2 * the_nilfs.h - the_nilfs shared structure.
4 * Copyright (C) 2005-2008 Nippon Telegraph and Telephone Corporation.
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.
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.
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
20 * Written by Ryusuke Konishi <ryusuke@osrg.net>
27 #include <linux/types.h>
28 #include <linux/buffer_head.h>
30 #include <linux/blkdev.h>
31 #include <linux/backing-dev.h>
34 /* the_nilfs struct */
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 */
43 * struct the_nilfs - struct to supervise multiple nilfs mount points
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_writer_mutex: mutex protecting ns_writer attach/detach
53 * @ns_writer_refcount: number of referrers on ns_writer
54 * @ns_current: back pointer to current mount
55 * @ns_sbh: buffer heads of on-disk super blocks
56 * @ns_sbp: pointers to super block data
57 * @ns_sbwtime: previous write time of super blocks
58 * @ns_sbsize: size of valid data in super block
59 * @ns_supers: list of nilfs super block structs
60 * @ns_seg_seq: segment sequence counter
61 * @ns_segnum: index number of the latest full segment.
62 * @ns_nextnum: index number of the full segment index to be used next
63 * @ns_pseg_offset: offset of next partial segment in the current full segment
64 * @ns_cno: next checkpoint number
65 * @ns_ctime: write time of the last segment
66 * @ns_nongc_ctime: write time of the last segment not for cleaner operation
67 * @ns_ndirtyblks: Number of dirty data blocks
68 * @ns_last_segment_lock: lock protecting fields for the latest segment
69 * @ns_last_pseg: start block number of the latest segment
70 * @ns_last_seq: sequence value of the latest segment
71 * @ns_last_cno: checkpoint number of the latest segment
72 * @ns_prot_seq: least sequence number of segments which must not be reclaimed
73 * @ns_free_segments_count: counter of free segments
74 * @ns_segctor_sem: segment constructor semaphore
75 * @ns_dat: DAT file inode
76 * @ns_cpfile: checkpoint file inode
77 * @ns_sufile: segusage file inode
78 * @ns_gc_dat: shadow inode of the DAT file inode for GC
79 * @ns_gc_inodes: dummy inodes to keep live blocks
80 * @ns_gc_inodes_h: hash list to keep dummy inode holding live blocks
81 * @ns_blocksize_bits: bit length of block size
82 * @ns_nsegments: number of segments in filesystem
83 * @ns_blocks_per_segment: number of blocks per segment
84 * @ns_r_segments_percentage: reserved segments percentage
85 * @ns_nrsvsegs: number of reserved segments
86 * @ns_first_data_block: block number of first data block
87 * @ns_inode_size: size of on-disk inode
88 * @ns_first_ino: first not-special inode number
89 * @ns_crc_seed: seed value of CRC32 calculation
92 unsigned long ns_flags;
94 struct list_head ns_list;
96 struct block_device *ns_bdev;
97 struct backing_dev_info *ns_bdi;
98 struct nilfs_sb_info *ns_writer;
99 struct rw_semaphore ns_sem;
100 struct rw_semaphore ns_super_sem;
101 struct mutex ns_writer_mutex;
102 atomic_t ns_writer_refcount;
105 * components protected by ns_super_sem
107 struct nilfs_sb_info *ns_current;
108 struct list_head ns_supers;
112 * - loading the latest checkpoint exclusively.
113 * - allocating a new full segment.
114 * - protecting s_dirt in the super_block struct
115 * (see nilfs_write_super) and the following fields.
117 struct buffer_head *ns_sbh[2];
118 struct nilfs_super_block *ns_sbp[2];
119 time_t ns_sbwtime[2];
121 unsigned ns_mount_state;
124 * Following fields are dedicated to a writable FS-instance.
125 * Except for the period seeking checkpoint, code outside the segment
126 * constructor must lock a segment semaphore while accessing these
128 * The writable FS-instance is sole during a lifetime of the_nilfs.
133 unsigned long ns_pseg_offset;
136 time_t ns_nongc_ctime;
137 atomic_t ns_ndirtyblks;
140 * The following fields hold information on the latest partial segment
141 * written to disk with a super root. These fields are protected by
142 * ns_last_segment_lock.
144 spinlock_t ns_last_segment_lock;
145 sector_t ns_last_pseg;
149 unsigned long ns_free_segments_count;
151 struct rw_semaphore ns_segctor_sem;
154 * Following fields are lock free except for the period before
155 * the_nilfs is initialized.
157 struct inode *ns_dat;
158 struct inode *ns_cpfile;
159 struct inode *ns_sufile;
160 struct inode *ns_gc_dat;
162 /* GC inode list and hash table head */
163 struct list_head ns_gc_inodes;
164 struct hlist_head *ns_gc_inodes_h;
166 /* Disk layout information (static) */
167 unsigned int ns_blocksize_bits;
168 unsigned long ns_nsegments;
169 unsigned long ns_blocks_per_segment;
170 unsigned long ns_r_segments_percentage;
171 unsigned long ns_nrsvsegs;
172 unsigned long ns_first_data_block;
178 #define NILFS_GCINODE_HASH_BITS 8
179 #define NILFS_GCINODE_HASH_SIZE (1<<NILFS_GCINODE_HASH_BITS)
181 #define THE_NILFS_FNS(bit, name) \
182 static inline void set_nilfs_##name(struct the_nilfs *nilfs) \
184 set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
186 static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \
188 clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
190 static inline int nilfs_##name(struct the_nilfs *nilfs) \
192 return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
195 THE_NILFS_FNS(INIT, init)
196 THE_NILFS_FNS(LOADED, loaded)
197 THE_NILFS_FNS(DISCONTINUED, discontinued)
199 /* Minimum interval of periodical update of superblocks (in seconds) */
200 #define NILFS_SB_FREQ 10
201 #define NILFS_ALTSB_FREQ 60 /* spare superblock */
203 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
204 struct the_nilfs *find_or_create_nilfs(struct block_device *);
205 void put_nilfs(struct the_nilfs *);
206 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
207 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
208 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
209 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
210 int nilfs_checkpoint_is_mounted(struct the_nilfs *, __u64, int);
211 int nilfs_near_disk_full(struct the_nilfs *);
212 void nilfs_fall_back_super_block(struct the_nilfs *);
213 void nilfs_swap_super_block(struct the_nilfs *);
216 static inline void get_nilfs(struct the_nilfs *nilfs)
218 /* Caller must have at least one reference of the_nilfs. */
219 atomic_inc(&nilfs->ns_count);
222 static inline struct nilfs_sb_info *nilfs_get_writer(struct the_nilfs *nilfs)
224 if (atomic_inc_and_test(&nilfs->ns_writer_refcount))
225 mutex_lock(&nilfs->ns_writer_mutex);
226 return nilfs->ns_writer;
229 static inline void nilfs_put_writer(struct the_nilfs *nilfs)
231 if (atomic_add_negative(-1, &nilfs->ns_writer_refcount))
232 mutex_unlock(&nilfs->ns_writer_mutex);
236 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
238 mutex_lock(&nilfs->ns_writer_mutex);
239 nilfs->ns_writer = sbi;
240 mutex_unlock(&nilfs->ns_writer_mutex);
244 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
246 mutex_lock(&nilfs->ns_writer_mutex);
247 if (sbi == nilfs->ns_writer)
248 nilfs->ns_writer = NULL;
249 mutex_unlock(&nilfs->ns_writer_mutex);
252 static inline void nilfs_put_sbinfo(struct nilfs_sb_info *sbi)
254 if (!atomic_dec_and_test(&sbi->s_count))
259 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
260 sector_t *seg_start, sector_t *seg_end)
262 *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
263 *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
265 *seg_start = nilfs->ns_first_data_block;
268 static inline sector_t
269 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
271 return (segnum == 0) ? nilfs->ns_first_data_block :
272 (sector_t)nilfs->ns_blocks_per_segment * segnum;
276 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
278 sector_t segnum = blocknr;
280 sector_div(segnum, nilfs->ns_blocks_per_segment);
285 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
288 /* terminate the current full segment (used in case of I/O-error) */
289 nilfs->ns_pseg_offset = seg_end - seg_start + 1;
292 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
294 /* move forward with a full segment */
295 nilfs->ns_segnum = nilfs->ns_nextnum;
296 nilfs->ns_pseg_offset = 0;
300 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
304 spin_lock(&nilfs->ns_last_segment_lock);
305 cno = nilfs->ns_last_cno;
306 spin_unlock(&nilfs->ns_last_segment_lock);
310 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
312 return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
315 #endif /* _THE_NILFS_H */