ext2: inodes, and the blocks of a file. More...

#include <ext2.h>
#include <ds/bitmap.h>

Macros
#define	SLOT_SINGLY EXT2_DIRECT_POINTERS

Functions
static off_t	ext2_inode_off (struct ext2 *desc, ino_t ino)
	Returns where an inode is on the disk, in bytes, or -EINVAL for an inode number that doesn't exist.
int	ext2_inode_read (struct ext2 desc, ino_t ino, struct ext2_inode ref)
	Reads an inode from the disk.
int	ext2_inode_write (struct ext2 desc, ino_t ino, struct ext2_inode ext2_inode)
	Writes an inode to the disk.
static int	block_tree (struct ext2 desc, size_t idx, int slot, size_t *rel)
	Finds where block idx of a file is in its tree: the slot of the inode it hangs from (0 to 11 for the direct pointers, 12 to 14 for the indirect ones) in slot, and its index under that slot in rel.
static uint32_t	slot_get (struct ext2_inode *inode, int slot)
	Returns the block pointer in a slot of an inode.
static void	slot_set (struct ext2_inode *inode, int slot, uint32_t block)
	Sets the block pointer in a slot of an inode.
static size_t	tree_span (struct ext2 *desc, int depth)
	Returns how many data blocks are under one pointer of an indirect block that is depth levels above them.
int	ext2_inode_block_read (struct ext2 desc, struct ext2_inode inode, size_t idx, void *buf)
	Reads a block of a file.
static int	ext2_inode_block_alloc (struct ext2 desc, struct ext2_inode inode, uint32_t *block)
	Allocates a block for a file, and counts it in the inode's blocks, which counts 512-byte sectors.
static int	ext2_indirect_block_get (struct ext2 desc, struct ext2_inode inode, uint32_t table, size_t idx, uint32_t *block)
	Gets the block pointer at index idx of the indirect block table, allocating a block there if there's none yet.
int	ext2_inode_block_write (struct ext2 desc, struct ext2_inode inode, uint32_t inode_nr, size_t idx, void *buf)
	Writes a block of a file, allocating it and the indirect blocks above it if they don't exist yet.
int	ext2_inode_alloc (struct ext2 desc, ino_t ino)
	Allocates a free inode: its bit is set in its group's inode bitmap, and the free counts go down.

Detailed Description

ext2: inodes, and the blocks of a file.

A file's blocks are found through its inode's 12 direct pointers, then a singly, a doubly and a triply indirect one: a tree of blocks of pointers.

Definition in file inode.c.

Macro Definition Documentation

◆ SLOT_SINGLY

#define SLOT_SINGLY EXT2_DIRECT_POINTERS

Definition at line 63 of file inode.c.

Referenced by block_tree(), slot_get(), and slot_set().

Function Documentation

◆ block_tree()

int block_tree	(	struct ext2 *	desc,
		size_t	idx,
		int *	slot,
		size_t *	rel )

static

Finds where block idx of a file is in its tree: the slot of the inode it hangs from (0 to 11 for the direct pointers, 12 to 14 for the indirect ones) in *slot, and its index under that slot in *rel.

Returns the depth: 0 if the slot points to the block itself, 1 to 3 for the levels of indirect blocks above it, or -EFBIG past the largest file.

Definition at line 73 of file inode.c.

References block_tree(), ext2::bs, EXT2_DIRECT_POINTERS, and SLOT_SINGLY.

Referenced by block_tree(), ext2_inode_block_read(), and ext2_inode_block_write().

◆ ext2_indirect_block_get()

int ext2_indirect_block_get	(	struct ext2 *	desc,
		struct ext2_inode *	inode,
		uint32_t	table,
		size_t	idx,
		uint32_t *	block )

static

Gets the block pointer at index idx of the indirect block table, allocating a block there if there's none yet.

Definition at line 200 of file inode.c.

References ext2::bs, ext2_block_read(), ext2_block_write(), ext2_indirect_block_get(), ext2_inode_block_alloc(), kfree(), kmalloc(), and table().

Referenced by ext2_indirect_block_get(), and ext2_inode_block_write().

◆ ext2_inode_alloc()

int ext2_inode_alloc	(	struct ext2 *	desc,
		ino_t *	ino )

Allocates a free inode: its bit is set in its group's inode bitmap, and the free counts go down.

A bitmap that couldn't be read isn't written back.

Parameters

desc	the mounted filesystem
ino	set to the inode number

Returns: 0, -ENOSPC if there's no free inode, -ENOMEM, or an I/O error

Definition at line 281 of file inode.c.

References ext2::bs, ext2_bgd_table_rewrite(), ext2_block_read(), ext2_block_write(), ext2_inode_alloc(), ext2_superblock_rewrite(), ext2_group::free_inodes, ext2_superblock::free_inodes, ext2_superblock::ginodes, ext2::groups, ext2_group::imap, kfree(), kmalloc(), LOG_DEBUG, bitmap::map, bitmap::max_idx, ext2::ngroups, and ext2::superblock.

Referenced by ext2_inode_alloc(), and ext2_vmknod().

◆ ext2_inode_block_alloc()

int ext2_inode_block_alloc	(	struct ext2 *	desc,
		struct ext2_inode *	inode,
		uint32_t *	block )

static

Allocates a block for a file, and counts it in the inode's blocks, which counts 512-byte sectors.

Definition at line 187 of file inode.c.

References ext2_inode::blocks, ext2::bs, ext2_block_alloc(), and ext2_inode_block_alloc().

Referenced by ext2_indirect_block_get(), ext2_inode_block_alloc(), and ext2_inode_block_write().

◆ ext2_inode_block_read()

int ext2_inode_block_read	(	struct ext2 *	desc,
		struct ext2_inode *	inode,
		size_t	idx,
		void *	buf )

Reads a block of a file.

A block that was never written (the file is sparse there) reads as zeros.

Parameters

desc	the mounted filesystem
inode	the file's inode
idx	the block's index in the file
buf	where it goes, a block's size

Returns: 0, -EFBIG past the largest file, -ENOMEM, or an I/O error

Definition at line 144 of file inode.c.

References block_tree(), ext2::bs, ext2_block_read(), ext2_inode_block_read(), kfree(), kmalloc(), memset(), slot_get(), table(), and tree_span().

Referenced by dentry_update(), ext2_dentry_create(), ext2_dentry_find(), ext2_inode_block_read(), ext2_read(), ext2_readdir(), ext2_trunc(), and ext2_write().

◆ ext2_inode_block_write()

int ext2_inode_block_write	(	struct ext2 *	desc,
		struct ext2_inode *	inode,
		uint32_t	inode_nr,
		size_t	idx,
		void *	buf )

Writes a block of a file, allocating it and the indirect blocks above it if they don't exist yet.

The inode is written back if blocks were allocated.

Parameters

desc	the mounted filesystem
inode	the file's inode
inode_nr	its inode number
idx	the block's index in the file
buf	the block's new contents

Returns: 0, -EFBIG, -ENOSPC, -ENOMEM, or an I/O error

Definition at line 235 of file inode.c.

References block_tree(), ext2_inode::blocks, ext2_block_write(), ext2_indirect_block_get(), ext2_inode_block_alloc(), ext2_inode_block_write(), ext2_inode_write(), slot_get(), slot_set(), and tree_span().

Referenced by dentry_update(), ext2_dentry_create(), ext2_inode_block_write(), ext2_trunc(), ext2_vmknod(), and ext2_write().

◆ ext2_inode_off()

off_t ext2_inode_off	(	struct ext2 *	desc,
		ino_t	ino )

inlinestatic

Returns where an inode is on the disk, in bytes, or -EINVAL for an inode number that doesn't exist.

Definition at line 12 of file inode.c.

References ext2::bs, ext2_inode_off(), ext2_superblock::ginodes, ext2::groups, ext2::inode_size, ext2_group::inodes, ext2_superblock::ninodes, and ext2::superblock.

Referenced by ext2_inode_off(), ext2_inode_read(), and ext2_inode_write().

◆ ext2_inode_read()

int ext2_inode_read	(	struct ext2 *	desc,
		ino_t	ino,
		struct ext2_inode *	ref )

Reads an inode from the disk.

Parameters

desc	the mounted filesystem
ino	the inode number
ref	where it goes; NULL only checks the number

Returns: 0, -EINVAL for a bad inode number, or an I/O error

Definition at line 33 of file inode.c.

References ext2_inode_off(), ext2_inode_read(), and ext2_io().

Referenced by dentry_update(), ext2_dentry_create(), ext2_finddir(), ext2_inode_build(), ext2_inode_discard(), ext2_inode_read(), ext2_inode_sync(), ext2_read(), ext2_readdir(), ext2_setattr(), ext2_trunc(), ext2_vlink(), ext2_vmknod(), ext2_vrename(), and ext2_write().

◆ ext2_inode_write()

int ext2_inode_write	(	struct ext2 *	desc,
		ino_t	ino,
		struct ext2_inode *	ext2_inode )

Writes an inode to the disk.

Parameters

desc	the mounted filesystem
ino	the inode number
ext2_inode	the inode

Returns: 0, -EINVAL for a bad inode number, or an I/O error

Definition at line 51 of file inode.c.

References ext2_inode_off(), ext2_inode_write(), and ext2_io().

Referenced by ext2_dentry_create(), ext2_inode_block_write(), ext2_inode_discard(), ext2_inode_sync(), ext2_inode_write(), ext2_setattr(), ext2_trunc(), ext2_vmknod(), and ext2_write().

◆ slot_get()

uint32_t slot_get	(	struct ext2_inode *	inode,
		int	slot )

static

Returns the block pointer in a slot of an inode.

A switch rather than an array, because the inode is packed, so its fields can't be pointed to.

Definition at line 101 of file inode.c.

References ext2_inode::direct_pointer, ext2_inode::doubly_indirect_pointer, ext2_inode::singly_indirect_pointer, slot_get(), SLOT_SINGLY, and ext2_inode::triply_indirect_pointer.

Referenced by ext2_inode_block_read(), ext2_inode_block_write(), and slot_get().

◆ slot_set()

void slot_set	(	struct ext2_inode *	inode,
		int	slot,
		uint32_t	block )

static

Sets the block pointer in a slot of an inode.

Definition at line 112 of file inode.c.

References ext2_inode::direct_pointer, ext2_inode::doubly_indirect_pointer, ext2_inode::singly_indirect_pointer, slot_set(), SLOT_SINGLY, and ext2_inode::triply_indirect_pointer.

Referenced by ext2_inode_block_write(), and slot_set().

◆ tree_span()

size_t tree_span	(	struct ext2 *	desc,
		int	depth )

static

Returns how many data blocks are under one pointer of an indirect block that is depth levels above them.

Definition at line 124 of file inode.c.

References ext2::bs, and tree_span().

Referenced by ext2_inode_block_read(), ext2_inode_block_write(), and tree_span().

Macros

Functions

Detailed Description

Macro Definition Documentation

◆ SLOT_SINGLY

Function Documentation

◆ block_tree()

◆ ext2_indirect_block_get()

◆ ext2_inode_alloc()

◆ ext2_inode_block_alloc()

◆ ext2_inode_block_read()

◆ ext2_inode_block_write()

◆ ext2_inode_off()

◆ ext2_inode_read()

◆ ext2_inode_write()

◆ slot_get()

◆ slot_set()

◆ tree_span()