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