nilfs2: add omitted comments for structures in nilfs2_fs.h
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / nilfs2 / the_nilfs.h
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1/*
2 * the_nilfs.h - the_nilfs shared structure.
3 *
4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 *
20 * Written by Ryusuke Konishi <ryusuke@osrg.net>
21 *
22 */
23
24#ifndef _THE_NILFS_H
25#define _THE_NILFS_H
26
27#include <linux/types.h>
28#include <linux/buffer_head.h>
ba65ae47 29#include <linux/rbtree.h>
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30#include <linux/fs.h>
31#include <linux/blkdev.h>
32#include <linux/backing-dev.h>
5a0e3ad6 33#include <linux/slab.h>
65b4643d 34
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35struct nilfs_sc_info;
36
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37/* the_nilfs struct */
38enum {
39 THE_NILFS_INIT = 0, /* Information from super_block is set */
65b4643d 40 THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
1cf58fa8 41 THE_NILFS_GC_RUNNING, /* gc process is running */
e605f0a7 42 THE_NILFS_SB_DIRTY, /* super block is dirty */
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43};
44
45/**
46 * struct the_nilfs - struct to supervise multiple nilfs mount points
47 * @ns_flags: flags
65b4643d 48 * @ns_bdev: block device
65b4643d 49 * @ns_sem: semaphore for shared states
572d8b39 50 * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
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51 * @ns_sbh: buffer heads of on-disk super blocks
52 * @ns_sbp: pointers to super block data
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53 * @ns_sbwtime: previous write time of super block
54 * @ns_sbwcount: write count of super block
e339ad31 55 * @ns_sbsize: size of valid data in super block
6b0f3393 56 * @ns_mount_state: file system state
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57 * @ns_seg_seq: segment sequence counter
58 * @ns_segnum: index number of the latest full segment.
59 * @ns_nextnum: index number of the full segment index to be used next
60 * @ns_pseg_offset: offset of next partial segment in the current full segment
61 * @ns_cno: next checkpoint number
62 * @ns_ctime: write time of the last segment
63 * @ns_nongc_ctime: write time of the last segment not for cleaner operation
64 * @ns_ndirtyblks: Number of dirty data blocks
65 * @ns_last_segment_lock: lock protecting fields for the latest segment
66 * @ns_last_pseg: start block number of the latest segment
67 * @ns_last_seq: sequence value of the latest segment
68 * @ns_last_cno: checkpoint number of the latest segment
2c2e52fc 69 * @ns_prot_seq: least sequence number of segments which must not be reclaimed
32502047 70 * @ns_prev_seq: base sequence number used to decide if advance log cursor
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71 * @ns_writer: log writer
72 * @ns_segctor_sem: semaphore protecting log write
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73 * @ns_dat: DAT file inode
74 * @ns_cpfile: checkpoint file inode
75 * @ns_sufile: segusage file inode
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76 * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
77 * @ns_cptree_lock: lock protecting @ns_cptree
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78 * @ns_dirty_files: list of dirty files
79 * @ns_inode_lock: lock protecting @ns_dirty_files
65b4643d 80 * @ns_gc_inodes: dummy inodes to keep live blocks
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81 * @ns_next_generation: next generation number for inodes
82 * @ns_next_gen_lock: lock protecting @ns_next_generation
3b2ce58b 83 * @ns_mount_opt: mount options
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84 * @ns_resuid: uid for reserved blocks
85 * @ns_resgid: gid for reserved blocks
86 * @ns_interval: checkpoint creation interval
87 * @ns_watermark: watermark for the number of dirty buffers
65b4643d 88 * @ns_blocksize_bits: bit length of block size
92c60cca 89 * @ns_blocksize: block size
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90 * @ns_nsegments: number of segments in filesystem
91 * @ns_blocks_per_segment: number of blocks per segment
92 * @ns_r_segments_percentage: reserved segments percentage
93 * @ns_nrsvsegs: number of reserved segments
94 * @ns_first_data_block: block number of first data block
95 * @ns_inode_size: size of on-disk inode
96 * @ns_first_ino: first not-special inode number
97 * @ns_crc_seed: seed value of CRC32 calculation
98 */
99struct the_nilfs {
100 unsigned long ns_flags;
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101
102 struct block_device *ns_bdev;
65b4643d 103 struct rw_semaphore ns_sem;
572d8b39 104 struct mutex ns_snapshot_mount_mutex;
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105
106 /*
107 * used for
108 * - loading the latest checkpoint exclusively.
109 * - allocating a new full segment.
110 * - protecting s_dirt in the super_block struct
111 * (see nilfs_write_super) and the following fields.
112 */
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113 struct buffer_head *ns_sbh[2];
114 struct nilfs_super_block *ns_sbp[2];
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115 time_t ns_sbwtime;
116 unsigned ns_sbwcount;
e339ad31 117 unsigned ns_sbsize;
65b4643d 118 unsigned ns_mount_state;
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119
120 /*
121 * Following fields are dedicated to a writable FS-instance.
122 * Except for the period seeking checkpoint, code outside the segment
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123 * constructor must lock a segment semaphore while accessing these
124 * fields.
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125 * The writable FS-instance is sole during a lifetime of the_nilfs.
126 */
127 u64 ns_seg_seq;
128 __u64 ns_segnum;
129 __u64 ns_nextnum;
130 unsigned long ns_pseg_offset;
131 __u64 ns_cno;
132 time_t ns_ctime;
133 time_t ns_nongc_ctime;
134 atomic_t ns_ndirtyblks;
135
136 /*
137 * The following fields hold information on the latest partial segment
138 * written to disk with a super root. These fields are protected by
139 * ns_last_segment_lock.
140 */
141 spinlock_t ns_last_segment_lock;
142 sector_t ns_last_pseg;
143 u64 ns_last_seq;
144 __u64 ns_last_cno;
2c2e52fc 145 u64 ns_prot_seq;
32502047 146 u64 ns_prev_seq;
65b4643d 147
3fd3fe5a 148 struct nilfs_sc_info *ns_writer;
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149 struct rw_semaphore ns_segctor_sem;
150
151 /*
152 * Following fields are lock free except for the period before
153 * the_nilfs is initialized.
154 */
155 struct inode *ns_dat;
156 struct inode *ns_cpfile;
157 struct inode *ns_sufile;
65b4643d 158
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159 /* Checkpoint tree */
160 struct rb_root ns_cptree;
161 spinlock_t ns_cptree_lock;
162
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163 /* Dirty inode list */
164 struct list_head ns_dirty_files;
165 spinlock_t ns_inode_lock;
166
263d90ce 167 /* GC inode list */
65b4643d 168 struct list_head ns_gc_inodes;
65b4643d 169
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170 /* Inode allocator */
171 u32 ns_next_generation;
172 spinlock_t ns_next_gen_lock;
173
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174 /* Mount options */
175 unsigned long ns_mount_opt;
176
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177 uid_t ns_resuid;
178 gid_t ns_resgid;
179 unsigned long ns_interval;
180 unsigned long ns_watermark;
181
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182 /* Disk layout information (static) */
183 unsigned int ns_blocksize_bits;
92c60cca 184 unsigned int ns_blocksize;
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185 unsigned long ns_nsegments;
186 unsigned long ns_blocks_per_segment;
187 unsigned long ns_r_segments_percentage;
188 unsigned long ns_nrsvsegs;
189 unsigned long ns_first_data_block;
190 int ns_inode_size;
191 int ns_first_ino;
192 u32 ns_crc_seed;
193};
194
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195#define THE_NILFS_FNS(bit, name) \
196static inline void set_nilfs_##name(struct the_nilfs *nilfs) \
197{ \
198 set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
199} \
200static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \
201{ \
202 clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
203} \
204static inline int nilfs_##name(struct the_nilfs *nilfs) \
205{ \
206 return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
207}
208
209THE_NILFS_FNS(INIT, init)
65b4643d 210THE_NILFS_FNS(DISCONTINUED, discontinued)
1cf58fa8 211THE_NILFS_FNS(GC_RUNNING, gc_running)
e605f0a7 212THE_NILFS_FNS(SB_DIRTY, sb_dirty)
65b4643d 213
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214/*
215 * Mount option operations
216 */
217#define nilfs_clear_opt(nilfs, opt) \
218 do { (nilfs)->ns_mount_opt &= ~NILFS_MOUNT_##opt; } while (0)
219#define nilfs_set_opt(nilfs, opt) \
220 do { (nilfs)->ns_mount_opt |= NILFS_MOUNT_##opt; } while (0)
221#define nilfs_test_opt(nilfs, opt) ((nilfs)->ns_mount_opt & NILFS_MOUNT_##opt)
222#define nilfs_write_opt(nilfs, mask, opt) \
223 do { (nilfs)->ns_mount_opt = \
224 (((nilfs)->ns_mount_opt & ~NILFS_MOUNT_##mask) | \
225 NILFS_MOUNT_##opt); \
226 } while (0)
227
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228/**
229 * struct nilfs_root - nilfs root object
230 * @cno: checkpoint number
231 * @rb_node: red-black tree node
232 * @count: refcount of this structure
233 * @nilfs: nilfs object
234 * @ifile: inode file
235 * @root: root inode
236 * @inodes_count: number of inodes
237 * @blocks_count: number of blocks (Reserved)
238 */
239struct nilfs_root {
240 __u64 cno;
241 struct rb_node rb_node;
242
243 atomic_t count;
244 struct the_nilfs *nilfs;
245 struct inode *ifile;
246
247 atomic_t inodes_count;
248 atomic_t blocks_count;
249};
250
251/* Special checkpoint number */
252#define NILFS_CPTREE_CURRENT_CNO 0
253
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254/* Minimum interval of periodical update of superblocks (in seconds) */
255#define NILFS_SB_FREQ 10
e339ad31 256
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257static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
258{
259 u64 t = get_seconds();
b2ac86e1 260 return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
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261}
262
b2ac86e1 263static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
79efdd94 264{
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265 int flip_bits = nilfs->ns_sbwcount & 0x0FL;
266 return (flip_bits != 0x08 && flip_bits != 0x0F);
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267}
268
65b4643d 269void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
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270struct the_nilfs *alloc_nilfs(struct block_device *bdev);
271void destroy_nilfs(struct the_nilfs *nilfs);
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272int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
273int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
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274unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs);
275void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs);
e902ec99 276int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
65b4643d 277int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
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278struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
279struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
280 __u64 cno);
281void nilfs_put_root(struct nilfs_root *root);
65b4643d 282int nilfs_near_disk_full(struct the_nilfs *);
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283void nilfs_fall_back_super_block(struct the_nilfs *);
284void nilfs_swap_super_block(struct the_nilfs *);
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285
286
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287static inline void nilfs_get_root(struct nilfs_root *root)
288{
289 atomic_inc(&root->count);
290}
291
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292static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
293{
294 unsigned valid_fs;
295
296 down_read(&nilfs->ns_sem);
297 valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
298 up_read(&nilfs->ns_sem);
299 return valid_fs;
300}
301
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302static inline void
303nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
304 sector_t *seg_start, sector_t *seg_end)
305{
306 *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
307 *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
308 if (segnum == 0)
309 *seg_start = nilfs->ns_first_data_block;
310}
311
312static inline sector_t
313nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
314{
315 return (segnum == 0) ? nilfs->ns_first_data_block :
316 (sector_t)nilfs->ns_blocks_per_segment * segnum;
317}
318
319static inline __u64
320nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
321{
322 sector_t segnum = blocknr;
323
324 sector_div(segnum, nilfs->ns_blocks_per_segment);
325 return segnum;
326}
327
328static inline void
329nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
330 sector_t seg_end)
331{
332 /* terminate the current full segment (used in case of I/O-error) */
333 nilfs->ns_pseg_offset = seg_end - seg_start + 1;
334}
335
336static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
337{
338 /* move forward with a full segment */
339 nilfs->ns_segnum = nilfs->ns_nextnum;
340 nilfs->ns_pseg_offset = 0;
341 nilfs->ns_seg_seq++;
342}
343
344static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
345{
346 __u64 cno;
347
348 spin_lock(&nilfs->ns_last_segment_lock);
349 cno = nilfs->ns_last_cno;
350 spin_unlock(&nilfs->ns_last_segment_lock);
351 return cno;
352}
353
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354static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
355{
356 return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
357}
358
65b4643d 359#endif /* _THE_NILFS_H */