xref: /linux/fs/btrfs/sysfs.c (revision 2ba9268dd603d23e17643437b2246acb6844953b)
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/sched.h>
20 #include <linux/slab.h>
21 #include <linux/spinlock.h>
22 #include <linux/completion.h>
23 #include <linux/buffer_head.h>
24 #include <linux/kobject.h>
25 #include <linux/bug.h>
26 #include <linux/genhd.h>
27 #include <linux/debugfs.h>
28 
29 #include "ctree.h"
30 #include "disk-io.h"
31 #include "transaction.h"
32 #include "sysfs.h"
33 #include "volumes.h"
34 
35 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
36 
37 static u64 get_features(struct btrfs_fs_info *fs_info,
38 			enum btrfs_feature_set set)
39 {
40 	struct btrfs_super_block *disk_super = fs_info->super_copy;
41 	if (set == FEAT_COMPAT)
42 		return btrfs_super_compat_flags(disk_super);
43 	else if (set == FEAT_COMPAT_RO)
44 		return btrfs_super_compat_ro_flags(disk_super);
45 	else
46 		return btrfs_super_incompat_flags(disk_super);
47 }
48 
49 static void set_features(struct btrfs_fs_info *fs_info,
50 			 enum btrfs_feature_set set, u64 features)
51 {
52 	struct btrfs_super_block *disk_super = fs_info->super_copy;
53 	if (set == FEAT_COMPAT)
54 		btrfs_set_super_compat_flags(disk_super, features);
55 	else if (set == FEAT_COMPAT_RO)
56 		btrfs_set_super_compat_ro_flags(disk_super, features);
57 	else
58 		btrfs_set_super_incompat_flags(disk_super, features);
59 }
60 
61 static int can_modify_feature(struct btrfs_feature_attr *fa)
62 {
63 	int val = 0;
64 	u64 set, clear;
65 	switch (fa->feature_set) {
66 	case FEAT_COMPAT:
67 		set = BTRFS_FEATURE_COMPAT_SAFE_SET;
68 		clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
69 		break;
70 	case FEAT_COMPAT_RO:
71 		set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
72 		clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
73 		break;
74 	case FEAT_INCOMPAT:
75 		set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
76 		clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
77 		break;
78 	default:
79 		printk(KERN_WARNING "btrfs: sysfs: unknown feature set %d\n",
80 				fa->feature_set);
81 		return 0;
82 	}
83 
84 	if (set & fa->feature_bit)
85 		val |= 1;
86 	if (clear & fa->feature_bit)
87 		val |= 2;
88 
89 	return val;
90 }
91 
92 static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
93 				       struct kobj_attribute *a, char *buf)
94 {
95 	int val = 0;
96 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
97 	struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
98 	if (fs_info) {
99 		u64 features = get_features(fs_info, fa->feature_set);
100 		if (features & fa->feature_bit)
101 			val = 1;
102 	} else
103 		val = can_modify_feature(fa);
104 
105 	return snprintf(buf, PAGE_SIZE, "%d\n", val);
106 }
107 
108 static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
109 					struct kobj_attribute *a,
110 					const char *buf, size_t count)
111 {
112 	struct btrfs_fs_info *fs_info;
113 	struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
114 	u64 features, set, clear;
115 	unsigned long val;
116 	int ret;
117 
118 	fs_info = to_fs_info(kobj);
119 	if (!fs_info)
120 		return -EPERM;
121 
122 	ret = kstrtoul(skip_spaces(buf), 0, &val);
123 	if (ret)
124 		return ret;
125 
126 	if (fa->feature_set == FEAT_COMPAT) {
127 		set = BTRFS_FEATURE_COMPAT_SAFE_SET;
128 		clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
129 	} else if (fa->feature_set == FEAT_COMPAT_RO) {
130 		set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
131 		clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
132 	} else {
133 		set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
134 		clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
135 	}
136 
137 	features = get_features(fs_info, fa->feature_set);
138 
139 	/* Nothing to do */
140 	if ((val && (features & fa->feature_bit)) ||
141 	    (!val && !(features & fa->feature_bit)))
142 		return count;
143 
144 	if ((val && !(set & fa->feature_bit)) ||
145 	    (!val && !(clear & fa->feature_bit))) {
146 		btrfs_info(fs_info,
147 			"%sabling feature %s on mounted fs is not supported.",
148 			val ? "En" : "Dis", fa->kobj_attr.attr.name);
149 		return -EPERM;
150 	}
151 
152 	btrfs_info(fs_info, "%s %s feature flag",
153 		   val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
154 
155 	spin_lock(&fs_info->super_lock);
156 	features = get_features(fs_info, fa->feature_set);
157 	if (val)
158 		features |= fa->feature_bit;
159 	else
160 		features &= ~fa->feature_bit;
161 	set_features(fs_info, fa->feature_set, features);
162 	spin_unlock(&fs_info->super_lock);
163 
164 	/*
165 	 * We don't want to do full transaction commit from inside sysfs
166 	 */
167 	btrfs_set_pending(fs_info, COMMIT);
168 	wake_up_process(fs_info->transaction_kthread);
169 
170 	return count;
171 }
172 
173 static umode_t btrfs_feature_visible(struct kobject *kobj,
174 				     struct attribute *attr, int unused)
175 {
176 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
177 	umode_t mode = attr->mode;
178 
179 	if (fs_info) {
180 		struct btrfs_feature_attr *fa;
181 		u64 features;
182 
183 		fa = attr_to_btrfs_feature_attr(attr);
184 		features = get_features(fs_info, fa->feature_set);
185 
186 		if (can_modify_feature(fa))
187 			mode |= S_IWUSR;
188 		else if (!(features & fa->feature_bit))
189 			mode = 0;
190 	}
191 
192 	return mode;
193 }
194 
195 BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
196 BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
197 BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
198 BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
199 BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
200 BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
201 BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
202 BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
203 BTRFS_FEAT_ATTR_INCOMPAT(no_holes, NO_HOLES);
204 
205 static struct attribute *btrfs_supported_feature_attrs[] = {
206 	BTRFS_FEAT_ATTR_PTR(mixed_backref),
207 	BTRFS_FEAT_ATTR_PTR(default_subvol),
208 	BTRFS_FEAT_ATTR_PTR(mixed_groups),
209 	BTRFS_FEAT_ATTR_PTR(compress_lzo),
210 	BTRFS_FEAT_ATTR_PTR(big_metadata),
211 	BTRFS_FEAT_ATTR_PTR(extended_iref),
212 	BTRFS_FEAT_ATTR_PTR(raid56),
213 	BTRFS_FEAT_ATTR_PTR(skinny_metadata),
214 	BTRFS_FEAT_ATTR_PTR(no_holes),
215 	NULL
216 };
217 
218 static const struct attribute_group btrfs_feature_attr_group = {
219 	.name = "features",
220 	.is_visible = btrfs_feature_visible,
221 	.attrs = btrfs_supported_feature_attrs,
222 };
223 
224 static ssize_t btrfs_show_u64(u64 *value_ptr, spinlock_t *lock, char *buf)
225 {
226 	u64 val;
227 	if (lock)
228 		spin_lock(lock);
229 	val = *value_ptr;
230 	if (lock)
231 		spin_unlock(lock);
232 	return snprintf(buf, PAGE_SIZE, "%llu\n", val);
233 }
234 
235 static ssize_t global_rsv_size_show(struct kobject *kobj,
236 				    struct kobj_attribute *ka, char *buf)
237 {
238 	struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
239 	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
240 	return btrfs_show_u64(&block_rsv->size, &block_rsv->lock, buf);
241 }
242 BTRFS_ATTR(global_rsv_size, global_rsv_size_show);
243 
244 static ssize_t global_rsv_reserved_show(struct kobject *kobj,
245 					struct kobj_attribute *a, char *buf)
246 {
247 	struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
248 	struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
249 	return btrfs_show_u64(&block_rsv->reserved, &block_rsv->lock, buf);
250 }
251 BTRFS_ATTR(global_rsv_reserved, global_rsv_reserved_show);
252 
253 #define to_space_info(_kobj) container_of(_kobj, struct btrfs_space_info, kobj)
254 #define to_raid_kobj(_kobj) container_of(_kobj, struct raid_kobject, kobj)
255 
256 static ssize_t raid_bytes_show(struct kobject *kobj,
257 			       struct kobj_attribute *attr, char *buf);
258 BTRFS_RAID_ATTR(total_bytes, raid_bytes_show);
259 BTRFS_RAID_ATTR(used_bytes, raid_bytes_show);
260 
261 static ssize_t raid_bytes_show(struct kobject *kobj,
262 			       struct kobj_attribute *attr, char *buf)
263 
264 {
265 	struct btrfs_space_info *sinfo = to_space_info(kobj->parent);
266 	struct btrfs_block_group_cache *block_group;
267 	int index = to_raid_kobj(kobj)->raid_type;
268 	u64 val = 0;
269 
270 	down_read(&sinfo->groups_sem);
271 	list_for_each_entry(block_group, &sinfo->block_groups[index], list) {
272 		if (&attr->attr == BTRFS_RAID_ATTR_PTR(total_bytes))
273 			val += block_group->key.offset;
274 		else
275 			val += btrfs_block_group_used(&block_group->item);
276 	}
277 	up_read(&sinfo->groups_sem);
278 	return snprintf(buf, PAGE_SIZE, "%llu\n", val);
279 }
280 
281 static struct attribute *raid_attributes[] = {
282 	BTRFS_RAID_ATTR_PTR(total_bytes),
283 	BTRFS_RAID_ATTR_PTR(used_bytes),
284 	NULL
285 };
286 
287 static void release_raid_kobj(struct kobject *kobj)
288 {
289 	kfree(to_raid_kobj(kobj));
290 }
291 
292 struct kobj_type btrfs_raid_ktype = {
293 	.sysfs_ops = &kobj_sysfs_ops,
294 	.release = release_raid_kobj,
295 	.default_attrs = raid_attributes,
296 };
297 
298 #define SPACE_INFO_ATTR(field)						\
299 static ssize_t btrfs_space_info_show_##field(struct kobject *kobj,	\
300 					     struct kobj_attribute *a,	\
301 					     char *buf)			\
302 {									\
303 	struct btrfs_space_info *sinfo = to_space_info(kobj);		\
304 	return btrfs_show_u64(&sinfo->field, &sinfo->lock, buf);	\
305 }									\
306 BTRFS_ATTR(field, btrfs_space_info_show_##field)
307 
308 static ssize_t btrfs_space_info_show_total_bytes_pinned(struct kobject *kobj,
309 						       struct kobj_attribute *a,
310 						       char *buf)
311 {
312 	struct btrfs_space_info *sinfo = to_space_info(kobj);
313 	s64 val = percpu_counter_sum(&sinfo->total_bytes_pinned);
314 	return snprintf(buf, PAGE_SIZE, "%lld\n", val);
315 }
316 
317 SPACE_INFO_ATTR(flags);
318 SPACE_INFO_ATTR(total_bytes);
319 SPACE_INFO_ATTR(bytes_used);
320 SPACE_INFO_ATTR(bytes_pinned);
321 SPACE_INFO_ATTR(bytes_reserved);
322 SPACE_INFO_ATTR(bytes_may_use);
323 SPACE_INFO_ATTR(disk_used);
324 SPACE_INFO_ATTR(disk_total);
325 BTRFS_ATTR(total_bytes_pinned, btrfs_space_info_show_total_bytes_pinned);
326 
327 static struct attribute *space_info_attrs[] = {
328 	BTRFS_ATTR_PTR(flags),
329 	BTRFS_ATTR_PTR(total_bytes),
330 	BTRFS_ATTR_PTR(bytes_used),
331 	BTRFS_ATTR_PTR(bytes_pinned),
332 	BTRFS_ATTR_PTR(bytes_reserved),
333 	BTRFS_ATTR_PTR(bytes_may_use),
334 	BTRFS_ATTR_PTR(disk_used),
335 	BTRFS_ATTR_PTR(disk_total),
336 	BTRFS_ATTR_PTR(total_bytes_pinned),
337 	NULL,
338 };
339 
340 static void space_info_release(struct kobject *kobj)
341 {
342 	struct btrfs_space_info *sinfo = to_space_info(kobj);
343 	percpu_counter_destroy(&sinfo->total_bytes_pinned);
344 	kfree(sinfo);
345 }
346 
347 struct kobj_type space_info_ktype = {
348 	.sysfs_ops = &kobj_sysfs_ops,
349 	.release = space_info_release,
350 	.default_attrs = space_info_attrs,
351 };
352 
353 static const struct attribute *allocation_attrs[] = {
354 	BTRFS_ATTR_PTR(global_rsv_reserved),
355 	BTRFS_ATTR_PTR(global_rsv_size),
356 	NULL,
357 };
358 
359 static ssize_t btrfs_label_show(struct kobject *kobj,
360 				struct kobj_attribute *a, char *buf)
361 {
362 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
363 	char *label = fs_info->super_copy->label;
364 	return snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
365 }
366 
367 static ssize_t btrfs_label_store(struct kobject *kobj,
368 				 struct kobj_attribute *a,
369 				 const char *buf, size_t len)
370 {
371 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
372 	size_t p_len;
373 
374 	if (fs_info->sb->s_flags & MS_RDONLY)
375 		return -EROFS;
376 
377 	/*
378 	 * p_len is the len until the first occurrence of either
379 	 * '\n' or '\0'
380 	 */
381 	p_len = strcspn(buf, "\n");
382 
383 	if (p_len >= BTRFS_LABEL_SIZE)
384 		return -EINVAL;
385 
386 	spin_lock(&fs_info->super_lock);
387 	memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
388 	memcpy(fs_info->super_copy->label, buf, p_len);
389 	spin_unlock(&fs_info->super_lock);
390 
391 	/*
392 	 * We don't want to do full transaction commit from inside sysfs
393 	 */
394 	btrfs_set_pending(fs_info, COMMIT);
395 	wake_up_process(fs_info->transaction_kthread);
396 
397 	return len;
398 }
399 BTRFS_ATTR_RW(label, btrfs_label_show, btrfs_label_store);
400 
401 static ssize_t btrfs_nodesize_show(struct kobject *kobj,
402 				struct kobj_attribute *a, char *buf)
403 {
404 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
405 
406 	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);
407 }
408 
409 BTRFS_ATTR(nodesize, btrfs_nodesize_show);
410 
411 static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
412 				struct kobj_attribute *a, char *buf)
413 {
414 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
415 
416 	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->sectorsize);
417 }
418 
419 BTRFS_ATTR(sectorsize, btrfs_sectorsize_show);
420 
421 static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
422 				struct kobj_attribute *a, char *buf)
423 {
424 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
425 
426 	return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->sectorsize);
427 }
428 
429 BTRFS_ATTR(clone_alignment, btrfs_clone_alignment_show);
430 
431 static struct attribute *btrfs_attrs[] = {
432 	BTRFS_ATTR_PTR(label),
433 	BTRFS_ATTR_PTR(nodesize),
434 	BTRFS_ATTR_PTR(sectorsize),
435 	BTRFS_ATTR_PTR(clone_alignment),
436 	NULL,
437 };
438 
439 static void btrfs_release_super_kobj(struct kobject *kobj)
440 {
441 	struct btrfs_fs_info *fs_info = to_fs_info(kobj);
442 	complete(&fs_info->kobj_unregister);
443 }
444 
445 static struct kobj_type btrfs_ktype = {
446 	.sysfs_ops	= &kobj_sysfs_ops,
447 	.release	= btrfs_release_super_kobj,
448 	.default_attrs	= btrfs_attrs,
449 };
450 
451 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
452 {
453 	if (kobj->ktype != &btrfs_ktype)
454 		return NULL;
455 	return container_of(kobj, struct btrfs_fs_info, super_kobj);
456 }
457 
458 #define NUM_FEATURE_BITS 64
459 static char btrfs_unknown_feature_names[3][NUM_FEATURE_BITS][13];
460 static struct btrfs_feature_attr btrfs_feature_attrs[3][NUM_FEATURE_BITS];
461 
462 static u64 supported_feature_masks[3] = {
463 	[FEAT_COMPAT]    = BTRFS_FEATURE_COMPAT_SUPP,
464 	[FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SUPP,
465 	[FEAT_INCOMPAT]  = BTRFS_FEATURE_INCOMPAT_SUPP,
466 };
467 
468 static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
469 {
470 	int set;
471 
472 	for (set = 0; set < FEAT_MAX; set++) {
473 		int i;
474 		struct attribute *attrs[2];
475 		struct attribute_group agroup = {
476 			.name = "features",
477 			.attrs = attrs,
478 		};
479 		u64 features = get_features(fs_info, set);
480 		features &= ~supported_feature_masks[set];
481 
482 		if (!features)
483 			continue;
484 
485 		attrs[1] = NULL;
486 		for (i = 0; i < NUM_FEATURE_BITS; i++) {
487 			struct btrfs_feature_attr *fa;
488 
489 			if (!(features & (1ULL << i)))
490 				continue;
491 
492 			fa = &btrfs_feature_attrs[set][i];
493 			attrs[0] = &fa->kobj_attr.attr;
494 			if (add) {
495 				int ret;
496 				ret = sysfs_merge_group(&fs_info->super_kobj,
497 							&agroup);
498 				if (ret)
499 					return ret;
500 			} else
501 				sysfs_unmerge_group(&fs_info->super_kobj,
502 						    &agroup);
503 		}
504 
505 	}
506 	return 0;
507 }
508 
509 static void __btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
510 {
511 	kobject_del(&fs_info->super_kobj);
512 	kobject_put(&fs_info->super_kobj);
513 	wait_for_completion(&fs_info->kobj_unregister);
514 }
515 
516 void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
517 {
518 	if (fs_info->space_info_kobj) {
519 		sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
520 		kobject_del(fs_info->space_info_kobj);
521 		kobject_put(fs_info->space_info_kobj);
522 	}
523 	kobject_del(fs_info->device_dir_kobj);
524 	kobject_put(fs_info->device_dir_kobj);
525 	addrm_unknown_feature_attrs(fs_info, false);
526 	sysfs_remove_group(&fs_info->super_kobj, &btrfs_feature_attr_group);
527 	__btrfs_sysfs_remove_one(fs_info);
528 }
529 
530 const char * const btrfs_feature_set_names[3] = {
531 	[FEAT_COMPAT]	 = "compat",
532 	[FEAT_COMPAT_RO] = "compat_ro",
533 	[FEAT_INCOMPAT]	 = "incompat",
534 };
535 
536 char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
537 {
538 	size_t bufsize = 4096; /* safe max, 64 names * 64 bytes */
539 	int len = 0;
540 	int i;
541 	char *str;
542 
543 	str = kmalloc(bufsize, GFP_KERNEL);
544 	if (!str)
545 		return str;
546 
547 	for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
548 		const char *name;
549 
550 		if (!(flags & (1ULL << i)))
551 			continue;
552 
553 		name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
554 		len += snprintf(str + len, bufsize - len, "%s%s",
555 				len ? "," : "", name);
556 	}
557 
558 	return str;
559 }
560 
561 static void init_feature_attrs(void)
562 {
563 	struct btrfs_feature_attr *fa;
564 	int set, i;
565 
566 	BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names) !=
567 		     ARRAY_SIZE(btrfs_feature_attrs));
568 	BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names[0]) !=
569 		     ARRAY_SIZE(btrfs_feature_attrs[0]));
570 
571 	memset(btrfs_feature_attrs, 0, sizeof(btrfs_feature_attrs));
572 	memset(btrfs_unknown_feature_names, 0,
573 	       sizeof(btrfs_unknown_feature_names));
574 
575 	for (i = 0; btrfs_supported_feature_attrs[i]; i++) {
576 		struct btrfs_feature_attr *sfa;
577 		struct attribute *a = btrfs_supported_feature_attrs[i];
578 		int bit;
579 		sfa = attr_to_btrfs_feature_attr(a);
580 		bit = ilog2(sfa->feature_bit);
581 		fa = &btrfs_feature_attrs[sfa->feature_set][bit];
582 
583 		fa->kobj_attr.attr.name = sfa->kobj_attr.attr.name;
584 	}
585 
586 	for (set = 0; set < FEAT_MAX; set++) {
587 		for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
588 			char *name = btrfs_unknown_feature_names[set][i];
589 			fa = &btrfs_feature_attrs[set][i];
590 
591 			if (fa->kobj_attr.attr.name)
592 				continue;
593 
594 			snprintf(name, 13, "%s:%u",
595 				 btrfs_feature_set_names[set], i);
596 
597 			fa->kobj_attr.attr.name = name;
598 			fa->kobj_attr.attr.mode = S_IRUGO;
599 			fa->feature_set = set;
600 			fa->feature_bit = 1ULL << i;
601 		}
602 	}
603 }
604 
605 int btrfs_kobj_rm_device(struct btrfs_fs_info *fs_info,
606 		struct btrfs_device *one_device)
607 {
608 	struct hd_struct *disk;
609 	struct kobject *disk_kobj;
610 
611 	if (!fs_info->device_dir_kobj)
612 		return -EINVAL;
613 
614 	if (one_device && one_device->bdev) {
615 		disk = one_device->bdev->bd_part;
616 		disk_kobj = &part_to_dev(disk)->kobj;
617 
618 		sysfs_remove_link(fs_info->device_dir_kobj,
619 						disk_kobj->name);
620 	}
621 
622 	return 0;
623 }
624 
625 int btrfs_kobj_add_device(struct btrfs_fs_info *fs_info,
626 		struct btrfs_device *one_device)
627 {
628 	int error = 0;
629 	struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
630 	struct btrfs_device *dev;
631 
632 	if (!fs_info->device_dir_kobj)
633 		fs_info->device_dir_kobj = kobject_create_and_add("devices",
634 						&fs_info->super_kobj);
635 
636 	if (!fs_info->device_dir_kobj)
637 		return -ENOMEM;
638 
639 	list_for_each_entry(dev, &fs_devices->devices, dev_list) {
640 		struct hd_struct *disk;
641 		struct kobject *disk_kobj;
642 
643 		if (!dev->bdev)
644 			continue;
645 
646 		if (one_device && one_device != dev)
647 			continue;
648 
649 		disk = dev->bdev->bd_part;
650 		disk_kobj = &part_to_dev(disk)->kobj;
651 
652 		error = sysfs_create_link(fs_info->device_dir_kobj,
653 					  disk_kobj, disk_kobj->name);
654 		if (error)
655 			break;
656 	}
657 
658 	return error;
659 }
660 
661 /* /sys/fs/btrfs/ entry */
662 static struct kset *btrfs_kset;
663 
664 /* /sys/kernel/debug/btrfs */
665 static struct dentry *btrfs_debugfs_root_dentry;
666 
667 /* Debugging tunables and exported data */
668 u64 btrfs_debugfs_test;
669 
670 int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
671 {
672 	int error;
673 
674 	init_completion(&fs_info->kobj_unregister);
675 	fs_info->super_kobj.kset = btrfs_kset;
676 	error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
677 				     "%pU", fs_info->fsid);
678 	if (error)
679 		return error;
680 
681 	error = sysfs_create_group(&fs_info->super_kobj,
682 				   &btrfs_feature_attr_group);
683 	if (error) {
684 		__btrfs_sysfs_remove_one(fs_info);
685 		return error;
686 	}
687 
688 	error = addrm_unknown_feature_attrs(fs_info, true);
689 	if (error)
690 		goto failure;
691 
692 	error = btrfs_kobj_add_device(fs_info, NULL);
693 	if (error)
694 		goto failure;
695 
696 	fs_info->space_info_kobj = kobject_create_and_add("allocation",
697 						  &fs_info->super_kobj);
698 	if (!fs_info->space_info_kobj) {
699 		error = -ENOMEM;
700 		goto failure;
701 	}
702 
703 	error = sysfs_create_files(fs_info->space_info_kobj, allocation_attrs);
704 	if (error)
705 		goto failure;
706 
707 	return 0;
708 failure:
709 	btrfs_sysfs_remove_one(fs_info);
710 	return error;
711 }
712 
713 static int btrfs_init_debugfs(void)
714 {
715 #ifdef CONFIG_DEBUG_FS
716 	btrfs_debugfs_root_dentry = debugfs_create_dir("btrfs", NULL);
717 	if (!btrfs_debugfs_root_dentry)
718 		return -ENOMEM;
719 
720 	debugfs_create_u64("test", S_IRUGO | S_IWUGO, btrfs_debugfs_root_dentry,
721 			&btrfs_debugfs_test);
722 #endif
723 	return 0;
724 }
725 
726 int btrfs_init_sysfs(void)
727 {
728 	int ret;
729 
730 	btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
731 	if (!btrfs_kset)
732 		return -ENOMEM;
733 
734 	ret = btrfs_init_debugfs();
735 	if (ret)
736 		goto out1;
737 
738 	init_feature_attrs();
739 	ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
740 	if (ret)
741 		goto out2;
742 
743 	return 0;
744 out2:
745 	debugfs_remove_recursive(btrfs_debugfs_root_dentry);
746 out1:
747 	kset_unregister(btrfs_kset);
748 
749 	return ret;
750 }
751 
752 void btrfs_exit_sysfs(void)
753 {
754 	sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
755 	kset_unregister(btrfs_kset);
756 	debugfs_remove_recursive(btrfs_debugfs_root_dentry);
757 }
758 
759