ext2_ext_attr.h revision dec5cd13fff821d1d3f6a922fbd986b3a86abb77 
1/*
2  File: linux/ext2_ext_attr.h
3
4  On-disk format of extended attributes for the ext2 filesystem.
5
6  (C) 2000 Andreas Gruenbacher, <a.gruenbacher@computer.org>
7*/
8
9#ifndef _EXT2_EXT_ATTR_H
10#define _EXT2_EXT_ATTR_H
11/* Magic value in attribute blocks */
12#define EXT2_EXT_ATTR_MAGIC_v1		0xEA010000
13#define EXT2_EXT_ATTR_MAGIC		0xEA020000
14
15/* Maximum number of references to one attribute block */
16#define EXT2_EXT_ATTR_REFCOUNT_MAX	1024
17
18struct ext2_ext_attr_header {
19	__u32	h_magic;	/* magic number for identification */
20	__u32	h_refcount;	/* reference count */
21	__u32	h_blocks;	/* number of disk blocks used */
22	__u32	h_hash;		/* hash value of all attributes */
23	__u32	h_reserved[4];	/* zero right now */
24};
25
26struct ext2_ext_attr_entry {
27	__u8	e_name_len;	/* length of name */
28	__u8	e_name_index;	/* attribute name index */
29	__u16	e_value_offs;	/* offset in disk block of value */
30	__u32	e_value_block;	/* disk block attribute is stored on (n/i) */
31	__u32	e_value_size;	/* size of attribute value */
32	__u32	e_hash;		/* hash value of name and value */
33#if 0
34	char	e_name[0];	/* attribute name */
35#endif
36};
37
38#define EXT2_EXT_ATTR_PAD_BITS		2
39#define EXT2_EXT_ATTR_PAD		((unsigned) 1<<EXT2_EXT_ATTR_PAD_BITS)
40#define EXT2_EXT_ATTR_ROUND		(EXT2_EXT_ATTR_PAD-1)
41#define EXT2_EXT_ATTR_LEN(name_len) \
42	(((name_len) + EXT2_EXT_ATTR_ROUND + \
43	sizeof(struct ext2_ext_attr_entry)) & ~EXT2_EXT_ATTR_ROUND)
44#define EXT2_EXT_ATTR_NEXT(entry) \
45	( (struct ext2_ext_attr_entry *)( \
46	  (char *)(entry) + EXT2_EXT_ATTR_LEN((entry)->e_name_len)) )
47#define EXT2_EXT_ATTR_SIZE(size) \
48	(((size) + EXT2_EXT_ATTR_ROUND) & ~EXT2_EXT_ATTR_ROUND)
49#define EXT2_EXT_IS_LAST_ENTRY(entry) (*((__u32 *)(entry)) == 0UL)
50#define EXT2_EXT_ATTR_NAME(entry) \
51	(((char *) (entry)) + sizeof(struct ext2_ext_attr_entry))
52#define EXT2_XATTR_LEN(name_len) \
53	(((name_len) + EXT2_EXT_ATTR_ROUND + \
54	sizeof(struct ext2_xattr_entry)) & ~EXT2_EXT_ATTR_ROUND)
55#define EXT2_XATTR_SIZE(size) \
56	(((size) + EXT2_EXT_ATTR_ROUND) & ~EXT2_EXT_ATTR_ROUND)
57
58#ifdef __KERNEL__
59# ifdef CONFIG_EXT2_FS_EXT_ATTR
60extern int ext2_get_ext_attr(struct inode *, const char *, char *, size_t, int);
61extern int ext2_set_ext_attr(struct inode *, const char *, char *, size_t, int);
62extern void ext2_ext_attr_free_inode(struct inode *inode);
63extern void ext2_ext_attr_put_super(struct super_block *sb);
64extern int ext2_ext_attr_init(void);
65extern void ext2_ext_attr_done(void);
66# else
67#  define ext2_get_ext_attr NULL
68#  define ext2_set_ext_attr NULL
69# endif
70#endif  /* __KERNEL__ */
71#endif  /* _EXT2_EXT_ATTR_H */
72