exiting a ton of rings at the same time. It just adds
+	 * noise and overhead, there's no discernable change in runtime
+	 * over using system_wq.
+	 */
+	queue_work(system_unbound_wq, &ctx->exit_work);
+}
+
+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;
+}
+
+struct io_task_cancel {
+	struct task_struct *task;
+	bool all;
+};
+
+static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	struct io_task_cancel *cancel = data;
+
+	return io_match_task_safe(req, cancel->task, cancel->all);
+}
+
+static __cold bool io_cancel_defer_files(struct io_ring_ctx *ctx,
+					 struct task_struct *task,
+					 bool cancel_all)
+{
+	struct io_defer_entry *de;
+	LIST_HEAD(list);
+
+	spin_lock(&ctx->completion_lock);
+	list_for_each_entry_reverse(de, &ctx->defer_list, list) {
+		if (io_match_task_safe(de->req, task, cancel_all)) {
+			list_cut_position(&list, &ctx->defer_list, &de->list);
+			break;
+		}
+	}
+	spin_unlock(&ctx->completion_lock);
+	if (list_empty(&list))
+		return false;
+
+	while (!list_empty(&list)) {
+		de = list_first_entry(&list, struct io_defer_entry, list);
+		list_del_init(&de->list);
+		io_req_task_queue_fail(de->req, -ECANCELED);
+		kfree(de);
+	}
+	return true;
+}
+
+static __cold bool io_uring_try_cancel_iowq(struct io_ring_ctx *ctx)
+{
+	struct io_tctx_node *node;
+	enum io_wq_cancel cret;
+	bool ret = false;
+
+	mutex_lock(&ctx->uring_lock);
+	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
+		struct io_uring_task *tctx = node->task->io_uring;
+
+		/*
+		 * io_wq will stay alive while we hold uring_lock, because it's
+		 * killed after ctx nodes, which requires to take the lock.
+		 */
+		if (!tctx || !tctx->io_wq)
+			continue;
+		cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_ctx_cb, ctx, true);
+		ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
+	}
+	mutex_unlock(&ctx->uring_lock);
+
+	return ret;
+}
+
+static __cold bool io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
+						struct task_struct *task,
+						bool cancel_all)
+{
+	struct io_task_cancel cancel = { .task = task, .all = cancel_all, };
+	struct io_uring_task *tctx = task ? task->io_uring : NULL;
+	enum io_wq_cancel cret;
+	bool ret = false;
+
+	/* set it so io_req_local_work_add() would wake us up */
+	if (ctx->flags & IORING_SETUP_DEFER_TASKRUN) {
+		atomic_set(&ctx->cq_wait_nr, 1);
+		smp_mb();
+	}
+
+	/* failed during ring init, it couldn't have issued any requests */
+	if (!ctx->rings)
+		return false;
+
+	if (!task) {
+		ret |= io_uring_try_cancel_iowq(ctx);
+	} else if (tctx && tctx->io_wq) {
+		/*
+		 * Cancels requests of all rings, not only @ctx, but
+		 * it's fine as the task is in exit/exec.
+		 */
+		cret = io_wq_cancel_cb(tctx->io_wq, io_cancel_task_cb,
+				       &cancel, true);
+		ret |= (cret != IO_WQ_CANCEL_NOTFOUND);
+	}
+
+	/* SQPOLL thread does its own polling */
+	if ((!(ctx->flags & IORING_SETUP_SQPOLL) && cancel_all) ||
+	    (ctx->sq_data && ctx->sq_data->thread == current)) {
+		while (!wq_list_empty(&ctx->iopoll_list)) {
+			io_iopoll_try_reap_events(ctx);
+			ret = true;
+			cond_resched();
+		}
+	}
+
+	if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
+	    io_allowed_defer_tw_run(ctx))
+		ret |= io_run_local_work(ctx) > 0;
+	ret |= io_cancel_defer_files(ctx, task, cancel_all);
+	mutex_lock(&ctx->uring_lock);
+	ret |= io_poll_remove_all(ctx, task, cancel_all);
+	mutex_unlock(&ctx->uring_lock);
+	ret |= io_kill_timeouts(ctx, task, cancel_all);
+	if (task)
+		ret |= io_run_task_work() > 0;
+	return ret;
+}
+
+static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked)
+{
+	if (tracked)
+		return atomic_read(&tctx->inflight_tracked);
+	return percpu_counter_sum(&tctx->inflight);
+}
+
+/*
+ * Find any io_uring ctx that this task has registered or done IO on, and cancel
+ * requests. @sqd should be not-null IFF it's an SQPOLL thread cancellation.
+ */
+__cold void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
+{
+	struct io_uring_task *tctx = current->io_uring;
+	struct io_ring_ctx *ctx;
+	struct io_tctx_node *node;
+	unsigned long index;
+	s64 inflight;
+	DEFINE_WAIT(wait);
+
+	WARN_ON_ONCE(sqd && sqd->thread != current);
+
+	if (!current->io_uring)
+		return;
+	if (tctx->io_wq)
+		io_wq_exit_start(tctx->io_wq);
+
+	atomic_inc(&tctx->in_cancel);
+	do {
+		bool loop = false;
+
+		io_uring_drop_tctx_refs(current);
+		/* read completions before cancelations */
+		inflight = tctx_inflight(tctx, !cancel_all);
+		if (!inflight)
+			break;
+
+		if (!sqd) {
+			xa_for_each(&tctx->xa, index, node) {
+				/* sqpoll task will cancel all its requests */
+				if (node->ctx->sq_data)
+					continue;
+				loop |= io_uring_try_cancel_requests(node->ctx,
+							current, cancel_all);
+			}
+		} else {
+			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+				loop |= io_uring_try_cancel_requests(ctx,
+								     current,
+								     cancel_all);
+		}
+
+		if (loop) {
+			cond_resched();
+			continue;
+		}
+
+		prepare_to_wait(&tctx->wait, &wait, TASK_INTERRUPTIBLE);
+		io_run_task_work();
+		io_uring_drop_tctx_refs(current);
+		xa_for_each(&tctx->xa, index, node) {
+			if (!llist_empty(&node->ctx->work_llist)) {
+				WARN_ON_ONCE(node->ctx->submitter_task &&
+					     node->ctx->submitter_task != current);
+				goto end_wait;
+			}
+		}
+		/*
+		 * If we've seen completions, retry without waiting. This
+		 * avoids a race where a completion comes in before we did
+		 * prepare_to_wait().
+		 */
+		if (inflight == tctx_inflight(tctx, !cancel_all))
+			schedule();
+end_wait:
+		finish_wait(&tctx->wait, &wait);
+	} while (1);
+
+	io_uring_clean_tctx(tctx);
+	if (cancel_all) {
+		/*
+		 * We shouldn't run task_works after cancel, so just leave
+		 * ->in_cancel set for normal exit.
+		 */
+		atomic_dec(&tctx->in_cancel);
+		/* for exec all current's requests should be gone, kill tctx */
+		__io_uring_free(current);
+	}
+}
+
+void __io_uring_cancel(bool cancel_all)
+{
+	io_uring_cancel_generic(cancel_all, NULL);
+}
+
+static void *io_uring_validate_mmap_request(struct file *file,
+					    loff_t pgoff, size_t sz)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+	loff_t offset = pgoff << PAGE_SHIFT;
+	struct page *page;
+	void *ptr;
+
+	switch (offset & IORING_OFF_MMAP_MASK) {
+	case IORING_OFF_SQ_RING:
+	case IORING_OFF_CQ_RING:
+		/* Don't allow mmap if the ring was setup without it */
+		if (ctx->flags & IORING_SETUP_NO_MMAP)
+			return ERR_PTR(-EINVAL);
+		ptr = ctx->rings;
+		break;
+	case IORING_OFF_SQES:
+		/* Don't allow mmap if the ring was setup without it */
+		if (ctx->flags & IORING_SETUP_NO_MMAP)
+			return ERR_PTR(-EINVAL);
+		ptr = ctx->sq_sqes;
+		break;
+	case IORING_OFF_PBUF_RING: {
+		unsigned int bgid;
+
+		bgid = (offset & ~IORING_OFF_MMAP_MASK) >> IORING_OFF_PBUF_SHIFT;
+		rcu_read_lock();
+		ptr = io_pbuf_get_address(ctx, bgid);
+		rcu_read_unlock();
+		if (!ptr)
+			return ERR_PTR(-EINVAL);
+		break;
+		}
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	page = virt_to_head_page(ptr);
+	if (sz > page_size(page))
+		return ERR_PTR(-EINVAL);
+
+	return ptr;
+}
+
+#ifdef CONFIG_MMU
+
+static __cold int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	size_t sz = vma->vm_end - vma->vm_start;
+	unsigned long pfn;
+	void *ptr;
+
+	ptr = io_uring_validate_mmap_request(file, vma->vm_pgoff, sz);
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
+	return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
+}
+
+static unsigned long io_uring_mmu_get_unmapped_area(struct file *filp,
+			unsigned long addr, unsigned long len,
+			unsigned long pgoff, unsigned long flags)
+{
+	void *ptr;
+
+	/*
+	 * Do not allow to map to user-provided address to avoid breaking the
+	 * aliasing rules. Userspace is not able to guess the offset address of
+	 * kernel kmalloc()ed memory area.
+	 */
+	if (addr)
+		return -EINVAL;
+
+	ptr = io_uring_validate_mmap_request(filp, pgoff, len);
+	if (IS_ERR(ptr))
+		return -ENOMEM;
+
+	/*
+	 * Some architectures have strong cache aliasing requirements.
+	 * For such architectures we need a coherent mapping which aliases
+	 * kernel memory *and* userspace memory. To achieve that:
+	 * - use a NULL file pointer to reference physical memory, and
+	 * - use the kernel virtual address of the shared io_uring context
+	 *   (instead of the userspace-provided address, which has to be 0UL
+	 *   anyway).
+	 * - use the same pgoff which the get_unmapped_area() uses to
+	 *   calculate the page colouring.
+	 * For architectures without such aliasing requirements, the
+	 * architecture will return any suitable mapping because addr is 0.
+	 */
+	filp = NULL;
+	flags |= MAP_SHARED;
+	pgoff = 0;	/* has been translated to ptr above */
+#ifdef SHM_COLOUR
+	addr = (uintptr_t) ptr;
+	pgoff = addr >> PAGE_SHIFT;
+#else
+	addr = 0UL;
+#endif
+	return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
+}
+
+#else /* !CONFIG_MMU */
+
+static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -EINVAL;
+}
+
+static unsigned int io_uring_nommu_mmap_capabilities(struct file *file)
+{
+	return NOMMU_MAP_DIRECT | NOMMU_MAP_READ | NOMMU_MAP_WRITE;
+}
+
+static unsigned long io_uring_nommu_get_unmapped_area(struct file *file,
+	unsigned long addr, unsigned long len,
+	unsigned long pgoff, unsigned long flags)
+{
+	void *ptr;
+
+	ptr = io_uring_validate_mmap_request(file, pgoff, len);
+	if (IS_ERR(ptr))
+		return PTR_ERR(ptr);
+
+	return (unsigned long) ptr;
+}
+
+#endif /* !CONFIG_MMU */
+
+static int io_validate_ext_arg(unsigned flags, const void __user *argp, size_t argsz)
+{
+	if (flags & IORING_ENTER_EXT_ARG) {
+		struct io_uring_getevents_arg arg;
+
+		if (argsz != sizeof(arg))
+			return -EINVAL;
+		if (copy_from_user(&arg, argp, sizeof(arg)))
+			return -EFAULT;
+	}
+	return 0;
+}
+
+static int io_get_ext_arg(unsigned flags, const void __user *argp, size_t *argsz,
+			  struct __kernel_timespec __user **ts,
+			  const sigset_t __user **sig)
+{
+	struct io_uring_getevents_arg arg;
+
+	/*
+	 * If EXT_ARG isn't set, then we have no timespec and the argp pointer
+	 * is just a pointer to the sigset_t.
+	 */
+	if (!(flags & IORING_ENTER_EXT_ARG)) {
+		*sig = (const sigset_t __user *) argp;
+		*ts = NULL;
+		return 0;
+	}
+
+	/*
+	 * EXT_ARG is set - ensure we agree on the size of it and copy in our
+	 * timespec and sigset_t pointers if good.
+	 */
+	if (*argsz != sizeof(arg))
+		return -EINVAL;
+	if (copy_from_user(&arg, argp, sizeof(arg)))
+		return -EFAULT;
+	if (arg.pad)
+		return -EINVAL;
+	*sig = u64_to_user_ptr(arg.sigmask);
+	*argsz = arg.sigmask_sz;
+	*ts = u64_to_user_ptr(arg.ts);
+	return 0;
+}
+
+SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
+		u32, min_complete, u32, flags, const void __user *, argp,
+		size_t, argsz)
+{
+	struct io_ring_ctx *ctx;
+	struct file *file;
+	long ret;
+
+	if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP |
+			       IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG |
+			       IORING_ENTER_REGISTERED_RING)))
+		return -EINVAL;
+
+	/*
+	 * Ring fd has been registered via IORING_REGISTER_RING_FDS, we
+	 * need only dereference our task private array to find it.
+	 */
+	if (flags & IORING_ENTER_REGISTERED_RING) {
+		struct io_uring_task *tctx = current->io_uring;
+
+		if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
+			return -EINVAL;
+		fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
+		file = tctx->registered_rings[fd];
+		if (unlikely(!file))
+			return -EBADF;
+	} else {
+		file = fget(fd);
+		if (unlikely(!file))
+			return -EBADF;
+		ret = -EOPNOTSUPP;
+		if (unlikely(!io_is_uring_fops(file)))
+			goto out;
+	}
+
+	ctx = file->private_data;
+	ret = -EBADFD;
+	if (unlikely(ctx->flags & IORING_SETUP_R_DISABLED))
+		goto out;
+
+	/*
+	 * 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) {
+		io_cqring_overflow_flush(ctx);
+
+		if (unlikely(ctx->sq_data->thread == NULL)) {
+			ret = -EOWNERDEAD;
+			goto out;
+		}
+		if (flags & IORING_ENTER_SQ_WAKEUP)
+			wake_up(&ctx->sq_data->wait);
+		if (flags & IORING_ENTER_SQ_WAIT)
+			io_sqpoll_wait_sq(ctx);
+
+		ret = to_submit;
+	} else if (to_submit) {
+		ret = io_uring_add_tctx_node(ctx);
+		if (unlikely(ret))
+			goto out;
+
+		mutex_lock(&ctx->uring_lock);
+		ret = io_submit_sqes(ctx, to_submit);
+		if (ret != to_submit) {
+			mutex_unlock(&ctx->uring_lock);
+			goto out;
+		}
+		if (flags & IORING_ENTER_GETEVENTS) {
+			if (ctx->syscall_iopoll)
+				goto iopoll_locked;
+			/*
+			 * Ignore errors, we'll soon call io_cqring_wait() and
+			 * it should handle ownership problems if any.
+			 */
+			if (ctx->flags & IORING_SETUP_DEFER_TASKRUN)
+				(void)io_run_local_work_locked(ctx);
+		}
+		mutex_unlock(&ctx->uring_lock);
+	}
+
+	if (flags & IORING_ENTER_GETEVENTS) {
+		int ret2;
+
+		if (ctx->syscall_iopoll) {
+			/*
+			 * We disallow the app entering submit/complete with
+			 * polling, but we still need to lock the ring to
+			 * prevent racing with polled issue that got punted to
+			 * a workqueue.
+			 */
+			mutex_lock(&ctx->uring_lock);
+iopoll_locked:
+			ret2 = io_validate_ext_arg(flags, argp, argsz);
+			if (likely(!ret2)) {
+				min_complete = min(min_complete,
+						   ctx->cq_entries);
+				ret2 = io_iopoll_check(ctx, min_complete);
+			}
+			mutex_unlock(&ctx->uring_lock);
+		} else {
+			const sigset_t __user *sig;
+			struct __kernel_timespec __user *ts;
+
+			ret2 = io_get_ext_arg(flags, argp, &argsz, &ts, &sig);
+			if (likely(!ret2)) {
+				min_complete = min(min_complete,
+						   ctx->cq_entries);
+				ret2 = io_cqring_wait(ctx, min_complete, sig,
+						      argsz, ts);
+			}
+		}
+
+		if (!ret) {
+			ret = ret2;
+
+			/*
+			 * EBADR indicates that one or more CQE were dropped.
+			 * Once the user has been informed we can clear the bit
+			 * as they are obviously ok with those drops.
+			 */
+			if (unlikely(ret2 == -EBADR))
+				clear_bit(IO_CHECK_CQ_DROPPED_BIT,
+					  &ctx->check_cq);
+		}
+	}
+out:
+	if (!(flags & IORING_ENTER_REGISTERED_RING))
+		fput(file);
+	return ret;
+}
+
+static const struct file_operations io_uring_fops = {
+	.release	= io_uring_release,
+	.mmap		= io_uring_mmap,
+#ifndef CONFIG_MMU
+	.get_unmapped_area = io_uring_nommu_get_unmapped_area,
+	.mmap_capabilities = io_uring_nommu_mmap_capabilities,
+#else
+	.get_unmapped_area = io_uring_mmu_get_unmapped_area,
+#endif
+	.poll		= io_uring_poll,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= io_uring_show_fdinfo,
+#endif
+};
+
+bool io_is_uring_fops(struct file *file)
+{
+	return file->f_op == &io_uring_fops;
+}
+
+static __cold 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;
+	void *ptr;
+
+	/* make sure these are sane, as we already accounted them */
+	ctx->sq_entries = p->sq_entries;
+	ctx->cq_entries = p->cq_entries;
+
+	size = rings_size(ctx, p->sq_entries, p->cq_entries, &sq_array_offset);
+	if (size == SIZE_MAX)
+		return -EOVERFLOW;
+
+	if (!(ctx->flags & IORING_SETUP_NO_MMAP))
+		rings = io_mem_alloc(size);
+	else
+		rings = io_rings_map(ctx, p->cq_off.user_addr, size);
+
+	if (IS_ERR(rings))
+		return PTR_ERR(rings);
+
+	ctx->rings = rings;
+	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
+		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;
+
+	if (p->flags & IORING_SETUP_SQE128)
+		size = array_size(2 * sizeof(struct io_uring_sqe), p->sq_entries);
+	else
+		size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
+	if (size == SIZE_MAX) {
+		io_rings_free(ctx);
+		return -EOVERFLOW;
+	}
+
+	if (!(ctx->flags & IORING_SETUP_NO_MMAP))
+		ptr = io_mem_alloc(size);
+	else
+		ptr = io_sqes_map(ctx, p->sq_off.user_addr, size);
+
+	if (IS_ERR(ptr)) {
+		io_rings_free(ctx);
+		return PTR_ERR(ptr);
+	}
+
+	ctx->sq_sqes = ptr;
+	return 0;
+}
+
+static int io_uring_install_fd(struct file *file)
+{
+	int fd;
+
+	fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+	fd_install(fd, file);
+	return fd;
+}
+
+/*
+ * 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 struct file *io_uring_get_file(struct io_ring_ctx *ctx)
+{
+	struct file *file;
+#if defined(CONFIG_UNIX)
+	int ret;
+
+	ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
+				&ctx->ring_sock);
+	if (ret)
+		return ERR_PTR(ret);
+#endif
+
+	file = anon_inode_getfile_secure("[io_uring]", &io_uring_fops, ctx,
+					 O_RDWR | O_CLOEXEC, NULL);
+#if defined(CONFIG_UNIX)
+	if (IS_ERR(file)) {
+		sock_release(ctx->ring_sock);
+		ctx->ring_sock = NULL;
+	} else {
+		ctx->ring_sock->file = file;
+	}
+#endif
+	return file;
+}
+
+static __cold int io_uring_create(unsigned entries, struct io_uring_params *p,
+				  struct io_uring_params __user *params)
+{
+	struct io_ring_ctx *ctx;
+	struct io_uring_task *tctx;
+	struct file *file;
+	int ret;
+
+	if (!entries)
+		return -EINVAL;
+	if (entries > IORING_MAX_ENTRIES) {
+		if (!(p->flags & IORING_SETUP_CLAMP))
+			return -EINVAL;
+		entries = IORING_MAX_ENTRIES;
+	}
+
+	if ((p->flags & IORING_SETUP_REGISTERED_FD_ONLY)
+	    && !(p->flags & IORING_SETUP_NO_MMAP))
+		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. If the application has
+	 * set IORING_SETUP_CQSIZE, it will have passed in the desired number
+	 * of CQ ring entries manually.
+	 */
+	p->sq_entries = roundup_pow_of_two(entries);
+	if (p->flags & IORING_SETUP_CQSIZE) {
+		/*
+		 * If IORING_SETUP_CQSIZE is set, we do the same roundup
+		 * to a power-of-two, if it isn't already. We do NOT impose
+		 * any cq vs sq ring sizing.
+		 */
+		if (!p->cq_entries)
+			return -EINVAL;
+		if (p->cq_entries > IORING_MAX_CQ_ENTRIES) {
+			if (!(p->flags & IORING_SETUP_CLAMP))
+				return -EINVAL;
+			p->cq_entries = IORING_MAX_CQ_ENTRIES;
+		}
+		p->cq_entries = roundup_pow_of_two(p->cq_entries);
+		if (p->cq_entries < p->sq_entries)
+			return -EINVAL;
+	} else {
+		p->cq_entries = 2 * p->sq_entries;
+	}
+
+	ctx = io_ring_ctx_alloc(p);
+	if (!ctx)
+		return -ENOMEM;
+
+	if ((ctx->flags & IORING_SETUP_DEFER_TASKRUN) &&
+	    !(ctx->flags & IORING_SETUP_IOPOLL) &&
+	    !(ctx->flags & IORING_SETUP_SQPOLL))
+		ctx->task_complete = true;
+
+	if (ctx->task_complete || (ctx->flags & IORING_SETUP_IOPOLL))
+		ctx->lockless_cq = true;
+
+	/*
+	 * lazy poll_wq activation relies on ->task_complete for synchronisation
+	 * purposes, see io_activate_pollwq()
+	 */
+	if (!ctx->task_complete)
+		ctx->poll_activated = true;
+
+	/*
+	 * When SETUP_IOPOLL and SETUP_SQPOLL are both enabled, user
+	 * space applications don't need to do io completion events
+	 * polling again, they can rely on io_sq_thread to do polling
+	 * work, which can reduce cpu usage and uring_lock contention.
+	 */
+	if (ctx->flags & IORING_SETUP_IOPOLL &&
+	    !(ctx->flags & IORING_SETUP_SQPOLL))
+		ctx->syscall_iopoll = 1;
+
+	ctx->compat = in_compat_syscall();
+	if (!ns_capable_noaudit(&init_user_ns, CAP_IPC_LOCK))
+		ctx->user = get_uid(current_user());
+
+	/*
+	 * For SQPOLL, we just need a wakeup, always. For !SQPOLL, if
+	 * COOP_TASKRUN is set, then IPIs are never needed by the app.
+	 */
+	ret = -EINVAL;
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		/* IPI related flags don't make sense with SQPOLL */
+		if (ctx->flags & (IORING_SETUP_COOP_TASKRUN |
+				  IORING_SETUP_TASKRUN_FLAG |
+				  IORING_SETUP_DEFER_TASKRUN))
+			goto err;
+		ctx->notify_method = TWA_SIGNAL_NO_IPI;
+	} else if (ctx->flags & IORING_SETUP_COOP_TASKRUN) {
+		ctx->notify_method = TWA_SIGNAL_NO_IPI;
+	} else {
+		if (ctx->flags & IORING_SETUP_TASKRUN_FLAG &&
+		    !(ctx->flags & IORING_SETUP_DEFER_TASKRUN))
+			goto err;
+		ctx->notify_method = TWA_SIGNAL;
+	}
+
+	/*
+	 * For DEFER_TASKRUN we require the completion task to be the same as the
+	 * submission task. This implies that there is only one submitter, so enforce
+	 * that.
+	 */
+	if (ctx->flags & IORING_SETUP_DEFER_TASKRUN &&
+	    !(ctx->flags & IORING_SETUP_SINGLE_ISSUER)) {
+		goto err;
+	}
+
+	/*
+	 * This is just grabbed for accounting purposes. When a process exits,
+	 * the mm is exited and dropped before the files, hence we need to hang
+	 * on to this mm purely for the purposes of being able to unaccount
+	 * memory (locked/pinned vm). It's not used for anything else.
+	 */
+	mmgrab(current->mm);
+	ctx->mm_account = current->mm;
+
+	ret = io_allocate_scq_urings(ctx, p);
+	if (ret)
+		goto err;
+
+	ret = io_sq_offload_create(ctx, p);
+	if (ret)
+		goto err;
+
+	ret = io_rsrc_init(ctx);
+	if (ret)
+		goto err;
+
+	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);
+	if (!(ctx->flags & IORING_SETUP_NO_SQARRAY))
+		p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
+	p->sq_off.resv1 = 0;
+	if (!(ctx->flags & IORING_SETUP_NO_MMAP))
+		p->sq_off.user_addr = 0;
+
+	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);
+	p->cq_off.flags = offsetof(struct io_rings, cq_flags);
+	p->cq_off.resv1 = 0;
+	if (!(ctx->flags & IORING_SETUP_NO_MMAP))
+		p->cq_off.user_addr = 0;
+
+	p->features = IORING_FEAT_SINGLE_MMAP | IORING_FEAT_NODROP |
+			IORING_FEAT_SUBMIT_STABLE | IORING_FEAT_RW_CUR_POS |
+			IORING_FEAT_CUR_PERSONALITY | IORING_FEAT_FAST_POLL |
+			IORING_FEAT_POLL_32BITS | IORING_FEAT_SQPOLL_NONFIXED |
+			IORING_FEAT_EXT_ARG | IORING_FEAT_NATIVE_WORKERS |
+			IORING_FEAT_RSRC_TAGS | IORING_FEAT_CQE_SKIP |
+			IORING_FEAT_LINKED_FILE | IORING_FEAT_REG_REG_RING;
+
+	if (copy_to_user(params, p, sizeof(*p))) {
+		ret = -EFAULT;
+		goto err;
+	}
+
+	if (ctx->flags & IORING_SETUP_SINGLE_ISSUER
+	    && !(ctx->flags & IORING_SETUP_R_DISABLED))
+		WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
+
+	file = io_uring_get_file(ctx);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto err;
+	}
+
+	ret = __io_uring_add_tctx_node(ctx);
+	if (ret)
+		goto err_fput;
+	tctx = current->io_uring;
+
+	/*
+	 * Install ring fd as the very last thing, so we don't risk someone
+	 * having closed it before we finish setup
+	 */
+	if (p->flags & IORING_SETUP_REGISTERED_FD_ONLY)
+		ret = io_ring_add_registered_file(tctx, file, 0, IO_RINGFD_REG_MAX);
+	else
+		ret = io_uring_install_fd(file);
+	if (ret < 0)
+		goto err_fput;
+
+	trace_io_uring_create(ret, ctx, p->sq_entries, p->cq_entries, p->flags);
+	return ret;
+err:
+	io_ring_ctx_wait_and_kill(ctx);
+	return ret;
+err_fput:
+	fput(file);
+	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;
+	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 | IORING_SETUP_CQSIZE |
+			IORING_SETUP_CLAMP | IORING_SETUP_ATTACH_WQ |
+			IORING_SETUP_R_DISABLED | IORING_SETUP_SUBMIT_ALL |
+			IORING_SETUP_COOP_TASKRUN | IORING_SETUP_TASKRUN_FLAG |
+			IORING_SETUP_SQE128 | IORING_SETUP_CQE32 |
+			IORING_SETUP_SINGLE_ISSUER | IORING_SETUP_DEFER_TASKRUN |
+			IORING_SETUP_NO_MMAP | IORING_SETUP_REGISTERED_FD_ONLY |
+			IORING_SETUP_NO_SQARRAY))
+		return -EINVAL;
+
+	return io_uring_create(entries, &p, params);
+}
+
+static inline bool io_uring_allowed(void)
+{
+	int disabled = READ_ONCE(sysctl_io_uring_disabled);
+	kgid_t io_uring_group;
+
+	if (disabled == 2)
+		return false;
+
+	if (disabled == 0 || capable(CAP_SYS_ADMIN))
+		return true;
+
+	io_uring_group = make_kgid(&init_user_ns, sysctl_io_uring_group);
+	if (!gid_valid(io_uring_group))
+		return false;
+
+	return in_group_p(io_uring_group);
+}
+
+SYSCALL_DEFINE2(io_uring_setup, u32, entries,
+		struct io_uring_params __user *, params)
+{
+	if (!io_uring_allowed())
+		return -EPERM;
+
+	return io_uring_setup(entries, params);
+}
+
+static __cold int io_probe(struct io_ring_ctx *ctx, void __user *arg,
+			   unsigned nr_args)
+{
+	struct io_uring_probe *p;
+	size_t size;
+	int i, ret;
+
+	size = struct_size(p, ops, nr_args);
+	if (size == SIZE_MAX)
+		return -EOVERFLOW;
+	p = kzalloc(size, GFP_KERNEL);
+	if (!p)
+		return -ENOMEM;
+
+	ret = -EFAULT;
+	if (copy_from_user(p, arg, size))
+		goto out;
+	ret = -EINVAL;
+	if (memchr_inv(p, 0, size))
+		goto out;
+
+	p->last_op = IORING_OP_LAST - 1;
+	if (nr_args > IORING_OP_LAST)
+		nr_args = IORING_OP_LAST;
+
+	for (i = 0; i < nr_args; i++) {
+		p->ops[i].op = i;
+		if (!io_issue_defs[i].not_supported)
+			p->ops[i].flags = IO_URING_OP_SUPPORTED;
+	}
+	p->ops_len = i;
+
+	ret = 0;
+	if (copy_to_user(arg, p, size))
+		ret = -EFAULT;
+out:
+	kfree(p);
+	return ret;
+}
+
+static int io_register_personality(struct io_ring_ctx *ctx)
+{
+	const struct cred *creds;
+	u32 id;
+	int ret;
+
+	creds = get_current_cred();
+
+	ret = xa_alloc_cyclic(&ctx->personalities, &id, (void *)creds,
+			XA_LIMIT(0, USHRT_MAX), &ctx->pers_next, GFP_KERNEL);
+	if (ret < 0) {
+		put_cred(creds);
+		return ret;
+	}
+	return id;
+}
+
+static __cold int io_register_restrictions(struct io_ring_ctx *ctx,
+					   void __user *arg, unsigned int nr_args)
+{
+	struct io_uring_restriction *res;
+	size_t size;
+	int i, ret;
+
+	/* Restrictions allowed only if rings started disabled */
+	if (!(ctx->flags & IORING_SETUP_R_DISABLED))
+		return -EBADFD;
+
+	/* We allow only a single restrictions registration */
+	if (ctx->restrictions.registered)
+		return -EBUSY;
+
+	if (!arg || nr_args > IORING_MAX_RESTRICTIONS)
+		return -EINVAL;
+
+	size = array_size(nr_args, sizeof(*res));
+	if (size == SIZE_MAX)
+		return -EOVERFLOW;
+
+	res = memdup_user(arg, size);
+	if (IS_ERR(res))
+		return PTR_ERR(res);
+
+	ret = 0;
+
+	for (i = 0; i < nr_args; i++) {
+		switch (res[i].opcode) {
+		case IORING_RESTRICTION_REGISTER_OP:
+			if (res[i].register_op >= IORING_REGISTER_LAST) {
+				ret = -EINVAL;
+				goto out;
+			}
+
+			__set_bit(res[i].register_op,
+				  ctx->restrictions.register_op);
+			break;
+		case IORING_RESTRICTION_SQE_OP:
+			if (res[i].sqe_op >= IORING_OP_LAST) {
+				ret = -EINVAL;
+				goto out;
+			}
+
+			__set_bit(res[i].sqe_op, ctx->restrictions.sqe_op);
+			break;
+		case IORING_RESTRICTION_SQE_FLAGS_ALLOWED:
+			ctx->restrictions.sqe_flags_allowed = res[i].sqe_flags;
+			break;
+		case IORING_RESTRICTION_SQE_FLAGS_REQUIRED:
+			ctx->restrictions.sqe_flags_required = res[i].sqe_flags;
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+out:
+	/* Reset all restrictions if an error happened */
+	if (ret != 0)
+		memset(&ctx->restrictions, 0, sizeof(ctx->restrictions));
+	else
+		ctx->restrictions.registered = true;
+
+	kfree(res);
+	return ret;
+}
+
+static int io_register_enable_rings(struct io_ring_ctx *ctx)
+{
+	if (!(ctx->flags & IORING_SETUP_R_DISABLED))
+		return -EBADFD;
+
+	if (ctx->flags & IORING_SETUP_SINGLE_ISSUER && !ctx->submitter_task) {
+		WRITE_ONCE(ctx->submitter_task, get_task_struct(current));
+		/*
+		 * Lazy activation attempts would fail if it was polled before
+		 * submitter_task is set.
+		 */
+		if (wq_has_sleeper(&ctx->poll_wq))
+			io_activate_pollwq(ctx);
+	}
+
+	if (ctx->restrictions.registered)
+		ctx->restricted = 1;
+
+	ctx->flags &= ~IORING_SETUP_R_DISABLED;
+	if (ctx->sq_data && wq_has_sleeper(&ctx->sq_data->wait))
+		wake_up(&ctx->sq_data->wait);
+	return 0;
+}
+
+static __cold int __io_register_iowq_aff(struct io_ring_ctx *ctx,
+					 cpumask_var_t new_mask)
+{
+	int ret;
+
+	if (!(ctx->flags & IORING_SETUP_SQPOLL)) {
+		ret = io_wq_cpu_affinity(current->io_uring, new_mask);
+	} else {
+		mutex_unlock(&ctx->uring_lock);
+		ret = io_sqpoll_wq_cpu_affinity(ctx, new_mask);
+		mutex_lock(&ctx->uring_lock);
+	}
+
+	return ret;
+}
+
+static __cold int io_register_iowq_aff(struct io_ring_ctx *ctx,
+				       void __user *arg, unsigned len)
+{
+	cpumask_var_t new_mask;
+	int ret;
+
+	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	cpumask_clear(new_mask);
+	if (len > cpumask_size())
+		len = cpumask_size();
+
+	if (in_compat_syscall()) {
+		ret = compat_get_bitmap(cpumask_bits(new_mask),
+					(const compat_ulong_t __user *)arg,
+					len * 8 /* CHAR_BIT */);
+	} else {
+		ret = copy_from_user(new_mask, arg, len);
+	}
+
+	if (ret) {
+		free_cpumask_var(new_mask);
+		return -EFAULT;
+	}
+
+	ret = __io_register_iowq_aff(ctx, new_mask);
+	free_cpumask_var(new_mask);
+	return ret;
+}
+
+static __cold int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
+{
+	return __io_register_iowq_aff(ctx, NULL);
+}
+
+static __cold int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
+					       void __user *arg)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_tctx_node *node;
+	struct io_uring_task *tctx = NULL;
+	struct io_sq_data *sqd = NULL;
+	__u32 new_count[2];
+	int i, ret;
+
+	if (copy_from_user(new_count, arg, sizeof(new_count)))
+		return -EFAULT;
+	for (i = 0; i < ARRAY_SIZE(new_count); i++)
+		if (new_count[i] > INT_MAX)
+			return -EINVAL;
+
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		sqd = ctx->sq_data;
+		if (sqd) {
+			/*
+			 * Observe the correct sqd->lock -> ctx->uring_lock
+			 * ordering. Fine to drop uring_lock here, we hold
+			 * a ref to the ctx.
+			 */
+			refcount_inc(&sqd->refs);
+			mutex_unlock(&ctx->uring_lock);
+			mutex_lock(&sqd->lock);
+			mutex_lock(&ctx->uring_lock);
+			if (sqd->thread)
+				tctx = sqd->thread->io_uring;
+		}
+	} else {
+		tctx = current->io_uring;
+	}
+
+	BUILD_BUG_ON(sizeof(new_count) != sizeof(ctx->iowq_limits));
+
+	for (i = 0; i < ARRAY_SIZE(new_count); i++)
+		if (new_count[i])
+			ctx->iowq_limits[i] = new_count[i];
+	ctx->iowq_limits_set = true;
+
+	if (tctx && tctx->io_wq) {
+		ret = io_wq_max_workers(tctx->io_wq, new_count);
+		if (ret)
+			goto err;
+	} else {
+		memset(new_count, 0, sizeof(new_count));
+	}
+
+	if (sqd) {
+		mutex_unlock(&sqd->lock);
+		io_put_sq_data(sqd);
+	}
+
+	if (copy_to_user(arg, new_count, sizeof(new_count)))
+		return -EFAULT;
+
+	/* that's it for SQPOLL, only the SQPOLL task creates requests */
+	if (sqd)
+		return 0;
+
+	/* now propagate the restriction to all registered users */
+	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
+		struct io_uring_task *tctx = node->task->io_uring;
+
+		if (WARN_ON_ONCE(!tctx->io_wq))
+			continue;
+
+		for (i = 0; i < ARRAY_SIZE(new_count); i++)
+			new_count[i] = ctx->iowq_limits[i];
+		/* ignore errors, it always returns zero anyway */
+		(void)io_wq_max_workers(tctx->io_wq, new_count);
+	}
+	return 0;
+err:
+	if (sqd) {
+		mutex_unlock(&sqd->lock);
+		io_put_sq_data(sqd);
+	}
+	return ret;
+}
+
+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 don't quiesce the refs for register anymore and so it can't be
+	 * dying as we're holding a file ref here.
+	 */
+	if (WARN_ON_ONCE(percpu_ref_is_dying(&ctx->refs)))
+		return -ENXIO;
+
+	if (ctx->submitter_task && ctx->submitter_task != current)
+		return -EEXIST;
+
+	if (ctx->restricted) {
+		opcode = array_index_nospec(opcode, IORING_REGISTER_LAST);
+		if (!test_bit(opcode, ctx->restrictions.register_op))
+			return -EACCES;
+	}
+
+	switch (opcode) {
+	case IORING_REGISTER_BUFFERS:
+		ret = -EFAULT;
+		if (!arg)
+			break;
+		ret = io_sqe_buffers_register(ctx, arg, nr_args, NULL);
+		break;
+	case IORING_UNREGISTER_BUFFERS:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_sqe_buffers_unregister(ctx);
+		break;
+	case IORING_REGISTER_FILES:
+		ret = -EFAULT;
+		if (!arg)
+			break;
+		ret = io_sqe_files_register(ctx, arg, nr_args, NULL);
+		break;
+	case IORING_UNREGISTER_FILES:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_sqe_files_unregister(ctx);
+		break;
+	case IORING_REGISTER_FILES_UPDATE:
+		ret = io_register_files_update(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_EVENTFD:
+		ret = -EINVAL;
+		if (nr_args != 1)
+			break;
+		ret = io_eventfd_register(ctx, arg, 0);
+		break;
+	case IORING_REGISTER_EVENTFD_ASYNC:
+		ret = -EINVAL;
+		if (nr_args != 1)
+			break;
+		ret = io_eventfd_register(ctx, arg, 1);
+		break;
+	case IORING_UNREGISTER_EVENTFD:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_eventfd_unregister(ctx);
+		break;
+	case IORING_REGISTER_PROBE:
+		ret = -EINVAL;
+		if (!arg || nr_args > 256)
+			break;
+		ret = io_probe(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_PERSONALITY:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_register_personality(ctx);
+		break;
+	case IORING_UNREGISTER_PERSONALITY:
+		ret = -EINVAL;
+		if (arg)
+			break;
+		ret = io_unregister_personality(ctx, nr_args);
+		break;
+	case IORING_REGISTER_ENABLE_RINGS:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_register_enable_rings(ctx);
+		break;
+	case IORING_REGISTER_RESTRICTIONS:
+		ret = io_register_restrictions(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_FILES2:
+		ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_FILE);
+		break;
+	case IORING_REGISTER_FILES_UPDATE2:
+		ret = io_register_rsrc_update(ctx, arg, nr_args,
+					      IORING_RSRC_FILE);
+		break;
+	case IORING_REGISTER_BUFFERS2:
+		ret = io_register_rsrc(ctx, arg, nr_args, IORING_RSRC_BUFFER);
+		break;
+	case IORING_REGISTER_BUFFERS_UPDATE:
+		ret = io_register_rsrc_update(ctx, arg, nr_args,
+					      IORING_RSRC_BUFFER);
+		break;
+	case IORING_REGISTER_IOWQ_AFF:
+		ret = -EINVAL;
+		if (!arg || !nr_args)
+			break;
+		ret = io_register_iowq_aff(ctx, arg, nr_args);
+		break;
+	case IORING_UNREGISTER_IOWQ_AFF:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_unregister_iowq_aff(ctx);
+		break;
+	case IORING_REGISTER_IOWQ_MAX_WORKERS:
+		ret = -EINVAL;
+		if (!arg || nr_args != 2)
+			break;
+		ret = io_register_iowq_max_workers(ctx, arg);
+		break;
+	case IORING_REGISTER_RING_FDS:
+		ret = io_ringfd_register(ctx, arg, nr_args);
+		break;
+	case IORING_UNREGISTER_RING_FDS:
+		ret = io_ringfd_unregister(ctx, arg, nr_args);
+		break;
+	case IORING_REGISTER_PBUF_RING:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_register_pbuf_ring(ctx, arg);
+		break;
+	case IORING_UNREGISTER_PBUF_RING:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_unregister_pbuf_ring(ctx, arg);
+		break;
+	case IORING_REGISTER_SYNC_CANCEL:
+		ret = -EINVAL;
+		if (!arg || nr_args != 1)
+			break;
+		ret = io_sync_cancel(ctx, arg);
+		break;
+	case IORING_REGISTER_FILE_ALLOC_RANGE:
+		ret = -EINVAL;
+		if (!arg || nr_args)
+			break;
+		ret = io_register_file_alloc_range(ctx, arg);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	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 file *file;
+	bool use_registered_ring;
+
+	use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING);
+	opcode &= ~IORING_REGISTER_USE_REGISTERED_RING;
+
+	if (opcode >= IORING_REGISTER_LAST)
+		return -EINVAL;
+
+	if (use_registered_ring) {
+		/*
+		 * Ring fd has been registered via IORING_REGISTER_RING_FDS, we
+		 * need only dereference our task private array to find it.
+		 */
+		struct io_uring_task *tctx = current->io_uring;
+
+		if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX))
+			return -EINVAL;
+		fd = array_index_nospec(fd, IO_RINGFD_REG_MAX);
+		file = tctx->registered_rings[fd];
+		if (unlikely(!file))
+			return -EBADF;
+	} else {
+		file = fget(fd);
+		if (unlikely(!file))
+			return -EBADF;
+		ret = -EOPNOTSUPP;
+		if (!io_is_uring_fops(file))
+			goto out_fput;
+	}
+
+	ctx = file->private_data;
+
+	mutex_lock(&ctx->uring_lock);
+	ret = __io_uring_register(ctx, opcode, arg, nr_args);
+	mutex_unlock(&ctx->uring_lock);
+	trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret);
+out_fput:
+	if (!use_registered_ring)
+		fput(file);
+	return ret;
+}
+
+static int __init io_uring_init(void)
+{
+#define __BUILD_BUG_VERIFY_OFFSET_SIZE(stype, eoffset, esize, ename) do { \
+	BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
+	BUILD_BUG_ON(sizeof_field(stype, ename) != esize); \
+} while (0)
+
+#define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
+	__BUILD_BUG_VERIFY_OFFSET_SIZE(struct io_uring_sqe, eoffset, sizeof(etype), ename)
+#define BUILD_BUG_SQE_ELEM_SIZE(eoffset, esize, ename) \
+	__BUILD_BUG_VERIFY_OFFSET_SIZE(struct io_uring_sqe, eoffset, esize, ename)
+	BUILD_BUG_ON(sizeof(struct io_uring_sqe) != 64);
+	BUILD_BUG_SQE_ELEM(0,  __u8,   opcode);
+	BUILD_BUG_SQE_ELEM(1,  __u8,   flags);
+	BUILD_BUG_SQE_ELEM(2,  __u16,  ioprio);
+	BUILD_BUG_SQE_ELEM(4,  __s32,  fd);
+	BUILD_BUG_SQE_ELEM(8,  __u64,  off);
+	BUILD_BUG_SQE_ELEM(8,  __u64,  addr2);
+	BUILD_BUG_SQE_ELEM(8,  __u32,  cmd_op);
+	BUILD_BUG_SQE_ELEM(12, __u32, __pad1);
+	BUILD_BUG_SQE_ELEM(16, __u64,  addr);
+	BUILD_BUG_SQE_ELEM(16, __u64,  splice_off_in);
+	BUILD_BUG_SQE_ELEM(24, __u32,  len);
+	BUILD_BUG_SQE_ELEM(28,     __kernel_rwf_t, rw_flags);
+	BUILD_BUG_SQE_ELEM(28, /* compat */   int, rw_flags);
+	BUILD_BUG_SQE_ELEM(28, /* compat */ __u32, rw_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  fsync_flags);
+	BUILD_BUG_SQE_ELEM(28, /* compat */ __u16,  poll_events);
+	BUILD_BUG_SQE_ELEM(28, __u32,  poll32_events);
+	BUILD_BUG_SQE_ELEM(28, __u32,  sync_range_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  msg_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  timeout_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  accept_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  cancel_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  open_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  statx_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  fadvise_advice);
+	BUILD_BUG_SQE_ELEM(28, __u32,  splice_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  rename_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  unlink_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  hardlink_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  xattr_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  msg_ring_flags);
+	BUILD_BUG_SQE_ELEM(32, __u64,  user_data);
+	BUILD_BUG_SQE_ELEM(40, __u16,  buf_index);
+	BUILD_BUG_SQE_ELEM(40, __u16,  buf_group);
+	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
+	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
+	BUILD_BUG_SQE_ELEM(44, __u32,  file_index);
+	BUILD_BUG_SQE_ELEM(44, __u16,  addr_len);
+	BUILD_BUG_SQE_ELEM(46, __u16,  __pad3[0]);
+	BUILD_BUG_SQE_ELEM(48, __u64,  addr3);
+	BUILD_BUG_SQE_ELEM_SIZE(48, 0, cmd);
+	BUILD_BUG_SQE_ELEM(56, __u64,  __pad2);
+
+	BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
+		     sizeof(struct io_uring_rsrc_update));
+	BUILD_BUG_ON(sizeof(struct io_uring_rsrc_update) >
+		     sizeof(struct io_uring_rsrc_update2));
+
+	/* ->buf_index is u16 */
+	BUILD_BUG_ON(offsetof(struct io_uring_buf_ring, bufs) != 0);
+	BUILD_BUG_ON(offsetof(struct io_uring_buf, resv) !=
+		     offsetof(struct io_uring_buf_ring, tail));
+
+	/* should fit into one byte */
+	BUILD_BUG_ON(SQE_VALID_FLAGS >= (1 << 8));
+	BUILD_BUG_ON(SQE_COMMON_FLAGS >= (1 << 8));
+	BUILD_BUG_ON((SQE_VALID_FLAGS | SQE_COMMON_FLAGS) != SQE_VALID_FLAGS);
+
+	BUILD_BUG_ON(__REQ_F_LAST_BIT > 8 * sizeof(int));
+
+	BUILD_BUG_ON(sizeof(atomic_t) != sizeof(u32));
+
+	io_uring_optable_init();
+
+	/*
+	 * Allow user copy in the per-command field, which starts after the
+	 * file in io_kiocb and until the opcode field. The openat2 handling
+	 * requires copying in user memory into the io_kiocb object in that
+	 * range, and HARDENED_USERCOPY will complain if we haven't
+	 * correctly annotated this range.
+	 */
+	req_cachep = kmem_cache_create_usercopy("io_kiocb",
+				sizeof(struct io_kiocb), 0,
+				SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+				SLAB_ACCOUNT | SLAB_TYPESAFE_BY_RCU,
+				offsetof(struct io_kiocb, cmd.data),
+				sizeof_field(struct io_kiocb, cmd.data), NULL);
+
+#ifdef CONFIG_SYSCTL
+	register_sysctl_init("kernel", kernel_io_uring_disabled_table);
+#endif
+
+	return 0;
+};
+__initcall(io_uring_init);
-- 
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