fs/btrfs/root-tree.c

   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/uuid.h>
  20 #include "ctree.h"
  21 #include "transaction.h"
  22 #include "disk-io.h"
  23 #include "print-tree.h"
  24
  25 /*
  26  * Read a root item from the tree. In case we detect a root item smaller then
  27  * sizeof(root_item), we know it's an old version of the root structure and
  28  * initialize all new fields to zero. The same happens if we detect mismatching
  29  * generation numbers as then we know the root was once mounted with an older
  30  * kernel that was not aware of the root item structure change.
  31  */
  32 void btrfs_read_root_item(struct btrfs_root *root,
  33                          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                         printk(KERN_WARNING "btrfs: mismatching "
  49                                         "generation and generation_v2 "
  50                                         "found in root item. This root "
  51                                         "was probably mounted with an "
  52                                         "older kernel. Resetting all "
  53                                         "new fields.\n");
  54                 }
  55                 need_reset = 1;
  56         }
  57         if (need_reset) {
  58                 memset(&item->generation_v2, 0,
  59                         sizeof(*item) - offsetof(struct btrfs_root_item,
  60                                         generation_v2));
  61
  62                 uuid_le_gen(&uuid);
  63                 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
  64         }
  65 }
  66
  67 /*
  68  * lookup the root with the highest offset for a given objectid.  The key we do
  69  * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
  70  * on error.
  71  */
  72 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
  73                         struct btrfs_root_item *item, struct btrfs_key *key)
  74 {
  75         struct btrfs_path *path;
  76         struct btrfs_key search_key;
  77         struct btrfs_key found_key;
  78         struct extent_buffer *l;
  79         int ret;
  80         int slot;
  81
  82         search_key.objectid = objectid;
  83         search_key.type = BTRFS_ROOT_ITEM_KEY;
  84         search_key.offset = (u64)-1;
  85
  86         path = btrfs_alloc_path();
  87         if (!path)
  88                 return -ENOMEM;
  89         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  90         if (ret < 0)
  91                 goto out;
  92
  93         BUG_ON(ret == 0);
  94         if (path->slots[0] == 0) {
  95                 ret = 1;
  96                 goto out;
  97         }
  98         l = path->nodes[0];
  99         slot = path->slots[0] - 1;
 100         btrfs_item_key_to_cpu(l, &found_key, slot);
 101         if (found_key.objectid != objectid ||
 102             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 103                 ret = 1;
 104                 goto out;
 105         }
 106         if (item)
 107                 btrfs_read_root_item(root, l, slot, item);
 108         if (key)
 109                 memcpy(key, &found_key, sizeof(found_key));
 110
 111         ret = 0;
 112 out:
 113         btrfs_free_path(path);
 114         return ret;
 115 }
 116
 117 void btrfs_set_root_node(struct btrfs_root_item *item,
 118                          struct extent_buffer *node)
 119 {
 120         btrfs_set_root_bytenr(item, node->start);
 121         btrfs_set_root_level(item, btrfs_header_level(node));
 122         btrfs_set_root_generation(item, btrfs_header_generation(node));
 123 }
 124
 125 /*
 126  * copy the data in 'item' into the btree
 127  */
 128 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 129                       *root, struct btrfs_key *key, struct btrfs_root_item
 130                       *item)
 131 {
 132         struct btrfs_path *path;
 133         struct extent_buffer *l;
 134         int ret;
 135         int slot;
 136         unsigned long ptr;
 137         int old_len;
 138
 139         path = btrfs_alloc_path();
 140         if (!path)
 141                 return -ENOMEM;
 142
 143         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 144         if (ret < 0) {
 145                 btrfs_abort_transaction(trans, root, ret);
 146                 goto out;
 147         }
 148
 149         if (ret != 0) {
 150                 btrfs_print_leaf(root, path->nodes[0]);
 151                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 152                        (unsigned long long)key->objectid, key->type,
 153                        (unsigned long long)key->offset);
 154                 BUG_ON(1);
 155         }
 156
 157         l = path->nodes[0];
 158         slot = path->slots[0];
 159         ptr = btrfs_item_ptr_offset(l, slot);
 160         old_len = btrfs_item_size_nr(l, slot);
 161
 162         /*
 163          * If this is the first time we update the root item which originated
 164          * from an older kernel, we need to enlarge the item size to make room
 165          * for the added fields.
 166          */
 167         if (old_len < sizeof(*item)) {
 168                 btrfs_release_path(path);
 169                 ret = btrfs_search_slot(trans, root, key, path,
 170                                 -1, 1);
 171                 if (ret < 0) {
 172                         btrfs_abort_transaction(trans, root, ret);
 173                         goto out;
 174                 }
 175
 176                 ret = btrfs_del_item(trans, root, path);
 177                 if (ret < 0) {
 178                         btrfs_abort_transaction(trans, root, ret);
 179                         goto out;
 180                 }
 181                 btrfs_release_path(path);
 182                 ret = btrfs_insert_empty_item(trans, root, path,
 183                                 key, sizeof(*item));
 184                 if (ret < 0) {
 185                         btrfs_abort_transaction(trans, root, ret);
 186                         goto out;
 187                 }
 188                 l = path->nodes[0];
 189                 slot = path->slots[0];
 190                 ptr = btrfs_item_ptr_offset(l, slot);
 191         }
 192
 193         /*
 194          * Update generation_v2 so at the next mount we know the new root
 195          * fields are valid.
 196          */
 197         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 198
 199         write_extent_buffer(l, item, ptr, sizeof(*item));
 200         btrfs_mark_buffer_dirty(path->nodes[0]);
 201 out:
 202         btrfs_free_path(path);
 203         return ret;
 204 }
 205
 206 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 207                       struct btrfs_key *key, struct btrfs_root_item *item)
 208 {
 209         /*
 210          * Make sure generation v1 and v2 match. See update_root for details.
 211          */
 212         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 213         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 214 }
 215
 216 /*
 217  * at mount time we want to find all the old transaction snapshots that were in
 218  * the process of being deleted if we crashed.  This is any root item with an
 219  * offset lower than the latest root.  They need to be queued for deletion to
 220  * finish what was happening when we crashed.
 221  */
 222 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 223 {
 224         struct btrfs_root *dead_root;
 225         struct btrfs_root_item *ri;
 226         struct btrfs_key key;
 227         struct btrfs_key found_key;
 228         struct btrfs_path *path;
 229         int ret;
 230         u32 nritems;
 231         struct extent_buffer *leaf;
 232         int slot;
 233
 234         key.objectid = objectid;
 235         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 236         key.offset = 0;
 237         path = btrfs_alloc_path();
 238         if (!path)
 239                 return -ENOMEM;
 240
 241 again:
 242         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 243         if (ret < 0)
 244                 goto err;
 245         while (1) {
 246                 leaf = path->nodes[0];
 247                 nritems = btrfs_header_nritems(leaf);
 248                 slot = path->slots[0];
 249                 if (slot >= nritems) {
 250                         ret = btrfs_next_leaf(root, path);
 251                         if (ret)
 252                                 break;
 253                         leaf = path->nodes[0];
 254                         nritems = btrfs_header_nritems(leaf);
 255                         slot = path->slots[0];
 256                 }
 257                 btrfs_item_key_to_cpu(leaf, &key, slot);
 258                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 259                         goto next;
 260
 261                 if (key.objectid < objectid)
 262                         goto next;
 263
 264                 if (key.objectid > objectid)
 265                         break;
 266
 267                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 268                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 269                         goto next;
 270
 271                 memcpy(&found_key, &key, sizeof(key));
 272                 key.offset++;
 273                 btrfs_release_path(path);
 274                 dead_root =
 275                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 276                                                     &found_key);
 277                 if (IS_ERR(dead_root)) {
 278                         ret = PTR_ERR(dead_root);
 279                         goto err;
 280                 }
 281
 282                 ret = btrfs_add_dead_root(dead_root);
 283                 if (ret)
 284                         goto err;
 285                 goto again;
 286 next:
 287                 slot++;
 288                 path->slots[0]++;
 289         }
 290         ret = 0;
 291 err:
 292         btrfs_free_path(path);
 293         return ret;
 294 }
 295
 296 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 297 {
 298         struct extent_buffer *leaf;
 299         struct btrfs_path *path;
 300         struct btrfs_key key;
 301         struct btrfs_key root_key;
 302         struct btrfs_root *root;
 303         int err = 0;
 304         int ret;
 305
 306         path = btrfs_alloc_path();
 307         if (!path)
 308                 return -ENOMEM;
 309
 310         key.objectid = BTRFS_ORPHAN_OBJECTID;
 311         key.type = BTRFS_ORPHAN_ITEM_KEY;
 312         key.offset = 0;
 313
 314         root_key.type = BTRFS_ROOT_ITEM_KEY;
 315         root_key.offset = (u64)-1;
 316
 317         while (1) {
 318                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 319                 if (ret < 0) {
 320                         err = ret;
 321                         break;
 322                 }
 323
 324                 leaf = path->nodes[0];
 325                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 326                         ret = btrfs_next_leaf(tree_root, path);
 327                         if (ret < 0)
 328                                 err = ret;
 329                         if (ret != 0)
 330                                 break;
 331                         leaf = path->nodes[0];
 332                 }
 333
 334                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 335                 btrfs_release_path(path);
 336
 337                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 338                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 339                         break;
 340
 341                 root_key.objectid = key.offset;
 342                 key.offset++;
 343
 344                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 345                                                   &root_key);
 346                 if (!IS_ERR(root))
 347                         continue;
 348
 349                 ret = PTR_ERR(root);
 350                 if (ret != -ENOENT) {
 351                         err = ret;
 352                         break;
 353                 }
 354
 355                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 356                 if (ret) {
 357                         err = ret;
 358                         break;
 359                 }
 360         }
 361
 362         btrfs_free_path(path);
 363         return err;
 364 }
 365
 366 /* drop the root item for 'key' from 'root' */
 367 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 368                    struct btrfs_key *key)
 369 {
 370         struct btrfs_path *path;
 371         int ret;
 372         struct btrfs_root_item *ri;
 373         struct extent_buffer *leaf;
 374
 375         path = btrfs_alloc_path();
 376         if (!path)
 377                 return -ENOMEM;
 378         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 379         if (ret < 0)
 380                 goto out;
 381
 382         BUG_ON(ret != 0);
 383         leaf = path->nodes[0];
 384         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 385
 386         ret = btrfs_del_item(trans, root, path);
 387 out:
 388         btrfs_free_path(path);
 389         return ret;
 390 }
 391
 392 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 393                        struct btrfs_root *tree_root,
 394                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 395                        const char *name, int name_len)
 396
 397 {
 398         struct btrfs_path *path;
 399         struct btrfs_root_ref *ref;
 400         struct extent_buffer *leaf;
 401         struct btrfs_key key;
 402         unsigned long ptr;
 403         int err = 0;
 404         int ret;
 405
 406         path = btrfs_alloc_path();
 407         if (!path)
 408                 return -ENOMEM;
 409
 410         key.objectid = root_id;
 411         key.type = BTRFS_ROOT_BACKREF_KEY;
 412         key.offset = ref_id;
 413 again:
 414         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 415         BUG_ON(ret < 0);
 416         if (ret == 0) {
 417                 leaf = path->nodes[0];
 418                 ref = btrfs_item_ptr(leaf, path->slots[0],
 419                                      struct btrfs_root_ref);
 420
 421                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 422                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 423                 ptr = (unsigned long)(ref + 1);
 424                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 425                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 426
 427                 ret = btrfs_del_item(trans, tree_root, path);
 428                 if (ret) {
 429                         err = ret;
 430                         goto out;
 431                 }
 432         } else
 433                 err = -ENOENT;
 434
 435         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 436                 btrfs_release_path(path);
 437                 key.objectid = ref_id;
 438                 key.type = BTRFS_ROOT_REF_KEY;
 439                 key.offset = root_id;
 440                 goto again;
 441         }
 442
 443 out:
 444         btrfs_free_path(path);
 445         return err;
 446 }
 447
 448 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 449                    struct btrfs_path *path,
 450                    u64 root_id, u64 ref_id)
 451 {
 452         struct btrfs_key key;
 453         int ret;
 454
 455         key.objectid = root_id;
 456         key.type = BTRFS_ROOT_REF_KEY;
 457         key.offset = ref_id;
 458
 459         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 460         return ret;
 461 }
 462
 463 /*
 464  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 465  * or BTRFS_ROOT_BACKREF_KEY.
 466  *
 467  * The dirid, sequence, name and name_len refer to the directory entry
 468  * that is referencing the root.
 469  *
 470  * For a forward ref, the root_id is the id of the tree referencing
 471  * the root and ref_id is the id of the subvol  or snapshot.
 472  *
 473  * For a back ref the root_id is the id of the subvol or snapshot and
 474  * ref_id is the id of the tree referencing it.
 475  *
 476  * Will return 0, -ENOMEM, or anything from the CoW path
 477  */
 478 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 479                        struct btrfs_root *tree_root,
 480                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 481                        const char *name, int name_len)
 482 {
 483         struct btrfs_key key;
 484         int ret;
 485         struct btrfs_path *path;
 486         struct btrfs_root_ref *ref;
 487         struct extent_buffer *leaf;
 488         unsigned long ptr;
 489
 490         path = btrfs_alloc_path();
 491         if (!path)
 492                 return -ENOMEM;
 493
 494         key.objectid = root_id;
 495         key.type = BTRFS_ROOT_BACKREF_KEY;
 496         key.offset = ref_id;
 497 again:
 498         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 499                                       sizeof(*ref) + name_len);
 500         if (ret) {
 501                 btrfs_abort_transaction(trans, tree_root, ret);
 502                 btrfs_free_path(path);
 503                 return ret;
 504         }
 505
 506         leaf = path->nodes[0];
 507         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 508         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 509         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 510         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 511         ptr = (unsigned long)(ref + 1);
 512         write_extent_buffer(leaf, name, ptr, name_len);
 513         btrfs_mark_buffer_dirty(leaf);
 514
 515         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 516                 btrfs_release_path(path);
 517                 key.objectid = ref_id;
 518                 key.type = BTRFS_ROOT_REF_KEY;
 519                 key.offset = root_id;
 520                 goto again;
 521         }
 522
 523         btrfs_free_path(path);
 524         return 0;
 525 }
 526
 527 /*
 528  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 529  * for subvolumes. To work around this problem, we steal a bit from
 530  * root_item->inode_item->flags, and use it to indicate if those fields
 531  * have been properly initialized.
 532  */
 533 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 534 {
 535         u64 inode_flags = le64_to_cpu(root_item->inode.flags);
 536
 537         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 538                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 539                 root_item->inode.flags = cpu_to_le64(inode_flags);
 540                 root_item->flags = 0;
 541                 root_item->byte_limit = 0;
 542         }
 543 }
 544
 545 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 546                              struct btrfs_root *root)
 547 {
 548         struct btrfs_root_item *item = &root->root_item;
 549         struct timespec ct = CURRENT_TIME;
 550
 551         spin_lock(&root->root_item_lock);
 552         item->ctransid = cpu_to_le64(trans->transid);
 553         item->ctime.sec = cpu_to_le64(ct.tv_sec);
 554         item->ctime.nsec = cpu_to_le32(ct.tv_nsec);
 555         spin_unlock(&root->root_item_lock);
 556 }