f804d41ec9d3b2e253972beed4ecda1fc2daf2b9
[linux-2.6.git] / fs / nilfs2 / super.c
1 /*
2  * super.c - NILFS module and super block management.
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  *  linux/fs/ext2/super.c
24  *
25  * Copyright (C) 1992, 1993, 1994, 1995
26  * Remy Card (card@masi.ibp.fr)
27  * Laboratoire MASI - Institut Blaise Pascal
28  * Universite Pierre et Marie Curie (Paris VI)
29  *
30  *  from
31  *
32  *  linux/fs/minix/inode.c
33  *
34  *  Copyright (C) 1991, 1992  Linus Torvalds
35  *
36  *  Big-endian to little-endian byte-swapping/bitmaps by
37  *        David S. Miller (davem@caip.rutgers.edu), 1995
38  */
39
40 #include <linux/module.h>
41 #include <linux/string.h>
42 #include <linux/slab.h>
43 #include <linux/init.h>
44 #include <linux/blkdev.h>
45 #include <linux/parser.h>
46 #include <linux/random.h>
47 #include <linux/crc32.h>
48 #include <linux/vfs.h>
49 #include <linux/writeback.h>
50 #include <linux/kobject.h>
51 #include <linux/seq_file.h>
52 #include <linux/mount.h>
53 #include "nilfs.h"
54 #include "export.h"
55 #include "mdt.h"
56 #include "alloc.h"
57 #include "btree.h"
58 #include "btnode.h"
59 #include "page.h"
60 #include "cpfile.h"
61 #include "ifile.h"
62 #include "dat.h"
63 #include "segment.h"
64 #include "segbuf.h"
65
66 MODULE_AUTHOR("NTT Corp.");
67 MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
68                    "(NILFS)");
69 MODULE_LICENSE("GPL");
70
71 static struct kmem_cache *nilfs_inode_cachep;
72 struct kmem_cache *nilfs_transaction_cachep;
73 struct kmem_cache *nilfs_segbuf_cachep;
74 struct kmem_cache *nilfs_btree_path_cache;
75
76 static int nilfs_setup_super(struct nilfs_sb_info *sbi, int is_mount);
77 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
78
79 static void nilfs_set_error(struct nilfs_sb_info *sbi)
80 {
81         struct the_nilfs *nilfs = sbi->s_nilfs;
82         struct nilfs_super_block **sbp;
83
84         down_write(&nilfs->ns_sem);
85         if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
86                 nilfs->ns_mount_state |= NILFS_ERROR_FS;
87                 sbp = nilfs_prepare_super(sbi, 0);
88                 if (likely(sbp)) {
89                         sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
90                         if (sbp[1])
91                                 sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
92                         nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL);
93                 }
94         }
95         up_write(&nilfs->ns_sem);
96 }
97
98 /**
99  * nilfs_error() - report failure condition on a filesystem
100  *
101  * nilfs_error() sets an ERROR_FS flag on the superblock as well as
102  * reporting an error message.  It should be called when NILFS detects
103  * incoherences or defects of meta data on disk.  As for sustainable
104  * errors such as a single-shot I/O error, nilfs_warning() or the printk()
105  * function should be used instead.
106  *
107  * The segment constructor must not call this function because it can
108  * kill itself.
109  */
110 void nilfs_error(struct super_block *sb, const char *function,
111                  const char *fmt, ...)
112 {
113         struct nilfs_sb_info *sbi = NILFS_SB(sb);
114         va_list args;
115
116         va_start(args, fmt);
117         printk(KERN_CRIT "NILFS error (device %s): %s: ", sb->s_id, function);
118         vprintk(fmt, args);
119         printk("\n");
120         va_end(args);
121
122         if (!(sb->s_flags & MS_RDONLY)) {
123                 nilfs_set_error(sbi);
124
125                 if (nilfs_test_opt(sbi, ERRORS_RO)) {
126                         printk(KERN_CRIT "Remounting filesystem read-only\n");
127                         sb->s_flags |= MS_RDONLY;
128                 }
129         }
130
131         if (nilfs_test_opt(sbi, ERRORS_PANIC))
132                 panic("NILFS (device %s): panic forced after error\n",
133                       sb->s_id);
134 }
135
136 void nilfs_warning(struct super_block *sb, const char *function,
137                    const char *fmt, ...)
138 {
139         va_list args;
140
141         va_start(args, fmt);
142         printk(KERN_WARNING "NILFS warning (device %s): %s: ",
143                sb->s_id, function);
144         vprintk(fmt, args);
145         printk("\n");
146         va_end(args);
147 }
148
149
150 struct inode *nilfs_alloc_inode(struct super_block *sb)
151 {
152         struct nilfs_inode_info *ii;
153
154         ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
155         if (!ii)
156                 return NULL;
157         ii->i_bh = NULL;
158         ii->i_state = 0;
159         ii->i_cno = 0;
160         ii->vfs_inode.i_version = 1;
161         nilfs_btnode_cache_init(&ii->i_btnode_cache, sb->s_bdi);
162         return &ii->vfs_inode;
163 }
164
165 void nilfs_destroy_inode(struct inode *inode)
166 {
167         struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
168
169         if (mdi) {
170                 kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
171                 kfree(mdi);
172         }
173         kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
174 }
175
176 static int nilfs_sync_super(struct nilfs_sb_info *sbi, int flag)
177 {
178         struct the_nilfs *nilfs = sbi->s_nilfs;
179         int err;
180
181  retry:
182         set_buffer_dirty(nilfs->ns_sbh[0]);
183         if (nilfs_test_opt(sbi, BARRIER)) {
184                 err = __sync_dirty_buffer(nilfs->ns_sbh[0],
185                                           WRITE_SYNC | WRITE_FLUSH_FUA);
186         } else {
187                 err = sync_dirty_buffer(nilfs->ns_sbh[0]);
188         }
189
190         if (unlikely(err)) {
191                 printk(KERN_ERR
192                        "NILFS: unable to write superblock (err=%d)\n", err);
193                 if (err == -EIO && nilfs->ns_sbh[1]) {
194                         /*
195                          * sbp[0] points to newer log than sbp[1],
196                          * so copy sbp[0] to sbp[1] to take over sbp[0].
197                          */
198                         memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
199                                nilfs->ns_sbsize);
200                         nilfs_fall_back_super_block(nilfs);
201                         goto retry;
202                 }
203         } else {
204                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
205
206                 nilfs->ns_sbwcount++;
207
208                 /*
209                  * The latest segment becomes trailable from the position
210                  * written in superblock.
211                  */
212                 clear_nilfs_discontinued(nilfs);
213
214                 /* update GC protection for recent segments */
215                 if (nilfs->ns_sbh[1]) {
216                         if (flag == NILFS_SB_COMMIT_ALL) {
217                                 set_buffer_dirty(nilfs->ns_sbh[1]);
218                                 if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
219                                         goto out;
220                         }
221                         if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
222                             le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
223                                 sbp = nilfs->ns_sbp[1];
224                 }
225
226                 spin_lock(&nilfs->ns_last_segment_lock);
227                 nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
228                 spin_unlock(&nilfs->ns_last_segment_lock);
229         }
230  out:
231         return err;
232 }
233
234 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
235                           struct the_nilfs *nilfs)
236 {
237         sector_t nfreeblocks;
238
239         /* nilfs->ns_sem must be locked by the caller. */
240         nilfs_count_free_blocks(nilfs, &nfreeblocks);
241         sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
242
243         spin_lock(&nilfs->ns_last_segment_lock);
244         sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
245         sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
246         sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
247         spin_unlock(&nilfs->ns_last_segment_lock);
248 }
249
250 struct nilfs_super_block **nilfs_prepare_super(struct nilfs_sb_info *sbi,
251                                                int flip)
252 {
253         struct the_nilfs *nilfs = sbi->s_nilfs;
254         struct nilfs_super_block **sbp = nilfs->ns_sbp;
255
256         /* nilfs->ns_sem must be locked by the caller. */
257         if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
258                 if (sbp[1] &&
259                     sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
260                         memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
261                 } else {
262                         printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
263                                sbi->s_super->s_id);
264                         return NULL;
265                 }
266         } else if (sbp[1] &&
267                    sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
268                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
269         }
270
271         if (flip && sbp[1])
272                 nilfs_swap_super_block(nilfs);
273
274         return sbp;
275 }
276
277 int nilfs_commit_super(struct nilfs_sb_info *sbi, int flag)
278 {
279         struct the_nilfs *nilfs = sbi->s_nilfs;
280         struct nilfs_super_block **sbp = nilfs->ns_sbp;
281         time_t t;
282
283         /* nilfs->ns_sem must be locked by the caller. */
284         t = get_seconds();
285         nilfs->ns_sbwtime = t;
286         sbp[0]->s_wtime = cpu_to_le64(t);
287         sbp[0]->s_sum = 0;
288         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
289                                              (unsigned char *)sbp[0],
290                                              nilfs->ns_sbsize));
291         if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
292                 sbp[1]->s_wtime = sbp[0]->s_wtime;
293                 sbp[1]->s_sum = 0;
294                 sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
295                                             (unsigned char *)sbp[1],
296                                             nilfs->ns_sbsize));
297         }
298         clear_nilfs_sb_dirty(nilfs);
299         return nilfs_sync_super(sbi, flag);
300 }
301
302 /**
303  * nilfs_cleanup_super() - write filesystem state for cleanup
304  * @sbi: nilfs_sb_info to be unmounted or degraded to read-only
305  *
306  * This function restores state flags in the on-disk super block.
307  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
308  * filesystem was not clean previously.
309  */
310 int nilfs_cleanup_super(struct nilfs_sb_info *sbi)
311 {
312         struct nilfs_super_block **sbp;
313         int flag = NILFS_SB_COMMIT;
314         int ret = -EIO;
315
316         sbp = nilfs_prepare_super(sbi, 0);
317         if (sbp) {
318                 sbp[0]->s_state = cpu_to_le16(sbi->s_nilfs->ns_mount_state);
319                 nilfs_set_log_cursor(sbp[0], sbi->s_nilfs);
320                 if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
321                         /*
322                          * make the "clean" flag also to the opposite
323                          * super block if both super blocks point to
324                          * the same checkpoint.
325                          */
326                         sbp[1]->s_state = sbp[0]->s_state;
327                         flag = NILFS_SB_COMMIT_ALL;
328                 }
329                 ret = nilfs_commit_super(sbi, flag);
330         }
331         return ret;
332 }
333
334 static void nilfs_put_super(struct super_block *sb)
335 {
336         struct nilfs_sb_info *sbi = NILFS_SB(sb);
337         struct the_nilfs *nilfs = sbi->s_nilfs;
338
339         nilfs_detach_segment_constructor(sbi);
340
341         if (!(sb->s_flags & MS_RDONLY)) {
342                 down_write(&nilfs->ns_sem);
343                 nilfs_cleanup_super(sbi);
344                 up_write(&nilfs->ns_sem);
345         }
346
347         iput(nilfs->ns_sufile);
348         iput(nilfs->ns_cpfile);
349         iput(nilfs->ns_dat);
350
351         destroy_nilfs(nilfs);
352         sbi->s_super = NULL;
353         sb->s_fs_info = NULL;
354         kfree(sbi);
355 }
356
357 static int nilfs_sync_fs(struct super_block *sb, int wait)
358 {
359         struct nilfs_sb_info *sbi = NILFS_SB(sb);
360         struct the_nilfs *nilfs = sbi->s_nilfs;
361         struct nilfs_super_block **sbp;
362         int err = 0;
363
364         /* This function is called when super block should be written back */
365         if (wait)
366                 err = nilfs_construct_segment(sb);
367
368         down_write(&nilfs->ns_sem);
369         if (nilfs_sb_dirty(nilfs)) {
370                 sbp = nilfs_prepare_super(sbi, nilfs_sb_will_flip(nilfs));
371                 if (likely(sbp)) {
372                         nilfs_set_log_cursor(sbp[0], nilfs);
373                         nilfs_commit_super(sbi, NILFS_SB_COMMIT);
374                 }
375         }
376         up_write(&nilfs->ns_sem);
377
378         return err;
379 }
380
381 int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno, int curr_mnt,
382                             struct nilfs_root **rootp)
383 {
384         struct the_nilfs *nilfs = sbi->s_nilfs;
385         struct nilfs_root *root;
386         struct nilfs_checkpoint *raw_cp;
387         struct buffer_head *bh_cp;
388         int err = -ENOMEM;
389
390         root = nilfs_find_or_create_root(
391                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
392         if (!root)
393                 return err;
394
395         if (root->ifile)
396                 goto reuse; /* already attached checkpoint */
397
398         down_read(&nilfs->ns_segctor_sem);
399         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
400                                           &bh_cp);
401         up_read(&nilfs->ns_segctor_sem);
402         if (unlikely(err)) {
403                 if (err == -ENOENT || err == -EINVAL) {
404                         printk(KERN_ERR
405                                "NILFS: Invalid checkpoint "
406                                "(checkpoint number=%llu)\n",
407                                (unsigned long long)cno);
408                         err = -EINVAL;
409                 }
410                 goto failed;
411         }
412
413         err = nilfs_ifile_read(sbi->s_super, root, nilfs->ns_inode_size,
414                                &raw_cp->cp_ifile_inode, &root->ifile);
415         if (err)
416                 goto failed_bh;
417
418         atomic_set(&root->inodes_count, le64_to_cpu(raw_cp->cp_inodes_count));
419         atomic_set(&root->blocks_count, le64_to_cpu(raw_cp->cp_blocks_count));
420
421         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
422
423  reuse:
424         *rootp = root;
425         return 0;
426
427  failed_bh:
428         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
429  failed:
430         nilfs_put_root(root);
431
432         return err;
433 }
434
435 static int nilfs_freeze(struct super_block *sb)
436 {
437         struct nilfs_sb_info *sbi = NILFS_SB(sb);
438         struct the_nilfs *nilfs = sbi->s_nilfs;
439         int err;
440
441         if (sb->s_flags & MS_RDONLY)
442                 return 0;
443
444         /* Mark super block clean */
445         down_write(&nilfs->ns_sem);
446         err = nilfs_cleanup_super(sbi);
447         up_write(&nilfs->ns_sem);
448         return err;
449 }
450
451 static int nilfs_unfreeze(struct super_block *sb)
452 {
453         struct nilfs_sb_info *sbi = NILFS_SB(sb);
454         struct the_nilfs *nilfs = sbi->s_nilfs;
455
456         if (sb->s_flags & MS_RDONLY)
457                 return 0;
458
459         down_write(&nilfs->ns_sem);
460         nilfs_setup_super(sbi, false);
461         up_write(&nilfs->ns_sem);
462         return 0;
463 }
464
465 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
466 {
467         struct super_block *sb = dentry->d_sb;
468         struct nilfs_root *root = NILFS_I(dentry->d_inode)->i_root;
469         struct the_nilfs *nilfs = root->nilfs;
470         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
471         unsigned long long blocks;
472         unsigned long overhead;
473         unsigned long nrsvblocks;
474         sector_t nfreeblocks;
475         int err;
476
477         /*
478          * Compute all of the segment blocks
479          *
480          * The blocks before first segment and after last segment
481          * are excluded.
482          */
483         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
484                 - nilfs->ns_first_data_block;
485         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
486
487         /*
488          * Compute the overhead
489          *
490          * When distributing meta data blocks outside segment structure,
491          * We must count them as the overhead.
492          */
493         overhead = 0;
494
495         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
496         if (unlikely(err))
497                 return err;
498
499         buf->f_type = NILFS_SUPER_MAGIC;
500         buf->f_bsize = sb->s_blocksize;
501         buf->f_blocks = blocks - overhead;
502         buf->f_bfree = nfreeblocks;
503         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
504                 (buf->f_bfree - nrsvblocks) : 0;
505         buf->f_files = atomic_read(&root->inodes_count);
506         buf->f_ffree = 0; /* nilfs_count_free_inodes(sb); */
507         buf->f_namelen = NILFS_NAME_LEN;
508         buf->f_fsid.val[0] = (u32)id;
509         buf->f_fsid.val[1] = (u32)(id >> 32);
510
511         return 0;
512 }
513
514 static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
515 {
516         struct super_block *sb = vfs->mnt_sb;
517         struct nilfs_sb_info *sbi = NILFS_SB(sb);
518         struct nilfs_root *root = NILFS_I(vfs->mnt_root->d_inode)->i_root;
519
520         if (!nilfs_test_opt(sbi, BARRIER))
521                 seq_puts(seq, ",nobarrier");
522         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
523                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
524         if (nilfs_test_opt(sbi, ERRORS_PANIC))
525                 seq_puts(seq, ",errors=panic");
526         if (nilfs_test_opt(sbi, ERRORS_CONT))
527                 seq_puts(seq, ",errors=continue");
528         if (nilfs_test_opt(sbi, STRICT_ORDER))
529                 seq_puts(seq, ",order=strict");
530         if (nilfs_test_opt(sbi, NORECOVERY))
531                 seq_puts(seq, ",norecovery");
532         if (nilfs_test_opt(sbi, DISCARD))
533                 seq_puts(seq, ",discard");
534
535         return 0;
536 }
537
538 static const struct super_operations nilfs_sops = {
539         .alloc_inode    = nilfs_alloc_inode,
540         .destroy_inode  = nilfs_destroy_inode,
541         .dirty_inode    = nilfs_dirty_inode,
542         /* .write_inode    = nilfs_write_inode, */
543         /* .put_inode      = nilfs_put_inode, */
544         /* .drop_inode    = nilfs_drop_inode, */
545         .evict_inode    = nilfs_evict_inode,
546         .put_super      = nilfs_put_super,
547         /* .write_super    = nilfs_write_super, */
548         .sync_fs        = nilfs_sync_fs,
549         .freeze_fs      = nilfs_freeze,
550         .unfreeze_fs    = nilfs_unfreeze,
551         /* .write_super_lockfs */
552         /* .unlockfs */
553         .statfs         = nilfs_statfs,
554         .remount_fs     = nilfs_remount,
555         /* .umount_begin */
556         .show_options = nilfs_show_options
557 };
558
559 enum {
560         Opt_err_cont, Opt_err_panic, Opt_err_ro,
561         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
562         Opt_discard, Opt_nodiscard, Opt_err,
563 };
564
565 static match_table_t tokens = {
566         {Opt_err_cont, "errors=continue"},
567         {Opt_err_panic, "errors=panic"},
568         {Opt_err_ro, "errors=remount-ro"},
569         {Opt_barrier, "barrier"},
570         {Opt_nobarrier, "nobarrier"},
571         {Opt_snapshot, "cp=%u"},
572         {Opt_order, "order=%s"},
573         {Opt_norecovery, "norecovery"},
574         {Opt_discard, "discard"},
575         {Opt_nodiscard, "nodiscard"},
576         {Opt_err, NULL}
577 };
578
579 static int parse_options(char *options, struct super_block *sb, int is_remount)
580 {
581         struct nilfs_sb_info *sbi = NILFS_SB(sb);
582         char *p;
583         substring_t args[MAX_OPT_ARGS];
584
585         if (!options)
586                 return 1;
587
588         while ((p = strsep(&options, ",")) != NULL) {
589                 int token;
590                 if (!*p)
591                         continue;
592
593                 token = match_token(p, tokens, args);
594                 switch (token) {
595                 case Opt_barrier:
596                         nilfs_set_opt(sbi, BARRIER);
597                         break;
598                 case Opt_nobarrier:
599                         nilfs_clear_opt(sbi, BARRIER);
600                         break;
601                 case Opt_order:
602                         if (strcmp(args[0].from, "relaxed") == 0)
603                                 /* Ordered data semantics */
604                                 nilfs_clear_opt(sbi, STRICT_ORDER);
605                         else if (strcmp(args[0].from, "strict") == 0)
606                                 /* Strict in-order semantics */
607                                 nilfs_set_opt(sbi, STRICT_ORDER);
608                         else
609                                 return 0;
610                         break;
611                 case Opt_err_panic:
612                         nilfs_write_opt(sbi, ERROR_MODE, ERRORS_PANIC);
613                         break;
614                 case Opt_err_ro:
615                         nilfs_write_opt(sbi, ERROR_MODE, ERRORS_RO);
616                         break;
617                 case Opt_err_cont:
618                         nilfs_write_opt(sbi, ERROR_MODE, ERRORS_CONT);
619                         break;
620                 case Opt_snapshot:
621                         if (is_remount) {
622                                 printk(KERN_ERR
623                                        "NILFS: \"%s\" option is invalid "
624                                        "for remount.\n", p);
625                                 return 0;
626                         }
627                         break;
628                 case Opt_norecovery:
629                         nilfs_set_opt(sbi, NORECOVERY);
630                         break;
631                 case Opt_discard:
632                         nilfs_set_opt(sbi, DISCARD);
633                         break;
634                 case Opt_nodiscard:
635                         nilfs_clear_opt(sbi, DISCARD);
636                         break;
637                 default:
638                         printk(KERN_ERR
639                                "NILFS: Unrecognized mount option \"%s\"\n", p);
640                         return 0;
641                 }
642         }
643         return 1;
644 }
645
646 static inline void
647 nilfs_set_default_options(struct nilfs_sb_info *sbi,
648                           struct nilfs_super_block *sbp)
649 {
650         sbi->s_mount_opt =
651                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
652 }
653
654 static int nilfs_setup_super(struct nilfs_sb_info *sbi, int is_mount)
655 {
656         struct the_nilfs *nilfs = sbi->s_nilfs;
657         struct nilfs_super_block **sbp;
658         int max_mnt_count;
659         int mnt_count;
660
661         /* nilfs->ns_sem must be locked by the caller. */
662         sbp = nilfs_prepare_super(sbi, 0);
663         if (!sbp)
664                 return -EIO;
665
666         if (!is_mount)
667                 goto skip_mount_setup;
668
669         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
670         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
671
672         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
673                 printk(KERN_WARNING
674                        "NILFS warning: mounting fs with errors\n");
675 #if 0
676         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
677                 printk(KERN_WARNING
678                        "NILFS warning: maximal mount count reached\n");
679 #endif
680         }
681         if (!max_mnt_count)
682                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
683
684         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
685         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
686
687 skip_mount_setup:
688         sbp[0]->s_state =
689                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
690         /* synchronize sbp[1] with sbp[0] */
691         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
692         return nilfs_commit_super(sbi, NILFS_SB_COMMIT_ALL);
693 }
694
695 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
696                                                  u64 pos, int blocksize,
697                                                  struct buffer_head **pbh)
698 {
699         unsigned long long sb_index = pos;
700         unsigned long offset;
701
702         offset = do_div(sb_index, blocksize);
703         *pbh = sb_bread(sb, sb_index);
704         if (!*pbh)
705                 return NULL;
706         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
707 }
708
709 int nilfs_store_magic_and_option(struct super_block *sb,
710                                  struct nilfs_super_block *sbp,
711                                  char *data)
712 {
713         struct nilfs_sb_info *sbi = NILFS_SB(sb);
714
715         sb->s_magic = le16_to_cpu(sbp->s_magic);
716
717         /* FS independent flags */
718 #ifdef NILFS_ATIME_DISABLE
719         sb->s_flags |= MS_NOATIME;
720 #endif
721
722         nilfs_set_default_options(sbi, sbp);
723
724         sbi->s_resuid = le16_to_cpu(sbp->s_def_resuid);
725         sbi->s_resgid = le16_to_cpu(sbp->s_def_resgid);
726         sbi->s_interval = le32_to_cpu(sbp->s_c_interval);
727         sbi->s_watermark = le32_to_cpu(sbp->s_c_block_max);
728
729         return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
730 }
731
732 int nilfs_check_feature_compatibility(struct super_block *sb,
733                                       struct nilfs_super_block *sbp)
734 {
735         __u64 features;
736
737         features = le64_to_cpu(sbp->s_feature_incompat) &
738                 ~NILFS_FEATURE_INCOMPAT_SUPP;
739         if (features) {
740                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
741                        "optional features (%llx)\n",
742                        (unsigned long long)features);
743                 return -EINVAL;
744         }
745         features = le64_to_cpu(sbp->s_feature_compat_ro) &
746                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
747         if (!(sb->s_flags & MS_RDONLY) && features) {
748                 printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
749                        "unsupported optional features (%llx)\n",
750                        (unsigned long long)features);
751                 return -EINVAL;
752         }
753         return 0;
754 }
755
756 static int nilfs_get_root_dentry(struct super_block *sb,
757                                  struct nilfs_root *root,
758                                  struct dentry **root_dentry)
759 {
760         struct inode *inode;
761         struct dentry *dentry;
762         int ret = 0;
763
764         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
765         if (IS_ERR(inode)) {
766                 printk(KERN_ERR "NILFS: get root inode failed\n");
767                 ret = PTR_ERR(inode);
768                 goto out;
769         }
770         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
771                 iput(inode);
772                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
773                 ret = -EINVAL;
774                 goto out;
775         }
776
777         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
778                 dentry = d_find_alias(inode);
779                 if (!dentry) {
780                         dentry = d_alloc_root(inode);
781                         if (!dentry) {
782                                 iput(inode);
783                                 ret = -ENOMEM;
784                                 goto failed_dentry;
785                         }
786                 } else {
787                         iput(inode);
788                 }
789         } else {
790                 dentry = d_obtain_alias(inode);
791                 if (IS_ERR(dentry)) {
792                         ret = PTR_ERR(dentry);
793                         goto failed_dentry;
794                 }
795         }
796         *root_dentry = dentry;
797  out:
798         return ret;
799
800  failed_dentry:
801         printk(KERN_ERR "NILFS: get root dentry failed\n");
802         goto out;
803 }
804
805 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
806                                  struct dentry **root_dentry)
807 {
808         struct the_nilfs *nilfs = NILFS_SB(s)->s_nilfs;
809         struct nilfs_root *root;
810         int ret;
811
812         down_read(&nilfs->ns_segctor_sem);
813         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
814         up_read(&nilfs->ns_segctor_sem);
815         if (ret < 0) {
816                 ret = (ret == -ENOENT) ? -EINVAL : ret;
817                 goto out;
818         } else if (!ret) {
819                 printk(KERN_ERR "NILFS: The specified checkpoint is "
820                        "not a snapshot (checkpoint number=%llu).\n",
821                        (unsigned long long)cno);
822                 ret = -EINVAL;
823                 goto out;
824         }
825
826         ret = nilfs_attach_checkpoint(NILFS_SB(s), cno, false, &root);
827         if (ret) {
828                 printk(KERN_ERR "NILFS: error loading snapshot "
829                        "(checkpoint number=%llu).\n",
830                (unsigned long long)cno);
831                 goto out;
832         }
833         ret = nilfs_get_root_dentry(s, root, root_dentry);
834         nilfs_put_root(root);
835  out:
836         return ret;
837 }
838
839 static int nilfs_tree_was_touched(struct dentry *root_dentry)
840 {
841         return atomic_read(&root_dentry->d_count) > 1;
842 }
843
844 /**
845  * nilfs_try_to_shrink_tree() - try to shrink dentries of a checkpoint
846  * @root_dentry: root dentry of the tree to be shrunk
847  *
848  * This function returns true if the tree was in-use.
849  */
850 static int nilfs_try_to_shrink_tree(struct dentry *root_dentry)
851 {
852         if (have_submounts(root_dentry))
853                 return true;
854         shrink_dcache_parent(root_dentry);
855         return nilfs_tree_was_touched(root_dentry);
856 }
857
858 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
859 {
860         struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
861         struct nilfs_root *root;
862         struct inode *inode;
863         struct dentry *dentry;
864         int ret;
865
866         if (cno < 0 || cno > nilfs->ns_cno)
867                 return false;
868
869         if (cno >= nilfs_last_cno(nilfs))
870                 return true;    /* protect recent checkpoints */
871
872         ret = false;
873         root = nilfs_lookup_root(NILFS_SB(sb)->s_nilfs, cno);
874         if (root) {
875                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
876                 if (inode) {
877                         dentry = d_find_alias(inode);
878                         if (dentry) {
879                                 if (nilfs_tree_was_touched(dentry))
880                                         ret = nilfs_try_to_shrink_tree(dentry);
881                                 dput(dentry);
882                         }
883                         iput(inode);
884                 }
885                 nilfs_put_root(root);
886         }
887         return ret;
888 }
889
890 /**
891  * nilfs_fill_super() - initialize a super block instance
892  * @sb: super_block
893  * @data: mount options
894  * @silent: silent mode flag
895  *
896  * This function is called exclusively by nilfs->ns_mount_mutex.
897  * So, the recovery process is protected from other simultaneous mounts.
898  */
899 static int
900 nilfs_fill_super(struct super_block *sb, void *data, int silent)
901 {
902         struct the_nilfs *nilfs;
903         struct nilfs_sb_info *sbi;
904         struct nilfs_root *fsroot;
905         struct backing_dev_info *bdi;
906         __u64 cno;
907         int err;
908
909         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
910         if (!sbi)
911                 return -ENOMEM;
912
913         sb->s_fs_info = sbi;
914         sbi->s_super = sb;
915
916         nilfs = alloc_nilfs(sb->s_bdev);
917         if (!nilfs) {
918                 err = -ENOMEM;
919                 goto failed_sbi;
920         }
921         sbi->s_nilfs = nilfs;
922
923         err = init_nilfs(nilfs, sbi, (char *)data);
924         if (err)
925                 goto failed_nilfs;
926
927         spin_lock_init(&sbi->s_inode_lock);
928         INIT_LIST_HEAD(&sbi->s_dirty_files);
929
930         /*
931          * Following initialization is overlapped because
932          * nilfs_sb_info structure has been cleared at the beginning.
933          * But we reserve them to keep our interest and make ready
934          * for the future change.
935          */
936         get_random_bytes(&sbi->s_next_generation,
937                          sizeof(sbi->s_next_generation));
938         spin_lock_init(&sbi->s_next_gen_lock);
939
940         sb->s_op = &nilfs_sops;
941         sb->s_export_op = &nilfs_export_ops;
942         sb->s_root = NULL;
943         sb->s_time_gran = 1;
944
945         bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
946         sb->s_bdi = bdi ? : &default_backing_dev_info;
947
948         err = load_nilfs(nilfs, sbi);
949         if (err)
950                 goto failed_nilfs;
951
952         cno = nilfs_last_cno(nilfs);
953         err = nilfs_attach_checkpoint(sbi, cno, true, &fsroot);
954         if (err) {
955                 printk(KERN_ERR "NILFS: error loading last checkpoint "
956                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
957                 goto failed_unload;
958         }
959
960         if (!(sb->s_flags & MS_RDONLY)) {
961                 err = nilfs_attach_segment_constructor(sbi, fsroot);
962                 if (err)
963                         goto failed_checkpoint;
964         }
965
966         err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
967         if (err)
968                 goto failed_segctor;
969
970         nilfs_put_root(fsroot);
971
972         if (!(sb->s_flags & MS_RDONLY)) {
973                 down_write(&nilfs->ns_sem);
974                 nilfs_setup_super(sbi, true);
975                 up_write(&nilfs->ns_sem);
976         }
977
978         return 0;
979
980  failed_segctor:
981         nilfs_detach_segment_constructor(sbi);
982
983  failed_checkpoint:
984         nilfs_put_root(fsroot);
985
986  failed_unload:
987         iput(nilfs->ns_sufile);
988         iput(nilfs->ns_cpfile);
989         iput(nilfs->ns_dat);
990
991  failed_nilfs:
992         destroy_nilfs(nilfs);
993
994  failed_sbi:
995         sb->s_fs_info = NULL;
996         kfree(sbi);
997         return err;
998 }
999
1000 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1001 {
1002         struct nilfs_sb_info *sbi = NILFS_SB(sb);
1003         struct the_nilfs *nilfs = sbi->s_nilfs;
1004         unsigned long old_sb_flags;
1005         struct nilfs_mount_options old_opts;
1006         int err;
1007
1008         old_sb_flags = sb->s_flags;
1009         old_opts.mount_opt = sbi->s_mount_opt;
1010
1011         if (!parse_options(data, sb, 1)) {
1012                 err = -EINVAL;
1013                 goto restore_opts;
1014         }
1015         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1016
1017         err = -EINVAL;
1018
1019         if (!nilfs_valid_fs(nilfs)) {
1020                 printk(KERN_WARNING "NILFS (device %s): couldn't "
1021                        "remount because the filesystem is in an "
1022                        "incomplete recovery state.\n", sb->s_id);
1023                 goto restore_opts;
1024         }
1025
1026         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1027                 goto out;
1028         if (*flags & MS_RDONLY) {
1029                 /* Shutting down the segment constructor */
1030                 nilfs_detach_segment_constructor(sbi);
1031                 sb->s_flags |= MS_RDONLY;
1032
1033                 /*
1034                  * Remounting a valid RW partition RDONLY, so set
1035                  * the RDONLY flag and then mark the partition as valid again.
1036                  */
1037                 down_write(&nilfs->ns_sem);
1038                 nilfs_cleanup_super(sbi);
1039                 up_write(&nilfs->ns_sem);
1040         } else {
1041                 __u64 features;
1042                 struct nilfs_root *root;
1043
1044                 /*
1045                  * Mounting a RDONLY partition read-write, so reread and
1046                  * store the current valid flag.  (It may have been changed
1047                  * by fsck since we originally mounted the partition.)
1048                  */
1049                 down_read(&nilfs->ns_sem);
1050                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1051                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
1052                 up_read(&nilfs->ns_sem);
1053                 if (features) {
1054                         printk(KERN_WARNING "NILFS (device %s): couldn't "
1055                                "remount RDWR because of unsupported optional "
1056                                "features (%llx)\n",
1057                                sb->s_id, (unsigned long long)features);
1058                         err = -EROFS;
1059                         goto restore_opts;
1060                 }
1061
1062                 sb->s_flags &= ~MS_RDONLY;
1063
1064                 root = NILFS_I(sb->s_root->d_inode)->i_root;
1065                 err = nilfs_attach_segment_constructor(sbi, root);
1066                 if (err)
1067                         goto restore_opts;
1068
1069                 down_write(&nilfs->ns_sem);
1070                 nilfs_setup_super(sbi, true);
1071                 up_write(&nilfs->ns_sem);
1072         }
1073  out:
1074         return 0;
1075
1076  restore_opts:
1077         sb->s_flags = old_sb_flags;
1078         sbi->s_mount_opt = old_opts.mount_opt;
1079         return err;
1080 }
1081
1082 struct nilfs_super_data {
1083         struct block_device *bdev;
1084         struct nilfs_sb_info *sbi;
1085         __u64 cno;
1086         int flags;
1087 };
1088
1089 /**
1090  * nilfs_identify - pre-read mount options needed to identify mount instance
1091  * @data: mount options
1092  * @sd: nilfs_super_data
1093  */
1094 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1095 {
1096         char *p, *options = data;
1097         substring_t args[MAX_OPT_ARGS];
1098         int token;
1099         int ret = 0;
1100
1101         do {
1102                 p = strsep(&options, ",");
1103                 if (p != NULL && *p) {
1104                         token = match_token(p, tokens, args);
1105                         if (token == Opt_snapshot) {
1106                                 if (!(sd->flags & MS_RDONLY)) {
1107                                         ret++;
1108                                 } else {
1109                                         sd->cno = simple_strtoull(args[0].from,
1110                                                                   NULL, 0);
1111                                         /*
1112                                          * No need to see the end pointer;
1113                                          * match_token() has done syntax
1114                                          * checking.
1115                                          */
1116                                         if (sd->cno == 0)
1117                                                 ret++;
1118                                 }
1119                         }
1120                         if (ret)
1121                                 printk(KERN_ERR
1122                                        "NILFS: invalid mount option: %s\n", p);
1123                 }
1124                 if (!options)
1125                         break;
1126                 BUG_ON(options == data);
1127                 *(options - 1) = ',';
1128         } while (!ret);
1129         return ret;
1130 }
1131
1132 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1133 {
1134         s->s_bdev = data;
1135         s->s_dev = s->s_bdev->bd_dev;
1136         return 0;
1137 }
1138
1139 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1140 {
1141         return (void *)s->s_bdev == data;
1142 }
1143
1144 static struct dentry *
1145 nilfs_mount(struct file_system_type *fs_type, int flags,
1146              const char *dev_name, void *data)
1147 {
1148         struct nilfs_super_data sd;
1149         struct super_block *s;
1150         fmode_t mode = FMODE_READ;
1151         struct dentry *root_dentry;
1152         int err, s_new = false;
1153
1154         if (!(flags & MS_RDONLY))
1155                 mode |= FMODE_WRITE;
1156
1157         sd.bdev = open_bdev_exclusive(dev_name, mode, fs_type);
1158         if (IS_ERR(sd.bdev))
1159                 return ERR_CAST(sd.bdev);
1160
1161         sd.cno = 0;
1162         sd.flags = flags;
1163         if (nilfs_identify((char *)data, &sd)) {
1164                 err = -EINVAL;
1165                 goto failed;
1166         }
1167
1168         /*
1169          * once the super is inserted into the list by sget, s_umount
1170          * will protect the lockfs code from trying to start a snapshot
1171          * while we are mounting
1172          */
1173         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1174         if (sd.bdev->bd_fsfreeze_count > 0) {
1175                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1176                 err = -EBUSY;
1177                 goto failed;
1178         }
1179         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, sd.bdev);
1180         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1181         if (IS_ERR(s)) {
1182                 err = PTR_ERR(s);
1183                 goto failed;
1184         }
1185
1186         if (!s->s_root) {
1187                 char b[BDEVNAME_SIZE];
1188
1189                 s_new = true;
1190
1191                 /* New superblock instance created */
1192                 s->s_flags = flags;
1193                 s->s_mode = mode;
1194                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1195                 sb_set_blocksize(s, block_size(sd.bdev));
1196
1197                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1198                 if (err)
1199                         goto failed_super;
1200
1201                 s->s_flags |= MS_ACTIVE;
1202         } else if (!sd.cno) {
1203                 int busy = false;
1204
1205                 if (nilfs_tree_was_touched(s->s_root)) {
1206                         busy = nilfs_try_to_shrink_tree(s->s_root);
1207                         if (busy && (flags ^ s->s_flags) & MS_RDONLY) {
1208                                 printk(KERN_ERR "NILFS: the device already "
1209                                        "has a %s mount.\n",
1210                                        (s->s_flags & MS_RDONLY) ?
1211                                        "read-only" : "read/write");
1212                                 err = -EBUSY;
1213                                 goto failed_super;
1214                         }
1215                 }
1216                 if (!busy) {
1217                         /*
1218                          * Try remount to setup mount states if the current
1219                          * tree is not mounted and only snapshots use this sb.
1220                          */
1221                         err = nilfs_remount(s, &flags, data);
1222                         if (err)
1223                                 goto failed_super;
1224                 }
1225         }
1226
1227         if (sd.cno) {
1228                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1229                 if (err)
1230                         goto failed_super;
1231         } else {
1232                 root_dentry = dget(s->s_root);
1233         }
1234
1235         if (!s_new)
1236                 close_bdev_exclusive(sd.bdev, mode);
1237
1238         return root_dentry;
1239
1240  failed_super:
1241         deactivate_locked_super(s);
1242
1243  failed:
1244         if (!s_new)
1245                 close_bdev_exclusive(sd.bdev, mode);
1246         return ERR_PTR(err);
1247 }
1248
1249 struct file_system_type nilfs_fs_type = {
1250         .owner    = THIS_MODULE,
1251         .name     = "nilfs2",
1252         .mount    = nilfs_mount,
1253         .kill_sb  = kill_block_super,
1254         .fs_flags = FS_REQUIRES_DEV,
1255 };
1256
1257 static void nilfs_inode_init_once(void *obj)
1258 {
1259         struct nilfs_inode_info *ii = obj;
1260
1261         INIT_LIST_HEAD(&ii->i_dirty);
1262 #ifdef CONFIG_NILFS_XATTR
1263         init_rwsem(&ii->xattr_sem);
1264 #endif
1265         nilfs_btnode_cache_init_once(&ii->i_btnode_cache);
1266         ii->i_bmap = &ii->i_bmap_data;
1267         inode_init_once(&ii->vfs_inode);
1268 }
1269
1270 static void nilfs_segbuf_init_once(void *obj)
1271 {
1272         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1273 }
1274
1275 static void nilfs_destroy_cachep(void)
1276 {
1277         if (nilfs_inode_cachep)
1278                 kmem_cache_destroy(nilfs_inode_cachep);
1279         if (nilfs_transaction_cachep)
1280                 kmem_cache_destroy(nilfs_transaction_cachep);
1281         if (nilfs_segbuf_cachep)
1282                 kmem_cache_destroy(nilfs_segbuf_cachep);
1283         if (nilfs_btree_path_cache)
1284                 kmem_cache_destroy(nilfs_btree_path_cache);
1285 }
1286
1287 static int __init nilfs_init_cachep(void)
1288 {
1289         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1290                         sizeof(struct nilfs_inode_info), 0,
1291                         SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
1292         if (!nilfs_inode_cachep)
1293                 goto fail;
1294
1295         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1296                         sizeof(struct nilfs_transaction_info), 0,
1297                         SLAB_RECLAIM_ACCOUNT, NULL);
1298         if (!nilfs_transaction_cachep)
1299                 goto fail;
1300
1301         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1302                         sizeof(struct nilfs_segment_buffer), 0,
1303                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1304         if (!nilfs_segbuf_cachep)
1305                 goto fail;
1306
1307         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1308                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1309                         0, 0, NULL);
1310         if (!nilfs_btree_path_cache)
1311                 goto fail;
1312
1313         return 0;
1314
1315 fail:
1316         nilfs_destroy_cachep();
1317         return -ENOMEM;
1318 }
1319
1320 static int __init init_nilfs_fs(void)
1321 {
1322         int err;
1323
1324         err = nilfs_init_cachep();
1325         if (err)
1326                 goto fail;
1327
1328         err = register_filesystem(&nilfs_fs_type);
1329         if (err)
1330                 goto free_cachep;
1331
1332         printk(KERN_INFO "NILFS version 2 loaded\n");
1333         return 0;
1334
1335 free_cachep:
1336         nilfs_destroy_cachep();
1337 fail:
1338         return err;
1339 }
1340
1341 static void __exit exit_nilfs_fs(void)
1342 {
1343         nilfs_destroy_cachep();
1344         unregister_filesystem(&nilfs_fs_type);
1345 }
1346
1347 module_init(init_nilfs_fs)
1348 module_exit(exit_nilfs_fs)