2
* Copyright (c) 2000-2001,2005 Silicon Graphics, Inc.
5
* This program is free software; you can redistribute it and/or
6
* modify it under the terms of the GNU General Public License as
7
* published by the Free Software Foundation.
9
* This program is distributed in the hope that it would be useful,
10
* but WITHOUT ANY WARRANTY; without even the implied warranty of
11
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12
* GNU General Public License for more details.
14
* You should have received a copy of the GNU General Public License
15
* along with this program; if not, write the Free Software Foundation,
16
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
#ifndef __XFS_DIR_LEAF_H__
19
#define __XFS_DIR_LEAF_H__
22
* Version 1 Directory layout, internal structure, access macros, etc.
23
* to allow various xfsprogs tools to read these structures.
25
* Large directories are structured around Btrees where all the data
26
* elements are in the leaf nodes. Filenames are hashed into an int,
27
* then that int is used as the index into the Btree. Since the hashval
28
* of a filename may not be unique, we may have duplicate keys. The
29
* internal links in the Btree are logical block offsets into the file.
32
/*========================================================================
33
* Directory Structure when equal to XFS_LBSIZE(mp) bytes.
34
*========================================================================*/
37
* This is the structure of the leaf nodes in the Btree.
39
* Struct leaf_entry's are packed from the top. Names grow from the bottom
40
* but are not packed. The freemap contains run-length-encoded entries
41
* for the free bytes after the leaf_entry's, but only the N largest such,
42
* smaller runs are dropped. When the freemap doesn't show enough space
43
* for an allocation, we compact the namelist area and try again. If we
44
* still don't have enough space, then we have to split the block.
46
* Since we have duplicate hash keys, for each key that matches, compare
47
* the actual string. The root and intermediate node search always takes
48
* the first-in-the-block key match found, so we should only have to work
49
* "forw"ard. If none matches, continue with the "forw"ard leaf nodes
50
* until the hash key changes or the filename is found.
52
* The parent directory and the self-pointer are explicitly represented
53
* (ie: there are entries for "." and "..").
55
* Note that the count being a __uint16_t limits us to something like a
56
* blocksize of 1.3MB in the face of worst case (short) filenames.
59
#define XFS_DIR_LEAF_MAGIC 0xfeeb
61
#define XFS_DIR_LEAF_MAPSIZE 3 /* how many freespace slots */
64
typedef struct xfs_dir_leaf_map { /* RLE map of free bytes */
65
__be16 base; /* base of free region */
66
__be16 size; /* run length of free region */
69
typedef struct xfs_dir_leaf_hdr { /* constant-structure header block */
70
xfs_da_blkinfo_t info; /* block type, links, etc. */
71
__be16 count; /* count of active leaf_entry's */
72
__be16 namebytes; /* num bytes of name strings stored */
73
__be16 firstused; /* first used byte in name area */
74
__u8 holes; /* != 0 if blk needs compaction */
76
xfs_dir_leaf_map_t freemap[XFS_DIR_LEAF_MAPSIZE];
79
typedef struct xfs_dir_leaf_entry { /* sorted on key, not name */
80
__be32 hashval; /* hash value of name */
81
__be16 nameidx; /* index into buffer of name */
82
__u8 namelen; /* length of name string */
84
} xfs_dir_leaf_entry_t;
86
typedef struct xfs_dir_leaf_name {
87
xfs_dir_ino_t inumber; /* inode number for this key */
88
__u8 name[1]; /* name string itself */
89
} xfs_dir_leaf_name_t;
91
typedef struct xfs_dir_leafblock {
92
xfs_dir_leaf_hdr_t hdr; /* constant-structure header block */
93
xfs_dir_leaf_entry_t entries[1]; /* var sized array */
94
xfs_dir_leaf_name_t namelist[1]; /* grows from bottom of buf */
95
} xfs_dir_leafblock_t;
97
static inline int xfs_dir_leaf_entsize_byname(int len)
99
return (uint)sizeof(xfs_dir_leaf_name_t)-1 + len;
102
static inline int xfs_dir_leaf_entsize_byentry(xfs_dir_leaf_entry_t *entry)
104
return (uint)sizeof(xfs_dir_leaf_name_t)-1 + (entry)->namelen;
107
static inline xfs_dir_leaf_name_t *
108
xfs_dir_leaf_namestruct(xfs_dir_leafblock_t *leafp, int offset)
110
return (xfs_dir_leaf_name_t *)&((char *)(leafp))[offset];
113
#endif /* __XFS_DIR_LEAF_H__ */
added
removed
include/xfs_dir_leaf.h
