Merge branch 'io_uring-5.5' into for-linus

* io_uring-5.5:
  io_uring: fix a typo in a comment
  io_uring: hook all linked requests via link_list
  io_uring: fix error handling in io_queue_link_head
  io_uring: use hash table for poll command lookups

Author: axboe

fs/io_uring.c

@@ -145,7 +145,7 @@ struct io_rings {
 	/*
 	 * Number of completion events lost because the queue was full;
 	 * this should be avoided by the application by making sure
-	 * there are not more requests pending thatn there is space in
+	 * there are not more requests pending than there is space in
 	 * the completion queue.
 	 *
 	 * Written by the kernel, shouldn't be modified by the
@@ -275,7 +275,8 @@ struct io_ring_ctx {
 		 * manipulate the list, hence no extra locking is needed there.
 		 */
 		struct list_head	poll_list;
-		struct rb_root		cancel_tree;
+		struct hlist_head	*cancel_hash;
+		unsigned		cancel_hash_bits;
 
 		spinlock_t		inflight_lock;
 		struct list_head	inflight_list;
@@ -355,7 +356,7 @@ struct io_kiocb {
 	struct io_ring_ctx	*ctx;
 	union {
 		struct list_head	list;
-		struct rb_node		rb_node;
+		struct hlist_node	hash_node;
 	};
 	struct list_head	link_list;
 	unsigned int		flags;
@@ -444,6 +445,7 @@ static void io_ring_ctx_ref_free(struct percpu_ref *ref)
 static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 {
 	struct io_ring_ctx *ctx;
+	int hash_bits;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -457,6 +459,21 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	if (!ctx->completions)
 		goto err;
 
+	/*
+	 * Use 5 bits less than the max cq entries, that should give us around
+	 * 32 entries per hash list if totally full and uniformly spread.
+	 */
+	hash_bits = ilog2(p->cq_entries);
+	hash_bits -= 5;
+	if (hash_bits <= 0)
+		hash_bits = 1;
+	ctx->cancel_hash_bits = hash_bits;
+	ctx->cancel_hash = kmalloc((1U << hash_bits) * sizeof(struct hlist_head),
+					GFP_KERNEL);
+	if (!ctx->cancel_hash)
+		goto err;
+	__hash_init(ctx->cancel_hash, 1U << hash_bits);
+
 	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free,
 			    PERCPU_REF_ALLOW_REINIT, GFP_KERNEL))
 		goto err;
@@ -470,7 +487,6 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	init_waitqueue_head(&ctx->wait);
 	spin_lock_init(&ctx->completion_lock);
 	INIT_LIST_HEAD(&ctx->poll_list);
-	ctx->cancel_tree = RB_ROOT;
 	INIT_LIST_HEAD(&ctx->defer_list);
 	INIT_LIST_HEAD(&ctx->timeout_list);
 	init_waitqueue_head(&ctx->inflight_wait);
@@ -481,6 +497,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	if (ctx->fallback_req)
 		kmem_cache_free(req_cachep, ctx->fallback_req);
 	kfree(ctx->completions);
+	kfree(ctx->cancel_hash);
 	kfree(ctx);
 	return NULL;
 }
@@ -899,7 +916,6 @@ static bool io_link_cancel_timeout(struct io_kiocb *req)
 static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	struct io_kiocb *nxt;
 	bool wake_ev = false;
 
 	/* Already got next link */
@@ -911,24 +927,21 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 	 * potentially happen if the chain is messed up, check to be on the
 	 * safe side.
 	 */
-	nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, list);
-	while (nxt) {
-		list_del_init(&nxt->list);
+	while (!list_empty(&req->link_list)) {
+		struct io_kiocb *nxt = list_first_entry(&req->link_list,
+						struct io_kiocb, link_list);
 
-		if ((req->flags & REQ_F_LINK_TIMEOUT) &&
-		    (nxt->flags & REQ_F_TIMEOUT)) {
+		if (unlikely((req->flags & REQ_F_LINK_TIMEOUT) &&
+			     (nxt->flags & REQ_F_TIMEOUT))) {
+			list_del_init(&nxt->link_list);
 			wake_ev |= io_link_cancel_timeout(nxt);
-			nxt = list_first_entry_or_null(&req->link_list,
-							struct io_kiocb, list);
 			req->flags &= ~REQ_F_LINK_TIMEOUT;
 			continue;
 		}
-		if (!list_empty(&req->link_list)) {
-			INIT_LIST_HEAD(&nxt->link_list);
-			list_splice(&req->link_list, &nxt->link_list);
-			nxt->flags |= REQ_F_LINK;
-		}
 
+		list_del_init(&req->link_list);
+		if (!list_empty(&nxt->link_list))
+			nxt->flags |= REQ_F_LINK;
 		*nxtptr = nxt;
 		break;
 	}
@@ -944,15 +957,15 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 static void io_fail_links(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	struct io_kiocb *link;
 	unsigned long flags;
 
 	spin_lock_irqsave(&ctx->completion_lock, flags);
 
 	while (!list_empty(&req->link_list)) {
-		link = list_first_entry(&req->link_list, struct io_kiocb, list);
-		list_del_init(&link->list);
+		struct io_kiocb *link = list_first_entry(&req->link_list,
+						struct io_kiocb, link_list);
 
+		list_del_init(&link->link_list);
 		trace_io_uring_fail_link(req, link);
 
 		if ((req->flags & REQ_F_LINK_TIMEOUT) &&
@@ -2260,14 +2273,6 @@ static int io_connect(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 #endif
 }
 
-static inline void io_poll_remove_req(struct io_kiocb *req)
-{
-	if (!RB_EMPTY_NODE(&req->rb_node)) {
-		rb_erase(&req->rb_node, &req->ctx->cancel_tree);
-		RB_CLEAR_NODE(&req->rb_node);
-	}
-}
-
 static void io_poll_remove_one(struct io_kiocb *req)
 {
 	struct io_poll_iocb *poll = &req->poll;
@@ -2279,36 +2284,34 @@ static void io_poll_remove_one(struct io_kiocb *req)
 		io_queue_async_work(req);
 	}
 	spin_unlock(&poll->head->lock);
-	io_poll_remove_req(req);
+	hash_del(&req->hash_node);
 }
 
 static void io_poll_remove_all(struct io_ring_ctx *ctx)
 {
-	struct rb_node *node;
+	struct hlist_node *tmp;
 	struct io_kiocb *req;
+	int i;
 
 	spin_lock_irq(&ctx->completion_lock);
-	while ((node = rb_first(&ctx->cancel_tree)) != NULL) {
-		req = rb_entry(node, struct io_kiocb, rb_node);
-		io_poll_remove_one(req);
+	for (i = 0; i < (1U << ctx->cancel_hash_bits); i++) {
+		struct hlist_head *list;
+
+		list = &ctx->cancel_hash[i];
+		hlist_for_each_entry_safe(req, tmp, list, hash_node)
+			io_poll_remove_one(req);
 	}
 	spin_unlock_irq(&ctx->completion_lock);
 }
 
 static int io_poll_cancel(struct io_ring_ctx *ctx, __u64 sqe_addr)
 {
-	struct rb_node *p, *parent = NULL;
+	struct hlist_head *list;
 	struct io_kiocb *req;
 
-	p = ctx->cancel_tree.rb_node;
-	while (p) {
-		parent = p;
-		req = rb_entry(parent, struct io_kiocb, rb_node);
-		if (sqe_addr < req->user_data) {
-			p = p->rb_left;
-		} else if (sqe_addr > req->user_data) {
-			p = p->rb_right;
-		} else {
+	list = &ctx->cancel_hash[hash_long(sqe_addr, ctx->cancel_hash_bits)];
+	hlist_for_each_entry(req, list, hash_node) {
+		if (sqe_addr == req->user_data) {
 			io_poll_remove_one(req);
 			return 0;
 		}
@@ -2390,7 +2393,7 @@ static void io_poll_complete_work(struct io_wq_work **workptr)
 		spin_unlock_irq(&ctx->completion_lock);
 		return;
 	}
-	io_poll_remove_req(req);
+	hash_del(&req->hash_node);
 	io_poll_complete(req, mask, ret);
 	spin_unlock_irq(&ctx->completion_lock);
 
@@ -2425,7 +2428,7 @@ static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
 	 * for finalizing the request, mark us as having grabbed that already.
 	 */
 	if (mask && spin_trylock_irqsave(&ctx->completion_lock, flags)) {
-		io_poll_remove_req(req);
+		hash_del(&req->hash_node);
 		io_poll_complete(req, mask, 0);
 		req->flags |= REQ_F_COMP_LOCKED;
 		io_put_req(req);
@@ -2463,20 +2466,10 @@ static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
 static void io_poll_req_insert(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	struct rb_node **p = &ctx->cancel_tree.rb_node;
-	struct rb_node *parent = NULL;
-	struct io_kiocb *tmp;
-
-	while (*p) {
-		parent = *p;
-		tmp = rb_entry(parent, struct io_kiocb, rb_node);
-		if (req->user_data < tmp->user_data)
-			p = &(*p)->rb_left;
-		else
-			p = &(*p)->rb_right;
-	}
-	rb_link_node(&req->rb_node, parent, p);
-	rb_insert_color(&req->rb_node, &ctx->cancel_tree);
+	struct hlist_head *list;
+
+	list = &ctx->cancel_hash[hash_long(req->user_data, ctx->cancel_hash_bits)];
+	hlist_add_head(&req->hash_node, list);
 }
 
 static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe,
@@ -2504,7 +2497,7 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	INIT_IO_WORK(&req->work, io_poll_complete_work);
 	events = READ_ONCE(sqe->poll_events);
 	poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
-	RB_CLEAR_NODE(&req->rb_node);
+	INIT_HLIST_NODE(&req->hash_node);
 
 	poll->head = NULL;
 	poll->done = false;
@@ -3173,10 +3166,11 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
 	 * We don't expect the list to be empty, that will only happen if we
 	 * race with the completion of the linked work.
 	 */
-	if (!list_empty(&req->list)) {
-		prev = list_entry(req->list.prev, struct io_kiocb, link_list);
+	if (!list_empty(&req->link_list)) {
+		prev = list_entry(req->link_list.prev, struct io_kiocb,
+				  link_list);
 		if (refcount_inc_not_zero(&prev->refs)) {
-			list_del_init(&req->list);
+			list_del_init(&req->link_list);
 			prev->flags &= ~REQ_F_LINK_TIMEOUT;
 		} else
 			prev = NULL;
@@ -3206,7 +3200,7 @@ static void io_queue_linked_timeout(struct io_kiocb *req)
 	 * we got a chance to setup the timer
 	 */
 	spin_lock_irq(&ctx->completion_lock);
-	if (!list_empty(&req->list)) {
+	if (!list_empty(&req->link_list)) {
 		struct io_timeout_data *data = &req->io->timeout;
 
 		data->timer.function = io_link_timeout_fn;
@@ -3226,7 +3220,8 @@ static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
 	if (!(req->flags & REQ_F_LINK))
 		return NULL;
 
-	nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb, list);
+	nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb,
+					link_list);
 	if (!nxt || nxt->sqe->opcode != IORING_OP_LINK_TIMEOUT)
 		return NULL;
 
@@ -3318,7 +3313,7 @@ static inline void io_queue_link_head(struct io_kiocb *req)
 
 #define SQE_VALID_FLAGS	(IOSQE_FIXED_FILE|IOSQE_IO_DRAIN|IOSQE_IO_LINK)
 
-static void io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
+static bool io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 			  struct io_kiocb **link)
 {
 	struct io_ring_ctx *ctx = req->ctx;
@@ -3337,7 +3332,7 @@ static void io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 err_req:
 		io_cqring_add_event(req, ret);
 		io_double_put_req(req);
-		return;
+		return false;
 	}
 
 	/*
@@ -3367,7 +3362,7 @@ static void io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 			goto err_req;
 		}
 		trace_io_uring_link(ctx, req, prev);
-		list_add_tail(&req->list, &prev->link_list);
+		list_add_tail(&req->link_list, &prev->link_list);
 	} else if (req->sqe->flags & IOSQE_IO_LINK) {
 		req->flags |= REQ_F_LINK;
 
@@ -3376,6 +3371,8 @@ static void io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 	} else {
 		io_queue_sqe(req);
 	}
+
+	return true;
 }
 
 /*
@@ -3505,6 +3502,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 			}
 		}
 
+		submitted++;
 		sqe_flags = req->sqe->flags;
 
 		req->ring_file = ring_file;
@@ -3514,9 +3512,8 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 		req->needs_fixed_file = async;
 		trace_io_uring_submit_sqe(ctx, req->sqe->user_data,
 					  true, async);
-		io_submit_sqe(req, statep, &link);
-		submitted++;
-
+		if (!io_submit_sqe(req, statep, &link))
+			break;
 		/*
 		 * If previous wasn't linked and we have a linked command,
 		 * that's the end of the chain. Submit the previous link.
@@ -4644,6 +4641,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 	free_uid(ctx->user);
 	put_cred(ctx->creds);
 	kfree(ctx->completions);
+	kfree(ctx->cancel_hash);
 	kmem_cache_free(req_cachep, ctx->fallback_req);
 	kfree(ctx);
 }