Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/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         (void)ret; /* FIXME: need to fix VFS to return error? */
66 }
67
68 enum {
69         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
70         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
71         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
72         Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
73         Opt_discard, Opt_space_cache, Opt_clear_cache, Opt_err,
74         Opt_user_subvol_rm_allowed,
75 };
76
77 static match_table_t tokens = {
78         {Opt_degraded, "degraded"},
79         {Opt_subvol, "subvol=%s"},
80         {Opt_subvolid, "subvolid=%d"},
81         {Opt_device, "device=%s"},
82         {Opt_nodatasum, "nodatasum"},
83         {Opt_nodatacow, "nodatacow"},
84         {Opt_nobarrier, "nobarrier"},
85         {Opt_max_inline, "max_inline=%s"},
86         {Opt_alloc_start, "alloc_start=%s"},
87         {Opt_thread_pool, "thread_pool=%d"},
88         {Opt_compress, "compress"},
89         {Opt_compress_force, "compress-force"},
90         {Opt_ssd, "ssd"},
91         {Opt_ssd_spread, "ssd_spread"},
92         {Opt_nossd, "nossd"},
93         {Opt_noacl, "noacl"},
94         {Opt_notreelog, "notreelog"},
95         {Opt_flushoncommit, "flushoncommit"},
96         {Opt_ratio, "metadata_ratio=%d"},
97         {Opt_discard, "discard"},
98         {Opt_space_cache, "space_cache"},
99         {Opt_clear_cache, "clear_cache"},
100         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
101         {Opt_err, NULL},
102 };
103
104 /*
105  * Regular mount options parser.  Everything that is needed only when
106  * reading in a new superblock is parsed here.
107  */
108 int btrfs_parse_options(struct btrfs_root *root, char *options)
109 {
110         struct btrfs_fs_info *info = root->fs_info;
111         substring_t args[MAX_OPT_ARGS];
112         char *p, *num, *orig;
113         int intarg;
114         int ret = 0;
115
116         if (!options)
117                 return 0;
118
119         /*
120          * strsep changes the string, duplicate it because parse_options
121          * gets called twice
122          */
123         options = kstrdup(options, GFP_NOFS);
124         if (!options)
125                 return -ENOMEM;
126
127         orig = options;
128
129         while ((p = strsep(&options, ",")) != NULL) {
130                 int token;
131                 if (!*p)
132                         continue;
133
134                 token = match_token(p, tokens, args);
135                 switch (token) {
136                 case Opt_degraded:
137                         printk(KERN_INFO "btrfs: allowing degraded mounts\n");
138                         btrfs_set_opt(info->mount_opt, DEGRADED);
139                         break;
140                 case Opt_subvol:
141                 case Opt_subvolid:
142                 case Opt_device:
143                         /*
144                          * These are parsed by btrfs_parse_early_options
145                          * and can be happily ignored here.
146                          */
147                         break;
148                 case Opt_nodatasum:
149                         printk(KERN_INFO "btrfs: setting nodatasum\n");
150                         btrfs_set_opt(info->mount_opt, NODATASUM);
151                         break;
152                 case Opt_nodatacow:
153                         printk(KERN_INFO "btrfs: setting nodatacow\n");
154                         btrfs_set_opt(info->mount_opt, NODATACOW);
155                         btrfs_set_opt(info->mount_opt, NODATASUM);
156                         break;
157                 case Opt_compress:
158                         printk(KERN_INFO "btrfs: use compression\n");
159                         btrfs_set_opt(info->mount_opt, COMPRESS);
160                         break;
161                 case Opt_compress_force:
162                         printk(KERN_INFO "btrfs: forcing compression\n");
163                         btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
164                         btrfs_set_opt(info->mount_opt, COMPRESS);
165                         break;
166                 case Opt_ssd:
167                         printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
168                         btrfs_set_opt(info->mount_opt, SSD);
169                         break;
170                 case Opt_ssd_spread:
171                         printk(KERN_INFO "btrfs: use spread ssd "
172                                "allocation scheme\n");
173                         btrfs_set_opt(info->mount_opt, SSD);
174                         btrfs_set_opt(info->mount_opt, SSD_SPREAD);
175                         break;
176                 case Opt_nossd:
177                         printk(KERN_INFO "btrfs: not using ssd allocation "
178                                "scheme\n");
179                         btrfs_set_opt(info->mount_opt, NOSSD);
180                         btrfs_clear_opt(info->mount_opt, SSD);
181                         btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
182                         break;
183                 case Opt_nobarrier:
184                         printk(KERN_INFO "btrfs: turning off barriers\n");
185                         btrfs_set_opt(info->mount_opt, NOBARRIER);
186                         break;
187                 case Opt_thread_pool:
188                         intarg = 0;
189                         match_int(&args[0], &intarg);
190                         if (intarg) {
191                                 info->thread_pool_size = intarg;
192                                 printk(KERN_INFO "btrfs: thread pool %d\n",
193                                        info->thread_pool_size);
194                         }
195                         break;
196                 case Opt_max_inline:
197                         num = match_strdup(&args[0]);
198                         if (num) {
199                                 info->max_inline = memparse(num, NULL);
200                                 kfree(num);
201
202                                 if (info->max_inline) {
203                                         info->max_inline = max_t(u64,
204                                                 info->max_inline,
205                                                 root->sectorsize);
206                                 }
207                                 printk(KERN_INFO "btrfs: max_inline at %llu\n",
208                                         (unsigned long long)info->max_inline);
209                         }
210                         break;
211                 case Opt_alloc_start:
212                         num = match_strdup(&args[0]);
213                         if (num) {
214                                 info->alloc_start = memparse(num, NULL);
215                                 kfree(num);
216                                 printk(KERN_INFO
217                                         "btrfs: allocations start at %llu\n",
218                                         (unsigned long long)info->alloc_start);
219                         }
220                         break;
221                 case Opt_noacl:
222                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
223                         break;
224                 case Opt_notreelog:
225                         printk(KERN_INFO "btrfs: disabling tree log\n");
226                         btrfs_set_opt(info->mount_opt, NOTREELOG);
227                         break;
228                 case Opt_flushoncommit:
229                         printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
230                         btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
231                         break;
232                 case Opt_ratio:
233                         intarg = 0;
234                         match_int(&args[0], &intarg);
235                         if (intarg) {
236                                 info->metadata_ratio = intarg;
237                                 printk(KERN_INFO "btrfs: metadata ratio %d\n",
238                                        info->metadata_ratio);
239                         }
240                         break;
241                 case Opt_discard:
242                         btrfs_set_opt(info->mount_opt, DISCARD);
243                         break;
244                 case Opt_space_cache:
245                         printk(KERN_INFO "btrfs: enabling disk space caching\n");
246                         btrfs_set_opt(info->mount_opt, SPACE_CACHE);
247                 case Opt_clear_cache:
248                         printk(KERN_INFO "btrfs: force clearing of disk cache\n");
249                         btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
250                         break;
251                 case Opt_user_subvol_rm_allowed:
252                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
253                         break;
254                 case Opt_err:
255                         printk(KERN_INFO "btrfs: unrecognized mount option "
256                                "'%s'\n", p);
257                         ret = -EINVAL;
258                         goto out;
259                 default:
260                         break;
261                 }
262         }
263 out:
264         kfree(orig);
265         return ret;
266 }
267
268 /*
269  * Parse mount options that are required early in the mount process.
270  *
271  * All other options will be parsed on much later in the mount process and
272  * only when we need to allocate a new super block.
273  */
274 static int btrfs_parse_early_options(const char *options, fmode_t flags,
275                 void *holder, char **subvol_name, u64 *subvol_objectid,
276                 struct btrfs_fs_devices **fs_devices)
277 {
278         substring_t args[MAX_OPT_ARGS];
279         char *opts, *p;
280         int error = 0;
281         int intarg;
282
283         if (!options)
284                 goto out;
285
286         /*
287          * strsep changes the string, duplicate it because parse_options
288          * gets called twice
289          */
290         opts = kstrdup(options, GFP_KERNEL);
291         if (!opts)
292                 return -ENOMEM;
293
294         while ((p = strsep(&opts, ",")) != NULL) {
295                 int token;
296                 if (!*p)
297                         continue;
298
299                 token = match_token(p, tokens, args);
300                 switch (token) {
301                 case Opt_subvol:
302                         *subvol_name = match_strdup(&args[0]);
303                         break;
304                 case Opt_subvolid:
305                         intarg = 0;
306                         error = match_int(&args[0], &intarg);
307                         if (!error) {
308                                 /* we want the original fs_tree */
309                                 if (!intarg)
310                                         *subvol_objectid =
311                                                 BTRFS_FS_TREE_OBJECTID;
312                                 else
313                                         *subvol_objectid = intarg;
314                         }
315                         break;
316                 case Opt_device:
317                         error = btrfs_scan_one_device(match_strdup(&args[0]),
318                                         flags, holder, fs_devices);
319                         if (error)
320                                 goto out_free_opts;
321                         break;
322                 default:
323                         break;
324                 }
325         }
326
327  out_free_opts:
328         kfree(opts);
329  out:
330         /*
331          * If no subvolume name is specified we use the default one.  Allocate
332          * a copy of the string "." here so that code later in the
333          * mount path doesn't care if it's the default volume or another one.
334          */
335         if (!*subvol_name) {
336                 *subvol_name = kstrdup(".", GFP_KERNEL);
337                 if (!*subvol_name)
338                         return -ENOMEM;
339         }
340         return error;
341 }
342
343 static struct dentry *get_default_root(struct super_block *sb,
344                                        u64 subvol_objectid)
345 {
346         struct btrfs_root *root = sb->s_fs_info;
347         struct btrfs_root *new_root;
348         struct btrfs_dir_item *di;
349         struct btrfs_path *path;
350         struct btrfs_key location;
351         struct inode *inode;
352         struct dentry *dentry;
353         u64 dir_id;
354         int new = 0;
355
356         /*
357          * We have a specific subvol we want to mount, just setup location and
358          * go look up the root.
359          */
360         if (subvol_objectid) {
361                 location.objectid = subvol_objectid;
362                 location.type = BTRFS_ROOT_ITEM_KEY;
363                 location.offset = (u64)-1;
364                 goto find_root;
365         }
366
367         path = btrfs_alloc_path();
368         if (!path)
369                 return ERR_PTR(-ENOMEM);
370         path->leave_spinning = 1;
371
372         /*
373          * Find the "default" dir item which points to the root item that we
374          * will mount by default if we haven't been given a specific subvolume
375          * to mount.
376          */
377         dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
378         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
379         if (IS_ERR(di))
380                 return ERR_CAST(di);
381         if (!di) {
382                 /*
383                  * Ok the default dir item isn't there.  This is weird since
384                  * it's always been there, but don't freak out, just try and
385                  * mount to root most subvolume.
386                  */
387                 btrfs_free_path(path);
388                 dir_id = BTRFS_FIRST_FREE_OBJECTID;
389                 new_root = root->fs_info->fs_root;
390                 goto setup_root;
391         }
392
393         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
394         btrfs_free_path(path);
395
396 find_root:
397         new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
398         if (IS_ERR(new_root))
399                 return ERR_CAST(new_root);
400
401         if (btrfs_root_refs(&new_root->root_item) == 0)
402                 return ERR_PTR(-ENOENT);
403
404         dir_id = btrfs_root_dirid(&new_root->root_item);
405 setup_root:
406         location.objectid = dir_id;
407         location.type = BTRFS_INODE_ITEM_KEY;
408         location.offset = 0;
409
410         inode = btrfs_iget(sb, &location, new_root, &new);
411         if (IS_ERR(inode))
412                 return ERR_CAST(inode);
413
414         /*
415          * If we're just mounting the root most subvol put the inode and return
416          * a reference to the dentry.  We will have already gotten a reference
417          * to the inode in btrfs_fill_super so we're good to go.
418          */
419         if (!new && sb->s_root->d_inode == inode) {
420                 iput(inode);
421                 return dget(sb->s_root);
422         }
423
424         if (new) {
425                 const struct qstr name = { .name = "/", .len = 1 };
426
427                 /*
428                  * New inode, we need to make the dentry a sibling of s_root so
429                  * everything gets cleaned up properly on unmount.
430                  */
431                 dentry = d_alloc(sb->s_root, &name);
432                 if (!dentry) {
433                         iput(inode);
434                         return ERR_PTR(-ENOMEM);
435                 }
436                 d_splice_alias(inode, dentry);
437         } else {
438                 /*
439                  * We found the inode in cache, just find a dentry for it and
440                  * put the reference to the inode we just got.
441                  */
442                 dentry = d_find_alias(inode);
443                 iput(inode);
444         }
445
446         return dentry;
447 }
448
449 static int btrfs_fill_super(struct super_block *sb,
450                             struct btrfs_fs_devices *fs_devices,
451                             void *data, int silent)
452 {
453         struct inode *inode;
454         struct dentry *root_dentry;
455         struct btrfs_root *tree_root;
456         struct btrfs_key key;
457         int err;
458
459         sb->s_maxbytes = MAX_LFS_FILESIZE;
460         sb->s_magic = BTRFS_SUPER_MAGIC;
461         sb->s_op = &btrfs_super_ops;
462         sb->s_export_op = &btrfs_export_ops;
463         sb->s_xattr = btrfs_xattr_handlers;
464         sb->s_time_gran = 1;
465 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
466         sb->s_flags |= MS_POSIXACL;
467 #endif
468
469         tree_root = open_ctree(sb, fs_devices, (char *)data);
470
471         if (IS_ERR(tree_root)) {
472                 printk("btrfs: open_ctree failed\n");
473                 return PTR_ERR(tree_root);
474         }
475         sb->s_fs_info = tree_root;
476
477         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
478         key.type = BTRFS_INODE_ITEM_KEY;
479         key.offset = 0;
480         inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
481         if (IS_ERR(inode)) {
482                 err = PTR_ERR(inode);
483                 goto fail_close;
484         }
485
486         root_dentry = d_alloc_root(inode);
487         if (!root_dentry) {
488                 iput(inode);
489                 err = -ENOMEM;
490                 goto fail_close;
491         }
492
493         sb->s_root = root_dentry;
494
495         save_mount_options(sb, data);
496         return 0;
497
498 fail_close:
499         close_ctree(tree_root);
500         return err;
501 }
502
503 int btrfs_sync_fs(struct super_block *sb, int wait)
504 {
505         struct btrfs_trans_handle *trans;
506         struct btrfs_root *root = btrfs_sb(sb);
507         int ret;
508
509         if (!wait) {
510                 filemap_flush(root->fs_info->btree_inode->i_mapping);
511                 return 0;
512         }
513
514         btrfs_start_delalloc_inodes(root, 0);
515         btrfs_wait_ordered_extents(root, 0, 0);
516
517         trans = btrfs_start_transaction(root, 0);
518         ret = btrfs_commit_transaction(trans, root);
519         return ret;
520 }
521
522 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
523 {
524         struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
525         struct btrfs_fs_info *info = root->fs_info;
526
527         if (btrfs_test_opt(root, DEGRADED))
528                 seq_puts(seq, ",degraded");
529         if (btrfs_test_opt(root, NODATASUM))
530                 seq_puts(seq, ",nodatasum");
531         if (btrfs_test_opt(root, NODATACOW))
532                 seq_puts(seq, ",nodatacow");
533         if (btrfs_test_opt(root, NOBARRIER))
534                 seq_puts(seq, ",nobarrier");
535         if (info->max_inline != 8192 * 1024)
536                 seq_printf(seq, ",max_inline=%llu",
537                            (unsigned long long)info->max_inline);
538         if (info->alloc_start != 0)
539                 seq_printf(seq, ",alloc_start=%llu",
540                            (unsigned long long)info->alloc_start);
541         if (info->thread_pool_size !=  min_t(unsigned long,
542                                              num_online_cpus() + 2, 8))
543                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
544         if (btrfs_test_opt(root, COMPRESS))
545                 seq_puts(seq, ",compress");
546         if (btrfs_test_opt(root, NOSSD))
547                 seq_puts(seq, ",nossd");
548         if (btrfs_test_opt(root, SSD_SPREAD))
549                 seq_puts(seq, ",ssd_spread");
550         else if (btrfs_test_opt(root, SSD))
551                 seq_puts(seq, ",ssd");
552         if (btrfs_test_opt(root, NOTREELOG))
553                 seq_puts(seq, ",notreelog");
554         if (btrfs_test_opt(root, FLUSHONCOMMIT))
555                 seq_puts(seq, ",flushoncommit");
556         if (btrfs_test_opt(root, DISCARD))
557                 seq_puts(seq, ",discard");
558         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
559                 seq_puts(seq, ",noacl");
560         return 0;
561 }
562
563 static int btrfs_test_super(struct super_block *s, void *data)
564 {
565         struct btrfs_fs_devices *test_fs_devices = data;
566         struct btrfs_root *root = btrfs_sb(s);
567
568         return root->fs_info->fs_devices == test_fs_devices;
569 }
570
571 /*
572  * Find a superblock for the given device / mount point.
573  *
574  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
575  *        for multiple device setup.  Make sure to keep it in sync.
576  */
577 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
578                 const char *dev_name, void *data)
579 {
580         struct block_device *bdev = NULL;
581         struct super_block *s;
582         struct dentry *root;
583         struct btrfs_fs_devices *fs_devices = NULL;
584         fmode_t mode = FMODE_READ;
585         char *subvol_name = NULL;
586         u64 subvol_objectid = 0;
587         int error = 0;
588
589         if (!(flags & MS_RDONLY))
590                 mode |= FMODE_WRITE;
591
592         error = btrfs_parse_early_options(data, mode, fs_type,
593                                           &subvol_name, &subvol_objectid,
594                                           &fs_devices);
595         if (error)
596                 return ERR_PTR(error);
597
598         error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
599         if (error)
600                 goto error_free_subvol_name;
601
602         error = btrfs_open_devices(fs_devices, mode, fs_type);
603         if (error)
604                 goto error_free_subvol_name;
605
606         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
607                 error = -EACCES;
608                 goto error_close_devices;
609         }
610
611         bdev = fs_devices->latest_bdev;
612         s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
613         if (IS_ERR(s))
614                 goto error_s;
615
616         if (s->s_root) {
617                 if ((flags ^ s->s_flags) & MS_RDONLY) {
618                         deactivate_locked_super(s);
619                         error = -EBUSY;
620                         goto error_close_devices;
621                 }
622
623                 btrfs_close_devices(fs_devices);
624         } else {
625                 char b[BDEVNAME_SIZE];
626
627                 s->s_flags = flags;
628                 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
629                 error = btrfs_fill_super(s, fs_devices, data,
630                                          flags & MS_SILENT ? 1 : 0);
631                 if (error) {
632                         deactivate_locked_super(s);
633                         goto error_free_subvol_name;
634                 }
635
636                 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
637                 s->s_flags |= MS_ACTIVE;
638         }
639
640         root = get_default_root(s, subvol_objectid);
641         if (IS_ERR(root)) {
642                 error = PTR_ERR(root);
643                 deactivate_locked_super(s);
644                 goto error_free_subvol_name;
645         }
646         /* if they gave us a subvolume name bind mount into that */
647         if (strcmp(subvol_name, ".")) {
648                 struct dentry *new_root;
649                 mutex_lock(&root->d_inode->i_mutex);
650                 new_root = lookup_one_len(subvol_name, root,
651                                       strlen(subvol_name));
652                 mutex_unlock(&root->d_inode->i_mutex);
653
654                 if (IS_ERR(new_root)) {
655                         deactivate_locked_super(s);
656                         error = PTR_ERR(new_root);
657                         dput(root);
658                         goto error_free_subvol_name;
659                 }
660                 if (!new_root->d_inode) {
661                         dput(root);
662                         dput(new_root);
663                         deactivate_locked_super(s);
664                         error = -ENXIO;
665                         goto error_free_subvol_name;
666                 }
667                 dput(root);
668                 root = new_root;
669         }
670
671         kfree(subvol_name);
672         return root;
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 ERR_PTR(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         .mount          = btrfs_mount,
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         .llseek = noop_llseek,
834 };
835
836 static struct miscdevice btrfs_misc = {
837         .minor          = BTRFS_MINOR,
838         .name           = "btrfs-control",
839         .fops           = &btrfs_ctl_fops
840 };
841
842 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
843 MODULE_ALIAS("devname:btrfs-control");
844
845 static int btrfs_interface_init(void)
846 {
847         return misc_register(&btrfs_misc);
848 }
849
850 static void btrfs_interface_exit(void)
851 {
852         if (misc_deregister(&btrfs_misc) < 0)
853                 printk(KERN_INFO "misc_deregister failed for control device");
854 }
855
856 static int __init init_btrfs_fs(void)
857 {
858         int err;
859
860         err = btrfs_init_sysfs();
861         if (err)
862                 return err;
863
864         err = btrfs_init_cachep();
865         if (err)
866                 goto free_sysfs;
867
868         err = extent_io_init();
869         if (err)
870                 goto free_cachep;
871
872         err = extent_map_init();
873         if (err)
874                 goto free_extent_io;
875
876         err = btrfs_interface_init();
877         if (err)
878                 goto free_extent_map;
879
880         err = register_filesystem(&btrfs_fs_type);
881         if (err)
882                 goto unregister_ioctl;
883
884         printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
885         return 0;
886
887 unregister_ioctl:
888         btrfs_interface_exit();
889 free_extent_map:
890         extent_map_exit();
891 free_extent_io:
892         extent_io_exit();
893 free_cachep:
894         btrfs_destroy_cachep();
895 free_sysfs:
896         btrfs_exit_sysfs();
897         return err;
898 }
899
900 static void __exit exit_btrfs_fs(void)
901 {
902         btrfs_destroy_cachep();
903         extent_map_exit();
904         extent_io_exit();
905         btrfs_interface_exit();
906         unregister_filesystem(&btrfs_fs_type);
907         btrfs_exit_sysfs();
908         btrfs_cleanup_fs_uuids();
909         btrfs_zlib_exit();
910 }
911
912 module_init(init_btrfs_fs)
913 module_exit(exit_btrfs_fs)
914
915 MODULE_LICENSE("GPL");