Annotation of sys/ufs/ext2fs/ext2fs.h, Revision 1.1.1.1
1.1 nbrk 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))
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