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Btrfs: Fix variables set but not read (bugs found by gcc 4.6)
[linux-2.6-block.git] / fs / btrfs / super.c
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1/*
2 * Copyright (C) 2007 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19#include <linux/blkdev.h>
20#include <linux/module.h>
21#include <linux/buffer_head.h>
22#include <linux/fs.h>
23#include <linux/pagemap.h>
24#include <linux/highmem.h>
25#include <linux/time.h>
26#include <linux/init.h>
27#include <linux/seq_file.h>
28#include <linux/string.h>
29#include <linux/backing-dev.h>
30#include <linux/mount.h>
31#include <linux/mpage.h>
32#include <linux/swap.h>
33#include <linux/writeback.h>
34#include <linux/statfs.h>
35#include <linux/compat.h>
36#include <linux/parser.h>
37#include <linux/ctype.h>
38#include <linux/namei.h>
39#include <linux/miscdevice.h>
40#include <linux/magic.h>
41#include <linux/slab.h>
42#include "compat.h"
43#include "ctree.h"
44#include "disk-io.h"
45#include "transaction.h"
46#include "btrfs_inode.h"
47#include "ioctl.h"
48#include "print-tree.h"
49#include "xattr.h"
50#include "volumes.h"
51#include "version.h"
52#include "export.h"
53#include "compression.h"
54
55static const struct super_operations btrfs_super_ops;
56
57static void btrfs_put_super(struct super_block *sb)
58{
59 struct btrfs_root *root = btrfs_sb(sb);
60 int ret;
61
62 ret = close_ctree(root);
63 sb->s_fs_info = NULL;
64}
65
66enum {
67 Opt_degraded, Opt_subvol, Opt_subvolid, Opt_device, Opt_nodatasum,
68 Opt_nodatacow, Opt_max_inline, Opt_alloc_start, Opt_nobarrier, Opt_ssd,
69 Opt_nossd, Opt_ssd_spread, Opt_thread_pool, Opt_noacl, Opt_compress,
70 Opt_compress_force, Opt_notreelog, Opt_ratio, Opt_flushoncommit,
71 Opt_discard, Opt_space_cache, Opt_clear_cache, Opt_err,
72};
73
74static match_table_t tokens = {
75 {Opt_degraded, "degraded"},
76 {Opt_subvol, "subvol=%s"},
77 {Opt_subvolid, "subvolid=%d"},
78 {Opt_device, "device=%s"},
79 {Opt_nodatasum, "nodatasum"},
80 {Opt_nodatacow, "nodatacow"},
81 {Opt_nobarrier, "nobarrier"},
82 {Opt_max_inline, "max_inline=%s"},
83 {Opt_alloc_start, "alloc_start=%s"},
84 {Opt_thread_pool, "thread_pool=%d"},
85 {Opt_compress, "compress"},
86 {Opt_compress_force, "compress-force"},
87 {Opt_ssd, "ssd"},
88 {Opt_ssd_spread, "ssd_spread"},
89 {Opt_nossd, "nossd"},
90 {Opt_noacl, "noacl"},
91 {Opt_notreelog, "notreelog"},
92 {Opt_flushoncommit, "flushoncommit"},
93 {Opt_ratio, "metadata_ratio=%d"},
94 {Opt_discard, "discard"},
95 {Opt_space_cache, "space_cache"},
96 {Opt_clear_cache, "clear_cache"},
97 {Opt_err, NULL},
98};
99
100/*
101 * Regular mount options parser. Everything that is needed only when
102 * reading in a new superblock is parsed here.
103 */
104int btrfs_parse_options(struct btrfs_root *root, char *options)
105{
106 struct btrfs_fs_info *info = root->fs_info;
107 substring_t args[MAX_OPT_ARGS];
108 char *p, *num, *orig;
109 int intarg;
110 int ret = 0;
111
112 if (!options)
113 return 0;
114
115 /*
116 * strsep changes the string, duplicate it because parse_options
117 * gets called twice
118 */
119 options = kstrdup(options, GFP_NOFS);
120 if (!options)
121 return -ENOMEM;
122
123 orig = options;
124
125 while ((p = strsep(&options, ",")) != NULL) {
126 int token;
127 if (!*p)
128 continue;
129
130 token = match_token(p, tokens, args);
131 switch (token) {
132 case Opt_degraded:
133 printk(KERN_INFO "btrfs: allowing degraded mounts\n");
134 btrfs_set_opt(info->mount_opt, DEGRADED);
135 break;
136 case Opt_subvol:
137 case Opt_subvolid:
138 case Opt_device:
139 /*
140 * These are parsed by btrfs_parse_early_options
141 * and can be happily ignored here.
142 */
143 break;
144 case Opt_nodatasum:
145 printk(KERN_INFO "btrfs: setting nodatasum\n");
146 btrfs_set_opt(info->mount_opt, NODATASUM);
147 break;
148 case Opt_nodatacow:
149 printk(KERN_INFO "btrfs: setting nodatacow\n");
150 btrfs_set_opt(info->mount_opt, NODATACOW);
151 btrfs_set_opt(info->mount_opt, NODATASUM);
152 break;
153 case Opt_compress:
154 printk(KERN_INFO "btrfs: use compression\n");
155 btrfs_set_opt(info->mount_opt, COMPRESS);
156 break;
157 case Opt_compress_force:
158 printk(KERN_INFO "btrfs: forcing compression\n");
159 btrfs_set_opt(info->mount_opt, FORCE_COMPRESS);
160 btrfs_set_opt(info->mount_opt, COMPRESS);
161 break;
162 case Opt_ssd:
163 printk(KERN_INFO "btrfs: use ssd allocation scheme\n");
164 btrfs_set_opt(info->mount_opt, SSD);
165 break;
166 case Opt_ssd_spread:
167 printk(KERN_INFO "btrfs: use spread ssd "
168 "allocation scheme\n");
169 btrfs_set_opt(info->mount_opt, SSD);
170 btrfs_set_opt(info->mount_opt, SSD_SPREAD);
171 break;
172 case Opt_nossd:
173 printk(KERN_INFO "btrfs: not using ssd allocation "
174 "scheme\n");
175 btrfs_set_opt(info->mount_opt, NOSSD);
176 btrfs_clear_opt(info->mount_opt, SSD);
177 btrfs_clear_opt(info->mount_opt, SSD_SPREAD);
178 break;
179 case Opt_nobarrier:
180 printk(KERN_INFO "btrfs: turning off barriers\n");
181 btrfs_set_opt(info->mount_opt, NOBARRIER);
182 break;
183 case Opt_thread_pool:
184 intarg = 0;
185 match_int(&args[0], &intarg);
186 if (intarg) {
187 info->thread_pool_size = intarg;
188 printk(KERN_INFO "btrfs: thread pool %d\n",
189 info->thread_pool_size);
190 }
191 break;
192 case Opt_max_inline:
193 num = match_strdup(&args[0]);
194 if (num) {
195 info->max_inline = memparse(num, NULL);
196 kfree(num);
197
198 if (info->max_inline) {
199 info->max_inline = max_t(u64,
200 info->max_inline,
201 root->sectorsize);
202 }
203 printk(KERN_INFO "btrfs: max_inline at %llu\n",
204 (unsigned long long)info->max_inline);
205 }
206 break;
207 case Opt_alloc_start:
208 num = match_strdup(&args[0]);
209 if (num) {
210 info->alloc_start = memparse(num, NULL);
211 kfree(num);
212 printk(KERN_INFO
213 "btrfs: allocations start at %llu\n",
214 (unsigned long long)info->alloc_start);
215 }
216 break;
217 case Opt_noacl:
218 root->fs_info->sb->s_flags &= ~MS_POSIXACL;
219 break;
220 case Opt_notreelog:
221 printk(KERN_INFO "btrfs: disabling tree log\n");
222 btrfs_set_opt(info->mount_opt, NOTREELOG);
223 break;
224 case Opt_flushoncommit:
225 printk(KERN_INFO "btrfs: turning on flush-on-commit\n");
226 btrfs_set_opt(info->mount_opt, FLUSHONCOMMIT);
227 break;
228 case Opt_ratio:
229 intarg = 0;
230 match_int(&args[0], &intarg);
231 if (intarg) {
232 info->metadata_ratio = intarg;
233 printk(KERN_INFO "btrfs: metadata ratio %d\n",
234 info->metadata_ratio);
235 }
236 break;
237 case Opt_discard:
238 btrfs_set_opt(info->mount_opt, DISCARD);
239 break;
240 case Opt_space_cache:
241 printk(KERN_INFO "btrfs: enabling disk space caching\n");
242 btrfs_set_opt(info->mount_opt, SPACE_CACHE);
243 case Opt_clear_cache:
244 printk(KERN_INFO "btrfs: force clearing of disk cache\n");
245 btrfs_set_opt(info->mount_opt, CLEAR_CACHE);
246 break;
247 case Opt_err:
248 printk(KERN_INFO "btrfs: unrecognized mount option "
249 "'%s'\n", p);
250 ret = -EINVAL;
251 goto out;
252 default:
253 break;
254 }
255 }
256out:
257 kfree(orig);
258 return ret;
259}
260
261/*
262 * Parse mount options that are required early in the mount process.
263 *
264 * All other options will be parsed on much later in the mount process and
265 * only when we need to allocate a new super block.
266 */
267static int btrfs_parse_early_options(const char *options, fmode_t flags,
268 void *holder, char **subvol_name, u64 *subvol_objectid,
269 struct btrfs_fs_devices **fs_devices)
270{
271 substring_t args[MAX_OPT_ARGS];
272 char *opts, *p;
273 int error = 0;
274 int intarg;
275
276 if (!options)
277 goto out;
278
279 /*
280 * strsep changes the string, duplicate it because parse_options
281 * gets called twice
282 */
283 opts = kstrdup(options, GFP_KERNEL);
284 if (!opts)
285 return -ENOMEM;
286
287 while ((p = strsep(&opts, ",")) != NULL) {
288 int token;
289 if (!*p)
290 continue;
291
292 token = match_token(p, tokens, args);
293 switch (token) {
294 case Opt_subvol:
295 *subvol_name = match_strdup(&args[0]);
296 break;
297 case Opt_subvolid:
298 intarg = 0;
299 error = match_int(&args[0], &intarg);
300 if (!error) {
301 /* we want the original fs_tree */
302 if (!intarg)
303 *subvol_objectid =
304 BTRFS_FS_TREE_OBJECTID;
305 else
306 *subvol_objectid = intarg;
307 }
308 break;
309 case Opt_device:
310 error = btrfs_scan_one_device(match_strdup(&args[0]),
311 flags, holder, fs_devices);
312 if (error)
313 goto out_free_opts;
314 break;
315 default:
316 break;
317 }
318 }
319
320 out_free_opts:
321 kfree(opts);
322 out:
323 /*
324 * If no subvolume name is specified we use the default one. Allocate
325 * a copy of the string "." here so that code later in the
326 * mount path doesn't care if it's the default volume or another one.
327 */
328 if (!*subvol_name) {
329 *subvol_name = kstrdup(".", GFP_KERNEL);
330 if (!*subvol_name)
331 return -ENOMEM;
332 }
333 return error;
334}
335
336static struct dentry *get_default_root(struct super_block *sb,
337 u64 subvol_objectid)
338{
339 struct btrfs_root *root = sb->s_fs_info;
340 struct btrfs_root *new_root;
341 struct btrfs_dir_item *di;
342 struct btrfs_path *path;
343 struct btrfs_key location;
344 struct inode *inode;
345 struct dentry *dentry;
346 u64 dir_id;
347 int new = 0;
348
349 /*
350 * We have a specific subvol we want to mount, just setup location and
351 * go look up the root.
352 */
353 if (subvol_objectid) {
354 location.objectid = subvol_objectid;
355 location.type = BTRFS_ROOT_ITEM_KEY;
356 location.offset = (u64)-1;
357 goto find_root;
358 }
359
360 path = btrfs_alloc_path();
361 if (!path)
362 return ERR_PTR(-ENOMEM);
363 path->leave_spinning = 1;
364
365 /*
366 * Find the "default" dir item which points to the root item that we
367 * will mount by default if we haven't been given a specific subvolume
368 * to mount.
369 */
370 dir_id = btrfs_super_root_dir(&root->fs_info->super_copy);
371 di = btrfs_lookup_dir_item(NULL, root, path, dir_id, "default", 7, 0);
372 if (IS_ERR(di))
373 return ERR_CAST(di);
374 if (!di) {
375 /*
376 * Ok the default dir item isn't there. This is weird since
377 * it's always been there, but don't freak out, just try and
378 * mount to root most subvolume.
379 */
380 btrfs_free_path(path);
381 dir_id = BTRFS_FIRST_FREE_OBJECTID;
382 new_root = root->fs_info->fs_root;
383 goto setup_root;
384 }
385
386 btrfs_dir_item_key_to_cpu(path->nodes[0], di, &location);
387 btrfs_free_path(path);
388
389find_root:
390 new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);
391 if (IS_ERR(new_root))
392 return ERR_CAST(new_root);
393
394 if (btrfs_root_refs(&new_root->root_item) == 0)
395 return ERR_PTR(-ENOENT);
396
397 dir_id = btrfs_root_dirid(&new_root->root_item);
398setup_root:
399 location.objectid = dir_id;
400 location.type = BTRFS_INODE_ITEM_KEY;
401 location.offset = 0;
402
403 inode = btrfs_iget(sb, &location, new_root, &new);
404 if (IS_ERR(inode))
405 return ERR_CAST(inode);
406
407 /*
408 * If we're just mounting the root most subvol put the inode and return
409 * a reference to the dentry. We will have already gotten a reference
410 * to the inode in btrfs_fill_super so we're good to go.
411 */
412 if (!new && sb->s_root->d_inode == inode) {
413 iput(inode);
414 return dget(sb->s_root);
415 }
416
417 if (new) {
418 const struct qstr name = { .name = "/", .len = 1 };
419
420 /*
421 * New inode, we need to make the dentry a sibling of s_root so
422 * everything gets cleaned up properly on unmount.
423 */
424 dentry = d_alloc(sb->s_root, &name);
425 if (!dentry) {
426 iput(inode);
427 return ERR_PTR(-ENOMEM);
428 }
429 d_splice_alias(inode, dentry);
430 } else {
431 /*
432 * We found the inode in cache, just find a dentry for it and
433 * put the reference to the inode we just got.
434 */
435 dentry = d_find_alias(inode);
436 iput(inode);
437 }
438
439 return dentry;
440}
441
442static int btrfs_fill_super(struct super_block *sb,
443 struct btrfs_fs_devices *fs_devices,
444 void *data, int silent)
445{
446 struct inode *inode;
447 struct dentry *root_dentry;
448 struct btrfs_super_block *disk_super;
449 struct btrfs_root *tree_root;
450 struct btrfs_key key;
451 int err;
452
453 sb->s_maxbytes = MAX_LFS_FILESIZE;
454 sb->s_magic = BTRFS_SUPER_MAGIC;
455 sb->s_op = &btrfs_super_ops;
456 sb->s_export_op = &btrfs_export_ops;
457 sb->s_xattr = btrfs_xattr_handlers;
458 sb->s_time_gran = 1;
459#ifdef CONFIG_BTRFS_FS_POSIX_ACL
460 sb->s_flags |= MS_POSIXACL;
461#endif
462
463 tree_root = open_ctree(sb, fs_devices, (char *)data);
464
465 if (IS_ERR(tree_root)) {
466 printk("btrfs: open_ctree failed\n");
467 return PTR_ERR(tree_root);
468 }
469 sb->s_fs_info = tree_root;
470 disk_super = &tree_root->fs_info->super_copy;
471
472 key.objectid = BTRFS_FIRST_FREE_OBJECTID;
473 key.type = BTRFS_INODE_ITEM_KEY;
474 key.offset = 0;
475 inode = btrfs_iget(sb, &key, tree_root->fs_info->fs_root, NULL);
476 if (IS_ERR(inode)) {
477 err = PTR_ERR(inode);
478 goto fail_close;
479 }
480
481 root_dentry = d_alloc_root(inode);
482 if (!root_dentry) {
483 iput(inode);
484 err = -ENOMEM;
485 goto fail_close;
486 }
487
488 sb->s_root = root_dentry;
489
490 save_mount_options(sb, data);
491 return 0;
492
493fail_close:
494 close_ctree(tree_root);
495 return err;
496}
497
498int btrfs_sync_fs(struct super_block *sb, int wait)
499{
500 struct btrfs_trans_handle *trans;
501 struct btrfs_root *root = btrfs_sb(sb);
502 int ret;
503
504 if (!wait) {
505 filemap_flush(root->fs_info->btree_inode->i_mapping);
506 return 0;
507 }
508
509 btrfs_start_delalloc_inodes(root, 0);
510 btrfs_wait_ordered_extents(root, 0, 0);
511
512 trans = btrfs_start_transaction(root, 0);
513 ret = btrfs_commit_transaction(trans, root);
514 return ret;
515}
516
517static int btrfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
518{
519 struct btrfs_root *root = btrfs_sb(vfs->mnt_sb);
520 struct btrfs_fs_info *info = root->fs_info;
521
522 if (btrfs_test_opt(root, DEGRADED))
523 seq_puts(seq, ",degraded");
524 if (btrfs_test_opt(root, NODATASUM))
525 seq_puts(seq, ",nodatasum");
526 if (btrfs_test_opt(root, NODATACOW))
527 seq_puts(seq, ",nodatacow");
528 if (btrfs_test_opt(root, NOBARRIER))
529 seq_puts(seq, ",nobarrier");
530 if (info->max_inline != 8192 * 1024)
531 seq_printf(seq, ",max_inline=%llu",
532 (unsigned long long)info->max_inline);
533 if (info->alloc_start != 0)
534 seq_printf(seq, ",alloc_start=%llu",
535 (unsigned long long)info->alloc_start);
536 if (info->thread_pool_size != min_t(unsigned long,
537 num_online_cpus() + 2, 8))
538 seq_printf(seq, ",thread_pool=%d", info->thread_pool_size);
539 if (btrfs_test_opt(root, COMPRESS))
540 seq_puts(seq, ",compress");
541 if (btrfs_test_opt(root, NOSSD))
542 seq_puts(seq, ",nossd");
543 if (btrfs_test_opt(root, SSD_SPREAD))
544 seq_puts(seq, ",ssd_spread");
545 else if (btrfs_test_opt(root, SSD))
546 seq_puts(seq, ",ssd");
547 if (btrfs_test_opt(root, NOTREELOG))
548 seq_puts(seq, ",notreelog");
549 if (btrfs_test_opt(root, FLUSHONCOMMIT))
550 seq_puts(seq, ",flushoncommit");
551 if (btrfs_test_opt(root, DISCARD))
552 seq_puts(seq, ",discard");
553 if (!(root->fs_info->sb->s_flags & MS_POSIXACL))
554 seq_puts(seq, ",noacl");
555 return 0;
556}
557
558static int btrfs_test_super(struct super_block *s, void *data)
559{
560 struct btrfs_fs_devices *test_fs_devices = data;
561 struct btrfs_root *root = btrfs_sb(s);
562
563 return root->fs_info->fs_devices == test_fs_devices;
564}
565
566/*
567 * Find a superblock for the given device / mount point.
568 *
569 * Note: This is based on get_sb_bdev from fs/super.c with a few additions
570 * for multiple device setup. Make sure to keep it in sync.
571 */
572static int btrfs_get_sb(struct file_system_type *fs_type, int flags,
573 const char *dev_name, void *data, struct vfsmount *mnt)
574{
575 struct block_device *bdev = NULL;
576 struct super_block *s;
577 struct dentry *root;
578 struct btrfs_fs_devices *fs_devices = NULL;
579 fmode_t mode = FMODE_READ;
580 char *subvol_name = NULL;
581 u64 subvol_objectid = 0;
582 int error = 0;
583 int found = 0;
584
585 if (!(flags & MS_RDONLY))
586 mode |= FMODE_WRITE;
587
588 error = btrfs_parse_early_options(data, mode, fs_type,
589 &subvol_name, &subvol_objectid,
590 &fs_devices);
591 if (error)
592 return error;
593
594 error = btrfs_scan_one_device(dev_name, mode, fs_type, &fs_devices);
595 if (error)
596 goto error_free_subvol_name;
597
598 error = btrfs_open_devices(fs_devices, mode, fs_type);
599 if (error)
600 goto error_free_subvol_name;
601
602 if (!(flags & MS_RDONLY) && fs_devices->rw_devices == 0) {
603 error = -EACCES;
604 goto error_close_devices;
605 }
606
607 bdev = fs_devices->latest_bdev;
608 s = sget(fs_type, btrfs_test_super, set_anon_super, fs_devices);
609 if (IS_ERR(s))
610 goto error_s;
611
612 if (s->s_root) {
613 if ((flags ^ s->s_flags) & MS_RDONLY) {
614 deactivate_locked_super(s);
615 error = -EBUSY;
616 goto error_close_devices;
617 }
618
619 found = 1;
620 btrfs_close_devices(fs_devices);
621 } else {
622 char b[BDEVNAME_SIZE];
623
624 s->s_flags = flags;
625 strlcpy(s->s_id, bdevname(bdev, b), sizeof(s->s_id));
626 error = btrfs_fill_super(s, fs_devices, data,
627 flags & MS_SILENT ? 1 : 0);
628 if (error) {
629 deactivate_locked_super(s);
630 goto error_free_subvol_name;
631 }
632
633 btrfs_sb(s)->fs_info->bdev_holder = fs_type;
634 s->s_flags |= MS_ACTIVE;
635 }
636
637 root = get_default_root(s, subvol_objectid);
638 if (IS_ERR(root)) {
639 error = PTR_ERR(root);
640 deactivate_locked_super(s);
641 goto error_free_subvol_name;
642 }
643 /* if they gave us a subvolume name bind mount into that */
644 if (strcmp(subvol_name, ".")) {
645 struct dentry *new_root;
646 mutex_lock(&root->d_inode->i_mutex);
647 new_root = lookup_one_len(subvol_name, root,
648 strlen(subvol_name));
649 mutex_unlock(&root->d_inode->i_mutex);
650
651 if (IS_ERR(new_root)) {
652 deactivate_locked_super(s);
653 error = PTR_ERR(new_root);
654 dput(root);
655 goto error_free_subvol_name;
656 }
657 if (!new_root->d_inode) {
658 dput(root);
659 dput(new_root);
660 deactivate_locked_super(s);
661 error = -ENXIO;
662 goto error_free_subvol_name;
663 }
664 dput(root);
665 root = new_root;
666 }
667
668 mnt->mnt_sb = s;
669 mnt->mnt_root = root;
670
671 kfree(subvol_name);
672 return 0;
673
674error_s:
675 error = PTR_ERR(s);
676error_close_devices:
677 btrfs_close_devices(fs_devices);
678error_free_subvol_name:
679 kfree(subvol_name);
680 return error;
681}
682
683static int btrfs_remount(struct super_block *sb, int *flags, char *data)
684{
685 struct btrfs_root *root = btrfs_sb(sb);
686 int ret;
687
688 ret = btrfs_parse_options(root, data);
689 if (ret)
690 return -EINVAL;
691
692 if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
693 return 0;
694
695 if (*flags & MS_RDONLY) {
696 sb->s_flags |= MS_RDONLY;
697
698 ret = btrfs_commit_super(root);
699 WARN_ON(ret);
700 } else {
701 if (root->fs_info->fs_devices->rw_devices == 0)
702 return -EACCES;
703
704 if (btrfs_super_log_root(&root->fs_info->super_copy) != 0)
705 return -EINVAL;
706
707 ret = btrfs_cleanup_fs_roots(root->fs_info);
708 WARN_ON(ret);
709
710 /* recover relocation */
711 ret = btrfs_recover_relocation(root);
712 WARN_ON(ret);
713
714 sb->s_flags &= ~MS_RDONLY;
715 }
716
717 return 0;
718}
719
720static int btrfs_statfs(struct dentry *dentry, struct kstatfs *buf)
721{
722 struct btrfs_root *root = btrfs_sb(dentry->d_sb);
723 struct btrfs_super_block *disk_super = &root->fs_info->super_copy;
724 struct list_head *head = &root->fs_info->space_info;
725 struct btrfs_space_info *found;
726 u64 total_used = 0;
727 u64 total_used_data = 0;
728 int bits = dentry->d_sb->s_blocksize_bits;
729 __be32 *fsid = (__be32 *)root->fs_info->fsid;
730
731 rcu_read_lock();
732 list_for_each_entry_rcu(found, head, list) {
733 if (found->flags & (BTRFS_BLOCK_GROUP_METADATA |
734 BTRFS_BLOCK_GROUP_SYSTEM))
735 total_used_data += found->disk_total;
736 else
737 total_used_data += found->disk_used;
738 total_used += found->disk_used;
739 }
740 rcu_read_unlock();
741
742 buf->f_namelen = BTRFS_NAME_LEN;
743 buf->f_blocks = btrfs_super_total_bytes(disk_super) >> bits;
744 buf->f_bfree = buf->f_blocks - (total_used >> bits);
745 buf->f_bavail = buf->f_blocks - (total_used_data >> bits);
746 buf->f_bsize = dentry->d_sb->s_blocksize;
747 buf->f_type = BTRFS_SUPER_MAGIC;
748
749 /* We treat it as constant endianness (it doesn't matter _which_)
750 because we want the fsid to come out the same whether mounted
751 on a big-endian or little-endian host */
752 buf->f_fsid.val[0] = be32_to_cpu(fsid[0]) ^ be32_to_cpu(fsid[2]);
753 buf->f_fsid.val[1] = be32_to_cpu(fsid[1]) ^ be32_to_cpu(fsid[3]);
754 /* Mask in the root object ID too, to disambiguate subvols */
755 buf->f_fsid.val[0] ^= BTRFS_I(dentry->d_inode)->root->objectid >> 32;
756 buf->f_fsid.val[1] ^= BTRFS_I(dentry->d_inode)->root->objectid;
757
758 return 0;
759}
760
761static struct file_system_type btrfs_fs_type = {
762 .owner = THIS_MODULE,
763 .name = "btrfs",
764 .get_sb = btrfs_get_sb,
765 .kill_sb = kill_anon_super,
766 .fs_flags = FS_REQUIRES_DEV,
767};
768
769/*
770 * used by btrfsctl to scan devices when no FS is mounted
771 */
772static long btrfs_control_ioctl(struct file *file, unsigned int cmd,
773 unsigned long arg)
774{
775 struct btrfs_ioctl_vol_args *vol;
776 struct btrfs_fs_devices *fs_devices;
777 int ret = -ENOTTY;
778
779 if (!capable(CAP_SYS_ADMIN))
780 return -EPERM;
781
782 vol = memdup_user((void __user *)arg, sizeof(*vol));
783 if (IS_ERR(vol))
784 return PTR_ERR(vol);
785
786 switch (cmd) {
787 case BTRFS_IOC_SCAN_DEV:
788 ret = btrfs_scan_one_device(vol->name, FMODE_READ,
789 &btrfs_fs_type, &fs_devices);
790 break;
791 }
792
793 kfree(vol);
794 return ret;
795}
796
797static int btrfs_freeze(struct super_block *sb)
798{
799 struct btrfs_root *root = btrfs_sb(sb);
800 mutex_lock(&root->fs_info->transaction_kthread_mutex);
801 mutex_lock(&root->fs_info->cleaner_mutex);
802 return 0;
803}
804
805static int btrfs_unfreeze(struct super_block *sb)
806{
807 struct btrfs_root *root = btrfs_sb(sb);
808 mutex_unlock(&root->fs_info->cleaner_mutex);
809 mutex_unlock(&root->fs_info->transaction_kthread_mutex);
810 return 0;
811}
812
813static const struct super_operations btrfs_super_ops = {
814 .drop_inode = btrfs_drop_inode,
815 .evict_inode = btrfs_evict_inode,
816 .put_super = btrfs_put_super,
817 .sync_fs = btrfs_sync_fs,
818 .show_options = btrfs_show_options,
819 .write_inode = btrfs_write_inode,
820 .dirty_inode = btrfs_dirty_inode,
821 .alloc_inode = btrfs_alloc_inode,
822 .destroy_inode = btrfs_destroy_inode,
823 .statfs = btrfs_statfs,
824 .remount_fs = btrfs_remount,
825 .freeze_fs = btrfs_freeze,
826 .unfreeze_fs = btrfs_unfreeze,
827};
828
829static const struct file_operations btrfs_ctl_fops = {
830 .unlocked_ioctl = btrfs_control_ioctl,
831 .compat_ioctl = btrfs_control_ioctl,
832 .owner = THIS_MODULE,
833};
834
835static struct miscdevice btrfs_misc = {
836 .minor = BTRFS_MINOR,
837 .name = "btrfs-control",
838 .fops = &btrfs_ctl_fops
839};
840
841MODULE_ALIAS_MISCDEV(BTRFS_MINOR);
842MODULE_ALIAS("devname:btrfs-control");
843
844static int btrfs_interface_init(void)
845{
846 return misc_register(&btrfs_misc);
847}
848
849static void btrfs_interface_exit(void)
850{
851 if (misc_deregister(&btrfs_misc) < 0)
852 printk(KERN_INFO "misc_deregister failed for control device");
853}
854
855static int __init init_btrfs_fs(void)
856{
857 int err;
858
859 err = btrfs_init_sysfs();
860 if (err)
861 return err;
862
863 err = btrfs_init_cachep();
864 if (err)
865 goto free_sysfs;
866
867 err = extent_io_init();
868 if (err)
869 goto free_cachep;
870
871 err = extent_map_init();
872 if (err)
873 goto free_extent_io;
874
875 err = btrfs_interface_init();
876 if (err)
877 goto free_extent_map;
878
879 err = register_filesystem(&btrfs_fs_type);
880 if (err)
881 goto unregister_ioctl;
882
883 printk(KERN_INFO "%s loaded\n", BTRFS_BUILD_VERSION);
884 return 0;
885
886unregister_ioctl:
887 btrfs_interface_exit();
888free_extent_map:
889 extent_map_exit();
890free_extent_io:
891 extent_io_exit();
892free_cachep:
893 btrfs_destroy_cachep();
894free_sysfs:
895 btrfs_exit_sysfs();
896 return err;
897}
898
899static void __exit exit_btrfs_fs(void)
900{
901 btrfs_destroy_cachep();
902 extent_map_exit();
903 extent_io_exit();
904 btrfs_interface_exit();
905 unregister_filesystem(&btrfs_fs_type);
906 btrfs_exit_sysfs();
907 btrfs_cleanup_fs_uuids();
908 btrfs_zlib_exit();
909}
910
911module_init(init_btrfs_fs)
912module_exit(exit_btrfs_fs)
913
914MODULE_LICENSE("GPL");
Linux 6.x block layer and io_uring tree(s)