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