xref: /openbmc/linux/fs/btrfs/super.c (revision 4161b450)
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 <linux/cleancache.h>
43 #include <linux/ratelimit.h>
44 #include <linux/btrfs.h>
45 #include "delayed-inode.h"
46 #include "ctree.h"
47 #include "disk-io.h"
48 #include "transaction.h"
49 #include "btrfs_inode.h"
50 #include "print-tree.h"
51 #include "hash.h"
52 #include "props.h"
53 #include "xattr.h"
54 #include "volumes.h"
55 #include "export.h"
56 #include "compression.h"
57 #include "rcu-string.h"
58 #include "dev-replace.h"
59 #include "free-space-cache.h"
60 #include "backref.h"
61 #include "tests/btrfs-tests.h"
62 
63 #include "qgroup.h"
64 #define CREATE_TRACE_POINTS
65 #include <trace/events/btrfs.h>
66 
67 static const struct super_operations btrfs_super_ops;
68 static struct file_system_type btrfs_fs_type;
69 
70 static int btrfs_remount(struct super_block *sb, int *flags, char *data);
71 
72 static const char *btrfs_decode_error(int errno)
73 {
74 	char *errstr = "unknown";
75 
76 	switch (errno) {
77 	case -EIO:
78 		errstr = "IO failure";
79 		break;
80 	case -ENOMEM:
81 		errstr = "Out of memory";
82 		break;
83 	case -EROFS:
84 		errstr = "Readonly filesystem";
85 		break;
86 	case -EEXIST:
87 		errstr = "Object already exists";
88 		break;
89 	case -ENOSPC:
90 		errstr = "No space left";
91 		break;
92 	case -ENOENT:
93 		errstr = "No such entry";
94 		break;
95 	}
96 
97 	return errstr;
98 }
99 
100 static void save_error_info(struct btrfs_fs_info *fs_info)
101 {
102 	/*
103 	 * today we only save the error info into ram.  Long term we'll
104 	 * also send it down to the disk
105 	 */
106 	set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
107 }
108 
109 /* btrfs handle error by forcing the filesystem readonly */
110 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
111 {
112 	struct super_block *sb = fs_info->sb;
113 
114 	if (sb->s_flags & MS_RDONLY)
115 		return;
116 
117 	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
118 		sb->s_flags |= MS_RDONLY;
119 		btrfs_info(fs_info, "forced readonly");
120 		/*
121 		 * Note that a running device replace operation is not
122 		 * canceled here although there is no way to update
123 		 * the progress. It would add the risk of a deadlock,
124 		 * therefore the canceling is ommited. The only penalty
125 		 * is that some I/O remains active until the procedure
126 		 * completes. The next time when the filesystem is
127 		 * mounted writeable again, the device replace
128 		 * operation continues.
129 		 */
130 	}
131 }
132 
133 #ifdef CONFIG_PRINTK
134 /*
135  * __btrfs_std_error decodes expected errors from the caller and
136  * invokes the approciate error response.
137  */
138 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
139 		       unsigned int line, int errno, const char *fmt, ...)
140 {
141 	struct super_block *sb = fs_info->sb;
142 	const char *errstr;
143 
144 	/*
145 	 * Special case: if the error is EROFS, and we're already
146 	 * under MS_RDONLY, then it is safe here.
147 	 */
148 	if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
149   		return;
150 
151 	errstr = btrfs_decode_error(errno);
152 	if (fmt) {
153 		struct va_format vaf;
154 		va_list args;
155 
156 		va_start(args, fmt);
157 		vaf.fmt = fmt;
158 		vaf.va = &args;
159 
160 		printk(KERN_CRIT
161 			"BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
162 			sb->s_id, function, line, errno, errstr, &vaf);
163 		va_end(args);
164 	} else {
165 		printk(KERN_CRIT "BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
166 			sb->s_id, function, line, errno, errstr);
167 	}
168 
169 	/* Don't go through full error handling during mount */
170 	save_error_info(fs_info);
171 	if (sb->s_flags & MS_BORN)
172 		btrfs_handle_error(fs_info);
173 }
174 
175 static const char * const logtypes[] = {
176 	"emergency",
177 	"alert",
178 	"critical",
179 	"error",
180 	"warning",
181 	"notice",
182 	"info",
183 	"debug",
184 };
185 
186 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
187 {
188 	struct super_block *sb = fs_info->sb;
189 	char lvl[4];
190 	struct va_format vaf;
191 	va_list args;
192 	const char *type = logtypes[4];
193 	int kern_level;
194 
195 	va_start(args, fmt);
196 
197 	kern_level = printk_get_level(fmt);
198 	if (kern_level) {
199 		size_t size = printk_skip_level(fmt) - fmt;
200 		memcpy(lvl, fmt,  size);
201 		lvl[size] = '\0';
202 		fmt += size;
203 		type = logtypes[kern_level - '0'];
204 	} else
205 		*lvl = '\0';
206 
207 	vaf.fmt = fmt;
208 	vaf.va = &args;
209 
210 	printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
211 
212 	va_end(args);
213 }
214 
215 #else
216 
217 void __btrfs_std_error(struct btrfs_fs_info *fs_info, const char *function,
218 		       unsigned int line, int errno, const char *fmt, ...)
219 {
220 	struct super_block *sb = fs_info->sb;
221 
222 	/*
223 	 * Special case: if the error is EROFS, and we're already
224 	 * under MS_RDONLY, then it is safe here.
225 	 */
226 	if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
227 		return;
228 
229 	/* Don't go through full error handling during mount */
230 	if (sb->s_flags & MS_BORN) {
231 		save_error_info(fs_info);
232 		btrfs_handle_error(fs_info);
233 	}
234 }
235 #endif
236 
237 /*
238  * We only mark the transaction aborted and then set the file system read-only.
239  * This will prevent new transactions from starting or trying to join this
240  * one.
241  *
242  * This means that error recovery at the call site is limited to freeing
243  * any local memory allocations and passing the error code up without
244  * further cleanup. The transaction should complete as it normally would
245  * in the call path but will return -EIO.
246  *
247  * We'll complete the cleanup in btrfs_end_transaction and
248  * btrfs_commit_transaction.
249  */
250 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
251 			       struct btrfs_root *root, const char *function,
252 			       unsigned int line, int errno)
253 {
254 	/*
255 	 * Report first abort since mount
256 	 */
257 	if (!test_and_set_bit(BTRFS_FS_STATE_TRANS_ABORTED,
258 				&root->fs_info->fs_state)) {
259 		WARN(1, KERN_DEBUG "BTRFS: Transaction aborted (error %d)\n",
260 				errno);
261 	}
262 	trans->aborted = errno;
263 	/* Nothing used. The other threads that have joined this
264 	 * transaction may be able to continue. */
265 	if (!trans->blocks_used && list_empty(&trans->new_bgs)) {
266 		const char *errstr;
267 
268 		errstr = btrfs_decode_error(errno);
269 		btrfs_warn(root->fs_info,
270 		           "%s:%d: Aborting unused transaction(%s).",
271 		           function, line, errstr);
272 		return;
273 	}
274 	ACCESS_ONCE(trans->transaction->aborted) = errno;
275 	/* Wake up anybody who may be waiting on this transaction */
276 	wake_up(&root->fs_info->transaction_wait);
277 	wake_up(&root->fs_info->transaction_blocked_wait);
278 	__btrfs_std_error(root->fs_info, function, line, errno, NULL);
279 }
280 /*
281  * __btrfs_panic decodes unexpected, fatal errors from the caller,
282  * issues an alert, and either panics or BUGs, depending on mount options.
283  */
284 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
285 		   unsigned int line, int errno, const char *fmt, ...)
286 {
287 	char *s_id = "<unknown>";
288 	const char *errstr;
289 	struct va_format vaf = { .fmt = fmt };
290 	va_list args;
291 
292 	if (fs_info)
293 		s_id = fs_info->sb->s_id;
294 
295 	va_start(args, fmt);
296 	vaf.va = &args;
297 
298 	errstr = btrfs_decode_error(errno);
299 	if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
300 		panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
301 			s_id, function, line, &vaf, errno, errstr);
302 
303 	btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
304 		   function, line, &vaf, errno, errstr);
305 	va_end(args);
306 	/* Caller calls BUG() */
307 }
308 
309 static void btrfs_put_super(struct super_block *sb)
310 {
311 	close_ctree(btrfs_sb(sb)->tree_root);
312 }
313 
314 enum {
315 	Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
316 	Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
317 	Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
318 	Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
319 	Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
320 	Opt_space_cache, Opt_clear_cache, Opt_user_subvol_rm_allowed,
321 	Opt_enospc_debug, Opt_subvolrootid, Opt_defrag, Opt_inode_cache,
322 	Opt_no_space_cache, Opt_recovery, Opt_skip_balance,
323 	Opt_check_integrity, Opt_check_integrity_including_extent_data,
324 	Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
325 	Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
326 	Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
327 	Opt_datasum, Opt_treelog, Opt_noinode_cache,
328 	Opt_err,
329 };
330 
331 static match_table_t tokens = {
332 	{Opt_degraded, "degraded"},
333 	{Opt_subvol, "subvol=%s"},
334 	{Opt_subvolid, "subvolid=%s"},
335 	{Opt_device, "device=%s"},
336 	{Opt_nodatasum, "nodatasum"},
337 	{Opt_datasum, "datasum"},
338 	{Opt_nodatacow, "nodatacow"},
339 	{Opt_datacow, "datacow"},
340 	{Opt_nobarrier, "nobarrier"},
341 	{Opt_barrier, "barrier"},
342 	{Opt_max_inline, "max_inline=%s"},
343 	{Opt_alloc_start, "alloc_start=%s"},
344 	{Opt_thread_pool, "thread_pool=%d"},
345 	{Opt_compress, "compress"},
346 	{Opt_compress_type, "compress=%s"},
347 	{Opt_compress_force, "compress-force"},
348 	{Opt_compress_force_type, "compress-force=%s"},
349 	{Opt_ssd, "ssd"},
350 	{Opt_ssd_spread, "ssd_spread"},
351 	{Opt_nossd, "nossd"},
352 	{Opt_acl, "acl"},
353 	{Opt_noacl, "noacl"},
354 	{Opt_notreelog, "notreelog"},
355 	{Opt_treelog, "treelog"},
356 	{Opt_flushoncommit, "flushoncommit"},
357 	{Opt_noflushoncommit, "noflushoncommit"},
358 	{Opt_ratio, "metadata_ratio=%d"},
359 	{Opt_discard, "discard"},
360 	{Opt_nodiscard, "nodiscard"},
361 	{Opt_space_cache, "space_cache"},
362 	{Opt_clear_cache, "clear_cache"},
363 	{Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
364 	{Opt_enospc_debug, "enospc_debug"},
365 	{Opt_noenospc_debug, "noenospc_debug"},
366 	{Opt_subvolrootid, "subvolrootid=%d"},
367 	{Opt_defrag, "autodefrag"},
368 	{Opt_nodefrag, "noautodefrag"},
369 	{Opt_inode_cache, "inode_cache"},
370 	{Opt_noinode_cache, "noinode_cache"},
371 	{Opt_no_space_cache, "nospace_cache"},
372 	{Opt_recovery, "recovery"},
373 	{Opt_skip_balance, "skip_balance"},
374 	{Opt_check_integrity, "check_int"},
375 	{Opt_check_integrity_including_extent_data, "check_int_data"},
376 	{Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
377 	{Opt_rescan_uuid_tree, "rescan_uuid_tree"},
378 	{Opt_fatal_errors, "fatal_errors=%s"},
379 	{Opt_commit_interval, "commit=%d"},
380 	{Opt_err, NULL},
381 };
382 
383 /*
384  * Regular mount options parser.  Everything that is needed only when
385  * reading in a new superblock is parsed here.
386  * XXX JDM: This needs to be cleaned up for remount.
387  */
388 int btrfs_parse_options(struct btrfs_root *root, char *options)
389 {
390 	struct btrfs_fs_info *info = root->fs_info;
391 	substring_t args[MAX_OPT_ARGS];
392 	char *p, *num, *orig = NULL;
393 	u64 cache_gen;
394 	int intarg;
395 	int ret = 0;
396 	char *compress_type;
397 	bool compress_force = false;
398 
399 	cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
400 	if (cache_gen)
401 		btrfs_set_opt(info->mount_opt, SPACE_CACHE);
402 
403 	if (!options)
404 		goto out;
405 
406 	/*
407 	 * strsep changes the string, duplicate it because parse_options
408 	 * gets called twice
409 	 */
410 	options = kstrdup(options, GFP_NOFS);
411 	if (!options)
412 		return -ENOMEM;
413 
414 	orig = options;
415 
416 	while ((p = strsep(&options, ",")) != NULL) {
417 		int token;
418 		if (!*p)
419 			continue;
420 
421 		token = match_token(p, tokens, args);
422 		switch (token) {
423 		case Opt_degraded:
424 			btrfs_info(root->fs_info, "allowing degraded mounts");
425 			btrfs_set_opt(info->mount_opt, DEGRADED);
426 			break;
427 		case Opt_subvol:
428 		case Opt_subvolid:
429 		case Opt_subvolrootid:
430 		case Opt_device:
431 			/*
432 			 * These are parsed by btrfs_parse_early_options
433 			 * and can be happily ignored here.
434 			 */
435 			break;
436 		case Opt_nodatasum:
437 			btrfs_set_and_info(root, NODATASUM,
438 					   "setting nodatasum");
439 			break;
440 		case Opt_datasum:
441 			if (btrfs_test_opt(root, NODATASUM)) {
442 				if (btrfs_test_opt(root, NODATACOW))
443 					btrfs_info(root->fs_info, "setting datasum, datacow enabled");
444 				else
445 					btrfs_info(root->fs_info, "setting datasum");
446 			}
447 			btrfs_clear_opt(info->mount_opt, NODATACOW);
448 			btrfs_clear_opt(info->mount_opt, NODATASUM);
449 			break;
450 		case Opt_nodatacow:
451 			if (!btrfs_test_opt(root, NODATACOW)) {
452 				if (!btrfs_test_opt(root, COMPRESS) ||
453 				    !btrfs_test_opt(root, FORCE_COMPRESS)) {
454 					btrfs_info(root->fs_info,
455 						   "setting nodatacow, compression disabled");
456 				} else {
457 					btrfs_info(root->fs_info, "setting nodatacow");
458 				}
459 			}
460 			btrfs_clear_opt(info->mount_opt, COMPRESS);
461 			btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
462 			btrfs_set_opt(info->mount_opt, NODATACOW);
463 			btrfs_set_opt(info->mount_opt, NODATASUM);
464 			break;
465 		case Opt_datacow:
466 			btrfs_clear_and_info(root, NODATACOW,
467 					     "setting datacow");
468 			break;
469 		case Opt_compress_force:
470 		case Opt_compress_force_type:
471 			compress_force = true;
472 			/* Fallthrough */
473 		case Opt_compress:
474 		case Opt_compress_type:
475 			if (token == Opt_compress ||
476 			    token == Opt_compress_force ||
477 			    strcmp(args[0].from, "zlib") == 0) {
478 				compress_type = "zlib";
479 				info->compress_type = BTRFS_COMPRESS_ZLIB;
480 				btrfs_set_opt(info->mount_opt, COMPRESS);
481 				btrfs_clear_opt(info->mount_opt, NODATACOW);
482 				btrfs_clear_opt(info->mount_opt, NODATASUM);
483 			} else if (strcmp(args[0].from, "lzo") == 0) {
484 				compress_type = "lzo";
485 				info->compress_type = BTRFS_COMPRESS_LZO;
486 				btrfs_set_opt(info->mount_opt, COMPRESS);
487 				btrfs_clear_opt(info->mount_opt, NODATACOW);
488 				btrfs_clear_opt(info->mount_opt, NODATASUM);
489 				btrfs_set_fs_incompat(info, COMPRESS_LZO);
490 			} else if (strncmp(args[0].from, "no", 2) == 0) {
491 				compress_type = "no";
492 				btrfs_clear_opt(info->mount_opt, COMPRESS);
493 				btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
494 				compress_force = false;
495 			} else {
496 				ret = -EINVAL;
497 				goto out;
498 			}
499 
500 			if (compress_force) {
501 				btrfs_set_and_info(root, FORCE_COMPRESS,
502 						   "force %s compression",
503 						   compress_type);
504 			} else {
505 				if (!btrfs_test_opt(root, COMPRESS))
506 					btrfs_info(root->fs_info,
507 						   "btrfs: use %s compression",
508 						   compress_type);
509 				/*
510 				 * If we remount from compress-force=xxx to
511 				 * compress=xxx, we need clear FORCE_COMPRESS
512 				 * flag, otherwise, there is no way for users
513 				 * to disable forcible compression separately.
514 				 */
515 				btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
516 			}
517 			break;
518 		case Opt_ssd:
519 			btrfs_set_and_info(root, SSD,
520 					   "use ssd allocation scheme");
521 			break;
522 		case Opt_ssd_spread:
523 			btrfs_set_and_info(root, SSD_SPREAD,
524 					   "use spread ssd allocation scheme");
525 			btrfs_set_opt(info->mount_opt, SSD);
526 			break;
527 		case Opt_nossd:
528 			btrfs_set_and_info(root, NOSSD,
529 					     "not using ssd allocation scheme");
530 			btrfs_clear_opt(info->mount_opt, SSD);
531 			break;
532 		case Opt_barrier:
533 			btrfs_clear_and_info(root, NOBARRIER,
534 					     "turning on barriers");
535 			break;
536 		case Opt_nobarrier:
537 			btrfs_set_and_info(root, NOBARRIER,
538 					   "turning off barriers");
539 			break;
540 		case Opt_thread_pool:
541 			ret = match_int(&args[0], &intarg);
542 			if (ret) {
543 				goto out;
544 			} else if (intarg > 0) {
545 				info->thread_pool_size = intarg;
546 			} else {
547 				ret = -EINVAL;
548 				goto out;
549 			}
550 			break;
551 		case Opt_max_inline:
552 			num = match_strdup(&args[0]);
553 			if (num) {
554 				info->max_inline = memparse(num, NULL);
555 				kfree(num);
556 
557 				if (info->max_inline) {
558 					info->max_inline = min_t(u64,
559 						info->max_inline,
560 						root->sectorsize);
561 				}
562 				btrfs_info(root->fs_info, "max_inline at %llu",
563 					info->max_inline);
564 			} else {
565 				ret = -ENOMEM;
566 				goto out;
567 			}
568 			break;
569 		case Opt_alloc_start:
570 			num = match_strdup(&args[0]);
571 			if (num) {
572 				mutex_lock(&info->chunk_mutex);
573 				info->alloc_start = memparse(num, NULL);
574 				mutex_unlock(&info->chunk_mutex);
575 				kfree(num);
576 				btrfs_info(root->fs_info, "allocations start at %llu",
577 					info->alloc_start);
578 			} else {
579 				ret = -ENOMEM;
580 				goto out;
581 			}
582 			break;
583 		case Opt_acl:
584 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
585 			root->fs_info->sb->s_flags |= MS_POSIXACL;
586 			break;
587 #else
588 			btrfs_err(root->fs_info,
589 				"support for ACL not compiled in!");
590 			ret = -EINVAL;
591 			goto out;
592 #endif
593 		case Opt_noacl:
594 			root->fs_info->sb->s_flags &= ~MS_POSIXACL;
595 			break;
596 		case Opt_notreelog:
597 			btrfs_set_and_info(root, NOTREELOG,
598 					   "disabling tree log");
599 			break;
600 		case Opt_treelog:
601 			btrfs_clear_and_info(root, NOTREELOG,
602 					     "enabling tree log");
603 			break;
604 		case Opt_flushoncommit:
605 			btrfs_set_and_info(root, FLUSHONCOMMIT,
606 					   "turning on flush-on-commit");
607 			break;
608 		case Opt_noflushoncommit:
609 			btrfs_clear_and_info(root, FLUSHONCOMMIT,
610 					     "turning off flush-on-commit");
611 			break;
612 		case Opt_ratio:
613 			ret = match_int(&args[0], &intarg);
614 			if (ret) {
615 				goto out;
616 			} else if (intarg >= 0) {
617 				info->metadata_ratio = intarg;
618 				btrfs_info(root->fs_info, "metadata ratio %d",
619 				       info->metadata_ratio);
620 			} else {
621 				ret = -EINVAL;
622 				goto out;
623 			}
624 			break;
625 		case Opt_discard:
626 			btrfs_set_and_info(root, DISCARD,
627 					   "turning on discard");
628 			break;
629 		case Opt_nodiscard:
630 			btrfs_clear_and_info(root, DISCARD,
631 					     "turning off discard");
632 			break;
633 		case Opt_space_cache:
634 			btrfs_set_and_info(root, SPACE_CACHE,
635 					   "enabling disk space caching");
636 			break;
637 		case Opt_rescan_uuid_tree:
638 			btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
639 			break;
640 		case Opt_no_space_cache:
641 			btrfs_clear_and_info(root, SPACE_CACHE,
642 					     "disabling disk space caching");
643 			break;
644 		case Opt_inode_cache:
645 			btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
646 					   "enabling inode map caching");
647 			break;
648 		case Opt_noinode_cache:
649 			btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
650 					     "disabling inode map caching");
651 			break;
652 		case Opt_clear_cache:
653 			btrfs_set_and_info(root, CLEAR_CACHE,
654 					   "force clearing of disk cache");
655 			break;
656 		case Opt_user_subvol_rm_allowed:
657 			btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
658 			break;
659 		case Opt_enospc_debug:
660 			btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
661 			break;
662 		case Opt_noenospc_debug:
663 			btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
664 			break;
665 		case Opt_defrag:
666 			btrfs_set_and_info(root, AUTO_DEFRAG,
667 					   "enabling auto defrag");
668 			break;
669 		case Opt_nodefrag:
670 			btrfs_clear_and_info(root, AUTO_DEFRAG,
671 					     "disabling auto defrag");
672 			break;
673 		case Opt_recovery:
674 			btrfs_info(root->fs_info, "enabling auto recovery");
675 			btrfs_set_opt(info->mount_opt, RECOVERY);
676 			break;
677 		case Opt_skip_balance:
678 			btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
679 			break;
680 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
681 		case Opt_check_integrity_including_extent_data:
682 			btrfs_info(root->fs_info,
683 				   "enabling check integrity including extent data");
684 			btrfs_set_opt(info->mount_opt,
685 				      CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
686 			btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
687 			break;
688 		case Opt_check_integrity:
689 			btrfs_info(root->fs_info, "enabling check integrity");
690 			btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
691 			break;
692 		case Opt_check_integrity_print_mask:
693 			ret = match_int(&args[0], &intarg);
694 			if (ret) {
695 				goto out;
696 			} else if (intarg >= 0) {
697 				info->check_integrity_print_mask = intarg;
698 				btrfs_info(root->fs_info, "check_integrity_print_mask 0x%x",
699 				       info->check_integrity_print_mask);
700 			} else {
701 				ret = -EINVAL;
702 				goto out;
703 			}
704 			break;
705 #else
706 		case Opt_check_integrity_including_extent_data:
707 		case Opt_check_integrity:
708 		case Opt_check_integrity_print_mask:
709 			btrfs_err(root->fs_info,
710 				"support for check_integrity* not compiled in!");
711 			ret = -EINVAL;
712 			goto out;
713 #endif
714 		case Opt_fatal_errors:
715 			if (strcmp(args[0].from, "panic") == 0)
716 				btrfs_set_opt(info->mount_opt,
717 					      PANIC_ON_FATAL_ERROR);
718 			else if (strcmp(args[0].from, "bug") == 0)
719 				btrfs_clear_opt(info->mount_opt,
720 					      PANIC_ON_FATAL_ERROR);
721 			else {
722 				ret = -EINVAL;
723 				goto out;
724 			}
725 			break;
726 		case Opt_commit_interval:
727 			intarg = 0;
728 			ret = match_int(&args[0], &intarg);
729 			if (ret < 0) {
730 				btrfs_err(root->fs_info, "invalid commit interval");
731 				ret = -EINVAL;
732 				goto out;
733 			}
734 			if (intarg > 0) {
735 				if (intarg > 300) {
736 					btrfs_warn(root->fs_info, "excessive commit interval %d",
737 							intarg);
738 				}
739 				info->commit_interval = intarg;
740 			} else {
741 				btrfs_info(root->fs_info, "using default commit interval %ds",
742 				    BTRFS_DEFAULT_COMMIT_INTERVAL);
743 				info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
744 			}
745 			break;
746 		case Opt_err:
747 			btrfs_info(root->fs_info, "unrecognized mount option '%s'", p);
748 			ret = -EINVAL;
749 			goto out;
750 		default:
751 			break;
752 		}
753 	}
754 out:
755 	if (!ret && btrfs_test_opt(root, SPACE_CACHE))
756 		btrfs_info(root->fs_info, "disk space caching is enabled");
757 	kfree(orig);
758 	return ret;
759 }
760 
761 /*
762  * Parse mount options that are required early in the mount process.
763  *
764  * All other options will be parsed on much later in the mount process and
765  * only when we need to allocate a new super block.
766  */
767 static int btrfs_parse_early_options(const char *options, fmode_t flags,
768 		void *holder, char **subvol_name, u64 *subvol_objectid,
769 		struct btrfs_fs_devices **fs_devices)
770 {
771 	substring_t args[MAX_OPT_ARGS];
772 	char *device_name, *opts, *orig, *p;
773 	char *num = NULL;
774 	int error = 0;
775 
776 	if (!options)
777 		return 0;
778 
779 	/*
780 	 * strsep changes the string, duplicate it because parse_options
781 	 * gets called twice
782 	 */
783 	opts = kstrdup(options, GFP_KERNEL);
784 	if (!opts)
785 		return -ENOMEM;
786 	orig = opts;
787 
788 	while ((p = strsep(&opts, ",")) != NULL) {
789 		int token;
790 		if (!*p)
791 			continue;
792 
793 		token = match_token(p, tokens, args);
794 		switch (token) {
795 		case Opt_subvol:
796 			kfree(*subvol_name);
797 			*subvol_name = match_strdup(&args[0]);
798 			if (!*subvol_name) {
799 				error = -ENOMEM;
800 				goto out;
801 			}
802 			break;
803 		case Opt_subvolid:
804 			num = match_strdup(&args[0]);
805 			if (num) {
806 				*subvol_objectid = memparse(num, NULL);
807 				kfree(num);
808 				/* we want the original fs_tree */
809 				if (!*subvol_objectid)
810 					*subvol_objectid =
811 						BTRFS_FS_TREE_OBJECTID;
812 			} else {
813 				error = -EINVAL;
814 				goto out;
815 			}
816 			break;
817 		case Opt_subvolrootid:
818 			printk(KERN_WARNING
819 				"BTRFS: 'subvolrootid' mount option is deprecated and has "
820 				"no effect\n");
821 			break;
822 		case Opt_device:
823 			device_name = match_strdup(&args[0]);
824 			if (!device_name) {
825 				error = -ENOMEM;
826 				goto out;
827 			}
828 			error = btrfs_scan_one_device(device_name,
829 					flags, holder, fs_devices);
830 			kfree(device_name);
831 			if (error)
832 				goto out;
833 			break;
834 		default:
835 			break;
836 		}
837 	}
838 
839 out:
840 	kfree(orig);
841 	return error;
842 }
843 
844 static struct dentry *get_default_root(struct super_block *sb,
845 				       u64 subvol_objectid)
846 {
847 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
848 	struct btrfs_root *root = fs_info->tree_root;
849 	struct btrfs_root *new_root;
850 	struct btrfs_dir_item *di;
851 	struct btrfs_path *path;
852 	struct btrfs_key location;
853 	struct inode *inode;
854 	u64 dir_id;
855 	int new = 0;
856 
857 	/*
858 	 * We have a specific subvol we want to mount, just setup location and
859 	 * go look up the root.
860 	 */
861 	if (subvol_objectid) {
862 		location.objectid = subvol_objectid;
863 		location.type = BTRFS_ROOT_ITEM_KEY;
864 		location.offset = (u64)-1;
865 		goto find_root;
866 	}
867 
868 	path = btrfs_alloc_path();
869 	if (!path)
870 		return ERR_PTR(-ENOMEM);
871 	path->leave_spinning = 1;
872 
873 	/*
874 	 * Find the "default" dir item which points to the root item that we
875 	 * will mount by default if we haven't been given a specific subvolume
876 	 * to mount.
877 	 */
878 	dir_id = btrfs_super_root_dir(fs_info->super_copy);
879 	di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
880 	if (IS_ERR(di)) {
881 		btrfs_free_path(path);
882 		return ERR_CAST(di);
883 	}
884 	if (!di) {
885 		/*
886 		 * Ok the default dir item isn't there.  This is weird since
887 		 * it's always been there, but don't freak out, just try and
888 		 * mount to root most subvolume.
889 		 */
890 		btrfs_free_path(path);
891 		dir_id = BTRFS_FIRST_FREE_OBJECTID;
892 		new_root = fs_info->fs_root;
893 		goto setup_root;
894 	}
895 
896 	btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
897 	btrfs_free_path(path);
898 
899 find_root:
900 	new_root = btrfs_read_fs_root_no_name(fs_info, &location);
901 	if (IS_ERR(new_root))
902 		return ERR_CAST(new_root);
903 
904 	dir_id = btrfs_root_dirid(&new_root->root_item);
905 setup_root:
906 	location.objectid = dir_id;
907 	location.type = BTRFS_INODE_ITEM_KEY;
908 	location.offset = 0;
909 
910 	inode = btrfs_iget(sb, &location, new_root, &new);
911 	if (IS_ERR(inode))
912 		return ERR_CAST(inode);
913 
914 	/*
915 	 * If we're just mounting the root most subvol put the inode and return
916 	 * a reference to the dentry.  We will have already gotten a reference
917 	 * to the inode in btrfs_fill_super so we're good to go.
918 	 */
919 	if (!new && sb->s_root->d_inode == inode) {
920 		iput(inode);
921 		return dget(sb->s_root);
922 	}
923 
924 	return d_obtain_root(inode);
925 }
926 
927 static int btrfs_fill_super(struct super_block *sb,
928 			    struct btrfs_fs_devices *fs_devices,
929 			    void *data, int silent)
930 {
931 	struct inode *inode;
932 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
933 	struct btrfs_key key;
934 	int err;
935 
936 	sb->s_maxbytes = MAX_LFS_FILESIZE;
937 	sb->s_magic = BTRFS_SUPER_MAGIC;
938 	sb->s_op = &btrfs_super_ops;
939 	sb->s_d_op = &btrfs_dentry_operations;
940 	sb->s_export_op = &btrfs_export_ops;
941 	sb->s_xattr = btrfs_xattr_handlers;
942 	sb->s_time_gran = 1;
943 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
944 	sb->s_flags |= MS_POSIXACL;
945 #endif
946 	sb->s_flags |= MS_I_VERSION;
947 	err = open_ctree(sb, fs_devices, (char *)data);
948 	if (err) {
949 		printk(KERN_ERR "BTRFS: open_ctree failed\n");
950 		return err;
951 	}
952 
953 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
954 	key.type = BTRFS_INODE_ITEM_KEY;
955 	key.offset = 0;
956 	inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
957 	if (IS_ERR(inode)) {
958 		err = PTR_ERR(inode);
959 		goto fail_close;
960 	}
961 
962 	sb->s_root = d_make_root(inode);
963 	if (!sb->s_root) {
964 		err = -ENOMEM;
965 		goto fail_close;
966 	}
967 
968 	save_mount_options(sb, data);
969 	cleancache_init_fs(sb);
970 	sb->s_flags |= MS_ACTIVE;
971 	return 0;
972 
973 fail_close:
974 	close_ctree(fs_info->tree_root);
975 	return err;
976 }
977 
978 int btrfs_sync_fs(struct super_block *sb, int wait)
979 {
980 	struct btrfs_trans_handle *trans;
981 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
982 	struct btrfs_root *root = fs_info->tree_root;
983 
984 	trace_btrfs_sync_fs(wait);
985 
986 	if (!wait) {
987 		filemap_flush(fs_info->btree_inode->i_mapping);
988 		return 0;
989 	}
990 
991 	btrfs_wait_ordered_roots(fs_info, -1);
992 
993 	trans = btrfs_attach_transaction_barrier(root);
994 	if (IS_ERR(trans)) {
995 		/* no transaction, don't bother */
996 		if (PTR_ERR(trans) == -ENOENT) {
997 			/*
998 			 * Exit unless we have some pending changes
999 			 * that need to go through commit
1000 			 */
1001 			if (fs_info->pending_changes == 0)
1002 				return 0;
1003 			/*
1004 			 * A non-blocking test if the fs is frozen. We must not
1005 			 * start a new transaction here otherwise a deadlock
1006 			 * happens. The pending operations are delayed to the
1007 			 * next commit after thawing.
1008 			 */
1009 			if (__sb_start_write(sb, SB_FREEZE_WRITE, false))
1010 				__sb_end_write(sb, SB_FREEZE_WRITE);
1011 			else
1012 				return 0;
1013 			trans = btrfs_start_transaction(root, 0);
1014 		}
1015 		if (IS_ERR(trans))
1016 			return PTR_ERR(trans);
1017 	}
1018 	return btrfs_commit_transaction(trans, root);
1019 }
1020 
1021 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1022 {
1023 	struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1024 	struct btrfs_root *root = info->tree_root;
1025 	char *compress_type;
1026 
1027 	if (btrfs_test_opt(root, DEGRADED))
1028 		seq_puts(seq, ",degraded");
1029 	if (btrfs_test_opt(root, NODATASUM))
1030 		seq_puts(seq, ",nodatasum");
1031 	if (btrfs_test_opt(root, NODATACOW))
1032 		seq_puts(seq, ",nodatacow");
1033 	if (btrfs_test_opt(root, NOBARRIER))
1034 		seq_puts(seq, ",nobarrier");
1035 	if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1036 		seq_printf(seq, ",max_inline=%llu", info->max_inline);
1037 	if (info->alloc_start != 0)
1038 		seq_printf(seq, ",alloc_start=%llu", info->alloc_start);
1039 	if (info->thread_pool_size !=  min_t(unsigned long,
1040 					     num_online_cpus() + 2, 8))
1041 		seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
1042 	if (btrfs_test_opt(root, COMPRESS)) {
1043 		if (info->compress_type == BTRFS_COMPRESS_ZLIB)
1044 			compress_type = "zlib";
1045 		else
1046 			compress_type = "lzo";
1047 		if (btrfs_test_opt(root, FORCE_COMPRESS))
1048 			seq_printf(seq, ",compress-force=%s", compress_type);
1049 		else
1050 			seq_printf(seq, ",compress=%s", compress_type);
1051 	}
1052 	if (btrfs_test_opt(root, NOSSD))
1053 		seq_puts(seq, ",nossd");
1054 	if (btrfs_test_opt(root, SSD_SPREAD))
1055 		seq_puts(seq, ",ssd_spread");
1056 	else if (btrfs_test_opt(root, SSD))
1057 		seq_puts(seq, ",ssd");
1058 	if (btrfs_test_opt(root, NOTREELOG))
1059 		seq_puts(seq, ",notreelog");
1060 	if (btrfs_test_opt(root, FLUSHONCOMMIT))
1061 		seq_puts(seq, ",flushoncommit");
1062 	if (btrfs_test_opt(root, DISCARD))
1063 		seq_puts(seq, ",discard");
1064 	if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
1065 		seq_puts(seq, ",noacl");
1066 	if (btrfs_test_opt(root, SPACE_CACHE))
1067 		seq_puts(seq, ",space_cache");
1068 	else
1069 		seq_puts(seq, ",nospace_cache");
1070 	if (btrfs_test_opt(root, RESCAN_UUID_TREE))
1071 		seq_puts(seq, ",rescan_uuid_tree");
1072 	if (btrfs_test_opt(root, CLEAR_CACHE))
1073 		seq_puts(seq, ",clear_cache");
1074 	if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
1075 		seq_puts(seq, ",user_subvol_rm_allowed");
1076 	if (btrfs_test_opt(root, ENOSPC_DEBUG))
1077 		seq_puts(seq, ",enospc_debug");
1078 	if (btrfs_test_opt(root, AUTO_DEFRAG))
1079 		seq_puts(seq, ",autodefrag");
1080 	if (btrfs_test_opt(root, INODE_MAP_CACHE))
1081 		seq_puts(seq, ",inode_cache");
1082 	if (btrfs_test_opt(root, SKIP_BALANCE))
1083 		seq_puts(seq, ",skip_balance");
1084 	if (btrfs_test_opt(root, RECOVERY))
1085 		seq_puts(seq, ",recovery");
1086 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1087 	if (btrfs_test_opt(root, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1088 		seq_puts(seq, ",check_int_data");
1089 	else if (btrfs_test_opt(root, CHECK_INTEGRITY))
1090 		seq_puts(seq, ",check_int");
1091 	if (info->check_integrity_print_mask)
1092 		seq_printf(seq, ",check_int_print_mask=%d",
1093 				info->check_integrity_print_mask);
1094 #endif
1095 	if (info->metadata_ratio)
1096 		seq_printf(seq, ",metadata_ratio=%d",
1097 				info->metadata_ratio);
1098 	if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
1099 		seq_puts(seq, ",fatal_errors=panic");
1100 	if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1101 		seq_printf(seq, ",commit=%d", info->commit_interval);
1102 	return 0;
1103 }
1104 
1105 static int btrfs_test_super(struct super_block *s, void *data)
1106 {
1107 	struct btrfs_fs_info *p = data;
1108 	struct btrfs_fs_info *fs_info = btrfs_sb(s);
1109 
1110 	return fs_info->fs_devices == p->fs_devices;
1111 }
1112 
1113 static int btrfs_set_super(struct super_block *s, void *data)
1114 {
1115 	int err = set_anon_super(s, data);
1116 	if (!err)
1117 		s->s_fs_info = data;
1118 	return err;
1119 }
1120 
1121 /*
1122  * subvolumes are identified by ino 256
1123  */
1124 static inline int is_subvolume_inode(struct inode *inode)
1125 {
1126 	if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1127 		return 1;
1128 	return 0;
1129 }
1130 
1131 /*
1132  * This will strip out the subvol=%s argument for an argument string and add
1133  * subvolid=0 to make sure we get the actual tree root for path walking to the
1134  * subvol we want.
1135  */
1136 static char *setup_root_args(char *args)
1137 {
1138 	unsigned len = strlen(args) + 2 + 1;
1139 	char *src, *dst, *buf;
1140 
1141 	/*
1142 	 * We need the same args as before, but with this substitution:
1143 	 * s!subvol=[^,]+!subvolid=0!
1144 	 *
1145 	 * Since the replacement string is up to 2 bytes longer than the
1146 	 * original, allocate strlen(args) + 2 + 1 bytes.
1147 	 */
1148 
1149 	src = strstr(args, "subvol=");
1150 	/* This shouldn't happen, but just in case.. */
1151 	if (!src)
1152 		return NULL;
1153 
1154 	buf = dst = kmalloc(len, GFP_NOFS);
1155 	if (!buf)
1156 		return NULL;
1157 
1158 	/*
1159 	 * If the subvol= arg is not at the start of the string,
1160 	 * copy whatever precedes it into buf.
1161 	 */
1162 	if (src != args) {
1163 		*src++ = '\0';
1164 		strcpy(buf, args);
1165 		dst += strlen(args);
1166 	}
1167 
1168 	strcpy(dst, "subvolid=0");
1169 	dst += strlen("subvolid=0");
1170 
1171 	/*
1172 	 * If there is a "," after the original subvol=... string,
1173 	 * copy that suffix into our buffer.  Otherwise, we're done.
1174 	 */
1175 	src = strchr(src, ',');
1176 	if (src)
1177 		strcpy(dst, src);
1178 
1179 	return buf;
1180 }
1181 
1182 static struct dentry *mount_subvol(const char *subvol_name, int flags,
1183 				   const char *device_name, char *data)
1184 {
1185 	struct dentry *root;
1186 	struct vfsmount *mnt;
1187 	char *newargs;
1188 
1189 	newargs = setup_root_args(data);
1190 	if (!newargs)
1191 		return ERR_PTR(-ENOMEM);
1192 	mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name,
1193 			     newargs);
1194 
1195 	if (PTR_RET(mnt) == -EBUSY) {
1196 		if (flags & MS_RDONLY) {
1197 			mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY, device_name,
1198 					     newargs);
1199 		} else {
1200 			int r;
1201 			mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY, device_name,
1202 					     newargs);
1203 			if (IS_ERR(mnt)) {
1204 				kfree(newargs);
1205 				return ERR_CAST(mnt);
1206 			}
1207 
1208 			r = btrfs_remount(mnt->mnt_sb, &flags, NULL);
1209 			if (r < 0) {
1210 				/* FIXME: release vfsmount mnt ??*/
1211 				kfree(newargs);
1212 				return ERR_PTR(r);
1213 			}
1214 		}
1215 	}
1216 
1217 	kfree(newargs);
1218 
1219 	if (IS_ERR(mnt))
1220 		return ERR_CAST(mnt);
1221 
1222 	root = mount_subtree(mnt, subvol_name);
1223 
1224 	if (!IS_ERR(root) && !is_subvolume_inode(root->d_inode)) {
1225 		struct super_block *s = root->d_sb;
1226 		dput(root);
1227 		root = ERR_PTR(-EINVAL);
1228 		deactivate_locked_super(s);
1229 		printk(KERN_ERR "BTRFS: '%s' is not a valid subvolume\n",
1230 				subvol_name);
1231 	}
1232 
1233 	return root;
1234 }
1235 
1236 static int parse_security_options(char *orig_opts,
1237 				  struct security_mnt_opts *sec_opts)
1238 {
1239 	char *secdata = NULL;
1240 	int ret = 0;
1241 
1242 	secdata = alloc_secdata();
1243 	if (!secdata)
1244 		return -ENOMEM;
1245 	ret = security_sb_copy_data(orig_opts, secdata);
1246 	if (ret) {
1247 		free_secdata(secdata);
1248 		return ret;
1249 	}
1250 	ret = security_sb_parse_opts_str(secdata, sec_opts);
1251 	free_secdata(secdata);
1252 	return ret;
1253 }
1254 
1255 static int setup_security_options(struct btrfs_fs_info *fs_info,
1256 				  struct super_block *sb,
1257 				  struct security_mnt_opts *sec_opts)
1258 {
1259 	int ret = 0;
1260 
1261 	/*
1262 	 * Call security_sb_set_mnt_opts() to check whether new sec_opts
1263 	 * is valid.
1264 	 */
1265 	ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1266 	if (ret)
1267 		return ret;
1268 
1269 #ifdef CONFIG_SECURITY
1270 	if (!fs_info->security_opts.num_mnt_opts) {
1271 		/* first time security setup, copy sec_opts to fs_info */
1272 		memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1273 	} else {
1274 		/*
1275 		 * Since SELinux(the only one supports security_mnt_opts) does
1276 		 * NOT support changing context during remount/mount same sb,
1277 		 * This must be the same or part of the same security options,
1278 		 * just free it.
1279 		 */
1280 		security_free_mnt_opts(sec_opts);
1281 	}
1282 #endif
1283 	return ret;
1284 }
1285 
1286 /*
1287  * Find a superblock for the given device / mount point.
1288  *
1289  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1290  *	  for multiple device setup.  Make sure to keep it in sync.
1291  */
1292 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1293 		const char *device_name, void *data)
1294 {
1295 	struct block_device *bdev = NULL;
1296 	struct super_block *s;
1297 	struct dentry *root;
1298 	struct btrfs_fs_devices *fs_devices = NULL;
1299 	struct btrfs_fs_info *fs_info = NULL;
1300 	struct security_mnt_opts new_sec_opts;
1301 	fmode_t mode = FMODE_READ;
1302 	char *subvol_name = NULL;
1303 	u64 subvol_objectid = 0;
1304 	int error = 0;
1305 
1306 	if (!(flags & MS_RDONLY))
1307 		mode |= FMODE_WRITE;
1308 
1309 	error = btrfs_parse_early_options(data, mode, fs_type,
1310 					  &subvol_name, &subvol_objectid,
1311 					  &fs_devices);
1312 	if (error) {
1313 		kfree(subvol_name);
1314 		return ERR_PTR(error);
1315 	}
1316 
1317 	if (subvol_name) {
1318 		root = mount_subvol(subvol_name, flags, device_name, data);
1319 		kfree(subvol_name);
1320 		return root;
1321 	}
1322 
1323 	security_init_mnt_opts(&new_sec_opts);
1324 	if (data) {
1325 		error = parse_security_options(data, &new_sec_opts);
1326 		if (error)
1327 			return ERR_PTR(error);
1328 	}
1329 
1330 	error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1331 	if (error)
1332 		goto error_sec_opts;
1333 
1334 	/*
1335 	 * Setup a dummy root and fs_info for test/set super.  This is because
1336 	 * we don't actually fill this stuff out until open_ctree, but we need
1337 	 * it for searching for existing supers, so this lets us do that and
1338 	 * then open_ctree will properly initialize everything later.
1339 	 */
1340 	fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1341 	if (!fs_info) {
1342 		error = -ENOMEM;
1343 		goto error_sec_opts;
1344 	}
1345 
1346 	fs_info->fs_devices = fs_devices;
1347 
1348 	fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1349 	fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1350 	security_init_mnt_opts(&fs_info->security_opts);
1351 	if (!fs_info->super_copy || !fs_info->super_for_commit) {
1352 		error = -ENOMEM;
1353 		goto error_fs_info;
1354 	}
1355 
1356 	error = btrfs_open_devices(fs_devices, mode, fs_type);
1357 	if (error)
1358 		goto error_fs_info;
1359 
1360 	if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1361 		error = -EACCES;
1362 		goto error_close_devices;
1363 	}
1364 
1365 	bdev = fs_devices->latest_bdev;
1366 	s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1367 		 fs_info);
1368 	if (IS_ERR(s)) {
1369 		error = PTR_ERR(s);
1370 		goto error_close_devices;
1371 	}
1372 
1373 	if (s->s_root) {
1374 		btrfs_close_devices(fs_devices);
1375 		free_fs_info(fs_info);
1376 		if ((flags ^ s->s_flags) & MS_RDONLY)
1377 			error = -EBUSY;
1378 	} else {
1379 		char b[BDEVNAME_SIZE];
1380 
1381 		strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
1382 		btrfs_sb(s)->bdev_holder = fs_type;
1383 		error = btrfs_fill_super(s, fs_devices, data,
1384 					 flags & MS_SILENT ? 1 : 0);
1385 	}
1386 
1387 	root = !error ? get_default_root(s, subvol_objectid) : ERR_PTR(error);
1388 	if (IS_ERR(root)) {
1389 		deactivate_locked_super(s);
1390 		error = PTR_ERR(root);
1391 		goto error_sec_opts;
1392 	}
1393 
1394 	fs_info = btrfs_sb(s);
1395 	error = setup_security_options(fs_info, s, &new_sec_opts);
1396 	if (error) {
1397 		dput(root);
1398 		deactivate_locked_super(s);
1399 		goto error_sec_opts;
1400 	}
1401 
1402 	return root;
1403 
1404 error_close_devices:
1405 	btrfs_close_devices(fs_devices);
1406 error_fs_info:
1407 	free_fs_info(fs_info);
1408 error_sec_opts:
1409 	security_free_mnt_opts(&new_sec_opts);
1410 	return ERR_PTR(error);
1411 }
1412 
1413 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1414 				     int new_pool_size, int old_pool_size)
1415 {
1416 	if (new_pool_size == old_pool_size)
1417 		return;
1418 
1419 	fs_info->thread_pool_size = new_pool_size;
1420 
1421 	btrfs_info(fs_info, "resize thread pool %d -> %d",
1422 	       old_pool_size, new_pool_size);
1423 
1424 	btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1425 	btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1426 	btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1427 	btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1428 	btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1429 	btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1430 	btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1431 				new_pool_size);
1432 	btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1433 	btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1434 	btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1435 	btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1436 	btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1437 				new_pool_size);
1438 }
1439 
1440 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1441 {
1442 	set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1443 }
1444 
1445 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1446 				       unsigned long old_opts, int flags)
1447 {
1448 	if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1449 	    (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1450 	     (flags & MS_RDONLY))) {
1451 		/* wait for any defraggers to finish */
1452 		wait_event(fs_info->transaction_wait,
1453 			   (atomic_read(&fs_info->defrag_running) == 0));
1454 		if (flags & MS_RDONLY)
1455 			sync_filesystem(fs_info->sb);
1456 	}
1457 }
1458 
1459 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1460 					 unsigned long old_opts)
1461 {
1462 	/*
1463 	 * We need cleanup all defragable inodes if the autodefragment is
1464 	 * close or the fs is R/O.
1465 	 */
1466 	if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1467 	    (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1468 	     (fs_info->sb->s_flags & MS_RDONLY))) {
1469 		btrfs_cleanup_defrag_inodes(fs_info);
1470 	}
1471 
1472 	clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1473 }
1474 
1475 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1476 {
1477 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1478 	struct btrfs_root *root = fs_info->tree_root;
1479 	unsigned old_flags = sb->s_flags;
1480 	unsigned long old_opts = fs_info->mount_opt;
1481 	unsigned long old_compress_type = fs_info->compress_type;
1482 	u64 old_max_inline = fs_info->max_inline;
1483 	u64 old_alloc_start = fs_info->alloc_start;
1484 	int old_thread_pool_size = fs_info->thread_pool_size;
1485 	unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1486 	int ret;
1487 
1488 	sync_filesystem(sb);
1489 	btrfs_remount_prepare(fs_info);
1490 
1491 	if (data) {
1492 		struct security_mnt_opts new_sec_opts;
1493 
1494 		security_init_mnt_opts(&new_sec_opts);
1495 		ret = parse_security_options(data, &new_sec_opts);
1496 		if (ret)
1497 			goto restore;
1498 		ret = setup_security_options(fs_info, sb,
1499 					     &new_sec_opts);
1500 		if (ret) {
1501 			security_free_mnt_opts(&new_sec_opts);
1502 			goto restore;
1503 		}
1504 	}
1505 
1506 	ret = btrfs_parse_options(root, data);
1507 	if (ret) {
1508 		ret = -EINVAL;
1509 		goto restore;
1510 	}
1511 
1512 	btrfs_remount_begin(fs_info, old_opts, *flags);
1513 	btrfs_resize_thread_pool(fs_info,
1514 		fs_info->thread_pool_size, old_thread_pool_size);
1515 
1516 	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1517 		goto out;
1518 
1519 	if (*flags & MS_RDONLY) {
1520 		/*
1521 		 * this also happens on 'umount -rf' or on shutdown, when
1522 		 * the filesystem is busy.
1523 		 */
1524 		cancel_work_sync(&fs_info->async_reclaim_work);
1525 
1526 		/* wait for the uuid_scan task to finish */
1527 		down(&fs_info->uuid_tree_rescan_sem);
1528 		/* avoid complains from lockdep et al. */
1529 		up(&fs_info->uuid_tree_rescan_sem);
1530 
1531 		sb->s_flags |= MS_RDONLY;
1532 
1533 		btrfs_dev_replace_suspend_for_unmount(fs_info);
1534 		btrfs_scrub_cancel(fs_info);
1535 		btrfs_pause_balance(fs_info);
1536 
1537 		ret = btrfs_commit_super(root);
1538 		if (ret)
1539 			goto restore;
1540 	} else {
1541 		if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1542 			btrfs_err(fs_info,
1543 				"Remounting read-write after error is not allowed");
1544 			ret = -EINVAL;
1545 			goto restore;
1546 		}
1547 		if (fs_info->fs_devices->rw_devices == 0) {
1548 			ret = -EACCES;
1549 			goto restore;
1550 		}
1551 
1552 		if (fs_info->fs_devices->missing_devices >
1553 		     fs_info->num_tolerated_disk_barrier_failures &&
1554 		    !(*flags & MS_RDONLY)) {
1555 			btrfs_warn(fs_info,
1556 				"too many missing devices, writeable remount is not allowed");
1557 			ret = -EACCES;
1558 			goto restore;
1559 		}
1560 
1561 		if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1562 			ret = -EINVAL;
1563 			goto restore;
1564 		}
1565 
1566 		ret = btrfs_cleanup_fs_roots(fs_info);
1567 		if (ret)
1568 			goto restore;
1569 
1570 		/* recover relocation */
1571 		mutex_lock(&fs_info->cleaner_mutex);
1572 		ret = btrfs_recover_relocation(root);
1573 		mutex_unlock(&fs_info->cleaner_mutex);
1574 		if (ret)
1575 			goto restore;
1576 
1577 		ret = btrfs_resume_balance_async(fs_info);
1578 		if (ret)
1579 			goto restore;
1580 
1581 		ret = btrfs_resume_dev_replace_async(fs_info);
1582 		if (ret) {
1583 			btrfs_warn(fs_info, "failed to resume dev_replace");
1584 			goto restore;
1585 		}
1586 
1587 		if (!fs_info->uuid_root) {
1588 			btrfs_info(fs_info, "creating UUID tree");
1589 			ret = btrfs_create_uuid_tree(fs_info);
1590 			if (ret) {
1591 				btrfs_warn(fs_info, "failed to create the UUID tree %d", ret);
1592 				goto restore;
1593 			}
1594 		}
1595 		sb->s_flags &= ~MS_RDONLY;
1596 	}
1597 out:
1598 	wake_up_process(fs_info->transaction_kthread);
1599 	btrfs_remount_cleanup(fs_info, old_opts);
1600 	return 0;
1601 
1602 restore:
1603 	/* We've hit an error - don't reset MS_RDONLY */
1604 	if (sb->s_flags & MS_RDONLY)
1605 		old_flags |= MS_RDONLY;
1606 	sb->s_flags = old_flags;
1607 	fs_info->mount_opt = old_opts;
1608 	fs_info->compress_type = old_compress_type;
1609 	fs_info->max_inline = old_max_inline;
1610 	mutex_lock(&fs_info->chunk_mutex);
1611 	fs_info->alloc_start = old_alloc_start;
1612 	mutex_unlock(&fs_info->chunk_mutex);
1613 	btrfs_resize_thread_pool(fs_info,
1614 		old_thread_pool_size, fs_info->thread_pool_size);
1615 	fs_info->metadata_ratio = old_metadata_ratio;
1616 	btrfs_remount_cleanup(fs_info, old_opts);
1617 	return ret;
1618 }
1619 
1620 /* Used to sort the devices by max_avail(descending sort) */
1621 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1622 				       const void *dev_info2)
1623 {
1624 	if (((struct btrfs_device_info *)dev_info1)->max_avail >
1625 	    ((struct btrfs_device_info *)dev_info2)->max_avail)
1626 		return -1;
1627 	else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1628 		 ((struct btrfs_device_info *)dev_info2)->max_avail)
1629 		return 1;
1630 	else
1631 	return 0;
1632 }
1633 
1634 /*
1635  * sort the devices by max_avail, in which max free extent size of each device
1636  * is stored.(Descending Sort)
1637  */
1638 static inline void btrfs_descending_sort_devices(
1639 					struct btrfs_device_info *devices,
1640 					size_t nr_devices)
1641 {
1642 	sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1643 	     btrfs_cmp_device_free_bytes, NULL);
1644 }
1645 
1646 /*
1647  * The helper to calc the free space on the devices that can be used to store
1648  * file data.
1649  */
1650 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1651 {
1652 	struct btrfs_fs_info *fs_info = root->fs_info;
1653 	struct btrfs_device_info *devices_info;
1654 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1655 	struct btrfs_device *device;
1656 	u64 skip_space;
1657 	u64 type;
1658 	u64 avail_space;
1659 	u64 used_space;
1660 	u64 min_stripe_size;
1661 	int min_stripes = 1, num_stripes = 1;
1662 	int i = 0, nr_devices;
1663 	int ret;
1664 
1665 	/*
1666 	 * We aren't under the device list lock, so this is racey-ish, but good
1667 	 * enough for our purposes.
1668 	 */
1669 	nr_devices = fs_info->fs_devices->open_devices;
1670 	if (!nr_devices) {
1671 		smp_mb();
1672 		nr_devices = fs_info->fs_devices->open_devices;
1673 		ASSERT(nr_devices);
1674 		if (!nr_devices) {
1675 			*free_bytes = 0;
1676 			return 0;
1677 		}
1678 	}
1679 
1680 	devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1681 			       GFP_NOFS);
1682 	if (!devices_info)
1683 		return -ENOMEM;
1684 
1685 	/* calc min stripe number for data space alloction */
1686 	type = btrfs_get_alloc_profile(root, 1);
1687 	if (type & BTRFS_BLOCK_GROUP_RAID0) {
1688 		min_stripes = 2;
1689 		num_stripes = nr_devices;
1690 	} else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1691 		min_stripes = 2;
1692 		num_stripes = 2;
1693 	} else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1694 		min_stripes = 4;
1695 		num_stripes = 4;
1696 	}
1697 
1698 	if (type & BTRFS_BLOCK_GROUP_DUP)
1699 		min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1700 	else
1701 		min_stripe_size = BTRFS_STRIPE_LEN;
1702 
1703 	if (fs_info->alloc_start)
1704 		mutex_lock(&fs_devices->device_list_mutex);
1705 	rcu_read_lock();
1706 	list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1707 		if (!device->in_fs_metadata || !device->bdev ||
1708 		    device->is_tgtdev_for_dev_replace)
1709 			continue;
1710 
1711 		if (i >= nr_devices)
1712 			break;
1713 
1714 		avail_space = device->total_bytes - device->bytes_used;
1715 
1716 		/* align with stripe_len */
1717 		do_div(avail_space, BTRFS_STRIPE_LEN);
1718 		avail_space *= BTRFS_STRIPE_LEN;
1719 
1720 		/*
1721 		 * In order to avoid overwritting the superblock on the drive,
1722 		 * btrfs starts at an offset of at least 1MB when doing chunk
1723 		 * allocation.
1724 		 */
1725 		skip_space = 1024 * 1024;
1726 
1727 		/* user can set the offset in fs_info->alloc_start. */
1728 		if (fs_info->alloc_start &&
1729 		    fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1730 		    device->total_bytes) {
1731 			rcu_read_unlock();
1732 			skip_space = max(fs_info->alloc_start, skip_space);
1733 
1734 			/*
1735 			 * btrfs can not use the free space in
1736 			 * [0, skip_space - 1], we must subtract it from the
1737 			 * total. In order to implement it, we account the used
1738 			 * space in this range first.
1739 			 */
1740 			ret = btrfs_account_dev_extents_size(device, 0,
1741 							     skip_space - 1,
1742 							     &used_space);
1743 			if (ret) {
1744 				kfree(devices_info);
1745 				mutex_unlock(&fs_devices->device_list_mutex);
1746 				return ret;
1747 			}
1748 
1749 			rcu_read_lock();
1750 
1751 			/* calc the free space in [0, skip_space - 1] */
1752 			skip_space -= used_space;
1753 		}
1754 
1755 		/*
1756 		 * we can use the free space in [0, skip_space - 1], subtract
1757 		 * it from the total.
1758 		 */
1759 		if (avail_space && avail_space >= skip_space)
1760 			avail_space -= skip_space;
1761 		else
1762 			avail_space = 0;
1763 
1764 		if (avail_space < min_stripe_size)
1765 			continue;
1766 
1767 		devices_info[i].dev = device;
1768 		devices_info[i].max_avail = avail_space;
1769 
1770 		i++;
1771 	}
1772 	rcu_read_unlock();
1773 	if (fs_info->alloc_start)
1774 		mutex_unlock(&fs_devices->device_list_mutex);
1775 
1776 	nr_devices = i;
1777 
1778 	btrfs_descending_sort_devices(devices_info, nr_devices);
1779 
1780 	i = nr_devices - 1;
1781 	avail_space = 0;
1782 	while (nr_devices >= min_stripes) {
1783 		if (num_stripes > nr_devices)
1784 			num_stripes = nr_devices;
1785 
1786 		if (devices_info[i].max_avail >= min_stripe_size) {
1787 			int j;
1788 			u64 alloc_size;
1789 
1790 			avail_space += devices_info[i].max_avail * num_stripes;
1791 			alloc_size = devices_info[i].max_avail;
1792 			for (j = i + 1 - num_stripes; j <= i; j++)
1793 				devices_info[j].max_avail -= alloc_size;
1794 		}
1795 		i--;
1796 		nr_devices--;
1797 	}
1798 
1799 	kfree(devices_info);
1800 	*free_bytes = avail_space;
1801 	return 0;
1802 }
1803 
1804 /*
1805  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
1806  *
1807  * If there's a redundant raid level at DATA block groups, use the respective
1808  * multiplier to scale the sizes.
1809  *
1810  * Unused device space usage is based on simulating the chunk allocator
1811  * algorithm that respects the device sizes, order of allocations and the
1812  * 'alloc_start' value, this is a close approximation of the actual use but
1813  * there are other factors that may change the result (like a new metadata
1814  * chunk).
1815  *
1816  * FIXME: not accurate for mixed block groups, total and free/used are ok,
1817  * available appears slightly larger.
1818  */
1819 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1820 {
1821 	struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
1822 	struct btrfs_super_block *disk_super = fs_info->super_copy;
1823 	struct list_head *head = &fs_info->space_info;
1824 	struct btrfs_space_info *found;
1825 	u64 total_used = 0;
1826 	u64 total_free_data = 0;
1827 	int bits = dentry->d_sb->s_blocksize_bits;
1828 	__be32 *fsid = (__be32 *)fs_info->fsid;
1829 	unsigned factor = 1;
1830 	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
1831 	int ret;
1832 
1833 	/*
1834 	 * holding chunk_muext to avoid allocating new chunks, holding
1835 	 * device_list_mutex to avoid the device being removed
1836 	 */
1837 	rcu_read_lock();
1838 	list_for_each_entry_rcu(found, head, list) {
1839 		if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
1840 			int i;
1841 
1842 			total_free_data += found->disk_total - found->disk_used;
1843 			total_free_data -=
1844 				btrfs_account_ro_block_groups_free_space(found);
1845 
1846 			for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
1847 				if (!list_empty(&found->block_groups[i])) {
1848 					switch (i) {
1849 					case BTRFS_RAID_DUP:
1850 					case BTRFS_RAID_RAID1:
1851 					case BTRFS_RAID_RAID10:
1852 						factor = 2;
1853 					}
1854 				}
1855 			}
1856 		}
1857 
1858 		total_used += found->disk_used;
1859 	}
1860 
1861 	rcu_read_unlock();
1862 
1863 	buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
1864 	buf->f_blocks >>= bits;
1865 	buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
1866 
1867 	/* Account global block reserve as used, it's in logical size already */
1868 	spin_lock(&block_rsv->lock);
1869 	buf->f_bfree -= block_rsv->size >> bits;
1870 	spin_unlock(&block_rsv->lock);
1871 
1872 	buf->f_bavail = div_u64(total_free_data, factor);
1873 	ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
1874 	if (ret)
1875 		return ret;
1876 	buf->f_bavail += div_u64(total_free_data, factor);
1877 	buf->f_bavail = buf->f_bavail >> bits;
1878 
1879 	buf->f_type = BTRFS_SUPER_MAGIC;
1880 	buf->f_bsize = dentry->d_sb->s_blocksize;
1881 	buf->f_namelen = BTRFS_NAME_LEN;
1882 
1883 	/* We treat it as constant endianness (it doesn't matter _which_)
1884 	   because we want the fsid to come out the same whether mounted
1885 	   on a big-endian or little-endian host */
1886 	buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
1887 	buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
1888 	/* Mask in the root object ID too, to disambiguate subvols */
1889 	buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
1890 	buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
1891 
1892 	return 0;
1893 }
1894 
1895 static void btrfs_kill_super(struct super_block *sb)
1896 {
1897 	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1898 	kill_anon_super(sb);
1899 	free_fs_info(fs_info);
1900 }
1901 
1902 static struct file_system_type btrfs_fs_type = {
1903 	.owner		= THIS_MODULE,
1904 	.name		= "btrfs",
1905 	.mount		= btrfs_mount,
1906 	.kill_sb	= btrfs_kill_super,
1907 	.fs_flags	= FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
1908 };
1909 MODULE_ALIAS_FS("btrfs");
1910 
1911 /*
1912  * used by btrfsctl to scan devices when no FS is mounted
1913  */
1914 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
1915 				unsigned long arg)
1916 {
1917 	struct btrfs_ioctl_vol_args *vol;
1918 	struct btrfs_fs_devices *fs_devices;
1919 	int ret = -ENOTTY;
1920 
1921 	if (!capable(CAP_SYS_ADMIN))
1922 		return -EPERM;
1923 
1924 	vol = memdup_user((void __user *)arg, sizeof(*vol));
1925 	if (IS_ERR(vol))
1926 		return PTR_ERR(vol);
1927 
1928 	switch (cmd) {
1929 	case BTRFS_IOC_SCAN_DEV:
1930 		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1931 					    &btrfs_fs_type, &fs_devices);
1932 		break;
1933 	case BTRFS_IOC_DEVICES_READY:
1934 		ret = btrfs_scan_one_device(vol->name, FMODE_READ,
1935 					    &btrfs_fs_type, &fs_devices);
1936 		if (ret)
1937 			break;
1938 		ret = !(fs_devices->num_devices == fs_devices->total_devices);
1939 		break;
1940 	}
1941 
1942 	kfree(vol);
1943 	return ret;
1944 }
1945 
1946 static int btrfs_freeze(struct super_block *sb)
1947 {
1948 	struct btrfs_trans_handle *trans;
1949 	struct btrfs_root *root = btrfs_sb(sb)->tree_root;
1950 
1951 	trans = btrfs_attach_transaction_barrier(root);
1952 	if (IS_ERR(trans)) {
1953 		/* no transaction, don't bother */
1954 		if (PTR_ERR(trans) == -ENOENT)
1955 			return 0;
1956 		return PTR_ERR(trans);
1957 	}
1958 	return btrfs_commit_transaction(trans, root);
1959 }
1960 
1961 static int btrfs_unfreeze(struct super_block *sb)
1962 {
1963 	return 0;
1964 }
1965 
1966 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
1967 {
1968 	struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
1969 	struct btrfs_fs_devices *cur_devices;
1970 	struct btrfs_device *dev, *first_dev = NULL;
1971 	struct list_head *head;
1972 	struct rcu_string *name;
1973 
1974 	mutex_lock(&fs_info->fs_devices->device_list_mutex);
1975 	cur_devices = fs_info->fs_devices;
1976 	while (cur_devices) {
1977 		head = &cur_devices->devices;
1978 		list_for_each_entry(dev, head, dev_list) {
1979 			if (dev->missing)
1980 				continue;
1981 			if (!dev->name)
1982 				continue;
1983 			if (!first_dev || dev->devid < first_dev->devid)
1984 				first_dev = dev;
1985 		}
1986 		cur_devices = cur_devices->seed;
1987 	}
1988 
1989 	if (first_dev) {
1990 		rcu_read_lock();
1991 		name = rcu_dereference(first_dev->name);
1992 		seq_escape(m, name->str, " \t\n\\");
1993 		rcu_read_unlock();
1994 	} else {
1995 		WARN_ON(1);
1996 	}
1997 	mutex_unlock(&fs_info->fs_devices->device_list_mutex);
1998 	return 0;
1999 }
2000 
2001 static const struct super_operations btrfs_super_ops = {
2002 	.drop_inode	= btrfs_drop_inode,
2003 	.evict_inode	= btrfs_evict_inode,
2004 	.put_super	= btrfs_put_super,
2005 	.sync_fs	= btrfs_sync_fs,
2006 	.show_options	= btrfs_show_options,
2007 	.show_devname	= btrfs_show_devname,
2008 	.write_inode	= btrfs_write_inode,
2009 	.alloc_inode	= btrfs_alloc_inode,
2010 	.destroy_inode	= btrfs_destroy_inode,
2011 	.statfs		= btrfs_statfs,
2012 	.remount_fs	= btrfs_remount,
2013 	.freeze_fs	= btrfs_freeze,
2014 	.unfreeze_fs	= btrfs_unfreeze,
2015 };
2016 
2017 static const struct file_operations btrfs_ctl_fops = {
2018 	.unlocked_ioctl	 = btrfs_control_ioctl,
2019 	.compat_ioctl = btrfs_control_ioctl,
2020 	.owner	 = THIS_MODULE,
2021 	.llseek = noop_llseek,
2022 };
2023 
2024 static struct miscdevice btrfs_misc = {
2025 	.minor		= BTRFS_MINOR,
2026 	.name		= "btrfs-control",
2027 	.fops		= &btrfs_ctl_fops
2028 };
2029 
2030 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2031 MODULE_ALIAS("devname:btrfs-control");
2032 
2033 static int btrfs_interface_init(void)
2034 {
2035 	return misc_register(&btrfs_misc);
2036 }
2037 
2038 static void btrfs_interface_exit(void)
2039 {
2040 	if (misc_deregister(&btrfs_misc) < 0)
2041 		printk(KERN_INFO "BTRFS: misc_deregister failed for control device\n");
2042 }
2043 
2044 static void btrfs_print_info(void)
2045 {
2046 	printk(KERN_INFO "Btrfs loaded"
2047 #ifdef CONFIG_BTRFS_DEBUG
2048 			", debug=on"
2049 #endif
2050 #ifdef CONFIG_BTRFS_ASSERT
2051 			", assert=on"
2052 #endif
2053 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2054 			", integrity-checker=on"
2055 #endif
2056 			"\n");
2057 }
2058 
2059 static int btrfs_run_sanity_tests(void)
2060 {
2061 	int ret;
2062 
2063 	ret = btrfs_init_test_fs();
2064 	if (ret)
2065 		return ret;
2066 
2067 	ret = btrfs_test_free_space_cache();
2068 	if (ret)
2069 		goto out;
2070 	ret = btrfs_test_extent_buffer_operations();
2071 	if (ret)
2072 		goto out;
2073 	ret = btrfs_test_extent_io();
2074 	if (ret)
2075 		goto out;
2076 	ret = btrfs_test_inodes();
2077 	if (ret)
2078 		goto out;
2079 	ret = btrfs_test_qgroups();
2080 out:
2081 	btrfs_destroy_test_fs();
2082 	return ret;
2083 }
2084 
2085 static int __init init_btrfs_fs(void)
2086 {
2087 	int err;
2088 
2089 	err = btrfs_hash_init();
2090 	if (err)
2091 		return err;
2092 
2093 	btrfs_props_init();
2094 
2095 	err = btrfs_init_sysfs();
2096 	if (err)
2097 		goto free_hash;
2098 
2099 	btrfs_init_compress();
2100 
2101 	err = btrfs_init_cachep();
2102 	if (err)
2103 		goto free_compress;
2104 
2105 	err = extent_io_init();
2106 	if (err)
2107 		goto free_cachep;
2108 
2109 	err = extent_map_init();
2110 	if (err)
2111 		goto free_extent_io;
2112 
2113 	err = ordered_data_init();
2114 	if (err)
2115 		goto free_extent_map;
2116 
2117 	err = btrfs_delayed_inode_init();
2118 	if (err)
2119 		goto free_ordered_data;
2120 
2121 	err = btrfs_auto_defrag_init();
2122 	if (err)
2123 		goto free_delayed_inode;
2124 
2125 	err = btrfs_delayed_ref_init();
2126 	if (err)
2127 		goto free_auto_defrag;
2128 
2129 	err = btrfs_prelim_ref_init();
2130 	if (err)
2131 		goto free_delayed_ref;
2132 
2133 	err = btrfs_end_io_wq_init();
2134 	if (err)
2135 		goto free_prelim_ref;
2136 
2137 	err = btrfs_interface_init();
2138 	if (err)
2139 		goto free_end_io_wq;
2140 
2141 	btrfs_init_lockdep();
2142 
2143 	btrfs_print_info();
2144 
2145 	err = btrfs_run_sanity_tests();
2146 	if (err)
2147 		goto unregister_ioctl;
2148 
2149 	err = register_filesystem(&btrfs_fs_type);
2150 	if (err)
2151 		goto unregister_ioctl;
2152 
2153 	return 0;
2154 
2155 unregister_ioctl:
2156 	btrfs_interface_exit();
2157 free_end_io_wq:
2158 	btrfs_end_io_wq_exit();
2159 free_prelim_ref:
2160 	btrfs_prelim_ref_exit();
2161 free_delayed_ref:
2162 	btrfs_delayed_ref_exit();
2163 free_auto_defrag:
2164 	btrfs_auto_defrag_exit();
2165 free_delayed_inode:
2166 	btrfs_delayed_inode_exit();
2167 free_ordered_data:
2168 	ordered_data_exit();
2169 free_extent_map:
2170 	extent_map_exit();
2171 free_extent_io:
2172 	extent_io_exit();
2173 free_cachep:
2174 	btrfs_destroy_cachep();
2175 free_compress:
2176 	btrfs_exit_compress();
2177 	btrfs_exit_sysfs();
2178 free_hash:
2179 	btrfs_hash_exit();
2180 	return err;
2181 }
2182 
2183 static void __exit exit_btrfs_fs(void)
2184 {
2185 	btrfs_destroy_cachep();
2186 	btrfs_delayed_ref_exit();
2187 	btrfs_auto_defrag_exit();
2188 	btrfs_delayed_inode_exit();
2189 	btrfs_prelim_ref_exit();
2190 	ordered_data_exit();
2191 	extent_map_exit();
2192 	extent_io_exit();
2193 	btrfs_interface_exit();
2194 	btrfs_end_io_wq_exit();
2195 	unregister_filesystem(&btrfs_fs_type);
2196 	btrfs_exit_sysfs();
2197 	btrfs_cleanup_fs_uuids();
2198 	btrfs_exit_compress();
2199 	btrfs_hash_exit();
2200 }
2201 
2202 late_initcall(init_btrfs_fs);
2203 module_exit(exit_btrfs_fs)
2204 
2205 MODULE_LICENSE("GPL");
2206