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         THE_NILFS_GC_RUNNING,   /* gc process is running */
  41 };
  42
  43 /**
  44  * struct the_nilfs - struct to supervise multiple nilfs mount points
  45  * @ns_flags: flags
  46  * @ns_count: reference count
  47  * @ns_list: list head for nilfs_list
  48  * @ns_bdev: block device
  49  * @ns_bdi: backing dev info
  50  * @ns_writer: back pointer to writable nilfs_sb_info
  51  * @ns_sem: semaphore for shared states
  52  * @ns_super_sem: semaphore for global operations across super block instances
  53  * @ns_mount_mutex: mutex protecting mount process of nilfs
  54  * @ns_writer_sem: semaphore protecting ns_writer attach/detach
  55  * @ns_current: back pointer to current mount
  56  * @ns_sbh: buffer heads of on-disk super blocks
  57  * @ns_sbp: pointers to super block data
  58  * @ns_sbwtime: previous write time of super blocks
  59  * @ns_sbsize: size of valid data in super block
  60  * @ns_supers: list of nilfs super block structs
  61  * @ns_seg_seq: segment sequence counter
  62  * @ns_segnum: index number of the latest full segment.
  63  * @ns_nextnum: index number of the full segment index to be used next
  64  * @ns_pseg_offset: offset of next partial segment in the current full segment
  65  * @ns_cno: next checkpoint number
  66  * @ns_ctime: write time of the last segment
  67  * @ns_nongc_ctime: write time of the last segment not for cleaner operation
  68  * @ns_ndirtyblks: Number of dirty data blocks
  69  * @ns_last_segment_lock: lock protecting fields for the latest segment
  70  * @ns_last_pseg: start block number of the latest segment
  71  * @ns_last_seq: sequence value of the latest segment
  72  * @ns_last_cno: checkpoint number of the latest segment
  73  * @ns_prot_seq: least sequence number of segments which must not be reclaimed
  74  * @ns_free_segments_count: counter of free segments
  75  * @ns_segctor_sem: segment constructor semaphore
  76  * @ns_dat: DAT file inode
  77  * @ns_cpfile: checkpoint file inode
  78  * @ns_sufile: segusage file inode
  79  * @ns_gc_dat: shadow inode of the DAT file inode for GC
  80  * @ns_gc_inodes: dummy inodes to keep live blocks
  81  * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
  82  * @ns_blocksize_bits: bit length of block size
  83  * @ns_nsegments: number of segments in filesystem
  84  * @ns_blocks_per_segment: number of blocks per segment
  85  * @ns_r_segments_percentage: reserved segments percentage
  86  * @ns_nrsvsegs: number of reserved segments
  87  * @ns_first_data_block: block number of first data block
  88  * @ns_inode_size: size of on-disk inode
  89  * @ns_first_ino: first not-special inode number
  90  * @ns_crc_seed: seed value of CRC32 calculation
  91  */
  92 struct the_nilfs {
  93         unsigned long           ns_flags;
  94         atomic_t                ns_count;
  95         struct list_head        ns_list;
  96
  97         struct block_device    *ns_bdev;
  98         struct backing_dev_info *ns_bdi;
  99         struct nilfs_sb_info   *ns_writer;
 100         struct rw_semaphore     ns_sem;
 101         struct rw_semaphore     ns_super_sem;
 102         struct mutex            ns_mount_mutex;
 103         struct rw_semaphore     ns_writer_sem;
 104
 105         /*
 106          * components protected by ns_super_sem
 107          */
 108         struct nilfs_sb_info   *ns_current;
 109         struct list_head        ns_supers;
 110
 111         /*
 112          * used for
 113          * - loading the latest checkpoint exclusively.
 114          * - allocating a new full segment.
 115          * - protecting s_dirt in the super_block struct
 116          *   (see nilfs_write_super) and the following fields.
 117          */
 118         struct buffer_head     *ns_sbh[2];
 119         struct nilfs_super_block *ns_sbp[2];
 120         time_t                  ns_sbwtime[2];
 121         unsigned                ns_sbsize;
 122         unsigned                ns_mount_state;
 123
 124         /*
 125          * Following fields are dedicated to a writable FS-instance.
 126          * Except for the period seeking checkpoint, code outside the segment
 127          * constructor must lock a segment semaphore while accessing these
 128          * fields.
 129          * The writable FS-instance is sole during a lifetime of the_nilfs.
 130          */
 131         u64                     ns_seg_seq;
 132         __u64                   ns_segnum;
 133         __u64                   ns_nextnum;
 134         unsigned long           ns_pseg_offset;
 135         __u64                   ns_cno;
 136         time_t                  ns_ctime;
 137         time_t                  ns_nongc_ctime;
 138         atomic_t                ns_ndirtyblks;
 139
 140         /*
 141          * The following fields hold information on the latest partial segment
 142          * written to disk with a super root.  These fields are protected by
 143          * ns_last_segment_lock.
 144          */
 145         spinlock_t              ns_last_segment_lock;
 146         sector_t                ns_last_pseg;
 147         u64                     ns_last_seq;
 148         __u64                   ns_last_cno;
 149         u64                     ns_prot_seq;
 150         unsigned long           ns_free_segments_count;
 151
 152         struct rw_semaphore     ns_segctor_sem;
 153
 154         /*
 155          * Following fields are lock free except for the period before
 156          * the_nilfs is initialized.
 157          */
 158         struct inode           *ns_dat;
 159         struct inode           *ns_cpfile;
 160         struct inode           *ns_sufile;
 161         struct inode           *ns_gc_dat;
 162
 163         /* GC inode list and hash table head */
 164         struct list_head        ns_gc_inodes;
 165         struct hlist_head      *ns_gc_inodes_h;
 166
 167         /* Disk layout information (static) */
 168         unsigned int            ns_blocksize_bits;
 169         unsigned long           ns_nsegments;
 170         unsigned long           ns_blocks_per_segment;
 171         unsigned long           ns_r_segments_percentage;
 172         unsigned long           ns_nrsvsegs;
 173         unsigned long           ns_first_data_block;
 174         int                     ns_inode_size;
 175         int                     ns_first_ino;
 176         u32                     ns_crc_seed;
 177 };
 178
 179 #define NILFS_GCINODE_HASH_BITS         8
 180 #define NILFS_GCINODE_HASH_SIZE         (1<<NILFS_GCINODE_HASH_BITS)
 181
 182 #define THE_NILFS_FNS(bit, name)                                        \
 183 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 184 {                                                                       \
 185         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 186 }                                                                       \
 187 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 188 {                                                                       \
 189         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 190 }                                                                       \
 191 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 192 {                                                                       \
 193         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 194 }
 195
 196 THE_NILFS_FNS(INIT, init)
 197 THE_NILFS_FNS(LOADED, loaded)
 198 THE_NILFS_FNS(DISCONTINUED, discontinued)
 199 THE_NILFS_FNS(GC_RUNNING, gc_running)
 200
 201 /* Minimum interval of periodical update of superblocks (in seconds) */
 202 #define NILFS_SB_FREQ           10
 203 #define NILFS_ALTSB_FREQ        60  /* spare superblock */
 204
 205 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
 206 {
 207         u64 t = get_seconds();
 208         return t < nilfs->ns_sbwtime[0] ||
 209                  t > nilfs->ns_sbwtime[0] + NILFS_SB_FREQ;
 210 }
 211
 212 static inline int nilfs_altsb_need_update(struct the_nilfs *nilfs)
 213 {
 214         u64 t = get_seconds();
 215         struct nilfs_super_block **sbp = nilfs->ns_sbp;
 216         return sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ;
 217 }
 218
 219 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 220 struct the_nilfs *find_or_create_nilfs(struct block_device *);
 221 void put_nilfs(struct the_nilfs *);
 222 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
 223 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
 224 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 225 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
 226 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
 227 int nilfs_near_disk_full(struct the_nilfs *);
 228 void nilfs_fall_back_super_block(struct the_nilfs *);
 229 void nilfs_swap_super_block(struct the_nilfs *);
 230
 231
 232 static inline void get_nilfs(struct the_nilfs *nilfs)
 233 {
 234         /* Caller must have at least one reference of the_nilfs. */
 235         atomic_inc(&nilfs->ns_count);
 236 }
 237
 238 static inline void
 239 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 240 {
 241         down_write(&nilfs->ns_writer_sem);
 242         nilfs->ns_writer = sbi;
 243         up_write(&nilfs->ns_writer_sem);
 244 }
 245
 246 static inline void
 247 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 248 {
 249         down_write(&nilfs->ns_writer_sem);
 250         if (sbi == nilfs->ns_writer)
 251                 nilfs->ns_writer = NULL;
 252         up_write(&nilfs->ns_writer_sem);
 253 }
 254
 255 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
 256 {
 257         if (atomic_dec_and_test(&sbi->s_count))
 258                 kfree(sbi);
 259 }
 260
 261 static inline void
 262 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 263                         sector_t *seg_start, sector_t *seg_end)
 264 {
 265         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 266         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 267         if (segnum == 0)
 268                 *seg_start = nilfs->ns_first_data_block;
 269 }
 270
 271 static inline sector_t
 272 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 273 {
 274         return (segnum == 0) ? nilfs->ns_first_data_block :
 275                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 276 }
 277
 278 static inline __u64
 279 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 280 {
 281         sector_t segnum = blocknr;
 282
 283         sector_div(segnum, nilfs->ns_blocks_per_segment);
 284         return segnum;
 285 }
 286
 287 static inline void
 288 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 289                         sector_t seg_end)
 290 {
 291         /* terminate the current full segment (used in case of I/O-error) */
 292         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 293 }
 294
 295 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 296 {
 297         /* move forward with a full segment */
 298         nilfs->ns_segnum = nilfs->ns_nextnum;
 299         nilfs->ns_pseg_offset = 0;
 300         nilfs->ns_seg_seq++;
 301 }
 302
 303 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 304 {
 305         __u64 cno;
 306
 307         spin_lock(&nilfs->ns_last_segment_lock);
 308         cno = nilfs->ns_last_cno;
 309         spin_unlock(&nilfs->ns_last_segment_lock);
 310         return cno;
 311 }
 312
 313 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 314 {
 315         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 316 }
 317
 318 #endif /* _THE_NILFS_H */