io_uring: add support for IORING_ASYNC_CANCEL_ALL

The current cancelation will lookup and cancel the first request it
finds based on the key passed in. Add a flag that allows to cancel any
request that matches they key. It completes with the number of requests
found and canceled, or res < 0 if an error occured.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20220418164402.75259-4-axboe@kernel.dk

fs/io-wq.h

@@ -155,6 +155,7 @@ struct io_wq_work_node *wq_stack_extract(struct io_wq_work_node *stack)
 struct io_wq_work {
 	struct io_wq_work_node list;
 	unsigned flags;
+	int cancel_seq;
 };
 
 static inline struct io_wq_work *wq_next_work(struct io_wq_work *work)

fs/io_uring.c

@@ -403,6 +403,7 @@ struct io_ring_ctx {
 		 */
 		struct io_rsrc_node	*rsrc_node;
 		int			rsrc_cached_refs;
+		atomic_t		cancel_seq;
 		struct io_file_table	file_table;
 		unsigned		nr_user_files;
 		unsigned		nr_user_bufs;
@@ -585,6 +586,7 @@ struct io_sync {
 struct io_cancel {
 	struct file			*file;
 	u64				addr;
+	u32				flags;
 };
 
 struct io_timeout {
@@ -991,6 +993,8 @@ struct io_defer_entry {
 struct io_cancel_data {
 	struct io_ring_ctx *ctx;
 	u64 data;
+	u32 flags;
+	int seq;
 };
 
 struct io_op_def {
@@ -1726,6 +1730,7 @@ static void io_prep_async_work(struct io_kiocb *req)
 
 	req->work.list.next = NULL;
 	req->work.flags = 0;
+	req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
 	if (req->flags & REQ_F_FORCE_ASYNC)
 		req->work.flags |= IO_WQ_WORK_CONCURRENT;
 
@@ -6159,6 +6164,7 @@ static int __io_arm_poll_handler(struct io_kiocb *req,
 	int v;
 
 	INIT_HLIST_NODE(&req->hash_node);
+	req->work.cancel_seq = atomic_read(&ctx->cancel_seq);
 	io_init_poll_iocb(poll, mask, io_poll_wake);
 	poll->file = req->file;
 
@@ -6316,6 +6322,11 @@ static struct io_kiocb *io_poll_find(struct io_ring_ctx *ctx, bool poll_only,
 			continue;
 		if (poll_only && req->opcode != IORING_OP_POLL_ADD)
 			continue;
+		if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
+			if (cd->seq == req->work.cancel_seq)
+				continue;
+			req->work.cancel_seq = cd->seq;
+		}
 		return req;
 	}
 	return NULL;
@@ -6501,9 +6512,15 @@ static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
 	bool found = false;
 
 	list_for_each_entry(req, &ctx->timeout_list, timeout.list) {
-		found = cd->data == req->cqe.user_data;
-		if (found)
-			break;
+		if (cd->data != req->cqe.user_data)
+			continue;
+		if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
+			if (cd->seq == req->work.cancel_seq)
+				continue;
+			req->work.cancel_seq = cd->seq;
+		}
+		found = true;
+		break;
 	}
 	if (!found)
 		return ERR_PTR(-ENOENT);
@@ -6777,7 +6794,16 @@ static bool io_cancel_cb(struct io_wq_work *work, void *data)
 	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
 	struct io_cancel_data *cd = data;
 
-	return req->ctx == cd->ctx && req->cqe.user_data == cd->data;
+	if (req->ctx != cd->ctx)
+		return false;
+	if (req->cqe.user_data != cd->data)
+		return false;
+	if (cd->flags & IORING_ASYNC_CANCEL_ALL) {
+		if (cd->seq == req->work.cancel_seq)
+			return false;
+		req->work.cancel_seq = cd->seq;
+	}
+	return true;
 }
 
 static int io_async_cancel_one(struct io_uring_task *tctx,
@@ -6789,7 +6815,8 @@ static int io_async_cancel_one(struct io_uring_task *tctx,
 	if (!tctx || !tctx->io_wq)
 		return -ENOENT;
 
-	cancel_ret = io_wq_cancel_cb(tctx->io_wq, io_cancel_cb, cd, false);
+	cancel_ret = io_wq_cancel_cb(tctx->io_wq, io_cancel_cb, cd,
+					cd->flags & IORING_ASYNC_CANCEL_ALL);
 	switch (cancel_ret) {
 	case IO_WQ_CANCEL_OK:
 		ret = 0;
@@ -6837,27 +6864,33 @@ 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 ||
-	    sqe->splice_fd_in)
+	if (sqe->ioprio || sqe->off || sqe->len || sqe->splice_fd_in)
 		return -EINVAL;
 
 	req->cancel.addr = READ_ONCE(sqe->addr);
+	req->cancel.flags = READ_ONCE(sqe->cancel_flags);
+	if (req->cancel.flags & ~IORING_ASYNC_CANCEL_ALL)
+		return -EINVAL;
+
 	return 0;
 }
 
-static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
+static int __io_async_cancel(struct io_cancel_data *cd, struct io_kiocb *req,
+			     unsigned int issue_flags)
 {
-	struct io_ring_ctx *ctx = req->ctx;
-	struct io_cancel_data cd = {
-		.ctx		= ctx,
-		.data		= req->cancel.addr,
-	};
+	bool cancel_all = cd->flags & IORING_ASYNC_CANCEL_ALL;
+	struct io_ring_ctx *ctx = cd->ctx;
 	struct io_tctx_node *node;
-	int ret;
+	int ret, nr = 0;
 
-	ret = io_try_cancel(req, &cd);
-	if (ret != -ENOENT)
-		goto done;
+	do {
+		ret = io_try_cancel(req, cd);
+		if (ret == -ENOENT)
+			break;
+		if (!cancel_all)
+			return ret;
+		nr++;
+	} while (1);
 
 	/* slow path, try all io-wq's */
 	io_ring_submit_lock(ctx, issue_flags);
@@ -6865,12 +6898,28 @@ static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
 	list_for_each_entry(node, &ctx->tctx_list, ctx_node) {
 		struct io_uring_task *tctx = node->task->io_uring;
 
-		ret = io_async_cancel_one(tctx, &cd);
-		if (ret != -ENOENT)
-			break;
+		ret = io_async_cancel_one(tctx, cd);
+		if (ret != -ENOENT) {
+			if (!cancel_all)
+				break;
+			nr++;
+		}
 	}
 	io_ring_submit_unlock(ctx, issue_flags);
-done:
+	return cancel_all ? nr : ret;
+}
+
+static int io_async_cancel(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_cancel_data cd = {
+		.ctx	= req->ctx,
+		.data	= req->cancel.addr,
+		.flags	= req->cancel.flags,
+		.seq	= atomic_inc_return(&req->ctx->cancel_seq),
+	};
+	int ret;
+
+	ret = __io_async_cancel(&cd, req, issue_flags);
 	if (ret < 0)
 		req_set_fail(req);
 	io_req_complete_post(req, ret, 0);

include/uapi/linux/io_uring.h

@@ -187,6 +187,13 @@ enum {
 #define IORING_POLL_UPDATE_EVENTS	(1U << 1)
 #define IORING_POLL_UPDATE_USER_DATA	(1U << 2)
 
+/*
+ * ASYNC_CANCEL flags.
+ *
+ * IORING_ASYNC_CANCEL_ALL	Cancel all requests that match the given key
+ */
+#define IORING_ASYNC_CANCEL_ALL	(1U << 0)
+
 /*
  * IO completion data structure (Completion Queue Entry)
  */