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 <linux/slab.h> 33 #include "sb.h" 34 35 /* the_nilfs struct */ 36 enum { 37 THE_NILFS_INIT = 0, /* Information from super_block is set */ 38 THE_NILFS_LOADED, /* Roll-back/roll-forward has done and 39 the latest checkpoint was loaded */ 40 THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */ 41 THE_NILFS_GC_RUNNING, /* gc process is running */ 42 THE_NILFS_SB_DIRTY, /* super block is dirty */ 43 }; 44 45 /** 46 * struct the_nilfs - struct to supervise multiple nilfs mount points 47 * @ns_flags: flags 48 * @ns_count: reference count 49 * @ns_list: list head for nilfs_list 50 * @ns_bdev: block device 51 * @ns_bdi: backing dev info 52 * @ns_writer: back pointer to writable nilfs_sb_info 53 * @ns_sem: semaphore for shared states 54 * @ns_super_sem: semaphore for global operations across super block instances 55 * @ns_mount_mutex: mutex protecting mount process of nilfs 56 * @ns_writer_sem: semaphore protecting ns_writer attach/detach 57 * @ns_current: back pointer to current mount 58 * @ns_sbh: buffer heads of on-disk super blocks 59 * @ns_sbp: pointers to super block data 60 * @ns_sbwtime: previous write time of super block 61 * @ns_sbwcount: write count of super block 62 * @ns_sbsize: size of valid data in super block 63 * @ns_supers: list of nilfs super block structs 64 * @ns_seg_seq: segment sequence counter 65 * @ns_segnum: index number of the latest full segment. 66 * @ns_nextnum: index number of the full segment index to be used next 67 * @ns_pseg_offset: offset of next partial segment in the current full segment 68 * @ns_cno: next checkpoint number 69 * @ns_ctime: write time of the last segment 70 * @ns_nongc_ctime: write time of the last segment not for cleaner operation 71 * @ns_ndirtyblks: Number of dirty data blocks 72 * @ns_last_segment_lock: lock protecting fields for the latest segment 73 * @ns_last_pseg: start block number of the latest segment 74 * @ns_last_seq: sequence value of the latest segment 75 * @ns_last_cno: checkpoint number of the latest segment 76 * @ns_prot_seq: least sequence number of segments which must not be reclaimed 77 * @ns_prev_seq: base sequence number used to decide if advance log cursor 78 * @ns_segctor_sem: segment constructor semaphore 79 * @ns_dat: DAT file inode 80 * @ns_cpfile: checkpoint file inode 81 * @ns_sufile: segusage file inode 82 * @ns_gc_dat: shadow inode of the DAT file inode for GC 83 * @ns_gc_inodes: dummy inodes to keep live blocks 84 * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks 85 * @ns_blocksize_bits: bit length of block size 86 * @ns_blocksize: block size 87 * @ns_nsegments: number of segments in filesystem 88 * @ns_blocks_per_segment: number of blocks per segment 89 * @ns_r_segments_percentage: reserved segments percentage 90 * @ns_nrsvsegs: number of reserved segments 91 * @ns_first_data_block: block number of first data block 92 * @ns_inode_size: size of on-disk inode 93 * @ns_first_ino: first not-special inode number 94 * @ns_crc_seed: seed value of CRC32 calculation 95 */ 96 struct the_nilfs { 97 unsigned long ns_flags; 98 atomic_t ns_count; 99 struct list_head ns_list; 100 101 struct block_device *ns_bdev; 102 struct backing_dev_info *ns_bdi; 103 struct nilfs_sb_info *ns_writer; 104 struct rw_semaphore ns_sem; 105 struct rw_semaphore ns_super_sem; 106 struct mutex ns_mount_mutex; 107 struct rw_semaphore ns_writer_sem; 108 109 /* 110 * components protected by ns_super_sem 111 */ 112 struct nilfs_sb_info *ns_current; 113 struct list_head ns_supers; 114 115 /* 116 * used for 117 * - loading the latest checkpoint exclusively. 118 * - allocating a new full segment. 119 * - protecting s_dirt in the super_block struct 120 * (see nilfs_write_super) and the following fields. 121 */ 122 struct buffer_head *ns_sbh[2]; 123 struct nilfs_super_block *ns_sbp[2]; 124 time_t ns_sbwtime; 125 unsigned ns_sbwcount; 126 unsigned ns_sbsize; 127 unsigned ns_mount_state; 128 129 /* 130 * Following fields are dedicated to a writable FS-instance. 131 * Except for the period seeking checkpoint, code outside the segment 132 * constructor must lock a segment semaphore while accessing these 133 * fields. 134 * The writable FS-instance is sole during a lifetime of the_nilfs. 135 */ 136 u64 ns_seg_seq; 137 __u64 ns_segnum; 138 __u64 ns_nextnum; 139 unsigned long ns_pseg_offset; 140 __u64 ns_cno; 141 time_t ns_ctime; 142 time_t ns_nongc_ctime; 143 atomic_t ns_ndirtyblks; 144 145 /* 146 * The following fields hold information on the latest partial segment 147 * written to disk with a super root. These fields are protected by 148 * ns_last_segment_lock. 149 */ 150 spinlock_t ns_last_segment_lock; 151 sector_t ns_last_pseg; 152 u64 ns_last_seq; 153 __u64 ns_last_cno; 154 u64 ns_prot_seq; 155 u64 ns_prev_seq; 156 157 struct rw_semaphore ns_segctor_sem; 158 159 /* 160 * Following fields are lock free except for the period before 161 * the_nilfs is initialized. 162 */ 163 struct inode *ns_dat; 164 struct inode *ns_cpfile; 165 struct inode *ns_sufile; 166 struct inode *ns_gc_dat; 167 168 /* GC inode list and hash table head */ 169 struct list_head ns_gc_inodes; 170 struct hlist_head *ns_gc_inodes_h; 171 172 /* Disk layout information (static) */ 173 unsigned int ns_blocksize_bits; 174 unsigned int ns_blocksize; 175 unsigned long ns_nsegments; 176 unsigned long ns_blocks_per_segment; 177 unsigned long ns_r_segments_percentage; 178 unsigned long ns_nrsvsegs; 179 unsigned long ns_first_data_block; 180 int ns_inode_size; 181 int ns_first_ino; 182 u32 ns_crc_seed; 183 }; 184 185 #define NILFS_GCINODE_HASH_BITS 8 186 #define NILFS_GCINODE_HASH_SIZE (1<<NILFS_GCINODE_HASH_BITS) 187 188 #define THE_NILFS_FNS(bit, name) \ 189 static inline void set_nilfs_##name(struct the_nilfs *nilfs) \ 190 { \ 191 set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 192 } \ 193 static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \ 194 { \ 195 clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 196 } \ 197 static inline int nilfs_##name(struct the_nilfs *nilfs) \ 198 { \ 199 return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 200 } 201 202 THE_NILFS_FNS(INIT, init) 203 THE_NILFS_FNS(LOADED, loaded) 204 THE_NILFS_FNS(DISCONTINUED, discontinued) 205 THE_NILFS_FNS(GC_RUNNING, gc_running) 206 THE_NILFS_FNS(SB_DIRTY, sb_dirty) 207 208 /* Minimum interval of periodical update of superblocks (in seconds) */ 209 #define NILFS_SB_FREQ 10 210 211 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs) 212 { 213 u64 t = get_seconds(); 214 return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ; 215 } 216 217 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs) 218 { 219 int flip_bits = nilfs->ns_sbwcount & 0x0FL; 220 return (flip_bits != 0x08 && flip_bits != 0x0F); 221 } 222 223 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64); 224 struct the_nilfs *find_or_create_nilfs(struct block_device *); 225 void put_nilfs(struct the_nilfs *); 226 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *); 227 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *); 228 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t); 229 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *); 230 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64); 231 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int); 232 int nilfs_near_disk_full(struct the_nilfs *); 233 void nilfs_fall_back_super_block(struct the_nilfs *); 234 void nilfs_swap_super_block(struct the_nilfs *); 235 236 237 static inline void get_nilfs(struct the_nilfs *nilfs) 238 { 239 /* Caller must have at least one reference of the_nilfs. */ 240 atomic_inc(&nilfs->ns_count); 241 } 242 243 static inline void 244 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 245 { 246 down_write(&nilfs->ns_writer_sem); 247 nilfs->ns_writer = sbi; 248 up_write(&nilfs->ns_writer_sem); 249 } 250 251 static inline void 252 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 253 { 254 down_write(&nilfs->ns_writer_sem); 255 if (sbi == nilfs->ns_writer) 256 nilfs->ns_writer = NULL; 257 up_write(&nilfs->ns_writer_sem); 258 } 259 260 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi) 261 { 262 if (atomic_dec_and_test(&sbi->s_count)) 263 kfree(sbi); 264 } 265 266 static inline int nilfs_valid_fs(struct the_nilfs *nilfs) 267 { 268 unsigned valid_fs; 269 270 down_read(&nilfs->ns_sem); 271 valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS); 272 up_read(&nilfs->ns_sem); 273 return valid_fs; 274 } 275 276 static inline void 277 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum, 278 sector_t *seg_start, sector_t *seg_end) 279 { 280 *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum; 281 *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1; 282 if (segnum == 0) 283 *seg_start = nilfs->ns_first_data_block; 284 } 285 286 static inline sector_t 287 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum) 288 { 289 return (segnum == 0) ? nilfs->ns_first_data_block : 290 (sector_t)nilfs->ns_blocks_per_segment * segnum; 291 } 292 293 static inline __u64 294 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr) 295 { 296 sector_t segnum = blocknr; 297 298 sector_div(segnum, nilfs->ns_blocks_per_segment); 299 return segnum; 300 } 301 302 static inline void 303 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start, 304 sector_t seg_end) 305 { 306 /* terminate the current full segment (used in case of I/O-error) */ 307 nilfs->ns_pseg_offset = seg_end - seg_start + 1; 308 } 309 310 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs) 311 { 312 /* move forward with a full segment */ 313 nilfs->ns_segnum = nilfs->ns_nextnum; 314 nilfs->ns_pseg_offset = 0; 315 nilfs->ns_seg_seq++; 316 } 317 318 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs) 319 { 320 __u64 cno; 321 322 spin_lock(&nilfs->ns_last_segment_lock); 323 cno = nilfs->ns_last_cno; 324 spin_unlock(&nilfs->ns_last_segment_lock); 325 return cno; 326 } 327 328 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n) 329 { 330 return n == nilfs->ns_segnum || n == nilfs->ns_nextnum; 331 } 332 333 #endif /* _THE_NILFS_H */ 334