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