xref: /netbsd-src/sys/ufs/ext2fs/ext2fs.h (revision bdc22b2e01993381dcefeff2bc9b56ca75a4235c)
1 /*	$NetBSD: ext2fs.h,v 1.48 2016/08/20 19:47:44 jdolecek Exp $	*/
2 
3 /*
4  * Copyright (c) 1982, 1986, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. Neither the name of the University nor the names of its contributors
16  *    may be used to endorse or promote products derived from this software
17  *    without specific prior written permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29  * SUCH DAMAGE.
30  *
31  *	@(#)fs.h	8.10 (Berkeley) 10/27/94
32  *  Modified for ext2fs by Manuel Bouyer.
33  */
34 
35 /*
36  * Copyright (c) 1997 Manuel Bouyer.
37  *
38  * Redistribution and use in source and binary forms, with or without
39  * modification, are permitted provided that the following conditions
40  * are met:
41  * 1. Redistributions of source code must retain the above copyright
42  *    notice, this list of conditions and the following disclaimer.
43  * 2. Redistributions in binary form must reproduce the above copyright
44  *    notice, this list of conditions and the following disclaimer in the
45  *    documentation and/or other materials provided with the distribution.
46  *
47  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
48  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
49  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
50  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
51  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
52  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
53  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
54  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
55  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
56  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
57  *
58  *	@(#)fs.h	8.10 (Berkeley) 10/27/94
59  *  Modified for ext2fs by Manuel Bouyer.
60  */
61 
62 #ifndef _UFS_EXT2FS_EXT2FS_H_
63 #define _UFS_EXT2FS_EXT2FS_H_
64 
65 #include <sys/bswap.h>
66 
67 /*
68  * Each disk drive contains some number of file systems.
69  * A file system consists of a number of cylinder groups.
70  * Each cylinder group has inodes and data.
71  *
72  * A file system is described by its super-block, which in turn
73  * describes the cylinder groups.  The super-block is critical
74  * data and is replicated in each cylinder group to protect against
75  * catastrophic loss.  This is done at `newfs' time and the critical
76  * super-block data does not change, so the copies need not be
77  * referenced further unless disaster strikes.
78  *
79  * The first boot and super blocks are given in absolute disk addresses.
80  * The byte-offset forms are preferred, as they don't imply a sector size.
81  */
82 #define BBSIZE		1024
83 #define SBSIZE		1024
84 #define	BBOFF		((off_t)(0))
85 #define	SBOFF		((off_t)(BBOFF + BBSIZE))
86 #define	BBLOCK		((daddr_t)(0))
87 #define	SBLOCK		((daddr_t)(BBLOCK + BBSIZE / DEV_BSIZE))
88 
89 #define	fsbtodb(fs, b)  ((daddr_t)(b) << (fs)->e2fs_fsbtodb)
90 /* calculates (loc / fs->fs_bsize) */
91 #define	lblkno(fs, loc) ((loc) >> (fs->e2fs_bshift))
92 #define	blksize(fs, ip, lbn) ((fs)->e2fs_bsize)
93 
94 /*
95  * Addresses stored in inodes are capable of addressing blocks
96  * XXX
97  */
98 
99 /*
100  * MINBSIZE is the smallest allowable block size.
101  * MINBSIZE must be big enough to hold a cylinder group block,
102  * thus changes to (struct cg) must keep its size within MINBSIZE.
103  * Note that super blocks are always of size SBSIZE,
104  * and that both SBSIZE and MAXBSIZE must be >= MINBSIZE.
105  */
106 #define LOG_MINBSIZE	10
107 #define MINBSIZE	(1 << LOG_MINBSIZE)
108 
109 /*
110  * The path name on which the file system is mounted is maintained
111  * in fs_fsmnt. MAXMNTLEN defines the amount of space allocated in
112  * the super block for this name.
113  */
114 #define MAXMNTLEN	512
115 
116 /*
117  * MINFREE gives the minimum acceptable percentage of file system
118  * blocks which may be free. If the freelist drops below this level
119  * only the superuser may continue to allocate blocks. This may
120  * be set to 0 if no reserve of free blocks is deemed necessary,
121  * however throughput drops by fifty percent if the file system
122  * is run at between 95% and 100% full; thus the minimum default
123  * value of fs_minfree is 5%. However, to get good clustering
124  * performance, 10% is a better choice. hence we use 10% as our
125  * default value. With 10% free space, fragmentation is not a
126  * problem, so we choose to optimize for time.
127  */
128 #define MINFREE		5
129 
130 /*
131  * This is maximum amount of links allowed for files. For directories,
132  * going over this means setting DIR_NLINK feature.
133  */
134 #define EXT2FS_LINK_MAX		65000
135 #define EXT2FS_LINK_INF		1		/* link count unknown */
136 
137 /*
138  * Super block for an ext2fs file system.
139  */
140 struct ext2fs {
141 	uint32_t  e2fs_icount;		/* Inode count */
142 	uint32_t  e2fs_bcount;		/* blocks count */
143 	uint32_t  e2fs_rbcount;		/* reserved blocks count */
144 	uint32_t  e2fs_fbcount;		/* free blocks count */
145 	uint32_t  e2fs_ficount;		/* free inodes count */
146 	uint32_t  e2fs_first_dblock;	/* first data block */
147 	uint32_t  e2fs_log_bsize;	/* bsize = 1024*(2^e2fs_log_bsize) */
148 	uint32_t  e2fs_fsize;		/* fragment size */
149 	uint32_t  e2fs_bpg;		/* blocks per group */
150 	uint32_t  e2fs_fpg;		/* frags per group */
151 	uint32_t  e2fs_ipg;		/* inodes per group */
152 	uint32_t  e2fs_mtime;		/* mount time */
153 	uint32_t  e2fs_wtime;		/* write time */
154 	uint16_t  e2fs_mnt_count;	/* mount count */
155 	uint16_t  e2fs_max_mnt_count;	/* max mount count */
156 	uint16_t  e2fs_magic;		/* magic number */
157 	uint16_t  e2fs_state;		/* file system state */
158 	uint16_t  e2fs_beh;		/* behavior on errors */
159 	uint16_t  e2fs_minrev;		/* minor revision level */
160 	uint32_t  e2fs_lastfsck;	/* time of last fsck */
161 	uint32_t  e2fs_fsckintv;	/* max time between fscks */
162 	uint32_t  e2fs_creator;		/* creator OS */
163 	uint32_t  e2fs_rev;		/* revision level */
164 	uint16_t  e2fs_ruid;		/* default uid for reserved blocks */
165 	uint16_t  e2fs_rgid;		/* default gid for reserved blocks */
166 	/* EXT2_DYNAMIC_REV superblocks */
167 	uint32_t  e2fs_first_ino;	/* first non-reserved inode */
168 	uint16_t  e2fs_inode_size;	/* size of inode structure */
169 	uint16_t  e2fs_block_group_nr;	/* block grp number of this sblk*/
170 	uint32_t  e2fs_features_compat;	/*  compatible feature set */
171 	uint32_t  e2fs_features_incompat; /* incompatible feature set */
172 	uint32_t  e2fs_features_rocompat; /* RO-compatible feature set */
173 	uint8_t   e2fs_uuid[16];	/* 128-bit uuid for volume */
174 	char      e2fs_vname[16];	/* volume name */
175 	char      e2fs_fsmnt[64];	/* name mounted on */
176 	uint32_t  e2fs_algo;		/* For compression */
177 	uint8_t   e2fs_prealloc;	/* # of blocks to preallocate */
178 	uint8_t   e2fs_dir_prealloc;	/* # of blocks to preallocate for dir */
179 	uint16_t  e2fs_reserved_ngdb;	/* # of reserved gd blocks for resize */
180 
181 	/* Additional fields */
182 	char      e3fs_journal_uuid[16];/* uuid of journal superblock */
183 	uint32_t  e3fs_journal_inum;	/* inode number of journal file */
184 	uint32_t  e3fs_journal_dev;	/* device number of journal file */
185 	uint32_t  e3fs_last_orphan;	/* start of list of inodes to delete */
186 	uint32_t  e3fs_hash_seed[4];	/* HTREE hash seed */
187 	char      e3fs_def_hash_version;/* Default hash version to use */
188 	char      e3fs_jnl_backup_type;
189 	uint16_t  e3fs_desc_size;	/* size of group descriptor */
190 	uint32_t  e3fs_default_mount_opts;
191 	uint32_t  e3fs_first_meta_bg;	/* First metablock block group */
192 	uint32_t  e3fs_mkfs_time;	/* when the fs was created */
193 	uint32_t  e3fs_jnl_blks[17];	/* backup of the journal inode */
194 	uint32_t  e4fs_bcount_hi;	/* high bits of blocks count */
195 	uint32_t  e4fs_rbcount_hi;	/* high bits of reserved blocks count */
196 	uint32_t  e4fs_fbcount_hi;	/* high bits of free blocks count */
197 	uint16_t  e4fs_min_extra_isize; /* all inodes have some bytes */
198 	uint16_t  e4fs_want_extra_isize;/* inodes must reserve some bytes */
199 	uint32_t  e4fs_flags;		/* miscellaneous flags */
200 	uint16_t  e4fs_raid_stride;	/* RAID stride */
201 	uint16_t  e4fs_mmpintv;		/* seconds to wait in MMP checking */
202 	uint64_t  e4fs_mmpblk;		/* block for multi-mount protection */
203 	uint32_t  e4fs_raid_stripe_wid; /* blocks on data disks (N * stride) */
204 	uint8_t   e4fs_log_gpf;		/* FLEX_BG group size */
205 	uint8_t   e4fs_chksum_type;	/* metadata checksum algorithm used */
206 	uint8_t   e4fs_encrypt;		/* versioning level for encryption */
207 	uint8_t   e4fs_reserved_pad;
208 	uint64_t  e4fs_kbytes_written;	/* number of lifetime kilobytes */
209 	uint32_t  e4fs_snapinum;	/* inode number of active snapshot */
210 	uint32_t  e4fs_snapid;		/* sequential ID of active snapshot */
211 	uint64_t  e4fs_snaprbcount;	/* rsvd blocks for active snapshot */
212 	uint32_t  e4fs_snaplist;	/* inode number for on-disk snapshot */
213 	uint32_t  e4fs_errcount;	/* number of file system errors */
214 	uint32_t  e4fs_first_errtime;	/* first time an error happened */
215 	uint32_t  e4fs_first_errino;	/* inode involved in first error */
216 	uint64_t  e4fs_first_errblk;	/* block involved of first error */
217 	uint8_t   e4fs_first_errfunc[32];/* function where error happened */
218 	uint32_t  e4fs_first_errline;	/* line number where error happened */
219 	uint32_t  e4fs_last_errtime;	/* most recent time of an error */
220 	uint32_t  e4fs_last_errino;	/* inode involved in last error */
221 	uint32_t  e4fs_last_errline;	/* line number where error happened */
222 	uint64_t  e4fs_last_errblk;	/* block involved of last error */
223 	uint8_t   e4fs_last_errfunc[32];/* function where error happened */
224 	uint8_t   e4fs_mount_opts[64];
225 	uint32_t  e4fs_usrquota_inum;	/* inode for tracking user quota */
226 	uint32_t  e4fs_grpquota_inum;	/* inode for tracking group quota */
227 	uint32_t  e4fs_overhead_clusters;/* overhead blocks/clusters */
228 	uint32_t  e4fs_backup_bgs[2];	/* groups with sparse_super2 SBs */
229 	uint8_t   e4fs_encrypt_algos[4];/* encryption algorithms in use */
230 	uint8_t   e4fs_encrypt_pw_salt[16];/* salt used for string2key */
231 	uint32_t  e4fs_lpf_ino;		/* location of the lost+found inode */
232 	uint32_t  e4fs_proj_quota_inum;	/* inode for tracking project quota */
233 	uint32_t  e4fs_chksum_seed;	/* checksum seed */
234 	uint32_t  e4fs_reserved[98];	/* padding to the end of the block */
235 	uint32_t  e4fs_sbchksum;	/* superblock checksum */
236 };
237 
238 
239 /* in-memory data for ext2fs */
240 struct m_ext2fs {
241 	struct ext2fs e2fs;
242 	u_char	e2fs_fsmnt[MAXMNTLEN];	/* name mounted on */
243 	int8_t	e2fs_ronly;	/* mounted read-only flag */
244 	int8_t	e2fs_fmod;	/* super block modified flag */
245 	int8_t	e2fs_uhash;	/* 3 if hash should be signed, 0 if not */
246 	int32_t	e2fs_bsize;	/* block size */
247 	int32_t e2fs_bshift;	/* ``lblkno'' calc of logical blkno */
248 	int32_t e2fs_bmask;	/* ``blkoff'' calc of blk offsets */
249 	int64_t e2fs_qbmask;	/* ~fs_bmask - for use with quad size */
250 	int32_t	e2fs_fsbtodb;	/* fsbtodb and dbtofsb shift constant */
251 	int32_t	e2fs_ncg;	/* number of cylinder groups */
252 	int32_t	e2fs_ngdb;	/* number of group descriptor blocks */
253 	int32_t	e2fs_ipb;	/* number of inodes per block */
254 	int32_t	e2fs_itpg;	/* number of inode table blocks per group */
255 	struct	ext2_gd *e2fs_gd; /* group descriptors (data not byteswapped) */
256 };
257 
258 
259 
260 /*
261  * Filesystem identification
262  */
263 #define	E2FS_MAGIC	0xef53	/* the ext2fs magic number */
264 #define E2FS_REV0	0	/* GOOD_OLD revision */
265 #define E2FS_REV1	1	/* Support compat/incompat features */
266 
267 /* compatible/incompatible features */
268 #define EXT2F_COMPAT_PREALLOC		0x0001
269 #define EXT2F_COMPAT_AFS		0x0002
270 #define EXT2F_COMPAT_HASJOURNAL		0x0004
271 #define EXT2F_COMPAT_EXTATTR		0x0008
272 #define EXT2F_COMPAT_RESIZE		0x0010
273 #define EXT2F_COMPAT_DIRHASHINDEX	0x0020
274 #define EXT2F_COMPAT_SPARSESUPER2	0x0200
275 #define	EXT2F_COMPAT_BITS \
276 	"\20" \
277 	"\12COMPAT_SPARSESUPER2" \
278 	"\11" \
279 	"\10" \
280 	"\07" \
281 	"\06COMPAT_DIRHASHINDEX" \
282 	"\05COMPAT_RESIZE" \
283 	"\04COMPAT_EXTATTR" \
284 	"\03COMPAT_HASJOURNAL" \
285 	"\02COMPAT_AFS" \
286 	"\01COMPAT_PREALLOC"
287 
288 #define EXT2F_ROCOMPAT_SPARSESUPER	0x0001
289 #define EXT2F_ROCOMPAT_LARGEFILE	0x0002
290 #define EXT2F_ROCOMPAT_BTREE_DIR	0x0004
291 #define EXT2F_ROCOMPAT_HUGE_FILE	0x0008
292 #define EXT2F_ROCOMPAT_GDT_CSUM		0x0010
293 #define EXT2F_ROCOMPAT_DIR_NLINK	0x0020
294 #define EXT2F_ROCOMPAT_EXTRA_ISIZE	0x0040
295 #define EXT2F_ROCOMPAT_QUOTA		0x0100
296 #define EXT2F_ROCOMPAT_BIGALLOC		0x0200
297 #define EXT2F_ROCOMPAT_METADATA_CKSUM	0x0400
298 #define EXT2F_ROCOMPAT_READONLY		0x1000
299 #define EXT2F_ROCOMPAT_PROJECT		0x2000
300 #define	EXT2F_ROCOMPAT_BITS \
301 	"\20" \
302 	"\16ROCOMPAT_PROJECT" \
303 	"\15ROCOMPAT_READONLY" \
304 	"\14" \
305 	"\13ROCOMPAT_METADATA_CKSUM" \
306 	"\12ROCOMPAT_BIGALLOC" \
307 	"\11ROCOMPAT_QUOTA" \
308 	"\10" \
309 	"\07ROCOMPAT_EXTRA_ISIZE" \
310 	"\06ROCOMPAT_DIR_NLINK" \
311 	"\05ROCOMPAT_GDT_CSUM" \
312 	"\04ROCOMPAT_HUGE_FILE" \
313 	"\03ROCOMPAT_BTREE_DIR" \
314 	"\02ROCOMPAT_LARGEFILE" \
315 	"\01ROCOMPAT_SPARSESUPER"
316 
317 #define EXT2F_INCOMPAT_COMP		0x0001
318 #define EXT2F_INCOMPAT_FTYPE		0x0002
319 #define	EXT2F_INCOMPAT_REPLAY_JOURNAL	0x0004
320 #define	EXT2F_INCOMPAT_USES_JOURNAL	0x0008
321 #define EXT2F_INCOMPAT_META_BG		0x0010
322 #define EXT2F_INCOMPAT_EXTENTS		0x0040
323 #define EXT2F_INCOMPAT_64BIT		0x0080
324 #define EXT2F_INCOMPAT_MMP		0x0100
325 #define EXT2F_INCOMPAT_FLEX_BG		0x0200
326 #define EXT2F_INCOMPAT_EA_INODE		0x0400
327 #define EXT2F_INCOMPAT_DIRDATA		0x1000
328 #define EXT2F_INCOMPAT_CSUM_SEED	0x2000
329 #define EXT2F_INCOMPAT_LARGEDIR		0x4000
330 #define EXT2F_INCOMPAT_INLINE_DATA	0x8000
331 #define EXT2F_INCOMPAT_ENCRYPT		0x10000
332 #define	EXT2F_INCOMPAT_BITS \
333 	"\20" \
334 	"\021INCOMPAT_ENCRYPT" \
335 	"\020INCOMPAT_INLINE_DATA" \
336 	"\017INCOMPAT_LARGEDIR" \
337 	"\016INCOMPAT_CSUM_SEED" \
338 	"\015INCOMPAT_DIRDATA" \
339 	"\014" \
340 	"\013INCOMPAT_EA_INODE" \
341 	"\012INCOMPAT_FLEX_BG" \
342 	"\011INCOMPAT_MMP" \
343 	"\010INCOMPAT_64BIT" \
344 	"\07INCOMPAT_EXTENTS" \
345 	"\05INCOMPAT_META_BG" \
346 	"\04INCOMPAT_USES_JOURNAL" \
347 	"\03INCOMPAT_REPLAY_JOURNAL" \
348 	"\02INCOMPAT_FTYPE" \
349 	"\01INCOMPAT_COMP"
350 
351 /*
352  * Features supported in this implementation
353  *
354  * We support the following REV1 features:
355  * - EXT2F_ROCOMPAT_SPARSESUPER
356  *    superblock backups stored only in cg_has_sb(bno) groups
357  * - EXT2F_ROCOMPAT_LARGEFILE
358  *    use e2di_size_high in struct ext2fs_dinode to store
359  *    upper 32bit of size for >2GB files
360  * - EXT2F_INCOMPAT_FTYPE
361  *    store file type to e2d_type in struct ext2fs_direct
362  *    (on REV0 e2d_namlen is uint16_t and no e2d_type, like ffs)
363  */
364 #define EXT2F_COMPAT_SUPP		0x0000
365 #define EXT2F_ROCOMPAT_SUPP		(EXT2F_ROCOMPAT_SPARSESUPER \
366 					 | EXT2F_ROCOMPAT_LARGEFILE \
367 					 | EXT2F_ROCOMPAT_HUGE_FILE \
368 					 | EXT2F_ROCOMPAT_EXTRA_ISIZE \
369 					 | EXT2F_ROCOMPAT_DIR_NLINK \
370 					 | EXT2F_ROCOMPAT_GDT_CSUM)
371 #define EXT2F_INCOMPAT_SUPP		(EXT2F_INCOMPAT_FTYPE \
372 					 | EXT2F_INCOMPAT_EXTENTS \
373 					 | EXT2F_INCOMPAT_FLEX_BG)
374 
375 /*
376  * Feature set definitions
377  */
378 #define EXT2F_HAS_COMPAT_FEATURE(fs, feature) \
379 	((fs)->e2fs.e2fs_rev >= E2FS_REV1 && \
380 	((fs)->e2fs.e2fs_features_compat & (feature)) != 0)
381 
382 #define EXT2F_HAS_ROCOMPAT_FEATURE(fs, feature) \
383 	((fs)->e2fs.e2fs_rev >= E2FS_REV1 && \
384 	((fs)->e2fs.e2fs_features_rocompat & (feature)) != 0)
385 
386 #define EXT2F_HAS_INCOMPAT_FEATURE(fs, feature) \
387 	((fs)->e2fs.e2fs_rev >= E2FS_REV1 && \
388 	((fs)->e2fs.e2fs_features_incompat & (feature)) != 0)
389 
390 
391 /*
392  * Definitions of behavior on errors
393  */
394 #define E2FS_BEH_CONTINUE	1	/* continue operation */
395 #define E2FS_BEH_READONLY	2	/* remount fs read only */
396 #define E2FS_BEH_PANIC		3	/* cause panic */
397 #define E2FS_BEH_DEFAULT	E2FS_BEH_CONTINUE
398 
399 /*
400  * OS identification
401  */
402 #define E2FS_OS_LINUX	0
403 #define E2FS_OS_HURD	1
404 #define E2FS_OS_MASIX	2
405 #define E2FS_OS_FREEBSD	3
406 #define E2FS_OS_LITES	4
407 
408 /*
409  * Filesystem clean flags
410  */
411 #define	E2FS_ISCLEAN	0x01
412 #define	E2FS_ERRORS	0x02
413 
414 /* ext2 file system block group descriptor */
415 
416 struct ext2_gd {
417 	uint32_t ext2bgd_b_bitmap;	/* blocks bitmap block */
418 	uint32_t ext2bgd_i_bitmap;	/* inodes bitmap block */
419 	uint32_t ext2bgd_i_tables;	/* first inodes table block */
420 	uint16_t ext2bgd_nbfree;	/* number of free blocks */
421 	uint16_t ext2bgd_nifree;	/* number of free inodes */
422 	uint16_t ext2bgd_ndirs;		/* number of directories */
423 
424 	/*
425 	 * Following only valid when either GDT_CSUM (AKA uninit_bg)
426 	 * or METADATA_CKSUM feature is on
427 	 */
428 	uint16_t ext2bgd_flags;		/* ext4 bg flags (INODE_UNINIT, ...)*/
429 	uint32_t ext2bgd_exclude_bitmap_lo;	/* snapshot exclude bitmap */
430 	uint16_t ext2bgd_block_bitmap_csum_lo;	/* Low block bitmap checksum */
431 	uint16_t ext2bgd_inode_bitmap_csum_lo;	/* Low inode bitmap checksum */
432 	uint16_t ext2bgd_itable_unused_lo;	/* Low unused inode offset */
433 	uint16_t ext2bgd_checksum;		/* Group desc checksum */
434 
435 	/*
436 	 * XXX disk32 Further fields only exist if 64BIT feature is on
437 	 * and superblock desc_size > 32, not supported for now.
438 	 */
439 };
440 
441 #define E2FS_BG_INODE_UNINIT	0x0001	/* Inode bitmap not used/initialized */
442 #define E2FS_BG_BLOCK_UNINIT	0x0002	/* Block bitmap not used/initialized */
443 #define E2FS_BG_INODE_ZEROED	0x0004	/* On-disk inode table initialized */
444 
445 #define E2FS_HAS_GD_CSUM(fs) \
446 	EXT2F_HAS_ROCOMPAT_FEATURE(fs, EXT2F_ROCOMPAT_GDT_CSUM|EXT2F_ROCOMPAT_METADATA_CKSUM) != 0
447 
448 /*
449  * If the EXT2F_ROCOMPAT_SPARSESUPER flag is set, the cylinder group has a
450  * copy of the super and cylinder group descriptors blocks only if it's
451  * 1, a power of 3, 5 or 7
452  */
453 
454 static __inline int cg_has_sb(int) __unused;
455 static __inline int
456 cg_has_sb(int i)
457 {
458 	int a3, a5, a7;
459 
460 	if (i == 0 || i == 1)
461 		return 1;
462 	for (a3 = 3, a5 = 5, a7 = 7;
463 	    a3 <= i || a5 <= i || a7 <= i;
464 	    a3 *= 3, a5 *= 5, a7 *= 7)
465 		if (i == a3 || i == a5 || i == a7)
466 			return 1;
467 	return 0;
468 }
469 
470 /* EXT2FS metadatas are stored in little-endian byte order. These macros
471  * helps reading theses metadatas
472  */
473 
474 #if BYTE_ORDER == LITTLE_ENDIAN
475 #	define h2fs16(x) (x)
476 #	define h2fs32(x) (x)
477 #	define h2fs64(x) (x)
478 #	define fs2h16(x) (x)
479 #	define fs2h32(x) (x)
480 #	define fs2h64(x) (x)
481 #	define e2fs_sbload(old, new) memcpy((new), (old), SBSIZE)
482 #	define e2fs_sbsave(old, new) memcpy((new), (old), SBSIZE)
483 #else
484 void e2fs_sb_bswap(struct ext2fs *, struct ext2fs *);
485 #	define h2fs16(x) bswap16(x)
486 #	define h2fs32(x) bswap32(x)
487 #	define h2fs64(x) bswap64(x)
488 #	define fs2h16(x) bswap16(x)
489 #	define fs2h32(x) bswap32(x)
490 #	define fs2h64(x) bswap64(x)
491 #	define e2fs_sbload(old, new) e2fs_sb_bswap((old), (new))
492 #	define e2fs_sbsave(old, new) e2fs_sb_bswap((old), (new))
493 #endif
494 
495 /* Group descriptors are not byte swapped */
496 #define e2fs_cgload(old, new, size) memcpy((new), (old), (size))
497 #define e2fs_cgsave(old, new, size) memcpy((new), (old), (size))
498 
499 /*
500  * Turn file system block numbers into disk block addresses.
501  * This maps file system blocks to device size blocks.
502  */
503 #define EXT2_FSBTODB(fs, b)	((b) << (fs)->e2fs_fsbtodb)
504 #define EXT2_DBTOFSB(fs, b)	((b) >> (fs)->e2fs_fsbtodb)
505 
506 /*
507  * Macros for handling inode numbers:
508  *	 inode number to file system block offset.
509  *	 inode number to cylinder group number.
510  *	 inode number to file system block address.
511  */
512 #define	ino_to_cg(fs, x)	(((x) - 1) / (fs)->e2fs.e2fs_ipg)
513 #define	ino_to_fsba(fs, x)						\
514 	(fs2h32((fs)->e2fs_gd[ino_to_cg((fs), (x))].ext2bgd_i_tables) +	\
515 	(((x) - 1) % (fs)->e2fs.e2fs_ipg) / (fs)->e2fs_ipb)
516 #define	ino_to_fsbo(fs, x)	(((x) - 1) % (fs)->e2fs_ipb)
517 
518 /*
519  * Give cylinder group number for a file system block.
520  * Give cylinder group block number for a file system block.
521  */
522 #define	dtog(fs, d) (((d) - (fs)->e2fs.e2fs_first_dblock) / (fs)->e2fs.e2fs_fpg)
523 #define	dtogd(fs, d) \
524 	(((d) - (fs)->e2fs.e2fs_first_dblock) % (fs)->e2fs.e2fs_fpg)
525 
526 /*
527  * The following macros optimize certain frequently calculated
528  * quantities by using shifts and masks in place of divisions
529  * modulos and multiplications.
530  */
531 #define ext2_blkoff(fs, loc)	/* calculates (loc % fs->e2fs_bsize) */ \
532 	((loc) & (fs)->e2fs_qbmask)
533 #define ext2_lblktosize(fs, blk) /* calculates (blk * fs->e2fs_bsize) */ \
534 	((blk) << (fs)->e2fs_bshift)
535 #define ext2_lblkno(fs, loc)	/* calculates (loc / fs->e2fs_bsize) */ \
536 	((loc) >> (fs)->e2fs_bshift)
537 #define ext2_blkroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \
538 	(((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
539 #define ext2_fragroundup(fs, size) /* calculates roundup(size, fs->e2fs_bsize) */ \
540 	(((size) + (fs)->e2fs_qbmask) & (fs)->e2fs_bmask)
541 /*
542  * Determine the number of available frags given a
543  * percentage to hold in reserve.
544  */
545 #define freespace(fs) \
546    ((fs)->e2fs.e2fs_fbcount - (fs)->e2fs.e2fs_rbcount)
547 
548 /*
549  * Number of indirects in a file system block.
550  */
551 #define	EXT2_NINDIR(fs)	((fs)->e2fs_bsize / sizeof(uint32_t))
552 
553 #endif /* !_UFS_EXT2FS_EXT2FS_H_ */
554