xref: /openbmc/linux/fs/nilfs2/the_nilfs.h (revision 4800cd83)
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/rbtree.h>
30 #include <linux/fs.h>
31 #include <linux/blkdev.h>
32 #include <linux/backing-dev.h>
33 #include <linux/slab.h>
34 #include "sb.h"
35 
36 /* the_nilfs struct */
37 enum {
38 	THE_NILFS_INIT = 0,     /* Information from super_block is set */
39 	THE_NILFS_DISCONTINUED,	/* 'next' pointer chain has broken */
40 	THE_NILFS_GC_RUNNING,	/* gc process is running */
41 	THE_NILFS_SB_DIRTY,	/* super block is dirty */
42 };
43 
44 /**
45  * struct the_nilfs - struct to supervise multiple nilfs mount points
46  * @ns_flags: flags
47  * @ns_bdev: block device
48  * @ns_sem: semaphore for shared states
49  * @ns_sbh: buffer heads of on-disk super blocks
50  * @ns_sbp: pointers to super block data
51  * @ns_sbwtime: previous write time of super block
52  * @ns_sbwcount: write count of super block
53  * @ns_sbsize: size of valid data in super block
54  * @ns_seg_seq: segment sequence counter
55  * @ns_segnum: index number of the latest full segment.
56  * @ns_nextnum: index number of the full segment index to be used next
57  * @ns_pseg_offset: offset of next partial segment in the current full segment
58  * @ns_cno: next checkpoint number
59  * @ns_ctime: write time of the last segment
60  * @ns_nongc_ctime: write time of the last segment not for cleaner operation
61  * @ns_ndirtyblks: Number of dirty data blocks
62  * @ns_last_segment_lock: lock protecting fields for the latest segment
63  * @ns_last_pseg: start block number of the latest segment
64  * @ns_last_seq: sequence value of the latest segment
65  * @ns_last_cno: checkpoint number of the latest segment
66  * @ns_prot_seq: least sequence number of segments which must not be reclaimed
67  * @ns_prev_seq: base sequence number used to decide if advance log cursor
68  * @ns_segctor_sem: segment constructor semaphore
69  * @ns_dat: DAT file inode
70  * @ns_cpfile: checkpoint file inode
71  * @ns_sufile: segusage file inode
72  * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
73  * @ns_cptree_lock: lock protecting @ns_cptree
74  * @ns_gc_inodes: dummy inodes to keep live blocks
75  * @ns_blocksize_bits: bit length of block size
76  * @ns_blocksize: block size
77  * @ns_nsegments: number of segments in filesystem
78  * @ns_blocks_per_segment: number of blocks per segment
79  * @ns_r_segments_percentage: reserved segments percentage
80  * @ns_nrsvsegs: number of reserved segments
81  * @ns_first_data_block: block number of first data block
82  * @ns_inode_size: size of on-disk inode
83  * @ns_first_ino: first not-special inode number
84  * @ns_crc_seed: seed value of CRC32 calculation
85  */
86 struct the_nilfs {
87 	unsigned long		ns_flags;
88 
89 	struct block_device    *ns_bdev;
90 	struct rw_semaphore	ns_sem;
91 
92 	/*
93 	 * used for
94 	 * - loading the latest checkpoint exclusively.
95 	 * - allocating a new full segment.
96 	 * - protecting s_dirt in the super_block struct
97 	 *   (see nilfs_write_super) and the following fields.
98 	 */
99 	struct buffer_head     *ns_sbh[2];
100 	struct nilfs_super_block *ns_sbp[2];
101 	time_t			ns_sbwtime;
102 	unsigned		ns_sbwcount;
103 	unsigned		ns_sbsize;
104 	unsigned		ns_mount_state;
105 
106 	/*
107 	 * Following fields are dedicated to a writable FS-instance.
108 	 * Except for the period seeking checkpoint, code outside the segment
109 	 * constructor must lock a segment semaphore while accessing these
110 	 * fields.
111 	 * The writable FS-instance is sole during a lifetime of the_nilfs.
112 	 */
113 	u64			ns_seg_seq;
114 	__u64			ns_segnum;
115 	__u64			ns_nextnum;
116 	unsigned long		ns_pseg_offset;
117 	__u64			ns_cno;
118 	time_t			ns_ctime;
119 	time_t			ns_nongc_ctime;
120 	atomic_t		ns_ndirtyblks;
121 
122 	/*
123 	 * The following fields hold information on the latest partial segment
124 	 * written to disk with a super root.  These fields are protected by
125 	 * ns_last_segment_lock.
126 	 */
127 	spinlock_t		ns_last_segment_lock;
128 	sector_t		ns_last_pseg;
129 	u64			ns_last_seq;
130 	__u64			ns_last_cno;
131 	u64			ns_prot_seq;
132 	u64			ns_prev_seq;
133 
134 	struct rw_semaphore	ns_segctor_sem;
135 
136 	/*
137 	 * Following fields are lock free except for the period before
138 	 * the_nilfs is initialized.
139 	 */
140 	struct inode	       *ns_dat;
141 	struct inode	       *ns_cpfile;
142 	struct inode	       *ns_sufile;
143 
144 	/* Checkpoint tree */
145 	struct rb_root		ns_cptree;
146 	spinlock_t		ns_cptree_lock;
147 
148 	/* GC inode list */
149 	struct list_head	ns_gc_inodes;
150 
151 	/* Disk layout information (static) */
152 	unsigned int		ns_blocksize_bits;
153 	unsigned int		ns_blocksize;
154 	unsigned long		ns_nsegments;
155 	unsigned long		ns_blocks_per_segment;
156 	unsigned long		ns_r_segments_percentage;
157 	unsigned long		ns_nrsvsegs;
158 	unsigned long		ns_first_data_block;
159 	int			ns_inode_size;
160 	int			ns_first_ino;
161 	u32			ns_crc_seed;
162 };
163 
164 #define THE_NILFS_FNS(bit, name)					\
165 static inline void set_nilfs_##name(struct the_nilfs *nilfs)		\
166 {									\
167 	set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);			\
168 }									\
169 static inline void clear_nilfs_##name(struct the_nilfs *nilfs)		\
170 {									\
171 	clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);			\
172 }									\
173 static inline int nilfs_##name(struct the_nilfs *nilfs)			\
174 {									\
175 	return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags);		\
176 }
177 
178 THE_NILFS_FNS(INIT, init)
179 THE_NILFS_FNS(DISCONTINUED, discontinued)
180 THE_NILFS_FNS(GC_RUNNING, gc_running)
181 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
182 
183 /**
184  * struct nilfs_root - nilfs root object
185  * @cno: checkpoint number
186  * @rb_node: red-black tree node
187  * @count: refcount of this structure
188  * @nilfs: nilfs object
189  * @ifile: inode file
190  * @root: root inode
191  * @inodes_count: number of inodes
192  * @blocks_count: number of blocks (Reserved)
193  */
194 struct nilfs_root {
195 	__u64 cno;
196 	struct rb_node rb_node;
197 
198 	atomic_t count;
199 	struct the_nilfs *nilfs;
200 	struct inode *ifile;
201 
202 	atomic_t inodes_count;
203 	atomic_t blocks_count;
204 };
205 
206 /* Special checkpoint number */
207 #define NILFS_CPTREE_CURRENT_CNO	0
208 
209 /* Minimum interval of periodical update of superblocks (in seconds) */
210 #define NILFS_SB_FREQ		10
211 
212 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
213 {
214 	u64 t = get_seconds();
215 	return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
216 }
217 
218 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
219 {
220 	int flip_bits = nilfs->ns_sbwcount & 0x0FL;
221 	return (flip_bits != 0x08 && flip_bits != 0x0F);
222 }
223 
224 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
225 struct the_nilfs *alloc_nilfs(struct block_device *bdev);
226 void destroy_nilfs(struct the_nilfs *nilfs);
227 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
228 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
229 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
230 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
231 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
232 struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
233 					     __u64 cno);
234 void nilfs_put_root(struct nilfs_root *root);
235 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
236 int nilfs_near_disk_full(struct the_nilfs *);
237 void nilfs_fall_back_super_block(struct the_nilfs *);
238 void nilfs_swap_super_block(struct the_nilfs *);
239 
240 
241 static inline void nilfs_get_root(struct nilfs_root *root)
242 {
243 	atomic_inc(&root->count);
244 }
245 
246 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
247 {
248 	unsigned valid_fs;
249 
250 	down_read(&nilfs->ns_sem);
251 	valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
252 	up_read(&nilfs->ns_sem);
253 	return valid_fs;
254 }
255 
256 static inline void
257 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
258 			sector_t *seg_start, sector_t *seg_end)
259 {
260 	*seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
261 	*seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
262 	if (segnum == 0)
263 		*seg_start = nilfs->ns_first_data_block;
264 }
265 
266 static inline sector_t
267 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
268 {
269 	return (segnum == 0) ? nilfs->ns_first_data_block :
270 		(sector_t)nilfs->ns_blocks_per_segment * segnum;
271 }
272 
273 static inline __u64
274 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
275 {
276 	sector_t segnum = blocknr;
277 
278 	sector_div(segnum, nilfs->ns_blocks_per_segment);
279 	return segnum;
280 }
281 
282 static inline void
283 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
284 			sector_t seg_end)
285 {
286 	/* terminate the current full segment (used in case of I/O-error) */
287 	nilfs->ns_pseg_offset = seg_end - seg_start + 1;
288 }
289 
290 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
291 {
292 	/* move forward with a full segment */
293 	nilfs->ns_segnum = nilfs->ns_nextnum;
294 	nilfs->ns_pseg_offset = 0;
295 	nilfs->ns_seg_seq++;
296 }
297 
298 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
299 {
300 	__u64 cno;
301 
302 	spin_lock(&nilfs->ns_last_segment_lock);
303 	cno = nilfs->ns_last_cno;
304 	spin_unlock(&nilfs->ns_last_segment_lock);
305 	return cno;
306 }
307 
308 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
309 {
310 	return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
311 }
312 
313 #endif /* _THE_NILFS_H */
314