Linux File System 1---The introduction of VFS

1. Introduction

The series of articles on document management is mainly about the Chen Li of the Document System management Knowledge lecture by teacher June.

Linux can support different file systems, which originate from UNIX file systems and are a feature of UNIX file systems.

2. Introduction of Virtual File system

The file system supported by the diagram kernel

Cat/proc/filesystems can be used to view the current kernel running file system, file system not only as a file management mechanism, but also as a other mechanism to join the VFS, such as Cgroup, etc.

　　　　

Figure File System directory structure

Linux files are unified, located in a directory tree, and process management is the concept of same strain.

Figure VFS File System architecture diagram

VFS provides a unified interface for user space, different file systems need to implement these interfaces, for the device files, the driver also to implement the corresponding interface, which embodies a mechanism and separation of the concept.

3.file_system_type Structural Body

Figure File_system_type Structural Body

• The Linux kernel uses the VFS (Virtual Filesystem Switch) framework
• Each filesystem needs to be registered in the VFS, which is populated with a struct file_system_type structure
• This structure describes the name of the file system and a message that points to the address of the corresponding VFS super block read routine

　　

The organizational structure of Figure File_system_type

• The kernel uses the linked list to organize each registered file system, with the list header as File_systems

4. Example: printing file_system_type information

Available through Cat/proc/kallsyms | WC can count the number of symbols in the kernel.

Because some symbols in the kernel are not exported, access is not allowed through cat/proc/kallsyms | grep File_systems can print out the address of file_systems and it can be manipulated.

　　　　　　　　　

Linux File System 1---The introduction of VFS