1 /* $OpenBSD: ext2fs.h,v 1.12 2007/06/02 00:45:50 pedro Exp $ */
2 /* $NetBSD: ext2fs.h,v 1.10 2000/01/28 16:00:23 bouyer Exp $ */
3
4 /*
5 * Copyright (c) 1997 Manuel Bouyer.
6 * Copyright (c) 1982, 1986, 1993
7 * The Regents of the University of California. All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * @(#)fs.h 8.10 (Berkeley) 10/27/94
34 * Modified for ext2fs by Manuel Bouyer.
35 */
36
37 #include <machine/endian.h>
38
39 /*
40 * Each disk drive contains some number of file systems.
41 * A file system consists of a number of cylinder groups.
42 * Each cylinder group has inodes and data.
43 *
44 * A file system is described by its super-block, which in turn
45 * describes the cylinder groups. The super-block is critical
46 * data and is replicated in each cylinder group to protect against
47 * catastrophic loss. This is done at `newfs' time and the critical
48 * super-block data does not change, so the copies need not be
49 * referenced further unless disaster strikes.
50 *
51 * The first boot and super blocks are given in absolute disk addresses.
52 * The byte-offset forms are preferred, as they don't imply a sector size.
53 */
54 #define BBSIZE 1024
55 #define SBSIZE 1024
56 #define BBOFF ((off_t)(0))
57 #define SBOFF ((off_t)(BBOFF + BBSIZE))
58 #define BBLOCK ((daddr_t)(0))
59 #define SBLOCK ((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
60
61 /*
62 * Addresses stored in inodes are capable of addressing blocks
63 * XXX
64 */
65
66 /*
67 * MINBSIZE is the smallest allowable block size.
68 * MINBSIZE must be big enough to hold a cylinder group block,
69 * thus changes to (struct cg) must keep its size within MINBSIZE.
70 * Note that super blocks are always of size SBSIZE,
71 * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
72 */
73 #define LOG_MINBSIZE 10
74 #define MINBSIZE (1 << LOG_MINBSIZE)
75
76 /*
77 * The path name on which the file system is mounted is maintained
78 * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
79 * the super block for this name.
80 */
81 #define MAXMNTLEN 512
82
83 /*
84 * MINFREE gives the minimum acceptable percentage of file system
85 * blocks which may be free. If the freelist drops below this level
86 * only the superuser may continue to allocate blocks. This may
87 * be set to 0 if no reserve of free blocks is deemed necessary,
88 * however throughput drops by fifty percent if the file system
89 * is run at between 95% and 100% full; thus the minimum default
90 * value of fs_minfree is 5%. However, to get good clustering
91 * performance, 10% is a better choice. hence we use 10% as our
92 * default value. With 10% free space, fragmentation is not a
93 * problem, so we choose to optimize for time.
94 */
95 #define MINFREE 5
96
97 /*
98 * Super block for an ext2fs file system.
99 */
100 struct ext2fs {
101 u_int32_t e2fs_icount; /* Inode count */
102 u_int32_t e2fs_bcount; /* blocks count */
103 u_int32_t e2fs_rbcount; /* reserved blocks count */
104 u_int32_t e2fs_fbcount; /* free blocks count */
105 u_int32_t e2fs_ficount; /* free inodes count */
106 u_int32_t e2fs_first_dblock; /* first data block */
107 u_int32_t e2fs_log_bsize; /* block size = 1024*(2^e2fs_log_bsize) */
108 u_int32_t e2fs_fsize; /* fragment size */
109 u_int32_t e2fs_bpg; /* blocks per group */
110 u_int32_t e2fs_fpg; /* frags per group */
111 u_int32_t e2fs_ipg; /* inodes per group */
112 u_int32_t e2fs_mtime; /* mount time */
113 u_int32_t e2fs_wtime; /* write time */
114 u_int16_t e2fs_mnt_count; /* mount count */
115 u_int16_t e2fs_max_mnt_count; /* max mount count */
116 u_int16_t e2fs_magic; /* magic number */
117 u_int16_t e2fs_state; /* file system state */
118 u_int16_t e2fs_beh; /* behavior on errors */
119 u_int16_t e2fs_minrev; /* minor revision level */
120 u_int32_t e2fs_lastfsck; /* time of last fsck */
121 u_int32_t e2fs_fsckintv; /* max time between fscks */
122 u_int32_t e2fs_creator; /* creator OS */
123 u_int32_t e2fs_rev; /* revision level */
124 u_int16_t e2fs_ruid; /* default uid for reserved blocks */
125 u_int16_t e2fs_rgid; /* default gid for reserved blocks */
126 /* EXT2_DYNAMIC_REV superblocks */
127 u_int32_t e2fs_first_ino; /* first non-reserved inode */
128 u_int16_t e2fs_inode_size; /* size of inode structure */
129 u_int16_t e2fs_block_group_nr; /* block grp number of this sblk*/
130 u_int32_t e2fs_features_compat; /* compatible feature set */
131 u_int32_t e2fs_features_incompat; /* incompatible feature set */
132 u_int32_t e2fs_features_rocompat; /* RO-compatible feature set */
133 u_int8_t e2fs_uuid[16]; /* 128-bit uuid for volume */
134 char e2fs_vname[16]; /* volume name */
135 char e2fs_fsmnt[64]; /* name mounted on */
136 u_int32_t e2fs_algo; /* For compression */
137 u_int8_t e2fs_prealloc; /* # of blocks to preallocate */
138 u_int8_t e2fs_dir_prealloc; /* # of blocks to preallocate for dir */
139 u_int16_t pad1;
140 u_int32_t reserved2[204];
141 };
142
143
144 /* in-memory data for ext2fs */
145 struct m_ext2fs {
146 struct ext2fs e2fs;
147 u_char e2fs_fsmnt[MAXMNTLEN]; /* name mounted on */
148 int8_t e2fs_ronly; /* mounted read-only flag */
149 int8_t e2fs_fmod; /* super block modified flag */
150 int32_t e2fs_bsize; /* block size */
151 int32_t e2fs_bshift; /* ``lblkno'' calc of logical blkno */
152 int32_t e2fs_bmask; /* ``blkoff'' calc of blk offsets */
153 int64_t e2fs_qbmask; /* ~fs_bmask - for use with quad size */
154 int32_t e2fs_fsbtodb; /* fsbtodb and dbtofsb shift constant */
155 int32_t e2fs_ncg; /* number of cylinder groups */
156 int32_t e2fs_ngdb; /* number of group descriptor block */
157 int32_t e2fs_ipb; /* number of inodes per block */
158 int32_t e2fs_itpg; /* number of inode table per group */
159 struct ext2_gd *e2fs_gd; /* group descriptors */
160 };
161
162
163
164 /*
165 * Filesystem identification
166 */
167 #define E2FS_MAGIC 0xef53 /* the ext2fs magic number */
168 #define E2FS_REV0 0 /* revision levels */
169 #define E2FS_REV1 1 /* revision levels */
170
171 /* compatible/imcompatible features */
172 #define EXT2F_COMPAT_PREALLOC 0x0001
173
174 #define EXT2F_ROCOMPAT_SPARSESUPER 0x0001
175 #define EXT2F_ROCOMPAT_LARGEFILE 0x0002
176 #define EXT2F_ROCOMPAT_BTREE_DIR 0x0004
177
178 #define EXT2F_INCOMPAT_COMP 0x0001
179 #define EXT2F_INCOMPAT_FTYPE 0x0002
180 #define EXT2F_INCOMPAT_RECOVER 0x0004
181 #define EXT2F_INCOMPAT_JOURNAL_DEV 0x0008
182
183 /* features supported in this implementation */
184 #define EXT2F_COMPAT_SUPP 0x0000
185 #define EXT2F_ROCOMPAT_SUPP (EXT2F_ROCOMPAT_SPARSESUPER \
186 | EXT2F_ROCOMPAT_LARGEFILE)
187 #define EXT2F_INCOMPAT_SUPP EXT2F_INCOMPAT_FTYPE
188
189 /*
190 * OS identification
191 */
192 #define E2FS_OS_LINUX 0
193 #define E2FS_OS_HURD 1
194 #define E2FS_OS_MASIX 2
195
196 /*
197 * Filesystem clean flags
198 */
199 #define E2FS_ISCLEAN 0x01
200 #define E2FS_ERRORS 0x02
201
202 /* ext2 file system block group descriptor */
203
204 struct ext2_gd {
205 u_int32_t ext2bgd_b_bitmap; /* blocks bitmap block */
206 u_int32_t ext2bgd_i_bitmap; /* inodes bitmap block */
207 u_int32_t ext2bgd_i_tables; /* inodes table block */
208 u_int16_t ext2bgd_nbfree; /* number of free blocks */
209 u_int16_t ext2bgd_nifree; /* number of free inodes */
210 u_int16_t ext2bgd_ndirs; /* number of directories */
211 u_int16_t reserved;
212 u_int32_t reserved2[3];
213 };
214
215 /*
216 * If the EXT2F_ROCOMPAT_SPARSESUPER flag is set, the cylinder group has a
217 * copy of the super and cylinder group descriptors blocks only if it's
218 * a power of 3, 5 or 7
219 */
220
221 static __inline__ int cg_has_sb(int) __attribute__((__unused__));
222 static __inline int
223 cg_has_sb(i)
224 int i;
225 {
226 int a3 ,a5 , a7;
227
228 if (i == 0 || i == 1)
229 return 1;
230 for (a3 = 3, a5 = 5, a7 = 7;
231 a3 <= i || a5 <= i || a7 <= i;
232 a3 *= 3, a5 *= 5, a7 *= 7)
233 if (i == a3 || i == a5 || i == a7)
234 return 1;
235 return 0;
236 }
237
238 /*
239 * EXT2FS metadatas are stored in little-endian byte order. These macros
240 * helps reading theses metadatas
241 */
242
243 #define h2fs16(x) htole16(x)
244 #define h2fs32(x) htole32(x)
245 #define fs2h16(x) letoh16(x)
246 #define fs2h32(x) letoh32(x)
247 #if BYTE_ORDER == LITTLE_ENDIAN
248 #define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE);
249 #define e2fs_cgload(old, new, size) memcpy((new), (old), (size));
250 #define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE);
251 #define e2fs_cgsave(old, new, size) memcpy((new), (old), (size));
252 #else
253 void e2fs_sb_bswap(struct ext2fs *, struct ext2fs *);
254 void e2fs_cg_bswap(struct ext2_gd *, struct ext2_gd *, int);
255 #define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new))
256 #define e2fs_cgload(old, new, size) e2fs_cg_bswap((old), (new), (size));
257 #define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new))
258 #define e2fs_cgsave(old, new, size) e2fs_cg_bswap((old), (new), (size));
259 #endif
260
261 /*
262 * Turn file system block numbers into disk block addresses.
263 * This maps file system blocks to device size blocks.
264 */
265 #define fsbtodb(fs, b) ((b) << (fs)->e2fs_fsbtodb)
266 #define dbtofsb(fs, b) ((b) >> (fs)->e2fs_fsbtodb)
267
268 /*
269 * Macros for handling inode numbers:
270 * inode number to file system block offset.
271 * inode number to cylinder group number.
272 * inode number to file system block address.
273 */
274 #define ino_to_cg(fs, x) (((x) - 1) / (fs)->e2fs.e2fs_ipg)
275 #define ino_to_fsba(fs, x) \
276 ((fs)->e2fs_gd[ino_to_cg(fs, x)].ext2bgd_i_tables + \
277 (((x)-1) % (fs)->e2fs.e2fs_ipg)/(fs)->e2fs_ipb)
278 #define ino_to_fsbo(fs, x) (((x)-1) % (fs)->e2fs_ipb)
279
280 /*
281 * Give cylinder group number for a file system block.
282 * Give cylinder group block number for a file system block.
283 */
284 #define dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg)
285 #define dtogd(fs, d) \
286 (((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg)
287
288 /*
289 * The following macros optimize certain frequently calculated
290 * quantities by using shifts and masks in place of divisions
291 * modulos and multiplications.
292 */
293 #define blkoff(fs, loc) /* calculates (loc % fs->e2fs_bsize) */ \
294 ((loc) & (fs)->e2fs_qbmask)
295 #define lblktosize(fs, blk) /* calculates (blk * fs->e2fs_bsize) */ \
296 ((blk) << (fs)->e2fs_bshift)
297 #define lblkno(fs, loc) /* calculates (loc / fs->e2fs_bsize) */ \
298 ((loc) >> (fs)->e2fs_bshift)
299 #define blkroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \
300 (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
301 #define fragroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \
302 (((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
303 /*
304 * Determine the number of available frags given a
305 * percentage to hold in reserve.
306 */
307 #define freespace(fs) \
308 ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount)
309
310 /*
311 * Number of indirects in a file system block.
312 */
313 #define NINDIR(fs) ((fs)->e2fs_bsize / sizeof(u_int32_t))