Btrfs: create special free space cache inode
[linux-3.10.git] / fs / btrfs / super.c
1 /*
2  * Copyright (C) 2007 Oracle.  All rights reserved.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public
6  * License v2 as published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public
14  * License along with this program; if not, write to the
15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16  * Boston, MA 021110-1307, USA.
17  */
18
19 #include <linux/blkdev.h>
20 #include <linux/module.h>
21 #include <linux/buffer_head.h>
22 #include <linux/fs.h>
23 #include <linux/pagemap.h>
24 #include <linux/highmem.h>
25 #include <linux/time.h>
26 #include <linux/init.h>
27 #include <linux/seq_file.h>
28 #include <linux/string.h>
29 #include <linux/backing-dev.h>
30 #include <linux/mount.h>
31 #include <linux/mpage.h>
32 #include <linux/swap.h>
33 #include <linux/writeback.h>
34 #include <linux/statfs.h>
35 #include <linux/compat.h>
36 #include <linux/parser.h>
37 #include <linux/ctype.h>
38 #include <linux/namei.h>
39 #include <linux/miscdevice.h>
40 #include <linux/magic.h>
41 #include <linux/slab.h>
42 #include "compat.h"
43 #include "ctree.h"
44 #include "disk-io.h"
45 #include "transaction.h"
46 #include "btrfs_inode.h"
47 #include "ioctl.h"
48 #include "print-tree.h"
49 #include "xattr.h"
50 #include "volumes.h"
51 #include "version.h"
52 #include "export.h"
53 #include "compression.h"
54
55 static const struct super_operations btrfs_super_ops;
56
57 static void btrfs_put_super(struct super_block *sb)
58 {
59         struct btrfs_root *root = btrfs_sb(sb);
60         int ret;
61
62         ret = close_ctree(root);
63         sb->s_fs_info = NULL;
64 }
65
66 enum {
67         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
68         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
69         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
70         Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
71         Opt_discard, Opt_space_cache, Opt_err,
72 };
73
74 static match_table_t tokens = {
75         {Opt_degraded, "degraded"},
76         {Opt_subvol, "subvol=%s"},
77         {Opt_subvolid, "subvolid=%d"},
78         {Opt_device, "device=%s"},
79         {Opt_nodatasum, "nodatasum"},
80         {Opt_nodatacow, "nodatacow"},
81         {Opt_nobarrier, "nobarrier"},
82         {Opt_max_inline, "max_inline=%s"},
83         {Opt_alloc_start, "alloc_start=%s"},
84         {Opt_thread_pool, "thread_pool=%d"},
85         {Opt_compress, "compress"},
86         {Opt_compress_force, "compress-force"},
87         {Opt_ssd, "ssd"},
88         {Opt_ssd_spread, "ssd_spread"},
89         {Opt_nossd, "nossd"},
90         {Opt_noacl, "noacl"},
91         {Opt_notreelog, "notreelog"},
92         {Opt_flushoncommit, "flushoncommit"},
93         {Opt_ratio, "metadata_ratio=%d"},
94         {Opt_discard, "discard"},
95         {Opt_space_cache, "space_cache"},
96         {Opt_err, NULL},
97 };
98
99 /*
100  * Regular mount options parser.  Everything that is needed only when
101  * reading in a new superblock is parsed here.
102  */
103 int btrfs_parse_options(struct btrfs_root *root, char *options)
104 {
105         struct btrfs_fs_info *info = root->fs_info;
106         substring_t args[MAX_OPT_ARGS];
107         char *p, *num, *orig;
108         int intarg;
109         int ret = 0;
110
111         if (!options)
112                 return 0;
113
114         /*
115          * strsep changes the string, duplicate it because parse_options
116          * gets called twice
117          */
118         options = kstrdup(options, GFP_NOFS);
119         if (!options)
120                 return -ENOMEM;
121
122         orig = options;
123
124         while ((p = strsep(&options, ",")) != NULL) {
125                 int token;
126                 if (!*p)
127                         continue;
128
129                 token = match_token(p, tokens, args);
130                 switch (token) {
131                 case Opt_degraded:
132                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
133                         btrfs_set_opt(info->mount_opt, DEGRADED);
134                         break;
135                 case Opt_subvol:
136                 case Opt_subvolid:
137                 case Opt_device:
138                         /*
139                          * These are parsed by btrfs_parse_early_options
140                          * and can be happily ignored here.
141                          */
142                         break;
143                 case Opt_nodatasum:
144                         printk(KERN_INFO "btrfs: setting nodatasum\n");
145                         btrfs_set_opt(info->mount_opt, NODATASUM);
146                         break;
147                 case Opt_nodatacow:
148                         printk(KERN_INFO "btrfs: setting nodatacow\n");
149                         btrfs_set_opt(info->mount_opt, NODATACOW);
150                         btrfs_set_opt(info->mount_opt, NODATASUM);
151                         break;
152                 case Opt_compress:
153                         printk(KERN_INFO "btrfs: use compression\n");
154                         btrfs_set_opt(info->mount_opt, COMPRESS);
155                         break;
156                 case Opt_compress_force:
157                         printk(KERN_INFO "btrfs: forcing compression\n");
158                         btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
159                         btrfs_set_opt(info->mount_opt, COMPRESS);
160                         break;
161                 case Opt_ssd:
162                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
163                         btrfs_set_opt(info->mount_opt, SSD);
164                         break;
165                 case Opt_ssd_spread:
166                         printk(KERN_INFO "btrfs: use spread ssd "
167                                "allocation scheme\n");
168                         btrfs_set_opt(info->mount_opt, SSD);
169                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
170                         break;
171                 case Opt_nossd:
172                         printk(KERN_INFO "btrfs: not using ssd allocation "
173                                "scheme\n");
174                         btrfs_set_opt(info->mount_opt, NOSSD);
175                         btrfs_clear_opt(info->mount_opt, SSD);
176                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
177                         break;
178                 case Opt_nobarrier:
179                         printk(KERN_INFO "btrfs: turning off barriers\n");
180                         btrfs_set_opt(info->mount_opt, NOBARRIER);
181                         break;
182                 case Opt_thread_pool:
183                         intarg = 0;
184                         match_int(&args[0], &intarg);
185                         if (intarg) {
186                                 info->thread_pool_size = intarg;
187                                 printk(KERN_INFO "btrfs: thread pool %d\n",
188                                        info->thread_pool_size);
189                         }
190                         break;
191                 case Opt_max_inline:
192                         num = match_strdup(&args[0]);
193                         if (num) {
194                                 info->max_inline = memparse(num, NULL);
195                                 kfree(num);
196
197                                 if (info->max_inline) {
198                                         info->max_inline = max_t(u64,
199                                                 info->max_inline,
200                                                 root->sectorsize);
201                                 }
202                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
203                                         (unsigned long long)info->max_inline);
204                         }
205                         break;
206                 case Opt_alloc_start:
207                         num = match_strdup(&args[0]);
208                         if (num) {
209                                 info->alloc_start = memparse(num, NULL);
210                                 kfree(num);
211                                 printk(KERN_INFO
212                                         "btrfs: allocations start at %llu\n",
213                                         (unsigned long long)info->alloc_start);
214                         }
215                         break;
216                 case Opt_noacl:
217                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
218                         break;
219                 case Opt_notreelog:
220                         printk(KERN_INFO "btrfs: disabling tree log\n");
221                         btrfs_set_opt(info->mount_opt, NOTREELOG);
222                         break;
223                 case Opt_flushoncommit:
224                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
225                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
226                         break;
227                 case Opt_ratio:
228                         intarg = 0;
229                         match_int(&args[0], &intarg);
230                         if (intarg) {
231                                 info->metadata_ratio = intarg;
232                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
233                                        info->metadata_ratio);
234                         }
235                         break;
236                 case Opt_discard:
237                         btrfs_set_opt(info->mount_opt, DISCARD);
238                         break;
239                 case Opt_space_cache:
240                         printk(KERN_INFO "btrfs: enabling disk space caching\n");
241                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
242                         break;
243                 case Opt_err:
244                         printk(KERN_INFO "btrfs: unrecognized mount option "
245                                "'%s'\n", p);
246                         ret = -EINVAL;
247                         goto out;
248                 default:
249                         break;
250                 }
251         }
252 out:
253         kfree(orig);
254         return ret;
255 }
256
257 /*
258  * Parse mount options that are required early in the mount process.
259  *
260  * All other options will be parsed on much later in the mount process and
261  * only when we need to allocate a new super block.
262  */
263 static int btrfs_parse_early_options(const char *options, fmode_t flags,
264                 void *holder, char **subvol_name, u64 *subvol_objectid,
265                 struct btrfs_fs_devices **fs_devices)
266 {
267         substring_t args[MAX_OPT_ARGS];
268         char *opts, *p;
269         int error = 0;
270         int intarg;
271
272         if (!options)
273                 goto out;
274
275         /*
276          * strsep changes the string, duplicate it because parse_options
277          * gets called twice
278          */
279         opts = kstrdup(options, GFP_KERNEL);
280         if (!opts)
281                 return -ENOMEM;
282
283         while ((p = strsep(&opts, ",")) != NULL) {
284                 int token;
285                 if (!*p)
286                         continue;
287
288                 token = match_token(p, tokens, args);
289                 switch (token) {
290                 case Opt_subvol:
291                         *subvol_name = match_strdup(&args[0]);
292                         break;
293                 case Opt_subvolid:
294                         intarg = 0;
295                         error = match_int(&args[0], &intarg);
296                         if (!error) {
297                                 /* we want the original fs_tree */
298                                 if (!intarg)
299                                         *subvol_objectid =
300                                                 BTRFS_FS_TREE_OBJECTID;
301                                 else
302                                         *subvol_objectid = intarg;
303                         }
304                         break;
305                 case Opt_device:
306                         error = btrfs_scan_one_device(match_strdup(&args[0]),
307                                         flags, holder, fs_devices);
308                         if (error)
309                                 goto out_free_opts;
310                         break;
311                 default:
312                         break;
313                 }
314         }
315
316  out_free_opts:
317         kfree(opts);
318  out:
319         /*
320          * If no subvolume name is specified we use the default one.  Allocate
321          * a copy of the string "." here so that code later in the
322          * mount path doesn't care if it's the default volume or another one.
323          */
324         if (!*subvol_name) {
325                 *subvol_name = kstrdup(".", GFP_KERNEL);
326                 if (!*subvol_name)
327                         return -ENOMEM;
328         }
329         return error;
330 }
331
332 static struct dentry *get_default_root(struct super_block *sb,
333                                        u64 subvol_objectid)
334 {
335         struct btrfs_root *root = sb->s_fs_info;
336         struct btrfs_root *new_root;
337         struct btrfs_dir_item *di;
338         struct btrfs_path *path;
339         struct btrfs_key location;
340         struct inode *inode;
341         struct dentry *dentry;
342         u64 dir_id;
343         int new = 0;
344
345         /*
346          * We have a specific subvol we want to mount, just setup location and
347          * go look up the root.
348          */
349         if (subvol_objectid) {
350                 location.objectid = subvol_objectid;
351                 location.type = BTRFS_ROOT_ITEM_KEY;
352                 location.offset = (u64)-1;
353                 goto find_root;
354         }
355
356         path = btrfs_alloc_path();
357         if (!path)
358                 return ERR_PTR(-ENOMEM);
359         path->leave_spinning = 1;
360
361         /*
362          * Find the "default" dir item which points to the root item that we
363          * will mount by default if we haven't been given a specific subvolume
364          * to mount.
365          */
366         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
367         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
368         if (IS_ERR(di))
369                 return ERR_CAST(di);
370         if (!di) {
371                 /*
372                  * Ok the default dir item isn't there.  This is weird since
373                  * it's always been there, but don't freak out, just try and
374                  * mount to root most subvolume.
375                  */
376                 btrfs_free_path(path);
377                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
378                 new_root = root->fs_info->fs_root;
379                 goto setup_root;
380         }
381
382         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
383         btrfs_free_path(path);
384
385 find_root:
386         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
387         if (IS_ERR(new_root))
388                 return ERR_PTR(PTR_ERR(new_root));
389
390         if (btrfs_root_refs(&new_root->root_item) == 0)
391                 return ERR_PTR(-ENOENT);
392
393         dir_id = btrfs_root_dirid(&new_root->root_item);
394 setup_root:
395         location.objectid = dir_id;
396         location.type = BTRFS_INODE_ITEM_KEY;
397         location.offset = 0;
398
399         inode = btrfs_iget(sb, &location, new_root, &new);
400         if (IS_ERR(inode))
401                 return ERR_CAST(inode);
402
403         /*
404          * If we're just mounting the root most subvol put the inode and return
405          * a reference to the dentry.  We will have already gotten a reference
406          * to the inode in btrfs_fill_super so we're good to go.
407          */
408         if (!new && sb->s_root->d_inode == inode) {
409                 iput(inode);
410                 return dget(sb->s_root);
411         }
412
413         if (new) {
414                 const struct qstr name = { .name = "/", .len = 1 };
415
416                 /*
417                  * New inode, we need to make the dentry a sibling of s_root so
418                  * everything gets cleaned up properly on unmount.
419                  */
420                 dentry = d_alloc(sb->s_root, &name);
421                 if (!dentry) {
422                         iput(inode);
423                         return ERR_PTR(-ENOMEM);
424                 }
425                 d_splice_alias(inode, dentry);
426         } else {
427                 /*
428                  * We found the inode in cache, just find a dentry for it and
429                  * put the reference to the inode we just got.
430                  */
431                 dentry = d_find_alias(inode);
432                 iput(inode);
433         }
434
435         return dentry;
436 }
437
438 static int btrfs_fill_super(struct super_block *sb,
439                             struct btrfs_fs_devices *fs_devices,
440                             void *data, int silent)
441 {
442         struct inode *inode;
443         struct dentry *root_dentry;
444         struct btrfs_super_block *disk_super;
445         struct btrfs_root *tree_root;
446         struct btrfs_key key;
447         int err;
448
449         sb->s_maxbytes = MAX_LFS_FILESIZE;
450         sb->s_magic = BTRFS_SUPER_MAGIC;
451         sb->s_op = &btrfs_super_ops;
452         sb->s_export_op = &btrfs_export_ops;
453         sb->s_xattr = btrfs_xattr_handlers;
454         sb->s_time_gran = 1;
455 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
456         sb->s_flags |= MS_POSIXACL;
457 #endif
458
459         tree_root = open_ctree(sb, fs_devices, (char *)data);
460
461         if (IS_ERR(tree_root)) {
462                 printk("btrfs: open_ctree failed\n");
463                 return PTR_ERR(tree_root);
464         }
465         sb->s_fs_info = tree_root;
466         disk_super = &tree_root->fs_info->super_copy;
467
468         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
469         key.type = BTRFS_INODE_ITEM_KEY;
470         key.offset = 0;
471         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
472         if (IS_ERR(inode)) {
473                 err = PTR_ERR(inode);
474                 goto fail_close;
475         }
476
477         root_dentry = d_alloc_root(inode);
478         if (!root_dentry) {
479                 iput(inode);
480                 err = -ENOMEM;
481                 goto fail_close;
482         }
483
484         sb->s_root = root_dentry;
485
486         save_mount_options(sb, data);
487         return 0;
488
489 fail_close:
490         close_ctree(tree_root);
491         return err;
492 }
493
494 int btrfs_sync_fs(struct super_block *sb, int wait)
495 {
496         struct btrfs_trans_handle *trans;
497         struct btrfs_root *root = btrfs_sb(sb);
498         int ret;
499
500         if (!wait) {
501                 filemap_flush(root->fs_info->btree_inode->i_mapping);
502                 return 0;
503         }
504
505         btrfs_start_delalloc_inodes(root, 0);
506         btrfs_wait_ordered_extents(root, 0, 0);
507
508         trans = btrfs_start_transaction(root, 0);
509         ret = btrfs_commit_transaction(trans, root);
510         return ret;
511 }
512
513 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
514 {
515         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
516         struct btrfs_fs_info *info = root->fs_info;
517
518         if (btrfs_test_opt(root, DEGRADED))
519                 seq_puts(seq, ",degraded");
520         if (btrfs_test_opt(root, NODATASUM))
521                 seq_puts(seq, ",nodatasum");
522         if (btrfs_test_opt(root, NODATACOW))
523                 seq_puts(seq, ",nodatacow");
524         if (btrfs_test_opt(root, NOBARRIER))
525                 seq_puts(seq, ",nobarrier");
526         if (info->max_inline != 8192 * 1024)
527                 seq_printf(seq, ",max_inline=%llu",
528                            (unsigned long long)info->max_inline);
529         if (info->alloc_start != 0)
530                 seq_printf(seq, ",alloc_start=%llu",
531                            (unsigned long long)info->alloc_start);
532         if (info->thread_pool_size !=  min_t(unsigned long,
533                                              num_online_cpus() + 2, 8))
534                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
535         if (btrfs_test_opt(root, COMPRESS))
536                 seq_puts(seq, ",compress");
537         if (btrfs_test_opt(root, NOSSD))
538                 seq_puts(seq, ",nossd");
539         if (btrfs_test_opt(root, SSD_SPREAD))
540                 seq_puts(seq, ",ssd_spread");
541         else if (btrfs_test_opt(root, SSD))
542                 seq_puts(seq, ",ssd");
543         if (btrfs_test_opt(root, NOTREELOG))
544                 seq_puts(seq, ",notreelog");
545         if (btrfs_test_opt(root, FLUSHONCOMMIT))
546                 seq_puts(seq, ",flushoncommit");
547         if (btrfs_test_opt(root, DISCARD))
548                 seq_puts(seq, ",discard");
549         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
550                 seq_puts(seq, ",noacl");
551         return 0;
552 }
553
554 static int btrfs_test_super(struct super_block *s, void *data)
555 {
556         struct btrfs_fs_devices *test_fs_devices = data;
557         struct btrfs_root *root = btrfs_sb(s);
558
559         return root->fs_info->fs_devices == test_fs_devices;
560 }
561
562 /*
563  * Find a superblock for the given device / mount point.
564  *
565  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
566  *        for multiple device setup.  Make sure to keep it in sync.
567  */
568 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
569                 const char *dev_name, void *data, struct vfsmount *mnt)
570 {
571         struct block_device *bdev = NULL;
572         struct super_block *s;
573         struct dentry *root;
574         struct btrfs_fs_devices *fs_devices = NULL;
575         fmode_t mode = FMODE_READ;
576         char *subvol_name = NULL;
577         u64 subvol_objectid = 0;
578         int error = 0;
579         int found = 0;
580
581         if (!(flags & MS_RDONLY))
582                 mode |= FMODE_WRITE;
583
584         error = btrfs_parse_early_options(data, mode, fs_type,
585                                           &subvol_name, &subvol_objectid,
586                                           &fs_devices);
587         if (error)
588                 return error;
589
590         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
591         if (error)
592                 goto error_free_subvol_name;
593
594         error = btrfs_open_devices(fs_devices, mode, fs_type);
595         if (error)
596                 goto error_free_subvol_name;
597
598         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
599                 error = -EACCES;
600                 goto error_close_devices;
601         }
602
603         bdev = fs_devices->latest_bdev;
604         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
605         if (IS_ERR(s))
606                 goto error_s;
607
608         if (s->s_root) {
609                 if ((flags ^ s->s_flags) & MS_RDONLY) {
610                         deactivate_locked_super(s);
611                         error = -EBUSY;
612                         goto error_close_devices;
613                 }
614
615                 found = 1;
616                 btrfs_close_devices(fs_devices);
617         } else {
618                 char b[BDEVNAME_SIZE];
619
620                 s->s_flags = flags;
621                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
622                 error = btrfs_fill_super(s, fs_devices, data,
623                                          flags & MS_SILENT ? 1 : 0);
624                 if (error) {
625                         deactivate_locked_super(s);
626                         goto error_free_subvol_name;
627                 }
628
629                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
630                 s->s_flags |= MS_ACTIVE;
631         }
632
633         root = get_default_root(s, subvol_objectid);
634         if (IS_ERR(root)) {
635                 error = PTR_ERR(root);
636                 deactivate_locked_super(s);
637                 goto error;
638         }
639         /* if they gave us a subvolume name bind mount into that */
640         if (strcmp(subvol_name, ".")) {
641                 struct dentry *new_root;
642                 mutex_lock(&root->d_inode->i_mutex);
643                 new_root = lookup_one_len(subvol_name, root,
644                                       strlen(subvol_name));
645                 mutex_unlock(&root->d_inode->i_mutex);
646
647                 if (IS_ERR(new_root)) {
648                         deactivate_locked_super(s);
649                         error = PTR_ERR(new_root);
650                         dput(root);
651                         goto error_close_devices;
652                 }
653                 if (!new_root->d_inode) {
654                         dput(root);
655                         dput(new_root);
656                         deactivate_locked_super(s);
657                         error = -ENXIO;
658                         goto error_close_devices;
659                 }
660                 dput(root);
661                 root = new_root;
662         }
663
664         mnt->mnt_sb = s;
665         mnt->mnt_root = root;
666
667         kfree(subvol_name);
668         return 0;
669
670 error_s:
671         error = PTR_ERR(s);
672 error_close_devices:
673         btrfs_close_devices(fs_devices);
674 error_free_subvol_name:
675         kfree(subvol_name);
676 error:
677         return error;
678 }
679
680 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
681 {
682         struct btrfs_root *root = btrfs_sb(sb);
683         int ret;
684
685         ret = btrfs_parse_options(root, data);
686         if (ret)
687                 return -EINVAL;
688
689         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
690                 return 0;
691
692         if (*flags & MS_RDONLY) {
693                 sb->s_flags |= MS_RDONLY;
694
695                 ret =  btrfs_commit_super(root);
696                 WARN_ON(ret);
697         } else {
698                 if (root->fs_info->fs_devices->rw_devices == 0)
699                         return -EACCES;
700
701                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
702                         return -EINVAL;
703
704                 ret = btrfs_cleanup_fs_roots(root->fs_info);
705                 WARN_ON(ret);
706
707                 /* recover relocation */
708                 ret = btrfs_recover_relocation(root);
709                 WARN_ON(ret);
710
711                 sb->s_flags &= ~MS_RDONLY;
712         }
713
714         return 0;
715 }
716
717 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
718 {
719         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
720         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
721         struct list_head *head = &root->fs_info->space_info;
722         struct btrfs_space_info *found;
723         u64 total_used = 0;
724         int bits = dentry->d_sb->s_blocksize_bits;
725         __be32 *fsid = (__be32 *)root->fs_info->fsid;
726
727         rcu_read_lock();
728         list_for_each_entry_rcu(found, head, list)
729                 total_used += found->disk_used;
730         rcu_read_unlock();
731
732         buf->f_namelen = BTRFS_NAME_LEN;
733         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
734         buf->f_bfree = buf->f_blocks - (total_used >> bits);
735         buf->f_bavail = buf->f_bfree;
736         buf->f_bsize = dentry->d_sb->s_blocksize;
737         buf->f_type = BTRFS_SUPER_MAGIC;
738
739         /* We treat it as constant endianness (it doesn't matter _which_)
740            because we want the fsid to come out the same whether mounted
741            on a big-endian or little-endian host */
742         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
743         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
744         /* Mask in the root object ID too, to disambiguate subvols */
745         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
746         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
747
748         return 0;
749 }
750
751 static struct file_system_type btrfs_fs_type = {
752         .owner          = THIS_MODULE,
753         .name           = "btrfs",
754         .get_sb         = btrfs_get_sb,
755         .kill_sb        = kill_anon_super,
756         .fs_flags       = FS_REQUIRES_DEV,
757 };
758
759 /*
760  * used by btrfsctl to scan devices when no FS is mounted
761  */
762 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
763                                 unsigned long arg)
764 {
765         struct btrfs_ioctl_vol_args *vol;
766         struct btrfs_fs_devices *fs_devices;
767         int ret = -ENOTTY;
768
769         if (!capable(CAP_SYS_ADMIN))
770                 return -EPERM;
771
772         vol = memdup_user((void __user *)arg, sizeof(*vol));
773         if (IS_ERR(vol))
774                 return PTR_ERR(vol);
775
776         switch (cmd) {
777         case BTRFS_IOC_SCAN_DEV:
778                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
779                                             &btrfs_fs_type, &fs_devices);
780                 break;
781         }
782
783         kfree(vol);
784         return ret;
785 }
786
787 static int btrfs_freeze(struct super_block *sb)
788 {
789         struct btrfs_root *root = btrfs_sb(sb);
790         mutex_lock(&root->fs_info->transaction_kthread_mutex);
791         mutex_lock(&root->fs_info->cleaner_mutex);
792         return 0;
793 }
794
795 static int btrfs_unfreeze(struct super_block *sb)
796 {
797         struct btrfs_root *root = btrfs_sb(sb);
798         mutex_unlock(&root->fs_info->cleaner_mutex);
799         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
800         return 0;
801 }
802
803 static const struct super_operations btrfs_super_ops = {
804         .drop_inode     = btrfs_drop_inode,
805         .evict_inode    = btrfs_evict_inode,
806         .put_super      = btrfs_put_super,
807         .sync_fs        = btrfs_sync_fs,
808         .show_options   = btrfs_show_options,
809         .write_inode    = btrfs_write_inode,
810         .dirty_inode    = btrfs_dirty_inode,
811         .alloc_inode    = btrfs_alloc_inode,
812         .destroy_inode  = btrfs_destroy_inode,
813         .statfs         = btrfs_statfs,
814         .remount_fs     = btrfs_remount,
815         .freeze_fs      = btrfs_freeze,
816         .unfreeze_fs    = btrfs_unfreeze,
817 };
818
819 static const struct file_operations btrfs_ctl_fops = {
820         .unlocked_ioctl  = btrfs_control_ioctl,
821         .compat_ioctl = btrfs_control_ioctl,
822         .owner   = THIS_MODULE,
823 };
824
825 static struct miscdevice btrfs_misc = {
826         .minor          = BTRFS_MINOR,
827         .name           = "btrfs-control",
828         .fops           = &btrfs_ctl_fops
829 };
830
831 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
832 MODULE_ALIAS("devname:btrfs-control");
833
834 static int btrfs_interface_init(void)
835 {
836         return misc_register(&btrfs_misc);
837 }
838
839 static void btrfs_interface_exit(void)
840 {
841         if (misc_deregister(&btrfs_misc) < 0)
842                 printk(KERN_INFO "misc_deregister failed for control device");
843 }
844
845 static int __init init_btrfs_fs(void)
846 {
847         int err;
848
849         err = btrfs_init_sysfs();
850         if (err)
851                 return err;
852
853         err = btrfs_init_cachep();
854         if (err)
855                 goto free_sysfs;
856
857         err = extent_io_init();
858         if (err)
859                 goto free_cachep;
860
861         err = extent_map_init();
862         if (err)
863                 goto free_extent_io;
864
865         err = btrfs_interface_init();
866         if (err)
867                 goto free_extent_map;
868
869         err = register_filesystem(&btrfs_fs_type);
870         if (err)
871                 goto unregister_ioctl;
872
873         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
874         return 0;
875
876 unregister_ioctl:
877         btrfs_interface_exit();
878 free_extent_map:
879         extent_map_exit();
880 free_extent_io:
881         extent_io_exit();
882 free_cachep:
883         btrfs_destroy_cachep();
884 free_sysfs:
885         btrfs_exit_sysfs();
886         return err;
887 }
888
889 static void __exit exit_btrfs_fs(void)
890 {
891         btrfs_destroy_cachep();
892         extent_map_exit();
893         extent_io_exit();
894         btrfs_interface_exit();
895         unregister_filesystem(&btrfs_fs_type);
896         btrfs_exit_sysfs();
897         btrfs_cleanup_fs_uuids();
898         btrfs_zlib_exit();
899 }
900
901 module_init(init_btrfs_fs)
902 module_exit(exit_btrfs_fs)
903
904 MODULE_LICENSE("GPL");