io_uring: move to separate directory

In preparation for splitting io_uring up a bit, move it into its own
top level directory. It didn't really belong in fs/ anyway, as it's
not a file system only API.

This adds io_uring/ and moves the core files in there, and updates the
MAINTAINERS file for the new location.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 0 insertions, 1424 deletions

diff --git a/fs/io-wq.c b/fs/io-wq.c
deleted file mode 100644
index 824623bcf1a5..000000000000
--- a/fs/io-wq.c
+++ /dev/null
@@ -1,1424 +0,0 @@
-// 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/task_work.h>
-#include <linux/audit.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;
-	struct io_wq_work *next_work;
-	raw_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;
-	raw_spinlock_t lock;
-	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[IO_WQ_ACCT_NR];
-
-	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);
-}
-
-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);
-	}
-
-	io_worker_release(worker);
-	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);
-	raw_spin_unlock(&wqe->lock);
-	io_wqe_dec_running(worker);
-	worker->flags = 0;
-	preempt_disable();
-	current->flags &= ~PF_IO_WORKER;
-	preempt_enable();
-
-	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)
-{
-	bool ret = false;
-
-	raw_spin_lock(&acct->lock);
-	if (!wq_list_empty(&acct->work_list) &&
-	    !test_bit(IO_ACCT_STALLED_BIT, &acct->flags))
-		ret = true;
-	raw_spin_unlock(&acct->lock);
-
-	return ret;
-}
-
-/*
- * 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)
-{
-	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))
-		return;
-	if (!io_acct_run_queue(acct))
-		return;
-
-	atomic_inc(&acct->nr_running);
-	atomic_inc(&wqe->wq->worker_refs);
-	io_queue_worker_create(worker, acct, create_worker_cb);
-}
-
-/*
- * 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)
-{
-	if (worker->flags & IO_WORKER_F_FREE) {
-		worker->flags &= ~IO_WORKER_F_FREE;
-		raw_spin_lock(&wqe->lock);
-		hlist_nulls_del_init_rcu(&worker->nulls_node);
-		raw_spin_unlock(&wqe->lock);
-	}
-}
-
-/*
- * 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(acct->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(&acct->lock);
-		unstalled = io_wait_on_hash(wqe, stall_hash);
-		raw_spin_lock(&acct->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 (unlikely(test_thread_flag(TIF_NOTIFY_SIGNAL))) {
-		__set_current_state(TASK_RUNNING);
-		clear_notify_signal();
-		if (task_work_pending(current))
-			task_work_run();
-		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();
-	}
-
-	raw_spin_lock(&worker->lock);
-	worker->cur_work = work;
-	worker->next_work = NULL;
-	raw_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)
-{
-	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;
-
-		/*
-		 * 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.
-		 */
-		raw_spin_lock(&acct->lock);
-		work = io_get_next_work(acct, worker);
-		raw_spin_unlock(&acct->lock);
-		if (work) {
-			__io_worker_busy(wqe, worker);
-
-			/*
-			 * Make sure cancelation can find this, even before
-			 * it becomes the active work. That avoids a window
-			 * where the work has been removed from our general
-			 * work list, but isn't yet discoverable as the
-			 * current work item for this worker.
-			 */
-			raw_spin_lock(&worker->lock);
-			worker->next_work = work;
-			raw_spin_unlock(&worker->lock);
-		} else {
-			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);
-			}
-		} while (work);
-	} 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);
-
-	audit_alloc_kernel(current);
-
-	while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
-		long ret;
-
-		set_current_state(TASK_INTERRUPTIBLE);
-		while (io_acct_run_queue(acct))
-			io_worker_handle_work(worker);
-
-		raw_spin_lock(&wqe->lock);
-		/* 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))
-		io_worker_handle_work(worker);
-
-	audit_free(current);
-	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->worker_private;
-
-	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->worker_private;
-
-	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_dec_running(worker);
-}
-
-static void io_init_new_worker(struct io_wqe *wqe, struct io_worker *worker,
-			       struct task_struct *tsk)
-{
-	tsk->worker_private = 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,
-			};
-
-			raw_spin_unlock(&wqe->lock);
-			while (io_acct_cancel_pending_work(wqe, acct, &match))
-				;
-		} else {
-			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;
-	raw_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);
-	struct io_cb_cancel_data match;
-	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(&acct->lock);
-	io_wqe_insert_work(wqe, work);
-	clear_bit(IO_ACCT_STALLED_BIT, &acct->flags);
-	raw_spin_unlock(&acct->lock);
-
-	raw_spin_lock(&wqe->lock);
-	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);
-		if (acct->nr_workers) {
-			raw_spin_unlock(&wqe->lock);
-			return;
-		}
-		raw_spin_unlock(&wqe->lock);
-
-		/* fatal condition, failed to create the first worker */
-		match.fn		= io_wq_work_match_item,
-		match.data		= work,
-		match.cancel_all	= false,
-
-		io_acct_cancel_pending_work(wqe, acct, &match);
-	}
-}
-
-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,
-				  struct io_cb_cancel_data *match,
-				  struct io_wq_work *work)
-{
-	if (work && match->fn(work, match->data)) {
-		work->flags |= IO_WQ_WORK_CANCEL;
-		__set_notify_signal(worker->task);
-		return true;
-	}
-
-	return false;
-}
-
-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.
-	 */
-	raw_spin_lock(&worker->lock);
-	if (__io_wq_worker_cancel(worker, match, worker->cur_work) ||
-	    __io_wq_worker_cancel(worker, match, worker->next_work))
-		match->nr_running++;
-	raw_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)
-{
-	struct io_wq_work_node *node, *prev;
-	struct io_wq_work *work;
-
-	raw_spin_lock(&acct->lock);
-	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(&acct->lock);
-		io_run_cancel(work, wqe);
-		match->nr_pending++;
-		/* not safe to continue after unlock */
-		return true;
-	}
-	raw_spin_unlock(&acct->lock);
-
-	return false;
-}
-
-static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
-				       struct io_cb_cancel_data *match)
-{
-	int i;
-retry:
-	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;
-			break;
-		}
-	}
-}
-
-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.
-	 *
-	 * Then 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.
-	 *
-	 * Do both of these while holding the wqe->lock, to ensure that
-	 * we'll find a work item regardless of state.
-	 */
-	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;
-
-		raw_spin_lock(&wqe->lock);
-		io_wqe_cancel_running_work(wqe, &match);
-		raw_spin_unlock(&wqe->lock);
-		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;
-		if (!alloc_cpumask_var(&wqe->cpu_mask, GFP_KERNEL))
-			goto err;
-		cpumask_copy(wqe->cpu_mask, cpumask_of_node(node));
-		wq->wqes[node] = wqe;
-		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);
-			raw_spin_lock_init(&acct->lock);
-		}
-		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);
-	}
-}
-
-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 < IO_WQ_ACCT_NR; 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);