nilfs2: rename nilfs_recover_logical_segments function
[linux-2.6.git] / fs / nilfs2 / the_nilfs.c
1 /*
2  * the_nilfs.c - 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 #include <linux/buffer_head.h>
25 #include <linux/slab.h>
26 #include <linux/blkdev.h>
27 #include <linux/backing-dev.h>
28 #include <linux/crc32.h>
29 #include "nilfs.h"
30 #include "segment.h"
31 #include "alloc.h"
32 #include "cpfile.h"
33 #include "sufile.h"
34 #include "dat.h"
35 #include "segbuf.h"
36
37
38 static LIST_HEAD(nilfs_objects);
39 static DEFINE_SPINLOCK(nilfs_lock);
40
41 void nilfs_set_last_segment(struct the_nilfs *nilfs,
42                             sector_t start_blocknr, u64 seq, __u64 cno)
43 {
44         spin_lock(&nilfs->ns_last_segment_lock);
45         nilfs->ns_last_pseg = start_blocknr;
46         nilfs->ns_last_seq = seq;
47         nilfs->ns_last_cno = cno;
48         spin_unlock(&nilfs->ns_last_segment_lock);
49 }
50
51 /**
52  * alloc_nilfs - allocate the_nilfs structure
53  * @bdev: block device to which the_nilfs is related
54  *
55  * alloc_nilfs() allocates memory for the_nilfs and
56  * initializes its reference count and locks.
57  *
58  * Return Value: On success, pointer to the_nilfs is returned.
59  * On error, NULL is returned.
60  */
61 static struct the_nilfs *alloc_nilfs(struct block_device *bdev)
62 {
63         struct the_nilfs *nilfs;
64
65         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
66         if (!nilfs)
67                 return NULL;
68
69         nilfs->ns_bdev = bdev;
70         atomic_set(&nilfs->ns_count, 1);
71         atomic_set(&nilfs->ns_ndirtyblks, 0);
72         init_rwsem(&nilfs->ns_sem);
73         init_rwsem(&nilfs->ns_super_sem);
74         mutex_init(&nilfs->ns_mount_mutex);
75         init_rwsem(&nilfs->ns_writer_sem);
76         INIT_LIST_HEAD(&nilfs->ns_list);
77         INIT_LIST_HEAD(&nilfs->ns_supers);
78         spin_lock_init(&nilfs->ns_last_segment_lock);
79         nilfs->ns_gc_inodes_h = NULL;
80         init_rwsem(&nilfs->ns_segctor_sem);
81
82         return nilfs;
83 }
84
85 /**
86  * find_or_create_nilfs - find or create nilfs object
87  * @bdev: block device to which the_nilfs is related
88  *
89  * find_nilfs() looks up an existent nilfs object created on the
90  * device and gets the reference count of the object.  If no nilfs object
91  * is found on the device, a new nilfs object is allocated.
92  *
93  * Return Value: On success, pointer to the nilfs object is returned.
94  * On error, NULL is returned.
95  */
96 struct the_nilfs *find_or_create_nilfs(struct block_device *bdev)
97 {
98         struct the_nilfs *nilfs, *new = NULL;
99
100  retry:
101         spin_lock(&nilfs_lock);
102         list_for_each_entry(nilfs, &nilfs_objects, ns_list) {
103                 if (nilfs->ns_bdev == bdev) {
104                         get_nilfs(nilfs);
105                         spin_unlock(&nilfs_lock);
106                         if (new)
107                                 put_nilfs(new);
108                         return nilfs; /* existing object */
109                 }
110         }
111         if (new) {
112                 list_add_tail(&new->ns_list, &nilfs_objects);
113                 spin_unlock(&nilfs_lock);
114                 return new; /* new object */
115         }
116         spin_unlock(&nilfs_lock);
117
118         new = alloc_nilfs(bdev);
119         if (new)
120                 goto retry;
121         return NULL; /* insufficient memory */
122 }
123
124 /**
125  * put_nilfs - release a reference to the_nilfs
126  * @nilfs: the_nilfs structure to be released
127  *
128  * put_nilfs() decrements a reference counter of the_nilfs.
129  * If the reference count reaches zero, the_nilfs is freed.
130  */
131 void put_nilfs(struct the_nilfs *nilfs)
132 {
133         spin_lock(&nilfs_lock);
134         if (!atomic_dec_and_test(&nilfs->ns_count)) {
135                 spin_unlock(&nilfs_lock);
136                 return;
137         }
138         list_del_init(&nilfs->ns_list);
139         spin_unlock(&nilfs_lock);
140
141         /*
142          * Increment of ns_count never occurs below because the caller
143          * of get_nilfs() holds at least one reference to the_nilfs.
144          * Thus its exclusion control is not required here.
145          */
146
147         might_sleep();
148         if (nilfs_loaded(nilfs)) {
149                 nilfs_mdt_destroy(nilfs->ns_sufile);
150                 nilfs_mdt_destroy(nilfs->ns_cpfile);
151                 nilfs_mdt_destroy(nilfs->ns_dat);
152                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
153         }
154         if (nilfs_init(nilfs)) {
155                 nilfs_destroy_gccache(nilfs);
156                 brelse(nilfs->ns_sbh[0]);
157                 brelse(nilfs->ns_sbh[1]);
158         }
159         kfree(nilfs);
160 }
161
162 static int nilfs_load_super_root(struct the_nilfs *nilfs, sector_t sr_block)
163 {
164         struct buffer_head *bh_sr;
165         struct nilfs_super_root *raw_sr;
166         struct nilfs_super_block **sbp = nilfs->ns_sbp;
167         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
168         unsigned inode_size;
169         int err;
170
171         err = nilfs_read_super_root_block(nilfs, sr_block, &bh_sr, 1);
172         if (unlikely(err))
173                 return err;
174
175         down_read(&nilfs->ns_sem);
176         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
177         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
178         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
179         up_read(&nilfs->ns_sem);
180
181         inode_size = nilfs->ns_inode_size;
182
183         err = -ENOMEM;
184         nilfs->ns_dat = nilfs_dat_new(nilfs, dat_entry_size);
185         if (unlikely(!nilfs->ns_dat))
186                 goto failed;
187
188         nilfs->ns_gc_dat = nilfs_dat_new(nilfs, dat_entry_size);
189         if (unlikely(!nilfs->ns_gc_dat))
190                 goto failed_dat;
191
192         nilfs->ns_cpfile = nilfs_cpfile_new(nilfs, checkpoint_size);
193         if (unlikely(!nilfs->ns_cpfile))
194                 goto failed_gc_dat;
195
196         nilfs->ns_sufile = nilfs_sufile_new(nilfs, segment_usage_size);
197         if (unlikely(!nilfs->ns_sufile))
198                 goto failed_cpfile;
199
200         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
201
202         err = nilfs_dat_read(nilfs->ns_dat, (void *)bh_sr->b_data +
203                              NILFS_SR_DAT_OFFSET(inode_size));
204         if (unlikely(err))
205                 goto failed_sufile;
206
207         err = nilfs_cpfile_read(nilfs->ns_cpfile, (void *)bh_sr->b_data +
208                                 NILFS_SR_CPFILE_OFFSET(inode_size));
209         if (unlikely(err))
210                 goto failed_sufile;
211
212         err = nilfs_sufile_read(nilfs->ns_sufile, (void *)bh_sr->b_data +
213                                 NILFS_SR_SUFILE_OFFSET(inode_size));
214         if (unlikely(err))
215                 goto failed_sufile;
216
217         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
218         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
219
220  failed:
221         brelse(bh_sr);
222         return err;
223
224  failed_sufile:
225         nilfs_mdt_destroy(nilfs->ns_sufile);
226
227  failed_cpfile:
228         nilfs_mdt_destroy(nilfs->ns_cpfile);
229
230  failed_gc_dat:
231         nilfs_mdt_destroy(nilfs->ns_gc_dat);
232
233  failed_dat:
234         nilfs_mdt_destroy(nilfs->ns_dat);
235         goto failed;
236 }
237
238 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
239 {
240         memset(ri, 0, sizeof(*ri));
241         INIT_LIST_HEAD(&ri->ri_used_segments);
242 }
243
244 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
245 {
246         nilfs_dispose_segment_list(&ri->ri_used_segments);
247 }
248
249 /**
250  * load_nilfs - load and recover the nilfs
251  * @nilfs: the_nilfs structure to be released
252  * @sbi: nilfs_sb_info used to recover past segment
253  *
254  * load_nilfs() searches and load the latest super root,
255  * attaches the last segment, and does recovery if needed.
256  * The caller must call this exclusively for simultaneous mounts.
257  */
258 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
259 {
260         struct nilfs_recovery_info ri;
261         unsigned int s_flags = sbi->s_super->s_flags;
262         int really_read_only = bdev_read_only(nilfs->ns_bdev);
263         int valid_fs = nilfs_valid_fs(nilfs);
264         int err;
265
266         if (nilfs_loaded(nilfs)) {
267                 if (valid_fs ||
268                     ((s_flags & MS_RDONLY) && nilfs_test_opt(sbi, NORECOVERY)))
269                         return 0;
270                 printk(KERN_ERR "NILFS: the filesystem is in an incomplete "
271                        "recovery state.\n");
272                 return -EINVAL;
273         }
274
275         if (!valid_fs) {
276                 printk(KERN_WARNING "NILFS warning: mounting unchecked fs\n");
277                 if (s_flags & MS_RDONLY) {
278                         printk(KERN_INFO "NILFS: INFO: recovery "
279                                "required for readonly filesystem.\n");
280                         printk(KERN_INFO "NILFS: write access will "
281                                "be enabled during recovery.\n");
282                 }
283         }
284
285         nilfs_init_recovery_info(&ri);
286
287         err = nilfs_search_super_root(nilfs, &ri);
288         if (unlikely(err)) {
289                 printk(KERN_ERR "NILFS: error searching super root.\n");
290                 goto failed;
291         }
292
293         err = nilfs_load_super_root(nilfs, ri.ri_super_root);
294         if (unlikely(err)) {
295                 printk(KERN_ERR "NILFS: error loading super root.\n");
296                 goto failed;
297         }
298
299         if (valid_fs)
300                 goto skip_recovery;
301
302         if (s_flags & MS_RDONLY) {
303                 if (nilfs_test_opt(sbi, NORECOVERY)) {
304                         printk(KERN_INFO "NILFS: norecovery option specified. "
305                                "skipping roll-forward recovery\n");
306                         goto skip_recovery;
307                 }
308                 if (really_read_only) {
309                         printk(KERN_ERR "NILFS: write access "
310                                "unavailable, cannot proceed.\n");
311                         err = -EROFS;
312                         goto failed_unload;
313                 }
314                 sbi->s_super->s_flags &= ~MS_RDONLY;
315         } else if (nilfs_test_opt(sbi, NORECOVERY)) {
316                 printk(KERN_ERR "NILFS: recovery cancelled because norecovery "
317                        "option was specified for a read/write mount\n");
318                 err = -EINVAL;
319                 goto failed_unload;
320         }
321
322         err = nilfs_salvage_orphan_logs(nilfs, sbi, &ri);
323         if (err)
324                 goto failed_unload;
325
326         down_write(&nilfs->ns_sem);
327         nilfs->ns_mount_state |= NILFS_VALID_FS;
328         nilfs->ns_sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
329         err = nilfs_commit_super(sbi, 1);
330         up_write(&nilfs->ns_sem);
331
332         if (err) {
333                 printk(KERN_ERR "NILFS: failed to update super block. "
334                        "recovery unfinished.\n");
335                 goto failed_unload;
336         }
337         printk(KERN_INFO "NILFS: recovery complete.\n");
338
339  skip_recovery:
340         set_nilfs_loaded(nilfs);
341         nilfs_clear_recovery_info(&ri);
342         sbi->s_super->s_flags = s_flags;
343         return 0;
344
345  failed_unload:
346         nilfs_mdt_destroy(nilfs->ns_cpfile);
347         nilfs_mdt_destroy(nilfs->ns_sufile);
348         nilfs_mdt_destroy(nilfs->ns_dat);
349
350  failed:
351         nilfs_clear_recovery_info(&ri);
352         sbi->s_super->s_flags = s_flags;
353         return err;
354 }
355
356 static unsigned long long nilfs_max_size(unsigned int blkbits)
357 {
358         unsigned int max_bits;
359         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
360
361         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
362         if (max_bits < 64)
363                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
364         return res;
365 }
366
367 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
368                                    struct nilfs_super_block *sbp)
369 {
370         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
371                 printk(KERN_ERR "NILFS: revision mismatch "
372                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
373                        "Please check the version of mkfs.nilfs.\n",
374                        le32_to_cpu(sbp->s_rev_level),
375                        le16_to_cpu(sbp->s_minor_rev_level),
376                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
377                 return -EINVAL;
378         }
379         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
380         if (nilfs->ns_sbsize > BLOCK_SIZE)
381                 return -EINVAL;
382
383         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
384         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
385
386         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
387         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
388                 printk(KERN_ERR "NILFS: too short segment.\n");
389                 return -EINVAL;
390         }
391
392         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
393         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
394         nilfs->ns_r_segments_percentage =
395                 le32_to_cpu(sbp->s_r_segments_percentage);
396         nilfs->ns_nrsvsegs =
397                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
398                       DIV_ROUND_UP(nilfs->ns_nsegments *
399                                    nilfs->ns_r_segments_percentage, 100));
400         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
401         return 0;
402 }
403
404 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
405 {
406         static unsigned char sum[4];
407         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
408         size_t bytes;
409         u32 crc;
410
411         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
412                 return 0;
413         bytes = le16_to_cpu(sbp->s_bytes);
414         if (bytes > BLOCK_SIZE)
415                 return 0;
416         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
417                        sumoff);
418         crc = crc32_le(crc, sum, 4);
419         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
420                        bytes - sumoff - 4);
421         return crc == le32_to_cpu(sbp->s_sum);
422 }
423
424 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
425 {
426         return offset < ((le64_to_cpu(sbp->s_nsegments) *
427                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
428                          (le32_to_cpu(sbp->s_log_block_size) + 10));
429 }
430
431 static void nilfs_release_super_block(struct the_nilfs *nilfs)
432 {
433         int i;
434
435         for (i = 0; i < 2; i++) {
436                 if (nilfs->ns_sbp[i]) {
437                         brelse(nilfs->ns_sbh[i]);
438                         nilfs->ns_sbh[i] = NULL;
439                         nilfs->ns_sbp[i] = NULL;
440                 }
441         }
442 }
443
444 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
445 {
446         brelse(nilfs->ns_sbh[0]);
447         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
448         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
449         nilfs->ns_sbh[1] = NULL;
450         nilfs->ns_sbp[1] = NULL;
451 }
452
453 void nilfs_swap_super_block(struct the_nilfs *nilfs)
454 {
455         struct buffer_head *tsbh = nilfs->ns_sbh[0];
456         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
457
458         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
459         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
460         nilfs->ns_sbh[1] = tsbh;
461         nilfs->ns_sbp[1] = tsbp;
462 }
463
464 static int nilfs_load_super_block(struct the_nilfs *nilfs,
465                                   struct super_block *sb, int blocksize,
466                                   struct nilfs_super_block **sbpp)
467 {
468         struct nilfs_super_block **sbp = nilfs->ns_sbp;
469         struct buffer_head **sbh = nilfs->ns_sbh;
470         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
471         int valid[2], swp = 0;
472
473         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
474                                         &sbh[0]);
475         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
476
477         if (!sbp[0]) {
478                 if (!sbp[1]) {
479                         printk(KERN_ERR "NILFS: unable to read superblock\n");
480                         return -EIO;
481                 }
482                 printk(KERN_WARNING
483                        "NILFS warning: unable to read primary superblock\n");
484         } else if (!sbp[1])
485                 printk(KERN_WARNING
486                        "NILFS warning: unable to read secondary superblock\n");
487
488         /*
489          * Compare two super blocks and set 1 in swp if the secondary
490          * super block is valid and newer.  Otherwise, set 0 in swp.
491          */
492         valid[0] = nilfs_valid_sb(sbp[0]);
493         valid[1] = nilfs_valid_sb(sbp[1]);
494         swp = valid[1] && (!valid[0] ||
495                            le64_to_cpu(sbp[1]->s_last_cno) >
496                            le64_to_cpu(sbp[0]->s_last_cno));
497
498         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
499                 brelse(sbh[1]);
500                 sbh[1] = NULL;
501                 sbp[1] = NULL;
502                 swp = 0;
503         }
504         if (!valid[swp]) {
505                 nilfs_release_super_block(nilfs);
506                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
507                        sb->s_id);
508                 return -EINVAL;
509         }
510
511         if (swp) {
512                 printk(KERN_WARNING "NILFS warning: broken superblock. "
513                        "using spare superblock.\n");
514                 nilfs_swap_super_block(nilfs);
515         }
516
517         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
518         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
519         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
520         *sbpp = sbp[0];
521         return 0;
522 }
523
524 /**
525  * init_nilfs - initialize a NILFS instance.
526  * @nilfs: the_nilfs structure
527  * @sbi: nilfs_sb_info
528  * @sb: super block
529  * @data: mount options
530  *
531  * init_nilfs() performs common initialization per block device (e.g.
532  * reading the super block, getting disk layout information, initializing
533  * shared fields in the_nilfs). It takes on some portion of the jobs
534  * typically done by a fill_super() routine. This division arises from
535  * the nature that multiple NILFS instances may be simultaneously
536  * mounted on a device.
537  * For multiple mounts on the same device, only the first mount
538  * invokes these tasks.
539  *
540  * Return Value: On success, 0 is returned. On error, a negative error
541  * code is returned.
542  */
543 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
544 {
545         struct super_block *sb = sbi->s_super;
546         struct nilfs_super_block *sbp;
547         struct backing_dev_info *bdi;
548         int blocksize;
549         int err;
550
551         down_write(&nilfs->ns_sem);
552         if (nilfs_init(nilfs)) {
553                 /* Load values from existing the_nilfs */
554                 sbp = nilfs->ns_sbp[0];
555                 err = nilfs_store_magic_and_option(sb, sbp, data);
556                 if (err)
557                         goto out;
558
559                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
560                 if (sb->s_blocksize != blocksize &&
561                     !sb_set_blocksize(sb, blocksize)) {
562                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
563                                blocksize);
564                         err = -EINVAL;
565                 }
566                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
567                 goto out;
568         }
569
570         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
571         if (!blocksize) {
572                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
573                 err = -EINVAL;
574                 goto out;
575         }
576         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
577         if (err)
578                 goto out;
579
580         err = nilfs_store_magic_and_option(sb, sbp, data);
581         if (err)
582                 goto failed_sbh;
583
584         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
585         if (sb->s_blocksize != blocksize) {
586                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
587
588                 if (blocksize < hw_blocksize) {
589                         printk(KERN_ERR
590                                "NILFS: blocksize %d too small for device "
591                                "(sector-size = %d).\n",
592                                blocksize, hw_blocksize);
593                         err = -EINVAL;
594                         goto failed_sbh;
595                 }
596                 nilfs_release_super_block(nilfs);
597                 sb_set_blocksize(sb, blocksize);
598
599                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
600                 if (err)
601                         goto out;
602                         /* not failed_sbh; sbh is released automatically
603                            when reloading fails. */
604         }
605         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
606         nilfs->ns_blocksize = blocksize;
607
608         err = nilfs_store_disk_layout(nilfs, sbp);
609         if (err)
610                 goto failed_sbh;
611
612         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
613
614         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
615
616         bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
617         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
618
619         /* Finding last segment */
620         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
621         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
622         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
623
624         nilfs->ns_seg_seq = nilfs->ns_last_seq;
625         nilfs->ns_segnum =
626                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
627         nilfs->ns_cno = nilfs->ns_last_cno + 1;
628         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
629                 printk(KERN_ERR "NILFS invalid last segment number.\n");
630                 err = -EINVAL;
631                 goto failed_sbh;
632         }
633         /* Dummy values  */
634         nilfs->ns_free_segments_count =
635                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
636
637         /* Initialize gcinode cache */
638         err = nilfs_init_gccache(nilfs);
639         if (err)
640                 goto failed_sbh;
641
642         set_nilfs_init(nilfs);
643         err = 0;
644  out:
645         up_write(&nilfs->ns_sem);
646         return err;
647
648  failed_sbh:
649         nilfs_release_super_block(nilfs);
650         goto out;
651 }
652
653 int nilfs_discard_segments(struct the_nilfs *nilfs, __u64 *segnump,
654                             size_t nsegs)
655 {
656         sector_t seg_start, seg_end;
657         sector_t start = 0, nblocks = 0;
658         unsigned int sects_per_block;
659         __u64 *sn;
660         int ret = 0;
661
662         sects_per_block = (1 << nilfs->ns_blocksize_bits) /
663                 bdev_logical_block_size(nilfs->ns_bdev);
664         for (sn = segnump; sn < segnump + nsegs; sn++) {
665                 nilfs_get_segment_range(nilfs, *sn, &seg_start, &seg_end);
666
667                 if (!nblocks) {
668                         start = seg_start;
669                         nblocks = seg_end - seg_start + 1;
670                 } else if (start + nblocks == seg_start) {
671                         nblocks += seg_end - seg_start + 1;
672                 } else {
673                         ret = blkdev_issue_discard(nilfs->ns_bdev,
674                                                    start * sects_per_block,
675                                                    nblocks * sects_per_block,
676                                                    GFP_NOFS,
677                                                    BLKDEV_IFL_BARRIER);
678                         if (ret < 0)
679                                 return ret;
680                         nblocks = 0;
681                 }
682         }
683         if (nblocks)
684                 ret = blkdev_issue_discard(nilfs->ns_bdev,
685                                            start * sects_per_block,
686                                            nblocks * sects_per_block,
687                                            GFP_NOFS, BLKDEV_IFL_BARRIER);
688         return ret;
689 }
690
691 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
692 {
693         struct inode *dat = nilfs_dat_inode(nilfs);
694         unsigned long ncleansegs;
695
696         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
697         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
698         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
699         *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
700         return 0;
701 }
702
703 int nilfs_near_disk_full(struct the_nilfs *nilfs)
704 {
705         unsigned long ncleansegs, nincsegs;
706
707         ncleansegs = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile);
708         nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
709                 nilfs->ns_blocks_per_segment + 1;
710
711         return ncleansegs <= nilfs->ns_nrsvsegs + nincsegs;
712 }
713
714 /**
715  * nilfs_find_sbinfo - find existing nilfs_sb_info structure
716  * @nilfs: nilfs object
717  * @rw_mount: mount type (non-zero value for read/write mount)
718  * @cno: checkpoint number (zero for read-only mount)
719  *
720  * nilfs_find_sbinfo() returns the nilfs_sb_info structure which
721  * @rw_mount and @cno (in case of snapshots) matched.  If no instance
722  * was found, NULL is returned.  Although the super block instance can
723  * be unmounted after this function returns, the nilfs_sb_info struct
724  * is kept on memory until nilfs_put_sbinfo() is called.
725  */
726 struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
727                                         int rw_mount, __u64 cno)
728 {
729         struct nilfs_sb_info *sbi;
730
731         down_read(&nilfs->ns_super_sem);
732         /*
733          * The SNAPSHOT flag and sb->s_flags are supposed to be
734          * protected with nilfs->ns_super_sem.
735          */
736         sbi = nilfs->ns_current;
737         if (rw_mount) {
738                 if (sbi && !(sbi->s_super->s_flags & MS_RDONLY))
739                         goto found; /* read/write mount */
740                 else
741                         goto out;
742         } else if (cno == 0) {
743                 if (sbi && (sbi->s_super->s_flags & MS_RDONLY))
744                         goto found; /* read-only mount */
745                 else
746                         goto out;
747         }
748
749         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
750                 if (nilfs_test_opt(sbi, SNAPSHOT) &&
751                     sbi->s_snapshot_cno == cno)
752                         goto found; /* snapshot mount */
753         }
754  out:
755         up_read(&nilfs->ns_super_sem);
756         return NULL;
757
758  found:
759         atomic_inc(&sbi->s_count);
760         up_read(&nilfs->ns_super_sem);
761         return sbi;
762 }
763
764 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
765                                 int snapshot_mount)
766 {
767         struct nilfs_sb_info *sbi;
768         int ret = 0;
769
770         down_read(&nilfs->ns_super_sem);
771         if (cno == 0 || cno > nilfs->ns_cno)
772                 goto out_unlock;
773
774         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
775                 if (sbi->s_snapshot_cno == cno &&
776                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
777                                         /* exclude read-only mounts */
778                         ret++;
779                         break;
780                 }
781         }
782         /* for protecting recent checkpoints */
783         if (cno >= nilfs_last_cno(nilfs))
784                 ret++;
785
786  out_unlock:
787         up_read(&nilfs->ns_super_sem);
788         return ret;
789 }