FUSE Passthrough Support May Land For Linux 6.9 To Help Boost I/O Performance

Being worked on and off for several years has been FUSE read/write passthrough support for improving the performance of File-Systems in User-Space by avoiding the daemon overhead on a per-file basis where read/write operations are forwarded by the kernel directly to the lower file-system rather than the FUSE daemon. FUSE passthrough mode has shown to be a big performance win and it looks like it could be finally mainlined come Linux 6.9.

The FUSE passthrough mode patches were recently queued up into FUSE.git's for-next branch. With the patches now in the "for-next" branch ahead of the Linux 6.9 merge window in March, the code will hopefully be merged for this next kernel cycle barring any last minute issues.

The support depends on the new FUSE_PASSTHROUGH Kconfig switch for allowing this bypassing of the FUSE server via mapping specific FUSE operations to be performed directly on the backing file. Benchmarks on earlier versions of the FUSE passthrough mode has shown it performing much closer to the native I/O performance than with the existing FUSE implementation:

For those interested, below is a presentation on FUSE passthrough from last year's Linux Storage / File-System Summit.

Linux 6.9 is looking to be another exciting kernel cycle. While the merge window will kickoff in March, the stable debut will happen around the middle of the year.