fs/btrfs/uuid-tree.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STRATO AG 2013.  All rights reserved.
   4  */
   5
   6 #include <linux/kthread.h>
   7 #include <linux/uuid.h>
   8 #include <linux/unaligned.h>
   9 #include "messages.h"
  10 #include "ctree.h"
  11 #include "transaction.h"
  12 #include "disk-io.h"
  13 #include "fs.h"
  14 #include "accessors.h"
  15 #include "uuid-tree.h"
  16 #include "ioctl.h"
  17
  18 static void btrfs_uuid_to_key(const u8 *uuid, u8 type, struct btrfs_key *key)
  19 {
  20         key->type = type;
  21         key->objectid = get_unaligned_le64(uuid);
  22         key->offset = get_unaligned_le64(uuid + sizeof(u64));
  23 }
  24
  25 /* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
  26 static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, const u8 *uuid,
  27                                   u8 type, u64 subid)
  28 {
  29         int ret;
  30         struct btrfs_path *path = NULL;
  31         struct extent_buffer *eb;
  32         int slot;
  33         u32 item_size;
  34         unsigned long offset;
  35         struct btrfs_key key;
  36
  37         if (WARN_ON_ONCE(!uuid_root)) {
  38                 ret = -ENOENT;
  39                 goto out;
  40         }
  41
  42         path = btrfs_alloc_path();
  43         if (!path) {
  44                 ret = -ENOMEM;
  45                 goto out;
  46         }
  47
  48         btrfs_uuid_to_key(uuid, type, &key);
  49         ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
  50         if (ret < 0) {
  51                 goto out;
  52         } else if (ret > 0) {
  53                 ret = -ENOENT;
  54                 goto out;
  55         }
  56
  57         eb = path->nodes[0];
  58         slot = path->slots[0];
  59         item_size = btrfs_item_size(eb, slot);
  60         offset = btrfs_item_ptr_offset(eb, slot);
  61         ret = -ENOENT;
  62
  63         if (!IS_ALIGNED(item_size, sizeof(u64))) {
  64                 btrfs_warn(uuid_root->fs_info,
  65                            "uuid item with illegal size %lu!",
  66                            (unsigned long)item_size);
  67                 goto out;
  68         }
  69         while (item_size) {
  70                 __le64 data;
  71
  72                 read_extent_buffer(eb, &data, offset, sizeof(data));
  73                 if (le64_to_cpu(data) == subid) {
  74                         ret = 0;
  75                         break;
  76                 }
  77                 offset += sizeof(data);
  78                 item_size -= sizeof(data);
  79         }
  80
  81 out:
  82         btrfs_free_path(path);
  83         return ret;
  84 }
  85
  86 int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans, const u8 *uuid, u8 type,
  87                         u64 subid_cpu)
  88 {
  89         struct btrfs_fs_info *fs_info = trans->fs_info;
  90         struct btrfs_root *uuid_root = fs_info->uuid_root;
  91         int ret;
  92         struct btrfs_path *path = NULL;
  93         struct btrfs_key key;
  94         struct extent_buffer *eb;
  95         int slot;
  96         unsigned long offset;
  97         __le64 subid_le;
  98
  99         ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
 100         if (ret != -ENOENT)
 101                 return ret;
 102
 103         if (WARN_ON_ONCE(!uuid_root)) {
 104                 ret = -EINVAL;
 105                 goto out;
 106         }
 107
 108         btrfs_uuid_to_key(uuid, type, &key);
 109
 110         path = btrfs_alloc_path();
 111         if (!path) {
 112                 ret = -ENOMEM;
 113                 goto out;
 114         }
 115
 116         ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
 117                                       sizeof(subid_le));
 118         if (ret == 0) {
 119                 /* Add an item for the type for the first time */
 120                 eb = path->nodes[0];
 121                 slot = path->slots[0];
 122                 offset = btrfs_item_ptr_offset(eb, slot);
 123         } else if (ret == -EEXIST) {
 124                 /*
 125                  * An item with that type already exists.
 126                  * Extend the item and store the new subid at the end.
 127                  */
 128                 btrfs_extend_item(trans, path, sizeof(subid_le));
 129                 eb = path->nodes[0];
 130                 slot = path->slots[0];
 131                 offset = btrfs_item_ptr_offset(eb, slot);
 132                 offset += btrfs_item_size(eb, slot) - sizeof(subid_le);
 133         } else {
 134                 btrfs_warn(fs_info,
 135                            "insert uuid item failed %d (0x%016llx, 0x%016llx) type %u!",
 136                            ret, key.objectid, key.offset, type);
 137                 goto out;
 138         }
 139
 140         ret = 0;
 141         subid_le = cpu_to_le64(subid_cpu);
 142         write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
 143 out:
 144         btrfs_free_path(path);
 145         return ret;
 146 }
 147
 148 int btrfs_uuid_tree_remove(struct btrfs_trans_handle *trans, const u8 *uuid, u8 type,
 149                         u64 subid)
 150 {
 151         struct btrfs_fs_info *fs_info = trans->fs_info;
 152         struct btrfs_root *uuid_root = fs_info->uuid_root;
 153         int ret;
 154         struct btrfs_path *path = NULL;
 155         struct btrfs_key key;
 156         struct extent_buffer *eb;
 157         int slot;
 158         unsigned long offset;
 159         u32 item_size;
 160         unsigned long move_dst;
 161         unsigned long move_src;
 162         unsigned long move_len;
 163
 164         if (WARN_ON_ONCE(!uuid_root)) {
 165                 ret = -EINVAL;
 166                 goto out;
 167         }
 168
 169         btrfs_uuid_to_key(uuid, type, &key);
 170
 171         path = btrfs_alloc_path();
 172         if (!path) {
 173                 ret = -ENOMEM;
 174                 goto out;
 175         }
 176
 177         ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
 178         if (ret < 0) {
 179                 btrfs_warn(fs_info, "error %d while searching for uuid item!",
 180                            ret);
 181                 goto out;
 182         }
 183         if (ret > 0) {
 184                 ret = -ENOENT;
 185                 goto out;
 186         }
 187
 188         eb = path->nodes[0];
 189         slot = path->slots[0];
 190         offset = btrfs_item_ptr_offset(eb, slot);
 191         item_size = btrfs_item_size(eb, slot);
 192         if (!IS_ALIGNED(item_size, sizeof(u64))) {
 193                 btrfs_warn(fs_info, "uuid item with illegal size %lu!",
 194                            (unsigned long)item_size);
 195                 ret = -ENOENT;
 196                 goto out;
 197         }
 198         while (item_size) {
 199                 __le64 read_subid;
 200
 201                 read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
 202                 if (le64_to_cpu(read_subid) == subid)
 203                         break;
 204                 offset += sizeof(read_subid);
 205                 item_size -= sizeof(read_subid);
 206         }
 207
 208         if (!item_size) {
 209                 ret = -ENOENT;
 210                 goto out;
 211         }
 212
 213         item_size = btrfs_item_size(eb, slot);
 214         if (item_size == sizeof(subid)) {
 215                 ret = btrfs_del_item(trans, uuid_root, path);
 216                 goto out;
 217         }
 218
 219         move_dst = offset;
 220         move_src = offset + sizeof(subid);
 221         move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
 222         memmove_extent_buffer(eb, move_dst, move_src, move_len);
 223         btrfs_truncate_item(trans, path, item_size - sizeof(subid), 1);
 224
 225 out:
 226         btrfs_free_path(path);
 227         return ret;
 228 }
 229
 230 static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
 231                                u64 subid)
 232 {
 233         struct btrfs_trans_handle *trans;
 234         int ret;
 235
 236         /* 1 - for the uuid item */
 237         trans = btrfs_start_transaction(uuid_root, 1);
 238         if (IS_ERR(trans)) {
 239                 ret = PTR_ERR(trans);
 240                 goto out;
 241         }
 242
 243         ret = btrfs_uuid_tree_remove(trans, uuid, type, subid);
 244         btrfs_end_transaction(trans);
 245
 246 out:
 247         return ret;
 248 }
 249
 250 /*
 251  * Check if there's an matching subvolume for given UUID
 252  *
 253  * Return:
 254  * 0    check succeeded, the entry is not outdated
 255  * > 0  if the check failed, the caller should remove the entry
 256  * < 0  if an error occurred
 257  */
 258 static int btrfs_check_uuid_tree_entry(struct btrfs_fs_info *fs_info,
 259                                        const u8 *uuid, u8 type, u64 subvolid)
 260 {
 261         int ret = 0;
 262         struct btrfs_root *subvol_root;
 263
 264         if (type != BTRFS_UUID_KEY_SUBVOL &&
 265             type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
 266                 goto out;
 267
 268         subvol_root = btrfs_get_fs_root(fs_info, subvolid, true);
 269         if (IS_ERR(subvol_root)) {
 270                 ret = PTR_ERR(subvol_root);
 271                 if (ret == -ENOENT)
 272                         ret = 1;
 273                 goto out;
 274         }
 275
 276         switch (type) {
 277         case BTRFS_UUID_KEY_SUBVOL:
 278                 if (memcmp(uuid, subvol_root->root_item.uuid, BTRFS_UUID_SIZE))
 279                         ret = 1;
 280                 break;
 281         case BTRFS_UUID_KEY_RECEIVED_SUBVOL:
 282                 if (memcmp(uuid, subvol_root->root_item.received_uuid,
 283                            BTRFS_UUID_SIZE))
 284                         ret = 1;
 285                 break;
 286         }
 287         btrfs_put_root(subvol_root);
 288 out:
 289         return ret;
 290 }
 291
 292 int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info)
 293 {
 294         struct btrfs_root *root = fs_info->uuid_root;
 295         struct btrfs_key key;
 296         struct btrfs_path *path;
 297         int ret = 0;
 298         struct extent_buffer *leaf;
 299         int slot;
 300         u32 item_size;
 301         unsigned long offset;
 302
 303         path = btrfs_alloc_path();
 304         if (!path) {
 305                 ret = -ENOMEM;
 306                 goto out;
 307         }
 308
 309         key.objectid = 0;
 310         key.type = 0;
 311         key.offset = 0;
 312
 313 again_search_slot:
 314         ret = btrfs_search_forward(root, &key, path, BTRFS_OLDEST_GENERATION);
 315         if (ret) {
 316                 if (ret > 0)
 317                         ret = 0;
 318                 goto out;
 319         }
 320
 321         while (1) {
 322                 if (btrfs_fs_closing(fs_info)) {
 323                         ret = -EINTR;
 324                         goto out;
 325                 }
 326                 cond_resched();
 327                 leaf = path->nodes[0];
 328                 slot = path->slots[0];
 329                 btrfs_item_key_to_cpu(leaf, &key, slot);
 330
 331                 if (key.type != BTRFS_UUID_KEY_SUBVOL &&
 332                     key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
 333                         goto skip;
 334
 335                 offset = btrfs_item_ptr_offset(leaf, slot);
 336                 item_size = btrfs_item_size(leaf, slot);
 337                 if (!IS_ALIGNED(item_size, sizeof(u64))) {
 338                         btrfs_warn(fs_info,
 339                                    "uuid item with illegal size %lu!",
 340                                    (unsigned long)item_size);
 341                         goto skip;
 342                 }
 343                 while (item_size) {
 344                         u8 uuid[BTRFS_UUID_SIZE];
 345                         __le64 subid_le;
 346                         u64 subid_cpu;
 347
 348                         put_unaligned_le64(key.objectid, uuid);
 349                         put_unaligned_le64(key.offset, uuid + sizeof(u64));
 350                         read_extent_buffer(leaf, &subid_le, offset,
 351                                            sizeof(subid_le));
 352                         subid_cpu = le64_to_cpu(subid_le);
 353                         ret = btrfs_check_uuid_tree_entry(fs_info, uuid,
 354                                                           key.type, subid_cpu);
 355                         if (ret < 0)
 356                                 goto out;
 357                         if (ret > 0) {
 358                                 btrfs_release_path(path);
 359                                 ret = btrfs_uuid_iter_rem(root, uuid, key.type,
 360                                                           subid_cpu);
 361                                 if (ret == 0) {
 362                                         /*
 363                                          * this might look inefficient, but the
 364                                          * justification is that it is an
 365                                          * exception that check_func returns 1,
 366                                          * and that in the regular case only one
 367                                          * entry per UUID exists.
 368                                          */
 369                                         goto again_search_slot;
 370                                 }
 371                                 if (ret < 0 && ret != -ENOENT)
 372                                         goto out;
 373                                 key.offset++;
 374                                 goto again_search_slot;
 375                         }
 376                         item_size -= sizeof(subid_le);
 377                         offset += sizeof(subid_le);
 378                 }
 379
 380 skip:
 381                 ret = btrfs_next_item(root, path);
 382                 if (ret == 0)
 383                         continue;
 384                 else if (ret > 0)
 385                         ret = 0;
 386                 break;
 387         }
 388
 389 out:
 390         btrfs_free_path(path);
 391         return ret;
 392 }
 393
 394 int btrfs_uuid_scan_kthread(void *data)
 395 {
 396         struct btrfs_fs_info *fs_info = data;
 397         struct btrfs_root *root = fs_info->tree_root;
 398         struct btrfs_key key;
 399         struct btrfs_path *path = NULL;
 400         int ret = 0;
 401         struct extent_buffer *eb;
 402         int slot;
 403         struct btrfs_root_item root_item;
 404         u32 item_size;
 405         struct btrfs_trans_handle *trans = NULL;
 406         bool closing = false;
 407
 408         path = btrfs_alloc_path();
 409         if (!path) {
 410                 ret = -ENOMEM;
 411                 goto out;
 412         }
 413
 414         key.objectid = 0;
 415         key.type = BTRFS_ROOT_ITEM_KEY;
 416         key.offset = 0;
 417
 418         while (1) {
 419                 if (btrfs_fs_closing(fs_info)) {
 420                         closing = true;
 421                         break;
 422                 }
 423                 ret = btrfs_search_forward(root, &key, path,
 424                                 BTRFS_OLDEST_GENERATION);
 425                 if (ret) {
 426                         if (ret > 0)
 427                                 ret = 0;
 428                         break;
 429                 }
 430
 431                 if (key.type != BTRFS_ROOT_ITEM_KEY ||
 432                     (key.objectid < BTRFS_FIRST_FREE_OBJECTID &&
 433                      key.objectid != BTRFS_FS_TREE_OBJECTID) ||
 434                     key.objectid > BTRFS_LAST_FREE_OBJECTID)
 435                         goto skip;
 436
 437                 eb = path->nodes[0];
 438                 slot = path->slots[0];
 439                 item_size = btrfs_item_size(eb, slot);
 440                 if (item_size < sizeof(root_item))
 441                         goto skip;
 442
 443                 read_extent_buffer(eb, &root_item,
 444                                    btrfs_item_ptr_offset(eb, slot),
 445                                    (int)sizeof(root_item));
 446                 if (btrfs_root_refs(&root_item) == 0)
 447                         goto skip;
 448
 449                 if (!btrfs_is_empty_uuid(root_item.uuid) ||
 450                     !btrfs_is_empty_uuid(root_item.received_uuid)) {
 451                         if (trans)
 452                                 goto update_tree;
 453
 454                         btrfs_release_path(path);
 455                         /*
 456                          * 1 - subvol uuid item
 457                          * 1 - received_subvol uuid item
 458                          */
 459                         trans = btrfs_start_transaction(fs_info->uuid_root, 2);
 460                         if (IS_ERR(trans)) {
 461                                 ret = PTR_ERR(trans);
 462                                 break;
 463                         }
 464                         continue;
 465                 } else {
 466                         goto skip;
 467                 }
 468 update_tree:
 469                 btrfs_release_path(path);
 470                 if (!btrfs_is_empty_uuid(root_item.uuid)) {
 471                         ret = btrfs_uuid_tree_add(trans, root_item.uuid,
 472                                                   BTRFS_UUID_KEY_SUBVOL,
 473                                                   key.objectid);
 474                         if (ret < 0) {
 475                                 btrfs_warn(fs_info, "uuid_tree_add failed %d",
 476                                         ret);
 477                                 break;
 478                         }
 479                 }
 480
 481                 if (!btrfs_is_empty_uuid(root_item.received_uuid)) {
 482                         ret = btrfs_uuid_tree_add(trans,
 483                                                   root_item.received_uuid,
 484                                                  BTRFS_UUID_KEY_RECEIVED_SUBVOL,
 485                                                   key.objectid);
 486                         if (ret < 0) {
 487                                 btrfs_warn(fs_info, "uuid_tree_add failed %d",
 488                                         ret);
 489                                 break;
 490                         }
 491                 }
 492
 493 skip:
 494                 btrfs_release_path(path);
 495                 if (trans) {
 496                         ret = btrfs_end_transaction(trans);
 497                         trans = NULL;
 498                         if (ret)
 499                                 break;
 500                 }
 501
 502                 if (key.offset < (u64)-1) {
 503                         key.offset++;
 504                 } else if (key.type < BTRFS_ROOT_ITEM_KEY) {
 505                         key.offset = 0;
 506                         key.type = BTRFS_ROOT_ITEM_KEY;
 507                 } else if (key.objectid < (u64)-1) {
 508                         key.offset = 0;
 509                         key.type = BTRFS_ROOT_ITEM_KEY;
 510                         key.objectid++;
 511                 } else {
 512                         break;
 513                 }
 514                 cond_resched();
 515         }
 516
 517 out:
 518         btrfs_free_path(path);
 519         if (trans && !IS_ERR(trans))
 520                 btrfs_end_transaction(trans);
 521         if (ret)
 522                 btrfs_warn(fs_info, "btrfs_uuid_scan_kthread failed %d", ret);
 523         else if (!closing)
 524                 set_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags);
 525         up(&fs_info->uuid_tree_rescan_sem);
 526         return 0;
 527 }
 528
 529 int btrfs_create_uuid_tree(struct btrfs_fs_info *fs_info)
 530 {
 531         struct btrfs_trans_handle *trans;
 532         struct btrfs_root *tree_root = fs_info->tree_root;
 533         struct btrfs_root *uuid_root;
 534         struct task_struct *task;
 535         int ret;
 536
 537         /*
 538          * 1 - root node
 539          * 1 - root item
 540          */
 541         trans = btrfs_start_transaction(tree_root, 2);
 542         if (IS_ERR(trans))
 543                 return PTR_ERR(trans);
 544
 545         uuid_root = btrfs_create_tree(trans, BTRFS_UUID_TREE_OBJECTID);
 546         if (IS_ERR(uuid_root)) {
 547                 ret = PTR_ERR(uuid_root);
 548                 btrfs_abort_transaction(trans, ret);
 549                 btrfs_end_transaction(trans);
 550                 return ret;
 551         }
 552
 553         fs_info->uuid_root = uuid_root;
 554
 555         ret = btrfs_commit_transaction(trans);
 556         if (ret)
 557                 return ret;
 558
 559         down(&fs_info->uuid_tree_rescan_sem);
 560         task = kthread_run(btrfs_uuid_scan_kthread, fs_info, "btrfs-uuid");
 561         if (IS_ERR(task)) {
 562                 /* fs_info->update_uuid_tree_gen remains 0 in all error case */
 563                 btrfs_warn(fs_info, "failed to start uuid_scan task");
 564                 up(&fs_info->uuid_tree_rescan_sem);
 565                 return PTR_ERR(task);
 566         }
 567
 568         return 0;
 569 }