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 reak key of the tree we look for 75 * 76 * If ->offset of 'seach_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_std_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_std_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 if (err) { 314 BUG_ON(err == -EEXIST); 315 btrfs_free_fs_root(root); 316 break; 317 } 318 319 if (btrfs_root_refs(&root->root_item) == 0) 320 btrfs_add_dead_root(root); 321 } 322 323 btrfs_free_path(path); 324 return err; 325 } 326 327 /* drop the root item for 'key' from 'root' */ 328 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root, 329 struct btrfs_key *key) 330 { 331 struct btrfs_path *path; 332 int ret; 333 334 path = btrfs_alloc_path(); 335 if (!path) 336 return -ENOMEM; 337 ret = btrfs_search_slot(trans, root, key, path, -1, 1); 338 if (ret < 0) 339 goto out; 340 341 BUG_ON(ret != 0); 342 343 ret = btrfs_del_item(trans, root, path); 344 out: 345 btrfs_free_path(path); 346 return ret; 347 } 348 349 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, 350 struct btrfs_root *tree_root, 351 u64 root_id, u64 ref_id, u64 dirid, u64 *sequence, 352 const char *name, int name_len) 353 354 { 355 struct btrfs_path *path; 356 struct btrfs_root_ref *ref; 357 struct extent_buffer *leaf; 358 struct btrfs_key key; 359 unsigned long ptr; 360 int err = 0; 361 int ret; 362 363 path = btrfs_alloc_path(); 364 if (!path) 365 return -ENOMEM; 366 367 key.objectid = root_id; 368 key.type = BTRFS_ROOT_BACKREF_KEY; 369 key.offset = ref_id; 370 again: 371 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1); 372 BUG_ON(ret < 0); 373 if (ret == 0) { 374 leaf = path->nodes[0]; 375 ref = btrfs_item_ptr(leaf, path->slots[0], 376 struct btrfs_root_ref); 377 378 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid); 379 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len); 380 ptr = (unsigned long)(ref + 1); 381 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len)); 382 *sequence = btrfs_root_ref_sequence(leaf, ref); 383 384 ret = btrfs_del_item(trans, tree_root, path); 385 if (ret) { 386 err = ret; 387 goto out; 388 } 389 } else 390 err = -ENOENT; 391 392 if (key.type == BTRFS_ROOT_BACKREF_KEY) { 393 btrfs_release_path(path); 394 key.objectid = ref_id; 395 key.type = BTRFS_ROOT_REF_KEY; 396 key.offset = root_id; 397 goto again; 398 } 399 400 out: 401 btrfs_free_path(path); 402 return err; 403 } 404 405 /* 406 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY 407 * or BTRFS_ROOT_BACKREF_KEY. 408 * 409 * The dirid, sequence, name and name_len refer to the directory entry 410 * that is referencing the root. 411 * 412 * For a forward ref, the root_id is the id of the tree referencing 413 * the root and ref_id is the id of the subvol or snapshot. 414 * 415 * For a back ref the root_id is the id of the subvol or snapshot and 416 * ref_id is the id of the tree referencing it. 417 * 418 * Will return 0, -ENOMEM, or anything from the CoW path 419 */ 420 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, 421 struct btrfs_root *tree_root, 422 u64 root_id, u64 ref_id, u64 dirid, u64 sequence, 423 const char *name, int name_len) 424 { 425 struct btrfs_key key; 426 int ret; 427 struct btrfs_path *path; 428 struct btrfs_root_ref *ref; 429 struct extent_buffer *leaf; 430 unsigned long ptr; 431 432 path = btrfs_alloc_path(); 433 if (!path) 434 return -ENOMEM; 435 436 key.objectid = root_id; 437 key.type = BTRFS_ROOT_BACKREF_KEY; 438 key.offset = ref_id; 439 again: 440 ret = btrfs_insert_empty_item(trans, tree_root, path, &key, 441 sizeof(*ref) + name_len); 442 if (ret) { 443 btrfs_abort_transaction(trans, tree_root, ret); 444 btrfs_free_path(path); 445 return ret; 446 } 447 448 leaf = path->nodes[0]; 449 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref); 450 btrfs_set_root_ref_dirid(leaf, ref, dirid); 451 btrfs_set_root_ref_sequence(leaf, ref, sequence); 452 btrfs_set_root_ref_name_len(leaf, ref, name_len); 453 ptr = (unsigned long)(ref + 1); 454 write_extent_buffer(leaf, name, ptr, name_len); 455 btrfs_mark_buffer_dirty(leaf); 456 457 if (key.type == BTRFS_ROOT_BACKREF_KEY) { 458 btrfs_release_path(path); 459 key.objectid = ref_id; 460 key.type = BTRFS_ROOT_REF_KEY; 461 key.offset = root_id; 462 goto again; 463 } 464 465 btrfs_free_path(path); 466 return 0; 467 } 468 469 /* 470 * Old btrfs forgets to init root_item->flags and root_item->byte_limit 471 * for subvolumes. To work around this problem, we steal a bit from 472 * root_item->inode_item->flags, and use it to indicate if those fields 473 * have been properly initialized. 474 */ 475 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item) 476 { 477 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode); 478 479 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) { 480 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT; 481 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags); 482 btrfs_set_root_flags(root_item, 0); 483 btrfs_set_root_limit(root_item, 0); 484 } 485 } 486 487 void btrfs_update_root_times(struct btrfs_trans_handle *trans, 488 struct btrfs_root *root) 489 { 490 struct btrfs_root_item *item = &root->root_item; 491 struct timespec ct = CURRENT_TIME; 492 493 spin_lock(&root->root_item_lock); 494 btrfs_set_root_ctransid(item, trans->transid); 495 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec); 496 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec); 497 spin_unlock(&root->root_item_lock); 498 } 499