fs/btrfs/sysfs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/sched.h>
   7 #include <linux/sched/mm.h>
   8 #include <linux/slab.h>
   9 #include <linux/spinlock.h>
  10 #include <linux/completion.h>
  11 #include <linux/bug.h>
  12 #include <crypto/hash.h>
  13
  14 #include "ctree.h"
  15 #include "disk-io.h"
  16 #include "transaction.h"
  17 #include "sysfs.h"
  18 #include "volumes.h"
  19 #include "space-info.h"
  20 #include "block-group.h"
  21
  22 struct btrfs_feature_attr {
  23         struct kobj_attribute kobj_attr;
  24         enum btrfs_feature_set feature_set;
  25         u64 feature_bit;
  26 };
  27
  28 /* For raid type sysfs entries */
  29 struct raid_kobject {
  30         u64 flags;
  31         struct kobject kobj;
  32 };
  33
  34 #define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)                   \
  35 {                                                                       \
  36         .attr   = { .name = __stringify(_name), .mode = _mode },        \
  37         .show   = _show,                                                \
  38         .store  = _store,                                               \
  39 }
  40
  41 #define BTRFS_ATTR_RW(_prefix, _name, _show, _store)                    \
  42         static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
  43                         __INIT_KOBJ_ATTR(_name, 0644, _show, _store)
  44
  45 #define BTRFS_ATTR(_prefix, _name, _show)                               \
  46         static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
  47                         __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
  48
  49 #define BTRFS_ATTR_PTR(_prefix, _name)                                  \
  50         (&btrfs_attr_##_prefix##_##_name.attr)
  51
  52 #define BTRFS_FEAT_ATTR(_name, _feature_set, _feature_prefix, _feature_bit)  \
  53 static struct btrfs_feature_attr btrfs_attr_features_##_name = {             \
  54         .kobj_attr = __INIT_KOBJ_ATTR(_name, S_IRUGO,                        \
  55                                       btrfs_feature_attr_show,               \
  56                                       btrfs_feature_attr_store),             \
  57         .feature_set    = _feature_set,                                      \
  58         .feature_bit    = _feature_prefix ##_## _feature_bit,                \
  59 }
  60 #define BTRFS_FEAT_ATTR_PTR(_name)                                           \
  61         (&btrfs_attr_features_##_name.kobj_attr.attr)
  62
  63 #define BTRFS_FEAT_ATTR_COMPAT(name, feature) \
  64         BTRFS_FEAT_ATTR(name, FEAT_COMPAT, BTRFS_FEATURE_COMPAT, feature)
  65 #define BTRFS_FEAT_ATTR_COMPAT_RO(name, feature) \
  66         BTRFS_FEAT_ATTR(name, FEAT_COMPAT_RO, BTRFS_FEATURE_COMPAT_RO, feature)
  67 #define BTRFS_FEAT_ATTR_INCOMPAT(name, feature) \
  68         BTRFS_FEAT_ATTR(name, FEAT_INCOMPAT, BTRFS_FEATURE_INCOMPAT, feature)
  69
  70 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
  71 static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj);
  72
  73 static struct btrfs_feature_attr *to_btrfs_feature_attr(struct kobj_attribute *a)
  74 {
  75         return container_of(a, struct btrfs_feature_attr, kobj_attr);
  76 }
  77
  78 static struct kobj_attribute *attr_to_btrfs_attr(struct attribute *attr)
  79 {
  80         return container_of(attr, struct kobj_attribute, attr);
  81 }
  82
  83 static struct btrfs_feature_attr *attr_to_btrfs_feature_attr(
  84                 struct attribute *attr)
  85 {
  86         return to_btrfs_feature_attr(attr_to_btrfs_attr(attr));
  87 }
  88
  89 static u64 get_features(struct btrfs_fs_info *fs_info,
  90                         enum btrfs_feature_set set)
  91 {
  92         struct btrfs_super_block *disk_super = fs_info->super_copy;
  93         if (set == FEAT_COMPAT)
  94                 return btrfs_super_compat_flags(disk_super);
  95         else if (set == FEAT_COMPAT_RO)
  96                 return btrfs_super_compat_ro_flags(disk_super);
  97         else
  98                 return btrfs_super_incompat_flags(disk_super);
  99 }
 100
 101 static void set_features(struct btrfs_fs_info *fs_info,
 102                          enum btrfs_feature_set set, u64 features)
 103 {
 104         struct btrfs_super_block *disk_super = fs_info->super_copy;
 105         if (set == FEAT_COMPAT)
 106                 btrfs_set_super_compat_flags(disk_super, features);
 107         else if (set == FEAT_COMPAT_RO)
 108                 btrfs_set_super_compat_ro_flags(disk_super, features);
 109         else
 110                 btrfs_set_super_incompat_flags(disk_super, features);
 111 }
 112
 113 static int can_modify_feature(struct btrfs_feature_attr *fa)
 114 {
 115         int val = 0;
 116         u64 set, clear;
 117         switch (fa->feature_set) {
 118         case FEAT_COMPAT:
 119                 set = BTRFS_FEATURE_COMPAT_SAFE_SET;
 120                 clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
 121                 break;
 122         case FEAT_COMPAT_RO:
 123                 set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
 124                 clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
 125                 break;
 126         case FEAT_INCOMPAT:
 127                 set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
 128                 clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
 129                 break;
 130         default:
 131                 pr_warn("btrfs: sysfs: unknown feature set %d\n",
 132                                 fa->feature_set);
 133                 return 0;
 134         }
 135
 136         if (set & fa->feature_bit)
 137                 val |= 1;
 138         if (clear & fa->feature_bit)
 139                 val |= 2;
 140
 141         return val;
 142 }
 143
 144 static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
 145                                        struct kobj_attribute *a, char *buf)
 146 {
 147         int val = 0;
 148         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 149         struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
 150         if (fs_info) {
 151                 u64 features = get_features(fs_info, fa->feature_set);
 152                 if (features & fa->feature_bit)
 153                         val = 1;
 154         } else
 155                 val = can_modify_feature(fa);
 156
 157         return snprintf(buf, PAGE_SIZE, "%d\n", val);
 158 }
 159
 160 static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
 161                                         struct kobj_attribute *a,
 162                                         const char *buf, size_t count)
 163 {
 164         struct btrfs_fs_info *fs_info;
 165         struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
 166         u64 features, set, clear;
 167         unsigned long val;
 168         int ret;
 169
 170         fs_info = to_fs_info(kobj);
 171         if (!fs_info)
 172                 return -EPERM;
 173
 174         if (sb_rdonly(fs_info->sb))
 175                 return -EROFS;
 176
 177         ret = kstrtoul(skip_spaces(buf), 0, &val);
 178         if (ret)
 179                 return ret;
 180
 181         if (fa->feature_set == FEAT_COMPAT) {
 182                 set = BTRFS_FEATURE_COMPAT_SAFE_SET;
 183                 clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
 184         } else if (fa->feature_set == FEAT_COMPAT_RO) {
 185                 set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
 186                 clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
 187         } else {
 188                 set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
 189                 clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
 190         }
 191
 192         features = get_features(fs_info, fa->feature_set);
 193
 194         /* Nothing to do */
 195         if ((val && (features & fa->feature_bit)) ||
 196             (!val && !(features & fa->feature_bit)))
 197                 return count;
 198
 199         if ((val && !(set & fa->feature_bit)) ||
 200             (!val && !(clear & fa->feature_bit))) {
 201                 btrfs_info(fs_info,
 202                         "%sabling feature %s on mounted fs is not supported.",
 203                         val ? "En" : "Dis", fa->kobj_attr.attr.name);
 204                 return -EPERM;
 205         }
 206
 207         btrfs_info(fs_info, "%s %s feature flag",
 208                    val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
 209
 210         spin_lock(&fs_info->super_lock);
 211         features = get_features(fs_info, fa->feature_set);
 212         if (val)
 213                 features |= fa->feature_bit;
 214         else
 215                 features &= ~fa->feature_bit;
 216         set_features(fs_info, fa->feature_set, features);
 217         spin_unlock(&fs_info->super_lock);
 218
 219         /*
 220          * We don't want to do full transaction commit from inside sysfs
 221          */
 222         btrfs_set_pending(fs_info, COMMIT);
 223         wake_up_process(fs_info->transaction_kthread);
 224
 225         return count;
 226 }
 227
 228 static umode_t btrfs_feature_visible(struct kobject *kobj,
 229                                      struct attribute *attr, int unused)
 230 {
 231         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 232         umode_t mode = attr->mode;
 233
 234         if (fs_info) {
 235                 struct btrfs_feature_attr *fa;
 236                 u64 features;
 237
 238                 fa = attr_to_btrfs_feature_attr(attr);
 239                 features = get_features(fs_info, fa->feature_set);
 240
 241                 if (can_modify_feature(fa))
 242                         mode |= S_IWUSR;
 243                 else if (!(features & fa->feature_bit))
 244                         mode = 0;
 245         }
 246
 247         return mode;
 248 }
 249
 250 BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
 251 BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
 252 BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
 253 BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
 254 BTRFS_FEAT_ATTR_INCOMPAT(compress_zstd, COMPRESS_ZSTD);
 255 BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
 256 BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
 257 BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
 258 BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
 259 BTRFS_FEAT_ATTR_INCOMPAT(no_holes, NO_HOLES);
 260 BTRFS_FEAT_ATTR_INCOMPAT(metadata_uuid, METADATA_UUID);
 261 BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
 262 BTRFS_FEAT_ATTR_INCOMPAT(raid1c34, RAID1C34);
 263
 264 static struct attribute *btrfs_supported_feature_attrs[] = {
 265         BTRFS_FEAT_ATTR_PTR(mixed_backref),
 266         BTRFS_FEAT_ATTR_PTR(default_subvol),
 267         BTRFS_FEAT_ATTR_PTR(mixed_groups),
 268         BTRFS_FEAT_ATTR_PTR(compress_lzo),
 269         BTRFS_FEAT_ATTR_PTR(compress_zstd),
 270         BTRFS_FEAT_ATTR_PTR(big_metadata),
 271         BTRFS_FEAT_ATTR_PTR(extended_iref),
 272         BTRFS_FEAT_ATTR_PTR(raid56),
 273         BTRFS_FEAT_ATTR_PTR(skinny_metadata),
 274         BTRFS_FEAT_ATTR_PTR(no_holes),
 275         BTRFS_FEAT_ATTR_PTR(metadata_uuid),
 276         BTRFS_FEAT_ATTR_PTR(free_space_tree),
 277         BTRFS_FEAT_ATTR_PTR(raid1c34),
 278         NULL
 279 };
 280
 281 /*
 282  * Features which depend on feature bits and may differ between each fs.
 283  *
 284  * /sys/fs/btrfs/features lists all available features of this kernel while
 285  * /sys/fs/btrfs/UUID/features shows features of the fs which are enabled or
 286  * can be changed online.
 287  */
 288 static const struct attribute_group btrfs_feature_attr_group = {
 289         .name = "features",
 290         .is_visible = btrfs_feature_visible,
 291         .attrs = btrfs_supported_feature_attrs,
 292 };
 293
 294 static ssize_t rmdir_subvol_show(struct kobject *kobj,
 295                                  struct kobj_attribute *ka, char *buf)
 296 {
 297         return snprintf(buf, PAGE_SIZE, "0\n");
 298 }
 299 BTRFS_ATTR(static_feature, rmdir_subvol, rmdir_subvol_show);
 300
 301 static ssize_t supported_checksums_show(struct kobject *kobj,
 302                                         struct kobj_attribute *a, char *buf)
 303 {
 304         ssize_t ret = 0;
 305         int i;
 306
 307         for (i = 0; i < btrfs_get_num_csums(); i++) {
 308                 /*
 309                  * This "trick" only works as long as 'enum btrfs_csum_type' has
 310                  * no holes in it
 311                  */
 312                 ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
 313                                 (i == 0 ? "" : " "), btrfs_super_csum_name(i));
 314
 315         }
 316
 317         ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n");
 318         return ret;
 319 }
 320 BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);
 321
 322 static struct attribute *btrfs_supported_static_feature_attrs[] = {
 323         BTRFS_ATTR_PTR(static_feature, rmdir_subvol),
 324         BTRFS_ATTR_PTR(static_feature, supported_checksums),
 325         NULL
 326 };
 327
 328 /*
 329  * Features which only depend on kernel version.
 330  *
 331  * These are listed in /sys/fs/btrfs/features along with
 332  * btrfs_feature_attr_group
 333  */
 334 static const struct attribute_group btrfs_static_feature_attr_group = {
 335         .name = "features",
 336         .attrs = btrfs_supported_static_feature_attrs,
 337 };
 338
 339 #ifdef CONFIG_BTRFS_DEBUG
 340
 341 /*
 342  * Discard statistics and tunables
 343  */
 344 static const struct attribute *discard_debug_attrs[] = {
 345         NULL,
 346 };
 347
 348 /*
 349  * Runtime debugging exported via sysfs
 350  *
 351  * /sys/fs/btrfs/debug - applies to module or all filesystems
 352  * /sys/fs/btrfs/UUID  - applies only to the given filesystem
 353  */
 354 static const struct attribute *btrfs_debug_mount_attrs[] = {
 355         NULL,
 356 };
 357
 358 static struct attribute *btrfs_debug_feature_attrs[] = {
 359         NULL
 360 };
 361
 362 static const struct attribute_group btrfs_debug_feature_attr_group = {
 363         .name = "debug",
 364         .attrs = btrfs_debug_feature_attrs,
 365 };
 366
 367 #endif
 368
 369 static ssize_t btrfs_show_u64(u64 *value_ptr, spinlock_t *lock, char *buf)
 370 {
 371         u64 val;
 372         if (lock)
 373                 spin_lock(lock);
 374         val = *value_ptr;
 375         if (lock)
 376                 spin_unlock(lock);
 377         return snprintf(buf, PAGE_SIZE, "%llu\n", val);
 378 }
 379
 380 static ssize_t global_rsv_size_show(struct kobject *kobj,
 381                                     struct kobj_attribute *ka, char *buf)
 382 {
 383         struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
 384         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
 385         return btrfs_show_u64(&block_rsv->size, &block_rsv->lock, buf);
 386 }
 387 BTRFS_ATTR(allocation, global_rsv_size, global_rsv_size_show);
 388
 389 static ssize_t global_rsv_reserved_show(struct kobject *kobj,
 390                                         struct kobj_attribute *a, char *buf)
 391 {
 392         struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
 393         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
 394         return btrfs_show_u64(&block_rsv->reserved, &block_rsv->lock, buf);
 395 }
 396 BTRFS_ATTR(allocation, global_rsv_reserved, global_rsv_reserved_show);
 397
 398 #define to_space_info(_kobj) container_of(_kobj, struct btrfs_space_info, kobj)
 399 #define to_raid_kobj(_kobj) container_of(_kobj, struct raid_kobject, kobj)
 400
 401 static ssize_t raid_bytes_show(struct kobject *kobj,
 402                                struct kobj_attribute *attr, char *buf);
 403 BTRFS_ATTR(raid, total_bytes, raid_bytes_show);
 404 BTRFS_ATTR(raid, used_bytes, raid_bytes_show);
 405
 406 static ssize_t raid_bytes_show(struct kobject *kobj,
 407                                struct kobj_attribute *attr, char *buf)
 408
 409 {
 410         struct btrfs_space_info *sinfo = to_space_info(kobj->parent);
 411         struct btrfs_block_group *block_group;
 412         int index = btrfs_bg_flags_to_raid_index(to_raid_kobj(kobj)->flags);
 413         u64 val = 0;
 414
 415         down_read(&sinfo->groups_sem);
 416         list_for_each_entry(block_group, &sinfo->block_groups[index], list) {
 417                 if (&attr->attr == BTRFS_ATTR_PTR(raid, total_bytes))
 418                         val += block_group->length;
 419                 else
 420                         val += block_group->used;
 421         }
 422         up_read(&sinfo->groups_sem);
 423         return snprintf(buf, PAGE_SIZE, "%llu\n", val);
 424 }
 425
 426 static struct attribute *raid_attrs[] = {
 427         BTRFS_ATTR_PTR(raid, total_bytes),
 428         BTRFS_ATTR_PTR(raid, used_bytes),
 429         NULL
 430 };
 431 ATTRIBUTE_GROUPS(raid);
 432
 433 static void release_raid_kobj(struct kobject *kobj)
 434 {
 435         kfree(to_raid_kobj(kobj));
 436 }
 437
 438 static struct kobj_type btrfs_raid_ktype = {
 439         .sysfs_ops = &kobj_sysfs_ops,
 440         .release = release_raid_kobj,
 441         .default_groups = raid_groups,
 442 };
 443
 444 #define SPACE_INFO_ATTR(field)                                          \
 445 static ssize_t btrfs_space_info_show_##field(struct kobject *kobj,      \
 446                                              struct kobj_attribute *a,  \
 447                                              char *buf)                 \
 448 {                                                                       \
 449         struct btrfs_space_info *sinfo = to_space_info(kobj);           \
 450         return btrfs_show_u64(&sinfo->field, &sinfo->lock, buf);        \
 451 }                                                                       \
 452 BTRFS_ATTR(space_info, field, btrfs_space_info_show_##field)
 453
 454 static ssize_t btrfs_space_info_show_total_bytes_pinned(struct kobject *kobj,
 455                                                        struct kobj_attribute *a,
 456                                                        char *buf)
 457 {
 458         struct btrfs_space_info *sinfo = to_space_info(kobj);
 459         s64 val = percpu_counter_sum(&sinfo->total_bytes_pinned);
 460         return snprintf(buf, PAGE_SIZE, "%lld\n", val);
 461 }
 462
 463 SPACE_INFO_ATTR(flags);
 464 SPACE_INFO_ATTR(total_bytes);
 465 SPACE_INFO_ATTR(bytes_used);
 466 SPACE_INFO_ATTR(bytes_pinned);
 467 SPACE_INFO_ATTR(bytes_reserved);
 468 SPACE_INFO_ATTR(bytes_may_use);
 469 SPACE_INFO_ATTR(bytes_readonly);
 470 SPACE_INFO_ATTR(disk_used);
 471 SPACE_INFO_ATTR(disk_total);
 472 BTRFS_ATTR(space_info, total_bytes_pinned,
 473            btrfs_space_info_show_total_bytes_pinned);
 474
 475 static struct attribute *space_info_attrs[] = {
 476         BTRFS_ATTR_PTR(space_info, flags),
 477         BTRFS_ATTR_PTR(space_info, total_bytes),
 478         BTRFS_ATTR_PTR(space_info, bytes_used),
 479         BTRFS_ATTR_PTR(space_info, bytes_pinned),
 480         BTRFS_ATTR_PTR(space_info, bytes_reserved),
 481         BTRFS_ATTR_PTR(space_info, bytes_may_use),
 482         BTRFS_ATTR_PTR(space_info, bytes_readonly),
 483         BTRFS_ATTR_PTR(space_info, disk_used),
 484         BTRFS_ATTR_PTR(space_info, disk_total),
 485         BTRFS_ATTR_PTR(space_info, total_bytes_pinned),
 486         NULL,
 487 };
 488 ATTRIBUTE_GROUPS(space_info);
 489
 490 static void space_info_release(struct kobject *kobj)
 491 {
 492         struct btrfs_space_info *sinfo = to_space_info(kobj);
 493         percpu_counter_destroy(&sinfo->total_bytes_pinned);
 494         kfree(sinfo);
 495 }
 496
 497 static struct kobj_type space_info_ktype = {
 498         .sysfs_ops = &kobj_sysfs_ops,
 499         .release = space_info_release,
 500         .default_groups = space_info_groups,
 501 };
 502
 503 static const struct attribute *allocation_attrs[] = {
 504         BTRFS_ATTR_PTR(allocation, global_rsv_reserved),
 505         BTRFS_ATTR_PTR(allocation, global_rsv_size),
 506         NULL,
 507 };
 508
 509 static ssize_t btrfs_label_show(struct kobject *kobj,
 510                                 struct kobj_attribute *a, char *buf)
 511 {
 512         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 513         char *label = fs_info->super_copy->label;
 514         ssize_t ret;
 515
 516         spin_lock(&fs_info->super_lock);
 517         ret = snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
 518         spin_unlock(&fs_info->super_lock);
 519
 520         return ret;
 521 }
 522
 523 static ssize_t btrfs_label_store(struct kobject *kobj,
 524                                  struct kobj_attribute *a,
 525                                  const char *buf, size_t len)
 526 {
 527         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 528         size_t p_len;
 529
 530         if (!fs_info)
 531                 return -EPERM;
 532
 533         if (sb_rdonly(fs_info->sb))
 534                 return -EROFS;
 535
 536         /*
 537          * p_len is the len until the first occurrence of either
 538          * '\n' or '\0'
 539          */
 540         p_len = strcspn(buf, "\n");
 541
 542         if (p_len >= BTRFS_LABEL_SIZE)
 543                 return -EINVAL;
 544
 545         spin_lock(&fs_info->super_lock);
 546         memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
 547         memcpy(fs_info->super_copy->label, buf, p_len);
 548         spin_unlock(&fs_info->super_lock);
 549
 550         /*
 551          * We don't want to do full transaction commit from inside sysfs
 552          */
 553         btrfs_set_pending(fs_info, COMMIT);
 554         wake_up_process(fs_info->transaction_kthread);
 555
 556         return len;
 557 }
 558 BTRFS_ATTR_RW(, label, btrfs_label_show, btrfs_label_store);
 559
 560 static ssize_t btrfs_nodesize_show(struct kobject *kobj,
 561                                 struct kobj_attribute *a, char *buf)
 562 {
 563         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 564
 565         return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);
 566 }
 567
 568 BTRFS_ATTR(, nodesize, btrfs_nodesize_show);
 569
 570 static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
 571                                 struct kobj_attribute *a, char *buf)
 572 {
 573         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 574
 575         return snprintf(buf, PAGE_SIZE, "%u\n",
 576                         fs_info->super_copy->sectorsize);
 577 }
 578
 579 BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
 580
 581 static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
 582                                 struct kobj_attribute *a, char *buf)
 583 {
 584         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 585
 586         return snprintf(buf, PAGE_SIZE, "%u\n",
 587                         fs_info->super_copy->sectorsize);
 588 }
 589
 590 BTRFS_ATTR(, clone_alignment, btrfs_clone_alignment_show);
 591
 592 static ssize_t quota_override_show(struct kobject *kobj,
 593                                    struct kobj_attribute *a, char *buf)
 594 {
 595         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 596         int quota_override;
 597
 598         quota_override = test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
 599         return snprintf(buf, PAGE_SIZE, "%d\n", quota_override);
 600 }
 601
 602 static ssize_t quota_override_store(struct kobject *kobj,
 603                                     struct kobj_attribute *a,
 604                                     const char *buf, size_t len)
 605 {
 606         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 607         unsigned long knob;
 608         int err;
 609
 610         if (!fs_info)
 611                 return -EPERM;
 612
 613         if (!capable(CAP_SYS_RESOURCE))
 614                 return -EPERM;
 615
 616         err = kstrtoul(buf, 10, &knob);
 617         if (err)
 618                 return err;
 619         if (knob > 1)
 620                 return -EINVAL;
 621
 622         if (knob)
 623                 set_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
 624         else
 625                 clear_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
 626
 627         return len;
 628 }
 629
 630 BTRFS_ATTR_RW(, quota_override, quota_override_show, quota_override_store);
 631
 632 static ssize_t btrfs_metadata_uuid_show(struct kobject *kobj,
 633                                 struct kobj_attribute *a, char *buf)
 634 {
 635         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 636
 637         return snprintf(buf, PAGE_SIZE, "%pU\n",
 638                         fs_info->fs_devices->metadata_uuid);
 639 }
 640
 641 BTRFS_ATTR(, metadata_uuid, btrfs_metadata_uuid_show);
 642
 643 static ssize_t btrfs_checksum_show(struct kobject *kobj,
 644                                    struct kobj_attribute *a, char *buf)
 645 {
 646         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 647         u16 csum_type = btrfs_super_csum_type(fs_info->super_copy);
 648
 649         return snprintf(buf, PAGE_SIZE, "%s (%s)\n",
 650                         btrfs_super_csum_name(csum_type),
 651                         crypto_shash_driver_name(fs_info->csum_shash));
 652 }
 653
 654 BTRFS_ATTR(, checksum, btrfs_checksum_show);
 655
 656 static const struct attribute *btrfs_attrs[] = {
 657         BTRFS_ATTR_PTR(, label),
 658         BTRFS_ATTR_PTR(, nodesize),
 659         BTRFS_ATTR_PTR(, sectorsize),
 660         BTRFS_ATTR_PTR(, clone_alignment),
 661         BTRFS_ATTR_PTR(, quota_override),
 662         BTRFS_ATTR_PTR(, metadata_uuid),
 663         BTRFS_ATTR_PTR(, checksum),
 664         NULL,
 665 };
 666
 667 static void btrfs_release_fsid_kobj(struct kobject *kobj)
 668 {
 669         struct btrfs_fs_devices *fs_devs = to_fs_devs(kobj);
 670
 671         memset(&fs_devs->fsid_kobj, 0, sizeof(struct kobject));
 672         complete(&fs_devs->kobj_unregister);
 673 }
 674
 675 static struct kobj_type btrfs_ktype = {
 676         .sysfs_ops      = &kobj_sysfs_ops,
 677         .release        = btrfs_release_fsid_kobj,
 678 };
 679
 680 static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj)
 681 {
 682         if (kobj->ktype != &btrfs_ktype)
 683                 return NULL;
 684         return container_of(kobj, struct btrfs_fs_devices, fsid_kobj);
 685 }
 686
 687 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
 688 {
 689         if (kobj->ktype != &btrfs_ktype)
 690                 return NULL;
 691         return to_fs_devs(kobj)->fs_info;
 692 }
 693
 694 #define NUM_FEATURE_BITS 64
 695 #define BTRFS_FEATURE_NAME_MAX 13
 696 static char btrfs_unknown_feature_names[FEAT_MAX][NUM_FEATURE_BITS][BTRFS_FEATURE_NAME_MAX];
 697 static struct btrfs_feature_attr btrfs_feature_attrs[FEAT_MAX][NUM_FEATURE_BITS];
 698
 699 static const u64 supported_feature_masks[FEAT_MAX] = {
 700         [FEAT_COMPAT]    = BTRFS_FEATURE_COMPAT_SUPP,
 701         [FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SUPP,
 702         [FEAT_INCOMPAT]  = BTRFS_FEATURE_INCOMPAT_SUPP,
 703 };
 704
 705 static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 706 {
 707         int set;
 708
 709         for (set = 0; set < FEAT_MAX; set++) {
 710                 int i;
 711                 struct attribute *attrs[2];
 712                 struct attribute_group agroup = {
 713                         .name = "features",
 714                         .attrs = attrs,
 715                 };
 716                 u64 features = get_features(fs_info, set);
 717                 features &= ~supported_feature_masks[set];
 718
 719                 if (!features)
 720                         continue;
 721
 722                 attrs[1] = NULL;
 723                 for (i = 0; i < NUM_FEATURE_BITS; i++) {
 724                         struct btrfs_feature_attr *fa;
 725
 726                         if (!(features & (1ULL << i)))
 727                                 continue;
 728
 729                         fa = &btrfs_feature_attrs[set][i];
 730                         attrs[0] = &fa->kobj_attr.attr;
 731                         if (add) {
 732                                 int ret;
 733                                 ret = sysfs_merge_group(&fs_info->fs_devices->fsid_kobj,
 734                                                         &agroup);
 735                                 if (ret)
 736                                         return ret;
 737                         } else
 738                                 sysfs_unmerge_group(&fs_info->fs_devices->fsid_kobj,
 739                                                     &agroup);
 740                 }
 741
 742         }
 743         return 0;
 744 }
 745
 746 static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 747 {
 748         if (fs_devs->devices_kobj) {
 749                 kobject_del(fs_devs->devices_kobj);
 750                 kobject_put(fs_devs->devices_kobj);
 751                 fs_devs->devices_kobj = NULL;
 752         }
 753
 754         if (fs_devs->fsid_kobj.state_initialized) {
 755                 kobject_del(&fs_devs->fsid_kobj);
 756                 kobject_put(&fs_devs->fsid_kobj);
 757                 wait_for_completion(&fs_devs->kobj_unregister);
 758         }
 759 }
 760
 761 /* when fs_devs is NULL it will remove all fsid kobject */
 762 void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 763 {
 764         struct list_head *fs_uuids = btrfs_get_fs_uuids();
 765
 766         if (fs_devs) {
 767                 __btrfs_sysfs_remove_fsid(fs_devs);
 768                 return;
 769         }
 770
 771         list_for_each_entry(fs_devs, fs_uuids, fs_list) {
 772                 __btrfs_sysfs_remove_fsid(fs_devs);
 773         }
 774 }
 775
 776 void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info)
 777 {
 778         btrfs_reset_fs_info_ptr(fs_info);
 779
 780         if (fs_info->space_info_kobj) {
 781                 sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
 782                 kobject_del(fs_info->space_info_kobj);
 783                 kobject_put(fs_info->space_info_kobj);
 784         }
 785 #ifdef CONFIG_BTRFS_DEBUG
 786         if (fs_info->discard_debug_kobj) {
 787                 sysfs_remove_files(fs_info->discard_debug_kobj,
 788                                    discard_debug_attrs);
 789                 kobject_del(fs_info->discard_debug_kobj);
 790                 kobject_put(fs_info->discard_debug_kobj);
 791         }
 792         if (fs_info->debug_kobj) {
 793                 sysfs_remove_files(fs_info->debug_kobj, btrfs_debug_mount_attrs);
 794                 kobject_del(fs_info->debug_kobj);
 795                 kobject_put(fs_info->debug_kobj);
 796         }
 797 #endif
 798         addrm_unknown_feature_attrs(fs_info, false);
 799         sysfs_remove_group(&fs_info->fs_devices->fsid_kobj, &btrfs_feature_attr_group);
 800         sysfs_remove_files(&fs_info->fs_devices->fsid_kobj, btrfs_attrs);
 801         btrfs_sysfs_rm_device_link(fs_info->fs_devices, NULL);
 802 }
 803
 804 static const char * const btrfs_feature_set_names[FEAT_MAX] = {
 805         [FEAT_COMPAT]    = "compat",
 806         [FEAT_COMPAT_RO] = "compat_ro",
 807         [FEAT_INCOMPAT]  = "incompat",
 808 };
 809
 810 const char * const btrfs_feature_set_name(enum btrfs_feature_set set)
 811 {
 812         return btrfs_feature_set_names[set];
 813 }
 814
 815 char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
 816 {
 817         size_t bufsize = 4096; /* safe max, 64 names * 64 bytes */
 818         int len = 0;
 819         int i;
 820         char *str;
 821
 822         str = kmalloc(bufsize, GFP_KERNEL);
 823         if (!str)
 824                 return str;
 825
 826         for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
 827                 const char *name;
 828
 829                 if (!(flags & (1ULL << i)))
 830                         continue;
 831
 832                 name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
 833                 len += snprintf(str + len, bufsize - len, "%s%s",
 834                                 len ? "," : "", name);
 835         }
 836
 837         return str;
 838 }
 839
 840 static void init_feature_attrs(void)
 841 {
 842         struct btrfs_feature_attr *fa;
 843         int set, i;
 844
 845         BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names) !=
 846                      ARRAY_SIZE(btrfs_feature_attrs));
 847         BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names[0]) !=
 848                      ARRAY_SIZE(btrfs_feature_attrs[0]));
 849
 850         memset(btrfs_feature_attrs, 0, sizeof(btrfs_feature_attrs));
 851         memset(btrfs_unknown_feature_names, 0,
 852                sizeof(btrfs_unknown_feature_names));
 853
 854         for (i = 0; btrfs_supported_feature_attrs[i]; i++) {
 855                 struct btrfs_feature_attr *sfa;
 856                 struct attribute *a = btrfs_supported_feature_attrs[i];
 857                 int bit;
 858                 sfa = attr_to_btrfs_feature_attr(a);
 859                 bit = ilog2(sfa->feature_bit);
 860                 fa = &btrfs_feature_attrs[sfa->feature_set][bit];
 861
 862                 fa->kobj_attr.attr.name = sfa->kobj_attr.attr.name;
 863         }
 864
 865         for (set = 0; set < FEAT_MAX; set++) {
 866                 for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
 867                         char *name = btrfs_unknown_feature_names[set][i];
 868                         fa = &btrfs_feature_attrs[set][i];
 869
 870                         if (fa->kobj_attr.attr.name)
 871                                 continue;
 872
 873                         snprintf(name, BTRFS_FEATURE_NAME_MAX, "%s:%u",
 874                                  btrfs_feature_set_names[set], i);
 875
 876                         fa->kobj_attr.attr.name = name;
 877                         fa->kobj_attr.attr.mode = S_IRUGO;
 878                         fa->feature_set = set;
 879                         fa->feature_bit = 1ULL << i;
 880                 }
 881         }
 882 }
 883
 884 /*
 885  * Create a sysfs entry for a given block group type at path
 886  * /sys/fs/btrfs/UUID/allocation/data/TYPE
 887  */
 888 void btrfs_sysfs_add_block_group_type(struct btrfs_block_group *cache)
 889 {
 890         struct btrfs_fs_info *fs_info = cache->fs_info;
 891         struct btrfs_space_info *space_info = cache->space_info;
 892         struct raid_kobject *rkobj;
 893         const int index = btrfs_bg_flags_to_raid_index(cache->flags);
 894         unsigned int nofs_flag;
 895         int ret;
 896
 897         /*
 898          * Setup a NOFS context because kobject_add(), deep in its call chain,
 899          * does GFP_KERNEL allocations, and we are often called in a context
 900          * where if reclaim is triggered we can deadlock (we are either holding
 901          * a transaction handle or some lock required for a transaction
 902          * commit).
 903          */
 904         nofs_flag = memalloc_nofs_save();
 905
 906         rkobj = kzalloc(sizeof(*rkobj), GFP_NOFS);
 907         if (!rkobj) {
 908                 memalloc_nofs_restore(nofs_flag);
 909                 btrfs_warn(cache->fs_info,
 910                                 "couldn't alloc memory for raid level kobject");
 911                 return;
 912         }
 913
 914         rkobj->flags = cache->flags;
 915         kobject_init(&rkobj->kobj, &btrfs_raid_ktype);
 916         ret = kobject_add(&rkobj->kobj, &space_info->kobj, "%s",
 917                           btrfs_bg_type_to_raid_name(rkobj->flags));
 918         memalloc_nofs_restore(nofs_flag);
 919         if (ret) {
 920                 kobject_put(&rkobj->kobj);
 921                 btrfs_warn(fs_info,
 922                         "failed to add kobject for block cache, ignoring");
 923                 return;
 924         }
 925
 926         space_info->block_group_kobjs[index] = &rkobj->kobj;
 927 }
 928
 929 /*
 930  * Remove sysfs directories for all block group types of a given space info and
 931  * the space info as well
 932  */
 933 void btrfs_sysfs_remove_space_info(struct btrfs_space_info *space_info)
 934 {
 935         int i;
 936
 937         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
 938                 struct kobject *kobj;
 939
 940                 kobj = space_info->block_group_kobjs[i];
 941                 space_info->block_group_kobjs[i] = NULL;
 942                 if (kobj) {
 943                         kobject_del(kobj);
 944                         kobject_put(kobj);
 945                 }
 946         }
 947         kobject_del(&space_info->kobj);
 948         kobject_put(&space_info->kobj);
 949 }
 950
 951 static const char *alloc_name(u64 flags)
 952 {
 953         switch (flags) {
 954         case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
 955                 return "mixed";
 956         case BTRFS_BLOCK_GROUP_METADATA:
 957                 return "metadata";
 958         case BTRFS_BLOCK_GROUP_DATA:
 959                 return "data";
 960         case BTRFS_BLOCK_GROUP_SYSTEM:
 961                 return "system";
 962         default:
 963                 WARN_ON(1);
 964                 return "invalid-combination";
 965         };
 966 }
 967
 968 /*
 969  * Create a sysfs entry for a space info type at path
 970  * /sys/fs/btrfs/UUID/allocation/TYPE
 971  */
 972 int btrfs_sysfs_add_space_info_type(struct btrfs_fs_info *fs_info,
 973                                     struct btrfs_space_info *space_info)
 974 {
 975         int ret;
 976
 977         ret = kobject_init_and_add(&space_info->kobj, &space_info_ktype,
 978                                    fs_info->space_info_kobj, "%s",
 979                                    alloc_name(space_info->flags));
 980         if (ret) {
 981                 kobject_put(&space_info->kobj);
 982                 return ret;
 983         }
 984
 985         return 0;
 986 }
 987
 988 /* when one_device is NULL, it removes all device links */
 989
 990 int btrfs_sysfs_rm_device_link(struct btrfs_fs_devices *fs_devices,
 991                 struct btrfs_device *one_device)
 992 {
 993         struct hd_struct *disk;
 994         struct kobject *disk_kobj;
 995
 996         if (!fs_devices->devices_kobj)
 997                 return -EINVAL;
 998
 999         if (one_device && one_device->bdev) {
1000                 disk = one_device->bdev->bd_part;
1001                 disk_kobj = &part_to_dev(disk)->kobj;
1002
1003                 sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
1004         }
1005
1006         if (one_device)
1007                 return 0;
1008
1009         list_for_each_entry(one_device,
1010                         &fs_devices->devices, dev_list) {
1011                 if (!one_device->bdev)
1012                         continue;
1013                 disk = one_device->bdev->bd_part;
1014                 disk_kobj = &part_to_dev(disk)->kobj;
1015
1016                 sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
1017         }
1018
1019         return 0;
1020 }
1021
1022 int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,
1023                                 struct btrfs_device *one_device)
1024 {
1025         int error = 0;
1026         struct btrfs_device *dev;
1027
1028         list_for_each_entry(dev, &fs_devices->devices, dev_list) {
1029                 struct hd_struct *disk;
1030                 struct kobject *disk_kobj;
1031
1032                 if (!dev->bdev)
1033                         continue;
1034
1035                 if (one_device && one_device != dev)
1036                         continue;
1037
1038                 disk = dev->bdev->bd_part;
1039                 disk_kobj = &part_to_dev(disk)->kobj;
1040
1041                 error = sysfs_create_link(fs_devices->devices_kobj,
1042                                           disk_kobj, disk_kobj->name);
1043                 if (error)
1044                         break;
1045         }
1046
1047         return error;
1048 }
1049
1050 void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action)
1051 {
1052         int ret;
1053
1054         ret = kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, action);
1055         if (ret)
1056                 pr_warn("BTRFS: Sending event '%d' to kobject: '%s' (%p): failed\n",
1057                         action, kobject_name(&disk_to_dev(bdev->bd_disk)->kobj),
1058                         &disk_to_dev(bdev->bd_disk)->kobj);
1059 }
1060
1061 void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices,
1062                                     const u8 *fsid)
1063 {
1064         char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
1065
1066         /*
1067          * Sprouting changes fsid of the mounted filesystem, rename the fsid
1068          * directory
1069          */
1070         snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU", fsid);
1071         if (kobject_rename(&fs_devices->fsid_kobj, fsid_buf))
1072                 btrfs_warn(fs_devices->fs_info,
1073                                 "sysfs: failed to create fsid for sprout");
1074 }
1075
1076 /* /sys/fs/btrfs/ entry */
1077 static struct kset *btrfs_kset;
1078
1079 /*
1080  * Creates:
1081  *              /sys/fs/btrfs/UUID
1082  *
1083  * Can be called by the device discovery thread.
1084  */
1085 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs)
1086 {
1087         int error;
1088
1089         init_completion(&fs_devs->kobj_unregister);
1090         fs_devs->fsid_kobj.kset = btrfs_kset;
1091         error = kobject_init_and_add(&fs_devs->fsid_kobj, &btrfs_ktype, NULL,
1092                                      "%pU", fs_devs->fsid);
1093         if (error) {
1094                 kobject_put(&fs_devs->fsid_kobj);
1095                 return error;
1096         }
1097
1098         fs_devs->devices_kobj = kobject_create_and_add("devices",
1099                                                        &fs_devs->fsid_kobj);
1100         if (!fs_devs->devices_kobj) {
1101                 btrfs_err(fs_devs->fs_info,
1102                           "failed to init sysfs device interface");
1103                 kobject_put(&fs_devs->fsid_kobj);
1104                 return -ENOMEM;
1105         }
1106
1107         return 0;
1108 }
1109
1110 int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
1111 {
1112         int error;
1113         struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
1114         struct kobject *fsid_kobj = &fs_devs->fsid_kobj;
1115
1116         btrfs_set_fs_info_ptr(fs_info);
1117
1118         error = btrfs_sysfs_add_device_link(fs_devs, NULL);
1119         if (error)
1120                 return error;
1121
1122         error = sysfs_create_files(fsid_kobj, btrfs_attrs);
1123         if (error) {
1124                 btrfs_sysfs_rm_device_link(fs_devs, NULL);
1125                 return error;
1126         }
1127
1128         error = sysfs_create_group(fsid_kobj,
1129                                    &btrfs_feature_attr_group);
1130         if (error)
1131                 goto failure;
1132
1133 #ifdef CONFIG_BTRFS_DEBUG
1134         fs_info->debug_kobj = kobject_create_and_add("debug", fsid_kobj);
1135         if (!fs_info->debug_kobj) {
1136                 error = -ENOMEM;
1137                 goto failure;
1138         }
1139
1140         error = sysfs_create_files(fs_info->debug_kobj, btrfs_debug_mount_attrs);
1141         if (error)
1142                 goto failure;
1143
1144         /* Discard directory */
1145         fs_info->discard_debug_kobj = kobject_create_and_add("discard",
1146                                                      fs_info->debug_kobj);
1147         if (!fs_info->discard_debug_kobj) {
1148                 error = -ENOMEM;
1149                 goto failure;
1150         }
1151
1152         error = sysfs_create_files(fs_info->discard_debug_kobj,
1153                                    discard_debug_attrs);
1154         if (error)
1155                 goto failure;
1156 #endif
1157
1158         error = addrm_unknown_feature_attrs(fs_info, true);
1159         if (error)
1160                 goto failure;
1161
1162         fs_info->space_info_kobj = kobject_create_and_add("allocation",
1163                                                   fsid_kobj);
1164         if (!fs_info->space_info_kobj) {
1165                 error = -ENOMEM;
1166                 goto failure;
1167         }
1168
1169         error = sysfs_create_files(fs_info->space_info_kobj, allocation_attrs);
1170         if (error)
1171                 goto failure;
1172
1173         return 0;
1174 failure:
1175         btrfs_sysfs_remove_mounted(fs_info);
1176         return error;
1177 }
1178
1179
1180 /*
1181  * Change per-fs features in /sys/fs/btrfs/UUID/features to match current
1182  * values in superblock. Call after any changes to incompat/compat_ro flags
1183  */
1184 void btrfs_sysfs_feature_update(struct btrfs_fs_info *fs_info,
1185                 u64 bit, enum btrfs_feature_set set)
1186 {
1187         struct btrfs_fs_devices *fs_devs;
1188         struct kobject *fsid_kobj;
1189         u64 features;
1190         int ret;
1191
1192         if (!fs_info)
1193                 return;
1194
1195         features = get_features(fs_info, set);
1196         ASSERT(bit & supported_feature_masks[set]);
1197
1198         fs_devs = fs_info->fs_devices;
1199         fsid_kobj = &fs_devs->fsid_kobj;
1200
1201         if (!fsid_kobj->state_initialized)
1202                 return;
1203
1204         /*
1205          * FIXME: this is too heavy to update just one value, ideally we'd like
1206          * to use sysfs_update_group but some refactoring is needed first.
1207          */
1208         sysfs_remove_group(fsid_kobj, &btrfs_feature_attr_group);
1209         ret = sysfs_create_group(fsid_kobj, &btrfs_feature_attr_group);
1210 }
1211
1212 int __init btrfs_init_sysfs(void)
1213 {
1214         int ret;
1215
1216         btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
1217         if (!btrfs_kset)
1218                 return -ENOMEM;
1219
1220         init_feature_attrs();
1221         ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
1222         if (ret)
1223                 goto out2;
1224         ret = sysfs_merge_group(&btrfs_kset->kobj,
1225                                 &btrfs_static_feature_attr_group);
1226         if (ret)
1227                 goto out_remove_group;
1228
1229 #ifdef CONFIG_BTRFS_DEBUG
1230         ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_debug_feature_attr_group);
1231         if (ret)
1232                 goto out2;
1233 #endif
1234
1235         return 0;
1236
1237 out_remove_group:
1238         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
1239 out2:
1240         kset_unregister(btrfs_kset);
1241
1242         return ret;
1243 }
1244
1245 void __cold btrfs_exit_sysfs(void)
1246 {
1247         sysfs_unmerge_group(&btrfs_kset->kobj,
1248                             &btrfs_static_feature_attr_group);
1249         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
1250 #ifdef CONFIG_BTRFS_DEBUG
1251         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_debug_feature_attr_group);
1252 #endif
1253         kset_unregister(btrfs_kset);
1254 }
1255