Re: [PATCH V9 1/4] fuse: Definitions and ioctl() for passthrough

[Miklos Szeredi]

On Thu, Sep 24, 2020 at 3:13 PM Alessio Balsini <balsini@xxxxxxxxxxx> wrote:
>
> Introduce the new FUSE passthrough ioctl(), which allows userspace to
> specify a direct connection between a FUSE file and a lower file system
> file.
> Such ioctl() requires userspace to specify:
> - the file descriptor of one of its opened files,
> - the unique identifier of the FUSE request associated with a pending
>   open/create operation,
> both encapsulated into a fuse_passthrough_out data structure.
> The ioctl() will search for the pending FUSE request matching the unique
> identifier, and update the passthrough file pointer of the request with the
> file pointer referenced by the passed file descriptor.
> When that pending FUSE request is handled, the passthrough file pointer
> is copied to the fuse_file data structure, so that the link between FUSE
> and lower file system is consolidated.

How about returning an ID from the ioctl (like the fuse2 porototype)
and returning that in fuse_open_out.passthrough_fh?

Seems a more straightforward interface to me.

Thanks,
Miklos