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 heads of on-disk super blocks 53 * @ns_sbp: pointers to super block data 54 * @ns_sbwtime: previous write time of super blocks 55 * @ns_sbsize: size of valid data in super block 56 * @ns_supers: list of nilfs super block structs 57 * @ns_seg_seq: segment sequence counter 58 * @ns_segnum: index number of the latest full segment. 59 * @ns_nextnum: index number of the full segment index to be used next 60 * @ns_pseg_offset: offset of next partial segment in the current full segment 61 * @ns_cno: next checkpoint number 62 * @ns_ctime: write time of the last segment 63 * @ns_nongc_ctime: write time of the last segment not for cleaner operation 64 * @ns_ndirtyblks: Number of dirty data blocks 65 * @ns_last_segment_lock: lock protecting fields for the latest segment 66 * @ns_last_pseg: start block number of the latest segment 67 * @ns_last_seq: sequence value of the latest segment 68 * @ns_last_cno: checkpoint number of the latest segment 69 * @ns_prot_seq: least sequence number of segments which must not be reclaimed 70 * @ns_free_segments_count: counter of free segments 71 * @ns_segctor_sem: segment constructor semaphore 72 * @ns_dat: DAT file inode 73 * @ns_cpfile: checkpoint file inode 74 * @ns_sufile: segusage file inode 75 * @ns_gc_dat: shadow inode of the DAT file inode for GC 76 * @ns_gc_inodes: dummy inodes to keep live blocks 77 * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks 78 * @ns_blocksize_bits: bit length of block size 79 * @ns_nsegments: number of segments in filesystem 80 * @ns_blocks_per_segment: number of blocks per segment 81 * @ns_r_segments_percentage: reserved segments percentage 82 * @ns_nrsvsegs: number of reserved segments 83 * @ns_first_data_block: block number of first data block 84 * @ns_inode_size: size of on-disk inode 85 * @ns_first_ino: first not-special inode number 86 * @ns_crc_seed: seed value of CRC32 calculation 87 */ 88 struct the_nilfs { 89 unsigned long ns_flags; 90 atomic_t ns_count; 91 92 struct block_device *ns_bdev; 93 struct backing_dev_info *ns_bdi; 94 struct nilfs_sb_info *ns_writer; 95 struct rw_semaphore ns_sem; 96 struct mutex ns_writer_mutex; 97 atomic_t ns_writer_refcount; 98 99 /* 100 * used for 101 * - loading the latest checkpoint exclusively. 102 * - allocating a new full segment. 103 * - protecting s_dirt in the super_block struct 104 * (see nilfs_write_super) and the following fields. 105 */ 106 struct buffer_head *ns_sbh[2]; 107 struct nilfs_super_block *ns_sbp[2]; 108 time_t ns_sbwtime[2]; 109 unsigned ns_sbsize; 110 unsigned ns_mount_state; 111 struct list_head ns_supers; 112 113 /* 114 * Following fields are dedicated to a writable FS-instance. 115 * Except for the period seeking checkpoint, code outside the segment 116 * constructor must lock a segment semaphore while accessing these 117 * fields. 118 * The writable FS-instance is sole during a lifetime of the_nilfs. 119 */ 120 u64 ns_seg_seq; 121 __u64 ns_segnum; 122 __u64 ns_nextnum; 123 unsigned long ns_pseg_offset; 124 __u64 ns_cno; 125 time_t ns_ctime; 126 time_t ns_nongc_ctime; 127 atomic_t ns_ndirtyblks; 128 129 /* 130 * The following fields hold information on the latest partial segment 131 * written to disk with a super root. These fields are protected by 132 * ns_last_segment_lock. 133 */ 134 spinlock_t ns_last_segment_lock; 135 sector_t ns_last_pseg; 136 u64 ns_last_seq; 137 __u64 ns_last_cno; 138 u64 ns_prot_seq; 139 unsigned long ns_free_segments_count; 140 141 struct rw_semaphore ns_segctor_sem; 142 143 /* 144 * Following fields are lock free except for the period before 145 * the_nilfs is initialized. 146 */ 147 struct inode *ns_dat; 148 struct inode *ns_cpfile; 149 struct inode *ns_sufile; 150 struct inode *ns_gc_dat; 151 152 /* GC inode list and hash table head */ 153 struct list_head ns_gc_inodes; 154 struct hlist_head *ns_gc_inodes_h; 155 156 /* Disk layout information (static) */ 157 unsigned int ns_blocksize_bits; 158 unsigned long ns_nsegments; 159 unsigned long ns_blocks_per_segment; 160 unsigned long ns_r_segments_percentage; 161 unsigned long ns_nrsvsegs; 162 unsigned long ns_first_data_block; 163 int ns_inode_size; 164 int ns_first_ino; 165 u32 ns_crc_seed; 166 }; 167 168 #define NILFS_GCINODE_HASH_BITS 8 169 #define NILFS_GCINODE_HASH_SIZE (1<<NILFS_GCINODE_HASH_BITS) 170 171 #define THE_NILFS_FNS(bit, name) \ 172 static inline void set_nilfs_##name(struct the_nilfs *nilfs) \ 173 { \ 174 set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 175 } \ 176 static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \ 177 { \ 178 clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 179 } \ 180 static inline int nilfs_##name(struct the_nilfs *nilfs) \ 181 { \ 182 return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \ 183 } 184 185 THE_NILFS_FNS(INIT, init) 186 THE_NILFS_FNS(LOADED, loaded) 187 THE_NILFS_FNS(DISCONTINUED, discontinued) 188 189 /* Minimum interval of periodical update of superblocks (in seconds) */ 190 #define NILFS_SB_FREQ 10 191 #define NILFS_ALTSB_FREQ 60 /* spare superblock */ 192 193 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64); 194 struct the_nilfs *alloc_nilfs(struct block_device *); 195 void put_nilfs(struct the_nilfs *); 196 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *); 197 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *); 198 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *); 199 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int); 200 int nilfs_near_disk_full(struct the_nilfs *); 201 void nilfs_fall_back_super_block(struct the_nilfs *); 202 void nilfs_swap_super_block(struct the_nilfs *); 203 204 205 static inline void get_nilfs(struct the_nilfs *nilfs) 206 { 207 /* Caller must have at least one reference of the_nilfs. */ 208 atomic_inc(&nilfs->ns_count); 209 } 210 211 static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs) 212 { 213 if (atomic_inc_and_test(&nilfs->ns_writer_refcount)) 214 mutex_lock(&nilfs->ns_writer_mutex); 215 return nilfs->ns_writer; 216 } 217 218 static inline void nilfs_put_writer(struct the_nilfs *nilfs) 219 { 220 if (atomic_add_negative(-1, &nilfs->ns_writer_refcount)) 221 mutex_unlock(&nilfs->ns_writer_mutex); 222 } 223 224 static inline void 225 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 226 { 227 mutex_lock(&nilfs->ns_writer_mutex); 228 nilfs->ns_writer = sbi; 229 mutex_unlock(&nilfs->ns_writer_mutex); 230 } 231 232 static inline void 233 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi) 234 { 235 mutex_lock(&nilfs->ns_writer_mutex); 236 if (sbi == nilfs->ns_writer) 237 nilfs->ns_writer = NULL; 238 mutex_unlock(&nilfs->ns_writer_mutex); 239 } 240 241 static inline void 242 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum, 243 sector_t *seg_start, sector_t *seg_end) 244 { 245 *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum; 246 *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1; 247 if (segnum == 0) 248 *seg_start = nilfs->ns_first_data_block; 249 } 250 251 static inline sector_t 252 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum) 253 { 254 return (segnum == 0) ? nilfs->ns_first_data_block : 255 (sector_t)nilfs->ns_blocks_per_segment * segnum; 256 } 257 258 static inline __u64 259 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr) 260 { 261 sector_t segnum = blocknr; 262 263 sector_div(segnum, nilfs->ns_blocks_per_segment); 264 return segnum; 265 } 266 267 static inline void 268 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start, 269 sector_t seg_end) 270 { 271 /* terminate the current full segment (used in case of I/O-error) */ 272 nilfs->ns_pseg_offset = seg_end - seg_start + 1; 273 } 274 275 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs) 276 { 277 /* move forward with a full segment */ 278 nilfs->ns_segnum = nilfs->ns_nextnum; 279 nilfs->ns_pseg_offset = 0; 280 nilfs->ns_seg_seq++; 281 } 282 283 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs) 284 { 285 __u64 cno; 286 287 spin_lock(&nilfs->ns_last_segment_lock); 288 cno = nilfs->ns_last_cno; 289 spin_unlock(&nilfs->ns_last_segment_lock); 290 return cno; 291 } 292 293 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n) 294 { 295 return n == nilfs->ns_segnum || n == nilfs->ns_nextnum; 296 } 297 298 #endif /* _THE_NILFS_H */ 299