Post Syndicated from original https://lwn.net/Articles/932060/

There are some filesystems that use the Filesystem
in Userspace (FUSE) framework but only to provide a different view of
an underlying filesystem, such as different file
metadata, a changed directory hierarchy, or other changes of that sort.
The read-only filtered
filesystem, which simply filters the view of which files
are available, is one example; the file data could come directly from the
underlying
filesystem, but currently needs to traverse the FUSE user-space server
process. Finding a way to bypass the server, so that the file I/O operations go
directly from the application to the underlying filesystem would be beneficial.
In
a filesystem session at the 2023 Linux Storage,
Filesystem, Memory-Management and BPF Summit, Miklos Szeredi wanted to explore
different options for adding such a mechanism, which was referred to as
a “FUSE passthrough”—though “bypass” might be a better alternative.