nilfs2: see state of root dentry for mount check of snapshots
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / nilfs2 / the_nilfs.h
blobcae56f338b648f53005426137eda467233c2d04a
1 /*
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>
24 #ifndef _THE_NILFS_H
25 #define _THE_NILFS_H
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"
36 /* the_nilfs struct */
37 enum {
38 THE_NILFS_INIT = 0, /* Information from super_block is set */
39 THE_NILFS_LOADED, /* Roll-back/roll-forward has done and
40 the latest checkpoint was loaded */
41 THE_NILFS_DISCONTINUED, /* 'next' pointer chain has broken */
42 THE_NILFS_GC_RUNNING, /* gc process is running */
43 THE_NILFS_SB_DIRTY, /* super block is dirty */
46 /**
47 * struct the_nilfs - struct to supervise multiple nilfs mount points
48 * @ns_flags: flags
49 * @ns_bdev: block device
50 * @ns_bdi: backing dev info
51 * @ns_writer: back pointer to writable nilfs_sb_info
52 * @ns_sem: semaphore for shared states
53 * @ns_writer_sem: semaphore protecting ns_writer attach/detach
54 * @ns_sbh: buffer heads of on-disk super blocks
55 * @ns_sbp: pointers to super block data
56 * @ns_sbwtime: previous write time of super block
57 * @ns_sbwcount: write count of super block
58 * @ns_sbsize: size of valid data in super block
59 * @ns_seg_seq: segment sequence counter
60 * @ns_segnum: index number of the latest full segment.
61 * @ns_nextnum: index number of the full segment index to be used next
62 * @ns_pseg_offset: offset of next partial segment in the current full segment
63 * @ns_cno: next checkpoint number
64 * @ns_ctime: write time of the last segment
65 * @ns_nongc_ctime: write time of the last segment not for cleaner operation
66 * @ns_ndirtyblks: Number of dirty data blocks
67 * @ns_last_segment_lock: lock protecting fields for the latest segment
68 * @ns_last_pseg: start block number of the latest segment
69 * @ns_last_seq: sequence value of the latest segment
70 * @ns_last_cno: checkpoint number of the latest segment
71 * @ns_prot_seq: least sequence number of segments which must not be reclaimed
72 * @ns_prev_seq: base sequence number used to decide if advance log cursor
73 * @ns_segctor_sem: segment constructor semaphore
74 * @ns_dat: DAT file inode
75 * @ns_cpfile: checkpoint file inode
76 * @ns_sufile: segusage file inode
77 * @ns_cptree: rb-tree of all mounted checkpoints (nilfs_root)
78 * @ns_cptree_lock: lock protecting @ns_cptree
79 * @ns_gc_inodes: dummy inodes to keep live blocks
80 * @ns_blocksize_bits: bit length of block size
81 * @ns_blocksize: 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
91 struct the_nilfs {
92 unsigned long ns_flags;
94 struct block_device *ns_bdev;
95 struct backing_dev_info *ns_bdi;
96 struct nilfs_sb_info *ns_writer;
97 struct rw_semaphore ns_sem;
98 struct rw_semaphore ns_writer_sem;
101 * used for
102 * - loading the latest checkpoint exclusively.
103 * - allocating a new full segment.
104 * - protecting s_dirt in the super_block struct
105 * (see nilfs_write_super) and the following fields.
107 struct buffer_head *ns_sbh[2];
108 struct nilfs_super_block *ns_sbp[2];
109 time_t ns_sbwtime;
110 unsigned ns_sbwcount;
111 unsigned ns_sbsize;
112 unsigned ns_mount_state;
115 * Following fields are dedicated to a writable FS-instance.
116 * Except for the period seeking checkpoint, code outside the segment
117 * constructor must lock a segment semaphore while accessing these
118 * fields.
119 * The writable FS-instance is sole during a lifetime of the_nilfs.
121 u64 ns_seg_seq;
122 __u64 ns_segnum;
123 __u64 ns_nextnum;
124 unsigned long ns_pseg_offset;
125 __u64 ns_cno;
126 time_t ns_ctime;
127 time_t ns_nongc_ctime;
128 atomic_t ns_ndirtyblks;
131 * The following fields hold information on the latest partial segment
132 * written to disk with a super root. These fields are protected by
133 * ns_last_segment_lock.
135 spinlock_t ns_last_segment_lock;
136 sector_t ns_last_pseg;
137 u64 ns_last_seq;
138 __u64 ns_last_cno;
139 u64 ns_prot_seq;
140 u64 ns_prev_seq;
142 struct rw_semaphore ns_segctor_sem;
145 * Following fields are lock free except for the period before
146 * the_nilfs is initialized.
148 struct inode *ns_dat;
149 struct inode *ns_cpfile;
150 struct inode *ns_sufile;
152 /* Checkpoint tree */
153 struct rb_root ns_cptree;
154 spinlock_t ns_cptree_lock;
156 /* GC inode list */
157 struct list_head ns_gc_inodes;
159 /* Disk layout information (static) */
160 unsigned int ns_blocksize_bits;
161 unsigned int ns_blocksize;
162 unsigned long ns_nsegments;
163 unsigned long ns_blocks_per_segment;
164 unsigned long ns_r_segments_percentage;
165 unsigned long ns_nrsvsegs;
166 unsigned long ns_first_data_block;
167 int ns_inode_size;
168 int ns_first_ino;
169 u32 ns_crc_seed;
172 #define THE_NILFS_FNS(bit, name) \
173 static inline void set_nilfs_##name(struct the_nilfs *nilfs) \
175 set_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
177 static inline void clear_nilfs_##name(struct the_nilfs *nilfs) \
179 clear_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
181 static inline int nilfs_##name(struct the_nilfs *nilfs) \
183 return test_bit(THE_NILFS_##bit, &(nilfs)->ns_flags); \
186 THE_NILFS_FNS(INIT, init)
187 THE_NILFS_FNS(LOADED, loaded)
188 THE_NILFS_FNS(DISCONTINUED, discontinued)
189 THE_NILFS_FNS(GC_RUNNING, gc_running)
190 THE_NILFS_FNS(SB_DIRTY, sb_dirty)
193 * struct nilfs_root - nilfs root object
194 * @cno: checkpoint number
195 * @rb_node: red-black tree node
196 * @count: refcount of this structure
197 * @nilfs: nilfs object
198 * @ifile: inode file
199 * @root: root inode
200 * @inodes_count: number of inodes
201 * @blocks_count: number of blocks (Reserved)
203 struct nilfs_root {
204 __u64 cno;
205 struct rb_node rb_node;
207 atomic_t count;
208 struct the_nilfs *nilfs;
209 struct inode *ifile;
211 atomic_t inodes_count;
212 atomic_t blocks_count;
215 /* Special checkpoint number */
216 #define NILFS_CPTREE_CURRENT_CNO 0
218 /* Minimum interval of periodical update of superblocks (in seconds) */
219 #define NILFS_SB_FREQ 10
221 static inline int nilfs_sb_need_update(struct the_nilfs *nilfs)
223 u64 t = get_seconds();
224 return t < nilfs->ns_sbwtime || t > nilfs->ns_sbwtime + NILFS_SB_FREQ;
227 static inline int nilfs_sb_will_flip(struct the_nilfs *nilfs)
229 int flip_bits = nilfs->ns_sbwcount & 0x0FL;
230 return (flip_bits != 0x08 && flip_bits != 0x0F);
233 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
234 struct the_nilfs *alloc_nilfs(struct block_device *bdev);
235 void destroy_nilfs(struct the_nilfs *nilfs);
236 int init_nilfs(struct the_nilfs *, struct nilfs_sb_info *, char *);
237 int load_nilfs(struct the_nilfs *, struct nilfs_sb_info *);
238 int nilfs_discard_segments(struct the_nilfs *, __u64 *, size_t);
239 int nilfs_count_free_blocks(struct the_nilfs *, sector_t *);
240 struct nilfs_root *nilfs_lookup_root(struct the_nilfs *nilfs, __u64 cno);
241 struct nilfs_root *nilfs_find_or_create_root(struct the_nilfs *nilfs,
242 __u64 cno);
243 void nilfs_put_root(struct nilfs_root *root);
244 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *, int, __u64);
245 int nilfs_near_disk_full(struct the_nilfs *);
246 void nilfs_fall_back_super_block(struct the_nilfs *);
247 void nilfs_swap_super_block(struct the_nilfs *);
250 static inline void nilfs_get_root(struct nilfs_root *root)
252 atomic_inc(&root->count);
255 static inline void
256 nilfs_attach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
258 down_write(&nilfs->ns_writer_sem);
259 nilfs->ns_writer = sbi;
260 up_write(&nilfs->ns_writer_sem);
263 static inline void
264 nilfs_detach_writer(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
266 down_write(&nilfs->ns_writer_sem);
267 if (sbi == nilfs->ns_writer)
268 nilfs->ns_writer = NULL;
269 up_write(&nilfs->ns_writer_sem);
272 static inline int nilfs_valid_fs(struct the_nilfs *nilfs)
274 unsigned valid_fs;
276 down_read(&nilfs->ns_sem);
277 valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
278 up_read(&nilfs->ns_sem);
279 return valid_fs;
282 static inline void
283 nilfs_get_segment_range(struct the_nilfs *nilfs, __u64 segnum,
284 sector_t *seg_start, sector_t *seg_end)
286 *seg_start = (sector_t)nilfs->ns_blocks_per_segment * segnum;
287 *seg_end = *seg_start + nilfs->ns_blocks_per_segment - 1;
288 if (segnum == 0)
289 *seg_start = nilfs->ns_first_data_block;
292 static inline sector_t
293 nilfs_get_segment_start_blocknr(struct the_nilfs *nilfs, __u64 segnum)
295 return (segnum == 0) ? nilfs->ns_first_data_block :
296 (sector_t)nilfs->ns_blocks_per_segment * segnum;
299 static inline __u64
300 nilfs_get_segnum_of_block(struct the_nilfs *nilfs, sector_t blocknr)
302 sector_t segnum = blocknr;
304 sector_div(segnum, nilfs->ns_blocks_per_segment);
305 return segnum;
308 static inline void
309 nilfs_terminate_segment(struct the_nilfs *nilfs, sector_t seg_start,
310 sector_t seg_end)
312 /* terminate the current full segment (used in case of I/O-error) */
313 nilfs->ns_pseg_offset = seg_end - seg_start + 1;
316 static inline void nilfs_shift_to_next_segment(struct the_nilfs *nilfs)
318 /* move forward with a full segment */
319 nilfs->ns_segnum = nilfs->ns_nextnum;
320 nilfs->ns_pseg_offset = 0;
321 nilfs->ns_seg_seq++;
324 static inline __u64 nilfs_last_cno(struct the_nilfs *nilfs)
326 __u64 cno;
328 spin_lock(&nilfs->ns_last_segment_lock);
329 cno = nilfs->ns_last_cno;
330 spin_unlock(&nilfs->ns_last_segment_lock);
331 return cno;
334 static inline int nilfs_segment_is_active(struct the_nilfs *nilfs, __u64 n)
336 return n == nilfs->ns_segnum || n == nilfs->ns_nextnum;
339 #endif /* _THE_NILFS_H */