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 "discard.h"
  16 #include "disk-io.h"
  17 #include "transaction.h"
  18 #include "sysfs.h"
  19 #include "volumes.h"
  20 #include "space-info.h"
  21 #include "block-group.h"
  22
  23 struct btrfs_feature_attr {
  24         struct kobj_attribute kobj_attr;
  25         enum btrfs_feature_set feature_set;
  26         u64 feature_bit;
  27 };
  28
  29 /* For raid type sysfs entries */
  30 struct raid_kobject {
  31         u64 flags;
  32         struct kobject kobj;
  33 };
  34
  35 #define __INIT_KOBJ_ATTR(_name, _mode, _show, _store)                   \
  36 {                                                                       \
  37         .attr   = { .name = __stringify(_name), .mode = _mode },        \
  38         .show   = _show,                                                \
  39         .store  = _store,                                               \
  40 }
  41
  42 #define BTRFS_ATTR_RW(_prefix, _name, _show, _store)                    \
  43         static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
  44                         __INIT_KOBJ_ATTR(_name, 0644, _show, _store)
  45
  46 #define BTRFS_ATTR(_prefix, _name, _show)                               \
  47         static struct kobj_attribute btrfs_attr_##_prefix##_##_name =   \
  48                         __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
  49
  50 #define BTRFS_ATTR_PTR(_prefix, _name)                                  \
  51         (&btrfs_attr_##_prefix##_##_name.attr)
  52
  53 #define BTRFS_FEAT_ATTR(_name, _feature_set, _feature_prefix, _feature_bit)  \
  54 static struct btrfs_feature_attr btrfs_attr_features_##_name = {             \
  55         .kobj_attr = __INIT_KOBJ_ATTR(_name, S_IRUGO,                        \
  56                                       btrfs_feature_attr_show,               \
  57                                       btrfs_feature_attr_store),             \
  58         .feature_set    = _feature_set,                                      \
  59         .feature_bit    = _feature_prefix ##_## _feature_bit,                \
  60 }
  61 #define BTRFS_FEAT_ATTR_PTR(_name)                                           \
  62         (&btrfs_attr_features_##_name.kobj_attr.attr)
  63
  64 #define BTRFS_FEAT_ATTR_COMPAT(name, feature) \
  65         BTRFS_FEAT_ATTR(name, FEAT_COMPAT, BTRFS_FEATURE_COMPAT, feature)
  66 #define BTRFS_FEAT_ATTR_COMPAT_RO(name, feature) \
  67         BTRFS_FEAT_ATTR(name, FEAT_COMPAT_RO, BTRFS_FEATURE_COMPAT_RO, feature)
  68 #define BTRFS_FEAT_ATTR_INCOMPAT(name, feature) \
  69         BTRFS_FEAT_ATTR(name, FEAT_INCOMPAT, BTRFS_FEATURE_INCOMPAT, feature)
  70
  71 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj);
  72 static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj);
  73
  74 static struct btrfs_feature_attr *to_btrfs_feature_attr(struct kobj_attribute *a)
  75 {
  76         return container_of(a, struct btrfs_feature_attr, kobj_attr);
  77 }
  78
  79 static struct kobj_attribute *attr_to_btrfs_attr(struct attribute *attr)
  80 {
  81         return container_of(attr, struct kobj_attribute, attr);
  82 }
  83
  84 static struct btrfs_feature_attr *attr_to_btrfs_feature_attr(
  85                 struct attribute *attr)
  86 {
  87         return to_btrfs_feature_attr(attr_to_btrfs_attr(attr));
  88 }
  89
  90 static u64 get_features(struct btrfs_fs_info *fs_info,
  91                         enum btrfs_feature_set set)
  92 {
  93         struct btrfs_super_block *disk_super = fs_info->super_copy;
  94         if (set == FEAT_COMPAT)
  95                 return btrfs_super_compat_flags(disk_super);
  96         else if (set == FEAT_COMPAT_RO)
  97                 return btrfs_super_compat_ro_flags(disk_super);
  98         else
  99                 return btrfs_super_incompat_flags(disk_super);
 100 }
 101
 102 static void set_features(struct btrfs_fs_info *fs_info,
 103                          enum btrfs_feature_set set, u64 features)
 104 {
 105         struct btrfs_super_block *disk_super = fs_info->super_copy;
 106         if (set == FEAT_COMPAT)
 107                 btrfs_set_super_compat_flags(disk_super, features);
 108         else if (set == FEAT_COMPAT_RO)
 109                 btrfs_set_super_compat_ro_flags(disk_super, features);
 110         else
 111                 btrfs_set_super_incompat_flags(disk_super, features);
 112 }
 113
 114 static int can_modify_feature(struct btrfs_feature_attr *fa)
 115 {
 116         int val = 0;
 117         u64 set, clear;
 118         switch (fa->feature_set) {
 119         case FEAT_COMPAT:
 120                 set = BTRFS_FEATURE_COMPAT_SAFE_SET;
 121                 clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
 122                 break;
 123         case FEAT_COMPAT_RO:
 124                 set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
 125                 clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
 126                 break;
 127         case FEAT_INCOMPAT:
 128                 set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
 129                 clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
 130                 break;
 131         default:
 132                 pr_warn("btrfs: sysfs: unknown feature set %d\n",
 133                                 fa->feature_set);
 134                 return 0;
 135         }
 136
 137         if (set & fa->feature_bit)
 138                 val |= 1;
 139         if (clear & fa->feature_bit)
 140                 val |= 2;
 141
 142         return val;
 143 }
 144
 145 static ssize_t btrfs_feature_attr_show(struct kobject *kobj,
 146                                        struct kobj_attribute *a, char *buf)
 147 {
 148         int val = 0;
 149         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 150         struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
 151         if (fs_info) {
 152                 u64 features = get_features(fs_info, fa->feature_set);
 153                 if (features & fa->feature_bit)
 154                         val = 1;
 155         } else
 156                 val = can_modify_feature(fa);
 157
 158         return snprintf(buf, PAGE_SIZE, "%d\n", val);
 159 }
 160
 161 static ssize_t btrfs_feature_attr_store(struct kobject *kobj,
 162                                         struct kobj_attribute *a,
 163                                         const char *buf, size_t count)
 164 {
 165         struct btrfs_fs_info *fs_info;
 166         struct btrfs_feature_attr *fa = to_btrfs_feature_attr(a);
 167         u64 features, set, clear;
 168         unsigned long val;
 169         int ret;
 170
 171         fs_info = to_fs_info(kobj);
 172         if (!fs_info)
 173                 return -EPERM;
 174
 175         if (sb_rdonly(fs_info->sb))
 176                 return -EROFS;
 177
 178         ret = kstrtoul(skip_spaces(buf), 0, &val);
 179         if (ret)
 180                 return ret;
 181
 182         if (fa->feature_set == FEAT_COMPAT) {
 183                 set = BTRFS_FEATURE_COMPAT_SAFE_SET;
 184                 clear = BTRFS_FEATURE_COMPAT_SAFE_CLEAR;
 185         } else if (fa->feature_set == FEAT_COMPAT_RO) {
 186                 set = BTRFS_FEATURE_COMPAT_RO_SAFE_SET;
 187                 clear = BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR;
 188         } else {
 189                 set = BTRFS_FEATURE_INCOMPAT_SAFE_SET;
 190                 clear = BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR;
 191         }
 192
 193         features = get_features(fs_info, fa->feature_set);
 194
 195         /* Nothing to do */
 196         if ((val && (features & fa->feature_bit)) ||
 197             (!val && !(features & fa->feature_bit)))
 198                 return count;
 199
 200         if ((val && !(set & fa->feature_bit)) ||
 201             (!val && !(clear & fa->feature_bit))) {
 202                 btrfs_info(fs_info,
 203                         "%sabling feature %s on mounted fs is not supported.",
 204                         val ? "En" : "Dis", fa->kobj_attr.attr.name);
 205                 return -EPERM;
 206         }
 207
 208         btrfs_info(fs_info, "%s %s feature flag",
 209                    val ? "Setting" : "Clearing", fa->kobj_attr.attr.name);
 210
 211         spin_lock(&fs_info->super_lock);
 212         features = get_features(fs_info, fa->feature_set);
 213         if (val)
 214                 features |= fa->feature_bit;
 215         else
 216                 features &= ~fa->feature_bit;
 217         set_features(fs_info, fa->feature_set, features);
 218         spin_unlock(&fs_info->super_lock);
 219
 220         /*
 221          * We don't want to do full transaction commit from inside sysfs
 222          */
 223         btrfs_set_pending(fs_info, COMMIT);
 224         wake_up_process(fs_info->transaction_kthread);
 225
 226         return count;
 227 }
 228
 229 static umode_t btrfs_feature_visible(struct kobject *kobj,
 230                                      struct attribute *attr, int unused)
 231 {
 232         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 233         umode_t mode = attr->mode;
 234
 235         if (fs_info) {
 236                 struct btrfs_feature_attr *fa;
 237                 u64 features;
 238
 239                 fa = attr_to_btrfs_feature_attr(attr);
 240                 features = get_features(fs_info, fa->feature_set);
 241
 242                 if (can_modify_feature(fa))
 243                         mode |= S_IWUSR;
 244                 else if (!(features & fa->feature_bit))
 245                         mode = 0;
 246         }
 247
 248         return mode;
 249 }
 250
 251 BTRFS_FEAT_ATTR_INCOMPAT(mixed_backref, MIXED_BACKREF);
 252 BTRFS_FEAT_ATTR_INCOMPAT(default_subvol, DEFAULT_SUBVOL);
 253 BTRFS_FEAT_ATTR_INCOMPAT(mixed_groups, MIXED_GROUPS);
 254 BTRFS_FEAT_ATTR_INCOMPAT(compress_lzo, COMPRESS_LZO);
 255 BTRFS_FEAT_ATTR_INCOMPAT(compress_zstd, COMPRESS_ZSTD);
 256 BTRFS_FEAT_ATTR_INCOMPAT(big_metadata, BIG_METADATA);
 257 BTRFS_FEAT_ATTR_INCOMPAT(extended_iref, EXTENDED_IREF);
 258 BTRFS_FEAT_ATTR_INCOMPAT(raid56, RAID56);
 259 BTRFS_FEAT_ATTR_INCOMPAT(skinny_metadata, SKINNY_METADATA);
 260 BTRFS_FEAT_ATTR_INCOMPAT(no_holes, NO_HOLES);
 261 BTRFS_FEAT_ATTR_INCOMPAT(metadata_uuid, METADATA_UUID);
 262 BTRFS_FEAT_ATTR_COMPAT_RO(free_space_tree, FREE_SPACE_TREE);
 263 BTRFS_FEAT_ATTR_INCOMPAT(raid1c34, RAID1C34);
 264
 265 static struct attribute *btrfs_supported_feature_attrs[] = {
 266         BTRFS_FEAT_ATTR_PTR(mixed_backref),
 267         BTRFS_FEAT_ATTR_PTR(default_subvol),
 268         BTRFS_FEAT_ATTR_PTR(mixed_groups),
 269         BTRFS_FEAT_ATTR_PTR(compress_lzo),
 270         BTRFS_FEAT_ATTR_PTR(compress_zstd),
 271         BTRFS_FEAT_ATTR_PTR(big_metadata),
 272         BTRFS_FEAT_ATTR_PTR(extended_iref),
 273         BTRFS_FEAT_ATTR_PTR(raid56),
 274         BTRFS_FEAT_ATTR_PTR(skinny_metadata),
 275         BTRFS_FEAT_ATTR_PTR(no_holes),
 276         BTRFS_FEAT_ATTR_PTR(metadata_uuid),
 277         BTRFS_FEAT_ATTR_PTR(free_space_tree),
 278         BTRFS_FEAT_ATTR_PTR(raid1c34),
 279         NULL
 280 };
 281
 282 /*
 283  * Features which depend on feature bits and may differ between each fs.
 284  *
 285  * /sys/fs/btrfs/features lists all available features of this kernel while
 286  * /sys/fs/btrfs/UUID/features shows features of the fs which are enabled or
 287  * can be changed online.
 288  */
 289 static const struct attribute_group btrfs_feature_attr_group = {
 290         .name = "features",
 291         .is_visible = btrfs_feature_visible,
 292         .attrs = btrfs_supported_feature_attrs,
 293 };
 294
 295 static ssize_t rmdir_subvol_show(struct kobject *kobj,
 296                                  struct kobj_attribute *ka, char *buf)
 297 {
 298         return snprintf(buf, PAGE_SIZE, "0\n");
 299 }
 300 BTRFS_ATTR(static_feature, rmdir_subvol, rmdir_subvol_show);
 301
 302 static ssize_t supported_checksums_show(struct kobject *kobj,
 303                                         struct kobj_attribute *a, char *buf)
 304 {
 305         ssize_t ret = 0;
 306         int i;
 307
 308         for (i = 0; i < btrfs_get_num_csums(); i++) {
 309                 /*
 310                  * This "trick" only works as long as 'enum btrfs_csum_type' has
 311                  * no holes in it
 312                  */
 313                 ret += snprintf(buf + ret, PAGE_SIZE - ret, "%s%s",
 314                                 (i == 0 ? "" : " "), btrfs_super_csum_name(i));
 315
 316         }
 317
 318         ret += snprintf(buf + ret, PAGE_SIZE - ret, "\n");
 319         return ret;
 320 }
 321 BTRFS_ATTR(static_feature, supported_checksums, supported_checksums_show);
 322
 323 static struct attribute *btrfs_supported_static_feature_attrs[] = {
 324         BTRFS_ATTR_PTR(static_feature, rmdir_subvol),
 325         BTRFS_ATTR_PTR(static_feature, supported_checksums),
 326         NULL
 327 };
 328
 329 /*
 330  * Features which only depend on kernel version.
 331  *
 332  * These are listed in /sys/fs/btrfs/features along with
 333  * btrfs_feature_attr_group
 334  */
 335 static const struct attribute_group btrfs_static_feature_attr_group = {
 336         .name = "features",
 337         .attrs = btrfs_supported_static_feature_attrs,
 338 };
 339
 340 #ifdef CONFIG_BTRFS_DEBUG
 341
 342 /*
 343  * Discard statistics and tunables
 344  */
 345 #define discard_to_fs_info(_kobj)       to_fs_info((_kobj)->parent->parent)
 346
 347 static ssize_t btrfs_discardable_bytes_show(struct kobject *kobj,
 348                                             struct kobj_attribute *a,
 349                                             char *buf)
 350 {
 351         struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
 352
 353         return snprintf(buf, PAGE_SIZE, "%lld\n",
 354                         atomic64_read(&fs_info->discard_ctl.discardable_bytes));
 355 }
 356 BTRFS_ATTR(discard, discardable_bytes, btrfs_discardable_bytes_show);
 357
 358 static ssize_t btrfs_discardable_extents_show(struct kobject *kobj,
 359                                               struct kobj_attribute *a,
 360                                               char *buf)
 361 {
 362         struct btrfs_fs_info *fs_info = discard_to_fs_info(kobj);
 363
 364         return snprintf(buf, PAGE_SIZE, "%d\n",
 365                         atomic_read(&fs_info->discard_ctl.discardable_extents));
 366 }
 367 BTRFS_ATTR(discard, discardable_extents, btrfs_discardable_extents_show);
 368
 369 static const struct attribute *discard_debug_attrs[] = {
 370         BTRFS_ATTR_PTR(discard, discardable_bytes),
 371         BTRFS_ATTR_PTR(discard, discardable_extents),
 372         NULL,
 373 };
 374
 375 /*
 376  * Runtime debugging exported via sysfs
 377  *
 378  * /sys/fs/btrfs/debug - applies to module or all filesystems
 379  * /sys/fs/btrfs/UUID  - applies only to the given filesystem
 380  */
 381 static const struct attribute *btrfs_debug_mount_attrs[] = {
 382         NULL,
 383 };
 384
 385 static struct attribute *btrfs_debug_feature_attrs[] = {
 386         NULL
 387 };
 388
 389 static const struct attribute_group btrfs_debug_feature_attr_group = {
 390         .name = "debug",
 391         .attrs = btrfs_debug_feature_attrs,
 392 };
 393
 394 #endif
 395
 396 static ssize_t btrfs_show_u64(u64 *value_ptr, spinlock_t *lock, char *buf)
 397 {
 398         u64 val;
 399         if (lock)
 400                 spin_lock(lock);
 401         val = *value_ptr;
 402         if (lock)
 403                 spin_unlock(lock);
 404         return snprintf(buf, PAGE_SIZE, "%llu\n", val);
 405 }
 406
 407 static ssize_t global_rsv_size_show(struct kobject *kobj,
 408                                     struct kobj_attribute *ka, char *buf)
 409 {
 410         struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
 411         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
 412         return btrfs_show_u64(&block_rsv->size, &block_rsv->lock, buf);
 413 }
 414 BTRFS_ATTR(allocation, global_rsv_size, global_rsv_size_show);
 415
 416 static ssize_t global_rsv_reserved_show(struct kobject *kobj,
 417                                         struct kobj_attribute *a, char *buf)
 418 {
 419         struct btrfs_fs_info *fs_info = to_fs_info(kobj->parent);
 420         struct btrfs_block_rsv *block_rsv = &fs_info->global_block_rsv;
 421         return btrfs_show_u64(&block_rsv->reserved, &block_rsv->lock, buf);
 422 }
 423 BTRFS_ATTR(allocation, global_rsv_reserved, global_rsv_reserved_show);
 424
 425 #define to_space_info(_kobj) container_of(_kobj, struct btrfs_space_info, kobj)
 426 #define to_raid_kobj(_kobj) container_of(_kobj, struct raid_kobject, kobj)
 427
 428 static ssize_t raid_bytes_show(struct kobject *kobj,
 429                                struct kobj_attribute *attr, char *buf);
 430 BTRFS_ATTR(raid, total_bytes, raid_bytes_show);
 431 BTRFS_ATTR(raid, used_bytes, raid_bytes_show);
 432
 433 static ssize_t raid_bytes_show(struct kobject *kobj,
 434                                struct kobj_attribute *attr, char *buf)
 435
 436 {
 437         struct btrfs_space_info *sinfo = to_space_info(kobj->parent);
 438         struct btrfs_block_group *block_group;
 439         int index = btrfs_bg_flags_to_raid_index(to_raid_kobj(kobj)->flags);
 440         u64 val = 0;
 441
 442         down_read(&sinfo->groups_sem);
 443         list_for_each_entry(block_group, &sinfo->block_groups[index], list) {
 444                 if (&attr->attr == BTRFS_ATTR_PTR(raid, total_bytes))
 445                         val += block_group->length;
 446                 else
 447                         val += block_group->used;
 448         }
 449         up_read(&sinfo->groups_sem);
 450         return snprintf(buf, PAGE_SIZE, "%llu\n", val);
 451 }
 452
 453 static struct attribute *raid_attrs[] = {
 454         BTRFS_ATTR_PTR(raid, total_bytes),
 455         BTRFS_ATTR_PTR(raid, used_bytes),
 456         NULL
 457 };
 458 ATTRIBUTE_GROUPS(raid);
 459
 460 static void release_raid_kobj(struct kobject *kobj)
 461 {
 462         kfree(to_raid_kobj(kobj));
 463 }
 464
 465 static struct kobj_type btrfs_raid_ktype = {
 466         .sysfs_ops = &kobj_sysfs_ops,
 467         .release = release_raid_kobj,
 468         .default_groups = raid_groups,
 469 };
 470
 471 #define SPACE_INFO_ATTR(field)                                          \
 472 static ssize_t btrfs_space_info_show_##field(struct kobject *kobj,      \
 473                                              struct kobj_attribute *a,  \
 474                                              char *buf)                 \
 475 {                                                                       \
 476         struct btrfs_space_info *sinfo = to_space_info(kobj);           \
 477         return btrfs_show_u64(&sinfo->field, &sinfo->lock, buf);        \
 478 }                                                                       \
 479 BTRFS_ATTR(space_info, field, btrfs_space_info_show_##field)
 480
 481 static ssize_t btrfs_space_info_show_total_bytes_pinned(struct kobject *kobj,
 482                                                        struct kobj_attribute *a,
 483                                                        char *buf)
 484 {
 485         struct btrfs_space_info *sinfo = to_space_info(kobj);
 486         s64 val = percpu_counter_sum(&sinfo->total_bytes_pinned);
 487         return snprintf(buf, PAGE_SIZE, "%lld\n", val);
 488 }
 489
 490 SPACE_INFO_ATTR(flags);
 491 SPACE_INFO_ATTR(total_bytes);
 492 SPACE_INFO_ATTR(bytes_used);
 493 SPACE_INFO_ATTR(bytes_pinned);
 494 SPACE_INFO_ATTR(bytes_reserved);
 495 SPACE_INFO_ATTR(bytes_may_use);
 496 SPACE_INFO_ATTR(bytes_readonly);
 497 SPACE_INFO_ATTR(disk_used);
 498 SPACE_INFO_ATTR(disk_total);
 499 BTRFS_ATTR(space_info, total_bytes_pinned,
 500            btrfs_space_info_show_total_bytes_pinned);
 501
 502 static struct attribute *space_info_attrs[] = {
 503         BTRFS_ATTR_PTR(space_info, flags),
 504         BTRFS_ATTR_PTR(space_info, total_bytes),
 505         BTRFS_ATTR_PTR(space_info, bytes_used),
 506         BTRFS_ATTR_PTR(space_info, bytes_pinned),
 507         BTRFS_ATTR_PTR(space_info, bytes_reserved),
 508         BTRFS_ATTR_PTR(space_info, bytes_may_use),
 509         BTRFS_ATTR_PTR(space_info, bytes_readonly),
 510         BTRFS_ATTR_PTR(space_info, disk_used),
 511         BTRFS_ATTR_PTR(space_info, disk_total),
 512         BTRFS_ATTR_PTR(space_info, total_bytes_pinned),
 513         NULL,
 514 };
 515 ATTRIBUTE_GROUPS(space_info);
 516
 517 static void space_info_release(struct kobject *kobj)
 518 {
 519         struct btrfs_space_info *sinfo = to_space_info(kobj);
 520         percpu_counter_destroy(&sinfo->total_bytes_pinned);
 521         kfree(sinfo);
 522 }
 523
 524 static struct kobj_type space_info_ktype = {
 525         .sysfs_ops = &kobj_sysfs_ops,
 526         .release = space_info_release,
 527         .default_groups = space_info_groups,
 528 };
 529
 530 static const struct attribute *allocation_attrs[] = {
 531         BTRFS_ATTR_PTR(allocation, global_rsv_reserved),
 532         BTRFS_ATTR_PTR(allocation, global_rsv_size),
 533         NULL,
 534 };
 535
 536 static ssize_t btrfs_label_show(struct kobject *kobj,
 537                                 struct kobj_attribute *a, char *buf)
 538 {
 539         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 540         char *label = fs_info->super_copy->label;
 541         ssize_t ret;
 542
 543         spin_lock(&fs_info->super_lock);
 544         ret = snprintf(buf, PAGE_SIZE, label[0] ? "%s\n" : "%s", label);
 545         spin_unlock(&fs_info->super_lock);
 546
 547         return ret;
 548 }
 549
 550 static ssize_t btrfs_label_store(struct kobject *kobj,
 551                                  struct kobj_attribute *a,
 552                                  const char *buf, size_t len)
 553 {
 554         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 555         size_t p_len;
 556
 557         if (!fs_info)
 558                 return -EPERM;
 559
 560         if (sb_rdonly(fs_info->sb))
 561                 return -EROFS;
 562
 563         /*
 564          * p_len is the len until the first occurrence of either
 565          * '\n' or '\0'
 566          */
 567         p_len = strcspn(buf, "\n");
 568
 569         if (p_len >= BTRFS_LABEL_SIZE)
 570                 return -EINVAL;
 571
 572         spin_lock(&fs_info->super_lock);
 573         memset(fs_info->super_copy->label, 0, BTRFS_LABEL_SIZE);
 574         memcpy(fs_info->super_copy->label, buf, p_len);
 575         spin_unlock(&fs_info->super_lock);
 576
 577         /*
 578          * We don't want to do full transaction commit from inside sysfs
 579          */
 580         btrfs_set_pending(fs_info, COMMIT);
 581         wake_up_process(fs_info->transaction_kthread);
 582
 583         return len;
 584 }
 585 BTRFS_ATTR_RW(, label, btrfs_label_show, btrfs_label_store);
 586
 587 static ssize_t btrfs_nodesize_show(struct kobject *kobj,
 588                                 struct kobj_attribute *a, char *buf)
 589 {
 590         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 591
 592         return snprintf(buf, PAGE_SIZE, "%u\n", fs_info->super_copy->nodesize);
 593 }
 594
 595 BTRFS_ATTR(, nodesize, btrfs_nodesize_show);
 596
 597 static ssize_t btrfs_sectorsize_show(struct kobject *kobj,
 598                                 struct kobj_attribute *a, char *buf)
 599 {
 600         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 601
 602         return snprintf(buf, PAGE_SIZE, "%u\n",
 603                         fs_info->super_copy->sectorsize);
 604 }
 605
 606 BTRFS_ATTR(, sectorsize, btrfs_sectorsize_show);
 607
 608 static ssize_t btrfs_clone_alignment_show(struct kobject *kobj,
 609                                 struct kobj_attribute *a, char *buf)
 610 {
 611         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 612
 613         return snprintf(buf, PAGE_SIZE, "%u\n",
 614                         fs_info->super_copy->sectorsize);
 615 }
 616
 617 BTRFS_ATTR(, clone_alignment, btrfs_clone_alignment_show);
 618
 619 static ssize_t quota_override_show(struct kobject *kobj,
 620                                    struct kobj_attribute *a, char *buf)
 621 {
 622         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 623         int quota_override;
 624
 625         quota_override = test_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
 626         return snprintf(buf, PAGE_SIZE, "%d\n", quota_override);
 627 }
 628
 629 static ssize_t quota_override_store(struct kobject *kobj,
 630                                     struct kobj_attribute *a,
 631                                     const char *buf, size_t len)
 632 {
 633         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 634         unsigned long knob;
 635         int err;
 636
 637         if (!fs_info)
 638                 return -EPERM;
 639
 640         if (!capable(CAP_SYS_RESOURCE))
 641                 return -EPERM;
 642
 643         err = kstrtoul(buf, 10, &knob);
 644         if (err)
 645                 return err;
 646         if (knob > 1)
 647                 return -EINVAL;
 648
 649         if (knob)
 650                 set_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
 651         else
 652                 clear_bit(BTRFS_FS_QUOTA_OVERRIDE, &fs_info->flags);
 653
 654         return len;
 655 }
 656
 657 BTRFS_ATTR_RW(, quota_override, quota_override_show, quota_override_store);
 658
 659 static ssize_t btrfs_metadata_uuid_show(struct kobject *kobj,
 660                                 struct kobj_attribute *a, char *buf)
 661 {
 662         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 663
 664         return snprintf(buf, PAGE_SIZE, "%pU\n",
 665                         fs_info->fs_devices->metadata_uuid);
 666 }
 667
 668 BTRFS_ATTR(, metadata_uuid, btrfs_metadata_uuid_show);
 669
 670 static ssize_t btrfs_checksum_show(struct kobject *kobj,
 671                                    struct kobj_attribute *a, char *buf)
 672 {
 673         struct btrfs_fs_info *fs_info = to_fs_info(kobj);
 674         u16 csum_type = btrfs_super_csum_type(fs_info->super_copy);
 675
 676         return snprintf(buf, PAGE_SIZE, "%s (%s)\n",
 677                         btrfs_super_csum_name(csum_type),
 678                         crypto_shash_driver_name(fs_info->csum_shash));
 679 }
 680
 681 BTRFS_ATTR(, checksum, btrfs_checksum_show);
 682
 683 static const struct attribute *btrfs_attrs[] = {
 684         BTRFS_ATTR_PTR(, label),
 685         BTRFS_ATTR_PTR(, nodesize),
 686         BTRFS_ATTR_PTR(, sectorsize),
 687         BTRFS_ATTR_PTR(, clone_alignment),
 688         BTRFS_ATTR_PTR(, quota_override),
 689         BTRFS_ATTR_PTR(, metadata_uuid),
 690         BTRFS_ATTR_PTR(, checksum),
 691         NULL,
 692 };
 693
 694 static void btrfs_release_fsid_kobj(struct kobject *kobj)
 695 {
 696         struct btrfs_fs_devices *fs_devs = to_fs_devs(kobj);
 697
 698         memset(&fs_devs->fsid_kobj, 0, sizeof(struct kobject));
 699         complete(&fs_devs->kobj_unregister);
 700 }
 701
 702 static struct kobj_type btrfs_ktype = {
 703         .sysfs_ops      = &kobj_sysfs_ops,
 704         .release        = btrfs_release_fsid_kobj,
 705 };
 706
 707 static inline struct btrfs_fs_devices *to_fs_devs(struct kobject *kobj)
 708 {
 709         if (kobj->ktype != &btrfs_ktype)
 710                 return NULL;
 711         return container_of(kobj, struct btrfs_fs_devices, fsid_kobj);
 712 }
 713
 714 static inline struct btrfs_fs_info *to_fs_info(struct kobject *kobj)
 715 {
 716         if (kobj->ktype != &btrfs_ktype)
 717                 return NULL;
 718         return to_fs_devs(kobj)->fs_info;
 719 }
 720
 721 #define NUM_FEATURE_BITS 64
 722 #define BTRFS_FEATURE_NAME_MAX 13
 723 static char btrfs_unknown_feature_names[FEAT_MAX][NUM_FEATURE_BITS][BTRFS_FEATURE_NAME_MAX];
 724 static struct btrfs_feature_attr btrfs_feature_attrs[FEAT_MAX][NUM_FEATURE_BITS];
 725
 726 static const u64 supported_feature_masks[FEAT_MAX] = {
 727         [FEAT_COMPAT]    = BTRFS_FEATURE_COMPAT_SUPP,
 728         [FEAT_COMPAT_RO] = BTRFS_FEATURE_COMPAT_RO_SUPP,
 729         [FEAT_INCOMPAT]  = BTRFS_FEATURE_INCOMPAT_SUPP,
 730 };
 731
 732 static int addrm_unknown_feature_attrs(struct btrfs_fs_info *fs_info, bool add)
 733 {
 734         int set;
 735
 736         for (set = 0; set < FEAT_MAX; set++) {
 737                 int i;
 738                 struct attribute *attrs[2];
 739                 struct attribute_group agroup = {
 740                         .name = "features",
 741                         .attrs = attrs,
 742                 };
 743                 u64 features = get_features(fs_info, set);
 744                 features &= ~supported_feature_masks[set];
 745
 746                 if (!features)
 747                         continue;
 748
 749                 attrs[1] = NULL;
 750                 for (i = 0; i < NUM_FEATURE_BITS; i++) {
 751                         struct btrfs_feature_attr *fa;
 752
 753                         if (!(features & (1ULL << i)))
 754                                 continue;
 755
 756                         fa = &btrfs_feature_attrs[set][i];
 757                         attrs[0] = &fa->kobj_attr.attr;
 758                         if (add) {
 759                                 int ret;
 760                                 ret = sysfs_merge_group(&fs_info->fs_devices->fsid_kobj,
 761                                                         &agroup);
 762                                 if (ret)
 763                                         return ret;
 764                         } else
 765                                 sysfs_unmerge_group(&fs_info->fs_devices->fsid_kobj,
 766                                                     &agroup);
 767                 }
 768
 769         }
 770         return 0;
 771 }
 772
 773 static void __btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 774 {
 775         if (fs_devs->devices_kobj) {
 776                 kobject_del(fs_devs->devices_kobj);
 777                 kobject_put(fs_devs->devices_kobj);
 778                 fs_devs->devices_kobj = NULL;
 779         }
 780
 781         if (fs_devs->fsid_kobj.state_initialized) {
 782                 kobject_del(&fs_devs->fsid_kobj);
 783                 kobject_put(&fs_devs->fsid_kobj);
 784                 wait_for_completion(&fs_devs->kobj_unregister);
 785         }
 786 }
 787
 788 /* when fs_devs is NULL it will remove all fsid kobject */
 789 void btrfs_sysfs_remove_fsid(struct btrfs_fs_devices *fs_devs)
 790 {
 791         struct list_head *fs_uuids = btrfs_get_fs_uuids();
 792
 793         if (fs_devs) {
 794                 __btrfs_sysfs_remove_fsid(fs_devs);
 795                 return;
 796         }
 797
 798         list_for_each_entry(fs_devs, fs_uuids, fs_list) {
 799                 __btrfs_sysfs_remove_fsid(fs_devs);
 800         }
 801 }
 802
 803 void btrfs_sysfs_remove_mounted(struct btrfs_fs_info *fs_info)
 804 {
 805         btrfs_reset_fs_info_ptr(fs_info);
 806
 807         if (fs_info->space_info_kobj) {
 808                 sysfs_remove_files(fs_info->space_info_kobj, allocation_attrs);
 809                 kobject_del(fs_info->space_info_kobj);
 810                 kobject_put(fs_info->space_info_kobj);
 811         }
 812 #ifdef CONFIG_BTRFS_DEBUG
 813         if (fs_info->discard_debug_kobj) {
 814                 sysfs_remove_files(fs_info->discard_debug_kobj,
 815                                    discard_debug_attrs);
 816                 kobject_del(fs_info->discard_debug_kobj);
 817                 kobject_put(fs_info->discard_debug_kobj);
 818         }
 819         if (fs_info->debug_kobj) {
 820                 sysfs_remove_files(fs_info->debug_kobj, btrfs_debug_mount_attrs);
 821                 kobject_del(fs_info->debug_kobj);
 822                 kobject_put(fs_info->debug_kobj);
 823         }
 824 #endif
 825         addrm_unknown_feature_attrs(fs_info, false);
 826         sysfs_remove_group(&fs_info->fs_devices->fsid_kobj, &btrfs_feature_attr_group);
 827         sysfs_remove_files(&fs_info->fs_devices->fsid_kobj, btrfs_attrs);
 828         btrfs_sysfs_rm_device_link(fs_info->fs_devices, NULL);
 829 }
 830
 831 static const char * const btrfs_feature_set_names[FEAT_MAX] = {
 832         [FEAT_COMPAT]    = "compat",
 833         [FEAT_COMPAT_RO] = "compat_ro",
 834         [FEAT_INCOMPAT]  = "incompat",
 835 };
 836
 837 const char * const btrfs_feature_set_name(enum btrfs_feature_set set)
 838 {
 839         return btrfs_feature_set_names[set];
 840 }
 841
 842 char *btrfs_printable_features(enum btrfs_feature_set set, u64 flags)
 843 {
 844         size_t bufsize = 4096; /* safe max, 64 names * 64 bytes */
 845         int len = 0;
 846         int i;
 847         char *str;
 848
 849         str = kmalloc(bufsize, GFP_KERNEL);
 850         if (!str)
 851                 return str;
 852
 853         for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
 854                 const char *name;
 855
 856                 if (!(flags & (1ULL << i)))
 857                         continue;
 858
 859                 name = btrfs_feature_attrs[set][i].kobj_attr.attr.name;
 860                 len += snprintf(str + len, bufsize - len, "%s%s",
 861                                 len ? "," : "", name);
 862         }
 863
 864         return str;
 865 }
 866
 867 static void init_feature_attrs(void)
 868 {
 869         struct btrfs_feature_attr *fa;
 870         int set, i;
 871
 872         BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names) !=
 873                      ARRAY_SIZE(btrfs_feature_attrs));
 874         BUILD_BUG_ON(ARRAY_SIZE(btrfs_unknown_feature_names[0]) !=
 875                      ARRAY_SIZE(btrfs_feature_attrs[0]));
 876
 877         memset(btrfs_feature_attrs, 0, sizeof(btrfs_feature_attrs));
 878         memset(btrfs_unknown_feature_names, 0,
 879                sizeof(btrfs_unknown_feature_names));
 880
 881         for (i = 0; btrfs_supported_feature_attrs[i]; i++) {
 882                 struct btrfs_feature_attr *sfa;
 883                 struct attribute *a = btrfs_supported_feature_attrs[i];
 884                 int bit;
 885                 sfa = attr_to_btrfs_feature_attr(a);
 886                 bit = ilog2(sfa->feature_bit);
 887                 fa = &btrfs_feature_attrs[sfa->feature_set][bit];
 888
 889                 fa->kobj_attr.attr.name = sfa->kobj_attr.attr.name;
 890         }
 891
 892         for (set = 0; set < FEAT_MAX; set++) {
 893                 for (i = 0; i < ARRAY_SIZE(btrfs_feature_attrs[set]); i++) {
 894                         char *name = btrfs_unknown_feature_names[set][i];
 895                         fa = &btrfs_feature_attrs[set][i];
 896
 897                         if (fa->kobj_attr.attr.name)
 898                                 continue;
 899
 900                         snprintf(name, BTRFS_FEATURE_NAME_MAX, "%s:%u",
 901                                  btrfs_feature_set_names[set], i);
 902
 903                         fa->kobj_attr.attr.name = name;
 904                         fa->kobj_attr.attr.mode = S_IRUGO;
 905                         fa->feature_set = set;
 906                         fa->feature_bit = 1ULL << i;
 907                 }
 908         }
 909 }
 910
 911 /*
 912  * Create a sysfs entry for a given block group type at path
 913  * /sys/fs/btrfs/UUID/allocation/data/TYPE
 914  */
 915 void btrfs_sysfs_add_block_group_type(struct btrfs_block_group *cache)
 916 {
 917         struct btrfs_fs_info *fs_info = cache->fs_info;
 918         struct btrfs_space_info *space_info = cache->space_info;
 919         struct raid_kobject *rkobj;
 920         const int index = btrfs_bg_flags_to_raid_index(cache->flags);
 921         unsigned int nofs_flag;
 922         int ret;
 923
 924         /*
 925          * Setup a NOFS context because kobject_add(), deep in its call chain,
 926          * does GFP_KERNEL allocations, and we are often called in a context
 927          * where if reclaim is triggered we can deadlock (we are either holding
 928          * a transaction handle or some lock required for a transaction
 929          * commit).
 930          */
 931         nofs_flag = memalloc_nofs_save();
 932
 933         rkobj = kzalloc(sizeof(*rkobj), GFP_NOFS);
 934         if (!rkobj) {
 935                 memalloc_nofs_restore(nofs_flag);
 936                 btrfs_warn(cache->fs_info,
 937                                 "couldn't alloc memory for raid level kobject");
 938                 return;
 939         }
 940
 941         rkobj->flags = cache->flags;
 942         kobject_init(&rkobj->kobj, &btrfs_raid_ktype);
 943         ret = kobject_add(&rkobj->kobj, &space_info->kobj, "%s",
 944                           btrfs_bg_type_to_raid_name(rkobj->flags));
 945         memalloc_nofs_restore(nofs_flag);
 946         if (ret) {
 947                 kobject_put(&rkobj->kobj);
 948                 btrfs_warn(fs_info,
 949                         "failed to add kobject for block cache, ignoring");
 950                 return;
 951         }
 952
 953         space_info->block_group_kobjs[index] = &rkobj->kobj;
 954 }
 955
 956 /*
 957  * Remove sysfs directories for all block group types of a given space info and
 958  * the space info as well
 959  */
 960 void btrfs_sysfs_remove_space_info(struct btrfs_space_info *space_info)
 961 {
 962         int i;
 963
 964         for (i = 0; i < BTRFS_NR_RAID_TYPES; i++) {
 965                 struct kobject *kobj;
 966
 967                 kobj = space_info->block_group_kobjs[i];
 968                 space_info->block_group_kobjs[i] = NULL;
 969                 if (kobj) {
 970                         kobject_del(kobj);
 971                         kobject_put(kobj);
 972                 }
 973         }
 974         kobject_del(&space_info->kobj);
 975         kobject_put(&space_info->kobj);
 976 }
 977
 978 static const char *alloc_name(u64 flags)
 979 {
 980         switch (flags) {
 981         case BTRFS_BLOCK_GROUP_METADATA | BTRFS_BLOCK_GROUP_DATA:
 982                 return "mixed";
 983         case BTRFS_BLOCK_GROUP_METADATA:
 984                 return "metadata";
 985         case BTRFS_BLOCK_GROUP_DATA:
 986                 return "data";
 987         case BTRFS_BLOCK_GROUP_SYSTEM:
 988                 return "system";
 989         default:
 990                 WARN_ON(1);
 991                 return "invalid-combination";
 992         };
 993 }
 994
 995 /*
 996  * Create a sysfs entry for a space info type at path
 997  * /sys/fs/btrfs/UUID/allocation/TYPE
 998  */
 999 int btrfs_sysfs_add_space_info_type(struct btrfs_fs_info *fs_info,
1000                                     struct btrfs_space_info *space_info)
1001 {
1002         int ret;
1003
1004         ret = kobject_init_and_add(&space_info->kobj, &space_info_ktype,
1005                                    fs_info->space_info_kobj, "%s",
1006                                    alloc_name(space_info->flags));
1007         if (ret) {
1008                 kobject_put(&space_info->kobj);
1009                 return ret;
1010         }
1011
1012         return 0;
1013 }
1014
1015 /* when one_device is NULL, it removes all device links */
1016
1017 int btrfs_sysfs_rm_device_link(struct btrfs_fs_devices *fs_devices,
1018                 struct btrfs_device *one_device)
1019 {
1020         struct hd_struct *disk;
1021         struct kobject *disk_kobj;
1022
1023         if (!fs_devices->devices_kobj)
1024                 return -EINVAL;
1025
1026         if (one_device && one_device->bdev) {
1027                 disk = one_device->bdev->bd_part;
1028                 disk_kobj = &part_to_dev(disk)->kobj;
1029
1030                 sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
1031         }
1032
1033         if (one_device)
1034                 return 0;
1035
1036         list_for_each_entry(one_device,
1037                         &fs_devices->devices, dev_list) {
1038                 if (!one_device->bdev)
1039                         continue;
1040                 disk = one_device->bdev->bd_part;
1041                 disk_kobj = &part_to_dev(disk)->kobj;
1042
1043                 sysfs_remove_link(fs_devices->devices_kobj, disk_kobj->name);
1044         }
1045
1046         return 0;
1047 }
1048
1049 int btrfs_sysfs_add_device_link(struct btrfs_fs_devices *fs_devices,
1050                                 struct btrfs_device *one_device)
1051 {
1052         int error = 0;
1053         struct btrfs_device *dev;
1054
1055         list_for_each_entry(dev, &fs_devices->devices, dev_list) {
1056                 struct hd_struct *disk;
1057                 struct kobject *disk_kobj;
1058
1059                 if (!dev->bdev)
1060                         continue;
1061
1062                 if (one_device && one_device != dev)
1063                         continue;
1064
1065                 disk = dev->bdev->bd_part;
1066                 disk_kobj = &part_to_dev(disk)->kobj;
1067
1068                 error = sysfs_create_link(fs_devices->devices_kobj,
1069                                           disk_kobj, disk_kobj->name);
1070                 if (error)
1071                         break;
1072         }
1073
1074         return error;
1075 }
1076
1077 void btrfs_kobject_uevent(struct block_device *bdev, enum kobject_action action)
1078 {
1079         int ret;
1080
1081         ret = kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, action);
1082         if (ret)
1083                 pr_warn("BTRFS: Sending event '%d' to kobject: '%s' (%p): failed\n",
1084                         action, kobject_name(&disk_to_dev(bdev->bd_disk)->kobj),
1085                         &disk_to_dev(bdev->bd_disk)->kobj);
1086 }
1087
1088 void btrfs_sysfs_update_sprout_fsid(struct btrfs_fs_devices *fs_devices,
1089                                     const u8 *fsid)
1090 {
1091         char fsid_buf[BTRFS_UUID_UNPARSED_SIZE];
1092
1093         /*
1094          * Sprouting changes fsid of the mounted filesystem, rename the fsid
1095          * directory
1096          */
1097         snprintf(fsid_buf, BTRFS_UUID_UNPARSED_SIZE, "%pU", fsid);
1098         if (kobject_rename(&fs_devices->fsid_kobj, fsid_buf))
1099                 btrfs_warn(fs_devices->fs_info,
1100                                 "sysfs: failed to create fsid for sprout");
1101 }
1102
1103 /* /sys/fs/btrfs/ entry */
1104 static struct kset *btrfs_kset;
1105
1106 /*
1107  * Creates:
1108  *              /sys/fs/btrfs/UUID
1109  *
1110  * Can be called by the device discovery thread.
1111  */
1112 int btrfs_sysfs_add_fsid(struct btrfs_fs_devices *fs_devs)
1113 {
1114         int error;
1115
1116         init_completion(&fs_devs->kobj_unregister);
1117         fs_devs->fsid_kobj.kset = btrfs_kset;
1118         error = kobject_init_and_add(&fs_devs->fsid_kobj, &btrfs_ktype, NULL,
1119                                      "%pU", fs_devs->fsid);
1120         if (error) {
1121                 kobject_put(&fs_devs->fsid_kobj);
1122                 return error;
1123         }
1124
1125         fs_devs->devices_kobj = kobject_create_and_add("devices",
1126                                                        &fs_devs->fsid_kobj);
1127         if (!fs_devs->devices_kobj) {
1128                 btrfs_err(fs_devs->fs_info,
1129                           "failed to init sysfs device interface");
1130                 kobject_put(&fs_devs->fsid_kobj);
1131                 return -ENOMEM;
1132         }
1133
1134         return 0;
1135 }
1136
1137 int btrfs_sysfs_add_mounted(struct btrfs_fs_info *fs_info)
1138 {
1139         int error;
1140         struct btrfs_fs_devices *fs_devs = fs_info->fs_devices;
1141         struct kobject *fsid_kobj = &fs_devs->fsid_kobj;
1142
1143         btrfs_set_fs_info_ptr(fs_info);
1144
1145         error = btrfs_sysfs_add_device_link(fs_devs, NULL);
1146         if (error)
1147                 return error;
1148
1149         error = sysfs_create_files(fsid_kobj, btrfs_attrs);
1150         if (error) {
1151                 btrfs_sysfs_rm_device_link(fs_devs, NULL);
1152                 return error;
1153         }
1154
1155         error = sysfs_create_group(fsid_kobj,
1156                                    &btrfs_feature_attr_group);
1157         if (error)
1158                 goto failure;
1159
1160 #ifdef CONFIG_BTRFS_DEBUG
1161         fs_info->debug_kobj = kobject_create_and_add("debug", fsid_kobj);
1162         if (!fs_info->debug_kobj) {
1163                 error = -ENOMEM;
1164                 goto failure;
1165         }
1166
1167         error = sysfs_create_files(fs_info->debug_kobj, btrfs_debug_mount_attrs);
1168         if (error)
1169                 goto failure;
1170
1171         /* Discard directory */
1172         fs_info->discard_debug_kobj = kobject_create_and_add("discard",
1173                                                      fs_info->debug_kobj);
1174         if (!fs_info->discard_debug_kobj) {
1175                 error = -ENOMEM;
1176                 goto failure;
1177         }
1178
1179         error = sysfs_create_files(fs_info->discard_debug_kobj,
1180                                    discard_debug_attrs);
1181         if (error)
1182                 goto failure;
1183 #endif
1184
1185         error = addrm_unknown_feature_attrs(fs_info, true);
1186         if (error)
1187                 goto failure;
1188
1189         fs_info->space_info_kobj = kobject_create_and_add("allocation",
1190                                                   fsid_kobj);
1191         if (!fs_info->space_info_kobj) {
1192                 error = -ENOMEM;
1193                 goto failure;
1194         }
1195
1196         error = sysfs_create_files(fs_info->space_info_kobj, allocation_attrs);
1197         if (error)
1198                 goto failure;
1199
1200         return 0;
1201 failure:
1202         btrfs_sysfs_remove_mounted(fs_info);
1203         return error;
1204 }
1205
1206
1207 /*
1208  * Change per-fs features in /sys/fs/btrfs/UUID/features to match current
1209  * values in superblock. Call after any changes to incompat/compat_ro flags
1210  */
1211 void btrfs_sysfs_feature_update(struct btrfs_fs_info *fs_info,
1212                 u64 bit, enum btrfs_feature_set set)
1213 {
1214         struct btrfs_fs_devices *fs_devs;
1215         struct kobject *fsid_kobj;
1216         u64 features;
1217         int ret;
1218
1219         if (!fs_info)
1220                 return;
1221
1222         features = get_features(fs_info, set);
1223         ASSERT(bit & supported_feature_masks[set]);
1224
1225         fs_devs = fs_info->fs_devices;
1226         fsid_kobj = &fs_devs->fsid_kobj;
1227
1228         if (!fsid_kobj->state_initialized)
1229                 return;
1230
1231         /*
1232          * FIXME: this is too heavy to update just one value, ideally we'd like
1233          * to use sysfs_update_group but some refactoring is needed first.
1234          */
1235         sysfs_remove_group(fsid_kobj, &btrfs_feature_attr_group);
1236         ret = sysfs_create_group(fsid_kobj, &btrfs_feature_attr_group);
1237 }
1238
1239 int __init btrfs_init_sysfs(void)
1240 {
1241         int ret;
1242
1243         btrfs_kset = kset_create_and_add("btrfs", NULL, fs_kobj);
1244         if (!btrfs_kset)
1245                 return -ENOMEM;
1246
1247         init_feature_attrs();
1248         ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
1249         if (ret)
1250                 goto out2;
1251         ret = sysfs_merge_group(&btrfs_kset->kobj,
1252                                 &btrfs_static_feature_attr_group);
1253         if (ret)
1254                 goto out_remove_group;
1255
1256 #ifdef CONFIG_BTRFS_DEBUG
1257         ret = sysfs_create_group(&btrfs_kset->kobj, &btrfs_debug_feature_attr_group);
1258         if (ret)
1259                 goto out2;
1260 #endif
1261
1262         return 0;
1263
1264 out_remove_group:
1265         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
1266 out2:
1267         kset_unregister(btrfs_kset);
1268
1269         return ret;
1270 }
1271
1272 void __cold btrfs_exit_sysfs(void)
1273 {
1274         sysfs_unmerge_group(&btrfs_kset->kobj,
1275                             &btrfs_static_feature_attr_group);
1276         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_feature_attr_group);
1277 #ifdef CONFIG_BTRFS_DEBUG
1278         sysfs_remove_group(&btrfs_kset->kobj, &btrfs_debug_feature_attr_group);
1279 #endif
1280         kset_unregister(btrfs_kset);
1281 }
1282