linux/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>
  29#include <linux/rbtree.h>
  30#include <linux/fs.h>
  31#include <linux/blkdev.h>
  32#include <linux/backing-dev.h>
  33#include <linux/slab.h>
  34
  35struct nilfs_sc_info;
  36
  37/* the_nilfs struct */
  38enum {
  39        THE_NILFS_INIT = 0,     /* Information from super_block is set */
  40        THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
  41        THE_NILFS_GC_RUNNING,   /* gc process is running */
  42        THE_NILFS_SB_DIRTY,     /* super block is dirty */
  43};
  44
  45/**
  46 * struct the_nilfs - struct to supervise multiple nilfs mount points
  47 * @ns_flags: flags
  48 * @ns_bdev: block device
  49 * @ns_sem: semaphore for shared states
  50 * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
  51 * @ns_sbh: buffer heads of on-disk super blocks
  52 * @ns_sbp: pointers to super block data
  53 * @ns_sbwtime: previous write time of super block
  54 * @ns_sbwcount: write count of super block
  55 * @ns_sbsize: size of valid data in super block
  56 * @ns_mount_state: file system state
  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
  69 * @ns_prot_seq: least sequence number of segments which must not be reclaimed
  70 * @ns_prev_seq: base sequence number used to decide if advance log cursor
  71 * @ns_writer: log writer
  72 * @ns_segctor_sem: semaphore protecting log write
  73 * @ns_dat: DAT file inode
  74 * @ns_cpfile: checkpoint file inode
  75 * @ns_sufile: segusage file inode
  76 * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
  77 * @ns_cptree_lock: lock protecting @ns_cptree
  78 * @ns_dirty_files: list of dirty files
  79 * @ns_inode_lock: lock protecting @ns_dirty_files
  80 * @ns_gc_inodes: dummy inodes to keep live blocks
  81 * @ns_next_generation: next generation number for inodes
  82 * @ns_next_gen_lock: lock protecting @ns_next_generation
  83 * @ns_mount_opt: mount options
  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
  88 * @ns_blocksize_bits: bit length of block size
  89 * @ns_blocksize: block size
  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;
 101
 102        struct block_device    *ns_bdev;
 103        struct rw_semaphore     ns_sem;
 104        struct mutex            ns_snapshot_mount_mutex;
 105
 106        /*
 107         * used for
 108         * - loading the latest checkpoint exclusively.
 109         * - allocating a new full segment.
 110         */
 111        struct buffer_head     *ns_sbh[2];
 112        struct nilfs_super_block *ns_sbp[2];
 113        time_t                  ns_sbwtime;
 114        unsigned                ns_sbwcount;
 115        unsigned                ns_sbsize;
 116        unsigned                ns_mount_state;
 117
 118        /*
 119         * Following fields are dedicated to a writable FS-instance.
 120         * Except for the period seeking checkpoint, code outside the segment
 121         * constructor must lock a segment semaphore while accessing these
 122         * fields.
 123         * The writable FS-instance is sole during a lifetime of the_nilfs.
 124         */
 125        u64                     ns_seg_seq;
 126        __u64                   ns_segnum;
 127        __u64                   ns_nextnum;
 128        unsigned long           ns_pseg_offset;
 129        __u64                   ns_cno;
 130        time_t                  ns_ctime;
 131        time_t                  ns_nongc_ctime;
 132        atomic_t                ns_ndirtyblks;
 133
 134        /*
 135         * The following fields hold information on the latest partial segment
 136         * written to disk with a super root.  These fields are protected by
 137         * ns_last_segment_lock.
 138         */
 139        spinlock_t              ns_last_segment_lock;
 140        sector_t                ns_last_pseg;
 141        u64                     ns_last_seq;
 142        __u64                   ns_last_cno;
 143        u64                     ns_prot_seq;
 144        u64                     ns_prev_seq;
 145
 146        struct nilfs_sc_info   *ns_writer;
 147        struct rw_semaphore     ns_segctor_sem;
 148
 149        /*
 150         * Following fields are lock free except for the period before
 151         * the_nilfs is initialized.
 152         */
 153        struct inode           *ns_dat;
 154        struct inode           *ns_cpfile;
 155        struct inode           *ns_sufile;
 156
 157        /* Checkpoint tree */
 158        struct rb_root          ns_cptree;
 159        spinlock_t              ns_cptree_lock;
 160
 161        /* Dirty inode list */
 162        struct list_head        ns_dirty_files;
 163        spinlock_t              ns_inode_lock;
 164
 165        /* GC inode list */
 166        struct list_head        ns_gc_inodes;
 167
 168        /* Inode allocator */
 169        u32                     ns_next_generation;
 170        spinlock_t              ns_next_gen_lock;
 171
 172        /* Mount options */
 173        unsigned long           ns_mount_opt;
 174
 175        uid_t                   ns_resuid;
 176        gid_t                   ns_resgid;
 177        unsigned long           ns_interval;
 178        unsigned long           ns_watermark;
 179
 180        /* Disk layout information (static) */
 181        unsigned int            ns_blocksize_bits;
 182        unsigned int            ns_blocksize;
 183        unsigned long           ns_nsegments;
 184        unsigned long           ns_blocks_per_segment;
 185        unsigned long           ns_r_segments_percentage;
 186        unsigned long           ns_nrsvsegs;
 187        unsigned long           ns_first_data_block;
 188        int                     ns_inode_size;
 189        int                     ns_first_ino;
 190        u32                     ns_crc_seed;
 191};
 192
 193#define THE_NILFS_FNS(bit, name)                                        \
 194static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 195{                                                                       \
 196        set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 197}                                                                       \
 198static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 199{                                                                       \
 200        clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 201}                                                                       \
 202static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 203{                                                                       \
 204        return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 205}
 206
 207THE_NILFS_FNS(INIT, init)
 208THE_NILFS_FNS(DISCONTINUED, discontinued)
 209THE_NILFS_FNS(GC_RUNNING, gc_running)
 210THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 211
 212/*
 213 * Mount option operations
 214 */
 215#define nilfs_clear_opt(nilfs, opt)  \
 216        do { (nilfs)->ns_mount_opt &= ~NILFS_MOUNT_##opt; } while (0)
 217#define nilfs_set_opt(nilfs, opt)  \
 218        do { (nilfs)->ns_mount_opt |= NILFS_MOUNT_##opt; } while (0)
 219#define nilfs_test_opt(nilfs, opt) ((nilfs)->ns_mount_opt & NILFS_MOUNT_##opt)
 220#define nilfs_write_opt(nilfs, mask, opt)                               \
 221        do { (nilfs)->ns_mount_opt =                                    \
 222                (((nilfs)->ns_mount_opt & ~NILFS_MOUNT_##mask) |        \
 223                 NILFS_MOUNT_##opt);                                    \
 224        } while (0)
 225
 226/**
 227 * struct nilfs_root - nilfs root object
 228 * @cno: checkpoint number
 229 * @rb_node: red-black tree node
 230 * @count: refcount of this structure
 231 * @nilfs: nilfs object
 232 * @ifile: inode file
 233 * @inodes_count: number of inodes
 234 * @blocks_count: number of blocks
 235 */
 236struct nilfs_root {
 237        __u64 cno;
 238        struct rb_node rb_node;
 239
 240        atomic_t count;
 241        struct the_nilfs *nilfs;
 242        struct inode *ifile;
 243
 244        atomic_t inodes_count;
 245        atomic_t blocks_count;
 246};
 247
 248/* Special checkpoint number */
 249#define NILFS_CPTREE_CURRENT_CNO        0
 250
 251/* Minimum interval of periodical update of superblocks (in seconds) */
 252#define NILFS_SB_FREQ           10
 253
 254static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 255{
 256        u64 t = get_seconds();
 257        return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
 258}
 259
 260static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
 261{
 262        int flip_bits = nilfs->ns_sbwcount & 0x0FL;
 263        return (flip_bits != 0x08 && flip_bits != 0x0F);
 264}
 265
 266void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 267struct the_nilfs *alloc_nilfs(struct block_device *bdev);
 268void destroy_nilfs(struct the_nilfs *nilfs);
 269int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
 270int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
 271unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs);
 272void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs);
 273int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 274int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 275struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
 276struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
 277                                             __u64 cno);
 278void nilfs_put_root(struct nilfs_root *root);
 279int nilfs_near_disk_full(struct the_nilfs *);
 280void nilfs_fall_back_super_block(struct the_nilfs *);
 281void nilfs_swap_super_block(struct the_nilfs *);
 282
 283
 284static inline void nilfs_get_root(struct nilfs_root *root)
 285{
 286        atomic_inc(&root->count);
 287}
 288
 289static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
 290{
 291        unsigned valid_fs;
 292
 293        down_read(&nilfs->ns_sem);
 294        valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 295        up_read(&nilfs->ns_sem);
 296        return valid_fs;
 297}
 298
 299static inline void
 300nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 301                        sector_t *seg_start, sector_t *seg_end)
 302{
 303        *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 304        *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 305        if (segnum == 0)
 306                *seg_start = nilfs->ns_first_data_block;
 307}
 308
 309static inline sector_t
 310nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 311{
 312        return (segnum == 0) ? nilfs->ns_first_data_block :
 313                (sector_t)nilfs->ns_blocks_per_segment * segnum;
 314}
 315
 316static inline __u64
 317nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 318{
 319        sector_t segnum = blocknr;
 320
 321        sector_div(segnum, nilfs->ns_blocks_per_segment);
 322        return segnum;
 323}
 324
 325static inline void
 326nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 327                        sector_t seg_end)
 328{
 329        /* terminate the current full segment (used in case of I/O-error) */
 330        nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 331}
 332
 333static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 334{
 335        /* move forward with a full segment */
 336        nilfs->ns_segnum = nilfs->ns_nextnum;
 337        nilfs->ns_pseg_offset = 0;
 338        nilfs->ns_seg_seq++;
 339}
 340
 341static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 342{
 343        __u64 cno;
 344
 345        spin_lock(&nilfs->ns_last_segment_lock);
 346        cno = nilfs->ns_last_cno;
 347        spin_unlock(&nilfs->ns_last_segment_lock);
 348        return cno;
 349}
 350
 351static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 352{
 353        return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 354}
 355
 356#endif /* _THE_NILFS_H */
 357
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