xref: /linux/fs/btrfs/super.c (revision 2e18e047981ae04be9bd0d9760057f7c1a7b3785)
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 "compat.h"
42 #include "ctree.h"
43 #include "disk-io.h"
44 #include "transaction.h"
45 #include "btrfs_inode.h"
46 #include "ioctl.h"
47 #include "print-tree.h"
48 #include "xattr.h"
49 #include "volumes.h"
50 #include "version.h"
51 #include "export.h"
52 #include "compression.h"
53 
54 static const struct super_operations btrfs_super_ops;
55 
56 static void btrfs_put_super(struct super_block *sb)
57 {
58 	struct btrfs_root *root = btrfs_sb(sb);
59 	int ret;
60 
61 	ret = close_ctree(root);
62 	sb->s_fs_info = NULL;
63 }
64 
65 enum {
66 	Opt_degraded, Opt_subvol, Opt_device, Opt_nodatasum, Opt_nodatacow,
67 	Opt_max_extent, Opt_max_inline, Opt_alloc_start, Opt_nobarrier,
68 	Opt_ssd, Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl,
69 	Opt_compress, Opt_compress_force, Opt_notreelog, Opt_ratio,
70 	Opt_flushoncommit,
71 	Opt_discard, Opt_err,
72 };
73 
74 static match_table_t tokens = {
75 	{Opt_degraded, "degraded"},
76 	{Opt_subvol, "subvol=%s"},
77 	{Opt_device, "device=%s"},
78 	{Opt_nodatasum, "nodatasum"},
79 	{Opt_nodatacow, "nodatacow"},
80 	{Opt_nobarrier, "nobarrier"},
81 	{Opt_max_extent, "max_extent=%s"},
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_err, NULL},
96 };
97 
98 u64 btrfs_parse_size(char *str)
99 {
100 	u64 res;
101 	int mult = 1;
102 	char *end;
103 	char last;
104 
105 	res = simple_strtoul(str, &end, 10);
106 
107 	last = end[0];
108 	if (isalpha(last)) {
109 		last = tolower(last);
110 		switch (last) {
111 		case 'g':
112 			mult *= 1024;
113 		case 'm':
114 			mult *= 1024;
115 		case 'k':
116 			mult *= 1024;
117 		}
118 		res = res * mult;
119 	}
120 	return res;
121 }
122 
123 /*
124  * Regular mount options parser.  Everything that is needed only when
125  * reading in a new superblock is parsed here.
126  */
127 int btrfs_parse_options(struct btrfs_root *root, char *options)
128 {
129 	struct btrfs_fs_info *info = root->fs_info;
130 	substring_t args[MAX_OPT_ARGS];
131 	char *p, *num;
132 	int intarg;
133 	int ret = 0;
134 
135 	if (!options)
136 		return 0;
137 
138 	/*
139 	 * strsep changes the string, duplicate it because parse_options
140 	 * gets called twice
141 	 */
142 	options = kstrdup(options, GFP_NOFS);
143 	if (!options)
144 		return -ENOMEM;
145 
146 
147 	while ((p = strsep(&options, ",")) != NULL) {
148 		int token;
149 		if (!*p)
150 			continue;
151 
152 		token = match_token(p, tokens, args);
153 		switch (token) {
154 		case Opt_degraded:
155 			printk(KERN_INFO "btrfs: allowing degraded mounts\n");
156 			btrfs_set_opt(info->mount_opt, DEGRADED);
157 			break;
158 		case Opt_subvol:
159 		case Opt_device:
160 			/*
161 			 * These are parsed by btrfs_parse_early_options
162 			 * and can be happily ignored here.
163 			 */
164 			break;
165 		case Opt_nodatasum:
166 			printk(KERN_INFO "btrfs: setting nodatasum\n");
167 			btrfs_set_opt(info->mount_opt, NODATASUM);
168 			break;
169 		case Opt_nodatacow:
170 			printk(KERN_INFO "btrfs: setting nodatacow\n");
171 			btrfs_set_opt(info->mount_opt, NODATACOW);
172 			btrfs_set_opt(info->mount_opt, NODATASUM);
173 			break;
174 		case Opt_compress:
175 			printk(KERN_INFO "btrfs: use compression\n");
176 			btrfs_set_opt(info->mount_opt, COMPRESS);
177 			break;
178 		case Opt_compress_force:
179 			printk(KERN_INFO "btrfs: forcing compression\n");
180 			btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
181 			btrfs_set_opt(info->mount_opt, COMPRESS);
182 			break;
183 		case Opt_ssd:
184 			printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
185 			btrfs_set_opt(info->mount_opt, SSD);
186 			break;
187 		case Opt_ssd_spread:
188 			printk(KERN_INFO "btrfs: use spread ssd "
189 			       "allocation scheme\n");
190 			btrfs_set_opt(info->mount_opt, SSD);
191 			btrfs_set_opt(info->mount_opt, SSD_SPREAD);
192 			break;
193 		case Opt_nossd:
194 			printk(KERN_INFO "btrfs: not using ssd allocation "
195 			       "scheme\n");
196 			btrfs_set_opt(info->mount_opt, NOSSD);
197 			btrfs_clear_opt(info->mount_opt, SSD);
198 			btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
199 			break;
200 		case Opt_nobarrier:
201 			printk(KERN_INFO "btrfs: turning off barriers\n");
202 			btrfs_set_opt(info->mount_opt, NOBARRIER);
203 			break;
204 		case Opt_thread_pool:
205 			intarg = 0;
206 			match_int(&args[0], &intarg);
207 			if (intarg) {
208 				info->thread_pool_size = intarg;
209 				printk(KERN_INFO "btrfs: thread pool %d\n",
210 				       info->thread_pool_size);
211 			}
212 			break;
213 		case Opt_max_extent:
214 			num = match_strdup(&args[0]);
215 			if (num) {
216 				info->max_extent = btrfs_parse_size(num);
217 				kfree(num);
218 
219 				info->max_extent = max_t(u64,
220 					info->max_extent, root->sectorsize);
221 				printk(KERN_INFO "btrfs: max_extent at %llu\n",
222 				       (unsigned long long)info->max_extent);
223 			}
224 			break;
225 		case Opt_max_inline:
226 			num = match_strdup(&args[0]);
227 			if (num) {
228 				info->max_inline = btrfs_parse_size(num);
229 				kfree(num);
230 
231 				if (info->max_inline) {
232 					info->max_inline = max_t(u64,
233 						info->max_inline,
234 						root->sectorsize);
235 				}
236 				printk(KERN_INFO "btrfs: max_inline at %llu\n",
237 					(unsigned long long)info->max_inline);
238 			}
239 			break;
240 		case Opt_alloc_start:
241 			num = match_strdup(&args[0]);
242 			if (num) {
243 				info->alloc_start = btrfs_parse_size(num);
244 				kfree(num);
245 				printk(KERN_INFO
246 					"btrfs: allocations start at %llu\n",
247 					(unsigned long long)info->alloc_start);
248 			}
249 			break;
250 		case Opt_noacl:
251 			root->fs_info->sb->s_flags &= ~MS_POSIXACL;
252 			break;
253 		case Opt_notreelog:
254 			printk(KERN_INFO "btrfs: disabling tree log\n");
255 			btrfs_set_opt(info->mount_opt, NOTREELOG);
256 			break;
257 		case Opt_flushoncommit:
258 			printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
259 			btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
260 			break;
261 		case Opt_ratio:
262 			intarg = 0;
263 			match_int(&args[0], &intarg);
264 			if (intarg) {
265 				info->metadata_ratio = intarg;
266 				printk(KERN_INFO "btrfs: metadata ratio %d\n",
267 				       info->metadata_ratio);
268 			}
269 			break;
270 		case Opt_discard:
271 			btrfs_set_opt(info->mount_opt, DISCARD);
272 			break;
273 		case Opt_err:
274 			printk(KERN_INFO "btrfs: unrecognized mount option "
275 			       "'%s'\n", p);
276 			ret = -EINVAL;
277 			goto out;
278 		default:
279 			break;
280 		}
281 	}
282 out:
283 	kfree(options);
284 	return ret;
285 }
286 
287 /*
288  * Parse mount options that are required early in the mount process.
289  *
290  * All other options will be parsed on much later in the mount process and
291  * only when we need to allocate a new super block.
292  */
293 static int btrfs_parse_early_options(const char *options, fmode_t flags,
294 		void *holder, char **subvol_name,
295 		struct btrfs_fs_devices **fs_devices)
296 {
297 	substring_t args[MAX_OPT_ARGS];
298 	char *opts, *p;
299 	int error = 0;
300 
301 	if (!options)
302 		goto out;
303 
304 	/*
305 	 * strsep changes the string, duplicate it because parse_options
306 	 * gets called twice
307 	 */
308 	opts = kstrdup(options, GFP_KERNEL);
309 	if (!opts)
310 		return -ENOMEM;
311 
312 	while ((p = strsep(&opts, ",")) != NULL) {
313 		int token;
314 		if (!*p)
315 			continue;
316 
317 		token = match_token(p, tokens, args);
318 		switch (token) {
319 		case Opt_subvol:
320 			*subvol_name = match_strdup(&args[0]);
321 			break;
322 		case Opt_device:
323 			error = btrfs_scan_one_device(match_strdup(&args[0]),
324 					flags, holder, fs_devices);
325 			if (error)
326 				goto out_free_opts;
327 			break;
328 		default:
329 			break;
330 		}
331 	}
332 
333  out_free_opts:
334 	kfree(opts);
335  out:
336 	/*
337 	 * If no subvolume name is specified we use the default one.  Allocate
338 	 * a copy of the string "." here so that code later in the
339 	 * mount path doesn't care if it's the default volume or another one.
340 	 */
341 	if (!*subvol_name) {
342 		*subvol_name = kstrdup(".", GFP_KERNEL);
343 		if (!*subvol_name)
344 			return -ENOMEM;
345 	}
346 	return error;
347 }
348 
349 static int btrfs_fill_super(struct super_block *sb,
350 			    struct btrfs_fs_devices *fs_devices,
351 			    void *data, int silent)
352 {
353 	struct inode *inode;
354 	struct dentry *root_dentry;
355 	struct btrfs_super_block *disk_super;
356 	struct btrfs_root *tree_root;
357 	struct btrfs_key key;
358 	int err;
359 
360 	sb->s_maxbytes = MAX_LFS_FILESIZE;
361 	sb->s_magic = BTRFS_SUPER_MAGIC;
362 	sb->s_op = &btrfs_super_ops;
363 	sb->s_export_op = &btrfs_export_ops;
364 	sb->s_xattr = btrfs_xattr_handlers;
365 	sb->s_time_gran = 1;
366 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
367 	sb->s_flags |= MS_POSIXACL;
368 #endif
369 
370 	tree_root = open_ctree(sb, fs_devices, (char *)data);
371 
372 	if (IS_ERR(tree_root)) {
373 		printk("btrfs: open_ctree failed\n");
374 		return PTR_ERR(tree_root);
375 	}
376 	sb->s_fs_info = tree_root;
377 	disk_super = &tree_root->fs_info->super_copy;
378 
379 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
380 	key.type = BTRFS_INODE_ITEM_KEY;
381 	key.offset = 0;
382 	inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root);
383 	if (IS_ERR(inode)) {
384 		err = PTR_ERR(inode);
385 		goto fail_close;
386 	}
387 
388 	root_dentry = d_alloc_root(inode);
389 	if (!root_dentry) {
390 		iput(inode);
391 		err = -ENOMEM;
392 		goto fail_close;
393 	}
394 #if 0
395 	/* this does the super kobj at the same time */
396 	err = btrfs_sysfs_add_super(tree_root->fs_info);
397 	if (err)
398 		goto fail_close;
399 #endif
400 
401 	sb->s_root = root_dentry;
402 
403 	save_mount_options(sb, data);
404 	return 0;
405 
406 fail_close:
407 	close_ctree(tree_root);
408 	return err;
409 }
410 
411 int btrfs_sync_fs(struct super_block *sb, int wait)
412 {
413 	struct btrfs_trans_handle *trans;
414 	struct btrfs_root *root = btrfs_sb(sb);
415 	int ret;
416 
417 	if (!wait) {
418 		filemap_flush(root->fs_info->btree_inode->i_mapping);
419 		return 0;
420 	}
421 
422 	btrfs_start_delalloc_inodes(root, 0);
423 	btrfs_wait_ordered_extents(root, 0, 0);
424 
425 	trans = btrfs_start_transaction(root, 1);
426 	ret = btrfs_commit_transaction(trans, root);
427 	return ret;
428 }
429 
430 static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
431 {
432 	struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
433 	struct btrfs_fs_info *info = root->fs_info;
434 
435 	if (btrfs_test_opt(root, DEGRADED))
436 		seq_puts(seq, ",degraded");
437 	if (btrfs_test_opt(root, NODATASUM))
438 		seq_puts(seq, ",nodatasum");
439 	if (btrfs_test_opt(root, NODATACOW))
440 		seq_puts(seq, ",nodatacow");
441 	if (btrfs_test_opt(root, NOBARRIER))
442 		seq_puts(seq, ",nobarrier");
443 	if (info->max_extent != (u64)-1)
444 		seq_printf(seq, ",max_extent=%llu",
445 			   (unsigned long long)info->max_extent);
446 	if (info->max_inline != 8192 * 1024)
447 		seq_printf(seq, ",max_inline=%llu",
448 			   (unsigned long long)info->max_inline);
449 	if (info->alloc_start != 0)
450 		seq_printf(seq, ",alloc_start=%llu",
451 			   (unsigned long long)info->alloc_start);
452 	if (info->thread_pool_size !=  min_t(unsigned long,
453 					     num_online_cpus() + 2, 8))
454 		seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
455 	if (btrfs_test_opt(root, COMPRESS))
456 		seq_puts(seq, ",compress");
457 	if (btrfs_test_opt(root, NOSSD))
458 		seq_puts(seq, ",nossd");
459 	if (btrfs_test_opt(root, SSD_SPREAD))
460 		seq_puts(seq, ",ssd_spread");
461 	else if (btrfs_test_opt(root, SSD))
462 		seq_puts(seq, ",ssd");
463 	if (btrfs_test_opt(root, NOTREELOG))
464 		seq_puts(seq, ",notreelog");
465 	if (btrfs_test_opt(root, FLUSHONCOMMIT))
466 		seq_puts(seq, ",flushoncommit");
467 	if (btrfs_test_opt(root, DISCARD))
468 		seq_puts(seq, ",discard");
469 	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
470 		seq_puts(seq, ",noacl");
471 	return 0;
472 }
473 
474 static int btrfs_test_super(struct super_block *s, void *data)
475 {
476 	struct btrfs_fs_devices *test_fs_devices = data;
477 	struct btrfs_root *root = btrfs_sb(s);
478 
479 	return root->fs_info->fs_devices == test_fs_devices;
480 }
481 
482 /*
483  * Find a superblock for the given device / mount point.
484  *
485  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
486  *	  for multiple device setup.  Make sure to keep it in sync.
487  */
488 static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
489 		const char *dev_name, void *data, struct vfsmount *mnt)
490 {
491 	char *subvol_name = NULL;
492 	struct block_device *bdev = NULL;
493 	struct super_block *s;
494 	struct dentry *root;
495 	struct btrfs_fs_devices *fs_devices = NULL;
496 	fmode_t mode = FMODE_READ;
497 	int error = 0;
498 
499 	if (!(flags & MS_RDONLY))
500 		mode |= FMODE_WRITE;
501 
502 	error = btrfs_parse_early_options(data, mode, fs_type,
503 					  &subvol_name, &fs_devices);
504 	if (error)
505 		return error;
506 
507 	error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
508 	if (error)
509 		goto error_free_subvol_name;
510 
511 	error = btrfs_open_devices(fs_devices, mode, fs_type);
512 	if (error)
513 		goto error_free_subvol_name;
514 
515 	if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
516 		error = -EACCES;
517 		goto error_close_devices;
518 	}
519 
520 	bdev = fs_devices->latest_bdev;
521 	s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
522 	if (IS_ERR(s))
523 		goto error_s;
524 
525 	if (s->s_root) {
526 		if ((flags ^ s->s_flags) & MS_RDONLY) {
527 			deactivate_locked_super(s);
528 			error = -EBUSY;
529 			goto error_close_devices;
530 		}
531 
532 		btrfs_close_devices(fs_devices);
533 	} else {
534 		char b[BDEVNAME_SIZE];
535 
536 		s->s_flags = flags;
537 		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
538 		error = btrfs_fill_super(s, fs_devices, data,
539 					 flags & MS_SILENT ? 1 : 0);
540 		if (error) {
541 			deactivate_locked_super(s);
542 			goto error_free_subvol_name;
543 		}
544 
545 		btrfs_sb(s)->fs_info->bdev_holder = fs_type;
546 		s->s_flags |= MS_ACTIVE;
547 	}
548 
549 	if (!strcmp(subvol_name, "."))
550 		root = dget(s->s_root);
551 	else {
552 		mutex_lock(&s->s_root->d_inode->i_mutex);
553 		root = lookup_one_len(subvol_name, s->s_root,
554 				      strlen(subvol_name));
555 		mutex_unlock(&s->s_root->d_inode->i_mutex);
556 
557 		if (IS_ERR(root)) {
558 			deactivate_locked_super(s);
559 			error = PTR_ERR(root);
560 			goto error_free_subvol_name;
561 		}
562 		if (!root->d_inode) {
563 			dput(root);
564 			deactivate_locked_super(s);
565 			error = -ENXIO;
566 			goto error_free_subvol_name;
567 		}
568 	}
569 
570 	mnt->mnt_sb = s;
571 	mnt->mnt_root = root;
572 
573 	kfree(subvol_name);
574 	return 0;
575 
576 error_s:
577 	error = PTR_ERR(s);
578 error_close_devices:
579 	btrfs_close_devices(fs_devices);
580 error_free_subvol_name:
581 	kfree(subvol_name);
582 	return error;
583 }
584 
585 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
586 {
587 	struct btrfs_root *root = btrfs_sb(sb);
588 	int ret;
589 
590 	ret = btrfs_parse_options(root, data);
591 	if (ret)
592 		return -EINVAL;
593 
594 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
595 		return 0;
596 
597 	if (*flags & MS_RDONLY) {
598 		sb->s_flags |= MS_RDONLY;
599 
600 		ret =  btrfs_commit_super(root);
601 		WARN_ON(ret);
602 	} else {
603 		if (root->fs_info->fs_devices->rw_devices == 0)
604 			return -EACCES;
605 
606 		if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
607 			return -EINVAL;
608 
609 		/* recover relocation */
610 		ret = btrfs_recover_relocation(root);
611 		WARN_ON(ret);
612 
613 		ret = btrfs_cleanup_fs_roots(root->fs_info);
614 		WARN_ON(ret);
615 
616 		sb->s_flags &= ~MS_RDONLY;
617 	}
618 
619 	return 0;
620 }
621 
622 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
623 {
624 	struct btrfs_root *root = btrfs_sb(dentry->d_sb);
625 	struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
626 	int bits = dentry->d_sb->s_blocksize_bits;
627 	__be32 *fsid = (__be32 *)root->fs_info->fsid;
628 
629 	buf->f_namelen = BTRFS_NAME_LEN;
630 	buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
631 	buf->f_bfree = buf->f_blocks -
632 		(btrfs_super_bytes_used(disk_super) >> bits);
633 	buf->f_bavail = buf->f_bfree;
634 	buf->f_bsize = dentry->d_sb->s_blocksize;
635 	buf->f_type = BTRFS_SUPER_MAGIC;
636 
637 	/* We treat it as constant endianness (it doesn't matter _which_)
638 	   because we want the fsid to come out the same whether mounted
639 	   on a big-endian or little-endian host */
640 	buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
641 	buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
642 	/* Mask in the root object ID too, to disambiguate subvols */
643 	buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
644 	buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
645 
646 	return 0;
647 }
648 
649 static struct file_system_type btrfs_fs_type = {
650 	.owner		= THIS_MODULE,
651 	.name		= "btrfs",
652 	.get_sb		= btrfs_get_sb,
653 	.kill_sb	= kill_anon_super,
654 	.fs_flags	= FS_REQUIRES_DEV,
655 };
656 
657 /*
658  * used by btrfsctl to scan devices when no FS is mounted
659  */
660 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
661 				unsigned long arg)
662 {
663 	struct btrfs_ioctl_vol_args *vol;
664 	struct btrfs_fs_devices *fs_devices;
665 	int ret = -ENOTTY;
666 
667 	if (!capable(CAP_SYS_ADMIN))
668 		return -EPERM;
669 
670 	vol = memdup_user((void __user *)arg, sizeof(*vol));
671 	if (IS_ERR(vol))
672 		return PTR_ERR(vol);
673 
674 	switch (cmd) {
675 	case BTRFS_IOC_SCAN_DEV:
676 		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
677 					    &btrfs_fs_type, &fs_devices);
678 		break;
679 	}
680 
681 	kfree(vol);
682 	return ret;
683 }
684 
685 static int btrfs_freeze(struct super_block *sb)
686 {
687 	struct btrfs_root *root = btrfs_sb(sb);
688 	mutex_lock(&root->fs_info->transaction_kthread_mutex);
689 	mutex_lock(&root->fs_info->cleaner_mutex);
690 	return 0;
691 }
692 
693 static int btrfs_unfreeze(struct super_block *sb)
694 {
695 	struct btrfs_root *root = btrfs_sb(sb);
696 	mutex_unlock(&root->fs_info->cleaner_mutex);
697 	mutex_unlock(&root->fs_info->transaction_kthread_mutex);
698 	return 0;
699 }
700 
701 static const struct super_operations btrfs_super_ops = {
702 	.drop_inode	= btrfs_drop_inode,
703 	.delete_inode	= btrfs_delete_inode,
704 	.put_super	= btrfs_put_super,
705 	.sync_fs	= btrfs_sync_fs,
706 	.show_options	= btrfs_show_options,
707 	.write_inode	= btrfs_write_inode,
708 	.dirty_inode	= btrfs_dirty_inode,
709 	.alloc_inode	= btrfs_alloc_inode,
710 	.destroy_inode	= btrfs_destroy_inode,
711 	.statfs		= btrfs_statfs,
712 	.remount_fs	= btrfs_remount,
713 	.freeze_fs	= btrfs_freeze,
714 	.unfreeze_fs	= btrfs_unfreeze,
715 };
716 
717 static const struct file_operations btrfs_ctl_fops = {
718 	.unlocked_ioctl	 = btrfs_control_ioctl,
719 	.compat_ioctl = btrfs_control_ioctl,
720 	.owner	 = THIS_MODULE,
721 };
722 
723 static struct miscdevice btrfs_misc = {
724 	.minor		= MISC_DYNAMIC_MINOR,
725 	.name		= "btrfs-control",
726 	.fops		= &btrfs_ctl_fops
727 };
728 
729 static int btrfs_interface_init(void)
730 {
731 	return misc_register(&btrfs_misc);
732 }
733 
734 static void btrfs_interface_exit(void)
735 {
736 	if (misc_deregister(&btrfs_misc) < 0)
737 		printk(KERN_INFO "misc_deregister failed for control device");
738 }
739 
740 static int __init init_btrfs_fs(void)
741 {
742 	int err;
743 
744 	err = btrfs_init_sysfs();
745 	if (err)
746 		return err;
747 
748 	err = btrfs_init_cachep();
749 	if (err)
750 		goto free_sysfs;
751 
752 	err = extent_io_init();
753 	if (err)
754 		goto free_cachep;
755 
756 	err = extent_map_init();
757 	if (err)
758 		goto free_extent_io;
759 
760 	err = btrfs_interface_init();
761 	if (err)
762 		goto free_extent_map;
763 
764 	err = register_filesystem(&btrfs_fs_type);
765 	if (err)
766 		goto unregister_ioctl;
767 
768 	printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
769 	return 0;
770 
771 unregister_ioctl:
772 	btrfs_interface_exit();
773 free_extent_map:
774 	extent_map_exit();
775 free_extent_io:
776 	extent_io_exit();
777 free_cachep:
778 	btrfs_destroy_cachep();
779 free_sysfs:
780 	btrfs_exit_sysfs();
781 	return err;
782 }
783 
784 static void __exit exit_btrfs_fs(void)
785 {
786 	btrfs_destroy_cachep();
787 	extent_map_exit();
788 	extent_io_exit();
789 	btrfs_interface_exit();
790 	unregister_filesystem(&btrfs_fs_type);
791 	btrfs_exit_sysfs();
792 	btrfs_cleanup_fs_uuids();
793 	btrfs_zlib_exit();
794 }
795 
796 module_init(init_btrfs_fs)
797 module_exit(exit_btrfs_fs)
798 
799 MODULE_LICENSE("GPL");
800