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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, sb->s_bdi);
170         return &ii->vfs_inode;
171 }
172 
173 static void nilfs_i_callback(struct rcu_head *head)
174 {
175         struct inode *inode = container_of(head, struct inode, i_rcu);
176         struct nilfs_mdt_info *mdi = NILFS_MDT(inode);
177 
178         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         return nilfs_sync_super(sb, flag);
314 }
315 
316 /**
317  * nilfs_cleanup_super() - write filesystem state for cleanup
318  * @sb: super block instance to be unmounted or degraded to read-only
319  *
320  * This function restores state flags in the on-disk super block.
321  * This will set "clean" flag (i.e. NILFS_VALID_FS) unless the
322  * filesystem was not clean previously.
323  */
324 int nilfs_cleanup_super(struct super_block *sb)
325 {
326         struct the_nilfs *nilfs = sb->s_fs_info;
327         struct nilfs_super_block **sbp;
328         int flag = NILFS_SB_COMMIT;
329         int ret = -EIO;
330 
331         sbp = nilfs_prepare_super(sb, 0);
332         if (sbp) {
333                 sbp[0]->s_state = cpu_to_le16(nilfs->ns_mount_state);
334                 nilfs_set_log_cursor(sbp[0], nilfs);
335                 if (sbp[1] && sbp[0]->s_last_cno == sbp[1]->s_last_cno) {
336                         /*
337                          * make the "clean" flag also to the opposite
338                          * super block if both super blocks point to
339                          * the same checkpoint.
340                          */
341                         sbp[1]->s_state = sbp[0]->s_state;
342                         flag = NILFS_SB_COMMIT_ALL;
343                 }
344                 ret = nilfs_commit_super(sb, flag);
345         }
346         return ret;
347 }
348 
349 /**
350  * nilfs_move_2nd_super - relocate secondary super block
351  * @sb: super block instance
352  * @sb2off: new offset of the secondary super block (in bytes)
353  */
354 static int nilfs_move_2nd_super(struct super_block *sb, loff_t sb2off)
355 {
356         struct the_nilfs *nilfs = sb->s_fs_info;
357         struct buffer_head *nsbh;
358         struct nilfs_super_block *nsbp;
359         sector_t blocknr, newblocknr;
360         unsigned long offset;
361         int sb2i = -1;  /* array index of the secondary superblock */
362         int ret = 0;
363 
364         /* nilfs->ns_sem must be locked by the caller. */
365         if (nilfs->ns_sbh[1] &&
366             nilfs->ns_sbh[1]->b_blocknr > nilfs->ns_first_data_block) {
367                 sb2i = 1;
368                 blocknr = nilfs->ns_sbh[1]->b_blocknr;
369         } else if (nilfs->ns_sbh[0]->b_blocknr > nilfs->ns_first_data_block) {
370                 sb2i = 0;
371                 blocknr = nilfs->ns_sbh[0]->b_blocknr;
372         }
373         if (sb2i >= 0 && (u64)blocknr << nilfs->ns_blocksize_bits == sb2off)
374                 goto out;  /* super block location is unchanged */
375 
376         /* Get new super block buffer */
377         newblocknr = sb2off >> nilfs->ns_blocksize_bits;
378         offset = sb2off & (nilfs->ns_blocksize - 1);
379         nsbh = sb_getblk(sb, newblocknr);
380         if (!nsbh) {
381                 printk(KERN_WARNING
382                        "NILFS warning: unable to move secondary superblock "
383                        "to block %llu\n", (unsigned long long)newblocknr);
384                 ret = -EIO;
385                 goto out;
386         }
387         nsbp = (void *)nsbh->b_data + offset;
388         memset(nsbp, 0, nilfs->ns_blocksize);
389 
390         if (sb2i >= 0) {
391                 memcpy(nsbp, nilfs->ns_sbp[sb2i], nilfs->ns_sbsize);
392                 brelse(nilfs->ns_sbh[sb2i]);
393                 nilfs->ns_sbh[sb2i] = nsbh;
394                 nilfs->ns_sbp[sb2i] = nsbp;
395         } else if (nilfs->ns_sbh[0]->b_blocknr < nilfs->ns_first_data_block) {
396                 /* secondary super block will be restored to index 1 */
397                 nilfs->ns_sbh[1] = nsbh;
398                 nilfs->ns_sbp[1] = nsbp;
399         } else {
400                 brelse(nsbh);
401         }
402 out:
403         return ret;
404 }
405 
406 /**
407  * nilfs_resize_fs - resize the filesystem
408  * @sb: super block instance
409  * @newsize: new size of the filesystem (in bytes)
410  */
411 int nilfs_resize_fs(struct super_block *sb, __u64 newsize)
412 {
413         struct the_nilfs *nilfs = sb->s_fs_info;
414         struct nilfs_super_block **sbp;
415         __u64 devsize, newnsegs;
416         loff_t sb2off;
417         int ret;
418 
419         ret = -ERANGE;
420         devsize = i_size_read(sb->s_bdev->bd_inode);
421         if (newsize > devsize)
422                 goto out;
423 
424         /*
425          * Write lock is required to protect some functions depending
426          * on the number of segments, the number of reserved segments,
427          * and so forth.
428          */
429         down_write(&nilfs->ns_segctor_sem);
430 
431         sb2off = NILFS_SB2_OFFSET_BYTES(newsize);
432         newnsegs = sb2off >> nilfs->ns_blocksize_bits;
433         do_div(newnsegs, nilfs->ns_blocks_per_segment);
434 
435         ret = nilfs_sufile_resize(nilfs->ns_sufile, newnsegs);
436         up_write(&nilfs->ns_segctor_sem);
437         if (ret < 0)
438                 goto out;
439 
440         ret = nilfs_construct_segment(sb);
441         if (ret < 0)
442                 goto out;
443 
444         down_write(&nilfs->ns_sem);
445         nilfs_move_2nd_super(sb, sb2off);
446         ret = -EIO;
447         sbp = nilfs_prepare_super(sb, 0);
448         if (likely(sbp)) {
449                 nilfs_set_log_cursor(sbp[0], nilfs);
450                 /*
451                  * Drop NILFS_RESIZE_FS flag for compatibility with
452                  * mount-time resize which may be implemented in a
453                  * future release.
454                  */
455                 sbp[0]->s_state = cpu_to_le16(le16_to_cpu(sbp[0]->s_state) &
456                                               ~NILFS_RESIZE_FS);
457                 sbp[0]->s_dev_size = cpu_to_le64(newsize);
458                 sbp[0]->s_nsegments = cpu_to_le64(nilfs->ns_nsegments);
459                 if (sbp[1])
460                         memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
461                 ret = nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
462         }
463         up_write(&nilfs->ns_sem);
464 
465         /*
466          * Reset the range of allocatable segments last.  This order
467          * is important in the case of expansion because the secondary
468          * superblock must be protected from log write until migration
469          * completes.
470          */
471         if (!ret)
472                 nilfs_sufile_set_alloc_range(nilfs->ns_sufile, 0, newnsegs - 1);
473 out:
474         return ret;
475 }
476 
477 static void nilfs_put_super(struct super_block *sb)
478 {
479         struct the_nilfs *nilfs = sb->s_fs_info;
480 
481         nilfs_detach_log_writer(sb);
482 
483         if (!(sb->s_flags & MS_RDONLY)) {
484                 down_write(&nilfs->ns_sem);
485                 nilfs_cleanup_super(sb);
486                 up_write(&nilfs->ns_sem);
487         }
488 
489         iput(nilfs->ns_sufile);
490         iput(nilfs->ns_cpfile);
491         iput(nilfs->ns_dat);
492 
493         destroy_nilfs(nilfs);
494         sb->s_fs_info = NULL;
495 }
496 
497 static int nilfs_sync_fs(struct super_block *sb, int wait)
498 {
499         struct the_nilfs *nilfs = sb->s_fs_info;
500         struct nilfs_super_block **sbp;
501         int err = 0;
502 
503         /* This function is called when super block should be written back */
504         if (wait)
505                 err = nilfs_construct_segment(sb);
506 
507         down_write(&nilfs->ns_sem);
508         if (nilfs_sb_dirty(nilfs)) {
509                 sbp = nilfs_prepare_super(sb, nilfs_sb_will_flip(nilfs));
510                 if (likely(sbp)) {
511                         nilfs_set_log_cursor(sbp[0], nilfs);
512                         nilfs_commit_super(sb, NILFS_SB_COMMIT);
513                 }
514         }
515         up_write(&nilfs->ns_sem);
516 
517         return err;
518 }
519 
520 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
521                             struct nilfs_root **rootp)
522 {
523         struct the_nilfs *nilfs = sb->s_fs_info;
524         struct nilfs_root *root;
525         struct nilfs_checkpoint *raw_cp;
526         struct buffer_head *bh_cp;
527         int err = -ENOMEM;
528 
529         root = nilfs_find_or_create_root(
530                 nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
531         if (!root)
532                 return err;
533 
534         if (root->ifile)
535                 goto reuse; /* already attached checkpoint */
536 
537         down_read(&nilfs->ns_segctor_sem);
538         err = nilfs_cpfile_get_checkpoint(nilfs->ns_cpfile, cno, 0, &raw_cp,
539                                           &bh_cp);
540         up_read(&nilfs->ns_segctor_sem);
541         if (unlikely(err)) {
542                 if (err == -ENOENT || err == -EINVAL) {
543                         printk(KERN_ERR
544                                "NILFS: Invalid checkpoint "
545                                "(checkpoint number=%llu)\n",
546                                (unsigned long long)cno);
547                         err = -EINVAL;
548                 }
549                 goto failed;
550         }
551 
552         err = nilfs_ifile_read(sb, root, nilfs->ns_inode_size,
553                                &raw_cp->cp_ifile_inode, &root->ifile);
554         if (err)
555                 goto failed_bh;
556 
557         atomic64_set(&root->inodes_count,
558                         le64_to_cpu(raw_cp->cp_inodes_count));
559         atomic64_set(&root->blocks_count,
560                         le64_to_cpu(raw_cp->cp_blocks_count));
561 
562         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
563 
564  reuse:
565         *rootp = root;
566         return 0;
567 
568  failed_bh:
569         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
570  failed:
571         nilfs_put_root(root);
572 
573         return err;
574 }
575 
576 static int nilfs_freeze(struct super_block *sb)
577 {
578         struct the_nilfs *nilfs = sb->s_fs_info;
579         int err;
580 
581         if (sb->s_flags & MS_RDONLY)
582                 return 0;
583 
584         /* Mark super block clean */
585         down_write(&nilfs->ns_sem);
586         err = nilfs_cleanup_super(sb);
587         up_write(&nilfs->ns_sem);
588         return err;
589 }
590 
591 static int nilfs_unfreeze(struct super_block *sb)
592 {
593         struct the_nilfs *nilfs = sb->s_fs_info;
594 
595         if (sb->s_flags & MS_RDONLY)
596                 return 0;
597 
598         down_write(&nilfs->ns_sem);
599         nilfs_setup_super(sb, false);
600         up_write(&nilfs->ns_sem);
601         return 0;
602 }
603 
604 static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
605 {
606         struct super_block *sb = dentry->d_sb;
607         struct nilfs_root *root = NILFS_I(dentry->d_inode)->i_root;
608         struct the_nilfs *nilfs = root->nilfs;
609         u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
610         unsigned long long blocks;
611         unsigned long overhead;
612         unsigned long nrsvblocks;
613         sector_t nfreeblocks;
614         u64 nmaxinodes, nfreeinodes;
615         int err;
616 
617         /*
618          * Compute all of the segment blocks
619          *
620          * The blocks before first segment and after last segment
621          * are excluded.
622          */
623         blocks = nilfs->ns_blocks_per_segment * nilfs->ns_nsegments
624                 - nilfs->ns_first_data_block;
625         nrsvblocks = nilfs->ns_nrsvsegs * nilfs->ns_blocks_per_segment;
626 
627         /*
628          * Compute the overhead
629          *
630          * When distributing meta data blocks outside segment structure,
631          * We must count them as the overhead.
632          */
633         overhead = 0;
634 
635         err = nilfs_count_free_blocks(nilfs, &nfreeblocks);
636         if (unlikely(err))
637                 return err;
638 
639         err = nilfs_ifile_count_free_inodes(root->ifile,
640                                             &nmaxinodes, &nfreeinodes);
641         if (unlikely(err)) {
642                 printk(KERN_WARNING
643                         "NILFS warning: fail to count free inodes: err %d.\n",
644                         err);
645                 if (err == -ERANGE) {
646                         /*
647                          * If nilfs_palloc_count_max_entries() returns
648                          * -ERANGE error code then we simply treat
649                          * curent inodes count as maximum possible and
650                          * zero as free inodes value.
651                          */
652                         nmaxinodes = atomic64_read(&root->inodes_count);
653                         nfreeinodes = 0;
654                         err = 0;
655                 } else
656                         return err;
657         }
658 
659         buf->f_type = NILFS_SUPER_MAGIC;
660         buf->f_bsize = sb->s_blocksize;
661         buf->f_blocks = blocks - overhead;
662         buf->f_bfree = nfreeblocks;
663         buf->f_bavail = (buf->f_bfree >= nrsvblocks) ?
664                 (buf->f_bfree - nrsvblocks) : 0;
665         buf->f_files = nmaxinodes;
666         buf->f_ffree = nfreeinodes;
667         buf->f_namelen = NILFS_NAME_LEN;
668         buf->f_fsid.val[0] = (u32)id;
669         buf->f_fsid.val[1] = (u32)(id >> 32);
670 
671         return 0;
672 }
673 
674 static int nilfs_show_options(struct seq_file *seq, struct dentry *dentry)
675 {
676         struct super_block *sb = dentry->d_sb;
677         struct the_nilfs *nilfs = sb->s_fs_info;
678         struct nilfs_root *root = NILFS_I(dentry->d_inode)->i_root;
679 
680         if (!nilfs_test_opt(nilfs, BARRIER))
681                 seq_puts(seq, ",nobarrier");
682         if (root->cno != NILFS_CPTREE_CURRENT_CNO)
683                 seq_printf(seq, ",cp=%llu", (unsigned long long)root->cno);
684         if (nilfs_test_opt(nilfs, ERRORS_PANIC))
685                 seq_puts(seq, ",errors=panic");
686         if (nilfs_test_opt(nilfs, ERRORS_CONT))
687                 seq_puts(seq, ",errors=continue");
688         if (nilfs_test_opt(nilfs, STRICT_ORDER))
689                 seq_puts(seq, ",order=strict");
690         if (nilfs_test_opt(nilfs, NORECOVERY))
691                 seq_puts(seq, ",norecovery");
692         if (nilfs_test_opt(nilfs, DISCARD))
693                 seq_puts(seq, ",discard");
694 
695         return 0;
696 }
697 
698 static const struct super_operations nilfs_sops = {
699         .alloc_inode    = nilfs_alloc_inode,
700         .destroy_inode  = nilfs_destroy_inode,
701         .dirty_inode    = nilfs_dirty_inode,
702         .evict_inode    = nilfs_evict_inode,
703         .put_super      = nilfs_put_super,
704         .sync_fs        = nilfs_sync_fs,
705         .freeze_fs      = nilfs_freeze,
706         .unfreeze_fs    = nilfs_unfreeze,
707         .statfs         = nilfs_statfs,
708         .remount_fs     = nilfs_remount,
709         .show_options = nilfs_show_options
710 };
711 
712 enum {
713         Opt_err_cont, Opt_err_panic, Opt_err_ro,
714         Opt_barrier, Opt_nobarrier, Opt_snapshot, Opt_order, Opt_norecovery,
715         Opt_discard, Opt_nodiscard, Opt_err,
716 };
717 
718 static match_table_t tokens = {
719         {Opt_err_cont, "errors=continue"},
720         {Opt_err_panic, "errors=panic"},
721         {Opt_err_ro, "errors=remount-ro"},
722         {Opt_barrier, "barrier"},
723         {Opt_nobarrier, "nobarrier"},
724         {Opt_snapshot, "cp=%u"},
725         {Opt_order, "order=%s"},
726         {Opt_norecovery, "norecovery"},
727         {Opt_discard, "discard"},
728         {Opt_nodiscard, "nodiscard"},
729         {Opt_err, NULL}
730 };
731 
732 static int parse_options(char *options, struct super_block *sb, int is_remount)
733 {
734         struct the_nilfs *nilfs = sb->s_fs_info;
735         char *p;
736         substring_t args[MAX_OPT_ARGS];
737 
738         if (!options)
739                 return 1;
740 
741         while ((p = strsep(&options, ",")) != NULL) {
742                 int token;
743                 if (!*p)
744                         continue;
745 
746                 token = match_token(p, tokens, args);
747                 switch (token) {
748                 case Opt_barrier:
749                         nilfs_set_opt(nilfs, BARRIER);
750                         break;
751                 case Opt_nobarrier:
752                         nilfs_clear_opt(nilfs, BARRIER);
753                         break;
754                 case Opt_order:
755                         if (strcmp(args[0].from, "relaxed") == 0)
756                                 /* Ordered data semantics */
757                                 nilfs_clear_opt(nilfs, STRICT_ORDER);
758                         else if (strcmp(args[0].from, "strict") == 0)
759                                 /* Strict in-order semantics */
760                                 nilfs_set_opt(nilfs, STRICT_ORDER);
761                         else
762                                 return 0;
763                         break;
764                 case Opt_err_panic:
765                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_PANIC);
766                         break;
767                 case Opt_err_ro:
768                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_RO);
769                         break;
770                 case Opt_err_cont:
771                         nilfs_write_opt(nilfs, ERROR_MODE, ERRORS_CONT);
772                         break;
773                 case Opt_snapshot:
774                         if (is_remount) {
775                                 printk(KERN_ERR
776                                        "NILFS: \"%s\" option is invalid "
777                                        "for remount.\n", p);
778                                 return 0;
779                         }
780                         break;
781                 case Opt_norecovery:
782                         nilfs_set_opt(nilfs, NORECOVERY);
783                         break;
784                 case Opt_discard:
785                         nilfs_set_opt(nilfs, DISCARD);
786                         break;
787                 case Opt_nodiscard:
788                         nilfs_clear_opt(nilfs, DISCARD);
789                         break;
790                 default:
791                         printk(KERN_ERR
792                                "NILFS: Unrecognized mount option \"%s\"\n", p);
793                         return 0;
794                 }
795         }
796         return 1;
797 }
798 
799 static inline void
800 nilfs_set_default_options(struct super_block *sb,
801                           struct nilfs_super_block *sbp)
802 {
803         struct the_nilfs *nilfs = sb->s_fs_info;
804 
805         nilfs->ns_mount_opt =
806                 NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
807 }
808 
809 static int nilfs_setup_super(struct super_block *sb, int is_mount)
810 {
811         struct the_nilfs *nilfs = sb->s_fs_info;
812         struct nilfs_super_block **sbp;
813         int max_mnt_count;
814         int mnt_count;
815 
816         /* nilfs->ns_sem must be locked by the caller. */
817         sbp = nilfs_prepare_super(sb, 0);
818         if (!sbp)
819                 return -EIO;
820 
821         if (!is_mount)
822                 goto skip_mount_setup;
823 
824         max_mnt_count = le16_to_cpu(sbp[0]->s_max_mnt_count);
825         mnt_count = le16_to_cpu(sbp[0]->s_mnt_count);
826 
827         if (nilfs->ns_mount_state & NILFS_ERROR_FS) {
828                 printk(KERN_WARNING
829                        "NILFS warning: mounting fs with errors\n");
830 #if 0
831         } else if (max_mnt_count >= 0 && mnt_count >= max_mnt_count) {
832                 printk(KERN_WARNING
833                        "NILFS warning: maximal mount count reached\n");
834 #endif
835         }
836         if (!max_mnt_count)
837                 sbp[0]->s_max_mnt_count = cpu_to_le16(NILFS_DFL_MAX_MNT_COUNT);
838 
839         sbp[0]->s_mnt_count = cpu_to_le16(mnt_count + 1);
840         sbp[0]->s_mtime = cpu_to_le64(get_seconds());
841 
842 skip_mount_setup:
843         sbp[0]->s_state =
844                 cpu_to_le16(le16_to_cpu(sbp[0]->s_state) & ~NILFS_VALID_FS);
845         /* synchronize sbp[1] with sbp[0] */
846         if (sbp[1])
847                 memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
848         return nilfs_commit_super(sb, NILFS_SB_COMMIT_ALL);
849 }
850 
851 struct nilfs_super_block *nilfs_read_super_block(struct super_block *sb,
852                                                  u64 pos, int blocksize,
853                                                  struct buffer_head **pbh)
854 {
855         unsigned long long sb_index = pos;
856         unsigned long offset;
857 
858         offset = do_div(sb_index, blocksize);
859         *pbh = sb_bread(sb, sb_index);
860         if (!*pbh)
861                 return NULL;
862         return (struct nilfs_super_block *)((char *)(*pbh)->b_data + offset);
863 }
864 
865 int nilfs_store_magic_and_option(struct super_block *sb,
866                                  struct nilfs_super_block *sbp,
867                                  char *data)
868 {
869         struct the_nilfs *nilfs = sb->s_fs_info;
870 
871         sb->s_magic = le16_to_cpu(sbp->s_magic);
872 
873         /* FS independent flags */
874 #ifdef NILFS_ATIME_DISABLE
875         sb->s_flags |= MS_NOATIME;
876 #endif
877 
878         nilfs_set_default_options(sb, sbp);
879 
880         nilfs->ns_resuid = le16_to_cpu(sbp->s_def_resuid);
881         nilfs->ns_resgid = le16_to_cpu(sbp->s_def_resgid);
882         nilfs->ns_interval = le32_to_cpu(sbp->s_c_interval);
883         nilfs->ns_watermark = le32_to_cpu(sbp->s_c_block_max);
884 
885         return !parse_options(data, sb, 0) ? -EINVAL : 0 ;
886 }
887 
888 int nilfs_check_feature_compatibility(struct super_block *sb,
889                                       struct nilfs_super_block *sbp)
890 {
891         __u64 features;
892 
893         features = le64_to_cpu(sbp->s_feature_incompat) &
894                 ~NILFS_FEATURE_INCOMPAT_SUPP;
895         if (features) {
896                 printk(KERN_ERR "NILFS: couldn't mount because of unsupported "
897                        "optional features (%llx)\n",
898                        (unsigned long long)features);
899                 return -EINVAL;
900         }
901         features = le64_to_cpu(sbp->s_feature_compat_ro) &
902                 ~NILFS_FEATURE_COMPAT_RO_SUPP;
903         if (!(sb->s_flags & MS_RDONLY) && features) {
904                 printk(KERN_ERR "NILFS: couldn't mount RDWR because of "
905                        "unsupported optional features (%llx)\n",
906                        (unsigned long long)features);
907                 return -EINVAL;
908         }
909         return 0;
910 }
911 
912 static int nilfs_get_root_dentry(struct super_block *sb,
913                                  struct nilfs_root *root,
914                                  struct dentry **root_dentry)
915 {
916         struct inode *inode;
917         struct dentry *dentry;
918         int ret = 0;
919 
920         inode = nilfs_iget(sb, root, NILFS_ROOT_INO);
921         if (IS_ERR(inode)) {
922                 printk(KERN_ERR "NILFS: get root inode failed\n");
923                 ret = PTR_ERR(inode);
924                 goto out;
925         }
926         if (!S_ISDIR(inode->i_mode) || !inode->i_blocks || !inode->i_size) {
927                 iput(inode);
928                 printk(KERN_ERR "NILFS: corrupt root inode.\n");
929                 ret = -EINVAL;
930                 goto out;
931         }
932 
933         if (root->cno == NILFS_CPTREE_CURRENT_CNO) {
934                 dentry = d_find_alias(inode);
935                 if (!dentry) {
936                         dentry = d_make_root(inode);
937                         if (!dentry) {
938                                 ret = -ENOMEM;
939                                 goto failed_dentry;
940                         }
941                 } else {
942                         iput(inode);
943                 }
944         } else {
945                 dentry = d_obtain_alias(inode);
946                 if (IS_ERR(dentry)) {
947                         ret = PTR_ERR(dentry);
948                         goto failed_dentry;
949                 }
950         }
951         *root_dentry = dentry;
952  out:
953         return ret;
954 
955  failed_dentry:
956         printk(KERN_ERR "NILFS: get root dentry failed\n");
957         goto out;
958 }
959 
960 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
961                                  struct dentry **root_dentry)
962 {
963         struct the_nilfs *nilfs = s->s_fs_info;
964         struct nilfs_root *root;
965         int ret;
966 
967         mutex_lock(&nilfs->ns_snapshot_mount_mutex);
968 
969         down_read(&nilfs->ns_segctor_sem);
970         ret = nilfs_cpfile_is_snapshot(nilfs->ns_cpfile, cno);
971         up_read(&nilfs->ns_segctor_sem);
972         if (ret < 0) {
973                 ret = (ret == -ENOENT) ? -EINVAL : ret;
974                 goto out;
975         } else if (!ret) {
976                 printk(KERN_ERR "NILFS: The specified checkpoint is "
977                        "not a snapshot (checkpoint number=%llu).\n",
978                        (unsigned long long)cno);
979                 ret = -EINVAL;
980                 goto out;
981         }
982 
983         ret = nilfs_attach_checkpoint(s, cno, false, &root);
984         if (ret) {
985                 printk(KERN_ERR "NILFS: error loading snapshot "
986                        "(checkpoint number=%llu).\n",
987                (unsigned long long)cno);
988                 goto out;
989         }
990         ret = nilfs_get_root_dentry(s, root, root_dentry);
991         nilfs_put_root(root);
992  out:
993         mutex_unlock(&nilfs->ns_snapshot_mount_mutex);
994         return ret;
995 }
996 
997 /**
998  * nilfs_tree_is_busy() - try to shrink dentries of a checkpoint
999  * @root_dentry: root dentry of the tree to be shrunk
1000  *
1001  * This function returns true if the tree was in-use.
1002  */
1003 static bool nilfs_tree_is_busy(struct dentry *root_dentry)
1004 {
1005         shrink_dcache_parent(root_dentry);
1006         return d_count(root_dentry) > 1;
1007 }
1008 
1009 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
1010 {
1011         struct the_nilfs *nilfs = sb->s_fs_info;
1012         struct nilfs_root *root;
1013         struct inode *inode;
1014         struct dentry *dentry;
1015         int ret;
1016 
1017         if (cno < 0 || cno > nilfs->ns_cno)
1018                 return false;
1019 
1020         if (cno >= nilfs_last_cno(nilfs))
1021                 return true;    /* protect recent checkpoints */
1022 
1023         ret = false;
1024         root = nilfs_lookup_root(nilfs, cno);
1025         if (root) {
1026                 inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
1027                 if (inode) {
1028                         dentry = d_find_alias(inode);
1029                         if (dentry) {
1030                                 ret = nilfs_tree_is_busy(dentry);
1031                                 dput(dentry);
1032                         }
1033                         iput(inode);
1034                 }
1035                 nilfs_put_root(root);
1036         }
1037         return ret;
1038 }
1039 
1040 /**
1041  * nilfs_fill_super() - initialize a super block instance
1042  * @sb: super_block
1043  * @data: mount options
1044  * @silent: silent mode flag
1045  *
1046  * This function is called exclusively by nilfs->ns_mount_mutex.
1047  * So, the recovery process is protected from other simultaneous mounts.
1048  */
1049 static int
1050 nilfs_fill_super(struct super_block *sb, void *data, int silent)
1051 {
1052         struct the_nilfs *nilfs;
1053         struct nilfs_root *fsroot;
1054         struct backing_dev_info *bdi;
1055         __u64 cno;
1056         int err;
1057 
1058         nilfs = alloc_nilfs(sb->s_bdev);
1059         if (!nilfs)
1060                 return -ENOMEM;
1061 
1062         sb->s_fs_info = nilfs;
1063 
1064         err = init_nilfs(nilfs, sb, (char *)data);
1065         if (err)
1066                 goto failed_nilfs;
1067 
1068         sb->s_op = &nilfs_sops;
1069         sb->s_export_op = &nilfs_export_ops;
1070         sb->s_root = NULL;
1071         sb->s_time_gran = 1;
1072         sb->s_max_links = NILFS_LINK_MAX;
1073 
1074         bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
1075         sb->s_bdi = bdi ? : &default_backing_dev_info;
1076 
1077         err = load_nilfs(nilfs, sb);
1078         if (err)
1079                 goto failed_nilfs;
1080 
1081         cno = nilfs_last_cno(nilfs);
1082         err = nilfs_attach_checkpoint(sb, cno, true, &fsroot);
1083         if (err) {
1084                 printk(KERN_ERR "NILFS: error loading last checkpoint "
1085                        "(checkpoint number=%llu).\n", (unsigned long long)cno);
1086                 goto failed_unload;
1087         }
1088 
1089         if (!(sb->s_flags & MS_RDONLY)) {
1090                 err = nilfs_attach_log_writer(sb, fsroot);
1091                 if (err)
1092                         goto failed_checkpoint;
1093         }
1094 
1095         err = nilfs_get_root_dentry(sb, fsroot, &sb->s_root);
1096         if (err)
1097                 goto failed_segctor;
1098 
1099         nilfs_put_root(fsroot);
1100 
1101         if (!(sb->s_flags & MS_RDONLY)) {
1102                 down_write(&nilfs->ns_sem);
1103                 nilfs_setup_super(sb, true);
1104                 up_write(&nilfs->ns_sem);
1105         }
1106 
1107         return 0;
1108 
1109  failed_segctor:
1110         nilfs_detach_log_writer(sb);
1111 
1112  failed_checkpoint:
1113         nilfs_put_root(fsroot);
1114 
1115  failed_unload:
1116         iput(nilfs->ns_sufile);
1117         iput(nilfs->ns_cpfile);
1118         iput(nilfs->ns_dat);
1119 
1120  failed_nilfs:
1121         destroy_nilfs(nilfs);
1122         return err;
1123 }
1124 
1125 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
1126 {
1127         struct the_nilfs *nilfs = sb->s_fs_info;
1128         unsigned long old_sb_flags;
1129         unsigned long old_mount_opt;
1130         int err;
1131 
1132         old_sb_flags = sb->s_flags;
1133         old_mount_opt = nilfs->ns_mount_opt;
1134 
1135         if (!parse_options(data, sb, 1)) {
1136                 err = -EINVAL;
1137                 goto restore_opts;
1138         }
1139         sb->s_flags = (sb->s_flags & ~MS_POSIXACL);
1140 
1141         err = -EINVAL;
1142 
1143         if (!nilfs_valid_fs(nilfs)) {
1144                 printk(KERN_WARNING "NILFS (device %s): couldn't "
1145                        "remount because the filesystem is in an "
1146                        "incomplete recovery state.\n", sb->s_id);
1147                 goto restore_opts;
1148         }
1149 
1150         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1151                 goto out;
1152         if (*flags & MS_RDONLY) {
1153                 /* Shutting down log writer */
1154                 nilfs_detach_log_writer(sb);
1155                 sb->s_flags |= MS_RDONLY;
1156 
1157                 /*
1158                  * Remounting a valid RW partition RDONLY, so set
1159                  * the RDONLY flag and then mark the partition as valid again.
1160                  */
1161                 down_write(&nilfs->ns_sem);
1162                 nilfs_cleanup_super(sb);
1163                 up_write(&nilfs->ns_sem);
1164         } else {
1165                 __u64 features;
1166                 struct nilfs_root *root;
1167 
1168                 /*
1169                  * Mounting a RDONLY partition read-write, so reread and
1170                  * store the current valid flag.  (It may have been changed
1171                  * by fsck since we originally mounted the partition.)
1172                  */
1173                 down_read(&nilfs->ns_sem);
1174                 features = le64_to_cpu(nilfs->ns_sbp[0]->s_feature_compat_ro) &
1175                         ~NILFS_FEATURE_COMPAT_RO_SUPP;
1176                 up_read(&nilfs->ns_sem);
1177                 if (features) {
1178                         printk(KERN_WARNING "NILFS (device %s): couldn't "
1179                                "remount RDWR because of unsupported optional "
1180                                "features (%llx)\n",
1181                                sb->s_id, (unsigned long long)features);
1182                         err = -EROFS;
1183                         goto restore_opts;
1184                 }
1185 
1186                 sb->s_flags &= ~MS_RDONLY;
1187 
1188                 root = NILFS_I(sb->s_root->d_inode)->i_root;
1189                 err = nilfs_attach_log_writer(sb, root);
1190                 if (err)
1191                         goto restore_opts;
1192 
1193                 down_write(&nilfs->ns_sem);
1194                 nilfs_setup_super(sb, true);
1195                 up_write(&nilfs->ns_sem);
1196         }
1197  out:
1198         return 0;
1199 
1200  restore_opts:
1201         sb->s_flags = old_sb_flags;
1202         nilfs->ns_mount_opt = old_mount_opt;
1203         return err;
1204 }
1205 
1206 struct nilfs_super_data {
1207         struct block_device *bdev;
1208         __u64 cno;
1209         int flags;
1210 };
1211 
1212 /**
1213  * nilfs_identify - pre-read mount options needed to identify mount instance
1214  * @data: mount options
1215  * @sd: nilfs_super_data
1216  */
1217 static int nilfs_identify(char *data, struct nilfs_super_data *sd)
1218 {
1219         char *p, *options = data;
1220         substring_t args[MAX_OPT_ARGS];
1221         int token;
1222         int ret = 0;
1223 
1224         do {
1225                 p = strsep(&options, ",");
1226                 if (p != NULL && *p) {
1227                         token = match_token(p, tokens, args);
1228                         if (token == Opt_snapshot) {
1229                                 if (!(sd->flags & MS_RDONLY)) {
1230                                         ret++;
1231                                 } else {
1232                                         sd->cno = simple_strtoull(args[0].from,
1233                                                                   NULL, 0);
1234                                         /*
1235                                          * No need to see the end pointer;
1236                                          * match_token() has done syntax
1237                                          * checking.
1238                                          */
1239                                         if (sd->cno == 0)
1240                                                 ret++;
1241                                 }
1242                         }
1243                         if (ret)
1244                                 printk(KERN_ERR
1245                                        "NILFS: invalid mount option: %s\n", p);
1246                 }
1247                 if (!options)
1248                         break;
1249                 BUG_ON(options == data);
1250                 *(options - 1) = ',';
1251         } while (!ret);
1252         return ret;
1253 }
1254 
1255 static int nilfs_set_bdev_super(struct super_block *s, void *data)
1256 {
1257         s->s_bdev = data;
1258         s->s_dev = s->s_bdev->bd_dev;
1259         return 0;
1260 }
1261 
1262 static int nilfs_test_bdev_super(struct super_block *s, void *data)
1263 {
1264         return (void *)s->s_bdev == data;
1265 }
1266 
1267 static struct dentry *
1268 nilfs_mount(struct file_system_type *fs_type, int flags,
1269              const char *dev_name, void *data)
1270 {
1271         struct nilfs_super_data sd;
1272         struct super_block *s;
1273         fmode_t mode = FMODE_READ | FMODE_EXCL;
1274         struct dentry *root_dentry;
1275         int err, s_new = false;
1276 
1277         if (!(flags & MS_RDONLY))
1278                 mode |= FMODE_WRITE;
1279 
1280         sd.bdev = blkdev_get_by_path(dev_name, mode, fs_type);
1281         if (IS_ERR(sd.bdev))
1282                 return ERR_CAST(sd.bdev);
1283 
1284         sd.cno = 0;
1285         sd.flags = flags;
1286         if (nilfs_identify((char *)data, &sd)) {
1287                 err = -EINVAL;
1288                 goto failed;
1289         }
1290 
1291         /*
1292          * once the super is inserted into the list by sget, s_umount
1293          * will protect the lockfs code from trying to start a snapshot
1294          * while we are mounting
1295          */
1296         mutex_lock(&sd.bdev->bd_fsfreeze_mutex);
1297         if (sd.bdev->bd_fsfreeze_count > 0) {
1298                 mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1299                 err = -EBUSY;
1300                 goto failed;
1301         }
1302         s = sget(fs_type, nilfs_test_bdev_super, nilfs_set_bdev_super, flags,
1303                  sd.bdev);
1304         mutex_unlock(&sd.bdev->bd_fsfreeze_mutex);
1305         if (IS_ERR(s)) {
1306                 err = PTR_ERR(s);
1307                 goto failed;
1308         }
1309 
1310         if (!s->s_root) {
1311                 char b[BDEVNAME_SIZE];
1312 
1313                 s_new = true;
1314 
1315                 /* New superblock instance created */
1316                 s->s_mode = mode;
1317                 strlcpy(s->s_id, bdevname(sd.bdev, b), sizeof(s->s_id));
1318                 sb_set_blocksize(s, block_size(sd.bdev));
1319 
1320                 err = nilfs_fill_super(s, data, flags & MS_SILENT ? 1 : 0);
1321                 if (err)
1322                         goto failed_super;
1323 
1324                 s->s_flags |= MS_ACTIVE;
1325         } else if (!sd.cno) {
1326                 if (nilfs_tree_is_busy(s->s_root)) {
1327                         if ((flags ^ s->s_flags) & MS_RDONLY) {
1328                                 printk(KERN_ERR "NILFS: the device already "
1329                                        "has a %s mount.\n",
1330                                        (s->s_flags & MS_RDONLY) ?
1331                                        "read-only" : "read/write");
1332                                 err = -EBUSY;
1333                                 goto failed_super;
1334                         }
1335                 } else {
1336                         /*
1337                          * Try remount to setup mount states if the current
1338                          * tree is not mounted and only snapshots use this sb.
1339                          */
1340                         err = nilfs_remount(s, &flags, data);
1341                         if (err)
1342                                 goto failed_super;
1343                 }
1344         }
1345 
1346         if (sd.cno) {
1347                 err = nilfs_attach_snapshot(s, sd.cno, &root_dentry);
1348                 if (err)
1349                         goto failed_super;
1350         } else {
1351                 root_dentry = dget(s->s_root);
1352         }
1353 
1354         if (!s_new)
1355                 blkdev_put(sd.bdev, mode);
1356 
1357         return root_dentry;
1358 
1359  failed_super:
1360         deactivate_locked_super(s);
1361 
1362  failed:
1363         if (!s_new)
1364                 blkdev_put(sd.bdev, mode);
1365         return ERR_PTR(err);
1366 }
1367 
1368 struct file_system_type nilfs_fs_type = {
1369         .owner    = THIS_MODULE,
1370         .name     = "nilfs2",
1371         .mount    = nilfs_mount,
1372         .kill_sb  = kill_block_super,
1373         .fs_flags = FS_REQUIRES_DEV,
1374 };
1375 MODULE_ALIAS_FS("nilfs2");
1376 
1377 static void nilfs_inode_init_once(void *obj)
1378 {
1379         struct nilfs_inode_info *ii = obj;
1380 
1381         INIT_LIST_HEAD(&ii->i_dirty);
1382 #ifdef CONFIG_NILFS_XATTR
1383         init_rwsem(&ii->xattr_sem);
1384 #endif
1385         address_space_init_once(&ii->i_btnode_cache);
1386         ii->i_bmap = &ii->i_bmap_data;
1387         inode_init_once(&ii->vfs_inode);
1388 }
1389 
1390 static void nilfs_segbuf_init_once(void *obj)
1391 {
1392         memset(obj, 0, sizeof(struct nilfs_segment_buffer));
1393 }
1394 
1395 static void nilfs_destroy_cachep(void)
1396 {
1397         /*
1398          * Make sure all delayed rcu free inodes are flushed before we
1399          * destroy cache.
1400          */
1401         rcu_barrier();
1402 
1403         if (nilfs_inode_cachep)
1404                 kmem_cache_destroy(nilfs_inode_cachep);
1405         if (nilfs_transaction_cachep)
1406                 kmem_cache_destroy(nilfs_transaction_cachep);
1407         if (nilfs_segbuf_cachep)
1408                 kmem_cache_destroy(nilfs_segbuf_cachep);
1409         if (nilfs_btree_path_cache)
1410                 kmem_cache_destroy(nilfs_btree_path_cache);
1411 }
1412 
1413 static int __init nilfs_init_cachep(void)
1414 {
1415         nilfs_inode_cachep = kmem_cache_create("nilfs2_inode_cache",
1416                         sizeof(struct nilfs_inode_info), 0,
1417                         SLAB_RECLAIM_ACCOUNT, nilfs_inode_init_once);
1418         if (!nilfs_inode_cachep)
1419                 goto fail;
1420 
1421         nilfs_transaction_cachep = kmem_cache_create("nilfs2_transaction_cache",
1422                         sizeof(struct nilfs_transaction_info), 0,
1423                         SLAB_RECLAIM_ACCOUNT, NULL);
1424         if (!nilfs_transaction_cachep)
1425                 goto fail;
1426 
1427         nilfs_segbuf_cachep = kmem_cache_create("nilfs2_segbuf_cache",
1428                         sizeof(struct nilfs_segment_buffer), 0,
1429                         SLAB_RECLAIM_ACCOUNT, nilfs_segbuf_init_once);
1430         if (!nilfs_segbuf_cachep)
1431                 goto fail;
1432 
1433         nilfs_btree_path_cache = kmem_cache_create("nilfs2_btree_path_cache",
1434                         sizeof(struct nilfs_btree_path) * NILFS_BTREE_LEVEL_MAX,
1435                         0, 0, NULL);
1436         if (!nilfs_btree_path_cache)
1437                 goto fail;
1438 
1439         return 0;
1440 
1441 fail:
1442         nilfs_destroy_cachep();
1443         return -ENOMEM;
1444 }
1445 
1446 static int __init init_nilfs_fs(void)
1447 {
1448         int err;
1449 
1450         err = nilfs_init_cachep();
1451         if (err)
1452                 goto fail;
1453 
1454         err = register_filesystem(&nilfs_fs_type);
1455         if (err)
1456                 goto free_cachep;
1457 
1458         printk(KERN_INFO "NILFS version 2 loaded\n");
1459         return 0;
1460 
1461 free_cachep:
1462         nilfs_destroy_cachep();
1463 fail:
1464         return err;
1465 }
1466 
1467 static void __exit exit_nilfs_fs(void)
1468 {
1469         nilfs_destroy_cachep();
1470         unregister_filesystem(&nilfs_fs_type);
1471 }
1472 
1473 module_init(init_nilfs_fs)
1474 module_exit(exit_nilfs_fs)
1475 

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