Merge branch 'bug-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/josef/btrfs...
[~shefty/rdma-dev.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_clear_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_clear_cache, "clear_cache"},
97         {Opt_err, NULL},
98 };
99
100 /*
101  * Regular mount options parser.  Everything that is needed only when
102  * reading in a new superblock is parsed here.
103  */
104 int btrfs_parse_options(struct btrfs_root *root, char *options)
105 {
106         struct btrfs_fs_info *info = root->fs_info;
107         substring_t args[MAX_OPT_ARGS];
108         char *p, *num, *orig;
109         int intarg;
110         int ret = 0;
111
112         if (!options)
113                 return 0;
114
115         /*
116          * strsep changes the string, duplicate it because parse_options
117          * gets called twice
118          */
119         options = kstrdup(options, GFP_NOFS);
120         if (!options)
121                 return -ENOMEM;
122
123         orig = options;
124
125         while ((p = strsep(&options, ",")) != NULL) {
126                 int token;
127                 if (!*p)
128                         continue;
129
130                 token = match_token(p, tokens, args);
131                 switch (token) {
132                 case Opt_degraded:
133                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
134                         btrfs_set_opt(info->mount_opt, DEGRADED);
135                         break;
136                 case Opt_subvol:
137                 case Opt_subvolid:
138                 case Opt_device:
139                         /*
140                          * These are parsed by btrfs_parse_early_options
141                          * and can be happily ignored here.
142                          */
143                         break;
144                 case Opt_nodatasum:
145                         printk(KERN_INFO "btrfs: setting nodatasum\n");
146                         btrfs_set_opt(info->mount_opt, NODATASUM);
147                         break;
148                 case Opt_nodatacow:
149                         printk(KERN_INFO "btrfs: setting nodatacow\n");
150                         btrfs_set_opt(info->mount_opt, NODATACOW);
151                         btrfs_set_opt(info->mount_opt, NODATASUM);
152                         break;
153                 case Opt_compress:
154                         printk(KERN_INFO "btrfs: use compression\n");
155                         btrfs_set_opt(info->mount_opt, COMPRESS);
156                         break;
157                 case Opt_compress_force:
158                         printk(KERN_INFO "btrfs: forcing compression\n");
159                         btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
160                         btrfs_set_opt(info->mount_opt, COMPRESS);
161                         break;
162                 case Opt_ssd:
163                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
164                         btrfs_set_opt(info->mount_opt, SSD);
165                         break;
166                 case Opt_ssd_spread:
167                         printk(KERN_INFO "btrfs: use spread ssd "
168                                "allocation scheme\n");
169                         btrfs_set_opt(info->mount_opt, SSD);
170                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
171                         break;
172                 case Opt_nossd:
173                         printk(KERN_INFO "btrfs: not using ssd allocation "
174                                "scheme\n");
175                         btrfs_set_opt(info->mount_opt, NOSSD);
176                         btrfs_clear_opt(info->mount_opt, SSD);
177                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
178                         break;
179                 case Opt_nobarrier:
180                         printk(KERN_INFO "btrfs: turning off barriers\n");
181                         btrfs_set_opt(info->mount_opt, NOBARRIER);
182                         break;
183                 case Opt_thread_pool:
184                         intarg = 0;
185                         match_int(&args[0], &intarg);
186                         if (intarg) {
187                                 info->thread_pool_size = intarg;
188                                 printk(KERN_INFO "btrfs: thread pool %d\n",
189                                        info->thread_pool_size);
190                         }
191                         break;
192                 case Opt_max_inline:
193                         num = match_strdup(&args[0]);
194                         if (num) {
195                                 info->max_inline = memparse(num, NULL);
196                                 kfree(num);
197
198                                 if (info->max_inline) {
199                                         info->max_inline = max_t(u64,
200                                                 info->max_inline,
201                                                 root->sectorsize);
202                                 }
203                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
204                                         (unsigned long long)info->max_inline);
205                         }
206                         break;
207                 case Opt_alloc_start:
208                         num = match_strdup(&args[0]);
209                         if (num) {
210                                 info->alloc_start = memparse(num, NULL);
211                                 kfree(num);
212                                 printk(KERN_INFO
213                                         "btrfs: allocations start at %llu\n",
214                                         (unsigned long long)info->alloc_start);
215                         }
216                         break;
217                 case Opt_noacl:
218                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
219                         break;
220                 case Opt_notreelog:
221                         printk(KERN_INFO "btrfs: disabling tree log\n");
222                         btrfs_set_opt(info->mount_opt, NOTREELOG);
223                         break;
224                 case Opt_flushoncommit:
225                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
226                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
227                         break;
228                 case Opt_ratio:
229                         intarg = 0;
230                         match_int(&args[0], &intarg);
231                         if (intarg) {
232                                 info->metadata_ratio = intarg;
233                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
234                                        info->metadata_ratio);
235                         }
236                         break;
237                 case Opt_discard:
238                         btrfs_set_opt(info->mount_opt, DISCARD);
239                         break;
240                 case Opt_space_cache:
241                         printk(KERN_INFO "btrfs: enabling disk space caching\n");
242                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
243                 case Opt_clear_cache:
244                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
245                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
246                         break;
247                 case Opt_err:
248                         printk(KERN_INFO "btrfs: unrecognized mount option "
249                                "'%s'\n", p);
250                         ret = -EINVAL;
251                         goto out;
252                 default:
253                         break;
254                 }
255         }
256 out:
257         kfree(orig);
258         return ret;
259 }
260
261 /*
262  * Parse mount options that are required early in the mount process.
263  *
264  * All other options will be parsed on much later in the mount process and
265  * only when we need to allocate a new super block.
266  */
267 static int btrfs_parse_early_options(const char *options, fmode_t flags,
268                 void *holder, char **subvol_name, u64 *subvol_objectid,
269                 struct btrfs_fs_devices **fs_devices)
270 {
271         substring_t args[MAX_OPT_ARGS];
272         char *opts, *p;
273         int error = 0;
274         int intarg;
275
276         if (!options)
277                 goto out;
278
279         /*
280          * strsep changes the string, duplicate it because parse_options
281          * gets called twice
282          */
283         opts = kstrdup(options, GFP_KERNEL);
284         if (!opts)
285                 return -ENOMEM;
286
287         while ((p = strsep(&opts, ",")) != NULL) {
288                 int token;
289                 if (!*p)
290                         continue;
291
292                 token = match_token(p, tokens, args);
293                 switch (token) {
294                 case Opt_subvol:
295                         *subvol_name = match_strdup(&args[0]);
296                         break;
297                 case Opt_subvolid:
298                         intarg = 0;
299                         error = match_int(&args[0], &intarg);
300                         if (!error) {
301                                 /* we want the original fs_tree */
302                                 if (!intarg)
303                                         *subvol_objectid =
304                                                 BTRFS_FS_TREE_OBJECTID;
305                                 else
306                                         *subvol_objectid = intarg;
307                         }
308                         break;
309                 case Opt_device:
310                         error = btrfs_scan_one_device(match_strdup(&args[0]),
311                                         flags, holder, fs_devices);
312                         if (error)
313                                 goto out_free_opts;
314                         break;
315                 default:
316                         break;
317                 }
318         }
319
320  out_free_opts:
321         kfree(opts);
322  out:
323         /*
324          * If no subvolume name is specified we use the default one.  Allocate
325          * a copy of the string "." here so that code later in the
326          * mount path doesn't care if it's the default volume or another one.
327          */
328         if (!*subvol_name) {
329                 *subvol_name = kstrdup(".", GFP_KERNEL);
330                 if (!*subvol_name)
331                         return -ENOMEM;
332         }
333         return error;
334 }
335
336 static struct dentry *get_default_root(struct super_block *sb,
337                                        u64 subvol_objectid)
338 {
339         struct btrfs_root *root = sb->s_fs_info;
340         struct btrfs_root *new_root;
341         struct btrfs_dir_item *di;
342         struct btrfs_path *path;
343         struct btrfs_key location;
344         struct inode *inode;
345         struct dentry *dentry;
346         u64 dir_id;
347         int new = 0;
348
349         /*
350          * We have a specific subvol we want to mount, just setup location and
351          * go look up the root.
352          */
353         if (subvol_objectid) {
354                 location.objectid = subvol_objectid;
355                 location.type = BTRFS_ROOT_ITEM_KEY;
356                 location.offset = (u64)-1;
357                 goto find_root;
358         }
359
360         path = btrfs_alloc_path();
361         if (!path)
362                 return ERR_PTR(-ENOMEM);
363         path->leave_spinning = 1;
364
365         /*
366          * Find the "default" dir item which points to the root item that we
367          * will mount by default if we haven't been given a specific subvolume
368          * to mount.
369          */
370         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
371         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
372         if (IS_ERR(di))
373                 return ERR_CAST(di);
374         if (!di) {
375                 /*
376                  * Ok the default dir item isn't there.  This is weird since
377                  * it's always been there, but don't freak out, just try and
378                  * mount to root most subvolume.
379                  */
380                 btrfs_free_path(path);
381                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
382                 new_root = root->fs_info->fs_root;
383                 goto setup_root;
384         }
385
386         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
387         btrfs_free_path(path);
388
389 find_root:
390         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
391         if (IS_ERR(new_root))
392                 return ERR_PTR(PTR_ERR(new_root));
393
394         if (btrfs_root_refs(&new_root->root_item) == 0)
395                 return ERR_PTR(-ENOENT);
396
397         dir_id = btrfs_root_dirid(&new_root->root_item);
398 setup_root:
399         location.objectid = dir_id;
400         location.type = BTRFS_INODE_ITEM_KEY;
401         location.offset = 0;
402
403         inode = btrfs_iget(sb, &location, new_root, &new);
404         if (IS_ERR(inode))
405                 return ERR_CAST(inode);
406
407         /*
408          * If we're just mounting the root most subvol put the inode and return
409          * a reference to the dentry.  We will have already gotten a reference
410          * to the inode in btrfs_fill_super so we're good to go.
411          */
412         if (!new && sb->s_root->d_inode == inode) {
413                 iput(inode);
414                 return dget(sb->s_root);
415         }
416
417         if (new) {
418                 const struct qstr name = { .name = "/", .len = 1 };
419
420                 /*
421                  * New inode, we need to make the dentry a sibling of s_root so
422                  * everything gets cleaned up properly on unmount.
423                  */
424                 dentry = d_alloc(sb->s_root, &name);
425                 if (!dentry) {
426                         iput(inode);
427                         return ERR_PTR(-ENOMEM);
428                 }
429                 d_splice_alias(inode, dentry);
430         } else {
431                 /*
432                  * We found the inode in cache, just find a dentry for it and
433                  * put the reference to the inode we just got.
434                  */
435                 dentry = d_find_alias(inode);
436                 iput(inode);
437         }
438
439         return dentry;
440 }
441
442 static int btrfs_fill_super(struct super_block *sb,
443                             struct btrfs_fs_devices *fs_devices,
444                             void *data, int silent)
445 {
446         struct inode *inode;
447         struct dentry *root_dentry;
448         struct btrfs_super_block *disk_super;
449         struct btrfs_root *tree_root;
450         struct btrfs_key key;
451         int err;
452
453         sb->s_maxbytes = MAX_LFS_FILESIZE;
454         sb->s_magic = BTRFS_SUPER_MAGIC;
455         sb->s_op = &btrfs_super_ops;
456         sb->s_export_op = &btrfs_export_ops;
457         sb->s_xattr = btrfs_xattr_handlers;
458         sb->s_time_gran = 1;
459 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
460         sb->s_flags |= MS_POSIXACL;
461 #endif
462
463         tree_root = open_ctree(sb, fs_devices, (char *)data);
464
465         if (IS_ERR(tree_root)) {
466                 printk("btrfs: open_ctree failed\n");
467                 return PTR_ERR(tree_root);
468         }
469         sb->s_fs_info = tree_root;
470         disk_super = &tree_root->fs_info->super_copy;
471
472         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
473         key.type = BTRFS_INODE_ITEM_KEY;
474         key.offset = 0;
475         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
476         if (IS_ERR(inode)) {
477                 err = PTR_ERR(inode);
478                 goto fail_close;
479         }
480
481         root_dentry = d_alloc_root(inode);
482         if (!root_dentry) {
483                 iput(inode);
484                 err = -ENOMEM;
485                 goto fail_close;
486         }
487
488         sb->s_root = root_dentry;
489
490         save_mount_options(sb, data);
491         return 0;
492
493 fail_close:
494         close_ctree(tree_root);
495         return err;
496 }
497
498 int btrfs_sync_fs(struct super_block *sb, int wait)
499 {
500         struct btrfs_trans_handle *trans;
501         struct btrfs_root *root = btrfs_sb(sb);
502         int ret;
503
504         if (!wait) {
505                 filemap_flush(root->fs_info->btree_inode->i_mapping);
506                 return 0;
507         }
508
509         btrfs_start_delalloc_inodes(root, 0);
510         btrfs_wait_ordered_extents(root, 0, 0);
511
512         trans = btrfs_start_transaction(root, 0);
513         ret = btrfs_commit_transaction(trans, root);
514         return ret;
515 }
516
517 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
518 {
519         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
520         struct btrfs_fs_info *info = root->fs_info;
521
522         if (btrfs_test_opt(root, DEGRADED))
523                 seq_puts(seq, ",degraded");
524         if (btrfs_test_opt(root, NODATASUM))
525                 seq_puts(seq, ",nodatasum");
526         if (btrfs_test_opt(root, NODATACOW))
527                 seq_puts(seq, ",nodatacow");
528         if (btrfs_test_opt(root, NOBARRIER))
529                 seq_puts(seq, ",nobarrier");
530         if (info->max_inline != 8192 * 1024)
531                 seq_printf(seq, ",max_inline=%llu",
532                            (unsigned long long)info->max_inline);
533         if (info->alloc_start != 0)
534                 seq_printf(seq, ",alloc_start=%llu",
535                            (unsigned long long)info->alloc_start);
536         if (info->thread_pool_size !=  min_t(unsigned long,
537                                              num_online_cpus() + 2, 8))
538                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
539         if (btrfs_test_opt(root, COMPRESS))
540                 seq_puts(seq, ",compress");
541         if (btrfs_test_opt(root, NOSSD))
542                 seq_puts(seq, ",nossd");
543         if (btrfs_test_opt(root, SSD_SPREAD))
544                 seq_puts(seq, ",ssd_spread");
545         else if (btrfs_test_opt(root, SSD))
546                 seq_puts(seq, ",ssd");
547         if (btrfs_test_opt(root, NOTREELOG))
548                 seq_puts(seq, ",notreelog");
549         if (btrfs_test_opt(root, FLUSHONCOMMIT))
550                 seq_puts(seq, ",flushoncommit");
551         if (btrfs_test_opt(root, DISCARD))
552                 seq_puts(seq, ",discard");
553         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
554                 seq_puts(seq, ",noacl");
555         return 0;
556 }
557
558 static int btrfs_test_super(struct super_block *s, void *data)
559 {
560         struct btrfs_fs_devices *test_fs_devices = data;
561         struct btrfs_root *root = btrfs_sb(s);
562
563         return root->fs_info->fs_devices == test_fs_devices;
564 }
565
566 /*
567  * Find a superblock for the given device / mount point.
568  *
569  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
570  *        for multiple device setup.  Make sure to keep it in sync.
571  */
572 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
573                 const char *dev_name, void *data, struct vfsmount *mnt)
574 {
575         struct block_device *bdev = NULL;
576         struct super_block *s;
577         struct dentry *root;
578         struct btrfs_fs_devices *fs_devices = NULL;
579         fmode_t mode = FMODE_READ;
580         char *subvol_name = NULL;
581         u64 subvol_objectid = 0;
582         int error = 0;
583         int found = 0;
584
585         if (!(flags & MS_RDONLY))
586                 mode |= FMODE_WRITE;
587
588         error = btrfs_parse_early_options(data, mode, fs_type,
589                                           &subvol_name, &subvol_objectid,
590                                           &fs_devices);
591         if (error)
592                 return error;
593
594         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
595         if (error)
596                 goto error_free_subvol_name;
597
598         error = btrfs_open_devices(fs_devices, mode, fs_type);
599         if (error)
600                 goto error_free_subvol_name;
601
602         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
603                 error = -EACCES;
604                 goto error_close_devices;
605         }
606
607         bdev = fs_devices->latest_bdev;
608         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
609         if (IS_ERR(s))
610                 goto error_s;
611
612         if (s->s_root) {
613                 if ((flags ^ s->s_flags) & MS_RDONLY) {
614                         deactivate_locked_super(s);
615                         error = -EBUSY;
616                         goto error_close_devices;
617                 }
618
619                 found = 1;
620                 btrfs_close_devices(fs_devices);
621         } else {
622                 char b[BDEVNAME_SIZE];
623
624                 s->s_flags = flags;
625                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
626                 error = btrfs_fill_super(s, fs_devices, data,
627                                          flags & MS_SILENT ? 1 : 0);
628                 if (error) {
629                         deactivate_locked_super(s);
630                         goto error_free_subvol_name;
631                 }
632
633                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
634                 s->s_flags |= MS_ACTIVE;
635         }
636
637         root = get_default_root(s, subvol_objectid);
638         if (IS_ERR(root)) {
639                 error = PTR_ERR(root);
640                 deactivate_locked_super(s);
641                 goto error_free_subvol_name;
642         }
643         /* if they gave us a subvolume name bind mount into that */
644         if (strcmp(subvol_name, ".")) {
645                 struct dentry *new_root;
646                 mutex_lock(&root->d_inode->i_mutex);
647                 new_root = lookup_one_len(subvol_name, root,
648                                       strlen(subvol_name));
649                 mutex_unlock(&root->d_inode->i_mutex);
650
651                 if (IS_ERR(new_root)) {
652                         deactivate_locked_super(s);
653                         error = PTR_ERR(new_root);
654                         dput(root);
655                         goto error_free_subvol_name;
656                 }
657                 if (!new_root->d_inode) {
658                         dput(root);
659                         dput(new_root);
660                         deactivate_locked_super(s);
661                         error = -ENXIO;
662                         goto error_free_subvol_name;
663                 }
664                 dput(root);
665                 root = new_root;
666         }
667
668         mnt->mnt_sb = s;
669         mnt->mnt_root = root;
670
671         kfree(subvol_name);
672         return 0;
673
674 error_s:
675         error = PTR_ERR(s);
676 error_close_devices:
677         btrfs_close_devices(fs_devices);
678 error_free_subvol_name:
679         kfree(subvol_name);
680         return error;
681 }
682
683 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
684 {
685         struct btrfs_root *root = btrfs_sb(sb);
686         int ret;
687
688         ret = btrfs_parse_options(root, data);
689         if (ret)
690                 return -EINVAL;
691
692         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
693                 return 0;
694
695         if (*flags & MS_RDONLY) {
696                 sb->s_flags |= MS_RDONLY;
697
698                 ret =  btrfs_commit_super(root);
699                 WARN_ON(ret);
700         } else {
701                 if (root->fs_info->fs_devices->rw_devices == 0)
702                         return -EACCES;
703
704                 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
705                         return -EINVAL;
706
707                 ret = btrfs_cleanup_fs_roots(root->fs_info);
708                 WARN_ON(ret);
709
710                 /* recover relocation */
711                 ret = btrfs_recover_relocation(root);
712                 WARN_ON(ret);
713
714                 sb->s_flags &= ~MS_RDONLY;
715         }
716
717         return 0;
718 }
719
720 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
721 {
722         struct btrfs_root *root = btrfs_sb(dentry->d_sb);
723         struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
724         struct list_head *head = &root->fs_info->space_info;
725         struct btrfs_space_info *found;
726         u64 total_used = 0;
727         u64 total_used_data = 0;
728         int bits = dentry->d_sb->s_blocksize_bits;
729         __be32 *fsid = (__be32 *)root->fs_info->fsid;
730
731         rcu_read_lock();
732         list_for_each_entry_rcu(found, head, list) {
733                 if (found->flags & (BTRFS_BLOCK_GROUP_METADATA |
734                                     BTRFS_BLOCK_GROUP_SYSTEM))
735                         total_used_data += found->disk_total;
736                 else
737                         total_used_data += found->disk_used;
738                 total_used += found->disk_used;
739         }
740         rcu_read_unlock();
741
742         buf->f_namelen = BTRFS_NAME_LEN;
743         buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
744         buf->f_bfree = buf->f_blocks - (total_used >> bits);
745         buf->f_bavail = buf->f_blocks - (total_used_data >> bits);
746         buf->f_bsize = dentry->d_sb->s_blocksize;
747         buf->f_type = BTRFS_SUPER_MAGIC;
748
749         /* We treat it as constant endianness (it doesn't matter _which_)
750            because we want the fsid to come out the same whether mounted
751            on a big-endian or little-endian host */
752         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
753         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
754         /* Mask in the root object ID too, to disambiguate subvols */
755         buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
756         buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
757
758         return 0;
759 }
760
761 static struct file_system_type btrfs_fs_type = {
762         .owner          = THIS_MODULE,
763         .name           = "btrfs",
764         .get_sb         = btrfs_get_sb,
765         .kill_sb        = kill_anon_super,
766         .fs_flags       = FS_REQUIRES_DEV,
767 };
768
769 /*
770  * used by btrfsctl to scan devices when no FS is mounted
771  */
772 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
773                                 unsigned long arg)
774 {
775         struct btrfs_ioctl_vol_args *vol;
776         struct btrfs_fs_devices *fs_devices;
777         int ret = -ENOTTY;
778
779         if (!capable(CAP_SYS_ADMIN))
780                 return -EPERM;
781
782         vol = memdup_user((void __user *)arg, sizeof(*vol));
783         if (IS_ERR(vol))
784                 return PTR_ERR(vol);
785
786         switch (cmd) {
787         case BTRFS_IOC_SCAN_DEV:
788                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
789                                             &btrfs_fs_type, &fs_devices);
790                 break;
791         }
792
793         kfree(vol);
794         return ret;
795 }
796
797 static int btrfs_freeze(struct super_block *sb)
798 {
799         struct btrfs_root *root = btrfs_sb(sb);
800         mutex_lock(&root->fs_info->transaction_kthread_mutex);
801         mutex_lock(&root->fs_info->cleaner_mutex);
802         return 0;
803 }
804
805 static int btrfs_unfreeze(struct super_block *sb)
806 {
807         struct btrfs_root *root = btrfs_sb(sb);
808         mutex_unlock(&root->fs_info->cleaner_mutex);
809         mutex_unlock(&root->fs_info->transaction_kthread_mutex);
810         return 0;
811 }
812
813 static const struct super_operations btrfs_super_ops = {
814         .drop_inode     = btrfs_drop_inode,
815         .evict_inode    = btrfs_evict_inode,
816         .put_super      = btrfs_put_super,
817         .sync_fs        = btrfs_sync_fs,
818         .show_options   = btrfs_show_options,
819         .write_inode    = btrfs_write_inode,
820         .dirty_inode    = btrfs_dirty_inode,
821         .alloc_inode    = btrfs_alloc_inode,
822         .destroy_inode  = btrfs_destroy_inode,
823         .statfs         = btrfs_statfs,
824         .remount_fs     = btrfs_remount,
825         .freeze_fs      = btrfs_freeze,
826         .unfreeze_fs    = btrfs_unfreeze,
827 };
828
829 static const struct file_operations btrfs_ctl_fops = {
830         .unlocked_ioctl  = btrfs_control_ioctl,
831         .compat_ioctl = btrfs_control_ioctl,
832         .owner   = THIS_MODULE,
833 };
834
835 static struct miscdevice btrfs_misc = {
836         .minor          = BTRFS_MINOR,
837         .name           = "btrfs-control",
838         .fops           = &btrfs_ctl_fops
839 };
840
841 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
842 MODULE_ALIAS("devname:btrfs-control");
843
844 static int btrfs_interface_init(void)
845 {
846         return misc_register(&btrfs_misc);
847 }
848
849 static void btrfs_interface_exit(void)
850 {
851         if (misc_deregister(&btrfs_misc) < 0)
852                 printk(KERN_INFO "misc_deregister failed for control device");
853 }
854
855 static int __init init_btrfs_fs(void)
856 {
857         int err;
858
859         err = btrfs_init_sysfs();
860         if (err)
861                 return err;
862
863         err = btrfs_init_cachep();
864         if (err)
865                 goto free_sysfs;
866
867         err = extent_io_init();
868         if (err)
869                 goto free_cachep;
870
871         err = extent_map_init();
872         if (err)
873                 goto free_extent_io;
874
875         err = btrfs_interface_init();
876         if (err)
877                 goto free_extent_map;
878
879         err = register_filesystem(&btrfs_fs_type);
880         if (err)
881                 goto unregister_ioctl;
882
883         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
884         return 0;
885
886 unregister_ioctl:
887         btrfs_interface_exit();
888 free_extent_map:
889         extent_map_exit();
890 free_extent_io:
891         extent_io_exit();
892 free_cachep:
893         btrfs_destroy_cachep();
894 free_sysfs:
895         btrfs_exit_sysfs();
896         return err;
897 }
898
899 static void __exit exit_btrfs_fs(void)
900 {
901         btrfs_destroy_cachep();
902         extent_map_exit();
903         extent_io_exit();
904         btrfs_interface_exit();
905         unregister_filesystem(&btrfs_fs_type);
906         btrfs_exit_sysfs();
907         btrfs_cleanup_fs_uuids();
908         btrfs_zlib_exit();
909 }
910
911 module_init(init_btrfs_fs)
912 module_exit(exit_btrfs_fs)
913
914 MODULE_LICENSE("GPL");