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_mutex: mutex protecting ns_writer attach/detach
  54  * @ns_writer_refcount: number of referrers on ns_writer
  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 mutex            ns_writer_mutex;
 104         atomic_t                ns_writer_refcount;
 105
 106         /*
 107          * components protected by ns_super_sem
 108          */
 109         struct nilfs_sb_info   *ns_current;
 110         struct list_head        ns_supers;
 111
 112         /*
 113          * used for
 114          * - loading the latest checkpoint exclusively.
 115          * - allocating a new full segment.
 116          * - protecting s_dirt in the super_block struct
 117          *   (see nilfs_write_super) and the following fields.
 118          */
 119         struct buffer_head     *ns_sbh[2];
 120         struct nilfs_super_block *ns_sbp[2];
 121         time_t                  ns_sbwtime[2];
 122         unsigned                ns_sbsize;
 123         unsigned                ns_mount_state;
 124
 125         /*
 126          * Following fields are dedicated to a writable FS-instance.
 127          * Except for the period seeking checkpoint, code outside the segment
 128          * constructor must lock a segment semaphore while accessing these
 129          * fields.
 130          * The writable FS-instance is sole during a lifetime of the_nilfs.
 131          */
 132         u64                     ns_seg_seq;
 133         __u64                   ns_segnum;
 134         __u64                   ns_nextnum;
 135         unsigned long           ns_pseg_offset;
 136         __u64                   ns_cno;
 137         time_t                  ns_ctime;
 138         time_t                  ns_nongc_ctime;
 139         atomic_t                ns_ndirtyblks;
 140
 141         /*
 142          * The following fields hold information on the latest partial segment
 143          * written to disk with a super root.  These fields are protected by
 144          * ns_last_segment_lock.
 145          */
 146         spinlock_t              ns_last_segment_lock;
 147         sector_t                ns_last_pseg;
 148         u64                     ns_last_seq;
 149         __u64                   ns_last_cno;
 150         u64                     ns_prot_seq;
 151         unsigned long           ns_free_segments_count;
 152
 153         struct rw_semaphore     ns_segctor_sem;
 154
 155         /*
 156          * Following fields are lock free except for the period before
 157          * the_nilfs is initialized.
 158          */
 159         struct inode           *ns_dat;
 160         struct inode           *ns_cpfile;
 161         struct inode           *ns_sufile;
 162         struct inode           *ns_gc_dat;
 163
 164         /* GC inode list and hash table head */
 165         struct list_head        ns_gc_inodes;
 166         struct hlist_head      *ns_gc_inodes_h;
 167
 168         /* Disk layout information (static) */
 169         unsigned int            ns_blocksize_bits;
 170         unsigned long           ns_nsegments;
 171         unsigned long           ns_blocks_per_segment;
 172         unsigned long           ns_r_segments_percentage;
 173         unsigned long           ns_nrsvsegs;
 174         unsigned long           ns_first_data_block;
 175         int                     ns_inode_size;
 176         int                     ns_first_ino;
 177         u32                     ns_crc_seed;
 178 };
 179
 180 #define NILFS_GCINODE_HASH_BITS         8
 181 #define NILFS_GCINODE_HASH_SIZE         (1<<NILFS_GCINODE_HASH_BITS)
 182
 183 #define THE_NILFS_FNS(bit, name)                                        \
 184 static inline void set_nilfs_##name(struct the_nilfs *nilfs)            \
 185 {                                                                       \
 186         set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                   \
 187 }                                                                       \
 188 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)          \
 189 {                                                                       \
 190         clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);                 \
 191 }                                                                       \
 192 static inline int nilfs_##name(struct the_nilfs *nilfs)                 \
 193 {                                                                       \
 194         return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);           \
 195 }
 196
 197 THE_NILFS_FNS(INIT, init)
 198 THE_NILFS_FNS(LOADED, loaded)
 199 THE_NILFS_FNS(DISCONTINUED, discontinued)
 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 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
 206 struct the_nilfs *find_or_create_nilfs(struct block_device *);
 207 void put_nilfs(struct the_nilfs *);
 208 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
 209 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
 210 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
 211 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
 212 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
 213 int nilfs_near_disk_full(struct the_nilfs *);
 214 void nilfs_fall_back_super_block(struct the_nilfs *);
 215 void nilfs_swap_super_block(struct the_nilfs *);
 216
 217
 218 static inline void get_nilfs(struct the_nilfs *nilfs)
 219 {
 220         /* Caller must have at least one reference of the_nilfs. */
 221         atomic_inc(&nilfs->ns_count);
 222 }
 223
 224 static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
 225 {
 226         if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
 227                 mutex_lock(&nilfs->ns_writer_mutex);
 228         return nilfs->ns_writer;
 229 }
 230
 231 static inline void nilfs_put_writer(struct the_nilfs *nilfs)
 232 {
 233         if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
 234                 mutex_unlock(&nilfs->ns_writer_mutex);
 235 }
 236
 237 static inline void
 238 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 239 {
 240         mutex_lock(&nilfs->ns_writer_mutex);
 241         nilfs->ns_writer = sbi;
 242         mutex_unlock(&nilfs->ns_writer_mutex);
 243 }
 244
 245 static inline void
 246 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
 247 {
 248         mutex_lock(&nilfs->ns_writer_mutex);
 249         if (sbi == nilfs->ns_writer)
 250                 nilfs->ns_writer = NULL;
 251         mutex_unlock(&nilfs->ns_writer_mutex);
 252 }
 253
 254 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
 255 {
 256         if (!atomic_dec_and_test(&sbi->s_count))
 257                 kfree(sbi);
 258 }
 259
 260 static inline void
 261 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
 262                         sector_t *seg_start, sector_t *seg_end)
 263 {
 264         *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
 265         *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
 266         if (segnum == 0)
 267                 *seg_start = nilfs->ns_first_data_block;
 268 }
 269
 270 static inline sector_t
 271 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
 272 {
 273         return (segnum == 0) ? nilfs->ns_first_data_block :
 274                 (sector_t)nilfs->ns_blocks_per_segment * segnum;
 275 }
 276
 277 static inline __u64
 278 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
 279 {
 280         sector_t segnum = blocknr;
 281
 282         sector_div(segnum, nilfs->ns_blocks_per_segment);
 283         return segnum;
 284 }
 285
 286 static inline void
 287 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
 288                         sector_t seg_end)
 289 {
 290         /* terminate the current full segment (used in case of I/O-error) */
 291         nilfs->ns_pseg_offset = seg_end - seg_start + 1;
 292 }
 293
 294 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
 295 {
 296         /* move forward with a full segment */
 297         nilfs->ns_segnum = nilfs->ns_nextnum;
 298         nilfs->ns_pseg_offset = 0;
 299         nilfs->ns_seg_seq++;
 300 }
 301
 302 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
 303 {
 304         __u64 cno;
 305
 306         spin_lock(&nilfs->ns_last_segment_lock);
 307         cno = nilfs->ns_last_cno;
 308         spin_unlock(&nilfs->ns_last_segment_lock);
 309         return cno;
 310 }
 311
 312 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
 313 {
 314         return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
 315 }
 316
 317 #endif /* _THE_NILFS_H */