Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 12740 insertions, 0 deletions

diff --git a/io_uring/Makefile b/io_uring/Makefile
new file mode 100644
index 000000000..3680425df
--- /dev/null
+++ b/io_uring/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for io_uring
+
+obj-$(CONFIG_IO_URING)		+= io_uring.o
+obj-$(CONFIG_IO_WQ)		+= io-wq.o
diff --git a/io_uring/io-wq.c b/io_uring/io-wq.c
new file mode 100644
index 000000000..fe8594a03
--- /dev/null
+++ b/io_uring/io-wq.c
@@ -0,0 +1,1414 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Basic worker thread pool for io_uring
+ *
+ * Copyright (C) 2019 Jens Axboe
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/sched/signal.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/rculist_nulls.h>
+#include <linux/cpu.h>
+#include <linux/tracehook.h>
+#include <uapi/linux/io_uring.h>
+
+#include "io-wq.h"
+
+#define WORKER_IDLE_TIMEOUT	(5 * HZ)
+
+enum {
+	IO_WORKER_F_UP		= 1,	/* up and active */
+	IO_WORKER_F_RUNNING	= 2,	/* account as running */
+	IO_WORKER_F_FREE	= 4,	/* worker on free list */
+	IO_WORKER_F_BOUND	= 8,	/* is doing bounded work */
+};
+
+enum {
+	IO_WQ_BIT_EXIT		= 0,	/* wq exiting */
+};
+
+enum {
+	IO_ACCT_STALLED_BIT	= 0,	/* stalled on hash */
+};
+
+/*
+ * One for each thread in a wqe pool
+ */
+struct io_worker {
+	refcount_t ref;
+	unsigned flags;
+	struct hlist_nulls_node nulls_node;
+	struct list_head all_list;
+	struct task_struct *task;
+	struct io_wqe *wqe;
+
+	struct io_wq_work *cur_work;
+	spinlock_t lock;
+
+	struct completion ref_done;
+
+	unsigned long create_state;
+	struct callback_head create_work;
+	int create_index;
+
+	union {
+		struct rcu_head rcu;
+		struct work_struct work;
+	};
+};
+
+#if BITS_PER_LONG == 64
+#define IO_WQ_HASH_ORDER	6
+#else
+#define IO_WQ_HASH_ORDER	5
+#endif
+
+#define IO_WQ_NR_HASH_BUCKETS	(1u << IO_WQ_HASH_ORDER)
+
+struct io_wqe_acct {
+	unsigned nr_workers;
+	unsigned max_workers;
+	int index;
+	atomic_t nr_running;
+	struct io_wq_work_list work_list;
+	unsigned long flags;
+};
+
+enum {
+	IO_WQ_ACCT_BOUND,
+	IO_WQ_ACCT_UNBOUND,
+	IO_WQ_ACCT_NR,
+};
+
+/*
+ * Per-node worker thread pool
+ */
+struct io_wqe {
+	raw_spinlock_t lock;
+	struct io_wqe_acct acct[2];
+
+	int node;
+
+	struct hlist_nulls_head free_list;
+	struct list_head all_list;
+
+	struct wait_queue_entry wait;
+
+	struct io_wq *wq;
+	struct io_wq_work *hash_tail[IO_WQ_NR_HASH_BUCKETS];
+
+	cpumask_var_t cpu_mask;
+};
+
+/*
+ * Per io_wq state
+  */
+struct io_wq {
+	unsigned long state;
+
+	free_work_fn *free_work;
+	io_wq_work_fn *do_work;
+
+	struct io_wq_hash *hash;
+
+	atomic_t worker_refs;
+	struct completion worker_done;
+
+	struct hlist_node cpuhp_node;
+
+	struct task_struct *task;
+
+	struct io_wqe *wqes[];
+};
+
+static enum cpuhp_state io_wq_online;
+
+struct io_cb_cancel_data {
+	work_cancel_fn *fn;
+	void *data;
+	int nr_running;
+	int nr_pending;
+	bool cancel_all;
+};
+
+static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index);
+static void io_wqe_dec_running(struct io_worker *worker);
+static bool io_acct_cancel_pending_work(struct io_wqe *wqe,
+					struct io_wqe_acct *acct,
+					struct io_cb_cancel_data *match);
+static void create_worker_cb(struct callback_head *cb);
+static void io_wq_cancel_tw_create(struct io_wq *wq);
+
+static bool io_worker_get(struct io_worker *worker)
+{
+	return refcount_inc_not_zero(&worker->ref);
+}
+
+static void io_worker_release(struct io_worker *worker)
+{
+	if (refcount_dec_and_test(&worker->ref))
+		complete(&worker->ref_done);
+}
+
+static inline struct io_wqe_acct *io_get_acct(struct io_wqe *wqe, bool bound)
+{
+	return &wqe->acct[bound ? IO_WQ_ACCT_BOUND : IO_WQ_ACCT_UNBOUND];
+}
+
+static inline struct io_wqe_acct *io_work_get_acct(struct io_wqe *wqe,
+						   struct io_wq_work *work)
+{
+	return io_get_acct(wqe, !(work->flags & IO_WQ_WORK_UNBOUND));
+}
+
+static inline struct io_wqe_acct *io_wqe_get_acct(struct io_worker *worker)
+{
+	return io_get_acct(worker->wqe, worker->flags & IO_WORKER_F_BOUND);
+}
+
+static void io_worker_ref_put(struct io_wq *wq)
+{
+	if (atomic_dec_and_test(&wq->worker_refs))
+		complete(&wq->worker_done);
+}
+
+bool io_wq_worker_stopped(void)
+{
+	struct io_worker *worker = current->pf_io_worker;
+
+	if (WARN_ON_ONCE(!io_wq_current_is_worker()))
+		return true;
+
+	return test_bit(IO_WQ_BIT_EXIT, &worker->wqe->wq->state);
+}
+
+static void io_worker_cancel_cb(struct io_worker *worker)
+{
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+	struct io_wqe *wqe = worker->wqe;
+	struct io_wq *wq = wqe->wq;
+
+	atomic_dec(&acct->nr_running);
+	raw_spin_lock(&worker->wqe->lock);
+	acct->nr_workers--;
+	raw_spin_unlock(&worker->wqe->lock);
+	io_worker_ref_put(wq);
+	clear_bit_unlock(0, &worker->create_state);
+	io_worker_release(worker);
+}
+
+static bool io_task_worker_match(struct callback_head *cb, void *data)
+{
+	struct io_worker *worker;
+
+	if (cb->func != create_worker_cb)
+		return false;
+	worker = container_of(cb, struct io_worker, create_work);
+	return worker == data;
+}
+
+static void io_worker_exit(struct io_worker *worker)
+{
+	struct io_wqe *wqe = worker->wqe;
+	struct io_wq *wq = wqe->wq;
+
+	while (1) {
+		struct callback_head *cb = task_work_cancel_match(wq->task,
+						io_task_worker_match, worker);
+
+		if (!cb)
+			break;
+		io_worker_cancel_cb(worker);
+	}
+
+	if (refcount_dec_and_test(&worker->ref))
+		complete(&worker->ref_done);
+	wait_for_completion(&worker->ref_done);
+
+	raw_spin_lock(&wqe->lock);
+	if (worker->flags & IO_WORKER_F_FREE)
+		hlist_nulls_del_rcu(&worker->nulls_node);
+	list_del_rcu(&worker->all_list);
+	preempt_disable();
+	io_wqe_dec_running(worker);
+	worker->flags = 0;
+	current->flags &= ~PF_IO_WORKER;
+	preempt_enable();
+	raw_spin_unlock(&wqe->lock);
+
+	kfree_rcu(worker, rcu);
+	io_worker_ref_put(wqe->wq);
+	do_exit(0);
+}
+
+static inline bool io_acct_run_queue(struct io_wqe_acct *acct)
+{
+	if (!wq_list_empty(&acct->work_list) &&
+	    !test_bit(IO_ACCT_STALLED_BIT, &acct->flags))
+		return true;
+	return false;
+}
+
+/*
+ * Check head of free list for an available worker. If one isn't available,
+ * caller must create one.
+ */
+static bool io_wqe_activate_free_worker(struct io_wqe *wqe,
+					struct io_wqe_acct *acct)
+	__must_hold(RCU)
+{
+	struct hlist_nulls_node *n;
+	struct io_worker *worker;
+
+	/*
+	 * Iterate free_list and see if we can find an idle worker to
+	 * activate. If a given worker is on the free_list but in the process
+	 * of exiting, keep trying.
+	 */
+	hlist_nulls_for_each_entry_rcu(worker, n, &wqe->free_list, nulls_node) {
+		if (!io_worker_get(worker))
+			continue;
+		if (io_wqe_get_acct(worker) != acct) {
+			io_worker_release(worker);
+			continue;
+		}
+		if (wake_up_process(worker->task)) {
+			io_worker_release(worker);
+			return true;
+		}
+		io_worker_release(worker);
+	}
+
+	return false;
+}
+
+/*
+ * We need a worker. If we find a free one, we're good. If not, and we're
+ * below the max number of workers, create one.
+ */
+static bool io_wqe_create_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
+{
+	/*
+	 * Most likely an attempt to queue unbounded work on an io_wq that
+	 * wasn't setup with any unbounded workers.
+	 */
+	if (unlikely(!acct->max_workers))
+		pr_warn_once("io-wq is not configured for unbound workers");
+
+	raw_spin_lock(&wqe->lock);
+	if (acct->nr_workers >= acct->max_workers) {
+		raw_spin_unlock(&wqe->lock);
+		return true;
+	}
+	acct->nr_workers++;
+	raw_spin_unlock(&wqe->lock);
+	atomic_inc(&acct->nr_running);
+	atomic_inc(&wqe->wq->worker_refs);
+	return create_io_worker(wqe->wq, wqe, acct->index);
+}
+
+static void io_wqe_inc_running(struct io_worker *worker)
+{
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+
+	atomic_inc(&acct->nr_running);
+}
+
+static void create_worker_cb(struct callback_head *cb)
+{
+	struct io_worker *worker;
+	struct io_wq *wq;
+	struct io_wqe *wqe;
+	struct io_wqe_acct *acct;
+	bool do_create = false;
+
+	worker = container_of(cb, struct io_worker, create_work);
+	wqe = worker->wqe;
+	wq = wqe->wq;
+	acct = &wqe->acct[worker->create_index];
+	raw_spin_lock(&wqe->lock);
+	if (acct->nr_workers < acct->max_workers) {
+		acct->nr_workers++;
+		do_create = true;
+	}
+	raw_spin_unlock(&wqe->lock);
+	if (do_create) {
+		create_io_worker(wq, wqe, worker->create_index);
+	} else {
+		atomic_dec(&acct->nr_running);
+		io_worker_ref_put(wq);
+	}
+	clear_bit_unlock(0, &worker->create_state);
+	io_worker_release(worker);
+}
+
+static bool io_queue_worker_create(struct io_worker *worker,
+				   struct io_wqe_acct *acct,
+				   task_work_func_t func)
+{
+	struct io_wqe *wqe = worker->wqe;
+	struct io_wq *wq = wqe->wq;
+
+	/* raced with exit, just ignore create call */
+	if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
+		goto fail;
+	if (!io_worker_get(worker))
+		goto fail;
+	/*
+	 * create_state manages ownership of create_work/index. We should
+	 * only need one entry per worker, as the worker going to sleep
+	 * will trigger the condition, and waking will clear it once it
+	 * runs the task_work.
+	 */
+	if (test_bit(0, &worker->create_state) ||
+	    test_and_set_bit_lock(0, &worker->create_state))
+		goto fail_release;
+
+	atomic_inc(&wq->worker_refs);
+	init_task_work(&worker->create_work, func);
+	worker->create_index = acct->index;
+	if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL)) {
+		/*
+		 * EXIT may have been set after checking it above, check after
+		 * adding the task_work and remove any creation item if it is
+		 * now set. wq exit does that too, but we can have added this
+		 * work item after we canceled in io_wq_exit_workers().
+		 */
+		if (test_bit(IO_WQ_BIT_EXIT, &wq->state))
+			io_wq_cancel_tw_create(wq);
+		io_worker_ref_put(wq);
+		return true;
+	}
+	io_worker_ref_put(wq);
+	clear_bit_unlock(0, &worker->create_state);
+fail_release:
+	io_worker_release(worker);
+fail:
+	atomic_dec(&acct->nr_running);
+	io_worker_ref_put(wq);
+	return false;
+}
+
+static void io_wqe_dec_running(struct io_worker *worker)
+	__must_hold(wqe->lock)
+{
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+	struct io_wqe *wqe = worker->wqe;
+
+	if (!(worker->flags & IO_WORKER_F_UP))
+		return;
+
+	if (atomic_dec_and_test(&acct->nr_running) && io_acct_run_queue(acct)) {
+		atomic_inc(&acct->nr_running);
+		atomic_inc(&wqe->wq->worker_refs);
+		raw_spin_unlock(&wqe->lock);
+		io_queue_worker_create(worker, acct, create_worker_cb);
+		raw_spin_lock(&wqe->lock);
+	}
+}
+
+/*
+ * Worker will start processing some work. Move it to the busy list, if
+ * it's currently on the freelist
+ */
+static void __io_worker_busy(struct io_wqe *wqe, struct io_worker *worker,
+			     struct io_wq_work *work)
+	__must_hold(wqe->lock)
+{
+	if (worker->flags & IO_WORKER_F_FREE) {
+		worker->flags &= ~IO_WORKER_F_FREE;
+		hlist_nulls_del_init_rcu(&worker->nulls_node);
+	}
+}
+
+/*
+ * No work, worker going to sleep. Move to freelist, and unuse mm if we
+ * have one attached. Dropping the mm may potentially sleep, so we drop
+ * the lock in that case and return success. Since the caller has to
+ * retry the loop in that case (we changed task state), we don't regrab
+ * the lock if we return success.
+ */
+static void __io_worker_idle(struct io_wqe *wqe, struct io_worker *worker)
+	__must_hold(wqe->lock)
+{
+	if (!(worker->flags & IO_WORKER_F_FREE)) {
+		worker->flags |= IO_WORKER_F_FREE;
+		hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
+	}
+}
+
+static inline unsigned int io_get_work_hash(struct io_wq_work *work)
+{
+	return work->flags >> IO_WQ_HASH_SHIFT;
+}
+
+static bool io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
+{
+	struct io_wq *wq = wqe->wq;
+	bool ret = false;
+
+	spin_lock_irq(&wq->hash->wait.lock);
+	if (list_empty(&wqe->wait.entry)) {
+		__add_wait_queue(&wq->hash->wait, &wqe->wait);
+		if (!test_bit(hash, &wq->hash->map)) {
+			__set_current_state(TASK_RUNNING);
+			list_del_init(&wqe->wait.entry);
+			ret = true;
+		}
+	}
+	spin_unlock_irq(&wq->hash->wait.lock);
+	return ret;
+}
+
+static struct io_wq_work *io_get_next_work(struct io_wqe_acct *acct,
+					   struct io_worker *worker)
+	__must_hold(wqe->lock)
+{
+	struct io_wq_work_node *node, *prev;
+	struct io_wq_work *work, *tail;
+	unsigned int stall_hash = -1U;
+	struct io_wqe *wqe = worker->wqe;
+
+	wq_list_for_each(node, prev, &acct->work_list) {
+		unsigned int hash;
+
+		work = container_of(node, struct io_wq_work, list);
+
+		/* not hashed, can run anytime */
+		if (!io_wq_is_hashed(work)) {
+			wq_list_del(&acct->work_list, node, prev);
+			return work;
+		}
+
+		hash = io_get_work_hash(work);
+		/* all items with this hash lie in [work, tail] */
+		tail = wqe->hash_tail[hash];
+
+		/* hashed, can run if not already running */
+		if (!test_and_set_bit(hash, &wqe->wq->hash->map)) {
+			wqe->hash_tail[hash] = NULL;
+			wq_list_cut(&acct->work_list, &tail->list, prev);
+			return work;
+		}
+		if (stall_hash == -1U)
+			stall_hash = hash;
+		/* fast forward to a next hash, for-each will fix up @prev */
+		node = &tail->list;
+	}
+
+	if (stall_hash != -1U) {
+		bool unstalled;
+
+		/*
+		 * Set this before dropping the lock to avoid racing with new
+		 * work being added and clearing the stalled bit.
+		 */
+		set_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+		raw_spin_unlock(&wqe->lock);
+		unstalled = io_wait_on_hash(wqe, stall_hash);
+		raw_spin_lock(&wqe->lock);
+		if (unstalled) {
+			clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+			if (wq_has_sleeper(&wqe->wq->hash->wait))
+				wake_up(&wqe->wq->hash->wait);
+		}
+	}
+
+	return NULL;
+}
+
+static bool io_flush_signals(void)
+{
+	if (test_thread_flag(TIF_NOTIFY_SIGNAL) || current->task_works) {
+		__set_current_state(TASK_RUNNING);
+		tracehook_notify_signal();
+		return true;
+	}
+	return false;
+}
+
+static void io_assign_current_work(struct io_worker *worker,
+				   struct io_wq_work *work)
+{
+	if (work) {
+		io_flush_signals();
+		cond_resched();
+	}
+
+	spin_lock(&worker->lock);
+	worker->cur_work = work;
+	spin_unlock(&worker->lock);
+}
+
+static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
+
+static void io_worker_handle_work(struct io_worker *worker)
+	__releases(wqe->lock)
+{
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+	struct io_wqe *wqe = worker->wqe;
+	struct io_wq *wq = wqe->wq;
+	bool do_kill = test_bit(IO_WQ_BIT_EXIT, &wq->state);
+
+	do {
+		struct io_wq_work *work;
+get_next:
+		/*
+		 * If we got some work, mark us as busy. If we didn't, but
+		 * the list isn't empty, it means we stalled on hashed work.
+		 * Mark us stalled so we don't keep looking for work when we
+		 * can't make progress, any work completion or insertion will
+		 * clear the stalled flag.
+		 */
+		work = io_get_next_work(acct, worker);
+		if (work)
+			__io_worker_busy(wqe, worker, work);
+
+		raw_spin_unlock(&wqe->lock);
+		if (!work)
+			break;
+		io_assign_current_work(worker, work);
+		__set_current_state(TASK_RUNNING);
+
+		/* handle a whole dependent link */
+		do {
+			struct io_wq_work *next_hashed, *linked;
+			unsigned int hash = io_get_work_hash(work);
+
+			next_hashed = wq_next_work(work);
+
+			if (unlikely(do_kill) && (work->flags & IO_WQ_WORK_UNBOUND))
+				work->flags |= IO_WQ_WORK_CANCEL;
+			wq->do_work(work);
+			io_assign_current_work(worker, NULL);
+
+			linked = wq->free_work(work);
+			work = next_hashed;
+			if (!work && linked && !io_wq_is_hashed(linked)) {
+				work = linked;
+				linked = NULL;
+			}
+			io_assign_current_work(worker, work);
+			if (linked)
+				io_wqe_enqueue(wqe, linked);
+
+			if (hash != -1U && !next_hashed) {
+				/* serialize hash clear with wake_up() */
+				spin_lock_irq(&wq->hash->wait.lock);
+				clear_bit(hash, &wq->hash->map);
+				clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+				spin_unlock_irq(&wq->hash->wait.lock);
+				if (wq_has_sleeper(&wq->hash->wait))
+					wake_up(&wq->hash->wait);
+				raw_spin_lock(&wqe->lock);
+				/* skip unnecessary unlock-lock wqe->lock */
+				if (!work)
+					goto get_next;
+				raw_spin_unlock(&wqe->lock);
+			}
+		} while (work);
+
+		raw_spin_lock(&wqe->lock);
+	} while (1);
+}
+
+static int io_wqe_worker(void *data)
+{
+	struct io_worker *worker = data;
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+	struct io_wqe *wqe = worker->wqe;
+	struct io_wq *wq = wqe->wq;
+	bool last_timeout = false;
+	char buf[TASK_COMM_LEN];
+
+	worker->flags |= (IO_WORKER_F_UP | IO_WORKER_F_RUNNING);
+
+	snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
+	set_task_comm(current, buf);
+
+	while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
+		long ret;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+loop:
+		raw_spin_lock(&wqe->lock);
+		if (io_acct_run_queue(acct)) {
+			io_worker_handle_work(worker);
+			goto loop;
+		}
+		/* timed out, exit unless we're the last worker */
+		if (last_timeout && acct->nr_workers > 1) {
+			acct->nr_workers--;
+			raw_spin_unlock(&wqe->lock);
+			__set_current_state(TASK_RUNNING);
+			break;
+		}
+		last_timeout = false;
+		__io_worker_idle(wqe, worker);
+		raw_spin_unlock(&wqe->lock);
+		if (io_flush_signals())
+			continue;
+		ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
+		if (signal_pending(current)) {
+			struct ksignal ksig;
+
+			if (!get_signal(&ksig))
+				continue;
+			break;
+		}
+		last_timeout = !ret;
+	}
+
+	if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
+		raw_spin_lock(&wqe->lock);
+		io_worker_handle_work(worker);
+	}
+
+	io_worker_exit(worker);
+	return 0;
+}
+
+/*
+ * Called when a worker is scheduled in. Mark us as currently running.
+ */
+void io_wq_worker_running(struct task_struct *tsk)
+{
+	struct io_worker *worker = tsk->pf_io_worker;
+
+	if (!worker)
+		return;
+	if (!(worker->flags & IO_WORKER_F_UP))
+		return;
+	if (worker->flags & IO_WORKER_F_RUNNING)
+		return;
+	worker->flags |= IO_WORKER_F_RUNNING;
+	io_wqe_inc_running(worker);
+}
+
+/*
+ * Called when worker is going to sleep. If there are no workers currently
+ * running and we have work pending, wake up a free one or create a new one.
+ */
+void io_wq_worker_sleeping(struct task_struct *tsk)
+{
+	struct io_worker *worker = tsk->pf_io_worker;
+
+	if (!worker)
+		return;
+	if (!(worker->flags & IO_WORKER_F_UP))
+		return;
+	if (!(worker->flags & IO_WORKER_F_RUNNING))
+		return;
+
+	worker->flags &= ~IO_WORKER_F_RUNNING;
+
+	raw_spin_lock(&worker->wqe->lock);
+	io_wqe_dec_running(worker);
+	raw_spin_unlock(&worker->wqe->lock);
+}
+
+static void io_init_new_worker(struct io_wqe *wqe, struct io_worker *worker,
+			       struct task_struct *tsk)
+{
+	tsk->pf_io_worker = worker;
+	worker->task = tsk;
+	set_cpus_allowed_ptr(tsk, wqe->cpu_mask);
+	tsk->flags |= PF_NO_SETAFFINITY;
+
+	raw_spin_lock(&wqe->lock);
+	hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
+	list_add_tail_rcu(&worker->all_list, &wqe->all_list);
+	worker->flags |= IO_WORKER_F_FREE;
+	raw_spin_unlock(&wqe->lock);
+	wake_up_new_task(tsk);
+}
+
+static bool io_wq_work_match_all(struct io_wq_work *work, void *data)
+{
+	return true;
+}
+
+static inline bool io_should_retry_thread(long err)
+{
+	/*
+	 * Prevent perpetual task_work retry, if the task (or its group) is
+	 * exiting.
+	 */
+	if (fatal_signal_pending(current))
+		return false;
+
+	switch (err) {
+	case -EAGAIN:
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static void create_worker_cont(struct callback_head *cb)
+{
+	struct io_worker *worker;
+	struct task_struct *tsk;
+	struct io_wqe *wqe;
+
+	worker = container_of(cb, struct io_worker, create_work);
+	clear_bit_unlock(0, &worker->create_state);
+	wqe = worker->wqe;
+	tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
+	if (!IS_ERR(tsk)) {
+		io_init_new_worker(wqe, worker, tsk);
+		io_worker_release(worker);
+		return;
+	} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
+		struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+
+		atomic_dec(&acct->nr_running);
+		raw_spin_lock(&wqe->lock);
+		acct->nr_workers--;
+		if (!acct->nr_workers) {
+			struct io_cb_cancel_data match = {
+				.fn		= io_wq_work_match_all,
+				.cancel_all	= true,
+			};
+
+			while (io_acct_cancel_pending_work(wqe, acct, &match))
+				raw_spin_lock(&wqe->lock);
+		}
+		raw_spin_unlock(&wqe->lock);
+		io_worker_ref_put(wqe->wq);
+		kfree(worker);
+		return;
+	}
+
+	/* re-create attempts grab a new worker ref, drop the existing one */
+	io_worker_release(worker);
+	schedule_work(&worker->work);
+}
+
+static void io_workqueue_create(struct work_struct *work)
+{
+	struct io_worker *worker = container_of(work, struct io_worker, work);
+	struct io_wqe_acct *acct = io_wqe_get_acct(worker);
+
+	if (!io_queue_worker_create(worker, acct, create_worker_cont))
+		kfree(worker);
+}
+
+static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
+{
+	struct io_wqe_acct *acct = &wqe->acct[index];
+	struct io_worker *worker;
+	struct task_struct *tsk;
+
+	__set_current_state(TASK_RUNNING);
+
+	worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, wqe->node);
+	if (!worker) {
+fail:
+		atomic_dec(&acct->nr_running);
+		raw_spin_lock(&wqe->lock);
+		acct->nr_workers--;
+		raw_spin_unlock(&wqe->lock);
+		io_worker_ref_put(wq);
+		return false;
+	}
+
+	refcount_set(&worker->ref, 1);
+	worker->wqe = wqe;
+	spin_lock_init(&worker->lock);
+	init_completion(&worker->ref_done);
+
+	if (index == IO_WQ_ACCT_BOUND)
+		worker->flags |= IO_WORKER_F_BOUND;
+
+	tsk = create_io_thread(io_wqe_worker, worker, wqe->node);
+	if (!IS_ERR(tsk)) {
+		io_init_new_worker(wqe, worker, tsk);
+	} else if (!io_should_retry_thread(PTR_ERR(tsk))) {
+		kfree(worker);
+		goto fail;
+	} else {
+		INIT_WORK(&worker->work, io_workqueue_create);
+		schedule_work(&worker->work);
+	}
+
+	return true;
+}
+
+/*
+ * Iterate the passed in list and call the specific function for each
+ * worker that isn't exiting
+ */
+static bool io_wq_for_each_worker(struct io_wqe *wqe,
+				  bool (*func)(struct io_worker *, void *),
+				  void *data)
+{
+	struct io_worker *worker;
+	bool ret = false;
+
+	list_for_each_entry_rcu(worker, &wqe->all_list, all_list) {
+		if (io_worker_get(worker)) {
+			/* no task if node is/was offline */
+			if (worker->task)
+				ret = func(worker, data);
+			io_worker_release(worker);
+			if (ret)
+				break;
+		}
+	}
+
+	return ret;
+}
+
+static bool io_wq_worker_wake(struct io_worker *worker, void *data)
+{
+	set_notify_signal(worker->task);
+	wake_up_process(worker->task);
+	return false;
+}
+
+static void io_run_cancel(struct io_wq_work *work, struct io_wqe *wqe)
+{
+	struct io_wq *wq = wqe->wq;
+
+	do {
+		work->flags |= IO_WQ_WORK_CANCEL;
+		wq->do_work(work);
+		work = wq->free_work(work);
+	} while (work);
+}
+
+static void io_wqe_insert_work(struct io_wqe *wqe, struct io_wq_work *work)
+{
+	struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
+	unsigned int hash;
+	struct io_wq_work *tail;
+
+	if (!io_wq_is_hashed(work)) {
+append:
+		wq_list_add_tail(&work->list, &acct->work_list);
+		return;
+	}
+
+	hash = io_get_work_hash(work);
+	tail = wqe->hash_tail[hash];
+	wqe->hash_tail[hash] = work;
+	if (!tail)
+		goto append;
+
+	wq_list_add_after(&work->list, &tail->list, &acct->work_list);
+}
+
+static bool io_wq_work_match_item(struct io_wq_work *work, void *data)
+{
+	return work == data;
+}
+
+static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
+{
+	struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
+	unsigned work_flags = work->flags;
+	bool do_create;
+
+	/*
+	 * If io-wq is exiting for this task, or if the request has explicitly
+	 * been marked as one that should not get executed, cancel it here.
+	 */
+	if (test_bit(IO_WQ_BIT_EXIT, &wqe->wq->state) ||
+	    (work->flags & IO_WQ_WORK_CANCEL)) {
+		io_run_cancel(work, wqe);
+		return;
+	}
+
+	raw_spin_lock(&wqe->lock);
+	io_wqe_insert_work(wqe, work);
+	clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
+
+	rcu_read_lock();
+	do_create = !io_wqe_activate_free_worker(wqe, acct);
+	rcu_read_unlock();
+
+	raw_spin_unlock(&wqe->lock);
+
+	if (do_create && ((work_flags & IO_WQ_WORK_CONCURRENT) ||
+	    !atomic_read(&acct->nr_running))) {
+		bool did_create;
+
+		did_create = io_wqe_create_worker(wqe, acct);
+		if (likely(did_create))
+			return;
+
+		raw_spin_lock(&wqe->lock);
+		/* fatal condition, failed to create the first worker */
+		if (!acct->nr_workers) {
+			struct io_cb_cancel_data match = {
+				.fn		= io_wq_work_match_item,
+				.data		= work,
+				.cancel_all	= false,
+			};
+
+			if (io_acct_cancel_pending_work(wqe, acct, &match))
+				raw_spin_lock(&wqe->lock);
+		}
+		raw_spin_unlock(&wqe->lock);
+	}
+}
+
+void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work)
+{
+	struct io_wqe *wqe = wq->wqes[numa_node_id()];
+
+	io_wqe_enqueue(wqe, work);
+}
+
+/*
+ * Work items that hash to the same value will not be done in parallel.
+ * Used to limit concurrent writes, generally hashed by inode.
+ */
+void io_wq_hash_work(struct io_wq_work *work, void *val)
+{
+	unsigned int bit;
+
+	bit = hash_ptr(val, IO_WQ_HASH_ORDER);
+	work->flags |= (IO_WQ_WORK_HASHED | (bit << IO_WQ_HASH_SHIFT));
+}
+
+static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
+{
+	struct io_cb_cancel_data *match = data;
+
+	/*
+	 * Hold the lock to avoid ->cur_work going out of scope, caller
+	 * may dereference the passed in work.
+	 */
+	spin_lock(&worker->lock);
+	if (worker->cur_work &&
+	    match->fn(worker->cur_work, match->data)) {
+		set_notify_signal(worker->task);
+		match->nr_running++;
+	}
+	spin_unlock(&worker->lock);
+
+	return match->nr_running && !match->cancel_all;
+}
+
+static inline void io_wqe_remove_pending(struct io_wqe *wqe,
+					 struct io_wq_work *work,
+					 struct io_wq_work_node *prev)
+{
+	struct io_wqe_acct *acct = io_work_get_acct(wqe, work);
+	unsigned int hash = io_get_work_hash(work);
+	struct io_wq_work *prev_work = NULL;
+
+	if (io_wq_is_hashed(work) && work == wqe->hash_tail[hash]) {
+		if (prev)
+			prev_work = container_of(prev, struct io_wq_work, list);
+		if (prev_work && io_get_work_hash(prev_work) == hash)
+			wqe->hash_tail[hash] = prev_work;
+		else
+			wqe->hash_tail[hash] = NULL;
+	}
+	wq_list_del(&acct->work_list, &work->list, prev);
+}
+
+static bool io_acct_cancel_pending_work(struct io_wqe *wqe,
+					struct io_wqe_acct *acct,
+					struct io_cb_cancel_data *match)
+	__releases(wqe->lock)
+{
+	struct io_wq_work_node *node, *prev;
+	struct io_wq_work *work;
+
+	wq_list_for_each(node, prev, &acct->work_list) {
+		work = container_of(node, struct io_wq_work, list);
+		if (!match->fn(work, match->data))
+			continue;
+		io_wqe_remove_pending(wqe, work, prev);
+		raw_spin_unlock(&wqe->lock);
+		io_run_cancel(work, wqe);
+		match->nr_pending++;
+		/* not safe to continue after unlock */
+		return true;
+	}
+
+	return false;
+}
+
+static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
+				       struct io_cb_cancel_data *match)
+{
+	int i;
+retry:
+	raw_spin_lock(&wqe->lock);
+	for (i = 0; i < IO_WQ_ACCT_NR; i++) {
+		struct io_wqe_acct *acct = io_get_acct(wqe, i == 0);
+
+		if (io_acct_cancel_pending_work(wqe, acct, match)) {
+			if (match->cancel_all)
+				goto retry;
+			return;
+		}
+	}
+	raw_spin_unlock(&wqe->lock);
+}
+
+static void io_wqe_cancel_running_work(struct io_wqe *wqe,
+				       struct io_cb_cancel_data *match)
+{
+	rcu_read_lock();
+	io_wq_for_each_worker(wqe, io_wq_worker_cancel, match);
+	rcu_read_unlock();
+}
+
+enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
+				  void *data, bool cancel_all)
+{
+	struct io_cb_cancel_data match = {
+		.fn		= cancel,
+		.data		= data,
+		.cancel_all	= cancel_all,
+	};
+	int node;
+
+	/*
+	 * First check pending list, if we're lucky we can just remove it
+	 * from there. CANCEL_OK means that the work is returned as-new,
+	 * no completion will be posted for it.
+	 */
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+
+		io_wqe_cancel_pending_work(wqe, &match);
+		if (match.nr_pending && !match.cancel_all)
+			return IO_WQ_CANCEL_OK;
+	}
+
+	/*
+	 * Now check if a free (going busy) or busy worker has the work
+	 * currently running. If we find it there, we'll return CANCEL_RUNNING
+	 * as an indication that we attempt to signal cancellation. The
+	 * completion will run normally in this case.
+	 */
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+
+		io_wqe_cancel_running_work(wqe, &match);
+		if (match.nr_running && !match.cancel_all)
+			return IO_WQ_CANCEL_RUNNING;
+	}
+
+	if (match.nr_running)
+		return IO_WQ_CANCEL_RUNNING;
+	if (match.nr_pending)
+		return IO_WQ_CANCEL_OK;
+	return IO_WQ_CANCEL_NOTFOUND;
+}
+
+static int io_wqe_hash_wake(struct wait_queue_entry *wait, unsigned mode,
+			    int sync, void *key)
+{
+	struct io_wqe *wqe = container_of(wait, struct io_wqe, wait);
+	int i;
+
+	list_del_init(&wait->entry);
+
+	rcu_read_lock();
+	for (i = 0; i < IO_WQ_ACCT_NR; i++) {
+		struct io_wqe_acct *acct = &wqe->acct[i];
+
+		if (test_and_clear_bit(IO_ACCT_STALLED_BIT, &acct->flags))
+			io_wqe_activate_free_worker(wqe, acct);
+	}
+	rcu_read_unlock();
+	return 1;
+}
+
+struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
+{
+	int ret, node, i;
+	struct io_wq *wq;
+
+	if (WARN_ON_ONCE(!data->free_work || !data->do_work))
+		return ERR_PTR(-EINVAL);
+	if (WARN_ON_ONCE(!bounded))
+		return ERR_PTR(-EINVAL);
+
+	wq = kzalloc(struct_size(wq, wqes, nr_node_ids), GFP_KERNEL);
+	if (!wq)
+		return ERR_PTR(-ENOMEM);
+	ret = cpuhp_state_add_instance_nocalls(io_wq_online, &wq->cpuhp_node);
+	if (ret)
+		goto err_wq;
+
+	refcount_inc(&data->hash->refs);
+	wq->hash = data->hash;
+	wq->free_work = data->free_work;
+	wq->do_work = data->do_work;
+
+	ret = -ENOMEM;
+	for_each_node(node) {
+		struct io_wqe *wqe;
+		int alloc_node = node;
+
+		if (!node_online(alloc_node))
+			alloc_node = NUMA_NO_NODE;
+		wqe = kzalloc_node(sizeof(struct io_wqe), GFP_KERNEL, alloc_node);
+		if (!wqe)
+			goto err;
+		wq->wqes[node] = wqe;
+		if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL))
+			goto err;
+		cpumask_copy(wqe->cpu_mask, cpumask_of_node(node));
+		wqe->node = alloc_node;
+		wqe->acct[IO_WQ_ACCT_BOUND].max_workers = bounded;
+		wqe->acct[IO_WQ_ACCT_UNBOUND].max_workers =
+					task_rlimit(current, RLIMIT_NPROC);
+		INIT_LIST_HEAD(&wqe->wait.entry);
+		wqe->wait.func = io_wqe_hash_wake;
+		for (i = 0; i < IO_WQ_ACCT_NR; i++) {
+			struct io_wqe_acct *acct = &wqe->acct[i];
+
+			acct->index = i;
+			atomic_set(&acct->nr_running, 0);
+			INIT_WQ_LIST(&acct->work_list);
+		}
+		wqe->wq = wq;
+		raw_spin_lock_init(&wqe->lock);
+		INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
+		INIT_LIST_HEAD(&wqe->all_list);
+	}
+
+	wq->task = get_task_struct(data->task);
+	atomic_set(&wq->worker_refs, 1);
+	init_completion(&wq->worker_done);
+	return wq;
+err:
+	io_wq_put_hash(data->hash);
+	cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
+	for_each_node(node) {
+		if (!wq->wqes[node])
+			continue;
+		free_cpumask_var(wq->wqes[node]->cpu_mask);
+		kfree(wq->wqes[node]);
+	}
+err_wq:
+	kfree(wq);
+	return ERR_PTR(ret);
+}
+
+static bool io_task_work_match(struct callback_head *cb, void *data)
+{
+	struct io_worker *worker;
+
+	if (cb->func != create_worker_cb && cb->func != create_worker_cont)
+		return false;
+	worker = container_of(cb, struct io_worker, create_work);
+	return worker->wqe->wq == data;
+}
+
+void io_wq_exit_start(struct io_wq *wq)
+{
+	set_bit(IO_WQ_BIT_EXIT, &wq->state);
+}
+
+static void io_wq_cancel_tw_create(struct io_wq *wq)
+{
+	struct callback_head *cb;
+
+	while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
+		struct io_worker *worker;
+
+		worker = container_of(cb, struct io_worker, create_work);
+		io_worker_cancel_cb(worker);
+		/*
+		 * Only the worker continuation helper has worker allocated and
+		 * hence needs freeing.
+		 */
+		if (cb->func == create_worker_cont)
+			kfree(worker);
+	}
+}
+
+static void io_wq_exit_workers(struct io_wq *wq)
+{
+	int node;
+
+	if (!wq->task)
+		return;
+
+	io_wq_cancel_tw_create(wq);
+
+	rcu_read_lock();
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+
+		io_wq_for_each_worker(wqe, io_wq_worker_wake, NULL);
+	}
+	rcu_read_unlock();
+	io_worker_ref_put(wq);
+	wait_for_completion(&wq->worker_done);
+
+	for_each_node(node) {
+		spin_lock_irq(&wq->hash->wait.lock);
+		list_del_init(&wq->wqes[node]->wait.entry);
+		spin_unlock_irq(&wq->hash->wait.lock);
+	}
+	put_task_struct(wq->task);
+	wq->task = NULL;
+}
+
+static void io_wq_destroy(struct io_wq *wq)
+{
+	int node;
+
+	cpuhp_state_remove_instance_nocalls(io_wq_online, &wq->cpuhp_node);
+
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+		struct io_cb_cancel_data match = {
+			.fn		= io_wq_work_match_all,
+			.cancel_all	= true,
+		};
+		io_wqe_cancel_pending_work(wqe, &match);
+		free_cpumask_var(wqe->cpu_mask);
+		kfree(wqe);
+	}
+	io_wq_put_hash(wq->hash);
+	kfree(wq);
+}
+
+void io_wq_put_and_exit(struct io_wq *wq)
+{
+	WARN_ON_ONCE(!test_bit(IO_WQ_BIT_EXIT, &wq->state));
+
+	io_wq_exit_workers(wq);
+	io_wq_destroy(wq);
+}
+
+struct online_data {
+	unsigned int cpu;
+	bool online;
+};
+
+static bool io_wq_worker_affinity(struct io_worker *worker, void *data)
+{
+	struct online_data *od = data;
+
+	if (od->online)
+		cpumask_set_cpu(od->cpu, worker->wqe->cpu_mask);
+	else
+		cpumask_clear_cpu(od->cpu, worker->wqe->cpu_mask);
+	return false;
+}
+
+static int __io_wq_cpu_online(struct io_wq *wq, unsigned int cpu, bool online)
+{
+	struct online_data od = {
+		.cpu = cpu,
+		.online = online
+	};
+	int i;
+
+	rcu_read_lock();
+	for_each_node(i)
+		io_wq_for_each_worker(wq->wqes[i], io_wq_worker_affinity, &od);
+	rcu_read_unlock();
+	return 0;
+}
+
+static int io_wq_cpu_online(unsigned int cpu, struct hlist_node *node)
+{
+	struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
+
+	return __io_wq_cpu_online(wq, cpu, true);
+}
+
+static int io_wq_cpu_offline(unsigned int cpu, struct hlist_node *node)
+{
+	struct io_wq *wq = hlist_entry_safe(node, struct io_wq, cpuhp_node);
+
+	return __io_wq_cpu_online(wq, cpu, false);
+}
+
+int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask)
+{
+	int i;
+
+	rcu_read_lock();
+	for_each_node(i) {
+		struct io_wqe *wqe = wq->wqes[i];
+
+		if (mask)
+			cpumask_copy(wqe->cpu_mask, mask);
+		else
+			cpumask_copy(wqe->cpu_mask, cpumask_of_node(i));
+	}
+	rcu_read_unlock();
+	return 0;
+}
+
+/*
+ * Set max number of unbounded workers, returns old value. If new_count is 0,
+ * then just return the old value.
+ */
+int io_wq_max_workers(struct io_wq *wq, int *new_count)
+{
+	int prev[IO_WQ_ACCT_NR];
+	bool first_node = true;
+	int i, node;
+
+	BUILD_BUG_ON((int) IO_WQ_ACCT_BOUND   != (int) IO_WQ_BOUND);
+	BUILD_BUG_ON((int) IO_WQ_ACCT_UNBOUND != (int) IO_WQ_UNBOUND);
+	BUILD_BUG_ON((int) IO_WQ_ACCT_NR      != 2);
+
+	for (i = 0; i < 2; i++) {
+		if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
+			new_count[i] = task_rlimit(current, RLIMIT_NPROC);
+	}
+
+	for (i = 0; i < IO_WQ_ACCT_NR; i++)
+		prev[i] = 0;
+
+	rcu_read_lock();
+	for_each_node(node) {
+		struct io_wqe *wqe = wq->wqes[node];
+		struct io_wqe_acct *acct;
+
+		raw_spin_lock(&wqe->lock);
+		for (i = 0; i < IO_WQ_ACCT_NR; i++) {
+			acct = &wqe->acct[i];
+			if (first_node)
+				prev[i] = max_t(int, acct->max_workers, prev[i]);
+			if (new_count[i])
+				acct->max_workers = new_count[i];
+		}
+		raw_spin_unlock(&wqe->lock);
+		first_node = false;
+	}
+	rcu_read_unlock();
+
+	for (i = 0; i < IO_WQ_ACCT_NR; i++)
+		new_count[i] = prev[i];
+
+	return 0;
+}
+
+static __init int io_wq_init(void)
+{
+	int ret;
+
+	ret = cpuhp_setup_state_multi(CPUHP_AP_ONLINE_DYN, "io-wq/online",
+					io_wq_cpu_online, io_wq_cpu_offline);
+	if (ret < 0)
+		return ret;
+	io_wq_online = ret;
+	return 0;
+}
+subsys_initcall(io_wq_init);
diff --git a/io_uring/io-wq.h b/io_uring/io-wq.h
new file mode 100644
index 000000000..48721cbd5
--- /dev/null
+++ b/io_uring/io-wq.h
@@ -0,0 +1,161 @@
+#ifndef INTERNAL_IO_WQ_H
+#define INTERNAL_IO_WQ_H
+
+#include <linux/refcount.h>
+
+struct io_wq;
+
+enum {
+	IO_WQ_WORK_CANCEL	= 1,
+	IO_WQ_WORK_HASHED	= 2,
+	IO_WQ_WORK_UNBOUND	= 4,
+	IO_WQ_WORK_CONCURRENT	= 16,
+
+	IO_WQ_HASH_SHIFT	= 24,	/* upper 8 bits are used for hash key */
+};
+
+enum io_wq_cancel {
+	IO_WQ_CANCEL_OK,	/* cancelled before started */
+	IO_WQ_CANCEL_RUNNING,	/* found, running, and attempted cancelled */
+	IO_WQ_CANCEL_NOTFOUND,	/* work not found */
+};
+
+struct io_wq_work_node {
+	struct io_wq_work_node *next;
+};
+
+struct io_wq_work_list {
+	struct io_wq_work_node *first;
+	struct io_wq_work_node *last;
+};
+
+static inline void wq_list_add_after(struct io_wq_work_node *node,
+				     struct io_wq_work_node *pos,
+				     struct io_wq_work_list *list)
+{
+	struct io_wq_work_node *next = pos->next;
+
+	pos->next = node;
+	node->next = next;
+	if (!next)
+		list->last = node;
+}
+
+static inline void wq_list_add_tail(struct io_wq_work_node *node,
+				    struct io_wq_work_list *list)
+{
+	node->next = NULL;
+	if (!list->first) {
+		list->last = node;
+		WRITE_ONCE(list->first, node);
+	} else {
+		list->last->next = node;
+		list->last = node;
+	}
+}
+
+static inline void wq_list_cut(struct io_wq_work_list *list,
+			       struct io_wq_work_node *last,
+			       struct io_wq_work_node *prev)
+{
+	/* first in the list, if prev==NULL */
+	if (!prev)
+		WRITE_ONCE(list->first, last->next);
+	else
+		prev->next = last->next;
+
+	if (last == list->last)
+		list->last = prev;
+	last->next = NULL;
+}
+
+static inline void wq_list_del(struct io_wq_work_list *list,
+			       struct io_wq_work_node *node,
+			       struct io_wq_work_node *prev)
+{
+	wq_list_cut(list, node, prev);
+}
+
+#define wq_list_for_each(pos, prv, head)			\
+	for (pos = (head)->first, prv = NULL; pos; prv = pos, pos = (pos)->next)
+
+#define wq_list_empty(list)	(READ_ONCE((list)->first) == NULL)
+#define INIT_WQ_LIST(list)	do {				\
+	(list)->first = NULL;					\
+	(list)->last = NULL;					\
+} while (0)
+
+struct io_wq_work {
+	struct io_wq_work_node list;
+	unsigned flags;
+};
+
+static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)
+{
+	if (!work->list.next)
+		return NULL;
+
+	return container_of(work->list.next, struct io_wq_work, list);
+}
+
+typedef struct io_wq_work *(free_work_fn)(struct io_wq_work *);
+typedef void (io_wq_work_fn)(struct io_wq_work *);
+
+struct io_wq_hash {
+	refcount_t refs;
+	unsigned long map;
+	struct wait_queue_head wait;
+};
+
+static inline void io_wq_put_hash(struct io_wq_hash *hash)
+{
+	if (refcount_dec_and_test(&hash->refs))
+		kfree(hash);
+}
+
+struct io_wq_data {
+	struct io_wq_hash *hash;
+	struct task_struct *task;
+	io_wq_work_fn *do_work;
+	free_work_fn *free_work;
+};
+
+struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data);
+void io_wq_exit_start(struct io_wq *wq);
+void io_wq_put_and_exit(struct io_wq *wq);
+
+void io_wq_enqueue(struct io_wq *wq, struct io_wq_work *work);
+void io_wq_hash_work(struct io_wq_work *work, void *val);
+
+int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask);
+int io_wq_max_workers(struct io_wq *wq, int *new_count);
+bool io_wq_worker_stopped(void);
+
+static inline bool io_wq_is_hashed(struct io_wq_work *work)
+{
+	return work->flags & IO_WQ_WORK_HASHED;
+}
+
+typedef bool (work_cancel_fn)(struct io_wq_work *, void *);
+
+enum io_wq_cancel io_wq_cancel_cb(struct io_wq *wq, work_cancel_fn *cancel,
+					void *data, bool cancel_all);
+
+#if defined(CONFIG_IO_WQ)
+extern void io_wq_worker_sleeping(struct task_struct *);
+extern void io_wq_worker_running(struct task_struct *);
+#else
+static inline void io_wq_worker_sleeping(struct task_struct *tsk)
+{
+}
+static inline void io_wq_worker_running(struct task_struct *tsk)
+{
+}
+#endif
+
+static inline bool io_wq_current_is_worker(void)
+{
+	return in_task() && (current->flags & PF_IO_WORKER) &&
+		current->pf_io_worker;
+}
+#endif
diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
new file mode 100644
index 000000000..936abc6ee
--- /dev/null
+++ b/io_uring/io_uring.c
@@ -0,0 +1,11159 @@
+// 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 <linux/compat.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/blkdev.h>
+#include <linux/bvec.h>
+#include <linux/net.h>
+#include <net/sock.h>
+#include <net/af_unix.h>
+#include <net/scm.h>
+#include <linux/anon_inodes.h>
+#include <linux/sched/mm.h>
+#include <linux/uaccess.h>
+#include <linux/nospec.h>
+#include <linux/sizes.h>
+#include <linux/hugetlb.h>
+#include <linux/highmem.h>
+#include <linux/namei.h>
+#include <linux/fsnotify.h>
+#include <linux/fadvise.h>
+#include <linux/eventpoll.h>
+#include <linux/splice.h>
+#include <linux/task_work.h>
+#include <linux/pagemap.h>
+#include <linux/io_uring.h>
+#include <linux/tracehook.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "../fs/internal.h"
+#include "io-wq.h"
+
+#define IORING_MAX_ENTRIES	32768
+#define IORING_MAX_CQ_ENTRIES	(2 * IORING_MAX_ENTRIES)
+#define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
+
+/* only define max */
+#define IORING_MAX_FIXED_FILES	(1U << 15)
+#define IORING_MAX_RESTRICTIONS	(IORING_RESTRICTION_LAST + \
+				 IORING_REGISTER_LAST + IORING_OP_LAST)
+
+#define IO_RSRC_TAG_TABLE_SHIFT	(PAGE_SHIFT - 3)
+#define IO_RSRC_TAG_TABLE_MAX	(1U << IO_RSRC_TAG_TABLE_SHIFT)
+#define IO_RSRC_TAG_TABLE_MASK	(IO_RSRC_TAG_TABLE_MAX - 1)
+
+#define IORING_MAX_REG_BUFFERS	(1U << 14)
+
+#define SQE_VALID_FLAGS	(IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK|	\
+				IOSQE_IO_HARDLINK | IOSQE_ASYNC | \
+				IOSQE_BUFFER_SELECT)
+#define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \
+				REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS)
+
+#define IO_TCTX_REFS_CACHE_NR	(1U << 10)
+
+struct io_uring {
+	u32 head ____cacheline_aligned_in_smp;
+	u32 tail ____cacheline_aligned_in_smp;
+};
+
+/*
+ * This data is shared with the application through the mmap at offsets
+ * IORING_OFF_SQ_RING and IORING_OFF_CQ_RING.
+ *
+ * The offsets to the member fields are published through struct
+ * io_sqring_offsets when calling io_uring_setup.
+ */
+struct io_rings {
+	/*
+	 * Head and tail offsets into the ring; the offsets need to be
+	 * masked to get valid indices.
+	 *
+	 * The kernel controls head of the sq ring and the tail of the cq ring,
+	 * and the application controls tail of the sq ring and the head of the
+	 * cq ring.
+	 */
+	struct io_uring		sq, cq;
+	/*
+	 * Bitmasks to apply to head and tail offsets (constant, equals
+	 * ring_entries - 1)
+	 */
+	u32			sq_ring_mask, cq_ring_mask;
+	/* Ring sizes (constant, power of 2) */
+	u32			sq_ring_entries, cq_ring_entries;
+	/*
+	 * Number of invalid entries dropped by the kernel due to
+	 * invalid index stored in array
+	 *
+	 * Written by the kernel, shouldn't be modified by the
+	 * application (i.e. get number of "new events" by comparing to
+	 * cached value).
+	 *
+	 * After a new SQ head value was read by the application this
+	 * counter includes all submissions that were dropped reaching
+	 * the new SQ head (and possibly more).
+	 */
+	u32			sq_dropped;
+	/*
+	 * Runtime SQ flags
+	 *
+	 * Written by the kernel, shouldn't be modified by the
+	 * application.
+	 *
+	 * The application needs a full memory barrier before checking
+	 * for IORING_SQ_NEED_WAKEUP after updating the sq tail.
+	 */
+	u32			sq_flags;
+	/*
+	 * Runtime CQ flags
+	 *
+	 * Written by the application, shouldn't be modified by the
+	 * kernel.
+	 */
+	u32			cq_flags;
+	/*
+	 * Number of completion events lost because the queue was full;
+	 * this should be avoided by the application by making sure
+	 * there are not more requests pending than there is space in
+	 * the completion queue.
+	 *
+	 * Written by the kernel, shouldn't be modified by the
+	 * application (i.e. get number of "new events" by comparing to
+	 * cached value).
+	 *
+	 * As completion events come in out of order this counter is not
+	 * ordered with any other data.
+	 */
+	u32			cq_overflow;
+	/*
+	 * Ring buffer of completion events.
+	 *
+	 * The kernel writes completion events fresh every time they are
+	 * produced, so the application is allowed to modify pending
+	 * entries.
+	 */
+	struct io_uring_cqe	cqes[] ____cacheline_aligned_in_smp;
+};
+
+enum io_uring_cmd_flags {
+	IO_URING_F_NONBLOCK		= 1,
+	IO_URING_F_COMPLETE_DEFER	= 2,
+};
+
+struct io_mapped_ubuf {
+	u64		ubuf;
+	u64		ubuf_end;
+	unsigned int	nr_bvecs;
+	unsigned long	acct_pages;
+	struct bio_vec	bvec[];
+};
+
+struct io_ring_ctx;
+
+struct io_overflow_cqe {
+	struct io_uring_cqe cqe;
+	struct list_head list;
+};
+
+struct io_fixed_file {
+	/* file * with additional FFS_* flags */
+	unsigned long file_ptr;
+};
+
+struct io_rsrc_put {
+	struct list_head list;
+	u64 tag;
+	union {
+		void *rsrc;
+		struct file *file;
+		struct io_mapped_ubuf *buf;
+	};
+};
+
+struct io_file_table {
+	struct io_fixed_file *files;
+};
+
+struct io_rsrc_node {
+	struct percpu_ref		refs;
+	struct list_head		node;
+	struct list_head		rsrc_list;
+	struct io_rsrc_data		*rsrc_data;
+	struct llist_node		llist;
+	bool				done;
+};
+
+typedef void (rsrc_put_fn)(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc);
+
+struct io_rsrc_data {
+	struct io_ring_ctx		*ctx;
+
+	u64				**tags;
+	unsigned int			nr;
+	rsrc_put_fn			*do_put;
+	atomic_t			refs;
+	struct completion		done;
+	bool				quiesce;
+};
+
+struct io_buffer {
+	struct list_head list;
+	__u64 addr;
+	__u32 len;
+	__u16 bid;
+};
+
+struct io_restriction {
+	DECLARE_BITMAP(register_op, IORING_REGISTER_LAST);
+	DECLARE_BITMAP(sqe_op, IORING_OP_LAST);
+	u8 sqe_flags_allowed;
+	u8 sqe_flags_required;
+	bool registered;
+};
+
+enum {
+	IO_SQ_THREAD_SHOULD_STOP = 0,
+	IO_SQ_THREAD_SHOULD_PARK,
+};
+
+struct io_sq_data {
+	refcount_t		refs;
+	atomic_t		park_pending;
+	struct mutex		lock;
+
+	/* ctx's that are using this sqd */
+	struct list_head	ctx_list;
+
+	struct task_struct	*thread;
+	struct wait_queue_head	wait;
+
+	unsigned		sq_thread_idle;
+	int			sq_cpu;
+	pid_t			task_pid;
+	pid_t			task_tgid;
+
+	unsigned long		state;
+	struct completion	exited;
+};
+
+#define IO_COMPL_BATCH			32
+#define IO_REQ_CACHE_SIZE		32
+#define IO_REQ_ALLOC_BATCH		8
+
+struct io_submit_link {
+	struct io_kiocb		*head;
+	struct io_kiocb		*last;
+};
+
+struct io_submit_state {
+	struct blk_plug		plug;
+	struct io_submit_link	link;
+
+	/*
+	 * io_kiocb alloc cache
+	 */
+	void			*reqs[IO_REQ_CACHE_SIZE];
+	unsigned int		free_reqs;
+
+	bool			plug_started;
+
+	/*
+	 * Batch completion logic
+	 */
+	struct io_kiocb		*compl_reqs[IO_COMPL_BATCH];
+	unsigned int		compl_nr;
+	/* inline/task_work completion list, under ->uring_lock */
+	struct list_head	free_list;
+
+	unsigned int		ios_left;
+};
+
+struct io_ring_ctx {
+	/* const or read-mostly hot data */
+	struct {
+		struct percpu_ref	refs;
+
+		struct io_rings		*rings;
+		unsigned int		flags;
+		unsigned int		compat: 1;
+		unsigned int		drain_next: 1;
+		unsigned int		eventfd_async: 1;
+		unsigned int		restricted: 1;
+		unsigned int		off_timeout_used: 1;
+		unsigned int		drain_active: 1;
+	} ____cacheline_aligned_in_smp;
+
+	/* submission data */
+	struct {
+		struct mutex		uring_lock;
+
+		/*
+		 * Ring buffer of indices into array of io_uring_sqe, which is
+		 * mmapped by the application using the IORING_OFF_SQES offset.
+		 *
+		 * This indirection could e.g. be used to assign fixed
+		 * io_uring_sqe entries to operations and only submit them to
+		 * the queue when needed.
+		 *
+		 * The kernel modifies neither the indices array nor the entries
+		 * array.
+		 */
+		u32			*sq_array;
+		struct io_uring_sqe	*sq_sqes;
+		unsigned		cached_sq_head;
+		unsigned		sq_entries;
+		struct list_head	defer_list;
+
+		/*
+		 * Fixed resources fast path, should be accessed only under
+		 * uring_lock, and updated through io_uring_register(2)
+		 */
+		struct io_rsrc_node	*rsrc_node;
+		struct io_file_table	file_table;
+		unsigned		nr_user_files;
+		unsigned		nr_user_bufs;
+		struct io_mapped_ubuf	**user_bufs;
+
+		struct io_submit_state	submit_state;
+		struct list_head	timeout_list;
+		struct list_head	ltimeout_list;
+		struct list_head	cq_overflow_list;
+		struct xarray		io_buffers;
+		struct xarray		personalities;
+		u32			pers_next;
+		unsigned		sq_thread_idle;
+	} ____cacheline_aligned_in_smp;
+
+	/* IRQ completion list, under ->completion_lock */
+	struct list_head	locked_free_list;
+	unsigned int		locked_free_nr;
+
+	const struct cred	*sq_creds;	/* cred used for __io_sq_thread() */
+	struct io_sq_data	*sq_data;	/* if using sq thread polling */
+
+	struct wait_queue_head	sqo_sq_wait;
+	struct list_head	sqd_list;
+
+	unsigned long		check_cq_overflow;
+
+	struct {
+		unsigned		cached_cq_tail;
+		unsigned		cq_entries;
+		struct eventfd_ctx	*cq_ev_fd;
+		struct wait_queue_head	poll_wait;
+		struct wait_queue_head	cq_wait;
+		unsigned		cq_extra;
+		atomic_t		cq_timeouts;
+		unsigned		cq_last_tm_flush;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		spinlock_t		completion_lock;
+
+		spinlock_t		timeout_lock;
+
+		/*
+		 * ->iopoll_list is protected by the ctx->uring_lock for
+		 * io_uring instances that don't use IORING_SETUP_SQPOLL.
+		 * For SQPOLL, only the single threaded io_sq_thread() will
+		 * manipulate the list, hence no extra locking is needed there.
+		 */
+		struct list_head	iopoll_list;
+		struct hlist_head	*cancel_hash;
+		unsigned		cancel_hash_bits;
+		bool			poll_multi_queue;
+	} ____cacheline_aligned_in_smp;
+
+	struct io_restriction		restrictions;
+
+	/* slow path rsrc auxilary data, used by update/register */
+	struct {
+		struct io_rsrc_node		*rsrc_backup_node;
+		struct io_mapped_ubuf		*dummy_ubuf;
+		struct io_rsrc_data		*file_data;
+		struct io_rsrc_data		*buf_data;
+
+		struct delayed_work		rsrc_put_work;
+		struct llist_head		rsrc_put_llist;
+		struct list_head		rsrc_ref_list;
+		spinlock_t			rsrc_ref_lock;
+	};
+
+	/* Keep this last, we don't need it for the fast path */
+	struct {
+		#if defined(CONFIG_UNIX)
+			struct socket		*ring_sock;
+		#endif
+		/* hashed buffered write serialization */
+		struct io_wq_hash		*hash_map;
+
+		/* Only used for accounting purposes */
+		struct user_struct		*user;
+		struct mm_struct		*mm_account;
+
+		/* ctx exit and cancelation */
+		struct llist_head		fallback_llist;
+		struct delayed_work		fallback_work;
+		struct work_struct		exit_work;
+		struct list_head		tctx_list;
+		struct completion		ref_comp;
+		u32				iowq_limits[2];
+		bool				iowq_limits_set;
+	};
+};
+
+struct io_uring_task {
+	/* submission side */
+	int			cached_refs;
+	struct xarray		xa;
+	struct wait_queue_head	wait;
+	const struct io_ring_ctx *last;
+	struct io_wq		*io_wq;
+	struct percpu_counter	inflight;
+	atomic_t		inflight_tracked;
+	atomic_t		in_idle;
+
+	spinlock_t		task_lock;
+	struct io_wq_work_list	task_list;
+	struct callback_head	task_work;
+	bool			task_running;
+};
+
+/*
+ * First field must be the file pointer in all the
+ * iocb unions! See also 'struct kiocb' in <linux/fs.h>
+ */
+struct io_poll_iocb {
+	struct file			*file;
+	struct wait_queue_head		*head;
+	__poll_t			events;
+	int				retries;
+	struct wait_queue_entry		wait;
+};
+
+struct io_poll_update {
+	struct file			*file;
+	u64				old_user_data;
+	u64				new_user_data;
+	__poll_t			events;
+	bool				update_events;
+	bool				update_user_data;
+};
+
+struct io_close {
+	struct file			*file;
+	int				fd;
+	u32				file_slot;
+};
+
+struct io_timeout_data {
+	struct io_kiocb			*req;
+	struct hrtimer			timer;
+	struct timespec64		ts;
+	enum hrtimer_mode		mode;
+	u32				flags;
+};
+
+struct io_accept {
+	struct file			*file;
+	struct sockaddr __user		*addr;
+	int __user			*addr_len;
+	int				flags;
+	u32				file_slot;
+	unsigned long			nofile;
+};
+
+struct io_sync {
+	struct file			*file;
+	loff_t				len;
+	loff_t				off;
+	int				flags;
+	int				mode;
+};
+
+struct io_cancel {
+	struct file			*file;
+	u64				addr;
+};
+
+struct io_timeout {
+	struct file			*file;
+	u32				off;
+	u32				target_seq;
+	struct list_head		list;
+	/* head of the link, used by linked timeouts only */
+	struct io_kiocb			*head;
+	/* for linked completions */
+	struct io_kiocb			*prev;
+};
+
+struct io_timeout_rem {
+	struct file			*file;
+	u64				addr;
+
+	/* timeout update */
+	struct timespec64		ts;
+	u32				flags;
+	bool				ltimeout;
+};
+
+struct io_rw {
+	/* NOTE: kiocb has the file as the first member, so don't do it here */
+	struct kiocb			kiocb;
+	u64				addr;
+	u64				len;
+};
+
+struct io_connect {
+	struct file			*file;
+	struct sockaddr __user		*addr;
+	int				addr_len;
+};
+
+struct io_sr_msg {
+	struct file			*file;
+	union {
+		struct compat_msghdr __user	*umsg_compat;
+		struct user_msghdr __user	*umsg;
+		void __user			*buf;
+	};
+	int				msg_flags;
+	int				bgid;
+	size_t				len;
+	size_t				done_io;
+	struct io_buffer		*kbuf;
+	void __user			*msg_control;
+};
+
+struct io_open {
+	struct file			*file;
+	int				dfd;
+	u32				file_slot;
+	struct filename			*filename;
+	struct open_how			how;
+	unsigned long			nofile;
+};
+
+struct io_rsrc_update {
+	struct file			*file;
+	u64				arg;
+	u32				nr_args;
+	u32				offset;
+};
+
+struct io_fadvise {
+	struct file			*file;
+	u64				offset;
+	u32				len;
+	u32				advice;
+};
+
+struct io_madvise {
+	struct file			*file;
+	u64				addr;
+	u32				len;
+	u32				advice;
+};
+
+struct io_epoll {
+	struct file			*file;
+	int				epfd;
+	int				op;
+	int				fd;
+	struct epoll_event		event;
+};
+
+struct io_splice {
+	struct file			*file_out;
+	loff_t				off_out;
+	loff_t				off_in;
+	u64				len;
+	int				splice_fd_in;
+	unsigned int			flags;
+};
+
+struct io_provide_buf {
+	struct file			*file;
+	__u64				addr;
+	__u32				len;
+	__u32				bgid;
+	__u16				nbufs;
+	__u16				bid;
+};
+
+struct io_statx {
+	struct file			*file;
+	int				dfd;
+	unsigned int			mask;
+	unsigned int			flags;
+	const char __user		*filename;
+	struct statx __user		*buffer;
+};
+
+struct io_shutdown {
+	struct file			*file;
+	int				how;
+};
+
+struct io_rename {
+	struct file			*file;
+	int				old_dfd;
+	int				new_dfd;
+	struct filename			*oldpath;
+	struct filename			*newpath;
+	int				flags;
+};
+
+struct io_unlink {
+	struct file			*file;
+	int				dfd;
+	int				flags;
+	struct filename			*filename;
+};
+
+struct io_mkdir {
+	struct file			*file;
+	int				dfd;
+	umode_t				mode;
+	struct filename			*filename;
+};
+
+struct io_symlink {
+	struct file			*file;
+	int				new_dfd;
+	struct filename			*oldpath;
+	struct filename			*newpath;
+};
+
+struct io_hardlink {
+	struct file			*file;
+	int				old_dfd;
+	int				new_dfd;
+	struct filename			*oldpath;
+	struct filename			*newpath;
+	int				flags;
+};
+
+struct io_completion {
+	struct file			*file;
+	u32				cflags;
+};
+
+struct io_async_connect {
+	struct sockaddr_storage		address;
+};
+
+struct io_async_msghdr {
+	struct iovec			fast_iov[UIO_FASTIOV];
+	/* points to an allocated iov, if NULL we use fast_iov instead */
+	struct iovec			*free_iov;
+	struct sockaddr __user		*uaddr;
+	struct msghdr			msg;
+	struct sockaddr_storage		addr;
+};
+
+struct io_async_rw {
+	struct iovec			fast_iov[UIO_FASTIOV];
+	const struct iovec		*free_iovec;
+	struct iov_iter			iter;
+	struct iov_iter_state		iter_state;
+	size_t				bytes_done;
+	struct wait_page_queue		wpq;
+};
+
+enum {
+	REQ_F_FIXED_FILE_BIT	= IOSQE_FIXED_FILE_BIT,
+	REQ_F_IO_DRAIN_BIT	= IOSQE_IO_DRAIN_BIT,
+	REQ_F_LINK_BIT		= IOSQE_IO_LINK_BIT,
+	REQ_F_HARDLINK_BIT	= IOSQE_IO_HARDLINK_BIT,
+	REQ_F_FORCE_ASYNC_BIT	= IOSQE_ASYNC_BIT,
+	REQ_F_BUFFER_SELECT_BIT	= IOSQE_BUFFER_SELECT_BIT,
+
+	/* first byte is taken by user flags, shift it to not overlap */
+	REQ_F_FAIL_BIT		= 8,
+	REQ_F_INFLIGHT_BIT,
+	REQ_F_CUR_POS_BIT,
+	REQ_F_NOWAIT_BIT,
+	REQ_F_LINK_TIMEOUT_BIT,
+	REQ_F_NEED_CLEANUP_BIT,
+	REQ_F_POLLED_BIT,
+	REQ_F_BUFFER_SELECTED_BIT,
+	REQ_F_COMPLETE_INLINE_BIT,
+	REQ_F_REISSUE_BIT,
+	REQ_F_CREDS_BIT,
+	REQ_F_REFCOUNT_BIT,
+	REQ_F_ARM_LTIMEOUT_BIT,
+	REQ_F_PARTIAL_IO_BIT,
+	/* keep async read/write and isreg together and in order */
+	REQ_F_NOWAIT_READ_BIT,
+	REQ_F_NOWAIT_WRITE_BIT,
+	REQ_F_ISREG_BIT,
+
+	/* not a real bit, just to check we're not overflowing the space */
+	__REQ_F_LAST_BIT,
+};
+
+enum {
+	/* ctx owns file */
+	REQ_F_FIXED_FILE	= BIT(REQ_F_FIXED_FILE_BIT),
+	/* drain existing IO first */
+	REQ_F_IO_DRAIN		= BIT(REQ_F_IO_DRAIN_BIT),
+	/* linked sqes */
+	REQ_F_LINK		= BIT(REQ_F_LINK_BIT),
+	/* doesn't sever on completion < 0 */
+	REQ_F_HARDLINK		= BIT(REQ_F_HARDLINK_BIT),
+	/* IOSQE_ASYNC */
+	REQ_F_FORCE_ASYNC	= BIT(REQ_F_FORCE_ASYNC_BIT),
+	/* IOSQE_BUFFER_SELECT */
+	REQ_F_BUFFER_SELECT	= BIT(REQ_F_BUFFER_SELECT_BIT),
+
+	/* fail rest of links */
+	REQ_F_FAIL		= BIT(REQ_F_FAIL_BIT),
+	/* on inflight list, should be cancelled and waited on exit reliably */
+	REQ_F_INFLIGHT		= BIT(REQ_F_INFLIGHT_BIT),
+	/* read/write uses file position */
+	REQ_F_CUR_POS		= BIT(REQ_F_CUR_POS_BIT),
+	/* must not punt to workers */
+	REQ_F_NOWAIT		= BIT(REQ_F_NOWAIT_BIT),
+	/* has or had linked timeout */
+	REQ_F_LINK_TIMEOUT	= BIT(REQ_F_LINK_TIMEOUT_BIT),
+	/* needs cleanup */
+	REQ_F_NEED_CLEANUP	= BIT(REQ_F_NEED_CLEANUP_BIT),
+	/* already went through poll handler */
+	REQ_F_POLLED		= BIT(REQ_F_POLLED_BIT),
+	/* buffer already selected */
+	REQ_F_BUFFER_SELECTED	= BIT(REQ_F_BUFFER_SELECTED_BIT),
+	/* completion is deferred through io_comp_state */
+	REQ_F_COMPLETE_INLINE	= BIT(REQ_F_COMPLETE_INLINE_BIT),
+	/* caller should reissue async */
+	REQ_F_REISSUE		= BIT(REQ_F_REISSUE_BIT),
+	/* supports async reads */
+	REQ_F_NOWAIT_READ	= BIT(REQ_F_NOWAIT_READ_BIT),
+	/* supports async writes */
+	REQ_F_NOWAIT_WRITE	= BIT(REQ_F_NOWAIT_WRITE_BIT),
+	/* regular file */
+	REQ_F_ISREG		= BIT(REQ_F_ISREG_BIT),
+	/* has creds assigned */
+	REQ_F_CREDS		= BIT(REQ_F_CREDS_BIT),
+	/* skip refcounting if not set */
+	REQ_F_REFCOUNT		= BIT(REQ_F_REFCOUNT_BIT),
+	/* there is a linked timeout that has to be armed */
+	REQ_F_ARM_LTIMEOUT	= BIT(REQ_F_ARM_LTIMEOUT_BIT),
+	/* request has already done partial IO */
+	REQ_F_PARTIAL_IO	= BIT(REQ_F_PARTIAL_IO_BIT),
+};
+
+struct async_poll {
+	struct io_poll_iocb	poll;
+	struct io_poll_iocb	*double_poll;
+};
+
+typedef void (*io_req_tw_func_t)(struct io_kiocb *req, bool *locked);
+
+struct io_task_work {
+	union {
+		struct io_wq_work_node	node;
+		struct llist_node	fallback_node;
+	};
+	io_req_tw_func_t		func;
+};
+
+enum {
+	IORING_RSRC_FILE		= 0,
+	IORING_RSRC_BUFFER		= 1,
+};
+
+/*
+ * NOTE! Each of the iocb union members has the file pointer
+ * as the first entry in their struct definition. So you can
+ * access the file pointer through any of the sub-structs,
+ * or directly as just 'ki_filp' in this struct.
+ */
+struct io_kiocb {
+	union {
+		struct file		*file;
+		struct io_rw		rw;
+		struct io_poll_iocb	poll;
+		struct io_poll_update	poll_update;
+		struct io_accept	accept;
+		struct io_sync		sync;
+		struct io_cancel	cancel;
+		struct io_timeout	timeout;
+		struct io_timeout_rem	timeout_rem;
+		struct io_connect	connect;
+		struct io_sr_msg	sr_msg;
+		struct io_open		open;
+		struct io_close		close;
+		struct io_rsrc_update	rsrc_update;
+		struct io_fadvise	fadvise;
+		struct io_madvise	madvise;
+		struct io_epoll		epoll;
+		struct io_splice	splice;
+		struct io_provide_buf	pbuf;
+		struct io_statx		statx;
+		struct io_shutdown	shutdown;
+		struct io_rename	rename;
+		struct io_unlink	unlink;
+		struct io_mkdir		mkdir;
+		struct io_symlink	symlink;
+		struct io_hardlink	hardlink;
+		/* use only after cleaning per-op data, see io_clean_op() */
+		struct io_completion	compl;
+	};
+
+	/* opcode allocated if it needs to store data for async defer */
+	void				*async_data;
+	u8				opcode;
+	/* polled IO has completed */
+	u8				iopoll_completed;
+
+	u16				buf_index;
+	u32				result;
+
+	struct io_ring_ctx		*ctx;
+	unsigned int			flags;
+	atomic_t			refs;
+	struct task_struct		*task;
+	u64				user_data;
+
+	struct io_kiocb			*link;
+	struct percpu_ref		*fixed_rsrc_refs;
+
+	/* used with ctx->iopoll_list with reads/writes */
+	struct list_head		inflight_entry;
+	struct io_task_work		io_task_work;
+	/* for polled requests, i.e. IORING_OP_POLL_ADD and async armed poll */
+	struct hlist_node		hash_node;
+	struct async_poll		*apoll;
+	struct io_wq_work		work;
+	const struct cred		*creds;
+
+	/* store used ubuf, so we can prevent reloading */
+	struct io_mapped_ubuf		*imu;
+	/* stores selected buf, valid IFF REQ_F_BUFFER_SELECTED is set */
+	struct io_buffer		*kbuf;
+	atomic_t			poll_refs;
+};
+
+struct io_tctx_node {
+	struct list_head	ctx_node;
+	struct task_struct	*task;
+	struct io_ring_ctx	*ctx;
+};
+
+struct io_defer_entry {
+	struct list_head	list;
+	struct io_kiocb		*req;
+	u32			seq;
+};
+
+struct io_op_def {
+	/* needs req->file assigned */
+	unsigned		needs_file : 1;
+	/* hash wq insertion if file is a regular file */
+	unsigned		hash_reg_file : 1;
+	/* unbound wq insertion if file is a non-regular file */
+	unsigned		unbound_nonreg_file : 1;
+	/* opcode is not supported by this kernel */
+	unsigned		not_supported : 1;
+	/* set if opcode supports polled "wait" */
+	unsigned		pollin : 1;
+	unsigned		pollout : 1;
+	/* op supports buffer selection */
+	unsigned		buffer_select : 1;
+	/* do prep async if is going to be punted */
+	unsigned		needs_async_setup : 1;
+	/* should block plug */
+	unsigned		plug : 1;
+	/* size of async data needed, if any */
+	unsigned short		async_size;
+};
+
+static const struct io_op_def io_op_defs[] = {
+	[IORING_OP_NOP] = {},
+	[IORING_OP_READV] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollin			= 1,
+		.buffer_select		= 1,
+		.needs_async_setup	= 1,
+		.plug			= 1,
+		.async_size		= sizeof(struct io_async_rw),
+	},
+	[IORING_OP_WRITEV] = {
+		.needs_file		= 1,
+		.hash_reg_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollout		= 1,
+		.needs_async_setup	= 1,
+		.plug			= 1,
+		.async_size		= sizeof(struct io_async_rw),
+	},
+	[IORING_OP_FSYNC] = {
+		.needs_file		= 1,
+	},
+	[IORING_OP_READ_FIXED] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollin			= 1,
+		.plug			= 1,
+		.async_size		= sizeof(struct io_async_rw),
+	},
+	[IORING_OP_WRITE_FIXED] = {
+		.needs_file		= 1,
+		.hash_reg_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollout		= 1,
+		.plug			= 1,
+		.async_size		= sizeof(struct io_async_rw),
+	},
+	[IORING_OP_POLL_ADD] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+	},
+	[IORING_OP_POLL_REMOVE] = {},
+	[IORING_OP_SYNC_FILE_RANGE] = {
+		.needs_file		= 1,
+	},
+	[IORING_OP_SENDMSG] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollout		= 1,
+		.needs_async_setup	= 1,
+		.async_size		= sizeof(struct io_async_msghdr),
+	},
+	[IORING_OP_RECVMSG] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollin			= 1,
+		.buffer_select		= 1,
+		.needs_async_setup	= 1,
+		.async_size		= sizeof(struct io_async_msghdr),
+	},
+	[IORING_OP_TIMEOUT] = {
+		.async_size		= sizeof(struct io_timeout_data),
+	},
+	[IORING_OP_TIMEOUT_REMOVE] = {
+		/* used by timeout updates' prep() */
+	},
+	[IORING_OP_ACCEPT] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollin			= 1,
+	},
+	[IORING_OP_ASYNC_CANCEL] = {},
+	[IORING_OP_LINK_TIMEOUT] = {
+		.async_size		= sizeof(struct io_timeout_data),
+	},
+	[IORING_OP_CONNECT] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollout		= 1,
+		.needs_async_setup	= 1,
+		.async_size		= sizeof(struct io_async_connect),
+	},
+	[IORING_OP_FALLOCATE] = {
+		.needs_file		= 1,
+	},
+	[IORING_OP_OPENAT] = {},
+	[IORING_OP_CLOSE] = {},
+	[IORING_OP_FILES_UPDATE] = {},
+	[IORING_OP_STATX] = {},
+	[IORING_OP_READ] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollin			= 1,
+		.buffer_select		= 1,
+		.plug			= 1,
+		.async_size		= sizeof(struct io_async_rw),
+	},
+	[IORING_OP_WRITE] = {
+		.needs_file		= 1,
+		.hash_reg_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollout		= 1,
+		.plug			= 1,
+		.async_size		= sizeof(struct io_async_rw),
+	},
+	[IORING_OP_FADVISE] = {
+		.needs_file		= 1,
+	},
+	[IORING_OP_MADVISE] = {},
+	[IORING_OP_SEND] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollout		= 1,
+	},
+	[IORING_OP_RECV] = {
+		.needs_file		= 1,
+		.unbound_nonreg_file	= 1,
+		.pollin			= 1,
+		.buffer_select		= 1,
+	},
+	[IORING_OP_OPENAT2] = {
+	},
+	[IORING_OP_EPOLL_CTL] = {
+		.unbound_nonreg_file	= 1,
+	},
+	[IORING_OP_SPLICE] = {
+		.needs_file		= 1,
+		.hash_reg_file		= 1,
+		.unbound_nonreg_file	= 1,
+	},
+	[IORING_OP_PROVIDE_BUFFERS] = {},
+	[IORING_OP_REMOVE_BUFFERS] = {},
+	[IORING_OP_TEE] = {
+		.needs_file		= 1,
+		.hash_reg_file		= 1,
+		.unbound_nonreg_file	= 1,
+	},
+	[IORING_OP_SHUTDOWN] = {
+		.needs_file		= 1,
+	},
+	[IORING_OP_RENAMEAT] = {},
+	[IORING_OP_UNLINKAT] = {},
+};
+
+/* 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)
+
+static bool io_disarm_next(struct io_kiocb *req);
+static void io_uring_del_tctx_node(unsigned long index);
+static void io_uring_try_cancel_requests(struct io_ring_ctx *ctx,
+					 struct task_struct *task,
+					 bool cancel_all);
+static void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd);
+
+static void io_fill_cqe_req(struct io_kiocb *req, s32 res, u32 cflags);
+
+static void io_put_req(struct io_kiocb *req);
+static void io_put_req_deferred(struct io_kiocb *req);
+static void io_dismantle_req(struct io_kiocb *req);
+static void io_queue_linked_timeout(struct io_kiocb *req);
+static int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
+				     struct io_uring_rsrc_update2 *up,
+				     unsigned nr_args);
+static void io_clean_op(struct io_kiocb *req);
+static struct file *io_file_get(struct io_ring_ctx *ctx,
+				struct io_kiocb *req, int fd, bool fixed,
+				unsigned int issue_flags);
+static void __io_queue_sqe(struct io_kiocb *req);
+static void io_rsrc_put_work(struct work_struct *work);
+
+static void io_req_task_queue(struct io_kiocb *req);
+static void io_submit_flush_completions(struct io_ring_ctx *ctx);
+static int io_req_prep_async(struct io_kiocb *req);
+
+static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
+				 unsigned int issue_flags, u32 slot_index);
+static int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags);
+
+static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer);
+
+static struct kmem_cache *req_cachep;
+
+static const struct file_operations io_uring_fops;
+
+struct sock *io_uring_get_socket(struct file *file)
+{
+#if defined(CONFIG_UNIX)
+	if (file->f_op == &io_uring_fops) {
+		struct io_ring_ctx *ctx = file->private_data;
+
+		return ctx->ring_sock->sk;
+	}
+#endif
+	return NULL;
+}
+EXPORT_SYMBOL(io_uring_get_socket);
+
+static inline void io_tw_lock(struct io_ring_ctx *ctx, bool *locked)
+{
+	if (!*locked) {
+		mutex_lock(&ctx->uring_lock);
+		*locked = true;
+	}
+}
+
+#define io_for_each_link(pos, head) \
+	for (pos = (head); pos; pos = pos->link)
+
+/*
+ * Shamelessly stolen from the mm implementation of page reference checking,
+ * see commit f958d7b528b1 for details.
+ */
+#define req_ref_zero_or_close_to_overflow(req)	\
+	((unsigned int) atomic_read(&(req->refs)) + 127u <= 127u)
+
+static inline bool req_ref_inc_not_zero(struct io_kiocb *req)
+{
+	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
+	return atomic_inc_not_zero(&req->refs);
+}
+
+static inline bool req_ref_put_and_test(struct io_kiocb *req)
+{
+	if (likely(!(req->flags & REQ_F_REFCOUNT)))
+		return true;
+
+	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
+	return atomic_dec_and_test(&req->refs);
+}
+
+static inline void req_ref_get(struct io_kiocb *req)
+{
+	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
+	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
+	atomic_inc(&req->refs);
+}
+
+static inline void __io_req_set_refcount(struct io_kiocb *req, int nr)
+{
+	if (!(req->flags & REQ_F_REFCOUNT)) {
+		req->flags |= REQ_F_REFCOUNT;
+		atomic_set(&req->refs, nr);
+	}
+}
+
+static inline void io_req_set_refcount(struct io_kiocb *req)
+{
+	__io_req_set_refcount(req, 1);
+}
+
+static inline void io_req_set_rsrc_node(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (!req->fixed_rsrc_refs) {
+		req->fixed_rsrc_refs = &ctx->rsrc_node->refs;
+		percpu_ref_get(req->fixed_rsrc_refs);
+	}
+}
+
+static void io_refs_resurrect(struct percpu_ref *ref, struct completion *compl)
+{
+	bool got = percpu_ref_tryget(ref);
+
+	/* already at zero, wait for ->release() */
+	if (!got)
+		wait_for_completion(compl);
+	percpu_ref_resurrect(ref);
+	if (got)
+		percpu_ref_put(ref);
+}
+
+static bool io_match_task(struct io_kiocb *head, struct task_struct *task,
+			  bool cancel_all)
+	__must_hold(&req->ctx->timeout_lock)
+{
+	struct io_kiocb *req;
+
+	if (task && head->task != task)
+		return false;
+	if (cancel_all)
+		return true;
+
+	io_for_each_link(req, head) {
+		if (req->flags & REQ_F_INFLIGHT)
+			return true;
+	}
+	return false;
+}
+
+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.
+ */
+static 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_set_fail(struct io_kiocb *req)
+{
+	req->flags |= REQ_F_FAIL;
+}
+
+static inline void req_fail_link_node(struct io_kiocb *req, int res)
+{
+	req_set_fail(req);
+	req->result = res;
+}
+
+static void io_ring_ctx_ref_free(struct percpu_ref *ref)
+{
+	struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
+
+	complete(&ctx->ref_comp);
+}
+
+static inline bool io_is_timeout_noseq(struct io_kiocb *req)
+{
+	return !req->timeout.off;
+}
+
+static 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;
+	bool locked = false;
+
+	percpu_ref_get(&ctx->refs);
+	llist_for_each_entry_safe(req, tmp, node, io_task_work.fallback_node)
+		req->io_task_work.func(req, &locked);
+
+	if (locked) {
+		if (ctx->submit_state.compl_nr)
+			io_submit_flush_completions(ctx);
+		mutex_unlock(&ctx->uring_lock);
+	}
+	percpu_ref_put(&ctx->refs);
+
+}
+
+static 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;
+
+	/*
+	 * 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.
+	 */
+	hash_bits = ilog2(p->cq_entries);
+	hash_bits -= 5;
+	if (hash_bits <= 0)
+		hash_bits = 1;
+	ctx->cancel_hash_bits = hash_bits;
+	ctx->cancel_hash = kmalloc((1U << hash_bits) * sizeof(struct hlist_head),
+					GFP_KERNEL);
+	if (!ctx->cancel_hash)
+		goto err;
+	__hash_init(ctx->cancel_hash, 1U << hash_bits);
+
+	ctx->dummy_ubuf = kzalloc(sizeof(*ctx->dummy_ubuf), GFP_KERNEL);
+	if (!ctx->dummy_ubuf)
+		goto err;
+	/* set invalid range, so io_import_fixed() fails meeting it */
+	ctx->dummy_ubuf->ubuf = -1UL;
+
+	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
+			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL))
+		goto err;
+
+	ctx->flags = p->flags;
+	init_waitqueue_head(&ctx->sqo_sq_wait);
+	INIT_LIST_HEAD(&ctx->sqd_list);
+	init_waitqueue_head(&ctx->poll_wait);
+	INIT_LIST_HEAD(&ctx->cq_overflow_list);
+	init_completion(&ctx->ref_comp);
+	xa_init_flags(&ctx->io_buffers, XA_FLAGS_ALLOC1);
+	xa_init_flags(&ctx->personalities, XA_FLAGS_ALLOC1);
+	mutex_init(&ctx->uring_lock);
+	init_waitqueue_head(&ctx->cq_wait);
+	spin_lock_init(&ctx->completion_lock);
+	spin_lock_init(&ctx->timeout_lock);
+	INIT_LIST_HEAD(&ctx->iopoll_list);
+	INIT_LIST_HEAD(&ctx->defer_list);
+	INIT_LIST_HEAD(&ctx->timeout_list);
+	INIT_LIST_HEAD(&ctx->ltimeout_list);
+	spin_lock_init(&ctx->rsrc_ref_lock);
+	INIT_LIST_HEAD(&ctx->rsrc_ref_list);
+	INIT_DELAYED_WORK(&ctx->rsrc_put_work, io_rsrc_put_work);
+	init_llist_head(&ctx->rsrc_put_llist);
+	INIT_LIST_HEAD(&ctx->tctx_list);
+	INIT_LIST_HEAD(&ctx->submit_state.free_list);
+	INIT_LIST_HEAD(&ctx->locked_free_list);
+	INIT_DELAYED_WORK(&ctx->fallback_work, io_fallback_req_func);
+	return ctx;
+err:
+	kfree(ctx->dummy_ubuf);
+	kfree(ctx->cancel_hash);
+	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;
+}
+
+#define FFS_ASYNC_READ		0x1UL
+#define FFS_ASYNC_WRITE		0x2UL
+#ifdef CONFIG_64BIT
+#define FFS_ISREG		0x4UL
+#else
+#define FFS_ISREG		0x0UL
+#endif
+#define FFS_MASK		~(FFS_ASYNC_READ|FFS_ASYNC_WRITE|FFS_ISREG)
+
+static inline bool io_req_ffs_set(struct io_kiocb *req)
+{
+	return IS_ENABLED(CONFIG_64BIT) && (req->flags & REQ_F_FIXED_FILE);
+}
+
+static 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 void io_prep_async_work(struct io_kiocb *req)
+{
+	const struct io_op_def *def = &io_op_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;
+	if (req->flags & REQ_F_FORCE_ASYNC)
+		req->work.flags |= IO_WQ_WORK_CONCURRENT;
+
+	if (req->flags & REQ_F_ISREG) {
+		if (def->hash_reg_file || (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);
+	}
+}
+
+static void io_queue_async_work(struct io_kiocb *req, bool *locked)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_kiocb *link = io_prep_linked_timeout(req);
+	struct io_uring_task *tctx = req->task->io_uring;
+
+	/* must not take the lock, NULL it as a precaution */
+	locked = NULL;
+
+	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(ctx, io_wq_is_hashed(&req->work), req,
+					&req->work, req->flags);
+	io_wq_enqueue(tctx->io_wq, &req->work);
+	if (link)
+		io_queue_linked_timeout(link);
+}
+
+static void io_kill_timeout(struct io_kiocb *req, int status)
+	__must_hold(&req->ctx->completion_lock)
+	__must_hold(&req->ctx->timeout_lock)
+{
+	struct io_timeout_data *io = req->async_data;
+
+	if (hrtimer_try_to_cancel(&io->timer) != -1) {
+		if (status)
+			req_set_fail(req);
+		atomic_set(&req->ctx->cq_timeouts,
+			atomic_read(&req->ctx->cq_timeouts) + 1);
+		list_del_init(&req->timeout.list);
+		io_fill_cqe_req(req, status, 0);
+		io_put_req_deferred(req);
+	}
+}
+
+static void io_queue_deferred(struct io_ring_ctx *ctx)
+{
+	lockdep_assert_held(&ctx->completion_lock);
+
+	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_flush_timeouts(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->completion_lock)
+{
+	u32 seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
+	struct io_kiocb *req, *tmp;
+
+	spin_lock_irq(&ctx->timeout_lock);
+	list_for_each_entry_safe(req, tmp, &ctx->timeout_list, timeout.list) {
+		u32 events_needed, events_got;
+
+		if (io_is_timeout_noseq(req))
+			break;
+
+		/*
+		 * Since seq can easily wrap around over time, subtract
+		 * the last seq at which timeouts were flushed before comparing.
+		 * Assuming not more than 2^31-1 events have happened since,
+		 * these subtractions won't have wrapped, so we can check if
+		 * target is in [last_seq, current_seq] by comparing the two.
+		 */
+		events_needed = req->timeout.target_seq - ctx->cq_last_tm_flush;
+		events_got = seq - ctx->cq_last_tm_flush;
+		if (events_got < events_needed)
+			break;
+
+		io_kill_timeout(req, 0);
+	}
+	ctx->cq_last_tm_flush = seq;
+	spin_unlock_irq(&ctx->timeout_lock);
+}
+
+static void __io_commit_cqring_flush(struct io_ring_ctx *ctx)
+{
+	if (ctx->off_timeout_used)
+		io_flush_timeouts(ctx);
+	if (ctx->drain_active)
+		io_queue_deferred(ctx);
+}
+
+static inline bool io_commit_needs_flush(struct io_ring_ctx *ctx)
+{
+	return ctx->off_timeout_used || ctx->drain_active;
+}
+
+static inline void __io_commit_cqring(struct io_ring_ctx *ctx)
+{
+	/* order cqe stores with ring update */
+	smp_store_release(&ctx->rings->cq.tail, ctx->cached_cq_tail);
+}
+
+static inline void io_commit_cqring(struct io_ring_ctx *ctx)
+{
+	if (unlikely(io_commit_needs_flush(ctx)))
+		__io_commit_cqring_flush(ctx);
+	__io_commit_cqring(ctx);
+}
+
+static inline bool io_sqring_full(struct io_ring_ctx *ctx)
+{
+	struct io_rings *r = ctx->rings;
+
+	return READ_ONCE(r->sq.tail) - ctx->cached_sq_head == ctx->sq_entries;
+}
+
+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 struct io_uring_cqe *io_get_cqe(struct io_ring_ctx *ctx)
+{
+	struct io_rings *rings = ctx->rings;
+	unsigned tail, mask = ctx->cq_entries - 1;
+
+	/*
+	 * writes to the cq entry need to come after reading head; the
+	 * control dependency is enough as we're using WRITE_ONCE to
+	 * fill the cq entry
+	 */
+	if (__io_cqring_events(ctx) == ctx->cq_entries)
+		return NULL;
+
+	tail = ctx->cached_cq_tail++;
+	return &rings->cqes[tail & mask];
+}
+
+static inline bool io_should_trigger_evfd(struct io_ring_ctx *ctx)
+{
+	if (likely(!ctx->cq_ev_fd))
+		return false;
+	if (READ_ONCE(ctx->rings->cq_flags) & IORING_CQ_EVENTFD_DISABLED)
+		return false;
+	return !ctx->eventfd_async || io_wq_current_is_worker();
+}
+
+/*
+ * This should only get called 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.
+ */
+static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
+{
+	/*
+	 * wake_up_all() may seem excessive, but io_wake_function() and
+	 * io_should_wake() handle the termination of the loop and only
+	 * wake as many waiters as we need to.
+	 */
+	if (wq_has_sleeper(&ctx->cq_wait))
+		__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
+				poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
+	if (ctx->sq_data && waitqueue_active(&ctx->sq_data->wait))
+		wake_up(&ctx->sq_data->wait);
+	if (io_should_trigger_evfd(ctx))
+		eventfd_signal_mask(ctx->cq_ev_fd, 1, EPOLL_URING_WAKE);
+	if (waitqueue_active(&ctx->poll_wait))
+		__wake_up(&ctx->poll_wait, TASK_INTERRUPTIBLE, 0,
+				poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
+}
+
+static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
+{
+	/* see waitqueue_active() comment */
+	smp_mb();
+
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		if (waitqueue_active(&ctx->cq_wait))
+			__wake_up(&ctx->cq_wait, TASK_NORMAL, 0,
+				  poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
+	}
+	if (io_should_trigger_evfd(ctx))
+		eventfd_signal_mask(ctx->cq_ev_fd, 1, EPOLL_URING_WAKE);
+	if (waitqueue_active(&ctx->poll_wait))
+		__wake_up(&ctx->poll_wait, TASK_INTERRUPTIBLE, 0,
+				poll_to_key(EPOLL_URING_WAKE | EPOLLIN));
+}
+
+/* Returns true if there are no backlogged entries after the flush */
+static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
+{
+	bool all_flushed, posted;
+
+	if (!force && __io_cqring_events(ctx) == ctx->cq_entries)
+		return false;
+
+	posted = false;
+	spin_lock(&ctx->completion_lock);
+	while (!list_empty(&ctx->cq_overflow_list)) {
+		struct io_uring_cqe *cqe = io_get_cqe(ctx);
+		struct io_overflow_cqe *ocqe;
+
+		if (!cqe && !force)
+			break;
+		ocqe = list_first_entry(&ctx->cq_overflow_list,
+					struct io_overflow_cqe, list);
+		if (cqe)
+			memcpy(cqe, &ocqe->cqe, sizeof(*cqe));
+		else
+			io_account_cq_overflow(ctx);
+
+		posted = true;
+		list_del(&ocqe->list);
+		kfree(ocqe);
+	}
+
+	all_flushed = list_empty(&ctx->cq_overflow_list);
+	if (all_flushed) {
+		clear_bit(0, &ctx->check_cq_overflow);
+		WRITE_ONCE(ctx->rings->sq_flags,
+			   ctx->rings->sq_flags & ~IORING_SQ_CQ_OVERFLOW);
+	}
+
+	if (posted)
+		io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+	if (posted)
+		io_cqring_ev_posted(ctx);
+	return all_flushed;
+}
+
+static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx)
+{
+	bool ret = true;
+
+	if (test_bit(0, &ctx->check_cq_overflow)) {
+		/* iopoll syncs against uring_lock, not completion_lock */
+		if (ctx->flags & IORING_SETUP_IOPOLL)
+			mutex_lock(&ctx->uring_lock);
+		ret = __io_cqring_overflow_flush(ctx, false);
+		if (ctx->flags & IORING_SETUP_IOPOLL)
+			mutex_unlock(&ctx->uring_lock);
+	}
+
+	return ret;
+}
+
+/* must to be called somewhat shortly after putting a request */
+static inline void io_put_task(struct task_struct *task, int nr)
+{
+	struct io_uring_task *tctx = task->io_uring;
+
+	if (likely(task == current)) {
+		tctx->cached_refs += nr;
+	} else {
+		percpu_counter_sub(&tctx->inflight, nr);
+		if (unlikely(atomic_read(&tctx->in_idle)))
+			wake_up(&tctx->wait);
+		put_task_struct_many(task, nr);
+	}
+}
+
+static 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 inline void io_get_task_refs(int nr)
+{
+	struct io_uring_task *tctx = current->io_uring;
+
+	tctx->cached_refs -= nr;
+	if (unlikely(tctx->cached_refs < 0))
+		io_task_refs_refill(tctx);
+}
+
+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)
+{
+	struct io_overflow_cqe *ocqe;
+
+	ocqe = kmalloc(sizeof(*ocqe), GFP_ATOMIC | __GFP_ACCOUNT);
+	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);
+		return false;
+	}
+	if (list_empty(&ctx->cq_overflow_list)) {
+		set_bit(0, &ctx->check_cq_overflow);
+		WRITE_ONCE(ctx->rings->sq_flags,
+			   ctx->rings->sq_flags | IORING_SQ_CQ_OVERFLOW);
+
+	}
+	ocqe->cqe.user_data = user_data;
+	ocqe->cqe.res = res;
+	ocqe->cqe.flags = cflags;
+	list_add_tail(&ocqe->list, &ctx->cq_overflow_list);
+	return true;
+}
+
+static inline bool __io_fill_cqe(struct io_ring_ctx *ctx, u64 user_data,
+				 s32 res, u32 cflags)
+{
+	struct io_uring_cqe *cqe;
+
+	trace_io_uring_complete(ctx, user_data, res, cflags);
+
+	/*
+	 * If we can't get a cq entry, userspace overflowed the
+	 * submission (by quite a lot). Increment the overflow count in
+	 * the ring.
+	 */
+	cqe = io_get_cqe(ctx);
+	if (likely(cqe)) {
+		WRITE_ONCE(cqe->user_data, user_data);
+		WRITE_ONCE(cqe->res, res);
+		WRITE_ONCE(cqe->flags, cflags);
+		return true;
+	}
+	return io_cqring_event_overflow(ctx, user_data, res, cflags);
+}
+
+static noinline void io_fill_cqe_req(struct io_kiocb *req, s32 res, u32 cflags)
+{
+	__io_fill_cqe(req->ctx, req->user_data, res, cflags);
+}
+
+static noinline bool io_fill_cqe_aux(struct io_ring_ctx *ctx, u64 user_data,
+				     s32 res, u32 cflags)
+{
+	ctx->cq_extra++;
+	return __io_fill_cqe(ctx, user_data, res, cflags);
+}
+
+static void io_req_complete_post(struct io_kiocb *req, s32 res,
+				 u32 cflags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	spin_lock(&ctx->completion_lock);
+	__io_fill_cqe(ctx, req->user_data, res, cflags);
+	/*
+	 * 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 & (REQ_F_LINK | REQ_F_HARDLINK)) {
+			if (req->flags & IO_DISARM_MASK)
+				io_disarm_next(req);
+			if (req->link) {
+				io_req_task_queue(req->link);
+				req->link = NULL;
+			}
+		}
+		io_dismantle_req(req);
+		io_put_task(req->task, 1);
+		list_add(&req->inflight_entry, &ctx->locked_free_list);
+		ctx->locked_free_nr++;
+	} else {
+		if (!percpu_ref_tryget(&ctx->refs))
+			req = NULL;
+	}
+	io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+
+	if (req) {
+		io_cqring_ev_posted(ctx);
+		percpu_ref_put(&ctx->refs);
+	}
+}
+
+static inline bool io_req_needs_clean(struct io_kiocb *req)
+{
+	return req->flags & IO_REQ_CLEAN_FLAGS;
+}
+
+static inline void io_req_complete_state(struct io_kiocb *req, s32 res,
+					 u32 cflags)
+{
+	if (io_req_needs_clean(req))
+		io_clean_op(req);
+	req->result = res;
+	req->compl.cflags = cflags;
+	req->flags |= REQ_F_COMPLETE_INLINE;
+}
+
+static inline void __io_req_complete(struct io_kiocb *req, unsigned issue_flags,
+				     s32 res, u32 cflags)
+{
+	if (issue_flags & IO_URING_F_COMPLETE_DEFER)
+		io_req_complete_state(req, res, cflags);
+	else
+		io_req_complete_post(req, res, cflags);
+}
+
+static inline void io_req_complete(struct io_kiocb *req, s32 res)
+{
+	__io_req_complete(req, 0, res, 0);
+}
+
+static void io_req_complete_failed(struct io_kiocb *req, s32 res)
+{
+	req_set_fail(req);
+	io_req_complete_post(req, res, 0);
+}
+
+static void io_req_complete_fail_submit(struct io_kiocb *req)
+{
+	/*
+	 * 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_complete_failed(req, req->result);
+}
+
+/*
+ * 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 */
+	req->result = 0;
+}
+
+static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
+					struct io_submit_state *state)
+{
+	spin_lock(&ctx->completion_lock);
+	list_splice_init(&ctx->locked_free_list, &state->free_list);
+	ctx->locked_free_nr = 0;
+	spin_unlock(&ctx->completion_lock);
+}
+
+/* Returns true IFF there are requests in the cache */
+static bool io_flush_cached_reqs(struct io_ring_ctx *ctx)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+	int nr;
+
+	/*
+	 * 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 (READ_ONCE(ctx->locked_free_nr) > IO_COMPL_BATCH)
+		io_flush_cached_locked_reqs(ctx, state);
+
+	nr = state->free_reqs;
+	while (!list_empty(&state->free_list)) {
+		struct io_kiocb *req = list_first_entry(&state->free_list,
+					struct io_kiocb, inflight_entry);
+
+		list_del(&req->inflight_entry);
+		state->reqs[nr++] = req;
+		if (nr == ARRAY_SIZE(state->reqs))
+			break;
+	}
+
+	state->free_reqs = nr;
+	return nr != 0;
+}
+
+/*
+ * 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.
+ */
+static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+	gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
+	int ret, i;
+
+	BUILD_BUG_ON(ARRAY_SIZE(state->reqs) < IO_REQ_ALLOC_BATCH);
+
+	if (likely(state->free_reqs || io_flush_cached_reqs(ctx)))
+		goto got_req;
+
+	ret = kmem_cache_alloc_bulk(req_cachep, gfp, IO_REQ_ALLOC_BATCH,
+				    state->reqs);
+
+	/*
+	 * Bulk alloc is all-or-nothing. If we fail to get a batch,
+	 * retry single alloc to be on the safe side.
+	 */
+	if (unlikely(ret <= 0)) {
+		state->reqs[0] = kmem_cache_alloc(req_cachep, gfp);
+		if (!state->reqs[0])
+			return NULL;
+		ret = 1;
+	}
+
+	for (i = 0; i < ret; i++)
+		io_preinit_req(state->reqs[i], ctx);
+	state->free_reqs = ret;
+got_req:
+	state->free_reqs--;
+	return state->reqs[state->free_reqs];
+}
+
+static inline void io_put_file(struct file *file)
+{
+	if (file)
+		fput(file);
+}
+
+static void io_dismantle_req(struct io_kiocb *req)
+{
+	unsigned int flags = req->flags;
+
+	if (io_req_needs_clean(req))
+		io_clean_op(req);
+	if (!(flags & REQ_F_FIXED_FILE))
+		io_put_file(req->file);
+	if (req->fixed_rsrc_refs)
+		percpu_ref_put(req->fixed_rsrc_refs);
+	if (req->async_data) {
+		kfree(req->async_data);
+		req->async_data = NULL;
+	}
+}
+
+static void __io_free_req(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	io_dismantle_req(req);
+	io_put_task(req->task, 1);
+
+	spin_lock(&ctx->completion_lock);
+	list_add(&req->inflight_entry, &ctx->locked_free_list);
+	ctx->locked_free_nr++;
+	spin_unlock(&ctx->completion_lock);
+
+	percpu_ref_put(&ctx->refs);
+}
+
+static inline void io_remove_next_linked(struct io_kiocb *req)
+{
+	struct io_kiocb *nxt = req->link;
+
+	req->link = nxt->link;
+	nxt->link = NULL;
+}
+
+static bool io_kill_linked_timeout(struct io_kiocb *req)
+	__must_hold(&req->ctx->completion_lock)
+	__must_hold(&req->ctx->timeout_lock)
+{
+	struct io_kiocb *link = req->link;
+
+	if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
+		struct io_timeout_data *io = link->async_data;
+
+		io_remove_next_linked(req);
+		link->timeout.head = NULL;
+		if (hrtimer_try_to_cancel(&io->timer) != -1) {
+			list_del(&link->timeout.list);
+			io_fill_cqe_req(link, -ECANCELED, 0);
+			io_put_req_deferred(link);
+			return true;
+		}
+	}
+	return false;
+}
+
+static void io_fail_links(struct io_kiocb *req)
+	__must_hold(&req->ctx->completion_lock)
+{
+	struct io_kiocb *nxt, *link = req->link;
+
+	req->link = NULL;
+	while (link) {
+		long res = -ECANCELED;
+
+		if (link->flags & REQ_F_FAIL)
+			res = link->result;
+
+		nxt = link->link;
+		link->link = NULL;
+
+		trace_io_uring_fail_link(req, link);
+		io_fill_cqe_req(link, res, 0);
+		io_put_req_deferred(link);
+		link = nxt;
+	}
+}
+
+static bool io_disarm_next(struct io_kiocb *req)
+	__must_hold(&req->ctx->completion_lock)
+{
+	bool posted = false;
+
+	if (req->flags & REQ_F_ARM_LTIMEOUT) {
+		struct io_kiocb *link = req->link;
+
+		req->flags &= ~REQ_F_ARM_LTIMEOUT;
+		if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
+			io_remove_next_linked(req);
+			io_fill_cqe_req(link, -ECANCELED, 0);
+			io_put_req_deferred(link);
+			posted = true;
+		}
+	} else if (req->flags & REQ_F_LINK_TIMEOUT) {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		spin_lock_irq(&ctx->timeout_lock);
+		posted = io_kill_linked_timeout(req);
+		spin_unlock_irq(&ctx->timeout_lock);
+	}
+	if (unlikely((req->flags & REQ_F_FAIL) &&
+		     !(req->flags & REQ_F_HARDLINK))) {
+		posted |= (req->link != NULL);
+		io_fail_links(req);
+	}
+	return posted;
+}
+
+static 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 (req->flags & IO_DISARM_MASK) {
+		struct io_ring_ctx *ctx = req->ctx;
+		bool posted;
+
+		spin_lock(&ctx->completion_lock);
+		posted = io_disarm_next(req);
+		if (posted)
+			io_commit_cqring(req->ctx);
+		spin_unlock(&ctx->completion_lock);
+		if (posted)
+			io_cqring_ev_posted(ctx);
+	}
+	nxt = req->link;
+	req->link = NULL;
+	return nxt;
+}
+
+static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
+{
+	if (likely(!(req->flags & (REQ_F_LINK|REQ_F_HARDLINK))))
+		return NULL;
+	return __io_req_find_next(req);
+}
+
+static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
+{
+	if (!ctx)
+		return;
+	if (*locked) {
+		if (ctx->submit_state.compl_nr)
+			io_submit_flush_completions(ctx);
+		mutex_unlock(&ctx->uring_lock);
+		*locked = false;
+	}
+	percpu_ref_put(&ctx->refs);
+}
+
+static void tctx_task_work(struct callback_head *cb)
+{
+	bool locked = false;
+	struct io_ring_ctx *ctx = NULL;
+	struct io_uring_task *tctx = container_of(cb, struct io_uring_task,
+						  task_work);
+
+	while (1) {
+		struct io_wq_work_node *node;
+
+		if (!tctx->task_list.first && locked && ctx->submit_state.compl_nr)
+			io_submit_flush_completions(ctx);
+
+		spin_lock_irq(&tctx->task_lock);
+		node = tctx->task_list.first;
+		INIT_WQ_LIST(&tctx->task_list);
+		if (!node)
+			tctx->task_running = false;
+		spin_unlock_irq(&tctx->task_lock);
+		if (!node)
+			break;
+
+		do {
+			struct io_wq_work_node *next = node->next;
+			struct io_kiocb *req = container_of(node, struct io_kiocb,
+							    io_task_work.node);
+
+			if (req->ctx != ctx) {
+				ctx_flush_and_put(ctx, &locked);
+				ctx = req->ctx;
+				/* if not contended, grab and improve batching */
+				locked = mutex_trylock(&ctx->uring_lock);
+				percpu_ref_get(&ctx->refs);
+			}
+			req->io_task_work.func(req, &locked);
+			node = next;
+			if (unlikely(need_resched())) {
+				ctx_flush_and_put(ctx, &locked);
+				ctx = NULL;
+				cond_resched();
+			}
+		} while (node);
+	}
+
+	ctx_flush_and_put(ctx, &locked);
+
+	/* relaxed read is enough as only the task itself sets ->in_idle */
+	if (unlikely(atomic_read(&tctx->in_idle)))
+		io_uring_drop_tctx_refs(current);
+}
+
+static void io_req_task_work_add(struct io_kiocb *req)
+{
+	struct task_struct *tsk = req->task;
+	struct io_uring_task *tctx = tsk->io_uring;
+	enum task_work_notify_mode notify;
+	struct io_wq_work_node *node;
+	unsigned long flags;
+	bool running;
+
+	WARN_ON_ONCE(!tctx);
+
+	spin_lock_irqsave(&tctx->task_lock, flags);
+	wq_list_add_tail(&req->io_task_work.node, &tctx->task_list);
+	running = tctx->task_running;
+	if (!running)
+		tctx->task_running = true;
+	spin_unlock_irqrestore(&tctx->task_lock, flags);
+
+	/* task_work already pending, we're done */
+	if (running)
+		return;
+
+	/*
+	 * SQPOLL kernel thread doesn't need notification, just a wakeup. For
+	 * all other cases, use TWA_SIGNAL unconditionally to ensure we're
+	 * processing task_work. There's no reliable way to tell if TWA_RESUME
+	 * will do the job.
+	 */
+	notify = (req->ctx->flags & IORING_SETUP_SQPOLL) ? TWA_NONE : TWA_SIGNAL;
+	if (!task_work_add(tsk, &tctx->task_work, notify)) {
+		wake_up_process(tsk);
+		return;
+	}
+
+	spin_lock_irqsave(&tctx->task_lock, flags);
+	tctx->task_running = false;
+	node = tctx->task_list.first;
+	INIT_WQ_LIST(&tctx->task_list);
+	spin_unlock_irqrestore(&tctx->task_lock, flags);
+
+	while (node) {
+		req = container_of(node, struct io_kiocb, io_task_work.node);
+		node = node->next;
+		if (llist_add(&req->io_task_work.fallback_node,
+			      &req->ctx->fallback_llist))
+			schedule_delayed_work(&req->ctx->fallback_work, 1);
+	}
+}
+
+static void io_req_task_cancel(struct io_kiocb *req, bool *locked)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	/* not needed for normal modes, but SQPOLL depends on it */
+	io_tw_lock(ctx, locked);
+	io_req_complete_failed(req, req->result);
+}
+
+static void io_req_task_submit(struct io_kiocb *req, bool *locked)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	io_tw_lock(ctx, locked);
+	/* req->task == current here, checking PF_EXITING is safe */
+	if (likely(!(req->task->flags & PF_EXITING)))
+		__io_queue_sqe(req);
+	else
+		io_req_complete_failed(req, -EFAULT);
+}
+
+static void io_req_task_queue_fail(struct io_kiocb *req, int ret)
+{
+	req->result = ret;
+	req->io_task_work.func = io_req_task_cancel;
+	io_req_task_work_add(req);
+}
+
+static void io_req_task_queue(struct io_kiocb *req)
+{
+	req->io_task_work.func = io_req_task_submit;
+	io_req_task_work_add(req);
+}
+
+static void io_req_task_queue_reissue(struct io_kiocb *req)
+{
+	req->io_task_work.func = io_queue_async_work;
+	io_req_task_work_add(req);
+}
+
+static inline 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_req(struct io_kiocb *req)
+{
+	io_queue_next(req);
+	__io_free_req(req);
+}
+
+static void io_free_req_work(struct io_kiocb *req, bool *locked)
+{
+	io_free_req(req);
+}
+
+struct req_batch {
+	struct task_struct	*task;
+	int			task_refs;
+	int			ctx_refs;
+};
+
+static inline void io_init_req_batch(struct req_batch *rb)
+{
+	rb->task_refs = 0;
+	rb->ctx_refs = 0;
+	rb->task = NULL;
+}
+
+static void io_req_free_batch_finish(struct io_ring_ctx *ctx,
+				     struct req_batch *rb)
+{
+	if (rb->ctx_refs)
+		percpu_ref_put_many(&ctx->refs, rb->ctx_refs);
+	if (rb->task)
+		io_put_task(rb->task, rb->task_refs);
+}
+
+static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req,
+			      struct io_submit_state *state)
+{
+	io_queue_next(req);
+	io_dismantle_req(req);
+
+	if (req->task != rb->task) {
+		if (rb->task)
+			io_put_task(rb->task, rb->task_refs);
+		rb->task = req->task;
+		rb->task_refs = 0;
+	}
+	rb->task_refs++;
+	rb->ctx_refs++;
+
+	if (state->free_reqs != ARRAY_SIZE(state->reqs))
+		state->reqs[state->free_reqs++] = req;
+	else
+		list_add(&req->inflight_entry, &state->free_list);
+}
+
+static void io_submit_flush_completions(struct io_ring_ctx *ctx)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+	int i, nr = state->compl_nr;
+	struct req_batch rb;
+
+	spin_lock(&ctx->completion_lock);
+	for (i = 0; i < nr; i++) {
+		struct io_kiocb *req = state->compl_reqs[i];
+
+		__io_fill_cqe(ctx, req->user_data, req->result,
+			      req->compl.cflags);
+	}
+	io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+	io_cqring_ev_posted(ctx);
+
+	io_init_req_batch(&rb);
+	for (i = 0; i < nr; i++) {
+		struct io_kiocb *req = state->compl_reqs[i];
+
+		if (req_ref_put_and_test(req))
+			io_req_free_batch(&rb, req, &ctx->submit_state);
+	}
+
+	io_req_free_batch_finish(ctx, &rb);
+	state->compl_nr = 0;
+}
+
+/*
+ * Drop reference to request, return next in chain (if there is one) if this
+ * was the last reference to this request.
+ */
+static inline struct io_kiocb *io_put_req_find_next(struct io_kiocb *req)
+{
+	struct io_kiocb *nxt = NULL;
+
+	if (req_ref_put_and_test(req)) {
+		nxt = io_req_find_next(req);
+		__io_free_req(req);
+	}
+	return nxt;
+}
+
+static inline void io_put_req(struct io_kiocb *req)
+{
+	if (req_ref_put_and_test(req))
+		io_free_req(req);
+}
+
+static inline void io_put_req_deferred(struct io_kiocb *req)
+{
+	if (req_ref_put_and_test(req)) {
+		req->io_task_work.func = io_free_req_work;
+		io_req_task_work_add(req);
+	}
+}
+
+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);
+}
+
+static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
+{
+	struct io_rings *rings = ctx->rings;
+
+	/* make sure SQ entry isn't read before tail */
+	return smp_load_acquire(&rings->sq.tail) - ctx->cached_sq_head;
+}
+
+static unsigned int io_put_kbuf(struct io_kiocb *req, struct io_buffer *kbuf)
+{
+	unsigned int cflags;
+
+	cflags = kbuf->bid << IORING_CQE_BUFFER_SHIFT;
+	cflags |= IORING_CQE_F_BUFFER;
+	req->flags &= ~REQ_F_BUFFER_SELECTED;
+	kfree(kbuf);
+	return cflags;
+}
+
+static inline unsigned int io_put_rw_kbuf(struct io_kiocb *req)
+{
+	struct io_buffer *kbuf;
+
+	if (likely(!(req->flags & REQ_F_BUFFER_SELECTED)))
+		return 0;
+	kbuf = (struct io_buffer *) (unsigned long) req->rw.addr;
+	return io_put_kbuf(req, kbuf);
+}
+
+static inline bool io_run_task_work(void)
+{
+	/*
+	 * PF_IO_WORKER never returns to userspace, so check here if we have
+	 * notify work that needs processing.
+	 */
+	if (current->flags & PF_IO_WORKER &&
+	    test_thread_flag(TIF_NOTIFY_RESUME)) {
+		__set_current_state(TASK_RUNNING);
+		tracehook_notify_resume(NULL);
+	}
+	if (test_thread_flag(TIF_NOTIFY_SIGNAL) || current->task_works) {
+		__set_current_state(TASK_RUNNING);
+		tracehook_notify_signal();
+		return true;
+	}
+
+	return false;
+}
+
+/*
+ * Find and free completed poll iocbs
+ */
+static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
+			       struct list_head *done)
+{
+	struct req_batch rb;
+	struct io_kiocb *req;
+
+	/* order with ->result store in io_complete_rw_iopoll() */
+	smp_rmb();
+
+	io_init_req_batch(&rb);
+	while (!list_empty(done)) {
+		struct io_uring_cqe *cqe;
+		unsigned cflags;
+
+		req = list_first_entry(done, struct io_kiocb, inflight_entry);
+		list_del(&req->inflight_entry);
+		cflags = io_put_rw_kbuf(req);
+		(*nr_events)++;
+
+		cqe = io_get_cqe(ctx);
+		if (cqe) {
+			WRITE_ONCE(cqe->user_data, req->user_data);
+			WRITE_ONCE(cqe->res, req->result);
+			WRITE_ONCE(cqe->flags, cflags);
+		} else {
+			spin_lock(&ctx->completion_lock);
+			io_cqring_event_overflow(ctx, req->user_data,
+							req->result, cflags);
+			spin_unlock(&ctx->completion_lock);
+		}
+
+		if (req_ref_put_and_test(req))
+			io_req_free_batch(&rb, req, &ctx->submit_state);
+	}
+
+	if (io_commit_needs_flush(ctx)) {
+		spin_lock(&ctx->completion_lock);
+		__io_commit_cqring_flush(ctx);
+		spin_unlock(&ctx->completion_lock);
+	}
+	__io_commit_cqring(ctx);
+	io_cqring_ev_posted_iopoll(ctx);
+	io_req_free_batch_finish(ctx, &rb);
+}
+
+static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
+			long min)
+{
+	struct io_kiocb *req, *tmp;
+	LIST_HEAD(done);
+	bool spin;
+
+	/*
+	 * Only spin for completions if we don't have multiple devices hanging
+	 * off our complete list, and we're under the requested amount.
+	 */
+	spin = !ctx->poll_multi_queue && *nr_events < min;
+
+	list_for_each_entry_safe(req, tmp, &ctx->iopoll_list, inflight_entry) {
+		struct kiocb *kiocb = &req->rw.kiocb;
+		int ret;
+
+		/*
+		 * Move completed and retryable entries to our local lists.
+		 * If we find a request that requires polling, break out
+		 * and complete those lists first, if we have entries there.
+		 */
+		if (READ_ONCE(req->iopoll_completed)) {
+			list_move_tail(&req->inflight_entry, &done);
+			continue;
+		}
+		if (!list_empty(&done))
+			break;
+
+		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
+		if (unlikely(ret < 0))
+			return ret;
+		else if (ret)
+			spin = false;
+
+		/* iopoll may have completed current req */
+		if (READ_ONCE(req->iopoll_completed))
+			list_move_tail(&req->inflight_entry, &done);
+	}
+
+	if (!list_empty(&done))
+		io_iopoll_complete(ctx, nr_events, &done);
+
+	return 0;
+}
+
+/*
+ * We can't just wait for polled events to come to us, we have to actively
+ * find and complete them.
+ */
+static void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
+{
+	if (!(ctx->flags & IORING_SETUP_IOPOLL))
+		return;
+
+	mutex_lock(&ctx->uring_lock);
+	while (!list_empty(&ctx->iopoll_list)) {
+		unsigned int nr_events = 0;
+
+		io_do_iopoll(ctx, &nr_events, 0);
+
+		/* let it sleep and repeat later if can't complete a request */
+		if (nr_events == 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;
+	int ret = 0;
+
+	/*
+	 * 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);
+	/*
+	 * 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 (test_bit(0, &ctx->check_cq_overflow))
+		__io_cqring_overflow_flush(ctx, false);
+	if (io_cqring_events(ctx))
+		goto out;
+	do {
+		/*
+		 * 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 (list_empty(&ctx->iopoll_list)) {
+			u32 tail = ctx->cached_cq_tail;
+
+			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 ||
+			    list_empty(&ctx->iopoll_list))
+				break;
+		}
+		ret = io_do_iopoll(ctx, &nr_events, min);
+
+		if (task_sigpending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
+	} while (!ret && nr_events < min && !need_resched());
+out:
+	mutex_unlock(&ctx->uring_lock);
+	return ret;
+}
+
+static void kiocb_end_write(struct io_kiocb *req)
+{
+	/*
+	 * Tell lockdep we inherited freeze protection from submission
+	 * thread.
+	 */
+	if (req->flags & REQ_F_ISREG) {
+		struct super_block *sb = file_inode(req->file)->i_sb;
+
+		__sb_writers_acquired(sb, SB_FREEZE_WRITE);
+		sb_end_write(sb);
+	}
+}
+
+#ifdef CONFIG_BLOCK
+static bool io_resubmit_prep(struct io_kiocb *req)
+{
+	struct io_async_rw *rw = req->async_data;
+
+	if (!rw)
+		return !io_req_prep_async(req);
+	iov_iter_restore(&rw->iter, &rw->iter_state);
+	return true;
+}
+
+static bool io_rw_should_reissue(struct io_kiocb *req)
+{
+	umode_t mode = file_inode(req->file)->i_mode;
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (!S_ISBLK(mode) && !S_ISREG(mode))
+		return false;
+	if ((req->flags & REQ_F_NOWAIT) || (io_wq_current_is_worker() &&
+	    !(ctx->flags & IORING_SETUP_IOPOLL)))
+		return false;
+	/*
+	 * If ref is dying, we might be running poll reap from the exit work.
+	 * Don't attempt to reissue from that path, just let it fail with
+	 * -EAGAIN.
+	 */
+	if (percpu_ref_is_dying(&ctx->refs))
+		return false;
+	/*
+	 * Play it safe and assume not safe to re-import and reissue if we're
+	 * not in the original thread group (or in task context).
+	 */
+	if (!same_thread_group(req->task, current) || !in_task())
+		return false;
+	return true;
+}
+#else
+static bool io_resubmit_prep(struct io_kiocb *req)
+{
+	return false;
+}
+static bool io_rw_should_reissue(struct io_kiocb *req)
+{
+	return false;
+}
+#endif
+
+/*
+ * Trigger the notifications after having done some IO, and finish the write
+ * accounting, if any.
+ */
+static void io_req_io_end(struct io_kiocb *req)
+{
+	struct io_rw *rw = &req->rw;
+
+	if (rw->kiocb.ki_flags & IOCB_WRITE) {
+		kiocb_end_write(req);
+		fsnotify_modify(req->file);
+	} else {
+		fsnotify_access(req->file);
+	}
+}
+
+static bool __io_complete_rw_common(struct io_kiocb *req, long res)
+{
+	if (res != req->result) {
+		if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
+		    io_rw_should_reissue(req)) {
+			/*
+			 * Reissue will start accounting again, finish the
+			 * current cycle.
+			 */
+			io_req_io_end(req);
+			req->flags |= REQ_F_REISSUE;
+			return true;
+		}
+		req_set_fail(req);
+		req->result = res;
+	}
+	return false;
+}
+
+static inline int io_fixup_rw_res(struct io_kiocb *req, long res)
+{
+	struct io_async_rw *io = req->async_data;
+
+	/* add previously done IO, if any */
+	if (io && io->bytes_done > 0) {
+		if (res < 0)
+			res = io->bytes_done;
+		else
+			res += io->bytes_done;
+	}
+	return res;
+}
+
+static void io_req_task_complete(struct io_kiocb *req, bool *locked)
+{
+	unsigned int cflags = io_put_rw_kbuf(req);
+	int res = req->result;
+
+	if (*locked) {
+		struct io_ring_ctx *ctx = req->ctx;
+		struct io_submit_state *state = &ctx->submit_state;
+
+		io_req_complete_state(req, res, cflags);
+		state->compl_reqs[state->compl_nr++] = req;
+		if (state->compl_nr == ARRAY_SIZE(state->compl_reqs))
+			io_submit_flush_completions(ctx);
+	} else {
+		io_req_complete_post(req, res, cflags);
+	}
+}
+
+static void io_req_rw_complete(struct io_kiocb *req, bool *locked)
+{
+	io_req_io_end(req);
+	io_req_task_complete(req, locked);
+}
+
+static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
+{
+	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
+
+	if (__io_complete_rw_common(req, res))
+		return;
+	req->result = io_fixup_rw_res(req, res);
+	req->io_task_work.func = io_req_rw_complete;
+	io_req_task_work_add(req);
+}
+
+static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
+{
+	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
+
+	if (kiocb->ki_flags & IOCB_WRITE)
+		kiocb_end_write(req);
+	if (unlikely(res != req->result)) {
+		if (res == -EAGAIN && io_rw_should_reissue(req)) {
+			req->flags |= REQ_F_REISSUE;
+			return;
+		}
+	}
+
+	WRITE_ONCE(req->result, res);
+	/* order with io_iopoll_complete() checking ->result */
+	smp_wmb();
+	WRITE_ONCE(req->iopoll_completed, 1);
+}
+
+/*
+ * 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)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	const bool in_async = io_wq_current_is_worker();
+
+	/* workqueue context doesn't hold uring_lock, grab it now */
+	if (unlikely(in_async))
+		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 (list_empty(&ctx->iopoll_list)) {
+		ctx->poll_multi_queue = false;
+	} else if (!ctx->poll_multi_queue) {
+		struct io_kiocb *list_req;
+		unsigned int queue_num0, queue_num1;
+
+		list_req = list_first_entry(&ctx->iopoll_list, struct io_kiocb,
+						inflight_entry);
+
+		if (list_req->file != req->file) {
+			ctx->poll_multi_queue = true;
+		} else {
+			queue_num0 = blk_qc_t_to_queue_num(list_req->rw.kiocb.ki_cookie);
+			queue_num1 = blk_qc_t_to_queue_num(req->rw.kiocb.ki_cookie);
+			if (queue_num0 != queue_num1)
+				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))
+		list_add(&req->inflight_entry, &ctx->iopoll_list);
+	else
+		list_add_tail(&req->inflight_entry, &ctx->iopoll_list);
+
+	if (unlikely(in_async)) {
+		/*
+		 * 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);
+	}
+}
+
+static bool io_bdev_nowait(struct block_device *bdev)
+{
+	return !bdev || blk_queue_nowait(bdev_get_queue(bdev));
+}
+
+/*
+ * If we tracked the file through the SCM inflight mechanism, we could support
+ * any file. For now, just ensure that anything potentially problematic is done
+ * inline.
+ */
+static bool __io_file_supports_nowait(struct file *file, int rw)
+{
+	umode_t mode = file_inode(file)->i_mode;
+
+	if (S_ISBLK(mode)) {
+		if (IS_ENABLED(CONFIG_BLOCK) &&
+		    io_bdev_nowait(I_BDEV(file->f_mapping->host)))
+			return true;
+		return false;
+	}
+	if (S_ISSOCK(mode))
+		return true;
+	if (S_ISREG(mode)) {
+		if (IS_ENABLED(CONFIG_BLOCK) &&
+		    io_bdev_nowait(file->f_inode->i_sb->s_bdev) &&
+		    file->f_op != &io_uring_fops)
+			return true;
+		return false;
+	}
+
+	/* any ->read/write should understand O_NONBLOCK */
+	if (file->f_flags & O_NONBLOCK)
+		return true;
+
+	if (!(file->f_mode & FMODE_NOWAIT))
+		return false;
+
+	if (rw == READ)
+		return file->f_op->read_iter != NULL;
+
+	return file->f_op->write_iter != NULL;
+}
+
+static bool io_file_supports_nowait(struct io_kiocb *req, int rw)
+{
+	if (rw == READ && (req->flags & REQ_F_NOWAIT_READ))
+		return true;
+	else if (rw == WRITE && (req->flags & REQ_F_NOWAIT_WRITE))
+		return true;
+
+	return __io_file_supports_nowait(req->file, rw);
+}
+
+static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+		      int rw)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct kiocb *kiocb = &req->rw.kiocb;
+	struct file *file = req->file;
+	unsigned ioprio;
+	int ret;
+
+	if (!io_req_ffs_set(req) && S_ISREG(file_inode(file)->i_mode))
+		req->flags |= REQ_F_ISREG;
+
+	kiocb->ki_pos = READ_ONCE(sqe->off);
+	kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
+	kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
+	ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
+	if (unlikely(ret))
+		return ret;
+
+	/*
+	 * If the file is marked O_NONBLOCK, still allow retry for it if it
+	 * supports async. Otherwise it's impossible to use O_NONBLOCK files
+	 * reliably. If not, or it IOCB_NOWAIT is set, don't retry.
+	 */
+	if ((kiocb->ki_flags & IOCB_NOWAIT) ||
+	    ((file->f_flags & O_NONBLOCK) && !io_file_supports_nowait(req, rw)))
+		req->flags |= REQ_F_NOWAIT;
+
+	ioprio = READ_ONCE(sqe->ioprio);
+	if (ioprio) {
+		ret = ioprio_check_cap(ioprio);
+		if (ret)
+			return ret;
+
+		kiocb->ki_ioprio = ioprio;
+	} else
+		kiocb->ki_ioprio = get_current_ioprio();
+
+	if (ctx->flags & IORING_SETUP_IOPOLL) {
+		if (!(kiocb->ki_flags & IOCB_DIRECT) ||
+		    !kiocb->ki_filp->f_op->iopoll)
+			return -EOPNOTSUPP;
+
+		kiocb->ki_flags |= IOCB_HIPRI;
+		kiocb->ki_complete = io_complete_rw_iopoll;
+		req->iopoll_completed = 0;
+	} else {
+		if (kiocb->ki_flags & IOCB_HIPRI)
+			return -EINVAL;
+		kiocb->ki_complete = io_complete_rw;
+	}
+
+	/* used for fixed read/write too - just read unconditionally */
+	req->buf_index = READ_ONCE(sqe->buf_index);
+	req->imu = NULL;
+
+	if (req->opcode == IORING_OP_READ_FIXED ||
+	    req->opcode == IORING_OP_WRITE_FIXED) {
+		struct io_ring_ctx *ctx = req->ctx;
+		u16 index;
+
+		if (unlikely(req->buf_index >= ctx->nr_user_bufs))
+			return -EFAULT;
+		index = array_index_nospec(req->buf_index, ctx->nr_user_bufs);
+		req->imu = ctx->user_bufs[index];
+		io_req_set_rsrc_node(req);
+	}
+
+	req->rw.addr = READ_ONCE(sqe->addr);
+	req->rw.len = READ_ONCE(sqe->len);
+	return 0;
+}
+
+static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
+{
+	switch (ret) {
+	case -EIOCBQUEUED:
+		break;
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/*
+		 * We can't just restart the syscall, since previously
+		 * submitted sqes may already be in progress. Just fail this
+		 * IO with EINTR.
+		 */
+		ret = -EINTR;
+		fallthrough;
+	default:
+		kiocb->ki_complete(kiocb, ret, 0);
+	}
+}
+
+static inline loff_t *io_kiocb_update_pos(struct io_kiocb *req)
+{
+	struct kiocb *kiocb = &req->rw.kiocb;
+
+	if (kiocb->ki_pos != -1)
+		return &kiocb->ki_pos;
+
+	if (!(req->file->f_mode & FMODE_STREAM)) {
+		req->flags |= REQ_F_CUR_POS;
+		kiocb->ki_pos = req->file->f_pos;
+		return &kiocb->ki_pos;
+	}
+
+	kiocb->ki_pos = 0;
+	return NULL;
+}
+
+static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
+		       unsigned int issue_flags)
+{
+	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
+
+	if (req->flags & REQ_F_CUR_POS)
+		req->file->f_pos = kiocb->ki_pos;
+	if (ret >= 0 && (kiocb->ki_complete == io_complete_rw)) {
+		if (!__io_complete_rw_common(req, ret)) {
+			/*
+			 * Safe to call io_end from here as we're inline
+			 * from the submission path.
+			 */
+			io_req_io_end(req);
+			__io_req_complete(req, issue_flags,
+					  io_fixup_rw_res(req, ret),
+					  io_put_rw_kbuf(req));
+		}
+	} else {
+		io_rw_done(kiocb, ret);
+	}
+
+	if (req->flags & REQ_F_REISSUE) {
+		req->flags &= ~REQ_F_REISSUE;
+		if (io_resubmit_prep(req)) {
+			io_req_task_queue_reissue(req);
+		} else {
+			unsigned int cflags = io_put_rw_kbuf(req);
+			struct io_ring_ctx *ctx = req->ctx;
+
+			ret = io_fixup_rw_res(req, ret);
+			req_set_fail(req);
+			if (!(issue_flags & IO_URING_F_NONBLOCK)) {
+				mutex_lock(&ctx->uring_lock);
+				__io_req_complete(req, issue_flags, ret, cflags);
+				mutex_unlock(&ctx->uring_lock);
+			} else {
+				__io_req_complete(req, issue_flags, ret, cflags);
+			}
+		}
+	}
+}
+
+static int __io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter,
+			     struct io_mapped_ubuf *imu)
+{
+	size_t len = req->rw.len;
+	u64 buf_end, buf_addr = req->rw.addr;
+	size_t offset;
+
+	if (unlikely(check_add_overflow(buf_addr, (u64)len, &buf_end)))
+		return -EFAULT;
+	/* not inside the mapped region */
+	if (unlikely(buf_addr < imu->ubuf || buf_end > imu->ubuf_end))
+		return -EFAULT;
+
+	/*
+	 * May not be a start of buffer, set size appropriately
+	 * and advance us to the beginning.
+	 */
+	offset = buf_addr - imu->ubuf;
+	iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
+
+	if (offset) {
+		/*
+		 * Don't use iov_iter_advance() here, as it's really slow for
+		 * using the latter parts of a big fixed buffer - it iterates
+		 * over each segment manually. We can cheat a bit here, because
+		 * we know that:
+		 *
+		 * 1) it's a BVEC iter, we set it up
+		 * 2) all bvecs are PAGE_SIZE in size, except potentially the
+		 *    first and last bvec
+		 *
+		 * So just find our index, and adjust the iterator afterwards.
+		 * If the offset is within the first bvec (or the whole first
+		 * bvec, just use iov_iter_advance(). This makes it easier
+		 * since we can just skip the first segment, which may not
+		 * be PAGE_SIZE aligned.
+		 */
+		const struct bio_vec *bvec = imu->bvec;
+
+		if (offset < bvec->bv_len) {
+			iov_iter_advance(iter, offset);
+		} else {
+			unsigned long seg_skip;
+
+			/* skip first vec */
+			offset -= bvec->bv_len;
+			seg_skip = 1 + (offset >> PAGE_SHIFT);
+
+			iter->bvec = bvec + seg_skip;
+			iter->nr_segs -= seg_skip;
+			iter->count -= bvec->bv_len + offset;
+			iter->iov_offset = offset & ~PAGE_MASK;
+		}
+	}
+
+	return 0;
+}
+
+static int io_import_fixed(struct io_kiocb *req, int rw, struct iov_iter *iter)
+{
+	if (WARN_ON_ONCE(!req->imu))
+		return -EFAULT;
+	return __io_import_fixed(req, rw, iter, req->imu);
+}
+
+static void io_ring_submit_unlock(struct io_ring_ctx *ctx, bool needs_lock)
+{
+	if (needs_lock)
+		mutex_unlock(&ctx->uring_lock);
+}
+
+static void io_ring_submit_lock(struct io_ring_ctx *ctx, bool needs_lock)
+{
+	/*
+	 * "Normal" inline submissions always hold the uring_lock, since we
+	 * grab it from the system call. Same is true for the SQPOLL offload.
+	 * The only exception is when we've detached the request and issue it
+	 * from an async worker thread, grab the lock for that case.
+	 */
+	if (needs_lock)
+		mutex_lock(&ctx->uring_lock);
+}
+
+static struct io_buffer *io_buffer_select(struct io_kiocb *req, size_t *len,
+					  int bgid, struct io_buffer *kbuf,
+					  bool needs_lock)
+{
+	struct io_buffer *head;
+
+	if (req->flags & REQ_F_BUFFER_SELECTED)
+		return kbuf;
+
+	io_ring_submit_lock(req->ctx, needs_lock);
+
+	lockdep_assert_held(&req->ctx->uring_lock);
+
+	head = xa_load(&req->ctx->io_buffers, bgid);
+	if (head) {
+		if (!list_empty(&head->list)) {
+			kbuf = list_last_entry(&head->list, struct io_buffer,
+							list);
+			list_del(&kbuf->list);
+		} else {
+			kbuf = head;
+			xa_erase(&req->ctx->io_buffers, bgid);
+		}
+		if (*len > kbuf->len)
+			*len = kbuf->len;
+	} else {
+		kbuf = ERR_PTR(-ENOBUFS);
+	}
+
+	io_ring_submit_unlock(req->ctx, needs_lock);
+
+	return kbuf;
+}
+
+static void __user *io_rw_buffer_select(struct io_kiocb *req, size_t *len,
+					bool needs_lock)
+{
+	struct io_buffer *kbuf;
+	u16 bgid;
+
+	kbuf = (struct io_buffer *) (unsigned long) req->rw.addr;
+	bgid = req->buf_index;
+	kbuf = io_buffer_select(req, len, bgid, kbuf, needs_lock);
+	if (IS_ERR(kbuf))
+		return kbuf;
+	req->rw.addr = (u64) (unsigned long) kbuf;
+	req->flags |= REQ_F_BUFFER_SELECTED;
+	return u64_to_user_ptr(kbuf->addr);
+}
+
+#ifdef CONFIG_COMPAT
+static ssize_t io_compat_import(struct io_kiocb *req, struct iovec *iov,
+				bool needs_lock)
+{
+	struct compat_iovec __user *uiov;
+	compat_ssize_t clen;
+	void __user *buf;
+	ssize_t len;
+
+	uiov = u64_to_user_ptr(req->rw.addr);
+	if (!access_ok(uiov, sizeof(*uiov)))
+		return -EFAULT;
+	if (__get_user(clen, &uiov->iov_len))
+		return -EFAULT;
+	if (clen < 0)
+		return -EINVAL;
+
+	len = clen;
+	buf = io_rw_buffer_select(req, &len, needs_lock);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+	iov[0].iov_base = buf;
+	iov[0].iov_len = (compat_size_t) len;
+	return 0;
+}
+#endif
+
+static ssize_t __io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
+				      bool needs_lock)
+{
+	struct iovec __user *uiov = u64_to_user_ptr(req->rw.addr);
+	void __user *buf;
+	ssize_t len;
+
+	if (copy_from_user(iov, uiov, sizeof(*uiov)))
+		return -EFAULT;
+
+	len = iov[0].iov_len;
+	if (len < 0)
+		return -EINVAL;
+	buf = io_rw_buffer_select(req, &len, needs_lock);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+	iov[0].iov_base = buf;
+	iov[0].iov_len = len;
+	return 0;
+}
+
+static ssize_t io_iov_buffer_select(struct io_kiocb *req, struct iovec *iov,
+				    bool needs_lock)
+{
+	if (req->flags & REQ_F_BUFFER_SELECTED) {
+		struct io_buffer *kbuf;
+
+		kbuf = (struct io_buffer *) (unsigned long) req->rw.addr;
+		iov[0].iov_base = u64_to_user_ptr(kbuf->addr);
+		iov[0].iov_len = kbuf->len;
+		return 0;
+	}
+	if (req->rw.len != 1)
+		return -EINVAL;
+
+#ifdef CONFIG_COMPAT
+	if (req->ctx->compat)
+		return io_compat_import(req, iov, needs_lock);
+#endif
+
+	return __io_iov_buffer_select(req, iov, needs_lock);
+}
+
+static int io_import_iovec(int rw, struct io_kiocb *req, struct iovec **iovec,
+			   struct iov_iter *iter, bool needs_lock)
+{
+	void __user *buf = u64_to_user_ptr(req->rw.addr);
+	size_t sqe_len = req->rw.len;
+	u8 opcode = req->opcode;
+	ssize_t ret;
+
+	if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
+		*iovec = NULL;
+		return io_import_fixed(req, rw, iter);
+	}
+
+	/* buffer index only valid with fixed read/write, or buffer select  */
+	if (req->buf_index && !(req->flags & REQ_F_BUFFER_SELECT))
+		return -EINVAL;
+
+	if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE) {
+		if (req->flags & REQ_F_BUFFER_SELECT) {
+			buf = io_rw_buffer_select(req, &sqe_len, needs_lock);
+			if (IS_ERR(buf))
+				return PTR_ERR(buf);
+			req->rw.len = sqe_len;
+		}
+
+		ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
+		*iovec = NULL;
+		return ret;
+	}
+
+	if (req->flags & REQ_F_BUFFER_SELECT) {
+		ret = io_iov_buffer_select(req, *iovec, needs_lock);
+		if (!ret)
+			iov_iter_init(iter, rw, *iovec, 1, (*iovec)->iov_len);
+		*iovec = NULL;
+		return ret;
+	}
+
+	return __import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter,
+			      req->ctx->compat);
+}
+
+static inline loff_t *io_kiocb_ppos(struct kiocb *kiocb)
+{
+	return (kiocb->ki_filp->f_mode & FMODE_STREAM) ? NULL : &kiocb->ki_pos;
+}
+
+/*
+ * For files that don't have ->read_iter() and ->write_iter(), handle them
+ * by looping over ->read() or ->write() manually.
+ */
+static ssize_t loop_rw_iter(int rw, struct io_kiocb *req, struct iov_iter *iter)
+{
+	struct kiocb *kiocb = &req->rw.kiocb;
+	struct file *file = req->file;
+	ssize_t ret = 0;
+	loff_t *ppos;
+
+	/*
+	 * Don't support polled IO through this interface, and we can't
+	 * support non-blocking either. For the latter, this just causes
+	 * the kiocb to be handled from an async context.
+	 */
+	if (kiocb->ki_flags & IOCB_HIPRI)
+		return -EOPNOTSUPP;
+	if (kiocb->ki_flags & IOCB_NOWAIT)
+		return -EAGAIN;
+
+	ppos = io_kiocb_ppos(kiocb);
+
+	while (iov_iter_count(iter)) {
+		struct iovec iovec;
+		ssize_t nr;
+
+		if (!iov_iter_is_bvec(iter)) {
+			iovec = iov_iter_iovec(iter);
+		} else {
+			iovec.iov_base = u64_to_user_ptr(req->rw.addr);
+			iovec.iov_len = req->rw.len;
+		}
+
+		if (rw == READ) {
+			nr = file->f_op->read(file, iovec.iov_base,
+					      iovec.iov_len, ppos);
+		} else {
+			nr = file->f_op->write(file, iovec.iov_base,
+					       iovec.iov_len, ppos);
+		}
+
+		if (nr < 0) {
+			if (!ret)
+				ret = nr;
+			break;
+		}
+		ret += nr;
+		if (!iov_iter_is_bvec(iter)) {
+			iov_iter_advance(iter, nr);
+		} else {
+			req->rw.addr += nr;
+			req->rw.len -= nr;
+			if (!req->rw.len)
+				break;
+		}
+		if (nr != iovec.iov_len)
+			break;
+	}
+
+	return ret;
+}
+
+static void io_req_map_rw(struct io_kiocb *req, const struct iovec *iovec,
+			  const struct iovec *fast_iov, struct iov_iter *iter)
+{
+	struct io_async_rw *rw = req->async_data;
+
+	memcpy(&rw->iter, iter, sizeof(*iter));
+	rw->free_iovec = iovec;
+	rw->bytes_done = 0;
+	/* can only be fixed buffers, no need to do anything */
+	if (iov_iter_is_bvec(iter))
+		return;
+	if (!iovec) {
+		unsigned iov_off = 0;
+
+		rw->iter.iov = rw->fast_iov;
+		if (iter->iov != fast_iov) {
+			iov_off = iter->iov - fast_iov;
+			rw->iter.iov += iov_off;
+		}
+		if (rw->fast_iov != fast_iov)
+			memcpy(rw->fast_iov + iov_off, fast_iov + iov_off,
+			       sizeof(struct iovec) * iter->nr_segs);
+	} else {
+		req->flags |= REQ_F_NEED_CLEANUP;
+	}
+}
+
+static inline int io_alloc_async_data(struct io_kiocb *req)
+{
+	WARN_ON_ONCE(!io_op_defs[req->opcode].async_size);
+	req->async_data = kmalloc(io_op_defs[req->opcode].async_size, GFP_KERNEL);
+	return req->async_data == NULL;
+}
+
+static int io_setup_async_rw(struct io_kiocb *req, const struct iovec *iovec,
+			     const struct iovec *fast_iov,
+			     struct iov_iter *iter, bool force)
+{
+	if (!force && !io_op_defs[req->opcode].needs_async_setup)
+		return 0;
+	if (!req->async_data) {
+		struct io_async_rw *iorw;
+
+		if (io_alloc_async_data(req)) {
+			kfree(iovec);
+			return -ENOMEM;
+		}
+
+		io_req_map_rw(req, iovec, fast_iov, iter);
+		iorw = req->async_data;
+		/* we've copied and mapped the iter, ensure state is saved */
+		iov_iter_save_state(&iorw->iter, &iorw->iter_state);
+	}
+	return 0;
+}
+
+static inline int io_rw_prep_async(struct io_kiocb *req, int rw)
+{
+	struct io_async_rw *iorw = req->async_data;
+	struct iovec *iov = iorw->fast_iov;
+	int ret;
+
+	iorw->bytes_done = 0;
+	iorw->free_iovec = NULL;
+
+	ret = io_import_iovec(rw, req, &iov, &iorw->iter, false);
+	if (unlikely(ret < 0))
+		return ret;
+
+	if (iov) {
+		iorw->free_iovec = iov;
+		req->flags |= REQ_F_NEED_CLEANUP;
+	}
+	iov_iter_save_state(&iorw->iter, &iorw->iter_state);
+	return 0;
+}
+
+static int io_read_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	if (unlikely(!(req->file->f_mode & FMODE_READ)))
+		return -EBADF;
+	return io_prep_rw(req, sqe, READ);
+}
+
+/*
+ * This is our waitqueue callback handler, registered through lock_page_async()
+ * when we initially tried to do the IO with the iocb armed our waitqueue.
+ * This gets called when the page is unlocked, and we generally expect that to
+ * happen when the page IO is completed and the page is now uptodate. This will
+ * queue a task_work based retry of the operation, attempting to copy the data
+ * again. If the latter fails because the page was NOT uptodate, then we will
+ * do a thread based blocking retry of the operation. That's the unexpected
+ * slow path.
+ */
+static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
+			     int sync, void *arg)
+{
+	struct wait_page_queue *wpq;
+	struct io_kiocb *req = wait->private;
+	struct wait_page_key *key = arg;
+
+	wpq = container_of(wait, struct wait_page_queue, wait);
+
+	if (!wake_page_match(wpq, key))
+		return 0;
+
+	req->rw.kiocb.ki_flags &= ~IOCB_WAITQ;
+	list_del_init(&wait->entry);
+	io_req_task_queue(req);
+	return 1;
+}
+
+/*
+ * This controls whether a given IO request should be armed for async page
+ * based retry. If we return false here, the request is handed to the async
+ * worker threads for retry. If we're doing buffered reads on a regular file,
+ * we prepare a private wait_page_queue entry and retry the operation. This
+ * will either succeed because the page is now uptodate and unlocked, or it
+ * will register a callback when the page is unlocked at IO completion. Through
+ * that callback, io_uring uses task_work to setup a retry of the operation.
+ * That retry will attempt the buffered read again. The retry will generally
+ * succeed, or in rare cases where it fails, we then fall back to using the
+ * async worker threads for a blocking retry.
+ */
+static bool io_rw_should_retry(struct io_kiocb *req)
+{
+	struct io_async_rw *rw = req->async_data;
+	struct wait_page_queue *wait = &rw->wpq;
+	struct kiocb *kiocb = &req->rw.kiocb;
+
+	/* never retry for NOWAIT, we just complete with -EAGAIN */
+	if (req->flags & REQ_F_NOWAIT)
+		return false;
+
+	/* Only for buffered IO */
+	if (kiocb->ki_flags & (IOCB_DIRECT | IOCB_HIPRI))
+		return false;
+
+	/*
+	 * just use poll if we can, and don't attempt if the fs doesn't
+	 * support callback based unlocks
+	 */
+	if (file_can_poll(req->file) || !(req->file->f_mode & FMODE_BUF_RASYNC))
+		return false;
+
+	wait->wait.func = io_async_buf_func;
+	wait->wait.private = req;
+	wait->wait.flags = 0;
+	INIT_LIST_HEAD(&wait->wait.entry);
+	kiocb->ki_flags |= IOCB_WAITQ;
+	kiocb->ki_flags &= ~IOCB_NOWAIT;
+	kiocb->ki_waitq = wait;
+	return true;
+}
+
+static inline int io_iter_do_read(struct io_kiocb *req, struct iov_iter *iter)
+{
+	if (req->file->f_op->read_iter)
+		return call_read_iter(req->file, &req->rw.kiocb, iter);
+	else if (req->file->f_op->read)
+		return loop_rw_iter(READ, req, iter);
+	else
+		return -EINVAL;
+}
+
+static bool need_read_all(struct io_kiocb *req)
+{
+	return req->flags & REQ_F_ISREG ||
+		S_ISBLK(file_inode(req->file)->i_mode);
+}
+
+static int io_read(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct kiocb *kiocb = &req->rw.kiocb;
+	struct iov_iter __iter, *iter = &__iter;
+	struct io_async_rw *rw = req->async_data;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+	struct iov_iter_state __state, *state;
+	ssize_t ret, ret2;
+	loff_t *ppos;
+
+	if (rw) {
+		iter = &rw->iter;
+		state = &rw->iter_state;
+		/*
+		 * We come here from an earlier attempt, restore our state to
+		 * match in case it doesn't. It's cheap enough that we don't
+		 * need to make this conditional.
+		 */
+		iov_iter_restore(iter, state);
+		iovec = NULL;
+	} else {
+		ret = io_import_iovec(READ, req, &iovec, iter, !force_nonblock);
+		if (ret < 0)
+			return ret;
+		state = &__state;
+		iov_iter_save_state(iter, state);
+	}
+	req->result = iov_iter_count(iter);
+
+	/* Ensure we clear previously set non-block flag */
+	if (!force_nonblock)
+		kiocb->ki_flags &= ~IOCB_NOWAIT;
+	else
+		kiocb->ki_flags |= IOCB_NOWAIT;
+
+	/* If the file doesn't support async, just async punt */
+	if (force_nonblock && !io_file_supports_nowait(req, READ)) {
+		ret = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
+		return ret ?: -EAGAIN;
+	}
+
+	ppos = io_kiocb_update_pos(req);
+
+	ret = rw_verify_area(READ, req->file, ppos, req->result);
+	if (unlikely(ret)) {
+		kfree(iovec);
+		return ret;
+	}
+
+	ret = io_iter_do_read(req, iter);
+
+	if (ret == -EAGAIN || (req->flags & REQ_F_REISSUE)) {
+		req->flags &= ~REQ_F_REISSUE;
+		/* IOPOLL retry should happen for io-wq threads */
+		if (!force_nonblock && !(req->ctx->flags & IORING_SETUP_IOPOLL))
+			goto done;
+		/* no retry on NONBLOCK nor RWF_NOWAIT */
+		if (req->flags & REQ_F_NOWAIT)
+			goto done;
+		ret = 0;
+	} else if (ret == -EIOCBQUEUED) {
+		goto out_free;
+	} else if (ret <= 0 || ret == req->result || !force_nonblock ||
+		   (req->flags & REQ_F_NOWAIT) || !need_read_all(req)) {
+		/* read all, failed, already did sync or don't want to retry */
+		goto done;
+	}
+
+	/*
+	 * Don't depend on the iter state matching what was consumed, or being
+	 * untouched in case of error. Restore it and we'll advance it
+	 * manually if we need to.
+	 */
+	iov_iter_restore(iter, state);
+
+	ret2 = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
+	if (ret2)
+		return ret2;
+
+	iovec = NULL;
+	rw = req->async_data;
+	/*
+	 * Now use our persistent iterator and state, if we aren't already.
+	 * We've restored and mapped the iter to match.
+	 */
+	if (iter != &rw->iter) {
+		iter = &rw->iter;
+		state = &rw->iter_state;
+	}
+
+	do {
+		/*
+		 * We end up here because of a partial read, either from
+		 * above or inside this loop. Advance the iter by the bytes
+		 * that were consumed.
+		 */
+		iov_iter_advance(iter, ret);
+		if (!iov_iter_count(iter))
+			break;
+		rw->bytes_done += ret;
+		iov_iter_save_state(iter, state);
+
+		/* if we can retry, do so with the callbacks armed */
+		if (!io_rw_should_retry(req)) {
+			kiocb->ki_flags &= ~IOCB_WAITQ;
+			return -EAGAIN;
+		}
+
+		req->result = iov_iter_count(iter);
+		/*
+		 * Now retry read with the IOCB_WAITQ parts set in the iocb. If
+		 * we get -EIOCBQUEUED, then we'll get a notification when the
+		 * desired page gets unlocked. We can also get a partial read
+		 * here, and if we do, then just retry at the new offset.
+		 */
+		ret = io_iter_do_read(req, iter);
+		if (ret == -EIOCBQUEUED)
+			return 0;
+		/* we got some bytes, but not all. retry. */
+		kiocb->ki_flags &= ~IOCB_WAITQ;
+		iov_iter_restore(iter, state);
+	} while (ret > 0);
+done:
+	kiocb_done(kiocb, ret, issue_flags);
+out_free:
+	/* it's faster to check here then delegate to kfree */
+	if (iovec)
+		kfree(iovec);
+	return 0;
+}
+
+static int io_write_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	if (unlikely(!(req->file->f_mode & FMODE_WRITE)))
+		return -EBADF;
+	return io_prep_rw(req, sqe, WRITE);
+}
+
+static int io_write(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct kiocb *kiocb = &req->rw.kiocb;
+	struct iov_iter __iter, *iter = &__iter;
+	struct io_async_rw *rw = req->async_data;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+	struct iov_iter_state __state, *state;
+	ssize_t ret, ret2;
+	loff_t *ppos;
+
+	if (rw) {
+		iter = &rw->iter;
+		state = &rw->iter_state;
+		iov_iter_restore(iter, state);
+		iovec = NULL;
+	} else {
+		ret = io_import_iovec(WRITE, req, &iovec, iter, !force_nonblock);
+		if (ret < 0)
+			return ret;
+		state = &__state;
+		iov_iter_save_state(iter, state);
+	}
+	req->result = iov_iter_count(iter);
+
+	/* Ensure we clear previously set non-block flag */
+	if (!force_nonblock)
+		kiocb->ki_flags &= ~IOCB_NOWAIT;
+	else
+		kiocb->ki_flags |= IOCB_NOWAIT;
+
+	/* If the file doesn't support async, just async punt */
+	if (force_nonblock && !io_file_supports_nowait(req, WRITE))
+		goto copy_iov;
+
+	/* file path doesn't support NOWAIT for non-direct_IO */
+	if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT) &&
+	    (req->flags & REQ_F_ISREG))
+		goto copy_iov;
+
+	ppos = io_kiocb_update_pos(req);
+
+	ret = rw_verify_area(WRITE, req->file, ppos, req->result);
+	if (unlikely(ret))
+		goto out_free;
+
+	/*
+	 * Open-code file_start_write here to grab freeze protection,
+	 * which will be released by another thread in
+	 * io_complete_rw().  Fool lockdep by telling it the lock got
+	 * released so that it doesn't complain about the held lock when
+	 * we return to userspace.
+	 */
+	if (req->flags & REQ_F_ISREG) {
+		sb_start_write(file_inode(req->file)->i_sb);
+		__sb_writers_release(file_inode(req->file)->i_sb,
+					SB_FREEZE_WRITE);
+	}
+	kiocb->ki_flags |= IOCB_WRITE;
+
+	if (req->file->f_op->write_iter)
+		ret2 = call_write_iter(req->file, kiocb, iter);
+	else if (req->file->f_op->write)
+		ret2 = loop_rw_iter(WRITE, req, iter);
+	else
+		ret2 = -EINVAL;
+
+	if (req->flags & REQ_F_REISSUE) {
+		req->flags &= ~REQ_F_REISSUE;
+		ret2 = -EAGAIN;
+	}
+
+	/*
+	 * Raw bdev writes will return -EOPNOTSUPP for IOCB_NOWAIT. Just
+	 * retry them without IOCB_NOWAIT.
+	 */
+	if (ret2 == -EOPNOTSUPP && (kiocb->ki_flags & IOCB_NOWAIT))
+		ret2 = -EAGAIN;
+	/* no retry on NONBLOCK nor RWF_NOWAIT */
+	if (ret2 == -EAGAIN && (req->flags & REQ_F_NOWAIT))
+		goto done;
+	if (!force_nonblock || ret2 != -EAGAIN) {
+		/* IOPOLL retry should happen for io-wq threads */
+		if ((req->ctx->flags & IORING_SETUP_IOPOLL) && ret2 == -EAGAIN)
+			goto copy_iov;
+done:
+		kiocb_done(kiocb, ret2, issue_flags);
+	} else {
+copy_iov:
+		iov_iter_restore(iter, state);
+		ret = io_setup_async_rw(req, iovec, inline_vecs, iter, false);
+		if (!ret) {
+			if (kiocb->ki_flags & IOCB_WRITE)
+				kiocb_end_write(req);
+			return -EAGAIN;
+		}
+		return ret;
+	}
+out_free:
+	/* it's reportedly faster than delegating the null check to kfree() */
+	if (iovec)
+		kfree(iovec);
+	return ret;
+}
+
+static int io_renameat_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe)
+{
+	struct io_rename *ren = &req->rename;
+	const char __user *oldf, *newf;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->flags & REQ_F_FIXED_FILE))
+		return -EBADF;
+
+	ren->old_dfd = READ_ONCE(sqe->fd);
+	oldf = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	newf = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+	ren->new_dfd = READ_ONCE(sqe->len);
+	ren->flags = READ_ONCE(sqe->rename_flags);
+
+	ren->oldpath = getname(oldf);
+	if (IS_ERR(ren->oldpath))
+		return PTR_ERR(ren->oldpath);
+
+	ren->newpath = getname(newf);
+	if (IS_ERR(ren->newpath)) {
+		putname(ren->oldpath);
+		return PTR_ERR(ren->newpath);
+	}
+
+	req->flags |= REQ_F_NEED_CLEANUP;
+	return 0;
+}
+
+static int io_renameat(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_rename *ren = &req->rename;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = do_renameat2(ren->old_dfd, ren->oldpath, ren->new_dfd,
+				ren->newpath, ren->flags);
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_unlinkat_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe)
+{
+	struct io_unlink *un = &req->unlink;
+	const char __user *fname;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
+	    sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->flags & REQ_F_FIXED_FILE))
+		return -EBADF;
+
+	un->dfd = READ_ONCE(sqe->fd);
+
+	un->flags = READ_ONCE(sqe->unlink_flags);
+	if (un->flags & ~AT_REMOVEDIR)
+		return -EINVAL;
+
+	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	un->filename = getname(fname);
+	if (IS_ERR(un->filename))
+		return PTR_ERR(un->filename);
+
+	req->flags |= REQ_F_NEED_CLEANUP;
+	return 0;
+}
+
+static int io_unlinkat(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_unlink *un = &req->unlink;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	if (un->flags & AT_REMOVEDIR)
+		ret = do_rmdir(un->dfd, un->filename);
+	else
+		ret = do_unlinkat(un->dfd, un->filename);
+
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_shutdown_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe)
+{
+#if defined(CONFIG_NET)
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->ioprio || sqe->off || sqe->addr || sqe->rw_flags ||
+		     sqe->buf_index || sqe->splice_fd_in))
+		return -EINVAL;
+
+	req->shutdown.how = READ_ONCE(sqe->len);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int io_shutdown(struct io_kiocb *req, unsigned int issue_flags)
+{
+#if defined(CONFIG_NET)
+	struct socket *sock;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	sock = sock_from_file(req->file, &ret);
+	if (unlikely(!sock))
+		return ret;
+
+	ret = __sys_shutdown_sock(sock, req->shutdown.how);
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int __io_splice_prep(struct io_kiocb *req,
+			    const struct io_uring_sqe *sqe)
+{
+	struct io_splice *sp = &req->splice;
+	unsigned int valid_flags = SPLICE_F_FD_IN_FIXED | SPLICE_F_ALL;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	sp->len = READ_ONCE(sqe->len);
+	sp->flags = READ_ONCE(sqe->splice_flags);
+	if (unlikely(sp->flags & ~valid_flags))
+		return -EINVAL;
+	sp->splice_fd_in = READ_ONCE(sqe->splice_fd_in);
+	return 0;
+}
+
+static int io_tee_prep(struct io_kiocb *req,
+		       const struct io_uring_sqe *sqe)
+{
+	if (READ_ONCE(sqe->splice_off_in) || READ_ONCE(sqe->off))
+		return -EINVAL;
+	return __io_splice_prep(req, sqe);
+}
+
+static int io_tee(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_splice *sp = &req->splice;
+	struct file *out = sp->file_out;
+	unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
+	struct file *in;
+	long ret = 0;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	in = io_file_get(req->ctx, req, sp->splice_fd_in,
+			 (sp->flags & SPLICE_F_FD_IN_FIXED), issue_flags);
+	if (!in) {
+		ret = -EBADF;
+		goto done;
+	}
+
+	if (sp->len)
+		ret = do_tee(in, out, sp->len, flags);
+
+	if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
+		io_put_file(in);
+done:
+	if (ret != sp->len)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_splice_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_splice *sp = &req->splice;
+
+	sp->off_in = READ_ONCE(sqe->splice_off_in);
+	sp->off_out = READ_ONCE(sqe->off);
+	return __io_splice_prep(req, sqe);
+}
+
+static int io_splice(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_splice *sp = &req->splice;
+	struct file *out = sp->file_out;
+	unsigned int flags = sp->flags & ~SPLICE_F_FD_IN_FIXED;
+	loff_t *poff_in, *poff_out;
+	struct file *in;
+	long ret = 0;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	in = io_file_get(req->ctx, req, sp->splice_fd_in,
+			 (sp->flags & SPLICE_F_FD_IN_FIXED), issue_flags);
+	if (!in) {
+		ret = -EBADF;
+		goto done;
+	}
+
+	poff_in = (sp->off_in == -1) ? NULL : &sp->off_in;
+	poff_out = (sp->off_out == -1) ? NULL : &sp->off_out;
+
+	if (sp->len)
+		ret = do_splice(in, poff_in, out, poff_out, sp->len, flags);
+
+	if (!(sp->flags & SPLICE_F_FD_IN_FIXED))
+		io_put_file(in);
+done:
+	if (ret != sp->len)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+/*
+ * IORING_OP_NOP just posts a completion event, nothing else.
+ */
+static int io_nop(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	__io_req_complete(req, issue_flags, 0, 0);
+	return 0;
+}
+
+static int io_fsync_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index ||
+		     sqe->splice_fd_in))
+		return -EINVAL;
+
+	req->sync.flags = READ_ONCE(sqe->fsync_flags);
+	if (unlikely(req->sync.flags & ~IORING_FSYNC_DATASYNC))
+		return -EINVAL;
+
+	req->sync.off = READ_ONCE(sqe->off);
+	req->sync.len = READ_ONCE(sqe->len);
+	return 0;
+}
+
+static int io_fsync(struct io_kiocb *req, unsigned int issue_flags)
+{
+	loff_t end = req->sync.off + req->sync.len;
+	int ret;
+
+	/* fsync always requires a blocking context */
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = vfs_fsync_range(req->file, req->sync.off,
+				end > 0 ? end : LLONG_MAX,
+				req->sync.flags & IORING_FSYNC_DATASYNC);
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_fallocate_prep(struct io_kiocb *req,
+			     const struct io_uring_sqe *sqe)
+{
+	if (sqe->ioprio || sqe->buf_index || sqe->rw_flags ||
+	    sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	req->sync.off = READ_ONCE(sqe->off);
+	req->sync.len = READ_ONCE(sqe->addr);
+	req->sync.mode = READ_ONCE(sqe->len);
+	return 0;
+}
+
+static int io_fallocate(struct io_kiocb *req, unsigned int issue_flags)
+{
+	int ret;
+
+	/* fallocate always requiring blocking context */
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+	ret = vfs_fallocate(req->file, req->sync.mode, req->sync.off,
+				req->sync.len);
+	if (ret < 0)
+		req_set_fail(req);
+	else
+		fsnotify_modify(req->file);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	const char __user *fname;
+	int ret;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->ioprio || sqe->buf_index))
+		return -EINVAL;
+	if (unlikely(req->flags & REQ_F_FIXED_FILE))
+		return -EBADF;
+
+	/* open.how should be already initialised */
+	if (!(req->open.how.flags & O_PATH) && force_o_largefile())
+		req->open.how.flags |= O_LARGEFILE;
+
+	req->open.dfd = READ_ONCE(sqe->fd);
+	fname = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	req->open.filename = getname(fname);
+	if (IS_ERR(req->open.filename)) {
+		ret = PTR_ERR(req->open.filename);
+		req->open.filename = NULL;
+		return ret;
+	}
+
+	req->open.file_slot = READ_ONCE(sqe->file_index);
+	if (req->open.file_slot && (req->open.how.flags & O_CLOEXEC))
+		return -EINVAL;
+
+	req->open.nofile = rlimit(RLIMIT_NOFILE);
+	req->flags |= REQ_F_NEED_CLEANUP;
+	return 0;
+}
+
+static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	u64 mode = READ_ONCE(sqe->len);
+	u64 flags = READ_ONCE(sqe->open_flags);
+
+	req->open.how = build_open_how(flags, mode);
+	return __io_openat_prep(req, sqe);
+}
+
+static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct open_how __user *how;
+	size_t len;
+	int ret;
+
+	how = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+	len = READ_ONCE(sqe->len);
+	if (len < OPEN_HOW_SIZE_VER0)
+		return -EINVAL;
+
+	ret = copy_struct_from_user(&req->open.how, sizeof(req->open.how), how,
+					len);
+	if (ret)
+		return ret;
+
+	return __io_openat_prep(req, sqe);
+}
+
+static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct open_flags op;
+	struct file *file;
+	bool resolve_nonblock, nonblock_set;
+	bool fixed = !!req->open.file_slot;
+	int ret;
+
+	ret = build_open_flags(&req->open.how, &op);
+	if (ret)
+		goto err;
+	nonblock_set = op.open_flag & O_NONBLOCK;
+	resolve_nonblock = req->open.how.resolve & RESOLVE_CACHED;
+	if (issue_flags & IO_URING_F_NONBLOCK) {
+		/*
+		 * Don't bother trying for O_TRUNC, O_CREAT, or O_TMPFILE open,
+		 * it'll always -EAGAIN. Note that we test for __O_TMPFILE
+		 * because O_TMPFILE includes O_DIRECTORY, which isn't a flag
+		 * we need to force async for.
+		 */
+		if (req->open.how.flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
+			return -EAGAIN;
+		op.lookup_flags |= LOOKUP_CACHED;
+		op.open_flag |= O_NONBLOCK;
+	}
+
+	if (!fixed) {
+		ret = __get_unused_fd_flags(req->open.how.flags, req->open.nofile);
+		if (ret < 0)
+			goto err;
+	}
+
+	file = do_filp_open(req->open.dfd, req->open.filename, &op);
+	if (IS_ERR(file)) {
+		/*
+		 * We could hang on to this 'fd' on retrying, but seems like
+		 * marginal gain for something that is now known to be a slower
+		 * path. So just put it, and we'll get a new one when we retry.
+		 */
+		if (!fixed)
+			put_unused_fd(ret);
+
+		ret = PTR_ERR(file);
+		/* only retry if RESOLVE_CACHED wasn't already set by application */
+		if (ret == -EAGAIN &&
+		    (!resolve_nonblock && (issue_flags & IO_URING_F_NONBLOCK)))
+			return -EAGAIN;
+		goto err;
+	}
+
+	if ((issue_flags & IO_URING_F_NONBLOCK) && !nonblock_set)
+		file->f_flags &= ~O_NONBLOCK;
+	fsnotify_open(file);
+
+	if (!fixed)
+		fd_install(ret, file);
+	else
+		ret = io_install_fixed_file(req, file, issue_flags,
+					    req->open.file_slot - 1);
+err:
+	putname(req->open.filename);
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	if (ret < 0)
+		req_set_fail(req);
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_openat(struct io_kiocb *req, unsigned int issue_flags)
+{
+	return io_openat2(req, issue_flags);
+}
+
+static int io_remove_buffers_prep(struct io_kiocb *req,
+				  const struct io_uring_sqe *sqe)
+{
+	struct io_provide_buf *p = &req->pbuf;
+	u64 tmp;
+
+	if (sqe->ioprio || sqe->rw_flags || sqe->addr || sqe->len || sqe->off ||
+	    sqe->splice_fd_in)
+		return -EINVAL;
+
+	tmp = READ_ONCE(sqe->fd);
+	if (!tmp || tmp > USHRT_MAX)
+		return -EINVAL;
+
+	memset(p, 0, sizeof(*p));
+	p->nbufs = tmp;
+	p->bgid = READ_ONCE(sqe->buf_group);
+	return 0;
+}
+
+static int __io_remove_buffers(struct io_ring_ctx *ctx, struct io_buffer *buf,
+			       int bgid, unsigned nbufs)
+{
+	unsigned i = 0;
+
+	/* shouldn't happen */
+	if (!nbufs)
+		return 0;
+
+	/* the head kbuf is the list itself */
+	while (!list_empty(&buf->list)) {
+		struct io_buffer *nxt;
+
+		nxt = list_first_entry(&buf->list, struct io_buffer, list);
+		list_del(&nxt->list);
+		kfree(nxt);
+		if (++i == nbufs)
+			return i;
+		cond_resched();
+	}
+	i++;
+	kfree(buf);
+	xa_erase(&ctx->io_buffers, bgid);
+
+	return i;
+}
+
+static int io_remove_buffers(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_provide_buf *p = &req->pbuf;
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_buffer *head;
+	int ret = 0;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+
+	io_ring_submit_lock(ctx, !force_nonblock);
+
+	lockdep_assert_held(&ctx->uring_lock);
+
+	ret = -ENOENT;
+	head = xa_load(&ctx->io_buffers, p->bgid);
+	if (head)
+		ret = __io_remove_buffers(ctx, head, p->bgid, p->nbufs);
+	if (ret < 0)
+		req_set_fail(req);
+
+	/* complete before unlock, IOPOLL may need the lock */
+	__io_req_complete(req, issue_flags, ret, 0);
+	io_ring_submit_unlock(ctx, !force_nonblock);
+	return 0;
+}
+
+static int io_provide_buffers_prep(struct io_kiocb *req,
+				   const struct io_uring_sqe *sqe)
+{
+	unsigned long size, tmp_check;
+	struct io_provide_buf *p = &req->pbuf;
+	u64 tmp;
+
+	if (sqe->ioprio || sqe->rw_flags || sqe->splice_fd_in)
+		return -EINVAL;
+
+	tmp = READ_ONCE(sqe->fd);
+	if (!tmp || tmp > USHRT_MAX)
+		return -E2BIG;
+	p->nbufs = tmp;
+	p->addr = READ_ONCE(sqe->addr);
+	p->len = READ_ONCE(sqe->len);
+
+	if (check_mul_overflow((unsigned long)p->len, (unsigned long)p->nbufs,
+				&size))
+		return -EOVERFLOW;
+	if (check_add_overflow((unsigned long)p->addr, size, &tmp_check))
+		return -EOVERFLOW;
+
+	size = (unsigned long)p->len * p->nbufs;
+	if (!access_ok(u64_to_user_ptr(p->addr), size))
+		return -EFAULT;
+
+	p->bgid = READ_ONCE(sqe->buf_group);
+	tmp = READ_ONCE(sqe->off);
+	if (tmp > USHRT_MAX)
+		return -E2BIG;
+	p->bid = tmp;
+	return 0;
+}
+
+static int io_add_buffers(struct io_provide_buf *pbuf, struct io_buffer **head)
+{
+	struct io_buffer *buf;
+	u64 addr = pbuf->addr;
+	int i, bid = pbuf->bid;
+
+	for (i = 0; i < pbuf->nbufs; i++) {
+		buf = kmalloc(sizeof(*buf), GFP_KERNEL_ACCOUNT);
+		if (!buf)
+			break;
+
+		buf->addr = addr;
+		buf->len = min_t(__u32, pbuf->len, MAX_RW_COUNT);
+		buf->bid = bid;
+		addr += pbuf->len;
+		bid++;
+		if (!*head) {
+			INIT_LIST_HEAD(&buf->list);
+			*head = buf;
+		} else {
+			list_add_tail(&buf->list, &(*head)->list);
+		}
+		cond_resched();
+	}
+
+	return i ? i : -ENOMEM;
+}
+
+static int io_provide_buffers(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_provide_buf *p = &req->pbuf;
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_buffer *head, *list;
+	int ret = 0;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+
+	io_ring_submit_lock(ctx, !force_nonblock);
+
+	lockdep_assert_held(&ctx->uring_lock);
+
+	list = head = xa_load(&ctx->io_buffers, p->bgid);
+
+	ret = io_add_buffers(p, &head);
+	if (ret >= 0 && !list) {
+		ret = xa_insert(&ctx->io_buffers, p->bgid, head,
+				GFP_KERNEL_ACCOUNT);
+		if (ret < 0)
+			__io_remove_buffers(ctx, head, p->bgid, -1U);
+	}
+	if (ret < 0)
+		req_set_fail(req);
+	/* complete before unlock, IOPOLL may need the lock */
+	__io_req_complete(req, issue_flags, ret, 0);
+	io_ring_submit_unlock(ctx, !force_nonblock);
+	return 0;
+}
+
+static int io_epoll_ctl_prep(struct io_kiocb *req,
+			     const struct io_uring_sqe *sqe)
+{
+#if defined(CONFIG_EPOLL)
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	req->epoll.epfd = READ_ONCE(sqe->fd);
+	req->epoll.op = READ_ONCE(sqe->len);
+	req->epoll.fd = READ_ONCE(sqe->off);
+
+	if (ep_op_has_event(req->epoll.op)) {
+		struct epoll_event __user *ev;
+
+		ev = u64_to_user_ptr(READ_ONCE(sqe->addr));
+		if (copy_from_user(&req->epoll.event, ev, sizeof(*ev)))
+			return -EFAULT;
+	}
+
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int io_epoll_ctl(struct io_kiocb *req, unsigned int issue_flags)
+{
+#if defined(CONFIG_EPOLL)
+	struct io_epoll *ie = &req->epoll;
+	int ret;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+
+	ret = do_epoll_ctl(ie->epfd, ie->op, ie->fd, &ie->event, force_nonblock);
+	if (force_nonblock && ret == -EAGAIN)
+		return -EAGAIN;
+
+	if (ret < 0)
+		req_set_fail(req);
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int io_madvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+#if defined(CONFIG_ADVISE_SYSCALLS) && defined(CONFIG_MMU)
+	if (sqe->ioprio || sqe->buf_index || sqe->off || sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	req->madvise.addr = READ_ONCE(sqe->addr);
+	req->madvise.len = READ_ONCE(sqe->len);
+	req->madvise.advice = READ_ONCE(sqe->fadvise_advice);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int io_madvise(struct io_kiocb *req, unsigned int issue_flags)
+{
+#if defined(CONFIG_ADVISE_SYSCALLS) && defined(CONFIG_MMU)
+	struct io_madvise *ma = &req->madvise;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = do_madvise(current->mm, ma->addr, ma->len, ma->advice);
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
+
+static int io_fadvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	if (sqe->ioprio || sqe->buf_index || sqe->addr || sqe->splice_fd_in)
+		return -EINVAL;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
+	req->fadvise.offset = READ_ONCE(sqe->off);
+	req->fadvise.len = READ_ONCE(sqe->len);
+	req->fadvise.advice = READ_ONCE(sqe->fadvise_advice);
+	return 0;
+}
+
+static int io_fadvise(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_fadvise *fa = &req->fadvise;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK) {
+		switch (fa->advice) {
+		case POSIX_FADV_NORMAL:
+		case POSIX_FADV_RANDOM:
+		case POSIX_FADV_SEQUENTIAL:
+			break;
+		default:
+			return -EAGAIN;
+		}
+	}
+
+	ret = vfs_fadvise(req->file, fa->offset, fa->len, fa->advice);
+	if (ret < 0)
+		req_set_fail(req);
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_statx_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
+		return -EINVAL;
+	if (req->flags & REQ_F_FIXED_FILE)
+		return -EBADF;
+
+	req->statx.dfd = READ_ONCE(sqe->fd);
+	req->statx.mask = READ_ONCE(sqe->len);
+	req->statx.filename = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	req->statx.buffer = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+	req->statx.flags = READ_ONCE(sqe->statx_flags);
+
+	return 0;
+}
+
+static int io_statx(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_statx *ctx = &req->statx;
+	int ret;
+
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = do_statx(ctx->dfd, ctx->filename, ctx->flags, ctx->mask,
+		       ctx->buffer);
+
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+static int io_close_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->off || sqe->addr || sqe->len ||
+	    sqe->rw_flags || sqe->buf_index)
+		return -EINVAL;
+	if (req->flags & REQ_F_FIXED_FILE)
+		return -EBADF;
+
+	req->close.fd = READ_ONCE(sqe->fd);
+	req->close.file_slot = READ_ONCE(sqe->file_index);
+	if (req->close.file_slot && req->close.fd)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int io_close(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct files_struct *files = current->files;
+	struct io_close *close = &req->close;
+	struct fdtable *fdt;
+	struct file *file = NULL;
+	int ret = -EBADF;
+
+	if (req->close.file_slot) {
+		ret = io_close_fixed(req, issue_flags);
+		goto err;
+	}
+
+	spin_lock(&files->file_lock);
+	fdt = files_fdtable(files);
+	if (close->fd >= fdt->max_fds) {
+		spin_unlock(&files->file_lock);
+		goto err;
+	}
+	file = fdt->fd[close->fd];
+	if (!file || file->f_op == &io_uring_fops) {
+		spin_unlock(&files->file_lock);
+		file = NULL;
+		goto err;
+	}
+
+	/* if the file has a flush method, be safe and punt to async */
+	if (file->f_op->flush && (issue_flags & IO_URING_F_NONBLOCK)) {
+		spin_unlock(&files->file_lock);
+		return -EAGAIN;
+	}
+
+	ret = __close_fd_get_file(close->fd, &file);
+	spin_unlock(&files->file_lock);
+	if (ret < 0) {
+		if (ret == -ENOENT)
+			ret = -EBADF;
+		goto err;
+	}
+
+	/* No ->flush() or already async, safely close from here */
+	ret = filp_close(file, current->files);
+err:
+	if (ret < 0)
+		req_set_fail(req);
+	if (file)
+		fput(file);
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_sfr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index ||
+		     sqe->splice_fd_in))
+		return -EINVAL;
+
+	req->sync.off = READ_ONCE(sqe->off);
+	req->sync.len = READ_ONCE(sqe->len);
+	req->sync.flags = READ_ONCE(sqe->sync_range_flags);
+	return 0;
+}
+
+static int io_sync_file_range(struct io_kiocb *req, unsigned int issue_flags)
+{
+	int ret;
+
+	/* sync_file_range always requires a blocking context */
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
+	ret = sync_file_range(req->file, req->sync.off, req->sync.len,
+				req->sync.flags);
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete(req, ret);
+	return 0;
+}
+
+#if defined(CONFIG_NET)
+static bool io_net_retry(struct socket *sock, int flags)
+{
+	if (!(flags & MSG_WAITALL))
+		return false;
+	return sock->type == SOCK_STREAM || sock->type == SOCK_SEQPACKET;
+}
+
+static int io_setup_async_msg(struct io_kiocb *req,
+			      struct io_async_msghdr *kmsg)
+{
+	struct io_async_msghdr *async_msg = req->async_data;
+
+	if (async_msg)
+		return -EAGAIN;
+	if (io_alloc_async_data(req)) {
+		kfree(kmsg->free_iov);
+		return -ENOMEM;
+	}
+	async_msg = req->async_data;
+	req->flags |= REQ_F_NEED_CLEANUP;
+	memcpy(async_msg, kmsg, sizeof(*kmsg));
+	if (async_msg->msg.msg_name)
+		async_msg->msg.msg_name = &async_msg->addr;
+	/* if were using fast_iov, set it to the new one */
+	if (!kmsg->free_iov) {
+		size_t fast_idx = kmsg->msg.msg_iter.iov - kmsg->fast_iov;
+		async_msg->msg.msg_iter.iov = &async_msg->fast_iov[fast_idx];
+	}
+
+	return -EAGAIN;
+}
+
+static int io_sendmsg_copy_hdr(struct io_kiocb *req,
+			       struct io_async_msghdr *iomsg)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+	int ret;
+
+	iomsg->msg.msg_name = &iomsg->addr;
+	iomsg->free_iov = iomsg->fast_iov;
+	ret = sendmsg_copy_msghdr(&iomsg->msg, req->sr_msg.umsg,
+				   req->sr_msg.msg_flags, &iomsg->free_iov);
+	/* save msg_control as sys_sendmsg() overwrites it */
+	sr->msg_control = iomsg->msg.msg_control;
+	return ret;
+}
+
+static int io_sendmsg_prep_async(struct io_kiocb *req)
+{
+	int ret;
+
+	ret = io_sendmsg_copy_hdr(req, req->async_data);
+	if (!ret)
+		req->flags |= REQ_F_NEED_CLEANUP;
+	return ret;
+}
+
+static int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->addr2 || sqe->file_index))
+		return -EINVAL;
+	if (unlikely(sqe->addr2 || sqe->file_index || sqe->ioprio))
+		return -EINVAL;
+
+	sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	sr->len = READ_ONCE(sqe->len);
+	sr->msg_flags = READ_ONCE(sqe->msg_flags) | MSG_NOSIGNAL;
+	if (sr->msg_flags & MSG_DONTWAIT)
+		req->flags |= REQ_F_NOWAIT;
+
+#ifdef CONFIG_COMPAT
+	if (req->ctx->compat)
+		sr->msg_flags |= MSG_CMSG_COMPAT;
+#endif
+	sr->done_io = 0;
+	return 0;
+}
+
+static int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_async_msghdr iomsg, *kmsg;
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct socket *sock;
+	unsigned flags;
+	int min_ret = 0;
+	int ret;
+
+	sock = sock_from_file(req->file, &ret);
+	if (unlikely(!sock))
+		return ret;
+
+	kmsg = req->async_data;
+	if (!kmsg) {
+		ret = io_sendmsg_copy_hdr(req, &iomsg);
+		if (ret)
+			return ret;
+		kmsg = &iomsg;
+	} else {
+		kmsg->msg.msg_control = sr->msg_control;
+	}
+
+	flags = req->sr_msg.msg_flags;
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		flags |= MSG_DONTWAIT;
+	if (flags & MSG_WAITALL)
+		min_ret = iov_iter_count(&kmsg->msg.msg_iter);
+
+	ret = __sys_sendmsg_sock(sock, &kmsg->msg, flags);
+
+	if (ret < min_ret) {
+		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
+			return io_setup_async_msg(req, kmsg);
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
+		if (ret > 0 && io_net_retry(sock, flags)) {
+			sr->done_io += ret;
+			req->flags |= REQ_F_PARTIAL_IO;
+			return io_setup_async_msg(req, kmsg);
+		}
+		req_set_fail(req);
+	}
+	/* fast path, check for non-NULL to avoid function call */
+	if (kmsg->free_iov)
+		kfree(kmsg->free_iov);
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	if (ret >= 0)
+		ret += sr->done_io;
+	else if (sr->done_io)
+		ret = sr->done_io;
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_send(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct msghdr msg;
+	struct iovec iov;
+	struct socket *sock;
+	unsigned flags;
+	int min_ret = 0;
+	int ret;
+
+	sock = sock_from_file(req->file, &ret);
+	if (unlikely(!sock))
+		return ret;
+
+	ret = import_single_range(WRITE, sr->buf, sr->len, &iov, &msg.msg_iter);
+	if (unlikely(ret))
+		return ret;
+
+	msg.msg_name = NULL;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_namelen = 0;
+
+	flags = req->sr_msg.msg_flags;
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		flags |= MSG_DONTWAIT;
+	if (flags & MSG_WAITALL)
+		min_ret = iov_iter_count(&msg.msg_iter);
+
+	msg.msg_flags = flags;
+	ret = sock_sendmsg(sock, &msg);
+	if (ret < min_ret) {
+		if (ret == -EAGAIN && (issue_flags & IO_URING_F_NONBLOCK))
+			return -EAGAIN;
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
+		if (ret > 0 && io_net_retry(sock, flags)) {
+			sr->len -= ret;
+			sr->buf += ret;
+			sr->done_io += ret;
+			req->flags |= REQ_F_PARTIAL_IO;
+			return -EAGAIN;
+		}
+		req_set_fail(req);
+	}
+	if (ret >= 0)
+		ret += sr->done_io;
+	else if (sr->done_io)
+		ret = sr->done_io;
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int __io_recvmsg_copy_hdr(struct io_kiocb *req,
+				 struct io_async_msghdr *iomsg)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct iovec __user *uiov;
+	size_t iov_len;
+	int ret;
+
+	ret = __copy_msghdr_from_user(&iomsg->msg, sr->umsg,
+					&iomsg->uaddr, &uiov, &iov_len);
+	if (ret)
+		return ret;
+
+	if (req->flags & REQ_F_BUFFER_SELECT) {
+		if (iov_len > 1)
+			return -EINVAL;
+		if (copy_from_user(iomsg->fast_iov, uiov, sizeof(*uiov)))
+			return -EFAULT;
+		sr->len = iomsg->fast_iov[0].iov_len;
+		iomsg->free_iov = NULL;
+	} else {
+		iomsg->free_iov = iomsg->fast_iov;
+		ret = __import_iovec(READ, uiov, iov_len, UIO_FASTIOV,
+				     &iomsg->free_iov, &iomsg->msg.msg_iter,
+				     false);
+		if (ret > 0)
+			ret = 0;
+	}
+
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static int __io_compat_recvmsg_copy_hdr(struct io_kiocb *req,
+					struct io_async_msghdr *iomsg)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct compat_iovec __user *uiov;
+	compat_uptr_t ptr;
+	compat_size_t len;
+	int ret;
+
+	ret = __get_compat_msghdr(&iomsg->msg, sr->umsg_compat, &iomsg->uaddr,
+				  &ptr, &len);
+	if (ret)
+		return ret;
+
+	uiov = compat_ptr(ptr);
+	if (req->flags & REQ_F_BUFFER_SELECT) {
+		compat_ssize_t clen;
+
+		if (len > 1)
+			return -EINVAL;
+		if (!access_ok(uiov, sizeof(*uiov)))
+			return -EFAULT;
+		if (__get_user(clen, &uiov->iov_len))
+			return -EFAULT;
+		if (clen < 0)
+			return -EINVAL;
+		sr->len = clen;
+		iomsg->free_iov = NULL;
+	} else {
+		iomsg->free_iov = iomsg->fast_iov;
+		ret = __import_iovec(READ, (struct iovec __user *)uiov, len,
+				   UIO_FASTIOV, &iomsg->free_iov,
+				   &iomsg->msg.msg_iter, true);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+#endif
+
+static int io_recvmsg_copy_hdr(struct io_kiocb *req,
+			       struct io_async_msghdr *iomsg)
+{
+	iomsg->msg.msg_name = &iomsg->addr;
+
+#ifdef CONFIG_COMPAT
+	if (req->ctx->compat)
+		return __io_compat_recvmsg_copy_hdr(req, iomsg);
+#endif
+
+	return __io_recvmsg_copy_hdr(req, iomsg);
+}
+
+static struct io_buffer *io_recv_buffer_select(struct io_kiocb *req,
+					       bool needs_lock)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct io_buffer *kbuf;
+
+	kbuf = io_buffer_select(req, &sr->len, sr->bgid, sr->kbuf, needs_lock);
+	if (IS_ERR(kbuf))
+		return kbuf;
+
+	sr->kbuf = kbuf;
+	req->flags |= REQ_F_BUFFER_SELECTED;
+	return kbuf;
+}
+
+static inline unsigned int io_put_recv_kbuf(struct io_kiocb *req)
+{
+	return io_put_kbuf(req, req->sr_msg.kbuf);
+}
+
+static int io_recvmsg_prep_async(struct io_kiocb *req)
+{
+	int ret;
+
+	ret = io_recvmsg_copy_hdr(req, req->async_data);
+	if (!ret)
+		req->flags |= REQ_F_NEED_CLEANUP;
+	return ret;
+}
+
+static int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_sr_msg *sr = &req->sr_msg;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(sqe->addr2 || sqe->file_index))
+		return -EINVAL;
+	if (unlikely(sqe->addr2 || sqe->file_index || sqe->ioprio))
+		return -EINVAL;
+
+	sr->umsg = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	sr->len = READ_ONCE(sqe->len);
+	sr->bgid = READ_ONCE(sqe->buf_group);
+	sr->msg_flags = READ_ONCE(sqe->msg_flags);
+	if (sr->msg_flags & MSG_DONTWAIT)
+		req->flags |= REQ_F_NOWAIT;
+
+#ifdef CONFIG_COMPAT
+	if (req->ctx->compat)
+		sr->msg_flags |= MSG_CMSG_COMPAT;
+#endif
+	sr->done_io = 0;
+	return 0;
+}
+
+static int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_async_msghdr iomsg, *kmsg;
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct socket *sock;
+	struct io_buffer *kbuf;
+	unsigned flags;
+	int min_ret = 0;
+	int ret, cflags = 0;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+
+	sock = sock_from_file(req->file, &ret);
+	if (unlikely(!sock))
+		return ret;
+
+	kmsg = req->async_data;
+	if (!kmsg) {
+		ret = io_recvmsg_copy_hdr(req, &iomsg);
+		if (ret)
+			return ret;
+		kmsg = &iomsg;
+	}
+
+	if (req->flags & REQ_F_BUFFER_SELECT) {
+		kbuf = io_recv_buffer_select(req, !force_nonblock);
+		if (IS_ERR(kbuf))
+			return PTR_ERR(kbuf);
+		kmsg->fast_iov[0].iov_base = u64_to_user_ptr(kbuf->addr);
+		kmsg->fast_iov[0].iov_len = req->sr_msg.len;
+		iov_iter_init(&kmsg->msg.msg_iter, READ, kmsg->fast_iov,
+				1, req->sr_msg.len);
+	}
+
+	flags = req->sr_msg.msg_flags;
+	if (force_nonblock)
+		flags |= MSG_DONTWAIT;
+	if (flags & MSG_WAITALL && !kmsg->msg.msg_controllen)
+		min_ret = iov_iter_count(&kmsg->msg.msg_iter);
+
+	ret = __sys_recvmsg_sock(sock, &kmsg->msg, req->sr_msg.umsg,
+					kmsg->uaddr, flags);
+	if (ret < min_ret) {
+		if (ret == -EAGAIN && force_nonblock)
+			return io_setup_async_msg(req, kmsg);
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
+		if (ret > 0 && io_net_retry(sock, flags)) {
+			kmsg->msg.msg_controllen = 0;
+			kmsg->msg.msg_control = NULL;
+			sr->done_io += ret;
+			req->flags |= REQ_F_PARTIAL_IO;
+			return io_setup_async_msg(req, kmsg);
+		}
+		req_set_fail(req);
+	} else if ((flags & MSG_WAITALL) && (kmsg->msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
+		req_set_fail(req);
+	}
+
+	if (req->flags & REQ_F_BUFFER_SELECTED)
+		cflags = io_put_recv_kbuf(req);
+	/* fast path, check for non-NULL to avoid function call */
+	if (kmsg->free_iov)
+		kfree(kmsg->free_iov);
+	req->flags &= ~REQ_F_NEED_CLEANUP;
+	if (ret >= 0)
+		ret += sr->done_io;
+	else if (sr->done_io)
+		ret = sr->done_io;
+	__io_req_complete(req, issue_flags, ret, cflags);
+	return 0;
+}
+
+static int io_recv(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_buffer *kbuf;
+	struct io_sr_msg *sr = &req->sr_msg;
+	struct msghdr msg;
+	void __user *buf = sr->buf;
+	struct socket *sock;
+	struct iovec iov;
+	unsigned flags;
+	int min_ret = 0;
+	int ret, cflags = 0;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+
+	sock = sock_from_file(req->file, &ret);
+	if (unlikely(!sock))
+		return ret;
+
+	if (req->flags & REQ_F_BUFFER_SELECT) {
+		kbuf = io_recv_buffer_select(req, !force_nonblock);
+		if (IS_ERR(kbuf))
+			return PTR_ERR(kbuf);
+		buf = u64_to_user_ptr(kbuf->addr);
+	}
+
+	ret = import_single_range(READ, buf, sr->len, &iov, &msg.msg_iter);
+	if (unlikely(ret))
+		goto out_free;
+
+	msg.msg_name = NULL;
+	msg.msg_control = NULL;
+	msg.msg_controllen = 0;
+	msg.msg_namelen = 0;
+	msg.msg_iocb = NULL;
+	msg.msg_flags = 0;
+
+	flags = req->sr_msg.msg_flags;
+	if (force_nonblock)
+		flags |= MSG_DONTWAIT;
+	if (flags & MSG_WAITALL)
+		min_ret = iov_iter_count(&msg.msg_iter);
+
+	ret = sock_recvmsg(sock, &msg, flags);
+	if (ret < min_ret) {
+		if (ret == -EAGAIN && force_nonblock)
+			return -EAGAIN;
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
+		if (ret > 0 && io_net_retry(sock, flags)) {
+			sr->len -= ret;
+			sr->buf += ret;
+			sr->done_io += ret;
+			req->flags |= REQ_F_PARTIAL_IO;
+			return -EAGAIN;
+		}
+		req_set_fail(req);
+	} else if ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) {
+out_free:
+		req_set_fail(req);
+	}
+	if (req->flags & REQ_F_BUFFER_SELECTED)
+		cflags = io_put_recv_kbuf(req);
+	if (ret >= 0)
+		ret += sr->done_io;
+	else if (sr->done_io)
+		ret = sr->done_io;
+	__io_req_complete(req, issue_flags, ret, cflags);
+	return 0;
+}
+
+static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_accept *accept = &req->accept;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->len || sqe->buf_index)
+		return -EINVAL;
+
+	accept->addr = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	accept->addr_len = u64_to_user_ptr(READ_ONCE(sqe->addr2));
+	accept->flags = READ_ONCE(sqe->accept_flags);
+	accept->nofile = rlimit(RLIMIT_NOFILE);
+
+	accept->file_slot = READ_ONCE(sqe->file_index);
+	if (accept->file_slot && (accept->flags & SOCK_CLOEXEC))
+		return -EINVAL;
+	if (accept->flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
+		return -EINVAL;
+	if (SOCK_NONBLOCK != O_NONBLOCK && (accept->flags & SOCK_NONBLOCK))
+		accept->flags = (accept->flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
+	return 0;
+}
+
+static int io_accept(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_accept *accept = &req->accept;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+	unsigned int file_flags = force_nonblock ? O_NONBLOCK : 0;
+	bool fixed = !!accept->file_slot;
+	struct file *file;
+	int ret, fd;
+
+	if (!fixed) {
+		fd = __get_unused_fd_flags(accept->flags, accept->nofile);
+		if (unlikely(fd < 0))
+			return fd;
+	}
+	file = do_accept(req->file, file_flags, accept->addr, accept->addr_len,
+			 accept->flags);
+
+	if (IS_ERR(file)) {
+		if (!fixed)
+			put_unused_fd(fd);
+		ret = PTR_ERR(file);
+		/* safe to retry */
+		req->flags |= REQ_F_PARTIAL_IO;
+		if (ret == -EAGAIN && force_nonblock)
+			return -EAGAIN;
+		if (ret == -ERESTARTSYS)
+			ret = -EINTR;
+		req_set_fail(req);
+	} else if (!fixed) {
+		fd_install(fd, file);
+		ret = fd;
+	} else {
+		ret = io_install_fixed_file(req, file, issue_flags,
+					    accept->file_slot - 1);
+	}
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_connect_prep_async(struct io_kiocb *req)
+{
+	struct io_async_connect *io = req->async_data;
+	struct io_connect *conn = &req->connect;
+
+	return move_addr_to_kernel(conn->addr, conn->addr_len, &io->address);
+}
+
+static int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_connect *conn = &req->connect;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->len || sqe->buf_index || sqe->rw_flags ||
+	    sqe->splice_fd_in)
+		return -EINVAL;
+
+	conn->addr = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	conn->addr_len =  READ_ONCE(sqe->addr2);
+	return 0;
+}
+
+static int io_connect(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_async_connect __io, *io;
+	unsigned file_flags;
+	int ret;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+
+	if (req->async_data) {
+		io = req->async_data;
+	} else {
+		ret = move_addr_to_kernel(req->connect.addr,
+						req->connect.addr_len,
+						&__io.address);
+		if (ret)
+			goto out;
+		io = &__io;
+	}
+
+	file_flags = force_nonblock ? O_NONBLOCK : 0;
+
+	ret = __sys_connect_file(req->file, &io->address,
+					req->connect.addr_len, file_flags);
+	if ((ret == -EAGAIN || ret == -EINPROGRESS) && force_nonblock) {
+		if (req->async_data)
+			return -EAGAIN;
+		if (io_alloc_async_data(req)) {
+			ret = -ENOMEM;
+			goto out;
+		}
+		memcpy(req->async_data, &__io, sizeof(__io));
+		return -EAGAIN;
+	}
+	if (ret == -ERESTARTSYS)
+		ret = -EINTR;
+out:
+	if (ret < 0)
+		req_set_fail(req);
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+#else /* !CONFIG_NET */
+#define IO_NETOP_FN(op)							\
+static int io_##op(struct io_kiocb *req, unsigned int issue_flags)	\
+{									\
+	return -EOPNOTSUPP;						\
+}
+
+#define IO_NETOP_PREP(op)						\
+IO_NETOP_FN(op)								\
+static int io_##op##_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) \
+{									\
+	return -EOPNOTSUPP;						\
+}									\
+
+#define IO_NETOP_PREP_ASYNC(op)						\
+IO_NETOP_PREP(op)							\
+static int io_##op##_prep_async(struct io_kiocb *req)			\
+{									\
+	return -EOPNOTSUPP;						\
+}
+
+IO_NETOP_PREP_ASYNC(sendmsg);
+IO_NETOP_PREP_ASYNC(recvmsg);
+IO_NETOP_PREP_ASYNC(connect);
+IO_NETOP_PREP(accept);
+IO_NETOP_FN(send);
+IO_NETOP_FN(recv);
+#endif /* CONFIG_NET */
+
+struct io_poll_table {
+	struct poll_table_struct pt;
+	struct io_kiocb *req;
+	int nr_entries;
+	int error;
+};
+
+#define IO_POLL_CANCEL_FLAG	BIT(31)
+#define IO_POLL_RETRY_FLAG	BIT(30)
+#define IO_POLL_REF_MASK	GENMASK(29, 0)
+
+/*
+ * We usually have 1-2 refs taken, 128 is more than enough and we want to
+ * maximise the margin between this amount and the moment when it overflows.
+ */
+#define IO_POLL_REF_BIAS       128
+
+static bool io_poll_get_ownership_slowpath(struct io_kiocb *req)
+{
+	int v;
+
+	/*
+	 * poll_refs are already elevated and we don't have much hope for
+	 * grabbing the ownership. Instead of incrementing set a retry flag
+	 * to notify the loop that there might have been some change.
+	 */
+	v = atomic_fetch_or(IO_POLL_RETRY_FLAG, &req->poll_refs);
+	if (v & IO_POLL_REF_MASK)
+		return false;
+	return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
+}
+
+/*
+ * If refs part of ->poll_refs (see IO_POLL_REF_MASK) is 0, it's free. We can
+ * bump it and acquire ownership. It's disallowed to modify requests while not
+ * owning it, that prevents from races for enqueueing task_work's and b/w
+ * arming poll and wakeups.
+ */
+static inline bool io_poll_get_ownership(struct io_kiocb *req)
+{
+	if (unlikely(atomic_read(&req->poll_refs) >= IO_POLL_REF_BIAS))
+		return io_poll_get_ownership_slowpath(req);
+	return !(atomic_fetch_inc(&req->poll_refs) & IO_POLL_REF_MASK);
+}
+
+static void io_poll_mark_cancelled(struct io_kiocb *req)
+{
+	atomic_or(IO_POLL_CANCEL_FLAG, &req->poll_refs);
+}
+
+static struct io_poll_iocb *io_poll_get_double(struct io_kiocb *req)
+{
+	/* pure poll stashes this in ->async_data, poll driven retry elsewhere */
+	if (req->opcode == IORING_OP_POLL_ADD)
+		return req->async_data;
+	return req->apoll->double_poll;
+}
+
+static struct io_poll_iocb *io_poll_get_single(struct io_kiocb *req)
+{
+	if (req->opcode == IORING_OP_POLL_ADD)
+		return &req->poll;
+	return &req->apoll->poll;
+}
+
+static void io_poll_req_insert(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct hlist_head *list;
+
+	list = &ctx->cancel_hash[hash_long(req->user_data, ctx->cancel_hash_bits)];
+	hlist_add_head(&req->hash_node, list);
+}
+
+static void io_init_poll_iocb(struct io_poll_iocb *poll, __poll_t events,
+			      wait_queue_func_t wake_func)
+{
+	poll->head = NULL;
+#define IO_POLL_UNMASK	(EPOLLERR|EPOLLHUP|EPOLLNVAL|EPOLLRDHUP)
+	/* mask in events that we always want/need */
+	poll->events = events | IO_POLL_UNMASK;
+	INIT_LIST_HEAD(&poll->wait.entry);
+	init_waitqueue_func_entry(&poll->wait, wake_func);
+}
+
+static inline void io_poll_remove_entry(struct io_poll_iocb *poll)
+{
+	struct wait_queue_head *head = smp_load_acquire(&poll->head);
+
+	if (head) {
+		spin_lock_irq(&head->lock);
+		list_del_init(&poll->wait.entry);
+		poll->head = NULL;
+		spin_unlock_irq(&head->lock);
+	}
+}
+
+static void io_poll_remove_entries(struct io_kiocb *req)
+{
+	struct io_poll_iocb *poll = io_poll_get_single(req);
+	struct io_poll_iocb *poll_double = io_poll_get_double(req);
+
+	/*
+	 * While we hold the waitqueue lock and the waitqueue is nonempty,
+	 * wake_up_pollfree() will wait for us.  However, taking the waitqueue
+	 * lock in the first place can race with the waitqueue being freed.
+	 *
+	 * We solve this as eventpoll does: by taking advantage of the fact that
+	 * all users of wake_up_pollfree() will RCU-delay the actual free.  If
+	 * we enter rcu_read_lock() and see that the pointer to the queue is
+	 * non-NULL, we can then lock it without the memory being freed out from
+	 * under us.
+	 *
+	 * Keep holding rcu_read_lock() as long as we hold the queue lock, in
+	 * case the caller deletes the entry from the queue, leaving it empty.
+	 * In that case, only RCU prevents the queue memory from being freed.
+	 */
+	rcu_read_lock();
+	io_poll_remove_entry(poll);
+	if (poll_double)
+		io_poll_remove_entry(poll_double);
+	rcu_read_unlock();
+}
+
+/*
+ * All poll tw should go through this. Checks for poll events, manages
+ * references, does rewait, etc.
+ *
+ * Returns a negative error on failure. >0 when no action require, which is
+ * either spurious wakeup or multishot CQE is served. 0 when it's done with
+ * the request, then the mask is stored in req->result.
+ */
+static int io_poll_check_events(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_poll_iocb *poll = io_poll_get_single(req);
+	int v;
+
+	/* req->task == current here, checking PF_EXITING is safe */
+	if (unlikely(req->task->flags & PF_EXITING))
+		io_poll_mark_cancelled(req);
+
+	do {
+		v = atomic_read(&req->poll_refs);
+
+		/* tw handler should be the owner, and so have some references */
+		if (WARN_ON_ONCE(!(v & IO_POLL_REF_MASK)))
+			return 0;
+		if (v & IO_POLL_CANCEL_FLAG)
+			return -ECANCELED;
+		/*
+		 * cqe.res contains only events of the first wake up
+		 * and all others are be lost. Redo vfs_poll() to get
+		 * up to date state.
+		 */
+		if ((v & IO_POLL_REF_MASK) != 1)
+			req->result = 0;
+		if (v & IO_POLL_RETRY_FLAG) {
+			req->result = 0;
+			/*
+			 * We won't find new events that came in between
+			 * vfs_poll and the ref put unless we clear the
+			 * flag in advance.
+			 */
+			atomic_andnot(IO_POLL_RETRY_FLAG, &req->poll_refs);
+			v &= ~IO_POLL_RETRY_FLAG;
+		}
+
+		if (!req->result) {
+			struct poll_table_struct pt = { ._key = poll->events };
+
+			req->result = vfs_poll(req->file, &pt) & poll->events;
+		}
+
+		/* multishot, just fill an CQE and proceed */
+		if (req->result && !(poll->events & EPOLLONESHOT)) {
+			__poll_t mask = mangle_poll(req->result & poll->events);
+			bool filled;
+
+			spin_lock(&ctx->completion_lock);
+			filled = io_fill_cqe_aux(ctx, req->user_data, mask,
+						 IORING_CQE_F_MORE);
+			io_commit_cqring(ctx);
+			spin_unlock(&ctx->completion_lock);
+			if (unlikely(!filled))
+				return -ECANCELED;
+			io_cqring_ev_posted(ctx);
+		} else if (req->result) {
+			return 0;
+		}
+
+		/* force the next iteration to vfs_poll() */
+		req->result = 0;
+
+		/*
+		 * Release all references, retry if someone tried to restart
+		 * task_work while we were executing it.
+		 */
+	} while (atomic_sub_return(v & IO_POLL_REF_MASK, &req->poll_refs) &
+					IO_POLL_REF_MASK);
+
+	return 1;
+}
+
+static void io_poll_task_func(struct io_kiocb *req, bool *locked)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
+
+	ret = io_poll_check_events(req);
+	if (ret > 0)
+		return;
+
+	if (!ret) {
+		req->result = mangle_poll(req->result & req->poll.events);
+	} else {
+		req->result = ret;
+		req_set_fail(req);
+	}
+
+	io_poll_remove_entries(req);
+	spin_lock(&ctx->completion_lock);
+	hash_del(&req->hash_node);
+	spin_unlock(&ctx->completion_lock);
+	io_req_complete_post(req, req->result, 0);
+}
+
+static void io_apoll_task_func(struct io_kiocb *req, bool *locked)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
+
+	ret = io_poll_check_events(req);
+	if (ret > 0)
+		return;
+
+	io_tw_lock(req->ctx, locked);
+	io_poll_remove_entries(req);
+	spin_lock(&ctx->completion_lock);
+	hash_del(&req->hash_node);
+	spin_unlock(&ctx->completion_lock);
+
+	if (!ret)
+		io_req_task_submit(req, locked);
+	else
+		io_req_complete_failed(req, ret);
+}
+
+static void __io_poll_execute(struct io_kiocb *req, int mask)
+{
+	req->result = mask;
+	if (req->opcode == IORING_OP_POLL_ADD)
+		req->io_task_work.func = io_poll_task_func;
+	else
+		req->io_task_work.func = io_apoll_task_func;
+
+	trace_io_uring_task_add(req->ctx, req->opcode, req->user_data, mask);
+	io_req_task_work_add(req);
+}
+
+static inline void io_poll_execute(struct io_kiocb *req, int res)
+{
+	if (io_poll_get_ownership(req))
+		__io_poll_execute(req, res);
+}
+
+static void io_poll_cancel_req(struct io_kiocb *req)
+{
+	io_poll_mark_cancelled(req);
+	/* kick tw, which should complete the request */
+	io_poll_execute(req, 0);
+}
+
+static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
+			void *key)
+{
+	struct io_kiocb *req = wait->private;
+	struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
+						 wait);
+	__poll_t mask = key_to_poll(key);
+
+	if (unlikely(mask & POLLFREE)) {
+		io_poll_mark_cancelled(req);
+		/* we have to kick tw in case it's not already */
+		io_poll_execute(req, 0);
+
+		/*
+		 * If the waitqueue is being freed early but someone is already
+		 * holds ownership over it, we have to tear down the request as
+		 * best we can. That means immediately removing the request from
+		 * its waitqueue and preventing all further accesses to the
+		 * waitqueue via the request.
+		 */
+		list_del_init(&poll->wait.entry);
+
+		/*
+		 * Careful: this *must* be the last step, since as soon
+		 * as req->head is NULL'ed out, the request can be
+		 * completed and freed, since aio_poll_complete_work()
+		 * will no longer need to take the waitqueue lock.
+		 */
+		smp_store_release(&poll->head, NULL);
+		return 1;
+	}
+
+	/* for instances that support it check for an event match first */
+	if (mask && !(mask & poll->events))
+		return 0;
+
+	if (io_poll_get_ownership(req)) {
+		/*
+		 * If we trigger a multishot poll off our own wakeup path,
+		 * disable multishot as there is a circular dependency between
+		 * CQ posting and triggering the event.
+		 */
+		if (mask & EPOLL_URING_WAKE)
+			poll->events |= EPOLLONESHOT;
+
+		__io_poll_execute(req, mask);
+	}
+	return 1;
+}
+
+static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
+			    struct wait_queue_head *head,
+			    struct io_poll_iocb **poll_ptr)
+{
+	struct io_kiocb *req = pt->req;
+
+	/*
+	 * The file being polled uses multiple waitqueues for poll handling
+	 * (e.g. one for read, one for write). Setup a separate io_poll_iocb
+	 * if this happens.
+	 */
+	if (unlikely(pt->nr_entries)) {
+		struct io_poll_iocb *first = poll;
+
+		/* double add on the same waitqueue head, ignore */
+		if (first->head == head)
+			return;
+		/* already have a 2nd entry, fail a third attempt */
+		if (*poll_ptr) {
+			if ((*poll_ptr)->head == head)
+				return;
+			pt->error = -EINVAL;
+			return;
+		}
+
+		poll = kmalloc(sizeof(*poll), GFP_ATOMIC);
+		if (!poll) {
+			pt->error = -ENOMEM;
+			return;
+		}
+		io_init_poll_iocb(poll, first->events, first->wait.func);
+		*poll_ptr = poll;
+	}
+
+	pt->nr_entries++;
+	poll->head = head;
+	poll->wait.private = req;
+
+	if (poll->events & EPOLLEXCLUSIVE)
+		add_wait_queue_exclusive(head, &poll->wait);
+	else
+		add_wait_queue(head, &poll->wait);
+}
+
+static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
+			       struct poll_table_struct *p)
+{
+	struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);
+
+	__io_queue_proc(&pt->req->poll, pt, head,
+			(struct io_poll_iocb **) &pt->req->async_data);
+}
+
+static int __io_arm_poll_handler(struct io_kiocb *req,
+				 struct io_poll_iocb *poll,
+				 struct io_poll_table *ipt, __poll_t mask)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	INIT_HLIST_NODE(&req->hash_node);
+	io_init_poll_iocb(poll, mask, io_poll_wake);
+	poll->file = req->file;
+	poll->wait.private = req;
+
+	ipt->pt._key = mask;
+	ipt->req = req;
+	ipt->error = 0;
+	ipt->nr_entries = 0;
+
+	/*
+	 * Take the ownership to delay any tw execution up until we're done
+	 * with poll arming. see io_poll_get_ownership().
+	 */
+	atomic_set(&req->poll_refs, 1);
+	mask = vfs_poll(req->file, &ipt->pt) & poll->events;
+
+	if (mask && (poll->events & EPOLLONESHOT)) {
+		io_poll_remove_entries(req);
+		/* no one else has access to the req, forget about the ref */
+		return mask;
+	}
+	if (!mask && unlikely(ipt->error || !ipt->nr_entries)) {
+		io_poll_remove_entries(req);
+		if (!ipt->error)
+			ipt->error = -EINVAL;
+		return 0;
+	}
+
+	spin_lock(&ctx->completion_lock);
+	io_poll_req_insert(req);
+	spin_unlock(&ctx->completion_lock);
+
+	if (mask) {
+		/* can't multishot if failed, just queue the event we've got */
+		if (unlikely(ipt->error || !ipt->nr_entries)) {
+			poll->events |= EPOLLONESHOT;
+			ipt->error = 0;
+		}
+		__io_poll_execute(req, mask);
+		return 0;
+	}
+
+	/*
+	 * Try to release ownership. If we see a change of state, e.g.
+	 * poll was waken up, queue up a tw, it'll deal with it.
+	 */
+	if (atomic_cmpxchg(&req->poll_refs, 1, 0) != 1)
+		__io_poll_execute(req, 0);
+	return 0;
+}
+
+static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,
+			       struct poll_table_struct *p)
+{
+	struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);
+	struct async_poll *apoll = pt->req->apoll;
+
+	__io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll);
+}
+
+enum {
+	IO_APOLL_OK,
+	IO_APOLL_ABORTED,
+	IO_APOLL_READY
+};
+
+/*
+ * We can't reliably detect loops in repeated poll triggers and issue
+ * subsequently failing. But rather than fail these immediately, allow a
+ * certain amount of retries before we give up. Given that this condition
+ * should _rarely_ trigger even once, we should be fine with a larger value.
+ */
+#define APOLL_MAX_RETRY		128
+
+static int io_arm_poll_handler(struct io_kiocb *req)
+{
+	const struct io_op_def *def = &io_op_defs[req->opcode];
+	struct io_ring_ctx *ctx = req->ctx;
+	struct async_poll *apoll;
+	struct io_poll_table ipt;
+	__poll_t mask = EPOLLONESHOT | POLLERR | POLLPRI;
+	int ret;
+
+	if (!req->file || !file_can_poll(req->file))
+		return IO_APOLL_ABORTED;
+	if (!def->pollin && !def->pollout)
+		return IO_APOLL_ABORTED;
+
+	if (def->pollin) {
+		mask |= POLLIN | POLLRDNORM;
+
+		/* If reading from MSG_ERRQUEUE using recvmsg, ignore POLLIN */
+		if ((req->opcode == IORING_OP_RECVMSG) &&
+		    (req->sr_msg.msg_flags & MSG_ERRQUEUE))
+			mask &= ~POLLIN;
+	} else {
+		mask |= POLLOUT | POLLWRNORM;
+	}
+
+	if (req->flags & REQ_F_POLLED) {
+		apoll = req->apoll;
+		kfree(apoll->double_poll);
+		if (unlikely(!--apoll->poll.retries)) {
+			apoll->double_poll = NULL;
+			return IO_APOLL_ABORTED;
+		}
+	} else {
+		apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);
+		if (unlikely(!apoll))
+			return IO_APOLL_ABORTED;
+		apoll->poll.retries = APOLL_MAX_RETRY;
+	}
+	apoll->double_poll = NULL;
+	req->apoll = apoll;
+	req->flags |= REQ_F_POLLED;
+	ipt.pt._qproc = io_async_queue_proc;
+
+	ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask);
+	if (ret || ipt.error)
+		return ret ? IO_APOLL_READY : IO_APOLL_ABORTED;
+
+	trace_io_uring_poll_arm(ctx, req, req->opcode, req->user_data,
+				mask, apoll->poll.events);
+	return IO_APOLL_OK;
+}
+
+/*
+ * Returns true if we found and killed one or more poll requests
+ */
+static bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
+			       bool cancel_all)
+{
+	struct hlist_node *tmp;
+	struct io_kiocb *req;
+	bool found = false;
+	int i;
+
+	spin_lock(&ctx->completion_lock);
+	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
+		struct hlist_head *list;
+
+		list = &ctx->cancel_hash[i];
+		hlist_for_each_entry_safe(req, tmp, list, hash_node) {
+			if (io_match_task_safe(req, tsk, cancel_all)) {
+				hlist_del_init(&req->hash_node);
+				io_poll_cancel_req(req);
+				found = true;
+			}
+		}
+	}
+	spin_unlock(&ctx->completion_lock);
+	return found;
+}
+
+static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, __u64 sqe_addr,
+				     bool poll_only)
+	__must_hold(&ctx->completion_lock)
+{
+	struct hlist_head *list;
+	struct io_kiocb *req;
+
+	list = &ctx->cancel_hash[hash_long(sqe_addr, ctx->cancel_hash_bits)];
+	hlist_for_each_entry(req, list, hash_node) {
+		if (sqe_addr != req->user_data)
+			continue;
+		if (poll_only && req->opcode != IORING_OP_POLL_ADD)
+			continue;
+		return req;
+	}
+	return NULL;
+}
+
+static bool io_poll_disarm(struct io_kiocb *req)
+	__must_hold(&ctx->completion_lock)
+{
+	if (!io_poll_get_ownership(req))
+		return false;
+	io_poll_remove_entries(req);
+	hash_del(&req->hash_node);
+	return true;
+}
+
+static int io_poll_cancel(struct io_ring_ctx *ctx, __u64 sqe_addr,
+			  bool poll_only)
+	__must_hold(&ctx->completion_lock)
+{
+	struct io_kiocb *req = io_poll_find(ctx, sqe_addr, poll_only);
+
+	if (!req)
+		return -ENOENT;
+	io_poll_cancel_req(req);
+	return 0;
+}
+
+static __poll_t io_poll_parse_events(const struct io_uring_sqe *sqe,
+				     unsigned int flags)
+{
+	u32 events;
+
+	events = READ_ONCE(sqe->poll32_events);
+#ifdef __BIG_ENDIAN
+	events = swahw32(events);
+#endif
+	if (!(flags & IORING_POLL_ADD_MULTI))
+		events |= EPOLLONESHOT;
+	return demangle_poll(events) | (events & (EPOLLEXCLUSIVE|EPOLLONESHOT));
+}
+
+static int io_poll_update_prep(struct io_kiocb *req,
+			       const struct io_uring_sqe *sqe)
+{
+	struct io_poll_update *upd = &req->poll_update;
+	u32 flags;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
+		return -EINVAL;
+	flags = READ_ONCE(sqe->len);
+	if (flags & ~(IORING_POLL_UPDATE_EVENTS | IORING_POLL_UPDATE_USER_DATA |
+		      IORING_POLL_ADD_MULTI))
+		return -EINVAL;
+	/* meaningless without update */
+	if (flags == IORING_POLL_ADD_MULTI)
+		return -EINVAL;
+
+	upd->old_user_data = READ_ONCE(sqe->addr);
+	upd->update_events = flags & IORING_POLL_UPDATE_EVENTS;
+	upd->update_user_data = flags & IORING_POLL_UPDATE_USER_DATA;
+
+	upd->new_user_data = READ_ONCE(sqe->off);
+	if (!upd->update_user_data && upd->new_user_data)
+		return -EINVAL;
+	if (upd->update_events)
+		upd->events = io_poll_parse_events(sqe, flags);
+	else if (sqe->poll32_events)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_poll_iocb *poll = &req->poll;
+	u32 flags;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->buf_index || sqe->off || sqe->addr)
+		return -EINVAL;
+	flags = READ_ONCE(sqe->len);
+	if (flags & ~IORING_POLL_ADD_MULTI)
+		return -EINVAL;
+
+	io_req_set_refcount(req);
+	poll->events = io_poll_parse_events(sqe, flags);
+	return 0;
+}
+
+static int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_poll_iocb *poll = &req->poll;
+	struct io_poll_table ipt;
+	int ret;
+
+	ipt.pt._qproc = io_poll_queue_proc;
+
+	ret = __io_arm_poll_handler(req, &req->poll, &ipt, poll->events);
+	if (!ret && ipt.error)
+		req_set_fail(req);
+	ret = ret ?: ipt.error;
+	if (ret)
+		__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_poll_update(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_kiocb *preq;
+	int ret2, ret = 0;
+
+	io_ring_submit_lock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+
+	spin_lock(&ctx->completion_lock);
+	preq = io_poll_find(ctx, req->poll_update.old_user_data, true);
+	if (!preq || !io_poll_disarm(preq)) {
+		spin_unlock(&ctx->completion_lock);
+		ret = preq ? -EALREADY : -ENOENT;
+		goto out;
+	}
+	spin_unlock(&ctx->completion_lock);
+
+	if (req->poll_update.update_events || req->poll_update.update_user_data) {
+		/* only mask one event flags, keep behavior flags */
+		if (req->poll_update.update_events) {
+			preq->poll.events &= ~0xffff;
+			preq->poll.events |= req->poll_update.events & 0xffff;
+			preq->poll.events |= IO_POLL_UNMASK;
+		}
+		if (req->poll_update.update_user_data)
+			preq->user_data = req->poll_update.new_user_data;
+
+		ret2 = io_poll_add(preq, issue_flags);
+		/* successfully updated, don't complete poll request */
+		if (!ret2)
+			goto out;
+	}
+	req_set_fail(preq);
+	io_req_complete(preq, -ECANCELED);
+out:
+	if (ret < 0)
+		req_set_fail(req);
+	/* complete update request, we're done with it */
+	io_req_complete(req, ret);
+	io_ring_submit_unlock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+	return 0;
+}
+
+static void io_req_task_timeout(struct io_kiocb *req, bool *locked)
+{
+	req_set_fail(req);
+	io_req_complete_post(req, -ETIME, 0);
+}
+
+static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
+{
+	struct io_timeout_data *data = container_of(timer,
+						struct io_timeout_data, timer);
+	struct io_kiocb *req = data->req;
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->timeout_lock, flags);
+	list_del_init(&req->timeout.list);
+	atomic_set(&req->ctx->cq_timeouts,
+		atomic_read(&req->ctx->cq_timeouts) + 1);
+	spin_unlock_irqrestore(&ctx->timeout_lock, flags);
+
+	req->io_task_work.func = io_req_task_timeout;
+	io_req_task_work_add(req);
+	return HRTIMER_NORESTART;
+}
+
+static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
+					   __u64 user_data)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_timeout_data *io;
+	struct io_kiocb *req;
+	bool found = false;
+
+	list_for_each_entry(req, &ctx->timeout_list, timeout.list) {
+		found = user_data == req->user_data;
+		if (found)
+			break;
+	}
+	if (!found)
+		return ERR_PTR(-ENOENT);
+
+	io = req->async_data;
+	if (hrtimer_try_to_cancel(&io->timer) == -1)
+		return ERR_PTR(-EALREADY);
+	list_del_init(&req->timeout.list);
+	return req;
+}
+
+static int io_timeout_cancel(struct io_ring_ctx *ctx, __u64 user_data)
+	__must_hold(&ctx->completion_lock)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_kiocb *req = io_timeout_extract(ctx, user_data);
+
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	req_set_fail(req);
+	io_fill_cqe_req(req, -ECANCELED, 0);
+	io_put_req_deferred(req);
+	return 0;
+}
+
+static clockid_t io_timeout_get_clock(struct io_timeout_data *data)
+{
+	switch (data->flags & IORING_TIMEOUT_CLOCK_MASK) {
+	case IORING_TIMEOUT_BOOTTIME:
+		return CLOCK_BOOTTIME;
+	case IORING_TIMEOUT_REALTIME:
+		return CLOCK_REALTIME;
+	default:
+		/* can't happen, vetted at prep time */
+		WARN_ON_ONCE(1);
+		fallthrough;
+	case 0:
+		return CLOCK_MONOTONIC;
+	}
+}
+
+static int io_linked_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
+				    struct timespec64 *ts, enum hrtimer_mode mode)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_timeout_data *io;
+	struct io_kiocb *req;
+	bool found = false;
+
+	list_for_each_entry(req, &ctx->ltimeout_list, timeout.list) {
+		found = user_data == req->user_data;
+		if (found)
+			break;
+	}
+	if (!found)
+		return -ENOENT;
+
+	io = req->async_data;
+	if (hrtimer_try_to_cancel(&io->timer) == -1)
+		return -EALREADY;
+	hrtimer_init(&io->timer, io_timeout_get_clock(io), mode);
+	io->timer.function = io_link_timeout_fn;
+	hrtimer_start(&io->timer, timespec64_to_ktime(*ts), mode);
+	return 0;
+}
+
+static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
+			     struct timespec64 *ts, enum hrtimer_mode mode)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_kiocb *req = io_timeout_extract(ctx, user_data);
+	struct io_timeout_data *data;
+
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	req->timeout.off = 0; /* noseq */
+	data = req->async_data;
+	list_add_tail(&req->timeout.list, &ctx->timeout_list);
+	hrtimer_init(&data->timer, io_timeout_get_clock(data), mode);
+	data->timer.function = io_timeout_fn;
+	hrtimer_start(&data->timer, timespec64_to_ktime(*ts), mode);
+	return 0;
+}
+
+static int io_timeout_remove_prep(struct io_kiocb *req,
+				  const struct io_uring_sqe *sqe)
+{
+	struct io_timeout_rem *tr = &req->timeout_rem;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->buf_index || sqe->len || sqe->splice_fd_in)
+		return -EINVAL;
+
+	tr->ltimeout = false;
+	tr->addr = READ_ONCE(sqe->addr);
+	tr->flags = READ_ONCE(sqe->timeout_flags);
+	if (tr->flags & IORING_TIMEOUT_UPDATE_MASK) {
+		if (hweight32(tr->flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
+			return -EINVAL;
+		if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
+			tr->ltimeout = true;
+		if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK|IORING_TIMEOUT_ABS))
+			return -EINVAL;
+		if (get_timespec64(&tr->ts, u64_to_user_ptr(sqe->addr2)))
+			return -EFAULT;
+	} else if (tr->flags) {
+		/* timeout removal doesn't support flags */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static inline enum hrtimer_mode io_translate_timeout_mode(unsigned int flags)
+{
+	return (flags & IORING_TIMEOUT_ABS) ? HRTIMER_MODE_ABS
+					    : HRTIMER_MODE_REL;
+}
+
+/*
+ * Remove or update an existing timeout command
+ */
+static int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_timeout_rem *tr = &req->timeout_rem;
+	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
+
+	if (!(req->timeout_rem.flags & IORING_TIMEOUT_UPDATE)) {
+		spin_lock(&ctx->completion_lock);
+		spin_lock_irq(&ctx->timeout_lock);
+		ret = io_timeout_cancel(ctx, tr->addr);
+		spin_unlock_irq(&ctx->timeout_lock);
+		spin_unlock(&ctx->completion_lock);
+	} else {
+		enum hrtimer_mode mode = io_translate_timeout_mode(tr->flags);
+
+		spin_lock_irq(&ctx->timeout_lock);
+		if (tr->ltimeout)
+			ret = io_linked_timeout_update(ctx, tr->addr, &tr->ts, mode);
+		else
+			ret = io_timeout_update(ctx, tr->addr, &tr->ts, mode);
+		spin_unlock_irq(&ctx->timeout_lock);
+	}
+
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete_post(req, ret, 0);
+	return 0;
+}
+
+static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+			   bool is_timeout_link)
+{
+	struct io_timeout_data *data;
+	unsigned flags;
+	u32 off = READ_ONCE(sqe->off);
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->buf_index || sqe->len != 1 ||
+	    sqe->splice_fd_in)
+		return -EINVAL;
+	if (off && is_timeout_link)
+		return -EINVAL;
+	flags = READ_ONCE(sqe->timeout_flags);
+	if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK))
+		return -EINVAL;
+	/* more than one clock specified is invalid, obviously */
+	if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
+		return -EINVAL;
+
+	INIT_LIST_HEAD(&req->timeout.list);
+	req->timeout.off = off;
+	if (unlikely(off && !req->ctx->off_timeout_used))
+		req->ctx->off_timeout_used = true;
+
+	if (!req->async_data && io_alloc_async_data(req))
+		return -ENOMEM;
+
+	data = req->async_data;
+	data->req = req;
+	data->flags = flags;
+
+	if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
+		return -EFAULT;
+
+	INIT_LIST_HEAD(&req->timeout.list);
+	data->mode = io_translate_timeout_mode(flags);
+	hrtimer_init(&data->timer, io_timeout_get_clock(data), data->mode);
+
+	if (is_timeout_link) {
+		struct io_submit_link *link = &req->ctx->submit_state.link;
+
+		if (!link->head)
+			return -EINVAL;
+		if (link->last->opcode == IORING_OP_LINK_TIMEOUT)
+			return -EINVAL;
+		req->timeout.head = link->last;
+		link->last->flags |= REQ_F_ARM_LTIMEOUT;
+	}
+	return 0;
+}
+
+static int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_timeout_data *data = req->async_data;
+	struct list_head *entry;
+	u32 tail, off = req->timeout.off;
+
+	spin_lock_irq(&ctx->timeout_lock);
+
+	/*
+	 * sqe->off holds how many events that need to occur for this
+	 * timeout event to be satisfied. If it isn't set, then this is
+	 * a pure timeout request, sequence isn't used.
+	 */
+	if (io_is_timeout_noseq(req)) {
+		entry = ctx->timeout_list.prev;
+		goto add;
+	}
+
+	tail = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts);
+	req->timeout.target_seq = tail + off;
+
+	/* Update the last seq here in case io_flush_timeouts() hasn't.
+	 * This is safe because ->completion_lock is held, and submissions
+	 * and completions are never mixed in the same ->completion_lock section.
+	 */
+	ctx->cq_last_tm_flush = tail;
+
+	/*
+	 * Insertion sort, ensuring the first entry in the list is always
+	 * the one we need first.
+	 */
+	list_for_each_prev(entry, &ctx->timeout_list) {
+		struct io_kiocb *nxt = list_entry(entry, struct io_kiocb,
+						  timeout.list);
+
+		if (io_is_timeout_noseq(nxt))
+			continue;
+		/* nxt.seq is behind @tail, otherwise would've been completed */
+		if (off >= nxt->timeout.target_seq - tail)
+			break;
+	}
+add:
+	list_add(&req->timeout.list, entry);
+	data->timer.function = io_timeout_fn;
+	hrtimer_start(&data->timer, timespec64_to_ktime(data->ts), data->mode);
+	spin_unlock_irq(&ctx->timeout_lock);
+	return 0;
+}
+
+struct io_cancel_data {
+	struct io_ring_ctx *ctx;
+	u64 user_data;
+};
+
+static bool io_cancel_cb(struct io_wq_work *work, void *data)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	struct io_cancel_data *cd = data;
+
+	return req->ctx == cd->ctx && req->user_data == cd->user_data;
+}
+
+static int io_async_cancel_one(struct io_uring_task *tctx, u64 user_data,
+			       struct io_ring_ctx *ctx)
+{
+	struct io_cancel_data data = { .ctx = ctx, .user_data = user_data, };
+	enum io_wq_cancel cancel_ret;
+	int ret = 0;
+
+	if (!tctx || !tctx->io_wq)
+		return -ENOENT;
+
+	cancel_ret = io_wq_cancel_cb(tctx->io_wq, io_cancel_cb, &data, false);
+	switch (cancel_ret) {
+	case IO_WQ_CANCEL_OK:
+		ret = 0;
+		break;
+	case IO_WQ_CANCEL_RUNNING:
+		ret = -EALREADY;
+		break;
+	case IO_WQ_CANCEL_NOTFOUND:
+		ret = -ENOENT;
+		break;
+	}
+
+	return ret;
+}
+
+static int io_try_cancel_userdata(struct io_kiocb *req, u64 sqe_addr)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
+
+	WARN_ON_ONCE(!io_wq_current_is_worker() && req->task != current);
+
+	ret = io_async_cancel_one(req->task->io_uring, sqe_addr, ctx);
+	if (ret != -ENOENT)
+		return ret;
+
+	spin_lock(&ctx->completion_lock);
+	spin_lock_irq(&ctx->timeout_lock);
+	ret = io_timeout_cancel(ctx, sqe_addr);
+	spin_unlock_irq(&ctx->timeout_lock);
+	if (ret != -ENOENT)
+		goto out;
+	ret = io_poll_cancel(ctx, sqe_addr, false);
+out:
+	spin_unlock(&ctx->completion_lock);
+	return ret;
+}
+
+static int io_async_cancel_prep(struct io_kiocb *req,
+				const struct io_uring_sqe *sqe)
+{
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->off || sqe->len || sqe->cancel_flags ||
+	    sqe->splice_fd_in)
+		return -EINVAL;
+
+	req->cancel.addr = READ_ONCE(sqe->addr);
+	return 0;
+}
+
+static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	u64 sqe_addr = req->cancel.addr;
+	struct io_tctx_node *node;
+	int ret;
+
+	ret = io_try_cancel_userdata(req, sqe_addr);
+	if (ret != -ENOENT)
+		goto done;
+
+	/* slow path, try all io-wq's */
+	io_ring_submit_lock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+	ret = -ENOENT;
+	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
+		struct io_uring_task *tctx = node->task->io_uring;
+
+		ret = io_async_cancel_one(tctx, req->cancel.addr, ctx);
+		if (ret != -ENOENT)
+			break;
+	}
+	io_ring_submit_unlock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+done:
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_complete_post(req, ret, 0);
+	return 0;
+}
+
+static int io_rsrc_update_prep(struct io_kiocb *req,
+				const struct io_uring_sqe *sqe)
+{
+	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->rw_flags || sqe->splice_fd_in)
+		return -EINVAL;
+
+	req->rsrc_update.offset = READ_ONCE(sqe->off);
+	req->rsrc_update.nr_args = READ_ONCE(sqe->len);
+	if (!req->rsrc_update.nr_args)
+		return -EINVAL;
+	req->rsrc_update.arg = READ_ONCE(sqe->addr);
+	return 0;
+}
+
+static int io_files_update(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_uring_rsrc_update2 up;
+	int ret;
+
+	up.offset = req->rsrc_update.offset;
+	up.data = req->rsrc_update.arg;
+	up.nr = 0;
+	up.tags = 0;
+	up.resv = 0;
+	up.resv2 = 0;
+
+	io_ring_submit_lock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+	ret = __io_register_rsrc_update(ctx, IORING_RSRC_FILE,
+					&up, req->rsrc_update.nr_args);
+	io_ring_submit_unlock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+
+	if (ret < 0)
+		req_set_fail(req);
+	__io_req_complete(req, issue_flags, ret, 0);
+	return 0;
+}
+
+static int io_req_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	switch (req->opcode) {
+	case IORING_OP_NOP:
+		return 0;
+	case IORING_OP_READV:
+	case IORING_OP_READ_FIXED:
+	case IORING_OP_READ:
+		return io_read_prep(req, sqe);
+	case IORING_OP_WRITEV:
+	case IORING_OP_WRITE_FIXED:
+	case IORING_OP_WRITE:
+		return io_write_prep(req, sqe);
+	case IORING_OP_POLL_ADD:
+		return io_poll_add_prep(req, sqe);
+	case IORING_OP_POLL_REMOVE:
+		return io_poll_update_prep(req, sqe);
+	case IORING_OP_FSYNC:
+		return io_fsync_prep(req, sqe);
+	case IORING_OP_SYNC_FILE_RANGE:
+		return io_sfr_prep(req, sqe);
+	case IORING_OP_SENDMSG:
+	case IORING_OP_SEND:
+		return io_sendmsg_prep(req, sqe);
+	case IORING_OP_RECVMSG:
+	case IORING_OP_RECV:
+		return io_recvmsg_prep(req, sqe);
+	case IORING_OP_CONNECT:
+		return io_connect_prep(req, sqe);
+	case IORING_OP_TIMEOUT:
+		return io_timeout_prep(req, sqe, false);
+	case IORING_OP_TIMEOUT_REMOVE:
+		return io_timeout_remove_prep(req, sqe);
+	case IORING_OP_ASYNC_CANCEL:
+		return io_async_cancel_prep(req, sqe);
+	case IORING_OP_LINK_TIMEOUT:
+		return io_timeout_prep(req, sqe, true);
+	case IORING_OP_ACCEPT:
+		return io_accept_prep(req, sqe);
+	case IORING_OP_FALLOCATE:
+		return io_fallocate_prep(req, sqe);
+	case IORING_OP_OPENAT:
+		return io_openat_prep(req, sqe);
+	case IORING_OP_CLOSE:
+		return io_close_prep(req, sqe);
+	case IORING_OP_FILES_UPDATE:
+		return io_rsrc_update_prep(req, sqe);
+	case IORING_OP_STATX:
+		return io_statx_prep(req, sqe);
+	case IORING_OP_FADVISE:
+		return io_fadvise_prep(req, sqe);
+	case IORING_OP_MADVISE:
+		return io_madvise_prep(req, sqe);
+	case IORING_OP_OPENAT2:
+		return io_openat2_prep(req, sqe);
+	case IORING_OP_EPOLL_CTL:
+		return io_epoll_ctl_prep(req, sqe);
+	case IORING_OP_SPLICE:
+		return io_splice_prep(req, sqe);
+	case IORING_OP_PROVIDE_BUFFERS:
+		return io_provide_buffers_prep(req, sqe);
+	case IORING_OP_REMOVE_BUFFERS:
+		return io_remove_buffers_prep(req, sqe);
+	case IORING_OP_TEE:
+		return io_tee_prep(req, sqe);
+	case IORING_OP_SHUTDOWN:
+		return io_shutdown_prep(req, sqe);
+	case IORING_OP_RENAMEAT:
+		return io_renameat_prep(req, sqe);
+	case IORING_OP_UNLINKAT:
+		return io_unlinkat_prep(req, sqe);
+	}
+
+	printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
+			req->opcode);
+	return -EINVAL;
+}
+
+static int io_req_prep_async(struct io_kiocb *req)
+{
+	if (!io_op_defs[req->opcode].needs_async_setup)
+		return 0;
+	if (WARN_ON_ONCE(req->async_data))
+		return -EFAULT;
+	if (io_alloc_async_data(req))
+		return -EAGAIN;
+
+	switch (req->opcode) {
+	case IORING_OP_READV:
+		return io_rw_prep_async(req, READ);
+	case IORING_OP_WRITEV:
+		return io_rw_prep_async(req, WRITE);
+	case IORING_OP_SENDMSG:
+		return io_sendmsg_prep_async(req);
+	case IORING_OP_RECVMSG:
+		return io_recvmsg_prep_async(req);
+	case IORING_OP_CONNECT:
+		return io_connect_prep_async(req);
+	}
+	printk_once(KERN_WARNING "io_uring: prep_async() bad opcode %d\n",
+		    req->opcode);
+	return -EFAULT;
+}
+
+static u32 io_get_sequence(struct io_kiocb *req)
+{
+	u32 seq = req->ctx->cached_sq_head;
+
+	/* need original cached_sq_head, but it was increased for each req */
+	io_for_each_link(req, req)
+		seq--;
+	return seq;
+}
+
+static bool io_drain_req(struct io_kiocb *req)
+{
+	struct io_kiocb *pos;
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_defer_entry *de;
+	int ret;
+	u32 seq;
+
+	if (req->flags & REQ_F_FAIL) {
+		io_req_complete_fail_submit(req);
+		return true;
+	}
+
+	/*
+	 * 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, IOSQE_IO_DRAIN will be
+	 * maintained for every request of our link.
+	 */
+	if (ctx->drain_next) {
+		req->flags |= REQ_F_IO_DRAIN;
+		ctx->drain_next = false;
+	}
+	/* not interested in head, start from the first linked */
+	io_for_each_link(pos, req->link) {
+		if (pos->flags & REQ_F_IO_DRAIN) {
+			ctx->drain_next = true;
+			req->flags |= REQ_F_IO_DRAIN;
+			break;
+		}
+	}
+
+	/* Still need defer if there is pending req in defer list. */
+	spin_lock(&ctx->completion_lock);
+	if (likely(list_empty_careful(&ctx->defer_list) &&
+		!(req->flags & REQ_F_IO_DRAIN))) {
+		spin_unlock(&ctx->completion_lock);
+		ctx->drain_active = false;
+		return false;
+	}
+	spin_unlock(&ctx->completion_lock);
+
+	seq = io_get_sequence(req);
+	/* Still a chance to pass the sequence check */
+	if (!req_need_defer(req, seq) && list_empty_careful(&ctx->defer_list))
+		return false;
+
+	ret = io_req_prep_async(req);
+	if (ret)
+		goto fail;
+	io_prep_async_link(req);
+	de = kmalloc(sizeof(*de), GFP_KERNEL);
+	if (!de) {
+		ret = -ENOMEM;
+fail:
+		io_req_complete_failed(req, ret);
+		return true;
+	}
+
+	spin_lock(&ctx->completion_lock);
+	if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
+		spin_unlock(&ctx->completion_lock);
+		kfree(de);
+		io_queue_async_work(req, NULL);
+		return true;
+	}
+
+	trace_io_uring_defer(ctx, req, req->user_data);
+	de->req = req;
+	de->seq = seq;
+	list_add_tail(&de->list, &ctx->defer_list);
+	spin_unlock(&ctx->completion_lock);
+	return true;
+}
+
+static void io_clean_op(struct io_kiocb *req)
+{
+	if (req->flags & REQ_F_BUFFER_SELECTED) {
+		switch (req->opcode) {
+		case IORING_OP_READV:
+		case IORING_OP_READ_FIXED:
+		case IORING_OP_READ:
+			kfree((void *)(unsigned long)req->rw.addr);
+			break;
+		case IORING_OP_RECVMSG:
+		case IORING_OP_RECV:
+			kfree(req->sr_msg.kbuf);
+			break;
+		}
+	}
+
+	if (req->flags & REQ_F_NEED_CLEANUP) {
+		switch (req->opcode) {
+		case IORING_OP_READV:
+		case IORING_OP_READ_FIXED:
+		case IORING_OP_READ:
+		case IORING_OP_WRITEV:
+		case IORING_OP_WRITE_FIXED:
+		case IORING_OP_WRITE: {
+			struct io_async_rw *io = req->async_data;
+
+			kfree(io->free_iovec);
+			break;
+			}
+		case IORING_OP_RECVMSG:
+		case IORING_OP_SENDMSG: {
+			struct io_async_msghdr *io = req->async_data;
+
+			kfree(io->free_iov);
+			break;
+			}
+		case IORING_OP_OPENAT:
+		case IORING_OP_OPENAT2:
+			if (req->open.filename)
+				putname(req->open.filename);
+			break;
+		case IORING_OP_RENAMEAT:
+			putname(req->rename.oldpath);
+			putname(req->rename.newpath);
+			break;
+		case IORING_OP_UNLINKAT:
+			putname(req->unlink.filename);
+			break;
+		}
+	}
+	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);
+
+	req->flags &= ~IO_REQ_CLEAN_FLAGS;
+}
+
+static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	const struct cred *creds = NULL;
+	int ret;
+
+	if ((req->flags & REQ_F_CREDS) && req->creds != current_cred())
+		creds = override_creds(req->creds);
+
+	switch (req->opcode) {
+	case IORING_OP_NOP:
+		ret = io_nop(req, issue_flags);
+		break;
+	case IORING_OP_READV:
+	case IORING_OP_READ_FIXED:
+	case IORING_OP_READ:
+		ret = io_read(req, issue_flags);
+		break;
+	case IORING_OP_WRITEV:
+	case IORING_OP_WRITE_FIXED:
+	case IORING_OP_WRITE:
+		ret = io_write(req, issue_flags);
+		break;
+	case IORING_OP_FSYNC:
+		ret = io_fsync(req, issue_flags);
+		break;
+	case IORING_OP_POLL_ADD:
+		ret = io_poll_add(req, issue_flags);
+		break;
+	case IORING_OP_POLL_REMOVE:
+		ret = io_poll_update(req, issue_flags);
+		break;
+	case IORING_OP_SYNC_FILE_RANGE:
+		ret = io_sync_file_range(req, issue_flags);
+		break;
+	case IORING_OP_SENDMSG:
+		ret = io_sendmsg(req, issue_flags);
+		break;
+	case IORING_OP_SEND:
+		ret = io_send(req, issue_flags);
+		break;
+	case IORING_OP_RECVMSG:
+		ret = io_recvmsg(req, issue_flags);
+		break;
+	case IORING_OP_RECV:
+		ret = io_recv(req, issue_flags);
+		break;
+	case IORING_OP_TIMEOUT:
+		ret = io_timeout(req, issue_flags);
+		break;
+	case IORING_OP_TIMEOUT_REMOVE:
+		ret = io_timeout_remove(req, issue_flags);
+		break;
+	case IORING_OP_ACCEPT:
+		ret = io_accept(req, issue_flags);
+		break;
+	case IORING_OP_CONNECT:
+		ret = io_connect(req, issue_flags);
+		break;
+	case IORING_OP_ASYNC_CANCEL:
+		ret = io_async_cancel(req, issue_flags);
+		break;
+	case IORING_OP_FALLOCATE:
+		ret = io_fallocate(req, issue_flags);
+		break;
+	case IORING_OP_OPENAT:
+		ret = io_openat(req, issue_flags);
+		break;
+	case IORING_OP_CLOSE:
+		ret = io_close(req, issue_flags);
+		break;
+	case IORING_OP_FILES_UPDATE:
+		ret = io_files_update(req, issue_flags);
+		break;
+	case IORING_OP_STATX:
+		ret = io_statx(req, issue_flags);
+		break;
+	case IORING_OP_FADVISE:
+		ret = io_fadvise(req, issue_flags);
+		break;
+	case IORING_OP_MADVISE:
+		ret = io_madvise(req, issue_flags);
+		break;
+	case IORING_OP_OPENAT2:
+		ret = io_openat2(req, issue_flags);
+		break;
+	case IORING_OP_EPOLL_CTL:
+		ret = io_epoll_ctl(req, issue_flags);
+		break;
+	case IORING_OP_SPLICE:
+		ret = io_splice(req, issue_flags);
+		break;
+	case IORING_OP_PROVIDE_BUFFERS:
+		ret = io_provide_buffers(req, issue_flags);
+		break;
+	case IORING_OP_REMOVE_BUFFERS:
+		ret = io_remove_buffers(req, issue_flags);
+		break;
+	case IORING_OP_TEE:
+		ret = io_tee(req, issue_flags);
+		break;
+	case IORING_OP_SHUTDOWN:
+		ret = io_shutdown(req, issue_flags);
+		break;
+	case IORING_OP_RENAMEAT:
+		ret = io_renameat(req, issue_flags);
+		break;
+	case IORING_OP_UNLINKAT:
+		ret = io_unlinkat(req, issue_flags);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	if (creds)
+		revert_creds(creds);
+	if (ret)
+		return ret;
+	/* If the op doesn't have a file, we're not polling for it */
+	if ((ctx->flags & IORING_SETUP_IOPOLL) && req->file)
+		io_iopoll_req_issued(req);
+
+	return 0;
+}
+
+static struct io_wq_work *io_wq_free_work(struct io_wq_work *work)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+
+	req = io_put_req_find_next(req);
+	return req ? &req->work : NULL;
+}
+
+static void io_wq_submit_work(struct io_wq_work *work)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	struct io_kiocb *timeout;
+	int ret = 0;
+
+	/* one will be dropped by ->io_free_work() after returning to io-wq */
+	if (!(req->flags & REQ_F_REFCOUNT))
+		__io_req_set_refcount(req, 2);
+	else
+		req_ref_get(req);
+
+	timeout = io_prep_linked_timeout(req);
+	if (timeout)
+		io_queue_linked_timeout(timeout);
+
+	/* either cancelled or io-wq is dying, so don't touch tctx->iowq */
+	if (work->flags & IO_WQ_WORK_CANCEL)
+		ret = -ECANCELED;
+
+	if (!ret) {
+		do {
+			ret = io_issue_sqe(req, 0);
+			/*
+			 * We can get EAGAIN for polled IO even though we're
+			 * forcing a sync submission from here, since we can't
+			 * wait for request slots on the block side.
+			 */
+			if (ret != -EAGAIN || !(req->ctx->flags & IORING_SETUP_IOPOLL))
+				break;
+			if (io_wq_worker_stopped())
+				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;
+
+			cond_resched();
+		} while (1);
+	}
+
+	/* avoid locking problems by failing it from a clean context */
+	if (ret)
+		io_req_task_queue_fail(req, ret);
+}
+
+static inline struct io_fixed_file *io_fixed_file_slot(struct io_file_table *table,
+						       unsigned i)
+{
+	return &table->files[i];
+}
+
+static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
+					      int index)
+{
+	struct io_fixed_file *slot = io_fixed_file_slot(&ctx->file_table, index);
+
+	return (struct file *) (slot->file_ptr & FFS_MASK);
+}
+
+static void io_fixed_file_set(struct io_fixed_file *file_slot, struct file *file)
+{
+	unsigned long file_ptr = (unsigned long) file;
+
+	if (__io_file_supports_nowait(file, READ))
+		file_ptr |= FFS_ASYNC_READ;
+	if (__io_file_supports_nowait(file, WRITE))
+		file_ptr |= FFS_ASYNC_WRITE;
+	if (S_ISREG(file_inode(file)->i_mode))
+		file_ptr |= FFS_ISREG;
+	file_slot->file_ptr = file_ptr;
+}
+
+static inline struct file *io_file_get_fixed(struct io_ring_ctx *ctx,
+					     struct io_kiocb *req, int fd,
+					     unsigned int issue_flags)
+{
+	struct file *file = NULL;
+	unsigned long file_ptr;
+
+	io_ring_submit_lock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+
+	if (unlikely((unsigned int)fd >= ctx->nr_user_files))
+		goto out;
+	fd = array_index_nospec(fd, ctx->nr_user_files);
+	file_ptr = io_fixed_file_slot(&ctx->file_table, fd)->file_ptr;
+	file = (struct file *) (file_ptr & FFS_MASK);
+	file_ptr &= ~FFS_MASK;
+	/* mask in overlapping REQ_F and FFS bits */
+	req->flags |= (file_ptr << REQ_F_NOWAIT_READ_BIT);
+	io_req_set_rsrc_node(req);
+out:
+	io_ring_submit_unlock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+	return file;
+}
+
+static struct file *io_file_get_normal(struct io_ring_ctx *ctx,
+				       struct io_kiocb *req, int fd)
+{
+	struct file *file = fget(fd);
+
+	trace_io_uring_file_get(ctx, fd);
+
+	/* we don't allow fixed io_uring files */
+	if (file && unlikely(file->f_op == &io_uring_fops))
+		io_req_track_inflight(req);
+	return file;
+}
+
+static inline struct file *io_file_get(struct io_ring_ctx *ctx,
+				       struct io_kiocb *req, int fd, bool fixed,
+				       unsigned int issue_flags)
+{
+	if (fixed)
+		return io_file_get_fixed(ctx, req, fd, issue_flags);
+	else
+		return io_file_get_normal(ctx, req, fd);
+}
+
+static void io_req_task_link_timeout(struct io_kiocb *req, bool *locked)
+{
+	struct io_kiocb *prev = req->timeout.prev;
+	int ret = -ENOENT;
+
+	if (prev) {
+		if (!(req->task->flags & PF_EXITING))
+			ret = io_try_cancel_userdata(req, prev->user_data);
+		io_req_complete_post(req, ret ?: -ETIME, 0);
+		io_put_req(prev);
+	} else {
+		io_req_complete_post(req, -ETIME, 0);
+	}
+}
+
+static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
+{
+	struct io_timeout_data *data = container_of(timer,
+						struct io_timeout_data, timer);
+	struct io_kiocb *prev, *req = data->req;
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->timeout_lock, flags);
+	prev = req->timeout.head;
+	req->timeout.head = NULL;
+
+	/*
+	 * We don't expect the list to be empty, that will only happen if we
+	 * race with the completion of the linked work.
+	 */
+	if (prev) {
+		io_remove_next_linked(prev);
+		if (!req_ref_inc_not_zero(prev))
+			prev = NULL;
+	}
+	list_del(&req->timeout.list);
+	req->timeout.prev = prev;
+	spin_unlock_irqrestore(&ctx->timeout_lock, flags);
+
+	req->io_task_work.func = io_req_task_link_timeout;
+	io_req_task_work_add(req);
+	return HRTIMER_NORESTART;
+}
+
+static void io_queue_linked_timeout(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	spin_lock_irq(&ctx->timeout_lock);
+	/*
+	 * If the back reference is NULL, then our linked request finished
+	 * before we got a chance to setup the timer
+	 */
+	if (req->timeout.head) {
+		struct io_timeout_data *data = req->async_data;
+
+		data->timer.function = io_link_timeout_fn;
+		hrtimer_start(&data->timer, timespec64_to_ktime(data->ts),
+				data->mode);
+		list_add_tail(&req->timeout.list, &ctx->ltimeout_list);
+	}
+	spin_unlock_irq(&ctx->timeout_lock);
+	/* drop submission reference */
+	io_put_req(req);
+}
+
+static void __io_queue_sqe(struct io_kiocb *req)
+	__must_hold(&req->ctx->uring_lock)
+{
+	struct io_kiocb *linked_timeout;
+	int ret;
+
+issue_sqe:
+	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)) {
+		if (req->flags & REQ_F_COMPLETE_INLINE) {
+			struct io_ring_ctx *ctx = req->ctx;
+			struct io_submit_state *state = &ctx->submit_state;
+
+			state->compl_reqs[state->compl_nr++] = req;
+			if (state->compl_nr == ARRAY_SIZE(state->compl_reqs))
+				io_submit_flush_completions(ctx);
+			return;
+		}
+
+		linked_timeout = io_prep_linked_timeout(req);
+		if (linked_timeout)
+			io_queue_linked_timeout(linked_timeout);
+	} else if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) {
+		linked_timeout = io_prep_linked_timeout(req);
+
+		switch (io_arm_poll_handler(req)) {
+		case IO_APOLL_READY:
+			if (linked_timeout)
+				io_queue_linked_timeout(linked_timeout);
+			goto issue_sqe;
+		case IO_APOLL_ABORTED:
+			/*
+			 * Queued up for async execution, worker will release
+			 * submit reference when the iocb is actually submitted.
+			 */
+			io_queue_async_work(req, NULL);
+			break;
+		}
+
+		if (linked_timeout)
+			io_queue_linked_timeout(linked_timeout);
+	} else {
+		io_req_complete_failed(req, ret);
+	}
+}
+
+static inline void io_queue_sqe(struct io_kiocb *req)
+	__must_hold(&req->ctx->uring_lock)
+{
+	if (unlikely(req->ctx->drain_active) && io_drain_req(req))
+		return;
+
+	if (likely(!(req->flags & (REQ_F_FORCE_ASYNC | REQ_F_FAIL)))) {
+		__io_queue_sqe(req);
+	} else if (req->flags & REQ_F_FAIL) {
+		io_req_complete_fail_submit(req);
+	} else {
+		int ret = io_req_prep_async(req);
+
+		if (unlikely(ret))
+			io_req_complete_failed(req, ret);
+		else
+			io_queue_async_work(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 (likely(!ctx->restricted))
+		return true;
+
+	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 int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
+		       const struct io_uring_sqe *sqe)
+	__must_hold(&ctx->uring_lock)
+{
+	struct io_submit_state *state;
+	unsigned int sqe_flags;
+	int personality, ret = 0;
+
+	/* req is partially pre-initialised, see io_preinit_req() */
+	req->opcode = READ_ONCE(sqe->opcode);
+	/* same numerical values with corresponding REQ_F_*, safe to copy */
+	req->flags = sqe_flags = READ_ONCE(sqe->flags);
+	req->user_data = READ_ONCE(sqe->user_data);
+	req->file = NULL;
+	req->fixed_rsrc_refs = NULL;
+	req->task = current;
+
+	/* enforce forwards compatibility on users */
+	if (unlikely(sqe_flags & ~SQE_VALID_FLAGS))
+		return -EINVAL;
+	if (unlikely(req->opcode >= IORING_OP_LAST))
+		return -EINVAL;
+	if (!io_check_restriction(ctx, req, sqe_flags))
+		return -EACCES;
+
+	if ((sqe_flags & IOSQE_BUFFER_SELECT) &&
+	    !io_op_defs[req->opcode].buffer_select)
+		return -EOPNOTSUPP;
+	if (unlikely(sqe_flags & IOSQE_IO_DRAIN))
+		ctx->drain_active = true;
+
+	personality = READ_ONCE(sqe->personality);
+	if (personality) {
+		req->creds = xa_load(&ctx->personalities, personality);
+		if (!req->creds)
+			return -EINVAL;
+		get_cred(req->creds);
+		req->flags |= REQ_F_CREDS;
+	}
+	state = &ctx->submit_state;
+
+	/*
+	 * Plug now if we have more than 1 IO left after this, and the target
+	 * is potentially a read/write to block based storage.
+	 */
+	if (!state->plug_started && state->ios_left > 1 &&
+	    io_op_defs[req->opcode].plug) {
+		blk_start_plug(&state->plug);
+		state->plug_started = true;
+	}
+
+	if (io_op_defs[req->opcode].needs_file) {
+		req->file = io_file_get(ctx, req, READ_ONCE(sqe->fd),
+					(sqe_flags & IOSQE_FIXED_FILE),
+					IO_URING_F_NONBLOCK);
+		if (unlikely(!req->file))
+			ret = -EBADF;
+	}
+
+	state->ios_left--;
+	return ret;
+}
+
+static 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)) {
+fail_req:
+		/* fail even hard links since we don't submit */
+		if (link->head) {
+			/*
+			 * we can judge a link req is failed or cancelled by if
+			 * REQ_F_FAIL is set, but the head is an exception since
+			 * it may be set REQ_F_FAIL because of other req's failure
+			 * so let's leverage req->result to distinguish if a head
+			 * is set REQ_F_FAIL because of its failure or other req's
+			 * failure so that we can set the correct ret code for it.
+			 * init result here to avoid affecting the normal path.
+			 */
+			if (!(link->head->flags & REQ_F_FAIL))
+				req_fail_link_node(link->head, -ECANCELED);
+		} else if (!(req->flags & (REQ_F_LINK | REQ_F_HARDLINK))) {
+			/*
+			 * the current req is a normal req, we should return
+			 * error and thus break the submittion loop.
+			 */
+			io_req_complete_failed(req, ret);
+			return ret;
+		}
+		req_fail_link_node(req, ret);
+	} else {
+		ret = io_req_prep(req, sqe);
+		if (unlikely(ret))
+			goto fail_req;
+	}
+
+	/* don't need @sqe from now on */
+	trace_io_uring_submit_sqe(ctx, req, req->opcode, req->user_data,
+				  req->flags, true,
+				  ctx->flags & IORING_SETUP_SQPOLL);
+
+	/*
+	 * If we already have a head request, queue this one for async
+	 * submittal once the head completes. If we don't have a head but
+	 * IOSQE_IO_LINK is set in the sqe, start a new head. This one will be
+	 * submitted sync once the chain is complete. If none of those
+	 * conditions are true (normal request), then just queue it.
+	 */
+	if (link->head) {
+		struct io_kiocb *head = link->head;
+
+		if (!(req->flags & REQ_F_FAIL)) {
+			ret = io_req_prep_async(req);
+			if (unlikely(ret)) {
+				req_fail_link_node(req, ret);
+				if (!(head->flags & REQ_F_FAIL))
+					req_fail_link_node(head, -ECANCELED);
+			}
+		}
+		trace_io_uring_link(ctx, req, head);
+		link->last->link = req;
+		link->last = req;
+
+		/* last request of a link, enqueue the link */
+		if (!(req->flags & (REQ_F_LINK | REQ_F_HARDLINK))) {
+			link->head = NULL;
+			io_queue_sqe(head);
+		}
+	} else {
+		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
+			link->head = req;
+			link->last = req;
+		} else {
+			io_queue_sqe(req);
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Batched submission is done, ensure local IO is flushed out.
+ */
+static void io_submit_state_end(struct io_submit_state *state,
+				struct io_ring_ctx *ctx)
+{
+	if (state->link.head)
+		io_queue_sqe(state->link.head);
+	if (state->compl_nr)
+		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->ios_left = 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 const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
+{
+	unsigned head, mask = ctx->sq_entries - 1;
+	unsigned sq_idx = ctx->cached_sq_head++ & mask;
+
+	/*
+	 * The cached sq head (or cq tail) serves two purposes:
+	 *
+	 * 1) allows us to batch the cost of updating the user visible
+	 *    head updates.
+	 * 2) allows the kernel side to track the head on its own, even
+	 *    though the application is the one updating it.
+	 */
+	head = READ_ONCE(ctx->sq_array[sq_idx]);
+	if (likely(head < ctx->sq_entries))
+		return &ctx->sq_sqes[head];
+
+	/* drop invalid entries */
+	ctx->cq_extra--;
+	WRITE_ONCE(ctx->rings->sq_dropped,
+		   READ_ONCE(ctx->rings->sq_dropped) + 1);
+	return NULL;
+}
+
+static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
+	__must_hold(&ctx->uring_lock)
+{
+	int submitted = 0;
+
+	/* make sure SQ entry isn't read before tail */
+	nr = min3(nr, ctx->sq_entries, io_sqring_entries(ctx));
+	if (!percpu_ref_tryget_many(&ctx->refs, nr))
+		return -EAGAIN;
+	io_get_task_refs(nr);
+
+	io_submit_state_start(&ctx->submit_state, nr);
+	while (submitted < nr) {
+		const struct io_uring_sqe *sqe;
+		struct io_kiocb *req;
+
+		req = io_alloc_req(ctx);
+		if (unlikely(!req)) {
+			if (!submitted)
+				submitted = -EAGAIN;
+			break;
+		}
+		sqe = io_get_sqe(ctx);
+		if (unlikely(!sqe)) {
+			list_add(&req->inflight_entry, &ctx->submit_state.free_list);
+			break;
+		}
+		/* will complete beyond this point, count as submitted */
+		submitted++;
+		if (io_submit_sqe(ctx, req, sqe))
+			break;
+	}
+
+	if (unlikely(submitted != nr)) {
+		int ref_used = (submitted == -EAGAIN) ? 0 : submitted;
+		int unused = nr - ref_used;
+
+		current->io_uring->cached_refs += unused;
+		percpu_ref_put_many(&ctx->refs, unused);
+	}
+
+	io_submit_state_end(&ctx->submit_state, ctx);
+	 /* Commit SQ ring head once we've consumed and submitted all SQEs */
+	io_commit_sqring(ctx);
+
+	return submitted;
+}
+
+static inline bool io_sqd_events_pending(struct io_sq_data *sqd)
+{
+	return READ_ONCE(sqd->state);
+}
+
+static inline void io_ring_set_wakeup_flag(struct io_ring_ctx *ctx)
+{
+	/* Tell userspace we may need a wakeup call */
+	spin_lock(&ctx->completion_lock);
+	WRITE_ONCE(ctx->rings->sq_flags,
+		   ctx->rings->sq_flags | IORING_SQ_NEED_WAKEUP);
+	spin_unlock(&ctx->completion_lock);
+}
+
+static inline void io_ring_clear_wakeup_flag(struct io_ring_ctx *ctx)
+{
+	spin_lock(&ctx->completion_lock);
+	WRITE_ONCE(ctx->rings->sq_flags,
+		   ctx->rings->sq_flags & ~IORING_SQ_NEED_WAKEUP);
+	spin_unlock(&ctx->completion_lock);
+}
+
+static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
+{
+	unsigned int to_submit;
+	int ret = 0;
+
+	to_submit = io_sqring_entries(ctx);
+	/* if we're handling multiple rings, cap submit size for fairness */
+	if (cap_entries && to_submit > IORING_SQPOLL_CAP_ENTRIES_VALUE)
+		to_submit = IORING_SQPOLL_CAP_ENTRIES_VALUE;
+
+	if (!list_empty(&ctx->iopoll_list) || to_submit) {
+		unsigned nr_events = 0;
+		const struct cred *creds = NULL;
+
+		if (ctx->sq_creds != current_cred())
+			creds = override_creds(ctx->sq_creds);
+
+		mutex_lock(&ctx->uring_lock);
+		if (!list_empty(&ctx->iopoll_list))
+			io_do_iopoll(ctx, &nr_events, 0);
+
+		/*
+		 * Don't submit if refs are dying, good for io_uring_register(),
+		 * but also it is relied upon by io_ring_exit_work()
+		 */
+		if (to_submit && likely(!percpu_ref_is_dying(&ctx->refs)) &&
+		    !(ctx->flags & IORING_SETUP_R_DISABLED))
+			ret = io_submit_sqes(ctx, to_submit);
+		mutex_unlock(&ctx->uring_lock);
+
+		if (to_submit && wq_has_sleeper(&ctx->sqo_sq_wait))
+			wake_up(&ctx->sqo_sq_wait);
+		if (creds)
+			revert_creds(creds);
+	}
+
+	return ret;
+}
+
+static void io_sqd_update_thread_idle(struct io_sq_data *sqd)
+{
+	struct io_ring_ctx *ctx;
+	unsigned sq_thread_idle = 0;
+
+	list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+		sq_thread_idle = max(sq_thread_idle, ctx->sq_thread_idle);
+	sqd->sq_thread_idle = sq_thread_idle;
+}
+
+static bool io_sqd_handle_event(struct io_sq_data *sqd)
+{
+	bool did_sig = false;
+	struct ksignal ksig;
+
+	if (test_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state) ||
+	    signal_pending(current)) {
+		mutex_unlock(&sqd->lock);
+		if (signal_pending(current))
+			did_sig = get_signal(&ksig);
+		cond_resched();
+		mutex_lock(&sqd->lock);
+	}
+	return did_sig || test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
+}
+
+static int io_sq_thread(void *data)
+{
+	struct io_sq_data *sqd = data;
+	struct io_ring_ctx *ctx;
+	unsigned long timeout = 0;
+	char buf[TASK_COMM_LEN];
+	DEFINE_WAIT(wait);
+
+	snprintf(buf, sizeof(buf), "iou-sqp-%d", sqd->task_pid);
+	set_task_comm(current, buf);
+
+	if (sqd->sq_cpu != -1)
+		set_cpus_allowed_ptr(current, cpumask_of(sqd->sq_cpu));
+	else
+		set_cpus_allowed_ptr(current, cpu_online_mask);
+	current->flags |= PF_NO_SETAFFINITY;
+
+	mutex_lock(&sqd->lock);
+	while (1) {
+		bool cap_entries, sqt_spin = false;
+
+		if (io_sqd_events_pending(sqd) || signal_pending(current)) {
+			if (io_sqd_handle_event(sqd))
+				break;
+			timeout = jiffies + sqd->sq_thread_idle;
+		}
+
+		cap_entries = !list_is_singular(&sqd->ctx_list);
+		list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
+			int ret = __io_sq_thread(ctx, cap_entries);
+
+			if (!sqt_spin && (ret > 0 || !list_empty(&ctx->iopoll_list)))
+				sqt_spin = true;
+		}
+		if (io_run_task_work())
+			sqt_spin = true;
+
+		if (sqt_spin || !time_after(jiffies, timeout)) {
+			cond_resched();
+			if (sqt_spin)
+				timeout = jiffies + sqd->sq_thread_idle;
+			continue;
+		}
+
+		prepare_to_wait(&sqd->wait, &wait, TASK_INTERRUPTIBLE);
+		if (!io_sqd_events_pending(sqd) && !current->task_works) {
+			bool needs_sched = true;
+
+			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list) {
+				io_ring_set_wakeup_flag(ctx);
+
+				if ((ctx->flags & IORING_SETUP_IOPOLL) &&
+				    !list_empty_careful(&ctx->iopoll_list)) {
+					needs_sched = false;
+					break;
+				}
+				if (io_sqring_entries(ctx)) {
+					needs_sched = false;
+					break;
+				}
+			}
+
+			if (needs_sched) {
+				mutex_unlock(&sqd->lock);
+				schedule();
+				mutex_lock(&sqd->lock);
+			}
+			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+				io_ring_clear_wakeup_flag(ctx);
+		}
+
+		finish_wait(&sqd->wait, &wait);
+		timeout = jiffies + sqd->sq_thread_idle;
+	}
+
+	io_uring_cancel_generic(true, sqd);
+	sqd->thread = NULL;
+	list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+		io_ring_set_wakeup_flag(ctx);
+	io_run_task_work();
+	mutex_unlock(&sqd->lock);
+
+	complete(&sqd->exited);
+	do_exit(0);
+}
+
+struct io_wait_queue {
+	struct wait_queue_entry wq;
+	struct io_ring_ctx *ctx;
+	unsigned cq_tail;
+	unsigned nr_timeouts;
+};
+
+static inline bool io_should_wake(struct io_wait_queue *iowq)
+{
+	struct io_ring_ctx *ctx = iowq->ctx;
+	int dist = ctx->cached_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) || test_bit(0, &iowq->ctx->check_cq_overflow))
+		return autoremove_wake_function(curr, mode, wake_flags, key);
+	return -1;
+}
+
+static int io_run_task_work_sig(void)
+{
+	if (io_run_task_work())
+		return 1;
+	if (!signal_pending(current))
+		return 0;
+	if (test_thread_flag(TIF_NOTIFY_SIGNAL))
+		return -ERESTARTSYS;
+	return -EINTR;
+}
+
+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,
+					  ktime_t *timeout)
+{
+	int io_wait, ret;
+
+	/* make sure we run task_work before checking for signals */
+	ret = io_run_task_work_sig();
+	if (ret || io_should_wake(iowq))
+		return ret;
+	/* let the caller flush overflows, retry */
+	if (test_bit(0, &ctx->check_cq_overflow))
+		return 1;
+
+	/*
+	 * 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 = 1;
+	if (!schedule_hrtimeout(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;
+	ktime_t timeout = KTIME_MAX;
+	int ret;
+
+	do {
+		io_cqring_overflow_flush(ctx);
+		if (io_cqring_events(ctx) >= min_events)
+			return 0;
+		if (!io_run_task_work())
+			break;
+	} while (1);
+
+	if (uts) {
+		struct timespec64 ts;
+
+		if (get_timespec64(&ts, uts))
+			return -EFAULT;
+		timeout = ktime_add_ns(timespec64_to_ktime(ts), ktime_get_ns());
+	}
+
+	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;
+
+	trace_io_uring_cqring_wait(ctx, min_events);
+	do {
+		/* if we can't even flush overflow, don't wait for more */
+		if (!io_cqring_overflow_flush(ctx)) {
+			ret = -EBUSY;
+			break;
+		}
+		prepare_to_wait_exclusive(&ctx->cq_wait, &iowq.wq,
+						TASK_INTERRUPTIBLE);
+		ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);
+		finish_wait(&ctx->cq_wait, &iowq.wq);
+		cond_resched();
+	} while (ret > 0);
+
+	restore_saved_sigmask_unless(ret == -EINTR);
+
+	return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
+}
+
+static void io_free_page_table(void **table, size_t size)
+{
+	unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
+
+	for (i = 0; i < nr_tables; i++)
+		kfree(table[i]);
+	kfree(table);
+}
+
+static void **io_alloc_page_table(size_t size)
+{
+	unsigned i, nr_tables = DIV_ROUND_UP(size, PAGE_SIZE);
+	size_t init_size = size;
+	void **table;
+
+	table = kcalloc(nr_tables, sizeof(*table), GFP_KERNEL_ACCOUNT);
+	if (!table)
+		return NULL;
+
+	for (i = 0; i < nr_tables; i++) {
+		unsigned int this_size = min_t(size_t, size, PAGE_SIZE);
+
+		table[i] = kzalloc(this_size, GFP_KERNEL_ACCOUNT);
+		if (!table[i]) {
+			io_free_page_table(table, init_size);
+			return NULL;
+		}
+		size -= this_size;
+	}
+	return table;
+}
+
+static void io_rsrc_node_destroy(struct io_rsrc_node *ref_node)
+{
+	percpu_ref_exit(&ref_node->refs);
+	kfree(ref_node);
+}
+
+static void io_rsrc_node_ref_zero(struct percpu_ref *ref)
+{
+	struct io_rsrc_node *node = container_of(ref, struct io_rsrc_node, refs);
+	struct io_ring_ctx *ctx = node->rsrc_data->ctx;
+	unsigned long flags;
+	bool first_add = false;
+	unsigned long delay = HZ;
+
+	spin_lock_irqsave(&ctx->rsrc_ref_lock, flags);
+	node->done = true;
+
+	/* if we are mid-quiesce then do not delay */
+	if (node->rsrc_data->quiesce)
+		delay = 0;
+
+	while (!list_empty(&ctx->rsrc_ref_list)) {
+		node = list_first_entry(&ctx->rsrc_ref_list,
+					    struct io_rsrc_node, node);
+		/* recycle ref nodes in order */
+		if (!node->done)
+			break;
+		list_del(&node->node);
+		first_add |= llist_add(&node->llist, &ctx->rsrc_put_llist);
+	}
+	spin_unlock_irqrestore(&ctx->rsrc_ref_lock, flags);
+
+	if (first_add)
+		mod_delayed_work(system_wq, &ctx->rsrc_put_work, delay);
+}
+
+static struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx)
+{
+	struct io_rsrc_node *ref_node;
+
+	ref_node = kzalloc(sizeof(*ref_node), GFP_KERNEL);
+	if (!ref_node)
+		return NULL;
+
+	if (percpu_ref_init(&ref_node->refs, io_rsrc_node_ref_zero,
+			    0, GFP_KERNEL)) {
+		kfree(ref_node);
+		return NULL;
+	}
+	INIT_LIST_HEAD(&ref_node->node);
+	INIT_LIST_HEAD(&ref_node->rsrc_list);
+	ref_node->done = false;
+	return ref_node;
+}
+
+static void io_rsrc_node_switch(struct io_ring_ctx *ctx,
+				struct io_rsrc_data *data_to_kill)
+{
+	WARN_ON_ONCE(!ctx->rsrc_backup_node);
+	WARN_ON_ONCE(data_to_kill && !ctx->rsrc_node);
+
+	if (data_to_kill) {
+		struct io_rsrc_node *rsrc_node = ctx->rsrc_node;
+
+		rsrc_node->rsrc_data = data_to_kill;
+		spin_lock_irq(&ctx->rsrc_ref_lock);
+		list_add_tail(&rsrc_node->node, &ctx->rsrc_ref_list);
+		spin_unlock_irq(&ctx->rsrc_ref_lock);
+
+		atomic_inc(&data_to_kill->refs);
+		percpu_ref_kill(&rsrc_node->refs);
+		ctx->rsrc_node = NULL;
+	}
+
+	if (!ctx->rsrc_node) {
+		ctx->rsrc_node = ctx->rsrc_backup_node;
+		ctx->rsrc_backup_node = NULL;
+	}
+}
+
+static int io_rsrc_node_switch_start(struct io_ring_ctx *ctx)
+{
+	if (ctx->rsrc_backup_node)
+		return 0;
+	ctx->rsrc_backup_node = io_rsrc_node_alloc(ctx);
+	return ctx->rsrc_backup_node ? 0 : -ENOMEM;
+}
+
+static int io_rsrc_ref_quiesce(struct io_rsrc_data *data, struct io_ring_ctx *ctx)
+{
+	int ret;
+
+	/* As we may drop ->uring_lock, other task may have started quiesce */
+	if (data->quiesce)
+		return -ENXIO;
+
+	data->quiesce = true;
+	do {
+		ret = io_rsrc_node_switch_start(ctx);
+		if (ret)
+			break;
+		io_rsrc_node_switch(ctx, data);
+
+		/* kill initial ref, already quiesced if zero */
+		if (atomic_dec_and_test(&data->refs))
+			break;
+		mutex_unlock(&ctx->uring_lock);
+		flush_delayed_work(&ctx->rsrc_put_work);
+		ret = wait_for_completion_interruptible(&data->done);
+		if (!ret) {
+			mutex_lock(&ctx->uring_lock);
+			if (atomic_read(&data->refs) > 0) {
+				/*
+				 * it has been revived by another thread while
+				 * we were unlocked
+				 */
+				mutex_unlock(&ctx->uring_lock);
+			} else {
+				break;
+			}
+		}
+
+		atomic_inc(&data->refs);
+		/* wait for all works potentially completing data->done */
+		flush_delayed_work(&ctx->rsrc_put_work);
+		reinit_completion(&data->done);
+
+		ret = io_run_task_work_sig();
+		mutex_lock(&ctx->uring_lock);
+	} while (ret >= 0);
+	data->quiesce = false;
+
+	return ret;
+}
+
+static u64 *io_get_tag_slot(struct io_rsrc_data *data, unsigned int idx)
+{
+	unsigned int off = idx & IO_RSRC_TAG_TABLE_MASK;
+	unsigned int table_idx = idx >> IO_RSRC_TAG_TABLE_SHIFT;
+
+	return &data->tags[table_idx][off];
+}
+
+static void io_rsrc_data_free(struct io_rsrc_data *data)
+{
+	size_t size = data->nr * sizeof(data->tags[0][0]);
+
+	if (data->tags)
+		io_free_page_table((void **)data->tags, size);
+	kfree(data);
+}
+
+static int io_rsrc_data_alloc(struct io_ring_ctx *ctx, rsrc_put_fn *do_put,
+			      u64 __user *utags, unsigned nr,
+			      struct io_rsrc_data **pdata)
+{
+	struct io_rsrc_data *data;
+	int ret = -ENOMEM;
+	unsigned i;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+	data->tags = (u64 **)io_alloc_page_table(nr * sizeof(data->tags[0][0]));
+	if (!data->tags) {
+		kfree(data);
+		return -ENOMEM;
+	}
+
+	data->nr = nr;
+	data->ctx = ctx;
+	data->do_put = do_put;
+	if (utags) {
+		ret = -EFAULT;
+		for (i = 0; i < nr; i++) {
+			u64 *tag_slot = io_get_tag_slot(data, i);
+
+			if (copy_from_user(tag_slot, &utags[i],
+					   sizeof(*tag_slot)))
+				goto fail;
+		}
+	}
+
+	atomic_set(&data->refs, 1);
+	init_completion(&data->done);
+	*pdata = data;
+	return 0;
+fail:
+	io_rsrc_data_free(data);
+	return ret;
+}
+
+static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
+{
+	table->files = kvcalloc(nr_files, sizeof(table->files[0]),
+				GFP_KERNEL_ACCOUNT);
+	return !!table->files;
+}
+
+static void io_free_file_tables(struct io_file_table *table)
+{
+	kvfree(table->files);
+	table->files = NULL;
+}
+
+static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
+{
+#if defined(CONFIG_UNIX)
+	if (ctx->ring_sock) {
+		struct sock *sock = ctx->ring_sock->sk;
+		struct sk_buff *skb;
+
+		while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
+			kfree_skb(skb);
+	}
+#else
+	int i;
+
+	for (i = 0; i < ctx->nr_user_files; i++) {
+		struct file *file;
+
+		file = io_file_from_index(ctx, i);
+		if (file)
+			fput(file);
+	}
+#endif
+	io_free_file_tables(&ctx->file_table);
+	io_rsrc_data_free(ctx->file_data);
+	ctx->file_data = NULL;
+	ctx->nr_user_files = 0;
+}
+
+static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
+{
+	unsigned nr = ctx->nr_user_files;
+	int ret;
+
+	if (!ctx->file_data)
+		return -ENXIO;
+
+	/*
+	 * Quiesce may unlock ->uring_lock, and while it's not held
+	 * prevent new requests using the table.
+	 */
+	ctx->nr_user_files = 0;
+	ret = io_rsrc_ref_quiesce(ctx->file_data, ctx);
+	ctx->nr_user_files = nr;
+	if (!ret)
+		__io_sqe_files_unregister(ctx);
+	return ret;
+}
+
+static void io_sq_thread_unpark(struct io_sq_data *sqd)
+	__releases(&sqd->lock)
+{
+	WARN_ON_ONCE(sqd->thread == current);
+
+	/*
+	 * Do the dance but not conditional clear_bit() because it'd race with
+	 * other threads incrementing park_pending and setting the bit.
+	 */
+	clear_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
+	if (atomic_dec_return(&sqd->park_pending))
+		set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
+	mutex_unlock(&sqd->lock);
+}
+
+static void io_sq_thread_park(struct io_sq_data *sqd)
+	__acquires(&sqd->lock)
+{
+	WARN_ON_ONCE(sqd->thread == current);
+
+	atomic_inc(&sqd->park_pending);
+	set_bit(IO_SQ_THREAD_SHOULD_PARK, &sqd->state);
+	mutex_lock(&sqd->lock);
+	if (sqd->thread)
+		wake_up_process(sqd->thread);
+}
+
+static void io_sq_thread_stop(struct io_sq_data *sqd)
+{
+	WARN_ON_ONCE(sqd->thread == current);
+	WARN_ON_ONCE(test_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state));
+
+	set_bit(IO_SQ_THREAD_SHOULD_STOP, &sqd->state);
+	mutex_lock(&sqd->lock);
+	if (sqd->thread)
+		wake_up_process(sqd->thread);
+	mutex_unlock(&sqd->lock);
+	wait_for_completion(&sqd->exited);
+}
+
+static void io_put_sq_data(struct io_sq_data *sqd)
+{
+	if (refcount_dec_and_test(&sqd->refs)) {
+		WARN_ON_ONCE(atomic_read(&sqd->park_pending));
+
+		io_sq_thread_stop(sqd);
+		kfree(sqd);
+	}
+}
+
+static void io_sq_thread_finish(struct io_ring_ctx *ctx)
+{
+	struct io_sq_data *sqd = ctx->sq_data;
+
+	if (sqd) {
+		io_sq_thread_park(sqd);
+		list_del_init(&ctx->sqd_list);
+		io_sqd_update_thread_idle(sqd);
+		io_sq_thread_unpark(sqd);
+
+		io_put_sq_data(sqd);
+		ctx->sq_data = NULL;
+	}
+}
+
+static struct io_sq_data *io_attach_sq_data(struct io_uring_params *p)
+{
+	struct io_ring_ctx *ctx_attach;
+	struct io_sq_data *sqd;
+	struct fd f;
+
+	f = fdget(p->wq_fd);
+	if (!f.file)
+		return ERR_PTR(-ENXIO);
+	if (f.file->f_op != &io_uring_fops) {
+		fdput(f);
+		return ERR_PTR(-EINVAL);
+	}
+
+	ctx_attach = f.file->private_data;
+	sqd = ctx_attach->sq_data;
+	if (!sqd) {
+		fdput(f);
+		return ERR_PTR(-EINVAL);
+	}
+	if (sqd->task_tgid != current->tgid) {
+		fdput(f);
+		return ERR_PTR(-EPERM);
+	}
+
+	refcount_inc(&sqd->refs);
+	fdput(f);
+	return sqd;
+}
+
+static struct io_sq_data *io_get_sq_data(struct io_uring_params *p,
+					 bool *attached)
+{
+	struct io_sq_data *sqd;
+
+	*attached = false;
+	if (p->flags & IORING_SETUP_ATTACH_WQ) {
+		sqd = io_attach_sq_data(p);
+		if (!IS_ERR(sqd)) {
+			*attached = true;
+			return sqd;
+		}
+		/* fall through for EPERM case, setup new sqd/task */
+		if (PTR_ERR(sqd) != -EPERM)
+			return sqd;
+	}
+
+	sqd = kzalloc(sizeof(*sqd), GFP_KERNEL);
+	if (!sqd)
+		return ERR_PTR(-ENOMEM);
+
+	atomic_set(&sqd->park_pending, 0);
+	refcount_set(&sqd->refs, 1);
+	INIT_LIST_HEAD(&sqd->ctx_list);
+	mutex_init(&sqd->lock);
+	init_waitqueue_head(&sqd->wait);
+	init_completion(&sqd->exited);
+	return sqd;
+}
+
+#if defined(CONFIG_UNIX)
+/*
+ * Ensure the UNIX gc is aware of our file set, so we are certain that
+ * the io_uring can be safely unregistered on process exit, even if we have
+ * loops in the file referencing.
+ */
+static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
+{
+	struct sock *sk = ctx->ring_sock->sk;
+	struct scm_fp_list *fpl;
+	struct sk_buff *skb;
+	int i, nr_files;
+
+	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
+	if (!fpl)
+		return -ENOMEM;
+
+	skb = alloc_skb(0, GFP_KERNEL);
+	if (!skb) {
+		kfree(fpl);
+		return -ENOMEM;
+	}
+
+	skb->sk = sk;
+	skb->scm_io_uring = 1;
+
+	nr_files = 0;
+	fpl->user = get_uid(current_user());
+	for (i = 0; i < nr; i++) {
+		struct file *file = io_file_from_index(ctx, i + offset);
+
+		if (!file)
+			continue;
+		fpl->fp[nr_files] = get_file(file);
+		unix_inflight(fpl->user, fpl->fp[nr_files]);
+		nr_files++;
+	}
+
+	if (nr_files) {
+		fpl->max = SCM_MAX_FD;
+		fpl->count = nr_files;
+		UNIXCB(skb).fp = fpl;
+		skb->destructor = unix_destruct_scm;
+		refcount_add(skb->truesize, &sk->sk_wmem_alloc);
+		skb_queue_head(&sk->sk_receive_queue, skb);
+
+		for (i = 0; i < nr; i++) {
+			struct file *file = io_file_from_index(ctx, i + offset);
+
+			if (file)
+				fput(file);
+		}
+	} else {
+		kfree_skb(skb);
+		free_uid(fpl->user);
+		kfree(fpl);
+	}
+
+	return 0;
+}
+
+/*
+ * If UNIX sockets are enabled, fd passing can cause a reference cycle which
+ * causes regular reference counting to break down. We rely on the UNIX
+ * garbage collection to take care of this problem for us.
+ */
+static int io_sqe_files_scm(struct io_ring_ctx *ctx)
+{
+	unsigned left, total;
+	int ret = 0;
+
+	total = 0;
+	left = ctx->nr_user_files;
+	while (left) {
+		unsigned this_files = min_t(unsigned, left, SCM_MAX_FD);
+
+		ret = __io_sqe_files_scm(ctx, this_files, total);
+		if (ret)
+			break;
+		left -= this_files;
+		total += this_files;
+	}
+
+	if (!ret)
+		return 0;
+
+	while (total < ctx->nr_user_files) {
+		struct file *file = io_file_from_index(ctx, total);
+
+		if (file)
+			fput(file);
+		total++;
+	}
+
+	return ret;
+}
+#else
+static int io_sqe_files_scm(struct io_ring_ctx *ctx)
+{
+	return 0;
+}
+#endif
+
+static void io_rsrc_file_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
+{
+	struct file *file = prsrc->file;
+#if defined(CONFIG_UNIX)
+	struct sock *sock = ctx->ring_sock->sk;
+	struct sk_buff_head list, *head = &sock->sk_receive_queue;
+	struct sk_buff *skb;
+	int i;
+
+	__skb_queue_head_init(&list);
+
+	/*
+	 * Find the skb that holds this file in its SCM_RIGHTS. When found,
+	 * remove this entry and rearrange the file array.
+	 */
+	skb = skb_dequeue(head);
+	while (skb) {
+		struct scm_fp_list *fp;
+
+		fp = UNIXCB(skb).fp;
+		for (i = 0; i < fp->count; i++) {
+			int left;
+
+			if (fp->fp[i] != file)
+				continue;
+
+			unix_notinflight(fp->user, fp->fp[i]);
+			left = fp->count - 1 - i;
+			if (left) {
+				memmove(&fp->fp[i], &fp->fp[i + 1],
+						left * sizeof(struct file *));
+			}
+			fp->count--;
+			if (!fp->count) {
+				kfree_skb(skb);
+				skb = NULL;
+			} else {
+				__skb_queue_tail(&list, skb);
+			}
+			fput(file);
+			file = NULL;
+			break;
+		}
+
+		if (!file)
+			break;
+
+		__skb_queue_tail(&list, skb);
+
+		skb = skb_dequeue(head);
+	}
+
+	if (skb_peek(&list)) {
+		spin_lock_irq(&head->lock);
+		while ((skb = __skb_dequeue(&list)) != NULL)
+			__skb_queue_tail(head, skb);
+		spin_unlock_irq(&head->lock);
+	}
+#else
+	fput(file);
+#endif
+}
+
+static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
+{
+	struct io_rsrc_data *rsrc_data = ref_node->rsrc_data;
+	struct io_ring_ctx *ctx = rsrc_data->ctx;
+	struct io_rsrc_put *prsrc, *tmp;
+
+	list_for_each_entry_safe(prsrc, tmp, &ref_node->rsrc_list, list) {
+		list_del(&prsrc->list);
+
+		if (prsrc->tag) {
+			bool lock_ring = ctx->flags & IORING_SETUP_IOPOLL;
+
+			io_ring_submit_lock(ctx, lock_ring);
+			spin_lock(&ctx->completion_lock);
+			io_fill_cqe_aux(ctx, prsrc->tag, 0, 0);
+			io_commit_cqring(ctx);
+			spin_unlock(&ctx->completion_lock);
+			io_cqring_ev_posted(ctx);
+			io_ring_submit_unlock(ctx, lock_ring);
+		}
+
+		rsrc_data->do_put(ctx, prsrc);
+		kfree(prsrc);
+	}
+
+	io_rsrc_node_destroy(ref_node);
+	if (atomic_dec_and_test(&rsrc_data->refs))
+		complete(&rsrc_data->done);
+}
+
+static void io_rsrc_put_work(struct work_struct *work)
+{
+	struct io_ring_ctx *ctx;
+	struct llist_node *node;
+
+	ctx = container_of(work, struct io_ring_ctx, rsrc_put_work.work);
+	node = llist_del_all(&ctx->rsrc_put_llist);
+
+	while (node) {
+		struct io_rsrc_node *ref_node;
+		struct llist_node *next = node->next;
+
+		ref_node = llist_entry(node, struct io_rsrc_node, llist);
+		__io_rsrc_put_work(ref_node);
+		node = next;
+	}
+}
+
+static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
+				 unsigned nr_args, u64 __user *tags)
+{
+	__s32 __user *fds = (__s32 __user *) arg;
+	struct file *file;
+	int fd, ret;
+	unsigned i;
+
+	if (ctx->file_data)
+		return -EBUSY;
+	if (!nr_args)
+		return -EINVAL;
+	if (nr_args > IORING_MAX_FIXED_FILES)
+		return -EMFILE;
+	if (nr_args > rlimit(RLIMIT_NOFILE))
+		return -EMFILE;
+	ret = io_rsrc_node_switch_start(ctx);
+	if (ret)
+		return ret;
+	ret = io_rsrc_data_alloc(ctx, io_rsrc_file_put, tags, nr_args,
+				 &ctx->file_data);
+	if (ret)
+		return ret;
+
+	ret = -ENOMEM;
+	if (!io_alloc_file_tables(&ctx->file_table, nr_args))
+		goto out_free;
+
+	for (i = 0; i < nr_args; i++, ctx->nr_user_files++) {
+		if (copy_from_user(&fd, &fds[i], sizeof(fd))) {
+			ret = -EFAULT;
+			goto out_fput;
+		}
+		/* allow sparse sets */
+		if (fd == -1) {
+			ret = -EINVAL;
+			if (unlikely(*io_get_tag_slot(ctx->file_data, i)))
+				goto out_fput;
+			continue;
+		}
+
+		file = fget(fd);
+		ret = -EBADF;
+		if (unlikely(!file))
+			goto out_fput;
+
+		/*
+		 * Don't allow io_uring instances to be registered. If UNIX
+		 * isn't enabled, then this causes a reference cycle and this
+		 * instance can never get freed. If UNIX is enabled we'll
+		 * handle it just fine, but there's still no point in allowing
+		 * a ring fd as it doesn't support regular read/write anyway.
+		 */
+		if (file->f_op == &io_uring_fops) {
+			fput(file);
+			goto out_fput;
+		}
+		io_fixed_file_set(io_fixed_file_slot(&ctx->file_table, i), file);
+	}
+
+	ret = io_sqe_files_scm(ctx);
+	if (ret) {
+		__io_sqe_files_unregister(ctx);
+		return ret;
+	}
+
+	io_rsrc_node_switch(ctx, NULL);
+	return ret;
+out_fput:
+	for (i = 0; i < ctx->nr_user_files; i++) {
+		file = io_file_from_index(ctx, i);
+		if (file)
+			fput(file);
+	}
+	io_free_file_tables(&ctx->file_table);
+	ctx->nr_user_files = 0;
+out_free:
+	io_rsrc_data_free(ctx->file_data);
+	ctx->file_data = NULL;
+	return ret;
+}
+
+static int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
+				 struct io_rsrc_node *node, void *rsrc)
+{
+	u64 *tag_slot = io_get_tag_slot(data, idx);
+	struct io_rsrc_put *prsrc;
+
+	prsrc = kzalloc(sizeof(*prsrc), GFP_KERNEL);
+	if (!prsrc)
+		return -ENOMEM;
+
+	prsrc->tag = *tag_slot;
+	*tag_slot = 0;
+	prsrc->rsrc = rsrc;
+	list_add(&prsrc->list, &node->rsrc_list);
+	return 0;
+}
+
+static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
+				 unsigned int issue_flags, u32 slot_index)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK;
+	bool needs_switch = false;
+	struct io_fixed_file *file_slot;
+	int ret = -EBADF;
+
+	io_ring_submit_lock(ctx, !force_nonblock);
+	if (file->f_op == &io_uring_fops)
+		goto err;
+	ret = -ENXIO;
+	if (!ctx->file_data)
+		goto err;
+	ret = -EINVAL;
+	if (slot_index >= ctx->nr_user_files)
+		goto err;
+
+	slot_index = array_index_nospec(slot_index, ctx->nr_user_files);
+	file_slot = io_fixed_file_slot(&ctx->file_table, slot_index);
+
+	if (file_slot->file_ptr) {
+		struct file *old_file;
+
+		ret = io_rsrc_node_switch_start(ctx);
+		if (ret)
+			goto err;
+
+		old_file = (struct file *)(file_slot->file_ptr & FFS_MASK);
+		ret = io_queue_rsrc_removal(ctx->file_data, slot_index,
+					    ctx->rsrc_node, old_file);
+		if (ret)
+			goto err;
+		file_slot->file_ptr = 0;
+		needs_switch = true;
+	}
+
+	*io_get_tag_slot(ctx->file_data, slot_index) = 0;
+	io_fixed_file_set(file_slot, file);
+	ret = 0;
+err:
+	if (needs_switch)
+		io_rsrc_node_switch(ctx, ctx->file_data);
+	io_ring_submit_unlock(ctx, !force_nonblock);
+	if (ret)
+		fput(file);
+	return ret;
+}
+
+static int io_close_fixed(struct io_kiocb *req, unsigned int issue_flags)
+{
+	unsigned int offset = req->close.file_slot - 1;
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_fixed_file *file_slot;
+	struct file *file;
+	int ret;
+
+	io_ring_submit_lock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+	ret = -ENXIO;
+	if (unlikely(!ctx->file_data))
+		goto out;
+	ret = -EINVAL;
+	if (offset >= ctx->nr_user_files)
+		goto out;
+	ret = io_rsrc_node_switch_start(ctx);
+	if (ret)
+		goto out;
+
+	offset = array_index_nospec(offset, ctx->nr_user_files);
+	file_slot = io_fixed_file_slot(&ctx->file_table, offset);
+	ret = -EBADF;
+	if (!file_slot->file_ptr)
+		goto out;
+
+	file = (struct file *)(file_slot->file_ptr & FFS_MASK);
+	ret = io_queue_rsrc_removal(ctx->file_data, offset, ctx->rsrc_node, file);
+	if (ret)
+		goto out;
+
+	file_slot->file_ptr = 0;
+	io_rsrc_node_switch(ctx, ctx->file_data);
+	ret = 0;
+out:
+	io_ring_submit_unlock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
+	return ret;
+}
+
+static int __io_sqe_files_update(struct io_ring_ctx *ctx,
+				 struct io_uring_rsrc_update2 *up,
+				 unsigned nr_args)
+{
+	u64 __user *tags = u64_to_user_ptr(up->tags);
+	__s32 __user *fds = u64_to_user_ptr(up->data);
+	struct io_rsrc_data *data = ctx->file_data;
+	struct io_fixed_file *file_slot;
+	struct file *file;
+	int fd, i, err = 0;
+	unsigned int done;
+	bool needs_switch = false;
+
+	if (!ctx->file_data)
+		return -ENXIO;
+	if (up->offset + nr_args > ctx->nr_user_files)
+		return -EINVAL;
+
+	for (done = 0; done < nr_args; done++) {
+		u64 tag = 0;
+
+		if ((tags && copy_from_user(&tag, &tags[done], sizeof(tag))) ||
+		    copy_from_user(&fd, &fds[done], sizeof(fd))) {
+			err = -EFAULT;
+			break;
+		}
+		if ((fd == IORING_REGISTER_FILES_SKIP || fd == -1) && tag) {
+			err = -EINVAL;
+			break;
+		}
+		if (fd == IORING_REGISTER_FILES_SKIP)
+			continue;
+
+		i = array_index_nospec(up->offset + done, ctx->nr_user_files);
+		file_slot = io_fixed_file_slot(&ctx->file_table, i);
+
+		if (file_slot->file_ptr) {
+			file = (struct file *)(file_slot->file_ptr & FFS_MASK);
+			err = io_queue_rsrc_removal(data, i, ctx->rsrc_node, file);
+			if (err)
+				break;
+			file_slot->file_ptr = 0;
+			needs_switch = true;
+		}
+		if (fd != -1) {
+			file = fget(fd);
+			if (!file) {
+				err = -EBADF;
+				break;
+			}
+			/*
+			 * Don't allow io_uring instances to be registered. If
+			 * UNIX isn't enabled, then this causes a reference
+			 * cycle and this instance can never get freed. If UNIX
+			 * is enabled we'll handle it just fine, but there's
+			 * still no point in allowing a ring fd as it doesn't
+			 * support regular read/write anyway.
+			 */
+			if (file->f_op == &io_uring_fops) {
+				fput(file);
+				err = -EBADF;
+				break;
+			}
+			*io_get_tag_slot(data, i) = tag;
+			io_fixed_file_set(file_slot, file);
+		}
+	}
+
+	if (needs_switch)
+		io_rsrc_node_switch(ctx, data);
+	return done ? done : err;
+}
+
+static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
+					struct task_struct *task)
+{
+	struct io_wq_hash *hash;
+	struct io_wq_data data;
+	unsigned int concurrency;
+
+	mutex_lock(&ctx->uring_lock);
+	hash = ctx->hash_map;
+	if (!hash) {
+		hash = kzalloc(sizeof(*hash), GFP_KERNEL);
+		if (!hash) {
+			mutex_unlock(&ctx->uring_lock);
+			return ERR_PTR(-ENOMEM);
+		}
+		refcount_set(&hash->refs, 1);
+		init_waitqueue_head(&hash->wait);
+		ctx->hash_map = hash;
+	}
+	mutex_unlock(&ctx->uring_lock);
+
+	data.hash = hash;
+	data.task = task;
+	data.free_work = io_wq_free_work;
+	data.do_work = io_wq_submit_work;
+
+	/* Do QD, or 4 * CPUS, whatever is smallest */
+	concurrency = min(ctx->sq_entries, 4 * num_online_cpus());
+
+	return io_wq_create(concurrency, &data);
+}
+
+static int io_uring_alloc_task_context(struct task_struct *task,
+				       struct io_ring_ctx *ctx)
+{
+	struct io_uring_task *tctx;
+	int ret;
+
+	tctx = kzalloc(sizeof(*tctx), GFP_KERNEL);
+	if (unlikely(!tctx))
+		return -ENOMEM;
+
+	ret = percpu_counter_init(&tctx->inflight, 0, GFP_KERNEL);
+	if (unlikely(ret)) {
+		kfree(tctx);
+		return ret;
+	}
+
+	tctx->io_wq = io_init_wq_offload(ctx, task);
+	if (IS_ERR(tctx->io_wq)) {
+		ret = PTR_ERR(tctx->io_wq);
+		percpu_counter_destroy(&tctx->inflight);
+		kfree(tctx);
+		return ret;
+	}
+
+	xa_init(&tctx->xa);
+	init_waitqueue_head(&tctx->wait);
+	atomic_set(&tctx->in_idle, 0);
+	atomic_set(&tctx->inflight_tracked, 0);
+	task->io_uring = tctx;
+	spin_lock_init(&tctx->task_lock);
+	INIT_WQ_LIST(&tctx->task_list);
+	init_task_work(&tctx->task_work, tctx_task_work);
+	return 0;
+}
+
+void __io_uring_free(struct task_struct *tsk)
+{
+	struct io_uring_task *tctx = tsk->io_uring;
+
+	WARN_ON_ONCE(!xa_empty(&tctx->xa));
+	WARN_ON_ONCE(tctx->io_wq);
+	WARN_ON_ONCE(tctx->cached_refs);
+
+	percpu_counter_destroy(&tctx->inflight);
+	kfree(tctx);
+	tsk->io_uring = NULL;
+}
+
+static int io_sq_offload_create(struct io_ring_ctx *ctx,
+				struct io_uring_params *p)
+{
+	int ret;
+
+	/* Retain compatibility with failing for an invalid attach attempt */
+	if ((ctx->flags & (IORING_SETUP_ATTACH_WQ | IORING_SETUP_SQPOLL)) ==
+				IORING_SETUP_ATTACH_WQ) {
+		struct fd f;
+
+		f = fdget(p->wq_fd);
+		if (!f.file)
+			return -ENXIO;
+		if (f.file->f_op != &io_uring_fops) {
+			fdput(f);
+			return -EINVAL;
+		}
+		fdput(f);
+	}
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		struct task_struct *tsk;
+		struct io_sq_data *sqd;
+		bool attached;
+
+		sqd = io_get_sq_data(p, &attached);
+		if (IS_ERR(sqd)) {
+			ret = PTR_ERR(sqd);
+			goto err;
+		}
+
+		ctx->sq_creds = get_current_cred();
+		ctx->sq_data = sqd;
+		ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
+		if (!ctx->sq_thread_idle)
+			ctx->sq_thread_idle = HZ;
+
+		io_sq_thread_park(sqd);
+		list_add(&ctx->sqd_list, &sqd->ctx_list);
+		io_sqd_update_thread_idle(sqd);
+		/* don't attach to a dying SQPOLL thread, would be racy */
+		ret = (attached && !sqd->thread) ? -ENXIO : 0;
+		io_sq_thread_unpark(sqd);
+
+		if (ret < 0)
+			goto err;
+		if (attached)
+			return 0;
+
+		if (p->flags & IORING_SETUP_SQ_AFF) {
+			int cpu = p->sq_thread_cpu;
+
+			ret = -EINVAL;
+			if (cpu >= nr_cpu_ids || !cpu_online(cpu))
+				goto err_sqpoll;
+			sqd->sq_cpu = cpu;
+		} else {
+			sqd->sq_cpu = -1;
+		}
+
+		sqd->task_pid = current->pid;
+		sqd->task_tgid = current->tgid;
+		tsk = create_io_thread(io_sq_thread, sqd, NUMA_NO_NODE);
+		if (IS_ERR(tsk)) {
+			ret = PTR_ERR(tsk);
+			goto err_sqpoll;
+		}
+
+		sqd->thread = tsk;
+		ret = io_uring_alloc_task_context(tsk, ctx);
+		wake_up_new_task(tsk);
+		if (ret)
+			goto err;
+	} else if (p->flags & IORING_SETUP_SQ_AFF) {
+		/* Can't have SQ_AFF without SQPOLL */
+		ret = -EINVAL;
+		goto err;
+	}
+
+	return 0;
+err_sqpoll:
+	complete(&ctx->sq_data->exited);
+err:
+	io_sq_thread_finish(ctx);
+	return ret;
+}
+
+static inline void __io_unaccount_mem(struct user_struct *user,
+				      unsigned long nr_pages)
+{
+	atomic_long_sub(nr_pages, &user->locked_vm);
+}
+
+static inline int __io_account_mem(struct user_struct *user,
+				   unsigned long nr_pages)
+{
+	unsigned long page_limit, cur_pages, new_pages;
+
+	/* Don't allow more pages than we can safely lock */
+	page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+
+	do {
+		cur_pages = atomic_long_read(&user->locked_vm);
+		new_pages = cur_pages + nr_pages;
+		if (new_pages > page_limit)
+			return -ENOMEM;
+	} while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
+					new_pages) != cur_pages);
+
+	return 0;
+}
+
+static void io_unaccount_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
+{
+	if (ctx->user)
+		__io_unaccount_mem(ctx->user, nr_pages);
+
+	if (ctx->mm_account)
+		atomic64_sub(nr_pages, &ctx->mm_account->pinned_vm);
+}
+
+static int io_account_mem(struct io_ring_ctx *ctx, unsigned long nr_pages)
+{
+	int ret;
+
+	if (ctx->user) {
+		ret = __io_account_mem(ctx->user, nr_pages);
+		if (ret)
+			return ret;
+	}
+
+	if (ctx->mm_account)
+		atomic64_add(nr_pages, &ctx->mm_account->pinned_vm);
+
+	return 0;
+}
+
+static void io_mem_free(void *ptr)
+{
+	struct page *page;
+
+	if (!ptr)
+		return;
+
+	page = virt_to_head_page(ptr);
+	if (put_page_testzero(page))
+		free_compound_page(page);
+}
+
+static void *io_mem_alloc(size_t size)
+{
+	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
+
+	return (void *) __get_free_pages(gfp, get_order(size));
+}
+
+static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
+				size_t *sq_offset)
+{
+	struct io_rings *rings;
+	size_t off, sq_array_size;
+
+	off = struct_size(rings, cqes, cq_entries);
+	if (off == SIZE_MAX)
+		return SIZE_MAX;
+
+#ifdef CONFIG_SMP
+	off = ALIGN(off, SMP_CACHE_BYTES);
+	if (off == 0)
+		return SIZE_MAX;
+#endif
+
+	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 void io_buffer_unmap(struct io_ring_ctx *ctx, struct io_mapped_ubuf **slot)
+{
+	struct io_mapped_ubuf *imu = *slot;
+	unsigned int i;
+
+	if (imu != ctx->dummy_ubuf) {
+		for (i = 0; i < imu->nr_bvecs; i++)
+			unpin_user_page(imu->bvec[i].bv_page);
+		if (imu->acct_pages)
+			io_unaccount_mem(ctx, imu->acct_pages);
+		kvfree(imu);
+	}
+	*slot = NULL;
+}
+
+static void io_rsrc_buf_put(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc)
+{
+	io_buffer_unmap(ctx, &prsrc->buf);
+	prsrc->buf = NULL;
+}
+
+static void __io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
+{
+	unsigned int i;
+
+	for (i = 0; i < ctx->nr_user_bufs; i++)
+		io_buffer_unmap(ctx, &ctx->user_bufs[i]);
+	kfree(ctx->user_bufs);
+	io_rsrc_data_free(ctx->buf_data);
+	ctx->user_bufs = NULL;
+	ctx->buf_data = NULL;
+	ctx->nr_user_bufs = 0;
+}
+
+static int io_sqe_buffers_unregister(struct io_ring_ctx *ctx)
+{
+	unsigned nr = ctx->nr_user_bufs;
+	int ret;
+
+	if (!ctx->buf_data)
+		return -ENXIO;
+
+	/*
+	 * Quiesce may unlock ->uring_lock, and while it's not held
+	 * prevent new requests using the table.
+	 */
+	ctx->nr_user_bufs = 0;
+	ret = io_rsrc_ref_quiesce(ctx->buf_data, ctx);
+	ctx->nr_user_bufs = nr;
+	if (!ret)
+		__io_sqe_buffers_unregister(ctx);
+	return ret;
+}
+
+static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
+		       void __user *arg, unsigned index)
+{
+	struct iovec __user *src;
+
+#ifdef CONFIG_COMPAT
+	if (ctx->compat) {
+		struct compat_iovec __user *ciovs;
+		struct compat_iovec ciov;
+
+		ciovs = (struct compat_iovec __user *) arg;
+		if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
+			return -EFAULT;
+
+		dst->iov_base = u64_to_user_ptr((u64)ciov.iov_base);
+		dst->iov_len = ciov.iov_len;
+		return 0;
+	}
+#endif
+	src = (struct iovec __user *) arg;
+	if (copy_from_user(dst, &src[index], sizeof(*dst)))
+		return -EFAULT;
+	return 0;
+}
+
+/*
+ * Not super efficient, but this is just a registration time. And we do cache
+ * the last compound head, so generally we'll only do a full search if we don't
+ * match that one.
+ *
+ * We check if the given compound head page has already been accounted, to
+ * avoid double accounting it. This allows us to account the full size of the
+ * page, not just the constituent pages of a huge page.
+ */
+static bool headpage_already_acct(struct io_ring_ctx *ctx, struct page **pages,
+				  int nr_pages, struct page *hpage)
+{
+	int i, j;
+
+	/* check current page array */
+	for (i = 0; i < nr_pages; i++) {
+		if (!PageCompound(pages[i]))
+			continue;
+		if (compound_head(pages[i]) == hpage)
+			return true;
+	}
+
+	/* check previously registered pages */
+	for (i = 0; i < ctx->nr_user_bufs; i++) {
+		struct io_mapped_ubuf *imu = ctx->user_bufs[i];
+
+		for (j = 0; j < imu->nr_bvecs; j++) {
+			if (!PageCompound(imu->bvec[j].bv_page))
+				continue;
+			if (compound_head(imu->bvec[j].bv_page) == hpage)
+				return true;
+		}
+	}
+
+	return false;
+}
+
+static int io_buffer_account_pin(struct io_ring_ctx *ctx, struct page **pages,
+				 int nr_pages, struct io_mapped_ubuf *imu,
+				 struct page **last_hpage)
+{
+	int i, ret;
+
+	imu->acct_pages = 0;
+	for (i = 0; i < nr_pages; i++) {
+		if (!PageCompound(pages[i])) {
+			imu->acct_pages++;
+		} else {
+			struct page *hpage;
+
+			hpage = compound_head(pages[i]);
+			if (hpage == *last_hpage)
+				continue;
+			*last_hpage = hpage;
+			if (headpage_already_acct(ctx, pages, i, hpage))
+				continue;
+			imu->acct_pages += page_size(hpage) >> PAGE_SHIFT;
+		}
+	}
+
+	if (!imu->acct_pages)
+		return 0;
+
+	ret = io_account_mem(ctx, imu->acct_pages);
+	if (ret)
+		imu->acct_pages = 0;
+	return ret;
+}
+
+static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
+				  struct io_mapped_ubuf **pimu,
+				  struct page **last_hpage)
+{
+	struct io_mapped_ubuf *imu = NULL;
+	struct vm_area_struct **vmas = NULL;
+	struct page **pages = NULL;
+	unsigned long off, start, end, ubuf;
+	size_t size;
+	int ret, pret, nr_pages, i;
+
+	if (!iov->iov_base) {
+		*pimu = ctx->dummy_ubuf;
+		return 0;
+	}
+
+	ubuf = (unsigned long) iov->iov_base;
+	end = (ubuf + iov->iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+	start = ubuf >> PAGE_SHIFT;
+	nr_pages = end - start;
+
+	*pimu = NULL;
+	ret = -ENOMEM;
+
+	pages = kvmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL);
+	if (!pages)
+		goto done;
+
+	vmas = kvmalloc_array(nr_pages, sizeof(struct vm_area_struct *),
+			      GFP_KERNEL);
+	if (!vmas)
+		goto done;
+
+	imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL);
+	if (!imu)
+		goto done;
+
+	ret = 0;
+	mmap_read_lock(current->mm);
+	pret = pin_user_pages(ubuf, nr_pages, FOLL_WRITE | FOLL_LONGTERM,
+			      pages, vmas);
+	if (pret == nr_pages) {
+		struct file *file = vmas[0]->vm_file;
+
+		/* don't support file backed memory */
+		for (i = 0; i < nr_pages; i++) {
+			if (vmas[i]->vm_file != file) {
+				ret = -EINVAL;
+				break;
+			}
+			if (!file)
+				continue;
+			if (!vma_is_shmem(vmas[i]) && !is_file_hugepages(file)) {
+				ret = -EOPNOTSUPP;
+				break;
+			}
+		}
+	} else {
+		ret = pret < 0 ? pret : -EFAULT;
+	}
+	mmap_read_unlock(current->mm);
+	if (ret) {
+		/*
+		 * if we did partial map, or found file backed vmas,
+		 * release any pages we did get
+		 */
+		if (pret > 0)
+			unpin_user_pages(pages, pret);
+		goto done;
+	}
+
+	ret = io_buffer_account_pin(ctx, pages, pret, imu, last_hpage);
+	if (ret) {
+		unpin_user_pages(pages, pret);
+		goto done;
+	}
+
+	off = ubuf & ~PAGE_MASK;
+	size = iov->iov_len;
+	for (i = 0; i < nr_pages; i++) {
+		size_t vec_len;
+
+		vec_len = min_t(size_t, size, PAGE_SIZE - off);
+		imu->bvec[i].bv_page = pages[i];
+		imu->bvec[i].bv_len = vec_len;
+		imu->bvec[i].bv_offset = off;
+		off = 0;
+		size -= vec_len;
+	}
+	/* store original address for later verification */
+	imu->ubuf = ubuf;
+	imu->ubuf_end = ubuf + iov->iov_len;
+	imu->nr_bvecs = nr_pages;
+	*pimu = imu;
+	ret = 0;
+done:
+	if (ret)
+		kvfree(imu);
+	kvfree(pages);
+	kvfree(vmas);
+	return ret;
+}
+
+static int io_buffers_map_alloc(struct io_ring_ctx *ctx, unsigned int nr_args)
+{
+	ctx->user_bufs = kcalloc(nr_args, sizeof(*ctx->user_bufs), GFP_KERNEL);
+	return ctx->user_bufs ? 0 : -ENOMEM;
+}
+
+static int io_buffer_validate(struct iovec *iov)
+{
+	unsigned long tmp, acct_len = iov->iov_len + (PAGE_SIZE - 1);
+
+	/*
+	 * Don't impose further limits on the size and buffer
+	 * constraints here, we'll -EINVAL later when IO is
+	 * submitted if they are wrong.
+	 */
+	if (!iov->iov_base)
+		return iov->iov_len ? -EFAULT : 0;
+	if (!iov->iov_len)
+		return -EFAULT;
+
+	/* arbitrary limit, but we need something */
+	if (iov->iov_len > SZ_1G)
+		return -EFAULT;
+
+	if (check_add_overflow((unsigned long)iov->iov_base, acct_len, &tmp))
+		return -EOVERFLOW;
+
+	return 0;
+}
+
+static int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
+				   unsigned int nr_args, u64 __user *tags)
+{
+	struct page *last_hpage = NULL;
+	struct io_rsrc_data *data;
+	int i, ret;
+	struct iovec iov;
+
+	if (ctx->user_bufs)
+		return -EBUSY;
+	if (!nr_args || nr_args > IORING_MAX_REG_BUFFERS)
+		return -EINVAL;
+	ret = io_rsrc_node_switch_start(ctx);
+	if (ret)
+		return ret;
+	ret = io_rsrc_data_alloc(ctx, io_rsrc_buf_put, tags, nr_args, &data);
+	if (ret)
+		return ret;
+	ret = io_buffers_map_alloc(ctx, nr_args);
+	if (ret) {
+		io_rsrc_data_free(data);
+		return ret;
+	}
+
+	for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
+		ret = io_copy_iov(ctx, &iov, arg, i);
+		if (ret)
+			break;
+		ret = io_buffer_validate(&iov);
+		if (ret)
+			break;
+		if (!iov.iov_base && *io_get_tag_slot(data, i)) {
+			ret = -EINVAL;
+			break;
+		}
+
+		ret = io_sqe_buffer_register(ctx, &iov, &ctx->user_bufs[i],
+					     &last_hpage);
+		if (ret)
+			break;
+	}
+
+	WARN_ON_ONCE(ctx->buf_data);
+
+	ctx->buf_data = data;
+	if (ret)
+		__io_sqe_buffers_unregister(ctx);
+	else
+		io_rsrc_node_switch(ctx, NULL);
+	return ret;
+}
+
+static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
+				   struct io_uring_rsrc_update2 *up,
+				   unsigned int nr_args)
+{
+	u64 __user *tags = u64_to_user_ptr(up->tags);
+	struct iovec iov, __user *iovs = u64_to_user_ptr(up->data);
+	struct page *last_hpage = NULL;
+	bool needs_switch = false;
+	__u32 done;
+	int i, err;
+
+	if (!ctx->buf_data)
+		return -ENXIO;
+	if (up->offset + nr_args > ctx->nr_user_bufs)
+		return -EINVAL;
+
+	for (done = 0; done < nr_args; done++) {
+		struct io_mapped_ubuf *imu;
+		int offset = up->offset + done;
+		u64 tag = 0;
+
+		err = io_copy_iov(ctx, &iov, iovs, done);
+		if (err)
+			break;
+		if (tags && copy_from_user(&tag, &tags[done], sizeof(tag))) {
+			err = -EFAULT;
+			break;
+		}
+		err = io_buffer_validate(&iov);
+		if (err)
+			break;
+		if (!iov.iov_base && tag) {
+			err = -EINVAL;
+			break;
+		}
+		err = io_sqe_buffer_register(ctx, &iov, &imu, &last_hpage);
+		if (err)
+			break;
+
+		i = array_index_nospec(offset, ctx->nr_user_bufs);
+		if (ctx->user_bufs[i] != ctx->dummy_ubuf) {
+			err = io_queue_rsrc_removal(ctx->buf_data, i,
+						    ctx->rsrc_node, ctx->user_bufs[i]);
+			if (unlikely(err)) {
+				io_buffer_unmap(ctx, &imu);
+				break;
+			}
+			ctx->user_bufs[i] = NULL;
+			needs_switch = true;
+		}
+
+		ctx->user_bufs[i] = imu;
+		*io_get_tag_slot(ctx->buf_data, offset) = tag;
+	}
+
+	if (needs_switch)
+		io_rsrc_node_switch(ctx, ctx->buf_data);
+	return done ? done : err;
+}
+
+static int io_eventfd_register(struct io_ring_ctx *ctx, void __user *arg)
+{
+	__s32 __user *fds = arg;
+	int fd;
+
+	if (ctx->cq_ev_fd)
+		return -EBUSY;
+
+	if (copy_from_user(&fd, fds, sizeof(*fds)))
+		return -EFAULT;
+
+	ctx->cq_ev_fd = eventfd_ctx_fdget(fd);
+	if (IS_ERR(ctx->cq_ev_fd)) {
+		int ret = PTR_ERR(ctx->cq_ev_fd);
+
+		ctx->cq_ev_fd = NULL;
+		return ret;
+	}
+
+	return 0;
+}
+
+static int io_eventfd_unregister(struct io_ring_ctx *ctx)
+{
+	if (ctx->cq_ev_fd) {
+		eventfd_ctx_put(ctx->cq_ev_fd);
+		ctx->cq_ev_fd = NULL;
+		return 0;
+	}
+
+	return -ENXIO;
+}
+
+static void io_destroy_buffers(struct io_ring_ctx *ctx)
+{
+	struct io_buffer *buf;
+	unsigned long index;
+
+	xa_for_each(&ctx->io_buffers, index, buf)
+		__io_remove_buffers(ctx, buf, index, -1U);
+}
+
+static void io_req_cache_free(struct list_head *list)
+{
+	struct io_kiocb *req, *nxt;
+
+	list_for_each_entry_safe(req, nxt, list, inflight_entry) {
+		list_del(&req->inflight_entry);
+		kmem_cache_free(req_cachep, req);
+	}
+}
+
+static void io_req_caches_free(struct io_ring_ctx *ctx)
+{
+	struct io_submit_state *state = &ctx->submit_state;
+
+	mutex_lock(&ctx->uring_lock);
+
+	if (state->free_reqs) {
+		kmem_cache_free_bulk(req_cachep, state->free_reqs, state->reqs);
+		state->free_reqs = 0;
+	}
+
+	io_flush_cached_locked_reqs(ctx, state);
+	io_req_cache_free(&state->free_list);
+	mutex_unlock(&ctx->uring_lock);
+}
+
+static void io_wait_rsrc_data(struct io_rsrc_data *data)
+{
+	if (data && !atomic_dec_and_test(&data->refs))
+		wait_for_completion(&data->done);
+}
+
+static 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 */
+	io_wait_rsrc_data(ctx->buf_data);
+	io_wait_rsrc_data(ctx->file_data);
+
+	mutex_lock(&ctx->uring_lock);
+	if (ctx->buf_data)
+		__io_sqe_buffers_unregister(ctx);
+	if (ctx->file_data)
+		__io_sqe_files_unregister(ctx);
+	if (ctx->rings)
+		__io_cqring_overflow_flush(ctx, true);
+	mutex_unlock(&ctx->uring_lock);
+	io_eventfd_unregister(ctx);
+	io_destroy_buffers(ctx);
+	if (ctx->sq_creds)
+		put_cred(ctx->sq_creds);
+
+	/* there are no registered resources left, nobody uses it */
+	if (ctx->rsrc_node)
+		io_rsrc_node_destroy(ctx->rsrc_node);
+	if (ctx->rsrc_backup_node)
+		io_rsrc_node_destroy(ctx->rsrc_backup_node);
+	flush_delayed_work(&ctx->rsrc_put_work);
+
+	WARN_ON_ONCE(!list_empty(&ctx->rsrc_ref_list));
+	WARN_ON_ONCE(!llist_empty(&ctx->rsrc_put_llist));
+
+#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));
+
+	if (ctx->mm_account) {
+		mmdrop(ctx->mm_account);
+		ctx->mm_account = NULL;
+	}
+
+	io_mem_free(ctx->rings);
+	io_mem_free(ctx->sq_sqes);
+
+	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_hash);
+	kfree(ctx->dummy_ubuf);
+	kfree(ctx);
+}
+
+static __poll_t io_uring_poll(struct file *file, poll_table *wait)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(file, &ctx->poll_wait, 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
+	 * pushs them to do the flush.
+	 */
+	if (io_cqring_events(ctx) || test_bit(0, &ctx->check_cq_overflow))
+		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 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_idle, 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_idle))
+		io_uring_del_tctx_node((unsigned long)work->ctx);
+	complete(&work->completion);
+}
+
+static 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 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 {
+		io_uring_try_cancel_requests(ctx, NULL, true);
+		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);
+		}
+
+		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;
+	/*
+	 * Some may use context even when all refs and requests have been put,
+	 * and they are free to do so while still holding uring_lock or
+	 * completion_lock, see io_req_task_submit(). Apart from other work,
+	 * this lock/unlock section also waits them to finish.
+	 */
+	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;
+		wake_up_process(node->task);
+
+		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);
+
+	io_ring_ctx_free(ctx);
+}
+
+/* Returns true if we found and killed one or more timeouts */
+static bool io_kill_timeouts(struct io_ring_ctx *ctx, struct task_struct *tsk,
+			     bool cancel_all)
+{
+	struct io_kiocb *req, *tmp;
+	int canceled = 0;
+
+	spin_lock(&ctx->completion_lock);
+	spin_lock_irq(&ctx->timeout_lock);
+	list_for_each_entry_safe(req, tmp, &ctx->timeout_list, timeout.list) {
+		if (io_match_task(req, tsk, cancel_all)) {
+			io_kill_timeout(req, -ECANCELED);
+			canceled++;
+		}
+	}
+	spin_unlock_irq(&ctx->timeout_lock);
+	if (canceled != 0)
+		io_commit_cqring(ctx);
+	spin_unlock(&ctx->completion_lock);
+	if (canceled != 0)
+		io_cqring_ev_posted(ctx);
+	return canceled != 0;
+}
+
+static 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);
+	if (ctx->rings)
+		__io_cqring_overflow_flush(ctx, true);
+	xa_for_each(&ctx->personalities, index, creds)
+		io_unregister_personality(ctx, index);
+	mutex_unlock(&ctx->uring_lock);
+
+	io_kill_timeouts(ctx, NULL, true);
+	io_poll_remove_all(ctx, NULL, true);
+
+	/* if we failed setting up the ctx, we might not have any rings */
+	io_iopoll_try_reap_events(ctx);
+
+	/* drop cached put refs after potentially doing completions */
+	if (current->io_uring)
+		io_uring_drop_tctx_refs(current);
+
+	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 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_complete_failed(de->req, -ECANCELED);
+		kfree(de);
+	}
+	return true;
+}
+
+static 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 void 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;
+
+	while (1) {
+		enum io_wq_cancel cret;
+		bool ret = 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 (!list_empty_careful(&ctx->iopoll_list)) {
+				io_iopoll_try_reap_events(ctx);
+				ret = true;
+				cond_resched();
+			}
+		}
+
+		ret |= io_cancel_defer_files(ctx, task, cancel_all);
+		ret |= io_poll_remove_all(ctx, task, cancel_all);
+		ret |= io_kill_timeouts(ctx, task, cancel_all);
+		if (task)
+			ret |= io_run_task_work();
+		if (!ret)
+			break;
+		cond_resched();
+	}
+}
+
+static int __io_uring_add_tctx_node(struct io_ring_ctx *ctx)
+{
+	struct io_uring_task *tctx = current->io_uring;
+	struct io_tctx_node *node;
+	int ret;
+
+	if (unlikely(!tctx)) {
+		ret = io_uring_alloc_task_context(current, ctx);
+		if (unlikely(ret))
+			return ret;
+
+		tctx = current->io_uring;
+		if (ctx->iowq_limits_set) {
+			unsigned int limits[2] = { ctx->iowq_limits[0],
+						   ctx->iowq_limits[1], };
+
+			ret = io_wq_max_workers(tctx->io_wq, limits);
+			if (ret)
+				return ret;
+		}
+	}
+	if (!xa_load(&tctx->xa, (unsigned long)ctx)) {
+		node = kmalloc(sizeof(*node), GFP_KERNEL);
+		if (!node)
+			return -ENOMEM;
+		node->ctx = ctx;
+		node->task = current;
+
+		ret = xa_err(xa_store(&tctx->xa, (unsigned long)ctx,
+					node, GFP_KERNEL));
+		if (ret) {
+			kfree(node);
+			return ret;
+		}
+
+		mutex_lock(&ctx->uring_lock);
+		list_add(&node->ctx_node, &ctx->tctx_list);
+		mutex_unlock(&ctx->uring_lock);
+	}
+	tctx->last = ctx;
+	return 0;
+}
+
+/*
+ * Note that this task has used io_uring. We use it for cancelation purposes.
+ */
+static inline int io_uring_add_tctx_node(struct io_ring_ctx *ctx)
+{
+	struct io_uring_task *tctx = current->io_uring;
+
+	if (likely(tctx && tctx->last == ctx))
+		return 0;
+	return __io_uring_add_tctx_node(ctx);
+}
+
+/*
+ * Remove this io_uring_file -> task mapping.
+ */
+static void io_uring_del_tctx_node(unsigned long index)
+{
+	struct io_uring_task *tctx = current->io_uring;
+	struct io_tctx_node *node;
+
+	if (!tctx)
+		return;
+	node = xa_erase(&tctx->xa, index);
+	if (!node)
+		return;
+
+	WARN_ON_ONCE(current != node->task);
+	WARN_ON_ONCE(list_empty(&node->ctx_node));
+
+	mutex_lock(&node->ctx->uring_lock);
+	list_del(&node->ctx_node);
+	mutex_unlock(&node->ctx->uring_lock);
+
+	if (tctx->last == node->ctx)
+		tctx->last = NULL;
+	kfree(node);
+}
+
+static void io_uring_clean_tctx(struct io_uring_task *tctx)
+{
+	struct io_wq *wq = tctx->io_wq;
+	struct io_tctx_node *node;
+	unsigned long index;
+
+	xa_for_each(&tctx->xa, index, node) {
+		io_uring_del_tctx_node(index);
+		cond_resched();
+	}
+	if (wq) {
+		/*
+		 * Must be after io_uring_del_task_file() (removes nodes under
+		 * uring_lock) to avoid race with io_uring_try_cancel_iowq().
+		 */
+		io_wq_put_and_exit(wq);
+		tctx->io_wq = NULL;
+	}
+}
+
+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.
+ */
+static 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;
+	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_idle);
+	do {
+		io_uring_drop_tctx_refs(current);
+		/* read completions before cancelations */
+		inflight = tctx_inflight(tctx, !cancel_all);
+		if (!inflight)
+			break;
+
+		if (!sqd) {
+			struct io_tctx_node *node;
+			unsigned long index;
+
+			xa_for_each(&tctx->xa, index, node) {
+				/* sqpoll task will cancel all its requests */
+				if (node->ctx->sq_data)
+					continue;
+				io_uring_try_cancel_requests(node->ctx, current,
+							     cancel_all);
+			}
+		} else {
+			list_for_each_entry(ctx, &sqd->ctx_list, sqd_list)
+				io_uring_try_cancel_requests(ctx, current,
+							     cancel_all);
+		}
+
+		prepare_to_wait(&tctx->wait, &wait, TASK_INTERRUPTIBLE);
+		io_run_task_work();
+		io_uring_drop_tctx_refs(current);
+
+		/*
+		 * 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();
+		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_idle set for normal exit.
+		 */
+		atomic_dec(&tctx->in_idle);
+		/* 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) {
+	case IORING_OFF_SQ_RING:
+	case IORING_OFF_CQ_RING:
+		ptr = ctx->rings;
+		break;
+	case IORING_OFF_SQES:
+		ptr = ctx->sq_sqes;
+		break;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+
+	page = virt_to_head_page(ptr);
+	if (sz > page_size(page))
+		return ERR_PTR(-EINVAL);
+
+	return ptr;
+}
+
+#ifdef CONFIG_MMU
+
+static 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);
+}
+
+#else /* !CONFIG_MMU */
+
+static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	return vma->vm_flags & (VM_SHARED | VM_MAYSHARE) ? 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_sqpoll_wait_sq(struct io_ring_ctx *ctx)
+{
+	DEFINE_WAIT(wait);
+
+	do {
+		if (!io_sqring_full(ctx))
+			break;
+		prepare_to_wait(&ctx->sqo_sq_wait, &wait, TASK_INTERRUPTIBLE);
+
+		if (!io_sqring_full(ctx))
+			break;
+		schedule();
+	} while (!signal_pending(current));
+
+	finish_wait(&ctx->sqo_sq_wait, &wait);
+	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;
+	int submitted = 0;
+	struct fd f;
+	long ret;
+
+	io_run_task_work();
+
+	if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP |
+			       IORING_ENTER_SQ_WAIT | IORING_ENTER_EXT_ARG)))
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (unlikely(!f.file))
+		return -EBADF;
+
+	ret = -EOPNOTSUPP;
+	if (unlikely(f.file->f_op != &io_uring_fops))
+		goto out_fput;
+
+	ret = -ENXIO;
+	ctx = f.file->private_data;
+	if (unlikely(!percpu_ref_tryget(&ctx->refs)))
+		goto out_fput;
+
+	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) {
+			ret = io_sqpoll_wait_sq(ctx);
+			if (ret)
+				goto out;
+		}
+		submitted = to_submit;
+	} else if (to_submit) {
+		ret = io_uring_add_tctx_node(ctx);
+		if (unlikely(ret))
+			goto out;
+		mutex_lock(&ctx->uring_lock);
+		submitted = io_submit_sqes(ctx, to_submit);
+		mutex_unlock(&ctx->uring_lock);
+
+		if (submitted != to_submit)
+			goto out;
+	}
+	if (flags & IORING_ENTER_GETEVENTS) {
+		const sigset_t __user *sig;
+		struct __kernel_timespec __user *ts;
+
+		ret = io_get_ext_arg(flags, argp, &argsz, &ts, &sig);
+		if (unlikely(ret))
+			goto out;
+
+		min_complete = min(min_complete, ctx->cq_entries);
+
+		/*
+		 * 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)) {
+			ret = io_iopoll_check(ctx, min_complete);
+		} else {
+			ret = io_cqring_wait(ctx, min_complete, sig, argsz, ts);
+		}
+	}
+
+out:
+	percpu_ref_put(&ctx->refs);
+out_fput:
+	fdput(f);
+	return submitted ? submitted : ret;
+}
+
+#ifdef CONFIG_PROC_FS
+static int io_uring_show_cred(struct seq_file *m, unsigned int id,
+		const struct cred *cred)
+{
+	struct user_namespace *uns = seq_user_ns(m);
+	struct group_info *gi;
+	kernel_cap_t cap;
+	unsigned __capi;
+	int g;
+
+	seq_printf(m, "%5d\n", id);
+	seq_put_decimal_ull(m, "\tUid:\t", from_kuid_munged(uns, cred->uid));
+	seq_put_decimal_ull(m, "\t\t", from_kuid_munged(uns, cred->euid));
+	seq_put_decimal_ull(m, "\t\t", from_kuid_munged(uns, cred->suid));
+	seq_put_decimal_ull(m, "\t\t", from_kuid_munged(uns, cred->fsuid));
+	seq_put_decimal_ull(m, "\n\tGid:\t", from_kgid_munged(uns, cred->gid));
+	seq_put_decimal_ull(m, "\t\t", from_kgid_munged(uns, cred->egid));
+	seq_put_decimal_ull(m, "\t\t", from_kgid_munged(uns, cred->sgid));
+	seq_put_decimal_ull(m, "\t\t", from_kgid_munged(uns, cred->fsgid));
+	seq_puts(m, "\n\tGroups:\t");
+	gi = cred->group_info;
+	for (g = 0; g < gi->ngroups; g++) {
+		seq_put_decimal_ull(m, g ? " " : "",
+					from_kgid_munged(uns, gi->gid[g]));
+	}
+	seq_puts(m, "\n\tCapEff:\t");
+	cap = cred->cap_effective;
+	CAP_FOR_EACH_U32(__capi)
+		seq_put_hex_ll(m, NULL, cap.cap[CAP_LAST_U32 - __capi], 8);
+	seq_putc(m, '\n');
+	return 0;
+}
+
+static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
+{
+	int sq_pid = -1, sq_cpu = -1;
+	bool has_lock;
+	int i;
+
+	/*
+	 * Avoid ABBA deadlock between the seq lock and the io_uring mutex,
+	 * since fdinfo case grabs it in the opposite direction of normal use
+	 * cases. If we fail to get the lock, we just don't iterate any
+	 * structures that could be going away outside the io_uring mutex.
+	 */
+	has_lock = mutex_trylock(&ctx->uring_lock);
+
+	if (has_lock && (ctx->flags & IORING_SETUP_SQPOLL)) {
+		struct io_sq_data *sq = ctx->sq_data;
+
+		if (mutex_trylock(&sq->lock)) {
+			if (sq->thread) {
+				sq_pid = task_pid_nr(sq->thread);
+				sq_cpu = task_cpu(sq->thread);
+			}
+			mutex_unlock(&sq->lock);
+		}
+	}
+
+	seq_printf(m, "SqThread:\t%d\n", sq_pid);
+	seq_printf(m, "SqThreadCpu:\t%d\n", sq_cpu);
+	seq_printf(m, "UserFiles:\t%u\n", ctx->nr_user_files);
+	for (i = 0; has_lock && i < ctx->nr_user_files; i++) {
+		struct file *f = io_file_from_index(ctx, i);
+
+		if (f)
+			seq_printf(m, "%5u: %s\n", i, file_dentry(f)->d_iname);
+		else
+			seq_printf(m, "%5u: <none>\n", i);
+	}
+	seq_printf(m, "UserBufs:\t%u\n", ctx->nr_user_bufs);
+	for (i = 0; has_lock && i < ctx->nr_user_bufs; i++) {
+		struct io_mapped_ubuf *buf = ctx->user_bufs[i];
+		unsigned int len = buf->ubuf_end - buf->ubuf;
+
+		seq_printf(m, "%5u: 0x%llx/%u\n", i, buf->ubuf, len);
+	}
+	if (has_lock && !xa_empty(&ctx->personalities)) {
+		unsigned long index;
+		const struct cred *cred;
+
+		seq_printf(m, "Personalities:\n");
+		xa_for_each(&ctx->personalities, index, cred)
+			io_uring_show_cred(m, index, cred);
+	}
+	seq_printf(m, "PollList:\n");
+	spin_lock(&ctx->completion_lock);
+	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
+		struct hlist_head *list = &ctx->cancel_hash[i];
+		struct io_kiocb *req;
+
+		hlist_for_each_entry(req, list, hash_node)
+			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,
+					req->task->task_works != NULL);
+	}
+	spin_unlock(&ctx->completion_lock);
+	if (has_lock)
+		mutex_unlock(&ctx->uring_lock);
+}
+
+static void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
+{
+	struct io_ring_ctx *ctx = f->private_data;
+
+	if (percpu_ref_tryget(&ctx->refs)) {
+		__io_uring_show_fdinfo(ctx, m);
+		percpu_ref_put(&ctx->refs);
+	}
+}
+#endif
+
+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,
+#endif
+	.poll		= io_uring_poll,
+#ifdef CONFIG_PROC_FS
+	.show_fdinfo	= io_uring_show_fdinfo,
+#endif
+};
+
+static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
+				  struct io_uring_params *p)
+{
+	struct io_rings *rings;
+	size_t size, sq_array_offset;
+
+	/* 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(p->sq_entries, p->cq_entries, &sq_array_offset);
+	if (size == SIZE_MAX)
+		return -EOVERFLOW;
+
+	rings = io_mem_alloc(size);
+	if (!rings)
+		return -ENOMEM;
+
+	ctx->rings = rings;
+	ctx->sq_array = (u32 *)((char *)rings + sq_array_offset);
+	rings->sq_ring_mask = p->sq_entries - 1;
+	rings->cq_ring_mask = p->cq_entries - 1;
+	rings->sq_ring_entries = p->sq_entries;
+	rings->cq_ring_entries = p->cq_entries;
+
+	size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
+	if (size == SIZE_MAX) {
+		io_mem_free(ctx->rings);
+		ctx->rings = NULL;
+		return -EOVERFLOW;
+	}
+
+	ctx->sq_sqes = io_mem_alloc(size);
+	if (!ctx->sq_sqes) {
+		io_mem_free(ctx->rings);
+		ctx->rings = NULL;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static int io_uring_install_fd(struct io_ring_ctx *ctx, struct file *file)
+{
+	int ret, fd;
+
+	fd = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+	if (fd < 0)
+		return fd;
+
+	ret = io_uring_add_tctx_node(ctx);
+	if (ret) {
+		put_unused_fd(fd);
+		return ret;
+	}
+	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("[io_uring]", &io_uring_fops, ctx,
+					O_RDWR | O_CLOEXEC);
+#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 int io_uring_create(unsigned entries, struct io_uring_params *p,
+			   struct io_uring_params __user *params)
+{
+	struct io_ring_ctx *ctx;
+	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;
+	}
+
+	/*
+	 * 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;
+	ctx->compat = in_compat_syscall();
+	if (!ns_capable_noaudit(&init_user_ns, CAP_IPC_LOCK))
+		ctx->user = get_uid(current_user());
+
+	/*
+	 * 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;
+	/* always set a rsrc node */
+	ret = io_rsrc_node_switch_start(ctx);
+	if (ret)
+		goto err;
+	io_rsrc_node_switch(ctx, NULL);
+
+	memset(&p->sq_off, 0, sizeof(p->sq_off));
+	p->sq_off.head = offsetof(struct io_rings, sq.head);
+	p->sq_off.tail = offsetof(struct io_rings, sq.tail);
+	p->sq_off.ring_mask = offsetof(struct io_rings, sq_ring_mask);
+	p->sq_off.ring_entries = offsetof(struct io_rings, sq_ring_entries);
+	p->sq_off.flags = offsetof(struct io_rings, sq_flags);
+	p->sq_off.dropped = offsetof(struct io_rings, sq_dropped);
+	p->sq_off.array = (char *)ctx->sq_array - (char *)ctx->rings;
+
+	memset(&p->cq_off, 0, sizeof(p->cq_off));
+	p->cq_off.head = offsetof(struct io_rings, cq.head);
+	p->cq_off.tail = offsetof(struct io_rings, cq.tail);
+	p->cq_off.ring_mask = offsetof(struct io_rings, cq_ring_mask);
+	p->cq_off.ring_entries = offsetof(struct io_rings, cq_ring_entries);
+	p->cq_off.overflow = offsetof(struct io_rings, cq_overflow);
+	p->cq_off.cqes = offsetof(struct io_rings, cqes);
+	p->cq_off.flags = offsetof(struct io_rings, cq_flags);
+
+	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;
+
+	if (copy_to_user(params, p, sizeof(*p))) {
+		ret = -EFAULT;
+		goto err;
+	}
+
+	file = io_uring_get_file(ctx);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto err;
+	}
+
+	/*
+	 * Install ring fd as the very last thing, so we don't risk someone
+	 * having closed it before we finish setup
+	 */
+	ret = io_uring_install_fd(ctx, file);
+	if (ret < 0) {
+		/* fput will clean it up */
+		fput(file);
+		return ret;
+	}
+
+	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;
+}
+
+/*
+ * 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))
+		return -EINVAL;
+
+	return  io_uring_create(entries, &p, params);
+}
+
+SYSCALL_DEFINE2(io_uring_setup, u32, entries,
+		struct io_uring_params __user *, params)
+{
+	return io_uring_setup(entries, params);
+}
+
+static 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_op_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 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->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 int __io_register_rsrc_update(struct io_ring_ctx *ctx, unsigned type,
+				     struct io_uring_rsrc_update2 *up,
+				     unsigned nr_args)
+{
+	__u32 tmp;
+	int err;
+
+	if (check_add_overflow(up->offset, nr_args, &tmp))
+		return -EOVERFLOW;
+	err = io_rsrc_node_switch_start(ctx);
+	if (err)
+		return err;
+
+	switch (type) {
+	case IORING_RSRC_FILE:
+		return __io_sqe_files_update(ctx, up, nr_args);
+	case IORING_RSRC_BUFFER:
+		return __io_sqe_buffers_update(ctx, up, nr_args);
+	}
+	return -EINVAL;
+}
+
+static int io_register_files_update(struct io_ring_ctx *ctx, void __user *arg,
+				    unsigned nr_args)
+{
+	struct io_uring_rsrc_update2 up;
+
+	if (!nr_args)
+		return -EINVAL;
+	memset(&up, 0, sizeof(up));
+	if (copy_from_user(&up, arg, sizeof(struct io_uring_rsrc_update)))
+		return -EFAULT;
+	if (up.resv || up.resv2)
+		return -EINVAL;
+	return __io_register_rsrc_update(ctx, IORING_RSRC_FILE, &up, nr_args);
+}
+
+static int io_register_rsrc_update(struct io_ring_ctx *ctx, void __user *arg,
+				   unsigned size, unsigned type)
+{
+	struct io_uring_rsrc_update2 up;
+
+	if (size != sizeof(up))
+		return -EINVAL;
+	if (copy_from_user(&up, arg, sizeof(up)))
+		return -EFAULT;
+	if (!up.nr || up.resv || up.resv2)
+		return -EINVAL;
+	return __io_register_rsrc_update(ctx, type, &up, up.nr);
+}
+
+static int io_register_rsrc(struct io_ring_ctx *ctx, void __user *arg,
+			    unsigned int size, unsigned int type)
+{
+	struct io_uring_rsrc_register rr;
+
+	/* keep it extendible */
+	if (size != sizeof(rr))
+		return -EINVAL;
+
+	memset(&rr, 0, sizeof(rr));
+	if (copy_from_user(&rr, arg, size))
+		return -EFAULT;
+	if (!rr.nr || rr.resv || rr.resv2)
+		return -EINVAL;
+
+	switch (type) {
+	case IORING_RSRC_FILE:
+		return io_sqe_files_register(ctx, u64_to_user_ptr(rr.data),
+					     rr.nr, u64_to_user_ptr(rr.tags));
+	case IORING_RSRC_BUFFER:
+		return io_sqe_buffers_register(ctx, u64_to_user_ptr(rr.data),
+					       rr.nr, u64_to_user_ptr(rr.tags));
+	}
+	return -EINVAL;
+}
+
+static int io_register_iowq_aff(struct io_ring_ctx *ctx, void __user *arg,
+				unsigned len)
+{
+	struct io_uring_task *tctx = current->io_uring;
+	cpumask_var_t new_mask;
+	int ret;
+
+	if (!tctx || !tctx->io_wq)
+		return -EINVAL;
+
+	if (!alloc_cpumask_var(&new_mask, GFP_KERNEL))
+		return -ENOMEM;
+
+	cpumask_clear(new_mask);
+	if (len > cpumask_size())
+		len = cpumask_size();
+
+#ifdef CONFIG_COMPAT
+	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);
+	}
+#else
+	ret = copy_from_user(new_mask, arg, len);
+#endif
+
+	if (ret) {
+		free_cpumask_var(new_mask);
+		return -EFAULT;
+	}
+
+	ret = io_wq_cpu_affinity(tctx->io_wq, new_mask);
+	free_cpumask_var(new_mask);
+	return ret;
+}
+
+static int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
+{
+	struct io_uring_task *tctx = current->io_uring;
+
+	if (!tctx || !tctx->io_wq)
+		return -EINVAL;
+
+	return io_wq_cpu_affinity(tctx->io_wq, NULL);
+}
+
+static 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;
+
+	ret = -EINVAL;
+	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 bool io_register_op_must_quiesce(int op)
+{
+	switch (op) {
+	case IORING_REGISTER_BUFFERS:
+	case IORING_UNREGISTER_BUFFERS:
+	case IORING_REGISTER_FILES:
+	case IORING_UNREGISTER_FILES:
+	case IORING_REGISTER_FILES_UPDATE:
+	case IORING_REGISTER_PROBE:
+	case IORING_REGISTER_PERSONALITY:
+	case IORING_UNREGISTER_PERSONALITY:
+	case IORING_REGISTER_FILES2:
+	case IORING_REGISTER_FILES_UPDATE2:
+	case IORING_REGISTER_BUFFERS2:
+	case IORING_REGISTER_BUFFERS_UPDATE:
+	case IORING_REGISTER_IOWQ_AFF:
+	case IORING_UNREGISTER_IOWQ_AFF:
+	case IORING_REGISTER_IOWQ_MAX_WORKERS:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static int io_ctx_quiesce(struct io_ring_ctx *ctx)
+{
+	long ret;
+
+	percpu_ref_kill(&ctx->refs);
+
+	/*
+	 * Drop uring mutex before waiting for references to exit. If another
+	 * thread is currently inside io_uring_enter() it might need to grab the
+	 * uring_lock to make progress. If we hold it here across the drain
+	 * wait, then we can deadlock. It's safe to drop the mutex here, since
+	 * no new references will come in after we've killed the percpu ref.
+	 */
+	mutex_unlock(&ctx->uring_lock);
+	do {
+		ret = wait_for_completion_interruptible(&ctx->ref_comp);
+		if (!ret)
+			break;
+		ret = io_run_task_work_sig();
+	} while (ret >= 0);
+	mutex_lock(&ctx->uring_lock);
+
+	if (ret)
+		io_refs_resurrect(&ctx->refs, &ctx->ref_comp);
+	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're inside the ring mutex, if the ref is already dying, then
+	 * someone else killed the ctx or is already going through
+	 * io_uring_register().
+	 */
+	if (percpu_ref_is_dying(&ctx->refs))
+		return -ENXIO;
+
+	if (ctx->restricted) {
+		opcode = array_index_nospec(opcode, IORING_REGISTER_LAST);
+		if (!test_bit(opcode, ctx->restrictions.register_op))
+			return -EACCES;
+	}
+
+	if (io_register_op_must_quiesce(opcode)) {
+		ret = io_ctx_quiesce(ctx);
+		if (ret)
+			return ret;
+	}
+
+	switch (opcode) {
+	case IORING_REGISTER_BUFFERS:
+		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 = 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:
+	case IORING_REGISTER_EVENTFD_ASYNC:
+		ret = -EINVAL;
+		if (nr_args != 1)
+			break;
+		ret = io_eventfd_register(ctx, arg);
+		if (ret)
+			break;
+		if (opcode == IORING_REGISTER_EVENTFD_ASYNC)
+			ctx->eventfd_async = 1;
+		else
+			ctx->eventfd_async = 0;
+		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;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	if (io_register_op_must_quiesce(opcode)) {
+		/* bring the ctx back to life */
+		percpu_ref_reinit(&ctx->refs);
+		reinit_completion(&ctx->ref_comp);
+	}
+	return ret;
+}
+
+SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
+		void __user *, arg, unsigned int, nr_args)
+{
+	struct io_ring_ctx *ctx;
+	long ret = -EBADF;
+	struct fd f;
+
+	if (opcode >= IORING_REGISTER_LAST)
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (!f.file)
+		return -EBADF;
+
+	ret = -EOPNOTSUPP;
+	if (f.file->f_op != &io_uring_fops)
+		goto out_fput;
+
+	ctx = f.file->private_data;
+
+	io_run_task_work();
+
+	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,
+							ctx->cq_ev_fd != NULL, ret);
+out_fput:
+	fdput(f);
+	return ret;
+}
+
+static int __init io_uring_init(void)
+{
+#define __BUILD_BUG_VERIFY_ELEMENT(stype, eoffset, etype, ename) do { \
+	BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
+	BUILD_BUG_ON(sizeof(etype) != sizeof_field(stype, ename)); \
+} while (0)
+
+#define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
+	__BUILD_BUG_VERIFY_ELEMENT(struct io_uring_sqe, eoffset, etype, 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(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(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_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(IORING_MAX_REG_BUFFERS >= (1u << 16));
+
+	/* should fit into one byte */
+	BUILD_BUG_ON(SQE_VALID_FLAGS >= (1 << 8));
+
+	BUILD_BUG_ON(ARRAY_SIZE(io_op_defs) != IORING_OP_LAST);
+	BUILD_BUG_ON(__REQ_F_LAST_BIT > 8 * sizeof(int));
+
+	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC |
+				SLAB_ACCOUNT);
+	return 0;
+};
+__initcall(io_uring_init);