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  * lookup the root with the highest offset for a given objectid.  The key we do
  26  * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
  27  * on error.
  28  */
  29 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
  30                         struct btrfs_root_item *item, struct btrfs_key *key)
  31 {
  32         struct btrfs_path *path;
  33         struct btrfs_key search_key;
  34         struct btrfs_key found_key;
  35         struct extent_buffer *l;
  36         int ret;
  37         int slot;
  38
  39         search_key.objectid = objectid;
  40         search_key.type = BTRFS_ROOT_ITEM_KEY;
  41         search_key.offset = (u64)-1;
  42
  43         path = btrfs_alloc_path();
  44         if (!path)
  45                 return -ENOMEM;
  46         ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
  47         if (ret < 0)
  48                 goto out;
  49
  50         BUG_ON(ret == 0);
  51         if (path->slots[0] == 0) {
  52                 ret = 1;
  53                 goto out;
  54         }
  55         l = path->nodes[0];
  56         slot = path->slots[0] - 1;
  57         btrfs_item_key_to_cpu(l, &found_key, slot);
  58         if (found_key.objectid != objectid ||
  59             found_key.type != BTRFS_ROOT_ITEM_KEY) {
  60                 ret = 1;
  61                 goto out;
  62         }
  63         if (item)
  64                 read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
  65                                    sizeof(*item));
  66         if (key)
  67                 memcpy(key, &found_key, sizeof(found_key));
  68         ret = 0;
  69 out:
  70         btrfs_free_path(path);
  71         return ret;
  72 }
  73
  74 int btrfs_set_root_node(struct btrfs_root_item *item,
  75                         struct extent_buffer *node)
  76 {
  77         btrfs_set_root_bytenr(item, node->start);
  78         btrfs_set_root_level(item, btrfs_header_level(node));
  79         btrfs_set_root_generation(item, btrfs_header_generation(node));
  80         return 0;
  81 }
  82
  83 /*
  84  * copy the data in 'item' into the btree
  85  */
  86 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
  87                       *root, struct btrfs_key *key, struct btrfs_root_item
  88                       *item)
  89 {
  90         struct btrfs_path *path;
  91         struct extent_buffer *l;
  92         int ret;
  93         int slot;
  94         unsigned long ptr;
  95
  96         path = btrfs_alloc_path();
  97         BUG_ON(!path);
  98         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
  99         if (ret < 0)
 100                 goto out;
 101
 102         if (ret != 0) {
 103                 btrfs_print_leaf(root, path->nodes[0]);
 104                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 105                        (unsigned long long)key->objectid, key->type,
 106                        (unsigned long long)key->offset);
 107                 BUG_ON(1);
 108         }
 109
 110         l = path->nodes[0];
 111         slot = path->slots[0];
 112         ptr = btrfs_item_ptr_offset(l, slot);
 113         write_extent_buffer(l, item, ptr, sizeof(*item));
 114         btrfs_mark_buffer_dirty(path->nodes[0]);
 115 out:
 116         btrfs_free_path(path);
 117         return ret;
 118 }
 119
 120 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 121                       *root, struct btrfs_key *key, struct btrfs_root_item
 122                       *item)
 123 {
 124         int ret;
 125         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 126         return ret;
 127 }
 128
 129 /*
 130  * at mount time we want to find all the old transaction snapshots that were in
 131  * the process of being deleted if we crashed.  This is any root item with an
 132  * offset lower than the latest root.  They need to be queued for deletion to
 133  * finish what was happening when we crashed.
 134  */
 135 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 136 {
 137         struct btrfs_root *dead_root;
 138         struct btrfs_root_item *ri;
 139         struct btrfs_key key;
 140         struct btrfs_key found_key;
 141         struct btrfs_path *path;
 142         int ret;
 143         u32 nritems;
 144         struct extent_buffer *leaf;
 145         int slot;
 146
 147         key.objectid = objectid;
 148         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 149         key.offset = 0;
 150         path = btrfs_alloc_path();
 151         if (!path)
 152                 return -ENOMEM;
 153
 154 again:
 155         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 156         if (ret < 0)
 157                 goto err;
 158         while (1) {
 159                 leaf = path->nodes[0];
 160                 nritems = btrfs_header_nritems(leaf);
 161                 slot = path->slots[0];
 162                 if (slot >= nritems) {
 163                         ret = btrfs_next_leaf(root, path);
 164                         if (ret)
 165                                 break;
 166                         leaf = path->nodes[0];
 167                         nritems = btrfs_header_nritems(leaf);
 168                         slot = path->slots[0];
 169                 }
 170                 btrfs_item_key_to_cpu(leaf, &key, slot);
 171                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 172                         goto next;
 173
 174                 if (key.objectid < objectid)
 175                         goto next;
 176
 177                 if (key.objectid > objectid)
 178                         break;
 179
 180                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 181                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 182                         goto next;
 183
 184                 memcpy(&found_key, &key, sizeof(key));
 185                 key.offset++;
 186                 btrfs_release_path(path);
 187                 dead_root =
 188                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 189                                                     &found_key);
 190                 if (IS_ERR(dead_root)) {
 191                         ret = PTR_ERR(dead_root);
 192                         goto err;
 193                 }
 194
 195                 ret = btrfs_add_dead_root(dead_root);
 196                 if (ret)
 197                         goto err;
 198                 goto again;
 199 next:
 200                 slot++;
 201                 path->slots[0]++;
 202         }
 203         ret = 0;
 204 err:
 205         btrfs_free_path(path);
 206         return ret;
 207 }
 208
 209 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 210 {
 211         struct extent_buffer *leaf;
 212         struct btrfs_path *path;
 213         struct btrfs_key key;
 214         struct btrfs_key root_key;
 215         struct btrfs_root *root;
 216         int err = 0;
 217         int ret;
 218
 219         path = btrfs_alloc_path();
 220         if (!path)
 221                 return -ENOMEM;
 222
 223         key.objectid = BTRFS_ORPHAN_OBJECTID;
 224         key.type = BTRFS_ORPHAN_ITEM_KEY;
 225         key.offset = 0;
 226
 227         root_key.type = BTRFS_ROOT_ITEM_KEY;
 228         root_key.offset = (u64)-1;
 229
 230         while (1) {
 231                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 232                 if (ret < 0) {
 233                         err = ret;
 234                         break;
 235                 }
 236
 237                 leaf = path->nodes[0];
 238                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 239                         ret = btrfs_next_leaf(tree_root, path);
 240                         if (ret < 0)
 241                                 err = ret;
 242                         if (ret != 0)
 243                                 break;
 244                         leaf = path->nodes[0];
 245                 }
 246
 247                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 248                 btrfs_release_path(path);
 249
 250                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 251                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 252                         break;
 253
 254                 root_key.objectid = key.offset;
 255                 key.offset++;
 256
 257                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 258                                                   &root_key);
 259                 if (!IS_ERR(root))
 260                         continue;
 261
 262                 ret = PTR_ERR(root);
 263                 if (ret != -ENOENT) {
 264                         err = ret;
 265                         break;
 266                 }
 267
 268                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 269                 if (ret) {
 270                         err = ret;
 271                         break;
 272                 }
 273         }
 274
 275         btrfs_free_path(path);
 276         return err;
 277 }
 278
 279 /* drop the root item for 'key' from 'root' */
 280 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 281                    struct btrfs_key *key)
 282 {
 283         struct btrfs_path *path;
 284         int ret;
 285         struct btrfs_root_item *ri;
 286         struct extent_buffer *leaf;
 287
 288         path = btrfs_alloc_path();
 289         if (!path)
 290                 return -ENOMEM;
 291         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 292         if (ret < 0)
 293                 goto out;
 294
 295         BUG_ON(ret != 0);
 296         leaf = path->nodes[0];
 297         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 298
 299         ret = btrfs_del_item(trans, root, path);
 300 out:
 301         btrfs_free_path(path);
 302         return ret;
 303 }
 304
 305 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 306                        struct btrfs_root *tree_root,
 307                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 308                        const char *name, int name_len)
 309
 310 {
 311         struct btrfs_path *path;
 312         struct btrfs_root_ref *ref;
 313         struct extent_buffer *leaf;
 314         struct btrfs_key key;
 315         unsigned long ptr;
 316         int err = 0;
 317         int ret;
 318
 319         path = btrfs_alloc_path();
 320         if (!path)
 321                 return -ENOMEM;
 322
 323         key.objectid = root_id;
 324         key.type = BTRFS_ROOT_BACKREF_KEY;
 325         key.offset = ref_id;
 326 again:
 327         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 328         BUG_ON(ret < 0);
 329         if (ret == 0) {
 330                 leaf = path->nodes[0];
 331                 ref = btrfs_item_ptr(leaf, path->slots[0],
 332                                      struct btrfs_root_ref);
 333
 334                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 335                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 336                 ptr = (unsigned long)(ref + 1);
 337                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 338                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 339
 340                 ret = btrfs_del_item(trans, tree_root, path);
 341                 if (ret) {
 342                         err = ret;
 343                         goto out;
 344                 }
 345         } else
 346                 err = -ENOENT;
 347
 348         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 349                 btrfs_release_path(path);
 350                 key.objectid = ref_id;
 351                 key.type = BTRFS_ROOT_REF_KEY;
 352                 key.offset = root_id;
 353                 goto again;
 354         }
 355
 356 out:
 357         btrfs_free_path(path);
 358         return err;
 359 }
 360
 361 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 362                    struct btrfs_path *path,
 363                    u64 root_id, u64 ref_id)
 364 {
 365         struct btrfs_key key;
 366         int ret;
 367
 368         key.objectid = root_id;
 369         key.type = BTRFS_ROOT_REF_KEY;
 370         key.offset = ref_id;
 371
 372         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 373         return ret;
 374 }
 375
 376 /*
 377  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 378  * or BTRFS_ROOT_BACKREF_KEY.
 379  *
 380  * The dirid, sequence, name and name_len refer to the directory entry
 381  * that is referencing the root.
 382  *
 383  * For a forward ref, the root_id is the id of the tree referencing
 384  * the root and ref_id is the id of the subvol  or snapshot.
 385  *
 386  * For a back ref the root_id is the id of the subvol or snapshot and
 387  * ref_id is the id of the tree referencing it.
 388  */
 389 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 390                        struct btrfs_root *tree_root,
 391                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 392                        const char *name, int name_len)
 393 {
 394         struct btrfs_key key;
 395         int ret;
 396         struct btrfs_path *path;
 397         struct btrfs_root_ref *ref;
 398         struct extent_buffer *leaf;
 399         unsigned long ptr;
 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_insert_empty_item(trans, tree_root, path, &key,
 410                                       sizeof(*ref) + name_len);
 411         BUG_ON(ret);
 412
 413         leaf = path->nodes[0];
 414         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 415         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 416         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 417         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 418         ptr = (unsigned long)(ref + 1);
 419         write_extent_buffer(leaf, name, ptr, name_len);
 420         btrfs_mark_buffer_dirty(leaf);
 421
 422         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 423                 btrfs_release_path(path);
 424                 key.objectid = ref_id;
 425                 key.type = BTRFS_ROOT_REF_KEY;
 426                 key.offset = root_id;
 427                 goto again;
 428         }
 429
 430         btrfs_free_path(path);
 431         return 0;
 432 }
 433
 434 /*
 435  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 436  * for subvolumes. To work around this problem, we steal a bit from
 437  * root_item->inode_item->flags, and use it to indicate if those fields
 438  * have been properly initialized.
 439  */
 440 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 441 {
 442         u64 inode_flags = le64_to_cpu(root_item->inode.flags);
 443
 444         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 445                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 446                 root_item->inode.flags = cpu_to_le64(inode_flags);
 447                 root_item->flags = 0;
 448                 root_item->byte_limit = 0;
 449         }
 450 }