FUSE-zstd

A simple FUSE filesystem where existing folder with files compressed by zstd is mapped to folder with uncompressed files.

What it does?

It simply remounts a part of existing filesystem path.

file.txt.zst
directory/
directory/file.txt.zst

to

file.txt
directory/
directory/file.txt

Note

When you add compressed files directly to the source folder, you need to reopen them in mounted folder to recalculate the uncompressed size (e.g. using head cmd), othewise the files in mounted folder will displayed as empty.

And also be sure that all the files in source folder will contain .zst extenstion, otherwise the files won't be shown in the mounted dir.

Requirements

• fuse3
• libfuse3

Building from sources

Insall rust

see https://www.rust-lang.org/tools/install

Install dev libraries

Debian:

apt install fuse3 libfuse3-3 libfuse3-dev

Compile it

cargo build --release

Prepare a package

Debian

Install cargo-deb

cargo install cargo-deb

Build the package

cargo deb

Usage

Make sure that option user_allow_other is enabled in your /etc/fuse.conf.

Make sure that both source and mount point directories exist and have proper permissions.

mkdir -p /tmp/fuse-zstd/ /tmp/fuse-zstd-compressed/

Run it.

cargo run -- --data-dir /tmp/fuse-zstd-compressed/ --mount-point /tmp/fuse-zstd/

Now every file you create in mount-point dir should appear as compressed file with zst extension in data-dir.

Limitations

• Source folder has to be only from a single FS (needs to have unique inodes).
• Source folder FS has to support extended file attributes (xattr) to store uncompressed size of the files.
• Source folder has to contain only files and directories (othewise fuse-zstd may crash).

Motivation

Although there are some filesystem which support compression not all hosting services support such filesystems. So imagine you have an ext4 FS with thousands of large JSON files. In this situation FUSE-Zstd can be quite handy.