On 1/17/25 12:18, Pavel Begunkov wrote:
> On 1/7/25 00:25, Bernd Schubert wrote:
>> 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.
>
> Reviewed-by: Pavel Begunkov <asml.silence@xxxxxxxxx> # io_uring
>
>>
>> Signed-off-by: Bernd Schubert <bschubert@xxxxxxx>
>> ---
>> fs/fuse/dev_uring.c | 450 ++++++++++++++++++++++++++++++++++++++++
>> ++++++++++
>> fs/fuse/dev_uring_i.h | 12 ++
>> fs/fuse/fuse_i.h | 4 +
>> 3 files changed, 466 insertions(+)
>>
>> diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c
>> index
>> b44ba4033615e01041313c040035b6da6af0ee17..f44e66a7ea577390da87e9ac7d118a9416898c28 100644
>> --- a/fs/fuse/dev_uring.c
>> +++ b/fs/fuse/dev_uring.c
>> @@ -26,6 +26,19 @@ 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,
>> + unsigned int issue_flags)
>> +{
>> + 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_done(ring_ent->cmd, 0, 0, issue_flags);
>> + ring_ent->cmd = NULL;
>
> I haven't checked if it races with some reallocation, but
> you might want to consider clearing it under the spin.
>
> spin_lock(&queue->lock);
> ...
> cmd = ring_ent->cmd;
> ring_ent->cmd = NULL;
> spin_unlock(&queue->lock);
>
> io_uring_cmd_done(cmd);
>
> Can be done on top if even needed.
Yes, thanks for your review! That is what I actually have in the ddn
branch, when I found the startup race.
Thanks,
Bernd
