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