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 <linux/uuid.h>
  20 #include "ctree.h"
  21 #include "transaction.h"
  22 #include "disk-io.h"
  23 #include "print-tree.h"
  24
  25 /*
  26  * Read a root item from the tree. In case we detect a root item smaller then
  27  * sizeof(root_item), we know it's an old version of the root structure and
  28  * initialize all new fields to zero. The same happens if we detect mismatching
  29  * generation numbers as then we know the root was once mounted with an older
  30  * kernel that was not aware of the root item structure change.
  31  */
  32 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
  33                                 struct btrfs_root_item *item)
  34 {
  35         uuid_le uuid;
  36         int len;
  37         int need_reset = 0;
  38
  39         len = btrfs_item_size_nr(eb, slot);
  40         read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
  41                         min_t(int, len, (int)sizeof(*item)));
  42         if (len < sizeof(*item))
  43                 need_reset = 1;
  44         if (!need_reset && btrfs_root_generation(item)
  45                 != btrfs_root_generation_v2(item)) {
  46                 if (btrfs_root_generation_v2(item) != 0) {
  47                         printk(KERN_WARNING "btrfs: mismatching "
  48                                         "generation and generation_v2 "
  49                                         "found in root item. This root "
  50                                         "was probably mounted with an "
  51                                         "older kernel. Resetting all "
  52                                         "new fields.\n");
  53                 }
  54                 need_reset = 1;
  55         }
  56         if (need_reset) {
  57                 memset(&item->generation_v2, 0,
  58                         sizeof(*item) - offsetof(struct btrfs_root_item,
  59                                         generation_v2));
  60
  61                 uuid_le_gen(&uuid);
  62                 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
  63         }
  64 }
  65
  66 /*
  67  * btrfs_find_root - lookup the root by the key.
  68  * root: the root of the root tree
  69  * search_key: the key to search
  70  * path: the path we search
  71  * root_item: the root item of the tree we look for
  72  * root_key: the reak key of the tree we look for
  73  *
  74  * If ->offset of 'seach_key' is -1ULL, it means we are not sure the offset
  75  * of the search key, just lookup the root with the highest offset for a
  76  * given objectid.
  77  *
  78  * If we find something return 0, otherwise > 0, < 0 on error.
  79  */
  80 int btrfs_find_root(struct btrfs_root *root, struct btrfs_key *search_key,
  81                     struct btrfs_path *path, struct btrfs_root_item *root_item,
  82                     struct btrfs_key *root_key)
  83 {
  84         struct btrfs_key found_key;
  85         struct extent_buffer *l;
  86         int ret;
  87         int slot;
  88
  89         ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
  90         if (ret < 0)
  91                 return ret;
  92
  93         if (search_key->offset != -1ULL) {      /* the search key is exact */
  94                 if (ret > 0)
  95                         goto out;
  96         } else {
  97                 BUG_ON(ret == 0);               /* Logical error */
  98                 if (path->slots[0] == 0)
  99                         goto out;
 100                 path->slots[0]--;
 101                 ret = 0;
 102         }
 103
 104         l = path->nodes[0];
 105         slot = path->slots[0];
 106
 107         btrfs_item_key_to_cpu(l, &found_key, slot);
 108         if (found_key.objectid != search_key->objectid ||
 109             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 110                 ret = 1;
 111                 goto out;
 112         }
 113
 114         if (root_item)
 115                 btrfs_read_root_item(l, slot, root_item);
 116         if (root_key)
 117                 memcpy(root_key, &found_key, sizeof(found_key));
 118 out:
 119         btrfs_release_path(path);
 120         return ret;
 121 }
 122
 123 void btrfs_set_root_node(struct btrfs_root_item *item,
 124                          struct extent_buffer *node)
 125 {
 126         btrfs_set_root_bytenr(item, node->start);
 127         btrfs_set_root_level(item, btrfs_header_level(node));
 128         btrfs_set_root_generation(item, btrfs_header_generation(node));
 129 }
 130
 131 /*
 132  * copy the data in 'item' into the btree
 133  */
 134 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 135                       *root, struct btrfs_key *key, struct btrfs_root_item
 136                       *item)
 137 {
 138         struct btrfs_path *path;
 139         struct extent_buffer *l;
 140         int ret;
 141         int slot;
 142         unsigned long ptr;
 143         int old_len;
 144
 145         path = btrfs_alloc_path();
 146         if (!path)
 147                 return -ENOMEM;
 148
 149         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 150         if (ret < 0) {
 151                 btrfs_abort_transaction(trans, root, ret);
 152                 goto out;
 153         }
 154
 155         if (ret != 0) {
 156                 btrfs_print_leaf(root, path->nodes[0]);
 157                 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
 158                        key->objectid, key->type, key->offset);
 159                 BUG_ON(1);
 160         }
 161
 162         l = path->nodes[0];
 163         slot = path->slots[0];
 164         ptr = btrfs_item_ptr_offset(l, slot);
 165         old_len = btrfs_item_size_nr(l, slot);
 166
 167         /*
 168          * If this is the first time we update the root item which originated
 169          * from an older kernel, we need to enlarge the item size to make room
 170          * for the added fields.
 171          */
 172         if (old_len < sizeof(*item)) {
 173                 btrfs_release_path(path);
 174                 ret = btrfs_search_slot(trans, root, key, path,
 175                                 -1, 1);
 176                 if (ret < 0) {
 177                         btrfs_abort_transaction(trans, root, ret);
 178                         goto out;
 179                 }
 180
 181                 ret = btrfs_del_item(trans, root, path);
 182                 if (ret < 0) {
 183                         btrfs_abort_transaction(trans, root, ret);
 184                         goto out;
 185                 }
 186                 btrfs_release_path(path);
 187                 ret = btrfs_insert_empty_item(trans, root, path,
 188                                 key, sizeof(*item));
 189                 if (ret < 0) {
 190                         btrfs_abort_transaction(trans, root, ret);
 191                         goto out;
 192                 }
 193                 l = path->nodes[0];
 194                 slot = path->slots[0];
 195                 ptr = btrfs_item_ptr_offset(l, slot);
 196         }
 197
 198         /*
 199          * Update generation_v2 so at the next mount we know the new root
 200          * fields are valid.
 201          */
 202         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 203
 204         write_extent_buffer(l, item, ptr, sizeof(*item));
 205         btrfs_mark_buffer_dirty(path->nodes[0]);
 206 out:
 207         btrfs_free_path(path);
 208         return ret;
 209 }
 210
 211 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 212                       struct btrfs_key *key, struct btrfs_root_item *item)
 213 {
 214         /*
 215          * Make sure generation v1 and v2 match. See update_root for details.
 216          */
 217         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 218         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 219 }
 220
 221 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 222 {
 223         struct extent_buffer *leaf;
 224         struct btrfs_path *path;
 225         struct btrfs_key key;
 226         struct btrfs_key root_key;
 227         struct btrfs_root *root;
 228         int err = 0;
 229         int ret;
 230         bool can_recover = true;
 231
 232         if (tree_root->fs_info->sb->s_flags & MS_RDONLY)
 233                 can_recover = false;
 234
 235         path = btrfs_alloc_path();
 236         if (!path)
 237                 return -ENOMEM;
 238
 239         key.objectid = BTRFS_ORPHAN_OBJECTID;
 240         key.type = BTRFS_ORPHAN_ITEM_KEY;
 241         key.offset = 0;
 242
 243         root_key.type = BTRFS_ROOT_ITEM_KEY;
 244         root_key.offset = (u64)-1;
 245
 246         while (1) {
 247                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 248                 if (ret < 0) {
 249                         err = ret;
 250                         break;
 251                 }
 252
 253                 leaf = path->nodes[0];
 254                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 255                         ret = btrfs_next_leaf(tree_root, path);
 256                         if (ret < 0)
 257                                 err = ret;
 258                         if (ret != 0)
 259                                 break;
 260                         leaf = path->nodes[0];
 261                 }
 262
 263                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 264                 btrfs_release_path(path);
 265
 266                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 267                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 268                         break;
 269
 270                 root_key.objectid = key.offset;
 271                 key.offset++;
 272
 273                 root = btrfs_read_fs_root(tree_root, &root_key);
 274                 err = PTR_RET(root);
 275                 if (err && err != -ENOENT) {
 276                         break;
 277                 } else if (err == -ENOENT) {
 278                         struct btrfs_trans_handle *trans;
 279
 280                         btrfs_release_path(path);
 281
 282                         trans = btrfs_join_transaction(tree_root);
 283                         if (IS_ERR(trans)) {
 284                                 err = PTR_ERR(trans);
 285                                 btrfs_error(tree_root->fs_info, err,
 286                                             "Failed to start trans to delete "
 287                                             "orphan item");
 288                                 break;
 289                         }
 290                         err = btrfs_del_orphan_item(trans, tree_root,
 291                                                     root_key.objectid);
 292                         btrfs_end_transaction(trans, tree_root);
 293                         if (err) {
 294                                 btrfs_error(tree_root->fs_info, err,
 295                                             "Failed to delete root orphan "
 296                                             "item");
 297                                 break;
 298                         }
 299                         continue;
 300                 }
 301
 302                 if (btrfs_root_refs(&root->root_item) == 0) {
 303                         btrfs_add_dead_root(root);
 304                         continue;
 305                 }
 306
 307                 err = btrfs_init_fs_root(root);
 308                 if (err) {
 309                         btrfs_free_fs_root(root);
 310                         break;
 311                 }
 312
 313                 root->orphan_item_inserted = 1;
 314
 315                 err = btrfs_insert_fs_root(root->fs_info, root);
 316                 if (err) {
 317                         BUG_ON(err == -EEXIST);
 318                         btrfs_free_fs_root(root);
 319                         break;
 320                 }
 321         }
 322
 323         btrfs_free_path(path);
 324         return err;
 325 }
 326
 327 /* drop the root item for 'key' from 'root' */
 328 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 329                    struct btrfs_key *key)
 330 {
 331         struct btrfs_path *path;
 332         int ret;
 333
 334         path = btrfs_alloc_path();
 335         if (!path)
 336                 return -ENOMEM;
 337         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 338         if (ret < 0)
 339                 goto out;
 340
 341         BUG_ON(ret != 0);
 342
 343         ret = btrfs_del_item(trans, root, path);
 344 out:
 345         btrfs_free_path(path);
 346         return ret;
 347 }
 348
 349 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 350                        struct btrfs_root *tree_root,
 351                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 352                        const char *name, int name_len)
 353
 354 {
 355         struct btrfs_path *path;
 356         struct btrfs_root_ref *ref;
 357         struct extent_buffer *leaf;
 358         struct btrfs_key key;
 359         unsigned long ptr;
 360         int err = 0;
 361         int ret;
 362
 363         path = btrfs_alloc_path();
 364         if (!path)
 365                 return -ENOMEM;
 366
 367         key.objectid = root_id;
 368         key.type = BTRFS_ROOT_BACKREF_KEY;
 369         key.offset = ref_id;
 370 again:
 371         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 372         BUG_ON(ret < 0);
 373         if (ret == 0) {
 374                 leaf = path->nodes[0];
 375                 ref = btrfs_item_ptr(leaf, path->slots[0],
 376                                      struct btrfs_root_ref);
 377
 378                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 379                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 380                 ptr = (unsigned long)(ref + 1);
 381                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 382                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 383
 384                 ret = btrfs_del_item(trans, tree_root, path);
 385                 if (ret) {
 386                         err = ret;
 387                         goto out;
 388                 }
 389         } else
 390                 err = -ENOENT;
 391
 392         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 393                 btrfs_release_path(path);
 394                 key.objectid = ref_id;
 395                 key.type = BTRFS_ROOT_REF_KEY;
 396                 key.offset = root_id;
 397                 goto again;
 398         }
 399
 400 out:
 401         btrfs_free_path(path);
 402         return err;
 403 }
 404
 405 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 406                    struct btrfs_path *path,
 407                    u64 root_id, u64 ref_id)
 408 {
 409         struct btrfs_key key;
 410         int ret;
 411
 412         key.objectid = root_id;
 413         key.type = BTRFS_ROOT_REF_KEY;
 414         key.offset = ref_id;
 415
 416         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 417         return ret;
 418 }
 419
 420 /*
 421  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 422  * or BTRFS_ROOT_BACKREF_KEY.
 423  *
 424  * The dirid, sequence, name and name_len refer to the directory entry
 425  * that is referencing the root.
 426  *
 427  * For a forward ref, the root_id is the id of the tree referencing
 428  * the root and ref_id is the id of the subvol  or snapshot.
 429  *
 430  * For a back ref the root_id is the id of the subvol or snapshot and
 431  * ref_id is the id of the tree referencing it.
 432  *
 433  * Will return 0, -ENOMEM, or anything from the CoW path
 434  */
 435 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 436                        struct btrfs_root *tree_root,
 437                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 438                        const char *name, int name_len)
 439 {
 440         struct btrfs_key key;
 441         int ret;
 442         struct btrfs_path *path;
 443         struct btrfs_root_ref *ref;
 444         struct extent_buffer *leaf;
 445         unsigned long ptr;
 446
 447         path = btrfs_alloc_path();
 448         if (!path)
 449                 return -ENOMEM;
 450
 451         key.objectid = root_id;
 452         key.type = BTRFS_ROOT_BACKREF_KEY;
 453         key.offset = ref_id;
 454 again:
 455         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 456                                       sizeof(*ref) + name_len);
 457         if (ret) {
 458                 btrfs_abort_transaction(trans, tree_root, ret);
 459                 btrfs_free_path(path);
 460                 return ret;
 461         }
 462
 463         leaf = path->nodes[0];
 464         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 465         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 466         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 467         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 468         ptr = (unsigned long)(ref + 1);
 469         write_extent_buffer(leaf, name, ptr, name_len);
 470         btrfs_mark_buffer_dirty(leaf);
 471
 472         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 473                 btrfs_release_path(path);
 474                 key.objectid = ref_id;
 475                 key.type = BTRFS_ROOT_REF_KEY;
 476                 key.offset = root_id;
 477                 goto again;
 478         }
 479
 480         btrfs_free_path(path);
 481         return 0;
 482 }
 483
 484 /*
 485  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 486  * for subvolumes. To work around this problem, we steal a bit from
 487  * root_item->inode_item->flags, and use it to indicate if those fields
 488  * have been properly initialized.
 489  */
 490 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 491 {
 492         u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
 493
 494         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 495                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 496                 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
 497                 btrfs_set_root_flags(root_item, 0);
 498                 btrfs_set_root_limit(root_item, 0);
 499         }
 500 }
 501
 502 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 503                              struct btrfs_root *root)
 504 {
 505         struct btrfs_root_item *item = &root->root_item;
 506         struct timespec ct = CURRENT_TIME;
 507
 508         spin_lock(&root->root_item_lock);
 509         btrfs_set_root_ctransid(item, trans->transid);
 510         btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
 511         btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
 512         spin_unlock(&root->root_item_lock);
 513 }