nilfs2: remove header file for segment list operations
[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 void nilfs_set_last_segment(struct the_nilfs *nilfs,
38                             sector_t start_blocknr, u64 seq, __u64 cno)
39 {
40         spin_lock(&nilfs->ns_last_segment_lock);
41         nilfs->ns_last_pseg = start_blocknr;
42         nilfs->ns_last_seq = seq;
43         nilfs->ns_last_cno = cno;
44         spin_unlock(&nilfs->ns_last_segment_lock);
45 }
46
47 /**
48  * alloc_nilfs - allocate the_nilfs structure
49  * @bdev: block device to which the_nilfs is related
50  *
51  * alloc_nilfs() allocates memory for the_nilfs and
52  * initializes its reference count and locks.
53  *
54  * Return Value: On success, pointer to the_nilfs is returned.
55  * On error, NULL is returned.
56  */
57 struct the_nilfs *alloc_nilfs(struct block_device *bdev)
58 {
59         struct the_nilfs *nilfs;
60
61         nilfs = kzalloc(sizeof(*nilfs), GFP_KERNEL);
62         if (!nilfs)
63                 return NULL;
64
65         nilfs->ns_bdev = bdev;
66         atomic_set(&nilfs->ns_count, 1);
67         atomic_set(&nilfs->ns_writer_refcount, -1);
68         atomic_set(&nilfs->ns_ndirtyblks, 0);
69         init_rwsem(&nilfs->ns_sem);
70         mutex_init(&nilfs->ns_writer_mutex);
71         INIT_LIST_HEAD(&nilfs->ns_supers);
72         spin_lock_init(&nilfs->ns_last_segment_lock);
73         nilfs->ns_gc_inodes_h = NULL;
74         init_rwsem(&nilfs->ns_segctor_sem);
75
76         return nilfs;
77 }
78
79 /**
80  * put_nilfs - release a reference to the_nilfs
81  * @nilfs: the_nilfs structure to be released
82  *
83  * put_nilfs() decrements a reference counter of the_nilfs.
84  * If the reference count reaches zero, the_nilfs is freed.
85  */
86 void put_nilfs(struct the_nilfs *nilfs)
87 {
88         if (!atomic_dec_and_test(&nilfs->ns_count))
89                 return;
90         /*
91          * Increment of ns_count never occur below because the caller
92          * of get_nilfs() holds at least one reference to the_nilfs.
93          * Thus its exclusion control is not required here.
94          */
95         might_sleep();
96         if (nilfs_loaded(nilfs)) {
97                 nilfs_mdt_clear(nilfs->ns_sufile);
98                 nilfs_mdt_destroy(nilfs->ns_sufile);
99                 nilfs_mdt_clear(nilfs->ns_cpfile);
100                 nilfs_mdt_destroy(nilfs->ns_cpfile);
101                 nilfs_mdt_clear(nilfs->ns_dat);
102                 nilfs_mdt_destroy(nilfs->ns_dat);
103                 /* XXX: how and when to clear nilfs->ns_gc_dat? */
104                 nilfs_mdt_destroy(nilfs->ns_gc_dat);
105         }
106         if (nilfs_init(nilfs)) {
107                 nilfs_destroy_gccache(nilfs);
108                 brelse(nilfs->ns_sbh[0]);
109                 brelse(nilfs->ns_sbh[1]);
110         }
111         kfree(nilfs);
112 }
113
114 static int nilfs_load_super_root(struct the_nilfs *nilfs,
115                                  struct nilfs_sb_info *sbi, sector_t sr_block)
116 {
117         static struct lock_class_key dat_lock_key;
118         struct buffer_head *bh_sr;
119         struct nilfs_super_root *raw_sr;
120         struct nilfs_super_block **sbp = nilfs->ns_sbp;
121         unsigned dat_entry_size, segment_usage_size, checkpoint_size;
122         unsigned inode_size;
123         int err;
124
125         err = nilfs_read_super_root_block(sbi->s_super, sr_block, &bh_sr, 1);
126         if (unlikely(err))
127                 return err;
128
129         down_read(&nilfs->ns_sem);
130         dat_entry_size = le16_to_cpu(sbp[0]->s_dat_entry_size);
131         checkpoint_size = le16_to_cpu(sbp[0]->s_checkpoint_size);
132         segment_usage_size = le16_to_cpu(sbp[0]->s_segment_usage_size);
133         up_read(&nilfs->ns_sem);
134
135         inode_size = nilfs->ns_inode_size;
136
137         err = -ENOMEM;
138         nilfs->ns_dat = nilfs_mdt_new(
139                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
140         if (unlikely(!nilfs->ns_dat))
141                 goto failed;
142
143         nilfs->ns_gc_dat = nilfs_mdt_new(
144                 nilfs, NULL, NILFS_DAT_INO, NILFS_DAT_GFP);
145         if (unlikely(!nilfs->ns_gc_dat))
146                 goto failed_dat;
147
148         nilfs->ns_cpfile = nilfs_mdt_new(
149                 nilfs, NULL, NILFS_CPFILE_INO, NILFS_CPFILE_GFP);
150         if (unlikely(!nilfs->ns_cpfile))
151                 goto failed_gc_dat;
152
153         nilfs->ns_sufile = nilfs_mdt_new(
154                 nilfs, NULL, NILFS_SUFILE_INO, NILFS_SUFILE_GFP);
155         if (unlikely(!nilfs->ns_sufile))
156                 goto failed_cpfile;
157
158         err = nilfs_palloc_init_blockgroup(nilfs->ns_dat, dat_entry_size);
159         if (unlikely(err))
160                 goto failed_sufile;
161
162         err = nilfs_palloc_init_blockgroup(nilfs->ns_gc_dat, dat_entry_size);
163         if (unlikely(err))
164                 goto failed_sufile;
165
166         lockdep_set_class(&NILFS_MDT(nilfs->ns_dat)->mi_sem, &dat_lock_key);
167         lockdep_set_class(&NILFS_MDT(nilfs->ns_gc_dat)->mi_sem, &dat_lock_key);
168
169         nilfs_mdt_set_shadow(nilfs->ns_dat, nilfs->ns_gc_dat);
170         nilfs_mdt_set_entry_size(nilfs->ns_cpfile, checkpoint_size,
171                                  sizeof(struct nilfs_cpfile_header));
172         nilfs_mdt_set_entry_size(nilfs->ns_sufile, segment_usage_size,
173                                  sizeof(struct nilfs_sufile_header));
174
175         err = nilfs_mdt_read_inode_direct(
176                 nilfs->ns_dat, bh_sr, NILFS_SR_DAT_OFFSET(inode_size));
177         if (unlikely(err))
178                 goto failed_sufile;
179
180         err = nilfs_mdt_read_inode_direct(
181                 nilfs->ns_cpfile, bh_sr, NILFS_SR_CPFILE_OFFSET(inode_size));
182         if (unlikely(err))
183                 goto failed_sufile;
184
185         err = nilfs_mdt_read_inode_direct(
186                 nilfs->ns_sufile, bh_sr, NILFS_SR_SUFILE_OFFSET(inode_size));
187         if (unlikely(err))
188                 goto failed_sufile;
189
190         raw_sr = (struct nilfs_super_root *)bh_sr->b_data;
191         nilfs->ns_nongc_ctime = le64_to_cpu(raw_sr->sr_nongc_ctime);
192
193  failed:
194         brelse(bh_sr);
195         return err;
196
197  failed_sufile:
198         nilfs_mdt_destroy(nilfs->ns_sufile);
199
200  failed_cpfile:
201         nilfs_mdt_destroy(nilfs->ns_cpfile);
202
203  failed_gc_dat:
204         nilfs_mdt_destroy(nilfs->ns_gc_dat);
205
206  failed_dat:
207         nilfs_mdt_destroy(nilfs->ns_dat);
208         goto failed;
209 }
210
211 static void nilfs_init_recovery_info(struct nilfs_recovery_info *ri)
212 {
213         memset(ri, 0, sizeof(*ri));
214         INIT_LIST_HEAD(&ri->ri_used_segments);
215 }
216
217 static void nilfs_clear_recovery_info(struct nilfs_recovery_info *ri)
218 {
219         nilfs_dispose_segment_list(&ri->ri_used_segments);
220 }
221
222 /**
223  * load_nilfs - load and recover the nilfs
224  * @nilfs: the_nilfs structure to be released
225  * @sbi: nilfs_sb_info used to recover past segment
226  *
227  * load_nilfs() searches and load the latest super root,
228  * attaches the last segment, and does recovery if needed.
229  * The caller must call this exclusively for simultaneous mounts.
230  */
231 int load_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi)
232 {
233         struct nilfs_recovery_info ri;
234         unsigned int s_flags = sbi->s_super->s_flags;
235         int really_read_only = bdev_read_only(nilfs->ns_bdev);
236         unsigned valid_fs;
237         int err = 0;
238
239         nilfs_init_recovery_info(&ri);
240
241         down_write(&nilfs->ns_sem);
242         valid_fs = (nilfs->ns_mount_state & NILFS_VALID_FS);
243         up_write(&nilfs->ns_sem);
244
245         if (!valid_fs && (s_flags & MS_RDONLY)) {
246                 printk(KERN_INFO "NILFS: INFO: recovery "
247                        "required for readonly filesystem.\n");
248                 if (really_read_only) {
249                         printk(KERN_ERR "NILFS: write access "
250                                "unavailable, cannot proceed.\n");
251                         err = -EROFS;
252                         goto failed;
253                 }
254                 printk(KERN_INFO "NILFS: write access will "
255                        "be enabled during recovery.\n");
256                 sbi->s_super->s_flags &= ~MS_RDONLY;
257         }
258
259         err = nilfs_search_super_root(nilfs, sbi, &ri);
260         if (unlikely(err)) {
261                 printk(KERN_ERR "NILFS: error searching super root.\n");
262                 goto failed;
263         }
264
265         err = nilfs_load_super_root(nilfs, sbi, ri.ri_super_root);
266         if (unlikely(err)) {
267                 printk(KERN_ERR "NILFS: error loading super root.\n");
268                 goto failed;
269         }
270
271         if (!valid_fs) {
272                 err = nilfs_recover_logical_segments(nilfs, sbi, &ri);
273                 if (unlikely(err)) {
274                         nilfs_mdt_destroy(nilfs->ns_cpfile);
275                         nilfs_mdt_destroy(nilfs->ns_sufile);
276                         nilfs_mdt_destroy(nilfs->ns_dat);
277                         goto failed;
278                 }
279                 if (ri.ri_need_recovery == NILFS_RECOVERY_SR_UPDATED)
280                         sbi->s_super->s_dirt = 1;
281         }
282
283         set_nilfs_loaded(nilfs);
284
285  failed:
286         nilfs_clear_recovery_info(&ri);
287         sbi->s_super->s_flags = s_flags;
288         return err;
289 }
290
291 static unsigned long long nilfs_max_size(unsigned int blkbits)
292 {
293         unsigned int max_bits;
294         unsigned long long res = MAX_LFS_FILESIZE; /* page cache limit */
295
296         max_bits = blkbits + NILFS_BMAP_KEY_BIT; /* bmap size limit */
297         if (max_bits < 64)
298                 res = min_t(unsigned long long, res, (1ULL << max_bits) - 1);
299         return res;
300 }
301
302 static int nilfs_store_disk_layout(struct the_nilfs *nilfs,
303                                    struct nilfs_super_block *sbp)
304 {
305         if (le32_to_cpu(sbp->s_rev_level) != NILFS_CURRENT_REV) {
306                 printk(KERN_ERR "NILFS: revision mismatch "
307                        "(superblock rev.=%d.%d, current rev.=%d.%d). "
308                        "Please check the version of mkfs.nilfs.\n",
309                        le32_to_cpu(sbp->s_rev_level),
310                        le16_to_cpu(sbp->s_minor_rev_level),
311                        NILFS_CURRENT_REV, NILFS_MINOR_REV);
312                 return -EINVAL;
313         }
314         nilfs->ns_sbsize = le16_to_cpu(sbp->s_bytes);
315         if (nilfs->ns_sbsize > BLOCK_SIZE)
316                 return -EINVAL;
317
318         nilfs->ns_inode_size = le16_to_cpu(sbp->s_inode_size);
319         nilfs->ns_first_ino = le32_to_cpu(sbp->s_first_ino);
320
321         nilfs->ns_blocks_per_segment = le32_to_cpu(sbp->s_blocks_per_segment);
322         if (nilfs->ns_blocks_per_segment < NILFS_SEG_MIN_BLOCKS) {
323                 printk(KERN_ERR "NILFS: too short segment. \n");
324                 return -EINVAL;
325         }
326
327         nilfs->ns_first_data_block = le64_to_cpu(sbp->s_first_data_block);
328         nilfs->ns_nsegments = le64_to_cpu(sbp->s_nsegments);
329         nilfs->ns_r_segments_percentage =
330                 le32_to_cpu(sbp->s_r_segments_percentage);
331         nilfs->ns_nrsvsegs =
332                 max_t(unsigned long, NILFS_MIN_NRSVSEGS,
333                       DIV_ROUND_UP(nilfs->ns_nsegments *
334                                    nilfs->ns_r_segments_percentage, 100));
335         nilfs->ns_crc_seed = le32_to_cpu(sbp->s_crc_seed);
336         return 0;
337 }
338
339 static int nilfs_valid_sb(struct nilfs_super_block *sbp)
340 {
341         static unsigned char sum[4];
342         const int sumoff = offsetof(struct nilfs_super_block, s_sum);
343         size_t bytes;
344         u32 crc;
345
346         if (!sbp || le16_to_cpu(sbp->s_magic) != NILFS_SUPER_MAGIC)
347                 return 0;
348         bytes = le16_to_cpu(sbp->s_bytes);
349         if (bytes > BLOCK_SIZE)
350                 return 0;
351         crc = crc32_le(le32_to_cpu(sbp->s_crc_seed), (unsigned char *)sbp,
352                        sumoff);
353         crc = crc32_le(crc, sum, 4);
354         crc = crc32_le(crc, (unsigned char *)sbp + sumoff + 4,
355                        bytes - sumoff - 4);
356         return crc == le32_to_cpu(sbp->s_sum);
357 }
358
359 static int nilfs_sb2_bad_offset(struct nilfs_super_block *sbp, u64 offset)
360 {
361         return offset < ((le64_to_cpu(sbp->s_nsegments) *
362                           le32_to_cpu(sbp->s_blocks_per_segment)) <<
363                          (le32_to_cpu(sbp->s_log_block_size) + 10));
364 }
365
366 static void nilfs_release_super_block(struct the_nilfs *nilfs)
367 {
368         int i;
369
370         for (i = 0; i < 2; i++) {
371                 if (nilfs->ns_sbp[i]) {
372                         brelse(nilfs->ns_sbh[i]);
373                         nilfs->ns_sbh[i] = NULL;
374                         nilfs->ns_sbp[i] = NULL;
375                 }
376         }
377 }
378
379 void nilfs_fall_back_super_block(struct the_nilfs *nilfs)
380 {
381         brelse(nilfs->ns_sbh[0]);
382         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
383         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
384         nilfs->ns_sbh[1] = NULL;
385         nilfs->ns_sbp[1] = NULL;
386 }
387
388 void nilfs_swap_super_block(struct the_nilfs *nilfs)
389 {
390         struct buffer_head *tsbh = nilfs->ns_sbh[0];
391         struct nilfs_super_block *tsbp = nilfs->ns_sbp[0];
392
393         nilfs->ns_sbh[0] = nilfs->ns_sbh[1];
394         nilfs->ns_sbp[0] = nilfs->ns_sbp[1];
395         nilfs->ns_sbh[1] = tsbh;
396         nilfs->ns_sbp[1] = tsbp;
397 }
398
399 static int nilfs_load_super_block(struct the_nilfs *nilfs,
400                                   struct super_block *sb, int blocksize,
401                                   struct nilfs_super_block **sbpp)
402 {
403         struct nilfs_super_block **sbp = nilfs->ns_sbp;
404         struct buffer_head **sbh = nilfs->ns_sbh;
405         u64 sb2off = NILFS_SB2_OFFSET_BYTES(nilfs->ns_bdev->bd_inode->i_size);
406         int valid[2], swp = 0;
407
408         sbp[0] = nilfs_read_super_block(sb, NILFS_SB_OFFSET_BYTES, blocksize,
409                                         &sbh[0]);
410         sbp[1] = nilfs_read_super_block(sb, sb2off, blocksize, &sbh[1]);
411
412         if (!sbp[0]) {
413                 if (!sbp[1]) {
414                         printk(KERN_ERR "NILFS: unable to read superblock\n");
415                         return -EIO;
416                 }
417                 printk(KERN_WARNING
418                        "NILFS warning: unable to read primary superblock\n");
419         } else if (!sbp[1])
420                 printk(KERN_WARNING
421                        "NILFS warning: unable to read secondary superblock\n");
422
423         valid[0] = nilfs_valid_sb(sbp[0]);
424         valid[1] = nilfs_valid_sb(sbp[1]);
425         swp = valid[1] &&
426                 (!valid[0] ||
427                  le64_to_cpu(sbp[1]->s_wtime) > le64_to_cpu(sbp[0]->s_wtime));
428
429         if (valid[swp] && nilfs_sb2_bad_offset(sbp[swp], sb2off)) {
430                 brelse(sbh[1]);
431                 sbh[1] = NULL;
432                 sbp[1] = NULL;
433                 swp = 0;
434         }
435         if (!valid[swp]) {
436                 nilfs_release_super_block(nilfs);
437                 printk(KERN_ERR "NILFS: Can't find nilfs on dev %s.\n",
438                        sb->s_id);
439                 return -EINVAL;
440         }
441
442         if (swp) {
443                 printk(KERN_WARNING "NILFS warning: broken superblock. "
444                        "using spare superblock.\n");
445                 nilfs_swap_super_block(nilfs);
446         }
447
448         nilfs->ns_sbwtime[0] = le64_to_cpu(sbp[0]->s_wtime);
449         nilfs->ns_sbwtime[1] = valid[!swp] ? le64_to_cpu(sbp[1]->s_wtime) : 0;
450         nilfs->ns_prot_seq = le64_to_cpu(sbp[valid[1] & !swp]->s_last_seq);
451         *sbpp = sbp[0];
452         return 0;
453 }
454
455 /**
456  * init_nilfs - initialize a NILFS instance.
457  * @nilfs: the_nilfs structure
458  * @sbi: nilfs_sb_info
459  * @sb: super block
460  * @data: mount options
461  *
462  * init_nilfs() performs common initialization per block device (e.g.
463  * reading the super block, getting disk layout information, initializing
464  * shared fields in the_nilfs). It takes on some portion of the jobs
465  * typically done by a fill_super() routine. This division arises from
466  * the nature that multiple NILFS instances may be simultaneously
467  * mounted on a device.
468  * For multiple mounts on the same device, only the first mount
469  * invokes these tasks.
470  *
471  * Return Value: On success, 0 is returned. On error, a negative error
472  * code is returned.
473  */
474 int init_nilfs(struct the_nilfs *nilfs, struct nilfs_sb_info *sbi, char *data)
475 {
476         struct super_block *sb = sbi->s_super;
477         struct nilfs_super_block *sbp;
478         struct backing_dev_info *bdi;
479         int blocksize;
480         int err;
481
482         down_write(&nilfs->ns_sem);
483         if (nilfs_init(nilfs)) {
484                 /* Load values from existing the_nilfs */
485                 sbp = nilfs->ns_sbp[0];
486                 err = nilfs_store_magic_and_option(sb, sbp, data);
487                 if (err)
488                         goto out;
489
490                 blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
491                 if (sb->s_blocksize != blocksize &&
492                     !sb_set_blocksize(sb, blocksize)) {
493                         printk(KERN_ERR "NILFS: blocksize %d unfit to device\n",
494                                blocksize);
495                         err = -EINVAL;
496                 }
497                 sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
498                 goto out;
499         }
500
501         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
502         if (!blocksize) {
503                 printk(KERN_ERR "NILFS: unable to set blocksize\n");
504                 err = -EINVAL;
505                 goto out;
506         }
507         err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
508         if (err)
509                 goto out;
510
511         err = nilfs_store_magic_and_option(sb, sbp, data);
512         if (err)
513                 goto failed_sbh;
514
515         blocksize = BLOCK_SIZE << le32_to_cpu(sbp->s_log_block_size);
516         if (sb->s_blocksize != blocksize) {
517                 int hw_blocksize = bdev_hardsect_size(sb->s_bdev);
518
519                 if (blocksize < hw_blocksize) {
520                         printk(KERN_ERR
521                                "NILFS: blocksize %d too small for device "
522                                "(sector-size = %d).\n",
523                                blocksize, hw_blocksize);
524                         err = -EINVAL;
525                         goto failed_sbh;
526                 }
527                 nilfs_release_super_block(nilfs);
528                 sb_set_blocksize(sb, blocksize);
529
530                 err = nilfs_load_super_block(nilfs, sb, blocksize, &sbp);
531                 if (err)
532                         goto out;
533                         /* not failed_sbh; sbh is released automatically
534                            when reloading fails. */
535         }
536         nilfs->ns_blocksize_bits = sb->s_blocksize_bits;
537
538         err = nilfs_store_disk_layout(nilfs, sbp);
539         if (err)
540                 goto failed_sbh;
541
542         sb->s_maxbytes = nilfs_max_size(sb->s_blocksize_bits);
543
544         nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
545
546         bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
547         if (!bdi)
548                 bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
549         nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
550
551         /* Finding last segment */
552         nilfs->ns_last_pseg = le64_to_cpu(sbp->s_last_pseg);
553         nilfs->ns_last_cno = le64_to_cpu(sbp->s_last_cno);
554         nilfs->ns_last_seq = le64_to_cpu(sbp->s_last_seq);
555
556         nilfs->ns_seg_seq = nilfs->ns_last_seq;
557         nilfs->ns_segnum =
558                 nilfs_get_segnum_of_block(nilfs, nilfs->ns_last_pseg);
559         nilfs->ns_cno = nilfs->ns_last_cno + 1;
560         if (nilfs->ns_segnum >= nilfs->ns_nsegments) {
561                 printk(KERN_ERR "NILFS invalid last segment number.\n");
562                 err = -EINVAL;
563                 goto failed_sbh;
564         }
565         /* Dummy values  */
566         nilfs->ns_free_segments_count =
567                 nilfs->ns_nsegments - (nilfs->ns_segnum + 1);
568
569         /* Initialize gcinode cache */
570         err = nilfs_init_gccache(nilfs);
571         if (err)
572                 goto failed_sbh;
573
574         set_nilfs_init(nilfs);
575         err = 0;
576  out:
577         up_write(&nilfs->ns_sem);
578         return err;
579
580  failed_sbh:
581         nilfs_release_super_block(nilfs);
582         goto out;
583 }
584
585 int nilfs_count_free_blocks(struct the_nilfs *nilfs, sector_t *nblocks)
586 {
587         struct inode *dat = nilfs_dat_inode(nilfs);
588         unsigned long ncleansegs;
589         int err;
590
591         down_read(&NILFS_MDT(dat)->mi_sem);     /* XXX */
592         err = nilfs_sufile_get_ncleansegs(nilfs->ns_sufile, &ncleansegs);
593         up_read(&NILFS_MDT(dat)->mi_sem);       /* XXX */
594         if (likely(!err))
595                 *nblocks = (sector_t)ncleansegs * nilfs->ns_blocks_per_segment;
596         return err;
597 }
598
599 int nilfs_near_disk_full(struct the_nilfs *nilfs)
600 {
601         struct inode *sufile = nilfs->ns_sufile;
602         unsigned long ncleansegs, nincsegs;
603         int ret;
604
605         ret = nilfs_sufile_get_ncleansegs(sufile, &ncleansegs);
606         if (likely(!ret)) {
607                 nincsegs = atomic_read(&nilfs->ns_ndirtyblks) /
608                         nilfs->ns_blocks_per_segment + 1;
609                 if (ncleansegs <= nilfs->ns_nrsvsegs + nincsegs)
610                         ret++;
611         }
612         return ret;
613 }
614
615 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
616                                 int snapshot_mount)
617 {
618         struct nilfs_sb_info *sbi;
619         int ret = 0;
620
621         down_read(&nilfs->ns_sem);
622         if (cno == 0 || cno > nilfs->ns_cno)
623                 goto out_unlock;
624
625         list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
626                 if (sbi->s_snapshot_cno == cno &&
627                     (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
628                                         /* exclude read-only mounts */
629                         ret++;
630                         break;
631                 }
632         }
633         /* for protecting recent checkpoints */
634         if (cno >= nilfs_last_cno(nilfs))
635                 ret++;
636
637  out_unlock:
638         up_read(&nilfs->ns_sem);
639         return ret;
640 }