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TOMOYO Linux Cross Reference
Linux/fs/nilfs2/super.c

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  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/crc32.h>
 47 #include <linux/vfs.h>
 48 #include <linux/writeback.h>
 49 #include <linux/seq_file.h>
 50 #include <linux/mount.h>
 51 #include "nilfs.h"
 52 #include "export.h"
 53 #include "mdt.h"
 54 #include "alloc.h"
 55 #include "btree.h"
 56 #include "btnode.h"
 57 #include "page.h"
 58 #include "cpfile.h"
 59 #include "sufile.h" /* nilfs_sufile_resize(), nilfs_sufile_set_alloc_range() */
 60 #include "ifile.h"
 61 #include "dat.h"
 62 #include "segment.h"
 63 #include "segbuf.h"
 64 
 65 MODULE_AUTHOR("NTT Corp.");
 66 MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
 67                    "(NILFS)");
 68 MODULE_LICENSE("GPL");
 69 
 70 static struct kmem_cache *nilfs_inode_cachep;
 71 struct kmem_cache *nilfs_transaction_cachep;
 72 struct kmem_cache *nilfs_segbuf_cachep;
 73 struct kmem_cache *nilfs_btree_path_cache;
 74 
 75 static int nilfs_setup_super(struct super_block *sb, int is_mount);
 76 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
 77 
 78 static void nilfs_set_error(struct super_block *sb)
 79 {
 80         struct the_nilfs *nilfs = sb->s_fs_info;
 81         struct nilfs_super_block **sbp;
 82 
 83         down_write(&nilfs->ns_sem);
 84         if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
 85                 nilfs->ns_mount_state |= NILFS_ERROR_FS;
 86                 sbp = nilfs_prepare_super(sb, 0);
 87                 if (likely(sbp)) {
 88                         sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
 89                         if (sbp[1])
 90                                 sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
 91                         nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
 92                 }
 93         }
 94         up_write(&nilfs->ns_sem);
 95 }
 96 
 97 /**
 98  * nilfs_error() - report failure condition on a filesystem
 99  *
100  * nilfs_error() sets an ERROR_FS flag on the superblock as well as
101  * reporting an error message.  It should be called when NILFS detects
102  * incoherences or defects of meta data on disk.  As for sustainable
103  * errors such as a single-shot I/O error, nilfs_warning() or the printk()
104  * function should be used instead.
105  *
106  * The segment constructor must not call this function because it can
107  * kill itself.
108  */
109 void nilfs_error(struct super_block *sb, const char *function,
110                  const char *fmt, ...)
111 {
112         struct the_nilfs *nilfs = sb->s_fs_info;
113         struct va_format vaf;
114         va_list args;
115 
116         va_start(args, fmt);
117 
118         vaf.fmt = fmt;
119         vaf.va = &args;
120 
121         printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
122                sb->s_id, function, &vaf);
123 
124         va_end(args);
125 
126         if (!(sb->s_flags & MS_RDONLY)) {
127                 nilfs_set_error(sb);
128 
129                 if (nilfs_test_opt(nilfs, ERRORS_RO)) {
130                         printk(KERN_CRIT "Remounting filesystem read-only\n");
131                         sb->s_flags |= MS_RDONLY;
132                 }
133         }
134 
135         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
136                 panic("NILFS (device %s): panic forced after error\n",
137                       sb->s_id);
138 }
139 
140 void nilfs_warning(struct super_block *sb, const char *function,
141                    const char *fmt, ...)
142 {
143         struct va_format vaf;
144         va_list args;
145 
146         va_start(args, fmt);
147 
148         vaf.fmt = fmt;
149         vaf.va = &args;
150 
151         printk(KERN_WARNING "NILFS warning (device %s): %s: %pV\n",
152                sb->s_id, function, &vaf);
153 
154         va_end(args);
155 }
156 
157 
158 struct inode *nilfs_alloc_inode(struct super_block *sb)
159 {
160         struct nilfs_inode_info *ii;
161 
162         ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
163         if (!ii)
164                 return NULL;
165         ii->i_bh = NULL;
166         ii->i_state = 0;
167         ii->i_cno = 0;
168         ii->vfs_inode.i_version = 1;
169         nilfs_mapping_init(&ii->i_btnode_cache, &ii->vfs_inode, sb->s_bdi);
170         return &ii->vfs_inode;
171 }
172 
173 static void nilfs_i_callback(struct rcu_head *head)
174 {
175         struct inode *inode = container_of(head, struct inode, i_rcu);
176         struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
177 
178         INIT_LIST_HEAD(&inode->i_dentry);
179 
180         if (mdi) {
181                 kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
182                 kfree(mdi);
183         }
184         kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
185 }
186 
187 void nilfs_destroy_inode(struct inode *inode)
188 {
189         call_rcu(&inode->i_rcu, nilfs_i_callback);
190 }
191 
192 static int nilfs_sync_super(struct super_block *sb, int flag)
193 {
194         struct the_nilfs *nilfs = sb->s_fs_info;
195         int err;
196 
197  retry:
198         set_buffer_dirty(nilfs->ns_sbh[0]);
199         if (nilfs_test_opt(nilfs, BARRIER)) {
200                 err = __sync_dirty_buffer(nilfs->ns_sbh[0],
201                                           WRITE_SYNC | WRITE_FLUSH_FUA);
202         } else {
203                 err = sync_dirty_buffer(nilfs->ns_sbh[0]);
204         }
205 
206         if (unlikely(err)) {
207                 printk(KERN_ERR
208                        "NILFS: unable to write superblock (err=%d)\n", err);
209                 if (err == -EIO && nilfs->ns_sbh[1]) {
210                         /*
211                          * sbp[0] points to newer log than sbp[1],
212                          * so copy sbp[0] to sbp[1] to take over sbp[0].
213                          */
214                         memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
215                                nilfs->ns_sbsize);
216                         nilfs_fall_back_super_block(nilfs);
217                         goto retry;
218                 }
219         } else {
220                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
221 
222                 nilfs->ns_sbwcount++;
223 
224                 /*
225                  * The latest segment becomes trailable from the position
226                  * written in superblock.
227                  */
228                 clear_nilfs_discontinued(nilfs);
229 
230                 /* update GC protection for recent segments */
231                 if (nilfs->ns_sbh[1]) {
232                         if (flag == NILFS_SB_COMMIT_ALL) {
233                                 set_buffer_dirty(nilfs->ns_sbh[1]);
234                                 if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
235                                         goto out;
236                         }
237                         if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
238                             le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
239                                 sbp = nilfs->ns_sbp[1];
240                 }
241 
242                 spin_lock(&nilfs->ns_last_segment_lock);
243                 nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
244                 spin_unlock(&nilfs->ns_last_segment_lock);
245         }
246  out:
247         return err;
248 }
249 
250 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
251                           struct the_nilfs *nilfs)
252 {
253         sector_t nfreeblocks;
254 
255         /* nilfs->ns_sem must be locked by the caller. */
256         nilfs_count_free_blocks(nilfs, &nfreeblocks);
257         sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
258 
259         spin_lock(&nilfs->ns_last_segment_lock);
260         sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
261         sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
262         sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
263         spin_unlock(&nilfs->ns_last_segment_lock);
264 }
265 
266 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
267                                                int flip)
268 {
269         struct the_nilfs *nilfs = sb->s_fs_info;
270         struct nilfs_super_block **sbp = nilfs->ns_sbp;
271 
272         /* nilfs->ns_sem must be locked by the caller. */
273         if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
274                 if (sbp[1] &&
275                     sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
276                         memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
277                 } else {
278                         printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
279                                sb->s_id);
280                         return NULL;
281                 }
282         } else if (sbp[1] &&
283                    sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
284                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
285         }
286 
287         if (flip && sbp[1])
288                 nilfs_swap_super_block(nilfs);
289 
290         return sbp;
291 }
292 
293 int nilfs_commit_super(struct super_block *sb, int flag)
294 {
295         struct the_nilfs *nilfs = sb->s_fs_info;
296         struct nilfs_super_block **sbp = nilfs->ns_sbp;
297         time_t t;
298 
299         /* nilfs->ns_sem must be locked by the caller. */
300         t = get_seconds();
301         nilfs->ns_sbwtime = t;
302         sbp[0]->s_wtime = cpu_to_le64(t);
303         sbp[0]->s_sum = 0;
304         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
305                                              (unsigned char *)sbp[0],
306                                              nilfs->ns_sbsize));
307         if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
308                 sbp[1]->s_wtime = sbp[0]->s_wtime;
309                 sbp[1]->s_sum = 0;
310                 sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
311                                             (unsigned char *)sbp[1],
312                                             nilfs->ns_sbsize));
313         }
314         clear_nilfs_sb_dirty(nilfs);
315         return nilfs_sync_super(sb, flag);
316 }
317 
318 /**
319  * nilfs_cleanup_super() - write filesystem state for cleanup
320  * @sb: super block instance to be unmounted or degraded to read-only
321  *
322  * This function restores state flags in the on-disk super block.
323  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
324  * filesystem was not clean previously.
325  */
326 int nilfs_cleanup_super(struct super_block *sb)
327 {
328         struct the_nilfs *nilfs = sb->s_fs_info;
329         struct nilfs_super_block **sbp;
330         int flag = NILFS_SB_COMMIT;
331         int ret = -EIO;
332 
333         sbp = nilfs_prepare_super(sb, 0);
334         if (sbp) {
335                 sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
336                 nilfs_set_log_cursor(sbp[0], nilfs);
337                 if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
338                         /*
339                          * make the "clean" flag also to the opposite
340                          * super block if both super blocks point to
341                          * the same checkpoint.
342                          */
343                         sbp[1]->s_state = sbp[0]->s_state;
344                         flag = NILFS_SB_COMMIT_ALL;
345                 }
346                 ret = nilfs_commit_super(sb, flag);
347         }
348         return ret;
349 }
350 
351 /**
352  * nilfs_move_2nd_super - relocate secondary super block
353  * @sb: super block instance
354  * @sb2off: new offset of the secondary super block (in bytes)
355  */
356 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
357 {
358         struct the_nilfs *nilfs = sb->s_fs_info;
359         struct buffer_head *nsbh;
360         struct nilfs_super_block *nsbp;
361         sector_t blocknr, newblocknr;
362         unsigned long offset;
363         int sb2i;  /* array index of the secondary superblock */
364         int ret = 0;
365 
366         /* nilfs->ns_sem must be locked by the caller. */
367         if (nilfs->ns_sbh[1] &&
368             nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
369                 sb2i = 1;
370                 blocknr = nilfs->ns_sbh[1]->b_blocknr;
371         } else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
372                 sb2i = 0;
373                 blocknr = nilfs->ns_sbh[0]->b_blocknr;
374         } else {
375                 sb2i = -1;
376                 blocknr = 0;
377         }
378         if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
379                 goto out;  /* super block location is unchanged */
380 
381         /* Get new super block buffer */
382         newblocknr = sb2off >> nilfs->ns_blocksize_bits;
383         offset = sb2off & (nilfs->ns_blocksize - 1);
384         nsbh = sb_getblk(sb, newblocknr);
385         if (!nsbh) {
386                 printk(KERN_WARNING
387                        "NILFS warning: unable to move secondary superblock "
388                        "to block %llu\n", (unsigned long long)newblocknr);
389                 ret = -EIO;
390                 goto out;
391         }
392         nsbp = (void *)nsbh->b_data + offset;
393         memset(nsbp, 0, nilfs->ns_blocksize);
394 
395         if (sb2i >= 0) {
396                 memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
397                 brelse(nilfs->ns_sbh[sb2i]);
398                 nilfs->ns_sbh[sb2i] = nsbh;
399                 nilfs->ns_sbp[sb2i] = nsbp;
400         } else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
401                 /* secondary super block will be restored to index 1 */
402                 nilfs->ns_sbh[1] = nsbh;
403                 nilfs->ns_sbp[1] = nsbp;
404         } else {
405                 brelse(nsbh);
406         }
407 out:
408         return ret;
409 }
410 
411 /**
412  * nilfs_resize_fs - resize the filesystem
413  * @sb: super block instance
414  * @newsize: new size of the filesystem (in bytes)
415  */
416 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
417 {
418         struct the_nilfs *nilfs = sb->s_fs_info;
419         struct nilfs_super_block **sbp;
420         __u64 devsize, newnsegs;
421         loff_t sb2off;
422         int ret;
423 
424         ret = -ERANGE;
425         devsize = i_size_read(sb->s_bdev->bd_inode);
426         if (newsize > devsize)
427                 goto out;
428 
429         /*
430          * Write lock is required to protect some functions depending
431          * on the number of segments, the number of reserved segments,
432          * and so forth.
433          */
434         down_write(&nilfs->ns_segctor_sem);
435 
436         sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
437         newnsegs = sb2off >> nilfs->ns_blocksize_bits;
438         do_div(newnsegs, nilfs->ns_blocks_per_segment);
439 
440         ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
441         up_write(&nilfs->ns_segctor_sem);
442         if (ret < 0)
443                 goto out;
444 
445         ret = nilfs_construct_segment(sb);
446         if (ret < 0)
447                 goto out;
448 
449         down_write(&nilfs->ns_sem);
450         nilfs_move_2nd_super(sb, sb2off);
451         ret = -EIO;
452         sbp = nilfs_prepare_super(sb, 0);
453         if (likely(sbp)) {
454                 nilfs_set_log_cursor(sbp[0], nilfs);
455                 /*
456                  * Drop NILFS_RESIZE_FS flag for compatibility with
457                  * mount-time resize which may be implemented in a
458                  * future release.
459                  */
460                 sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
461                                               ~NILFS_RESIZE_FS);
462                 sbp[0]->s_dev_size = cpu_to_le64(newsize);
463                 sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
464                 if (sbp[1])
465                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
466                 ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
467         }
468         up_write(&nilfs->ns_sem);
469 
470         /*
471          * Reset the range of allocatable segments last.  This order
472          * is important in the case of expansion because the secondary
473          * superblock must be protected from log write until migration
474          * completes.
475          */
476         if (!ret)
477                 nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
478 out:
479         return ret;
480 }
481 
482 static void nilfs_put_super(struct super_block *sb)
483 {
484         struct the_nilfs *nilfs = sb->s_fs_info;
485 
486         nilfs_detach_log_writer(sb);
487 
488         if (!(sb->s_flags & MS_RDONLY)) {
489                 down_write(&nilfs->ns_sem);
490                 nilfs_cleanup_super(sb);
491                 up_write(&nilfs->ns_sem);
492         }
493 
494         iput(nilfs->ns_sufile);
495         iput(nilfs->ns_cpfile);
496         iput(nilfs->ns_dat);
497 
498         destroy_nilfs(nilfs);
499         sb->s_fs_info = NULL;
500 }
501 
502 static int nilfs_sync_fs(struct super_block *sb, int wait)
503 {
504         struct the_nilfs *nilfs = sb->s_fs_info;
505         struct nilfs_super_block **sbp;
506         int err = 0;
507 
508         /* This function is called when super block should be written back */
509         if (wait)
510                 err = nilfs_construct_segment(sb);
511 
512         down_write(&nilfs->ns_sem);
513         if (nilfs_sb_dirty(nilfs)) {
514                 sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
515                 if (likely(sbp)) {
516                         nilfs_set_log_cursor(sbp[0], nilfs);
517                         nilfs_commit_super(sb, NILFS_SB_COMMIT);
518                 }
519         }
520         up_write(&nilfs->ns_sem);
521 
522         return err;
523 }
524 
525 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
526                             struct nilfs_root **rootp)
527 {
528         struct the_nilfs *nilfs = sb->s_fs_info;
529         struct nilfs_root *root;
530         struct nilfs_checkpoint *raw_cp;
531         struct buffer_head *bh_cp;
532         int err = -ENOMEM;
533 
534         root = nilfs_find_or_create_root(
535                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
536         if (!root)
537                 return err;
538 
539         if (root->ifile)
540                 goto reuse; /* already attached checkpoint */
541 
542         down_read(&nilfs->ns_segctor_sem);
543         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
544                                           &bh_cp);
545         up_read(&nilfs->ns_segctor_sem);
546         if (unlikely(err)) {
547                 if (err == -ENOENT || err == -EINVAL) {
548                         printk(KERN_ERR
549                                "NILFS: Invalid checkpoint "
550                                "(checkpoint number=%llu)\n",
551                                (unsigned long long)cno);
552                         err = -EINVAL;
553                 }
554                 goto failed;
555         }
556 
557         err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
558                                &raw_cp->cp_ifile_inode, &root->ifile);
559         if (err)
560                 goto failed_bh;
561 
562         atomic_set(&root->inodes_count, le64_to_cpu(raw_cp->cp_inodes_count));
563         atomic_set(&root->blocks_count, le64_to_cpu(raw_cp->cp_blocks_count));
564 
565         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
566 
567  reuse:
568         *rootp = root;
569         return 0;
570 
571  failed_bh:
572         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
573  failed:
574         nilfs_put_root(root);
575 
576         return err;
577 }
578 
579 static int nilfs_freeze(struct super_block *sb)
580 {
581         struct the_nilfs *nilfs = sb->s_fs_info;
582         int err;
583 
584         if (sb->s_flags & MS_RDONLY)
585                 return 0;
586 
587         /* Mark super block clean */
588         down_write(&nilfs->ns_sem);
589         err = nilfs_cleanup_super(sb);
590         up_write(&nilfs->ns_sem);
591         return err;
592 }
593 
594 static int nilfs_unfreeze(struct super_block *sb)
595 {
596         struct the_nilfs *nilfs = sb->s_fs_info;
597 
598         if (sb->s_flags & MS_RDONLY)
599                 return 0;
600 
601         down_write(&nilfs->ns_sem);
602         nilfs_setup_super(sb, false);
603         up_write(&nilfs->ns_sem);
604         return 0;
605 }
606 
607 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
608 {
609         struct super_block *sb = dentry->d_sb;
610         struct nilfs_root *root = NILFS_I(dentry->d_inode)->i_root;
611         struct the_nilfs *nilfs = root->nilfs;
612         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
613         unsigned long long blocks;
614         unsigned long overhead;
615         unsigned long nrsvblocks;
616         sector_t nfreeblocks;
617         int err;
618 
619         /*
620          * Compute all of the segment blocks
621          *
622          * The blocks before first segment and after last segment
623          * are excluded.
624          */
625         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
626                 - nilfs->ns_first_data_block;
627         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
628 
629         /*
630          * Compute the overhead
631          *
632          * When distributing meta data blocks outside segment structure,
633          * We must count them as the overhead.
634          */
635         overhead = 0;
636 
637         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
638         if (unlikely(err))
639                 return err;
640 
641         buf->f_type = NILFS_SUPER_MAGIC;
642         buf->f_bsize = sb->s_blocksize;
643         buf->f_blocks = blocks - overhead;
644         buf->f_bfree = nfreeblocks;
645         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
646                 (buf->f_bfree - nrsvblocks) : 0;
647         buf->f_files = atomic_read(&root->inodes_count);
648         buf->f_ffree = 0; /* nilfs_count_free_inodes(sb); */
649         buf->f_namelen = NILFS_NAME_LEN;
650         buf->f_fsid.val[0] = (u32)id;
651         buf->f_fsid.val[1] = (u32)(id >> 32);
652 
653         return 0;
654 }
655 
656 static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
657 {
658         struct super_block *sb = vfs->mnt_sb;
659         struct the_nilfs *nilfs = sb->s_fs_info;
660         struct nilfs_root *root = NILFS_I(vfs->mnt_root->d_inode)->i_root;
661 
662         if (!nilfs_test_opt(nilfs, BARRIER))
663                 seq_puts(seq, ",nobarrier");
664         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
665                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
666         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
667                 seq_puts(seq, ",errors=panic");
668         if (nilfs_test_opt(nilfs, ERRORS_CONT))
669                 seq_puts(seq, ",errors=continue");
670         if (nilfs_test_opt(nilfs, STRICT_ORDER))
671                 seq_puts(seq, ",order=strict");
672         if (nilfs_test_opt(nilfs, NORECOVERY))
673                 seq_puts(seq, ",norecovery");
674         if (nilfs_test_opt(nilfs, DISCARD))
675                 seq_puts(seq, ",discard");
676 
677         return 0;
678 }
679 
680 static const struct super_operations nilfs_sops = {
681         .alloc_inode    = nilfs_alloc_inode,
682         .destroy_inode  = nilfs_destroy_inode,
683         .dirty_inode    = nilfs_dirty_inode,
684         /* .write_inode    = nilfs_write_inode, */
685         /* .put_inode      = nilfs_put_inode, */
686         /* .drop_inode    = nilfs_drop_inode, */
687         .evict_inode    = nilfs_evict_inode,
688         .put_super      = nilfs_put_super,
689         /* .write_super    = nilfs_write_super, */
690         .sync_fs        = nilfs_sync_fs,
691         .freeze_fs      = nilfs_freeze,
692         .unfreeze_fs    = nilfs_unfreeze,
693         /* .write_super_lockfs */
694         /* .unlockfs */
695         .statfs         = nilfs_statfs,
696         .remount_fs     = nilfs_remount,
697         /* .umount_begin */
698         .show_options = nilfs_show_options
699 };
700 
701 enum {
702         Opt_err_cont, Opt_err_panic, Opt_err_ro,
703         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
704         Opt_discard, Opt_nodiscard, Opt_err,
705 };
706 
707 static match_table_t tokens = {
708         {Opt_err_cont, "errors=continue"},
709         {Opt_err_panic, "errors=panic"},
710         {Opt_err_ro, "errors=remount-ro"},
711         {Opt_barrier, "barrier"},
712         {Opt_nobarrier, "nobarrier"},
713         {Opt_snapshot, "cp=%u"},
714         {Opt_order, "order=%s"},
715         {Opt_norecovery, "norecovery"},
716         {Opt_discard, "discard"},
717         {Opt_nodiscard, "nodiscard"},
718         {Opt_err, NULL}
719 };
720 
721 static int parse_options(char *options, struct super_block *sb, int is_remount)
722 {
723         struct the_nilfs *nilfs = sb->s_fs_info;
724         char *p;
725         substring_t args[MAX_OPT_ARGS];
726 
727         if (!options)
728                 return 1;
729 
730         while ((p = strsep(&options, ",")) != NULL) {
731                 int token;
732                 if (!*p)
733                         continue;
734 
735                 token = match_token(p, tokens, args);
736                 switch (token) {
737                 case Opt_barrier:
738                         nilfs_set_opt(nilfs, BARRIER);
739                         break;
740                 case Opt_nobarrier:
741                         nilfs_clear_opt(nilfs, BARRIER);
742                         break;
743                 case Opt_order:
744                         if (strcmp(args[0].from, "relaxed") == 0)
745                                 /* Ordered data semantics */
746                                 nilfs_clear_opt(nilfs, STRICT_ORDER);
747                         else if (strcmp(args[0].from, "strict") == 0)
748                                 /* Strict in-order semantics */
749                                 nilfs_set_opt(nilfs, STRICT_ORDER);
750                         else
751                                 return 0;
752                         break;
753                 case Opt_err_panic:
754                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
755                         break;
756                 case Opt_err_ro:
757                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
758                         break;
759                 case Opt_err_cont:
760                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
761                         break;
762                 case Opt_snapshot:
763                         if (is_remount) {
764                                 printk(KERN_ERR
765                                        "NILFS: \"%s\" option is invalid "
766                                        "for remount.\n", p);
767                                 return 0;
768                         }
769                         break;
770                 case Opt_norecovery:
771                         nilfs_set_opt(nilfs, NORECOVERY);
772                         break;
773                 case Opt_discard:
774                         nilfs_set_opt(nilfs, DISCARD);
775                         break;
776                 case Opt_nodiscard:
777                         nilfs_clear_opt(nilfs, DISCARD);
778                         break;
779                 default:
780                         printk(KERN_ERR
781                                "NILFS: Unrecognized mount option \"%s\"\n", p);
782                         return 0;
783                 }
784         }
785         return 1;
786 }
787 
788 static inline void
789 nilfs_set_default_options(struct super_block *sb,
790                           struct nilfs_super_block *sbp)
791 {
792         struct the_nilfs *nilfs = sb->s_fs_info;
793 
794         nilfs->ns_mount_opt =
795                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
796 }
797 
798 static int nilfs_setup_super(struct super_block *sb, int is_mount)
799 {
800         struct the_nilfs *nilfs = sb->s_fs_info;
801         struct nilfs_super_block **sbp;
802         int max_mnt_count;
803         int mnt_count;
804 
805         /* nilfs->ns_sem must be locked by the caller. */
806         sbp = nilfs_prepare_super(sb, 0);
807         if (!sbp)
808                 return -EIO;
809 
810         if (!is_mount)
811                 goto skip_mount_setup;
812 
813         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
814         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
815 
816         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
817                 printk(KERN_WARNING
818                        "NILFS warning: mounting fs with errors\n");
819 #if 0
820         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
821                 printk(KERN_WARNING
822                        "NILFS warning: maximal mount count reached\n");
823 #endif
824         }
825         if (!max_mnt_count)
826                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
827 
828         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
829         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
830 
831 skip_mount_setup:
832         sbp[0]->s_state =
833                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
834         /* synchronize sbp[1] with sbp[0] */
835         if (sbp[1])
836                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
837         return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
838 }
839 
840 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
841                                                  u64 pos, int blocksize,
842                                                  struct buffer_head **pbh)
843 {
844         unsigned long long sb_index = pos;
845         unsigned long offset;
846 
847         offset = do_div(sb_index, blocksize);
848         *pbh = sb_bread(sb, sb_index);
849         if (!*pbh)
850                 return NULL;
851         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
852 }
853 
854 int nilfs_store_magic_and_option(struct super_block *sb,
855                                  struct nilfs_super_block *sbp,
856                                  char *data)
857 {
858         struct the_nilfs *nilfs = sb->s_fs_info;
859 
860         sb->s_magic = le16_to_cpu(sbp->s_magic);
861 
862         /* FS independent flags */
863 #ifdef NILFS_ATIME_DISABLE
864         sb->s_flags |= MS_NOATIME;
865 #endif
866 
867         nilfs_set_default_options(sb, sbp);
868 
869         nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
870         nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
871         nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
872         nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
873 
874         return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
875 }
876 
877 int nilfs_check_feature_compatibility(struct super_block *sb,
878                                       struct nilfs_super_block *sbp)
879 {
880         __u64 features;
881 
882         features = le64_to_cpu(sbp->s_feature_incompat) &
883                 ~NILFS_FEATURE_INCOMPAT_SUPP;
884         if (features) {
885                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
886                        "optional features (%llx)\n",
887                        (unsigned long long)features);
888                 return -EINVAL;
889         }
890         features = le64_to_cpu(sbp->s_feature_compat_ro) &
891                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
892         if (!(sb->s_flags & MS_RDONLY) && features) {
893                 printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
894                        "unsupported optional features (%llx)\n",
895                        (unsigned long long)features);
896                 return -EINVAL;
897         }
898         return 0;
899 }
900 
901 static int nilfs_get_root_dentry(struct super_block *sb,
902                                  struct nilfs_root *root,
903                                  struct dentry **root_dentry)
904 {
905         struct inode *inode;
906         struct dentry *dentry;
907         int ret = 0;
908 
909         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
910         if (IS_ERR(inode)) {
911                 printk(KERN_ERR "NILFS: get root inode failed\n");
912                 ret = PTR_ERR(inode);
913                 goto out;
914         }
915         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
916                 iput(inode);
917                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
918                 ret = -EINVAL;
919                 goto out;
920         }
921 
922         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
923                 dentry = d_find_alias(inode);
924                 if (!dentry) {
925                         dentry = d_alloc_root(inode);
926                         if (!dentry) {
927                                 iput(inode);
928                                 ret = -ENOMEM;
929                                 goto failed_dentry;
930                         }
931                 } else {
932                         iput(inode);
933                 }
934         } else {
935                 dentry = d_obtain_alias(inode);
936                 if (IS_ERR(dentry)) {
937                         ret = PTR_ERR(dentry);
938                         goto failed_dentry;
939                 }
940         }
941         *root_dentry = dentry;
942  out:
943         return ret;
944 
945  failed_dentry:
946         printk(KERN_ERR "NILFS: get root dentry failed\n");
947         goto out;
948 }
949 
950 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
951                                  struct dentry **root_dentry)
952 {
953         struct the_nilfs *nilfs = s->s_fs_info;
954         struct nilfs_root *root;
955         int ret;
956 
957         mutex_lock(&nilfs->ns_snapshot_mount_mutex);
958 
959         down_read(&nilfs->ns_segctor_sem);
960         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
961         up_read(&nilfs->ns_segctor_sem);
962         if (ret < 0) {
963                 ret = (ret == -ENOENT) ? -EINVAL : ret;
964                 goto out;
965         } else if (!ret) {
966                 printk(KERN_ERR "NILFS: The specified checkpoint is "
967                        "not a snapshot (checkpoint number=%llu).\n",
968                        (unsigned long long)cno);
969                 ret = -EINVAL;
970                 goto out;
971         }
972 
973         ret = nilfs_attach_checkpoint(s, cno, false, &root);
974         if (ret) {
975                 printk(KERN_ERR "NILFS: error loading snapshot "
976                        "(checkpoint number=%llu).\n",
977                (unsigned long long)cno);
978                 goto out;
979         }
980         ret = nilfs_get_root_dentry(s, root, root_dentry);
981         nilfs_put_root(root);
982  out:
983         mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
984         return ret;
985 }
986 
987 static int nilfs_tree_was_touched(struct dentry *root_dentry)
988 {
989         return root_dentry->d_count > 1;
990 }
991 
992 /**
993  * nilfs_try_to_shrink_tree() - try to shrink dentries of a checkpoint
994  * @root_dentry: root dentry of the tree to be shrunk
995  *
996  * This function returns true if the tree was in-use.
997  */
998 static int nilfs_try_to_shrink_tree(struct dentry *root_dentry)
999 {
1000         if (have_submounts(root_dentry))
1001                 return true;
1002         shrink_dcache_parent(root_dentry);
1003         return nilfs_tree_was_touched(root_dentry);
1004 }
1005 
1006 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1007 {
1008         struct the_nilfs *nilfs = sb->s_fs_info;
1009         struct nilfs_root *root;
1010         struct inode *inode;
1011         struct dentry *dentry;
1012         int ret;
1013 
1014         if (cno < 0 || cno > nilfs->ns_cno)
1015                 return false;
1016 
1017         if (cno >= nilfs_last_cno(nilfs))
1018                 return true;    /* protect recent checkpoints */
1019 
1020         ret = false;
1021         root = nilfs_lookup_root(nilfs, cno);
1022         if (root) {
1023                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1024                 if (inode) {
1025                         dentry = d_find_alias(inode);
1026                         if (dentry) {
1027                                 if (nilfs_tree_was_touched(dentry))
1028                                         ret = nilfs_try_to_shrink_tree(dentry);
1029                                 dput(dentry);
1030                         }
1031                         iput(inode);
1032                 }
1033                 nilfs_put_root(root);
1034         }
1035         return ret;
1036 }
1037 
1038 /**
1039  * nilfs_fill_super() - initialize a super block instance
1040  * @sb: super_block
1041  * @data: mount options
1042  * @silent: silent mode flag
1043  *
1044  * This function is called exclusively by nilfs->ns_mount_mutex.
1045  * So, the recovery process is protected from other simultaneous mounts.
1046  */
1047 static int
1048 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1049 {
1050         struct the_nilfs *nilfs;
1051         struct nilfs_root *fsroot;
1052         struct backing_dev_info *bdi;
1053         __u64 cno;
1054         int err;
1055 
1056         nilfs = alloc_nilfs(sb->s_bdev);
1057         if (!nilfs)
1058                 return -ENOMEM;
1059 
1060         sb->s_fs_info = nilfs;
1061 
1062         err = init_nilfs(nilfs, sb, (char *)data);
1063         if (err)
1064                 goto failed_nilfs;
1065 
1066         sb->s_op = &nilfs_sops;
1067         sb->s_export_op = &nilfs_export_ops;
1068         sb->s_root = NULL;
1069         sb->s_time_gran = 1;
1070 
1071         bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
1072         sb->s_bdi = bdi ? : &default_backing_dev_info;
1073 
1074         err = load_nilfs(nilfs, sb);
1075         if (err)
1076                 goto failed_nilfs;
1077 
1078         cno = nilfs_last_cno(nilfs);
1079         err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1080         if (err) {
1081                 printk(KERN_ERR "NILFS: error loading last checkpoint "
1082                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
1083                 goto failed_unload;
1084         }
1085 
1086         if (!(sb->s_flags & MS_RDONLY)) {
1087                 err = nilfs_attach_log_writer(sb, fsroot);
1088                 if (err)
1089                         goto failed_checkpoint;
1090         }
1091 
1092         err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1093         if (err)
1094                 goto failed_segctor;
1095 
1096         nilfs_put_root(fsroot);
1097 
1098         if (!(sb->s_flags & MS_RDONLY)) {
1099                 down_write(&nilfs->ns_sem);
1100                 nilfs_setup_super(sb, true);
1101                 up_write(&nilfs->ns_sem);
1102         }
1103 
1104         return 0;
1105 
1106  failed_segctor:
1107         nilfs_detach_log_writer(sb);
1108 
1109  failed_checkpoint:
1110         nilfs_put_root(fsroot);
1111 
1112  failed_unload:
1113         iput(nilfs->ns_sufile);
1114         iput(nilfs->ns_cpfile);
1115         iput(nilfs->ns_dat);
1116 
1117  failed_nilfs:
1118         destroy_nilfs(nilfs);
1119         return err;
1120 }
1121 
1122 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1123 {
1124         struct the_nilfs *nilfs = sb->s_fs_info;
1125         unsigned long old_sb_flags;
1126         unsigned long old_mount_opt;
1127         int err;
1128 
1129         old_sb_flags = sb->s_flags;
1130         old_mount_opt = nilfs->ns_mount_opt;
1131 
1132         if (!parse_options(data, sb, 1)) {
1133                 err = -EINVAL;
1134                 goto restore_opts;
1135         }
1136         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1137 
1138         err = -EINVAL;
1139 
1140         if (!nilfs_valid_fs(nilfs)) {
1141                 printk(KERN_WARNING "NILFS (device %s): couldn't "
1142                        "remount because the filesystem is in an "
1143                        "incomplete recovery state.\n", sb->s_id);
1144                 goto restore_opts;
1145         }
1146 
1147         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1148                 goto out;
1149         if (*flags & MS_RDONLY) {
1150                 /* Shutting down log writer */
1151                 nilfs_detach_log_writer(sb);
1152                 sb->s_flags |= MS_RDONLY;
1153 
1154                 /*
1155                  * Remounting a valid RW partition RDONLY, so set
1156                  * the RDONLY flag and then mark the partition as valid again.
1157                  */
1158                 down_write(&nilfs->ns_sem);
1159                 nilfs_cleanup_super(sb);
1160                 up_write(&nilfs->ns_sem);
1161         } else {
1162                 __u64 features;
1163                 struct nilfs_root *root;
1164 
1165                 /*
1166                  * Mounting a RDONLY partition read-write, so reread and
1167                  * store the current valid flag.  (It may have been changed
1168                  * by fsck since we originally mounted the partition.)
1169                  */
1170                 down_read(&nilfs->ns_sem);
1171                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1172                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
1173                 up_read(&nilfs->ns_sem);
1174                 if (features) {
1175                         printk(KERN_WARNING "NILFS (device %s): couldn't "
1176                                "remount RDWR because of unsupported optional "
1177                                "features (%llx)\n",
1178                                sb->s_id, (unsigned long long)features);
1179                         err = -EROFS;
1180                         goto restore_opts;
1181                 }
1182 
1183                 sb->s_flags &= ~MS_RDONLY;
1184 
1185                 root = NILFS_I(sb->s_root->d_inode)->i_root;
1186                 err = nilfs_attach_log_writer(sb, root);
1187                 if (err)
1188                         goto restore_opts;
1189 
1190                 down_write(&nilfs->ns_sem);
1191                 nilfs_setup_super(sb, true);
1192                 up_write(&nilfs->ns_sem);
1193         }
1194  out:
1195         return 0;
1196 
1197  restore_opts:
1198         sb->s_flags = old_sb_flags;
1199         nilfs->ns_mount_opt = old_mount_opt;
1200         return err;
1201 }
1202 
1203 struct nilfs_super_data {
1204         struct block_device *bdev;
1205         __u64 cno;
1206         int flags;
1207 };
1208 
1209 /**
1210  * nilfs_identify - pre-read mount options needed to identify mount instance
1211  * @data: mount options
1212  * @sd: nilfs_super_data
1213  */
1214 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1215 {
1216         char *p, *options = data;
1217         substring_t args[MAX_OPT_ARGS];
1218         int token;
1219         int ret = 0;
1220 
1221         do {
1222                 p = strsep(&options, ",");
1223                 if (p != NULL && *p) {
1224                         token = match_token(p, tokens, args);
1225                         if (token == Opt_snapshot) {
1226                                 if (!(sd->flags & MS_RDONLY)) {
1227                                         ret++;
1228                                 } else {
1229                                         sd->cno = simple_strtoull(args[0].from,
1230                                                                   NULL, 0);
1231                                         /*
1232                                          * No need to see the end pointer;
1233                                          * match_token() has done syntax
1234                                          * checking.
1235                                          */
1236                                         if (sd->cno == 0)
1237                                                 ret++;
1238                                 }
1239                         }
1240                         if (ret)
1241                                 printk(KERN_ERR
1242                                        "NILFS: invalid mount option: %s\n", p);
1243                 }
1244                 if (!options)
1245                         break;
1246                 BUG_ON(options == data);
1247                 *(options - 1) = ',';
1248         } while (!ret);
1249         return ret;
1250 }
1251 
1252 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1253 {
1254         s->s_bdev = data;
1255         s->s_dev = s->s_bdev->bd_dev;
1256         return 0;
1257 }
1258 
1259 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1260 {
1261         return (void *)s->s_bdev == data;
1262 }
1263 
1264 static struct dentry *
1265 nilfs_mount(struct file_system_type *fs_type, int flags,
1266              const char *dev_name, void *data)
1267 {
1268         struct nilfs_super_data sd;
1269         struct super_block *s;
1270         fmode_t mode = FMODE_READ | FMODE_EXCL;
1271         struct dentry *root_dentry;
1272         int err, s_new = false;
1273 
1274         if (!(flags & MS_RDONLY))
1275                 mode |= FMODE_WRITE;
1276 
1277         sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1278         if (IS_ERR(sd.bdev))
1279                 return ERR_CAST(sd.bdev);
1280 
1281         sd.cno = 0;
1282         sd.flags = flags;
1283         if (nilfs_identify((char *)data, &sd)) {
1284                 err = -EINVAL;
1285                 goto failed;
1286         }
1287 
1288         /*
1289          * once the super is inserted into the list by sget, s_umount
1290          * will protect the lockfs code from trying to start a snapshot
1291          * while we are mounting
1292          */
1293         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1294         if (sd.bdev->bd_fsfreeze_count > 0) {
1295                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1296                 err = -EBUSY;
1297                 goto failed;
1298         }
1299         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, sd.bdev);
1300         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1301         if (IS_ERR(s)) {
1302                 err = PTR_ERR(s);
1303                 goto failed;
1304         }
1305 
1306         if (!s->s_root) {
1307                 char b[BDEVNAME_SIZE];
1308 
1309                 s_new = true;
1310 
1311                 /* New superblock instance created */
1312                 s->s_flags = flags;
1313                 s->s_mode = mode;
1314                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1315                 sb_set_blocksize(s, block_size(sd.bdev));
1316 
1317                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1318                 if (err)
1319                         goto failed_super;
1320 
1321                 s->s_flags |= MS_ACTIVE;
1322         } else if (!sd.cno) {
1323                 int busy = false;
1324 
1325                 if (nilfs_tree_was_touched(s->s_root)) {
1326                         busy = nilfs_try_to_shrink_tree(s->s_root);
1327                         if (busy && (flags ^ s->s_flags) & MS_RDONLY) {
1328                                 printk(KERN_ERR "NILFS: the device already "
1329                                        "has a %s mount.\n",
1330                                        (s->s_flags & MS_RDONLY) ?
1331                                        "read-only" : "read/write");
1332                                 err = -EBUSY;
1333                                 goto failed_super;
1334                         }
1335                 }
1336                 if (!busy) {
1337                         /*
1338                          * Try remount to setup mount states if the current
1339                          * tree is not mounted and only snapshots use this sb.
1340                          */
1341                         err = nilfs_remount(s, &flags, data);
1342                         if (err)
1343                                 goto failed_super;
1344                 }
1345         }
1346 
1347         if (sd.cno) {
1348                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1349                 if (err)
1350                         goto failed_super;
1351         } else {
1352                 root_dentry = dget(s->s_root);
1353         }
1354 
1355         if (!s_new)
1356                 blkdev_put(sd.bdev, mode);
1357 
1358         return root_dentry;
1359 
1360  failed_super:
1361         deactivate_locked_super(s);
1362 
1363  failed:
1364         if (!s_new)
1365                 blkdev_put(sd.bdev, mode);
1366         return ERR_PTR(err);
1367 }
1368 
1369 struct file_system_type nilfs_fs_type = {
1370         .owner    = THIS_MODULE,
1371         .name     = "nilfs2",
1372         .mount    = nilfs_mount,
1373         .kill_sb  = kill_block_super,
1374         .fs_flags = FS_REQUIRES_DEV,
1375 };
1376 
1377 static void nilfs_inode_init_once(void *obj)
1378 {
1379         struct nilfs_inode_info *ii = obj;
1380 
1381         INIT_LIST_HEAD(&ii->i_dirty);
1382 #ifdef CONFIG_NILFS_XATTR
1383         init_rwsem(&ii->xattr_sem);
1384 #endif
1385         address_space_init_once(&ii->i_btnode_cache);
1386         ii->i_bmap = &ii->i_bmap_data;
1387         inode_init_once(&ii->vfs_inode);
1388 }
1389 
1390 static void nilfs_segbuf_init_once(void *obj)
1391 {
1392         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1393 }
1394 
1395 static void nilfs_destroy_cachep(void)
1396 {
1397         if (nilfs_inode_cachep)
1398                 kmem_cache_destroy(nilfs_inode_cachep);
1399         if (nilfs_transaction_cachep)
1400                 kmem_cache_destroy(nilfs_transaction_cachep);
1401         if (nilfs_segbuf_cachep)
1402                 kmem_cache_destroy(nilfs_segbuf_cachep);
1403         if (nilfs_btree_path_cache)
1404                 kmem_cache_destroy(nilfs_btree_path_cache);
1405 }
1406 
1407 static int __init nilfs_init_cachep(void)
1408 {
1409         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1410                         sizeof(struct nilfs_inode_info), 0,
1411                         SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
1412         if (!nilfs_inode_cachep)
1413                 goto fail;
1414 
1415         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1416                         sizeof(struct nilfs_transaction_info), 0,
1417                         SLAB_RECLAIM_ACCOUNT, NULL);
1418         if (!nilfs_transaction_cachep)
1419                 goto fail;
1420 
1421         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1422                         sizeof(struct nilfs_segment_buffer), 0,
1423                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1424         if (!nilfs_segbuf_cachep)
1425                 goto fail;
1426 
1427         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1428                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1429                         0, 0, NULL);
1430         if (!nilfs_btree_path_cache)
1431                 goto fail;
1432 
1433         return 0;
1434 
1435 fail:
1436         nilfs_destroy_cachep();
1437         return -ENOMEM;
1438 }
1439 
1440 static int __init init_nilfs_fs(void)
1441 {
1442         int err;
1443 
1444         err = nilfs_init_cachep();
1445         if (err)
1446                 goto fail;
1447 
1448         err = register_filesystem(&nilfs_fs_type);
1449         if (err)
1450                 goto free_cachep;
1451 
1452         printk(KERN_INFO "NILFS version 2 loaded\n");
1453         return 0;
1454 
1455 free_cachep:
1456         nilfs_destroy_cachep();
1457 fail:
1458         return err;
1459 }
1460 
1461 static void __exit exit_nilfs_fs(void)
1462 {
1463         nilfs_destroy_cachep();
1464         unregister_filesystem(&nilfs_fs_type);
1465 }
1466 
1467 module_init(init_nilfs_fs)
1468 module_exit(exit_nilfs_fs)
1469 

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