fs/nilfs2/the_nilfs.h

   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  * Written by Ryusuke Konishi.
  17  *
  18  */
  19
  20 #ifndef _THE_NILFS_H
  21 #define _THE_NILFS_H
  22
  23 #include <linux/types.h>
  24 #include <linux/buffer_head.h>
  25 #include <linux/rbtree.h>
  26 #include <linux/fs.h>
  27 #include <linux/blkdev.h>
  28 #include <linux/backing-dev.h>
  29 #include <linux/slab.h>
  30
  31 struct nilfs_sc_info;
  32 struct nilfs_sysfs_dev_subgroups;
  33
  34 /* the_nilfs struct */
  35 enum {
  36         THE_NILFS_INIT = 0,     /* Information from super_block is set */
  37         THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
  38         THE_NILFS_GC_RUNNING,   /* gc process is running */
  39         THE_NILFS_SB_DIRTY,     /* super block is dirty */
  40 };
  41
  42 /**
  43  * struct the_nilfs - struct to supervise multiple nilfs mount points
  44  * @ns_flags: flags
  45  * @ns_flushed_device: flag indicating if all volatile data was flushed
  46  * @ns_sb: back pointer to super block instance
  47  * @ns_bdev: block device
  48  * @ns_sem: semaphore for shared states
  49  * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
  50  * @ns_sbh: buffer heads of on-disk super blocks
  51  * @ns_sbp: pointers to super block data
  52  * @ns_sbwtime: previous write time of super block
  53  * @ns_sbwcount: write count of super block
  54  * @ns_sbsize: size of valid data in super block
  55  * @ns_mount_state: file system state
  56  * @ns_sb_update_freq: interval of periodical update of superblocks (in seconds)
  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  * @ns_dev_kobj: /sys/fs/<nilfs>/<device>
  99  * @ns_dev_kobj_unregister: completion state
 100  * @ns_dev_subgroups: <device> subgroups pointer
 101  */
 102 struct the_nilfs {
 103         unsigned long           ns_flags;
 104         int                     ns_flushed_device;
 105
 106         struct super_block     *ns_sb;
 107         struct block_device    *ns_bdev;
 108         struct rw_semaphore     ns_sem;
 109         struct mutex            ns_snapshot_mount_mutex;
 110
 111         /*
 112          * used for
 113          * - loading the latest checkpoint exclusively.
 114          * - allocating a new full segment.
 115          */
 116         struct buffer_head     *ns_sbh[2];
 117         struct nilfs_super_block *ns_sbp[2];
 118         time_t                  ns_sbwtime;
 119         unsigned int            ns_sbwcount;
 120         unsigned int            ns_sbsize;
 121         unsigned int            ns_mount_state;
 122         unsigned int            ns_sb_update_freq;
 123
 124         /*
 125          * The following fields are updated by a writable FS-instance.
 126          * These fields are protected by ns_segctor_sem outside load_nilfs().
 127          */
 128         u64                     ns_seg_seq;
 129         __u64                   ns_segnum;
 130         __u64                   ns_nextnum;
 131         unsigned long           ns_pseg_offset;
 132         __u64                   ns_cno;
 133         time_t                  ns_ctime;
 134         time_t                  ns_nongc_ctime;
 135         atomic_t                ns_ndirtyblks;
 136
 137         /*
 138          * The following fields hold information on the latest partial segment
 139          * written to disk with a super root.  These fields are protected by
 140          * ns_last_segment_lock.
 141          */
 142         spinlock_t              ns_last_segment_lock;
 143         sector_t                ns_last_pseg;
 144         u64                     ns_last_seq;
 145         __u64                   ns_last_cno;
 146         u64                     ns_prot_seq;
 147         u64                     ns_prev_seq;
 148
 149         struct nilfs_sc_info   *ns_writer;
 150         struct rw_semaphore     ns_segctor_sem;
 151
 152         /*
 153          * Following fields are lock free except for the period before
 154          * the_nilfs is initialized.
 155          */
 156         struct inode           *ns_dat;
 157         struct inode           *ns_cpfile;
 158         struct inode           *ns_sufile;
 159
 160         /* Checkpoint tree */
 161         struct rb_root          ns_cptree;
 162         spinlock_t              ns_cptree_lock;
 163
 164         /* Dirty inode list */
 165         struct list_head        ns_dirty_files;
 166         spinlock_t              ns_inode_lock;
 167
 168         /* GC inode list */
 169         struct list_head        ns_gc_inodes;
 170
 171         /* Inode allocator */
 172         u32                     ns_next_generation;
 173         spinlock_t              ns_next_gen_lock;
 174
 175         /* Mount options */
 176         unsigned long           ns_mount_opt;
 177
 178         uid_t                   ns_resuid;
 179         gid_t                   ns_resgid;
 180         unsigned long           ns_interval;
 181         unsigned long           ns_watermark;
 182
 183         /* Disk layout information (static) */
 184         unsigned int            ns_blocksize_bits;
 185         unsigned int            ns_blocksize;
 186         unsigned long           ns_nsegments;
 187         unsigned long           ns_blocks_per_segment;
 188         unsigned long           ns_r_segments_percentage;
 189         unsigned long           ns_nrsvsegs;
 190         unsigned long           ns_first_data_block;
 191         int                     ns_inode_size;
 192         int                     ns_first_ino;
 193         u32                     ns_crc_seed;
 194
 195         /* /sys/fs/<nilfs>/<device> */
 196         struct kobject ns_dev_kobj;
 197         struct completion ns_dev_kobj_unregister;
 198         struct nilfs_sysfs_dev_subgroups *ns_dev_subgroups;
 199 };
 200
 201 #define THE_NILFS_FNS(bit, name)                                        \
 202 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 203 {                                                                       \
 204         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 205 }                                                                       \
 206 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 207 {                                                                       \
 208         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 209 }                                                                       \
 210 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 211 {                                                                       \
 212         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 213 }
 214
 215 THE_NILFS_FNS(INIT, init)
 216 THE_NILFS_FNS(DISCONTINUED, discontinued)
 217 THE_NILFS_FNS(GC_RUNNING, gc_running)
 218 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 219
 220 /*
 221  * Mount option operations
 222  */
 223 #define nilfs_clear_opt(nilfs, opt)  \
 224         ((nilfs)->ns_mount_opt &= ~NILFS_MOUNT_##opt)
 225 #define nilfs_set_opt(nilfs, opt)  \
 226         ((nilfs)->ns_mount_opt |= NILFS_MOUNT_##opt)
 227 #define nilfs_test_opt(nilfs, opt) ((nilfs)->ns_mount_opt & NILFS_MOUNT_##opt)
 228 #define nilfs_write_opt(nilfs, mask, opt)                               \
 229         ((nilfs)->ns_mount_opt =                                        \
 230                 (((nilfs)->ns_mount_opt & ~NILFS_MOUNT_##mask) |        \
 231                  NILFS_MOUNT_##opt))                                    \
 232
 233 /**
 234  * struct nilfs_root - nilfs root object
 235  * @cno: checkpoint number
 236  * @rb_node: red-black tree node
 237  * @count: refcount of this structure
 238  * @nilfs: nilfs object
 239  * @ifile: inode file
 240  * @inodes_count: number of inodes
 241  * @blocks_count: number of blocks
 242  * @snapshot_kobj: /sys/fs/<nilfs>/<device>/mounted_snapshots/<snapshot>
 243  * @snapshot_kobj_unregister: completion state for kernel object
 244  */
 245 struct nilfs_root {
 246         __u64 cno;
 247         struct rb_node rb_node;
 248
 249         atomic_t count;
 250         struct the_nilfs *nilfs;
 251         struct inode *ifile;
 252
 253         atomic64_t inodes_count;
 254         atomic64_t blocks_count;
 255
 256         /* /sys/fs/<nilfs>/<device>/mounted_snapshots/<snapshot> */
 257         struct kobject snapshot_kobj;
 258         struct completion snapshot_kobj_unregister;
 259 };
 260
 261 /* Special checkpoint number */
 262 #define NILFS_CPTREE_CURRENT_CNO        0
 263
 264 /* Minimum interval of periodical update of superblocks (in seconds) */
 265 #define NILFS_SB_FREQ           10
 266
 267 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 268 {
 269         u64 t = get_seconds();
 270
 271         return t < nilfs->ns_sbwtime ||
 272                 t > nilfs->ns_sbwtime + nilfs->ns_sb_update_freq;
 273 }
 274
 275 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
 276 {
 277         int flip_bits = nilfs->ns_sbwcount & 0x0FL;
 278
 279         return (flip_bits != 0x08 && flip_bits != 0x0F);
 280 }
 281
 282 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 283 struct the_nilfs *alloc_nilfs(struct super_block *sb);
 284 void destroy_nilfs(struct the_nilfs *nilfs);
 285 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
 286 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
 287 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs);
 288 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs);
 289 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 290 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 291 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
 292 struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
 293                                              __u64 cno);
 294 void nilfs_put_root(struct nilfs_root *root);
 295 int nilfs_near_disk_full(struct the_nilfs *);
 296 void nilfs_fall_back_super_block(struct the_nilfs *);
 297 void nilfs_swap_super_block(struct the_nilfs *);
 298
 299
 300 static inline void nilfs_get_root(struct nilfs_root *root)
 301 {
 302         atomic_inc(&root->count);
 303 }
 304
 305 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
 306 {
 307         unsigned int valid_fs;
 308
 309         down_read(&nilfs->ns_sem);
 310         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 311         up_read(&nilfs->ns_sem);
 312         return valid_fs;
 313 }
 314
 315 static inline void
 316 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 317                         sector_t *seg_start, sector_t *seg_end)
 318 {
 319         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 320         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 321         if (segnum == 0)
 322                 *seg_start = nilfs->ns_first_data_block;
 323 }
 324
 325 static inline sector_t
 326 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 327 {
 328         return (segnum == 0) ? nilfs->ns_first_data_block :
 329                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 330 }
 331
 332 static inline __u64
 333 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 334 {
 335         sector_t segnum = blocknr;
 336
 337         sector_div(segnum, nilfs->ns_blocks_per_segment);
 338         return segnum;
 339 }
 340
 341 static inline void
 342 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 343                         sector_t seg_end)
 344 {
 345         /* terminate the current full segment (used in case of I/O-error) */
 346         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 347 }
 348
 349 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 350 {
 351         /* move forward with a full segment */
 352         nilfs->ns_segnum = nilfs->ns_nextnum;
 353         nilfs->ns_pseg_offset = 0;
 354         nilfs->ns_seg_seq++;
 355 }
 356
 357 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 358 {
 359         __u64 cno;
 360
 361         spin_lock(&nilfs->ns_last_segment_lock);
 362         cno = nilfs->ns_last_cno;
 363         spin_unlock(&nilfs->ns_last_segment_lock);
 364         return cno;
 365 }
 366
 367 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 368 {
 369         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 370 }
 371
 372 static inline int nilfs_flush_device(struct the_nilfs *nilfs)
 373 {
 374         int err;
 375
 376         if (!nilfs_test_opt(nilfs, BARRIER) || nilfs->ns_flushed_device)
 377                 return 0;
 378
 379         nilfs->ns_flushed_device = 1;
 380         /*
 381          * the store to ns_flushed_device must not be reordered after
 382          * blkdev_issue_flush().
 383          */
 384         smp_wmb();
 385
 386         err = blkdev_issue_flush(nilfs->ns_bdev, GFP_KERNEL, NULL);
 387         if (err != -EIO)
 388                 err = 0;
 389         return err;
 390 }
 391
 392 #endif /* _THE_NILFS_H */