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 #include "sb.h"
  35
  36 /* the_nilfs struct */
  37 enum {
  38         THE_NILFS_INIT = 0,     /* Information from super_block is set */
  39         THE_NILFS_LOADED,       /* Roll-back/roll-forward has done and
  40                                    the latest checkpoint was loaded */
  41         THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
  42         THE_NILFS_GC_RUNNING,   /* gc process is running */
  43         THE_NILFS_SB_DIRTY,     /* super block is dirty */
  44 };
  45
  46 /**
  47  * struct the_nilfs - struct to supervise multiple nilfs mount points
  48  * @ns_flags: flags
  49  * @ns_bdev: block device
  50  * @ns_bdi: backing dev info
  51  * @ns_writer: back pointer to writable nilfs_sb_info
  52  * @ns_sem: semaphore for shared states
  53  * @ns_writer_sem: semaphore protecting ns_writer attach/detach
  54  * @ns_sbh: buffer heads of on-disk super blocks
  55  * @ns_sbp: pointers to super block data
  56  * @ns_sbwtime: previous write time of super block
  57  * @ns_sbwcount: write count of super block
  58  * @ns_sbsize: size of valid data in super block
  59  * @ns_seg_seq: segment sequence counter
  60  * @ns_segnum: index number of the latest full segment.
  61  * @ns_nextnum: index number of the full segment index to be used next
  62  * @ns_pseg_offset: offset of next partial segment in the current full segment
  63  * @ns_cno: next checkpoint number
  64  * @ns_ctime: write time of the last segment
  65  * @ns_nongc_ctime: write time of the last segment not for cleaner operation
  66  * @ns_ndirtyblks: Number of dirty data blocks
  67  * @ns_last_segment_lock: lock protecting fields for the latest segment
  68  * @ns_last_pseg: start block number of the latest segment
  69  * @ns_last_seq: sequence value of the latest segment
  70  * @ns_last_cno: checkpoint number of the latest segment
  71  * @ns_prot_seq: least sequence number of segments which must not be reclaimed
  72  * @ns_prev_seq: base sequence number used to decide if advance log cursor
  73  * @ns_segctor_sem: segment constructor semaphore
  74  * @ns_dat: DAT file inode
  75  * @ns_cpfile: checkpoint file inode
  76  * @ns_sufile: segusage file inode
  77  * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
  78  * @ns_cptree_lock: lock protecting @ns_cptree
  79  * @ns_gc_inodes: dummy inodes to keep live blocks
  80  * @ns_blocksize_bits: bit length of block size
  81  * @ns_blocksize: block size
  82  * @ns_nsegments: number of segments in filesystem
  83  * @ns_blocks_per_segment: number of blocks per segment
  84  * @ns_r_segments_percentage: reserved segments percentage
  85  * @ns_nrsvsegs: number of reserved segments
  86  * @ns_first_data_block: block number of first data block
  87  * @ns_inode_size: size of on-disk inode
  88  * @ns_first_ino: first not-special inode number
  89  * @ns_crc_seed: seed value of CRC32 calculation
  90  */
  91 struct the_nilfs {
  92         unsigned long           ns_flags;
  93
  94         struct block_device    *ns_bdev;
  95         struct backing_dev_info *ns_bdi;
  96         struct nilfs_sb_info   *ns_writer;
  97         struct rw_semaphore     ns_sem;
  98         struct rw_semaphore     ns_writer_sem;
  99
 100         /*
 101          * used for
 102          * - loading the latest checkpoint exclusively.
 103          * - allocating a new full segment.
 104          * - protecting s_dirt in the super_block struct
 105          *   (see nilfs_write_super) and the following fields.
 106          */
 107         struct buffer_head     *ns_sbh[2];
 108         struct nilfs_super_block *ns_sbp[2];
 109         time_t                  ns_sbwtime;
 110         unsigned                ns_sbwcount;
 111         unsigned                ns_sbsize;
 112         unsigned                ns_mount_state;
 113
 114         /*
 115          * Following fields are dedicated to a writable FS-instance.
 116          * Except for the period seeking checkpoint, code outside the segment
 117          * constructor must lock a segment semaphore while accessing these
 118          * fields.
 119          * The writable FS-instance is sole during a lifetime of the_nilfs.
 120          */
 121         u64                     ns_seg_seq;
 122         __u64                   ns_segnum;
 123         __u64                   ns_nextnum;
 124         unsigned long           ns_pseg_offset;
 125         __u64                   ns_cno;
 126         time_t                  ns_ctime;
 127         time_t                  ns_nongc_ctime;
 128         atomic_t                ns_ndirtyblks;
 129
 130         /*
 131          * The following fields hold information on the latest partial segment
 132          * written to disk with a super root.  These fields are protected by
 133          * ns_last_segment_lock.
 134          */
 135         spinlock_t              ns_last_segment_lock;
 136         sector_t                ns_last_pseg;
 137         u64                     ns_last_seq;
 138         __u64                   ns_last_cno;
 139         u64                     ns_prot_seq;
 140         u64                     ns_prev_seq;
 141
 142         struct rw_semaphore     ns_segctor_sem;
 143
 144         /*
 145          * Following fields are lock free except for the period before
 146          * the_nilfs is initialized.
 147          */
 148         struct inode           *ns_dat;
 149         struct inode           *ns_cpfile;
 150         struct inode           *ns_sufile;
 151
 152         /* Checkpoint tree */
 153         struct rb_root          ns_cptree;
 154         spinlock_t              ns_cptree_lock;
 155
 156         /* GC inode list */
 157         struct list_head        ns_gc_inodes;
 158
 159         /* Disk layout information (static) */
 160         unsigned int            ns_blocksize_bits;
 161         unsigned int            ns_blocksize;
 162         unsigned long           ns_nsegments;
 163         unsigned long           ns_blocks_per_segment;
 164         unsigned long           ns_r_segments_percentage;
 165         unsigned long           ns_nrsvsegs;
 166         unsigned long           ns_first_data_block;
 167         int                     ns_inode_size;
 168         int                     ns_first_ino;
 169         u32                     ns_crc_seed;
 170 };
 171
 172 #define THE_NILFS_FNS(bit, name)                                        \
 173 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 174 {                                                                       \
 175         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 176 }                                                                       \
 177 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 178 {                                                                       \
 179         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 180 }                                                                       \
 181 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 182 {                                                                       \
 183         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 184 }
 185
 186 THE_NILFS_FNS(INIT, init)
 187 THE_NILFS_FNS(LOADED, loaded)
 188 THE_NILFS_FNS(DISCONTINUED, discontinued)
 189 THE_NILFS_FNS(GC_RUNNING, gc_running)
 190 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 191
 192 /**
 193  * struct nilfs_root - nilfs root object
 194  * @cno: checkpoint number
 195  * @rb_node: red-black tree node
 196  * @count: refcount of this structure
 197  * @nilfs: nilfs object
 198  * @ifile: inode file
 199  * @root: root inode
 200  * @inodes_count: number of inodes
 201  * @blocks_count: number of blocks (Reserved)
 202  */
 203 struct nilfs_root {
 204         __u64 cno;
 205         struct rb_node rb_node;
 206
 207         atomic_t count;
 208         struct the_nilfs *nilfs;
 209         struct inode *ifile;
 210
 211         atomic_t inodes_count;
 212         atomic_t blocks_count;
 213 };
 214
 215 /* Special checkpoint number */
 216 #define NILFS_CPTREE_CURRENT_CNO        0
 217
 218 /* Minimum interval of periodical update of superblocks (in seconds) */
 219 #define NILFS_SB_FREQ           10
 220
 221 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 222 {
 223         u64 t = get_seconds();
 224         return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
 225 }
 226
 227 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
 228 {
 229         int flip_bits = nilfs->ns_sbwcount & 0x0FL;
 230         return (flip_bits != 0x08 && flip_bits != 0x0F);
 231 }
 232
 233 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 234 struct the_nilfs *alloc_nilfs(struct block_device *bdev);
 235 void destroy_nilfs(struct the_nilfs *nilfs);
 236 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
 237 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
 238 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 239 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 240 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
 241 struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
 242                                              __u64 cno);
 243 void nilfs_put_root(struct nilfs_root *root);
 244 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
 245 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
 246 int nilfs_near_disk_full(struct the_nilfs *);
 247 void nilfs_fall_back_super_block(struct the_nilfs *);
 248 void nilfs_swap_super_block(struct the_nilfs *);
 249
 250
 251 static inline void nilfs_get_root(struct nilfs_root *root)
 252 {
 253         atomic_inc(&root->count);
 254 }
 255
 256 static inline void
 257 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 258 {
 259         down_write(&nilfs->ns_writer_sem);
 260         nilfs->ns_writer = sbi;
 261         up_write(&nilfs->ns_writer_sem);
 262 }
 263
 264 static inline void
 265 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 266 {
 267         down_write(&nilfs->ns_writer_sem);
 268         if (sbi == nilfs->ns_writer)
 269                 nilfs->ns_writer = NULL;
 270         up_write(&nilfs->ns_writer_sem);
 271 }
 272
 273 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
 274 {
 275         unsigned valid_fs;
 276
 277         down_read(&nilfs->ns_sem);
 278         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 279         up_read(&nilfs->ns_sem);
 280         return valid_fs;
 281 }
 282
 283 static inline void
 284 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 285                         sector_t *seg_start, sector_t *seg_end)
 286 {
 287         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 288         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 289         if (segnum == 0)
 290                 *seg_start = nilfs->ns_first_data_block;
 291 }
 292
 293 static inline sector_t
 294 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 295 {
 296         return (segnum == 0) ? nilfs->ns_first_data_block :
 297                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 298 }
 299
 300 static inline __u64
 301 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 302 {
 303         sector_t segnum = blocknr;
 304
 305         sector_div(segnum, nilfs->ns_blocks_per_segment);
 306         return segnum;
 307 }
 308
 309 static inline void
 310 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 311                         sector_t seg_end)
 312 {
 313         /* terminate the current full segment (used in case of I/O-error) */
 314         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 315 }
 316
 317 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 318 {
 319         /* move forward with a full segment */
 320         nilfs->ns_segnum = nilfs->ns_nextnum;
 321         nilfs->ns_pseg_offset = 0;
 322         nilfs->ns_seg_seq++;
 323 }
 324
 325 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 326 {
 327         __u64 cno;
 328
 329         spin_lock(&nilfs->ns_last_segment_lock);
 330         cno = nilfs->ns_last_cno;
 331         spin_unlock(&nilfs->ns_last_segment_lock);
 332         return cno;
 333 }
 334
 335 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 336 {
 337         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 338 }
 339
 340 #endif /* _THE_NILFS_H */