Commit c090c8ab authored by Bernd Schubert's avatar Bernd Schubert Committed by Miklos Szeredi
Browse files

fuse: Add io-uring sqe commit and fetch support 



This adds support for fuse request completion through ring SQEs
(FUSE_URING_CMD_COMMIT_AND_FETCH handling). After committing
the ring entry it becomes available for new fuse requests.
Handling of requests through the ring (SQE/CQE handling)
is complete now.

Fuse request data are copied through the mmaped ring buffer,
there is no support for any zero copy yet.

Signed-off-by: default avatarBernd Schubert <bschubert@ddn.com>
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com> # io_uring
Reviewed-by: default avatarLuis Henriques <luis@igalia.com>
Signed-off-by: default avatarMiklos Szeredi <mszeredi@redhat.com>
parent 38213365

fs/fuse/dev_uring.c

+441 −0
Original line number Diff line number Diff line
@@ -24,6 +24,17 @@ bool fuse_uring_enabled(void) 
	return enable_uring;

}



static void fuse_uring_req_end(struct fuse_ring_ent *ent, struct fuse_req *req,

			       int error)

{

	ent->fuse_req = NULL;

	if (error)

		req->out.h.error = error;



	clear_bit(FR_SENT, &req->flags);

	fuse_request_end(req);

}



void fuse_uring_destruct(struct fuse_conn *fc)

{

	struct fuse_ring *ring = fc->ring;
@@ -39,8 +50,11 @@ void fuse_uring_destruct(struct fuse_conn *fc) 
			continue;



		WARN_ON(!list_empty(&queue->ent_avail_queue));

		WARN_ON(!list_empty(&queue->ent_w_req_queue));

		WARN_ON(!list_empty(&queue->ent_commit_queue));

		WARN_ON(!list_empty(&queue->ent_in_userspace));



		kfree(queue->fpq.processing);

		kfree(queue);

		ring->queues[qid] = NULL;

	}
@@ -99,20 +113,34 @@ static struct fuse_ring_queue *fuse_uring_create_queue(struct fuse_ring *ring, 
{

	struct fuse_conn *fc = ring->fc;

	struct fuse_ring_queue *queue;

	struct list_head *pq;



	queue = kzalloc(sizeof(*queue), GFP_KERNEL_ACCOUNT);

	if (!queue)

		return NULL;

	pq = kcalloc(FUSE_PQ_HASH_SIZE, sizeof(struct list_head), GFP_KERNEL);

	if (!pq) {

		kfree(queue);

		return NULL;

	}



	queue->qid = qid;

	queue->ring = ring;

	spin_lock_init(&queue->lock);



	INIT_LIST_HEAD(&queue->ent_avail_queue);

	INIT_LIST_HEAD(&queue->ent_commit_queue);

	INIT_LIST_HEAD(&queue->ent_w_req_queue);

	INIT_LIST_HEAD(&queue->ent_in_userspace);

	INIT_LIST_HEAD(&queue->fuse_req_queue);



	queue->fpq.processing = pq;

	fuse_pqueue_init(&queue->fpq);



	spin_lock(&fc->lock);

	if (ring->queues[qid]) {

		spin_unlock(&fc->lock);

		kfree(queue->fpq.processing);

		kfree(queue);

		return ring->queues[qid];

	}
@@ -126,6 +154,214 @@ static struct fuse_ring_queue *fuse_uring_create_queue(struct fuse_ring *ring, 
	return queue;

}



/*

 * Checks for errors and stores it into the request

 */

static int fuse_uring_out_header_has_err(struct fuse_out_header *oh,

					 struct fuse_req *req,

					 struct fuse_conn *fc)

{

	int err;



	err = -EINVAL;

	if (oh->unique == 0) {

		/* Not supported through io-uring yet */

		pr_warn_once("notify through fuse-io-uring not supported\n");

		goto err;

	}



	if (oh->error <= -ERESTARTSYS || oh->error > 0)

		goto err;



	if (oh->error) {

		err = oh->error;

		goto err;

	}



	err = -ENOENT;

	if ((oh->unique & ~FUSE_INT_REQ_BIT) != req->in.h.unique) {

		pr_warn_ratelimited("unique mismatch, expected: %llu got %llu\n",

				    req->in.h.unique,

				    oh->unique & ~FUSE_INT_REQ_BIT);

		goto err;

	}



	/*

	 * Is it an interrupt reply ID?

	 * XXX: Not supported through fuse-io-uring yet, it should not even

	 *      find the request - should not happen.

	 */

	WARN_ON_ONCE(oh->unique & FUSE_INT_REQ_BIT);



	err = 0;

err:

	return err;

}



static int fuse_uring_copy_from_ring(struct fuse_ring *ring,

				     struct fuse_req *req,

				     struct fuse_ring_ent *ent)

{

	struct fuse_copy_state cs;

	struct fuse_args *args = req->args;

	struct iov_iter iter;

	int err;

	struct fuse_uring_ent_in_out ring_in_out;



	err = copy_from_user(&ring_in_out, &ent->headers->ring_ent_in_out,

			     sizeof(ring_in_out));

	if (err)

		return -EFAULT;



	err = import_ubuf(ITER_SOURCE, ent->payload, ring->max_payload_sz,

			  &iter);

	if (err)

		return err;



	fuse_copy_init(&cs, 0, &iter);

	cs.is_uring = 1;

	cs.req = req;



	return fuse_copy_out_args(&cs, args, ring_in_out.payload_sz);

}



 /*

  * Copy data from the req to the ring buffer

  */

static int fuse_uring_args_to_ring(struct fuse_ring *ring, struct fuse_req *req,

				   struct fuse_ring_ent *ent)

{

	struct fuse_copy_state cs;

	struct fuse_args *args = req->args;

	struct fuse_in_arg *in_args = args->in_args;

	int num_args = args->in_numargs;

	int err;

	struct iov_iter iter;

	struct fuse_uring_ent_in_out ent_in_out = {

		.flags = 0,

		.commit_id = req->in.h.unique,

	};



	err = import_ubuf(ITER_DEST, ent->payload, ring->max_payload_sz, &iter);

	if (err) {

		pr_info_ratelimited("fuse: Import of user buffer failed\n");

		return err;

	}



	fuse_copy_init(&cs, 1, &iter);

	cs.is_uring = 1;

	cs.req = req;



	if (num_args > 0) {

		/*

		 * Expectation is that the first argument is the per op header.

		 * Some op code have that as zero size.

		 */

		if (args->in_args[0].size > 0) {

			err = copy_to_user(&ent->headers->op_in, in_args->value,

					   in_args->size);

			if (err) {

				pr_info_ratelimited(

					"Copying the header failed.\n");

				return -EFAULT;

			}

		}

		in_args++;

		num_args--;

	}



	/* copy the payload */

	err = fuse_copy_args(&cs, num_args, args->in_pages,

			     (struct fuse_arg *)in_args, 0);

	if (err) {

		pr_info_ratelimited("%s fuse_copy_args failed\n", __func__);

		return err;

	}



	ent_in_out.payload_sz = cs.ring.copied_sz;

	err = copy_to_user(&ent->headers->ring_ent_in_out, &ent_in_out,

			   sizeof(ent_in_out));

	return err ? -EFAULT : 0;

}



static int fuse_uring_copy_to_ring(struct fuse_ring_ent *ent,

				   struct fuse_req *req)

{

	struct fuse_ring_queue *queue = ent->queue;

	struct fuse_ring *ring = queue->ring;

	int err;



	err = -EIO;

	if (WARN_ON(ent->state != FRRS_FUSE_REQ)) {

		pr_err("qid=%d ring-req=%p invalid state %d on send\n",

		       queue->qid, ent, ent->state);

		return err;

	}



	err = -EINVAL;

	if (WARN_ON(req->in.h.unique == 0))

		return err;



	/* copy the request */

	err = fuse_uring_args_to_ring(ring, req, ent);

	if (unlikely(err)) {

		pr_info_ratelimited("Copy to ring failed: %d\n", err);

		return err;

	}



	/* copy fuse_in_header */

	err = copy_to_user(&ent->headers->in_out, &req->in.h,

			   sizeof(req->in.h));

	if (err) {

		err = -EFAULT;

		return err;

	}



	return 0;

}



static int fuse_uring_prepare_send(struct fuse_ring_ent *ent,

				   struct fuse_req *req)

{

	int err;



	err = fuse_uring_copy_to_ring(ent, req);

	if (!err)

		set_bit(FR_SENT, &req->flags);

	else

		fuse_uring_req_end(ent, req, err);



	return err;

}



/*

 * Write data to the ring buffer and send the request to userspace,

 * userspace will read it

 * This is comparable with classical read(/dev/fuse)

 */

static int fuse_uring_send_next_to_ring(struct fuse_ring_ent *ent,

					struct fuse_req *req,

					unsigned int issue_flags)

{

	struct fuse_ring_queue *queue = ent->queue;

	int err;

	struct io_uring_cmd *cmd;



	err = fuse_uring_prepare_send(ent, req);

	if (err)

		return err;



	spin_lock(&queue->lock);

	cmd = ent->cmd;

	ent->cmd = NULL;

	ent->state = FRRS_USERSPACE;

	list_move(&ent->list, &queue->ent_in_userspace);

	spin_unlock(&queue->lock);



	io_uring_cmd_done(cmd, 0, 0, issue_flags);

	return 0;

}



/*

 * Make a ring entry available for fuse_req assignment

 */
@@ -137,6 +373,203 @@ static void fuse_uring_ent_avail(struct fuse_ring_ent *ent, 
	ent->state = FRRS_AVAILABLE;

}



/* Used to find the request on SQE commit */

static void fuse_uring_add_to_pq(struct fuse_ring_ent *ent,

				 struct fuse_req *req)

{

	struct fuse_ring_queue *queue = ent->queue;

	struct fuse_pqueue *fpq = &queue->fpq;

	unsigned int hash;



	req->ring_entry = ent;

	hash = fuse_req_hash(req->in.h.unique);

	list_move_tail(&req->list, &fpq->processing[hash]);

}



/*

 * Assign a fuse queue entry to the given entry

 */

static void fuse_uring_add_req_to_ring_ent(struct fuse_ring_ent *ent,

					   struct fuse_req *req)

{

	struct fuse_ring_queue *queue = ent->queue;

	struct fuse_conn *fc = req->fm->fc;

	struct fuse_iqueue *fiq = &fc->iq;



	lockdep_assert_held(&queue->lock);



	if (WARN_ON_ONCE(ent->state != FRRS_AVAILABLE &&

			 ent->state != FRRS_COMMIT)) {

		pr_warn("%s qid=%d state=%d\n", __func__, ent->queue->qid,

			ent->state);

	}



	spin_lock(&fiq->lock);

	clear_bit(FR_PENDING, &req->flags);

	spin_unlock(&fiq->lock);

	ent->fuse_req = req;

	ent->state = FRRS_FUSE_REQ;

	list_move(&ent->list, &queue->ent_w_req_queue);

	fuse_uring_add_to_pq(ent, req);

}



/* Fetch the next fuse request if available */

static struct fuse_req *fuse_uring_ent_assign_req(struct fuse_ring_ent *ent)

	__must_hold(&queue->lock)

{

	struct fuse_req *req;

	struct fuse_ring_queue *queue = ent->queue;

	struct list_head *req_queue = &queue->fuse_req_queue;



	lockdep_assert_held(&queue->lock);



	/* get and assign the next entry while it is still holding the lock */

	req = list_first_entry_or_null(req_queue, struct fuse_req, list);

	if (req)

		fuse_uring_add_req_to_ring_ent(ent, req);



	return req;

}



/*

 * Read data from the ring buffer, which user space has written to

 * This is comparible with handling of classical write(/dev/fuse).

 * Also make the ring request available again for new fuse requests.

 */

static void fuse_uring_commit(struct fuse_ring_ent *ent, struct fuse_req *req,

			      unsigned int issue_flags)

{

	struct fuse_ring *ring = ent->queue->ring;

	struct fuse_conn *fc = ring->fc;

	ssize_t err = 0;



	err = copy_from_user(&req->out.h, &ent->headers->in_out,

			     sizeof(req->out.h));

	if (err) {

		req->out.h.error = -EFAULT;

		goto out;

	}



	err = fuse_uring_out_header_has_err(&req->out.h, req, fc);

	if (err) {

		/* req->out.h.error already set */

		goto out;

	}



	err = fuse_uring_copy_from_ring(ring, req, ent);

out:

	fuse_uring_req_end(ent, req, err);

}



/*

 * Get the next fuse req and send it

 */

static void fuse_uring_next_fuse_req(struct fuse_ring_ent *ent,

				     struct fuse_ring_queue *queue,

				     unsigned int issue_flags)

{

	int err;

	struct fuse_req *req;



retry:

	spin_lock(&queue->lock);

	fuse_uring_ent_avail(ent, queue);

	req = fuse_uring_ent_assign_req(ent);

	spin_unlock(&queue->lock);



	if (req) {

		err = fuse_uring_send_next_to_ring(ent, req, issue_flags);

		if (err)

			goto retry;

	}

}



static int fuse_ring_ent_set_commit(struct fuse_ring_ent *ent)

{

	struct fuse_ring_queue *queue = ent->queue;



	lockdep_assert_held(&queue->lock);



	if (WARN_ON_ONCE(ent->state != FRRS_USERSPACE))

		return -EIO;



	ent->state = FRRS_COMMIT;

	list_move(&ent->list, &queue->ent_commit_queue);



	return 0;

}



/* FUSE_URING_CMD_COMMIT_AND_FETCH handler */

static int fuse_uring_commit_fetch(struct io_uring_cmd *cmd, int issue_flags,

				   struct fuse_conn *fc)

{

	const struct fuse_uring_cmd_req *cmd_req = io_uring_sqe_cmd(cmd->sqe);

	struct fuse_ring_ent *ent;

	int err;

	struct fuse_ring *ring = fc->ring;

	struct fuse_ring_queue *queue;

	uint64_t commit_id = READ_ONCE(cmd_req->commit_id);

	unsigned int qid = READ_ONCE(cmd_req->qid);

	struct fuse_pqueue *fpq;

	struct fuse_req *req;



	err = -ENOTCONN;

	if (!ring)

		return err;



	if (qid >= ring->nr_queues)

		return -EINVAL;



	queue = ring->queues[qid];

	if (!queue)

		return err;

	fpq = &queue->fpq;



	spin_lock(&queue->lock);

	/* Find a request based on the unique ID of the fuse request

	 * This should get revised, as it needs a hash calculation and list

	 * search. And full struct fuse_pqueue is needed (memory overhead).

	 * As well as the link from req to ring_ent.

	 */

	req = fuse_request_find(fpq, commit_id);

	err = -ENOENT;

	if (!req) {

		pr_info("qid=%d commit_id %llu not found\n", queue->qid,

			commit_id);

		spin_unlock(&queue->lock);

		return err;

	}

	list_del_init(&req->list);

	ent = req->ring_entry;

	req->ring_entry = NULL;



	err = fuse_ring_ent_set_commit(ent);

	if (err != 0) {

		pr_info_ratelimited("qid=%d commit_id %llu state %d",

				    queue->qid, commit_id, ent->state);

		spin_unlock(&queue->lock);

		req->out.h.error = err;

		clear_bit(FR_SENT, &req->flags);

		fuse_request_end(req);

		return err;

	}



	ent->cmd = cmd;

	spin_unlock(&queue->lock);



	/* without the queue lock, as other locks are taken */

	fuse_uring_commit(ent, req, issue_flags);



	/*

	 * Fetching the next request is absolutely required as queued

	 * fuse requests would otherwise not get processed - committing

	 * and fetching is done in one step vs legacy fuse, which has separated

	 * read (fetch request) and write (commit result).

	 */

	fuse_uring_next_fuse_req(ent, queue, issue_flags);

	return 0;

}



/*

 * fuse_uring_req_fetch command handling

 */
@@ -318,6 +751,14 @@ int __maybe_unused fuse_uring_cmd(struct io_uring_cmd *cmd, 
			return err;

		}

		break;

	case FUSE_IO_URING_CMD_COMMIT_AND_FETCH:

		err = fuse_uring_commit_fetch(cmd, issue_flags, fc);

		if (err) {

			pr_info_once("FUSE_IO_URING_COMMIT_AND_FETCH failed err=%d\n",

				     err);

			return err;

		}

		break;

	default:

		return -EINVAL;

	}

fs/fuse/dev_uring_i.h

+12 −0
Original line number Diff line number Diff line
@@ -20,6 +20,9 @@ enum fuse_ring_req_state { 
	/* The ring entry is waiting for new fuse requests */

	FRRS_AVAILABLE,



	/* The ring entry got assigned a fuse req */

	FRRS_FUSE_REQ,



	/* The ring entry is in or on the way to user space */

	FRRS_USERSPACE,

};
@@ -67,7 +70,16 @@ struct fuse_ring_queue { 
	 * entries in the process of being committed or in the process

	 * to be sent to userspace

	 */

	struct list_head ent_w_req_queue;

	struct list_head ent_commit_queue;



	/* entries in userspace */

	struct list_head ent_in_userspace;



	/* fuse requests waiting for an entry slot */

	struct list_head fuse_req_queue;



	struct fuse_pqueue fpq;

};



/**

fs/fuse/fuse_i.h

+4 −0
Original line number Diff line number Diff line
@@ -438,6 +438,10 @@ struct fuse_req { 


	/** fuse_mount this request belongs to */

	struct fuse_mount *fm;



#ifdef CONFIG_FUSE_IO_URING

	void *ring_entry;

#endif

};



struct fuse_iqueue;