DragonOS/docs/locales/en/kernel/filesystem/overview.md

:::{note} AI Translation Notice

This document was automatically translated by Qwen/Qwen3-8B model, for reference only.

• Source document: kernel/filesystem/overview.md

• Translation time: 2025-05-19 01:41:36

• Translation model: Qwen/Qwen3-8B

Please report issues via Community Channel

:::

:::{note} Author of this article: Long Jin

Email: longjin@DragonOS.org :::

Overview

  In this article, we will introduce the architecture design of the DragonOS file system.

Overview

  As shown in the following diagram, the file system-related mechanisms of DragonOS mainly include the following parts:

• System call interface
• Virtual File System (VFS)
  • File abstraction (File)
  • Mount file system (MountFS)
• Specific file systems

            ┌─────────────────────────────────────────────────┐
            │                                                 │
Syscall:    │   sys_open, sys_read, sys_write, sys_close,     │
            │                                                 │
            │   sys_lseek, etc..                              │
            │                                                 │
            └───────────────────────┬─────────────────────────┘
                                    │
                                    │
    VFS:                     ┌──────▼─────┐
                             │            │
                             │    File    │
                             │            │
                             └──────┬─────┘
                                    │
                           ┌────────▼────────┐
                           │                 │
                           │     MountFS     │
                           │                 │
                           └────┬────────────┘
                                │
   Filesystems:   ┌─────────────┼─────────────┬────────────┐
                  │             │             │            │
            ┌─────▼─────┐ ┌─────▼─────┐ ┌─────▼────┐ ┌─────▼─────┐
            │           │ │           │ │          │ │           │
            │    FAT    │ │   DevFS   │ │  ProcFS  │ │   RamFS   │
            │           │ │           │ │          │ │           │
            └───────────┘ └───────────┘ └──────────┘ └───────────┘

System Call Interface

  The file system-related system call interfaces of DragonOS mainly include the following:

• sys_open: Open file
• sys_read: Read file
• sys_write: Write file
• sys_close: Close file
• sys_lseek: Set file pointer position
• sys_mkdir: Create directory
• sys_unlink_at: Delete file or directory (distinguish between file and directory by parameter flag)
• sys_ioctl: Control device (not implemented)
• sys_fstat: Get file status (not implemented)
• sys_fsync: Synchronize file (not implemented)
• sys_ftruncate: Truncate file (not implemented)
• sys_fchmod: Modify file permissions (not implemented)
• Other system call interfaces (not implemented)

  For the specific meaning of the interfaces, you can refer to the relevant documentation of Linux.

Virtual File System (VFS)

  VFS is the core of the DragonOS file system, providing a unified set of file system interfaces, allowing DragonOS to support various different file systems. The main functions of VFS include:

• Provide a unified file system interface
• Provide file system mounting and unmounting mechanism (MountFS)
• Provide file abstraction (File)
• Provide file system abstraction (FileSystem)
• Provide IndexNode abstraction
• Provide file system caching and synchronization mechanism (not implemented yet)

  For detailed introduction of VFS, please see DragonOS Virtual File System.

Specific File Systems

  The file systems currently supported by DragonOS include:

• FAT file system (FAT12, FAT16, FAT32)
• DevFS
• ProcFS
• RamFS