fs/btrfs/root-tree.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/err.h>
   7 #include <linux/uuid.h>
   8 #include "ctree.h"
   9 #include "transaction.h"
  10 #include "disk-io.h"
  11 #include "print-tree.h"
  12
  13 /*
  14  * Read a root item from the tree. In case we detect a root item smaller then
  15  * sizeof(root_item), we know it's an old version of the root structure and
  16  * initialize all new fields to zero. The same happens if we detect mismatching
  17  * generation numbers as then we know the root was once mounted with an older
  18  * kernel that was not aware of the root item structure change.
  19  */
  20 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
  21                                 struct btrfs_root_item *item)
  22 {
  23         uuid_le uuid;
  24         int len;
  25         int need_reset = 0;
  26
  27         len = btrfs_item_size_nr(eb, slot);
  28         read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
  29                         min_t(int, len, (int)sizeof(*item)));
  30         if (len < sizeof(*item))
  31                 need_reset = 1;
  32         if (!need_reset && btrfs_root_generation(item)
  33                 != btrfs_root_generation_v2(item)) {
  34                 if (btrfs_root_generation_v2(item) != 0) {
  35                         btrfs_warn(eb->fs_info,
  36                                         "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
  37                 }
  38                 need_reset = 1;
  39         }
  40         if (need_reset) {
  41                 memset(&item->generation_v2, 0,
  42                         sizeof(*item) - offsetof(struct btrfs_root_item,
  43                                         generation_v2));
  44
  45                 uuid_le_gen(&uuid);
  46                 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
  47         }
  48 }
  49
  50 /*
  51  * btrfs_find_root - lookup the root by the key.
  52  * root: the root of the root tree
  53  * search_key: the key to search
  54  * path: the path we search
  55  * root_item: the root item of the tree we look for
  56  * root_key: the root key of the tree we look for
  57  *
  58  * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
  59  * of the search key, just lookup the root with the highest offset for a
  60  * given objectid.
  61  *
  62  * If we find something return 0, otherwise > 0, < 0 on error.
  63  */
  64 int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
  65                     struct btrfs_path *path, struct btrfs_root_item *root_item,
  66                     struct btrfs_key *root_key)
  67 {
  68         struct btrfs_key found_key;
  69         struct extent_buffer *l;
  70         int ret;
  71         int slot;
  72
  73         ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
  74         if (ret < 0)
  75                 return ret;
  76
  77         if (search_key->offset != -1ULL) {      /* the search key is exact */
  78                 if (ret > 0)
  79                         goto out;
  80         } else {
  81                 BUG_ON(ret == 0);               /* Logical error */
  82                 if (path->slots[0] == 0)
  83                         goto out;
  84                 path->slots[0]--;
  85                 ret = 0;
  86         }
  87
  88         l = path->nodes[0];
  89         slot = path->slots[0];
  90
  91         btrfs_item_key_to_cpu(l, &found_key, slot);
  92         if (found_key.objectid != search_key->objectid ||
  93             found_key.type != BTRFS_ROOT_ITEM_KEY) {
  94                 ret = 1;
  95                 goto out;
  96         }
  97
  98         if (root_item)
  99                 btrfs_read_root_item(l, slot, root_item);
 100         if (root_key)
 101                 memcpy(root_key, &found_key, sizeof(found_key));
 102 out:
 103         btrfs_release_path(path);
 104         return ret;
 105 }
 106
 107 void btrfs_set_root_node(struct btrfs_root_item *item,
 108                          struct extent_buffer *node)
 109 {
 110         btrfs_set_root_bytenr(item, node->start);
 111         btrfs_set_root_level(item, btrfs_header_level(node));
 112         btrfs_set_root_generation(item, btrfs_header_generation(node));
 113 }
 114
 115 /*
 116  * copy the data in 'item' into the btree
 117  */
 118 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 119                       *root, struct btrfs_key *key, struct btrfs_root_item
 120                       *item)
 121 {
 122         struct btrfs_fs_info *fs_info = root->fs_info;
 123         struct btrfs_path *path;
 124         struct extent_buffer *l;
 125         int ret;
 126         int slot;
 127         unsigned long ptr;
 128         u32 old_len;
 129
 130         path = btrfs_alloc_path();
 131         if (!path)
 132                 return -ENOMEM;
 133
 134         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 135         if (ret < 0) {
 136                 btrfs_abort_transaction(trans, ret);
 137                 goto out;
 138         }
 139
 140         if (ret != 0) {
 141                 btrfs_print_leaf(path->nodes[0]);
 142                 btrfs_crit(fs_info, "unable to update root key %llu %u %llu",
 143                            key->objectid, key->type, key->offset);
 144                 BUG_ON(1);
 145         }
 146
 147         l = path->nodes[0];
 148         slot = path->slots[0];
 149         ptr = btrfs_item_ptr_offset(l, slot);
 150         old_len = btrfs_item_size_nr(l, slot);
 151
 152         /*
 153          * If this is the first time we update the root item which originated
 154          * from an older kernel, we need to enlarge the item size to make room
 155          * for the added fields.
 156          */
 157         if (old_len < sizeof(*item)) {
 158                 btrfs_release_path(path);
 159                 ret = btrfs_search_slot(trans, root, key, path,
 160                                 -1, 1);
 161                 if (ret < 0) {
 162                         btrfs_abort_transaction(trans, ret);
 163                         goto out;
 164                 }
 165
 166                 ret = btrfs_del_item(trans, root, path);
 167                 if (ret < 0) {
 168                         btrfs_abort_transaction(trans, ret);
 169                         goto out;
 170                 }
 171                 btrfs_release_path(path);
 172                 ret = btrfs_insert_empty_item(trans, root, path,
 173                                 key, sizeof(*item));
 174                 if (ret < 0) {
 175                         btrfs_abort_transaction(trans, ret);
 176                         goto out;
 177                 }
 178                 l = path->nodes[0];
 179                 slot = path->slots[0];
 180                 ptr = btrfs_item_ptr_offset(l, slot);
 181         }
 182
 183         /*
 184          * Update generation_v2 so at the next mount we know the new root
 185          * fields are valid.
 186          */
 187         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 188
 189         write_extent_buffer(l, item, ptr, sizeof(*item));
 190         btrfs_mark_buffer_dirty(path->nodes[0]);
 191 out:
 192         btrfs_free_path(path);
 193         return ret;
 194 }
 195
 196 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 197                       const struct btrfs_key *key, struct btrfs_root_item *item)
 198 {
 199         /*
 200          * Make sure generation v1 and v2 match. See update_root for details.
 201          */
 202         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 203         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 204 }
 205
 206 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 207 {
 208         struct btrfs_root *tree_root = fs_info->tree_root;
 209         struct extent_buffer *leaf;
 210         struct btrfs_path *path;
 211         struct btrfs_key key;
 212         struct btrfs_key root_key;
 213         struct btrfs_root *root;
 214         int err = 0;
 215         int ret;
 216
 217         path = btrfs_alloc_path();
 218         if (!path)
 219                 return -ENOMEM;
 220
 221         key.objectid = BTRFS_ORPHAN_OBJECTID;
 222         key.type = BTRFS_ORPHAN_ITEM_KEY;
 223         key.offset = 0;
 224
 225         root_key.type = BTRFS_ROOT_ITEM_KEY;
 226         root_key.offset = (u64)-1;
 227
 228         while (1) {
 229                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 230                 if (ret < 0) {
 231                         err = ret;
 232                         break;
 233                 }
 234
 235                 leaf = path->nodes[0];
 236                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 237                         ret = btrfs_next_leaf(tree_root, path);
 238                         if (ret < 0)
 239                                 err = ret;
 240                         if (ret != 0)
 241                                 break;
 242                         leaf = path->nodes[0];
 243                 }
 244
 245                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 246                 btrfs_release_path(path);
 247
 248                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 249                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 250                         break;
 251
 252                 root_key.objectid = key.offset;
 253                 key.offset++;
 254
 255                 /*
 256                  * The root might have been inserted already, as before we look
 257                  * for orphan roots, log replay might have happened, which
 258                  * triggers a transaction commit and qgroup accounting, which
 259                  * in turn reads and inserts fs roots while doing backref
 260                  * walking.
 261                  */
 262                 root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
 263                 if (root) {
 264                         WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
 265                                           &root->state));
 266                         if (btrfs_root_refs(&root->root_item) == 0)
 267                                 btrfs_add_dead_root(root);
 268                         continue;
 269                 }
 270
 271                 root = btrfs_read_fs_root(tree_root, &root_key);
 272                 err = PTR_ERR_OR_ZERO(root);
 273                 if (err && err != -ENOENT) {
 274                         break;
 275                 } else if (err == -ENOENT) {
 276                         struct btrfs_trans_handle *trans;
 277
 278                         btrfs_release_path(path);
 279
 280                         trans = btrfs_join_transaction(tree_root);
 281                         if (IS_ERR(trans)) {
 282                                 err = PTR_ERR(trans);
 283                                 btrfs_handle_fs_error(fs_info, err,
 284                                             "Failed to start trans to delete orphan item");
 285                                 break;
 286                         }
 287                         err = btrfs_del_orphan_item(trans, tree_root,
 288                                                     root_key.objectid);
 289                         btrfs_end_transaction(trans);
 290                         if (err) {
 291                                 btrfs_handle_fs_error(fs_info, err,
 292                                             "Failed to delete root orphan item");
 293                                 break;
 294                         }
 295                         continue;
 296                 }
 297
 298                 err = btrfs_init_fs_root(root);
 299                 if (err) {
 300                         btrfs_free_fs_root(root);
 301                         break;
 302                 }
 303
 304                 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
 305
 306                 err = btrfs_insert_fs_root(fs_info, root);
 307                 if (err) {
 308                         BUG_ON(err == -EEXIST);
 309                         btrfs_free_fs_root(root);
 310                         break;
 311                 }
 312
 313                 if (btrfs_root_refs(&root->root_item) == 0)
 314                         btrfs_add_dead_root(root);
 315         }
 316
 317         btrfs_free_path(path);
 318         return err;
 319 }
 320
 321 /* drop the root item for 'key' from the tree root */
 322 int btrfs_del_root(struct btrfs_trans_handle *trans,
 323                    struct btrfs_fs_info *fs_info, const struct btrfs_key *key)
 324 {
 325         struct btrfs_root *root = fs_info->tree_root;
 326         struct btrfs_path *path;
 327         int ret;
 328
 329         path = btrfs_alloc_path();
 330         if (!path)
 331                 return -ENOMEM;
 332         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 333         if (ret < 0)
 334                 goto out;
 335
 336         BUG_ON(ret != 0);
 337
 338         ret = btrfs_del_item(trans, root, path);
 339 out:
 340         btrfs_free_path(path);
 341         return ret;
 342 }
 343
 344 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 345                        struct btrfs_fs_info *fs_info,
 346                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 347                        const char *name, int name_len)
 348
 349 {
 350         struct btrfs_root *tree_root = fs_info->tree_root;
 351         struct btrfs_path *path;
 352         struct btrfs_root_ref *ref;
 353         struct extent_buffer *leaf;
 354         struct btrfs_key key;
 355         unsigned long ptr;
 356         int err = 0;
 357         int ret;
 358
 359         path = btrfs_alloc_path();
 360         if (!path)
 361                 return -ENOMEM;
 362
 363         key.objectid = root_id;
 364         key.type = BTRFS_ROOT_BACKREF_KEY;
 365         key.offset = ref_id;
 366 again:
 367         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 368         BUG_ON(ret < 0);
 369         if (ret == 0) {
 370                 leaf = path->nodes[0];
 371                 ref = btrfs_item_ptr(leaf, path->slots[0],
 372                                      struct btrfs_root_ref);
 373
 374                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 375                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 376                 ptr = (unsigned long)(ref + 1);
 377                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 378                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 379
 380                 ret = btrfs_del_item(trans, tree_root, path);
 381                 if (ret) {
 382                         err = ret;
 383                         goto out;
 384                 }
 385         } else
 386                 err = -ENOENT;
 387
 388         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 389                 btrfs_release_path(path);
 390                 key.objectid = ref_id;
 391                 key.type = BTRFS_ROOT_REF_KEY;
 392                 key.offset = root_id;
 393                 goto again;
 394         }
 395
 396 out:
 397         btrfs_free_path(path);
 398         return err;
 399 }
 400
 401 /*
 402  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 403  * or BTRFS_ROOT_BACKREF_KEY.
 404  *
 405  * The dirid, sequence, name and name_len refer to the directory entry
 406  * that is referencing the root.
 407  *
 408  * For a forward ref, the root_id is the id of the tree referencing
 409  * the root and ref_id is the id of the subvol  or snapshot.
 410  *
 411  * For a back ref the root_id is the id of the subvol or snapshot and
 412  * ref_id is the id of the tree referencing it.
 413  *
 414  * Will return 0, -ENOMEM, or anything from the CoW path
 415  */
 416 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 417                        struct btrfs_fs_info *fs_info,
 418                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 419                        const char *name, int name_len)
 420 {
 421         struct btrfs_root *tree_root = fs_info->tree_root;
 422         struct btrfs_key key;
 423         int ret;
 424         struct btrfs_path *path;
 425         struct btrfs_root_ref *ref;
 426         struct extent_buffer *leaf;
 427         unsigned long ptr;
 428
 429         path = btrfs_alloc_path();
 430         if (!path)
 431                 return -ENOMEM;
 432
 433         key.objectid = root_id;
 434         key.type = BTRFS_ROOT_BACKREF_KEY;
 435         key.offset = ref_id;
 436 again:
 437         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 438                                       sizeof(*ref) + name_len);
 439         if (ret) {
 440                 btrfs_abort_transaction(trans, ret);
 441                 btrfs_free_path(path);
 442                 return ret;
 443         }
 444
 445         leaf = path->nodes[0];
 446         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 447         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 448         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 449         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 450         ptr = (unsigned long)(ref + 1);
 451         write_extent_buffer(leaf, name, ptr, name_len);
 452         btrfs_mark_buffer_dirty(leaf);
 453
 454         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 455                 btrfs_release_path(path);
 456                 key.objectid = ref_id;
 457                 key.type = BTRFS_ROOT_REF_KEY;
 458                 key.offset = root_id;
 459                 goto again;
 460         }
 461
 462         btrfs_free_path(path);
 463         return 0;
 464 }
 465
 466 /*
 467  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 468  * for subvolumes. To work around this problem, we steal a bit from
 469  * root_item->inode_item->flags, and use it to indicate if those fields
 470  * have been properly initialized.
 471  */
 472 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 473 {
 474         u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
 475
 476         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 477                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 478                 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
 479                 btrfs_set_root_flags(root_item, 0);
 480                 btrfs_set_root_limit(root_item, 0);
 481         }
 482 }
 483
 484 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 485                              struct btrfs_root *root)
 486 {
 487         struct btrfs_root_item *item = &root->root_item;
 488         struct timespec64 ct;
 489
 490         ktime_get_real_ts64(&ct);
 491         spin_lock(&root->root_item_lock);
 492         btrfs_set_root_ctransid(item, trans->transid);
 493         btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
 494         btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
 495         spin_unlock(&root->root_item_lock);
 496 }