ext2_ext_attr.h revision 7746cad695fb6708f2e1e68bc16eddcf75e4a281 
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/* Magic value in attribute blocks */
10#define EXT2_EXT_ATTR_MAGIC		0xEA010000
11
12/* Maximum number of references to one attribute block */
13#define EXT2_EXT_ATTR_REFCOUNT_MAX	1024
14
15struct ext2_ext_attr_header {
16	__u32	h_magic;	/* magic number for identification */
17	__u32	h_refcount;	/* reference count */
18	__u32	h_blocks;	/* number of disk blocks used */
19	__u32	h_hash;		/* hash value of all attributes */
20	__u32	h_reserved[4];	/* zero right now */
21};
22
23struct ext2_ext_attr_entry {
24	__u8	e_name_len;	/* length of name */
25	__u8	e_name_index;	/* index into table of names (n/i) */
26	__u16	e_value_offs;	/* offset in disk block of value */
27	__u32	e_value_block;	/* disk block attribute is stored on (n/i) */
28	__u32	e_value_size;	/* size of attribute value */
29	__u32	e_hash;		/* hash value of name and value */
30	char	e_name[0];	/* attribute name */
31};
32
33#define EXT2_EXT_ATTR_PAD_BITS		2
34#define EXT2_EXT_ATTR_PAD		(1<<EXT2_EXT_ATTR_PAD_BITS)
35#define EXT2_EXT_ATTR_ROUND		(EXT2_EXT_ATTR_PAD-1)
36#define EXT2_EXT_ATTR_LEN(name_len) \
37	(((name_len) + EXT2_EXT_ATTR_ROUND + \
38	sizeof(struct ext2_ext_attr_entry)) & ~EXT2_EXT_ATTR_ROUND)
39#define EXT2_EXT_ATTR_NEXT(entry) \
40	( (struct ext2_ext_attr_entry *)( \
41	  (char *)(entry) + EXT2_EXT_ATTR_LEN((entry)->e_name_len)) )
42#define EXT2_EXT_ATTR_SIZE(size) \
43	(((size) + EXT2_EXT_ATTR_ROUND) & ~EXT2_EXT_ATTR_ROUND)
44
45#ifdef __KERNEL__
46# ifdef CONFIG_EXT2_FS_EXT_ATTR
47extern int ext2_get_ext_attr(struct inode *, const char *, char *, size_t, int);
48extern int ext2_set_ext_attr(struct inode *, const char *, char *, size_t, int);
49extern void ext2_ext_attr_free_inode(struct inode *inode);
50extern void ext2_ext_attr_put_super(struct super_block *sb);
51extern int ext2_ext_attr_init(void);
52extern void ext2_ext_attr_done(void);
53# else
54#  define ext2_get_ext_attr NULL
55#  define ext2_set_ext_attr NULL
56# endif
57#endif  /* __KERNEL__ */
58
59