Operating SystemsSpecial File Systems

Special File Systems

LevelAdvanced

Duration90 mins

TopicSpecial File Systems

5 / 5

FUSE - Filesystem in Userspace

When Anyone Can Create a File System

Traditionally, implementing a file system required kernel programming—a domain of C code, kernel APIs, and the risk of crashing the entire system with a single bug. File system development was limited to kernel experts, and prototyping new ideas meant long compile-debug-reboot cycles.

FUSE changed everything. FUSE—Filesystem in Userspace—provides a bridge between the kernel's VFS layer and ordinary userspace programs. Your file system can be written in Python, Go, Rust, JavaScript, or any language. A bug crashes only your FUSE process, not the kernel. Development happens in minutes rather than hours.

The result is an explosion of creative file systems:

sshfs — Mount remote directories over SSH
s3fs — Mount Amazon S3 buckets as local directories
archivemount — Navigate inside ZIP/TAR files as folders
gocryptfs — Encrypted overlay file systems
rclone mount — Mount Google Drive, Dropbox, and 40+ cloud providers
NTFS-3G — Full NTFS read/write support

FUSE democratized file system development, enabling solutions that would never have been written as kernel modules.

What You Will Learn

By the end of this page, you will understand FUSE architecture from kernel module to libfuse to user implementation. You'll learn the performance tradeoffs, security considerations, and how to evaluate when FUSE is appropriate versus kernel file systems.

FUSE Architecture Overview

FUSE consists of three main components that work together to route file system operations from kernel to userspace and back:

FUSE kernel module (fuse.ko) — Intercepts VFS operations and routes them to userspace
libfuse — Userspace library that handles protocol communication and provides a friendly API
User daemon — Your file system implementation, linked against libfuse

The request flow:

Converting Mermaid diagram...

Key architectural points:

Context switches — Every operation involves at least two context switches (kernel→user→kernel)
Serialization — Requests are serialized through /dev/fuse; libfuse may use multiple threads
Asynchronous possible — Modern FUSE supports async I/O for better concurrency
Interrupts — Long operations can be interrupted (user presses Ctrl+C)

fuse_components
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
# Check if FUSE kernel module is loaded
$ lsmod | grep fuse
fuse                  147456  5
 
# The /dev/fuse device node
$ ls -la /dev/fuse
crw-rw-rw- 1 root root 10, 229 Jan 16 10:00 /dev/fuse
 
# View mounted FUSE filesystems
$ mount | grep fuse
fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)
sshfs#user@host:/path on /mnt/remote type fuse.sshfs (rw,nosuid,nodev,...)
 
# Each FUSE mount has a connection entry
$ ls /sys/fs/fuse/connections/
42  43  45
 
# Connection details
$ cat /sys/fs/fuse/connections/42/waiting
0    # Number of requests waiting for userspace

fusermount vs mount.fuse

FUSE filesystems can be mounted by unprivileged users using fusermount (a setuid helper) or via mount.fuse. This is a key feature—no root access required to mount your network drives or encrypted folders.

The FUSE Protocol

Communication between the kernel and userspace happens through a well-defined protocol over /dev/fuse. Understanding this protocol reveals how FUSE operations map to your file system callbacks.

Core FUSE Operations
Operation	VFS Trigger	Description	Must Implement?
`FUSE_LOOKUP`	`path_lookup`	Resolve path component to inode	Yes
`FUSE_GETATTR`	`stat`, `fstat`	Get file/directory attributes	Yes
`FUSE_READDIR`	`readdir`	List directory contents	Yes (for directories)
`FUSE_OPEN`	`open`	Open file, return handle	Yes
`FUSE_READ`	`read`	Read file content	Yes
`FUSE_WRITE`	`write`	Write file content	If writable
`FUSE_CREATE`	`creat`, `open(O_CREAT)`	Create and open file	If writable
`FUSE_MKDIR`	`mkdir`	Create directory	If writable
`FUSE_UNLINK`	`unlink`	Delete file	If writable
`FUSE_RELEASE`	`close`	Close file handle	Usually
`FUSE_FLUSH`	`close`, `fsync`	Flush buffers before close	Optional
`FUSE_SETATTR`	`chmod`, `chown`, `utimes`	Modify attributes	If writable

Protocol structure:

Each request contains a header followed by operation-specific data:

struct fuse_in_header {
    uint32_t len;      // Total message length
    uint32_t opcode;   // FUSE_READ, FUSE_WRITE, etc.
    uint64_t unique;   // Request ID for matching replies
    uint64_t nodeid;   // Inode number
    uint32_t uid;      // Caller's UID
    uint32_t gid;      // Caller's GID
    uint32_t pid;      // Caller's PID
    uint32_t padding;
};

Replies include a header and operation-specific results:

struct fuse_out_header {
    uint32_t len;      // Total message length
    int32_t  error;    // 0 for success, negative errno for error
    uint64_t unique;   // Matches request's unique ID
};

High-Level vs Low-Level API

libfuse provides two APIs: the high-level API operates on paths (easier, recommended for most users) while the low-level API operates on inodes with explicit reply functions (more control, required for advanced features). Most FUSE filesystems use the high-level API.

Implementing a FUSE Filesystem

Let's walk through implementing a simple FUSE filesystem. This example creates a read-only filesystem with a single file—enough to demonstrate the core concepts.

simple_fuse.c
C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
/*
 * simplefs.c - A minimal FUSE filesystem
 * Compile: gcc -Wall simplefs.c `pkg-config fuse3 --cflags --libs` -o simplefs
 * Usage: ./simplefs /mnt/point
 */
 
#define FUSE_USE_VERSION 31
 
#include <fuse.h>
#include <string.h>
#include <errno.h>
 
/* Our single file's content */
static const char *hello_str = "Hello from FUSE!\n";
static const char *hello_path = "/hello.txt";
 
/* 
 * getattr - Return file/directory attributes
 * Called for stat(), lstat(), etc.
 */
static int simple_getattr(const char *path, struct stat *stbuf,
                          struct fuse_file_info *fi)
{
    memset(stbuf, 0, sizeof(struct stat));
 
    if (strcmp(path, "/") == 0) {
        /* Root directory */
        stbuf->st_mode = S_IFDIR | 0755;
        stbuf->st_nlink = 2;
        return 0;
    } 
    else if (strcmp(path, hello_path) == 0) {
        /* Our file */
        stbuf->st_mode = S_IFREG | 0444;
        stbuf->st_nlink = 1;
        stbuf->st_size = strlen(hello_str);
        return 0;
    }
 
    return -ENOENT;  /* Path not found */
}
 
/*
 * readdir - List directory contents
 * Called for ls, etc.
 */
static int simple_readdir(const char *path, void *buf, 
                          fuse_fill_dir_t filler,
                          off_t offset, struct fuse_file_info *fi,
                          enum fuse_readdir_flags flags)
{
    if (strcmp(path, "/") != 0)
        return -ENOENT;
 
    /* Standard directory entries */
    filler(buf, ".", NULL, 0, 0);
    filler(buf, "..", NULL, 0, 0);
    
    /* Our file (without leading /) */
    filler(buf, "hello.txt", NULL, 0, 0);
 
    return 0;
}
 
/*
 * open - Open a file
 * Validate access permissions
 */
static int simple_open(const char *path, struct fuse_file_info *fi)
{
    if (strcmp(path, hello_path) != 0)
        return -ENOENT;
 
    /* Read-only filesystem */
    if ((fi->flags & O_ACCMODE) != O_RDONLY)
        return -EACCES;
 
    return 0;
}
 
/*
 * read - Read file content
 */
static int simple_read(const char *path, char *buf, size_t size,
                       off_t offset, struct fuse_file_info *fi)
{
    size_t len;
 
    if (strcmp(path, hello_path) != 0)
        return -ENOENT;
 
    len = strlen(hello_str);
    
    if (offset >= len)
        return 0;  /* EOF */
 
    if (offset + size > len)
        size = len - offset;
 
    memcpy(buf, hello_str + offset, size);
    return size;
}
 
/* Operations table - which functions we implement */
static const struct fuse_operations simple_ops = {
    .getattr  = simple_getattr,
    .readdir  = simple_readdir,
    .open     = simple_open,
    .read     = simple_read,
};
 
int main(int argc, char *argv[])
{
    return fuse_main(argc, argv, &simple_ops, NULL);
}

fuse_usage
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
# Build the filesystem
$ gcc -Wall simplefs.c `pkg-config fuse3 --cflags --libs` -o simplefs
 
# Mount it
$ mkdir /tmp/mnt
$ ./simplefs /tmp/mnt
 
# Use it like any filesystem!
$ ls /tmp/mnt
hello.txt
 
$ cat /tmp/mnt/hello.txt
Hello from FUSE!
 
$ ls -la /tmp/mnt/
total 0
drwxr-xr-x 2 user user    0 Jan  1  1970 .
drwxrwxrwt 5 root root 1024 Jan 16 10:00 ..
-r--r--r-- 1 user user   17 Jan  1  1970 hello.txt
 
# Unmount
$ fusermount -u /tmp/mnt
 
# Debug mode (foreground, verbose)
$ ./simplefs -f -d /tmp/mnt

Python example with fusepy:

FUSE filesystems don't have to be in C. Here's the equivalent in Python:

simple_fuse.py
Python
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
#!/usr/bin/env python3
"""
simple_fuse.py - A minimal FUSE filesystem in Python
Install: pip install fusepy
Usage: python simple_fuse.py /mnt/point
"""
 
from fuse import FUSE, FuseOSError, Operations
from errno import ENOENT
from stat import S_IFDIR, S_IFREG
import os
 
class SimpleFS(Operations):
    def __init__(self):
        self.content = b"Hello from FUSE!\n"
    
    def getattr(self, path, fh=None):
        if path == '/':
            return {'st_mode': S_IFDIR | 0o755, 'st_nlink': 2}
        elif path == '/hello.txt':
            return {
                'st_mode': S_IFREG | 0o444,
                'st_nlink': 1,
                'st_size': len(self.content)
            }
        else:
            raise FuseOSError(ENOENT)
    
    def readdir(self, path, fh):
        return ['.', '..', 'hello.txt']
    
    def open(self, path, flags):
        if path != '/hello.txt':
            raise FuseOSError(ENOENT)
        return 0
    
    def read(self, path, size, offset, fh):
        return self.content[offset:offset + size]
 
if __name__ == '__main__':
    import sys
    FUSE(SimpleFS(), sys.argv[1], foreground=True)

Popular FUSE Filesystems

FUSE has enabled hundreds of creative file system implementations. Here are the most notable categories and examples:

Filesystem	Description	Use Case
sshfs	Mount remote directories over SSH	Access remote files as local; no special server setup
s3fs-fuse	Mount Amazon S3 buckets	Access S3 as local filesystem; suitable for read-heavy workloads
rclone mount	Mount 40+ cloud providers	Google Drive, Dropbox, OneDrive, etc. as local folders
davfs2	Mount WebDAV shares	NextCloud, ownCloud, Box.com access
gcsfs	Mount Google Cloud Storage	GCS as local filesystem

sshfs_usage
Bash
# Mount remote directory over SSH
$ sshfs user@host:/remote/path /local/mount
 
# With options for better performance
$ sshfs user@host:/path /mnt \
    -o cache=yes \
    -o kernel_cache \
    -o compression=yes \
    -o ServerAliveInterval=15
 
# Unmount
$ fusermount -u /local/mount

Performance Considerations

FUSE's flexibility comes at a performance cost. Understanding these tradeoffs helps you decide when FUSE is appropriate and how to optimize FUSE-based solutions.

Performance Costs

•Context switches — Every operation crosses kernel/user boundary twice
•Data copying — Data must be copied between kernel and userspace buffers
•Serialization — Protocol overhead for marshalling requests/replies
•Single daemon — Default single-thread limits concurrency
•Latency — Adds microseconds to every operation

Mitigation Strategies

•Multithreading — Use -o max_threads=N for parallel requests
•splice/zero-copy — Modern FUSE supports splice() for less copying
•Kernel caching — Enable kernel_cache, auto_cache for reads
•Writeback caching — -o writeback_cache for write aggregation
•Large reads — -o max_read=N for fewer, larger requests

fuse_performance_options
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
# ═══════════════════════════════════════════════════════════════
# Performance-optimized FUSE mount options
# ═══════════════════════════════════════════════════════════════
 
# For read-heavy workloads (sshfs, s3fs)
$ sshfs user@host:/path /mnt \
    -o kernel_cache \        # Cache file data in kernel
    -o auto_cache \          # Invalidate cache intelligently
    -o cache=yes \           # Enable all caching
    -o cache_timeout=300 \   # 5 minute attribute cache
    -o max_readahead=131072 \ # 128K readahead
    -o compression=yes         # Reduce network transfer
 
# For write-heavy workloads
$ fuse_fs /mnt \
    -o writeback_cache \     # Aggregate writes
    -o max_write=131072 \    # 128K writes
    -o max_background=32       # More background writeback
 
# Multithreaded for concurrent access
$ fuse_fs /mnt -o max_threads=16
 
# ═══════════════════════════════════════════════════════════════
# Benchmarking FUSE overhead
# ═══════════════════════════════════════════════════════════════
 
# Baseline: native filesystem
$ fio --name=test --filename=/native/testfile --size=1G --rw=randread --bs=4k
 
# FUSE filesystem (same underlying storage)
$ fio --name=test --filename=/fuse_mount/testfile --size=1G --rw=randread --bs=4k
 
# Typical results:
# Native:     200k IOPS, 50µs latency
# FUSE:        50k IOPS, 200µs latency
# Overhead:   ~4x for small random operations
 
# For sequential large I/O, overhead is much smaller:
# Native:     3.5 GB/s
# FUSE:       3.0 GB/s  (14% overhead)

When to Use FUSE vs Kernel Filesystem
Factor	Prefer FUSE	Prefer Kernel FS
Development speed	Rapid prototyping, iterating	Mature, stable implementation
Safety	Bugs crash only daemon	Must not crash kernel
Performance needs	Network I/O dominates	Low-latency local storage
Complexity	Simple logic, any language	Complex, must be C/Rust
Deployment	No kernel modules needed	Needs kernel/module updates
Use case	Cloud storage, encryption overlays	Local block devices, high IOPS

Network-Bound Workloads

For network-based FUSE filesystems (sshfs, s3fs, rclone), the network latency typically dwarfs FUSE overhead. A 10ms network round-trip makes FUSE's 100µs overhead negligible. FUSE is often the perfect solution for these cases.

Security Model

FUSE introduces unique security considerations since it allows unprivileged users to provide filesystem operations that affect how files appear to the system.

FUSE Security Features

•User-owned mounts — By default, only the mounting user can access FUSE mounts (prevents privilege escalation)
•allow_other — Explicit permission needed to let other users access the mount (requires root or user_allow_other in /etc/fuse.conf)
•allow_root — Allows root to access user-owned FUSE mounts (separate from allow_other)
•Nosuid by default — Setuid/setgid bits are ignored on FUSE mounts (prevents local privilege escalation)
•Nodev by default — Device nodes on FUSE mounts are ignored (prevents device exploitation)
•Inode owner verification — Kernel validates that daemon is returning consistent ownership

fuse_security
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
# ═══════════════════════════════════════════════════════════════
# Default behavior: only mounting user can access
# ═══════════════════════════════════════════════════════════════
 
$ sshfs user@host:/path /mnt/remote                       # Mount as user
$ ls /mnt/remote                                          # Works
$ sudo ls /mnt/remote                                     # Permission denied!
 
# ═══════════════════════════════════════════════════════════════
# Enabling access for other users
# ═══════════════════════════════════════════════════════════════
 
# 1. Edit /etc/fuse.conf (as root)
$ cat /etc/fuse.conf
user_allow_other    # Uncomment this line
 
# 2. Mount with allow_other
$ sshfs -o allow_other user@host:/path /mnt/remote
$ sudo ls /mnt/remote                                     # Now works!
 
# ═══════════════════════════════════════════════════════════════
# Security restrictions
# ═══════════════════════════════════════════════════════════════
 
# FUSE mounts are nosuid by default
$ mount | grep fuse
sshfs#user@host:/path on /mnt/remote type fuse.sshfs (rw,nosuid,nodev,...)
 
# Even if filesystem returns setuid bit, it's ignored
$ ls -la /mnt/remote/setuid_binary
-rwsr-xr-x 1 root root 12345 ... setuid_binary
# The 's' is displayed, but execution won't gain privileges
 
# ═══════════════════════════════════════════════════════════════
# Preventing malicious FUSE filesystems
# ═══════════════════════════════════════════════════════════════
 
# A malicious FUSE FS could:
# - Return different content each read (confuse security tools)
# - Lie about file permissions/ownership
# - Hang on read (denial of service)
# - Return very slow (resource exhaustion)
 
# Mitigations:
# - nosuid/nodev defaults
# - User isolation (no allow_other by default)
# - Timeout handling in VFS
# - Never run untrusted FUSE daemons

Security Implications of allow_other

Enabling allow_other means root (and other users) can access files through your FUSE daemon. If your daemon has bugs or returns incorrect permissions, this could expose data or enable attacks. Only use allow_other when necessary, and only with trusted FUSE implementations.

Advanced FUSE Features

Modern FUSE (especially FUSE 3.x) includes advanced features for improved performance and functionality:

Advanced FUSE 3.x Features
Feature	Description	Benefit
Writeback cache	Kernel aggregates writes before sending	Dramatically better write performance
Readdirplus	Readdir returns stat info too	Fewer round-trips for ls -la
Parallel readdir	Multiple readdir requests concurrently	Faster large directory listing
Splice support	Zero-copy data transfer	Reduced CPU usage for large transfers
FOPEN_KEEP_CACHE	Preserve cache across opens	Better cache utilization
Passthrough I/O	Direct I/O to underlying file (experimental)	Near-native performance for overlays
Notifications	Kernel can notify daemon of invalidation	Cache coherence with external changes

fuse_advanced_features
C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
/* Enabling advanced features in FUSE daemon */
 
/* In init() callback, specify capabilities */
static void *my_init(struct fuse_conn_info *conn,
                     struct fuse_config *cfg)
{
    /* Enable writeback caching */
    if (conn->capable & FUSE_CAP_WRITEBACK_CACHE)
        conn->want |= FUSE_CAP_WRITEBACK_CACHE;
    
    /* Enable readdirplus */
    if (conn->capable & FUSE_CAP_READDIRPLUS)
        conn->want |= FUSE_CAP_READDIRPLUS;
    
    /* Enable parallel readdir */
    if (conn->capable & FUSE_CAP_PARALLEL_DIROPS)
        conn->want |= FUSE_CAP_PARALLEL_DIROPS;
    
    /* Keep page cache across opens */
    cfg->kernel_cache = 1;
    cfg->auto_cache = 1;
    
    /* Larger read/write buffers */
    conn->max_read = 131072;    /* 128KB */
    conn->max_write = 131072;
    
    return NULL;
}
 
/* Readdirplus: return stat info with each entry */
static int my_readdirplus(const char *path, void *buf, 
                          fuse_fill_dir_t filler,
                          off_t offset, 
                          struct fuse_file_info *fi,
                          enum fuse_readdir_flags flags)
{
    struct stat stbuf;
    
    /* Fill stat info for each entry */
    memset(&stbuf, 0, sizeof(stbuf));
    stbuf.st_mode = S_IFREG | 0644;
    stbuf.st_size = 1234;
    stbuf.st_mtime = time(NULL);
    
    /* Pass stat info to filler - kernel won't need extra getattr calls */
    filler(buf, "filename.txt", &stbuf, 0, 
           FUSE_FILL_DIR_PLUS);
    
    return 0;
}

virtiofs: FUSE for VMs

virtiofs uses the FUSE protocol over a virtio transport to share host directories with VMs. This provides near-native performance because the FUSE operations go directly to the host without network serialization. QEMU/KVM and libvirt support virtiofs for fast shared filesystem access.

Debugging FUSE Filesystems

Debugging FUSE filesystems is much easier than kernel filesystems—you can use standard debugging tools, add print statements, and attach debuggers without rebooting.

fuse_debugging
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
# ═══════════════════════════════════════════════════════════════
# Debug mode: foreground with verbose output
# ═══════════════════════════════════════════════════════════════
 
$ ./my_fuse_fs -f -d /mnt/point
# -f = foreground (don't daemonize)
# -d = debug (print every FUSE operation)
 
# Output shows every operation:
unique: 1, opcode: LOOKUP (1), nodeid: 1, insize: 48, pid: 12345
LOOKUP /hello.txt
   getattr /hello.txt
   unique: 1, success, outsize: 144
 
unique: 2, opcode: OPEN (14), nodeid: 2, insize: 48, pid: 12345
OPEN /hello.txt
   unique: 2, success, outsize: 32
 
# ═══════════════════════════════════════════════════════════════
# Attach gdb to running FUSE process
# ═══════════════════════════════════════════════════════════════
 
$ ps aux | grep my_fuse_fs
user     12345  0.0  0.1  12345  6789 ?  Sl   10:00   0:00 ./my_fuse_fs /mnt
 
$ sudo gdb -p 12345
 
# ═══════════════════════════════════════════════════════════════
# Trace FUSE operations with strace
# ═══════════════════════════════════════════════════════════════
 
# Watch the application side
$ strace cat /mnt/fuse_fs/file.txt
open("/mnt/fuse_fs/file.txt", O_RDONLY) = 3
read(3, "Hello from FUSE!\n", 4096) = 17
...
 
# Watch the FUSE daemon side
$ strace -p $(pgrep my_fuse_fs)
read(3, "\x30\x00\x00\x00\x01\x00\x00\x00...", 135168) = 48  # Read request
write(3, "\x90\x00\x00\x00\x00\x00\x00\x00...", 144) = 144    # Send reply
 
# ═══════════════════════════════════════════════════════════════
# Check FUSE connection status
# ═══════════════════════════════════════════════════════════════
 
$ cat /sys/fs/fuse/connections/*/waiting
0    # Requests waiting for daemon
 
$ cat /sys/fs/fuse/connections/*/congestion_threshold
0    # Congestion control
 
# If 'waiting' is high, daemon is too slow
 
# ═══════════════════════════════════════════════════════════════
# Force unmount stuck FUSE filesystem
# ═══════════════════════════════════════════════════════════════
 
# Normal unmount
$ fusermount -u /mnt/point
 
# Force unmount (if daemon is hung)
$ fusermount -zu /mnt/point      # Lazy unmount
 
# Kill daemon directly
$ pkill -9 my_fuse_fs
$ fusermount -u /mnt/point

Summary: FUSE

FUSE democratized filesystem development, enabling solutions from encrypted overlays to cloud storage mounts that would never have been practical as kernel modules.

Key Takeaways

•Architecture — Kernel module intercepts VFS calls, routes to userspace daemon via /dev/fuse
•Any language — Implement filesystems in Python, Go, Rust, C, or any language with FUSE bindings
•Safety — Bugs crash only your daemon, not the kernel; debugging with standard tools
•Unprivileged mounting — Users can mount FUSE filesystems without root access via fusermount
•Rich ecosystem — sshfs, gocryptfs, rclone, s3fs, NTFS-3G, and hundreds more
•Performance tradeoffs — Context switches add latency; use caching options for mitigation
•Security model — nosuid/nodev defaults, user isolation, explicit allow_other needed

Module complete:

This concludes our exploration of special file systems. You've learned about:

/proc — The process file system exposing kernel and process information
/sys — The sysfs unified device model interface
tmpfs — Memory-backed file storage with swap support
devtmpfs — Kernel-managed dynamic device file system
FUSE — The framework enabling userspace file system implementations

These special file systems form the infrastructure that makes modern Linux work—from system monitoring to device management to application-specific virtual file systems.

Module Complete

You now have comprehensive knowledge of special file systems in Linux. This understanding is essential for system administration, performance optimization, security hardening, and building applications that leverage these powerful abstractions.

5 / 5

Loading learning content...

Operating SystemsSpecial File Systems

Special File Systems

LevelAdvanced

Duration90 mins

TopicSpecial File Systems

5 / 5

FUSE - Filesystem in Userspace

When Anyone Can Create a File System

The result is an explosion of creative file systems:

sshfs — Mount remote directories over SSH
s3fs — Mount Amazon S3 buckets as local directories
archivemount — Navigate inside ZIP/TAR files as folders
gocryptfs — Encrypted overlay file systems
rclone mount — Mount Google Drive, Dropbox, and 40+ cloud providers
NTFS-3G — Full NTFS read/write support

FUSE democratized file system development, enabling solutions that would never have been written as kernel modules.

What You Will Learn

FUSE Architecture Overview

FUSE consists of three main components that work together to route file system operations from kernel to userspace and back:

FUSE kernel module (fuse.ko) — Intercepts VFS operations and routes them to userspace
libfuse — Userspace library that handles protocol communication and provides a friendly API
User daemon — Your file system implementation, linked against libfuse

The request flow:

Converting Mermaid diagram...

Key architectural points:

Context switches — Every operation involves at least two context switches (kernel→user→kernel)
Serialization — Requests are serialized through /dev/fuse; libfuse may use multiple threads
Asynchronous possible — Modern FUSE supports async I/O for better concurrency
Interrupts — Long operations can be interrupted (user presses Ctrl+C)

fuse_components
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
# Check if FUSE kernel module is loaded
$ lsmod | grep fuse
fuse                  147456  5
 
# The /dev/fuse device node
$ ls -la /dev/fuse
crw-rw-rw- 1 root root 10, 229 Jan 16 10:00 /dev/fuse
 
# View mounted FUSE filesystems
$ mount | grep fuse
fusectl on /sys/fs/fuse/connections type fusectl (rw,nosuid,nodev,noexec,relatime)
sshfs#user@host:/path on /mnt/remote type fuse.sshfs (rw,nosuid,nodev,...)
 
# Each FUSE mount has a connection entry
$ ls /sys/fs/fuse/connections/
42  43  45
 
# Connection details
$ cat /sys/fs/fuse/connections/42/waiting
0    # Number of requests waiting for userspace

fusermount vs mount.fuse

The FUSE Protocol

Communication between the kernel and userspace happens through a well-defined protocol over /dev/fuse. Understanding this protocol reveals how FUSE operations map to your file system callbacks.

Core FUSE Operations
Operation	VFS Trigger	Description	Must Implement?
`FUSE_LOOKUP`	`path_lookup`	Resolve path component to inode	Yes
`FUSE_GETATTR`	`stat`, `fstat`	Get file/directory attributes	Yes
`FUSE_READDIR`	`readdir`	List directory contents	Yes (for directories)
`FUSE_OPEN`	`open`	Open file, return handle	Yes
`FUSE_READ`	`read`	Read file content	Yes
`FUSE_WRITE`	`write`	Write file content	If writable
`FUSE_CREATE`	`creat`, `open(O_CREAT)`	Create and open file	If writable
`FUSE_MKDIR`	`mkdir`	Create directory	If writable
`FUSE_UNLINK`	`unlink`	Delete file	If writable
`FUSE_RELEASE`	`close`	Close file handle	Usually
`FUSE_FLUSH`	`close`, `fsync`	Flush buffers before close	Optional
`FUSE_SETATTR`	`chmod`, `chown`, `utimes`	Modify attributes	If writable

Protocol structure:

Each request contains a header followed by operation-specific data:

struct fuse_in_header {
    uint32_t len;      // Total message length
    uint32_t opcode;   // FUSE_READ, FUSE_WRITE, etc.
    uint64_t unique;   // Request ID for matching replies
    uint64_t nodeid;   // Inode number
    uint32_t uid;      // Caller's UID
    uint32_t gid;      // Caller's GID
    uint32_t pid;      // Caller's PID
    uint32_t padding;
};

Replies include a header and operation-specific results:

struct fuse_out_header {
    uint32_t len;      // Total message length
    int32_t  error;    // 0 for success, negative errno for error
    uint64_t unique;   // Matches request's unique ID
};

High-Level vs Low-Level API

Implementing a FUSE Filesystem

Let's walk through implementing a simple FUSE filesystem. This example creates a read-only filesystem with a single file—enough to demonstrate the core concepts.

simple_fuse.c
C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
/*
 * simplefs.c - A minimal FUSE filesystem
 * Compile: gcc -Wall simplefs.c `pkg-config fuse3 --cflags --libs` -o simplefs
 * Usage: ./simplefs /mnt/point
 */
 
#define FUSE_USE_VERSION 31
 
#include <fuse.h>
#include <string.h>
#include <errno.h>
 
/* Our single file's content */
static const char *hello_str = "Hello from FUSE!\n";
static const char *hello_path = "/hello.txt";
 
/* 
 * getattr - Return file/directory attributes
 * Called for stat(), lstat(), etc.
 */
static int simple_getattr(const char *path, struct stat *stbuf,
                          struct fuse_file_info *fi)
{
    memset(stbuf, 0, sizeof(struct stat));
 
    if (strcmp(path, "/") == 0) {
        /* Root directory */
        stbuf->st_mode = S_IFDIR | 0755;
        stbuf->st_nlink = 2;
        return 0;
    } 
    else if (strcmp(path, hello_path) == 0) {
        /* Our file */
        stbuf->st_mode = S_IFREG | 0444;
        stbuf->st_nlink = 1;
        stbuf->st_size = strlen(hello_str);
        return 0;
    }
 
    return -ENOENT;  /* Path not found */
}
 
/*
 * readdir - List directory contents
 * Called for ls, etc.
 */
static int simple_readdir(const char *path, void *buf, 
                          fuse_fill_dir_t filler,
                          off_t offset, struct fuse_file_info *fi,
                          enum fuse_readdir_flags flags)
{
    if (strcmp(path, "/") != 0)
        return -ENOENT;
 
    /* Standard directory entries */
    filler(buf, ".", NULL, 0, 0);
    filler(buf, "..", NULL, 0, 0);
    
    /* Our file (without leading /) */
    filler(buf, "hello.txt", NULL, 0, 0);
 
    return 0;
}
 
/*
 * open - Open a file
 * Validate access permissions
 */
static int simple_open(const char *path, struct fuse_file_info *fi)
{
    if (strcmp(path, hello_path) != 0)
        return -ENOENT;
 
    /* Read-only filesystem */
    if ((fi->flags & O_ACCMODE) != O_RDONLY)
        return -EACCES;
 
    return 0;
}
 
/*
 * read - Read file content
 */
static int simple_read(const char *path, char *buf, size_t size,
                       off_t offset, struct fuse_file_info *fi)
{
    size_t len;
 
    if (strcmp(path, hello_path) != 0)
        return -ENOENT;
 
    len = strlen(hello_str);
    
    if (offset >= len)
        return 0;  /* EOF */
 
    if (offset + size > len)
        size = len - offset;
 
    memcpy(buf, hello_str + offset, size);
    return size;
}
 
/* Operations table - which functions we implement */
static const struct fuse_operations simple_ops = {
    .getattr  = simple_getattr,
    .readdir  = simple_readdir,
    .open     = simple_open,
    .read     = simple_read,
};
 
int main(int argc, char *argv[])
{
    return fuse_main(argc, argv, &simple_ops, NULL);
}

fuse_usage
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
# Build the filesystem
$ gcc -Wall simplefs.c `pkg-config fuse3 --cflags --libs` -o simplefs
 
# Mount it
$ mkdir /tmp/mnt
$ ./simplefs /tmp/mnt
 
# Use it like any filesystem!
$ ls /tmp/mnt
hello.txt
 
$ cat /tmp/mnt/hello.txt
Hello from FUSE!
 
$ ls -la /tmp/mnt/
total 0
drwxr-xr-x 2 user user    0 Jan  1  1970 .
drwxrwxrwt 5 root root 1024 Jan 16 10:00 ..
-r--r--r-- 1 user user   17 Jan  1  1970 hello.txt
 
# Unmount
$ fusermount -u /tmp/mnt
 
# Debug mode (foreground, verbose)
$ ./simplefs -f -d /tmp/mnt

Python example with fusepy:

FUSE filesystems don't have to be in C. Here's the equivalent in Python:

simple_fuse.py
Python
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
#!/usr/bin/env python3
"""
simple_fuse.py - A minimal FUSE filesystem in Python
Install: pip install fusepy
Usage: python simple_fuse.py /mnt/point
"""
 
from fuse import FUSE, FuseOSError, Operations
from errno import ENOENT
from stat import S_IFDIR, S_IFREG
import os
 
class SimpleFS(Operations):
    def __init__(self):
        self.content = b"Hello from FUSE!\n"
    
    def getattr(self, path, fh=None):
        if path == '/':
            return {'st_mode': S_IFDIR | 0o755, 'st_nlink': 2}
        elif path == '/hello.txt':
            return {
                'st_mode': S_IFREG | 0o444,
                'st_nlink': 1,
                'st_size': len(self.content)
            }
        else:
            raise FuseOSError(ENOENT)
    
    def readdir(self, path, fh):
        return ['.', '..', 'hello.txt']
    
    def open(self, path, flags):
        if path != '/hello.txt':
            raise FuseOSError(ENOENT)
        return 0
    
    def read(self, path, size, offset, fh):
        return self.content[offset:offset + size]
 
if __name__ == '__main__':
    import sys
    FUSE(SimpleFS(), sys.argv[1], foreground=True)

Popular FUSE Filesystems

FUSE has enabled hundreds of creative file system implementations. Here are the most notable categories and examples:

Filesystem	Description	Use Case
sshfs	Mount remote directories over SSH	Access remote files as local; no special server setup
s3fs-fuse	Mount Amazon S3 buckets	Access S3 as local filesystem; suitable for read-heavy workloads
rclone mount	Mount 40+ cloud providers	Google Drive, Dropbox, OneDrive, etc. as local folders
davfs2	Mount WebDAV shares	NextCloud, ownCloud, Box.com access
gcsfs	Mount Google Cloud Storage	GCS as local filesystem

sshfs_usage
Bash
# Mount remote directory over SSH
$ sshfs user@host:/remote/path /local/mount
 
# With options for better performance
$ sshfs user@host:/path /mnt \
    -o cache=yes \
    -o kernel_cache \
    -o compression=yes \
    -o ServerAliveInterval=15
 
# Unmount
$ fusermount -u /local/mount

Performance Considerations

FUSE's flexibility comes at a performance cost. Understanding these tradeoffs helps you decide when FUSE is appropriate and how to optimize FUSE-based solutions.

Performance Costs

•Context switches — Every operation crosses kernel/user boundary twice
•Data copying — Data must be copied between kernel and userspace buffers
•Serialization — Protocol overhead for marshalling requests/replies
•Single daemon — Default single-thread limits concurrency
•Latency — Adds microseconds to every operation

Mitigation Strategies

•Multithreading — Use -o max_threads=N for parallel requests
•splice/zero-copy — Modern FUSE supports splice() for less copying
•Kernel caching — Enable kernel_cache, auto_cache for reads
•Writeback caching — -o writeback_cache for write aggregation
•Large reads — -o max_read=N for fewer, larger requests

fuse_performance_options
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
# ═══════════════════════════════════════════════════════════════
# Performance-optimized FUSE mount options
# ═══════════════════════════════════════════════════════════════
 
# For read-heavy workloads (sshfs, s3fs)
$ sshfs user@host:/path /mnt \
    -o kernel_cache \        # Cache file data in kernel
    -o auto_cache \          # Invalidate cache intelligently
    -o cache=yes \           # Enable all caching
    -o cache_timeout=300 \   # 5 minute attribute cache
    -o max_readahead=131072 \ # 128K readahead
    -o compression=yes         # Reduce network transfer
 
# For write-heavy workloads
$ fuse_fs /mnt \
    -o writeback_cache \     # Aggregate writes
    -o max_write=131072 \    # 128K writes
    -o max_background=32       # More background writeback
 
# Multithreaded for concurrent access
$ fuse_fs /mnt -o max_threads=16
 
# ═══════════════════════════════════════════════════════════════
# Benchmarking FUSE overhead
# ═══════════════════════════════════════════════════════════════
 
# Baseline: native filesystem
$ fio --name=test --filename=/native/testfile --size=1G --rw=randread --bs=4k
 
# FUSE filesystem (same underlying storage)
$ fio --name=test --filename=/fuse_mount/testfile --size=1G --rw=randread --bs=4k
 
# Typical results:
# Native:     200k IOPS, 50µs latency
# FUSE:        50k IOPS, 200µs latency
# Overhead:   ~4x for small random operations
 
# For sequential large I/O, overhead is much smaller:
# Native:     3.5 GB/s
# FUSE:       3.0 GB/s  (14% overhead)

When to Use FUSE vs Kernel Filesystem
Factor	Prefer FUSE	Prefer Kernel FS
Development speed	Rapid prototyping, iterating	Mature, stable implementation
Safety	Bugs crash only daemon	Must not crash kernel
Performance needs	Network I/O dominates	Low-latency local storage
Complexity	Simple logic, any language	Complex, must be C/Rust
Deployment	No kernel modules needed	Needs kernel/module updates
Use case	Cloud storage, encryption overlays	Local block devices, high IOPS

Network-Bound Workloads

Security Model

FUSE introduces unique security considerations since it allows unprivileged users to provide filesystem operations that affect how files appear to the system.

FUSE Security Features

•User-owned mounts — By default, only the mounting user can access FUSE mounts (prevents privilege escalation)
•allow_other — Explicit permission needed to let other users access the mount (requires root or user_allow_other in /etc/fuse.conf)
•allow_root — Allows root to access user-owned FUSE mounts (separate from allow_other)
•Nosuid by default — Setuid/setgid bits are ignored on FUSE mounts (prevents local privilege escalation)
•Nodev by default — Device nodes on FUSE mounts are ignored (prevents device exploitation)
•Inode owner verification — Kernel validates that daemon is returning consistent ownership

fuse_security
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
# ═══════════════════════════════════════════════════════════════
# Default behavior: only mounting user can access
# ═══════════════════════════════════════════════════════════════
 
$ sshfs user@host:/path /mnt/remote                       # Mount as user
$ ls /mnt/remote                                          # Works
$ sudo ls /mnt/remote                                     # Permission denied!
 
# ═══════════════════════════════════════════════════════════════
# Enabling access for other users
# ═══════════════════════════════════════════════════════════════
 
# 1. Edit /etc/fuse.conf (as root)
$ cat /etc/fuse.conf
user_allow_other    # Uncomment this line
 
# 2. Mount with allow_other
$ sshfs -o allow_other user@host:/path /mnt/remote
$ sudo ls /mnt/remote                                     # Now works!
 
# ═══════════════════════════════════════════════════════════════
# Security restrictions
# ═══════════════════════════════════════════════════════════════
 
# FUSE mounts are nosuid by default
$ mount | grep fuse
sshfs#user@host:/path on /mnt/remote type fuse.sshfs (rw,nosuid,nodev,...)
 
# Even if filesystem returns setuid bit, it's ignored
$ ls -la /mnt/remote/setuid_binary
-rwsr-xr-x 1 root root 12345 ... setuid_binary
# The 's' is displayed, but execution won't gain privileges
 
# ═══════════════════════════════════════════════════════════════
# Preventing malicious FUSE filesystems
# ═══════════════════════════════════════════════════════════════
 
# A malicious FUSE FS could:
# - Return different content each read (confuse security tools)
# - Lie about file permissions/ownership
# - Hang on read (denial of service)
# - Return very slow (resource exhaustion)
 
# Mitigations:
# - nosuid/nodev defaults
# - User isolation (no allow_other by default)
# - Timeout handling in VFS
# - Never run untrusted FUSE daemons

Security Implications of allow_other

Advanced FUSE Features

Modern FUSE (especially FUSE 3.x) includes advanced features for improved performance and functionality:

Advanced FUSE 3.x Features
Feature	Description	Benefit
Writeback cache	Kernel aggregates writes before sending	Dramatically better write performance
Readdirplus	Readdir returns stat info too	Fewer round-trips for ls -la
Parallel readdir	Multiple readdir requests concurrently	Faster large directory listing
Splice support	Zero-copy data transfer	Reduced CPU usage for large transfers
FOPEN_KEEP_CACHE	Preserve cache across opens	Better cache utilization
Passthrough I/O	Direct I/O to underlying file (experimental)	Near-native performance for overlays
Notifications	Kernel can notify daemon of invalidation	Cache coherence with external changes

fuse_advanced_features
C
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
/* Enabling advanced features in FUSE daemon */
 
/* In init() callback, specify capabilities */
static void *my_init(struct fuse_conn_info *conn,
                     struct fuse_config *cfg)
{
    /* Enable writeback caching */
    if (conn->capable & FUSE_CAP_WRITEBACK_CACHE)
        conn->want |= FUSE_CAP_WRITEBACK_CACHE;
    
    /* Enable readdirplus */
    if (conn->capable & FUSE_CAP_READDIRPLUS)
        conn->want |= FUSE_CAP_READDIRPLUS;
    
    /* Enable parallel readdir */
    if (conn->capable & FUSE_CAP_PARALLEL_DIROPS)
        conn->want |= FUSE_CAP_PARALLEL_DIROPS;
    
    /* Keep page cache across opens */
    cfg->kernel_cache = 1;
    cfg->auto_cache = 1;
    
    /* Larger read/write buffers */
    conn->max_read = 131072;    /* 128KB */
    conn->max_write = 131072;
    
    return NULL;
}
 
/* Readdirplus: return stat info with each entry */
static int my_readdirplus(const char *path, void *buf, 
                          fuse_fill_dir_t filler,
                          off_t offset, 
                          struct fuse_file_info *fi,
                          enum fuse_readdir_flags flags)
{
    struct stat stbuf;
    
    /* Fill stat info for each entry */
    memset(&stbuf, 0, sizeof(stbuf));
    stbuf.st_mode = S_IFREG | 0644;
    stbuf.st_size = 1234;
    stbuf.st_mtime = time(NULL);
    
    /* Pass stat info to filler - kernel won't need extra getattr calls */
    filler(buf, "filename.txt", &stbuf, 0, 
           FUSE_FILL_DIR_PLUS);
    
    return 0;
}

virtiofs: FUSE for VMs

Debugging FUSE Filesystems

Debugging FUSE filesystems is much easier than kernel filesystems—you can use standard debugging tools, add print statements, and attach debuggers without rebooting.

fuse_debugging
Bash
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
# ═══════════════════════════════════════════════════════════════
# Debug mode: foreground with verbose output
# ═══════════════════════════════════════════════════════════════
 
$ ./my_fuse_fs -f -d /mnt/point
# -f = foreground (don't daemonize)
# -d = debug (print every FUSE operation)
 
# Output shows every operation:
unique: 1, opcode: LOOKUP (1), nodeid: 1, insize: 48, pid: 12345
LOOKUP /hello.txt
   getattr /hello.txt
   unique: 1, success, outsize: 144
 
unique: 2, opcode: OPEN (14), nodeid: 2, insize: 48, pid: 12345
OPEN /hello.txt
   unique: 2, success, outsize: 32
 
# ═══════════════════════════════════════════════════════════════
# Attach gdb to running FUSE process
# ═══════════════════════════════════════════════════════════════
 
$ ps aux | grep my_fuse_fs
user     12345  0.0  0.1  12345  6789 ?  Sl   10:00   0:00 ./my_fuse_fs /mnt
 
$ sudo gdb -p 12345
 
# ═══════════════════════════════════════════════════════════════
# Trace FUSE operations with strace
# ═══════════════════════════════════════════════════════════════
 
# Watch the application side
$ strace cat /mnt/fuse_fs/file.txt
open("/mnt/fuse_fs/file.txt", O_RDONLY) = 3
read(3, "Hello from FUSE!\n", 4096) = 17
...
 
# Watch the FUSE daemon side
$ strace -p $(pgrep my_fuse_fs)
read(3, "\x30\x00\x00\x00\x01\x00\x00\x00...", 135168) = 48  # Read request
write(3, "\x90\x00\x00\x00\x00\x00\x00\x00...", 144) = 144    # Send reply
 
# ═══════════════════════════════════════════════════════════════
# Check FUSE connection status
# ═══════════════════════════════════════════════════════════════
 
$ cat /sys/fs/fuse/connections/*/waiting
0    # Requests waiting for daemon
 
$ cat /sys/fs/fuse/connections/*/congestion_threshold
0    # Congestion control
 
# If 'waiting' is high, daemon is too slow
 
# ═══════════════════════════════════════════════════════════════
# Force unmount stuck FUSE filesystem
# ═══════════════════════════════════════════════════════════════
 
# Normal unmount
$ fusermount -u /mnt/point
 
# Force unmount (if daemon is hung)
$ fusermount -zu /mnt/point      # Lazy unmount
 
# Kill daemon directly
$ pkill -9 my_fuse_fs
$ fusermount -u /mnt/point

Summary: FUSE

FUSE democratized filesystem development, enabling solutions from encrypted overlays to cloud storage mounts that would never have been practical as kernel modules.

Key Takeaways

•Architecture — Kernel module intercepts VFS calls, routes to userspace daemon via /dev/fuse
•Any language — Implement filesystems in Python, Go, Rust, C, or any language with FUSE bindings
•Safety — Bugs crash only your daemon, not the kernel; debugging with standard tools
•Unprivileged mounting — Users can mount FUSE filesystems without root access via fusermount
•Rich ecosystem — sshfs, gocryptfs, rclone, s3fs, NTFS-3G, and hundreds more
•Performance tradeoffs — Context switches add latency; use caching options for mitigation
•Security model — nosuid/nodev defaults, user isolation, explicit allow_other needed

Module complete:

This concludes our exploration of special file systems. You've learned about:

/proc — The process file system exposing kernel and process information
/sys — The sysfs unified device model interface
tmpfs — Memory-backed file storage with swap support
devtmpfs — Kernel-managed dynamic device file system
FUSE — The framework enabling userspace file system implementations

These special file systems form the infrastructure that makes modern Linux work—from system monitoring to device management to application-specific virtual file systems.

Module Complete

5 / 5