1 /* 2 * Copyright (C) 2007 Oracle. All rights reserved. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public 6 * License v2 as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11 * General Public License for more details. 12 * 13 * You should have received a copy of the GNU General Public 14 * License along with this program; if not, write to the 15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330, 16 * Boston, MA 021110-1307, USA. 17 */ 18 19 #include <linux/err.h> 20 #include <linux/uuid.h> 21 #include "ctree.h" 22 #include "transaction.h" 23 #include "disk-io.h" 24 #include "print-tree.h" 25 26 /* 27 * Read a root item from the tree. In case we detect a root item smaller then 28 * sizeof(root_item), we know it's an old version of the root structure and 29 * initialize all new fields to zero. The same happens if we detect mismatching 30 * generation numbers as then we know the root was once mounted with an older 31 * kernel that was not aware of the root item structure change. 32 */ 33 static void btrfs_read_root_item(struct extent_buffer *eb, int slot, 34 struct btrfs_root_item *item) 35 { 36 uuid_le uuid; 37 int len; 38 int need_reset = 0; 39 40 len = btrfs_item_size_nr(eb, slot); 41 read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot), 42 min_t(int, len, (int)sizeof(*item))); 43 if (len < sizeof(*item)) 44 need_reset = 1; 45 if (!need_reset && btrfs_root_generation(item) 46 != btrfs_root_generation_v2(item)) { 47 if (btrfs_root_generation_v2(item) != 0) { 48 btrfs_warn(eb->fs_info, 49 "mismatching " 50 "generation and generation_v2 " 51 "found in root item. This root " 52 "was probably mounted with an " 53 "older kernel. Resetting all " 54 "new fields."); 55 } 56 need_reset = 1; 57 } 58 if (need_reset) { 59 memset(&item->generation_v2, 0, 60 sizeof(*item) - offsetof(struct btrfs_root_item, 61 generation_v2)); 62 63 uuid_le_gen(&uuid); 64 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE); 65 } 66 } 67 68 /* 69 * btrfs_find_root - lookup the root by the key. 70 * root: the root of the root tree 71 * search_key: the key to search 72 * path: the path we search 73 * root_item: the root item of the tree we look for 74 * root_key: the root key of the tree we look for 75 * 76 * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset 77 * of the search key, just lookup the root with the highest offset for a 78 * given objectid. 79 * 80 * If we find something return 0, otherwise > 0, < 0 on error. 81 */ 82 int btrfs_find_root(struct btrfs_root *root, struct btrfs_key *search_key, 83 struct btrfs_path *path, struct btrfs_root_item *root_item, 84 struct btrfs_key *root_key) 85 { 86 struct btrfs_key found_key; 87 struct extent_buffer *l; 88 int ret; 89 int slot; 90 91 ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0); 92 if (ret < 0) 93 return ret; 94 95 if (search_key->offset != -1ULL) { /* the search key is exact */ 96 if (ret > 0) 97 goto out; 98 } else { 99 BUG_ON(ret == 0); /* Logical error */ 100 if (path->slots[0] == 0) 101 goto out; 102 path->slots[0]--; 103 ret = 0; 104 } 105 106 l = path->nodes[0]; 107 slot = path->slots[0]; 108 109 btrfs_item_key_to_cpu(l, &found_key, slot); 110 if (found_key.objectid != search_key->objectid || 111 found_key.type != BTRFS_ROOT_ITEM_KEY) { 112 ret = 1; 113 goto out; 114 } 115 116 if (root_item) 117 btrfs_read_root_item(l, slot, root_item); 118 if (root_key) 119 memcpy(root_key, &found_key, sizeof(found_key)); 120 out: 121 btrfs_release_path(path); 122 return ret; 123 } 124 125 void btrfs_set_root_node(struct btrfs_root_item *item, 126 struct extent_buffer *node) 127 { 128 btrfs_set_root_bytenr(item, node->start); 129 btrfs_set_root_level(item, btrfs_header_level(node)); 130 btrfs_set_root_generation(item, btrfs_header_generation(node)); 131 } 132 133 /* 134 * copy the data in 'item' into the btree 135 */ 136 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root 137 *root, struct btrfs_key *key, struct btrfs_root_item 138 *item) 139 { 140 struct btrfs_path *path; 141 struct extent_buffer *l; 142 int ret; 143 int slot; 144 unsigned long ptr; 145 u32 old_len; 146 147 path = btrfs_alloc_path(); 148 if (!path) 149 return -ENOMEM; 150 151 ret = btrfs_search_slot(trans, root, key, path, 0, 1); 152 if (ret < 0) { 153 btrfs_abort_transaction(trans, root, ret); 154 goto out; 155 } 156 157 if (ret != 0) { 158 btrfs_print_leaf(root, path->nodes[0]); 159 btrfs_crit(root->fs_info, "unable to update root key %llu %u %llu", 160 key->objectid, key->type, key->offset); 161 BUG_ON(1); 162 } 163 164 l = path->nodes[0]; 165 slot = path->slots[0]; 166 ptr = btrfs_item_ptr_offset(l, slot); 167 old_len = btrfs_item_size_nr(l, slot); 168 169 /* 170 * If this is the first time we update the root item which originated 171 * from an older kernel, we need to enlarge the item size to make room 172 * for the added fields. 173 */ 174 if (old_len < sizeof(*item)) { 175 btrfs_release_path(path); 176 ret = btrfs_search_slot(trans, root, key, path, 177 -1, 1); 178 if (ret < 0) { 179 btrfs_abort_transaction(trans, root, ret); 180 goto out; 181 } 182 183 ret = btrfs_del_item(trans, root, path); 184 if (ret < 0) { 185 btrfs_abort_transaction(trans, root, ret); 186 goto out; 187 } 188 btrfs_release_path(path); 189 ret = btrfs_insert_empty_item(trans, root, path, 190 key, sizeof(*item)); 191 if (ret < 0) { 192 btrfs_abort_transaction(trans, root, ret); 193 goto out; 194 } 195 l = path->nodes[0]; 196 slot = path->slots[0]; 197 ptr = btrfs_item_ptr_offset(l, slot); 198 } 199 200 /* 201 * Update generation_v2 so at the next mount we know the new root 202 * fields are valid. 203 */ 204 btrfs_set_root_generation_v2(item, btrfs_root_generation(item)); 205 206 write_extent_buffer(l, item, ptr, sizeof(*item)); 207 btrfs_mark_buffer_dirty(path->nodes[0]); 208 out: 209 btrfs_free_path(path); 210 return ret; 211 } 212 213 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, 214 struct btrfs_key *key, struct btrfs_root_item *item) 215 { 216 /* 217 * Make sure generation v1 and v2 match. See update_root for details. 218 */ 219 btrfs_set_root_generation_v2(item, btrfs_root_generation(item)); 220 return btrfs_insert_item(trans, root, key, item, sizeof(*item)); 221 } 222 223 int btrfs_find_orphan_roots(struct btrfs_root *tree_root) 224 { 225 struct extent_buffer *leaf; 226 struct btrfs_path *path; 227 struct btrfs_key key; 228 struct btrfs_key root_key; 229 struct btrfs_root *root; 230 int err = 0; 231 int ret; 232 bool can_recover = true; 233 234 if (tree_root->fs_info->sb->s_flags & MS_RDONLY) 235 can_recover = false; 236 237 path = btrfs_alloc_path(); 238 if (!path) 239 return -ENOMEM; 240 241 key.objectid = BTRFS_ORPHAN_OBJECTID; 242 key.type = BTRFS_ORPHAN_ITEM_KEY; 243 key.offset = 0; 244 245 root_key.type = BTRFS_ROOT_ITEM_KEY; 246 root_key.offset = (u64)-1; 247 248 while (1) { 249 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0); 250 if (ret < 0) { 251 err = ret; 252 break; 253 } 254 255 leaf = path->nodes[0]; 256 if (path->slots[0] >= btrfs_header_nritems(leaf)) { 257 ret = btrfs_next_leaf(tree_root, path); 258 if (ret < 0) 259 err = ret; 260 if (ret != 0) 261 break; 262 leaf = path->nodes[0]; 263 } 264 265 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]); 266 btrfs_release_path(path); 267 268 if (key.objectid != BTRFS_ORPHAN_OBJECTID || 269 key.type != BTRFS_ORPHAN_ITEM_KEY) 270 break; 271 272 root_key.objectid = key.offset; 273 key.offset++; 274 275 root = btrfs_read_fs_root(tree_root, &root_key); 276 err = PTR_ERR_OR_ZERO(root); 277 if (err && err != -ENOENT) { 278 break; 279 } else if (err == -ENOENT) { 280 struct btrfs_trans_handle *trans; 281 282 btrfs_release_path(path); 283 284 trans = btrfs_join_transaction(tree_root); 285 if (IS_ERR(trans)) { 286 err = PTR_ERR(trans); 287 btrfs_handle_fs_error(tree_root->fs_info, err, 288 "Failed to start trans to delete " 289 "orphan item"); 290 break; 291 } 292 err = btrfs_del_orphan_item(trans, tree_root, 293 root_key.objectid); 294 btrfs_end_transaction(trans, tree_root); 295 if (err) { 296 btrfs_handle_fs_error(tree_root->fs_info, err, 297 "Failed to delete root orphan " 298 "item"); 299 break; 300 } 301 continue; 302 } 303 304 err = btrfs_init_fs_root(root); 305 if (err) { 306 btrfs_free_fs_root(root); 307 break; 308 } 309 310 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state); 311 312 err = btrfs_insert_fs_root(root->fs_info, root); 313 /* 314 * The root might have been inserted already, as before we look 315 * for orphan roots, log replay might have happened, which 316 * triggers a transaction commit and qgroup accounting, which 317 * in turn reads and inserts fs roots while doing backref 318 * walking. 319 */ 320 if (err == -EEXIST) 321 err = 0; 322 if (err) { 323 btrfs_free_fs_root(root); 324 break; 325 } 326 327 if (btrfs_root_refs(&root->root_item) == 0) 328 btrfs_add_dead_root(root); 329 } 330 331 btrfs_free_path(path); 332 return err; 333 } 334 335 /* drop the root item for 'key' from 'root' */ 336 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, 337 struct btrfs_key *key) 338 { 339 struct btrfs_path *path; 340 int ret; 341 342 path = btrfs_alloc_path(); 343 if (!path) 344 return -ENOMEM; 345 ret = btrfs_search_slot(trans, root, key, path, -1, 1); 346 if (ret < 0) 347 goto out; 348 349 BUG_ON(ret != 0); 350 351 ret = btrfs_del_item(trans, root, path); 352 out: 353 btrfs_free_path(path); 354 return ret; 355 } 356 357 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, 358 struct btrfs_root *tree_root, 359 u64 root_id, u64 ref_id, u64 dirid, u64 *sequence, 360 const char *name, int name_len) 361 362 { 363 struct btrfs_path *path; 364 struct btrfs_root_ref *ref; 365 struct extent_buffer *leaf; 366 struct btrfs_key key; 367 unsigned long ptr; 368 int err = 0; 369 int ret; 370 371 path = btrfs_alloc_path(); 372 if (!path) 373 return -ENOMEM; 374 375 key.objectid = root_id; 376 key.type = BTRFS_ROOT_BACKREF_KEY; 377 key.offset = ref_id; 378 again: 379 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1); 380 BUG_ON(ret < 0); 381 if (ret == 0) { 382 leaf = path->nodes[0]; 383 ref = btrfs_item_ptr(leaf, path->slots[0], 384 struct btrfs_root_ref); 385 386 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid); 387 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len); 388 ptr = (unsigned long)(ref + 1); 389 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len)); 390 *sequence = btrfs_root_ref_sequence(leaf, ref); 391 392 ret = btrfs_del_item(trans, tree_root, path); 393 if (ret) { 394 err = ret; 395 goto out; 396 } 397 } else 398 err = -ENOENT; 399 400 if (key.type == BTRFS_ROOT_BACKREF_KEY) { 401 btrfs_release_path(path); 402 key.objectid = ref_id; 403 key.type = BTRFS_ROOT_REF_KEY; 404 key.offset = root_id; 405 goto again; 406 } 407 408 out: 409 btrfs_free_path(path); 410 return err; 411 } 412 413 /* 414 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY 415 * or BTRFS_ROOT_BACKREF_KEY. 416 * 417 * The dirid, sequence, name and name_len refer to the directory entry 418 * that is referencing the root. 419 * 420 * For a forward ref, the root_id is the id of the tree referencing 421 * the root and ref_id is the id of the subvol or snapshot. 422 * 423 * For a back ref the root_id is the id of the subvol or snapshot and 424 * ref_id is the id of the tree referencing it. 425 * 426 * Will return 0, -ENOMEM, or anything from the CoW path 427 */ 428 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, 429 struct btrfs_root *tree_root, 430 u64 root_id, u64 ref_id, u64 dirid, u64 sequence, 431 const char *name, int name_len) 432 { 433 struct btrfs_key key; 434 int ret; 435 struct btrfs_path *path; 436 struct btrfs_root_ref *ref; 437 struct extent_buffer *leaf; 438 unsigned long ptr; 439 440 path = btrfs_alloc_path(); 441 if (!path) 442 return -ENOMEM; 443 444 key.objectid = root_id; 445 key.type = BTRFS_ROOT_BACKREF_KEY; 446 key.offset = ref_id; 447 again: 448 ret = btrfs_insert_empty_item(trans, tree_root, path, &key, 449 sizeof(*ref) + name_len); 450 if (ret) { 451 btrfs_abort_transaction(trans, tree_root, ret); 452 btrfs_free_path(path); 453 return ret; 454 } 455 456 leaf = path->nodes[0]; 457 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref); 458 btrfs_set_root_ref_dirid(leaf, ref, dirid); 459 btrfs_set_root_ref_sequence(leaf, ref, sequence); 460 btrfs_set_root_ref_name_len(leaf, ref, name_len); 461 ptr = (unsigned long)(ref + 1); 462 write_extent_buffer(leaf, name, ptr, name_len); 463 btrfs_mark_buffer_dirty(leaf); 464 465 if (key.type == BTRFS_ROOT_BACKREF_KEY) { 466 btrfs_release_path(path); 467 key.objectid = ref_id; 468 key.type = BTRFS_ROOT_REF_KEY; 469 key.offset = root_id; 470 goto again; 471 } 472 473 btrfs_free_path(path); 474 return 0; 475 } 476 477 /* 478 * Old btrfs forgets to init root_item->flags and root_item->byte_limit 479 * for subvolumes. To work around this problem, we steal a bit from 480 * root_item->inode_item->flags, and use it to indicate if those fields 481 * have been properly initialized. 482 */ 483 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item) 484 { 485 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode); 486 487 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) { 488 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT; 489 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags); 490 btrfs_set_root_flags(root_item, 0); 491 btrfs_set_root_limit(root_item, 0); 492 } 493 } 494 495 void btrfs_update_root_times(struct btrfs_trans_handle *trans, 496 struct btrfs_root *root) 497 { 498 struct btrfs_root_item *item = &root->root_item; 499 struct timespec ct = current_fs_time(root->fs_info->sb); 500 501 spin_lock(&root->root_item_lock); 502 btrfs_set_root_ctransid(item, trans->transid); 503 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec); 504 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec); 505 spin_unlock(&root->root_item_lock); 506 } 507