VFS

Virtual File System. More...

Collaboration diagram for VFS:

Modules
	Virtual filesystem
	Virtual nodes

Data Structures
struct	vfs_fs
	Represents a file system format. More...

Macros
#define	DECLARE_FILESYSTEM(fs_name, fs_new)
	Declare a new available filesystem. More...

Functions
static bool	vfs_exist (const char *path)

Detailed Description

Virtual Filesystem

The virtual is an abstraction over filesystems used to separate the high level interface from the low level fs-dependent implementation. It also allows for computing a path which spans over multiple different imbricked filesystems, effectively viewing it as a single big filesystem from the user's POV.

Design

The VFS splits each mounted filesystem into 2 parts:

• The virtual filesystem: The filesystem as a whole
• Virtual nodes: The individual components (files, dirs, ...) that make up this filesystem

The VFS driver keeps track of all the present virtual filesystem, and addresses them in order to find a requested path. When "opening" a file, we instead ask the corresponding VFS to create the VNODE which corresponds to this file, and interact with it instead. All the filesystem dependant logic is hidden from the VFS driver.

See also

http://www.cs.fsu.edu/~awang/courses/cop5611_s2024/vnode.pdf

Macro Definition Documentation

DECLARE_FILESYSTEM

#define DECLARE_FILESYSTEM	(		fs_name,
			fs_new
	)

Value:

    SECTION(".data.vfs.filesystems")             \
    MAYBE_UNUSED                                 \
    static vfs_fs_t fs_name##_fs_declaration = { \
        .name = stringify(fs_name),              \
        .new = fs_new,                           \
    }

A file system needs to be declared using this macro for the VFS driver to be able to mount it using vfs_mount.

Parameters

fs_name	The name of the filesystem
fw_new	The function used to create a new instance of this filesystem

Function Documentation

vfs_exist()

static bool vfs_exist ( const char *  path )

inlinestatic

Returns

Whether a path exists in the current VFS.