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Linux/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  * Written by Ryusuke Konishi.
 17  */
 18 /*
 19  *  linux/fs/ext2/super.c
 20  *
 21  * Copyright (C) 1992, 1993, 1994, 1995
 22  * Remy Card (card@masi.ibp.fr)
 23  * Laboratoire MASI - Institut Blaise Pascal
 24  * Universite Pierre et Marie Curie (Paris VI)
 25  *
 26  *  from
 27  *
 28  *  linux/fs/minix/inode.c
 29  *
 30  *  Copyright (C) 1991, 1992  Linus Torvalds
 31  *
 32  *  Big-endian to little-endian byte-swapping/bitmaps by
 33  *        David S. Miller (davem@caip.rutgers.edu), 1995
 34  */
 35 
 36 #include <linux/module.h>
 37 #include <linux/string.h>
 38 #include <linux/slab.h>
 39 #include <linux/init.h>
 40 #include <linux/blkdev.h>
 41 #include <linux/parser.h>
 42 #include <linux/crc32.h>
 43 #include <linux/vfs.h>
 44 #include <linux/writeback.h>
 45 #include <linux/seq_file.h>
 46 #include <linux/mount.h>
 47 #include "nilfs.h"
 48 #include "export.h"
 49 #include "mdt.h"
 50 #include "alloc.h"
 51 #include "btree.h"
 52 #include "btnode.h"
 53 #include "page.h"
 54 #include "cpfile.h"
 55 #include "sufile.h" /* nilfs_sufile_resize(), nilfs_sufile_set_alloc_range() */
 56 #include "ifile.h"
 57 #include "dat.h"
 58 #include "segment.h"
 59 #include "segbuf.h"
 60 
 61 MODULE_AUTHOR("NTT Corp.");
 62 MODULE_DESCRIPTION("A New Implementation of the Log-structured Filesystem "
 63                    "(NILFS)");
 64 MODULE_LICENSE("GPL");
 65 
 66 static struct kmem_cache *nilfs_inode_cachep;
 67 struct kmem_cache *nilfs_transaction_cachep;
 68 struct kmem_cache *nilfs_segbuf_cachep;
 69 struct kmem_cache *nilfs_btree_path_cache;
 70 
 71 static int nilfs_setup_super(struct super_block *sb, int is_mount);
 72 static int nilfs_remount(struct super_block *sb, int *flags, char *data);
 73 
 74 void __nilfs_msg(struct super_block *sb, const char *level, const char *fmt,
 75                  ...)
 76 {
 77         struct va_format vaf;
 78         va_list args;
 79 
 80         va_start(args, fmt);
 81         vaf.fmt = fmt;
 82         vaf.va = &args;
 83         if (sb)
 84                 printk("%sNILFS (%s): %pV\n", level, sb->s_id, &vaf);
 85         else
 86                 printk("%sNILFS: %pV\n", level, &vaf);
 87         va_end(args);
 88 }
 89 
 90 static void nilfs_set_error(struct super_block *sb)
 91 {
 92         struct the_nilfs *nilfs = sb->s_fs_info;
 93         struct nilfs_super_block **sbp;
 94 
 95         down_write(&nilfs->ns_sem);
 96         if (!(nilfs->ns_mount_state & NILFS_ERROR_FS)) {
 97                 nilfs->ns_mount_state |= NILFS_ERROR_FS;
 98                 sbp = nilfs_prepare_super(sb, 0);
 99                 if (likely(sbp)) {
100                         sbp[0]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
101                         if (sbp[1])
102                                 sbp[1]->s_state |= cpu_to_le16(NILFS_ERROR_FS);
103                         nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
104                 }
105         }
106         up_write(&nilfs->ns_sem);
107 }
108 
109 /**
110  * __nilfs_error() - report failure condition on a filesystem
111  *
112  * __nilfs_error() sets an ERROR_FS flag on the superblock as well as
113  * reporting an error message.  This function should be called when
114  * NILFS detects incoherences or defects of meta data on disk.
115  *
116  * This implements the body of nilfs_error() macro.  Normally,
117  * nilfs_error() should be used.  As for sustainable errors such as a
118  * single-shot I/O error, nilfs_msg() should be used instead.
119  *
120  * Callers should not add a trailing newline since this will do it.
121  */
122 void __nilfs_error(struct super_block *sb, const char *function,
123                    const char *fmt, ...)
124 {
125         struct the_nilfs *nilfs = sb->s_fs_info;
126         struct va_format vaf;
127         va_list args;
128 
129         va_start(args, fmt);
130 
131         vaf.fmt = fmt;
132         vaf.va = &args;
133 
134         printk(KERN_CRIT "NILFS error (device %s): %s: %pV\n",
135                sb->s_id, function, &vaf);
136 
137         va_end(args);
138 
139         if (!(sb->s_flags & MS_RDONLY)) {
140                 nilfs_set_error(sb);
141 
142                 if (nilfs_test_opt(nilfs, ERRORS_RO)) {
143                         printk(KERN_CRIT "Remounting filesystem read-only\n");
144                         sb->s_flags |= MS_RDONLY;
145                 }
146         }
147 
148         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
149                 panic("NILFS (device %s): panic forced after error\n",
150                       sb->s_id);
151 }
152 
153 struct inode *nilfs_alloc_inode(struct super_block *sb)
154 {
155         struct nilfs_inode_info *ii;
156 
157         ii = kmem_cache_alloc(nilfs_inode_cachep, GFP_NOFS);
158         if (!ii)
159                 return NULL;
160         ii->i_bh = NULL;
161         ii->i_state = 0;
162         ii->i_cno = 0;
163         ii->vfs_inode.i_version = 1;
164         nilfs_mapping_init(&ii->i_btnode_cache, &ii->vfs_inode);
165         return &ii->vfs_inode;
166 }
167 
168 static void nilfs_i_callback(struct rcu_head *head)
169 {
170         struct inode *inode = container_of(head, struct inode, i_rcu);
171 
172         if (nilfs_is_metadata_file_inode(inode))
173                 nilfs_mdt_destroy(inode);
174 
175         kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
176 }
177 
178 void nilfs_destroy_inode(struct inode *inode)
179 {
180         call_rcu(&inode->i_rcu, nilfs_i_callback);
181 }
182 
183 static int nilfs_sync_super(struct super_block *sb, int flag)
184 {
185         struct the_nilfs *nilfs = sb->s_fs_info;
186         int err;
187 
188  retry:
189         set_buffer_dirty(nilfs->ns_sbh[0]);
190         if (nilfs_test_opt(nilfs, BARRIER)) {
191                 err = __sync_dirty_buffer(nilfs->ns_sbh[0],
192                                           WRITE_SYNC | WRITE_FLUSH_FUA);
193         } else {
194                 err = sync_dirty_buffer(nilfs->ns_sbh[0]);
195         }
196 
197         if (unlikely(err)) {
198                 nilfs_msg(sb, KERN_ERR, "unable to write superblock: err=%d",
199                           err);
200                 if (err == -EIO && nilfs->ns_sbh[1]) {
201                         /*
202                          * sbp[0] points to newer log than sbp[1],
203                          * so copy sbp[0] to sbp[1] to take over sbp[0].
204                          */
205                         memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
206                                nilfs->ns_sbsize);
207                         nilfs_fall_back_super_block(nilfs);
208                         goto retry;
209                 }
210         } else {
211                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
212 
213                 nilfs->ns_sbwcount++;
214 
215                 /*
216                  * The latest segment becomes trailable from the position
217                  * written in superblock.
218                  */
219                 clear_nilfs_discontinued(nilfs);
220 
221                 /* update GC protection for recent segments */
222                 if (nilfs->ns_sbh[1]) {
223                         if (flag == NILFS_SB_COMMIT_ALL) {
224                                 set_buffer_dirty(nilfs->ns_sbh[1]);
225                                 if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
226                                         goto out;
227                         }
228                         if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
229                             le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
230                                 sbp = nilfs->ns_sbp[1];
231                 }
232 
233                 spin_lock(&nilfs->ns_last_segment_lock);
234                 nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
235                 spin_unlock(&nilfs->ns_last_segment_lock);
236         }
237  out:
238         return err;
239 }
240 
241 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
242                           struct the_nilfs *nilfs)
243 {
244         sector_t nfreeblocks;
245 
246         /* nilfs->ns_sem must be locked by the caller. */
247         nilfs_count_free_blocks(nilfs, &nfreeblocks);
248         sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
249 
250         spin_lock(&nilfs->ns_last_segment_lock);
251         sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
252         sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
253         sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
254         spin_unlock(&nilfs->ns_last_segment_lock);
255 }
256 
257 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
258                                                int flip)
259 {
260         struct the_nilfs *nilfs = sb->s_fs_info;
261         struct nilfs_super_block **sbp = nilfs->ns_sbp;
262 
263         /* nilfs->ns_sem must be locked by the caller. */
264         if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
265                 if (sbp[1] &&
266                     sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
267                         memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
268                 } else {
269                         nilfs_msg(sb, KERN_CRIT, "superblock broke");
270                         return NULL;
271                 }
272         } else if (sbp[1] &&
273                    sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
274                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
275         }
276 
277         if (flip && sbp[1])
278                 nilfs_swap_super_block(nilfs);
279 
280         return sbp;
281 }
282 
283 int nilfs_commit_super(struct super_block *sb, int flag)
284 {
285         struct the_nilfs *nilfs = sb->s_fs_info;
286         struct nilfs_super_block **sbp = nilfs->ns_sbp;
287         time_t t;
288 
289         /* nilfs->ns_sem must be locked by the caller. */
290         t = get_seconds();
291         nilfs->ns_sbwtime = t;
292         sbp[0]->s_wtime = cpu_to_le64(t);
293         sbp[0]->s_sum = 0;
294         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
295                                              (unsigned char *)sbp[0],
296                                              nilfs->ns_sbsize));
297         if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
298                 sbp[1]->s_wtime = sbp[0]->s_wtime;
299                 sbp[1]->s_sum = 0;
300                 sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
301                                             (unsigned char *)sbp[1],
302                                             nilfs->ns_sbsize));
303         }
304         clear_nilfs_sb_dirty(nilfs);
305         nilfs->ns_flushed_device = 1;
306         /* make sure store to ns_flushed_device cannot be reordered */
307         smp_wmb();
308         return nilfs_sync_super(sb, flag);
309 }
310 
311 /**
312  * nilfs_cleanup_super() - write filesystem state for cleanup
313  * @sb: super block instance to be unmounted or degraded to read-only
314  *
315  * This function restores state flags in the on-disk super block.
316  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
317  * filesystem was not clean previously.
318  */
319 int nilfs_cleanup_super(struct super_block *sb)
320 {
321         struct the_nilfs *nilfs = sb->s_fs_info;
322         struct nilfs_super_block **sbp;
323         int flag = NILFS_SB_COMMIT;
324         int ret = -EIO;
325 
326         sbp = nilfs_prepare_super(sb, 0);
327         if (sbp) {
328                 sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
329                 nilfs_set_log_cursor(sbp[0], nilfs);
330                 if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
331                         /*
332                          * make the "clean" flag also to the opposite
333                          * super block if both super blocks point to
334                          * the same checkpoint.
335                          */
336                         sbp[1]->s_state = sbp[0]->s_state;
337                         flag = NILFS_SB_COMMIT_ALL;
338                 }
339                 ret = nilfs_commit_super(sb, flag);
340         }
341         return ret;
342 }
343 
344 /**
345  * nilfs_move_2nd_super - relocate secondary super block
346  * @sb: super block instance
347  * @sb2off: new offset of the secondary super block (in bytes)
348  */
349 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
350 {
351         struct the_nilfs *nilfs = sb->s_fs_info;
352         struct buffer_head *nsbh;
353         struct nilfs_super_block *nsbp;
354         sector_t blocknr, newblocknr;
355         unsigned long offset;
356         int sb2i;  /* array index of the secondary superblock */
357         int ret = 0;
358 
359         /* nilfs->ns_sem must be locked by the caller. */
360         if (nilfs->ns_sbh[1] &&
361             nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
362                 sb2i = 1;
363                 blocknr = nilfs->ns_sbh[1]->b_blocknr;
364         } else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
365                 sb2i = 0;
366                 blocknr = nilfs->ns_sbh[0]->b_blocknr;
367         } else {
368                 sb2i = -1;
369                 blocknr = 0;
370         }
371         if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
372                 goto out;  /* super block location is unchanged */
373 
374         /* Get new super block buffer */
375         newblocknr = sb2off >> nilfs->ns_blocksize_bits;
376         offset = sb2off & (nilfs->ns_blocksize - 1);
377         nsbh = sb_getblk(sb, newblocknr);
378         if (!nsbh) {
379                 nilfs_msg(sb, KERN_WARNING,
380                           "unable to move secondary superblock to block %llu",
381                           (unsigned long long)newblocknr);
382                 ret = -EIO;
383                 goto out;
384         }
385         nsbp = (void *)nsbh->b_data + offset;
386         memset(nsbp, 0, nilfs->ns_blocksize);
387 
388         if (sb2i >= 0) {
389                 memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
390                 brelse(nilfs->ns_sbh[sb2i]);
391                 nilfs->ns_sbh[sb2i] = nsbh;
392                 nilfs->ns_sbp[sb2i] = nsbp;
393         } else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
394                 /* secondary super block will be restored to index 1 */
395                 nilfs->ns_sbh[1] = nsbh;
396                 nilfs->ns_sbp[1] = nsbp;
397         } else {
398                 brelse(nsbh);
399         }
400 out:
401         return ret;
402 }
403 
404 /**
405  * nilfs_resize_fs - resize the filesystem
406  * @sb: super block instance
407  * @newsize: new size of the filesystem (in bytes)
408  */
409 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
410 {
411         struct the_nilfs *nilfs = sb->s_fs_info;
412         struct nilfs_super_block **sbp;
413         __u64 devsize, newnsegs;
414         loff_t sb2off;
415         int ret;
416 
417         ret = -ERANGE;
418         devsize = i_size_read(sb->s_bdev->bd_inode);
419         if (newsize > devsize)
420                 goto out;
421 
422         /*
423          * Write lock is required to protect some functions depending
424          * on the number of segments, the number of reserved segments,
425          * and so forth.
426          */
427         down_write(&nilfs->ns_segctor_sem);
428 
429         sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
430         newnsegs = sb2off >> nilfs->ns_blocksize_bits;
431         do_div(newnsegs, nilfs->ns_blocks_per_segment);
432 
433         ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
434         up_write(&nilfs->ns_segctor_sem);
435         if (ret < 0)
436                 goto out;
437 
438         ret = nilfs_construct_segment(sb);
439         if (ret < 0)
440                 goto out;
441 
442         down_write(&nilfs->ns_sem);
443         nilfs_move_2nd_super(sb, sb2off);
444         ret = -EIO;
445         sbp = nilfs_prepare_super(sb, 0);
446         if (likely(sbp)) {
447                 nilfs_set_log_cursor(sbp[0], nilfs);
448                 /*
449                  * Drop NILFS_RESIZE_FS flag for compatibility with
450                  * mount-time resize which may be implemented in a
451                  * future release.
452                  */
453                 sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
454                                               ~NILFS_RESIZE_FS);
455                 sbp[0]->s_dev_size = cpu_to_le64(newsize);
456                 sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
457                 if (sbp[1])
458                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
459                 ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
460         }
461         up_write(&nilfs->ns_sem);
462 
463         /*
464          * Reset the range of allocatable segments last.  This order
465          * is important in the case of expansion because the secondary
466          * superblock must be protected from log write until migration
467          * completes.
468          */
469         if (!ret)
470                 nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
471 out:
472         return ret;
473 }
474 
475 static void nilfs_put_super(struct super_block *sb)
476 {
477         struct the_nilfs *nilfs = sb->s_fs_info;
478 
479         nilfs_detach_log_writer(sb);
480 
481         if (!(sb->s_flags & MS_RDONLY)) {
482                 down_write(&nilfs->ns_sem);
483                 nilfs_cleanup_super(sb);
484                 up_write(&nilfs->ns_sem);
485         }
486 
487         iput(nilfs->ns_sufile);
488         iput(nilfs->ns_cpfile);
489         iput(nilfs->ns_dat);
490 
491         destroy_nilfs(nilfs);
492         sb->s_fs_info = NULL;
493 }
494 
495 static int nilfs_sync_fs(struct super_block *sb, int wait)
496 {
497         struct the_nilfs *nilfs = sb->s_fs_info;
498         struct nilfs_super_block **sbp;
499         int err = 0;
500 
501         /* This function is called when super block should be written back */
502         if (wait)
503                 err = nilfs_construct_segment(sb);
504 
505         down_write(&nilfs->ns_sem);
506         if (nilfs_sb_dirty(nilfs)) {
507                 sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
508                 if (likely(sbp)) {
509                         nilfs_set_log_cursor(sbp[0], nilfs);
510                         nilfs_commit_super(sb, NILFS_SB_COMMIT);
511                 }
512         }
513         up_write(&nilfs->ns_sem);
514 
515         if (!err)
516                 err = nilfs_flush_device(nilfs);
517 
518         return err;
519 }
520 
521 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
522                             struct nilfs_root **rootp)
523 {
524         struct the_nilfs *nilfs = sb->s_fs_info;
525         struct nilfs_root *root;
526         struct nilfs_checkpoint *raw_cp;
527         struct buffer_head *bh_cp;
528         int err = -ENOMEM;
529 
530         root = nilfs_find_or_create_root(
531                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
532         if (!root)
533                 return err;
534 
535         if (root->ifile)
536                 goto reuse; /* already attached checkpoint */
537 
538         down_read(&nilfs->ns_segctor_sem);
539         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
540                                           &bh_cp);
541         up_read(&nilfs->ns_segctor_sem);
542         if (unlikely(err)) {
543                 if (err == -ENOENT || err == -EINVAL) {
544                         nilfs_msg(sb, KERN_ERR,
545                                   "Invalid checkpoint (checkpoint number=%llu)",
546                                   (unsigned long long)cno);
547                         err = -EINVAL;
548                 }
549                 goto failed;
550         }
551 
552         err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
553                                &raw_cp->cp_ifile_inode, &root->ifile);
554         if (err)
555                 goto failed_bh;
556 
557         atomic64_set(&root->inodes_count,
558                         le64_to_cpu(raw_cp->cp_inodes_count));
559         atomic64_set(&root->blocks_count,
560                         le64_to_cpu(raw_cp->cp_blocks_count));
561 
562         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
563 
564  reuse:
565         *rootp = root;
566         return 0;
567 
568  failed_bh:
569         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
570  failed:
571         nilfs_put_root(root);
572 
573         return err;
574 }
575 
576 static int nilfs_freeze(struct super_block *sb)
577 {
578         struct the_nilfs *nilfs = sb->s_fs_info;
579         int err;
580 
581         if (sb->s_flags & MS_RDONLY)
582                 return 0;
583 
584         /* Mark super block clean */
585         down_write(&nilfs->ns_sem);
586         err = nilfs_cleanup_super(sb);
587         up_write(&nilfs->ns_sem);
588         return err;
589 }
590 
591 static int nilfs_unfreeze(struct super_block *sb)
592 {
593         struct the_nilfs *nilfs = sb->s_fs_info;
594 
595         if (sb->s_flags & MS_RDONLY)
596                 return 0;
597 
598         down_write(&nilfs->ns_sem);
599         nilfs_setup_super(sb, false);
600         up_write(&nilfs->ns_sem);
601         return 0;
602 }
603 
604 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
605 {
606         struct super_block *sb = dentry->d_sb;
607         struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
608         struct the_nilfs *nilfs = root->nilfs;
609         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
610         unsigned long long blocks;
611         unsigned long overhead;
612         unsigned long nrsvblocks;
613         sector_t nfreeblocks;
614         u64 nmaxinodes, nfreeinodes;
615         int err;
616 
617         /*
618          * Compute all of the segment blocks
619          *
620          * The blocks before first segment and after last segment
621          * are excluded.
622          */
623         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
624                 - nilfs->ns_first_data_block;
625         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
626 
627         /*
628          * Compute the overhead
629          *
630          * When distributing meta data blocks outside segment structure,
631          * We must count them as the overhead.
632          */
633         overhead = 0;
634 
635         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
636         if (unlikely(err))
637                 return err;
638 
639         err = nilfs_ifile_count_free_inodes(root->ifile,
640                                             &nmaxinodes, &nfreeinodes);
641         if (unlikely(err)) {
642                 nilfs_msg(sb, KERN_WARNING,
643                           "failed to count free inodes: err=%d", err);
644                 if (err == -ERANGE) {
645                         /*
646                          * If nilfs_palloc_count_max_entries() returns
647                          * -ERANGE error code then we simply treat
648                          * curent inodes count as maximum possible and
649                          * zero as free inodes value.
650                          */
651                         nmaxinodes = atomic64_read(&root->inodes_count);
652                         nfreeinodes = 0;
653                         err = 0;
654                 } else
655                         return err;
656         }
657 
658         buf->f_type = NILFS_SUPER_MAGIC;
659         buf->f_bsize = sb->s_blocksize;
660         buf->f_blocks = blocks - overhead;
661         buf->f_bfree = nfreeblocks;
662         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
663                 (buf->f_bfree - nrsvblocks) : 0;
664         buf->f_files = nmaxinodes;
665         buf->f_ffree = nfreeinodes;
666         buf->f_namelen = NILFS_NAME_LEN;
667         buf->f_fsid.val[0] = (u32)id;
668         buf->f_fsid.val[1] = (u32)(id >> 32);
669 
670         return 0;
671 }
672 
673 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
674 {
675         struct super_block *sb = dentry->d_sb;
676         struct the_nilfs *nilfs = sb->s_fs_info;
677         struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
678 
679         if (!nilfs_test_opt(nilfs, BARRIER))
680                 seq_puts(seq, ",nobarrier");
681         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
682                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
683         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
684                 seq_puts(seq, ",errors=panic");
685         if (nilfs_test_opt(nilfs, ERRORS_CONT))
686                 seq_puts(seq, ",errors=continue");
687         if (nilfs_test_opt(nilfs, STRICT_ORDER))
688                 seq_puts(seq, ",order=strict");
689         if (nilfs_test_opt(nilfs, NORECOVERY))
690                 seq_puts(seq, ",norecovery");
691         if (nilfs_test_opt(nilfs, DISCARD))
692                 seq_puts(seq, ",discard");
693 
694         return 0;
695 }
696 
697 static const struct super_operations nilfs_sops = {
698         .alloc_inode    = nilfs_alloc_inode,
699         .destroy_inode  = nilfs_destroy_inode,
700         .dirty_inode    = nilfs_dirty_inode,
701         .evict_inode    = nilfs_evict_inode,
702         .put_super      = nilfs_put_super,
703         .sync_fs        = nilfs_sync_fs,
704         .freeze_fs      = nilfs_freeze,
705         .unfreeze_fs    = nilfs_unfreeze,
706         .statfs         = nilfs_statfs,
707         .remount_fs     = nilfs_remount,
708         .show_options = nilfs_show_options
709 };
710 
711 enum {
712         Opt_err_cont, Opt_err_panic, Opt_err_ro,
713         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
714         Opt_discard, Opt_nodiscard, Opt_err,
715 };
716 
717 static match_table_t tokens = {
718         {Opt_err_cont, "errors=continue"},
719         {Opt_err_panic, "errors=panic"},
720         {Opt_err_ro, "errors=remount-ro"},
721         {Opt_barrier, "barrier"},
722         {Opt_nobarrier, "nobarrier"},
723         {Opt_snapshot, "cp=%u"},
724         {Opt_order, "order=%s"},
725         {Opt_norecovery, "norecovery"},
726         {Opt_discard, "discard"},
727         {Opt_nodiscard, "nodiscard"},
728         {Opt_err, NULL}
729 };
730 
731 static int parse_options(char *options, struct super_block *sb, int is_remount)
732 {
733         struct the_nilfs *nilfs = sb->s_fs_info;
734         char *p;
735         substring_t args[MAX_OPT_ARGS];
736 
737         if (!options)
738                 return 1;
739 
740         while ((p = strsep(&options, ",")) != NULL) {
741                 int token;
742 
743                 if (!*p)
744                         continue;
745 
746                 token = match_token(p, tokens, args);
747                 switch (token) {
748                 case Opt_barrier:
749                         nilfs_set_opt(nilfs, BARRIER);
750                         break;
751                 case Opt_nobarrier:
752                         nilfs_clear_opt(nilfs, BARRIER);
753                         break;
754                 case Opt_order:
755                         if (strcmp(args[0].from, "relaxed") == 0)
756                                 /* Ordered data semantics */
757                                 nilfs_clear_opt(nilfs, STRICT_ORDER);
758                         else if (strcmp(args[0].from, "strict") == 0)
759                                 /* Strict in-order semantics */
760                                 nilfs_set_opt(nilfs, STRICT_ORDER);
761                         else
762                                 return 0;
763                         break;
764                 case Opt_err_panic:
765                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
766                         break;
767                 case Opt_err_ro:
768                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
769                         break;
770                 case Opt_err_cont:
771                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
772                         break;
773                 case Opt_snapshot:
774                         if (is_remount) {
775                                 nilfs_msg(sb, KERN_ERR,
776                                           "\"%s\" option is invalid for remount",
777                                           p);
778                                 return 0;
779                         }
780                         break;
781                 case Opt_norecovery:
782                         nilfs_set_opt(nilfs, NORECOVERY);
783                         break;
784                 case Opt_discard:
785                         nilfs_set_opt(nilfs, DISCARD);
786                         break;
787                 case Opt_nodiscard:
788                         nilfs_clear_opt(nilfs, DISCARD);
789                         break;
790                 default:
791                         nilfs_msg(sb, KERN_ERR,
792                                   "unrecognized mount option \"%s\"", p);
793                         return 0;
794                 }
795         }
796         return 1;
797 }
798 
799 static inline void
800 nilfs_set_default_options(struct super_block *sb,
801                           struct nilfs_super_block *sbp)
802 {
803         struct the_nilfs *nilfs = sb->s_fs_info;
804 
805         nilfs->ns_mount_opt =
806                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
807 }
808 
809 static int nilfs_setup_super(struct super_block *sb, int is_mount)
810 {
811         struct the_nilfs *nilfs = sb->s_fs_info;
812         struct nilfs_super_block **sbp;
813         int max_mnt_count;
814         int mnt_count;
815 
816         /* nilfs->ns_sem must be locked by the caller. */
817         sbp = nilfs_prepare_super(sb, 0);
818         if (!sbp)
819                 return -EIO;
820 
821         if (!is_mount)
822                 goto skip_mount_setup;
823 
824         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
825         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
826 
827         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
828                 nilfs_msg(sb, KERN_WARNING, "mounting fs with errors");
829 #if 0
830         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
831                 nilfs_msg(sb, KERN_WARNING, "maximal mount count reached");
832 #endif
833         }
834         if (!max_mnt_count)
835                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
836 
837         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
838         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
839 
840 skip_mount_setup:
841         sbp[0]->s_state =
842                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
843         /* synchronize sbp[1] with sbp[0] */
844         if (sbp[1])
845                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
846         return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
847 }
848 
849 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
850                                                  u64 pos, int blocksize,
851                                                  struct buffer_head **pbh)
852 {
853         unsigned long long sb_index = pos;
854         unsigned long offset;
855 
856         offset = do_div(sb_index, blocksize);
857         *pbh = sb_bread(sb, sb_index);
858         if (!*pbh)
859                 return NULL;
860         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
861 }
862 
863 int nilfs_store_magic_and_option(struct super_block *sb,
864                                  struct nilfs_super_block *sbp,
865                                  char *data)
866 {
867         struct the_nilfs *nilfs = sb->s_fs_info;
868 
869         sb->s_magic = le16_to_cpu(sbp->s_magic);
870 
871         /* FS independent flags */
872 #ifdef NILFS_ATIME_DISABLE
873         sb->s_flags |= MS_NOATIME;
874 #endif
875 
876         nilfs_set_default_options(sb, sbp);
877 
878         nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
879         nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
880         nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
881         nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
882 
883         return !parse_options(data, sb, 0) ? -EINVAL : 0;
884 }
885 
886 int nilfs_check_feature_compatibility(struct super_block *sb,
887                                       struct nilfs_super_block *sbp)
888 {
889         __u64 features;
890 
891         features = le64_to_cpu(sbp->s_feature_incompat) &
892                 ~NILFS_FEATURE_INCOMPAT_SUPP;
893         if (features) {
894                 nilfs_msg(sb, KERN_ERR,
895                           "couldn't mount because of unsupported optional features (%llx)",
896                           (unsigned long long)features);
897                 return -EINVAL;
898         }
899         features = le64_to_cpu(sbp->s_feature_compat_ro) &
900                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
901         if (!(sb->s_flags & MS_RDONLY) && features) {
902                 nilfs_msg(sb, KERN_ERR,
903                           "couldn't mount RDWR because of unsupported optional features (%llx)",
904                           (unsigned long long)features);
905                 return -EINVAL;
906         }
907         return 0;
908 }
909 
910 static int nilfs_get_root_dentry(struct super_block *sb,
911                                  struct nilfs_root *root,
912                                  struct dentry **root_dentry)
913 {
914         struct inode *inode;
915         struct dentry *dentry;
916         int ret = 0;
917 
918         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
919         if (IS_ERR(inode)) {
920                 ret = PTR_ERR(inode);
921                 nilfs_msg(sb, KERN_ERR, "error %d getting root inode", ret);
922                 goto out;
923         }
924         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
925                 iput(inode);
926                 nilfs_msg(sb, KERN_ERR, "corrupt root inode");
927                 ret = -EINVAL;
928                 goto out;
929         }
930 
931         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
932                 dentry = d_find_alias(inode);
933                 if (!dentry) {
934                         dentry = d_make_root(inode);
935                         if (!dentry) {
936                                 ret = -ENOMEM;
937                                 goto failed_dentry;
938                         }
939                 } else {
940                         iput(inode);
941                 }
942         } else {
943                 dentry = d_obtain_root(inode);
944                 if (IS_ERR(dentry)) {
945                         ret = PTR_ERR(dentry);
946                         goto failed_dentry;
947                 }
948         }
949         *root_dentry = dentry;
950  out:
951         return ret;
952 
953  failed_dentry:
954         nilfs_msg(sb, KERN_ERR, "error %d getting root dentry", ret);
955         goto out;
956 }
957 
958 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
959                                  struct dentry **root_dentry)
960 {
961         struct the_nilfs *nilfs = s->s_fs_info;
962         struct nilfs_root *root;
963         int ret;
964 
965         mutex_lock(&nilfs->ns_snapshot_mount_mutex);
966 
967         down_read(&nilfs->ns_segctor_sem);
968         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
969         up_read(&nilfs->ns_segctor_sem);
970         if (ret < 0) {
971                 ret = (ret == -ENOENT) ? -EINVAL : ret;
972                 goto out;
973         } else if (!ret) {
974                 nilfs_msg(s, KERN_ERR,
975                           "The specified checkpoint is not a snapshot (checkpoint number=%llu)",
976                           (unsigned long long)cno);
977                 ret = -EINVAL;
978                 goto out;
979         }
980 
981         ret = nilfs_attach_checkpoint(s, cno, false, &root);
982         if (ret) {
983                 nilfs_msg(s, KERN_ERR,
984                           "error %d while loading snapshot (checkpoint number=%llu)",
985                           ret, (unsigned long long)cno);
986                 goto out;
987         }
988         ret = nilfs_get_root_dentry(s, root, root_dentry);
989         nilfs_put_root(root);
990  out:
991         mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
992         return ret;
993 }
994 
995 /**
996  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
997  * @root_dentry: root dentry of the tree to be shrunk
998  *
999  * This function returns true if the tree was in-use.
1000  */
1001 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
1002 {
1003         shrink_dcache_parent(root_dentry);
1004         return d_count(root_dentry) > 1;
1005 }
1006 
1007 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1008 {
1009         struct the_nilfs *nilfs = sb->s_fs_info;
1010         struct nilfs_root *root;
1011         struct inode *inode;
1012         struct dentry *dentry;
1013         int ret;
1014 
1015         if (cno > nilfs->ns_cno)
1016                 return false;
1017 
1018         if (cno >= nilfs_last_cno(nilfs))
1019                 return true;    /* protect recent checkpoints */
1020 
1021         ret = false;
1022         root = nilfs_lookup_root(nilfs, cno);
1023         if (root) {
1024                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1025                 if (inode) {
1026                         dentry = d_find_alias(inode);
1027                         if (dentry) {
1028                                 ret = nilfs_tree_is_busy(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         __u64 cno;
1053         int err;
1054 
1055         nilfs = alloc_nilfs(sb);
1056         if (!nilfs)
1057                 return -ENOMEM;
1058 
1059         sb->s_fs_info = nilfs;
1060 
1061         err = init_nilfs(nilfs, sb, (char *)data);
1062         if (err)
1063                 goto failed_nilfs;
1064 
1065         sb->s_op = &nilfs_sops;
1066         sb->s_export_op = &nilfs_export_ops;
1067         sb->s_root = NULL;
1068         sb->s_time_gran = 1;
1069         sb->s_max_links = NILFS_LINK_MAX;
1070 
1071         sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
1072 
1073         err = load_nilfs(nilfs, sb);
1074         if (err)
1075                 goto failed_nilfs;
1076 
1077         cno = nilfs_last_cno(nilfs);
1078         err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1079         if (err) {
1080                 nilfs_msg(sb, KERN_ERR,
1081                           "error %d while loading last checkpoint (checkpoint number=%llu)",
1082                           err, (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         sync_filesystem(sb);
1130         old_sb_flags = sb->s_flags;
1131         old_mount_opt = nilfs->ns_mount_opt;
1132 
1133         if (!parse_options(data, sb, 1)) {
1134                 err = -EINVAL;
1135                 goto restore_opts;
1136         }
1137         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1138 
1139         err = -EINVAL;
1140 
1141         if (!nilfs_valid_fs(nilfs)) {
1142                 nilfs_msg(sb, KERN_WARNING,
1143                           "couldn't remount because the filesystem is in an incomplete recovery state");
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                         nilfs_msg(sb, KERN_WARNING,
1176                                   "couldn't remount RDWR because of unsupported optional features (%llx)",
1177                                   (unsigned long long)features);
1178                         err = -EROFS;
1179                         goto restore_opts;
1180                 }
1181 
1182                 sb->s_flags &= ~MS_RDONLY;
1183 
1184                 root = NILFS_I(d_inode(sb->s_root))->i_root;
1185                 err = nilfs_attach_log_writer(sb, root);
1186                 if (err)
1187                         goto restore_opts;
1188 
1189                 down_write(&nilfs->ns_sem);
1190                 nilfs_setup_super(sb, true);
1191                 up_write(&nilfs->ns_sem);
1192         }
1193  out:
1194         return 0;
1195 
1196  restore_opts:
1197         sb->s_flags = old_sb_flags;
1198         nilfs->ns_mount_opt = old_mount_opt;
1199         return err;
1200 }
1201 
1202 struct nilfs_super_data {
1203         struct block_device *bdev;
1204         __u64 cno;
1205         int flags;
1206 };
1207 
1208 static int nilfs_parse_snapshot_option(const char *option,
1209                                        const substring_t *arg,
1210                                        struct nilfs_super_data *sd)
1211 {
1212         unsigned long long val;
1213         const char *msg = NULL;
1214         int err;
1215 
1216         if (!(sd->flags & MS_RDONLY)) {
1217                 msg = "read-only option is not specified";
1218                 goto parse_error;
1219         }
1220 
1221         err = kstrtoull(arg->from, 0, &val);
1222         if (err) {
1223                 if (err == -ERANGE)
1224                         msg = "too large checkpoint number";
1225                 else
1226                         msg = "malformed argument";
1227                 goto parse_error;
1228         } else if (val == 0) {
1229                 msg = "invalid checkpoint number 0";
1230                 goto parse_error;
1231         }
1232         sd->cno = val;
1233         return 0;
1234 
1235 parse_error:
1236         nilfs_msg(NULL, KERN_ERR, "invalid option \"%s\": %s", option, msg);
1237         return 1;
1238 }
1239 
1240 /**
1241  * nilfs_identify - pre-read mount options needed to identify mount instance
1242  * @data: mount options
1243  * @sd: nilfs_super_data
1244  */
1245 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1246 {
1247         char *p, *options = data;
1248         substring_t args[MAX_OPT_ARGS];
1249         int token;
1250         int ret = 0;
1251 
1252         do {
1253                 p = strsep(&options, ",");
1254                 if (p != NULL && *p) {
1255                         token = match_token(p, tokens, args);
1256                         if (token == Opt_snapshot)
1257                                 ret = nilfs_parse_snapshot_option(p, &args[0],
1258                                                                   sd);
1259                 }
1260                 if (!options)
1261                         break;
1262                 BUG_ON(options == data);
1263                 *(options - 1) = ',';
1264         } while (!ret);
1265         return ret;
1266 }
1267 
1268 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1269 {
1270         s->s_bdev = data;
1271         s->s_dev = s->s_bdev->bd_dev;
1272         return 0;
1273 }
1274 
1275 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1276 {
1277         return (void *)s->s_bdev == data;
1278 }
1279 
1280 static struct dentry *
1281 nilfs_mount(struct file_system_type *fs_type, int flags,
1282              const char *dev_name, void *data)
1283 {
1284         struct nilfs_super_data sd;
1285         struct super_block *s;
1286         fmode_t mode = FMODE_READ | FMODE_EXCL;
1287         struct dentry *root_dentry;
1288         int err, s_new = false;
1289 
1290         if (!(flags & MS_RDONLY))
1291                 mode |= FMODE_WRITE;
1292 
1293         sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1294         if (IS_ERR(sd.bdev))
1295                 return ERR_CAST(sd.bdev);
1296 
1297         sd.cno = 0;
1298         sd.flags = flags;
1299         if (nilfs_identify((char *)data, &sd)) {
1300                 err = -EINVAL;
1301                 goto failed;
1302         }
1303 
1304         /*
1305          * once the super is inserted into the list by sget, s_umount
1306          * will protect the lockfs code from trying to start a snapshot
1307          * while we are mounting
1308          */
1309         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1310         if (sd.bdev->bd_fsfreeze_count > 0) {
1311                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1312                 err = -EBUSY;
1313                 goto failed;
1314         }
1315         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1316                  sd.bdev);
1317         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1318         if (IS_ERR(s)) {
1319                 err = PTR_ERR(s);
1320                 goto failed;
1321         }
1322 
1323         if (!s->s_root) {
1324                 s_new = true;
1325 
1326                 /* New superblock instance created */
1327                 s->s_mode = mode;
1328                 snprintf(s->s_id, sizeof(s->s_id), "%pg", sd.bdev);
1329                 sb_set_blocksize(s, block_size(sd.bdev));
1330 
1331                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1332                 if (err)
1333                         goto failed_super;
1334 
1335                 s->s_flags |= MS_ACTIVE;
1336         } else if (!sd.cno) {
1337                 if (nilfs_tree_is_busy(s->s_root)) {
1338                         if ((flags ^ s->s_flags) & MS_RDONLY) {
1339                                 nilfs_msg(s, KERN_ERR,
1340                                           "the device already has a %s mount.",
1341                                           (s->s_flags & MS_RDONLY) ?
1342                                           "read-only" : "read/write");
1343                                 err = -EBUSY;
1344                                 goto failed_super;
1345                         }
1346                 } else {
1347                         /*
1348                          * Try remount to setup mount states if the current
1349                          * tree is not mounted and only snapshots use this sb.
1350                          */
1351                         err = nilfs_remount(s, &flags, data);
1352                         if (err)
1353                                 goto failed_super;
1354                 }
1355         }
1356 
1357         if (sd.cno) {
1358                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1359                 if (err)
1360                         goto failed_super;
1361         } else {
1362                 root_dentry = dget(s->s_root);
1363         }
1364 
1365         if (!s_new)
1366                 blkdev_put(sd.bdev, mode);
1367 
1368         return root_dentry;
1369 
1370  failed_super:
1371         deactivate_locked_super(s);
1372 
1373  failed:
1374         if (!s_new)
1375                 blkdev_put(sd.bdev, mode);
1376         return ERR_PTR(err);
1377 }
1378 
1379 struct file_system_type nilfs_fs_type = {
1380         .owner    = THIS_MODULE,
1381         .name     = "nilfs2",
1382         .mount    = nilfs_mount,
1383         .kill_sb  = kill_block_super,
1384         .fs_flags = FS_REQUIRES_DEV,
1385 };
1386 MODULE_ALIAS_FS("nilfs2");
1387 
1388 static void nilfs_inode_init_once(void *obj)
1389 {
1390         struct nilfs_inode_info *ii = obj;
1391 
1392         INIT_LIST_HEAD(&ii->i_dirty);
1393 #ifdef CONFIG_NILFS_XATTR
1394         init_rwsem(&ii->xattr_sem);
1395 #endif
1396         address_space_init_once(&ii->i_btnode_cache);
1397         ii->i_bmap = &ii->i_bmap_data;
1398         inode_init_once(&ii->vfs_inode);
1399 }
1400 
1401 static void nilfs_segbuf_init_once(void *obj)
1402 {
1403         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1404 }
1405 
1406 static void nilfs_destroy_cachep(void)
1407 {
1408         /*
1409          * Make sure all delayed rcu free inodes are flushed before we
1410          * destroy cache.
1411          */
1412         rcu_barrier();
1413 
1414         kmem_cache_destroy(nilfs_inode_cachep);
1415         kmem_cache_destroy(nilfs_transaction_cachep);
1416         kmem_cache_destroy(nilfs_segbuf_cachep);
1417         kmem_cache_destroy(nilfs_btree_path_cache);
1418 }
1419 
1420 static int __init nilfs_init_cachep(void)
1421 {
1422         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1423                         sizeof(struct nilfs_inode_info), 0,
1424                         SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
1425                         nilfs_inode_init_once);
1426         if (!nilfs_inode_cachep)
1427                 goto fail;
1428 
1429         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1430                         sizeof(struct nilfs_transaction_info), 0,
1431                         SLAB_RECLAIM_ACCOUNT, NULL);
1432         if (!nilfs_transaction_cachep)
1433                 goto fail;
1434 
1435         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1436                         sizeof(struct nilfs_segment_buffer), 0,
1437                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1438         if (!nilfs_segbuf_cachep)
1439                 goto fail;
1440 
1441         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1442                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1443                         0, 0, NULL);
1444         if (!nilfs_btree_path_cache)
1445                 goto fail;
1446 
1447         return 0;
1448 
1449 fail:
1450         nilfs_destroy_cachep();
1451         return -ENOMEM;
1452 }
1453 
1454 static int __init init_nilfs_fs(void)
1455 {
1456         int err;
1457 
1458         err = nilfs_init_cachep();
1459         if (err)
1460                 goto fail;
1461 
1462         err = nilfs_sysfs_init();
1463         if (err)
1464                 goto free_cachep;
1465 
1466         err = register_filesystem(&nilfs_fs_type);
1467         if (err)
1468                 goto deinit_sysfs_entry;
1469 
1470         printk(KERN_INFO "NILFS version 2 loaded\n");
1471         return 0;
1472 
1473 deinit_sysfs_entry:
1474         nilfs_sysfs_exit();
1475 free_cachep:
1476         nilfs_destroy_cachep();
1477 fail:
1478         return err;
1479 }
1480 
1481 static void __exit exit_nilfs_fs(void)
1482 {
1483         nilfs_destroy_cachep();
1484         nilfs_sysfs_exit();
1485         unregister_filesystem(&nilfs_fs_type);
1486 }
1487 
1488 module_init(init_nilfs_fs)
1489 module_exit(exit_nilfs_fs)
1490 

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