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 void 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 }
  81
  82 /*
  83  * copy the data in 'item' into the btree
  84  */
  85 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
  86                       *root, struct btrfs_key *key, struct btrfs_root_item
  87                       *item)
  88 {
  89         struct btrfs_path *path;
  90         struct extent_buffer *l;
  91         int ret;
  92         int slot;
  93         unsigned long ptr;
  94
  95         path = btrfs_alloc_path();
  96         BUG_ON(!path);
  97         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
  98         if (ret < 0)
  99                 goto out;
 100
 101         if (ret != 0) {
 102                 btrfs_print_leaf(root, path->nodes[0]);
 103                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 104                        (unsigned long long)key->objectid, key->type,
 105                        (unsigned long long)key->offset);
 106                 BUG_ON(1);
 107         }
 108
 109         l = path->nodes[0];
 110         slot = path->slots[0];
 111         ptr = btrfs_item_ptr_offset(l, slot);
 112         write_extent_buffer(l, item, ptr, sizeof(*item));
 113         btrfs_mark_buffer_dirty(path->nodes[0]);
 114 out:
 115         btrfs_free_path(path);
 116         return ret;
 117 }
 118
 119 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
 120                       *root, struct btrfs_key *key, struct btrfs_root_item
 121                       *item)
 122 {
 123         int ret;
 124         ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
 125         return ret;
 126 }
 127
 128 /*
 129  * at mount time we want to find all the old transaction snapshots that were in
 130  * the process of being deleted if we crashed.  This is any root item with an
 131  * offset lower than the latest root.  They need to be queued for deletion to
 132  * finish what was happening when we crashed.
 133  */
 134 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
 135 {
 136         struct btrfs_root *dead_root;
 137         struct btrfs_root_item *ri;
 138         struct btrfs_key key;
 139         struct btrfs_key found_key;
 140         struct btrfs_path *path;
 141         int ret;
 142         u32 nritems;
 143         struct extent_buffer *leaf;
 144         int slot;
 145
 146         key.objectid = objectid;
 147         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 148         key.offset = 0;
 149         path = btrfs_alloc_path();
 150         if (!path)
 151                 return -ENOMEM;
 152
 153 again:
 154         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 155         if (ret < 0)
 156                 goto err;
 157         while (1) {
 158                 leaf = path->nodes[0];
 159                 nritems = btrfs_header_nritems(leaf);
 160                 slot = path->slots[0];
 161                 if (slot >= nritems) {
 162                         ret = btrfs_next_leaf(root, path);
 163                         if (ret)
 164                                 break;
 165                         leaf = path->nodes[0];
 166                         nritems = btrfs_header_nritems(leaf);
 167                         slot = path->slots[0];
 168                 }
 169                 btrfs_item_key_to_cpu(leaf, &key, slot);
 170                 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
 171                         goto next;
 172
 173                 if (key.objectid < objectid)
 174                         goto next;
 175
 176                 if (key.objectid > objectid)
 177                         break;
 178
 179                 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
 180                 if (btrfs_disk_root_refs(leaf, ri) != 0)
 181                         goto next;
 182
 183                 memcpy(&found_key, &key, sizeof(key));
 184                 key.offset++;
 185                 btrfs_release_path(path);
 186                 dead_root =
 187                         btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
 188                                                     &found_key);
 189                 if (IS_ERR(dead_root)) {
 190                         ret = PTR_ERR(dead_root);
 191                         goto err;
 192                 }
 193
 194                 ret = btrfs_add_dead_root(dead_root);
 195                 if (ret)
 196                         goto err;
 197                 goto again;
 198 next:
 199                 slot++;
 200                 path->slots[0]++;
 201         }
 202         ret = 0;
 203 err:
 204         btrfs_free_path(path);
 205         return ret;
 206 }
 207
 208 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 209 {
 210         struct extent_buffer *leaf;
 211         struct btrfs_path *path;
 212         struct btrfs_key key;
 213         struct btrfs_key root_key;
 214         struct btrfs_root *root;
 215         int err = 0;
 216         int ret;
 217
 218         path = btrfs_alloc_path();
 219         if (!path)
 220                 return -ENOMEM;
 221
 222         key.objectid = BTRFS_ORPHAN_OBJECTID;
 223         key.type = BTRFS_ORPHAN_ITEM_KEY;
 224         key.offset = 0;
 225
 226         root_key.type = BTRFS_ROOT_ITEM_KEY;
 227         root_key.offset = (u64)-1;
 228
 229         while (1) {
 230                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 231                 if (ret < 0) {
 232                         err = ret;
 233                         break;
 234                 }
 235
 236                 leaf = path->nodes[0];
 237                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 238                         ret = btrfs_next_leaf(tree_root, path);
 239                         if (ret < 0)
 240                                 err = ret;
 241                         if (ret != 0)
 242                                 break;
 243                         leaf = path->nodes[0];
 244                 }
 245
 246                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 247                 btrfs_release_path(path);
 248
 249                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 250                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 251                         break;
 252
 253                 root_key.objectid = key.offset;
 254                 key.offset++;
 255
 256                 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
 257                                                   &root_key);
 258                 if (!IS_ERR(root))
 259                         continue;
 260
 261                 ret = PTR_ERR(root);
 262                 if (ret != -ENOENT) {
 263                         err = ret;
 264                         break;
 265                 }
 266
 267                 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
 268                 if (ret) {
 269                         err = ret;
 270                         break;
 271                 }
 272         }
 273
 274         btrfs_free_path(path);
 275         return err;
 276 }
 277
 278 /* drop the root item for 'key' from 'root' */
 279 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 280                    struct btrfs_key *key)
 281 {
 282         struct btrfs_path *path;
 283         int ret;
 284         struct btrfs_root_item *ri;
 285         struct extent_buffer *leaf;
 286
 287         path = btrfs_alloc_path();
 288         if (!path)
 289                 return -ENOMEM;
 290         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 291         if (ret < 0)
 292                 goto out;
 293
 294         BUG_ON(ret != 0);
 295         leaf = path->nodes[0];
 296         ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
 297
 298         ret = btrfs_del_item(trans, root, path);
 299 out:
 300         btrfs_free_path(path);
 301         return ret;
 302 }
 303
 304 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 305                        struct btrfs_root *tree_root,
 306                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 307                        const char *name, int name_len)
 308
 309 {
 310         struct btrfs_path *path;
 311         struct btrfs_root_ref *ref;
 312         struct extent_buffer *leaf;
 313         struct btrfs_key key;
 314         unsigned long ptr;
 315         int err = 0;
 316         int ret;
 317
 318         path = btrfs_alloc_path();
 319         if (!path)
 320                 return -ENOMEM;
 321
 322         key.objectid = root_id;
 323         key.type = BTRFS_ROOT_BACKREF_KEY;
 324         key.offset = ref_id;
 325 again:
 326         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 327         BUG_ON(ret < 0);
 328         if (ret == 0) {
 329                 leaf = path->nodes[0];
 330                 ref = btrfs_item_ptr(leaf, path->slots[0],
 331                                      struct btrfs_root_ref);
 332
 333                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 334                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 335                 ptr = (unsigned long)(ref + 1);
 336                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 337                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 338
 339                 ret = btrfs_del_item(trans, tree_root, path);
 340                 if (ret) {
 341                         err = ret;
 342                         goto out;
 343                 }
 344         } else
 345                 err = -ENOENT;
 346
 347         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 348                 btrfs_release_path(path);
 349                 key.objectid = ref_id;
 350                 key.type = BTRFS_ROOT_REF_KEY;
 351                 key.offset = root_id;
 352                 goto again;
 353         }
 354
 355 out:
 356         btrfs_free_path(path);
 357         return err;
 358 }
 359
 360 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 361                    struct btrfs_path *path,
 362                    u64 root_id, u64 ref_id)
 363 {
 364         struct btrfs_key key;
 365         int ret;
 366
 367         key.objectid = root_id;
 368         key.type = BTRFS_ROOT_REF_KEY;
 369         key.offset = ref_id;
 370
 371         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 372         return ret;
 373 }
 374
 375 /*
 376  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 377  * or BTRFS_ROOT_BACKREF_KEY.
 378  *
 379  * The dirid, sequence, name and name_len refer to the directory entry
 380  * that is referencing the root.
 381  *
 382  * For a forward ref, the root_id is the id of the tree referencing
 383  * the root and ref_id is the id of the subvol  or snapshot.
 384  *
 385  * For a back ref the root_id is the id of the subvol or snapshot and
 386  * ref_id is the id of the tree referencing it.
 387  */
 388 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 389                        struct btrfs_root *tree_root,
 390                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 391                        const char *name, int name_len)
 392 {
 393         struct btrfs_key key;
 394         int ret;
 395         struct btrfs_path *path;
 396         struct btrfs_root_ref *ref;
 397         struct extent_buffer *leaf;
 398         unsigned long ptr;
 399
 400         path = btrfs_alloc_path();
 401         if (!path)
 402                 return -ENOMEM;
 403
 404         key.objectid = root_id;
 405         key.type = BTRFS_ROOT_BACKREF_KEY;
 406         key.offset = ref_id;
 407 again:
 408         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 409                                       sizeof(*ref) + name_len);
 410         BUG_ON(ret);
 411
 412         leaf = path->nodes[0];
 413         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 414         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 415         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 416         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 417         ptr = (unsigned long)(ref + 1);
 418         write_extent_buffer(leaf, name, ptr, name_len);
 419         btrfs_mark_buffer_dirty(leaf);
 420
 421         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 422                 btrfs_release_path(path);
 423                 key.objectid = ref_id;
 424                 key.type = BTRFS_ROOT_REF_KEY;
 425                 key.offset = root_id;
 426                 goto again;
 427         }
 428
 429         btrfs_free_path(path);
 430         return 0;
 431 }
 432
 433 /*
 434  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 435  * for subvolumes. To work around this problem, we steal a bit from
 436  * root_item->inode_item->flags, and use it to indicate if those fields
 437  * have been properly initialized.
 438  */
 439 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 440 {
 441         u64 inode_flags = le64_to_cpu(root_item->inode.flags);
 442
 443         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 444                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 445                 root_item->inode.flags = cpu_to_le64(inode_flags);
 446                 root_item->flags = 0;
 447                 root_item->byte_limit = 0;
 448         }
 449 }