Merge tag 'io_uring-5.5-20191220' of git://git.kernel.dk/linux-block

Pull io_uring fixes from Jens Axboe:
 "Here's a set of fixes that should go into 5.5-rc3 for io_uring.

  This is bigger than I'd like it to be, mainly because we're fixing the
  case where an application reuses sqe data right after issue. This
  really must work, or it's confusing. With 5.5 we're flagging us as
  submit stable for the actual data, this must also be the case for
  SQEs.

  Honestly, I'd really like to add another series on top of this, since
  it cleans it up considerable and prevents any SQE reuse by design. I
  posted that here:

    https://lore.kernel.org/io-uring/20191220174742.7449-1-axboe@kernel.dk/T/#u

  and may still send it your way early next week once it's been looked
  at and had some more soak time (does pass all regression tests). With
  that series, we've unified the prep+issue handling, and only the prep
  phase even has access to the SQE.

  Anyway, outside of that, fixes in here for a few other issues that
  have been hit in testing or production"

* tag 'io_uring-5.5-20191220' of git://git.kernel.dk/linux-block:
  io_uring: io_wq_submit_work() should not touch req->rw
  io_uring: don't wait when under-submitting
  io_uring: warn about unhandled opcode
  io_uring: read opcode and user_data from SQE exactly once
  io_uring: make IORING_OP_TIMEOUT_REMOVE deferrable
  io_uring: make IORING_OP_CANCEL_ASYNC deferrable
  io_uring: make IORING_POLL_ADD and IORING_POLL_REMOVE deferrable
  io_uring: make HARDLINK imply LINK
  io_uring: any deferred command must have stable sqe data
  io_uring: remove 'sqe' parameter to the OP helpers that take it
  io_uring: fix pre-prepped issue with force_nonblock == true
  io-wq: re-add io_wq_current_is_worker()
  io_uring: fix sporadic -EFAULT from IORING_OP_RECVMSG
  io_uring: fix stale comment and a few typos

fs/io-wq.c

@@ -948,7 +948,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
 	/*
 	 * Now check if a free (going busy) or busy worker has the work
 	 * currently running. If we find it there, we'll return CANCEL_RUNNING
-	 * as an indication that we attempte to signal cancellation. The
+	 * as an indication that we attempt to signal cancellation. The
 	 * completion will run normally in this case.
 	 */
 	rcu_read_lock();

fs/io-wq.h

@@ -120,6 +120,10 @@ static inline void io_wq_worker_sleeping(struct task_struct *tsk)
 static inline void io_wq_worker_running(struct task_struct *tsk)
 {
 }
-#endif /* CONFIG_IO_WQ */
+#endif
 
-#endif /* INTERNAL_IO_WQ_H */
+static inline bool io_wq_current_is_worker(void)
+{
+	return in_task() && (current->flags & PF_IO_WORKER);
+}
+#endif

fs/io_uring.c

@@ -289,7 +289,10 @@ struct io_ring_ctx {
  */
 struct io_poll_iocb {
 	struct file			*file;
-	struct wait_queue_head		*head;
+	union {
+		struct wait_queue_head	*head;
+		u64			addr;
+	};
 	__poll_t			events;
 	bool				done;
 	bool				canceled;
@@ -304,6 +307,31 @@ struct io_timeout_data {
 	u32				seq_offset;
 };
 
+struct io_accept {
+	struct file			*file;
+	struct sockaddr __user		*addr;
+	int __user			*addr_len;
+	int				flags;
+};
+
+struct io_sync {
+	struct file			*file;
+	loff_t				len;
+	loff_t				off;
+	int				flags;
+};
+
+struct io_cancel {
+	struct file			*file;
+	u64				addr;
+};
+
+struct io_timeout {
+	struct file			*file;
+	u64				addr;
+	int				flags;
+};
+
 struct io_async_connect {
 	struct sockaddr_storage		address;
 };
@@ -343,6 +371,10 @@ struct io_kiocb {
 		struct file		*file;
 		struct kiocb		rw;
 		struct io_poll_iocb	poll;
+		struct io_accept	accept;
+		struct io_sync		sync;
+		struct io_cancel	cancel;
+		struct io_timeout	timeout;
 	};
 
 	const struct io_uring_sqe	*sqe;
@@ -352,6 +384,7 @@ struct io_kiocb {
 	bool				has_user;
 	bool				in_async;
 	bool				needs_fixed_file;
+	u8				opcode;
 
 	struct io_ring_ctx	*ctx;
 	union {
@@ -378,6 +411,7 @@ struct io_kiocb {
 #define REQ_F_INFLIGHT		16384	/* on inflight list */
 #define REQ_F_COMP_LOCKED	32768	/* completion under lock */
 #define REQ_F_HARDLINK		65536	/* doesn't sever on completion < 0 */
+#define REQ_F_PREPPED		131072	/* request already opcode prepared */
 	u64			user_data;
 	u32			result;
 	u32			sequence;
@@ -564,12 +598,10 @@ static void __io_commit_cqring(struct io_ring_ctx *ctx)
 	}
 }
 
-static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
+static inline bool io_req_needs_user(struct io_kiocb *req)
 {
-	u8 opcode = READ_ONCE(sqe->opcode);
-
-	return !(opcode == IORING_OP_READ_FIXED ||
-		 opcode == IORING_OP_WRITE_FIXED);
+	return !(req->opcode == IORING_OP_READ_FIXED ||
+		 req->opcode == IORING_OP_WRITE_FIXED);
 }
 
 static inline bool io_prep_async_work(struct io_kiocb *req,
@@ -578,7 +610,7 @@ static inline bool io_prep_async_work(struct io_kiocb *req,
 	bool do_hashed = false;
 
 	if (req->sqe) {
-		switch (req->sqe->opcode) {
+		switch (req->opcode) {
 		case IORING_OP_WRITEV:
 		case IORING_OP_WRITE_FIXED:
 			/* only regular files should be hashed for writes */
@@ -601,7 +633,7 @@ static inline bool io_prep_async_work(struct io_kiocb *req,
 				req->work.flags |= IO_WQ_WORK_UNBOUND;
 			break;
 		}
-		if (io_sqe_needs_user(req->sqe))
+		if (io_req_needs_user(req))
 			req->work.flags |= IO_WQ_WORK_NEEDS_USER;
 	}
 
@@ -972,7 +1004,7 @@ static void io_fail_links(struct io_kiocb *req)
 		trace_io_uring_fail_link(req, link);
 
 		if ((req->flags & REQ_F_LINK_TIMEOUT) &&
-		    link->sqe->opcode == IORING_OP_LINK_TIMEOUT) {
+		    link->opcode == IORING_OP_LINK_TIMEOUT) {
 			io_link_cancel_timeout(link);
 		} else {
 			io_cqring_fill_event(link, -ECANCELED);
@@ -1178,7 +1210,7 @@ static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
 }
 
 /*
- * Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
+ * Poll for a minimum of 'min' events. Note that if min == 0 we consider that a
  * non-spinning poll check - we'll still enter the driver poll loop, but only
  * as a non-spinning completion check.
  */
@@ -1615,7 +1647,7 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
 	 * for that purpose and instead let the caller pass in the read/write
 	 * flag.
 	 */
-	opcode = READ_ONCE(sqe->opcode);
+	opcode = req->opcode;
 	if (opcode == IORING_OP_READ_FIXED || opcode == IORING_OP_WRITE_FIXED) {
 		*iovec = NULL;
 		return io_import_fixed(req->ctx, rw, sqe, iter);
@@ -1701,7 +1733,7 @@ static ssize_t loop_rw_iter(int rw, struct file *file, struct kiocb *kiocb,
 	return ret;
 }
 
-static void io_req_map_io(struct io_kiocb *req, ssize_t io_size,
+static void io_req_map_rw(struct io_kiocb *req, ssize_t io_size,
 			  struct iovec *iovec, struct iovec *fast_iov,
 			  struct iov_iter *iter)
 {
@@ -1715,19 +1747,39 @@ static void io_req_map_io(struct io_kiocb *req, ssize_t io_size,
 	}
 }
 
-static int io_setup_async_io(struct io_kiocb *req, ssize_t io_size,
-			     struct iovec *iovec, struct iovec *fast_iov,
-			     struct iov_iter *iter)
+static int io_alloc_async_ctx(struct io_kiocb *req)
 {
 	req->io = kmalloc(sizeof(*req->io), GFP_KERNEL);
 	if (req->io) {
-		io_req_map_io(req, io_size, iovec, fast_iov, iter);
 		memcpy(&req->io->sqe, req->sqe, sizeof(req->io->sqe));
 		req->sqe = &req->io->sqe;
 		return 0;
 	}
 
-	return -ENOMEM;
+	return 1;
+}
+
+static void io_rw_async(struct io_wq_work **workptr)
+{
+	struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+	struct iovec *iov = NULL;
+
+	if (req->io->rw.iov != req->io->rw.fast_iov)
+		iov = req->io->rw.iov;
+	io_wq_submit_work(workptr);
+	kfree(iov);
+}
+
+static int io_setup_async_rw(struct io_kiocb *req, ssize_t io_size,
+			     struct iovec *iovec, struct iovec *fast_iov,
+			     struct iov_iter *iter)
+{
+	if (!req->io && io_alloc_async_ctx(req))
+		return -ENOMEM;
+
+	io_req_map_rw(req, io_size, iovec, fast_iov, iter);
+	req->work.func = io_rw_async;
+	return 0;
 }
 
 static int io_read_prep(struct io_kiocb *req, struct iovec **iovec,
@@ -1765,6 +1817,10 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
 			return ret;
 	}
 
+	/* Ensure we clear previously set non-block flag */
+	if (!force_nonblock)
+		req->rw.ki_flags &= ~IOCB_NOWAIT;
+
 	file = req->file;
 	io_size = ret;
 	if (req->flags & REQ_F_LINK)
@@ -1806,7 +1862,7 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
 			kiocb_done(kiocb, ret2, nxt, req->in_async);
 		} else {
 copy_iov:
-			ret = io_setup_async_io(req, io_size, iovec,
+			ret = io_setup_async_rw(req, io_size, iovec,
 						inline_vecs, &iter);
 			if (ret)
 				goto out_free;
@@ -1814,7 +1870,8 @@ static int io_read(struct io_kiocb *req, struct io_kiocb **nxt,
 		}
 	}
 out_free:
-	kfree(iovec);
+	if (!io_wq_current_is_worker())
+		kfree(iovec);
 	return ret;
 }
 
@@ -1853,6 +1910,10 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
 			return ret;
 	}
 
+	/* Ensure we clear previously set non-block flag */
+	if (!force_nonblock)
+		req->rw.ki_flags &= ~IOCB_NOWAIT;
+
 	file = kiocb->ki_filp;
 	io_size = ret;
 	if (req->flags & REQ_F_LINK)
@@ -1900,7 +1961,7 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
 			kiocb_done(kiocb, ret2, nxt, req->in_async);
 		} else {
 copy_iov:
-			ret = io_setup_async_io(req, io_size, iovec,
+			ret = io_setup_async_rw(req, io_size, iovec,
 						inline_vecs, &iter);
 			if (ret)
 				goto out_free;
@@ -1908,7 +1969,8 @@ static int io_write(struct io_kiocb *req, struct io_kiocb **nxt,
 		}
 	}
 out_free:
-	kfree(iovec);
+	if (!io_wq_current_is_worker())
+		kfree(iovec);
 	return ret;
 }
 
@@ -1927,10 +1989,13 @@ static int io_nop(struct io_kiocb *req)
 	return 0;
 }
 
-static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int io_prep_fsync(struct io_kiocb *req)
 {
+	const struct io_uring_sqe *sqe = req->sqe;
 	struct io_ring_ctx *ctx = req->ctx;
 
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
 	if (!req->file)
 		return -EBADF;
 
@@ -1939,46 +2004,80 @@ static int io_prep_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
 		return -EINVAL;
 
+	req->sync.flags = READ_ONCE(sqe->fsync_flags);
+	if (unlikely(req->sync.flags & ~IORING_FSYNC_DATASYNC))
+		return -EINVAL;
+
+	req->sync.off = READ_ONCE(sqe->off);
+	req->sync.len = READ_ONCE(sqe->len);
+	req->flags |= REQ_F_PREPPED;
 	return 0;
 }
 
-static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		    struct io_kiocb **nxt, bool force_nonblock)
+static bool io_req_cancelled(struct io_kiocb *req)
 {
-	loff_t sqe_off = READ_ONCE(sqe->off);
-	loff_t sqe_len = READ_ONCE(sqe->len);
-	loff_t end = sqe_off + sqe_len;
-	unsigned fsync_flags;
+	if (req->work.flags & IO_WQ_WORK_CANCEL) {
+		req_set_fail_links(req);
+		io_cqring_add_event(req, -ECANCELED);
+		io_put_req(req);
+		return true;
+	}
+
+	return false;
+}
+
+static void io_fsync_finish(struct io_wq_work **workptr)
+{
+	struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+	loff_t end = req->sync.off + req->sync.len;
+	struct io_kiocb *nxt = NULL;
 	int ret;
 
-	fsync_flags = READ_ONCE(sqe->fsync_flags);
-	if (unlikely(fsync_flags & ~IORING_FSYNC_DATASYNC))
-		return -EINVAL;
+	if (io_req_cancelled(req))
+		return;
+
+	ret = vfs_fsync_range(req->rw.ki_filp, req->sync.off,
+				end > 0 ? end : LLONG_MAX,
+				req->sync.flags & IORING_FSYNC_DATASYNC);
+	if (ret < 0)
+		req_set_fail_links(req);
+	io_cqring_add_event(req, ret);
+	io_put_req_find_next(req, &nxt);
+	if (nxt)
+		*workptr = &nxt->work;
+}
+
+static int io_fsync(struct io_kiocb *req, struct io_kiocb **nxt,
+		    bool force_nonblock)
+{
+	struct io_wq_work *work, *old_work;
+	int ret;
 
-	ret = io_prep_fsync(req, sqe);
+	ret = io_prep_fsync(req);
 	if (ret)
 		return ret;
 
 	/* fsync always requires a blocking context */
-	if (force_nonblock)
+	if (force_nonblock) {
+		io_put_req(req);
+		req->work.func = io_fsync_finish;
 		return -EAGAIN;
+	}
 
-	ret = vfs_fsync_range(req->rw.ki_filp, sqe_off,
-				end > 0 ? end : LLONG_MAX,
-				fsync_flags & IORING_FSYNC_DATASYNC);
-
-	if (ret < 0)
-		req_set_fail_links(req);
-	io_cqring_add_event(req, ret);
-	io_put_req_find_next(req, nxt);
+	work = old_work = &req->work;
+	io_fsync_finish(&work);
+	if (work && work != old_work)
+		*nxt = container_of(work, struct io_kiocb, work);
 	return 0;
 }
 
-static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int io_prep_sfr(struct io_kiocb *req)
 {
+	const struct io_uring_sqe *sqe = req->sqe;
 	struct io_ring_ctx *ctx = req->ctx;
-	int ret = 0;
 
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
 	if (!req->file)
 		return -EBADF;
 
@@ -1987,39 +2086,68 @@ static int io_prep_sfr(struct io_kiocb *req, const struct io_uring_sqe *sqe)
 	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
 		return -EINVAL;
 
-	return ret;
+	req->sync.off = READ_ONCE(sqe->off);
+	req->sync.len = READ_ONCE(sqe->len);
+	req->sync.flags = READ_ONCE(sqe->sync_range_flags);
+	req->flags |= REQ_F_PREPPED;
+	return 0;
 }
 
-static int io_sync_file_range(struct io_kiocb *req,
-			      const struct io_uring_sqe *sqe,
-			      struct io_kiocb **nxt,
+static void io_sync_file_range_finish(struct io_wq_work **workptr)
+{
+	struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+	struct io_kiocb *nxt = NULL;
+	int ret;
+
+	if (io_req_cancelled(req))
+		return;
+
+	ret = sync_file_range(req->rw.ki_filp, req->sync.off, req->sync.len,
+				req->sync.flags);
+	if (ret < 0)
+		req_set_fail_links(req);
+	io_cqring_add_event(req, ret);
+	io_put_req_find_next(req, &nxt);
+	if (nxt)
+		*workptr = &nxt->work;
+}
+
+static int io_sync_file_range(struct io_kiocb *req, struct io_kiocb **nxt,
 			      bool force_nonblock)
 {
-	loff_t sqe_off;
-	loff_t sqe_len;
-	unsigned flags;
+	struct io_wq_work *work, *old_work;
 	int ret;
 
-	ret = io_prep_sfr(req, sqe);
+	ret = io_prep_sfr(req);
 	if (ret)
 		return ret;
 
 	/* sync_file_range always requires a blocking context */
-	if (force_nonblock)
+	if (force_nonblock) {
+		io_put_req(req);
+		req->work.func = io_sync_file_range_finish;
 		return -EAGAIN;
+	}
 
-	sqe_off = READ_ONCE(sqe->off);
-	sqe_len = READ_ONCE(sqe->len);
-	flags = READ_ONCE(sqe->sync_range_flags);
+	work = old_work = &req->work;
+	io_sync_file_range_finish(&work);
+	if (work && work != old_work)
+		*nxt = container_of(work, struct io_kiocb, work);
+	return 0;
+}
 
-	ret = sync_file_range(req->rw.ki_filp, sqe_off, sqe_len, flags);
+#if defined(CONFIG_NET)
+static void io_sendrecv_async(struct io_wq_work **workptr)
+{
+	struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+	struct iovec *iov = NULL;
 
-	if (ret < 0)
-		req_set_fail_links(req);
-	io_cqring_add_event(req, ret);
-	io_put_req_find_next(req, nxt);
-	return 0;
+	if (req->io->rw.iov != req->io->rw.fast_iov)
+		iov = req->io->msg.iov;
+	io_wq_submit_work(workptr);
+	kfree(iov);
 }
+#endif
 
 static int io_sendmsg_prep(struct io_kiocb *req, struct io_async_ctx *io)
 {
@@ -2037,10 +2165,12 @@ static int io_sendmsg_prep(struct io_kiocb *req, struct io_async_ctx *io)
 #endif
 }
 
-static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		      struct io_kiocb **nxt, bool force_nonblock)
+static int io_sendmsg(struct io_kiocb *req, struct io_kiocb **nxt,
+		      bool force_nonblock)
 {
 #if defined(CONFIG_NET)
+	const struct io_uring_sqe *sqe = req->sqe;
+	struct io_async_msghdr *kmsg = NULL;
 	struct socket *sock;
 	int ret;
 
@@ -2049,9 +2179,8 @@ static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
 	sock = sock_from_file(req->file, &ret);
 	if (sock) {
-		struct io_async_ctx io, *copy;
+		struct io_async_ctx io;
 		struct sockaddr_storage addr;
-		struct msghdr *kmsg;
 		unsigned flags;
 
 		flags = READ_ONCE(sqe->msg_flags);
@@ -2061,34 +2190,37 @@ static int io_sendmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 			flags |= MSG_DONTWAIT;
 
 		if (req->io) {
-			kmsg = &req->io->msg.msg;
-			kmsg->msg_name = &addr;
+			kmsg = &req->io->msg;
+			kmsg->msg.msg_name = &addr;
+			/* if iov is set, it's allocated already */
+			if (!kmsg->iov)
+				kmsg->iov = kmsg->fast_iov;
+			kmsg->msg.msg_iter.iov = kmsg->iov;
 		} else {
-			kmsg = &io.msg.msg;
-			kmsg->msg_name = &addr;
+			kmsg = &io.msg;
+			kmsg->msg.msg_name = &addr;
 			ret = io_sendmsg_prep(req, &io);
 			if (ret)
 				goto out;
 		}
 
-		ret = __sys_sendmsg_sock(sock, kmsg, flags);
+		ret = __sys_sendmsg_sock(sock, &kmsg->msg, flags);
 		if (force_nonblock && ret == -EAGAIN) {
-			copy = kmalloc(sizeof(*copy), GFP_KERNEL);
-			if (!copy) {
-				ret = -ENOMEM;
-				goto out;
-			}
-			memcpy(&copy->msg, &io.msg, sizeof(copy->msg));
-			req->io = copy;
-			memcpy(&req->io->sqe, req->sqe, sizeof(*req->sqe));
-			req->sqe = &req->io->sqe;
-			return ret;
+			if (req->io)
+				return -EAGAIN;
+			if (io_alloc_async_ctx(req))
+				return -ENOMEM;
+			memcpy(&req->io->msg, &io.msg, sizeof(io.msg));
+			req->work.func = io_sendrecv_async;
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
 	}
 
 out:
+	if (!io_wq_current_is_worker() && kmsg && kmsg->iov != kmsg->fast_iov)
+		kfree(kmsg->iov);
 	io_cqring_add_event(req, ret);
 	if (ret < 0)
 		req_set_fail_links(req);
@@ -2116,10 +2248,12 @@ static int io_recvmsg_prep(struct io_kiocb *req, struct io_async_ctx *io)
 #endif
 }
 
-static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		      struct io_kiocb **nxt, bool force_nonblock)
+static int io_recvmsg(struct io_kiocb *req, struct io_kiocb **nxt,
+		      bool force_nonblock)
 {
 #if defined(CONFIG_NET)
+	const struct io_uring_sqe *sqe = req->sqe;
+	struct io_async_msghdr *kmsg = NULL;
 	struct socket *sock;
 	int ret;
 
@@ -2129,9 +2263,8 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	sock = sock_from_file(req->file, &ret);
 	if (sock) {
 		struct user_msghdr __user *msg;
-		struct io_async_ctx io, *copy;
+		struct io_async_ctx io;
 		struct sockaddr_storage addr;
-		struct msghdr *kmsg;
 		unsigned flags;
 
 		flags = READ_ONCE(sqe->msg_flags);
@@ -2143,34 +2276,37 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		msg = (struct user_msghdr __user *) (unsigned long)
 			READ_ONCE(sqe->addr);
 		if (req->io) {
-			kmsg = &req->io->msg.msg;
-			kmsg->msg_name = &addr;
+			kmsg = &req->io->msg;
+			kmsg->msg.msg_name = &addr;
+			/* if iov is set, it's allocated already */
+			if (!kmsg->iov)
+				kmsg->iov = kmsg->fast_iov;
+			kmsg->msg.msg_iter.iov = kmsg->iov;
 		} else {
-			kmsg = &io.msg.msg;
-			kmsg->msg_name = &addr;
+			kmsg = &io.msg;
+			kmsg->msg.msg_name = &addr;
 			ret = io_recvmsg_prep(req, &io);
 			if (ret)
 				goto out;
 		}
 
-		ret = __sys_recvmsg_sock(sock, kmsg, msg, io.msg.uaddr, flags);
+		ret = __sys_recvmsg_sock(sock, &kmsg->msg, msg, kmsg->uaddr, flags);
 		if (force_nonblock && ret == -EAGAIN) {
-			copy = kmalloc(sizeof(*copy), GFP_KERNEL);
-			if (!copy) {
-				ret = -ENOMEM;
-				goto out;
-			}
-			memcpy(copy, &io, sizeof(*copy));
-			req->io = copy;
-			memcpy(&req->io->sqe, req->sqe, sizeof(*req->sqe));
-			req->sqe = &req->io->sqe;
-			return ret;
+			if (req->io)
+				return -EAGAIN;
+			if (io_alloc_async_ctx(req))
+				return -ENOMEM;
+			memcpy(&req->io->msg, &io.msg, sizeof(io.msg));
+			req->work.func = io_sendrecv_async;
+			return -EAGAIN;
 		}
 		if (ret == -ERESTARTSYS)
 			ret = -EINTR;
 	}
 
 out:
+	if (!io_wq_current_is_worker() && kmsg && kmsg->iov != kmsg->fast_iov)
+		kfree(kmsg->iov);
 	io_cqring_add_event(req, ret);
 	if (ret < 0)
 		req_set_fail_links(req);
@@ -2181,30 +2317,44 @@ static int io_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 #endif
 }
 
-static int io_accept(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		     struct io_kiocb **nxt, bool force_nonblock)
+static int io_accept_prep(struct io_kiocb *req)
 {
 #if defined(CONFIG_NET)
-	struct sockaddr __user *addr;
-	int __user *addr_len;
-	unsigned file_flags;
-	int flags, ret;
+	const struct io_uring_sqe *sqe = req->sqe;
+	struct io_accept *accept = &req->accept;
+
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
 
 	if (unlikely(req->ctx->flags & (IORING_SETUP_IOPOLL|IORING_SETUP_SQPOLL)))
 		return -EINVAL;
 	if (sqe->ioprio || sqe->len || sqe->buf_index)
 		return -EINVAL;
 
-	addr = (struct sockaddr __user *) (unsigned long) READ_ONCE(sqe->addr);
-	addr_len = (int __user *) (unsigned long) READ_ONCE(sqe->addr2);
-	flags = READ_ONCE(sqe->accept_flags);
-	file_flags = force_nonblock ? O_NONBLOCK : 0;
+	accept->addr = (struct sockaddr __user *)
+				(unsigned long) READ_ONCE(sqe->addr);
+	accept->addr_len = (int __user *) (unsigned long) READ_ONCE(sqe->addr2);
+	accept->flags = READ_ONCE(sqe->accept_flags);
+	req->flags |= REQ_F_PREPPED;
+	return 0;
+#else
+	return -EOPNOTSUPP;
+#endif
+}
 
-	ret = __sys_accept4_file(req->file, file_flags, addr, addr_len, flags);
-	if (ret == -EAGAIN && force_nonblock) {
-		req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
+#if defined(CONFIG_NET)
+static int __io_accept(struct io_kiocb *req, struct io_kiocb **nxt,
+		       bool force_nonblock)
+{
+	struct io_accept *accept = &req->accept;
+	unsigned file_flags;
+	int ret;
+
+	file_flags = force_nonblock ? O_NONBLOCK : 0;
+	ret = __sys_accept4_file(req->file, file_flags, accept->addr,
+					accept->addr_len, accept->flags);
+	if (ret == -EAGAIN && force_nonblock)
 		return -EAGAIN;
-	}
 	if (ret == -ERESTARTSYS)
 		ret = -EINTR;
 	if (ret < 0)
@@ -2212,6 +2362,39 @@ static int io_accept(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	io_cqring_add_event(req, ret);
 	io_put_req_find_next(req, nxt);
 	return 0;
+}
+
+static void io_accept_finish(struct io_wq_work **workptr)
+{
+	struct io_kiocb *req = container_of(*workptr, struct io_kiocb, work);
+	struct io_kiocb *nxt = NULL;
+
+	if (io_req_cancelled(req))
+		return;
+	__io_accept(req, &nxt, false);
+	if (nxt)
+		*workptr = &nxt->work;
+}
+#endif
+
+static int io_accept(struct io_kiocb *req, struct io_kiocb **nxt,
+		     bool force_nonblock)
+{
+#if defined(CONFIG_NET)
+	int ret;
+
+	ret = io_accept_prep(req);
+	if (ret)
+		return ret;
+
+	ret = __io_accept(req, nxt, force_nonblock);
+	if (ret == -EAGAIN && force_nonblock) {
+		req->work.func = io_accept_finish;
+		req->work.flags |= IO_WQ_WORK_NEEDS_FILES;
+		io_put_req(req);
+		return -EAGAIN;
+	}
+	return 0;
 #else
 	return -EOPNOTSUPP;
 #endif
@@ -2232,10 +2415,11 @@ static int io_connect_prep(struct io_kiocb *req, struct io_async_ctx *io)
 #endif
 }
 
-static int io_connect(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		      struct io_kiocb **nxt, bool force_nonblock)
+static int io_connect(struct io_kiocb *req, struct io_kiocb **nxt,
+		      bool force_nonblock)
 {
 #if defined(CONFIG_NET)
+	const struct io_uring_sqe *sqe = req->sqe;
 	struct io_async_ctx __io, *io;
 	unsigned file_flags;
 	int addr_len, ret;
@@ -2260,15 +2444,13 @@ static int io_connect(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	ret = __sys_connect_file(req->file, &io->connect.address, addr_len,
 					file_flags);
 	if ((ret == -EAGAIN || ret == -EINPROGRESS) && force_nonblock) {
-		io = kmalloc(sizeof(*io), GFP_KERNEL);
-		if (!io) {
+		if (req->io)
+			return -EAGAIN;
+		if (io_alloc_async_ctx(req)) {
 			ret = -ENOMEM;
 			goto out;
 		}
-		memcpy(&io->connect, &__io.connect, sizeof(io->connect));
-		req->io = io;
-		memcpy(&io->sqe, req->sqe, sizeof(*req->sqe));
-		req->sqe = &io->sqe;
+		memcpy(&req->io->connect, &__io.connect, sizeof(__io.connect));
 		return -EAGAIN;
 	}
 	if (ret == -ERESTARTSYS)
@@ -2331,23 +2513,40 @@ static int io_poll_cancel(struct io_ring_ctx *ctx, __u64 sqe_addr)
 	return -ENOENT;
 }
 
+static int io_poll_remove_prep(struct io_kiocb *req)
+{
+	const struct io_uring_sqe *sqe = req->sqe;
+
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
+	    sqe->poll_events)
+		return -EINVAL;
+
+	req->poll.addr = READ_ONCE(sqe->addr);
+	req->flags |= REQ_F_PREPPED;
+	return 0;
+}
+
 /*
  * Find a running poll command that matches one specified in sqe->addr,
  * and remove it if found.
  */
-static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int io_poll_remove(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
+	u64 addr;
 	int ret;
 
-	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
-		return -EINVAL;
-	if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
-	    sqe->poll_events)
-		return -EINVAL;
+	ret = io_poll_remove_prep(req);
+	if (ret)
+		return ret;
 
+	addr = req->poll.addr;
 	spin_lock_irq(&ctx->completion_lock);
-	ret = io_poll_cancel(ctx, READ_ONCE(sqe->addr));
+	ret = io_poll_cancel(ctx, addr);
 	spin_unlock_irq(&ctx->completion_lock);
 
 	io_cqring_add_event(req, ret);
@@ -2482,16 +2681,14 @@ static void io_poll_req_insert(struct io_kiocb *req)
 	hlist_add_head(&req->hash_node, list);
 }
 
-static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		       struct io_kiocb **nxt)
+static int io_poll_add_prep(struct io_kiocb *req)
 {
+	const struct io_uring_sqe *sqe = req->sqe;
 	struct io_poll_iocb *poll = &req->poll;
-	struct io_ring_ctx *ctx = req->ctx;
-	struct io_poll_table ipt;
-	bool cancel = false;
-	__poll_t mask;
 	u16 events;
 
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
 	if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
@@ -2499,10 +2696,26 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (!poll->file)
 		return -EBADF;
 
-	req->io = NULL;
-	INIT_IO_WORK(&req->work, io_poll_complete_work);
+	req->flags |= REQ_F_PREPPED;
 	events = READ_ONCE(sqe->poll_events);
 	poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
+	return 0;
+}
+
+static int io_poll_add(struct io_kiocb *req, struct io_kiocb **nxt)
+{
+	struct io_poll_iocb *poll = &req->poll;
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_poll_table ipt;
+	bool cancel = false;
+	__poll_t mask;
+	int ret;
+
+	ret = io_poll_add_prep(req);
+	if (ret)
+		return ret;
+
+	INIT_IO_WORK(&req->work, io_poll_complete_work);
 	INIT_HLIST_NODE(&req->hash_node);
 
 	poll->head = NULL;
@@ -2573,7 +2786,7 @@ static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
 
 		/*
 		 * Adjust the reqs sequence before the current one because it
-		 * will consume a slot in the cq_ring and the the cq_tail
+		 * will consume a slot in the cq_ring and the cq_tail
 		 * pointer will be increased, otherwise other timeout reqs may
 		 * return in advance without waiting for enough wait_nr.
 		 */
@@ -2619,26 +2832,40 @@ static int io_timeout_cancel(struct io_ring_ctx *ctx, __u64 user_data)
 	return 0;
 }
 
+static int io_timeout_remove_prep(struct io_kiocb *req)
+{
+	const struct io_uring_sqe *sqe = req->sqe;
+
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->flags || sqe->ioprio || sqe->buf_index || sqe->len)
+		return -EINVAL;
+
+	req->timeout.addr = READ_ONCE(sqe->addr);
+	req->timeout.flags = READ_ONCE(sqe->timeout_flags);
+	if (req->timeout.flags)
+		return -EINVAL;
+
+	req->flags |= REQ_F_PREPPED;
+	return 0;
+}
+
 /*
  * Remove or update an existing timeout command
  */
-static int io_timeout_remove(struct io_kiocb *req,
-			     const struct io_uring_sqe *sqe)
+static int io_timeout_remove(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	unsigned flags;
 	int ret;
 
-	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
-		return -EINVAL;
-	if (sqe->flags || sqe->ioprio || sqe->buf_index || sqe->len)
-		return -EINVAL;
-	flags = READ_ONCE(sqe->timeout_flags);
-	if (flags)
-		return -EINVAL;
+	ret = io_timeout_remove_prep(req);
+	if (ret)
+		return ret;
 
 	spin_lock_irq(&ctx->completion_lock);
-	ret = io_timeout_cancel(ctx, READ_ONCE(sqe->addr));
+	ret = io_timeout_cancel(ctx, req->timeout.addr);
 
 	io_cqring_fill_event(req, ret);
 	io_commit_cqring(ctx);
@@ -2680,31 +2907,25 @@ static int io_timeout_prep(struct io_kiocb *req, struct io_async_ctx *io,
 		data->mode = HRTIMER_MODE_REL;
 
 	hrtimer_init(&data->timer, CLOCK_MONOTONIC, data->mode);
-	req->io = io;
 	return 0;
 }
 
-static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+static int io_timeout(struct io_kiocb *req)
 {
+	const struct io_uring_sqe *sqe = req->sqe;
 	unsigned count;
 	struct io_ring_ctx *ctx = req->ctx;
 	struct io_timeout_data *data;
-	struct io_async_ctx *io;
 	struct list_head *entry;
 	unsigned span = 0;
+	int ret;
 
-	io = req->io;
-	if (!io) {
-		int ret;
-
-		io = kmalloc(sizeof(*io), GFP_KERNEL);
-		if (!io)
+	if (!req->io) {
+		if (io_alloc_async_ctx(req))
 			return -ENOMEM;
-		ret = io_timeout_prep(req, io, false);
-		if (ret) {
-			kfree(io);
+		ret = io_timeout_prep(req, req->io, false);
+		if (ret)
 			return ret;
-		}
 	}
 	data = &req->io->timeout;
 
@@ -2831,38 +3052,79 @@ static void io_async_find_and_cancel(struct io_ring_ctx *ctx,
 	io_put_req_find_next(req, nxt);
 }
 
-static int io_async_cancel(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-			   struct io_kiocb **nxt)
+static int io_async_cancel_prep(struct io_kiocb *req)
 {
-	struct io_ring_ctx *ctx = req->ctx;
+	const struct io_uring_sqe *sqe = req->sqe;
 
-	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+	if (req->flags & REQ_F_PREPPED)
+		return 0;
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
 	if (sqe->flags || sqe->ioprio || sqe->off || sqe->len ||
 	    sqe->cancel_flags)
 		return -EINVAL;
 
-	io_async_find_and_cancel(ctx, req, READ_ONCE(sqe->addr), nxt, 0);
+	req->flags |= REQ_F_PREPPED;
+	req->cancel.addr = READ_ONCE(sqe->addr);
+	return 0;
+}
+
+static int io_async_cancel(struct io_kiocb *req, struct io_kiocb **nxt)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
+
+	ret = io_async_cancel_prep(req);
+	if (ret)
+		return ret;
+
+	io_async_find_and_cancel(ctx, req, req->cancel.addr, nxt, 0);
 	return 0;
 }
 
-static int io_req_defer_prep(struct io_kiocb *req, struct io_async_ctx *io)
+static int io_req_defer_prep(struct io_kiocb *req)
 {
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct io_async_ctx *io = req->io;
 	struct iov_iter iter;
-	ssize_t ret;
-
-	memcpy(&io->sqe, req->sqe, sizeof(io->sqe));
-	req->sqe = &io->sqe;
+	ssize_t ret = 0;
 
-	switch (io->sqe.opcode) {
+	switch (req->opcode) {
+	case IORING_OP_NOP:
+		break;
 	case IORING_OP_READV:
 	case IORING_OP_READ_FIXED:
+		/* ensure prep does right import */
+		req->io = NULL;
 		ret = io_read_prep(req, &iovec, &iter, true);
+		req->io = io;
+		if (ret < 0)
+			break;
+		io_req_map_rw(req, ret, iovec, inline_vecs, &iter);
+		ret = 0;
 		break;
 	case IORING_OP_WRITEV:
 	case IORING_OP_WRITE_FIXED:
+		/* ensure prep does right import */
+		req->io = NULL;
 		ret = io_write_prep(req, &iovec, &iter, true);
+		req->io = io;
+		if (ret < 0)
+			break;
+		io_req_map_rw(req, ret, iovec, inline_vecs, &iter);
+		ret = 0;
+		break;
+	case IORING_OP_POLL_ADD:
+		ret = io_poll_add_prep(req);
+		break;
+	case IORING_OP_POLL_REMOVE:
+		ret = io_poll_remove_prep(req);
+		break;
+	case IORING_OP_FSYNC:
+		ret = io_prep_fsync(req);
+		break;
+	case IORING_OP_SYNC_FILE_RANGE:
+		ret = io_prep_sfr(req);
 		break;
 	case IORING_OP_SENDMSG:
 		ret = io_sendmsg_prep(req, io);
@@ -2874,41 +3136,45 @@ static int io_req_defer_prep(struct io_kiocb *req, struct io_async_ctx *io)
 		ret = io_connect_prep(req, io);
 		break;
 	case IORING_OP_TIMEOUT:
-		return io_timeout_prep(req, io, false);
+		ret = io_timeout_prep(req, io, false);
+		break;
+	case IORING_OP_TIMEOUT_REMOVE:
+		ret = io_timeout_remove_prep(req);
+		break;
+	case IORING_OP_ASYNC_CANCEL:
+		ret = io_async_cancel_prep(req);
+		break;
 	case IORING_OP_LINK_TIMEOUT:
-		return io_timeout_prep(req, io, true);
+		ret = io_timeout_prep(req, io, true);
+		break;
+	case IORING_OP_ACCEPT:
+		ret = io_accept_prep(req);
+		break;
 	default:
-		req->io = io;
-		return 0;
+		printk_once(KERN_WARNING "io_uring: unhandled opcode %d\n",
+				req->opcode);
+		ret = -EINVAL;
+		break;
 	}
 
-	if (ret < 0)
-		return ret;
-
-	req->io = io;
-	io_req_map_io(req, ret, iovec, inline_vecs, &iter);
-	return 0;
+	return ret;
 }
 
 static int io_req_defer(struct io_kiocb *req)
 {
 	struct io_ring_ctx *ctx = req->ctx;
-	struct io_async_ctx *io;
 	int ret;
 
 	/* Still need defer if there is pending req in defer list. */
 	if (!req_need_defer(req) && list_empty(&ctx->defer_list))
 		return 0;
 
-	io = kmalloc(sizeof(*io), GFP_KERNEL);
-	if (!io)
+	if (io_alloc_async_ctx(req))
 		return -EAGAIN;
 
-	ret = io_req_defer_prep(req, io);
-	if (ret < 0) {
-		kfree(io);
+	ret = io_req_defer_prep(req);
+	if (ret < 0)
 		return ret;
-	}
 
 	spin_lock_irq(&ctx->completion_lock);
 	if (!req_need_defer(req) && list_empty(&ctx->defer_list)) {
@@ -2926,11 +3192,10 @@ __attribute__((nonnull))
 static int io_issue_sqe(struct io_kiocb *req, struct io_kiocb **nxt,
 			bool force_nonblock)
 {
-	int ret, opcode;
 	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
 
-	opcode = READ_ONCE(req->sqe->opcode);
-	switch (opcode) {
+	switch (req->opcode) {
 	case IORING_OP_NOP:
 		ret = io_nop(req);
 		break;
@@ -2951,37 +3216,37 @@ static int io_issue_sqe(struct io_kiocb *req, struct io_kiocb **nxt,
 		ret = io_write(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_FSYNC:
-		ret = io_fsync(req, req->sqe, nxt, force_nonblock);
+		ret = io_fsync(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_POLL_ADD:
-		ret = io_poll_add(req, req->sqe, nxt);
+		ret = io_poll_add(req, nxt);
 		break;
 	case IORING_OP_POLL_REMOVE:
-		ret = io_poll_remove(req, req->sqe);
+		ret = io_poll_remove(req);
 		break;
 	case IORING_OP_SYNC_FILE_RANGE:
-		ret = io_sync_file_range(req, req->sqe, nxt, force_nonblock);
+		ret = io_sync_file_range(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_SENDMSG:
-		ret = io_sendmsg(req, req->sqe, nxt, force_nonblock);
+		ret = io_sendmsg(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_RECVMSG:
-		ret = io_recvmsg(req, req->sqe, nxt, force_nonblock);
+		ret = io_recvmsg(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_TIMEOUT:
-		ret = io_timeout(req, req->sqe);
+		ret = io_timeout(req);
 		break;
 	case IORING_OP_TIMEOUT_REMOVE:
-		ret = io_timeout_remove(req, req->sqe);
+		ret = io_timeout_remove(req);
 		break;
 	case IORING_OP_ACCEPT:
-		ret = io_accept(req, req->sqe, nxt, force_nonblock);
+		ret = io_accept(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_CONNECT:
-		ret = io_connect(req, req->sqe, nxt, force_nonblock);
+		ret = io_connect(req, nxt, force_nonblock);
 		break;
 	case IORING_OP_ASYNC_CANCEL:
-		ret = io_async_cancel(req, req->sqe, nxt);
+		ret = io_async_cancel(req, nxt);
 		break;
 	default:
 		ret = -EINVAL;
@@ -3017,9 +3282,6 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
 	struct io_kiocb *nxt = NULL;
 	int ret = 0;
 
-	/* Ensure we clear previously set non-block flag */
-	req->rw.ki_flags &= ~IOCB_NOWAIT;
-
 	if (work->flags & IO_WQ_WORK_CANCEL)
 		ret = -ECANCELED;
 
@@ -3067,11 +3329,9 @@ static bool io_req_op_valid(int op)
 	return op >= IORING_OP_NOP && op < IORING_OP_LAST;
 }
 
-static int io_op_needs_file(const struct io_uring_sqe *sqe)
+static int io_req_needs_file(struct io_kiocb *req)
 {
-	int op = READ_ONCE(sqe->opcode);
-
-	switch (op) {
+	switch (req->opcode) {
 	case IORING_OP_NOP:
 	case IORING_OP_POLL_REMOVE:
 	case IORING_OP_TIMEOUT:
@@ -3080,7 +3340,7 @@ static int io_op_needs_file(const struct io_uring_sqe *sqe)
 	case IORING_OP_LINK_TIMEOUT:
 		return 0;
 	default:
-		if (io_req_op_valid(op))
+		if (io_req_op_valid(req->opcode))
 			return 1;
 		return -EINVAL;
 	}
@@ -3107,7 +3367,7 @@ static int io_req_set_file(struct io_submit_state *state, struct io_kiocb *req)
 	if (flags & IOSQE_IO_DRAIN)
 		req->flags |= REQ_F_IO_DRAIN;
 
-	ret = io_op_needs_file(req->sqe);
+	ret = io_req_needs_file(req);
 	if (ret <= 0)
 		return ret;
 
@@ -3227,7 +3487,7 @@ static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
 
 	nxt = list_first_entry_or_null(&req->link_list, struct io_kiocb,
 					link_list);
-	if (!nxt || nxt->sqe->opcode != IORING_OP_LINK_TIMEOUT)
+	if (!nxt || nxt->opcode != IORING_OP_LINK_TIMEOUT)
 		return NULL;
 
 	req->flags |= REQ_F_LINK_TIMEOUT;
@@ -3329,8 +3589,6 @@ static bool io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 	struct io_ring_ctx *ctx = req->ctx;
 	int ret;
 
-	req->user_data = req->sqe->user_data;
-
 	/* enforce forwards compatibility on users */
 	if (unlikely(req->sqe->flags & ~SQE_VALID_FLAGS)) {
 		ret = -EINVAL;
@@ -3354,7 +3612,6 @@ static bool io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 	 */
 	if (*link) {
 		struct io_kiocb *prev = *link;
-		struct io_async_ctx *io;
 
 		if (req->sqe->flags & IOSQE_IO_DRAIN)
 			(*link)->flags |= REQ_F_DRAIN_LINK | REQ_F_IO_DRAIN;
@@ -3362,15 +3619,13 @@ static bool io_submit_sqe(struct io_kiocb *req, struct io_submit_state *state,
 		if (req->sqe->flags & IOSQE_IO_HARDLINK)
 			req->flags |= REQ_F_HARDLINK;
 
-		io = kmalloc(sizeof(*io), GFP_KERNEL);
-		if (!io) {
+		if (io_alloc_async_ctx(req)) {
 			ret = -EAGAIN;
 			goto err_req;
 		}
 
-		ret = io_req_defer_prep(req, io);
+		ret = io_req_defer_prep(req);
 		if (ret) {
-			kfree(io);
 			/* fail even hard links since we don't submit */
 			prev->flags |= REQ_F_FAIL_LINK;
 			goto err_req;
@@ -3430,7 +3685,7 @@ static void io_commit_sqring(struct io_ring_ctx *ctx)
 }
 
 /*
- * Fetch an sqe, if one is available. Note that s->sqe will point to memory
+ * Fetch an sqe, if one is available. Note that req->sqe will point to memory
  * that is mapped by userspace. This means that care needs to be taken to
  * ensure that reads are stable, as we cannot rely on userspace always
  * being a good citizen. If members of the sqe are validated and then later
@@ -3465,6 +3720,8 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct io_kiocb *req)
 		 */
 		req->sequence = ctx->cached_sq_head;
 		req->sqe = &ctx->sq_sqes[head];
+		req->opcode = READ_ONCE(req->sqe->opcode);
+		req->user_data = READ_ONCE(req->sqe->user_data);
 		ctx->cached_sq_head++;
 		return true;
 	}
@@ -3510,7 +3767,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 			break;
 		}
 
-		if (io_sqe_needs_user(req->sqe) && !*mm) {
+		if (io_req_needs_user(req) && !*mm) {
 			mm_fault = mm_fault || !mmget_not_zero(ctx->sqo_mm);
 			if (!mm_fault) {
 				use_mm(ctx->sqo_mm);
@@ -3526,15 +3783,14 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 		req->has_user = *mm != NULL;
 		req->in_async = async;
 		req->needs_fixed_file = async;
-		trace_io_uring_submit_sqe(ctx, req->sqe->user_data,
-					  true, async);
+		trace_io_uring_submit_sqe(ctx, req->user_data, true, async);
 		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.
 		 */
-		if (!(sqe_flags & IOSQE_IO_LINK) && link) {
+		if (!(sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) && link) {
 			io_queue_link_head(link);
 			link = NULL;
 		}
@@ -3694,7 +3950,7 @@ static inline bool io_should_wake(struct io_wait_queue *iowq, bool noflush)
 	struct io_ring_ctx *ctx = iowq->ctx;
 
 	/*
-	 * Wake up if we have enough events, or if a timeout occured since we
+	 * 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.
 	 */
@@ -4884,6 +5140,9 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 		submitted = io_submit_sqes(ctx, to_submit, f.file, fd,
 					   &cur_mm, false);
 		mutex_unlock(&ctx->uring_lock);
+
+		if (submitted != to_submit)
+			goto out;
 	}
 	if (flags & IORING_ENTER_GETEVENTS) {
 		unsigned nr_events = 0;
@@ -4897,6 +5156,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 		}
 	}
 
+out:
 	percpu_ref_put(&ctx->refs);
 out_fput:
 	fdput(f);