1 /* SPDX-License-Identifier: LGPL-2.1+ WITH Linux-syscall-note */
2 /*
3 * nilfs2_ondisk.h - NILFS2 on-disk structures
4 *
5 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as published
9 * by the Free Software Foundation; either version 2.1 of the License, or
10 * (at your option) any later version.
11 */
12 /*
13 * linux/include/linux/ext2_fs.h
14 *
15 * Copyright (C) 1992, 1993, 1994, 1995
16 * Remy Card (card@masi.ibp.fr)
17 * Laboratoire MASI - Institut Blaise Pascal
18 * Universite Pierre et Marie Curie (Paris VI)
19 *
20 * from
21 *
22 * linux/include/linux/minix_fs.h
23 *
24 * Copyright (C) 1991, 1992 Linus Torvalds
25 */
26
27 #ifndef _LINUX_NILFS2_ONDISK_H
28 #define _LINUX_NILFS2_ONDISK_H
29
30 #include <linux/types.h>
31 #include <linux/magic.h>
32 #include <asm/byteorder.h>
33
34 #define NILFS_INODE_BMAP_SIZE 7
35
36 /**
37 * struct nilfs_inode - structure of an inode on disk
38 * @i_blocks: blocks count
39 * @i_size: size in bytes
40 * @i_ctime: creation time (seconds)
41 * @i_mtime: modification time (seconds)
42 * @i_ctime_nsec: creation time (nano seconds)
43 * @i_mtime_nsec: modification time (nano seconds)
44 * @i_uid: user id
45 * @i_gid: group id
46 * @i_mode: file mode
47 * @i_links_count: links count
48 * @i_flags: file flags
49 * @i_bmap: block mapping
50 * @i_xattr: extended attributes
51 * @i_generation: file generation (for NFS)
52 * @i_pad: padding
53 */
54 struct nilfs_inode {
55 __le64 i_blocks;
56 __le64 i_size;
57 __le64 i_ctime;
58 __le64 i_mtime;
59 __le32 i_ctime_nsec;
60 __le32 i_mtime_nsec;
61 __le32 i_uid;
62 __le32 i_gid;
63 __le16 i_mode;
64 __le16 i_links_count;
65 __le32 i_flags;
66 __le64 i_bmap[NILFS_INODE_BMAP_SIZE];
67 #define i_device_code i_bmap[0]
68 __le64 i_xattr;
69 __le32 i_generation;
70 __le32 i_pad;
71 };
72
73 #define NILFS_MIN_INODE_SIZE 128
74
75 /**
76 * struct nilfs_super_root - structure of super root
77 * @sr_sum: check sum
78 * @sr_bytes: byte count of the structure
79 * @sr_flags: flags (reserved)
80 * @sr_nongc_ctime: write time of the last segment not for cleaner operation
81 * @sr_dat: DAT file inode
82 * @sr_cpfile: checkpoint file inode
83 * @sr_sufile: segment usage file inode
84 */
85 struct nilfs_super_root {
86 __le32 sr_sum;
87 __le16 sr_bytes;
88 __le16 sr_flags;
89 __le64 sr_nongc_ctime;
90 struct nilfs_inode sr_dat;
91 struct nilfs_inode sr_cpfile;
92 struct nilfs_inode sr_sufile;
93 };
94
95 #define NILFS_SR_MDT_OFFSET(inode_size, i) \
96 ((unsigned long)&((struct nilfs_super_root *)0)->sr_dat + \
97 (inode_size) * (i))
98 #define NILFS_SR_DAT_OFFSET(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 0)
99 #define NILFS_SR_CPFILE_OFFSET(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 1)
100 #define NILFS_SR_SUFILE_OFFSET(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 2)
101 #define NILFS_SR_BYTES(inode_size) NILFS_SR_MDT_OFFSET(inode_size, 3)
102
103 /*
104 * Maximal mount counts
105 */
106 #define NILFS_DFL_MAX_MNT_COUNT 50 /* 50 mounts */
107
108 /*
109 * File system states (sbp->s_state, nilfs->ns_mount_state)
110 */
111 #define NILFS_VALID_FS 0x0001 /* Unmounted cleanly */
112 #define NILFS_ERROR_FS 0x0002 /* Errors detected */
113 #define NILFS_RESIZE_FS 0x0004 /* Resize required */
114
115 /*
116 * Mount flags (sbi->s_mount_opt)
117 */
118 #define NILFS_MOUNT_ERROR_MODE 0x0070 /* Error mode mask */
119 #define NILFS_MOUNT_ERRORS_CONT 0x0010 /* Continue on errors */
120 #define NILFS_MOUNT_ERRORS_RO 0x0020 /* Remount fs ro on errors */
121 #define NILFS_MOUNT_ERRORS_PANIC 0x0040 /* Panic on errors */
122 #define NILFS_MOUNT_BARRIER 0x1000 /* Use block barriers */
123 #define NILFS_MOUNT_STRICT_ORDER 0x2000 /*
124 * Apply strict in-order
125 * semantics also for data
126 */
127 #define NILFS_MOUNT_NORECOVERY 0x4000 /*
128 * Disable write access during
129 * mount-time recovery
130 */
131 #define NILFS_MOUNT_DISCARD 0x8000 /* Issue DISCARD requests */
132
133
134 /**
135 * struct nilfs_super_block - structure of super block on disk
136 */
137 struct nilfs_super_block {
138 /*00*/ __le32 s_rev_level; /* Revision level */
139 __le16 s_minor_rev_level; /* minor revision level */
140 __le16 s_magic; /* Magic signature */
141
142 __le16 s_bytes; /*
143 * Bytes count of CRC calculation
144 * for this structure. s_reserved
145 * is excluded.
146 */
147 __le16 s_flags; /* flags */
148 __le32 s_crc_seed; /* Seed value of CRC calculation */
149 /*10*/ __le32 s_sum; /* Check sum of super block */
150
151 __le32 s_log_block_size; /*
152 * Block size represented as follows
153 * blocksize =
154 * 1 << (s_log_block_size + 10)
155 */
156 __le64 s_nsegments; /* Number of segments in filesystem */
157 /*20*/ __le64 s_dev_size; /* block device size in bytes */
158 __le64 s_first_data_block; /* 1st seg disk block number */
159 /*30*/ __le32 s_blocks_per_segment; /* number of blocks per full segment */
160 __le32 s_r_segments_percentage; /* Reserved segments percentage */
161
162 __le64 s_last_cno; /* Last checkpoint number */
163 /*40*/ __le64 s_last_pseg; /* disk block addr pseg written last */
164 __le64 s_last_seq; /* seq. number of seg written last */
165 /*50*/ __le64 s_free_blocks_count; /* Free blocks count */
166
167 __le64 s_ctime; /*
168 * Creation time (execution time of
169 * newfs)
170 */
171 /*60*/ __le64 s_mtime; /* Mount time */
172 __le64 s_wtime; /* Write time */
173 /*70*/ __le16 s_mnt_count; /* Mount count */
174 __le16 s_max_mnt_count; /* Maximal mount count */
175 __le16 s_state; /* File system state */
176 __le16 s_errors; /* Behaviour when detecting errors */
177 __le64 s_lastcheck; /* time of last check */
178
179 /*80*/ __le32 s_checkinterval; /* max. time between checks */
180 __le32 s_creator_os; /* OS */
181 __le16 s_def_resuid; /* Default uid for reserved blocks */
182 __le16 s_def_resgid; /* Default gid for reserved blocks */
183 __le32 s_first_ino; /* First non-reserved inode */
184
185 /*90*/ __le16 s_inode_size; /* Size of an inode */
186 __le16 s_dat_entry_size; /* Size of a dat entry */
187 __le16 s_checkpoint_size; /* Size of a checkpoint */
188 __le16 s_segment_usage_size; /* Size of a segment usage */
189
190 /*98*/ __u8 s_uuid[16]; /* 128-bit uuid for volume */
191 /*A8*/ char s_volume_name[80]; /* volume name */
192
193 /*F8*/ __le32 s_c_interval; /* Commit interval of segment */
194 __le32 s_c_block_max; /*
195 * Threshold of data amount for
196 * the segment construction
197 */
198 /*100*/ __le64 s_feature_compat; /* Compatible feature set */
199 __le64 s_feature_compat_ro; /* Read-only compatible feature set */
200 __le64 s_feature_incompat; /* Incompatible feature set */
201 __u32 s_reserved[186]; /* padding to the end of the block */
202 };
203
204 /*
205 * Codes for operating systems
206 */
207 #define NILFS_OS_LINUX 0
208 /* Codes from 1 to 4 are reserved to keep compatibility with ext2 creator-OS */
209
210 /*
211 * Revision levels
212 */
213 #define NILFS_CURRENT_REV 2 /* current major revision */
214 #define NILFS_MINOR_REV 0 /* minor revision */
215 #define NILFS_MIN_SUPP_REV 2 /* minimum supported revision */
216
217 /*
218 * Feature set definitions
219 *
220 * If there is a bit set in the incompatible feature set that the kernel
221 * doesn't know about, it should refuse to mount the filesystem.
222 */
223 #define NILFS_FEATURE_COMPAT_RO_BLOCK_COUNT 0x00000001ULL
224
225 #define NILFS_FEATURE_COMPAT_SUPP 0ULL
226 #define NILFS_FEATURE_COMPAT_RO_SUPP NILFS_FEATURE_COMPAT_RO_BLOCK_COUNT
227 #define NILFS_FEATURE_INCOMPAT_SUPP 0ULL
228
229 /*
230 * Bytes count of super_block for CRC-calculation
231 */
232 #define NILFS_SB_BYTES \
233 ((long)&((struct nilfs_super_block *)0)->s_reserved)
234
235 /*
236 * Special inode number
237 */
238 #define NILFS_ROOT_INO 2 /* Root file inode */
239 #define NILFS_DAT_INO 3 /* DAT file */
240 #define NILFS_CPFILE_INO 4 /* checkpoint file */
241 #define NILFS_SUFILE_INO 5 /* segment usage file */
242 #define NILFS_IFILE_INO 6 /* ifile */
243 #define NILFS_ATIME_INO 7 /* Atime file (reserved) */
244 #define NILFS_XATTR_INO 8 /* Xattribute file (reserved) */
245 #define NILFS_SKETCH_INO 10 /* Sketch file */
246 #define NILFS_USER_INO 11 /* Fisrt user's file inode number */
247
248 #define NILFS_SB_OFFSET_BYTES 1024 /* byte offset of nilfs superblock */
249
250 #define NILFS_SEG_MIN_BLOCKS 16 /*
251 * Minimum number of blocks in
252 * a full segment
253 */
254 #define NILFS_PSEG_MIN_BLOCKS 2 /*
255 * Minimum number of blocks in
256 * a partial segment
257 */
258 #define NILFS_MIN_NRSVSEGS 8 /*
259 * Minimum number of reserved
260 * segments
261 */
262
263 /*
264 * We call DAT, cpfile, and sufile root metadata files. Inodes of
265 * these files are written in super root block instead of ifile, and
266 * garbage collector doesn't keep any past versions of these files.
267 */
268 #define NILFS_ROOT_METADATA_FILE(ino) \
269 ((ino) >= NILFS_DAT_INO && (ino) <= NILFS_SUFILE_INO)
270
271 /*
272 * bytes offset of secondary super block
273 */
274 #define NILFS_SB2_OFFSET_BYTES(devsize) ((((devsize) >> 12) - 1) << 12)
275
276 /*
277 * Maximal count of links to a file
278 */
279 #define NILFS_LINK_MAX 32000
280
281 /*
282 * Structure of a directory entry
283 * (Same as ext2)
284 */
285
286 #define NILFS_NAME_LEN 255
287
288 /*
289 * Block size limitations
290 */
291 #define NILFS_MIN_BLOCK_SIZE 1024
292 #define NILFS_MAX_BLOCK_SIZE 65536
293
294 /*
295 * The new version of the directory entry. Since V0 structures are
296 * stored in intel byte order, and the name_len field could never be
297 * bigger than 255 chars, it's safe to reclaim the extra byte for the
298 * file_type field.
299 */
300 struct nilfs_dir_entry {
301 __le64 inode; /* Inode number */
302 __le16 rec_len; /* Directory entry length */
303 __u8 name_len; /* Name length */
304 __u8 file_type; /* Dir entry type (file, dir, etc) */
305 char name[NILFS_NAME_LEN]; /* File name */
306 char pad;
307 };
308
309 /*
310 * NILFS directory file types. Only the low 3 bits are used. The
311 * other bits are reserved for now.
312 */
313 enum {
314 NILFS_FT_UNKNOWN,
315 NILFS_FT_REG_FILE,
316 NILFS_FT_DIR,
317 NILFS_FT_CHRDEV,
318 NILFS_FT_BLKDEV,
319 NILFS_FT_FIFO,
320 NILFS_FT_SOCK,
321 NILFS_FT_SYMLINK,
322 NILFS_FT_MAX
323 };
324
325 /*
326 * NILFS_DIR_PAD defines the directory entries boundaries
327 *
328 * NOTE: It must be a multiple of 8
329 */
330 #define NILFS_DIR_PAD 8
331 #define NILFS_DIR_ROUND (NILFS_DIR_PAD - 1)
332 #define NILFS_DIR_REC_LEN(name_len) (((name_len) + 12 + NILFS_DIR_ROUND) & \
333 ~NILFS_DIR_ROUND)
334 #define NILFS_MAX_REC_LEN ((1 << 16) - 1)
335
336 /**
337 * struct nilfs_finfo - file information
338 * @fi_ino: inode number
339 * @fi_cno: checkpoint number
340 * @fi_nblocks: number of blocks (including intermediate blocks)
341 * @fi_ndatablk: number of file data blocks
342 */
343 struct nilfs_finfo {
344 __le64 fi_ino;
345 __le64 fi_cno;
346 __le32 fi_nblocks;
347 __le32 fi_ndatablk;
348 };
349
350 /**
351 * struct nilfs_binfo_v - information on a data block (except DAT)
352 * @bi_vblocknr: virtual block number
353 * @bi_blkoff: block offset
354 */
355 struct nilfs_binfo_v {
356 __le64 bi_vblocknr;
357 __le64 bi_blkoff;
358 };
359
360 /**
361 * struct nilfs_binfo_dat - information on a DAT node block
362 * @bi_blkoff: block offset
363 * @bi_level: level
364 * @bi_pad: padding
365 */
366 struct nilfs_binfo_dat {
367 __le64 bi_blkoff;
368 __u8 bi_level;
369 __u8 bi_pad[7];
370 };
371
372 /**
373 * union nilfs_binfo: block information
374 * @bi_v: nilfs_binfo_v structure
375 * @bi_dat: nilfs_binfo_dat structure
376 */
377 union nilfs_binfo {
378 struct nilfs_binfo_v bi_v;
379 struct nilfs_binfo_dat bi_dat;
380 };
381
382 /**
383 * struct nilfs_segment_summary - segment summary header
384 * @ss_datasum: checksum of data
385 * @ss_sumsum: checksum of segment summary
386 * @ss_magic: magic number
387 * @ss_bytes: size of this structure in bytes
388 * @ss_flags: flags
389 * @ss_seq: sequence number
390 * @ss_create: creation timestamp
391 * @ss_next: next segment
392 * @ss_nblocks: number of blocks
393 * @ss_nfinfo: number of finfo structures
394 * @ss_sumbytes: total size of segment summary in bytes
395 * @ss_pad: padding
396 * @ss_cno: checkpoint number
397 */
398 struct nilfs_segment_summary {
399 __le32 ss_datasum;
400 __le32 ss_sumsum;
401 __le32 ss_magic;
402 __le16 ss_bytes;
403 __le16 ss_flags;
404 __le64 ss_seq;
405 __le64 ss_create;
406 __le64 ss_next;
407 __le32 ss_nblocks;
408 __le32 ss_nfinfo;
409 __le32 ss_sumbytes;
410 __le32 ss_pad;
411 __le64 ss_cno;
412 /* array of finfo structures */
413 };
414
415 #define NILFS_SEGSUM_MAGIC 0x1eaffa11 /* segment summary magic number */
416
417 /*
418 * Segment summary flags
419 */
420 #define NILFS_SS_LOGBGN 0x0001 /* begins a logical segment */
421 #define NILFS_SS_LOGEND 0x0002 /* ends a logical segment */
422 #define NILFS_SS_SR 0x0004 /* has super root */
423 #define NILFS_SS_SYNDT 0x0008 /* includes data only updates */
424 #define NILFS_SS_GC 0x0010 /* segment written for cleaner operation */
425
426 /**
427 * struct nilfs_btree_node - header of B-tree node block
428 * @bn_flags: flags
429 * @bn_level: level
430 * @bn_nchildren: number of children
431 * @bn_pad: padding
432 */
433 struct nilfs_btree_node {
434 __u8 bn_flags;
435 __u8 bn_level;
436 __le16 bn_nchildren;
437 __le32 bn_pad;
438 };
439
440 /* flags */
441 #define NILFS_BTREE_NODE_ROOT 0x01
442
443 /* level */
444 #define NILFS_BTREE_LEVEL_DATA 0
445 #define NILFS_BTREE_LEVEL_NODE_MIN (NILFS_BTREE_LEVEL_DATA + 1)
446 #define NILFS_BTREE_LEVEL_MAX 14 /* Max level (exclusive) */
447
448 /**
449 * struct nilfs_direct_node - header of built-in bmap array
450 * @dn_flags: flags
451 * @dn_pad: padding
452 */
453 struct nilfs_direct_node {
454 __u8 dn_flags;
455 __u8 pad[7];
456 };
457
458 /**
459 * struct nilfs_palloc_group_desc - block group descriptor
460 * @pg_nfrees: number of free entries in block group
461 */
462 struct nilfs_palloc_group_desc {
463 __le32 pg_nfrees;
464 };
465
466 /**
467 * struct nilfs_dat_entry - disk address translation entry
468 * @de_blocknr: block number
469 * @de_start: start checkpoint number
470 * @de_end: end checkpoint number
471 * @de_rsv: reserved for future use
472 */
473 struct nilfs_dat_entry {
474 __le64 de_blocknr;
475 __le64 de_start;
476 __le64 de_end;
477 __le64 de_rsv;
478 };
479
480 #define NILFS_MIN_DAT_ENTRY_SIZE 32
481
482 /**
483 * struct nilfs_snapshot_list - snapshot list
484 * @ssl_next: next checkpoint number on snapshot list
485 * @ssl_prev: previous checkpoint number on snapshot list
486 */
487 struct nilfs_snapshot_list {
488 __le64 ssl_next;
489 __le64 ssl_prev;
490 };
491
492 /**
493 * struct nilfs_checkpoint - checkpoint structure
494 * @cp_flags: flags
495 * @cp_checkpoints_count: checkpoints count in a block
496 * @cp_snapshot_list: snapshot list
497 * @cp_cno: checkpoint number
498 * @cp_create: creation timestamp
499 * @cp_nblk_inc: number of blocks incremented by this checkpoint
500 * @cp_inodes_count: inodes count
501 * @cp_blocks_count: blocks count
502 * @cp_ifile_inode: inode of ifile
503 */
504 struct nilfs_checkpoint {
505 __le32 cp_flags;
506 __le32 cp_checkpoints_count;
507 struct nilfs_snapshot_list cp_snapshot_list;
508 __le64 cp_cno;
509 __le64 cp_create;
510 __le64 cp_nblk_inc;
511 __le64 cp_inodes_count;
512 __le64 cp_blocks_count;
513
514 /*
515 * Do not change the byte offset of ifile inode.
516 * To keep the compatibility of the disk format,
517 * additional fields should be added behind cp_ifile_inode.
518 */
519 struct nilfs_inode cp_ifile_inode;
520 };
521
522 #define NILFS_MIN_CHECKPOINT_SIZE (64 + NILFS_MIN_INODE_SIZE)
523
524 /* checkpoint flags */
525 enum {
526 NILFS_CHECKPOINT_SNAPSHOT,
527 NILFS_CHECKPOINT_INVALID,
528 NILFS_CHECKPOINT_SKETCH,
529 NILFS_CHECKPOINT_MINOR,
530 };
531
532 #define NILFS_CHECKPOINT_FNS(flag, name) \
533 static inline void \
534 nilfs_checkpoint_set_##name(struct nilfs_checkpoint *cp) \
535 { \
536 cp->cp_flags = __cpu_to_le32(__le32_to_cpu(cp->cp_flags) | \
537 (1UL << NILFS_CHECKPOINT_##flag)); \
538 } \
539 static inline void \
540 nilfs_checkpoint_clear_##name(struct nilfs_checkpoint *cp) \
541 { \
542 cp->cp_flags = __cpu_to_le32(__le32_to_cpu(cp->cp_flags) & \
543 ~(1UL << NILFS_CHECKPOINT_##flag)); \
544 } \
545 static inline int \
546 nilfs_checkpoint_##name(const struct nilfs_checkpoint *cp) \
547 { \
548 return !!(__le32_to_cpu(cp->cp_flags) & \
549 (1UL << NILFS_CHECKPOINT_##flag)); \
550 }
551
552 NILFS_CHECKPOINT_FNS(SNAPSHOT, snapshot)
553 NILFS_CHECKPOINT_FNS(INVALID, invalid)
554 NILFS_CHECKPOINT_FNS(MINOR, minor)
555
556 /**
557 * struct nilfs_cpfile_header - checkpoint file header
558 * @ch_ncheckpoints: number of checkpoints
559 * @ch_nsnapshots: number of snapshots
560 * @ch_snapshot_list: snapshot list
561 */
562 struct nilfs_cpfile_header {
563 __le64 ch_ncheckpoints;
564 __le64 ch_nsnapshots;
565 struct nilfs_snapshot_list ch_snapshot_list;
566 };
567
568 #define NILFS_CPFILE_FIRST_CHECKPOINT_OFFSET \
569 ((sizeof(struct nilfs_cpfile_header) + \
570 sizeof(struct nilfs_checkpoint) - 1) / \
571 sizeof(struct nilfs_checkpoint))
572
573 /**
574 * struct nilfs_segment_usage - segment usage
575 * @su_lastmod: last modified timestamp
576 * @su_nblocks: number of blocks in segment
577 * @su_flags: flags
578 */
579 struct nilfs_segment_usage {
580 __le64 su_lastmod;
581 __le32 su_nblocks;
582 __le32 su_flags;
583 };
584
585 #define NILFS_MIN_SEGMENT_USAGE_SIZE 16
586
587 /* segment usage flag */
588 enum {
589 NILFS_SEGMENT_USAGE_ACTIVE,
590 NILFS_SEGMENT_USAGE_DIRTY,
591 NILFS_SEGMENT_USAGE_ERROR,
592 };
593
594 #define NILFS_SEGMENT_USAGE_FNS(flag, name) \
595 static inline void \
596 nilfs_segment_usage_set_##name(struct nilfs_segment_usage *su) \
597 { \
598 su->su_flags = __cpu_to_le32(__le32_to_cpu(su->su_flags) | \
599 (1UL << NILFS_SEGMENT_USAGE_##flag));\
600 } \
601 static inline void \
602 nilfs_segment_usage_clear_##name(struct nilfs_segment_usage *su) \
603 { \
604 su->su_flags = \
605 __cpu_to_le32(__le32_to_cpu(su->su_flags) & \
606 ~(1UL << NILFS_SEGMENT_USAGE_##flag)); \
607 } \
608 static inline int \
609 nilfs_segment_usage_##name(const struct nilfs_segment_usage *su) \
610 { \
611 return !!(__le32_to_cpu(su->su_flags) & \
612 (1UL << NILFS_SEGMENT_USAGE_##flag)); \
613 }
614
615 NILFS_SEGMENT_USAGE_FNS(ACTIVE, active)
616 NILFS_SEGMENT_USAGE_FNS(DIRTY, dirty)
617 NILFS_SEGMENT_USAGE_FNS(ERROR, error)
618
619 static inline void
620 nilfs_segment_usage_set_clean(struct nilfs_segment_usage *su)
621 {
622 su->su_lastmod = __cpu_to_le64(0);
623 su->su_nblocks = __cpu_to_le32(0);
624 su->su_flags = __cpu_to_le32(0);
625 }
626
627 static inline int
628 nilfs_segment_usage_clean(const struct nilfs_segment_usage *su)
629 {
630 return !__le32_to_cpu(su->su_flags);
631 }
632
633 /**
634 * struct nilfs_sufile_header - segment usage file header
635 * @sh_ncleansegs: number of clean segments
636 * @sh_ndirtysegs: number of dirty segments
637 * @sh_last_alloc: last allocated segment number
638 */
639 struct nilfs_sufile_header {
640 __le64 sh_ncleansegs;
641 __le64 sh_ndirtysegs;
642 __le64 sh_last_alloc;
643 /* ... */
644 };
645
646 #define NILFS_SUFILE_FIRST_SEGMENT_USAGE_OFFSET \
647 ((sizeof(struct nilfs_sufile_header) + \
648 sizeof(struct nilfs_segment_usage) - 1) / \
649 sizeof(struct nilfs_segment_usage))
650
651 #endif /* _LINUX_NILFS2_ONDISK_H */
652
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