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/fs.h>
  30 #include <linux/blkdev.h>
  31 #include <linux/backing-dev.h>
  32 #include <linux/slab.h>
  33 #include "sb.h"
  34
  35 /* the_nilfs struct */
  36 enum {
  37         THE_NILFS_INIT = 0,     /* Information from super_block is set */
  38         THE_NILFS_LOADED,       /* Roll-back/roll-forward has done and
  39                                    the latest checkpoint was loaded */
  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_count: reference count
  49  * @ns_list: list head for nilfs_list
  50  * @ns_bdev: block device
  51  * @ns_bdi: backing dev info
  52  * @ns_writer: back pointer to writable nilfs_sb_info
  53  * @ns_sem: semaphore for shared states
  54  * @ns_super_sem: semaphore for global operations across super block instances
  55  * @ns_mount_mutex: mutex protecting mount process of nilfs
  56  * @ns_writer_sem: semaphore protecting ns_writer attach/detach
  57  * @ns_current: back pointer to current mount
  58  * @ns_sbh: buffer heads of on-disk super blocks
  59  * @ns_sbp: pointers to super block data
  60  * @ns_sbwtime: previous write time of super block
  61  * @ns_sbwcount: write count of super block
  62  * @ns_sbsize: size of valid data in super block
  63  * @ns_supers: list of nilfs super block structs
  64  * @ns_seg_seq: segment sequence counter
  65  * @ns_segnum: index number of the latest full segment.
  66  * @ns_nextnum: index number of the full segment index to be used next
  67  * @ns_pseg_offset: offset of next partial segment in the current full segment
  68  * @ns_cno: next checkpoint number
  69  * @ns_ctime: write time of the last segment
  70  * @ns_nongc_ctime: write time of the last segment not for cleaner operation
  71  * @ns_ndirtyblks: Number of dirty data blocks
  72  * @ns_last_segment_lock: lock protecting fields for the latest segment
  73  * @ns_last_pseg: start block number of the latest segment
  74  * @ns_last_seq: sequence value of the latest segment
  75  * @ns_last_cno: checkpoint number of the latest segment
  76  * @ns_prot_seq: least sequence number of segments which must not be reclaimed
  77  * @ns_prev_seq: base sequence number used to decide if advance log cursor
  78  * @ns_segctor_sem: segment constructor semaphore
  79  * @ns_dat: DAT file inode
  80  * @ns_cpfile: checkpoint file inode
  81  * @ns_sufile: segusage file inode
  82  * @ns_gc_dat: shadow inode of the DAT file inode for GC
  83  * @ns_gc_inodes: dummy inodes to keep live blocks
  84  * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
  85  * @ns_blocksize_bits: bit length of block size
  86  * @ns_blocksize: block size
  87  * @ns_nsegments: number of segments in filesystem
  88  * @ns_blocks_per_segment: number of blocks per segment
  89  * @ns_r_segments_percentage: reserved segments percentage
  90  * @ns_nrsvsegs: number of reserved segments
  91  * @ns_first_data_block: block number of first data block
  92  * @ns_inode_size: size of on-disk inode
  93  * @ns_first_ino: first not-special inode number
  94  * @ns_crc_seed: seed value of CRC32 calculation
  95  */
  96 struct the_nilfs {
  97         unsigned long           ns_flags;
  98         atomic_t                ns_count;
  99         struct list_head        ns_list;
 100
 101         struct block_device    *ns_bdev;
 102         struct backing_dev_info *ns_bdi;
 103         struct nilfs_sb_info   *ns_writer;
 104         struct rw_semaphore     ns_sem;
 105         struct rw_semaphore     ns_super_sem;
 106         struct mutex            ns_mount_mutex;
 107         struct rw_semaphore     ns_writer_sem;
 108
 109         /*
 110          * components protected by ns_super_sem
 111          */
 112         struct nilfs_sb_info   *ns_current;
 113         struct list_head        ns_supers;
 114
 115         /*
 116          * used for
 117          * - loading the latest checkpoint exclusively.
 118          * - allocating a new full segment.
 119          * - protecting s_dirt in the super_block struct
 120          *   (see nilfs_write_super) and the following fields.
 121          */
 122         struct buffer_head     *ns_sbh[2];
 123         struct nilfs_super_block *ns_sbp[2];
 124         time_t                  ns_sbwtime;
 125         unsigned                ns_sbwcount;
 126         unsigned                ns_sbsize;
 127         unsigned                ns_mount_state;
 128
 129         /*
 130          * Following fields are dedicated to a writable FS-instance.
 131          * Except for the period seeking checkpoint, code outside the segment
 132          * constructor must lock a segment semaphore while accessing these
 133          * fields.
 134          * The writable FS-instance is sole during a lifetime of the_nilfs.
 135          */
 136         u64                     ns_seg_seq;
 137         __u64                   ns_segnum;
 138         __u64                   ns_nextnum;
 139         unsigned long           ns_pseg_offset;
 140         __u64                   ns_cno;
 141         time_t                  ns_ctime;
 142         time_t                  ns_nongc_ctime;
 143         atomic_t                ns_ndirtyblks;
 144
 145         /*
 146          * The following fields hold information on the latest partial segment
 147          * written to disk with a super root.  These fields are protected by
 148          * ns_last_segment_lock.
 149          */
 150         spinlock_t              ns_last_segment_lock;
 151         sector_t                ns_last_pseg;
 152         u64                     ns_last_seq;
 153         __u64                   ns_last_cno;
 154         u64                     ns_prot_seq;
 155         u64                     ns_prev_seq;
 156
 157         struct rw_semaphore     ns_segctor_sem;
 158
 159         /*
 160          * Following fields are lock free except for the period before
 161          * the_nilfs is initialized.
 162          */
 163         struct inode           *ns_dat;
 164         struct inode           *ns_cpfile;
 165         struct inode           *ns_sufile;
 166         struct inode           *ns_gc_dat;
 167
 168         /* GC inode list and hash table head */
 169         struct list_head        ns_gc_inodes;
 170         struct hlist_head      *ns_gc_inodes_h;
 171
 172         /* Disk layout information (static) */
 173         unsigned int            ns_blocksize_bits;
 174         unsigned int            ns_blocksize;
 175         unsigned long           ns_nsegments;
 176         unsigned long           ns_blocks_per_segment;
 177         unsigned long           ns_r_segments_percentage;
 178         unsigned long           ns_nrsvsegs;
 179         unsigned long           ns_first_data_block;
 180         int                     ns_inode_size;
 181         int                     ns_first_ino;
 182         u32                     ns_crc_seed;
 183 };
 184
 185 #define NILFS_GCINODE_HASH_BITS         8
 186 #define NILFS_GCINODE_HASH_SIZE         (1<<NILFS_GCINODE_HASH_BITS)
 187
 188 #define THE_NILFS_FNS(bit, name)                                        \
 189 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 190 {                                                                       \
 191         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 192 }                                                                       \
 193 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 194 {                                                                       \
 195         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 196 }                                                                       \
 197 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 198 {                                                                       \
 199         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 200 }
 201
 202 THE_NILFS_FNS(INIT, init)
 203 THE_NILFS_FNS(LOADED, loaded)
 204 THE_NILFS_FNS(DISCONTINUED, discontinued)
 205 THE_NILFS_FNS(GC_RUNNING, gc_running)
 206 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 207
 208 /* Minimum interval of periodical update of superblocks (in seconds) */
 209 #define NILFS_SB_FREQ           10
 210
 211 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 212 {
 213         u64 t = get_seconds();
 214         return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
 215 }
 216
 217 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
 218 {
 219         int flip_bits = nilfs->ns_sbwcount & 0x0FL;
 220         return (flip_bits != 0x08 && flip_bits != 0x0F);
 221 }
 222
 223 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 224 struct the_nilfs *find_or_create_nilfs(struct block_device *);
 225 void put_nilfs(struct the_nilfs *);
 226 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
 227 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
 228 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
 229 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 230 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
 231 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
 232 int nilfs_near_disk_full(struct the_nilfs *);
 233 void nilfs_fall_back_super_block(struct the_nilfs *);
 234 void nilfs_swap_super_block(struct the_nilfs *);
 235
 236
 237 static inline void get_nilfs(struct the_nilfs *nilfs)
 238 {
 239         /* Caller must have at least one reference of the_nilfs. */
 240         atomic_inc(&nilfs->ns_count);
 241 }
 242
 243 static inline void
 244 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 245 {
 246         down_write(&nilfs->ns_writer_sem);
 247         nilfs->ns_writer = sbi;
 248         up_write(&nilfs->ns_writer_sem);
 249 }
 250
 251 static inline void
 252 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 253 {
 254         down_write(&nilfs->ns_writer_sem);
 255         if (sbi == nilfs->ns_writer)
 256                 nilfs->ns_writer = NULL;
 257         up_write(&nilfs->ns_writer_sem);
 258 }
 259
 260 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
 261 {
 262         if (atomic_dec_and_test(&sbi->s_count))
 263                 kfree(sbi);
 264 }
 265
 266 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
 267 {
 268         unsigned valid_fs;
 269
 270         down_read(&nilfs->ns_sem);
 271         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
 272         up_read(&nilfs->ns_sem);
 273         return valid_fs;
 274 }
 275
 276 static inline void
 277 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 278                         sector_t *seg_start, sector_t *seg_end)
 279 {
 280         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 281         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 282         if (segnum == 0)
 283                 *seg_start = nilfs->ns_first_data_block;
 284 }
 285
 286 static inline sector_t
 287 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 288 {
 289         return (segnum == 0) ? nilfs->ns_first_data_block :
 290                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 291 }
 292
 293 static inline __u64
 294 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 295 {
 296         sector_t segnum = blocknr;
 297
 298         sector_div(segnum, nilfs->ns_blocks_per_segment);
 299         return segnum;
 300 }
 301
 302 static inline void
 303 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 304                         sector_t seg_end)
 305 {
 306         /* terminate the current full segment (used in case of I/O-error) */
 307         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 308 }
 309
 310 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 311 {
 312         /* move forward with a full segment */
 313         nilfs->ns_segnum = nilfs->ns_nextnum;
 314         nilfs->ns_pseg_offset = 0;
 315         nilfs->ns_seg_seq++;
 316 }
 317
 318 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 319 {
 320         __u64 cno;
 321
 322         spin_lock(&nilfs->ns_last_segment_lock);
 323         cno = nilfs->ns_last_cno;
 324         spin_unlock(&nilfs->ns_last_segment_lock);
 325         return cno;
 326 }
 327
 328 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 329 {
 330         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 331 }
 332
 333 #endif /* _THE_NILFS_H */