Re: [PATCH RFC v7 09/16] fuse: {uring} Add uring sqe commit and fetch support

Pavel Begunkov
2024-12-03T13:46:51Z

On 11/27/24 13:40, Bernd Schubert wrote:
> This adds support for fuse request completion through ring SQEs
> (FUSE_URING_REQ_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: Bernd Schubert <bschubert@ddn.com>
> ---
...
> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
> index af9c5f116ba1dcf6c01d0359d1a06491c92c32f9..7bb07f5ba436fcb89537f0821f08a7167da52902 100644
> --- a/fs/fuse/dev_uring.c
> +++ b/fs/fuse/dev_uring.c
> @@ -24,6 +24,19 @@ bool fuse_uring_enabled(void)
...
> +/*
> + * 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 *ring_ent)
> +{
> + int err = 0;
> + struct fuse_ring_queue *queue = ring_ent->queue;
> +
> + err = fuse_uring_prepare_send(ring_ent);
> + if (err)
> + goto err;
> +
> + spin_lock(&queue->lock);
> + ring_ent->state = FRRS_USERSPACE;
> + list_move(&ring_ent->list, &queue->ent_in_userspace);
> + spin_unlock(&queue->lock);
> +
> + io_uring_cmd_complete_in_task(ring_ent->cmd,
> + fuse_uring_async_send_to_ring);

Just io_uring_cmd_done should be enough.

io_uring_cmd_done(cmd, 0, 0, issue_flags);

> + return 0;
> +
> +err:
> + return err;
> +}
> +
> /*
> * Make a ring entry available for fuse_req assignment
> */
> @@ -148,6 +385,189 @@ static void fuse_uring_ent_avail(struct fuse_ring_ent *ring_ent,
> ring_ent->state = FRRS_WAIT;
> }
>
...
> +
> +/* FUSE_URING_REQ_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);

Same comment about checking SQE128, fuse_uring_cmd() sounds like a good
place for it.

> + struct fuse_ring_ent *ring_ent;
> + int err;
> + struct fuse_ring *ring = fc->ring;
> + struct fuse_ring_queue *queue;
> + uint64_t commit_id = cmd_req->commit_id;
> + struct fuse_pqueue fpq;
> + struct fuse_req *req;
> +
> + err = -ENOTCONN;
> + if (!ring)
> + return err;
> +
> + queue = ring->queues[cmd_req->qid];

READ_ONCE()

> + if (!queue)
> + return err;
> + fpq = queue->fpq;
> +

--
Pavel Begunkov