fs/btrfs/sysfs.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/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
  28 #include "ctree.h"
  29 #include "disk-io.h"
  30 #include "transaction.h"
  31 #include "sysfs.h"
  32 #include "volumes.h"
  33
  34 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
  35
  36 static u64 get_features(struct btrfs_fs_info *fs_info,
  37                         enum btrfs_feature_set set)
  38 {
  39         struct btrfs_super_block *disk_super = fs_info->super_copy;
  40         if (set == FEAT_COMPAT)
  41                 return btrfs_super_compat_flags(disk_super);
  42         else if (set == FEAT_COMPAT_RO)
  43                 return btrfs_super_compat_ro_flags(disk_super);
  44         else
  45                 return btrfs_super_incompat_flags(disk_super);
  46 }
  47
  48 static void set_features(struct btrfs_fs_info *fs_info,
  49                          enum btrfs_feature_set set, u64 features)
  50 {
  51         struct btrfs_super_block *disk_super = fs_info->super_copy;
  52         if (set == FEAT_COMPAT)
  53                 btrfs_set_super_compat_flags(disk_super, features);
  54         else if (set == FEAT_COMPAT_RO)
  55                 btrfs_set_super_compat_ro_flags(disk_super, features);
  56         else
  57                 btrfs_set_super_incompat_flags(disk_super, features);
  58 }
  59
  60 static int can_modify_feature(struct btrfs_feature_attr *fa)
  61 {
  62         int val = 0;
  63         u64 set, clear;
  64         switch (fa->feature_set) {
  65         case FEAT_COMPAT:
  66                 set = BTRFS_FEATURE_COMPAT_SAFE_SET;
  67                 clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
  68                 break;
  69         case FEAT_COMPAT_RO:
  70                 set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
  71                 clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
  72                 break;
  73         case FEAT_INCOMPAT:
  74                 set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
  75                 clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
  76                 break;
  77         default:
  78                 BUG();
  79         }
  80
  81         if (set & fa->feature_bit)
  82                 val |= 1;
  83         if (clear & fa->feature_bit)
  84                 val |= 2;
  85
  86         return val;
  87 }
  88
  89 static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
  90                                        struct kobj_attribute *a, char *buf)
  91 {
  92         int val = 0;
  93         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
  94         struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
  95         if (fs_info) {
  96                 u64 features = get_features(fs_info, fa->feature_set);
  97                 if (features & fa->feature_bit)
  98                         val = 1;
  99         } else
 100                 val = can_modify_feature(fa);
 101
 102         return snprintf(buf, PAGE_SIZE, "%d\n", val);
 103 }
 104
 105 static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
 106                                         struct kobj_attribute *a,
 107                                         const char *buf, size_t count)
 108 {
 109         struct btrfs_fs_info *fs_info;
 110         struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
 111         struct btrfs_trans_handle *trans;
 112         u64 features, set, clear;
 113         unsigned long val;
 114         int ret;
 115
 116         fs_info = to_fs_info(kobj);
 117         if (!fs_info)
 118                 return -EPERM;
 119
 120         ret = kstrtoul(skip_spaces(buf), 0, &val);
 121         if (ret)
 122                 return ret;
 123
 124         if (fa->feature_set == FEAT_COMPAT) {
 125                 set = BTRFS_FEATURE_COMPAT_SAFE_SET;
 126                 clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
 127         } else if (fa->feature_set == FEAT_COMPAT_RO) {
 128                 set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
 129                 clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
 130         } else {
 131                 set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
 132                 clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
 133         }
 134
 135         features = get_features(fs_info, fa->feature_set);
 136
 137         /* Nothing to do */
 138         if ((val && (features & fa->feature_bit)) ||
 139             (!val && !(features & fa->feature_bit)))
 140                 return count;
 141
 142         if ((val && !(set & fa->feature_bit)) ||
 143             (!val && !(clear & fa->feature_bit))) {
 144                 btrfs_info(fs_info,
 145                         "%sabling feature %s on mounted fs is not supported.",
 146                         val ? "En" : "Dis", fa->kobj_attr.attr.name);
 147                 return -EPERM;
 148         }
 149
 150         btrfs_info(fs_info, "%s %s feature flag",
 151                    val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
 152
 153         trans = btrfs_start_transaction(fs_info->fs_root, 1);
 154         if (IS_ERR(trans))
 155                 return PTR_ERR(trans);
 156
 157         spin_lock(&fs_info->super_lock);
 158         features = get_features(fs_info, fa->feature_set);
 159         if (val)
 160                 features |= fa->feature_bit;
 161         else
 162                 features &= ~fa->feature_bit;
 163         set_features(fs_info, fa->feature_set, features);
 164         spin_unlock(&fs_info->super_lock);
 165
 166         ret = btrfs_commit_transaction(trans, fs_info->fs_root);
 167         if (ret)
 168                 return ret;
 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(compress_lzov2, COMPRESS_LZOv2);
 200 BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
 201 BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
 202 BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
 203 BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
 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(compress_lzov2),
 211         BTRFS_FEAT_ATTR_PTR(big_metadata),
 212         BTRFS_FEAT_ATTR_PTR(extended_iref),
 213         BTRFS_FEAT_ATTR_PTR(raid56),
 214         BTRFS_FEAT_ATTR_PTR(skinny_metadata),
 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, 0444, 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, 0444, global_rsv_reserved_show);
 252
 253 #define to_space_info(_kobj) container_of(_kobj, struct btrfs_space_info, kobj)
 254
 255 static ssize_t raid_bytes_show(struct kobject *kobj,
 256                                struct kobj_attribute *attr, char *buf);
 257 BTRFS_RAID_ATTR(total_bytes, raid_bytes_show);
 258 BTRFS_RAID_ATTR(used_bytes, raid_bytes_show);
 259
 260 static ssize_t raid_bytes_show(struct kobject *kobj,
 261                                struct kobj_attribute *attr, char *buf)
 262
 263 {
 264         struct btrfs_space_info *sinfo = to_space_info(kobj->parent);
 265         struct btrfs_block_group_cache *block_group;
 266         int index = kobj - sinfo->block_group_kobjs;
 267         u64 val = 0;
 268
 269         down_read(&sinfo->groups_sem);
 270         list_for_each_entry(block_group, &sinfo->block_groups[index], list) {
 271                 if (&attr->attr == BTRFS_RAID_ATTR_PTR(total_bytes))
 272                         val += block_group->key.offset;
 273                 else
 274                         val += btrfs_block_group_used(&block_group->item);
 275         }
 276         up_read(&sinfo->groups_sem);
 277         return snprintf(buf, PAGE_SIZE, "%llu\n", val);
 278 }
 279
 280 static struct attribute *raid_attributes[] = {
 281         BTRFS_RAID_ATTR_PTR(total_bytes),
 282         BTRFS_RAID_ATTR_PTR(used_bytes),
 283         NULL
 284 };
 285
 286 static void release_raid_kobj(struct kobject *kobj)
 287 {
 288         kobject_put(kobj->parent);
 289 }
 290
 291 struct kobj_type btrfs_raid_ktype = {
 292         .sysfs_ops = &kobj_sysfs_ops,
 293         .release = release_raid_kobj,
 294         .default_attrs = raid_attributes,
 295 };
 296
 297 #define SPACE_INFO_ATTR(field)                                          \
 298 static ssize_t btrfs_space_info_show_##field(struct kobject *kobj,      \
 299                                              struct kobj_attribute *a,  \
 300                                              char *buf)                 \
 301 {                                                                       \
 302         struct btrfs_space_info *sinfo = to_space_info(kobj);           \
 303         return btrfs_show_u64(&sinfo->field, &sinfo->lock, buf);        \
 304 }                                                                       \
 305 BTRFS_ATTR(field, 0444, btrfs_space_info_show_##field)
 306
 307 static ssize_t btrfs_space_info_show_total_bytes_pinned(struct kobject *kobj,
 308                                                        struct kobj_attribute *a,
 309                                                        char *buf)
 310 {
 311         struct btrfs_space_info *sinfo = to_space_info(kobj);
 312         s64 val = percpu_counter_sum(&sinfo->total_bytes_pinned);
 313         return snprintf(buf, PAGE_SIZE, "%lld\n", val);
 314 }
 315
 316 SPACE_INFO_ATTR(flags);
 317 SPACE_INFO_ATTR(total_bytes);
 318 SPACE_INFO_ATTR(bytes_used);
 319 SPACE_INFO_ATTR(bytes_pinned);
 320 SPACE_INFO_ATTR(bytes_reserved);
 321 SPACE_INFO_ATTR(bytes_may_use);
 322 SPACE_INFO_ATTR(disk_used);
 323 SPACE_INFO_ATTR(disk_total);
 324 BTRFS_ATTR(total_bytes_pinned, 0444, btrfs_space_info_show_total_bytes_pinned);
 325
 326 static struct attribute *space_info_attrs[] = {
 327         BTRFS_ATTR_PTR(flags),
 328         BTRFS_ATTR_PTR(total_bytes),
 329         BTRFS_ATTR_PTR(bytes_used),
 330         BTRFS_ATTR_PTR(bytes_pinned),
 331         BTRFS_ATTR_PTR(bytes_reserved),
 332         BTRFS_ATTR_PTR(bytes_may_use),
 333         BTRFS_ATTR_PTR(disk_used),
 334         BTRFS_ATTR_PTR(disk_total),
 335         BTRFS_ATTR_PTR(total_bytes_pinned),
 336         NULL,
 337 };
 338
 339 static void space_info_release(struct kobject *kobj)
 340 {
 341         struct btrfs_space_info *sinfo = to_space_info(kobj);
 342         percpu_counter_destroy(&sinfo->total_bytes_pinned);
 343         kfree(sinfo);
 344 }
 345
 346 struct kobj_type space_info_ktype = {
 347         .sysfs_ops = &kobj_sysfs_ops,
 348         .release = space_info_release,
 349         .default_attrs = space_info_attrs,
 350 };
 351
 352 static const struct attribute *allocation_attrs[] = {
 353         BTRFS_ATTR_PTR(global_rsv_reserved),
 354         BTRFS_ATTR_PTR(global_rsv_size),
 355         NULL,
 356 };
 357
 358 static void btrfs_release_super_kobj(struct kobject *kobj)
 359 {
 360         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 361         complete(&fs_info->kobj_unregister);
 362 }
 363
 364 static struct kobj_type btrfs_ktype = {
 365         .sysfs_ops      = &kobj_sysfs_ops,
 366         .release        = btrfs_release_super_kobj,
 367 };
 368
 369 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
 370 {
 371         if (kobj->ktype != &btrfs_ktype)
 372                 return NULL;
 373         return container_of(kobj, struct btrfs_fs_info, super_kobj);
 374 }
 375
 376 void btrfs_sysfs_remove_one(struct btrfs_fs_info *fs_info)
 377 {
 378         sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
 379         kobject_del(fs_info->device_dir_kobj);
 380         kobject_put(fs_info->device_dir_kobj);
 381         kobject_del(fs_info->space_info_kobj);
 382         kobject_put(fs_info->space_info_kobj);
 383         kobject_del(&fs_info->super_kobj);
 384         kobject_put(&fs_info->super_kobj);
 385         wait_for_completion(&fs_info->kobj_unregister);
 386 }
 387
 388 const char * const btrfs_feature_set_names[3] = {
 389         [FEAT_COMPAT]    = "compat",
 390         [FEAT_COMPAT_RO] = "compat_ro",
 391         [FEAT_INCOMPAT]  = "incompat",
 392 };
 393
 394 #define NUM_FEATURE_BITS 64
 395 static char btrfs_unknown_feature_names[3][NUM_FEATURE_BITS][13];
 396 static struct btrfs_feature_attr btrfs_feature_attrs[3][NUM_FEATURE_BITS];
 397
 398 char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
 399 {
 400         size_t bufsize = 4096; /* safe max, 64 names * 64 bytes */
 401         int len = 0;
 402         int i;
 403         char *str;
 404
 405         str = kmalloc(bufsize, GFP_KERNEL);
 406         if (!str)
 407                 return str;
 408
 409         for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
 410                 const char *name;
 411
 412                 if (!(flags & (1ULL << i)))
 413                         continue;
 414
 415                 name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
 416                 len += snprintf(str + len, bufsize - len, "%s%s",
 417                                 len ? "," : "", name);
 418         }
 419
 420         return str;
 421 }
 422
 423 static void init_feature_attrs(void)
 424 {
 425         struct btrfs_feature_attr *fa;
 426         int set, i;
 427
 428         BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names) !=
 429                      ARRAY_SIZE(btrfs_feature_attrs));
 430         BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names[0]) !=
 431                      ARRAY_SIZE(btrfs_feature_attrs[0]));
 432
 433         memset(btrfs_feature_attrs, 0, sizeof(btrfs_feature_attrs));
 434         memset(btrfs_unknown_feature_names, 0,
 435                sizeof(btrfs_unknown_feature_names));
 436
 437         for (i = 0; btrfs_supported_feature_attrs[i]; i++) {
 438                 struct btrfs_feature_attr *sfa;
 439                 struct attribute *a = btrfs_supported_feature_attrs[i];
 440                 int bit;
 441                 sfa = attr_to_btrfs_feature_attr(a);
 442                 bit = ilog2(sfa->feature_bit);
 443                 fa = &btrfs_feature_attrs[sfa->feature_set][bit];
 444
 445                 fa->kobj_attr.attr.name = sfa->kobj_attr.attr.name;
 446         }
 447
 448         for (set = 0; set < FEAT_MAX; set++) {
 449                 for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
 450                         char *name = btrfs_unknown_feature_names[set][i];
 451                         fa = &btrfs_feature_attrs[set][i];
 452
 453                         if (fa->kobj_attr.attr.name)
 454                                 continue;
 455
 456                         snprintf(name, 13, "%s:%u",
 457                                  btrfs_feature_set_names[set], i);
 458
 459                         fa->kobj_attr.attr.name = name;
 460                         fa->kobj_attr.attr.mode = S_IRUGO;
 461                         fa->feature_set = set;
 462                         fa->feature_bit = 1ULL << i;
 463                 }
 464         }
 465 }
 466
 467 static u64 supported_feature_masks[3] = {
 468         [FEAT_COMPAT]    = BTRFS_FEATURE_COMPAT_SUPP,
 469         [FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SUPP,
 470         [FEAT_INCOMPAT]  = BTRFS_FEATURE_INCOMPAT_SUPP,
 471 };
 472
 473 static int add_unknown_feature_attrs(struct btrfs_fs_info *fs_info)
 474 {
 475         int set;
 476
 477         for (set = 0; set < FEAT_MAX; set++) {
 478                 int i, count, ret, index = 0;
 479                 struct attribute **attrs;
 480                 struct attribute_group agroup = {
 481                         .name = "features",
 482                 };
 483                 u64 features = get_features(fs_info, set);
 484                 features &= ~supported_feature_masks[set];
 485
 486                 count = hweight64(features);
 487
 488                 if (!count)
 489                         continue;
 490
 491                 attrs = kcalloc(count + 1, sizeof(void *), GFP_KERNEL);
 492
 493                 for (i = 0; i < NUM_FEATURE_BITS; i++) {
 494                         struct btrfs_feature_attr *fa;
 495
 496                         if (!(features & (1ULL << i)))
 497                                 continue;
 498
 499                         fa = &btrfs_feature_attrs[set][i];
 500                         attrs[index++] = &fa->kobj_attr.attr;
 501                 }
 502
 503                 attrs[index] = NULL;
 504                 agroup.attrs = attrs;
 505
 506                 ret = sysfs_merge_group(&fs_info->super_kobj, &agroup);
 507                 kfree(attrs);
 508                 if (ret)
 509                         return ret;
 510         }
 511         return 0;
 512 }
 513
 514 static int add_device_membership(struct btrfs_fs_info *fs_info)
 515 {
 516         int error = 0;
 517         struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
 518         struct btrfs_device *dev;
 519
 520         fs_info->device_dir_kobj = kobject_create_and_add("devices",
 521                                                 &fs_info->super_kobj);
 522         if (!fs_info->device_dir_kobj)
 523                 return -ENOMEM;
 524
 525         list_for_each_entry(dev, &fs_devices->devices, dev_list) {
 526                 struct hd_struct *disk = dev->bdev->bd_part;
 527                 struct kobject *disk_kobj = &part_to_dev(disk)->kobj;
 528
 529                 error = sysfs_create_link(fs_info->device_dir_kobj,
 530                                           disk_kobj, disk_kobj->name);
 531                 if (error)
 532                         break;
 533         }
 534
 535         return error;
 536 }
 537
 538 /* /sys/fs/btrfs/ entry */
 539 static struct kset *btrfs_kset;
 540
 541 int btrfs_sysfs_add_one(struct btrfs_fs_info *fs_info)
 542 {
 543         int error;
 544
 545         init_completion(&fs_info->kobj_unregister);
 546         fs_info->super_kobj.kset = btrfs_kset;
 547         error = kobject_init_and_add(&fs_info->super_kobj, &btrfs_ktype, NULL,
 548                                      "%pU", fs_info->fsid);
 549
 550         error = sysfs_create_group(&fs_info->super_kobj,
 551                                    &btrfs_feature_attr_group);
 552         if (error)
 553                 goto failure;
 554
 555         error = add_unknown_feature_attrs(fs_info);
 556         if (error)
 557                 goto failure;
 558
 559         error = add_device_membership(fs_info);
 560         if (error)
 561                 goto failure;
 562
 563         fs_info->space_info_kobj = kobject_create_and_add("allocation",
 564                                                   &fs_info->super_kobj);
 565         if (!fs_info->space_info_kobj) {
 566                 error = -ENOMEM;
 567                 goto failure;
 568         }
 569
 570         error = sysfs_create_files(fs_info->space_info_kobj, allocation_attrs);
 571         if (error)
 572                 goto failure;
 573
 574         return 0;
 575 failure:
 576         btrfs_sysfs_remove_one(fs_info);
 577         return error;
 578 }
 579
 580 int btrfs_init_sysfs(void)
 581 {
 582         int ret;
 583         btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
 584         if (!btrfs_kset)
 585                 return -ENOMEM;
 586
 587         init_feature_attrs();
 588
 589         ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
 590         if (ret) {
 591                 kset_unregister(btrfs_kset);
 592                 return ret;
 593         }
 594
 595         return 0;
 596 }
 597
 598 void btrfs_exit_sysfs(void)
 599 {
 600         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
 601         kset_unregister(btrfs_kset);
 602 }
 603