arcbox-fs

High-performance filesystem service for ArcBox.

Overview

This crate implements VirtioFS-based file sharing between host and guest, providing near-native file I/O performance. It handles FUSE protocol requests from the guest and maps them to host filesystem operations.

Features

• Zero-copy I/O: Direct memory mapping when possible
• Parallel I/O: Concurrent request handling with multiple worker threads
• Intelligent caching: Negative cache for "file not found" results
• FUSE protocol: Compatible with standard virtiofs drivers
• Passthrough filesystem: Direct mapping of guest operations to host

Architecture

Guest: mount -t virtiofs arcbox /mnt/arcbox
                   |
                   v
+------------------------------------------+
|               arcbox-fs                   |
|  +------------------------------------+  |
|  |          FuseDispatcher            |  |
|  |  - Request parsing                 |  |
|  |  - Reply handling                  |  |
|  +------------------------------------+  |
|  +------------------------------------+  |
|  |         PassthroughFs              |  |
|  |  - Direct host filesystem access   |  |
|  |  - File handle management          |  |
|  +------------------------------------+  |
|  +------------------------------------+  |
|  |         NegativeCache              |  |
|  |  - Caches non-existent paths       |  |
|  +------------------------------------+  |
+------------------------------------------+

Usage

use arcbox_fs::{FsConfig, FuseDispatcher, PassthroughConfig, PassthroughFs};

let config = FsConfig {
    tag: "arcbox".to_string(),
    source: "/path/to/share".to_string(),
    num_threads: 4,
    writeback_cache: true,
    cache_timeout: 1,
};

let fs = PassthroughFs::new(PassthroughConfig::default())?;
let dispatcher = FuseDispatcher::new(fs);

Performance Optimizations

• Negative caching: Avoids repeated stat() calls on non-existent paths (effective for node_modules, .git)
• Handle reuse: Keeps file handles open for frequently accessed files
• Readahead: Prefetches sequential reads
• Write combining: Batches small writes

License

MIT OR Apache-2.0