block: Do away with the notion of hardsect_size
[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 "seglist.h"
36 #include "segbuf.h"
37
38 void nilfs_set_last_segment(struct the_nilfs *nilfs,
39                             sector_t start_blocknr, u64 seq, __u64 cno)
40 {
41         spin_lock(&nilfs->ns_last_segment_lock);
42         nilfs->ns_last_pseg = start_blocknr;
43         nilfs->ns_last_seq = seq;
44         nilfs->ns_last_cno = cno;
45         spin_unlock(&nilfs->ns_last_segment_lock);
46 }
47
48 /**
49  * alloc_nilfs - allocate the_nilfs structure
50  * @bdev: block device to which the_nilfs is related
51  *
52  * alloc_nilfs() allocates memory for the_nilfs and
53  * initializes its reference count and locks.
54  *
55  * Return Value: On success, pointer to the_nilfs is returned.
56  * On error, NULL is returned.
57  */
58 struct the_nilfs *alloc_nilfs(struct block_device *bdev)
59 {
60         struct the_nilfs *nilfs;
61
62         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
63         if (!nilfs)
64                 return NULL;
65
66         nilfs->ns_bdev = bdev;
67         atomic_set(&nilfs->ns_count, 1);
68         atomic_set(&nilfs->ns_writer_refcount, -1);
69         atomic_set(&nilfs->ns_ndirtyblks, 0);
70         init_rwsem(&nilfs->ns_sem);
71         mutex_init(&nilfs->ns_writer_mutex);
72         INIT_LIST_HEAD(&nilfs->ns_supers);
73         spin_lock_init(&nilfs->ns_last_segment_lock);
74         nilfs->ns_gc_inodes_h = NULL;
75         init_rwsem(&nilfs->ns_segctor_sem);
76
77         return nilfs;
78 }
79
80 /**
81  * put_nilfs - release a reference to the_nilfs
82  * @nilfs: the_nilfs structure to be released
83  *
84  * put_nilfs() decrements a reference counter of the_nilfs.
85  * If the reference count reaches zero, the_nilfs is freed.
86  */
87 void put_nilfs(struct the_nilfs *nilfs)
88 {
89         if (!atomic_dec_and_test(&nilfs->ns_count))
90                 return;
91         /*
92          * Increment of ns_count never occur below because the caller
93          * of get_nilfs() holds at least one reference to the_nilfs.
94          * Thus its exclusion control is not required here.
95          */
96         might_sleep();
97         if (nilfs_loaded(nilfs)) {
98                 nilfs_mdt_clear(nilfs->ns_sufile);
99                 nilfs_mdt_destroy(nilfs->ns_sufile);
100                 nilfs_mdt_clear(nilfs->ns_cpfile);
101                 nilfs_mdt_destroy(nilfs->ns_cpfile);
102                 nilfs_mdt_clear(nilfs->ns_dat);
103                 nilfs_mdt_destroy(nilfs->ns_dat);
104                 /* XXX: how and when to clear nilfs->ns_gc_dat? */
105                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
106         }
107         if (nilfs_init(nilfs)) {
108                 nilfs_destroy_gccache(nilfs);
109                 brelse(nilfs->ns_sbh[0]);
110                 brelse(nilfs->ns_sbh[1]);
111         }
112         kfree(nilfs);
113 }
114
115 static int nilfs_load_super_root(struct the_nilfs *nilfs,
116                                  struct nilfs_sb_info *sbi, sector_t sr_block)
117 {
118         static struct lock_class_key dat_lock_key;
119         struct buffer_head *bh_sr;
120         struct nilfs_super_root *raw_sr;
121         struct nilfs_super_block **sbp = nilfs->ns_sbp;
122         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
123         unsigned inode_size;
124         int err;
125
126         err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
127         if (unlikely(err))
128                 return err;
129
130         down_read(&nilfs->ns_sem);
131         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
132         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
133         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
134         up_read(&nilfs->ns_sem);
135
136         inode_size = nilfs->ns_inode_size;
137
138         err = -ENOMEM;
139         nilfs->ns_dat = nilfs_mdt_new(
140                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
141         if (unlikely(!nilfs->ns_dat))
142                 goto failed;
143
144         nilfs->ns_gc_dat = nilfs_mdt_new(
145                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
146         if (unlikely(!nilfs->ns_gc_dat))
147                 goto failed_dat;
148
149         nilfs->ns_cpfile = nilfs_mdt_new(
150                 nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
151         if (unlikely(!nilfs->ns_cpfile))
152                 goto failed_gc_dat;
153
154         nilfs->ns_sufile = nilfs_mdt_new(
155                 nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
156         if (unlikely(!nilfs->ns_sufile))
157                 goto failed_cpfile;
158
159         err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
160         if (unlikely(err))
161                 goto failed_sufile;
162
163         err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
164         if (unlikely(err))
165                 goto failed_sufile;
166
167         lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key);
168         lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key);
169
170         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
171         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
172                                  sizeof(struct nilfs_cpfile_header));
173         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
174                                  sizeof(struct nilfs_sufile_header));
175
176         err = nilfs_mdt_read_inode_direct(
177                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
178         if (unlikely(err))
179                 goto failed_sufile;
180
181         err = nilfs_mdt_read_inode_direct(
182                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
183         if (unlikely(err))
184                 goto failed_sufile;
185
186         err = nilfs_mdt_read_inode_direct(
187                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
188         if (unlikely(err))
189                 goto failed_sufile;
190
191         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
192         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
193
194  failed:
195         brelse(bh_sr);
196         return err;
197
198  failed_sufile:
199         nilfs_mdt_destroy(nilfs->ns_sufile);
200
201  failed_cpfile:
202         nilfs_mdt_destroy(nilfs->ns_cpfile);
203
204  failed_gc_dat:
205         nilfs_mdt_destroy(nilfs->ns_gc_dat);
206
207  failed_dat:
208         nilfs_mdt_destroy(nilfs->ns_dat);
209         goto failed;
210 }
211
212 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
213 {
214         memset(ri, 0, sizeof(*ri));
215         INIT_LIST_HEAD(&ri->ri_used_segments);
216 }
217
218 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
219 {
220         nilfs_dispose_segment_list(&ri->ri_used_segments);
221 }
222
223 /**
224  * load_nilfs - load and recover the nilfs
225  * @nilfs: the_nilfs structure to be released
226  * @sbi: nilfs_sb_info used to recover past segment
227  *
228  * load_nilfs() searches and load the latest super root,
229  * attaches the last segment, and does recovery if needed.
230  * The caller must call this exclusively for simultaneous mounts.
231  */
232 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
233 {
234         struct nilfs_recovery_info ri;
235         unsigned int s_flags = sbi->s_super->s_flags;
236         int really_read_only = bdev_read_only(nilfs->ns_bdev);
237         unsigned valid_fs;
238         int err = 0;
239
240         nilfs_init_recovery_info(&ri);
241
242         down_write(&nilfs->ns_sem);
243         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
244         up_write(&nilfs->ns_sem);
245
246         if (!valid_fs && (s_flags & MS_RDONLY)) {
247                 printk(KERN_INFO "NILFS: INFO: recovery "
248                        "required for readonly filesystem.\n");
249                 if (really_read_only) {
250                         printk(KERN_ERR "NILFS: write access "
251                                "unavailable, cannot proceed.\n");
252                         err = -EROFS;
253                         goto failed;
254                 }
255                 printk(KERN_INFO "NILFS: write access will "
256                        "be enabled during recovery.\n");
257                 sbi->s_super->s_flags &= ~MS_RDONLY;
258         }
259
260         err = nilfs_search_super_root(nilfs, sbi, &ri);
261         if (unlikely(err)) {
262                 printk(KERN_ERR "NILFS: error searching super root.\n");
263                 goto failed;
264         }
265
266         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
267         if (unlikely(err)) {
268                 printk(KERN_ERR "NILFS: error loading super root.\n");
269                 goto failed;
270         }
271
272         if (!valid_fs) {
273                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
274                 if (unlikely(err)) {
275                         nilfs_mdt_destroy(nilfs->ns_cpfile);
276                         nilfs_mdt_destroy(nilfs->ns_sufile);
277                         nilfs_mdt_destroy(nilfs->ns_dat);
278                         goto failed;
279                 }
280                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
281                         sbi->s_super->s_dirt = 1;
282         }
283
284         set_nilfs_loaded(nilfs);
285
286  failed:
287         nilfs_clear_recovery_info(&ri);
288         sbi->s_super->s_flags = s_flags;
289         return err;
290 }
291
292 static unsigned long long nilfs_max_size(unsigned int blkbits)
293 {
294         unsigned int max_bits;
295         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
296
297         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
298         if (max_bits < 64)
299                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
300         return res;
301 }
302
303 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
304                                    struct nilfs_super_block *sbp)
305 {
306         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
307                 printk(KERN_ERR "NILFS: revision mismatch "
308                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
309                        "Please check the version of mkfs.nilfs.\n",
310                        le32_to_cpu(sbp->s_rev_level),
311                        le16_to_cpu(sbp->s_minor_rev_level),
312                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
313                 return -EINVAL;
314         }
315         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
316         if (nilfs->ns_sbsize > BLOCK_SIZE)
317                 return -EINVAL;
318
319         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
320         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
321
322         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
323         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
324                 printk(KERN_ERR "NILFS: too short segment. \n");
325                 return -EINVAL;
326         }
327
328         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
329         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
330         nilfs->ns_r_segments_percentage =
331                 le32_to_cpu(sbp->s_r_segments_percentage);
332         nilfs->ns_nrsvsegs =
333                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
334                       DIV_ROUND_UP(nilfs->ns_nsegments *
335                                    nilfs->ns_r_segments_percentage, 100));
336         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
337         return 0;
338 }
339
340 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
341 {
342         static unsigned char sum[4];
343         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
344         size_t bytes;
345         u32 crc;
346
347         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
348                 return 0;
349         bytes = le16_to_cpu(sbp->s_bytes);
350         if (bytes > BLOCK_SIZE)
351                 return 0;
352         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
353                        sumoff);
354         crc = crc32_le(crc, sum, 4);
355         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
356                        bytes - sumoff - 4);
357         return crc == le32_to_cpu(sbp->s_sum);
358 }
359
360 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
361 {
362         return offset < ((le64_to_cpu(sbp->s_nsegments) *
363                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
364                          (le32_to_cpu(sbp->s_log_block_size) + 10));
365 }
366
367 static void nilfs_release_super_block(struct the_nilfs *nilfs)
368 {
369         int i;
370
371         for (i = 0; i < 2; i++) {
372                 if (nilfs->ns_sbp[i]) {
373                         brelse(nilfs->ns_sbh[i]);
374                         nilfs->ns_sbh[i] = NULL;
375                         nilfs->ns_sbp[i] = NULL;
376                 }
377         }
378 }
379
380 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
381 {
382         brelse(nilfs->ns_sbh[0]);
383         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
384         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
385         nilfs->ns_sbh[1] = NULL;
386         nilfs->ns_sbp[1] = NULL;
387 }
388
389 void nilfs_swap_super_block(struct the_nilfs *nilfs)
390 {
391         struct buffer_head *tsbh = nilfs->ns_sbh[0];
392         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
393
394         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
395         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
396         nilfs->ns_sbh[1] = tsbh;
397         nilfs->ns_sbp[1] = tsbp;
398 }
399
400 static int nilfs_load_super_block(struct the_nilfs *nilfs,
401                                   struct super_block *sb, int blocksize,
402                                   struct nilfs_super_block **sbpp)
403 {
404         struct nilfs_super_block **sbp = nilfs->ns_sbp;
405         struct buffer_head **sbh = nilfs->ns_sbh;
406         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
407         int valid[2], swp = 0;
408
409         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
410                                         &sbh[0]);
411         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
412
413         if (!sbp[0]) {
414                 if (!sbp[1]) {
415                         printk(KERN_ERR "NILFS: unable to read superblock\n");
416                         return -EIO;
417                 }
418                 printk(KERN_WARNING
419                        "NILFS warning: unable to read primary superblock\n");
420         } else if (!sbp[1])
421                 printk(KERN_WARNING
422                        "NILFS warning: unable to read secondary superblock\n");
423
424         valid[0] = nilfs_valid_sb(sbp[0]);
425         valid[1] = nilfs_valid_sb(sbp[1]);
426         swp = valid[1] &&
427                 (!valid[0] ||
428                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
429
430         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
431                 brelse(sbh[1]);
432                 sbh[1] = NULL;
433                 sbp[1] = NULL;
434                 swp = 0;
435         }
436         if (!valid[swp]) {
437                 nilfs_release_super_block(nilfs);
438                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
439                        sb->s_id);
440                 return -EINVAL;
441         }
442
443         if (swp) {
444                 printk(KERN_WARNING "NILFS warning: broken superblock. "
445                        "using spare superblock.\n");
446                 nilfs_swap_super_block(nilfs);
447         }
448
449         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
450         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
451         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
452         *sbpp = sbp[0];
453         return 0;
454 }
455
456 /**
457  * init_nilfs - initialize a NILFS instance.
458  * @nilfs: the_nilfs structure
459  * @sbi: nilfs_sb_info
460  * @sb: super block
461  * @data: mount options
462  *
463  * init_nilfs() performs common initialization per block device (e.g.
464  * reading the super block, getting disk layout information, initializing
465  * shared fields in the_nilfs). It takes on some portion of the jobs
466  * typically done by a fill_super() routine. This division arises from
467  * the nature that multiple NILFS instances may be simultaneously
468  * mounted on a device.
469  * For multiple mounts on the same device, only the first mount
470  * invokes these tasks.
471  *
472  * Return Value: On success, 0 is returned. On error, a negative error
473  * code is returned.
474  */
475 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
476 {
477         struct super_block *sb = sbi->s_super;
478         struct nilfs_super_block *sbp;
479         struct backing_dev_info *bdi;
480         int blocksize;
481         int err;
482
483         down_write(&nilfs->ns_sem);
484         if (nilfs_init(nilfs)) {
485                 /* Load values from existing the_nilfs */
486                 sbp = nilfs->ns_sbp[0];
487                 err = nilfs_store_magic_and_option(sb, sbp, data);
488                 if (err)
489                         goto out;
490
491                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
492                 if (sb->s_blocksize != blocksize &&
493                     !sb_set_blocksize(sb, blocksize)) {
494                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
495                                blocksize);
496                         err = -EINVAL;
497                 }
498                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
499                 goto out;
500         }
501
502         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
503         if (!blocksize) {
504                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
505                 err = -EINVAL;
506                 goto out;
507         }
508         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
509         if (err)
510                 goto out;
511
512         err = nilfs_store_magic_and_option(sb, sbp, data);
513         if (err)
514                 goto failed_sbh;
515
516         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
517         if (sb->s_blocksize != blocksize) {
518                 int hw_blocksize = bdev_logical_block_size(sb->s_bdev);
519
520                 if (blocksize < hw_blocksize) {
521                         printk(KERN_ERR
522                                "NILFS: blocksize %d too small for device "
523                                "(sector-size = %d).\n",
524                                blocksize, hw_blocksize);
525                         err = -EINVAL;
526                         goto failed_sbh;
527                 }
528                 nilfs_release_super_block(nilfs);
529                 sb_set_blocksize(sb, blocksize);
530
531                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
532                 if (err)
533                         goto out;
534                         /* not failed_sbh; sbh is released automatically
535                            when reloading fails. */
536         }
537         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
538
539         err = nilfs_store_disk_layout(nilfs, sbp);
540         if (err)
541                 goto failed_sbh;
542
543         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
544
545         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
546
547         bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
548         if (!bdi)
549                 bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
550         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
551
552         /* Finding last segment */
553         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
554         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
555         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
556
557         nilfs->ns_seg_seq = nilfs->ns_last_seq;
558         nilfs->ns_segnum =
559                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
560         nilfs->ns_cno = nilfs->ns_last_cno + 1;
561         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
562                 printk(KERN_ERR "NILFS invalid last segment number.\n");
563                 err = -EINVAL;
564                 goto failed_sbh;
565         }
566         /* Dummy values  */
567         nilfs->ns_free_segments_count =
568                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
569
570         /* Initialize gcinode cache */
571         err = nilfs_init_gccache(nilfs);
572         if (err)
573                 goto failed_sbh;
574
575         set_nilfs_init(nilfs);
576         err = 0;
577  out:
578         up_write(&nilfs->ns_sem);
579         return err;
580
581  failed_sbh:
582         nilfs_release_super_block(nilfs);
583         goto out;
584 }
585
586 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
587 {
588         struct inode *dat = nilfs_dat_inode(nilfs);
589         unsigned long ncleansegs;
590         int err;
591
592         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
593         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
594         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
595         if (likely(!err))
596                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
597         return err;
598 }
599
600 int nilfs_near_disk_full(struct the_nilfs *nilfs)
601 {
602         struct inode *sufile = nilfs->ns_sufile;
603         unsigned long ncleansegs, nincsegs;
604         int ret;
605
606         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
607         if (likely(!ret)) {
608                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
609                         nilfs->ns_blocks_per_segment + 1;
610                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
611                         ret++;
612         }
613         return ret;
614 }
615
616 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
617                                 int snapshot_mount)
618 {
619         struct nilfs_sb_info *sbi;
620         int ret = 0;
621
622         down_read(&nilfs->ns_sem);
623         if (cno == 0 || cno > nilfs->ns_cno)
624                 goto out_unlock;
625
626         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
627                 if (sbi->s_snapshot_cno == cno &&
628                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
629                                         /* exclude read-only mounts */
630                         ret++;
631                         break;
632                 }
633         }
634         /* for protecting recent checkpoints */
635         if (cno >= nilfs_last_cno(nilfs))
636                 ret++;
637
638  out_unlock:
639         up_read(&nilfs->ns_sem);
640         return ret;
641 }