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