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