Documentation/filesystems/fuse/fuse.rst

Source file repositories/reference/linux-study-clean/Documentation/filesystems/fuse/fuse.rst

File Facts

System: Linux kernel
Corpus path: Documentation/filesystems/fuse/fuse.rst
Extension: .rst
Size: 17902 bytes
Lines: 441
Domain: Support Tooling And Documentation
Bucket: Documentation
Inferred role: Support Tooling And Documentation: documentation
Status: atlas-only

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
Touches user memory; correctness depends on fault-safe copying and privilege boundary handling.

Dependency Surface

No C-style include directives detected by the generator.

Detected Declarations

No top-level syscall, struct, function, initcall, or export declaration detected by the generator.

Annotated Snippet

.. SPDX-License-Identifier: GPL-2.0

=============
FUSE Overview
=============

Definitions
===========

Userspace filesystem:
  A filesystem in which data and metadata are provided by an ordinary
  userspace process.  The filesystem can be accessed normally through
  the kernel interface.

Filesystem daemon:
  The process(es) providing the data and metadata of the filesystem.

Non-privileged mount (or user mount):
  A userspace filesystem mounted by a non-privileged (non-root) user.
  The filesystem daemon is running with the privileges of the mounting
  user.  NOTE: this is not the same as mounts allowed with the "user"
  option in /etc/fstab, which is not discussed here.

Filesystem connection:
  A connection between the filesystem daemon and the kernel.  The
  connection exists until either the daemon dies, or the filesystem is
  umounted.  Note that detaching (or lazy umounting) the filesystem
  does *not* break the connection, in this case it will exist until
  the last reference to the filesystem is released.

Mount owner:
  The user who does the mounting.

User:
  The user who is performing filesystem operations.

What is FUSE?
=============

FUSE is a userspace filesystem framework.  It consists of a kernel
module (fuse.ko), a userspace library (libfuse.*) and a mount utility
(fusermount).

One of the most important features of FUSE is allowing secure,
non-privileged mounts.  This opens up new possibilities for the use of
filesystems.  A good example is sshfs: a secure network filesystem
using the sftp protocol.

The userspace library and utilities are available from the
`FUSE homepage: <https://github.com/libfuse/>`_

Filesystem type
===============

The filesystem type given to mount(2) can be one of the following:

    fuse
      This is the usual way to mount a FUSE filesystem.  The first
      argument of the mount system call may contain an arbitrary string,
      which is not interpreted by the kernel.

    fuseblk
      The filesystem is block device based.  The first argument of the
      mount system call is interpreted as the name of the device.

Mount options
=============

fd=N
  The file descriptor to use for communication between the userspace

Annotation

Atlas domain: Support Tooling And Documentation / Documentation.
Implementation status: atlas-only.
This snippet crosses the user/kernel memory boundary; validate fault handling and access checks before translating the pattern.

Implementation Notes

This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.