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_release_path(root, path);
 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_item *item;
 186         struct btrfs_root_item *ri;
 187         struct btrfs_key key;
 188         struct btrfs_key found_key;
 189         struct btrfs_path *path;
 190         int ret;
 191         u32 nritems;
 192         struct extent_buffer *leaf;
 193         int slot;
 194
 195         key.objectid = objectid;
 196         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 197         key.offset = 0;
 198         path = btrfs_alloc_path();
 199         if (!path)
 200                 return -ENOMEM;
 201
 202 again:
 203         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 204         if (ret < 0)
 205                 goto err;
 206         while (1) {
 207                 leaf = path->nodes[0];
 208                 nritems = btrfs_header_nritems(leaf);
 209                 slot = path->slots[0];
 210                 if (slot >= nritems) {
 211                         ret = btrfs_next_leaf(root, path);
 212                         if (ret)
 213                                 break;
 214                         leaf = path->nodes[0];
 215                         nritems = btrfs_header_nritems(leaf);
 216                         slot = path->slots[0];
 217                 }
 218                 item = btrfs_item_nr(leaf, slot);
 219                 btrfs_item_key_to_cpu(leaf, &key, slot);
 220                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 221                         goto next;
 222
 223                 if (key.objectid < objectid)
 224                         goto next;
 225
 226                 if (key.objectid > objectid)
 227                         break;
 228
 229                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 230                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 231                         goto next;
 232
 233                 memcpy(&found_key, &key, sizeof(key));
 234                 key.offset++;
 235                 btrfs_release_path(root, path);
 236                 dead_root =
 237                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 238                                                     &found_key);
 239                 if (IS_ERR(dead_root)) {
 240                         ret = PTR_ERR(dead_root);
 241                         goto err;
 242                 }
 243
 244                 ret = btrfs_add_dead_root(dead_root);
 245                 if (ret)
 246                         goto err;
 247                 goto again;
 248 next:
 249                 slot++;
 250                 path->slots[0]++;
 251         }
 252         ret = 0;
 253 err:
 254         btrfs_free_path(path);
 255         return ret;
 256 }
 257
 258 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 259 {
 260         struct extent_buffer *leaf;
 261         struct btrfs_path *path;
 262         struct btrfs_key key;
 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         while (1) {
 275                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 276                 if (ret < 0) {
 277                         err = ret;
 278                         break;
 279                 }
 280
 281                 leaf = path->nodes[0];
 282                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 283                         ret = btrfs_next_leaf(tree_root, path);
 284                         if (ret < 0)
 285                                 err = ret;
 286                         if (ret != 0)
 287                                 break;
 288                         leaf = path->nodes[0];
 289                 }
 290
 291                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 292                 btrfs_release_path(tree_root, path);
 293
 294                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 295                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 296                         break;
 297
 298                 ret = btrfs_find_dead_roots(tree_root, key.offset);
 299                 if (ret) {
 300                         err = ret;
 301                         break;
 302                 }
 303
 304                 key.offset++;
 305         }
 306
 307         btrfs_free_path(path);
 308         return err;
 309 }
 310
 311 /* drop the root item for 'key' from 'root' */
 312 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 313                    struct btrfs_key *key)
 314 {
 315         struct btrfs_path *path;
 316         int ret;
 317         u32 refs;
 318         struct btrfs_root_item *ri;
 319         struct extent_buffer *leaf;
 320
 321         path = btrfs_alloc_path();
 322         BUG_ON(!path);
 323         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 324         if (ret < 0)
 325                 goto out;
 326
 327         BUG_ON(ret != 0);
 328         leaf = path->nodes[0];
 329         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 330
 331         refs = btrfs_disk_root_refs(leaf, ri);
 332         BUG_ON(refs != 0);
 333         ret = btrfs_del_item(trans, root, path);
 334 out:
 335         btrfs_release_path(root, path);
 336         btrfs_free_path(path);
 337         return ret;
 338 }
 339
 340 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 341                        struct btrfs_root *tree_root,
 342                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 343                        const char *name, int name_len)
 344
 345 {
 346         struct btrfs_path *path;
 347         struct btrfs_root_ref *ref;
 348         struct extent_buffer *leaf;
 349         struct btrfs_key key;
 350         unsigned long ptr;
 351         int err = 0;
 352         int ret;
 353
 354         path = btrfs_alloc_path();
 355         if (!path)
 356                 return -ENOMEM;
 357
 358         key.objectid = root_id;
 359         key.type = BTRFS_ROOT_BACKREF_KEY;
 360         key.offset = ref_id;
 361 again:
 362         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 363         BUG_ON(ret < 0);
 364         if (ret == 0) {
 365                 leaf = path->nodes[0];
 366                 ref = btrfs_item_ptr(leaf, path->slots[0],
 367                                      struct btrfs_root_ref);
 368
 369                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 370                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 371                 ptr = (unsigned long)(ref + 1);
 372                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 373                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 374
 375                 ret = btrfs_del_item(trans, tree_root, path);
 376                 BUG_ON(ret);
 377         } else
 378                 err = -ENOENT;
 379
 380         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 381                 btrfs_release_path(tree_root, path);
 382                 key.objectid = ref_id;
 383                 key.type = BTRFS_ROOT_REF_KEY;
 384                 key.offset = root_id;
 385                 goto again;
 386         }
 387
 388         btrfs_free_path(path);
 389         return err;
 390 }
 391
 392 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 393                    struct btrfs_path *path,
 394                    u64 root_id, u64 ref_id)
 395 {
 396         struct btrfs_key key;
 397         int ret;
 398
 399         key.objectid = root_id;
 400         key.type = BTRFS_ROOT_REF_KEY;
 401         key.offset = ref_id;
 402
 403         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 404         return ret;
 405 }
 406
 407 /*
 408  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 409  * or BTRFS_ROOT_BACKREF_KEY.
 410  *
 411  * The dirid, sequence, name and name_len refer to the directory entry
 412  * that is referencing the root.
 413  *
 414  * For a forward ref, the root_id is the id of the tree referencing
 415  * the root and ref_id is the id of the subvol  or snapshot.
 416  *
 417  * For a back ref the root_id is the id of the subvol or snapshot and
 418  * ref_id is the id of the tree referencing it.
 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         BUG_ON(ret);
 443
 444         leaf = path->nodes[0];
 445         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 446         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 447         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 448         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 449         ptr = (unsigned long)(ref + 1);
 450         write_extent_buffer(leaf, name, ptr, name_len);
 451         btrfs_mark_buffer_dirty(leaf);
 452
 453         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 454                 btrfs_release_path(tree_root, path);
 455                 key.objectid = ref_id;
 456                 key.type = BTRFS_ROOT_REF_KEY;
 457                 key.offset = root_id;
 458                 goto again;
 459         }
 460
 461         btrfs_free_path(path);
 462         return 0;
 463 }