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                 goto out_abort;
 146
 147         if (ret != 0) {
 148                 btrfs_print_leaf(root, path->nodes[0]);
 149                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 150                        (unsigned long long)key->objectid, key->type,
 151                        (unsigned long long)key->offset);
 152                 BUG_ON(1);
 153         }
 154
 155         l = path->nodes[0];
 156         slot = path->slots[0];
 157         ptr = btrfs_item_ptr_offset(l, slot);
 158         old_len = btrfs_item_size_nr(l, slot);
 159
 160         /*
 161          * If this is the first time we update the root item which originated
 162          * from an older kernel, we need to enlarge the item size to make room
 163          * for the added fields.
 164          */
 165         if (old_len < sizeof(*item)) {
 166                 btrfs_release_path(path);
 167                 ret = btrfs_search_slot(trans, root, key, path,
 168                                 -1, 1);
 169                 if (ret < 0)
 170                         goto out_abort;
 171                 ret = btrfs_del_item(trans, root, path);
 172                 if (ret < 0)
 173                         goto out_abort;
 174                 btrfs_release_path(path);
 175                 ret = btrfs_insert_empty_item(trans, root, path,
 176                                 key, sizeof(*item));
 177                 if (ret < 0)
 178                         goto out_abort;
 179                 l = path->nodes[0];
 180                 slot = path->slots[0];
 181                 ptr = btrfs_item_ptr_offset(l, slot);
 182         }
 183
 184         /*
 185          * Update generation_v2 so at the next mount we know the new root
 186          * fields are valid.
 187          */
 188         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 189
 190         write_extent_buffer(l, item, ptr, sizeof(*item));
 191         btrfs_mark_buffer_dirty(path->nodes[0]);
 192 out:
 193         btrfs_free_path(path);
 194         return ret;
 195
 196 out_abort:
 197         btrfs_abort_transaction(trans, root, ret);
 198         goto out;
 199 }
 200
 201 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 202                       struct btrfs_key *key, struct btrfs_root_item *item)
 203 {
 204         /*
 205          * Make sure generation v1 and v2 match. See update_root for details.
 206          */
 207         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 208         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 209 }
 210
 211 /*
 212  * at mount time we want to find all the old transaction snapshots that were in
 213  * the process of being deleted if we crashed.  This is any root item with an
 214  * offset lower than the latest root.  They need to be queued for deletion to
 215  * finish what was happening when we crashed.
 216  */
 217 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 218 {
 219         struct btrfs_root *dead_root;
 220         struct btrfs_root_item *ri;
 221         struct btrfs_key key;
 222         struct btrfs_key found_key;
 223         struct btrfs_path *path;
 224         int ret;
 225         u32 nritems;
 226         struct extent_buffer *leaf;
 227         int slot;
 228
 229         key.objectid = objectid;
 230         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 231         key.offset = 0;
 232         path = btrfs_alloc_path();
 233         if (!path)
 234                 return -ENOMEM;
 235
 236 again:
 237         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 238         if (ret < 0)
 239                 goto err;
 240         while (1) {
 241                 leaf = path->nodes[0];
 242                 nritems = btrfs_header_nritems(leaf);
 243                 slot = path->slots[0];
 244                 if (slot >= nritems) {
 245                         ret = btrfs_next_leaf(root, path);
 246                         if (ret)
 247                                 break;
 248                         leaf = path->nodes[0];
 249                         nritems = btrfs_header_nritems(leaf);
 250                         slot = path->slots[0];
 251                 }
 252                 btrfs_item_key_to_cpu(leaf, &key, slot);
 253                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 254                         goto next;
 255
 256                 if (key.objectid < objectid)
 257                         goto next;
 258
 259                 if (key.objectid > objectid)
 260                         break;
 261
 262                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 263                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 264                         goto next;
 265
 266                 memcpy(&found_key, &key, sizeof(key));
 267                 key.offset++;
 268                 btrfs_release_path(path);
 269                 dead_root =
 270                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 271                                                     &found_key);
 272                 if (IS_ERR(dead_root)) {
 273                         ret = PTR_ERR(dead_root);
 274                         goto err;
 275                 }
 276
 277                 ret = btrfs_add_dead_root(dead_root);
 278                 if (ret)
 279                         goto err;
 280                 goto again;
 281 next:
 282                 slot++;
 283                 path->slots[0]++;
 284         }
 285         ret = 0;
 286 err:
 287         btrfs_free_path(path);
 288         return ret;
 289 }
 290
 291 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 292 {
 293         struct extent_buffer *leaf;
 294         struct btrfs_path *path;
 295         struct btrfs_key key;
 296         struct btrfs_key root_key;
 297         struct btrfs_root *root;
 298         int err = 0;
 299         int ret;
 300
 301         path = btrfs_alloc_path();
 302         if (!path)
 303                 return -ENOMEM;
 304
 305         key.objectid = BTRFS_ORPHAN_OBJECTID;
 306         key.type = BTRFS_ORPHAN_ITEM_KEY;
 307         key.offset = 0;
 308
 309         root_key.type = BTRFS_ROOT_ITEM_KEY;
 310         root_key.offset = (u64)-1;
 311
 312         while (1) {
 313                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 314                 if (ret < 0) {
 315                         err = ret;
 316                         break;
 317                 }
 318
 319                 leaf = path->nodes[0];
 320                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 321                         ret = btrfs_next_leaf(tree_root, path);
 322                         if (ret < 0)
 323                                 err = ret;
 324                         if (ret != 0)
 325                                 break;
 326                         leaf = path->nodes[0];
 327                 }
 328
 329                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 330                 btrfs_release_path(path);
 331
 332                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 333                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 334                         break;
 335
 336                 root_key.objectid = key.offset;
 337                 key.offset++;
 338
 339                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 340                                                   &root_key);
 341                 if (!IS_ERR(root))
 342                         continue;
 343
 344                 ret = PTR_ERR(root);
 345                 if (ret != -ENOENT) {
 346                         err = ret;
 347                         break;
 348                 }
 349
 350                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 351                 if (ret) {
 352                         err = ret;
 353                         break;
 354                 }
 355         }
 356
 357         btrfs_free_path(path);
 358         return err;
 359 }
 360
 361 /* drop the root item for 'key' from 'root' */
 362 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 363                    struct btrfs_key *key)
 364 {
 365         struct btrfs_path *path;
 366         int ret;
 367         struct btrfs_root_item *ri;
 368         struct extent_buffer *leaf;
 369
 370         path = btrfs_alloc_path();
 371         if (!path)
 372                 return -ENOMEM;
 373         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 374         if (ret < 0)
 375                 goto out;
 376
 377         BUG_ON(ret != 0);
 378         leaf = path->nodes[0];
 379         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 380
 381         ret = btrfs_del_item(trans, root, path);
 382 out:
 383         btrfs_free_path(path);
 384         return ret;
 385 }
 386
 387 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 388                        struct btrfs_root *tree_root,
 389                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 390                        const char *name, int name_len)
 391
 392 {
 393         struct btrfs_path *path;
 394         struct btrfs_root_ref *ref;
 395         struct extent_buffer *leaf;
 396         struct btrfs_key key;
 397         unsigned long ptr;
 398         int err = 0;
 399         int ret;
 400
 401         path = btrfs_alloc_path();
 402         if (!path)
 403                 return -ENOMEM;
 404
 405         key.objectid = root_id;
 406         key.type = BTRFS_ROOT_BACKREF_KEY;
 407         key.offset = ref_id;
 408 again:
 409         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 410         BUG_ON(ret < 0);
 411         if (ret == 0) {
 412                 leaf = path->nodes[0];
 413                 ref = btrfs_item_ptr(leaf, path->slots[0],
 414                                      struct btrfs_root_ref);
 415
 416                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 417                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 418                 ptr = (unsigned long)(ref + 1);
 419                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 420                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 421
 422                 ret = btrfs_del_item(trans, tree_root, path);
 423                 if (ret) {
 424                         err = ret;
 425                         goto out;
 426                 }
 427         } else
 428                 err = -ENOENT;
 429
 430         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 431                 btrfs_release_path(path);
 432                 key.objectid = ref_id;
 433                 key.type = BTRFS_ROOT_REF_KEY;
 434                 key.offset = root_id;
 435                 goto again;
 436         }
 437
 438 out:
 439         btrfs_free_path(path);
 440         return err;
 441 }
 442
 443 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 444                    struct btrfs_path *path,
 445                    u64 root_id, u64 ref_id)
 446 {
 447         struct btrfs_key key;
 448         int ret;
 449
 450         key.objectid = root_id;
 451         key.type = BTRFS_ROOT_REF_KEY;
 452         key.offset = ref_id;
 453
 454         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 455         return ret;
 456 }
 457
 458 /*
 459  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 460  * or BTRFS_ROOT_BACKREF_KEY.
 461  *
 462  * The dirid, sequence, name and name_len refer to the directory entry
 463  * that is referencing the root.
 464  *
 465  * For a forward ref, the root_id is the id of the tree referencing
 466  * the root and ref_id is the id of the subvol  or snapshot.
 467  *
 468  * For a back ref the root_id is the id of the subvol or snapshot and
 469  * ref_id is the id of the tree referencing it.
 470  *
 471  * Will return 0, -ENOMEM, or anything from the CoW path
 472  */
 473 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 474                        struct btrfs_root *tree_root,
 475                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 476                        const char *name, int name_len)
 477 {
 478         struct btrfs_key key;
 479         int ret;
 480         struct btrfs_path *path;
 481         struct btrfs_root_ref *ref;
 482         struct extent_buffer *leaf;
 483         unsigned long ptr;
 484
 485         path = btrfs_alloc_path();
 486         if (!path)
 487                 return -ENOMEM;
 488
 489         key.objectid = root_id;
 490         key.type = BTRFS_ROOT_BACKREF_KEY;
 491         key.offset = ref_id;
 492 again:
 493         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 494                                       sizeof(*ref) + name_len);
 495         if (ret) {
 496                 btrfs_abort_transaction(trans, tree_root, ret);
 497                 btrfs_free_path(path);
 498                 return ret;
 499         }
 500
 501         leaf = path->nodes[0];
 502         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 503         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 504         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 505         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 506         ptr = (unsigned long)(ref + 1);
 507         write_extent_buffer(leaf, name, ptr, name_len);
 508         btrfs_mark_buffer_dirty(leaf);
 509
 510         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 511                 btrfs_release_path(path);
 512                 key.objectid = ref_id;
 513                 key.type = BTRFS_ROOT_REF_KEY;
 514                 key.offset = root_id;
 515                 goto again;
 516         }
 517
 518         btrfs_free_path(path);
 519         return 0;
 520 }
 521
 522 /*
 523  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 524  * for subvolumes. To work around this problem, we steal a bit from
 525  * root_item->inode_item->flags, and use it to indicate if those fields
 526  * have been properly initialized.
 527  */
 528 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 529 {
 530         u64 inode_flags = le64_to_cpu(root_item->inode.flags);
 531
 532         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 533                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 534                 root_item->inode.flags = cpu_to_le64(inode_flags);
 535                 root_item->flags = 0;
 536                 root_item->byte_limit = 0;
 537         }
 538 }
 539
 540 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 541                              struct btrfs_root *root)
 542 {
 543         struct btrfs_root_item *item = &root->root_item;
 544         struct timespec ct = CURRENT_TIME;
 545
 546         spin_lock(&root->root_times_lock);
 547         item->ctransid = cpu_to_le64(trans->transid);
 548         item->ctime.sec = cpu_to_le64(ct.tv_sec);
 549         item->ctime.nsec = cpu_to_le32(ct.tv_nsec);
 550         spin_unlock(&root->root_times_lock);
 551 }