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