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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  * 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);
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         if (mdi) {
179                 kfree(mdi->mi_bgl); /* kfree(NULL) is safe */
180                 kfree(mdi);
181         }
182         kmem_cache_free(nilfs_inode_cachep, NILFS_I(inode));
183 }
184 
185 void nilfs_destroy_inode(struct inode *inode)
186 {
187         call_rcu(&inode->i_rcu, nilfs_i_callback);
188 }
189 
190 static int nilfs_sync_super(struct super_block *sb, int flag)
191 {
192         struct the_nilfs *nilfs = sb->s_fs_info;
193         int err;
194 
195  retry:
196         set_buffer_dirty(nilfs->ns_sbh[0]);
197         if (nilfs_test_opt(nilfs, BARRIER)) {
198                 err = __sync_dirty_buffer(nilfs->ns_sbh[0],
199                                           WRITE_SYNC | WRITE_FLUSH_FUA);
200         } else {
201                 err = sync_dirty_buffer(nilfs->ns_sbh[0]);
202         }
203 
204         if (unlikely(err)) {
205                 printk(KERN_ERR
206                        "NILFS: unable to write superblock (err=%d)\n", err);
207                 if (err == -EIO && nilfs->ns_sbh[1]) {
208                         /*
209                          * sbp[0] points to newer log than sbp[1],
210                          * so copy sbp[0] to sbp[1] to take over sbp[0].
211                          */
212                         memcpy(nilfs->ns_sbp[1], nilfs->ns_sbp[0],
213                                nilfs->ns_sbsize);
214                         nilfs_fall_back_super_block(nilfs);
215                         goto retry;
216                 }
217         } else {
218                 struct nilfs_super_block *sbp = nilfs->ns_sbp[0];
219 
220                 nilfs->ns_sbwcount++;
221 
222                 /*
223                  * The latest segment becomes trailable from the position
224                  * written in superblock.
225                  */
226                 clear_nilfs_discontinued(nilfs);
227 
228                 /* update GC protection for recent segments */
229                 if (nilfs->ns_sbh[1]) {
230                         if (flag == NILFS_SB_COMMIT_ALL) {
231                                 set_buffer_dirty(nilfs->ns_sbh[1]);
232                                 if (sync_dirty_buffer(nilfs->ns_sbh[1]) < 0)
233                                         goto out;
234                         }
235                         if (le64_to_cpu(nilfs->ns_sbp[1]->s_last_cno) <
236                             le64_to_cpu(nilfs->ns_sbp[0]->s_last_cno))
237                                 sbp = nilfs->ns_sbp[1];
238                 }
239 
240                 spin_lock(&nilfs->ns_last_segment_lock);
241                 nilfs->ns_prot_seq = le64_to_cpu(sbp->s_last_seq);
242                 spin_unlock(&nilfs->ns_last_segment_lock);
243         }
244  out:
245         return err;
246 }
247 
248 void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
249                           struct the_nilfs *nilfs)
250 {
251         sector_t nfreeblocks;
252 
253         /* nilfs->ns_sem must be locked by the caller. */
254         nilfs_count_free_blocks(nilfs, &nfreeblocks);
255         sbp->s_free_blocks_count = cpu_to_le64(nfreeblocks);
256 
257         spin_lock(&nilfs->ns_last_segment_lock);
258         sbp->s_last_seq = cpu_to_le64(nilfs->ns_last_seq);
259         sbp->s_last_pseg = cpu_to_le64(nilfs->ns_last_pseg);
260         sbp->s_last_cno = cpu_to_le64(nilfs->ns_last_cno);
261         spin_unlock(&nilfs->ns_last_segment_lock);
262 }
263 
264 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
265                                                int flip)
266 {
267         struct the_nilfs *nilfs = sb->s_fs_info;
268         struct nilfs_super_block **sbp = nilfs->ns_sbp;
269 
270         /* nilfs->ns_sem must be locked by the caller. */
271         if (sbp[0]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
272                 if (sbp[1] &&
273                     sbp[1]->s_magic == cpu_to_le16(NILFS_SUPER_MAGIC)) {
274                         memcpy(sbp[0], sbp[1], nilfs->ns_sbsize);
275                 } else {
276                         printk(KERN_CRIT "NILFS: superblock broke on dev %s\n",
277                                sb->s_id);
278                         return NULL;
279                 }
280         } else if (sbp[1] &&
281                    sbp[1]->s_magic != cpu_to_le16(NILFS_SUPER_MAGIC)) {
282                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
283         }
284 
285         if (flip && sbp[1])
286                 nilfs_swap_super_block(nilfs);
287 
288         return sbp;
289 }
290 
291 int nilfs_commit_super(struct super_block *sb, int flag)
292 {
293         struct the_nilfs *nilfs = sb->s_fs_info;
294         struct nilfs_super_block **sbp = nilfs->ns_sbp;
295         time_t t;
296 
297         /* nilfs->ns_sem must be locked by the caller. */
298         t = get_seconds();
299         nilfs->ns_sbwtime = t;
300         sbp[0]->s_wtime = cpu_to_le64(t);
301         sbp[0]->s_sum = 0;
302         sbp[0]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
303                                              (unsigned char *)sbp[0],
304                                              nilfs->ns_sbsize));
305         if (flag == NILFS_SB_COMMIT_ALL && sbp[1]) {
306                 sbp[1]->s_wtime = sbp[0]->s_wtime;
307                 sbp[1]->s_sum = 0;
308                 sbp[1]->s_sum = cpu_to_le32(crc32_le(nilfs->ns_crc_seed,
309                                             (unsigned char *)sbp[1],
310                                             nilfs->ns_sbsize));
311         }
312         clear_nilfs_sb_dirty(nilfs);
313         nilfs->ns_flushed_device = 1;
314         /* make sure store to ns_flushed_device cannot be reordered */
315         smp_wmb();
316         return nilfs_sync_super(sb, flag);
317 }
318 
319 /**
320  * nilfs_cleanup_super() - write filesystem state for cleanup
321  * @sb: super block instance to be unmounted or degraded to read-only
322  *
323  * This function restores state flags in the on-disk super block.
324  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
325  * filesystem was not clean previously.
326  */
327 int nilfs_cleanup_super(struct super_block *sb)
328 {
329         struct the_nilfs *nilfs = sb->s_fs_info;
330         struct nilfs_super_block **sbp;
331         int flag = NILFS_SB_COMMIT;
332         int ret = -EIO;
333 
334         sbp = nilfs_prepare_super(sb, 0);
335         if (sbp) {
336                 sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
337                 nilfs_set_log_cursor(sbp[0], nilfs);
338                 if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
339                         /*
340                          * make the "clean" flag also to the opposite
341                          * super block if both super blocks point to
342                          * the same checkpoint.
343                          */
344                         sbp[1]->s_state = sbp[0]->s_state;
345                         flag = NILFS_SB_COMMIT_ALL;
346                 }
347                 ret = nilfs_commit_super(sb, flag);
348         }
349         return ret;
350 }
351 
352 /**
353  * nilfs_move_2nd_super - relocate secondary super block
354  * @sb: super block instance
355  * @sb2off: new offset of the secondary super block (in bytes)
356  */
357 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
358 {
359         struct the_nilfs *nilfs = sb->s_fs_info;
360         struct buffer_head *nsbh;
361         struct nilfs_super_block *nsbp;
362         sector_t blocknr, newblocknr;
363         unsigned long offset;
364         int sb2i;  /* array index of the secondary superblock */
365         int ret = 0;
366 
367         /* nilfs->ns_sem must be locked by the caller. */
368         if (nilfs->ns_sbh[1] &&
369             nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
370                 sb2i = 1;
371                 blocknr = nilfs->ns_sbh[1]->b_blocknr;
372         } else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
373                 sb2i = 0;
374                 blocknr = nilfs->ns_sbh[0]->b_blocknr;
375         } else {
376                 sb2i = -1;
377                 blocknr = 0;
378         }
379         if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
380                 goto out;  /* super block location is unchanged */
381 
382         /* Get new super block buffer */
383         newblocknr = sb2off >> nilfs->ns_blocksize_bits;
384         offset = sb2off & (nilfs->ns_blocksize - 1);
385         nsbh = sb_getblk(sb, newblocknr);
386         if (!nsbh) {
387                 printk(KERN_WARNING
388                        "NILFS warning: unable to move secondary superblock "
389                        "to block %llu\n", (unsigned long long)newblocknr);
390                 ret = -EIO;
391                 goto out;
392         }
393         nsbp = (void *)nsbh->b_data + offset;
394         memset(nsbp, 0, nilfs->ns_blocksize);
395 
396         if (sb2i >= 0) {
397                 memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
398                 brelse(nilfs->ns_sbh[sb2i]);
399                 nilfs->ns_sbh[sb2i] = nsbh;
400                 nilfs->ns_sbp[sb2i] = nsbp;
401         } else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
402                 /* secondary super block will be restored to index 1 */
403                 nilfs->ns_sbh[1] = nsbh;
404                 nilfs->ns_sbp[1] = nsbp;
405         } else {
406                 brelse(nsbh);
407         }
408 out:
409         return ret;
410 }
411 
412 /**
413  * nilfs_resize_fs - resize the filesystem
414  * @sb: super block instance
415  * @newsize: new size of the filesystem (in bytes)
416  */
417 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
418 {
419         struct the_nilfs *nilfs = sb->s_fs_info;
420         struct nilfs_super_block **sbp;
421         __u64 devsize, newnsegs;
422         loff_t sb2off;
423         int ret;
424 
425         ret = -ERANGE;
426         devsize = i_size_read(sb->s_bdev->bd_inode);
427         if (newsize > devsize)
428                 goto out;
429 
430         /*
431          * Write lock is required to protect some functions depending
432          * on the number of segments, the number of reserved segments,
433          * and so forth.
434          */
435         down_write(&nilfs->ns_segctor_sem);
436 
437         sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
438         newnsegs = sb2off >> nilfs->ns_blocksize_bits;
439         do_div(newnsegs, nilfs->ns_blocks_per_segment);
440 
441         ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
442         up_write(&nilfs->ns_segctor_sem);
443         if (ret < 0)
444                 goto out;
445 
446         ret = nilfs_construct_segment(sb);
447         if (ret < 0)
448                 goto out;
449 
450         down_write(&nilfs->ns_sem);
451         nilfs_move_2nd_super(sb, sb2off);
452         ret = -EIO;
453         sbp = nilfs_prepare_super(sb, 0);
454         if (likely(sbp)) {
455                 nilfs_set_log_cursor(sbp[0], nilfs);
456                 /*
457                  * Drop NILFS_RESIZE_FS flag for compatibility with
458                  * mount-time resize which may be implemented in a
459                  * future release.
460                  */
461                 sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
462                                               ~NILFS_RESIZE_FS);
463                 sbp[0]->s_dev_size = cpu_to_le64(newsize);
464                 sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
465                 if (sbp[1])
466                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
467                 ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
468         }
469         up_write(&nilfs->ns_sem);
470 
471         /*
472          * Reset the range of allocatable segments last.  This order
473          * is important in the case of expansion because the secondary
474          * superblock must be protected from log write until migration
475          * completes.
476          */
477         if (!ret)
478                 nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
479 out:
480         return ret;
481 }
482 
483 static void nilfs_put_super(struct super_block *sb)
484 {
485         struct the_nilfs *nilfs = sb->s_fs_info;
486 
487         nilfs_detach_log_writer(sb);
488 
489         if (!(sb->s_flags & MS_RDONLY)) {
490                 down_write(&nilfs->ns_sem);
491                 nilfs_cleanup_super(sb);
492                 up_write(&nilfs->ns_sem);
493         }
494 
495         iput(nilfs->ns_sufile);
496         iput(nilfs->ns_cpfile);
497         iput(nilfs->ns_dat);
498 
499         destroy_nilfs(nilfs);
500         sb->s_fs_info = NULL;
501 }
502 
503 static int nilfs_sync_fs(struct super_block *sb, int wait)
504 {
505         struct the_nilfs *nilfs = sb->s_fs_info;
506         struct nilfs_super_block **sbp;
507         int err = 0;
508 
509         /* This function is called when super block should be written back */
510         if (wait)
511                 err = nilfs_construct_segment(sb);
512 
513         down_write(&nilfs->ns_sem);
514         if (nilfs_sb_dirty(nilfs)) {
515                 sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
516                 if (likely(sbp)) {
517                         nilfs_set_log_cursor(sbp[0], nilfs);
518                         nilfs_commit_super(sb, NILFS_SB_COMMIT);
519                 }
520         }
521         up_write(&nilfs->ns_sem);
522 
523         if (!err)
524                 err = nilfs_flush_device(nilfs);
525 
526         return err;
527 }
528 
529 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
530                             struct nilfs_root **rootp)
531 {
532         struct the_nilfs *nilfs = sb->s_fs_info;
533         struct nilfs_root *root;
534         struct nilfs_checkpoint *raw_cp;
535         struct buffer_head *bh_cp;
536         int err = -ENOMEM;
537 
538         root = nilfs_find_or_create_root(
539                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
540         if (!root)
541                 return err;
542 
543         if (root->ifile)
544                 goto reuse; /* already attached checkpoint */
545 
546         down_read(&nilfs->ns_segctor_sem);
547         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
548                                           &bh_cp);
549         up_read(&nilfs->ns_segctor_sem);
550         if (unlikely(err)) {
551                 if (err == -ENOENT || err == -EINVAL) {
552                         printk(KERN_ERR
553                                "NILFS: Invalid checkpoint "
554                                "(checkpoint number=%llu)\n",
555                                (unsigned long long)cno);
556                         err = -EINVAL;
557                 }
558                 goto failed;
559         }
560 
561         err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
562                                &raw_cp->cp_ifile_inode, &root->ifile);
563         if (err)
564                 goto failed_bh;
565 
566         atomic64_set(&root->inodes_count,
567                         le64_to_cpu(raw_cp->cp_inodes_count));
568         atomic64_set(&root->blocks_count,
569                         le64_to_cpu(raw_cp->cp_blocks_count));
570 
571         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
572 
573  reuse:
574         *rootp = root;
575         return 0;
576 
577  failed_bh:
578         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
579  failed:
580         nilfs_put_root(root);
581 
582         return err;
583 }
584 
585 static int nilfs_freeze(struct super_block *sb)
586 {
587         struct the_nilfs *nilfs = sb->s_fs_info;
588         int err;
589 
590         if (sb->s_flags & MS_RDONLY)
591                 return 0;
592 
593         /* Mark super block clean */
594         down_write(&nilfs->ns_sem);
595         err = nilfs_cleanup_super(sb);
596         up_write(&nilfs->ns_sem);
597         return err;
598 }
599 
600 static int nilfs_unfreeze(struct super_block *sb)
601 {
602         struct the_nilfs *nilfs = sb->s_fs_info;
603 
604         if (sb->s_flags & MS_RDONLY)
605                 return 0;
606 
607         down_write(&nilfs->ns_sem);
608         nilfs_setup_super(sb, false);
609         up_write(&nilfs->ns_sem);
610         return 0;
611 }
612 
613 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
614 {
615         struct super_block *sb = dentry->d_sb;
616         struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
617         struct the_nilfs *nilfs = root->nilfs;
618         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
619         unsigned long long blocks;
620         unsigned long overhead;
621         unsigned long nrsvblocks;
622         sector_t nfreeblocks;
623         u64 nmaxinodes, nfreeinodes;
624         int err;
625 
626         /*
627          * Compute all of the segment blocks
628          *
629          * The blocks before first segment and after last segment
630          * are excluded.
631          */
632         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
633                 - nilfs->ns_first_data_block;
634         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
635 
636         /*
637          * Compute the overhead
638          *
639          * When distributing meta data blocks outside segment structure,
640          * We must count them as the overhead.
641          */
642         overhead = 0;
643 
644         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
645         if (unlikely(err))
646                 return err;
647 
648         err = nilfs_ifile_count_free_inodes(root->ifile,
649                                             &nmaxinodes, &nfreeinodes);
650         if (unlikely(err)) {
651                 printk(KERN_WARNING
652                         "NILFS warning: fail to count free inodes: err %d.\n",
653                         err);
654                 if (err == -ERANGE) {
655                         /*
656                          * If nilfs_palloc_count_max_entries() returns
657                          * -ERANGE error code then we simply treat
658                          * curent inodes count as maximum possible and
659                          * zero as free inodes value.
660                          */
661                         nmaxinodes = atomic64_read(&root->inodes_count);
662                         nfreeinodes = 0;
663                         err = 0;
664                 } else
665                         return err;
666         }
667 
668         buf->f_type = NILFS_SUPER_MAGIC;
669         buf->f_bsize = sb->s_blocksize;
670         buf->f_blocks = blocks - overhead;
671         buf->f_bfree = nfreeblocks;
672         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
673                 (buf->f_bfree - nrsvblocks) : 0;
674         buf->f_files = nmaxinodes;
675         buf->f_ffree = nfreeinodes;
676         buf->f_namelen = NILFS_NAME_LEN;
677         buf->f_fsid.val[0] = (u32)id;
678         buf->f_fsid.val[1] = (u32)(id >> 32);
679 
680         return 0;
681 }
682 
683 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
684 {
685         struct super_block *sb = dentry->d_sb;
686         struct the_nilfs *nilfs = sb->s_fs_info;
687         struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
688 
689         if (!nilfs_test_opt(nilfs, BARRIER))
690                 seq_puts(seq, ",nobarrier");
691         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
692                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
693         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
694                 seq_puts(seq, ",errors=panic");
695         if (nilfs_test_opt(nilfs, ERRORS_CONT))
696                 seq_puts(seq, ",errors=continue");
697         if (nilfs_test_opt(nilfs, STRICT_ORDER))
698                 seq_puts(seq, ",order=strict");
699         if (nilfs_test_opt(nilfs, NORECOVERY))
700                 seq_puts(seq, ",norecovery");
701         if (nilfs_test_opt(nilfs, DISCARD))
702                 seq_puts(seq, ",discard");
703 
704         return 0;
705 }
706 
707 static const struct super_operations nilfs_sops = {
708         .alloc_inode    = nilfs_alloc_inode,
709         .destroy_inode  = nilfs_destroy_inode,
710         .dirty_inode    = nilfs_dirty_inode,
711         .evict_inode    = nilfs_evict_inode,
712         .put_super      = nilfs_put_super,
713         .sync_fs        = nilfs_sync_fs,
714         .freeze_fs      = nilfs_freeze,
715         .unfreeze_fs    = nilfs_unfreeze,
716         .statfs         = nilfs_statfs,
717         .remount_fs     = nilfs_remount,
718         .show_options = nilfs_show_options
719 };
720 
721 enum {
722         Opt_err_cont, Opt_err_panic, Opt_err_ro,
723         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
724         Opt_discard, Opt_nodiscard, Opt_err,
725 };
726 
727 static match_table_t tokens = {
728         {Opt_err_cont, "errors=continue"},
729         {Opt_err_panic, "errors=panic"},
730         {Opt_err_ro, "errors=remount-ro"},
731         {Opt_barrier, "barrier"},
732         {Opt_nobarrier, "nobarrier"},
733         {Opt_snapshot, "cp=%u"},
734         {Opt_order, "order=%s"},
735         {Opt_norecovery, "norecovery"},
736         {Opt_discard, "discard"},
737         {Opt_nodiscard, "nodiscard"},
738         {Opt_err, NULL}
739 };
740 
741 static int parse_options(char *options, struct super_block *sb, int is_remount)
742 {
743         struct the_nilfs *nilfs = sb->s_fs_info;
744         char *p;
745         substring_t args[MAX_OPT_ARGS];
746 
747         if (!options)
748                 return 1;
749 
750         while ((p = strsep(&options, ",")) != NULL) {
751                 int token;
752                 if (!*p)
753                         continue;
754 
755                 token = match_token(p, tokens, args);
756                 switch (token) {
757                 case Opt_barrier:
758                         nilfs_set_opt(nilfs, BARRIER);
759                         break;
760                 case Opt_nobarrier:
761                         nilfs_clear_opt(nilfs, BARRIER);
762                         break;
763                 case Opt_order:
764                         if (strcmp(args[0].from, "relaxed") == 0)
765                                 /* Ordered data semantics */
766                                 nilfs_clear_opt(nilfs, STRICT_ORDER);
767                         else if (strcmp(args[0].from, "strict") == 0)
768                                 /* Strict in-order semantics */
769                                 nilfs_set_opt(nilfs, STRICT_ORDER);
770                         else
771                                 return 0;
772                         break;
773                 case Opt_err_panic:
774                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
775                         break;
776                 case Opt_err_ro:
777                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
778                         break;
779                 case Opt_err_cont:
780                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
781                         break;
782                 case Opt_snapshot:
783                         if (is_remount) {
784                                 printk(KERN_ERR
785                                        "NILFS: \"%s\" option is invalid "
786                                        "for remount.\n", p);
787                                 return 0;
788                         }
789                         break;
790                 case Opt_norecovery:
791                         nilfs_set_opt(nilfs, NORECOVERY);
792                         break;
793                 case Opt_discard:
794                         nilfs_set_opt(nilfs, DISCARD);
795                         break;
796                 case Opt_nodiscard:
797                         nilfs_clear_opt(nilfs, DISCARD);
798                         break;
799                 default:
800                         printk(KERN_ERR
801                                "NILFS: Unrecognized mount option \"%s\"\n", p);
802                         return 0;
803                 }
804         }
805         return 1;
806 }
807 
808 static inline void
809 nilfs_set_default_options(struct super_block *sb,
810                           struct nilfs_super_block *sbp)
811 {
812         struct the_nilfs *nilfs = sb->s_fs_info;
813 
814         nilfs->ns_mount_opt =
815                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
816 }
817 
818 static int nilfs_setup_super(struct super_block *sb, int is_mount)
819 {
820         struct the_nilfs *nilfs = sb->s_fs_info;
821         struct nilfs_super_block **sbp;
822         int max_mnt_count;
823         int mnt_count;
824 
825         /* nilfs->ns_sem must be locked by the caller. */
826         sbp = nilfs_prepare_super(sb, 0);
827         if (!sbp)
828                 return -EIO;
829 
830         if (!is_mount)
831                 goto skip_mount_setup;
832 
833         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
834         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
835 
836         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
837                 printk(KERN_WARNING
838                        "NILFS warning: mounting fs with errors\n");
839 #if 0
840         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
841                 printk(KERN_WARNING
842                        "NILFS warning: maximal mount count reached\n");
843 #endif
844         }
845         if (!max_mnt_count)
846                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
847 
848         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
849         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
850 
851 skip_mount_setup:
852         sbp[0]->s_state =
853                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
854         /* synchronize sbp[1] with sbp[0] */
855         if (sbp[1])
856                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
857         return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
858 }
859 
860 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
861                                                  u64 pos, int blocksize,
862                                                  struct buffer_head **pbh)
863 {
864         unsigned long long sb_index = pos;
865         unsigned long offset;
866 
867         offset = do_div(sb_index, blocksize);
868         *pbh = sb_bread(sb, sb_index);
869         if (!*pbh)
870                 return NULL;
871         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
872 }
873 
874 int nilfs_store_magic_and_option(struct super_block *sb,
875                                  struct nilfs_super_block *sbp,
876                                  char *data)
877 {
878         struct the_nilfs *nilfs = sb->s_fs_info;
879 
880         sb->s_magic = le16_to_cpu(sbp->s_magic);
881 
882         /* FS independent flags */
883 #ifdef NILFS_ATIME_DISABLE
884         sb->s_flags |= MS_NOATIME;
885 #endif
886 
887         nilfs_set_default_options(sb, sbp);
888 
889         nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
890         nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
891         nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
892         nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
893 
894         return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
895 }
896 
897 int nilfs_check_feature_compatibility(struct super_block *sb,
898                                       struct nilfs_super_block *sbp)
899 {
900         __u64 features;
901 
902         features = le64_to_cpu(sbp->s_feature_incompat) &
903                 ~NILFS_FEATURE_INCOMPAT_SUPP;
904         if (features) {
905                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
906                        "optional features (%llx)\n",
907                        (unsigned long long)features);
908                 return -EINVAL;
909         }
910         features = le64_to_cpu(sbp->s_feature_compat_ro) &
911                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
912         if (!(sb->s_flags & MS_RDONLY) && features) {
913                 printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
914                        "unsupported optional features (%llx)\n",
915                        (unsigned long long)features);
916                 return -EINVAL;
917         }
918         return 0;
919 }
920 
921 static int nilfs_get_root_dentry(struct super_block *sb,
922                                  struct nilfs_root *root,
923                                  struct dentry **root_dentry)
924 {
925         struct inode *inode;
926         struct dentry *dentry;
927         int ret = 0;
928 
929         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
930         if (IS_ERR(inode)) {
931                 printk(KERN_ERR "NILFS: get root inode failed\n");
932                 ret = PTR_ERR(inode);
933                 goto out;
934         }
935         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
936                 iput(inode);
937                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
938                 ret = -EINVAL;
939                 goto out;
940         }
941 
942         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
943                 dentry = d_find_alias(inode);
944                 if (!dentry) {
945                         dentry = d_make_root(inode);
946                         if (!dentry) {
947                                 ret = -ENOMEM;
948                                 goto failed_dentry;
949                         }
950                 } else {
951                         iput(inode);
952                 }
953         } else {
954                 dentry = d_obtain_root(inode);
955                 if (IS_ERR(dentry)) {
956                         ret = PTR_ERR(dentry);
957                         goto failed_dentry;
958                 }
959         }
960         *root_dentry = dentry;
961  out:
962         return ret;
963 
964  failed_dentry:
965         printk(KERN_ERR "NILFS: get root dentry failed\n");
966         goto out;
967 }
968 
969 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
970                                  struct dentry **root_dentry)
971 {
972         struct the_nilfs *nilfs = s->s_fs_info;
973         struct nilfs_root *root;
974         int ret;
975 
976         mutex_lock(&nilfs->ns_snapshot_mount_mutex);
977 
978         down_read(&nilfs->ns_segctor_sem);
979         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
980         up_read(&nilfs->ns_segctor_sem);
981         if (ret < 0) {
982                 ret = (ret == -ENOENT) ? -EINVAL : ret;
983                 goto out;
984         } else if (!ret) {
985                 printk(KERN_ERR "NILFS: The specified checkpoint is "
986                        "not a snapshot (checkpoint number=%llu).\n",
987                        (unsigned long long)cno);
988                 ret = -EINVAL;
989                 goto out;
990         }
991 
992         ret = nilfs_attach_checkpoint(s, cno, false, &root);
993         if (ret) {
994                 printk(KERN_ERR "NILFS: error loading snapshot "
995                        "(checkpoint number=%llu).\n",
996                (unsigned long long)cno);
997                 goto out;
998         }
999         ret = nilfs_get_root_dentry(s, root, root_dentry);
1000         nilfs_put_root(root);
1001  out:
1002         mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
1003         return ret;
1004 }
1005 
1006 /**
1007  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
1008  * @root_dentry: root dentry of the tree to be shrunk
1009  *
1010  * This function returns true if the tree was in-use.
1011  */
1012 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
1013 {
1014         shrink_dcache_parent(root_dentry);
1015         return d_count(root_dentry) > 1;
1016 }
1017 
1018 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1019 {
1020         struct the_nilfs *nilfs = sb->s_fs_info;
1021         struct nilfs_root *root;
1022         struct inode *inode;
1023         struct dentry *dentry;
1024         int ret;
1025 
1026         if (cno > nilfs->ns_cno)
1027                 return false;
1028 
1029         if (cno >= nilfs_last_cno(nilfs))
1030                 return true;    /* protect recent checkpoints */
1031 
1032         ret = false;
1033         root = nilfs_lookup_root(nilfs, cno);
1034         if (root) {
1035                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1036                 if (inode) {
1037                         dentry = d_find_alias(inode);
1038                         if (dentry) {
1039                                 ret = nilfs_tree_is_busy(dentry);
1040                                 dput(dentry);
1041                         }
1042                         iput(inode);
1043                 }
1044                 nilfs_put_root(root);
1045         }
1046         return ret;
1047 }
1048 
1049 /**
1050  * nilfs_fill_super() - initialize a super block instance
1051  * @sb: super_block
1052  * @data: mount options
1053  * @silent: silent mode flag
1054  *
1055  * This function is called exclusively by nilfs->ns_mount_mutex.
1056  * So, the recovery process is protected from other simultaneous mounts.
1057  */
1058 static int
1059 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1060 {
1061         struct the_nilfs *nilfs;
1062         struct nilfs_root *fsroot;
1063         __u64 cno;
1064         int err;
1065 
1066         nilfs = alloc_nilfs(sb->s_bdev);
1067         if (!nilfs)
1068                 return -ENOMEM;
1069 
1070         sb->s_fs_info = nilfs;
1071 
1072         err = init_nilfs(nilfs, sb, (char *)data);
1073         if (err)
1074                 goto failed_nilfs;
1075 
1076         sb->s_op = &nilfs_sops;
1077         sb->s_export_op = &nilfs_export_ops;
1078         sb->s_root = NULL;
1079         sb->s_time_gran = 1;
1080         sb->s_max_links = NILFS_LINK_MAX;
1081 
1082         sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
1083 
1084         err = load_nilfs(nilfs, sb);
1085         if (err)
1086                 goto failed_nilfs;
1087 
1088         cno = nilfs_last_cno(nilfs);
1089         err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1090         if (err) {
1091                 printk(KERN_ERR "NILFS: error loading last checkpoint "
1092                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
1093                 goto failed_unload;
1094         }
1095 
1096         if (!(sb->s_flags & MS_RDONLY)) {
1097                 err = nilfs_attach_log_writer(sb, fsroot);
1098                 if (err)
1099                         goto failed_checkpoint;
1100         }
1101 
1102         err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1103         if (err)
1104                 goto failed_segctor;
1105 
1106         nilfs_put_root(fsroot);
1107 
1108         if (!(sb->s_flags & MS_RDONLY)) {
1109                 down_write(&nilfs->ns_sem);
1110                 nilfs_setup_super(sb, true);
1111                 up_write(&nilfs->ns_sem);
1112         }
1113 
1114         return 0;
1115 
1116  failed_segctor:
1117         nilfs_detach_log_writer(sb);
1118 
1119  failed_checkpoint:
1120         nilfs_put_root(fsroot);
1121 
1122  failed_unload:
1123         iput(nilfs->ns_sufile);
1124         iput(nilfs->ns_cpfile);
1125         iput(nilfs->ns_dat);
1126 
1127  failed_nilfs:
1128         destroy_nilfs(nilfs);
1129         return err;
1130 }
1131 
1132 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1133 {
1134         struct the_nilfs *nilfs = sb->s_fs_info;
1135         unsigned long old_sb_flags;
1136         unsigned long old_mount_opt;
1137         int err;
1138 
1139         sync_filesystem(sb);
1140         old_sb_flags = sb->s_flags;
1141         old_mount_opt = nilfs->ns_mount_opt;
1142 
1143         if (!parse_options(data, sb, 1)) {
1144                 err = -EINVAL;
1145                 goto restore_opts;
1146         }
1147         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1148 
1149         err = -EINVAL;
1150 
1151         if (!nilfs_valid_fs(nilfs)) {
1152                 printk(KERN_WARNING "NILFS (device %s): couldn't "
1153                        "remount because the filesystem is in an "
1154                        "incomplete recovery state.\n", sb->s_id);
1155                 goto restore_opts;
1156         }
1157 
1158         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1159                 goto out;
1160         if (*flags & MS_RDONLY) {
1161                 /* Shutting down log writer */
1162                 nilfs_detach_log_writer(sb);
1163                 sb->s_flags |= MS_RDONLY;
1164 
1165                 /*
1166                  * Remounting a valid RW partition RDONLY, so set
1167                  * the RDONLY flag and then mark the partition as valid again.
1168                  */
1169                 down_write(&nilfs->ns_sem);
1170                 nilfs_cleanup_super(sb);
1171                 up_write(&nilfs->ns_sem);
1172         } else {
1173                 __u64 features;
1174                 struct nilfs_root *root;
1175 
1176                 /*
1177                  * Mounting a RDONLY partition read-write, so reread and
1178                  * store the current valid flag.  (It may have been changed
1179                  * by fsck since we originally mounted the partition.)
1180                  */
1181                 down_read(&nilfs->ns_sem);
1182                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1183                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
1184                 up_read(&nilfs->ns_sem);
1185                 if (features) {
1186                         printk(KERN_WARNING "NILFS (device %s): couldn't "
1187                                "remount RDWR because of unsupported optional "
1188                                "features (%llx)\n",
1189                                sb->s_id, (unsigned long long)features);
1190                         err = -EROFS;
1191                         goto restore_opts;
1192                 }
1193 
1194                 sb->s_flags &= ~MS_RDONLY;
1195 
1196                 root = NILFS_I(d_inode(sb->s_root))->i_root;
1197                 err = nilfs_attach_log_writer(sb, root);
1198                 if (err)
1199                         goto restore_opts;
1200 
1201                 down_write(&nilfs->ns_sem);
1202                 nilfs_setup_super(sb, true);
1203                 up_write(&nilfs->ns_sem);
1204         }
1205  out:
1206         return 0;
1207 
1208  restore_opts:
1209         sb->s_flags = old_sb_flags;
1210         nilfs->ns_mount_opt = old_mount_opt;
1211         return err;
1212 }
1213 
1214 struct nilfs_super_data {
1215         struct block_device *bdev;
1216         __u64 cno;
1217         int flags;
1218 };
1219 
1220 /**
1221  * nilfs_identify - pre-read mount options needed to identify mount instance
1222  * @data: mount options
1223  * @sd: nilfs_super_data
1224  */
1225 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1226 {
1227         char *p, *options = data;
1228         substring_t args[MAX_OPT_ARGS];
1229         int token;
1230         int ret = 0;
1231 
1232         do {
1233                 p = strsep(&options, ",");
1234                 if (p != NULL && *p) {
1235                         token = match_token(p, tokens, args);
1236                         if (token == Opt_snapshot) {
1237                                 if (!(sd->flags & MS_RDONLY)) {
1238                                         ret++;
1239                                 } else {
1240                                         sd->cno = simple_strtoull(args[0].from,
1241                                                                   NULL, 0);
1242                                         /*
1243                                          * No need to see the end pointer;
1244                                          * match_token() has done syntax
1245                                          * checking.
1246                                          */
1247                                         if (sd->cno == 0)
1248                                                 ret++;
1249                                 }
1250                         }
1251                         if (ret)
1252                                 printk(KERN_ERR
1253                                        "NILFS: invalid mount option: %s\n", p);
1254                 }
1255                 if (!options)
1256                         break;
1257                 BUG_ON(options == data);
1258                 *(options - 1) = ',';
1259         } while (!ret);
1260         return ret;
1261 }
1262 
1263 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1264 {
1265         s->s_bdev = data;
1266         s->s_dev = s->s_bdev->bd_dev;
1267         return 0;
1268 }
1269 
1270 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1271 {
1272         return (void *)s->s_bdev == data;
1273 }
1274 
1275 static struct dentry *
1276 nilfs_mount(struct file_system_type *fs_type, int flags,
1277              const char *dev_name, void *data)
1278 {
1279         struct nilfs_super_data sd;
1280         struct super_block *s;
1281         fmode_t mode = FMODE_READ | FMODE_EXCL;
1282         struct dentry *root_dentry;
1283         int err, s_new = false;
1284 
1285         if (!(flags & MS_RDONLY))
1286                 mode |= FMODE_WRITE;
1287 
1288         sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1289         if (IS_ERR(sd.bdev))
1290                 return ERR_CAST(sd.bdev);
1291 
1292         sd.cno = 0;
1293         sd.flags = flags;
1294         if (nilfs_identify((char *)data, &sd)) {
1295                 err = -EINVAL;
1296                 goto failed;
1297         }
1298 
1299         /*
1300          * once the super is inserted into the list by sget, s_umount
1301          * will protect the lockfs code from trying to start a snapshot
1302          * while we are mounting
1303          */
1304         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1305         if (sd.bdev->bd_fsfreeze_count > 0) {
1306                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1307                 err = -EBUSY;
1308                 goto failed;
1309         }
1310         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1311                  sd.bdev);
1312         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1313         if (IS_ERR(s)) {
1314                 err = PTR_ERR(s);
1315                 goto failed;
1316         }
1317 
1318         if (!s->s_root) {
1319                 char b[BDEVNAME_SIZE];
1320 
1321                 s_new = true;
1322 
1323                 /* New superblock instance created */
1324                 s->s_mode = mode;
1325                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1326                 sb_set_blocksize(s, block_size(sd.bdev));
1327 
1328                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1329                 if (err)
1330                         goto failed_super;
1331 
1332                 s->s_flags |= MS_ACTIVE;
1333         } else if (!sd.cno) {
1334                 if (nilfs_tree_is_busy(s->s_root)) {
1335                         if ((flags ^ s->s_flags) & MS_RDONLY) {
1336                                 printk(KERN_ERR "NILFS: the device already "
1337                                        "has a %s mount.\n",
1338                                        (s->s_flags & MS_RDONLY) ?
1339                                        "read-only" : "read/write");
1340                                 err = -EBUSY;
1341                                 goto failed_super;
1342                         }
1343                 } else {
1344                         /*
1345                          * Try remount to setup mount states if the current
1346                          * tree is not mounted and only snapshots use this sb.
1347                          */
1348                         err = nilfs_remount(s, &flags, data);
1349                         if (err)
1350                                 goto failed_super;
1351                 }
1352         }
1353 
1354         if (sd.cno) {
1355                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1356                 if (err)
1357                         goto failed_super;
1358         } else {
1359                 root_dentry = dget(s->s_root);
1360         }
1361 
1362         if (!s_new)
1363                 blkdev_put(sd.bdev, mode);
1364 
1365         return root_dentry;
1366 
1367  failed_super:
1368         deactivate_locked_super(s);
1369 
1370  failed:
1371         if (!s_new)
1372                 blkdev_put(sd.bdev, mode);
1373         return ERR_PTR(err);
1374 }
1375 
1376 struct file_system_type nilfs_fs_type = {
1377         .owner    = THIS_MODULE,
1378         .name     = "nilfs2",
1379         .mount    = nilfs_mount,
1380         .kill_sb  = kill_block_super,
1381         .fs_flags = FS_REQUIRES_DEV,
1382 };
1383 MODULE_ALIAS_FS("nilfs2");
1384 
1385 static void nilfs_inode_init_once(void *obj)
1386 {
1387         struct nilfs_inode_info *ii = obj;
1388 
1389         INIT_LIST_HEAD(&ii->i_dirty);
1390 #ifdef CONFIG_NILFS_XATTR
1391         init_rwsem(&ii->xattr_sem);
1392 #endif
1393         address_space_init_once(&ii->i_btnode_cache);
1394         ii->i_bmap = &ii->i_bmap_data;
1395         inode_init_once(&ii->vfs_inode);
1396 }
1397 
1398 static void nilfs_segbuf_init_once(void *obj)
1399 {
1400         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1401 }
1402 
1403 static void nilfs_destroy_cachep(void)
1404 {
1405         /*
1406          * Make sure all delayed rcu free inodes are flushed before we
1407          * destroy cache.
1408          */
1409         rcu_barrier();
1410 
1411         kmem_cache_destroy(nilfs_inode_cachep);
1412         kmem_cache_destroy(nilfs_transaction_cachep);
1413         kmem_cache_destroy(nilfs_segbuf_cachep);
1414         kmem_cache_destroy(nilfs_btree_path_cache);
1415 }
1416 
1417 static int __init nilfs_init_cachep(void)
1418 {
1419         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1420                         sizeof(struct nilfs_inode_info), 0,
1421                         SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
1422         if (!nilfs_inode_cachep)
1423                 goto fail;
1424 
1425         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1426                         sizeof(struct nilfs_transaction_info), 0,
1427                         SLAB_RECLAIM_ACCOUNT, NULL);
1428         if (!nilfs_transaction_cachep)
1429                 goto fail;
1430 
1431         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1432                         sizeof(struct nilfs_segment_buffer), 0,
1433                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1434         if (!nilfs_segbuf_cachep)
1435                 goto fail;
1436 
1437         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1438                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1439                         0, 0, NULL);
1440         if (!nilfs_btree_path_cache)
1441                 goto fail;
1442 
1443         return 0;
1444 
1445 fail:
1446         nilfs_destroy_cachep();
1447         return -ENOMEM;
1448 }
1449 
1450 static int __init init_nilfs_fs(void)
1451 {
1452         int err;
1453 
1454         err = nilfs_init_cachep();
1455         if (err)
1456                 goto fail;
1457 
1458         err = nilfs_sysfs_init();
1459         if (err)
1460                 goto free_cachep;
1461 
1462         err = register_filesystem(&nilfs_fs_type);
1463         if (err)
1464                 goto deinit_sysfs_entry;
1465 
1466         printk(KERN_INFO "NILFS version 2 loaded\n");
1467         return 0;
1468 
1469 deinit_sysfs_entry:
1470         nilfs_sysfs_exit();
1471 free_cachep:
1472         nilfs_destroy_cachep();
1473 fail:
1474         return err;
1475 }
1476 
1477 static void __exit exit_nilfs_fs(void)
1478 {
1479         nilfs_destroy_cachep();
1480         nilfs_sysfs_exit();
1481         unregister_filesystem(&nilfs_fs_type);
1482 }
1483 
1484 module_init(init_nilfs_fs)
1485 module_exit(exit_nilfs_fs)
1486 

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