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

From: Moinak Bhattacharyya
Date: Fri Feb 21 2025 - 13:15:08 EST


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.
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.