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         if (!path)
  92                 return -ENOMEM;
  93         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  94         if (ret < 0)
  95                 goto out;
  96
  97         BUG_ON(ret == 0);
  98         if (path->slots[0] == 0) {
  99                 ret = 1;
 100                 goto out;
 101         }
 102         l = path->nodes[0];
 103         slot = path->slots[0] - 1;
 104         btrfs_item_key_to_cpu(l, &found_key, slot);
 105         if (found_key.objectid != objectid ||
 106             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 107                 ret = 1;
 108                 goto out;
 109         }
 110         if (item)
 111                 read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
 112                                    sizeof(*item));
 113         if (key)
 114                 memcpy(key, &found_key, sizeof(found_key));
 115         ret = 0;
 116 out:
 117         btrfs_free_path(path);
 118         return ret;
 119 }
 120
 121 int btrfs_set_root_node(struct btrfs_root_item *item,
 122                         struct extent_buffer *node)
 123 {
 124         btrfs_set_root_bytenr(item, node->start);
 125         btrfs_set_root_level(item, btrfs_header_level(node));
 126         btrfs_set_root_generation(item, btrfs_header_generation(node));
 127         return 0;
 128 }
 129
 130 /*
 131  * copy the data in 'item' into the btree
 132  */
 133 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 134                       *root, struct btrfs_key *key, struct btrfs_root_item
 135                       *item)
 136 {
 137         struct btrfs_path *path;
 138         struct extent_buffer *l;
 139         int ret;
 140         int slot;
 141         unsigned long ptr;
 142
 143         path = btrfs_alloc_path();
 144         BUG_ON(!path);
 145         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 146         if (ret < 0)
 147                 goto out;
 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         write_extent_buffer(l, item, ptr, sizeof(*item));
 161         btrfs_mark_buffer_dirty(path->nodes[0]);
 162 out:
 163         btrfs_free_path(path);
 164         return ret;
 165 }
 166
 167 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 168                       *root, struct btrfs_key *key, struct btrfs_root_item
 169                       *item)
 170 {
 171         int ret;
 172         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 173         return ret;
 174 }
 175
 176 /*
 177  * at mount time we want to find all the old transaction snapshots that were in
 178  * the process of being deleted if we crashed.  This is any root item with an
 179  * offset lower than the latest root.  They need to be queued for deletion to
 180  * finish what was happening when we crashed.
 181  */
 182 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 183 {
 184         struct btrfs_root *dead_root;
 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                 btrfs_item_key_to_cpu(leaf, &key, slot);
 218                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 219                         goto next;
 220
 221                 if (key.objectid < objectid)
 222                         goto next;
 223
 224                 if (key.objectid > objectid)
 225                         break;
 226
 227                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 228                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 229                         goto next;
 230
 231                 memcpy(&found_key, &key, sizeof(key));
 232                 key.offset++;
 233                 btrfs_release_path(root, path);
 234                 dead_root =
 235                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 236                                                     &found_key);
 237                 if (IS_ERR(dead_root)) {
 238                         ret = PTR_ERR(dead_root);
 239                         goto err;
 240                 }
 241
 242                 ret = btrfs_add_dead_root(dead_root);
 243                 if (ret)
 244                         goto err;
 245                 goto again;
 246 next:
 247                 slot++;
 248                 path->slots[0]++;
 249         }
 250         ret = 0;
 251 err:
 252         btrfs_free_path(path);
 253         return ret;
 254 }
 255
 256 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 257 {
 258         struct extent_buffer *leaf;
 259         struct btrfs_path *path;
 260         struct btrfs_key key;
 261         struct btrfs_key root_key;
 262         struct btrfs_root *root;
 263         int err = 0;
 264         int ret;
 265
 266         path = btrfs_alloc_path();
 267         if (!path)
 268                 return -ENOMEM;
 269
 270         key.objectid = BTRFS_ORPHAN_OBJECTID;
 271         key.type = BTRFS_ORPHAN_ITEM_KEY;
 272         key.offset = 0;
 273
 274         root_key.type = BTRFS_ROOT_ITEM_KEY;
 275         root_key.offset = (u64)-1;
 276
 277         while (1) {
 278                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 279                 if (ret < 0) {
 280                         err = ret;
 281                         break;
 282                 }
 283
 284                 leaf = path->nodes[0];
 285                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 286                         ret = btrfs_next_leaf(tree_root, path);
 287                         if (ret < 0)
 288                                 err = ret;
 289                         if (ret != 0)
 290                                 break;
 291                         leaf = path->nodes[0];
 292                 }
 293
 294                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 295                 btrfs_release_path(tree_root, path);
 296
 297                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 298                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 299                         break;
 300
 301                 root_key.objectid = key.offset;
 302                 key.offset++;
 303
 304                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 305                                                   &root_key);
 306                 if (!IS_ERR(root))
 307                         continue;
 308
 309                 ret = PTR_ERR(root);
 310                 if (ret != -ENOENT) {
 311                         err = ret;
 312                         break;
 313                 }
 314
 315                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 316                 if (ret) {
 317                         err = ret;
 318                         break;
 319                 }
 320         }
 321
 322         btrfs_free_path(path);
 323         return err;
 324 }
 325
 326 /* drop the root item for 'key' from 'root' */
 327 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 328                    struct btrfs_key *key)
 329 {
 330         struct btrfs_path *path;
 331         int ret;
 332         struct btrfs_root_item *ri;
 333         struct extent_buffer *leaf;
 334
 335         path = btrfs_alloc_path();
 336         if (!path)
 337                 return -ENOMEM;
 338         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 339         if (ret < 0)
 340                 goto out;
 341
 342         BUG_ON(ret != 0);
 343         leaf = path->nodes[0];
 344         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 345
 346         ret = btrfs_del_item(trans, root, path);
 347 out:
 348         btrfs_free_path(path);
 349         return ret;
 350 }
 351
 352 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 353                        struct btrfs_root *tree_root,
 354                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 355                        const char *name, int name_len)
 356
 357 {
 358         struct btrfs_path *path;
 359         struct btrfs_root_ref *ref;
 360         struct extent_buffer *leaf;
 361         struct btrfs_key key;
 362         unsigned long ptr;
 363         int err = 0;
 364         int ret;
 365
 366         path = btrfs_alloc_path();
 367         if (!path)
 368                 return -ENOMEM;
 369
 370         key.objectid = root_id;
 371         key.type = BTRFS_ROOT_BACKREF_KEY;
 372         key.offset = ref_id;
 373 again:
 374         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 375         BUG_ON(ret < 0);
 376         if (ret == 0) {
 377                 leaf = path->nodes[0];
 378                 ref = btrfs_item_ptr(leaf, path->slots[0],
 379                                      struct btrfs_root_ref);
 380
 381                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 382                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 383                 ptr = (unsigned long)(ref + 1);
 384                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 385                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 386
 387                 ret = btrfs_del_item(trans, tree_root, path);
 388                 BUG_ON(ret);
 389         } else
 390                 err = -ENOENT;
 391
 392         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 393                 btrfs_release_path(tree_root, path);
 394                 key.objectid = ref_id;
 395                 key.type = BTRFS_ROOT_REF_KEY;
 396                 key.offset = root_id;
 397                 goto again;
 398         }
 399
 400         btrfs_free_path(path);
 401         return err;
 402 }
 403
 404 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 405                    struct btrfs_path *path,
 406                    u64 root_id, u64 ref_id)
 407 {
 408         struct btrfs_key key;
 409         int ret;
 410
 411         key.objectid = root_id;
 412         key.type = BTRFS_ROOT_REF_KEY;
 413         key.offset = ref_id;
 414
 415         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 416         return ret;
 417 }
 418
 419 /*
 420  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 421  * or BTRFS_ROOT_BACKREF_KEY.
 422  *
 423  * The dirid, sequence, name and name_len refer to the directory entry
 424  * that is referencing the root.
 425  *
 426  * For a forward ref, the root_id is the id of the tree referencing
 427  * the root and ref_id is the id of the subvol  or snapshot.
 428  *
 429  * For a back ref the root_id is the id of the subvol or snapshot and
 430  * ref_id is the id of the tree referencing it.
 431  */
 432 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 433                        struct btrfs_root *tree_root,
 434                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 435                        const char *name, int name_len)
 436 {
 437         struct btrfs_key key;
 438         int ret;
 439         struct btrfs_path *path;
 440         struct btrfs_root_ref *ref;
 441         struct extent_buffer *leaf;
 442         unsigned long ptr;
 443
 444         path = btrfs_alloc_path();
 445         if (!path)
 446                 return -ENOMEM;
 447
 448         key.objectid = root_id;
 449         key.type = BTRFS_ROOT_BACKREF_KEY;
 450         key.offset = ref_id;
 451 again:
 452         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 453                                       sizeof(*ref) + name_len);
 454         BUG_ON(ret);
 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(tree_root, 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 = le64_to_cpu(root_item->inode.flags);
 486
 487         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 488                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 489                 root_item->inode.flags = cpu_to_le64(inode_flags);
 490                 root_item->flags = 0;
 491                 root_item->byte_limit = 0;
 492         }
 493 }