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 "sb.h"
  33
  34 /* the_nilfs struct */
  35 enum {
  36         THE_NILFS_INIT = 0,     /* Information from super_block is set */
  37         THE_NILFS_LOADED,       /* Roll-back/roll-forward has done and
  38                                    the latest checkpoint was loaded */
  39         THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
  40 };
  41
  42 /**
  43  * struct the_nilfs - struct to supervise multiple nilfs mount points
  44  * @ns_flags: flags
  45  * @ns_count: reference count
  46  * @ns_list: list head for nilfs_list
  47  * @ns_bdev: block device
  48  * @ns_bdi: backing dev info
  49  * @ns_writer: back pointer to writable nilfs_sb_info
  50  * @ns_sem: semaphore for shared states
  51  * @ns_super_sem: semaphore for global operations across super block instances
  52  * @ns_mount_mutex: mutex protecting mount process of nilfs
  53  * @ns_writer_sem: semaphore protecting ns_writer attach/detach
  54  * @ns_current: back pointer to current mount
  55  * @ns_sbh: buffer heads of on-disk super blocks
  56  * @ns_sbp: pointers to super block data
  57  * @ns_sbwtime: previous write time of super blocks
  58  * @ns_sbsize: size of valid data in super block
  59  * @ns_supers: list of nilfs super block structs
  60  * @ns_seg_seq: segment sequence counter
  61  * @ns_segnum: index number of the latest full segment.
  62  * @ns_nextnum: index number of the full segment index to be used next
  63  * @ns_pseg_offset: offset of next partial segment in the current full segment
  64  * @ns_cno: next checkpoint number
  65  * @ns_ctime: write time of the last segment
  66  * @ns_nongc_ctime: write time of the last segment not for cleaner operation
  67  * @ns_ndirtyblks: Number of dirty data blocks
  68  * @ns_last_segment_lock: lock protecting fields for the latest segment
  69  * @ns_last_pseg: start block number of the latest segment
  70  * @ns_last_seq: sequence value of the latest segment
  71  * @ns_last_cno: checkpoint number of the latest segment
  72  * @ns_prot_seq: least sequence number of segments which must not be reclaimed
  73  * @ns_free_segments_count: counter of free segments
  74  * @ns_segctor_sem: segment constructor semaphore
  75  * @ns_dat: DAT file inode
  76  * @ns_cpfile: checkpoint file inode
  77  * @ns_sufile: segusage file inode
  78  * @ns_gc_dat: shadow inode of the DAT file inode for GC
  79  * @ns_gc_inodes: dummy inodes to keep live blocks
  80  * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
  81  * @ns_blocksize_bits: bit length of 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         atomic_t                ns_count;
  94         struct list_head        ns_list;
  95
  96         struct block_device    *ns_bdev;
  97         struct backing_dev_info *ns_bdi;
  98         struct nilfs_sb_info   *ns_writer;
  99         struct rw_semaphore     ns_sem;
 100         struct rw_semaphore     ns_super_sem;
 101         struct mutex            ns_mount_mutex;
 102         struct rw_semaphore     ns_writer_sem;
 103
 104         /*
 105          * components protected by ns_super_sem
 106          */
 107         struct nilfs_sb_info   *ns_current;
 108         struct list_head        ns_supers;
 109
 110         /*
 111          * used for
 112          * - loading the latest checkpoint exclusively.
 113          * - allocating a new full segment.
 114          * - protecting s_dirt in the super_block struct
 115          *   (see nilfs_write_super) and the following fields.
 116          */
 117         struct buffer_head     *ns_sbh[2];
 118         struct nilfs_super_block *ns_sbp[2];
 119         time_t                  ns_sbwtime[2];
 120         unsigned                ns_sbsize;
 121         unsigned                ns_mount_state;
 122
 123         /*
 124          * Following fields are dedicated to a writable FS-instance.
 125          * Except for the period seeking checkpoint, code outside the segment
 126          * constructor must lock a segment semaphore while accessing these
 127          * fields.
 128          * The writable FS-instance is sole during a lifetime of the_nilfs.
 129          */
 130         u64                     ns_seg_seq;
 131         __u64                   ns_segnum;
 132         __u64                   ns_nextnum;
 133         unsigned long           ns_pseg_offset;
 134         __u64                   ns_cno;
 135         time_t                  ns_ctime;
 136         time_t                  ns_nongc_ctime;
 137         atomic_t                ns_ndirtyblks;
 138
 139         /*
 140          * The following fields hold information on the latest partial segment
 141          * written to disk with a super root.  These fields are protected by
 142          * ns_last_segment_lock.
 143          */
 144         spinlock_t              ns_last_segment_lock;
 145         sector_t                ns_last_pseg;
 146         u64                     ns_last_seq;
 147         __u64                   ns_last_cno;
 148         u64                     ns_prot_seq;
 149         unsigned long           ns_free_segments_count;
 150
 151         struct rw_semaphore     ns_segctor_sem;
 152
 153         /*
 154          * Following fields are lock free except for the period before
 155          * the_nilfs is initialized.
 156          */
 157         struct inode           *ns_dat;
 158         struct inode           *ns_cpfile;
 159         struct inode           *ns_sufile;
 160         struct inode           *ns_gc_dat;
 161
 162         /* GC inode list and hash table head */
 163         struct list_head        ns_gc_inodes;
 164         struct hlist_head      *ns_gc_inodes_h;
 165
 166         /* Disk layout information (static) */
 167         unsigned int            ns_blocksize_bits;
 168         unsigned long           ns_nsegments;
 169         unsigned long           ns_blocks_per_segment;
 170         unsigned long           ns_r_segments_percentage;
 171         unsigned long           ns_nrsvsegs;
 172         unsigned long           ns_first_data_block;
 173         int                     ns_inode_size;
 174         int                     ns_first_ino;
 175         u32                     ns_crc_seed;
 176 };
 177
 178 #define NILFS_GCINODE_HASH_BITS         8
 179 #define NILFS_GCINODE_HASH_SIZE         (1<<NILFS_GCINODE_HASH_BITS)
 180
 181 #define THE_NILFS_FNS(bit, name)                                        \
 182 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 183 {                                                                       \
 184         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 185 }                                                                       \
 186 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 187 {                                                                       \
 188         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 189 }                                                                       \
 190 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 191 {                                                                       \
 192         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 193 }
 194
 195 THE_NILFS_FNS(INIT, init)
 196 THE_NILFS_FNS(LOADED, loaded)
 197 THE_NILFS_FNS(DISCONTINUED, discontinued)
 198
 199 /* Minimum interval of periodical update of superblocks (in seconds) */
 200 #define NILFS_SB_FREQ           10
 201 #define NILFS_ALTSB_FREQ        60  /* spare superblock */
 202
 203 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 204 struct the_nilfs *find_or_create_nilfs(struct block_device *);
 205 void put_nilfs(struct the_nilfs *);
 206 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
 207 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
 208 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 209 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
 210 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
 211 int nilfs_near_disk_full(struct the_nilfs *);
 212 void nilfs_fall_back_super_block(struct the_nilfs *);
 213 void nilfs_swap_super_block(struct the_nilfs *);
 214
 215
 216 static inline void get_nilfs(struct the_nilfs *nilfs)
 217 {
 218         /* Caller must have at least one reference of the_nilfs. */
 219         atomic_inc(&nilfs->ns_count);
 220 }
 221
 222 static inline void
 223 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 224 {
 225         down_write(&nilfs->ns_writer_sem);
 226         nilfs->ns_writer = sbi;
 227         up_write(&nilfs->ns_writer_sem);
 228 }
 229
 230 static inline void
 231 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 232 {
 233         down_write(&nilfs->ns_writer_sem);
 234         if (sbi == nilfs->ns_writer)
 235                 nilfs->ns_writer = NULL;
 236         up_write(&nilfs->ns_writer_sem);
 237 }
 238
 239 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
 240 {
 241         if (atomic_dec_and_test(&sbi->s_count))
 242                 kfree(sbi);
 243 }
 244
 245 static inline void
 246 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 247                         sector_t *seg_start, sector_t *seg_end)
 248 {
 249         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 250         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 251         if (segnum == 0)
 252                 *seg_start = nilfs->ns_first_data_block;
 253 }
 254
 255 static inline sector_t
 256 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 257 {
 258         return (segnum == 0) ? nilfs->ns_first_data_block :
 259                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 260 }
 261
 262 static inline __u64
 263 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 264 {
 265         sector_t segnum = blocknr;
 266
 267         sector_div(segnum, nilfs->ns_blocks_per_segment);
 268         return segnum;
 269 }
 270
 271 static inline void
 272 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 273                         sector_t seg_end)
 274 {
 275         /* terminate the current full segment (used in case of I/O-error) */
 276         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 277 }
 278
 279 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 280 {
 281         /* move forward with a full segment */
 282         nilfs->ns_segnum = nilfs->ns_nextnum;
 283         nilfs->ns_pseg_offset = 0;
 284         nilfs->ns_seg_seq++;
 285 }
 286
 287 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 288 {
 289         __u64 cno;
 290
 291         spin_lock(&nilfs->ns_last_segment_lock);
 292         cno = nilfs->ns_last_cno;
 293         spin_unlock(&nilfs->ns_last_segment_lock);
 294         return cno;
 295 }
 296
 297 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 298 {
 299         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 300 }
 301
 302 #endif /* _THE_NILFS_H */