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  * 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
  35 struct nilfs_sc_info;
  36
  37 /* the_nilfs struct */
  38 enum {
  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  */
  99 struct 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          * - protecting s_dirt in the super_block struct
 111          *   (see nilfs_write_super) and the following fields.
 112          */
 113         struct buffer_head     *ns_sbh[2];
 114         struct nilfs_super_block *ns_sbp[2];
 115         time_t                  ns_sbwtime;
 116         unsigned                ns_sbwcount;
 117         unsigned                ns_sbsize;
 118         unsigned                ns_mount_state;
 119
 120         /*
 121          * Following fields are dedicated to a writable FS-instance.
 122          * Except for the period seeking checkpoint, code outside the segment
 123          * constructor must lock a segment semaphore while accessing these
 124          * fields.
 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;
 145         u64                     ns_prot_seq;
 146         u64                     ns_prev_seq;
 147
 148         struct nilfs_sc_info   *ns_writer;
 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;
 158
 159         /* Checkpoint tree */
 160         struct rb_root          ns_cptree;
 161         spinlock_t              ns_cptree_lock;
 162
 163         /* Dirty inode list */
 164         struct list_head        ns_dirty_files;
 165         spinlock_t              ns_inode_lock;
 166
 167         /* GC inode list */
 168         struct list_head        ns_gc_inodes;
 169
 170         /* Inode allocator */
 171         u32                     ns_next_generation;
 172         spinlock_t              ns_next_gen_lock;
 173
 174         /* Mount options */
 175         unsigned long           ns_mount_opt;
 176
 177         uid_t                   ns_resuid;
 178         gid_t                   ns_resgid;
 179         unsigned long           ns_interval;
 180         unsigned long           ns_watermark;
 181
 182         /* Disk layout information (static) */
 183         unsigned int            ns_blocksize_bits;
 184         unsigned int            ns_blocksize;
 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
 195 #define THE_NILFS_FNS(bit, name)                                        \
 196 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 197 {                                                                       \
 198         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 199 }                                                                       \
 200 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 201 {                                                                       \
 202         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 203 }                                                                       \
 204 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 205 {                                                                       \
 206         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 207 }
 208
 209 THE_NILFS_FNS(INIT, init)
 210 THE_NILFS_FNS(DISCONTINUED, discontinued)
 211 THE_NILFS_FNS(GC_RUNNING, gc_running)
 212 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 213
 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
 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  * @inodes_count: number of inodes
 236  * @blocks_count: number of blocks
 237  */
 238 struct nilfs_root {
 239         __u64 cno;
 240         struct rb_node rb_node;
 241
 242         atomic_t count;
 243         struct the_nilfs *nilfs;
 244         struct inode *ifile;
 245
 246         atomic_t inodes_count;
 247         atomic_t blocks_count;
 248 };
 249
 250 /* Special checkpoint number */
 251 #define NILFS_CPTREE_CURRENT_CNO        0
 252
 253 /* Minimum interval of periodical update of superblocks (in seconds) */
 254 #define NILFS_SB_FREQ           10
 255
 256 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 257 {
 258         u64 t = get_seconds();
 259         return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
 260 }
 261
 262 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
 263 {
 264         int flip_bits = nilfs->ns_sbwcount & 0x0FL;
 265         return (flip_bits != 0x08 && flip_bits != 0x0F);
 266 }
 267
 268 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 269 struct the_nilfs *alloc_nilfs(struct block_device *bdev);
 270 void destroy_nilfs(struct the_nilfs *nilfs);
 271 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
 272 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
 273 unsigned long nilfs_nrsvsegs(struct the_nilfs *nilfs, unsigned long nsegs);
 274 void nilfs_set_nsegments(struct the_nilfs *nilfs, unsigned long nsegs);
 275 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 276 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 277 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
 278 struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
 279                                              __u64 cno);
 280 void nilfs_put_root(struct nilfs_root *root);
 281 int nilfs_near_disk_full(struct the_nilfs *);
 282 void nilfs_fall_back_super_block(struct the_nilfs *);
 283 void nilfs_swap_super_block(struct the_nilfs *);
 284
 285
 286 static inline void nilfs_get_root(struct nilfs_root *root)
 287 {
 288         atomic_inc(&root->count);
 289 }
 290
 291 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
 292 {
 293         unsigned valid_fs;
 294
 295         down_read(&nilfs->ns_sem);
 296         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 297         up_read(&nilfs->ns_sem);
 298         return valid_fs;
 299 }
 300
 301 static inline void
 302 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 303                         sector_t *seg_start, sector_t *seg_end)
 304 {
 305         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 306         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 307         if (segnum == 0)
 308                 *seg_start = nilfs->ns_first_data_block;
 309 }
 310
 311 static inline sector_t
 312 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 313 {
 314         return (segnum == 0) ? nilfs->ns_first_data_block :
 315                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 316 }
 317
 318 static inline __u64
 319 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 320 {
 321         sector_t segnum = blocknr;
 322
 323         sector_div(segnum, nilfs->ns_blocks_per_segment);
 324         return segnum;
 325 }
 326
 327 static inline void
 328 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 329                         sector_t seg_end)
 330 {
 331         /* terminate the current full segment (used in case of I/O-error) */
 332         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 333 }
 334
 335 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 336 {
 337         /* move forward with a full segment */
 338         nilfs->ns_segnum = nilfs->ns_nextnum;
 339         nilfs->ns_pseg_offset = 0;
 340         nilfs->ns_seg_seq++;
 341 }
 342
 343 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 344 {
 345         __u64 cno;
 346
 347         spin_lock(&nilfs->ns_last_segment_lock);
 348         cno = nilfs->ns_last_cno;
 349         spin_unlock(&nilfs->ns_last_segment_lock);
 350         return cno;
 351 }
 352
 353 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 354 {
 355         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 356 }
 357
 358 #endif /* _THE_NILFS_H */