Re: [PATCH] Fuse: Add backing file support for uring_cmd

[Bernd Schubert <bernd@bsbernd.com>]

On 2/21/25 19:13, Moinak Bhattacharyya wrote:
> I don't have the modifications to libfuse. What tree are you using for
> the uring modifications? I dont see any uring patches on the latest
> master liburing.

https://github.com/bsbernd/libfuse/tree/uring

This is a development branch, goint to create a new branch out
of that during the next days (now that I'm eventually almost through
with libfuse-3.17).

>>> It is possible, for example set FOPEN_PASSTHROUGH_FD to
>>> interpret backing_id as backing_fd, but note that in the current
>>> implementation of passthrough_hp, not every open does
>>> fuse_passthrough_open().
>>> The non-first open of an inode uses a backing_id stashed in inode,
>>> from the first open so we'd need different server logic depending on
>>> the commands channel, which is not nice.
> I wonder if we can just require URING registered FDs (using
> IORING_REGISTER_FILES). I think io_uring does checks on the file
> permissions when the FD is registered.

Could you explain how fd registration into the ring would help here?


Thanks,
Bernd