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 "ctree.h"
  20 #include "transaction.h"
  21 #include "disk-io.h"
  22 #include "print-tree.h"
  23
  24 /*
  25  *  search forward for a root, starting with objectid 'search_start'
  26  *  if a root key is found, the objectid we find is filled into 'found_objectid'
  27  *  and 0 is returned.  < 0 is returned on error, 1 if there is nothing
  28  *  left in the tree.
  29  */
  30 int btrfs_search_root(struct btrfs_root *root, u64 search_start,
  31                       u64 *found_objectid)
  32 {
  33         struct btrfs_path *path;
  34         struct btrfs_key search_key;
  35         int ret;
  36
  37         root = root->fs_info->tree_root;
  38         search_key.objectid = search_start;
  39         search_key.type = (u8)-1;
  40         search_key.offset = (u64)-1;
  41
  42         path = btrfs_alloc_path();
  43         BUG_ON(!path);
  44 again:
  45         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  46         if (ret < 0)
  47                 goto out;
  48         if (ret == 0) {
  49                 ret = 1;
  50                 goto out;
  51         }
  52         if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
  53                 ret = btrfs_next_leaf(root, path);
  54                 if (ret)
  55                         goto out;
  56         }
  57         btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
  58         if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
  59                 search_key.offset++;
  60                 btrfs_release_path(root, path);
  61                 goto again;
  62         }
  63         ret = 0;
  64         *found_objectid = search_key.objectid;
  65
  66 out:
  67         btrfs_free_path(path);
  68         return ret;
  69 }
  70
  71 /*
  72  * lookup the root with the highest offset for a given objectid.  The key we do
  73  * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
  74  * on error.
  75  */
  76 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
  77                         struct btrfs_root_item *item, struct btrfs_key *key)
  78 {
  79         struct btrfs_path *path;
  80         struct btrfs_key search_key;
  81         struct btrfs_key found_key;
  82         struct extent_buffer *l;
  83         int ret;
  84         int slot;
  85
  86         search_key.objectid = objectid;
  87         search_key.type = BTRFS_ROOT_ITEM_KEY;
  88         search_key.offset = (u64)-1;
  89
  90         path = btrfs_alloc_path();
  91         BUG_ON(!path);
  92         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  93         if (ret < 0)
  94                 goto out;
  95
  96         BUG_ON(ret == 0);
  97         if (path->slots[0] == 0) {
  98                 ret = 1;
  99                 goto out;
 100         }
 101         l = path->nodes[0];
 102         slot = path->slots[0] - 1;
 103         btrfs_item_key_to_cpu(l, &found_key, slot);
 104         if (found_key.objectid != objectid ||
 105             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 106                 ret = 1;
 107                 goto out;
 108         }
 109         if (item)
 110                 read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
 111                                    sizeof(*item));
 112         if (key)
 113                 memcpy(key, &found_key, sizeof(found_key));
 114         ret = 0;
 115 out:
 116         btrfs_free_path(path);
 117         return ret;
 118 }
 119
 120 int btrfs_set_root_node(struct btrfs_root_item *item,
 121                         struct extent_buffer *node)
 122 {
 123         btrfs_set_root_bytenr(item, node->start);
 124         btrfs_set_root_level(item, btrfs_header_level(node));
 125         btrfs_set_root_generation(item, btrfs_header_generation(node));
 126         return 0;
 127 }
 128
 129 /*
 130  * copy the data in 'item' into the btree
 131  */
 132 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 133                       *root, struct btrfs_key *key, struct btrfs_root_item
 134                       *item)
 135 {
 136         struct btrfs_path *path;
 137         struct extent_buffer *l;
 138         int ret;
 139         int slot;
 140         unsigned long ptr;
 141
 142         path = btrfs_alloc_path();
 143         BUG_ON(!path);
 144         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 145         if (ret < 0)
 146                 goto out;
 147
 148         if (ret != 0) {
 149                 btrfs_print_leaf(root, path->nodes[0]);
 150                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 151                        (unsigned long long)key->objectid, key->type,
 152                        (unsigned long long)key->offset);
 153                 BUG_ON(1);
 154         }
 155
 156         l = path->nodes[0];
 157         slot = path->slots[0];
 158         ptr = btrfs_item_ptr_offset(l, slot);
 159         write_extent_buffer(l, item, ptr, sizeof(*item));
 160         btrfs_mark_buffer_dirty(path->nodes[0]);
 161 out:
 162         btrfs_free_path(path);
 163         return ret;
 164 }
 165
 166 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 167                       *root, struct btrfs_key *key, struct btrfs_root_item
 168                       *item)
 169 {
 170         int ret;
 171         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 172         return ret;
 173 }
 174
 175 /*
 176  * at mount time we want to find all the old transaction snapshots that were in
 177  * the process of being deleted if we crashed.  This is any root item with an
 178  * offset lower than the latest root.  They need to be queued for deletion to
 179  * finish what was happening when we crashed.
 180  */
 181 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 182 {
 183         struct btrfs_root *dead_root;
 184         struct btrfs_item *item;
 185         struct btrfs_root_item *ri;
 186         struct btrfs_key key;
 187         struct btrfs_key found_key;
 188         struct btrfs_path *path;
 189         int ret;
 190         u32 nritems;
 191         struct extent_buffer *leaf;
 192         int slot;
 193
 194         key.objectid = objectid;
 195         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 196         key.offset = 0;
 197         path = btrfs_alloc_path();
 198         if (!path)
 199                 return -ENOMEM;
 200
 201 again:
 202         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 203         if (ret < 0)
 204                 goto err;
 205         while (1) {
 206                 leaf = path->nodes[0];
 207                 nritems = btrfs_header_nritems(leaf);
 208                 slot = path->slots[0];
 209                 if (slot >= nritems) {
 210                         ret = btrfs_next_leaf(root, path);
 211                         if (ret)
 212                                 break;
 213                         leaf = path->nodes[0];
 214                         nritems = btrfs_header_nritems(leaf);
 215                         slot = path->slots[0];
 216                 }
 217                 item = btrfs_item_nr(leaf, slot);
 218                 btrfs_item_key_to_cpu(leaf, &key, slot);
 219                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 220                         goto next;
 221
 222                 if (key.objectid < objectid)
 223                         goto next;
 224
 225                 if (key.objectid > objectid)
 226                         break;
 227
 228                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 229                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 230                         goto next;
 231
 232                 memcpy(&found_key, &key, sizeof(key));
 233                 key.offset++;
 234                 btrfs_release_path(root, path);
 235                 dead_root =
 236                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 237                                                     &found_key);
 238                 if (IS_ERR(dead_root)) {
 239                         ret = PTR_ERR(dead_root);
 240                         goto err;
 241                 }
 242
 243                 ret = btrfs_add_dead_root(dead_root);
 244                 if (ret)
 245                         goto err;
 246                 goto again;
 247 next:
 248                 slot++;
 249                 path->slots[0]++;
 250         }
 251         ret = 0;
 252 err:
 253         btrfs_free_path(path);
 254         return ret;
 255 }
 256
 257 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 258 {
 259         struct extent_buffer *leaf;
 260         struct btrfs_path *path;
 261         struct btrfs_key key;
 262         struct btrfs_key root_key;
 263         struct btrfs_root *root;
 264         int err = 0;
 265         int ret;
 266
 267         path = btrfs_alloc_path();
 268         if (!path)
 269                 return -ENOMEM;
 270
 271         key.objectid = BTRFS_ORPHAN_OBJECTID;
 272         key.type = BTRFS_ORPHAN_ITEM_KEY;
 273         key.offset = 0;
 274
 275         root_key.type = BTRFS_ROOT_ITEM_KEY;
 276         root_key.offset = (u64)-1;
 277
 278         while (1) {
 279                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 280                 if (ret < 0) {
 281                         err = ret;
 282                         break;
 283                 }
 284
 285                 leaf = path->nodes[0];
 286                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 287                         ret = btrfs_next_leaf(tree_root, path);
 288                         if (ret < 0)
 289                                 err = ret;
 290                         if (ret != 0)
 291                                 break;
 292                         leaf = path->nodes[0];
 293                 }
 294
 295                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 296                 btrfs_release_path(tree_root, path);
 297
 298                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 299                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 300                         break;
 301
 302                 root_key.objectid = key.offset;
 303                 key.offset++;
 304
 305                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 306                                                   &root_key);
 307                 if (!IS_ERR(root))
 308                         continue;
 309
 310                 ret = PTR_ERR(root);
 311                 if (ret != -ENOENT) {
 312                         err = ret;
 313                         break;
 314                 }
 315
 316                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 317                 if (ret) {
 318                         err = ret;
 319                         break;
 320                 }
 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         u32 refs;
 334         struct btrfs_root_item *ri;
 335         struct extent_buffer *leaf;
 336
 337         path = btrfs_alloc_path();
 338         BUG_ON(!path);
 339         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 340         if (ret < 0)
 341                 goto out;
 342
 343         BUG_ON(ret != 0);
 344         leaf = path->nodes[0];
 345         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 346
 347         refs = btrfs_disk_root_refs(leaf, ri);
 348         BUG_ON(refs != 0);
 349         ret = btrfs_del_item(trans, root, path);
 350 out:
 351         btrfs_free_path(path);
 352         return ret;
 353 }
 354
 355 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 356                        struct btrfs_root *tree_root,
 357                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 358                        const char *name, int name_len)
 359
 360 {
 361         struct btrfs_path *path;
 362         struct btrfs_root_ref *ref;
 363         struct extent_buffer *leaf;
 364         struct btrfs_key key;
 365         unsigned long ptr;
 366         int err = 0;
 367         int ret;
 368
 369         path = btrfs_alloc_path();
 370         if (!path)
 371                 return -ENOMEM;
 372
 373         key.objectid = root_id;
 374         key.type = BTRFS_ROOT_BACKREF_KEY;
 375         key.offset = ref_id;
 376 again:
 377         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 378         BUG_ON(ret < 0);
 379         if (ret == 0) {
 380                 leaf = path->nodes[0];
 381                 ref = btrfs_item_ptr(leaf, path->slots[0],
 382                                      struct btrfs_root_ref);
 383
 384                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 385                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 386                 ptr = (unsigned long)(ref + 1);
 387                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 388                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 389
 390                 ret = btrfs_del_item(trans, tree_root, path);
 391                 BUG_ON(ret);
 392         } else
 393                 err = -ENOENT;
 394
 395         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 396                 btrfs_release_path(tree_root, path);
 397                 key.objectid = ref_id;
 398                 key.type = BTRFS_ROOT_REF_KEY;
 399                 key.offset = root_id;
 400                 goto again;
 401         }
 402
 403         btrfs_free_path(path);
 404         return err;
 405 }
 406
 407 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 408                    struct btrfs_path *path,
 409                    u64 root_id, u64 ref_id)
 410 {
 411         struct btrfs_key key;
 412         int ret;
 413
 414         key.objectid = root_id;
 415         key.type = BTRFS_ROOT_REF_KEY;
 416         key.offset = ref_id;
 417
 418         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 419         return ret;
 420 }
 421
 422 /*
 423  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 424  * or BTRFS_ROOT_BACKREF_KEY.
 425  *
 426  * The dirid, sequence, name and name_len refer to the directory entry
 427  * that is referencing the root.
 428  *
 429  * For a forward ref, the root_id is the id of the tree referencing
 430  * the root and ref_id is the id of the subvol  or snapshot.
 431  *
 432  * For a back ref the root_id is the id of the subvol or snapshot and
 433  * ref_id is the id of the tree referencing it.
 434  */
 435 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 436                        struct btrfs_root *tree_root,
 437                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 438                        const char *name, int name_len)
 439 {
 440         struct btrfs_key key;
 441         int ret;
 442         struct btrfs_path *path;
 443         struct btrfs_root_ref *ref;
 444         struct extent_buffer *leaf;
 445         unsigned long ptr;
 446
 447         path = btrfs_alloc_path();
 448         if (!path)
 449                 return -ENOMEM;
 450
 451         key.objectid = root_id;
 452         key.type = BTRFS_ROOT_BACKREF_KEY;
 453         key.offset = ref_id;
 454 again:
 455         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 456                                       sizeof(*ref) + name_len);
 457         BUG_ON(ret);
 458
 459         leaf = path->nodes[0];
 460         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 461         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 462         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 463         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 464         ptr = (unsigned long)(ref + 1);
 465         write_extent_buffer(leaf, name, ptr, name_len);
 466         btrfs_mark_buffer_dirty(leaf);
 467
 468         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 469                 btrfs_release_path(tree_root, path);
 470                 key.objectid = ref_id;
 471                 key.type = BTRFS_ROOT_REF_KEY;
 472                 key.offset = root_id;
 473                 goto again;
 474         }
 475
 476         btrfs_free_path(path);
 477         return 0;
 478 }