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 THE_NILFS_GC_RUNNING, /* gc process is running */ 41 }; 42 43 /** 44 * struct the_nilfs - struct to supervise multiple nilfs mount points 45 * @ns_flags: flags 46 * @ns_count: reference count 47 * @ns_list: list head for nilfs_list 48 * @ns_bdev: block device 49 * @ns_bdi: backing dev info 50 * @ns_writer: back pointer to writable nilfs_sb_info 51 * @ns_sem: semaphore for shared states 52 * @ns_super_sem: semaphore for global operations across super block instances 53 * @ns_mount_mutex: mutex protecting mount process of nilfs 54 * @ns_writer_sem: semaphore protecting ns_writer attach/detach 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 rw_semaphore ns_writer_sem; 104 105 /* 106 * components protected by ns_super_sem 107 */ 108 struct nilfs_sb_info *ns_current; 109 struct list_head ns_supers; 110 111 /* 112 * used for 113 * - loading the latest checkpoint exclusively. 114 * - allocating a new full segment. 115 * - protecting s_dirt in the super_block struct 116 * (see nilfs_write_super) and the following fields. 117 */ 118 struct buffer_head *ns_sbh[2]; 119 struct nilfs_super_block *ns_sbp[2]; 120 time_t ns_sbwtime[2]; 121 unsigned ns_sbsize; 122 unsigned ns_mount_state; 123 124 /* 125 * Following fields are dedicated to a writable FS-instance. 126 * Except for the period seeking checkpoint, code outside the segment 127 * constructor must lock a segment semaphore while accessing these 128 * fields. 129 * The writable FS-instance is sole during a lifetime of the_nilfs. 130 */ 131 u64 ns_seg_seq; 132 __u64 ns_segnum; 133 __u64 ns_nextnum; 134 unsigned long ns_pseg_offset; 135 __u64 ns_cno; 136 time_t ns_ctime; 137 time_t ns_nongc_ctime; 138 atomic_t ns_ndirtyblks; 139 140 /* 141 * The following fields hold information on the latest partial segment 142 * written to disk with a super root. These fields are protected by 143 * ns_last_segment_lock. 144 */ 145 spinlock_t ns_last_segment_lock; 146 sector_t ns_last_pseg; 147 u64 ns_last_seq; 148 __u64 ns_last_cno; 149 u64 ns_prot_seq; 150 unsigned long ns_free_segments_count; 151 152 struct rw_semaphore ns_segctor_sem; 153 154 /* 155 * Following fields are lock free except for the period before 156 * the_nilfs is initialized. 157 */ 158 struct inode *ns_dat; 159 struct inode *ns_cpfile; 160 struct inode *ns_sufile; 161 struct inode *ns_gc_dat; 162 163 /* GC inode list and hash table head */ 164 struct list_head ns_gc_inodes; 165 struct hlist_head *ns_gc_inodes_h; 166 167 /* Disk layout information (static) */ 168 unsigned int ns_blocksize_bits; 169 unsigned long ns_nsegments; 170 unsigned long ns_blocks_per_segment; 171 unsigned long ns_r_segments_percentage; 172 unsigned long ns_nrsvsegs; 173 unsigned long ns_first_data_block; 174 int ns_inode_size; 175 int ns_first_ino; 176 u32 ns_crc_seed; 177 }; 178 179 #define NILFS_GCINODE_HASH_BITS 8 180 #define NILFS_GCINODE_HASH_SIZE (1<<NILFS_GCINODE_HASH_BITS) 181 182 #define THE_NILFS_FNS(bit, name) \ 183 static inline void set_nilfs_##name(struct the_nilfs *nilfs) \ 184 { \ 185 set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 186 } \ 187 static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \ 188 { \ 189 clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 190 } \ 191 static inline int nilfs_##name(struct the_nilfs *nilfs) \ 192 { \ 193 return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 194 } 195 196 THE_NILFS_FNS(INIT, init) 197 THE_NILFS_FNS(LOADED, loaded) 198 THE_NILFS_FNS(DISCONTINUED, discontinued) 199 THE_NILFS_FNS(GC_RUNNING, gc_running) 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 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs) 206 { 207 u64 t = get_seconds(); 208 return t < nilfs->ns_sbwtime[0] || 209 t > nilfs->ns_sbwtime[0] + NILFS_SB_FREQ; 210 } 211 212 static inline int nilfs_altsb_need_update(struct the_nilfs *nilfs) 213 { 214 u64 t = get_seconds(); 215 struct nilfs_super_block **sbp = nilfs->ns_sbp; 216 return sbp[1] && t > nilfs->ns_sbwtime[1] + NILFS_ALTSB_FREQ; 217 } 218 219 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64); 220 struct the_nilfs *find_or_create_nilfs(struct block_device *); 221 void put_nilfs(struct the_nilfs *); 222 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *); 223 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *); 224 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *); 225 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64); 226 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int); 227 int nilfs_near_disk_full(struct the_nilfs *); 228 void nilfs_fall_back_super_block(struct the_nilfs *); 229 void nilfs_swap_super_block(struct the_nilfs *); 230 231 232 static inline void get_nilfs(struct the_nilfs *nilfs) 233 { 234 /* Caller must have at least one reference of the_nilfs. */ 235 atomic_inc(&nilfs->ns_count); 236 } 237 238 static inline void 239 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 240 { 241 down_write(&nilfs->ns_writer_sem); 242 nilfs->ns_writer = sbi; 243 up_write(&nilfs->ns_writer_sem); 244 } 245 246 static inline void 247 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 248 { 249 down_write(&nilfs->ns_writer_sem); 250 if (sbi == nilfs->ns_writer) 251 nilfs->ns_writer = NULL; 252 up_write(&nilfs->ns_writer_sem); 253 } 254 255 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi) 256 { 257 if (atomic_dec_and_test(&sbi->s_count)) 258 kfree(sbi); 259 } 260 261 static inline int nilfs_valid_fs(struct the_nilfs *nilfs) 262 { 263 unsigned valid_fs; 264 265 down_read(&nilfs->ns_sem); 266 valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS); 267 up_read(&nilfs->ns_sem); 268 return valid_fs; 269 } 270 271 static inline void 272 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum, 273 sector_t *seg_start, sector_t *seg_end) 274 { 275 *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum; 276 *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1; 277 if (segnum == 0) 278 *seg_start = nilfs->ns_first_data_block; 279 } 280 281 static inline sector_t 282 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum) 283 { 284 return (segnum == 0) ? nilfs->ns_first_data_block : 285 (sector_t)nilfs->ns_blocks_per_segment * segnum; 286 } 287 288 static inline __u64 289 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr) 290 { 291 sector_t segnum = blocknr; 292 293 sector_div(segnum, nilfs->ns_blocks_per_segment); 294 return segnum; 295 } 296 297 static inline void 298 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start, 299 sector_t seg_end) 300 { 301 /* terminate the current full segment (used in case of I/O-error) */ 302 nilfs->ns_pseg_offset = seg_end - seg_start + 1; 303 } 304 305 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs) 306 { 307 /* move forward with a full segment */ 308 nilfs->ns_segnum = nilfs->ns_nextnum; 309 nilfs->ns_pseg_offset = 0; 310 nilfs->ns_seg_seq++; 311 } 312 313 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs) 314 { 315 __u64 cno; 316 317 spin_lock(&nilfs->ns_last_segment_lock); 318 cno = nilfs->ns_last_cno; 319 spin_unlock(&nilfs->ns_last_segment_lock); 320 return cno; 321 } 322 323 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n) 324 { 325 return n == nilfs->ns_segnum || n == nilfs->ns_nextnum; 326 } 327 328 #endif /* _THE_NILFS_H */ 329