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_root_item *ri;
 185         struct btrfs_key key;
 186         struct btrfs_key found_key;
 187         struct btrfs_path *path;
 188         int ret;
 189         u32 nritems;
 190         struct extent_buffer *leaf;
 191         int slot;
 192
 193         key.objectid = objectid;
 194         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 195         key.offset = 0;
 196         path = btrfs_alloc_path();
 197         if (!path)
 198                 return -ENOMEM;
 199
 200 again:
 201         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 202         if (ret < 0)
 203                 goto err;
 204         while (1) {
 205                 leaf = path->nodes[0];
 206                 nritems = btrfs_header_nritems(leaf);
 207                 slot = path->slots[0];
 208                 if (slot >= nritems) {
 209                         ret = btrfs_next_leaf(root, path);
 210                         if (ret)
 211                                 break;
 212                         leaf = path->nodes[0];
 213                         nritems = btrfs_header_nritems(leaf);
 214                         slot = path->slots[0];
 215                 }
 216                 btrfs_item_key_to_cpu(leaf, &key, slot);
 217                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 218                         goto next;
 219
 220                 if (key.objectid < objectid)
 221                         goto next;
 222
 223                 if (key.objectid > objectid)
 224                         break;
 225
 226                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 227                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 228                         goto next;
 229
 230                 memcpy(&found_key, &key, sizeof(key));
 231                 key.offset++;
 232                 btrfs_release_path(root, path);
 233                 dead_root =
 234                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 235                                                     &found_key);
 236                 if (IS_ERR(dead_root)) {
 237                         ret = PTR_ERR(dead_root);
 238                         goto err;
 239                 }
 240
 241                 ret = btrfs_add_dead_root(dead_root);
 242                 if (ret)
 243                         goto err;
 244                 goto again;
 245 next:
 246                 slot++;
 247                 path->slots[0]++;
 248         }
 249         ret = 0;
 250 err:
 251         btrfs_free_path(path);
 252         return ret;
 253 }
 254
 255 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 256 {
 257         struct extent_buffer *leaf;
 258         struct btrfs_path *path;
 259         struct btrfs_key key;
 260         struct btrfs_key root_key;
 261         struct btrfs_root *root;
 262         int err = 0;
 263         int ret;
 264
 265         path = btrfs_alloc_path();
 266         if (!path)
 267                 return -ENOMEM;
 268
 269         key.objectid = BTRFS_ORPHAN_OBJECTID;
 270         key.type = BTRFS_ORPHAN_ITEM_KEY;
 271         key.offset = 0;
 272
 273         root_key.type = BTRFS_ROOT_ITEM_KEY;
 274         root_key.offset = (u64)-1;
 275
 276         while (1) {
 277                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 278                 if (ret < 0) {
 279                         err = ret;
 280                         break;
 281                 }
 282
 283                 leaf = path->nodes[0];
 284                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 285                         ret = btrfs_next_leaf(tree_root, path);
 286                         if (ret < 0)
 287                                 err = ret;
 288                         if (ret != 0)
 289                                 break;
 290                         leaf = path->nodes[0];
 291                 }
 292
 293                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 294                 btrfs_release_path(tree_root, path);
 295
 296                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 297                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 298                         break;
 299
 300                 root_key.objectid = key.offset;
 301                 key.offset++;
 302
 303                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 304                                                   &root_key);
 305                 if (!IS_ERR(root))
 306                         continue;
 307
 308                 ret = PTR_ERR(root);
 309                 if (ret != -ENOENT) {
 310                         err = ret;
 311                         break;
 312                 }
 313
 314                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 315                 if (ret) {
 316                         err = ret;
 317                         break;
 318                 }
 319         }
 320
 321         btrfs_free_path(path);
 322         return err;
 323 }
 324
 325 /* drop the root item for 'key' from 'root' */
 326 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 327                    struct btrfs_key *key)
 328 {
 329         struct btrfs_path *path;
 330         int ret;
 331         struct btrfs_root_item *ri;
 332         struct extent_buffer *leaf;
 333
 334         path = btrfs_alloc_path();
 335         BUG_ON(!path);
 336         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 337         if (ret < 0)
 338                 goto out;
 339
 340         BUG_ON(ret != 0);
 341         leaf = path->nodes[0];
 342         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 343
 344         ret = btrfs_del_item(trans, root, path);
 345 out:
 346         btrfs_free_path(path);
 347         return ret;
 348 }
 349
 350 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 351                        struct btrfs_root *tree_root,
 352                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 353                        const char *name, int name_len)
 354
 355 {
 356         struct btrfs_path *path;
 357         struct btrfs_root_ref *ref;
 358         struct extent_buffer *leaf;
 359         struct btrfs_key key;
 360         unsigned long ptr;
 361         int err = 0;
 362         int ret;
 363
 364         path = btrfs_alloc_path();
 365         if (!path)
 366                 return -ENOMEM;
 367
 368         key.objectid = root_id;
 369         key.type = BTRFS_ROOT_BACKREF_KEY;
 370         key.offset = ref_id;
 371 again:
 372         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 373         BUG_ON(ret < 0);
 374         if (ret == 0) {
 375                 leaf = path->nodes[0];
 376                 ref = btrfs_item_ptr(leaf, path->slots[0],
 377                                      struct btrfs_root_ref);
 378
 379                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 380                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 381                 ptr = (unsigned long)(ref + 1);
 382                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 383                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 384
 385                 ret = btrfs_del_item(trans, tree_root, path);
 386                 BUG_ON(ret);
 387         } else
 388                 err = -ENOENT;
 389
 390         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 391                 btrfs_release_path(tree_root, path);
 392                 key.objectid = ref_id;
 393                 key.type = BTRFS_ROOT_REF_KEY;
 394                 key.offset = root_id;
 395                 goto again;
 396         }
 397
 398         btrfs_free_path(path);
 399         return err;
 400 }
 401
 402 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 403                    struct btrfs_path *path,
 404                    u64 root_id, u64 ref_id)
 405 {
 406         struct btrfs_key key;
 407         int ret;
 408
 409         key.objectid = root_id;
 410         key.type = BTRFS_ROOT_REF_KEY;
 411         key.offset = ref_id;
 412
 413         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 414         return ret;
 415 }
 416
 417 /*
 418  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 419  * or BTRFS_ROOT_BACKREF_KEY.
 420  *
 421  * The dirid, sequence, name and name_len refer to the directory entry
 422  * that is referencing the root.
 423  *
 424  * For a forward ref, the root_id is the id of the tree referencing
 425  * the root and ref_id is the id of the subvol  or snapshot.
 426  *
 427  * For a back ref the root_id is the id of the subvol or snapshot and
 428  * ref_id is the id of the tree referencing it.
 429  */
 430 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 431                        struct btrfs_root *tree_root,
 432                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 433                        const char *name, int name_len)
 434 {
 435         struct btrfs_key key;
 436         int ret;
 437         struct btrfs_path *path;
 438         struct btrfs_root_ref *ref;
 439         struct extent_buffer *leaf;
 440         unsigned long ptr;
 441
 442         path = btrfs_alloc_path();
 443         if (!path)
 444                 return -ENOMEM;
 445
 446         key.objectid = root_id;
 447         key.type = BTRFS_ROOT_BACKREF_KEY;
 448         key.offset = ref_id;
 449 again:
 450         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 451                                       sizeof(*ref) + name_len);
 452         BUG_ON(ret);
 453
 454         leaf = path->nodes[0];
 455         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 456         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 457         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 458         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 459         ptr = (unsigned long)(ref + 1);
 460         write_extent_buffer(leaf, name, ptr, name_len);
 461         btrfs_mark_buffer_dirty(leaf);
 462
 463         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 464                 btrfs_release_path(tree_root, path);
 465                 key.objectid = ref_id;
 466                 key.type = BTRFS_ROOT_REF_KEY;
 467                 key.offset = root_id;
 468                 goto again;
 469         }
 470
 471         btrfs_free_path(path);
 472         return 0;
 473 }