Merge tag 'for-6.1/io_uring-2022-10-03' of git://git.kernel.dk/linux

Pull io_uring updates from Jens Axboe:

 - Add supported for more directly managed task_work running.

   This is beneficial for real world applications that end up issuing
   lots of system calls as part of handling work. Normal task_work will
   always execute as we transition in and out of the kernel, even for
   "unrelated" system calls. It's more efficient to defer the handling
   of io_uring's deferred work until the application wants it to be run,
   generally in batches.

   As part of ongoing work to write an io_uring network backend for
   Thrift, this has been shown to greatly improve performance. (Dylan)

 - Add IOPOLL support for passthrough (Kanchan)

 - Improvements and fixes to the send zero-copy support (Pavel)

 - Partial IO handling fixes (Pavel)

 - CQE ordering fixes around CQ ring overflow (Pavel)

 - Support sendto() for non-zc as well (Pavel)

 - Support sendmsg for zerocopy (Pavel)

 - Networking iov_iter fix (Stefan)

 - Misc fixes and cleanups (Pavel, me)

* tag 'for-6.1/io_uring-2022-10-03' of git://git.kernel.dk/linux: (56 commits)
  io_uring/net: fix notif cqe reordering
  io_uring/net: don't update msg_name if not provided
  io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL
  io_uring/rw: defer fsnotify calls to task context
  io_uring/net: fix fast_iov assignment in io_setup_async_msg()
  io_uring/net: fix non-zc send with address
  io_uring/net: don't skip notifs for failed requests
  io_uring/rw: don't lose short results on io_setup_async_rw()
  io_uring/rw: fix unexpected link breakage
  io_uring/net: fix cleanup double free free_iov init
  io_uring: fix CQE reordering
  io_uring/net: fix UAF in io_sendrecv_fail()
  selftest/net: adjust io_uring sendzc notif handling
  io_uring: ensure local task_work marks task as running
  io_uring/net: zerocopy sendmsg
  io_uring/net: combine fail handlers
  io_uring/net: rename io_sendzc()
  io_uring/net: support non-zerocopy sendto
  io_uring/net: refactor io_setup_async_addr
  io_uring/net: don't lose partial send_zc on fail
  ...

Author: torvalds

block/blk-mq.c

@@ -1233,7 +1233,7 @@ static void blk_end_sync_rq(struct request *rq, blk_status_t ret)
 	complete(&wait->done);
 }
 
-static bool blk_rq_is_poll(struct request *rq)
+bool blk_rq_is_poll(struct request *rq)
 {
 	if (!rq->mq_hctx)
 		return false;
@@ -1243,6 +1243,7 @@ static bool blk_rq_is_poll(struct request *rq)
 		return false;
 	return true;
 }
+EXPORT_SYMBOL_GPL(blk_rq_is_poll);
 
 static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
 {

drivers/nvme/host/core.c

@@ -3976,6 +3976,7 @@ static const struct file_operations nvme_ns_chr_fops = {
 	.unlocked_ioctl	= nvme_ns_chr_ioctl,
 	.compat_ioctl	= compat_ptr_ioctl,
 	.uring_cmd	= nvme_ns_chr_uring_cmd,
+	.uring_cmd_iopoll = nvme_ns_chr_uring_cmd_iopoll,
 };
 
 static int nvme_add_ns_cdev(struct nvme_ns *ns)

drivers/nvme/host/ioctl.c

@@ -391,11 +391,19 @@ static void nvme_uring_cmd_end_io(struct request *req, blk_status_t err)
 	struct nvme_uring_cmd_pdu *pdu = nvme_uring_cmd_pdu(ioucmd);
 	/* extract bio before reusing the same field for request */
 	struct bio *bio = pdu->bio;
+	void *cookie = READ_ONCE(ioucmd->cookie);
 
 	pdu->req = req;
 	req->bio = bio;
-	/* this takes care of moving rest of completion-work to task context */
-	io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
+
+	/*
+	 * For iopoll, complete it directly.
+	 * Otherwise, move the completion to task work.
+	 */
+	if (cookie != NULL && blk_rq_is_poll(req))
+		nvme_uring_task_cb(ioucmd);
+	else
+		io_uring_cmd_complete_in_task(ioucmd, nvme_uring_task_cb);
 }
 
 static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
@@ -445,7 +453,10 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 		rq_flags = REQ_NOWAIT;
 		blk_flags = BLK_MQ_REQ_NOWAIT;
 	}
+	if (issue_flags & IO_URING_F_IOPOLL)
+		rq_flags |= REQ_POLLED;
 
+retry:
 	req = nvme_alloc_user_request(q, &c, nvme_to_user_ptr(d.addr),
 			d.data_len, nvme_to_user_ptr(d.metadata),
 			d.metadata_len, 0, &meta, d.timeout_ms ?
@@ -456,6 +467,17 @@ static int nvme_uring_cmd_io(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
 	req->end_io = nvme_uring_cmd_end_io;
 	req->end_io_data = ioucmd;
 
+	if (issue_flags & IO_URING_F_IOPOLL && rq_flags & REQ_POLLED) {
+		if (unlikely(!req->bio)) {
+			/* we can't poll this, so alloc regular req instead */
+			blk_mq_free_request(req);
+			rq_flags &= ~REQ_POLLED;
+			goto retry;
+		} else {
+			WRITE_ONCE(ioucmd->cookie, req->bio);
+			req->bio->bi_opf |= REQ_POLLED;
+		}
+	}
 	/* to free bio on completion, as req->bio will be null at that time */
 	pdu->bio = req->bio;
 	pdu->meta = meta;
@@ -559,9 +581,6 @@ long nvme_ns_chr_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 static int nvme_uring_cmd_checks(unsigned int issue_flags)
 {
-	/* IOPOLL not supported yet */
-	if (issue_flags & IO_URING_F_IOPOLL)
-		return -EOPNOTSUPP;
 
 	/* NVMe passthrough requires big SQE/CQE support */
 	if ((issue_flags & (IO_URING_F_SQE128|IO_URING_F_CQE32)) !=
@@ -604,6 +623,25 @@ int nvme_ns_chr_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
 	return nvme_ns_uring_cmd(ns, ioucmd, issue_flags);
 }
 
+int nvme_ns_chr_uring_cmd_iopoll(struct io_uring_cmd *ioucmd,
+				 struct io_comp_batch *iob,
+				 unsigned int poll_flags)
+{
+	struct bio *bio;
+	int ret = 0;
+	struct nvme_ns *ns;
+	struct request_queue *q;
+
+	rcu_read_lock();
+	bio = READ_ONCE(ioucmd->cookie);
+	ns = container_of(file_inode(ioucmd->file)->i_cdev,
+			struct nvme_ns, cdev);
+	q = ns->queue;
+	if (test_bit(QUEUE_FLAG_POLL, &q->queue_flags) && bio && bio->bi_bdev)
+		ret = bio_poll(bio, iob, poll_flags);
+	rcu_read_unlock();
+	return ret;
+}
 #ifdef CONFIG_NVME_MULTIPATH
 static int nvme_ns_head_ctrl_ioctl(struct nvme_ns *ns, unsigned int cmd,
 		void __user *argp, struct nvme_ns_head *head, int srcu_idx)
@@ -685,13 +723,42 @@ int nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,
 	srcu_read_unlock(&head->srcu, srcu_idx);
 	return ret;
 }
+
+int nvme_ns_head_chr_uring_cmd_iopoll(struct io_uring_cmd *ioucmd,
+				      struct io_comp_batch *iob,
+				      unsigned int poll_flags)
+{
+	struct cdev *cdev = file_inode(ioucmd->file)->i_cdev;
+	struct nvme_ns_head *head = container_of(cdev, struct nvme_ns_head, cdev);
+	int srcu_idx = srcu_read_lock(&head->srcu);
+	struct nvme_ns *ns = nvme_find_path(head);
+	struct bio *bio;
+	int ret = 0;
+	struct request_queue *q;
+
+	if (ns) {
+		rcu_read_lock();
+		bio = READ_ONCE(ioucmd->cookie);
+		q = ns->queue;
+		if (test_bit(QUEUE_FLAG_POLL, &q->queue_flags) && bio
+				&& bio->bi_bdev)
+			ret = bio_poll(bio, iob, poll_flags);
+		rcu_read_unlock();
+	}
+	srcu_read_unlock(&head->srcu, srcu_idx);
+	return ret;
+}
 #endif /* CONFIG_NVME_MULTIPATH */
 
 int nvme_dev_uring_cmd(struct io_uring_cmd *ioucmd, unsigned int issue_flags)
 {
 	struct nvme_ctrl *ctrl = ioucmd->file->private_data;
 	int ret;
 
+	/* IOPOLL not supported yet */
+	if (issue_flags & IO_URING_F_IOPOLL)
+		return -EOPNOTSUPP;
+
 	ret = nvme_uring_cmd_checks(issue_flags);
 	if (ret)
 		return ret;

drivers/nvme/host/multipath.c

@@ -439,6 +439,7 @@ static const struct file_operations nvme_ns_head_chr_fops = {
 	.unlocked_ioctl	= nvme_ns_head_chr_ioctl,
 	.compat_ioctl	= compat_ptr_ioctl,
 	.uring_cmd	= nvme_ns_head_chr_uring_cmd,
+	.uring_cmd_iopoll = nvme_ns_head_chr_uring_cmd_iopoll,
 };
 
 static int nvme_add_ns_head_cdev(struct nvme_ns_head *head)

drivers/nvme/host/nvme.h

@@ -821,6 +821,10 @@ long nvme_ns_head_chr_ioctl(struct file *file, unsigned int cmd,
 		unsigned long arg);
 long nvme_dev_ioctl(struct file *file, unsigned int cmd,
 		unsigned long arg);
+int nvme_ns_chr_uring_cmd_iopoll(struct io_uring_cmd *ioucmd,
+		struct io_comp_batch *iob, unsigned int poll_flags);
+int nvme_ns_head_chr_uring_cmd_iopoll(struct io_uring_cmd *ioucmd,
+		struct io_comp_batch *iob, unsigned int poll_flags);
 int nvme_ns_chr_uring_cmd(struct io_uring_cmd *ioucmd,
 		unsigned int issue_flags);
 int nvme_ns_head_chr_uring_cmd(struct io_uring_cmd *ioucmd,

fs/eventfd.c

@@ -69,17 +69,17 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
 	 * it returns false, the eventfd_signal() call should be deferred to a
 	 * safe context.
 	 */
-	if (WARN_ON_ONCE(current->in_eventfd_signal))
+	if (WARN_ON_ONCE(current->in_eventfd))
 		return 0;
 
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
-	current->in_eventfd_signal = 1;
+	current->in_eventfd = 1;
 	if (ULLONG_MAX - ctx->count < n)
 		n = ULLONG_MAX - ctx->count;
 	ctx->count += n;
 	if (waitqueue_active(&ctx->wqh))
 		wake_up_locked_poll(&ctx->wqh, EPOLLIN);
-	current->in_eventfd_signal = 0;
+	current->in_eventfd = 0;
 	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
 
 	return n;
@@ -253,8 +253,10 @@ static ssize_t eventfd_read(struct kiocb *iocb, struct iov_iter *to)
 		__set_current_state(TASK_RUNNING);
 	}
 	eventfd_ctx_do_read(ctx, &ucnt);
+	current->in_eventfd = 1;
 	if (waitqueue_active(&ctx->wqh))
 		wake_up_locked_poll(&ctx->wqh, EPOLLOUT);
+	current->in_eventfd = 0;
 	spin_unlock_irq(&ctx->wqh.lock);
 	if (unlikely(copy_to_iter(&ucnt, sizeof(ucnt), to) != sizeof(ucnt)))
 		return -EFAULT;
@@ -301,8 +303,10 @@ static ssize_t eventfd_write(struct file *file, const char __user *buf, size_t c
 	}
 	if (likely(res > 0)) {
 		ctx->count += ucnt;
+		current->in_eventfd = 1;
 		if (waitqueue_active(&ctx->wqh))
 			wake_up_locked_poll(&ctx->wqh, EPOLLIN);
+		current->in_eventfd = 0;
 	}
 	spin_unlock_irq(&ctx->wqh.lock);
 

include/linux/blk-mq.h

@@ -980,6 +980,7 @@ int blk_rq_map_kern(struct request_queue *, struct request *, void *,
 int blk_rq_append_bio(struct request *rq, struct bio *bio);
 void blk_execute_rq_nowait(struct request *rq, bool at_head);
 blk_status_t blk_execute_rq(struct request *rq, bool at_head);
+bool blk_rq_is_poll(struct request *rq);
 
 struct req_iterator {
 	struct bvec_iter iter;

include/linux/eventfd.h

@@ -46,7 +46,7 @@ void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
 
 static inline bool eventfd_signal_allowed(void)
 {
-	return !current->in_eventfd_signal;
+	return !current->in_eventfd;
 }
 
 #else /* CONFIG_EVENTFD */

include/linux/fs.h

@@ -2133,6 +2133,8 @@ struct file_operations {
 				   loff_t len, unsigned int remap_flags);
 	int (*fadvise)(struct file *, loff_t, loff_t, int);
 	int (*uring_cmd)(struct io_uring_cmd *ioucmd, unsigned int issue_flags);
+	int (*uring_cmd_iopoll)(struct io_uring_cmd *, struct io_comp_batch *,
+				unsigned int poll_flags);
 } __randomize_layout;
 
 struct inode_operations {

include/linux/io_uring.h

@@ -20,8 +20,12 @@ enum io_uring_cmd_flags {
 struct io_uring_cmd {
 	struct file	*file;
 	const void	*cmd;
-	/* callback to defer completions to task context */
-	void (*task_work_cb)(struct io_uring_cmd *cmd);
+	union {
+		/* callback to defer completions to task context */
+		void (*task_work_cb)(struct io_uring_cmd *cmd);
+		/* used for polled completion */
+		void *cookie;
+	};
 	u32		cmd_op;
 	u32		pad;
 	u8		pdu[32]; /* available inline for free use */