Merge tag 'upstream-4.8-rc1' of git://git.infradead.org/linux-ubifs
[sfrench/cifs-2.6.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 <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 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 /* btrfs handle error by forcing the filesystem readonly */
101 static void btrfs_handle_error(struct btrfs_fs_info *fs_info)
102 {
103         struct super_block *sb = fs_info->sb;
104
105         if (sb->s_flags & MS_RDONLY)
106                 return;
107
108         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
109                 sb->s_flags |= MS_RDONLY;
110                 btrfs_info(fs_info, "forced readonly");
111                 /*
112                  * Note that a running device replace operation is not
113                  * canceled here although there is no way to update
114                  * the progress. It would add the risk of a deadlock,
115                  * therefore the canceling is omitted. The only penalty
116                  * is that some I/O remains active until the procedure
117                  * completes. The next time when the filesystem is
118                  * mounted writeable again, the device replace
119                  * operation continues.
120                  */
121         }
122 }
123
124 /*
125  * __btrfs_handle_fs_error decodes expected errors from the caller and
126  * invokes the approciate error response.
127  */
128 __cold
129 void __btrfs_handle_fs_error(struct btrfs_fs_info *fs_info, const char *function,
130                        unsigned int line, int errno, const char *fmt, ...)
131 {
132         struct super_block *sb = fs_info->sb;
133 #ifdef CONFIG_PRINTK
134         const char *errstr;
135 #endif
136
137         /*
138          * Special case: if the error is EROFS, and we're already
139          * under MS_RDONLY, then it is safe here.
140          */
141         if (errno == -EROFS && (sb->s_flags & MS_RDONLY))
142                 return;
143
144 #ifdef CONFIG_PRINTK
145         errstr = btrfs_decode_error(errno);
146         if (fmt) {
147                 struct va_format vaf;
148                 va_list args;
149
150                 va_start(args, fmt);
151                 vaf.fmt = fmt;
152                 vaf.va = &args;
153
154                 printk(KERN_CRIT
155                         "BTRFS: error (device %s) in %s:%d: errno=%d %s (%pV)\n",
156                         sb->s_id, function, line, errno, errstr, &vaf);
157                 va_end(args);
158         } else {
159                 printk(KERN_CRIT "BTRFS: error (device %s) in %s:%d: errno=%d %s\n",
160                         sb->s_id, function, line, errno, errstr);
161         }
162 #endif
163
164         /*
165          * Today we only save the error info to memory.  Long term we'll
166          * also send it down to the disk
167          */
168         set_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state);
169
170         /* Don't go through full error handling during mount */
171         if (sb->s_flags & MS_BORN)
172                 btrfs_handle_error(fs_info);
173 }
174
175 #ifdef CONFIG_PRINTK
176 static const char * const logtypes[] = {
177         "emergency",
178         "alert",
179         "critical",
180         "error",
181         "warning",
182         "notice",
183         "info",
184         "debug",
185 };
186
187 void btrfs_printk(const struct btrfs_fs_info *fs_info, const char *fmt, ...)
188 {
189         struct super_block *sb = fs_info->sb;
190         char lvl[4];
191         struct va_format vaf;
192         va_list args;
193         const char *type = logtypes[4];
194         int kern_level;
195
196         va_start(args, fmt);
197
198         kern_level = printk_get_level(fmt);
199         if (kern_level) {
200                 size_t size = printk_skip_level(fmt) - fmt;
201                 memcpy(lvl, fmt,  size);
202                 lvl[size] = '\0';
203                 fmt += size;
204                 type = logtypes[kern_level - '0'];
205         } else
206                 *lvl = '\0';
207
208         vaf.fmt = fmt;
209         vaf.va = &args;
210
211         printk("%sBTRFS %s (device %s): %pV\n", lvl, type, sb->s_id, &vaf);
212
213         va_end(args);
214 }
215 #endif
216
217 /*
218  * We only mark the transaction aborted and then set the file system read-only.
219  * This will prevent new transactions from starting or trying to join this
220  * one.
221  *
222  * This means that error recovery at the call site is limited to freeing
223  * any local memory allocations and passing the error code up without
224  * further cleanup. The transaction should complete as it normally would
225  * in the call path but will return -EIO.
226  *
227  * We'll complete the cleanup in btrfs_end_transaction and
228  * btrfs_commit_transaction.
229  */
230 __cold
231 void __btrfs_abort_transaction(struct btrfs_trans_handle *trans,
232                                struct btrfs_root *root, const char *function,
233                                unsigned int line, int errno)
234 {
235         trans->aborted = errno;
236         /* Nothing used. The other threads that have joined this
237          * transaction may be able to continue. */
238         if (!trans->dirty && list_empty(&trans->new_bgs)) {
239                 const char *errstr;
240
241                 errstr = btrfs_decode_error(errno);
242                 btrfs_warn(root->fs_info,
243                            "%s:%d: Aborting unused transaction(%s).",
244                            function, line, errstr);
245                 return;
246         }
247         ACCESS_ONCE(trans->transaction->aborted) = errno;
248         /* Wake up anybody who may be waiting on this transaction */
249         wake_up(&root->fs_info->transaction_wait);
250         wake_up(&root->fs_info->transaction_blocked_wait);
251         __btrfs_handle_fs_error(root->fs_info, function, line, errno, NULL);
252 }
253 /*
254  * __btrfs_panic decodes unexpected, fatal errors from the caller,
255  * issues an alert, and either panics or BUGs, depending on mount options.
256  */
257 __cold
258 void __btrfs_panic(struct btrfs_fs_info *fs_info, const char *function,
259                    unsigned int line, int errno, const char *fmt, ...)
260 {
261         char *s_id = "<unknown>";
262         const char *errstr;
263         struct va_format vaf = { .fmt = fmt };
264         va_list args;
265
266         if (fs_info)
267                 s_id = fs_info->sb->s_id;
268
269         va_start(args, fmt);
270         vaf.va = &args;
271
272         errstr = btrfs_decode_error(errno);
273         if (fs_info && (fs_info->mount_opt & BTRFS_MOUNT_PANIC_ON_FATAL_ERROR))
274                 panic(KERN_CRIT "BTRFS panic (device %s) in %s:%d: %pV (errno=%d %s)\n",
275                         s_id, function, line, &vaf, errno, errstr);
276
277         btrfs_crit(fs_info, "panic in %s:%d: %pV (errno=%d %s)",
278                    function, line, &vaf, errno, errstr);
279         va_end(args);
280         /* Caller calls BUG() */
281 }
282
283 static void btrfs_put_super(struct super_block *sb)
284 {
285         close_ctree(btrfs_sb(sb)->tree_root);
286 }
287
288 enum {
289         Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
290         Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
291         Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
292         Opt_compress_type, Opt_compress_force, Opt_compress_force_type,
293         Opt_notreelog, Opt_ratio, Opt_flushoncommit, Opt_discard,
294         Opt_space_cache, Opt_space_cache_version, Opt_clear_cache,
295         Opt_user_subvol_rm_allowed, Opt_enospc_debug, Opt_subvolrootid,
296         Opt_defrag, Opt_inode_cache, Opt_no_space_cache, Opt_recovery,
297         Opt_skip_balance, Opt_check_integrity,
298         Opt_check_integrity_including_extent_data,
299         Opt_check_integrity_print_mask, Opt_fatal_errors, Opt_rescan_uuid_tree,
300         Opt_commit_interval, Opt_barrier, Opt_nodefrag, Opt_nodiscard,
301         Opt_noenospc_debug, Opt_noflushoncommit, Opt_acl, Opt_datacow,
302         Opt_datasum, Opt_treelog, Opt_noinode_cache, Opt_usebackuproot,
303         Opt_nologreplay, Opt_norecovery,
304 #ifdef CONFIG_BTRFS_DEBUG
305         Opt_fragment_data, Opt_fragment_metadata, Opt_fragment_all,
306 #endif
307         Opt_err,
308 };
309
310 static const match_table_t tokens = {
311         {Opt_degraded, "degraded"},
312         {Opt_subvol, "subvol=%s"},
313         {Opt_subvolid, "subvolid=%s"},
314         {Opt_device, "device=%s"},
315         {Opt_nodatasum, "nodatasum"},
316         {Opt_datasum, "datasum"},
317         {Opt_nodatacow, "nodatacow"},
318         {Opt_datacow, "datacow"},
319         {Opt_nobarrier, "nobarrier"},
320         {Opt_barrier, "barrier"},
321         {Opt_max_inline, "max_inline=%s"},
322         {Opt_alloc_start, "alloc_start=%s"},
323         {Opt_thread_pool, "thread_pool=%d"},
324         {Opt_compress, "compress"},
325         {Opt_compress_type, "compress=%s"},
326         {Opt_compress_force, "compress-force"},
327         {Opt_compress_force_type, "compress-force=%s"},
328         {Opt_ssd, "ssd"},
329         {Opt_ssd_spread, "ssd_spread"},
330         {Opt_nossd, "nossd"},
331         {Opt_acl, "acl"},
332         {Opt_noacl, "noacl"},
333         {Opt_notreelog, "notreelog"},
334         {Opt_treelog, "treelog"},
335         {Opt_nologreplay, "nologreplay"},
336         {Opt_norecovery, "norecovery"},
337         {Opt_flushoncommit, "flushoncommit"},
338         {Opt_noflushoncommit, "noflushoncommit"},
339         {Opt_ratio, "metadata_ratio=%d"},
340         {Opt_discard, "discard"},
341         {Opt_nodiscard, "nodiscard"},
342         {Opt_space_cache, "space_cache"},
343         {Opt_space_cache_version, "space_cache=%s"},
344         {Opt_clear_cache, "clear_cache"},
345         {Opt_user_subvol_rm_allowed, "user_subvol_rm_allowed"},
346         {Opt_enospc_debug, "enospc_debug"},
347         {Opt_noenospc_debug, "noenospc_debug"},
348         {Opt_subvolrootid, "subvolrootid=%d"},
349         {Opt_defrag, "autodefrag"},
350         {Opt_nodefrag, "noautodefrag"},
351         {Opt_inode_cache, "inode_cache"},
352         {Opt_noinode_cache, "noinode_cache"},
353         {Opt_no_space_cache, "nospace_cache"},
354         {Opt_recovery, "recovery"}, /* deprecated */
355         {Opt_usebackuproot, "usebackuproot"},
356         {Opt_skip_balance, "skip_balance"},
357         {Opt_check_integrity, "check_int"},
358         {Opt_check_integrity_including_extent_data, "check_int_data"},
359         {Opt_check_integrity_print_mask, "check_int_print_mask=%d"},
360         {Opt_rescan_uuid_tree, "rescan_uuid_tree"},
361         {Opt_fatal_errors, "fatal_errors=%s"},
362         {Opt_commit_interval, "commit=%d"},
363 #ifdef CONFIG_BTRFS_DEBUG
364         {Opt_fragment_data, "fragment=data"},
365         {Opt_fragment_metadata, "fragment=metadata"},
366         {Opt_fragment_all, "fragment=all"},
367 #endif
368         {Opt_err, NULL},
369 };
370
371 /*
372  * Regular mount options parser.  Everything that is needed only when
373  * reading in a new superblock is parsed here.
374  * XXX JDM: This needs to be cleaned up for remount.
375  */
376 int btrfs_parse_options(struct btrfs_root *root, char *options,
377                         unsigned long new_flags)
378 {
379         struct btrfs_fs_info *info = root->fs_info;
380         substring_t args[MAX_OPT_ARGS];
381         char *p, *num, *orig = NULL;
382         u64 cache_gen;
383         int intarg;
384         int ret = 0;
385         char *compress_type;
386         bool compress_force = false;
387         enum btrfs_compression_type saved_compress_type;
388         bool saved_compress_force;
389         int no_compress = 0;
390
391         cache_gen = btrfs_super_cache_generation(root->fs_info->super_copy);
392         if (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE))
393                 btrfs_set_opt(info->mount_opt, FREE_SPACE_TREE);
394         else if (cache_gen)
395                 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
396
397         /*
398          * Even the options are empty, we still need to do extra check
399          * against new flags
400          */
401         if (!options)
402                 goto check;
403
404         /*
405          * strsep changes the string, duplicate it because parse_options
406          * gets called twice
407          */
408         options = kstrdup(options, GFP_NOFS);
409         if (!options)
410                 return -ENOMEM;
411
412         orig = options;
413
414         while ((p = strsep(&options, ",")) != NULL) {
415                 int token;
416                 if (!*p)
417                         continue;
418
419                 token = match_token(p, tokens, args);
420                 switch (token) {
421                 case Opt_degraded:
422                         btrfs_info(root->fs_info, "allowing degraded mounts");
423                         btrfs_set_opt(info->mount_opt, DEGRADED);
424                         break;
425                 case Opt_subvol:
426                 case Opt_subvolid:
427                 case Opt_subvolrootid:
428                 case Opt_device:
429                         /*
430                          * These are parsed by btrfs_parse_early_options
431                          * and can be happily ignored here.
432                          */
433                         break;
434                 case Opt_nodatasum:
435                         btrfs_set_and_info(root, NODATASUM,
436                                            "setting nodatasum");
437                         break;
438                 case Opt_datasum:
439                         if (btrfs_test_opt(root, NODATASUM)) {
440                                 if (btrfs_test_opt(root, NODATACOW))
441                                         btrfs_info(root->fs_info, "setting datasum, datacow enabled");
442                                 else
443                                         btrfs_info(root->fs_info, "setting datasum");
444                         }
445                         btrfs_clear_opt(info->mount_opt, NODATACOW);
446                         btrfs_clear_opt(info->mount_opt, NODATASUM);
447                         break;
448                 case Opt_nodatacow:
449                         if (!btrfs_test_opt(root, NODATACOW)) {
450                                 if (!btrfs_test_opt(root, COMPRESS) ||
451                                     !btrfs_test_opt(root, FORCE_COMPRESS)) {
452                                         btrfs_info(root->fs_info,
453                                                    "setting nodatacow, compression disabled");
454                                 } else {
455                                         btrfs_info(root->fs_info, "setting nodatacow");
456                                 }
457                         }
458                         btrfs_clear_opt(info->mount_opt, COMPRESS);
459                         btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
460                         btrfs_set_opt(info->mount_opt, NODATACOW);
461                         btrfs_set_opt(info->mount_opt, NODATASUM);
462                         break;
463                 case Opt_datacow:
464                         btrfs_clear_and_info(root, NODATACOW,
465                                              "setting datacow");
466                         break;
467                 case Opt_compress_force:
468                 case Opt_compress_force_type:
469                         compress_force = true;
470                         /* Fallthrough */
471                 case Opt_compress:
472                 case Opt_compress_type:
473                         saved_compress_type = btrfs_test_opt(root, COMPRESS) ?
474                                 info->compress_type : BTRFS_COMPRESS_NONE;
475                         saved_compress_force =
476                                 btrfs_test_opt(root, FORCE_COMPRESS);
477                         if (token == Opt_compress ||
478                             token == Opt_compress_force ||
479                             strcmp(args[0].from, "zlib") == 0) {
480                                 compress_type = "zlib";
481                                 info->compress_type = BTRFS_COMPRESS_ZLIB;
482                                 btrfs_set_opt(info->mount_opt, COMPRESS);
483                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
484                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
485                                 no_compress = 0;
486                         } else if (strcmp(args[0].from, "lzo") == 0) {
487                                 compress_type = "lzo";
488                                 info->compress_type = BTRFS_COMPRESS_LZO;
489                                 btrfs_set_opt(info->mount_opt, COMPRESS);
490                                 btrfs_clear_opt(info->mount_opt, NODATACOW);
491                                 btrfs_clear_opt(info->mount_opt, NODATASUM);
492                                 btrfs_set_fs_incompat(info, COMPRESS_LZO);
493                                 no_compress = 0;
494                         } else if (strncmp(args[0].from, "no", 2) == 0) {
495                                 compress_type = "no";
496                                 btrfs_clear_opt(info->mount_opt, COMPRESS);
497                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
498                                 compress_force = false;
499                                 no_compress++;
500                         } else {
501                                 ret = -EINVAL;
502                                 goto out;
503                         }
504
505                         if (compress_force) {
506                                 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
507                         } else {
508                                 /*
509                                  * If we remount from compress-force=xxx to
510                                  * compress=xxx, we need clear FORCE_COMPRESS
511                                  * flag, otherwise, there is no way for users
512                                  * to disable forcible compression separately.
513                                  */
514                                 btrfs_clear_opt(info->mount_opt, FORCE_COMPRESS);
515                         }
516                         if ((btrfs_test_opt(root, COMPRESS) &&
517                              (info->compress_type != saved_compress_type ||
518                               compress_force != saved_compress_force)) ||
519                             (!btrfs_test_opt(root, COMPRESS) &&
520                              no_compress == 1)) {
521                                 btrfs_info(root->fs_info,
522                                            "%s %s compression",
523                                            (compress_force) ? "force" : "use",
524                                            compress_type);
525                         }
526                         compress_force = false;
527                         break;
528                 case Opt_ssd:
529                         btrfs_set_and_info(root, SSD,
530                                            "use ssd allocation scheme");
531                         break;
532                 case Opt_ssd_spread:
533                         btrfs_set_and_info(root, SSD_SPREAD,
534                                            "use spread ssd allocation scheme");
535                         btrfs_set_opt(info->mount_opt, SSD);
536                         break;
537                 case Opt_nossd:
538                         btrfs_set_and_info(root, NOSSD,
539                                              "not using ssd allocation scheme");
540                         btrfs_clear_opt(info->mount_opt, SSD);
541                         break;
542                 case Opt_barrier:
543                         btrfs_clear_and_info(root, NOBARRIER,
544                                              "turning on barriers");
545                         break;
546                 case Opt_nobarrier:
547                         btrfs_set_and_info(root, NOBARRIER,
548                                            "turning off barriers");
549                         break;
550                 case Opt_thread_pool:
551                         ret = match_int(&args[0], &intarg);
552                         if (ret) {
553                                 goto out;
554                         } else if (intarg > 0) {
555                                 info->thread_pool_size = intarg;
556                         } else {
557                                 ret = -EINVAL;
558                                 goto out;
559                         }
560                         break;
561                 case Opt_max_inline:
562                         num = match_strdup(&args[0]);
563                         if (num) {
564                                 info->max_inline = memparse(num, NULL);
565                                 kfree(num);
566
567                                 if (info->max_inline) {
568                                         info->max_inline = min_t(u64,
569                                                 info->max_inline,
570                                                 root->sectorsize);
571                                 }
572                                 btrfs_info(root->fs_info, "max_inline at %llu",
573                                         info->max_inline);
574                         } else {
575                                 ret = -ENOMEM;
576                                 goto out;
577                         }
578                         break;
579                 case Opt_alloc_start:
580                         num = match_strdup(&args[0]);
581                         if (num) {
582                                 mutex_lock(&info->chunk_mutex);
583                                 info->alloc_start = memparse(num, NULL);
584                                 mutex_unlock(&info->chunk_mutex);
585                                 kfree(num);
586                                 btrfs_info(root->fs_info, "allocations start at %llu",
587                                         info->alloc_start);
588                         } else {
589                                 ret = -ENOMEM;
590                                 goto out;
591                         }
592                         break;
593                 case Opt_acl:
594 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
595                         root->fs_info->sb->s_flags |= MS_POSIXACL;
596                         break;
597 #else
598                         btrfs_err(root->fs_info,
599                                 "support for ACL not compiled in!");
600                         ret = -EINVAL;
601                         goto out;
602 #endif
603                 case Opt_noacl:
604                         root->fs_info->sb->s_flags &= ~MS_POSIXACL;
605                         break;
606                 case Opt_notreelog:
607                         btrfs_set_and_info(root, NOTREELOG,
608                                            "disabling tree log");
609                         break;
610                 case Opt_treelog:
611                         btrfs_clear_and_info(root, NOTREELOG,
612                                              "enabling tree log");
613                         break;
614                 case Opt_norecovery:
615                 case Opt_nologreplay:
616                         btrfs_set_and_info(root, NOLOGREPLAY,
617                                            "disabling log replay at mount time");
618                         break;
619                 case Opt_flushoncommit:
620                         btrfs_set_and_info(root, FLUSHONCOMMIT,
621                                            "turning on flush-on-commit");
622                         break;
623                 case Opt_noflushoncommit:
624                         btrfs_clear_and_info(root, FLUSHONCOMMIT,
625                                              "turning off flush-on-commit");
626                         break;
627                 case Opt_ratio:
628                         ret = match_int(&args[0], &intarg);
629                         if (ret) {
630                                 goto out;
631                         } else if (intarg >= 0) {
632                                 info->metadata_ratio = intarg;
633                                 btrfs_info(root->fs_info, "metadata ratio %d",
634                                        info->metadata_ratio);
635                         } else {
636                                 ret = -EINVAL;
637                                 goto out;
638                         }
639                         break;
640                 case Opt_discard:
641                         btrfs_set_and_info(root, DISCARD,
642                                            "turning on discard");
643                         break;
644                 case Opt_nodiscard:
645                         btrfs_clear_and_info(root, DISCARD,
646                                              "turning off discard");
647                         break;
648                 case Opt_space_cache:
649                 case Opt_space_cache_version:
650                         if (token == Opt_space_cache ||
651                             strcmp(args[0].from, "v1") == 0) {
652                                 btrfs_clear_opt(root->fs_info->mount_opt,
653                                                 FREE_SPACE_TREE);
654                                 btrfs_set_and_info(root, SPACE_CACHE,
655                                                    "enabling disk space caching");
656                         } else if (strcmp(args[0].from, "v2") == 0) {
657                                 btrfs_clear_opt(root->fs_info->mount_opt,
658                                                 SPACE_CACHE);
659                                 btrfs_set_and_info(root, FREE_SPACE_TREE,
660                                                    "enabling free space tree");
661                         } else {
662                                 ret = -EINVAL;
663                                 goto out;
664                         }
665                         break;
666                 case Opt_rescan_uuid_tree:
667                         btrfs_set_opt(info->mount_opt, RESCAN_UUID_TREE);
668                         break;
669                 case Opt_no_space_cache:
670                         if (btrfs_test_opt(root, SPACE_CACHE)) {
671                                 btrfs_clear_and_info(root, SPACE_CACHE,
672                                                      "disabling disk space caching");
673                         }
674                         if (btrfs_test_opt(root, FREE_SPACE_TREE)) {
675                                 btrfs_clear_and_info(root, FREE_SPACE_TREE,
676                                                      "disabling free space tree");
677                         }
678                         break;
679                 case Opt_inode_cache:
680                         btrfs_set_pending_and_info(info, INODE_MAP_CACHE,
681                                            "enabling inode map caching");
682                         break;
683                 case Opt_noinode_cache:
684                         btrfs_clear_pending_and_info(info, INODE_MAP_CACHE,
685                                              "disabling inode map caching");
686                         break;
687                 case Opt_clear_cache:
688                         btrfs_set_and_info(root, CLEAR_CACHE,
689                                            "force clearing of disk cache");
690                         break;
691                 case Opt_user_subvol_rm_allowed:
692                         btrfs_set_opt(info->mount_opt, USER_SUBVOL_RM_ALLOWED);
693                         break;
694                 case Opt_enospc_debug:
695                         btrfs_set_opt(info->mount_opt, ENOSPC_DEBUG);
696                         break;
697                 case Opt_noenospc_debug:
698                         btrfs_clear_opt(info->mount_opt, ENOSPC_DEBUG);
699                         break;
700                 case Opt_defrag:
701                         btrfs_set_and_info(root, AUTO_DEFRAG,
702                                            "enabling auto defrag");
703                         break;
704                 case Opt_nodefrag:
705                         btrfs_clear_and_info(root, AUTO_DEFRAG,
706                                              "disabling auto defrag");
707                         break;
708                 case Opt_recovery:
709                         btrfs_warn(root->fs_info,
710                                    "'recovery' is deprecated, use 'usebackuproot' instead");
711                 case Opt_usebackuproot:
712                         btrfs_info(root->fs_info,
713                                    "trying to use backup root at mount time");
714                         btrfs_set_opt(info->mount_opt, USEBACKUPROOT);
715                         break;
716                 case Opt_skip_balance:
717                         btrfs_set_opt(info->mount_opt, SKIP_BALANCE);
718                         break;
719 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
720                 case Opt_check_integrity_including_extent_data:
721                         btrfs_info(root->fs_info,
722                                    "enabling check integrity including extent data");
723                         btrfs_set_opt(info->mount_opt,
724                                       CHECK_INTEGRITY_INCLUDING_EXTENT_DATA);
725                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
726                         break;
727                 case Opt_check_integrity:
728                         btrfs_info(root->fs_info, "enabling check integrity");
729                         btrfs_set_opt(info->mount_opt, CHECK_INTEGRITY);
730                         break;
731                 case Opt_check_integrity_print_mask:
732                         ret = match_int(&args[0], &intarg);
733                         if (ret) {
734                                 goto out;
735                         } else if (intarg >= 0) {
736                                 info->check_integrity_print_mask = intarg;
737                                 btrfs_info(root->fs_info, "check_integrity_print_mask 0x%x",
738                                        info->check_integrity_print_mask);
739                         } else {
740                                 ret = -EINVAL;
741                                 goto out;
742                         }
743                         break;
744 #else
745                 case Opt_check_integrity_including_extent_data:
746                 case Opt_check_integrity:
747                 case Opt_check_integrity_print_mask:
748                         btrfs_err(root->fs_info,
749                                 "support for check_integrity* not compiled in!");
750                         ret = -EINVAL;
751                         goto out;
752 #endif
753                 case Opt_fatal_errors:
754                         if (strcmp(args[0].from, "panic") == 0)
755                                 btrfs_set_opt(info->mount_opt,
756                                               PANIC_ON_FATAL_ERROR);
757                         else if (strcmp(args[0].from, "bug") == 0)
758                                 btrfs_clear_opt(info->mount_opt,
759                                               PANIC_ON_FATAL_ERROR);
760                         else {
761                                 ret = -EINVAL;
762                                 goto out;
763                         }
764                         break;
765                 case Opt_commit_interval:
766                         intarg = 0;
767                         ret = match_int(&args[0], &intarg);
768                         if (ret < 0) {
769                                 btrfs_err(root->fs_info, "invalid commit interval");
770                                 ret = -EINVAL;
771                                 goto out;
772                         }
773                         if (intarg > 0) {
774                                 if (intarg > 300) {
775                                         btrfs_warn(root->fs_info, "excessive commit interval %d",
776                                                         intarg);
777                                 }
778                                 info->commit_interval = intarg;
779                         } else {
780                                 btrfs_info(root->fs_info, "using default commit interval %ds",
781                                     BTRFS_DEFAULT_COMMIT_INTERVAL);
782                                 info->commit_interval = BTRFS_DEFAULT_COMMIT_INTERVAL;
783                         }
784                         break;
785 #ifdef CONFIG_BTRFS_DEBUG
786                 case Opt_fragment_all:
787                         btrfs_info(root->fs_info, "fragmenting all space");
788                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
789                         btrfs_set_opt(info->mount_opt, FRAGMENT_METADATA);
790                         break;
791                 case Opt_fragment_metadata:
792                         btrfs_info(root->fs_info, "fragmenting metadata");
793                         btrfs_set_opt(info->mount_opt,
794                                       FRAGMENT_METADATA);
795                         break;
796                 case Opt_fragment_data:
797                         btrfs_info(root->fs_info, "fragmenting data");
798                         btrfs_set_opt(info->mount_opt, FRAGMENT_DATA);
799                         break;
800 #endif
801                 case Opt_err:
802                         btrfs_info(root->fs_info, "unrecognized mount option '%s'", p);
803                         ret = -EINVAL;
804                         goto out;
805                 default:
806                         break;
807                 }
808         }
809 check:
810         /*
811          * Extra check for current option against current flag
812          */
813         if (btrfs_test_opt(root, NOLOGREPLAY) && !(new_flags & MS_RDONLY)) {
814                 btrfs_err(root->fs_info,
815                           "nologreplay must be used with ro mount option");
816                 ret = -EINVAL;
817         }
818 out:
819         if (btrfs_fs_compat_ro(root->fs_info, FREE_SPACE_TREE) &&
820             !btrfs_test_opt(root, FREE_SPACE_TREE) &&
821             !btrfs_test_opt(root, CLEAR_CACHE)) {
822                 btrfs_err(root->fs_info, "cannot disable free space tree");
823                 ret = -EINVAL;
824
825         }
826         if (!ret && btrfs_test_opt(root, SPACE_CACHE))
827                 btrfs_info(root->fs_info, "disk space caching is enabled");
828         if (!ret && btrfs_test_opt(root, FREE_SPACE_TREE))
829                 btrfs_info(root->fs_info, "using free space tree");
830         kfree(orig);
831         return ret;
832 }
833
834 /*
835  * Parse mount options that are required early in the mount process.
836  *
837  * All other options will be parsed on much later in the mount process and
838  * only when we need to allocate a new super block.
839  */
840 static int btrfs_parse_early_options(const char *options, fmode_t flags,
841                 void *holder, char **subvol_name, u64 *subvol_objectid,
842                 struct btrfs_fs_devices **fs_devices)
843 {
844         substring_t args[MAX_OPT_ARGS];
845         char *device_name, *opts, *orig, *p;
846         char *num = NULL;
847         int error = 0;
848
849         if (!options)
850                 return 0;
851
852         /*
853          * strsep changes the string, duplicate it because parse_options
854          * gets called twice
855          */
856         opts = kstrdup(options, GFP_KERNEL);
857         if (!opts)
858                 return -ENOMEM;
859         orig = opts;
860
861         while ((p = strsep(&opts, ",")) != NULL) {
862                 int token;
863                 if (!*p)
864                         continue;
865
866                 token = match_token(p, tokens, args);
867                 switch (token) {
868                 case Opt_subvol:
869                         kfree(*subvol_name);
870                         *subvol_name = match_strdup(&args[0]);
871                         if (!*subvol_name) {
872                                 error = -ENOMEM;
873                                 goto out;
874                         }
875                         break;
876                 case Opt_subvolid:
877                         num = match_strdup(&args[0]);
878                         if (num) {
879                                 *subvol_objectid = memparse(num, NULL);
880                                 kfree(num);
881                                 /* we want the original fs_tree */
882                                 if (!*subvol_objectid)
883                                         *subvol_objectid =
884                                                 BTRFS_FS_TREE_OBJECTID;
885                         } else {
886                                 error = -EINVAL;
887                                 goto out;
888                         }
889                         break;
890                 case Opt_subvolrootid:
891                         printk(KERN_WARNING
892                                 "BTRFS: 'subvolrootid' mount option is deprecated and has "
893                                 "no effect\n");
894                         break;
895                 case Opt_device:
896                         device_name = match_strdup(&args[0]);
897                         if (!device_name) {
898                                 error = -ENOMEM;
899                                 goto out;
900                         }
901                         error = btrfs_scan_one_device(device_name,
902                                         flags, holder, fs_devices);
903                         kfree(device_name);
904                         if (error)
905                                 goto out;
906                         break;
907                 default:
908                         break;
909                 }
910         }
911
912 out:
913         kfree(orig);
914         return error;
915 }
916
917 static char *get_subvol_name_from_objectid(struct btrfs_fs_info *fs_info,
918                                            u64 subvol_objectid)
919 {
920         struct btrfs_root *root = fs_info->tree_root;
921         struct btrfs_root *fs_root;
922         struct btrfs_root_ref *root_ref;
923         struct btrfs_inode_ref *inode_ref;
924         struct btrfs_key key;
925         struct btrfs_path *path = NULL;
926         char *name = NULL, *ptr;
927         u64 dirid;
928         int len;
929         int ret;
930
931         path = btrfs_alloc_path();
932         if (!path) {
933                 ret = -ENOMEM;
934                 goto err;
935         }
936         path->leave_spinning = 1;
937
938         name = kmalloc(PATH_MAX, GFP_NOFS);
939         if (!name) {
940                 ret = -ENOMEM;
941                 goto err;
942         }
943         ptr = name + PATH_MAX - 1;
944         ptr[0] = '\0';
945
946         /*
947          * Walk up the subvolume trees in the tree of tree roots by root
948          * backrefs until we hit the top-level subvolume.
949          */
950         while (subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
951                 key.objectid = subvol_objectid;
952                 key.type = BTRFS_ROOT_BACKREF_KEY;
953                 key.offset = (u64)-1;
954
955                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
956                 if (ret < 0) {
957                         goto err;
958                 } else if (ret > 0) {
959                         ret = btrfs_previous_item(root, path, subvol_objectid,
960                                                   BTRFS_ROOT_BACKREF_KEY);
961                         if (ret < 0) {
962                                 goto err;
963                         } else if (ret > 0) {
964                                 ret = -ENOENT;
965                                 goto err;
966                         }
967                 }
968
969                 btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
970                 subvol_objectid = key.offset;
971
972                 root_ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
973                                           struct btrfs_root_ref);
974                 len = btrfs_root_ref_name_len(path->nodes[0], root_ref);
975                 ptr -= len + 1;
976                 if (ptr < name) {
977                         ret = -ENAMETOOLONG;
978                         goto err;
979                 }
980                 read_extent_buffer(path->nodes[0], ptr + 1,
981                                    (unsigned long)(root_ref + 1), len);
982                 ptr[0] = '/';
983                 dirid = btrfs_root_ref_dirid(path->nodes[0], root_ref);
984                 btrfs_release_path(path);
985
986                 key.objectid = subvol_objectid;
987                 key.type = BTRFS_ROOT_ITEM_KEY;
988                 key.offset = (u64)-1;
989                 fs_root = btrfs_read_fs_root_no_name(fs_info, &key);
990                 if (IS_ERR(fs_root)) {
991                         ret = PTR_ERR(fs_root);
992                         goto err;
993                 }
994
995                 /*
996                  * Walk up the filesystem tree by inode refs until we hit the
997                  * root directory.
998                  */
999                 while (dirid != BTRFS_FIRST_FREE_OBJECTID) {
1000                         key.objectid = dirid;
1001                         key.type = BTRFS_INODE_REF_KEY;
1002                         key.offset = (u64)-1;
1003
1004                         ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
1005                         if (ret < 0) {
1006                                 goto err;
1007                         } else if (ret > 0) {
1008                                 ret = btrfs_previous_item(fs_root, path, dirid,
1009                                                           BTRFS_INODE_REF_KEY);
1010                                 if (ret < 0) {
1011                                         goto err;
1012                                 } else if (ret > 0) {
1013                                         ret = -ENOENT;
1014                                         goto err;
1015                                 }
1016                         }
1017
1018                         btrfs_item_key_to_cpu(path->nodes[0], &key, path->slots[0]);
1019                         dirid = key.offset;
1020
1021                         inode_ref = btrfs_item_ptr(path->nodes[0],
1022                                                    path->slots[0],
1023                                                    struct btrfs_inode_ref);
1024                         len = btrfs_inode_ref_name_len(path->nodes[0],
1025                                                        inode_ref);
1026                         ptr -= len + 1;
1027                         if (ptr < name) {
1028                                 ret = -ENAMETOOLONG;
1029                                 goto err;
1030                         }
1031                         read_extent_buffer(path->nodes[0], ptr + 1,
1032                                            (unsigned long)(inode_ref + 1), len);
1033                         ptr[0] = '/';
1034                         btrfs_release_path(path);
1035                 }
1036         }
1037
1038         btrfs_free_path(path);
1039         if (ptr == name + PATH_MAX - 1) {
1040                 name[0] = '/';
1041                 name[1] = '\0';
1042         } else {
1043                 memmove(name, ptr, name + PATH_MAX - ptr);
1044         }
1045         return name;
1046
1047 err:
1048         btrfs_free_path(path);
1049         kfree(name);
1050         return ERR_PTR(ret);
1051 }
1052
1053 static int get_default_subvol_objectid(struct btrfs_fs_info *fs_info, u64 *objectid)
1054 {
1055         struct btrfs_root *root = fs_info->tree_root;
1056         struct btrfs_dir_item *di;
1057         struct btrfs_path *path;
1058         struct btrfs_key location;
1059         u64 dir_id;
1060
1061         path = btrfs_alloc_path();
1062         if (!path)
1063                 return -ENOMEM;
1064         path->leave_spinning = 1;
1065
1066         /*
1067          * Find the "default" dir item which points to the root item that we
1068          * will mount by default if we haven't been given a specific subvolume
1069          * to mount.
1070          */
1071         dir_id = btrfs_super_root_dir(fs_info->super_copy);
1072         di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
1073         if (IS_ERR(di)) {
1074                 btrfs_free_path(path);
1075                 return PTR_ERR(di);
1076         }
1077         if (!di) {
1078                 /*
1079                  * Ok the default dir item isn't there.  This is weird since
1080                  * it's always been there, but don't freak out, just try and
1081                  * mount the top-level subvolume.
1082                  */
1083                 btrfs_free_path(path);
1084                 *objectid = BTRFS_FS_TREE_OBJECTID;
1085                 return 0;
1086         }
1087
1088         btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
1089         btrfs_free_path(path);
1090         *objectid = location.objectid;
1091         return 0;
1092 }
1093
1094 static int btrfs_fill_super(struct super_block *sb,
1095                             struct btrfs_fs_devices *fs_devices,
1096                             void *data, int silent)
1097 {
1098         struct inode *inode;
1099         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1100         struct btrfs_key key;
1101         int err;
1102
1103         sb->s_maxbytes = MAX_LFS_FILESIZE;
1104         sb->s_magic = BTRFS_SUPER_MAGIC;
1105         sb->s_op = &btrfs_super_ops;
1106         sb->s_d_op = &btrfs_dentry_operations;
1107         sb->s_export_op = &btrfs_export_ops;
1108         sb->s_xattr = btrfs_xattr_handlers;
1109         sb->s_time_gran = 1;
1110 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
1111         sb->s_flags |= MS_POSIXACL;
1112 #endif
1113         sb->s_flags |= MS_I_VERSION;
1114         sb->s_iflags |= SB_I_CGROUPWB;
1115         err = open_ctree(sb, fs_devices, (char *)data);
1116         if (err) {
1117                 printk(KERN_ERR "BTRFS: open_ctree failed\n");
1118                 return err;
1119         }
1120
1121         key.objectid = BTRFS_FIRST_FREE_OBJECTID;
1122         key.type = BTRFS_INODE_ITEM_KEY;
1123         key.offset = 0;
1124         inode = btrfs_iget(sb, &key, fs_info->fs_root, NULL);
1125         if (IS_ERR(inode)) {
1126                 err = PTR_ERR(inode);
1127                 goto fail_close;
1128         }
1129
1130         sb->s_root = d_make_root(inode);
1131         if (!sb->s_root) {
1132                 err = -ENOMEM;
1133                 goto fail_close;
1134         }
1135
1136         save_mount_options(sb, data);
1137         cleancache_init_fs(sb);
1138         sb->s_flags |= MS_ACTIVE;
1139         return 0;
1140
1141 fail_close:
1142         close_ctree(fs_info->tree_root);
1143         return err;
1144 }
1145
1146 int btrfs_sync_fs(struct super_block *sb, int wait)
1147 {
1148         struct btrfs_trans_handle *trans;
1149         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1150         struct btrfs_root *root = fs_info->tree_root;
1151
1152         trace_btrfs_sync_fs(wait);
1153
1154         if (!wait) {
1155                 filemap_flush(fs_info->btree_inode->i_mapping);
1156                 return 0;
1157         }
1158
1159         btrfs_wait_ordered_roots(fs_info, -1, 0, (u64)-1);
1160
1161         trans = btrfs_attach_transaction_barrier(root);
1162         if (IS_ERR(trans)) {
1163                 /* no transaction, don't bother */
1164                 if (PTR_ERR(trans) == -ENOENT) {
1165                         /*
1166                          * Exit unless we have some pending changes
1167                          * that need to go through commit
1168                          */
1169                         if (fs_info->pending_changes == 0)
1170                                 return 0;
1171                         /*
1172                          * A non-blocking test if the fs is frozen. We must not
1173                          * start a new transaction here otherwise a deadlock
1174                          * happens. The pending operations are delayed to the
1175                          * next commit after thawing.
1176                          */
1177                         if (__sb_start_write(sb, SB_FREEZE_WRITE, false))
1178                                 __sb_end_write(sb, SB_FREEZE_WRITE);
1179                         else
1180                                 return 0;
1181                         trans = btrfs_start_transaction(root, 0);
1182                 }
1183                 if (IS_ERR(trans))
1184                         return PTR_ERR(trans);
1185         }
1186         return btrfs_commit_transaction(trans, root);
1187 }
1188
1189 static int btrfs_show_options(struct seq_file *seq, struct dentry *dentry)
1190 {
1191         struct btrfs_fs_info *info = btrfs_sb(dentry->d_sb);
1192         struct btrfs_root *root = info->tree_root;
1193         char *compress_type;
1194
1195         if (btrfs_test_opt(root, DEGRADED))
1196                 seq_puts(seq, ",degraded");
1197         if (btrfs_test_opt(root, NODATASUM))
1198                 seq_puts(seq, ",nodatasum");
1199         if (btrfs_test_opt(root, NODATACOW))
1200                 seq_puts(seq, ",nodatacow");
1201         if (btrfs_test_opt(root, NOBARRIER))
1202                 seq_puts(seq, ",nobarrier");
1203         if (info->max_inline != BTRFS_DEFAULT_MAX_INLINE)
1204                 seq_printf(seq, ",max_inline=%llu", info->max_inline);
1205         if (info->alloc_start != 0)
1206                 seq_printf(seq, ",alloc_start=%llu", info->alloc_start);
1207         if (info->thread_pool_size !=  min_t(unsigned long,
1208                                              num_online_cpus() + 2, 8))
1209                 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
1210         if (btrfs_test_opt(root, COMPRESS)) {
1211                 if (info->compress_type == BTRFS_COMPRESS_ZLIB)
1212                         compress_type = "zlib";
1213                 else
1214                         compress_type = "lzo";
1215                 if (btrfs_test_opt(root, FORCE_COMPRESS))
1216                         seq_printf(seq, ",compress-force=%s", compress_type);
1217                 else
1218                         seq_printf(seq, ",compress=%s", compress_type);
1219         }
1220         if (btrfs_test_opt(root, NOSSD))
1221                 seq_puts(seq, ",nossd");
1222         if (btrfs_test_opt(root, SSD_SPREAD))
1223                 seq_puts(seq, ",ssd_spread");
1224         else if (btrfs_test_opt(root, SSD))
1225                 seq_puts(seq, ",ssd");
1226         if (btrfs_test_opt(root, NOTREELOG))
1227                 seq_puts(seq, ",notreelog");
1228         if (btrfs_test_opt(root, NOLOGREPLAY))
1229                 seq_puts(seq, ",nologreplay");
1230         if (btrfs_test_opt(root, FLUSHONCOMMIT))
1231                 seq_puts(seq, ",flushoncommit");
1232         if (btrfs_test_opt(root, DISCARD))
1233                 seq_puts(seq, ",discard");
1234         if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
1235                 seq_puts(seq, ",noacl");
1236         if (btrfs_test_opt(root, SPACE_CACHE))
1237                 seq_puts(seq, ",space_cache");
1238         else if (btrfs_test_opt(root, FREE_SPACE_TREE))
1239                 seq_puts(seq, ",space_cache=v2");
1240         else
1241                 seq_puts(seq, ",nospace_cache");
1242         if (btrfs_test_opt(root, RESCAN_UUID_TREE))
1243                 seq_puts(seq, ",rescan_uuid_tree");
1244         if (btrfs_test_opt(root, CLEAR_CACHE))
1245                 seq_puts(seq, ",clear_cache");
1246         if (btrfs_test_opt(root, USER_SUBVOL_RM_ALLOWED))
1247                 seq_puts(seq, ",user_subvol_rm_allowed");
1248         if (btrfs_test_opt(root, ENOSPC_DEBUG))
1249                 seq_puts(seq, ",enospc_debug");
1250         if (btrfs_test_opt(root, AUTO_DEFRAG))
1251                 seq_puts(seq, ",autodefrag");
1252         if (btrfs_test_opt(root, INODE_MAP_CACHE))
1253                 seq_puts(seq, ",inode_cache");
1254         if (btrfs_test_opt(root, SKIP_BALANCE))
1255                 seq_puts(seq, ",skip_balance");
1256 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
1257         if (btrfs_test_opt(root, CHECK_INTEGRITY_INCLUDING_EXTENT_DATA))
1258                 seq_puts(seq, ",check_int_data");
1259         else if (btrfs_test_opt(root, CHECK_INTEGRITY))
1260                 seq_puts(seq, ",check_int");
1261         if (info->check_integrity_print_mask)
1262                 seq_printf(seq, ",check_int_print_mask=%d",
1263                                 info->check_integrity_print_mask);
1264 #endif
1265         if (info->metadata_ratio)
1266                 seq_printf(seq, ",metadata_ratio=%d",
1267                                 info->metadata_ratio);
1268         if (btrfs_test_opt(root, PANIC_ON_FATAL_ERROR))
1269                 seq_puts(seq, ",fatal_errors=panic");
1270         if (info->commit_interval != BTRFS_DEFAULT_COMMIT_INTERVAL)
1271                 seq_printf(seq, ",commit=%d", info->commit_interval);
1272 #ifdef CONFIG_BTRFS_DEBUG
1273         if (btrfs_test_opt(root, FRAGMENT_DATA))
1274                 seq_puts(seq, ",fragment=data");
1275         if (btrfs_test_opt(root, FRAGMENT_METADATA))
1276                 seq_puts(seq, ",fragment=metadata");
1277 #endif
1278         seq_printf(seq, ",subvolid=%llu",
1279                   BTRFS_I(d_inode(dentry))->root->root_key.objectid);
1280         seq_puts(seq, ",subvol=");
1281         seq_dentry(seq, dentry, " \t\n\\");
1282         return 0;
1283 }
1284
1285 static int btrfs_test_super(struct super_block *s, void *data)
1286 {
1287         struct btrfs_fs_info *p = data;
1288         struct btrfs_fs_info *fs_info = btrfs_sb(s);
1289
1290         return fs_info->fs_devices == p->fs_devices;
1291 }
1292
1293 static int btrfs_set_super(struct super_block *s, void *data)
1294 {
1295         int err = set_anon_super(s, data);
1296         if (!err)
1297                 s->s_fs_info = data;
1298         return err;
1299 }
1300
1301 /*
1302  * subvolumes are identified by ino 256
1303  */
1304 static inline int is_subvolume_inode(struct inode *inode)
1305 {
1306         if (inode && inode->i_ino == BTRFS_FIRST_FREE_OBJECTID)
1307                 return 1;
1308         return 0;
1309 }
1310
1311 /*
1312  * This will add subvolid=0 to the argument string while removing any subvol=
1313  * and subvolid= arguments to make sure we get the top-level root for path
1314  * walking to the subvol we want.
1315  */
1316 static char *setup_root_args(char *args)
1317 {
1318         char *buf, *dst, *sep;
1319
1320         if (!args)
1321                 return kstrdup("subvolid=0", GFP_NOFS);
1322
1323         /* The worst case is that we add ",subvolid=0" to the end. */
1324         buf = dst = kmalloc(strlen(args) + strlen(",subvolid=0") + 1, GFP_NOFS);
1325         if (!buf)
1326                 return NULL;
1327
1328         while (1) {
1329                 sep = strchrnul(args, ',');
1330                 if (!strstarts(args, "subvol=") &&
1331                     !strstarts(args, "subvolid=")) {
1332                         memcpy(dst, args, sep - args);
1333                         dst += sep - args;
1334                         *dst++ = ',';
1335                 }
1336                 if (*sep)
1337                         args = sep + 1;
1338                 else
1339                         break;
1340         }
1341         strcpy(dst, "subvolid=0");
1342
1343         return buf;
1344 }
1345
1346 static struct dentry *mount_subvol(const char *subvol_name, u64 subvol_objectid,
1347                                    int flags, const char *device_name,
1348                                    char *data)
1349 {
1350         struct dentry *root;
1351         struct vfsmount *mnt = NULL;
1352         char *newargs;
1353         int ret;
1354
1355         newargs = setup_root_args(data);
1356         if (!newargs) {
1357                 root = ERR_PTR(-ENOMEM);
1358                 goto out;
1359         }
1360
1361         mnt = vfs_kern_mount(&btrfs_fs_type, flags, device_name, newargs);
1362         if (PTR_ERR_OR_ZERO(mnt) == -EBUSY) {
1363                 if (flags & MS_RDONLY) {
1364                         mnt = vfs_kern_mount(&btrfs_fs_type, flags & ~MS_RDONLY,
1365                                              device_name, newargs);
1366                 } else {
1367                         mnt = vfs_kern_mount(&btrfs_fs_type, flags | MS_RDONLY,
1368                                              device_name, newargs);
1369                         if (IS_ERR(mnt)) {
1370                                 root = ERR_CAST(mnt);
1371                                 mnt = NULL;
1372                                 goto out;
1373                         }
1374
1375                         down_write(&mnt->mnt_sb->s_umount);
1376                         ret = btrfs_remount(mnt->mnt_sb, &flags, NULL);
1377                         up_write(&mnt->mnt_sb->s_umount);
1378                         if (ret < 0) {
1379                                 root = ERR_PTR(ret);
1380                                 goto out;
1381                         }
1382                 }
1383         }
1384         if (IS_ERR(mnt)) {
1385                 root = ERR_CAST(mnt);
1386                 mnt = NULL;
1387                 goto out;
1388         }
1389
1390         if (!subvol_name) {
1391                 if (!subvol_objectid) {
1392                         ret = get_default_subvol_objectid(btrfs_sb(mnt->mnt_sb),
1393                                                           &subvol_objectid);
1394                         if (ret) {
1395                                 root = ERR_PTR(ret);
1396                                 goto out;
1397                         }
1398                 }
1399                 subvol_name = get_subvol_name_from_objectid(btrfs_sb(mnt->mnt_sb),
1400                                                             subvol_objectid);
1401                 if (IS_ERR(subvol_name)) {
1402                         root = ERR_CAST(subvol_name);
1403                         subvol_name = NULL;
1404                         goto out;
1405                 }
1406
1407         }
1408
1409         root = mount_subtree(mnt, subvol_name);
1410         /* mount_subtree() drops our reference on the vfsmount. */
1411         mnt = NULL;
1412
1413         if (!IS_ERR(root)) {
1414                 struct super_block *s = root->d_sb;
1415                 struct inode *root_inode = d_inode(root);
1416                 u64 root_objectid = BTRFS_I(root_inode)->root->root_key.objectid;
1417
1418                 ret = 0;
1419                 if (!is_subvolume_inode(root_inode)) {
1420                         pr_err("BTRFS: '%s' is not a valid subvolume\n",
1421                                subvol_name);
1422                         ret = -EINVAL;
1423                 }
1424                 if (subvol_objectid && root_objectid != subvol_objectid) {
1425                         /*
1426                          * This will also catch a race condition where a
1427                          * subvolume which was passed by ID is renamed and
1428                          * another subvolume is renamed over the old location.
1429                          */
1430                         pr_err("BTRFS: subvol '%s' does not match subvolid %llu\n",
1431                                subvol_name, subvol_objectid);
1432                         ret = -EINVAL;
1433                 }
1434                 if (ret) {
1435                         dput(root);
1436                         root = ERR_PTR(ret);
1437                         deactivate_locked_super(s);
1438                 }
1439         }
1440
1441 out:
1442         mntput(mnt);
1443         kfree(newargs);
1444         kfree(subvol_name);
1445         return root;
1446 }
1447
1448 static int parse_security_options(char *orig_opts,
1449                                   struct security_mnt_opts *sec_opts)
1450 {
1451         char *secdata = NULL;
1452         int ret = 0;
1453
1454         secdata = alloc_secdata();
1455         if (!secdata)
1456                 return -ENOMEM;
1457         ret = security_sb_copy_data(orig_opts, secdata);
1458         if (ret) {
1459                 free_secdata(secdata);
1460                 return ret;
1461         }
1462         ret = security_sb_parse_opts_str(secdata, sec_opts);
1463         free_secdata(secdata);
1464         return ret;
1465 }
1466
1467 static int setup_security_options(struct btrfs_fs_info *fs_info,
1468                                   struct super_block *sb,
1469                                   struct security_mnt_opts *sec_opts)
1470 {
1471         int ret = 0;
1472
1473         /*
1474          * Call security_sb_set_mnt_opts() to check whether new sec_opts
1475          * is valid.
1476          */
1477         ret = security_sb_set_mnt_opts(sb, sec_opts, 0, NULL);
1478         if (ret)
1479                 return ret;
1480
1481 #ifdef CONFIG_SECURITY
1482         if (!fs_info->security_opts.num_mnt_opts) {
1483                 /* first time security setup, copy sec_opts to fs_info */
1484                 memcpy(&fs_info->security_opts, sec_opts, sizeof(*sec_opts));
1485         } else {
1486                 /*
1487                  * Since SELinux (the only one supporting security_mnt_opts)
1488                  * does NOT support changing context during remount/mount of
1489                  * the same sb, this must be the same or part of the same
1490                  * security options, just free it.
1491                  */
1492                 security_free_mnt_opts(sec_opts);
1493         }
1494 #endif
1495         return ret;
1496 }
1497
1498 /*
1499  * Find a superblock for the given device / mount point.
1500  *
1501  * Note:  This is based on get_sb_bdev from fs/super.c with a few additions
1502  *        for multiple device setup.  Make sure to keep it in sync.
1503  */
1504 static struct dentry *btrfs_mount(struct file_system_type *fs_type, int flags,
1505                 const char *device_name, void *data)
1506 {
1507         struct block_device *bdev = NULL;
1508         struct super_block *s;
1509         struct btrfs_fs_devices *fs_devices = NULL;
1510         struct btrfs_fs_info *fs_info = NULL;
1511         struct security_mnt_opts new_sec_opts;
1512         fmode_t mode = FMODE_READ;
1513         char *subvol_name = NULL;
1514         u64 subvol_objectid = 0;
1515         int error = 0;
1516
1517         if (!(flags & MS_RDONLY))
1518                 mode |= FMODE_WRITE;
1519
1520         error = btrfs_parse_early_options(data, mode, fs_type,
1521                                           &subvol_name, &subvol_objectid,
1522                                           &fs_devices);
1523         if (error) {
1524                 kfree(subvol_name);
1525                 return ERR_PTR(error);
1526         }
1527
1528         if (subvol_name || subvol_objectid != BTRFS_FS_TREE_OBJECTID) {
1529                 /* mount_subvol() will free subvol_name. */
1530                 return mount_subvol(subvol_name, subvol_objectid, flags,
1531                                     device_name, data);
1532         }
1533
1534         security_init_mnt_opts(&new_sec_opts);
1535         if (data) {
1536                 error = parse_security_options(data, &new_sec_opts);
1537                 if (error)
1538                         return ERR_PTR(error);
1539         }
1540
1541         error = btrfs_scan_one_device(device_name, mode, fs_type, &fs_devices);
1542         if (error)
1543                 goto error_sec_opts;
1544
1545         /*
1546          * Setup a dummy root and fs_info for test/set super.  This is because
1547          * we don't actually fill this stuff out until open_ctree, but we need
1548          * it for searching for existing supers, so this lets us do that and
1549          * then open_ctree will properly initialize everything later.
1550          */
1551         fs_info = kzalloc(sizeof(struct btrfs_fs_info), GFP_NOFS);
1552         if (!fs_info) {
1553                 error = -ENOMEM;
1554                 goto error_sec_opts;
1555         }
1556
1557         fs_info->fs_devices = fs_devices;
1558
1559         fs_info->super_copy = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1560         fs_info->super_for_commit = kzalloc(BTRFS_SUPER_INFO_SIZE, GFP_NOFS);
1561         security_init_mnt_opts(&fs_info->security_opts);
1562         if (!fs_info->super_copy || !fs_info->super_for_commit) {
1563                 error = -ENOMEM;
1564                 goto error_fs_info;
1565         }
1566
1567         error = btrfs_open_devices(fs_devices, mode, fs_type);
1568         if (error)
1569                 goto error_fs_info;
1570
1571         if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
1572                 error = -EACCES;
1573                 goto error_close_devices;
1574         }
1575
1576         bdev = fs_devices->latest_bdev;
1577         s = sget(fs_type, btrfs_test_super, btrfs_set_super, flags | MS_NOSEC,
1578                  fs_info);
1579         if (IS_ERR(s)) {
1580                 error = PTR_ERR(s);
1581                 goto error_close_devices;
1582         }
1583
1584         if (s->s_root) {
1585                 btrfs_close_devices(fs_devices);
1586                 free_fs_info(fs_info);
1587                 if ((flags ^ s->s_flags) & MS_RDONLY)
1588                         error = -EBUSY;
1589         } else {
1590                 snprintf(s->s_id, sizeof(s->s_id), "%pg", bdev);
1591                 btrfs_sb(s)->bdev_holder = fs_type;
1592                 error = btrfs_fill_super(s, fs_devices, data,
1593                                          flags & MS_SILENT ? 1 : 0);
1594         }
1595         if (error) {
1596                 deactivate_locked_super(s);
1597                 goto error_sec_opts;
1598         }
1599
1600         fs_info = btrfs_sb(s);
1601         error = setup_security_options(fs_info, s, &new_sec_opts);
1602         if (error) {
1603                 deactivate_locked_super(s);
1604                 goto error_sec_opts;
1605         }
1606
1607         return dget(s->s_root);
1608
1609 error_close_devices:
1610         btrfs_close_devices(fs_devices);
1611 error_fs_info:
1612         free_fs_info(fs_info);
1613 error_sec_opts:
1614         security_free_mnt_opts(&new_sec_opts);
1615         return ERR_PTR(error);
1616 }
1617
1618 static void btrfs_resize_thread_pool(struct btrfs_fs_info *fs_info,
1619                                      int new_pool_size, int old_pool_size)
1620 {
1621         if (new_pool_size == old_pool_size)
1622                 return;
1623
1624         fs_info->thread_pool_size = new_pool_size;
1625
1626         btrfs_info(fs_info, "resize thread pool %d -> %d",
1627                old_pool_size, new_pool_size);
1628
1629         btrfs_workqueue_set_max(fs_info->workers, new_pool_size);
1630         btrfs_workqueue_set_max(fs_info->delalloc_workers, new_pool_size);
1631         btrfs_workqueue_set_max(fs_info->submit_workers, new_pool_size);
1632         btrfs_workqueue_set_max(fs_info->caching_workers, new_pool_size);
1633         btrfs_workqueue_set_max(fs_info->endio_workers, new_pool_size);
1634         btrfs_workqueue_set_max(fs_info->endio_meta_workers, new_pool_size);
1635         btrfs_workqueue_set_max(fs_info->endio_meta_write_workers,
1636                                 new_pool_size);
1637         btrfs_workqueue_set_max(fs_info->endio_write_workers, new_pool_size);
1638         btrfs_workqueue_set_max(fs_info->endio_freespace_worker, new_pool_size);
1639         btrfs_workqueue_set_max(fs_info->delayed_workers, new_pool_size);
1640         btrfs_workqueue_set_max(fs_info->readahead_workers, new_pool_size);
1641         btrfs_workqueue_set_max(fs_info->scrub_wr_completion_workers,
1642                                 new_pool_size);
1643 }
1644
1645 static inline void btrfs_remount_prepare(struct btrfs_fs_info *fs_info)
1646 {
1647         set_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1648 }
1649
1650 static inline void btrfs_remount_begin(struct btrfs_fs_info *fs_info,
1651                                        unsigned long old_opts, int flags)
1652 {
1653         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1654             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1655              (flags & MS_RDONLY))) {
1656                 /* wait for any defraggers to finish */
1657                 wait_event(fs_info->transaction_wait,
1658                            (atomic_read(&fs_info->defrag_running) == 0));
1659                 if (flags & MS_RDONLY)
1660                         sync_filesystem(fs_info->sb);
1661         }
1662 }
1663
1664 static inline void btrfs_remount_cleanup(struct btrfs_fs_info *fs_info,
1665                                          unsigned long old_opts)
1666 {
1667         /*
1668          * We need to cleanup all defragable inodes if the autodefragment is
1669          * close or the filesystem is read only.
1670          */
1671         if (btrfs_raw_test_opt(old_opts, AUTO_DEFRAG) &&
1672             (!btrfs_raw_test_opt(fs_info->mount_opt, AUTO_DEFRAG) ||
1673              (fs_info->sb->s_flags & MS_RDONLY))) {
1674                 btrfs_cleanup_defrag_inodes(fs_info);
1675         }
1676
1677         clear_bit(BTRFS_FS_STATE_REMOUNTING, &fs_info->fs_state);
1678 }
1679
1680 static int btrfs_remount(struct super_block *sb, int *flags, char *data)
1681 {
1682         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
1683         struct btrfs_root *root = fs_info->tree_root;
1684         unsigned old_flags = sb->s_flags;
1685         unsigned long old_opts = fs_info->mount_opt;
1686         unsigned long old_compress_type = fs_info->compress_type;
1687         u64 old_max_inline = fs_info->max_inline;
1688         u64 old_alloc_start = fs_info->alloc_start;
1689         int old_thread_pool_size = fs_info->thread_pool_size;
1690         unsigned int old_metadata_ratio = fs_info->metadata_ratio;
1691         int ret;
1692
1693         sync_filesystem(sb);
1694         btrfs_remount_prepare(fs_info);
1695
1696         if (data) {
1697                 struct security_mnt_opts new_sec_opts;
1698
1699                 security_init_mnt_opts(&new_sec_opts);
1700                 ret = parse_security_options(data, &new_sec_opts);
1701                 if (ret)
1702                         goto restore;
1703                 ret = setup_security_options(fs_info, sb,
1704                                              &new_sec_opts);
1705                 if (ret) {
1706                         security_free_mnt_opts(&new_sec_opts);
1707                         goto restore;
1708                 }
1709         }
1710
1711         ret = btrfs_parse_options(root, data, *flags);
1712         if (ret) {
1713                 ret = -EINVAL;
1714                 goto restore;
1715         }
1716
1717         btrfs_remount_begin(fs_info, old_opts, *flags);
1718         btrfs_resize_thread_pool(fs_info,
1719                 fs_info->thread_pool_size, old_thread_pool_size);
1720
1721         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
1722                 goto out;
1723
1724         if (*flags & MS_RDONLY) {
1725                 /*
1726                  * this also happens on 'umount -rf' or on shutdown, when
1727                  * the filesystem is busy.
1728                  */
1729                 cancel_work_sync(&fs_info->async_reclaim_work);
1730
1731                 /* wait for the uuid_scan task to finish */
1732                 down(&fs_info->uuid_tree_rescan_sem);
1733                 /* avoid complains from lockdep et al. */
1734                 up(&fs_info->uuid_tree_rescan_sem);
1735
1736                 sb->s_flags |= MS_RDONLY;
1737
1738                 /*
1739                  * Setting MS_RDONLY will put the cleaner thread to
1740                  * sleep at the next loop if it's already active.
1741                  * If it's already asleep, we'll leave unused block
1742                  * groups on disk until we're mounted read-write again
1743                  * unless we clean them up here.
1744                  */
1745                 btrfs_delete_unused_bgs(fs_info);
1746
1747                 btrfs_dev_replace_suspend_for_unmount(fs_info);
1748                 btrfs_scrub_cancel(fs_info);
1749                 btrfs_pause_balance(fs_info);
1750
1751                 ret = btrfs_commit_super(root);
1752                 if (ret)
1753                         goto restore;
1754         } else {
1755                 if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
1756                         btrfs_err(fs_info,
1757                                 "Remounting read-write after error is not allowed");
1758                         ret = -EINVAL;
1759                         goto restore;
1760                 }
1761                 if (fs_info->fs_devices->rw_devices == 0) {
1762                         ret = -EACCES;
1763                         goto restore;
1764                 }
1765
1766                 if (fs_info->fs_devices->missing_devices >
1767                      fs_info->num_tolerated_disk_barrier_failures &&
1768                     !(*flags & MS_RDONLY)) {
1769                         btrfs_warn(fs_info,
1770                                 "too many missing devices, writeable remount is not allowed");
1771                         ret = -EACCES;
1772                         goto restore;
1773                 }
1774
1775                 if (btrfs_super_log_root(fs_info->super_copy) != 0) {
1776                         ret = -EINVAL;
1777                         goto restore;
1778                 }
1779
1780                 ret = btrfs_cleanup_fs_roots(fs_info);
1781                 if (ret)
1782                         goto restore;
1783
1784                 /* recover relocation */
1785                 mutex_lock(&fs_info->cleaner_mutex);
1786                 ret = btrfs_recover_relocation(root);
1787                 mutex_unlock(&fs_info->cleaner_mutex);
1788                 if (ret)
1789                         goto restore;
1790
1791                 ret = btrfs_resume_balance_async(fs_info);
1792                 if (ret)
1793                         goto restore;
1794
1795                 ret = btrfs_resume_dev_replace_async(fs_info);
1796                 if (ret) {
1797                         btrfs_warn(fs_info, "failed to resume dev_replace");
1798                         goto restore;
1799                 }
1800
1801                 if (!fs_info->uuid_root) {
1802                         btrfs_info(fs_info, "creating UUID tree");
1803                         ret = btrfs_create_uuid_tree(fs_info);
1804                         if (ret) {
1805                                 btrfs_warn(fs_info, "failed to create the UUID tree %d", ret);
1806                                 goto restore;
1807                         }
1808                 }
1809                 sb->s_flags &= ~MS_RDONLY;
1810
1811                 fs_info->open = 1;
1812         }
1813 out:
1814         wake_up_process(fs_info->transaction_kthread);
1815         btrfs_remount_cleanup(fs_info, old_opts);
1816         return 0;
1817
1818 restore:
1819         /* We've hit an error - don't reset MS_RDONLY */
1820         if (sb->s_flags & MS_RDONLY)
1821                 old_flags |= MS_RDONLY;
1822         sb->s_flags = old_flags;
1823         fs_info->mount_opt = old_opts;
1824         fs_info->compress_type = old_compress_type;
1825         fs_info->max_inline = old_max_inline;
1826         mutex_lock(&fs_info->chunk_mutex);
1827         fs_info->alloc_start = old_alloc_start;
1828         mutex_unlock(&fs_info->chunk_mutex);
1829         btrfs_resize_thread_pool(fs_info,
1830                 old_thread_pool_size, fs_info->thread_pool_size);
1831         fs_info->metadata_ratio = old_metadata_ratio;
1832         btrfs_remount_cleanup(fs_info, old_opts);
1833         return ret;
1834 }
1835
1836 /* Used to sort the devices by max_avail(descending sort) */
1837 static int btrfs_cmp_device_free_bytes(const void *dev_info1,
1838                                        const void *dev_info2)
1839 {
1840         if (((struct btrfs_device_info *)dev_info1)->max_avail >
1841             ((struct btrfs_device_info *)dev_info2)->max_avail)
1842                 return -1;
1843         else if (((struct btrfs_device_info *)dev_info1)->max_avail <
1844                  ((struct btrfs_device_info *)dev_info2)->max_avail)
1845                 return 1;
1846         else
1847         return 0;
1848 }
1849
1850 /*
1851  * sort the devices by max_avail, in which max free extent size of each device
1852  * is stored.(Descending Sort)
1853  */
1854 static inline void btrfs_descending_sort_devices(
1855                                         struct btrfs_device_info *devices,
1856                                         size_t nr_devices)
1857 {
1858         sort(devices, nr_devices, sizeof(struct btrfs_device_info),
1859              btrfs_cmp_device_free_bytes, NULL);
1860 }
1861
1862 /*
1863  * The helper to calc the free space on the devices that can be used to store
1864  * file data.
1865  */
1866 static int btrfs_calc_avail_data_space(struct btrfs_root *root, u64 *free_bytes)
1867 {
1868         struct btrfs_fs_info *fs_info = root->fs_info;
1869         struct btrfs_device_info *devices_info;
1870         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
1871         struct btrfs_device *device;
1872         u64 skip_space;
1873         u64 type;
1874         u64 avail_space;
1875         u64 used_space;
1876         u64 min_stripe_size;
1877         int min_stripes = 1, num_stripes = 1;
1878         int i = 0, nr_devices;
1879         int ret;
1880
1881         /*
1882          * We aren't under the device list lock, so this is racy-ish, but good
1883          * enough for our purposes.
1884          */
1885         nr_devices = fs_info->fs_devices->open_devices;
1886         if (!nr_devices) {
1887                 smp_mb();
1888                 nr_devices = fs_info->fs_devices->open_devices;
1889                 ASSERT(nr_devices);
1890                 if (!nr_devices) {
1891                         *free_bytes = 0;
1892                         return 0;
1893                 }
1894         }
1895
1896         devices_info = kmalloc_array(nr_devices, sizeof(*devices_info),
1897                                GFP_NOFS);
1898         if (!devices_info)
1899                 return -ENOMEM;
1900
1901         /* calc min stripe number for data space allocation */
1902         type = btrfs_get_alloc_profile(root, 1);
1903         if (type & BTRFS_BLOCK_GROUP_RAID0) {
1904                 min_stripes = 2;
1905                 num_stripes = nr_devices;
1906         } else if (type & BTRFS_BLOCK_GROUP_RAID1) {
1907                 min_stripes = 2;
1908                 num_stripes = 2;
1909         } else if (type & BTRFS_BLOCK_GROUP_RAID10) {
1910                 min_stripes = 4;
1911                 num_stripes = 4;
1912         }
1913
1914         if (type & BTRFS_BLOCK_GROUP_DUP)
1915                 min_stripe_size = 2 * BTRFS_STRIPE_LEN;
1916         else
1917                 min_stripe_size = BTRFS_STRIPE_LEN;
1918
1919         if (fs_info->alloc_start)
1920                 mutex_lock(&fs_devices->device_list_mutex);
1921         rcu_read_lock();
1922         list_for_each_entry_rcu(device, &fs_devices->devices, dev_list) {
1923                 if (!device->in_fs_metadata || !device->bdev ||
1924                     device->is_tgtdev_for_dev_replace)
1925                         continue;
1926
1927                 if (i >= nr_devices)
1928                         break;
1929
1930                 avail_space = device->total_bytes - device->bytes_used;
1931
1932                 /* align with stripe_len */
1933                 avail_space = div_u64(avail_space, BTRFS_STRIPE_LEN);
1934                 avail_space *= BTRFS_STRIPE_LEN;
1935
1936                 /*
1937                  * In order to avoid overwriting the superblock on the drive,
1938                  * btrfs starts at an offset of at least 1MB when doing chunk
1939                  * allocation.
1940                  */
1941                 skip_space = SZ_1M;
1942
1943                 /* user can set the offset in fs_info->alloc_start. */
1944                 if (fs_info->alloc_start &&
1945                     fs_info->alloc_start + BTRFS_STRIPE_LEN <=
1946                     device->total_bytes) {
1947                         rcu_read_unlock();
1948                         skip_space = max(fs_info->alloc_start, skip_space);
1949
1950                         /*
1951                          * btrfs can not use the free space in
1952                          * [0, skip_space - 1], we must subtract it from the
1953                          * total. In order to implement it, we account the used
1954                          * space in this range first.
1955                          */
1956                         ret = btrfs_account_dev_extents_size(device, 0,
1957                                                              skip_space - 1,
1958                                                              &used_space);
1959                         if (ret) {
1960                                 kfree(devices_info);
1961                                 mutex_unlock(&fs_devices->device_list_mutex);
1962                                 return ret;
1963                         }
1964
1965                         rcu_read_lock();
1966
1967                         /* calc the free space in [0, skip_space - 1] */
1968                         skip_space -= used_space;
1969                 }
1970
1971                 /*
1972                  * we can use the free space in [0, skip_space - 1], subtract
1973                  * it from the total.
1974                  */
1975                 if (avail_space && avail_space >= skip_space)
1976                         avail_space -= skip_space;
1977                 else
1978                         avail_space = 0;
1979
1980                 if (avail_space < min_stripe_size)
1981                         continue;
1982
1983                 devices_info[i].dev = device;
1984                 devices_info[i].max_avail = avail_space;
1985
1986                 i++;
1987         }
1988         rcu_read_unlock();
1989         if (fs_info->alloc_start)
1990                 mutex_unlock(&fs_devices->device_list_mutex);
1991
1992         nr_devices = i;
1993
1994         btrfs_descending_sort_devices(devices_info, nr_devices);
1995
1996         i = nr_devices - 1;
1997         avail_space = 0;
1998         while (nr_devices >= min_stripes) {
1999                 if (num_stripes > nr_devices)
2000                         num_stripes = nr_devices;
2001
2002                 if (devices_info[i].max_avail >= min_stripe_size) {
2003                         int j;
2004                         u64 alloc_size;
2005
2006                         avail_space += devices_info[i].max_avail * num_stripes;
2007                         alloc_size = devices_info[i].max_avail;
2008                         for (j = i + 1 - num_stripes; j <= i; j++)
2009                                 devices_info[j].max_avail -= alloc_size;
2010                 }
2011                 i--;
2012                 nr_devices--;
2013         }
2014
2015         kfree(devices_info);
2016         *free_bytes = avail_space;
2017         return 0;
2018 }
2019
2020 /*
2021  * Calculate numbers for 'df', pessimistic in case of mixed raid profiles.
2022  *
2023  * If there's a redundant raid level at DATA block groups, use the respective
2024  * multiplier to scale the sizes.
2025  *
2026  * Unused device space usage is based on simulating the chunk allocator
2027  * algorithm that respects the device sizes, order of allocations and the
2028  * 'alloc_start' value, this is a close approximation of the actual use but
2029  * there are other factors that may change the result (like a new metadata
2030  * chunk).
2031  *
2032  * If metadata is exhausted, f_bavail will be 0.
2033  *
2034  * FIXME: not accurate for mixed block groups, total and free/used are ok,
2035  * available appears slightly larger.
2036  */
2037 static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
2038 {
2039         struct btrfs_fs_info *fs_info = btrfs_sb(dentry->d_sb);
2040         struct btrfs_super_block *disk_super = fs_info->super_copy;
2041         struct list_head *head = &fs_info->space_info;
2042         struct btrfs_space_info *found;
2043         u64 total_used = 0;
2044         u64 total_free_data = 0;
2045         u64 total_free_meta = 0;
2046         int bits = dentry->d_sb->s_blocksize_bits;
2047         __be32 *fsid = (__be32 *)fs_info->fsid;
2048         unsigned factor = 1;
2049         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
2050         int ret;
2051         u64 thresh = 0;
2052         int mixed = 0;
2053
2054         /*
2055          * holding chunk_mutex to avoid allocating new chunks, holding
2056          * device_list_mutex to avoid the device being removed
2057          */
2058         rcu_read_lock();
2059         list_for_each_entry_rcu(found, head, list) {
2060                 if (found->flags & BTRFS_BLOCK_GROUP_DATA) {
2061                         int i;
2062
2063                         total_free_data += found->disk_total - found->disk_used;
2064                         total_free_data -=
2065                                 btrfs_account_ro_block_groups_free_space(found);
2066
2067                         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
2068                                 if (!list_empty(&found->block_groups[i])) {
2069                                         switch (i) {
2070                                         case BTRFS_RAID_DUP:
2071                                         case BTRFS_RAID_RAID1:
2072                                         case BTRFS_RAID_RAID10:
2073                                                 factor = 2;
2074                                         }
2075                                 }
2076                         }
2077                 }
2078
2079                 /*
2080                  * Metadata in mixed block goup profiles are accounted in data
2081                  */
2082                 if (!mixed && found->flags & BTRFS_BLOCK_GROUP_METADATA) {
2083                         if (found->flags & BTRFS_BLOCK_GROUP_DATA)
2084                                 mixed = 1;
2085                         else
2086                                 total_free_meta += found->disk_total -
2087                                         found->disk_used;
2088                 }
2089
2090                 total_used += found->disk_used;
2091         }
2092
2093         rcu_read_unlock();
2094
2095         buf->f_blocks = div_u64(btrfs_super_total_bytes(disk_super), factor);
2096         buf->f_blocks >>= bits;
2097         buf->f_bfree = buf->f_blocks - (div_u64(total_used, factor) >> bits);
2098
2099         /* Account global block reserve as used, it's in logical size already */
2100         spin_lock(&block_rsv->lock);
2101         /* Mixed block groups accounting is not byte-accurate, avoid overflow */
2102         if (buf->f_bfree >= block_rsv->size >> bits)
2103                 buf->f_bfree -= block_rsv->size >> bits;
2104         else
2105                 buf->f_bfree = 0;
2106         spin_unlock(&block_rsv->lock);
2107
2108         buf->f_bavail = div_u64(total_free_data, factor);
2109         ret = btrfs_calc_avail_data_space(fs_info->tree_root, &total_free_data);
2110         if (ret)
2111                 return ret;
2112         buf->f_bavail += div_u64(total_free_data, factor);
2113         buf->f_bavail = buf->f_bavail >> bits;
2114
2115         /*
2116          * We calculate the remaining metadata space minus global reserve. If
2117          * this is (supposedly) smaller than zero, there's no space. But this
2118          * does not hold in practice, the exhausted state happens where's still
2119          * some positive delta. So we apply some guesswork and compare the
2120          * delta to a 4M threshold.  (Practically observed delta was ~2M.)
2121          *
2122          * We probably cannot calculate the exact threshold value because this
2123          * depends on the internal reservations requested by various
2124          * operations, so some operations that consume a few metadata will
2125          * succeed even if the Avail is zero. But this is better than the other
2126          * way around.
2127          */
2128         thresh = 4 * 1024 * 1024;
2129
2130         if (!mixed && total_free_meta - thresh < block_rsv->size)
2131                 buf->f_bavail = 0;
2132
2133         buf->f_type = BTRFS_SUPER_MAGIC;
2134         buf->f_bsize = dentry->d_sb->s_blocksize;
2135         buf->f_namelen = BTRFS_NAME_LEN;
2136
2137         /* We treat it as constant endianness (it doesn't matter _which_)
2138            because we want the fsid to come out the same whether mounted
2139            on a big-endian or little-endian host */
2140         buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
2141         buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
2142         /* Mask in the root object ID too, to disambiguate subvols */
2143         buf->f_fsid.val[0] ^= BTRFS_I(d_inode(dentry))->root->objectid >> 32;
2144         buf->f_fsid.val[1] ^= BTRFS_I(d_inode(dentry))->root->objectid;
2145
2146         return 0;
2147 }
2148
2149 static void btrfs_kill_super(struct super_block *sb)
2150 {
2151         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
2152         kill_anon_super(sb);
2153         free_fs_info(fs_info);
2154 }
2155
2156 static struct file_system_type btrfs_fs_type = {
2157         .owner          = THIS_MODULE,
2158         .name           = "btrfs",
2159         .mount          = btrfs_mount,
2160         .kill_sb        = btrfs_kill_super,
2161         .fs_flags       = FS_REQUIRES_DEV | FS_BINARY_MOUNTDATA,
2162 };
2163 MODULE_ALIAS_FS("btrfs");
2164
2165 static int btrfs_control_open(struct inode *inode, struct file *file)
2166 {
2167         /*
2168          * The control file's private_data is used to hold the
2169          * transaction when it is started and is used to keep
2170          * track of whether a transaction is already in progress.
2171          */
2172         file->private_data = NULL;
2173         return 0;
2174 }
2175
2176 /*
2177  * used by btrfsctl to scan devices when no FS is mounted
2178  */
2179 static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
2180                                 unsigned long arg)
2181 {
2182         struct btrfs_ioctl_vol_args *vol;
2183         struct btrfs_fs_devices *fs_devices;
2184         int ret = -ENOTTY;
2185
2186         if (!capable(CAP_SYS_ADMIN))
2187                 return -EPERM;
2188
2189         vol = memdup_user((void __user *)arg, sizeof(*vol));
2190         if (IS_ERR(vol))
2191                 return PTR_ERR(vol);
2192
2193         switch (cmd) {
2194         case BTRFS_IOC_SCAN_DEV:
2195                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2196                                             &btrfs_fs_type, &fs_devices);
2197                 break;
2198         case BTRFS_IOC_DEVICES_READY:
2199                 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
2200                                             &btrfs_fs_type, &fs_devices);
2201                 if (ret)
2202                         break;
2203                 ret = !(fs_devices->num_devices == fs_devices->total_devices);
2204                 break;
2205         case BTRFS_IOC_GET_SUPPORTED_FEATURES:
2206                 ret = btrfs_ioctl_get_supported_features((void __user*)arg);
2207                 break;
2208         }
2209
2210         kfree(vol);
2211         return ret;
2212 }
2213
2214 static int btrfs_freeze(struct super_block *sb)
2215 {
2216         struct btrfs_trans_handle *trans;
2217         struct btrfs_root *root = btrfs_sb(sb)->tree_root;
2218
2219         trans = btrfs_attach_transaction_barrier(root);
2220         if (IS_ERR(trans)) {
2221                 /* no transaction, don't bother */
2222                 if (PTR_ERR(trans) == -ENOENT)
2223                         return 0;
2224                 return PTR_ERR(trans);
2225         }
2226         return btrfs_commit_transaction(trans, root);
2227 }
2228
2229 static int btrfs_show_devname(struct seq_file *m, struct dentry *root)
2230 {
2231         struct btrfs_fs_info *fs_info = btrfs_sb(root->d_sb);
2232         struct btrfs_fs_devices *cur_devices;
2233         struct btrfs_device *dev, *first_dev = NULL;
2234         struct list_head *head;
2235         struct rcu_string *name;
2236
2237         mutex_lock(&fs_info->fs_devices->device_list_mutex);
2238         cur_devices = fs_info->fs_devices;
2239         while (cur_devices) {
2240                 head = &cur_devices->devices;
2241                 list_for_each_entry(dev, head, dev_list) {
2242                         if (dev->missing)
2243                                 continue;
2244                         if (!dev->name)
2245                                 continue;
2246                         if (!first_dev || dev->devid < first_dev->devid)
2247                                 first_dev = dev;
2248                 }
2249                 cur_devices = cur_devices->seed;
2250         }
2251
2252         if (first_dev) {
2253                 rcu_read_lock();
2254                 name = rcu_dereference(first_dev->name);
2255                 seq_escape(m, name->str, " \t\n\\");
2256                 rcu_read_unlock();
2257         } else {
2258                 WARN_ON(1);
2259         }
2260         mutex_unlock(&fs_info->fs_devices->device_list_mutex);
2261         return 0;
2262 }
2263
2264 static const struct super_operations btrfs_super_ops = {
2265         .drop_inode     = btrfs_drop_inode,
2266         .evict_inode    = btrfs_evict_inode,
2267         .put_super      = btrfs_put_super,
2268         .sync_fs        = btrfs_sync_fs,
2269         .show_options   = btrfs_show_options,
2270         .show_devname   = btrfs_show_devname,
2271         .write_inode    = btrfs_write_inode,
2272         .alloc_inode    = btrfs_alloc_inode,
2273         .destroy_inode  = btrfs_destroy_inode,
2274         .statfs         = btrfs_statfs,
2275         .remount_fs     = btrfs_remount,
2276         .freeze_fs      = btrfs_freeze,
2277 };
2278
2279 static const struct file_operations btrfs_ctl_fops = {
2280         .open = btrfs_control_open,
2281         .unlocked_ioctl  = btrfs_control_ioctl,
2282         .compat_ioctl = btrfs_control_ioctl,
2283         .owner   = THIS_MODULE,
2284         .llseek = noop_llseek,
2285 };
2286
2287 static struct miscdevice btrfs_misc = {
2288         .minor          = BTRFS_MINOR,
2289         .name           = "btrfs-control",
2290         .fops           = &btrfs_ctl_fops
2291 };
2292
2293 MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
2294 MODULE_ALIAS("devname:btrfs-control");
2295
2296 static int btrfs_interface_init(void)
2297 {
2298         return misc_register(&btrfs_misc);
2299 }
2300
2301 static void btrfs_interface_exit(void)
2302 {
2303         misc_deregister(&btrfs_misc);
2304 }
2305
2306 static void btrfs_print_mod_info(void)
2307 {
2308         printk(KERN_INFO "Btrfs loaded, crc32c=%s"
2309 #ifdef CONFIG_BTRFS_DEBUG
2310                         ", debug=on"
2311 #endif
2312 #ifdef CONFIG_BTRFS_ASSERT
2313                         ", assert=on"
2314 #endif
2315 #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
2316                         ", integrity-checker=on"
2317 #endif
2318                         "\n",
2319                         btrfs_crc32c_impl());
2320 }
2321
2322 static int btrfs_run_sanity_tests(void)
2323 {
2324         int ret, i;
2325         u32 sectorsize, nodesize;
2326         u32 test_sectorsize[] = {
2327                 PAGE_SIZE,
2328         };
2329         ret = btrfs_init_test_fs();
2330         if (ret)
2331                 return ret;
2332         for (i = 0; i < ARRAY_SIZE(test_sectorsize); i++) {
2333                 sectorsize = test_sectorsize[i];
2334                 for (nodesize = sectorsize;
2335                      nodesize <= BTRFS_MAX_METADATA_BLOCKSIZE;
2336                      nodesize <<= 1) {
2337                         pr_info("BTRFS: selftest: sectorsize: %u  nodesize: %u\n",
2338                                 sectorsize, nodesize);
2339                         ret = btrfs_test_free_space_cache(sectorsize, nodesize);
2340                         if (ret)
2341                                 goto out;
2342                         ret = btrfs_test_extent_buffer_operations(sectorsize,
2343                                 nodesize);
2344                         if (ret)
2345                                 goto out;
2346                         ret = btrfs_test_extent_io(sectorsize, nodesize);
2347                         if (ret)
2348                                 goto out;
2349                         ret = btrfs_test_inodes(sectorsize, nodesize);
2350                         if (ret)
2351                                 goto out;
2352                         ret = btrfs_test_qgroups(sectorsize, nodesize);
2353                         if (ret)
2354                                 goto out;
2355                         ret = btrfs_test_free_space_tree(sectorsize, nodesize);
2356                         if (ret)
2357                                 goto out;
2358                 }
2359         }
2360 out:
2361         btrfs_destroy_test_fs();
2362         return ret;
2363 }
2364
2365 static int __init init_btrfs_fs(void)
2366 {
2367         int err;
2368
2369         err = btrfs_hash_init();
2370         if (err)
2371                 return err;
2372
2373         btrfs_props_init();
2374
2375         err = btrfs_init_sysfs();
2376         if (err)
2377                 goto free_hash;
2378
2379         btrfs_init_compress();
2380
2381         err = btrfs_init_cachep();
2382         if (err)
2383                 goto free_compress;
2384
2385         err = extent_io_init();
2386         if (err)
2387                 goto free_cachep;
2388
2389         err = extent_map_init();
2390         if (err)
2391                 goto free_extent_io;
2392
2393         err = ordered_data_init();
2394         if (err)
2395                 goto free_extent_map;
2396
2397         err = btrfs_delayed_inode_init();
2398         if (err)
2399                 goto free_ordered_data;
2400
2401         err = btrfs_auto_defrag_init();
2402         if (err)
2403                 goto free_delayed_inode;
2404
2405         err = btrfs_delayed_ref_init();
2406         if (err)
2407                 goto free_auto_defrag;
2408
2409         err = btrfs_prelim_ref_init();
2410         if (err)
2411                 goto free_delayed_ref;
2412
2413         err = btrfs_end_io_wq_init();
2414         if (err)
2415                 goto free_prelim_ref;
2416
2417         err = btrfs_interface_init();
2418         if (err)
2419                 goto free_end_io_wq;
2420
2421         btrfs_init_lockdep();
2422
2423         btrfs_print_mod_info();
2424
2425         err = btrfs_run_sanity_tests();
2426         if (err)
2427                 goto unregister_ioctl;
2428
2429         err = register_filesystem(&btrfs_fs_type);
2430         if (err)
2431                 goto unregister_ioctl;
2432
2433         return 0;
2434
2435 unregister_ioctl:
2436         btrfs_interface_exit();
2437 free_end_io_wq:
2438         btrfs_end_io_wq_exit();
2439 free_prelim_ref:
2440         btrfs_prelim_ref_exit();
2441 free_delayed_ref:
2442         btrfs_delayed_ref_exit();
2443 free_auto_defrag:
2444         btrfs_auto_defrag_exit();
2445 free_delayed_inode:
2446         btrfs_delayed_inode_exit();
2447 free_ordered_data:
2448         ordered_data_exit();
2449 free_extent_map:
2450         extent_map_exit();
2451 free_extent_io:
2452         extent_io_exit();
2453 free_cachep:
2454         btrfs_destroy_cachep();
2455 free_compress:
2456         btrfs_exit_compress();
2457         btrfs_exit_sysfs();
2458 free_hash:
2459         btrfs_hash_exit();
2460         return err;
2461 }
2462
2463 static void __exit exit_btrfs_fs(void)
2464 {
2465         btrfs_destroy_cachep();
2466         btrfs_delayed_ref_exit();
2467         btrfs_auto_defrag_exit();
2468         btrfs_delayed_inode_exit();
2469         btrfs_prelim_ref_exit();
2470         ordered_data_exit();
2471         extent_map_exit();
2472         extent_io_exit();
2473         btrfs_interface_exit();
2474         btrfs_end_io_wq_exit();
2475         unregister_filesystem(&btrfs_fs_type);
2476         btrfs_exit_sysfs();
2477         btrfs_cleanup_fs_uuids();
2478         btrfs_exit_compress();
2479         btrfs_hash_exit();
2480 }
2481
2482 late_initcall(init_btrfs_fs);
2483 module_exit(exit_btrfs_fs)
2484
2485 MODULE_LICENSE("GPL");