Merge tag 'for-5.15/io_uring-2021-08-30' of git://git.kernel.dk/linux-block

Pull io_uring updates from Jens Axboe:

 - cancellation cleanups (Hao, Pavel)

 - io-wq accounting cleanup (Hao)

 - io_uring submit locking fix (Hao)

 - io_uring link handling fixes (Hao)

 - fixed file improvements (wangyangbo, Pavel)

 - allow updates of linked timeouts like regular timeouts (Pavel)

 - IOPOLL fix (Pavel)

 - remove batched file get optimization (Pavel)

 - improve reference handling (Pavel)

 - IRQ task_work batching (Pavel)

 - allow pure fixed file, and add support for open/accept (Pavel)

 - GFP_ATOMIC RT kernel fix

 - multiple CQ ring waiter improvement

 - funnel IRQ completions through task_work

 - add support for limiting async workers explicitly

 - add different clocksource support for timeouts

 - io-wq wakeup race fix

 - lots of cleanups and improvement (Pavel et al)

* tag 'for-5.15/io_uring-2021-08-30' of git://git.kernel.dk/linux-block: (87 commits)
  io-wq: fix wakeup race when adding new work
  io-wq: wqe and worker locks no longer need to be IRQ safe
  io-wq: check max_worker limits if a worker transitions bound state
  io_uring: allow updating linked timeouts
  io_uring: keep ltimeouts in a list
  io_uring: support CLOCK_BOOTTIME/REALTIME for timeouts
  io-wq: provide a way to limit max number of workers
  io_uring: add build check for buf_index overflows
  io_uring: clarify io_req_task_cancel() locking
  io_uring: add task-refs-get helper
  io_uring: fix failed linkchain code logic
  io_uring: remove redundant req_set_fail()
  io_uring: don't free request to slab
  io_uring: accept directly into fixed file table
  io_uring: hand code io_accept() fd installing
  io_uring: openat directly into fixed fd table
  net: add accept helper not installing fd
  io_uring: fix io_try_cancel_userdata race for iowq
  io_uring: IRQ rw completion batching
  io_uring: batch task work locking
  ...

8 files changed, 1216 insertions, 845 deletions

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 7d2ed8c7dd3128..cd9bd095fb1bbb 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -51,6 +51,10 @@ struct io_worker {
 
 	struct completion ref_done;
 
+	unsigned long create_state;
+	struct callback_head create_work;
+	int create_index;
+
 	struct rcu_head rcu;
 };
 
@@ -174,7 +178,7 @@ static void io_worker_exit(struct io_worker *worker)
 		complete(&worker->ref_done);
 	wait_for_completion(&worker->ref_done);
 
-	raw_spin_lock_irq(&wqe->lock);
+	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);
@@ -184,7 +188,7 @@ static void io_worker_exit(struct io_worker *worker)
 	worker->flags = 0;
 	current->flags &= ~PF_IO_WORKER;
 	preempt_enable();
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_unlock(&wqe->lock);
 
 	kfree_rcu(worker, rcu);
 	io_worker_ref_put(wqe->wq);
@@ -250,18 +254,19 @@ static void io_wqe_wake_worker(struct io_wqe *wqe, struct io_wqe_acct *acct)
 	if (!ret) {
 		bool do_create = false, first = false;
 
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		if (acct->nr_workers < acct->max_workers) {
-			atomic_inc(&acct->nr_running);
-			atomic_inc(&wqe->wq->worker_refs);
 			if (!acct->nr_workers)
 				first = true;
 			acct->nr_workers++;
 			do_create = true;
 		}
-		raw_spin_unlock_irq(&wqe->lock);
-		if (do_create)
+		raw_spin_unlock(&wqe->lock);
+		if (do_create) {
+			atomic_inc(&acct->nr_running);
+			atomic_inc(&wqe->wq->worker_refs);
 			create_io_worker(wqe->wq, wqe, acct->index, first);
+		}
 	}
 }
 
@@ -272,60 +277,63 @@ static void io_wqe_inc_running(struct io_worker *worker)
 	atomic_inc(&acct->nr_running);
 }
 
-struct create_worker_data {
-	struct callback_head work;
-	struct io_wqe *wqe;
-	int index;
-};
-
 static void create_worker_cb(struct callback_head *cb)
 {
-	struct create_worker_data *cwd;
+	struct io_worker *worker;
 	struct io_wq *wq;
 	struct io_wqe *wqe;
 	struct io_wqe_acct *acct;
 	bool do_create = false, first = false;
 
-	cwd = container_of(cb, struct create_worker_data, work);
-	wqe = cwd->wqe;
+	worker = container_of(cb, struct io_worker, create_work);
+	wqe = worker->wqe;
 	wq = wqe->wq;
-	acct = &wqe->acct[cwd->index];
-	raw_spin_lock_irq(&wqe->lock);
+	acct = &wqe->acct[worker->create_index];
+	raw_spin_lock(&wqe->lock);
 	if (acct->nr_workers < acct->max_workers) {
 		if (!acct->nr_workers)
 			first = true;
 		acct->nr_workers++;
 		do_create = true;
 	}
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_unlock(&wqe->lock);
 	if (do_create) {
-		create_io_worker(wq, wqe, cwd->index, first);
+		create_io_worker(wq, wqe, worker->create_index, first);
 	} else {
 		atomic_dec(&acct->nr_running);
 		io_worker_ref_put(wq);
 	}
-	kfree(cwd);
+	clear_bit_unlock(0, &worker->create_state);
+	io_worker_release(worker);
 }
 
-static void io_queue_worker_create(struct io_wqe *wqe, struct io_wqe_acct *acct)
+static void io_queue_worker_create(struct io_wqe *wqe, struct io_worker *worker,
+				   struct io_wqe_acct *acct)
 {
-	struct create_worker_data *cwd;
 	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;
 
-	cwd = kmalloc(sizeof(*cwd), GFP_ATOMIC);
-	if (cwd) {
-		init_task_work(&cwd->work, create_worker_cb);
-		cwd->wqe = wqe;
-		cwd->index = acct->index;
-		if (!task_work_add(wq->task, &cwd->work, TWA_SIGNAL))
-			return;
-
-		kfree(cwd);
-	}
+	init_task_work(&worker->create_work, create_worker_cb);
+	worker->create_index = acct->index;
+	if (!task_work_add(wq->task, &worker->create_work, TWA_SIGNAL))
+		return;
+	clear_bit_unlock(0, &worker->create_state);
+fail_release:
+	io_worker_release(worker);
 fail:
 	atomic_dec(&acct->nr_running);
 	io_worker_ref_put(wq);
@@ -343,7 +351,7 @@ static void io_wqe_dec_running(struct io_worker *worker)
 	if (atomic_dec_and_test(&acct->nr_running) && io_wqe_run_queue(wqe)) {
 		atomic_inc(&acct->nr_running);
 		atomic_inc(&wqe->wq->worker_refs);
-		io_queue_worker_create(wqe, acct);
+		io_queue_worker_create(wqe, worker, acct);
 	}
 }
 
@@ -416,7 +424,28 @@ static void io_wait_on_hash(struct io_wqe *wqe, unsigned int hash)
 	spin_unlock(&wq->hash->wait.lock);
 }
 
-static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
+/*
+ * We can always run the work if the worker is currently the same type as
+ * the work (eg both are bound, or both are unbound). If they are not the
+ * same, only allow it if incrementing the worker count would be allowed.
+ */
+static bool io_worker_can_run_work(struct io_worker *worker,
+				   struct io_wq_work *work)
+{
+	struct io_wqe_acct *acct;
+
+	if (!(worker->flags & IO_WORKER_F_BOUND) !=
+	    !(work->flags & IO_WQ_WORK_UNBOUND))
+		return true;
+
+	/* not the same type, check if we'd go over the limit */
+	acct = io_work_get_acct(worker->wqe, work);
+	return acct->nr_workers < acct->max_workers;
+}
+
+static struct io_wq_work *io_get_next_work(struct io_wqe *wqe,
+					   struct io_worker *worker,
+					   bool *stalled)
 	__must_hold(wqe->lock)
 {
 	struct io_wq_work_node *node, *prev;
@@ -428,6 +457,9 @@ static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
 
 		work = container_of(node, struct io_wq_work, list);
 
+		if (!io_worker_can_run_work(worker, work))
+			break;
+
 		/* not hashed, can run anytime */
 		if (!io_wq_is_hashed(work)) {
 			wq_list_del(&wqe->work_list, node, prev);
@@ -454,6 +486,7 @@ static struct io_wq_work *io_get_next_work(struct io_wqe *wqe)
 		raw_spin_unlock(&wqe->lock);
 		io_wait_on_hash(wqe, stall_hash);
 		raw_spin_lock(&wqe->lock);
+		*stalled = true;
 	}
 
 	return NULL;
@@ -477,9 +510,9 @@ static void io_assign_current_work(struct io_worker *worker,
 		cond_resched();
 	}
 
-	spin_lock_irq(&worker->lock);
+	spin_lock(&worker->lock);
 	worker->cur_work = work;
-	spin_unlock_irq(&worker->lock);
+	spin_unlock(&worker->lock);
 }
 
 static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work);
@@ -493,6 +526,7 @@ static void io_worker_handle_work(struct io_worker *worker)
 
 	do {
 		struct io_wq_work *work;
+		bool stalled;
 get_next:
 		/*
 		 * If we got some work, mark us as busy. If we didn't, but
@@ -501,13 +535,14 @@ get_next:
 		 * can't make progress, any work completion or insertion will
 		 * clear the stalled flag.
 		 */
-		work = io_get_next_work(wqe);
+		stalled = false;
+		work = io_get_next_work(wqe, worker, &stalled);
 		if (work)
 			__io_worker_busy(wqe, worker, work);
-		else if (!wq_list_empty(&wqe->work_list))
+		else if (stalled)
 			wqe->flags |= IO_WQE_FLAG_STALLED;
 
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		if (!work)
 			break;
 		io_assign_current_work(worker, work);
@@ -539,16 +574,16 @@ get_next:
 				clear_bit(hash, &wq->hash->map);
 				if (wq_has_sleeper(&wq->hash->wait))
 					wake_up(&wq->hash->wait);
-				raw_spin_lock_irq(&wqe->lock);
+				raw_spin_lock(&wqe->lock);
 				wqe->flags &= ~IO_WQE_FLAG_STALLED;
 				/* skip unnecessary unlock-lock wqe->lock */
 				if (!work)
 					goto get_next;
-				raw_spin_unlock_irq(&wqe->lock);
+				raw_spin_unlock(&wqe->lock);
 			}
 		} while (work);
 
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 	} while (1);
 }
 
@@ -569,13 +604,13 @@ static int io_wqe_worker(void *data)
 
 		set_current_state(TASK_INTERRUPTIBLE);
 loop:
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		if (io_wqe_run_queue(wqe)) {
 			io_worker_handle_work(worker);
 			goto loop;
 		}
 		__io_worker_idle(wqe, worker);
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		if (io_flush_signals())
 			continue;
 		ret = schedule_timeout(WORKER_IDLE_TIMEOUT);
@@ -594,7 +629,7 @@ loop:
 	}
 
 	if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		io_worker_handle_work(worker);
 	}
 
@@ -636,9 +671,9 @@ void io_wq_worker_sleeping(struct task_struct *tsk)
 
 	worker->flags &= ~IO_WORKER_F_RUNNING;
 
-	raw_spin_lock_irq(&worker->wqe->lock);
+	raw_spin_lock(&worker->wqe->lock);
 	io_wqe_dec_running(worker);
-	raw_spin_unlock_irq(&worker->wqe->lock);
+	raw_spin_unlock(&worker->wqe->lock);
 }
 
 static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bool first)
@@ -664,9 +699,9 @@ static void create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index, bo
 		kfree(worker);
 fail:
 		atomic_dec(&acct->nr_running);
-		raw_spin_lock_irq(&wqe->lock);
+		raw_spin_lock(&wqe->lock);
 		acct->nr_workers--;
-		raw_spin_unlock_irq(&wqe->lock);
+		raw_spin_unlock(&wqe->lock);
 		io_worker_ref_put(wq);
 		return;
 	}
@@ -676,7 +711,7 @@ fail:
 	set_cpus_allowed_ptr(tsk, wqe->cpu_mask);
 	tsk->flags |= PF_NO_SETAFFINITY;
 
-	raw_spin_lock_irq(&wqe->lock);
+	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;
@@ -684,7 +719,7 @@ fail:
 		worker->flags |= IO_WORKER_F_BOUND;
 	if (first && (worker->flags & IO_WORKER_F_BOUND))
 		worker->flags |= IO_WORKER_F_FIXED;
-	raw_spin_unlock_irq(&wqe->lock);
+	raw_spin_unlock(&wqe->lock);
 	wake_up_new_task(tsk);
 }
 
@@ -759,8 +794,7 @@ append:
 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);
-	int work_flags;
-	unsigned long flags;
+	bool do_wake;
 
 	/*
 	 * If io-wq is exiting for this task, or if the request has explicitly
@@ -772,14 +806,14 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
 		return;
 	}
 
-	work_flags = work->flags;
-	raw_spin_lock_irqsave(&wqe->lock, flags);
+	raw_spin_lock(&wqe->lock);
 	io_wqe_insert_work(wqe, work);
 	wqe->flags &= ~IO_WQE_FLAG_STALLED;
-	raw_spin_unlock_irqrestore(&wqe->lock, flags);
+	do_wake = (work->flags & IO_WQ_WORK_CONCURRENT) ||
+			!atomic_read(&acct->nr_running);
+	raw_spin_unlock(&wqe->lock);
 
-	if ((work_flags & IO_WQ_WORK_CONCURRENT) ||
-	    !atomic_read(&acct->nr_running))
+	if (do_wake)
 		io_wqe_wake_worker(wqe, acct);
 }
 
@@ -805,19 +839,18 @@ void io_wq_hash_work(struct io_wq_work *work, void *val)
 static bool io_wq_worker_cancel(struct io_worker *worker, void *data)
 {
 	struct io_cb_cancel_data *match = data;
-	unsigned long flags;
 
 	/*
 	 * Hold the lock to avoid ->cur_work going out of scope, caller
 	 * may dereference the passed in work.
 	 */
-	spin_lock_irqsave(&worker->lock, flags);
+	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_irqrestore(&worker->lock, flags);
+	spin_unlock(&worker->lock);
 
 	return match->nr_running && !match->cancel_all;
 }
@@ -845,16 +878,15 @@ static void io_wqe_cancel_pending_work(struct io_wqe *wqe,
 {
 	struct io_wq_work_node *node, *prev;
 	struct io_wq_work *work;
-	unsigned long flags;
 
 retry:
-	raw_spin_lock_irqsave(&wqe->lock, flags);
+	raw_spin_lock(&wqe->lock);
 	wq_list_for_each(node, prev, &wqe->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_irqrestore(&wqe->lock, flags);
+		raw_spin_unlock(&wqe->lock);
 		io_run_cancel(work, wqe);
 		match->nr_pending++;
 		if (!match->cancel_all)
@@ -863,7 +895,7 @@ retry:
 		/* not safe to continue after unlock */
 		goto retry;
 	}
-	raw_spin_unlock_irqrestore(&wqe->lock, flags);
+	raw_spin_unlock(&wqe->lock);
 }
 
 static void io_wqe_cancel_running_work(struct io_wqe *wqe,
@@ -1004,12 +1036,12 @@ err_wq:
 
 static bool io_task_work_match(struct callback_head *cb, void *data)
 {
-	struct create_worker_data *cwd;
+	struct io_worker *worker;
 
 	if (cb->func != create_worker_cb)
 		return false;
-	cwd = container_of(cb, struct create_worker_data, work);
-	return cwd->wqe->wq == data;
+	worker = container_of(cb, struct io_worker, create_work);
+	return worker->wqe->wq == data;
 }
 
 void io_wq_exit_start(struct io_wq *wq)
@@ -1026,12 +1058,13 @@ static void io_wq_exit_workers(struct io_wq *wq)
 		return;
 
 	while ((cb = task_work_cancel_match(wq->task, io_task_work_match, wq)) != NULL) {
-		struct create_worker_data *cwd;
+		struct io_worker *worker;
 
-		cwd = container_of(cb, struct create_worker_data, work);
-		atomic_dec(&cwd->wqe->acct[cwd->index].nr_running);
+		worker = container_of(cb, struct io_worker, create_work);
+		atomic_dec(&worker->wqe->acct[worker->create_index].nr_running);
 		io_worker_ref_put(wq);
-		kfree(cwd);
+		clear_bit_unlock(0, &worker->create_state);
+		io_worker_release(worker);
 	}
 
 	rcu_read_lock();
@@ -1143,6 +1176,35 @@ int io_wq_cpu_affinity(struct io_wq *wq, cpumask_var_t mask)
 	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 i, node, prev = 0;
+
+	for (i = 0; i < 2; i++) {
+		if (new_count[i] > task_rlimit(current, RLIMIT_NPROC))
+			new_count[i] = task_rlimit(current, RLIMIT_NPROC);
+	}
+
+	rcu_read_lock();
+	for_each_node(node) {
+		struct io_wqe_acct *acct;
+
+		for (i = 0; i < 2; i++) {
+			acct = &wq->wqes[node]->acct[i];
+			prev = max_t(int, acct->max_workers, prev);
+			if (new_count[i])
+				acct->max_workers = new_count[i];
+			new_count[i] = prev;
+		}
+	}
+	rcu_read_unlock();
+	return 0;
+}
+
 static __init int io_wq_init(void)
 {
 	int ret;
diff --git a/fs/io-wq.h b/fs/io-wq.h
index 3999ee58ff26dd..bf5c4c53376057 100644
--- a/fs/io-wq.h
+++ b/fs/io-wq.h
@@ -44,6 +44,7 @@ static inline void wq_list_add_after(struct io_wq_work_node *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);
@@ -51,7 +52,6 @@ static inline void wq_list_add_tail(struct io_wq_work_node *node,
 		list->last->next = node;
 		list->last = node;
 	}
-	node->next = NULL;
 }
 
 static inline void wq_list_cut(struct io_wq_work_list *list,
@@ -128,6 +128,7 @@ 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);
 
 static inline bool io_wq_is_hashed(struct io_wq_work *work)
 {
diff --git a/fs/io_uring.c b/fs/io_uring.c
index a2e20a6fbfed8e..7cc458e0b636c6 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -92,17 +92,12 @@
 #define IORING_MAX_CQ_ENTRIES	(2 * IORING_MAX_ENTRIES)
 #define IORING_SQPOLL_CAP_ENTRIES_VALUE 8
 
-/*
- * Shift of 9 is 512 entries, or exactly one page on 64-bit archs
- */
-#define IORING_FILE_TABLE_SHIFT	9
-#define IORING_MAX_FILES_TABLE	(1U << IORING_FILE_TABLE_SHIFT)
-#define IORING_FILE_TABLE_MASK	(IORING_MAX_FILES_TABLE - 1)
-#define IORING_MAX_FIXED_FILES	(64 * IORING_MAX_FILES_TABLE)
+/* 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	9
+#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)
 
@@ -235,8 +230,7 @@ struct io_rsrc_put {
 };
 
 struct io_file_table {
-	/* two level table */
-	struct io_fixed_file **files;
+	struct io_fixed_file *files;
 };
 
 struct io_rsrc_node {
@@ -301,18 +295,10 @@ struct io_sq_data {
 	struct completion	exited;
 };
 
-#define IO_IOPOLL_BATCH			8
 #define IO_COMPL_BATCH			32
 #define IO_REQ_CACHE_SIZE		32
 #define IO_REQ_ALLOC_BATCH		8
 
-struct io_comp_state {
-	struct io_kiocb		*reqs[IO_COMPL_BATCH];
-	unsigned int		nr;
-	/* inline/task_work completion list, under ->uring_lock */
-	struct list_head	free_list;
-};
-
 struct io_submit_link {
 	struct io_kiocb		*head;
 	struct io_kiocb		*last;
@@ -333,14 +319,11 @@ struct io_submit_state {
 	/*
 	 * Batch completion logic
 	 */
-	struct io_comp_state	comp;
+	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;
 
-	/*
-	 * File reference cache
-	 */
-	struct file		*file;
-	unsigned int		fd;
-	unsigned int		file_refs;
 	unsigned int		ios_left;
 };
 
@@ -392,6 +375,7 @@ struct io_ring_ctx {
 
 		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;
@@ -426,6 +410,8 @@ struct io_ring_ctx {
 	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.
@@ -487,8 +473,8 @@ struct io_uring_task {
 
 	spinlock_t		task_lock;
 	struct io_wq_work_list	task_list;
-	unsigned long		task_state;
 	struct callback_head	task_work;
+	bool			task_running;
 };
 
 /*
@@ -523,6 +509,7 @@ struct io_timeout_data {
 	struct hrtimer			timer;
 	struct timespec64		ts;
 	enum hrtimer_mode		mode;
+	u32				flags;
 };
 
 struct io_accept {
@@ -530,6 +517,7 @@ struct io_accept {
 	struct sockaddr __user		*addr;
 	int __user			*addr_len;
 	int				flags;
+	u32				file_slot;
 	unsigned long			nofile;
 };
 
@@ -553,6 +541,8 @@ struct io_timeout {
 	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 {
@@ -562,6 +552,7 @@ struct io_timeout_rem {
 	/* timeout update */
 	struct timespec64		ts;
 	u32				flags;
+	bool				ltimeout;
 };
 
 struct io_rw {
@@ -593,6 +584,7 @@ struct io_sr_msg {
 struct io_open {
 	struct file			*file;
 	int				dfd;
+	u32				file_slot;
 	struct filename			*filename;
 	struct open_how			how;
 	unsigned long			nofile;
@@ -677,7 +669,6 @@ struct io_unlink {
 
 struct io_completion {
 	struct file			*file;
-	struct list_head		list;
 	u32				cflags;
 };
 
@@ -719,14 +710,15 @@ enum {
 	REQ_F_NEED_CLEANUP_BIT,
 	REQ_F_POLLED_BIT,
 	REQ_F_BUFFER_SELECTED_BIT,
-	REQ_F_LTIMEOUT_ACTIVE_BIT,
 	REQ_F_COMPLETE_INLINE_BIT,
 	REQ_F_REISSUE_BIT,
 	REQ_F_DONT_REISSUE_BIT,
 	REQ_F_CREDS_BIT,
+	REQ_F_REFCOUNT_BIT,
+	REQ_F_ARM_LTIMEOUT_BIT,
 	/* keep async read/write and isreg together and in order */
-	REQ_F_ASYNC_READ_BIT,
-	REQ_F_ASYNC_WRITE_BIT,
+	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 */
@@ -763,8 +755,6 @@ enum {
 	REQ_F_POLLED		= BIT(REQ_F_POLLED_BIT),
 	/* buffer already selected */
 	REQ_F_BUFFER_SELECTED	= BIT(REQ_F_BUFFER_SELECTED_BIT),
-	/* linked timeout is active, i.e. prepared by link's head */
-	REQ_F_LTIMEOUT_ACTIVE	= BIT(REQ_F_LTIMEOUT_ACTIVE_BIT),
 	/* completion is deferred through io_comp_state */
 	REQ_F_COMPLETE_INLINE	= BIT(REQ_F_COMPLETE_INLINE_BIT),
 	/* caller should reissue async */
@@ -772,13 +762,17 @@ enum {
 	/* don't attempt request reissue, see io_rw_reissue() */
 	REQ_F_DONT_REISSUE	= BIT(REQ_F_DONT_REISSUE_BIT),
 	/* supports async reads */
-	REQ_F_ASYNC_READ	= BIT(REQ_F_ASYNC_READ_BIT),
+	REQ_F_NOWAIT_READ	= BIT(REQ_F_NOWAIT_READ_BIT),
 	/* supports async writes */
-	REQ_F_ASYNC_WRITE	= BIT(REQ_F_ASYNC_WRITE_BIT),
+	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),
 };
 
 struct async_poll {
@@ -786,7 +780,7 @@ struct async_poll {
 	struct io_poll_iocb	*double_poll;
 };
 
-typedef void (*io_req_tw_func_t)(struct io_kiocb *req);
+typedef void (*io_req_tw_func_t)(struct io_kiocb *req, bool *locked);
 
 struct io_task_work {
 	union {
@@ -1045,37 +1039,38 @@ static const struct io_op_def io_op_defs[] = {
 	[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 struct io_rsrc_node *io_rsrc_node_alloc(struct io_ring_ctx *ctx);
 
 static bool io_cqring_fill_event(struct io_ring_ctx *ctx, u64 user_data,
 				 long res, unsigned int cflags);
 static void io_put_req(struct io_kiocb *req);
-static void io_put_req_deferred(struct io_kiocb *req, int nr);
+static void io_put_req_deferred(struct io_kiocb *req);
 static void io_dismantle_req(struct io_kiocb *req);
-static void io_put_task(struct task_struct *task, int nr);
-static struct io_kiocb *io_prep_linked_timeout(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_submit_state *state,
+static struct file *io_file_get(struct io_ring_ctx *ctx,
 				struct io_kiocb *req, int fd, bool fixed);
 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 bool io_poll_remove_waitqs(struct io_kiocb *req);
 static int io_req_prep_async(struct io_kiocb *req);
 
-static void io_fallback_req_func(struct work_struct *unused);
+static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
+				 unsigned int issue_flags, u32 slot_index);
+static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer);
 
 static struct kmem_cache *req_cachep;
 
@@ -1094,9 +1089,65 @@ struct sock *io_uring_get_socket(struct file *file)
 }
 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_put(struct io_kiocb *req)
+{
+	WARN_ON_ONCE(!(req->flags & REQ_F_REFCOUNT));
+	WARN_ON_ONCE(req_ref_put_and_test(req));
+}
+
+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;
@@ -1141,6 +1192,12 @@ 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);
@@ -1153,6 +1210,27 @@ 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;
@@ -1198,15 +1276,17 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	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.comp.free_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;
@@ -1236,6 +1316,20 @@ static bool req_need_defer(struct io_kiocb *req, u32 seq)
 	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)) {
@@ -1244,6 +1338,32 @@ static void io_req_track_inflight(struct io_kiocb *req)
 	}
 }
 
+static inline void io_unprep_linked_timeout(struct io_kiocb *req)
+{
+	req->flags &= ~REQ_F_LINK_TIMEOUT;
+}
+
+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];
@@ -1283,22 +1403,25 @@ static void io_prep_async_link(struct io_kiocb *req)
 	if (req->flags & REQ_F_LINK_TIMEOUT) {
 		struct io_ring_ctx *ctx = req->ctx;
 
-		spin_lock_irq(&ctx->completion_lock);
+		spin_lock(&ctx->completion_lock);
 		io_for_each_link(cur, req)
 			io_prep_async_work(cur);
-		spin_unlock_irq(&ctx->completion_lock);
+		spin_unlock(&ctx->completion_lock);
 	} else {
 		io_for_each_link(cur, req)
 			io_prep_async_work(cur);
 	}
 }
 
-static void io_queue_async_work(struct io_kiocb *req)
+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);
 
@@ -1324,6 +1447,7 @@ static void io_queue_async_work(struct io_kiocb *req)
 
 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;
 
@@ -1332,7 +1456,7 @@ static void io_kill_timeout(struct io_kiocb *req, int status)
 			atomic_read(&req->ctx->cq_timeouts) + 1);
 		list_del_init(&req->timeout.list);
 		io_cqring_fill_event(req->ctx, req->user_data, status, 0);
-		io_put_req_deferred(req, 1);
+		io_put_req_deferred(req);
 	}
 }
 
@@ -1351,9 +1475,11 @@ static void io_queue_deferred(struct io_ring_ctx *ctx)
 }
 
 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);
 
+	spin_lock_irq(&ctx->timeout_lock);
 	while (!list_empty(&ctx->timeout_list)) {
 		u32 events_needed, events_got;
 		struct io_kiocb *req = list_first_entry(&ctx->timeout_list,
@@ -1378,6 +1504,7 @@ static void io_flush_timeouts(struct io_ring_ctx *ctx)
 		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)
@@ -1434,13 +1561,22 @@ static inline bool io_should_trigger_evfd(struct io_ring_ctx *ctx)
 	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)
 {
-	/* see waitqueue_active() comment */
-	smp_mb();
-
-	if (waitqueue_active(&ctx->cq_wait))
-		wake_up(&ctx->cq_wait);
+	/*
+	 * 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_all(&ctx->cq_wait);
 	if (ctx->sq_data && waitqueue_active(&ctx->sq_data->wait))
 		wake_up(&ctx->sq_data->wait);
 	if (io_should_trigger_evfd(ctx))
@@ -1453,12 +1589,9 @@ static void io_cqring_ev_posted(struct io_ring_ctx *ctx)
 
 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);
+		if (wq_has_sleeper(&ctx->cq_wait))
+			wake_up_all(&ctx->cq_wait);
 	}
 	if (io_should_trigger_evfd(ctx))
 		eventfd_signal(ctx->cq_ev_fd, 1);
@@ -1471,14 +1604,13 @@ static void io_cqring_ev_posted_iopoll(struct io_ring_ctx *ctx)
 /* Returns true if there are no backlogged entries after the flush */
 static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
 {
-	unsigned long flags;
 	bool all_flushed, posted;
 
 	if (!force && __io_cqring_events(ctx) == ctx->cq_entries)
 		return false;
 
 	posted = false;
-	spin_lock_irqsave(&ctx->completion_lock, flags);
+	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;
@@ -1506,13 +1638,13 @@ static bool __io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
 
 	if (posted)
 		io_commit_cqring(ctx);
-	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+	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 force)
+static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx)
 {
 	bool ret = true;
 
@@ -1520,7 +1652,7 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
 		/* 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, force);
+		ret = __io_cqring_overflow_flush(ctx, false);
 		if (ctx->flags & IORING_SETUP_IOPOLL)
 			mutex_unlock(&ctx->uring_lock);
 	}
@@ -1528,39 +1660,37 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
 	return ret;
 }
 
-/*
- * 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)
+/* must to be called somewhat shortly after putting a request */
+static inline void io_put_task(struct task_struct *task, int nr)
 {
-	return atomic_inc_not_zero(&req->refs);
-}
+	struct io_uring_task *tctx = task->io_uring;
 
-static inline bool req_ref_sub_and_test(struct io_kiocb *req, int refs)
-{
-	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
-	return atomic_sub_and_test(refs, &req->refs);
+	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 inline bool req_ref_put_and_test(struct io_kiocb *req)
+static void io_task_refs_refill(struct io_uring_task *tctx)
 {
-	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
-	return atomic_dec_and_test(&req->refs);
-}
+	unsigned int refill = -tctx->cached_refs + IO_TCTX_REFS_CACHE_NR;
 
-static inline void req_ref_put(struct io_kiocb *req)
-{
-	WARN_ON_ONCE(req_ref_put_and_test(req));
+	percpu_counter_add(&tctx->inflight, refill);
+	refcount_add(refill, &current->usage);
+	tctx->cached_refs += refill;
 }
 
-static inline void req_ref_get(struct io_kiocb *req)
+static inline void io_get_task_refs(int nr)
 {
-	WARN_ON_ONCE(req_ref_zero_or_close_to_overflow(req));
-	atomic_inc(&req->refs);
+	struct io_uring_task *tctx = current->io_uring;
+
+	tctx->cached_refs -= nr;
+	if (unlikely(tctx->cached_refs < 0))
+		io_task_refs_refill(tctx);
 }
 
 static bool io_cqring_event_overflow(struct io_ring_ctx *ctx, u64 user_data,
@@ -1624,9 +1754,8 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
 				 unsigned int cflags)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	unsigned long flags;
 
-	spin_lock_irqsave(&ctx->completion_lock, flags);
+	spin_lock(&ctx->completion_lock);
 	__io_cqring_fill_event(ctx, req->user_data, res, cflags);
 	/*
 	 * If we're the last reference to this request, add to our locked
@@ -1634,7 +1763,7 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
 	 */
 	if (req_ref_put_and_test(req)) {
 		if (req->flags & (REQ_F_LINK | REQ_F_HARDLINK)) {
-			if (req->flags & (REQ_F_LINK_TIMEOUT | REQ_F_FAIL))
+			if (req->flags & IO_DISARM_MASK)
 				io_disarm_next(req);
 			if (req->link) {
 				io_req_task_queue(req->link);
@@ -1643,14 +1772,14 @@ static void io_req_complete_post(struct io_kiocb *req, long res,
 		}
 		io_dismantle_req(req);
 		io_put_task(req->task, 1);
-		list_add(&req->compl.list, &ctx->locked_free_list);
+		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_irqrestore(&ctx->completion_lock, flags);
+	spin_unlock(&ctx->completion_lock);
 
 	if (req) {
 		io_cqring_ev_posted(ctx);
@@ -1690,24 +1819,35 @@ static inline void io_req_complete(struct io_kiocb *req, long res)
 static void io_req_complete_failed(struct io_kiocb *req, long res)
 {
 	req_set_fail(req);
-	io_put_req(req);
 	io_req_complete_post(req, res, 0);
 }
 
+/*
+ * 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_comp_state *cs)
+					struct io_submit_state *state)
 {
-	spin_lock_irq(&ctx->completion_lock);
-	list_splice_init(&ctx->locked_free_list, &cs->free_list);
+	spin_lock(&ctx->completion_lock);
+	list_splice_init(&ctx->locked_free_list, &state->free_list);
 	ctx->locked_free_nr = 0;
-	spin_unlock_irq(&ctx->completion_lock);
+	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;
-	struct io_comp_state *cs = &state->comp;
 	int nr;
 
 	/*
@@ -1716,14 +1856,14 @@ static bool io_flush_cached_reqs(struct io_ring_ctx *ctx)
 	 * side cache.
 	 */
 	if (READ_ONCE(ctx->locked_free_nr) > IO_COMPL_BATCH)
-		io_flush_cached_locked_reqs(ctx, cs);
+		io_flush_cached_locked_reqs(ctx, state);
 
 	nr = state->free_reqs;
-	while (!list_empty(&cs->free_list)) {
-		struct io_kiocb *req = list_first_entry(&cs->free_list,
-						struct io_kiocb, compl.list);
+	while (!list_empty(&state->free_list)) {
+		struct io_kiocb *req = list_first_entry(&state->free_list,
+					struct io_kiocb, inflight_entry);
 
-		list_del(&req->compl.list);
+		list_del(&req->inflight_entry);
 		state->reqs[nr++] = req;
 		if (nr == ARRAY_SIZE(state->reqs))
 			break;
@@ -1733,48 +1873,41 @@ static bool io_flush_cached_reqs(struct io_ring_ctx *ctx)
 	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 (!state->free_reqs) {
-		gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
-		int ret, i;
-
-		if (io_flush_cached_reqs(ctx))
-			goto got_req;
+	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);
+	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;
-		}
-
-		/*
-		 * Don't initialise the fields below on every allocation, but
-		 * do that in advance and keep valid on free.
-		 */
-		for (i = 0; i < ret; i++) {
-			struct io_kiocb *req = state->reqs[i];
-
-			req->ctx = ctx;
-			req->link = NULL;
-			req->async_data = NULL;
-			/* not necessary, but safer to zero */
-			req->result = 0;
-		}
-		state->free_reqs = ret;
+	/*
+	 * 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];
@@ -1802,17 +1935,6 @@ static void io_dismantle_req(struct io_kiocb *req)
 	}
 }
 
-/* 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;
-
-	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_free_req(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
@@ -1820,7 +1942,11 @@ static void __io_free_req(struct io_kiocb *req)
 	io_dismantle_req(req);
 	io_put_task(req->task, 1);
 
-	kmem_cache_free(req_cachep, req);
+	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);
 }
 
@@ -1834,22 +1960,20 @@ static inline void io_remove_next_linked(struct io_kiocb *req)
 
 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;
 
-	/*
-	 * Can happen if a linked timeout fired and link had been like
-	 * req -> link t-out -> link t-out [-> ...]
-	 */
-	if (link && (link->flags & REQ_F_LTIMEOUT_ACTIVE)) {
+	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_cqring_fill_event(link->ctx, link->user_data,
 					     -ECANCELED, 0);
-			io_put_req_deferred(link, 1);
+			io_put_req_deferred(link);
 			return true;
 		}
 	}
@@ -1863,12 +1987,17 @@ static void io_fail_links(struct io_kiocb *req)
 
 	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_cqring_fill_event(link->ctx, link->user_data, -ECANCELED, 0);
-		io_put_req_deferred(link, 2);
+		io_cqring_fill_event(link->ctx, link->user_data, res, 0);
+		io_put_req_deferred(link);
 		link = nxt;
 	}
 }
@@ -1878,8 +2007,24 @@ static bool io_disarm_next(struct io_kiocb *req)
 {
 	bool posted = false;
 
-	if (likely(req->flags & REQ_F_LINK_TIMEOUT))
+	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_cqring_fill_event(link->ctx, link->user_data,
+					     -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);
@@ -1898,16 +2043,15 @@ static struct io_kiocb *__io_req_find_next(struct io_kiocb *req)
 	 * dependencies to the next request. In case of failure, fail the rest
 	 * of the chain.
 	 */
-	if (req->flags & (REQ_F_LINK_TIMEOUT | REQ_F_FAIL)) {
+	if (req->flags & IO_DISARM_MASK) {
 		struct io_ring_ctx *ctx = req->ctx;
-		unsigned long flags;
 		bool posted;
 
-		spin_lock_irqsave(&ctx->completion_lock, flags);
+		spin_lock(&ctx->completion_lock);
 		posted = io_disarm_next(req);
 		if (posted)
 			io_commit_cqring(req->ctx);
-		spin_unlock_irqrestore(&ctx->completion_lock, flags);
+		spin_unlock(&ctx->completion_lock);
 		if (posted)
 			io_cqring_ev_posted(ctx);
 	}
@@ -1923,20 +2067,22 @@ static inline struct io_kiocb *io_req_find_next(struct io_kiocb *req)
 	return __io_req_find_next(req);
 }
 
-static void ctx_flush_and_put(struct io_ring_ctx *ctx)
+static void ctx_flush_and_put(struct io_ring_ctx *ctx, bool *locked)
 {
 	if (!ctx)
 		return;
-	if (ctx->submit_state.comp.nr) {
-		mutex_lock(&ctx->uring_lock);
-		io_submit_flush_completions(ctx);
+	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);
@@ -1947,37 +2093,32 @@ static void tctx_task_work(struct callback_head *cb)
 		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;
 
-		while (node) {
+		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);
+				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);
+			req->io_task_work.func(req, &locked);
 			node = next;
-		}
-		if (wq_list_empty(&tctx->task_list)) {
-			spin_lock_irq(&tctx->task_lock);
-			clear_bit(0, &tctx->task_state);
-			if (wq_list_empty(&tctx->task_list)) {
-				spin_unlock_irq(&tctx->task_lock);
-				break;
-			}
-			spin_unlock_irq(&tctx->task_lock);
-			/* another tctx_task_work() is enqueued, yield */
-			if (test_and_set_bit(0, &tctx->task_state))
-				break;
-		}
+		} while (node);
+
 		cond_resched();
 	}
 
-	ctx_flush_and_put(ctx);
+	ctx_flush_and_put(ctx, &locked);
 }
 
 static void io_req_task_work_add(struct io_kiocb *req)
@@ -1987,19 +2128,20 @@ static void io_req_task_work_add(struct io_kiocb *req)
 	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 (test_bit(0, &tctx->task_state) ||
-	    test_and_set_bit(0, &tctx->task_state))
+	if (running)
 		return;
-	if (unlikely(tsk->flags & PF_EXITING))
-		goto fail;
 
 	/*
 	 * SQPOLL kernel thread doesn't need notification, just a wakeup. For
@@ -2012,9 +2154,9 @@ static void io_req_task_work_add(struct io_kiocb *req)
 		wake_up_process(tsk);
 		return;
 	}
-fail:
-	clear_bit(0, &tctx->task_state);
+
 	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);
@@ -2028,27 +2170,25 @@ fail:
 	}
 }
 
-static void io_req_task_cancel(struct io_kiocb *req)
+static void io_req_task_cancel(struct io_kiocb *req, bool *locked)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 
-	/* ctx is guaranteed to stay alive while we hold uring_lock */
-	mutex_lock(&ctx->uring_lock);
+	/* not needed for normal modes, but SQPOLL depends on it */
+	io_tw_lock(ctx, locked);
 	io_req_complete_failed(req, req->result);
-	mutex_unlock(&ctx->uring_lock);
 }
 
-static void io_req_task_submit(struct io_kiocb *req)
+static void io_req_task_submit(struct io_kiocb *req, bool *locked)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 
-	/* ctx stays valid until unlock, even if we drop all ours ctx->refs */
-	mutex_lock(&ctx->uring_lock);
-	if (!(req->task->flags & PF_EXITING) && !req->task->in_execve)
+	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);
-	mutex_unlock(&ctx->uring_lock);
 }
 
 static void io_req_task_queue_fail(struct io_kiocb *req, int ret)
@@ -2084,6 +2224,11 @@ static void io_free_req(struct io_kiocb *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;
@@ -2100,10 +2245,10 @@ static inline void io_init_req_batch(struct req_batch *rb)
 static void io_req_free_batch_finish(struct io_ring_ctx *ctx,
 				     struct req_batch *rb)
 {
-	if (rb->task)
-		io_put_task(rb->task, rb->task_refs);
 	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,
@@ -2124,37 +2269,37 @@ static void io_req_free_batch(struct req_batch *rb, struct io_kiocb *req,
 	if (state->free_reqs != ARRAY_SIZE(state->reqs))
 		state->reqs[state->free_reqs++] = req;
 	else
-		list_add(&req->compl.list, &state->comp.free_list);
+		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_comp_state *cs = &ctx->submit_state.comp;
-	int i, nr = cs->nr;
+	struct io_submit_state *state = &ctx->submit_state;
+	int i, nr = state->compl_nr;
 	struct req_batch rb;
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	for (i = 0; i < nr; i++) {
-		struct io_kiocb *req = cs->reqs[i];
+		struct io_kiocb *req = state->compl_reqs[i];
 
 		__io_cqring_fill_event(ctx, req->user_data, req->result,
 					req->compl.cflags);
 	}
 	io_commit_cqring(ctx);
-	spin_unlock_irq(&ctx->completion_lock);
+	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 = cs->reqs[i];
+		struct io_kiocb *req = state->compl_reqs[i];
 
-		/* submission and completion refs */
-		if (req_ref_sub_and_test(req, 2))
+		if (req_ref_put_and_test(req))
 			io_req_free_batch(&rb, req, &ctx->submit_state);
 	}
 
 	io_req_free_batch_finish(ctx, &rb);
-	cs->nr = 0;
+	state->compl_nr = 0;
 }
 
 /*
@@ -2178,16 +2323,12 @@ static inline void io_put_req(struct io_kiocb *req)
 		io_free_req(req);
 }
 
-static void io_free_req_deferred(struct io_kiocb *req)
+static inline void io_put_req_deferred(struct io_kiocb *req)
 {
-	req->io_task_work.func = io_free_req;
-	io_req_task_work_add(req);
-}
-
-static inline void io_put_req_deferred(struct io_kiocb *req, int refs)
-{
-	if (req_ref_sub_and_test(req, refs))
-		io_free_req_deferred(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)
@@ -2220,6 +2361,8 @@ 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);
 }
@@ -2239,7 +2382,7 @@ static inline bool io_run_task_work(void)
  * Find and free completed poll iocbs
  */
 static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
-			       struct list_head *done, bool resubmit)
+			       struct list_head *done)
 {
 	struct req_batch rb;
 	struct io_kiocb *req;
@@ -2249,23 +2392,18 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 
 	io_init_req_batch(&rb);
 	while (!list_empty(done)) {
-		int cflags = 0;
-
 		req = list_first_entry(done, struct io_kiocb, inflight_entry);
 		list_del(&req->inflight_entry);
 
-		if (READ_ONCE(req->result) == -EAGAIN && resubmit &&
+		if (READ_ONCE(req->result) == -EAGAIN &&
 		    !(req->flags & REQ_F_DONT_REISSUE)) {
 			req->iopoll_completed = 0;
-			req_ref_get(req);
 			io_req_task_queue_reissue(req);
 			continue;
 		}
 
-		if (req->flags & REQ_F_BUFFER_SELECTED)
-			cflags = io_put_rw_kbuf(req);
-
-		__io_cqring_fill_event(ctx, req->user_data, req->result, cflags);
+		__io_cqring_fill_event(ctx, req->user_data, req->result,
+					io_put_rw_kbuf(req));
 		(*nr_events)++;
 
 		if (req_ref_put_and_test(req))
@@ -2278,12 +2416,11 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 }
 
 static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
-			long min, bool resubmit)
+			long min)
 {
 	struct io_kiocb *req, *tmp;
 	LIST_HEAD(done);
 	bool spin;
-	int ret;
 
 	/*
 	 * Only spin for completions if we don't have multiple devices hanging
@@ -2291,9 +2428,9 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 	 */
 	spin = !ctx->poll_multi_queue && *nr_events < min;
 
-	ret = 0;
 	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.
@@ -2308,22 +2445,20 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 			break;
 
 		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
-		if (ret < 0)
-			break;
+		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 (ret && spin)
-			spin = false;
-		ret = 0;
 	}
 
 	if (!list_empty(&done))
-		io_iopoll_complete(ctx, nr_events, &done, resubmit);
+		io_iopoll_complete(ctx, nr_events, &done);
 
-	return ret;
+	return 0;
 }
 
 /*
@@ -2339,7 +2474,7 @@ static void io_iopoll_try_reap_events(struct io_ring_ctx *ctx)
 	while (!list_empty(&ctx->iopoll_list)) {
 		unsigned int nr_events = 0;
 
-		io_do_iopoll(ctx, &nr_events, 0, false);
+		io_do_iopoll(ctx, &nr_events, 0);
 
 		/* let it sleep and repeat later if can't complete a request */
 		if (nr_events == 0)
@@ -2401,7 +2536,7 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, long min)
 			    list_empty(&ctx->iopoll_list))
 				break;
 		}
-		ret = io_do_iopoll(ctx, &nr_events, min, true);
+		ret = io_do_iopoll(ctx, &nr_events, min);
 	} while (!ret && nr_events < min && !need_resched());
 out:
 	mutex_unlock(&ctx->uring_lock);
@@ -2470,44 +2605,57 @@ static bool io_rw_should_reissue(struct io_kiocb *req)
 }
 #endif
 
-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;
-
-	percpu_ref_get(&ctx->refs);
-	llist_for_each_entry_safe(req, tmp, node, io_task_work.fallback_node)
-		req->io_task_work.func(req);
-	percpu_ref_put(&ctx->refs);
-}
-
-static void __io_complete_rw(struct io_kiocb *req, long res, long res2,
-			     unsigned int issue_flags)
+static bool __io_complete_rw_common(struct io_kiocb *req, long res)
 {
-	int cflags = 0;
-
 	if (req->rw.kiocb.ki_flags & IOCB_WRITE)
 		kiocb_end_write(req);
 	if (res != req->result) {
 		if ((res == -EAGAIN || res == -EOPNOTSUPP) &&
 		    io_rw_should_reissue(req)) {
 			req->flags |= REQ_F_REISSUE;
-			return;
+			return true;
 		}
 		req_set_fail(req);
+		req->result = res;
+	}
+	return false;
+}
+
+static void io_req_task_complete(struct io_kiocb *req, bool *locked)
+{
+	unsigned int cflags = io_put_rw_kbuf(req);
+	long 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);
 	}
-	if (req->flags & REQ_F_BUFFER_SELECTED)
-		cflags = io_put_rw_kbuf(req);
-	__io_req_complete(req, issue_flags, res, cflags);
+}
+
+static void __io_complete_rw(struct io_kiocb *req, long res, long res2,
+			     unsigned int issue_flags)
+{
+	if (__io_complete_rw_common(req, res))
+		return;
+	__io_req_complete(req, 0, req->result, io_put_rw_kbuf(req));
 }
 
 static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
 {
 	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw.kiocb);
 
-	__io_complete_rw(req, res, res2, 0);
+	if (__io_complete_rw_common(req, res))
+		return;
+	req->result = res;
+	req->io_task_work.func = io_req_task_complete;
+	io_req_task_work_add(req);
 }
 
 static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
@@ -2593,40 +2741,6 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
 	}
 }
 
-static inline void io_state_file_put(struct io_submit_state *state)
-{
-	if (state->file_refs) {
-		fput_many(state->file, state->file_refs);
-		state->file_refs = 0;
-	}
-}
-
-/*
- * Get as many references to a file as we have IOs left in this submission,
- * assuming most submissions are for one file, or at least that each file
- * has more than one submission.
- */
-static struct file *__io_file_get(struct io_submit_state *state, int fd)
-{
-	if (!state)
-		return fget(fd);
-
-	if (state->file_refs) {
-		if (state->fd == fd) {
-			state->file_refs--;
-			return state->file;
-		}
-		io_state_file_put(state);
-	}
-	state->file = fget_many(fd, state->ios_left);
-	if (unlikely(!state->file))
-		return NULL;
-
-	state->fd = fd;
-	state->file_refs = state->ios_left - 1;
-	return state->file;
-}
-
 static bool io_bdev_nowait(struct block_device *bdev)
 {
 	return !bdev || blk_queue_nowait(bdev_get_queue(bdev));
@@ -2637,7 +2751,7 @@ static bool io_bdev_nowait(struct block_device *bdev)
  * any file. For now, just ensure that anything potentially problematic is done
  * inline.
  */
-static bool __io_file_supports_async(struct file *file, int rw)
+static bool __io_file_supports_nowait(struct file *file, int rw)
 {
 	umode_t mode = file_inode(file)->i_mode;
 
@@ -2670,14 +2784,14 @@ static bool __io_file_supports_async(struct file *file, int rw)
 	return file->f_op->write_iter != NULL;
 }
 
-static bool io_file_supports_async(struct io_kiocb *req, int rw)
+static bool io_file_supports_nowait(struct io_kiocb *req, int rw)
 {
-	if (rw == READ && (req->flags & REQ_F_ASYNC_READ))
+	if (rw == READ && (req->flags & REQ_F_NOWAIT_READ))
 		return true;
-	else if (rw == WRITE && (req->flags & REQ_F_ASYNC_WRITE))
+	else if (rw == WRITE && (req->flags & REQ_F_NOWAIT_WRITE))
 		return true;
 
-	return __io_file_supports_async(req->file, rw);
+	return __io_file_supports_nowait(req->file, rw);
 }
 
 static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
@@ -2688,7 +2802,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	unsigned ioprio;
 	int ret;
 
-	if (!(req->flags & REQ_F_ISREG) && S_ISREG(file_inode(file)->i_mode))
+	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);
@@ -2788,15 +2902,11 @@ static void kiocb_done(struct kiocb *kiocb, ssize_t ret,
 	if (check_reissue && (req->flags & REQ_F_REISSUE)) {
 		req->flags &= ~REQ_F_REISSUE;
 		if (io_resubmit_prep(req)) {
-			req_ref_get(req);
 			io_req_task_queue_reissue(req);
 		} else {
-			int cflags = 0;
-
 			req_set_fail(req);
-			if (req->flags & REQ_F_BUFFER_SELECTED)
-				cflags = io_put_rw_kbuf(req);
-			__io_req_complete(req, issue_flags, ret, cflags);
+			__io_req_complete(req, issue_flags, ret,
+					  io_put_rw_kbuf(req));
 		}
 	}
 }
@@ -3214,9 +3324,6 @@ static int io_async_buf_func(struct wait_queue_entry *wait, unsigned mode,
 
 	req->rw.kiocb.ki_flags &= ~IOCB_WAITQ;
 	list_del_init(&wait->entry);
-
-	/* submit ref gets dropped, acquire a new one */
-	req_ref_get(req);
 	io_req_task_queue(req);
 	return 1;
 }
@@ -3301,7 +3408,7 @@ static int io_read(struct io_kiocb *req, unsigned int issue_flags)
 		kiocb->ki_flags |= IOCB_NOWAIT;
 
 	/* If the file doesn't support async, just async punt */
-	if (force_nonblock && !io_file_supports_async(req, READ)) {
+	if (force_nonblock && !io_file_supports_nowait(req, READ)) {
 		ret = io_setup_async_rw(req, iovec, inline_vecs, iter, true);
 		return ret ?: -EAGAIN;
 	}
@@ -3406,7 +3513,7 @@ static int io_write(struct io_kiocb *req, unsigned int issue_flags)
 		kiocb->ki_flags |= IOCB_NOWAIT;
 
 	/* If the file doesn't support async, just async punt */
-	if (force_nonblock && !io_file_supports_async(req, WRITE))
+	if (force_nonblock && !io_file_supports_nowait(req, WRITE))
 		goto copy_iov;
 
 	/* file path doesn't support NOWAIT for non-direct_IO */
@@ -3481,7 +3588,7 @@ static int io_renameat_prep(struct io_kiocb *req,
 
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->buf_index)
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
 		return -EINVAL;
 	if (unlikely(req->flags & REQ_F_FIXED_FILE))
 		return -EBADF;
@@ -3532,7 +3639,8 @@ static int io_unlinkat_prep(struct io_kiocb *req,
 
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
+	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;
@@ -3578,8 +3686,8 @@ static int io_shutdown_prep(struct io_kiocb *req,
 #if defined(CONFIG_NET)
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->off || sqe->addr || sqe->rw_flags ||
-	    sqe->buf_index)
+	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);
@@ -3628,7 +3736,7 @@ static int __io_splice_prep(struct io_kiocb *req,
 	if (unlikely(sp->flags & ~valid_flags))
 		return -EINVAL;
 
-	sp->file_in = io_file_get(NULL, req, READ_ONCE(sqe->splice_fd_in),
+	sp->file_in = io_file_get(req->ctx, req, READ_ONCE(sqe->splice_fd_in),
 				  (sp->flags & SPLICE_F_FD_IN_FIXED));
 	if (!sp->file_in)
 		return -EBADF;
@@ -3727,7 +3835,8 @@ static int io_fsync_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
+	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index ||
+		     sqe->splice_fd_in))
 		return -EINVAL;
 
 	req->sync.flags = READ_ONCE(sqe->fsync_flags);
@@ -3760,7 +3869,8 @@ static int io_fsync(struct io_kiocb *req, unsigned int issue_flags)
 static int io_fallocate_prep(struct io_kiocb *req,
 			     const struct io_uring_sqe *sqe)
 {
-	if (sqe->ioprio || sqe->buf_index || sqe->rw_flags)
+	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;
@@ -3791,6 +3901,8 @@ 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))
@@ -3808,6 +3920,11 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 		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;
@@ -3815,12 +3932,9 @@ static int __io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 
 static int io_openat_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
-	u64 flags, mode;
+	u64 mode = READ_ONCE(sqe->len);
+	u64 flags = READ_ONCE(sqe->open_flags);
 
-	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
-		return -EINVAL;
-	mode = READ_ONCE(sqe->len);
-	flags = READ_ONCE(sqe->open_flags);
 	req->open.how = build_open_how(flags, mode);
 	return __io_openat_prep(req, sqe);
 }
@@ -3831,8 +3945,6 @@ static int io_openat2_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	size_t len;
 	int ret;
 
-	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
-		return -EINVAL;
 	how = u64_to_user_ptr(READ_ONCE(sqe->addr2));
 	len = READ_ONCE(sqe->len);
 	if (len < OPEN_HOW_SIZE_VER0)
@@ -3850,8 +3962,8 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
 {
 	struct open_flags op;
 	struct file *file;
-	bool nonblock_set;
-	bool resolve_nonblock;
+	bool resolve_nonblock, nonblock_set;
+	bool fixed = !!req->open.file_slot;
 	int ret;
 
 	ret = build_open_flags(&req->open.how, &op);
@@ -3870,9 +3982,11 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
 		op.open_flag |= O_NONBLOCK;
 	}
 
-	ret = __get_unused_fd_flags(req->open.how.flags, req->open.nofile);
-	if (ret < 0)
-		goto err;
+	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)) {
@@ -3881,7 +3995,8 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
 		 * 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.
 		 */
-		put_unused_fd(ret);
+		if (!fixed)
+			put_unused_fd(ret);
 
 		ret = PTR_ERR(file);
 		/* only retry if RESOLVE_CACHED wasn't already set by application */
@@ -3894,7 +4009,12 @@ static int io_openat2(struct io_kiocb *req, unsigned int issue_flags)
 	if ((issue_flags & IO_URING_F_NONBLOCK) && !nonblock_set)
 		file->f_flags &= ~O_NONBLOCK;
 	fsnotify_open(file);
-	fd_install(ret, 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;
@@ -3915,7 +4035,8 @@ static int io_remove_buffers_prep(struct io_kiocb *req,
 	struct io_provide_buf *p = &req->pbuf;
 	u64 tmp;
 
-	if (sqe->ioprio || sqe->rw_flags || sqe->addr || sqe->len || sqe->off)
+	if (sqe->ioprio || sqe->rw_flags || sqe->addr || sqe->len || sqe->off ||
+	    sqe->splice_fd_in)
 		return -EINVAL;
 
 	tmp = READ_ONCE(sqe->fd);
@@ -3986,7 +4107,7 @@ static int io_provide_buffers_prep(struct io_kiocb *req,
 	struct io_provide_buf *p = &req->pbuf;
 	u64 tmp;
 
-	if (sqe->ioprio || sqe->rw_flags)
+	if (sqe->ioprio || sqe->rw_flags || sqe->splice_fd_in)
 		return -EINVAL;
 
 	tmp = READ_ONCE(sqe->fd);
@@ -4073,7 +4194,7 @@ 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)
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
 		return -EINVAL;
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
@@ -4119,7 +4240,7 @@ static int io_epoll_ctl(struct io_kiocb *req, unsigned int issue_flags)
 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)
+	if (sqe->ioprio || sqe->buf_index || sqe->off || sqe->splice_fd_in)
 		return -EINVAL;
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
@@ -4154,7 +4275,7 @@ static int io_madvise(struct io_kiocb *req, unsigned int issue_flags)
 
 static int io_fadvise_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 {
-	if (sqe->ioprio || sqe->buf_index || sqe->addr)
+	if (sqe->ioprio || sqe->buf_index || sqe->addr || sqe->splice_fd_in)
 		return -EINVAL;
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
@@ -4192,7 +4313,7 @@ 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)
+	if (sqe->ioprio || sqe->buf_index || sqe->splice_fd_in)
 		return -EINVAL;
 	if (req->flags & REQ_F_FIXED_FILE)
 		return -EBADF;
@@ -4228,7 +4349,7 @@ 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)
+	    sqe->rw_flags || sqe->buf_index || sqe->splice_fd_in)
 		return -EINVAL;
 	if (req->flags & REQ_F_FIXED_FILE)
 		return -EBADF;
@@ -4289,7 +4410,8 @@ static int io_sfr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 
 	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
+	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index ||
+		     sqe->splice_fd_in))
 		return -EINVAL;
 
 	req->sync.off = READ_ONCE(sqe->off);
@@ -4723,6 +4845,15 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	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 && ((req->open.how.flags & O_CLOEXEC) ||
+				  (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;
 }
 
@@ -4731,20 +4862,35 @@ 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;
-	int ret;
+	bool fixed = !!accept->file_slot;
+	struct file *file;
+	int ret, fd;
 
 	if (req->file->f_flags & O_NONBLOCK)
 		req->flags |= REQ_F_NOWAIT;
 
-	ret = __sys_accept4_file(req->file, file_flags, accept->addr,
-					accept->addr_len, accept->flags,
-					accept->nofile);
-	if (ret == -EAGAIN && force_nonblock)
-		return -EAGAIN;
-	if (ret < 0) {
+	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);
+		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;
@@ -4764,7 +4910,8 @@ static int io_connect_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->len || sqe->buf_index || sqe->rw_flags)
+	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));
@@ -4877,6 +5024,7 @@ static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 
+	/* req->task == current here, checking PF_EXITING is safe */
 	if (unlikely(req->task->flags & PF_EXITING))
 		WRITE_ONCE(poll->canceled, true);
 
@@ -4886,7 +5034,7 @@ static bool io_poll_rewait(struct io_kiocb *req, struct io_poll_iocb *poll)
 		req->result = vfs_poll(req->file, &pt) & poll->events;
 	}
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	if (!req->result && !READ_ONCE(poll->canceled)) {
 		add_wait_queue(poll->head, &poll->wait);
 		return true;
@@ -4920,12 +5068,12 @@ static void io_poll_remove_double(struct io_kiocb *req)
 	if (poll && poll->head) {
 		struct wait_queue_head *head = poll->head;
 
-		spin_lock(&head->lock);
+		spin_lock_irq(&head->lock);
 		list_del_init(&poll->wait.entry);
 		if (poll->wait.private)
 			req_ref_put(req);
 		poll->head = NULL;
-		spin_unlock(&head->lock);
+		spin_unlock_irq(&head->lock);
 	}
 }
 
@@ -4955,13 +5103,13 @@ static bool io_poll_complete(struct io_kiocb *req, __poll_t mask)
 	return !(flags & IORING_CQE_F_MORE);
 }
 
-static void io_poll_task_func(struct io_kiocb *req)
+static void io_poll_task_func(struct io_kiocb *req, bool *locked)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_kiocb *nxt;
 
 	if (io_poll_rewait(req, &req->poll)) {
-		spin_unlock_irq(&ctx->completion_lock);
+		spin_unlock(&ctx->completion_lock);
 	} else {
 		bool done;
 
@@ -4973,13 +5121,13 @@ static void io_poll_task_func(struct io_kiocb *req)
 			req->result = 0;
 			add_wait_queue(req->poll.head, &req->poll.wait);
 		}
-		spin_unlock_irq(&ctx->completion_lock);
+		spin_unlock(&ctx->completion_lock);
 		io_cqring_ev_posted(ctx);
 
 		if (done) {
 			nxt = io_put_req_find_next(req);
 			if (nxt)
-				io_req_task_submit(nxt);
+				io_req_task_submit(nxt, locked);
 		}
 	}
 }
@@ -4990,6 +5138,7 @@ static int io_poll_double_wake(struct wait_queue_entry *wait, unsigned mode,
 	struct io_kiocb *req = wait->private;
 	struct io_poll_iocb *poll = io_poll_get_single(req);
 	__poll_t mask = key_to_poll(key);
+	unsigned long flags;
 
 	/* for instances that support it check for an event match first: */
 	if (mask && !(mask & poll->events))
@@ -5002,13 +5151,13 @@ static int io_poll_double_wake(struct wait_queue_entry *wait, unsigned mode,
 	if (poll->head) {
 		bool done;
 
-		spin_lock(&poll->head->lock);
+		spin_lock_irqsave(&poll->head->lock, flags);
 		done = list_empty(&poll->wait.entry);
 		if (!done)
 			list_del_init(&poll->wait.entry);
 		/* make sure double remove sees this as being gone */
 		wait->private = NULL;
-		spin_unlock(&poll->head->lock);
+		spin_unlock_irqrestore(&poll->head->lock, flags);
 		if (!done) {
 			/* use wait func handler, so it matches the rq type */
 			poll->wait.func(&poll->wait, mode, sync, key);
@@ -5045,8 +5194,13 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
 	if (unlikely(pt->nr_entries)) {
 		struct io_poll_iocb *poll_one = poll;
 
+		/* double add on the same waitqueue head, ignore */
+		if (poll_one->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;
 		}
@@ -5056,9 +5210,6 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt,
 		 */
 		if (!(poll_one->events & EPOLLONESHOT))
 			poll_one->events |= EPOLLONESHOT;
-		/* double add on the same waitqueue head, ignore */
-		if (poll_one->head == head)
-			return;
 		poll = kmalloc(sizeof(*poll), GFP_ATOMIC);
 		if (!poll) {
 			pt->error = -ENOMEM;
@@ -5088,7 +5239,7 @@ static void io_async_queue_proc(struct file *file, struct wait_queue_head *head,
 	__io_queue_proc(&apoll->poll, pt, head, &apoll->double_poll);
 }
 
-static void io_async_task_func(struct io_kiocb *req)
+static void io_async_task_func(struct io_kiocb *req, bool *locked)
 {
 	struct async_poll *apoll = req->apoll;
 	struct io_ring_ctx *ctx = req->ctx;
@@ -5096,16 +5247,16 @@ static void io_async_task_func(struct io_kiocb *req)
 	trace_io_uring_task_run(req->ctx, req, req->opcode, req->user_data);
 
 	if (io_poll_rewait(req, &apoll->poll)) {
-		spin_unlock_irq(&ctx->completion_lock);
+		spin_unlock(&ctx->completion_lock);
 		return;
 	}
 
 	hash_del(&req->hash_node);
 	io_poll_remove_double(req);
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 
 	if (!READ_ONCE(apoll->poll.canceled))
-		io_req_task_submit(req);
+		io_req_task_submit(req, locked);
 	else
 		io_req_complete_failed(req, -ECANCELED);
 }
@@ -5154,11 +5305,11 @@ static __poll_t __io_arm_poll_handler(struct io_kiocb *req,
 	if (unlikely(!ipt->nr_entries) && !ipt->error)
 		ipt->error = -EINVAL;
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	if (ipt->error || (mask && (poll->events & EPOLLONESHOT)))
 		io_poll_remove_double(req);
 	if (likely(poll->head)) {
-		spin_lock(&poll->head->lock);
+		spin_lock_irq(&poll->head->lock);
 		if (unlikely(list_empty(&poll->wait.entry))) {
 			if (ipt->error)
 				cancel = true;
@@ -5171,7 +5322,7 @@ static __poll_t __io_arm_poll_handler(struct io_kiocb *req,
 			WRITE_ONCE(poll->canceled, true);
 		else if (!poll->done) /* actually waiting for an event */
 			io_poll_req_insert(req);
-		spin_unlock(&poll->head->lock);
+		spin_unlock_irq(&poll->head->lock);
 	}
 
 	return mask;
@@ -5213,7 +5364,7 @@ static int io_arm_poll_handler(struct io_kiocb *req)
 	}
 
 	/* if we can't nonblock try, then no point in arming a poll handler */
-	if (!io_file_supports_async(req, rw))
+	if (!io_file_supports_nowait(req, rw))
 		return IO_APOLL_ABORTED;
 
 	apoll = kmalloc(sizeof(*apoll), GFP_ATOMIC);
@@ -5223,16 +5374,14 @@ static int io_arm_poll_handler(struct io_kiocb *req)
 	req->apoll = apoll;
 	req->flags |= REQ_F_POLLED;
 	ipt.pt._qproc = io_async_queue_proc;
+	io_req_set_refcount(req);
 
 	ret = __io_arm_poll_handler(req, &apoll->poll, &ipt, mask,
 					io_async_wake);
-	if (ret || ipt.error) {
-		spin_unlock_irq(&ctx->completion_lock);
-		if (ret)
-			return IO_APOLL_READY;
-		return IO_APOLL_ABORTED;
-	}
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
+	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;
@@ -5246,19 +5395,19 @@ static bool __io_poll_remove_one(struct io_kiocb *req,
 
 	if (!poll->head)
 		return false;
-	spin_lock(&poll->head->lock);
+	spin_lock_irq(&poll->head->lock);
 	if (do_cancel)
 		WRITE_ONCE(poll->canceled, true);
 	if (!list_empty(&poll->wait.entry)) {
 		list_del_init(&poll->wait.entry);
 		do_complete = true;
 	}
-	spin_unlock(&poll->head->lock);
+	spin_unlock_irq(&poll->head->lock);
 	hash_del(&req->hash_node);
 	return do_complete;
 }
 
-static bool io_poll_remove_waitqs(struct io_kiocb *req)
+static bool io_poll_remove_one(struct io_kiocb *req)
 	__must_hold(&req->ctx->completion_lock)
 {
 	bool do_complete;
@@ -5266,26 +5415,12 @@ static bool io_poll_remove_waitqs(struct io_kiocb *req)
 	io_poll_remove_double(req);
 	do_complete = __io_poll_remove_one(req, io_poll_get_single(req), true);
 
-	if (req->opcode != IORING_OP_POLL_ADD && do_complete) {
-		/* non-poll requests have submit ref still */
-		req_ref_put(req);
-	}
-	return do_complete;
-}
-
-static bool io_poll_remove_one(struct io_kiocb *req)
-	__must_hold(&req->ctx->completion_lock)
-{
-	bool do_complete;
-
-	do_complete = io_poll_remove_waitqs(req);
 	if (do_complete) {
 		io_cqring_fill_event(req->ctx, req->user_data, -ECANCELED, 0);
 		io_commit_cqring(req->ctx);
 		req_set_fail(req);
-		io_put_req_deferred(req, 1);
+		io_put_req_deferred(req);
 	}
-
 	return do_complete;
 }
 
@@ -5299,7 +5434,7 @@ static bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 	struct io_kiocb *req;
 	int posted = 0, i;
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
 		struct hlist_head *list;
 
@@ -5309,7 +5444,7 @@ static bool io_poll_remove_all(struct io_ring_ctx *ctx, struct task_struct *tsk,
 				posted += io_poll_remove_one(req);
 		}
 	}
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 
 	if (posted)
 		io_cqring_ev_posted(ctx);
@@ -5372,7 +5507,7 @@ static int io_poll_update_prep(struct io_kiocb *req,
 
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->buf_index)
+	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 |
@@ -5427,6 +5562,7 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe
 	if (flags & ~IORING_POLL_ADD_MULTI)
 		return -EINVAL;
 
+	io_req_set_refcount(req);
 	poll->events = io_poll_parse_events(sqe, flags);
 	return 0;
 }
@@ -5447,7 +5583,7 @@ static int io_poll_add(struct io_kiocb *req, unsigned int issue_flags)
 		ipt.error = 0;
 		io_poll_complete(req, mask);
 	}
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 
 	if (mask) {
 		io_cqring_ev_posted(ctx);
@@ -5464,7 +5600,7 @@ static int io_poll_update(struct io_kiocb *req, unsigned int issue_flags)
 	bool completing;
 	int ret;
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	preq = io_poll_find(ctx, req->poll_update.old_user_data, true);
 	if (!preq) {
 		ret = -ENOENT;
@@ -5491,7 +5627,7 @@ static int io_poll_update(struct io_kiocb *req, unsigned int issue_flags)
 	ret = 0;
 err:
 	if (ret < 0) {
-		spin_unlock_irq(&ctx->completion_lock);
+		spin_unlock(&ctx->completion_lock);
 		req_set_fail(req);
 		io_req_complete(req, ret);
 		return 0;
@@ -5504,7 +5640,7 @@ err:
 	}
 	if (req->poll_update.update_user_data)
 		preq->user_data = req->poll_update.new_user_data;
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 
 	/* complete update request, we're done with it */
 	io_req_complete(req, ret);
@@ -5519,6 +5655,12 @@ err:
 	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,
@@ -5527,24 +5669,20 @@ static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
 	struct io_ring_ctx *ctx = req->ctx;
 	unsigned long flags;
 
-	spin_lock_irqsave(&ctx->completion_lock, 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);
 
-	io_cqring_fill_event(ctx, req->user_data, -ETIME, 0);
-	io_commit_cqring(ctx);
-	spin_unlock_irqrestore(&ctx->completion_lock, flags);
-
-	io_cqring_ev_posted(ctx);
-	req_set_fail(req);
-	io_put_req(req);
+	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->completion_lock)
+	__must_hold(&ctx->timeout_lock)
 {
 	struct io_timeout_data *io;
 	struct io_kiocb *req;
@@ -5567,6 +5705,7 @@ static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
 
 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);
 
@@ -5575,13 +5714,54 @@ static int io_timeout_cancel(struct io_ring_ctx *ctx, __u64 user_data)
 
 	req_set_fail(req);
 	io_cqring_fill_event(ctx, req->user_data, -ECANCELED, 0);
-	io_put_req_deferred(req, 1);
+	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->completion_lock)
+	__must_hold(&ctx->timeout_lock)
 {
 	struct io_kiocb *req = io_timeout_extract(ctx, user_data);
 	struct io_timeout_data *data;
@@ -5592,7 +5772,7 @@ static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
 	req->timeout.off = 0; /* noseq */
 	data = req->async_data;
 	list_add_tail(&req->timeout.list, &ctx->timeout_list);
-	hrtimer_init(&data->timer, CLOCK_MONOTONIC, mode);
+	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;
@@ -5607,13 +5787,18 @@ static int io_timeout_remove_prep(struct io_kiocb *req,
 		return -EINVAL;
 	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->buf_index || sqe->len)
+	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) {
-		if (tr->flags & ~(IORING_TIMEOUT_UPDATE|IORING_TIMEOUT_ABS))
+	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;
@@ -5640,20 +5825,26 @@ static int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
 	struct io_ring_ctx *ctx = req->ctx;
 	int ret;
 
-	spin_lock_irq(&ctx->completion_lock);
-	if (!(req->timeout_rem.flags & IORING_TIMEOUT_UPDATE))
+	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);
-	else
-		ret = io_timeout_update(ctx, tr->addr, &tr->ts,
-					io_translate_timeout_mode(tr->flags));
+		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);
+	}
 
-	io_cqring_fill_event(ctx, req->user_data, ret, 0);
-	io_commit_cqring(ctx);
-	spin_unlock_irq(&ctx->completion_lock);
-	io_cqring_ev_posted(ctx);
 	if (ret < 0)
 		req_set_fail(req);
-	io_put_req(req);
+	io_req_complete_post(req, ret, 0);
 	return 0;
 }
 
@@ -5666,14 +5857,19 @@ static int io_timeout_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->len != 1)
+	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)
+	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;
@@ -5683,14 +5879,24 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
 	data = req->async_data;
 	data->req = req;
+	data->flags = flags;
 
 	if (get_timespec64(&data->ts, u64_to_user_ptr(sqe->addr)))
 		return -EFAULT;
 
 	data->mode = io_translate_timeout_mode(flags);
-	hrtimer_init(&data->timer, CLOCK_MONOTONIC, data->mode);
-	if (is_timeout_link)
-		io_req_track_inflight(req);
+	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;
 }
 
@@ -5701,7 +5907,7 @@ static int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
 	struct list_head *entry;
 	u32 tail, off = req->timeout.off;
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock_irq(&ctx->timeout_lock);
 
 	/*
 	 * sqe->off holds how many events that need to occur for this
@@ -5740,7 +5946,7 @@ 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->completion_lock);
+	spin_unlock_irq(&ctx->timeout_lock);
 	return 0;
 }
 
@@ -5783,31 +5989,27 @@ static int io_async_cancel_one(struct io_uring_task *tctx, u64 user_data,
 	return ret;
 }
 
-static void io_async_find_and_cancel(struct io_ring_ctx *ctx,
-				     struct io_kiocb *req, __u64 sqe_addr,
-				     int success_ret)
+static int io_try_cancel_userdata(struct io_kiocb *req, u64 sqe_addr)
 {
-	unsigned long flags;
+	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);
-	spin_lock_irqsave(&ctx->completion_lock, flags);
 	if (ret != -ENOENT)
-		goto done;
+		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 done;
+		goto out;
 	ret = io_poll_cancel(ctx, sqe_addr, false);
-done:
-	if (!ret)
-		ret = success_ret;
-	io_cqring_fill_event(ctx, req->user_data, ret, 0);
-	io_commit_cqring(ctx);
-	spin_unlock_irqrestore(&ctx->completion_lock, flags);
-	io_cqring_ev_posted(ctx);
-
-	if (ret < 0)
-		req_set_fail(req);
+out:
+	spin_unlock(&ctx->completion_lock);
+	return ret;
 }
 
 static int io_async_cancel_prep(struct io_kiocb *req,
@@ -5817,7 +6019,8 @@ static int io_async_cancel_prep(struct io_kiocb *req,
 		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)
+	if (sqe->ioprio || sqe->off || sqe->len || sqe->cancel_flags ||
+	    sqe->splice_fd_in)
 		return -EINVAL;
 
 	req->cancel.addr = READ_ONCE(sqe->addr);
@@ -5831,18 +6034,9 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
 	struct io_tctx_node *node;
 	int ret;
 
-	/* tasks should wait for their io-wq threads, so safe w/o sync */
-	ret = io_async_cancel_one(req->task->io_uring, sqe_addr, ctx);
-	spin_lock_irq(&ctx->completion_lock);
-	if (ret != -ENOENT)
-		goto done;
-	ret = io_timeout_cancel(ctx, sqe_addr);
+	ret = io_try_cancel_userdata(req, sqe_addr);
 	if (ret != -ENOENT)
 		goto done;
-	ret = io_poll_cancel(ctx, sqe_addr, false);
-	if (ret != -ENOENT)
-		goto done;
-	spin_unlock_irq(&ctx->completion_lock);
 
 	/* slow path, try all io-wq's */
 	io_ring_submit_lock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
@@ -5855,17 +6049,10 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
 			break;
 	}
 	io_ring_submit_unlock(ctx, !(issue_flags & IO_URING_F_NONBLOCK));
-
-	spin_lock_irq(&ctx->completion_lock);
 done:
-	io_cqring_fill_event(ctx, req->user_data, ret, 0);
-	io_commit_cqring(ctx);
-	spin_unlock_irq(&ctx->completion_lock);
-	io_cqring_ev_posted(ctx);
-
 	if (ret < 0)
 		req_set_fail(req);
-	io_put_req(req);
+	io_req_complete_post(req, ret, 0);
 	return 0;
 }
 
@@ -5874,7 +6061,7 @@ static int io_rsrc_update_prep(struct io_kiocb *req,
 {
 	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
 		return -EINVAL;
-	if (sqe->ioprio || sqe->rw_flags)
+	if (sqe->ioprio || sqe->rw_flags || sqe->splice_fd_in)
 		return -EINVAL;
 
 	req->rsrc_update.offset = READ_ONCE(sqe->off);
@@ -6076,11 +6263,11 @@ fail:
 		return true;
 	}
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	if (!req_need_defer(req, seq) && list_empty(&ctx->defer_list)) {
-		spin_unlock_irq(&ctx->completion_lock);
+		spin_unlock(&ctx->completion_lock);
 		kfree(de);
-		io_queue_async_work(req);
+		io_queue_async_work(req, NULL);
 		return true;
 	}
 
@@ -6088,7 +6275,7 @@ fail:
 	de->req = req;
 	de->seq = seq;
 	list_add_tail(&de->list, &ctx->defer_list);
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 	return true;
 }
 
@@ -6289,16 +6476,31 @@ static int io_issue_sqe(struct io_kiocb *req, unsigned int issue_flags)
 	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;
 
@@ -6317,29 +6519,14 @@ static void io_wq_submit_work(struct io_wq_work *work)
 	}
 
 	/* avoid locking problems by failing it from a clean context */
-	if (ret) {
-		/* io-wq is going to take one down */
-		req_ref_get(req);
+	if (ret)
 		io_req_task_queue_fail(req, ret);
-	}
 }
 
-#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 struct io_fixed_file *io_fixed_file_slot(struct io_file_table *table,
-						      unsigned i)
+						       unsigned i)
 {
-	struct io_fixed_file *table_l2;
-
-	table_l2 = table->files[i >> IORING_FILE_TABLE_SHIFT];
-	return &table_l2[i & IORING_FILE_TABLE_MASK];
+	return &table->files[i];
 }
 
 static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
@@ -6354,45 +6541,69 @@ 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_async(file, READ))
+	if (__io_file_supports_nowait(file, READ))
 		file_ptr |= FFS_ASYNC_READ;
-	if (__io_file_supports_async(file, WRITE))
+	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 struct file *io_file_get(struct io_submit_state *state,
-				struct io_kiocb *req, int fd, bool fixed)
+static inline struct file *io_file_get_fixed(struct io_ring_ctx *ctx,
+					     struct io_kiocb *req, int fd)
 {
-	struct io_ring_ctx *ctx = req->ctx;
 	struct file *file;
+	unsigned long file_ptr;
 
-	if (fixed) {
-		unsigned long file_ptr;
+	if (unlikely((unsigned int)fd >= ctx->nr_user_files))
+		return NULL;
+	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);
+	return file;
+}
 
-		if (unlikely((unsigned int)fd >= ctx->nr_user_files))
-			return NULL;
-		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_ASYNC_READ_BIT);
-		io_req_set_rsrc_node(req);
-	} else {
-		trace_io_uring_file_get(ctx, fd);
-		file = __io_file_get(state, fd);
+static struct file *io_file_get_normal(struct io_ring_ctx *ctx,
+				       struct io_kiocb *req, int fd)
+{
+	struct file *file = fget(fd);
 
-		/* we don't allow fixed io_uring files */
-		if (file && unlikely(file->f_op == &io_uring_fops))
-			io_req_track_inflight(req);
-	}
+	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)
+{
+	if (fixed)
+		return io_file_get_fixed(ctx, req, fd);
+	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;
+
+	if (prev) {
+		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,
@@ -6401,7 +6612,7 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
 	struct io_ring_ctx *ctx = req->ctx;
 	unsigned long flags;
 
-	spin_lock_irqsave(&ctx->completion_lock, flags);
+	spin_lock_irqsave(&ctx->timeout_lock, flags);
 	prev = req->timeout.head;
 	req->timeout.head = NULL;
 
@@ -6414,15 +6625,12 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
 		if (!req_ref_inc_not_zero(prev))
 			prev = NULL;
 	}
-	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+	list_del(&req->timeout.list);
+	req->timeout.prev = prev;
+	spin_unlock_irqrestore(&ctx->timeout_lock, flags);
 
-	if (prev) {
-		io_async_find_and_cancel(ctx, req, prev->user_data, -ETIME);
-		io_put_req_deferred(prev, 1);
-		io_put_req_deferred(req, 1);
-	} else {
-		io_req_complete_post(req, -ETIME, 0);
-	}
+	req->io_task_work.func = io_req_task_link_timeout;
+	io_req_task_work_add(req);
 	return HRTIMER_NORESTART;
 }
 
@@ -6430,7 +6638,7 @@ static void io_queue_linked_timeout(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 
-	spin_lock_irq(&ctx->completion_lock);
+	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
@@ -6441,29 +6649,17 @@ static void io_queue_linked_timeout(struct io_kiocb *req)
 		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->completion_lock);
+	spin_unlock_irq(&ctx->timeout_lock);
 	/* drop submission reference */
 	io_put_req(req);
 }
 
-static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
-{
-	struct io_kiocb *nxt = req->link;
-
-	if (!nxt || (req->flags & REQ_F_LINK_TIMEOUT) ||
-	    nxt->opcode != IORING_OP_LINK_TIMEOUT)
-		return NULL;
-
-	nxt->timeout.head = req;
-	nxt->flags |= REQ_F_LTIMEOUT_ACTIVE;
-	req->flags |= REQ_F_LINK_TIMEOUT;
-	return nxt;
-}
-
 static void __io_queue_sqe(struct io_kiocb *req)
+	__must_hold(&req->ctx->uring_lock)
 {
-	struct io_kiocb *linked_timeout = io_prep_linked_timeout(req);
+	struct io_kiocb *linked_timeout;
 	int ret;
 
 issue_sqe:
@@ -6474,50 +6670,60 @@ issue_sqe:
 	 * doesn't support non-blocking read/write attempts
 	 */
 	if (likely(!ret)) {
-		/* drop submission reference */
 		if (req->flags & REQ_F_COMPLETE_INLINE) {
 			struct io_ring_ctx *ctx = req->ctx;
-			struct io_comp_state *cs = &ctx->submit_state.comp;
+			struct io_submit_state *state = &ctx->submit_state;
 
-			cs->reqs[cs->nr++] = req;
-			if (cs->nr == ARRAY_SIZE(cs->reqs))
+			state->compl_reqs[state->compl_nr++] = req;
+			if (state->compl_nr == ARRAY_SIZE(state->compl_reqs))
 				io_submit_flush_completions(ctx);
-		} else {
-			io_put_req(req);
+			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_unprep_linked_timeout(req);
 			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);
+			io_queue_async_work(req, NULL);
 			break;
 		}
+
+		if (linked_timeout)
+			io_queue_linked_timeout(linked_timeout);
 	} else {
 		io_req_complete_failed(req, ret);
 	}
-	if (linked_timeout)
-		io_queue_linked_timeout(linked_timeout);
 }
 
 static inline void io_queue_sqe(struct io_kiocb *req)
+	__must_hold(&req->ctx->uring_lock)
 {
 	if (unlikely(req->ctx->drain_active) && io_drain_req(req))
 		return;
 
-	if (likely(!(req->flags & REQ_F_FORCE_ASYNC))) {
+	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_failed(req, req->result);
 	} else {
 		int ret = io_req_prep_async(req);
 
 		if (unlikely(ret))
 			io_req_complete_failed(req, ret);
 		else
-			io_queue_async_work(req);
+			io_queue_async_work(req, NULL);
 	}
 }
 
@@ -6549,19 +6755,19 @@ static inline bool io_check_restriction(struct io_ring_ctx *ctx,
 
 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;
-	/* one is dropped after submission, the other at completion */
-	atomic_set(&req->refs, 2);
 	req->task = current;
 
 	/* enforce forwards compatibility on users */
@@ -6599,9 +6805,8 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	}
 
 	if (io_op_defs[req->opcode].needs_file) {
-		bool fixed = req->flags & REQ_F_FIXED_FILE;
-
-		req->file = io_file_get(state, req, READ_ONCE(sqe->fd), fixed);
+		req->file = io_file_get(ctx, req, READ_ONCE(sqe->fd),
+					(sqe_flags & IOSQE_FIXED_FILE));
 		if (unlikely(!req->file))
 			ret = -EBADF;
 	}
@@ -6612,6 +6817,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 
 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;
@@ -6619,20 +6825,34 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	ret = io_init_req(ctx, req, sqe);
 	if (unlikely(ret)) {
 fail_req:
+		/* fail even hard links since we don't submit */
 		if (link->head) {
-			/* fail even hard links since we don't submit */
-			req_set_fail(link->head);
-			io_req_complete_failed(link->head, -ECANCELED);
-			link->head = NULL;
+			/*
+			 * 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;
 		}
-		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;
 	}
 
-	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,
@@ -6648,9 +6868,14 @@ fail_req:
 	if (link->head) {
 		struct io_kiocb *head = link->head;
 
-		ret = io_req_prep_async(req);
-		if (unlikely(ret))
-			goto fail_req;
+		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;
@@ -6680,11 +6905,10 @@ static void io_submit_state_end(struct io_submit_state *state,
 {
 	if (state->link.head)
 		io_queue_sqe(state->link.head);
-	if (state->comp.nr)
+	if (state->compl_nr)
 		io_submit_flush_completions(ctx);
 	if (state->plug_started)
 		blk_finish_plug(&state->plug);
-	io_state_file_put(state);
 }
 
 /*
@@ -6744,26 +6968,17 @@ static const struct io_uring_sqe *io_get_sqe(struct io_ring_ctx *ctx)
 }
 
 static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
+	__must_hold(&ctx->uring_lock)
 {
-	struct io_uring_task *tctx;
 	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);
 
-	tctx = current->io_uring;
-	tctx->cached_refs -= nr;
-	if (unlikely(tctx->cached_refs < 0)) {
-		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;
-	}
 	io_submit_state_start(&ctx->submit_state, nr);
-
 	while (submitted < nr) {
 		const struct io_uring_sqe *sqe;
 		struct io_kiocb *req;
@@ -6776,7 +6991,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
 		}
 		sqe = io_get_sqe(ctx);
 		if (unlikely(!sqe)) {
-			kmem_cache_free(req_cachep, req);
+			list_add(&req->inflight_entry, &ctx->submit_state.free_list);
 			break;
 		}
 		/* will complete beyond this point, count as submitted */
@@ -6808,18 +7023,18 @@ static inline bool io_sqd_events_pending(struct io_sq_data *sqd)
 static inline void io_ring_set_wakeup_flag(struct io_ring_ctx *ctx)
 {
 	/* Tell userspace we may need a wakeup call */
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	WRITE_ONCE(ctx->rings->sq_flags,
 		   ctx->rings->sq_flags | IORING_SQ_NEED_WAKEUP);
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 }
 
 static inline void io_ring_clear_wakeup_flag(struct io_ring_ctx *ctx)
 {
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	WRITE_ONCE(ctx->rings->sq_flags,
 		   ctx->rings->sq_flags & ~IORING_SQ_NEED_WAKEUP);
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 }
 
 static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
@@ -6841,7 +7056,7 @@ static int __io_sq_thread(struct io_ring_ctx *ctx, bool cap_entries)
 
 		mutex_lock(&ctx->uring_lock);
 		if (!list_empty(&ctx->iopoll_list))
-			io_do_iopoll(ctx, &nr_events, 0, true);
+			io_do_iopoll(ctx, &nr_events, 0);
 
 		/*
 		 * Don't submit if refs are dying, good for io_uring_register(),
@@ -6976,21 +7191,21 @@ static int io_sq_thread(void *data)
 struct io_wait_queue {
 	struct wait_queue_entry wq;
 	struct io_ring_ctx *ctx;
-	unsigned to_wait;
+	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 io_cqring_events(ctx) >= iowq->to_wait ||
-			atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
+	return dist >= 0 || atomic_read(&ctx->cq_timeouts) != iowq->nr_timeouts;
 }
 
 static int io_wake_function(struct wait_queue_entry *curr, unsigned int mode,
@@ -7046,21 +7261,13 @@ 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 = {
-		.wq = {
-			.private	= current,
-			.func		= io_wake_function,
-			.entry		= LIST_HEAD_INIT(iowq.wq.entry),
-		},
-		.ctx		= ctx,
-		.to_wait	= min_events,
-	};
+	struct io_wait_queue iowq;
 	struct io_rings *rings = ctx->rings;
 	signed long timeout = MAX_SCHEDULE_TIMEOUT;
 	int ret;
 
 	do {
-		io_cqring_overflow_flush(ctx, false);
+		io_cqring_overflow_flush(ctx);
 		if (io_cqring_events(ctx) >= min_events)
 			return 0;
 		if (!io_run_task_work())
@@ -7088,11 +7295,17 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 		timeout = timespec64_to_jiffies(&ts);
 	}
 
+	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, false)) {
+		if (!io_cqring_overflow_flush(ctx)) {
 			ret = -EBUSY;
 			break;
 		}
@@ -7123,14 +7336,14 @@ static void **io_alloc_page_table(size_t size)
 	size_t init_size = size;
 	void **table;
 
-	table = kcalloc(nr_tables, sizeof(*table), GFP_KERNEL);
+	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);
+		table[i] = kzalloc(this_size, GFP_KERNEL_ACCOUNT);
 		if (!table[i]) {
 			io_free_page_table(table, init_size);
 			return NULL;
@@ -7146,6 +7359,50 @@ static void io_rsrc_node_destroy(struct io_rsrc_node *ref_node)
 	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;
+
+	spin_lock_irqsave(&ctx->rsrc_ref_lock, flags);
+	node->done = true;
+
+	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, HZ);
+}
+
+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)
 {
@@ -7277,17 +7534,14 @@ fail:
 
 static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
 {
-	size_t size = nr_files * sizeof(struct io_fixed_file);
-
-	table->files = (struct io_fixed_file **)io_alloc_page_table(size);
+	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, unsigned nr_files)
+static void io_free_file_tables(struct io_file_table *table)
 {
-	size_t size = nr_files * sizeof(struct io_fixed_file);
-
-	io_free_page_table((void **)table->files, size);
+	kvfree(table->files);
 	table->files = NULL;
 }
 
@@ -7312,7 +7566,7 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
 			fput(file);
 	}
 #endif
-	io_free_file_tables(&ctx->file_table, ctx->nr_user_files);
+	io_free_file_tables(&ctx->file_table);
 	io_rsrc_data_free(ctx->file_data);
 	ctx->file_data = NULL;
 	ctx->nr_user_files = 0;
@@ -7628,11 +7882,11 @@ static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
 			bool lock_ring = ctx->flags & IORING_SETUP_IOPOLL;
 
 			io_ring_submit_lock(ctx, lock_ring);
-			spin_lock_irq(&ctx->completion_lock);
+			spin_lock(&ctx->completion_lock);
 			io_cqring_fill_event(ctx, prsrc->tag, 0, 0);
 			ctx->cq_extra++;
 			io_commit_cqring(ctx);
-			spin_unlock_irq(&ctx->completion_lock);
+			spin_unlock(&ctx->completion_lock);
 			io_cqring_ev_posted(ctx);
 			io_ring_submit_unlock(ctx, lock_ring);
 		}
@@ -7664,50 +7918,6 @@ static void io_rsrc_put_work(struct work_struct *work)
 	}
 }
 
-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;
-
-	spin_lock_irqsave(&ctx->rsrc_ref_lock, flags);
-	node->done = true;
-
-	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, HZ);
-}
-
-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 int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 				 unsigned nr_args, u64 __user *tags)
 {
@@ -7722,6 +7932,8 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 		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;
@@ -7780,7 +7992,7 @@ out_fput:
 		if (file)
 			fput(file);
 	}
-	io_free_file_tables(&ctx->file_table, nr_args);
+	io_free_file_tables(&ctx->file_table);
 	ctx->nr_user_files = 0;
 out_free:
 	io_rsrc_data_free(ctx->file_data);
@@ -7831,6 +8043,46 @@ static int io_sqe_file_register(struct io_ring_ctx *ctx, struct file *file,
 #endif
 }
 
+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;
+	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);
+	ret = -EBADF;
+	if (file_slot->file_ptr)
+		goto err;
+
+	*io_get_tag_slot(ctx->file_data, slot_index) = 0;
+	io_fixed_file_set(file_slot, file);
+	ret = io_sqe_file_register(ctx, file, slot_index);
+	if (ret) {
+		file_slot->file_ptr = 0;
+		goto err;
+	}
+
+	ret = 0;
+err:
+	io_ring_submit_unlock(ctx, !force_nonblock);
+	if (ret)
+		fput(file);
+	return ret;
+}
+
 static int io_queue_rsrc_removal(struct io_rsrc_data *data, unsigned idx,
 				 struct io_rsrc_node *node, void *rsrc)
 {
@@ -7926,14 +8178,6 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 	return done ? done : err;
 }
 
-static struct io_wq_work *io_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 struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
 					struct task_struct *task)
 {
@@ -7957,7 +8201,7 @@ static struct io_wq *io_init_wq_offload(struct io_ring_ctx *ctx,
 
 	data.hash = hash;
 	data.task = task;
-	data.free_work = io_free_work;
+	data.free_work = io_wq_free_work;
 	data.do_work = io_wq_submit_work;
 
 	/* Do QD, or 4 * CPUS, whatever is smallest */
@@ -8624,33 +8868,29 @@ static void io_destroy_buffers(struct io_ring_ctx *ctx)
 		__io_remove_buffers(ctx, buf, index, -1U);
 }
 
-static void io_req_cache_free(struct list_head *list, struct task_struct *tsk)
+static void io_req_cache_free(struct list_head *list)
 {
 	struct io_kiocb *req, *nxt;
 
-	list_for_each_entry_safe(req, nxt, list, compl.list) {
-		if (tsk && req->task != tsk)
-			continue;
-		list_del(&req->compl.list);
+	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 *submit_state = &ctx->submit_state;
-	struct io_comp_state *cs = &ctx->submit_state.comp;
+	struct io_submit_state *state = &ctx->submit_state;
 
 	mutex_lock(&ctx->uring_lock);
 
-	if (submit_state->free_reqs) {
-		kmem_cache_free_bulk(req_cachep, submit_state->free_reqs,
-				     submit_state->reqs);
-		submit_state->free_reqs = 0;
+	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, cs);
-	io_req_cache_free(&cs->free_list, NULL);
+	io_flush_cached_locked_reqs(ctx, state);
+	io_req_cache_free(&state->free_list);
 	mutex_unlock(&ctx->uring_lock);
 }
 
@@ -8702,6 +8942,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 		sock_release(ctx->ring_sock);
 	}
 #endif
+	WARN_ON_ONCE(!list_empty(&ctx->ltimeout_list));
 
 	io_mem_free(ctx->rings);
 	io_mem_free(ctx->sq_sqes);
@@ -8801,6 +9042,7 @@ 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;
@@ -8825,8 +9067,11 @@ static void io_ring_exit_work(struct work_struct *work)
 			io_sq_thread_unpark(sqd);
 		}
 
-		WARN_ON_ONCE(time_after(jiffies, timeout));
-	} while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20));
+		if (WARN_ON_ONCE(time_after(jiffies, timeout))) {
+			/* there is little hope left, don't run it too often */
+			interval = HZ * 60;
+		}
+	} while (!wait_for_completion_timeout(&ctx->ref_comp, interval));
 
 	init_completion(&exit.completion);
 	init_task_work(&exit.task_work, io_tctx_exit_cb);
@@ -8855,8 +9100,8 @@ static void io_ring_exit_work(struct work_struct *work)
 		mutex_lock(&ctx->uring_lock);
 	}
 	mutex_unlock(&ctx->uring_lock);
-	spin_lock_irq(&ctx->completion_lock);
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 
 	io_ring_ctx_free(ctx);
 }
@@ -8868,16 +9113,18 @@ static bool io_kill_timeouts(struct io_ring_ctx *ctx, struct task_struct *tsk,
 	struct io_kiocb *req, *tmp;
 	int canceled = 0;
 
-	spin_lock_irq(&ctx->completion_lock);
+	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_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 	if (canceled != 0)
 		io_cqring_ev_posted(ctx);
 	return canceled != 0;
@@ -8933,13 +9180,12 @@ static bool io_cancel_task_cb(struct io_wq_work *work, void *data)
 	bool ret;
 
 	if (!cancel->all && (req->flags & REQ_F_LINK_TIMEOUT)) {
-		unsigned long flags;
 		struct io_ring_ctx *ctx = req->ctx;
 
 		/* protect against races with linked timeouts */
-		spin_lock_irqsave(&ctx->completion_lock, flags);
+		spin_lock(&ctx->completion_lock);
 		ret = io_match_task(req, cancel->task, cancel->all);
-		spin_unlock_irqrestore(&ctx->completion_lock, flags);
+		spin_unlock(&ctx->completion_lock);
 	} else {
 		ret = io_match_task(req, cancel->task, cancel->all);
 	}
@@ -8952,14 +9198,14 @@ static bool io_cancel_defer_files(struct io_ring_ctx *ctx,
 	struct io_defer_entry *de;
 	LIST_HEAD(list);
 
-	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&ctx->completion_lock);
 	list_for_each_entry_reverse(de, &ctx->defer_list, list) {
 		if (io_match_task(de->req, task, cancel_all)) {
 			list_cut_position(&list, &ctx->defer_list, &de->list);
 			break;
 		}
 	}
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 	if (list_empty(&list))
 		return false;
 
@@ -9124,8 +9370,8 @@ static void io_uring_clean_tctx(struct io_uring_task *tctx)
 		 * Must be after io_uring_del_task_file() (removes nodes under
 		 * uring_lock) to avoid race with io_uring_try_cancel_iowq().
 		 */
-		tctx->io_wq = NULL;
 		io_wq_put_and_exit(wq);
+		tctx->io_wq = NULL;
 	}
 }
 
@@ -9141,9 +9387,11 @@ static void io_uring_drop_tctx_refs(struct task_struct *task)
 	struct io_uring_task *tctx = task->io_uring;
 	unsigned int refs = tctx->cached_refs;
 
-	tctx->cached_refs = 0;
-	percpu_counter_sub(&tctx->inflight, refs);
-	put_task_struct_many(task, refs);
+	if (refs) {
+		tctx->cached_refs = 0;
+		percpu_counter_sub(&tctx->inflight, refs);
+		put_task_struct_many(task, refs);
+	}
 }
 
 /*
@@ -9164,9 +9412,9 @@ static void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
 	if (tctx->io_wq)
 		io_wq_exit_start(tctx->io_wq);
 
-	io_uring_drop_tctx_refs(current);
 	atomic_inc(&tctx->in_idle);
 	do {
+		io_uring_drop_tctx_refs(current);
 		/* read completions before cancelations */
 		inflight = tctx_inflight(tctx, !cancel_all);
 		if (!inflight)
@@ -9190,6 +9438,7 @@ static void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
 		}
 
 		prepare_to_wait(&tctx->wait, &wait, TASK_UNINTERRUPTIBLE);
+		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
@@ -9208,9 +9457,9 @@ static void io_uring_cancel_generic(bool cancel_all, struct io_sq_data *sqd)
 	}
 }
 
-void __io_uring_cancel(struct files_struct *files)
+void __io_uring_cancel(bool cancel_all)
 {
-	io_uring_cancel_generic(!files, NULL);
+	io_uring_cancel_generic(cancel_all, NULL);
 }
 
 static void *io_uring_validate_mmap_request(struct file *file,
@@ -9370,7 +9619,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 	 */
 	ret = 0;
 	if (ctx->flags & IORING_SETUP_SQPOLL) {
-		io_cqring_overflow_flush(ctx, false);
+		io_cqring_overflow_flush(ctx);
 
 		if (unlikely(ctx->sq_data->thread == NULL)) {
 			ret = -EOWNERDEAD;
@@ -9506,7 +9755,7 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
 			io_uring_show_cred(m, index, cred);
 	}
 	seq_printf(m, "PollList:\n");
-	spin_lock_irq(&ctx->completion_lock);
+	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;
@@ -9515,7 +9764,7 @@ static void __io_uring_show_fdinfo(struct io_ring_ctx *ctx, struct seq_file *m)
 			seq_printf(m, "  op=%d, task_works=%d\n", req->opcode,
 					req->task->task_works != NULL);
 	}
-	spin_unlock_irq(&ctx->completion_lock);
+	spin_unlock(&ctx->completion_lock);
 	if (has_lock)
 		mutex_unlock(&ctx->uring_lock);
 }
@@ -10048,6 +10297,31 @@ static int io_unregister_iowq_aff(struct io_ring_ctx *ctx)
 	return io_wq_cpu_affinity(tctx->io_wq, NULL);
 }
 
+static int io_register_iowq_max_workers(struct io_ring_ctx *ctx,
+					void __user *arg)
+{
+	struct io_uring_task *tctx = current->io_uring;
+	__u32 new_count[2];
+	int i, ret;
+
+	if (!tctx || !tctx->io_wq)
+		return -EINVAL;
+	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;
+
+	ret = io_wq_max_workers(tctx->io_wq, new_count);
+	if (ret)
+		return ret;
+
+	if (copy_to_user(arg, new_count, sizeof(new_count)))
+		return -EFAULT;
+
+	return 0;
+}
+
 static bool io_register_op_must_quiesce(int op)
 {
 	switch (op) {
@@ -10065,12 +10339,40 @@ static bool io_register_op_must_quiesce(int op)
 	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)
@@ -10095,31 +10397,9 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 	}
 
 	if (io_register_op_must_quiesce(opcode)) {
-		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();
-			if (ret < 0)
-				break;
-		} while (1);
-		mutex_lock(&ctx->uring_lock);
-
-		if (ret) {
-			io_refs_resurrect(&ctx->refs, &ctx->ref_comp);
+		ret = io_ctx_quiesce(ctx);
+		if (ret)
 			return ret;
-		}
 	}
 
 	switch (opcode) {
@@ -10216,6 +10496,12 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 			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;
@@ -10297,11 +10583,16 @@ static int __init io_uring_init(void)
 	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));
 
diff --git a/include/linux/io_uring.h b/include/linux/io_uring.h
index 04b650bcbbe532..649a4d7c241bcc 100644
--- a/include/linux/io_uring.h
+++ b/include/linux/io_uring.h
@@ -7,17 +7,18 @@
 
 #if defined(CONFIG_IO_URING)
 struct sock *io_uring_get_socket(struct file *file);
-void __io_uring_cancel(struct files_struct *files);
+void __io_uring_cancel(bool cancel_all);
 void __io_uring_free(struct task_struct *tsk);
 
-static inline void io_uring_files_cancel(struct files_struct *files)
+static inline void io_uring_files_cancel(void)
 {
 	if (current->io_uring)
-		__io_uring_cancel(files);
+		__io_uring_cancel(false);
 }
 static inline void io_uring_task_cancel(void)
 {
-	return io_uring_files_cancel(NULL);
+	if (current->io_uring)
+		__io_uring_cancel(true);
 }
 static inline void io_uring_free(struct task_struct *tsk)
 {
@@ -32,7 +33,7 @@ static inline struct sock *io_uring_get_socket(struct file *file)
 static inline void io_uring_task_cancel(void)
 {
 }
-static inline void io_uring_files_cancel(struct files_struct *files)
+static inline void io_uring_files_cancel(void)
 {
 }
 static inline void io_uring_free(struct task_struct *tsk)
diff --git a/include/linux/socket.h b/include/linux/socket.h
index 0d8e3dcb7f8816..d3c1a42a2edd94 100644
--- a/include/linux/socket.h
+++ b/include/linux/socket.h
@@ -421,6 +421,9 @@ extern int __sys_accept4_file(struct file *file, unsigned file_flags,
 			struct sockaddr __user *upeer_sockaddr,
 			 int __user *upeer_addrlen, int flags,
 			 unsigned long nofile);
+extern struct file *do_accept(struct file *file, unsigned file_flags,
+			      struct sockaddr __user *upeer_sockaddr,
+			      int __user *upeer_addrlen, int flags);
 extern int __sys_accept4(int fd, struct sockaddr __user *upeer_sockaddr,
 			 int __user *upeer_addrlen, int flags);
 extern int __sys_socket(int family, int type, int protocol);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 79126d5cd289d8..3caec91996589f 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -55,7 +55,10 @@ struct io_uring_sqe {
 	} __attribute__((packed));
 	/* personality to use, if used */
 	__u16	personality;
-	__s32	splice_fd_in;
+	union {
+		__s32	splice_fd_in;
+		__u32	file_index;
+	};
 	__u64	__pad2[2];
 };
 
@@ -146,9 +149,13 @@ enum {
 /*
  * sqe->timeout_flags
  */
-#define IORING_TIMEOUT_ABS	(1U << 0)
-#define IORING_TIMEOUT_UPDATE	(1U << 1)
-
+#define IORING_TIMEOUT_ABS		(1U << 0)
+#define IORING_TIMEOUT_UPDATE		(1U << 1)
+#define IORING_TIMEOUT_BOOTTIME		(1U << 2)
+#define IORING_TIMEOUT_REALTIME		(1U << 3)
+#define IORING_LINK_TIMEOUT_UPDATE	(1U << 4)
+#define IORING_TIMEOUT_CLOCK_MASK	(IORING_TIMEOUT_BOOTTIME | IORING_TIMEOUT_REALTIME)
+#define IORING_TIMEOUT_UPDATE_MASK	(IORING_TIMEOUT_UPDATE | IORING_LINK_TIMEOUT_UPDATE)
 /*
  * sqe->splice_flags
  * extends splice(2) flags
@@ -306,6 +313,9 @@ enum {
 	IORING_REGISTER_IOWQ_AFF		= 17,
 	IORING_UNREGISTER_IOWQ_AFF		= 18,
 
+	/* set/get max number of workers */
+	IORING_REGISTER_IOWQ_MAX_WORKERS	= 19,
+
 	/* this goes last */
 	IORING_REGISTER_LAST
 };
diff --git a/kernel/exit.c b/kernel/exit.c
index 9a89e7f36acb43..91a43e57a32ebb 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -777,7 +777,7 @@ void __noreturn do_exit(long code)
 		schedule();
 	}
 
-	io_uring_files_cancel(tsk->files);
+	io_uring_files_cancel();
 	exit_signals(tsk);  /* sets PF_EXITING */
 
 	/* sync mm's RSS info before statistics gathering */
diff --git a/net/socket.c b/net/socket.c
index 0b2dad3bdf7fe9..532fff5a3684f4 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1722,32 +1722,22 @@ SYSCALL_DEFINE2(listen, int, fd, int, backlog)
 	return __sys_listen(fd, backlog);
 }
 
-int __sys_accept4_file(struct file *file, unsigned file_flags,
+struct file *do_accept(struct file *file, unsigned file_flags,
 		       struct sockaddr __user *upeer_sockaddr,
-		       int __user *upeer_addrlen, int flags,
-		       unsigned long nofile)
+		       int __user *upeer_addrlen, int flags)
 {
 	struct socket *sock, *newsock;
 	struct file *newfile;
-	int err, len, newfd;
+	int err, len;
 	struct sockaddr_storage address;
 
-	if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
-		return -EINVAL;
-
-	if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
-		flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
-
 	sock = sock_from_file(file);
-	if (!sock) {
-		err = -ENOTSOCK;
-		goto out;
-	}
+	if (!sock)
+		return ERR_PTR(-ENOTSOCK);
 
-	err = -ENFILE;
 	newsock = sock_alloc();
 	if (!newsock)
-		goto out;
+		return ERR_PTR(-ENFILE);
 
 	newsock->type = sock->type;
 	newsock->ops = sock->ops;
@@ -1758,18 +1748,9 @@ int __sys_accept4_file(struct file *file, unsigned file_flags,
 	 */
 	__module_get(newsock->ops->owner);
 
-	newfd = __get_unused_fd_flags(flags, nofile);
-	if (unlikely(newfd < 0)) {
-		err = newfd;
-		sock_release(newsock);
-		goto out;
-	}
 	newfile = sock_alloc_file(newsock, flags, sock->sk->sk_prot_creator->name);
-	if (IS_ERR(newfile)) {
-		err = PTR_ERR(newfile);
-		put_unused_fd(newfd);
-		goto out;
-	}
+	if (IS_ERR(newfile))
+		return newfile;
 
 	err = security_socket_accept(sock, newsock);
 	if (err)
@@ -1794,16 +1775,38 @@ int __sys_accept4_file(struct file *file, unsigned file_flags,
 	}
 
 	/* File flags are not inherited via accept() unlike another OSes. */
-
-	fd_install(newfd, newfile);
-	err = newfd;
-out:
-	return err;
+	return newfile;
 out_fd:
 	fput(newfile);
-	put_unused_fd(newfd);
-	goto out;
+	return ERR_PTR(err);
+}
+
+int __sys_accept4_file(struct file *file, unsigned file_flags,
+		       struct sockaddr __user *upeer_sockaddr,
+		       int __user *upeer_addrlen, int flags,
+		       unsigned long nofile)
+{
+	struct file *newfile;
+	int newfd;
 
+	if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
+		return -EINVAL;
+
+	if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
+		flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
+
+	newfd = __get_unused_fd_flags(flags, nofile);
+	if (unlikely(newfd < 0))
+		return newfd;
+
+	newfile = do_accept(file, file_flags, upeer_sockaddr, upeer_addrlen,
+			    flags);
+	if (IS_ERR(newfile)) {
+		put_unused_fd(newfd);
+		return PTR_ERR(newfile);
+	}
+	fd_install(newfd, newfile);
+	return newfd;
 }
 
 /*