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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 = -1;  /* 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         }
376         if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
377                 goto out;  /* super block location is unchanged */
378 
379         /* Get new super block buffer */
380         newblocknr = sb2off >> nilfs->ns_blocksize_bits;
381         offset = sb2off & (nilfs->ns_blocksize - 1);
382         nsbh = sb_getblk(sb, newblocknr);
383         if (!nsbh) {
384                 printk(KERN_WARNING
385                        "NILFS warning: unable to move secondary superblock "
386                        "to block %llu\n", (unsigned long long)newblocknr);
387                 ret = -EIO;
388                 goto out;
389         }
390         nsbp = (void *)nsbh->b_data + offset;
391         memset(nsbp, 0, nilfs->ns_blocksize);
392 
393         if (sb2i >= 0) {
394                 memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
395                 brelse(nilfs->ns_sbh[sb2i]);
396                 nilfs->ns_sbh[sb2i] = nsbh;
397                 nilfs->ns_sbp[sb2i] = nsbp;
398         } else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
399                 /* secondary super block will be restored to index 1 */
400                 nilfs->ns_sbh[1] = nsbh;
401                 nilfs->ns_sbp[1] = nsbp;
402         } else {
403                 brelse(nsbh);
404         }
405 out:
406         return ret;
407 }
408 
409 /**
410  * nilfs_resize_fs - resize the filesystem
411  * @sb: super block instance
412  * @newsize: new size of the filesystem (in bytes)
413  */
414 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
415 {
416         struct the_nilfs *nilfs = sb->s_fs_info;
417         struct nilfs_super_block **sbp;
418         __u64 devsize, newnsegs;
419         loff_t sb2off;
420         int ret;
421 
422         ret = -ERANGE;
423         devsize = i_size_read(sb->s_bdev->bd_inode);
424         if (newsize > devsize)
425                 goto out;
426 
427         /*
428          * Write lock is required to protect some functions depending
429          * on the number of segments, the number of reserved segments,
430          * and so forth.
431          */
432         down_write(&nilfs->ns_segctor_sem);
433 
434         sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
435         newnsegs = sb2off >> nilfs->ns_blocksize_bits;
436         do_div(newnsegs, nilfs->ns_blocks_per_segment);
437 
438         ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
439         up_write(&nilfs->ns_segctor_sem);
440         if (ret < 0)
441                 goto out;
442 
443         ret = nilfs_construct_segment(sb);
444         if (ret < 0)
445                 goto out;
446 
447         down_write(&nilfs->ns_sem);
448         nilfs_move_2nd_super(sb, sb2off);
449         ret = -EIO;
450         sbp = nilfs_prepare_super(sb, 0);
451         if (likely(sbp)) {
452                 nilfs_set_log_cursor(sbp[0], nilfs);
453                 /*
454                  * Drop NILFS_RESIZE_FS flag for compatibility with
455                  * mount-time resize which may be implemented in a
456                  * future release.
457                  */
458                 sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
459                                               ~NILFS_RESIZE_FS);
460                 sbp[0]->s_dev_size = cpu_to_le64(newsize);
461                 sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
462                 if (sbp[1])
463                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
464                 ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
465         }
466         up_write(&nilfs->ns_sem);
467 
468         /*
469          * Reset the range of allocatable segments last.  This order
470          * is important in the case of expansion because the secondary
471          * superblock must be protected from log write until migration
472          * completes.
473          */
474         if (!ret)
475                 nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
476 out:
477         return ret;
478 }
479 
480 static void nilfs_put_super(struct super_block *sb)
481 {
482         struct the_nilfs *nilfs = sb->s_fs_info;
483 
484         nilfs_detach_log_writer(sb);
485 
486         if (!(sb->s_flags & MS_RDONLY)) {
487                 down_write(&nilfs->ns_sem);
488                 nilfs_cleanup_super(sb);
489                 up_write(&nilfs->ns_sem);
490         }
491 
492         iput(nilfs->ns_sufile);
493         iput(nilfs->ns_cpfile);
494         iput(nilfs->ns_dat);
495 
496         destroy_nilfs(nilfs);
497         sb->s_fs_info = NULL;
498 }
499 
500 static int nilfs_sync_fs(struct super_block *sb, int wait)
501 {
502         struct the_nilfs *nilfs = sb->s_fs_info;
503         struct nilfs_super_block **sbp;
504         int err = 0;
505 
506         /* This function is called when super block should be written back */
507         if (wait)
508                 err = nilfs_construct_segment(sb);
509 
510         down_write(&nilfs->ns_sem);
511         if (nilfs_sb_dirty(nilfs)) {
512                 sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
513                 if (likely(sbp)) {
514                         nilfs_set_log_cursor(sbp[0], nilfs);
515                         nilfs_commit_super(sb, NILFS_SB_COMMIT);
516                 }
517         }
518         up_write(&nilfs->ns_sem);
519 
520         if (!err)
521                 err = nilfs_flush_device(nilfs);
522 
523         return err;
524 }
525 
526 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
527                             struct nilfs_root **rootp)
528 {
529         struct the_nilfs *nilfs = sb->s_fs_info;
530         struct nilfs_root *root;
531         struct nilfs_checkpoint *raw_cp;
532         struct buffer_head *bh_cp;
533         int err = -ENOMEM;
534 
535         root = nilfs_find_or_create_root(
536                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
537         if (!root)
538                 return err;
539 
540         if (root->ifile)
541                 goto reuse; /* already attached checkpoint */
542 
543         down_read(&nilfs->ns_segctor_sem);
544         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
545                                           &bh_cp);
546         up_read(&nilfs->ns_segctor_sem);
547         if (unlikely(err)) {
548                 if (err == -ENOENT || err == -EINVAL) {
549                         printk(KERN_ERR
550                                "NILFS: Invalid checkpoint "
551                                "(checkpoint number=%llu)\n",
552                                (unsigned long long)cno);
553                         err = -EINVAL;
554                 }
555                 goto failed;
556         }
557 
558         err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
559                                &raw_cp->cp_ifile_inode, &root->ifile);
560         if (err)
561                 goto failed_bh;
562 
563         atomic64_set(&root->inodes_count,
564                         le64_to_cpu(raw_cp->cp_inodes_count));
565         atomic64_set(&root->blocks_count,
566                         le64_to_cpu(raw_cp->cp_blocks_count));
567 
568         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
569 
570  reuse:
571         *rootp = root;
572         return 0;
573 
574  failed_bh:
575         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
576  failed:
577         nilfs_put_root(root);
578 
579         return err;
580 }
581 
582 static int nilfs_freeze(struct super_block *sb)
583 {
584         struct the_nilfs *nilfs = sb->s_fs_info;
585         int err;
586 
587         if (sb->s_flags & MS_RDONLY)
588                 return 0;
589 
590         /* Mark super block clean */
591         down_write(&nilfs->ns_sem);
592         err = nilfs_cleanup_super(sb);
593         up_write(&nilfs->ns_sem);
594         return err;
595 }
596 
597 static int nilfs_unfreeze(struct super_block *sb)
598 {
599         struct the_nilfs *nilfs = sb->s_fs_info;
600 
601         if (sb->s_flags & MS_RDONLY)
602                 return 0;
603 
604         down_write(&nilfs->ns_sem);
605         nilfs_setup_super(sb, false);
606         up_write(&nilfs->ns_sem);
607         return 0;
608 }
609 
610 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
611 {
612         struct super_block *sb = dentry->d_sb;
613         struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
614         struct the_nilfs *nilfs = root->nilfs;
615         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
616         unsigned long long blocks;
617         unsigned long overhead;
618         unsigned long nrsvblocks;
619         sector_t nfreeblocks;
620         u64 nmaxinodes, nfreeinodes;
621         int err;
622 
623         /*
624          * Compute all of the segment blocks
625          *
626          * The blocks before first segment and after last segment
627          * are excluded.
628          */
629         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
630                 - nilfs->ns_first_data_block;
631         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
632 
633         /*
634          * Compute the overhead
635          *
636          * When distributing meta data blocks outside segment structure,
637          * We must count them as the overhead.
638          */
639         overhead = 0;
640 
641         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
642         if (unlikely(err))
643                 return err;
644 
645         err = nilfs_ifile_count_free_inodes(root->ifile,
646                                             &nmaxinodes, &nfreeinodes);
647         if (unlikely(err)) {
648                 printk(KERN_WARNING
649                         "NILFS warning: fail to count free inodes: err %d.\n",
650                         err);
651                 if (err == -ERANGE) {
652                         /*
653                          * If nilfs_palloc_count_max_entries() returns
654                          * -ERANGE error code then we simply treat
655                          * curent inodes count as maximum possible and
656                          * zero as free inodes value.
657                          */
658                         nmaxinodes = atomic64_read(&root->inodes_count);
659                         nfreeinodes = 0;
660                         err = 0;
661                 } else
662                         return err;
663         }
664 
665         buf->f_type = NILFS_SUPER_MAGIC;
666         buf->f_bsize = sb->s_blocksize;
667         buf->f_blocks = blocks - overhead;
668         buf->f_bfree = nfreeblocks;
669         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
670                 (buf->f_bfree - nrsvblocks) : 0;
671         buf->f_files = nmaxinodes;
672         buf->f_ffree = nfreeinodes;
673         buf->f_namelen = NILFS_NAME_LEN;
674         buf->f_fsid.val[0] = (u32)id;
675         buf->f_fsid.val[1] = (u32)(id >> 32);
676 
677         return 0;
678 }
679 
680 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
681 {
682         struct super_block *sb = dentry->d_sb;
683         struct the_nilfs *nilfs = sb->s_fs_info;
684         struct nilfs_root *root = NILFS_I(d_inode(dentry))->i_root;
685 
686         if (!nilfs_test_opt(nilfs, BARRIER))
687                 seq_puts(seq, ",nobarrier");
688         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
689                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
690         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
691                 seq_puts(seq, ",errors=panic");
692         if (nilfs_test_opt(nilfs, ERRORS_CONT))
693                 seq_puts(seq, ",errors=continue");
694         if (nilfs_test_opt(nilfs, STRICT_ORDER))
695                 seq_puts(seq, ",order=strict");
696         if (nilfs_test_opt(nilfs, NORECOVERY))
697                 seq_puts(seq, ",norecovery");
698         if (nilfs_test_opt(nilfs, DISCARD))
699                 seq_puts(seq, ",discard");
700 
701         return 0;
702 }
703 
704 static const struct super_operations nilfs_sops = {
705         .alloc_inode    = nilfs_alloc_inode,
706         .destroy_inode  = nilfs_destroy_inode,
707         .dirty_inode    = nilfs_dirty_inode,
708         .evict_inode    = nilfs_evict_inode,
709         .put_super      = nilfs_put_super,
710         .sync_fs        = nilfs_sync_fs,
711         .freeze_fs      = nilfs_freeze,
712         .unfreeze_fs    = nilfs_unfreeze,
713         .statfs         = nilfs_statfs,
714         .remount_fs     = nilfs_remount,
715         .show_options = nilfs_show_options
716 };
717 
718 enum {
719         Opt_err_cont, Opt_err_panic, Opt_err_ro,
720         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
721         Opt_discard, Opt_nodiscard, Opt_err,
722 };
723 
724 static match_table_t tokens = {
725         {Opt_err_cont, "errors=continue"},
726         {Opt_err_panic, "errors=panic"},
727         {Opt_err_ro, "errors=remount-ro"},
728         {Opt_barrier, "barrier"},
729         {Opt_nobarrier, "nobarrier"},
730         {Opt_snapshot, "cp=%u"},
731         {Opt_order, "order=%s"},
732         {Opt_norecovery, "norecovery"},
733         {Opt_discard, "discard"},
734         {Opt_nodiscard, "nodiscard"},
735         {Opt_err, NULL}
736 };
737 
738 static int parse_options(char *options, struct super_block *sb, int is_remount)
739 {
740         struct the_nilfs *nilfs = sb->s_fs_info;
741         char *p;
742         substring_t args[MAX_OPT_ARGS];
743 
744         if (!options)
745                 return 1;
746 
747         while ((p = strsep(&options, ",")) != NULL) {
748                 int token;
749                 if (!*p)
750                         continue;
751 
752                 token = match_token(p, tokens, args);
753                 switch (token) {
754                 case Opt_barrier:
755                         nilfs_set_opt(nilfs, BARRIER);
756                         break;
757                 case Opt_nobarrier:
758                         nilfs_clear_opt(nilfs, BARRIER);
759                         break;
760                 case Opt_order:
761                         if (strcmp(args[0].from, "relaxed") == 0)
762                                 /* Ordered data semantics */
763                                 nilfs_clear_opt(nilfs, STRICT_ORDER);
764                         else if (strcmp(args[0].from, "strict") == 0)
765                                 /* Strict in-order semantics */
766                                 nilfs_set_opt(nilfs, STRICT_ORDER);
767                         else
768                                 return 0;
769                         break;
770                 case Opt_err_panic:
771                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
772                         break;
773                 case Opt_err_ro:
774                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
775                         break;
776                 case Opt_err_cont:
777                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
778                         break;
779                 case Opt_snapshot:
780                         if (is_remount) {
781                                 printk(KERN_ERR
782                                        "NILFS: \"%s\" option is invalid "
783                                        "for remount.\n", p);
784                                 return 0;
785                         }
786                         break;
787                 case Opt_norecovery:
788                         nilfs_set_opt(nilfs, NORECOVERY);
789                         break;
790                 case Opt_discard:
791                         nilfs_set_opt(nilfs, DISCARD);
792                         break;
793                 case Opt_nodiscard:
794                         nilfs_clear_opt(nilfs, DISCARD);
795                         break;
796                 default:
797                         printk(KERN_ERR
798                                "NILFS: Unrecognized mount option \"%s\"\n", p);
799                         return 0;
800                 }
801         }
802         return 1;
803 }
804 
805 static inline void
806 nilfs_set_default_options(struct super_block *sb,
807                           struct nilfs_super_block *sbp)
808 {
809         struct the_nilfs *nilfs = sb->s_fs_info;
810 
811         nilfs->ns_mount_opt =
812                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
813 }
814 
815 static int nilfs_setup_super(struct super_block *sb, int is_mount)
816 {
817         struct the_nilfs *nilfs = sb->s_fs_info;
818         struct nilfs_super_block **sbp;
819         int max_mnt_count;
820         int mnt_count;
821 
822         /* nilfs->ns_sem must be locked by the caller. */
823         sbp = nilfs_prepare_super(sb, 0);
824         if (!sbp)
825                 return -EIO;
826 
827         if (!is_mount)
828                 goto skip_mount_setup;
829 
830         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
831         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
832 
833         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
834                 printk(KERN_WARNING
835                        "NILFS warning: mounting fs with errors\n");
836 #if 0
837         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
838                 printk(KERN_WARNING
839                        "NILFS warning: maximal mount count reached\n");
840 #endif
841         }
842         if (!max_mnt_count)
843                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
844 
845         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
846         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
847 
848 skip_mount_setup:
849         sbp[0]->s_state =
850                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
851         /* synchronize sbp[1] with sbp[0] */
852         if (sbp[1])
853                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
854         return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
855 }
856 
857 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
858                                                  u64 pos, int blocksize,
859                                                  struct buffer_head **pbh)
860 {
861         unsigned long long sb_index = pos;
862         unsigned long offset;
863 
864         offset = do_div(sb_index, blocksize);
865         *pbh = sb_bread(sb, sb_index);
866         if (!*pbh)
867                 return NULL;
868         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
869 }
870 
871 int nilfs_store_magic_and_option(struct super_block *sb,
872                                  struct nilfs_super_block *sbp,
873                                  char *data)
874 {
875         struct the_nilfs *nilfs = sb->s_fs_info;
876 
877         sb->s_magic = le16_to_cpu(sbp->s_magic);
878 
879         /* FS independent flags */
880 #ifdef NILFS_ATIME_DISABLE
881         sb->s_flags |= MS_NOATIME;
882 #endif
883 
884         nilfs_set_default_options(sb, sbp);
885 
886         nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
887         nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
888         nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
889         nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
890 
891         return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
892 }
893 
894 int nilfs_check_feature_compatibility(struct super_block *sb,
895                                       struct nilfs_super_block *sbp)
896 {
897         __u64 features;
898 
899         features = le64_to_cpu(sbp->s_feature_incompat) &
900                 ~NILFS_FEATURE_INCOMPAT_SUPP;
901         if (features) {
902                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
903                        "optional features (%llx)\n",
904                        (unsigned long long)features);
905                 return -EINVAL;
906         }
907         features = le64_to_cpu(sbp->s_feature_compat_ro) &
908                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
909         if (!(sb->s_flags & MS_RDONLY) && features) {
910                 printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
911                        "unsupported optional features (%llx)\n",
912                        (unsigned long long)features);
913                 return -EINVAL;
914         }
915         return 0;
916 }
917 
918 static int nilfs_get_root_dentry(struct super_block *sb,
919                                  struct nilfs_root *root,
920                                  struct dentry **root_dentry)
921 {
922         struct inode *inode;
923         struct dentry *dentry;
924         int ret = 0;
925 
926         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
927         if (IS_ERR(inode)) {
928                 printk(KERN_ERR "NILFS: get root inode failed\n");
929                 ret = PTR_ERR(inode);
930                 goto out;
931         }
932         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
933                 iput(inode);
934                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
935                 ret = -EINVAL;
936                 goto out;
937         }
938 
939         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
940                 dentry = d_find_alias(inode);
941                 if (!dentry) {
942                         dentry = d_make_root(inode);
943                         if (!dentry) {
944                                 ret = -ENOMEM;
945                                 goto failed_dentry;
946                         }
947                 } else {
948                         iput(inode);
949                 }
950         } else {
951                 dentry = d_obtain_root(inode);
952                 if (IS_ERR(dentry)) {
953                         ret = PTR_ERR(dentry);
954                         goto failed_dentry;
955                 }
956         }
957         *root_dentry = dentry;
958  out:
959         return ret;
960 
961  failed_dentry:
962         printk(KERN_ERR "NILFS: get root dentry failed\n");
963         goto out;
964 }
965 
966 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
967                                  struct dentry **root_dentry)
968 {
969         struct the_nilfs *nilfs = s->s_fs_info;
970         struct nilfs_root *root;
971         int ret;
972 
973         mutex_lock(&nilfs->ns_snapshot_mount_mutex);
974 
975         down_read(&nilfs->ns_segctor_sem);
976         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
977         up_read(&nilfs->ns_segctor_sem);
978         if (ret < 0) {
979                 ret = (ret == -ENOENT) ? -EINVAL : ret;
980                 goto out;
981         } else if (!ret) {
982                 printk(KERN_ERR "NILFS: The specified checkpoint is "
983                        "not a snapshot (checkpoint number=%llu).\n",
984                        (unsigned long long)cno);
985                 ret = -EINVAL;
986                 goto out;
987         }
988 
989         ret = nilfs_attach_checkpoint(s, cno, false, &root);
990         if (ret) {
991                 printk(KERN_ERR "NILFS: error loading snapshot "
992                        "(checkpoint number=%llu).\n",
993                (unsigned long long)cno);
994                 goto out;
995         }
996         ret = nilfs_get_root_dentry(s, root, root_dentry);
997         nilfs_put_root(root);
998  out:
999         mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
1000         return ret;
1001 }
1002 
1003 /**
1004  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
1005  * @root_dentry: root dentry of the tree to be shrunk
1006  *
1007  * This function returns true if the tree was in-use.
1008  */
1009 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
1010 {
1011         shrink_dcache_parent(root_dentry);
1012         return d_count(root_dentry) > 1;
1013 }
1014 
1015 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1016 {
1017         struct the_nilfs *nilfs = sb->s_fs_info;
1018         struct nilfs_root *root;
1019         struct inode *inode;
1020         struct dentry *dentry;
1021         int ret;
1022 
1023         if (cno > nilfs->ns_cno)
1024                 return false;
1025 
1026         if (cno >= nilfs_last_cno(nilfs))
1027                 return true;    /* protect recent checkpoints */
1028 
1029         ret = false;
1030         root = nilfs_lookup_root(nilfs, cno);
1031         if (root) {
1032                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1033                 if (inode) {
1034                         dentry = d_find_alias(inode);
1035                         if (dentry) {
1036                                 ret = nilfs_tree_is_busy(dentry);
1037                                 dput(dentry);
1038                         }
1039                         iput(inode);
1040                 }
1041                 nilfs_put_root(root);
1042         }
1043         return ret;
1044 }
1045 
1046 /**
1047  * nilfs_fill_super() - initialize a super block instance
1048  * @sb: super_block
1049  * @data: mount options
1050  * @silent: silent mode flag
1051  *
1052  * This function is called exclusively by nilfs->ns_mount_mutex.
1053  * So, the recovery process is protected from other simultaneous mounts.
1054  */
1055 static int
1056 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1057 {
1058         struct the_nilfs *nilfs;
1059         struct nilfs_root *fsroot;
1060         __u64 cno;
1061         int err;
1062 
1063         nilfs = alloc_nilfs(sb->s_bdev);
1064         if (!nilfs)
1065                 return -ENOMEM;
1066 
1067         sb->s_fs_info = nilfs;
1068 
1069         err = init_nilfs(nilfs, sb, (char *)data);
1070         if (err)
1071                 goto failed_nilfs;
1072 
1073         sb->s_op = &nilfs_sops;
1074         sb->s_export_op = &nilfs_export_ops;
1075         sb->s_root = NULL;
1076         sb->s_time_gran = 1;
1077         sb->s_max_links = NILFS_LINK_MAX;
1078 
1079         sb->s_bdi = &bdev_get_queue(sb->s_bdev)->backing_dev_info;
1080 
1081         err = load_nilfs(nilfs, sb);
1082         if (err)
1083                 goto failed_nilfs;
1084 
1085         cno = nilfs_last_cno(nilfs);
1086         err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1087         if (err) {
1088                 printk(KERN_ERR "NILFS: error loading last checkpoint "
1089                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
1090                 goto failed_unload;
1091         }
1092 
1093         if (!(sb->s_flags & MS_RDONLY)) {
1094                 err = nilfs_attach_log_writer(sb, fsroot);
1095                 if (err)
1096                         goto failed_checkpoint;
1097         }
1098 
1099         err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1100         if (err)
1101                 goto failed_segctor;
1102 
1103         nilfs_put_root(fsroot);
1104 
1105         if (!(sb->s_flags & MS_RDONLY)) {
1106                 down_write(&nilfs->ns_sem);
1107                 nilfs_setup_super(sb, true);
1108                 up_write(&nilfs->ns_sem);
1109         }
1110 
1111         return 0;
1112 
1113  failed_segctor:
1114         nilfs_detach_log_writer(sb);
1115 
1116  failed_checkpoint:
1117         nilfs_put_root(fsroot);
1118 
1119  failed_unload:
1120         iput(nilfs->ns_sufile);
1121         iput(nilfs->ns_cpfile);
1122         iput(nilfs->ns_dat);
1123 
1124  failed_nilfs:
1125         destroy_nilfs(nilfs);
1126         return err;
1127 }
1128 
1129 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1130 {
1131         struct the_nilfs *nilfs = sb->s_fs_info;
1132         unsigned long old_sb_flags;
1133         unsigned long old_mount_opt;
1134         int err;
1135 
1136         sync_filesystem(sb);
1137         old_sb_flags = sb->s_flags;
1138         old_mount_opt = nilfs->ns_mount_opt;
1139 
1140         if (!parse_options(data, sb, 1)) {
1141                 err = -EINVAL;
1142                 goto restore_opts;
1143         }
1144         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1145 
1146         err = -EINVAL;
1147 
1148         if (!nilfs_valid_fs(nilfs)) {
1149                 printk(KERN_WARNING "NILFS (device %s): couldn't "
1150                        "remount because the filesystem is in an "
1151                        "incomplete recovery state.\n", sb->s_id);
1152                 goto restore_opts;
1153         }
1154 
1155         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1156                 goto out;
1157         if (*flags & MS_RDONLY) {
1158                 /* Shutting down log writer */
1159                 nilfs_detach_log_writer(sb);
1160                 sb->s_flags |= MS_RDONLY;
1161 
1162                 /*
1163                  * Remounting a valid RW partition RDONLY, so set
1164                  * the RDONLY flag and then mark the partition as valid again.
1165                  */
1166                 down_write(&nilfs->ns_sem);
1167                 nilfs_cleanup_super(sb);
1168                 up_write(&nilfs->ns_sem);
1169         } else {
1170                 __u64 features;
1171                 struct nilfs_root *root;
1172 
1173                 /*
1174                  * Mounting a RDONLY partition read-write, so reread and
1175                  * store the current valid flag.  (It may have been changed
1176                  * by fsck since we originally mounted the partition.)
1177                  */
1178                 down_read(&nilfs->ns_sem);
1179                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1180                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
1181                 up_read(&nilfs->ns_sem);
1182                 if (features) {
1183                         printk(KERN_WARNING "NILFS (device %s): couldn't "
1184                                "remount RDWR because of unsupported optional "
1185                                "features (%llx)\n",
1186                                sb->s_id, (unsigned long long)features);
1187                         err = -EROFS;
1188                         goto restore_opts;
1189                 }
1190 
1191                 sb->s_flags &= ~MS_RDONLY;
1192 
1193                 root = NILFS_I(d_inode(sb->s_root))->i_root;
1194                 err = nilfs_attach_log_writer(sb, root);
1195                 if (err)
1196                         goto restore_opts;
1197 
1198                 down_write(&nilfs->ns_sem);
1199                 nilfs_setup_super(sb, true);
1200                 up_write(&nilfs->ns_sem);
1201         }
1202  out:
1203         return 0;
1204 
1205  restore_opts:
1206         sb->s_flags = old_sb_flags;
1207         nilfs->ns_mount_opt = old_mount_opt;
1208         return err;
1209 }
1210 
1211 struct nilfs_super_data {
1212         struct block_device *bdev;
1213         __u64 cno;
1214         int flags;
1215 };
1216 
1217 /**
1218  * nilfs_identify - pre-read mount options needed to identify mount instance
1219  * @data: mount options
1220  * @sd: nilfs_super_data
1221  */
1222 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1223 {
1224         char *p, *options = data;
1225         substring_t args[MAX_OPT_ARGS];
1226         int token;
1227         int ret = 0;
1228 
1229         do {
1230                 p = strsep(&options, ",");
1231                 if (p != NULL && *p) {
1232                         token = match_token(p, tokens, args);
1233                         if (token == Opt_snapshot) {
1234                                 if (!(sd->flags & MS_RDONLY)) {
1235                                         ret++;
1236                                 } else {
1237                                         sd->cno = simple_strtoull(args[0].from,
1238                                                                   NULL, 0);
1239                                         /*
1240                                          * No need to see the end pointer;
1241                                          * match_token() has done syntax
1242                                          * checking.
1243                                          */
1244                                         if (sd->cno == 0)
1245                                                 ret++;
1246                                 }
1247                         }
1248                         if (ret)
1249                                 printk(KERN_ERR
1250                                        "NILFS: invalid mount option: %s\n", p);
1251                 }
1252                 if (!options)
1253                         break;
1254                 BUG_ON(options == data);
1255                 *(options - 1) = ',';
1256         } while (!ret);
1257         return ret;
1258 }
1259 
1260 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1261 {
1262         s->s_bdev = data;
1263         s->s_dev = s->s_bdev->bd_dev;
1264         return 0;
1265 }
1266 
1267 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1268 {
1269         return (void *)s->s_bdev == data;
1270 }
1271 
1272 static struct dentry *
1273 nilfs_mount(struct file_system_type *fs_type, int flags,
1274              const char *dev_name, void *data)
1275 {
1276         struct nilfs_super_data sd;
1277         struct super_block *s;
1278         fmode_t mode = FMODE_READ | FMODE_EXCL;
1279         struct dentry *root_dentry;
1280         int err, s_new = false;
1281 
1282         if (!(flags & MS_RDONLY))
1283                 mode |= FMODE_WRITE;
1284 
1285         sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1286         if (IS_ERR(sd.bdev))
1287                 return ERR_CAST(sd.bdev);
1288 
1289         sd.cno = 0;
1290         sd.flags = flags;
1291         if (nilfs_identify((char *)data, &sd)) {
1292                 err = -EINVAL;
1293                 goto failed;
1294         }
1295 
1296         /*
1297          * once the super is inserted into the list by sget, s_umount
1298          * will protect the lockfs code from trying to start a snapshot
1299          * while we are mounting
1300          */
1301         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1302         if (sd.bdev->bd_fsfreeze_count > 0) {
1303                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1304                 err = -EBUSY;
1305                 goto failed;
1306         }
1307         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1308                  sd.bdev);
1309         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1310         if (IS_ERR(s)) {
1311                 err = PTR_ERR(s);
1312                 goto failed;
1313         }
1314 
1315         if (!s->s_root) {
1316                 char b[BDEVNAME_SIZE];
1317 
1318                 s_new = true;
1319 
1320                 /* New superblock instance created */
1321                 s->s_mode = mode;
1322                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1323                 sb_set_blocksize(s, block_size(sd.bdev));
1324 
1325                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1326                 if (err)
1327                         goto failed_super;
1328 
1329                 s->s_flags |= MS_ACTIVE;
1330         } else if (!sd.cno) {
1331                 if (nilfs_tree_is_busy(s->s_root)) {
1332                         if ((flags ^ s->s_flags) & MS_RDONLY) {
1333                                 printk(KERN_ERR "NILFS: the device already "
1334                                        "has a %s mount.\n",
1335                                        (s->s_flags & MS_RDONLY) ?
1336                                        "read-only" : "read/write");
1337                                 err = -EBUSY;
1338                                 goto failed_super;
1339                         }
1340                 } else {
1341                         /*
1342                          * Try remount to setup mount states if the current
1343                          * tree is not mounted and only snapshots use this sb.
1344                          */
1345                         err = nilfs_remount(s, &flags, data);
1346                         if (err)
1347                                 goto failed_super;
1348                 }
1349         }
1350 
1351         if (sd.cno) {
1352                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1353                 if (err)
1354                         goto failed_super;
1355         } else {
1356                 root_dentry = dget(s->s_root);
1357         }
1358 
1359         if (!s_new)
1360                 blkdev_put(sd.bdev, mode);
1361 
1362         return root_dentry;
1363 
1364  failed_super:
1365         deactivate_locked_super(s);
1366 
1367  failed:
1368         if (!s_new)
1369                 blkdev_put(sd.bdev, mode);
1370         return ERR_PTR(err);
1371 }
1372 
1373 struct file_system_type nilfs_fs_type = {
1374         .owner    = THIS_MODULE,
1375         .name     = "nilfs2",
1376         .mount    = nilfs_mount,
1377         .kill_sb  = kill_block_super,
1378         .fs_flags = FS_REQUIRES_DEV,
1379 };
1380 MODULE_ALIAS_FS("nilfs2");
1381 
1382 static void nilfs_inode_init_once(void *obj)
1383 {
1384         struct nilfs_inode_info *ii = obj;
1385 
1386         INIT_LIST_HEAD(&ii->i_dirty);
1387 #ifdef CONFIG_NILFS_XATTR
1388         init_rwsem(&ii->xattr_sem);
1389 #endif
1390         address_space_init_once(&ii->i_btnode_cache);
1391         ii->i_bmap = &ii->i_bmap_data;
1392         inode_init_once(&ii->vfs_inode);
1393 }
1394 
1395 static void nilfs_segbuf_init_once(void *obj)
1396 {
1397         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1398 }
1399 
1400 static void nilfs_destroy_cachep(void)
1401 {
1402         /*
1403          * Make sure all delayed rcu free inodes are flushed before we
1404          * destroy cache.
1405          */
1406         rcu_barrier();
1407 
1408         if (nilfs_inode_cachep)
1409                 kmem_cache_destroy(nilfs_inode_cachep);
1410         if (nilfs_transaction_cachep)
1411                 kmem_cache_destroy(nilfs_transaction_cachep);
1412         if (nilfs_segbuf_cachep)
1413                 kmem_cache_destroy(nilfs_segbuf_cachep);
1414         if (nilfs_btree_path_cache)
1415                 kmem_cache_destroy(nilfs_btree_path_cache);
1416 }
1417 
1418 static int __init nilfs_init_cachep(void)
1419 {
1420         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1421                         sizeof(struct nilfs_inode_info), 0,
1422                         SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
1423         if (!nilfs_inode_cachep)
1424                 goto fail;
1425 
1426         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1427                         sizeof(struct nilfs_transaction_info), 0,
1428                         SLAB_RECLAIM_ACCOUNT, NULL);
1429         if (!nilfs_transaction_cachep)
1430                 goto fail;
1431 
1432         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1433                         sizeof(struct nilfs_segment_buffer), 0,
1434                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1435         if (!nilfs_segbuf_cachep)
1436                 goto fail;
1437 
1438         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1439                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1440                         0, 0, NULL);
1441         if (!nilfs_btree_path_cache)
1442                 goto fail;
1443 
1444         return 0;
1445 
1446 fail:
1447         nilfs_destroy_cachep();
1448         return -ENOMEM;
1449 }
1450 
1451 static int __init init_nilfs_fs(void)
1452 {
1453         int err;
1454 
1455         err = nilfs_init_cachep();
1456         if (err)
1457                 goto fail;
1458 
1459         err = nilfs_sysfs_init();
1460         if (err)
1461                 goto free_cachep;
1462 
1463         err = register_filesystem(&nilfs_fs_type);
1464         if (err)
1465                 goto deinit_sysfs_entry;
1466 
1467         printk(KERN_INFO "NILFS version 2 loaded\n");
1468         return 0;
1469 
1470 deinit_sysfs_entry:
1471         nilfs_sysfs_exit();
1472 free_cachep:
1473         nilfs_destroy_cachep();
1474 fail:
1475         return err;
1476 }
1477 
1478 static void __exit exit_nilfs_fs(void)
1479 {
1480         nilfs_destroy_cachep();
1481         nilfs_sysfs_exit();
1482         unregister_filesystem(&nilfs_fs_type);
1483 }
1484 
1485 module_init(init_nilfs_fs)
1486 module_exit(exit_nilfs_fs)
1487 

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