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_bdev: block device
  47  * @ns_sem: semaphore for shared states
  48  * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
  49  * @ns_sbh: buffer heads of on-disk super blocks
  50  * @ns_sbp: pointers to super block data
  51  * @ns_sbwtime: previous write time of super block
  52  * @ns_sbwcount: write count of super block
  53  * @ns_sbsize: size of valid data in super block
  54  * @ns_mount_state: file system state
  55  * @ns_sb_update_freq: interval of periodical update of superblocks (in seconds)
  56  * @ns_seg_seq: segment sequence counter
  57  * @ns_segnum: index number of the latest full segment.
  58  * @ns_nextnum: index number of the full segment index to be used next
  59  * @ns_pseg_offset: offset of next partial segment in the current full segment
  60  * @ns_cno: next checkpoint number
  61  * @ns_ctime: write time of the last segment
  62  * @ns_nongc_ctime: write time of the last segment not for cleaner operation
  63  * @ns_ndirtyblks: Number of dirty data blocks
  64  * @ns_last_segment_lock: lock protecting fields for the latest segment
  65  * @ns_last_pseg: start block number of the latest segment
  66  * @ns_last_seq: sequence value of the latest segment
  67  * @ns_last_cno: checkpoint number of the latest segment
  68  * @ns_prot_seq: least sequence number of segments which must not be reclaimed
  69  * @ns_prev_seq: base sequence number used to decide if advance log cursor
  70  * @ns_writer: log writer
  71  * @ns_segctor_sem: semaphore protecting log write
  72  * @ns_dat: DAT file inode
  73  * @ns_cpfile: checkpoint file inode
  74  * @ns_sufile: segusage file inode
  75  * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
  76  * @ns_cptree_lock: lock protecting @ns_cptree
  77  * @ns_dirty_files: list of dirty files
  78  * @ns_inode_lock: lock protecting @ns_dirty_files
  79  * @ns_gc_inodes: dummy inodes to keep live blocks
  80  * @ns_next_generation: next generation number for inodes
  81  * @ns_next_gen_lock: lock protecting @ns_next_generation
  82  * @ns_mount_opt: mount options
  83  * @ns_resuid: uid for reserved blocks
  84  * @ns_resgid: gid for reserved blocks
  85  * @ns_interval: checkpoint creation interval
  86  * @ns_watermark: watermark for the number of dirty buffers
  87  * @ns_blocksize_bits: bit length of block size
  88  * @ns_blocksize: block size
  89  * @ns_nsegments: number of segments in filesystem
  90  * @ns_blocks_per_segment: number of blocks per segment
  91  * @ns_r_segments_percentage: reserved segments percentage
  92  * @ns_nrsvsegs: number of reserved segments
  93  * @ns_first_data_block: block number of first data block
  94  * @ns_inode_size: size of on-disk inode
  95  * @ns_first_ino: first not-special inode number
  96  * @ns_crc_seed: seed value of CRC32 calculation
  97  * @ns_dev_kobj: /sys/fs/<nilfs>/<device>
  98  * @ns_dev_kobj_unregister: completion state
  99  * @ns_dev_subgroups: <device> subgroups pointer
 100  */
 101 struct the_nilfs {
 102         unsigned long           ns_flags;
 103         int                     ns_flushed_device;
 104
 105         struct block_device    *ns_bdev;
 106         struct rw_semaphore     ns_sem;
 107         struct mutex            ns_snapshot_mount_mutex;
 108
 109         /*
 110          * used for
 111          * - loading the latest checkpoint exclusively.
 112          * - allocating a new full segment.
 113          */
 114         struct buffer_head     *ns_sbh[2];
 115         struct nilfs_super_block *ns_sbp[2];
 116         time_t                  ns_sbwtime;
 117         unsigned int            ns_sbwcount;
 118         unsigned int            ns_sbsize;
 119         unsigned int            ns_mount_state;
 120         unsigned int            ns_sb_update_freq;
 121
 122         /*
 123          * Following fields are dedicated to a writable FS-instance.
 124          * Except for the period seeking checkpoint, code outside the segment
 125          * constructor must lock a segment semaphore while accessing these
 126          * fields.
 127          * The writable FS-instance is sole during a lifetime of the_nilfs.
 128          */
 129         u64                     ns_seg_seq;
 130         __u64                   ns_segnum;
 131         __u64                   ns_nextnum;
 132         unsigned long           ns_pseg_offset;
 133         __u64                   ns_cno;
 134         time_t                  ns_ctime;
 135         time_t                  ns_nongc_ctime;
 136         atomic_t                ns_ndirtyblks;
 137
 138         /*
 139          * The following fields hold information on the latest partial segment
 140          * written to disk with a super root.  These fields are protected by
 141          * ns_last_segment_lock.
 142          */
 143         spinlock_t              ns_last_segment_lock;
 144         sector_t                ns_last_pseg;
 145         u64                     ns_last_seq;
 146         __u64                   ns_last_cno;
 147         u64                     ns_prot_seq;
 148         u64                     ns_prev_seq;
 149
 150         struct nilfs_sc_info   *ns_writer;
 151         struct rw_semaphore     ns_segctor_sem;
 152
 153         /*
 154          * Following fields are lock free except for the period before
 155          * the_nilfs is initialized.
 156          */
 157         struct inode           *ns_dat;
 158         struct inode           *ns_cpfile;
 159         struct inode           *ns_sufile;
 160
 161         /* Checkpoint tree */
 162         struct rb_root          ns_cptree;
 163         spinlock_t              ns_cptree_lock;
 164
 165         /* Dirty inode list */
 166         struct list_head        ns_dirty_files;
 167         spinlock_t              ns_inode_lock;
 168
 169         /* GC inode list */
 170         struct list_head        ns_gc_inodes;
 171
 172         /* Inode allocator */
 173         u32                     ns_next_generation;
 174         spinlock_t              ns_next_gen_lock;
 175
 176         /* Mount options */
 177         unsigned long           ns_mount_opt;
 178
 179         uid_t                   ns_resuid;
 180         gid_t                   ns_resgid;
 181         unsigned long           ns_interval;
 182         unsigned long           ns_watermark;
 183
 184         /* Disk layout information (static) */
 185         unsigned int            ns_blocksize_bits;
 186         unsigned int            ns_blocksize;
 187         unsigned long           ns_nsegments;
 188         unsigned long           ns_blocks_per_segment;
 189         unsigned long           ns_r_segments_percentage;
 190         unsigned long           ns_nrsvsegs;
 191         unsigned long           ns_first_data_block;
 192         int                     ns_inode_size;
 193         int                     ns_first_ino;
 194         u32                     ns_crc_seed;
 195
 196         /* /sys/fs/<nilfs>/<device> */
 197         struct kobject ns_dev_kobj;
 198         struct completion ns_dev_kobj_unregister;
 199         struct nilfs_sysfs_dev_subgroups *ns_dev_subgroups;
 200 };
 201
 202 #define THE_NILFS_FNS(bit, name)                                        \
 203 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 204 {                                                                       \
 205         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 206 }                                                                       \
 207 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 208 {                                                                       \
 209         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 210 }                                                                       \
 211 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 212 {                                                                       \
 213         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 214 }
 215
 216 THE_NILFS_FNS(INIT, init)
 217 THE_NILFS_FNS(DISCONTINUED, discontinued)
 218 THE_NILFS_FNS(GC_RUNNING, gc_running)
 219 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 220
 221 /*
 222  * Mount option operations
 223  */
 224 #define nilfs_clear_opt(nilfs, opt)  \
 225         ((nilfs)->ns_mount_opt &= ~NILFS_MOUNT_##opt)
 226 #define nilfs_set_opt(nilfs, opt)  \
 227         ((nilfs)->ns_mount_opt |= NILFS_MOUNT_##opt)
 228 #define nilfs_test_opt(nilfs, opt) ((nilfs)->ns_mount_opt & NILFS_MOUNT_##opt)
 229 #define nilfs_write_opt(nilfs, mask, opt)                               \
 230         ((nilfs)->ns_mount_opt =                                        \
 231                 (((nilfs)->ns_mount_opt & ~NILFS_MOUNT_##mask) |        \
 232                  NILFS_MOUNT_##opt))                                    \
 233
 234 /**
 235  * struct nilfs_root - nilfs root object
 236  * @cno: checkpoint number
 237  * @rb_node: red-black tree node
 238  * @count: refcount of this structure
 239  * @nilfs: nilfs object
 240  * @ifile: inode file
 241  * @inodes_count: number of inodes
 242  * @blocks_count: number of blocks
 243  * @snapshot_kobj: /sys/fs/<nilfs>/<device>/mounted_snapshots/<snapshot>
 244  * @snapshot_kobj_unregister: completion state for kernel object
 245  */
 246 struct nilfs_root {
 247         __u64 cno;
 248         struct rb_node rb_node;
 249
 250         atomic_t count;
 251         struct the_nilfs *nilfs;
 252         struct inode *ifile;
 253
 254         atomic64_t inodes_count;
 255         atomic64_t blocks_count;
 256
 257         /* /sys/fs/<nilfs>/<device>/mounted_snapshots/<snapshot> */
 258         struct kobject snapshot_kobj;
 259         struct completion snapshot_kobj_unregister;
 260 };
 261
 262 /* Special checkpoint number */
 263 #define NILFS_CPTREE_CURRENT_CNO        0
 264
 265 /* Minimum interval of periodical update of superblocks (in seconds) */
 266 #define NILFS_SB_FREQ           10
 267
 268 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 269 {
 270         u64 t = get_seconds();
 271
 272         return t < nilfs->ns_sbwtime ||
 273                 t > nilfs->ns_sbwtime + nilfs->ns_sb_update_freq;
 274 }
 275
 276 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
 277 {
 278         int flip_bits = nilfs->ns_sbwcount & 0x0FL;
 279
 280         return (flip_bits != 0x08 && flip_bits != 0x0F);
 281 }
 282
 283 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 284 struct the_nilfs *alloc_nilfs(struct block_device *bdev);
 285 void destroy_nilfs(struct the_nilfs *nilfs);
 286 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
 287 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
 288 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs);
 289 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs);
 290 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 291 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 292 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
 293 struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
 294                                              __u64 cno);
 295 void nilfs_put_root(struct nilfs_root *root);
 296 int nilfs_near_disk_full(struct the_nilfs *);
 297 void nilfs_fall_back_super_block(struct the_nilfs *);
 298 void nilfs_swap_super_block(struct the_nilfs *);
 299
 300
 301 static inline void nilfs_get_root(struct nilfs_root *root)
 302 {
 303         atomic_inc(&root->count);
 304 }
 305
 306 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
 307 {
 308         unsigned int valid_fs;
 309
 310         down_read(&nilfs->ns_sem);
 311         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 312         up_read(&nilfs->ns_sem);
 313         return valid_fs;
 314 }
 315
 316 static inline void
 317 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 318                         sector_t *seg_start, sector_t *seg_end)
 319 {
 320         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 321         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 322         if (segnum == 0)
 323                 *seg_start = nilfs->ns_first_data_block;
 324 }
 325
 326 static inline sector_t
 327 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 328 {
 329         return (segnum == 0) ? nilfs->ns_first_data_block :
 330                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 331 }
 332
 333 static inline __u64
 334 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 335 {
 336         sector_t segnum = blocknr;
 337
 338         sector_div(segnum, nilfs->ns_blocks_per_segment);
 339         return segnum;
 340 }
 341
 342 static inline void
 343 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 344                         sector_t seg_end)
 345 {
 346         /* terminate the current full segment (used in case of I/O-error) */
 347         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 348 }
 349
 350 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 351 {
 352         /* move forward with a full segment */
 353         nilfs->ns_segnum = nilfs->ns_nextnum;
 354         nilfs->ns_pseg_offset = 0;
 355         nilfs->ns_seg_seq++;
 356 }
 357
 358 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 359 {
 360         __u64 cno;
 361
 362         spin_lock(&nilfs->ns_last_segment_lock);
 363         cno = nilfs->ns_last_cno;
 364         spin_unlock(&nilfs->ns_last_segment_lock);
 365         return cno;
 366 }
 367
 368 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 369 {
 370         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 371 }
 372
 373 static inline int nilfs_flush_device(struct the_nilfs *nilfs)
 374 {
 375         int err;
 376
 377         if (!nilfs_test_opt(nilfs, BARRIER) || nilfs->ns_flushed_device)
 378                 return 0;
 379
 380         nilfs->ns_flushed_device = 1;
 381         /*
 382          * the store to ns_flushed_device must not be reordered after
 383          * blkdev_issue_flush().
 384          */
 385         smp_wmb();
 386
 387         err = blkdev_issue_flush(nilfs->ns_bdev, GFP_KERNEL, NULL);
 388         if (err != -EIO)
 389                 err = 0;
 390         return err;
 391 }
 392
 393 #endif /* _THE_NILFS_H */