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/err.h>
  20 #include <linux/uuid.h>
  21 #include "ctree.h"
  22 #include "transaction.h"
  23 #include "disk-io.h"
  24 #include "print-tree.h"
  25
  26 /*
  27  * Read a root item from the tree. In case we detect a root item smaller then
  28  * sizeof(root_item), we know it's an old version of the root structure and
  29  * initialize all new fields to zero. The same happens if we detect mismatching
  30  * generation numbers as then we know the root was once mounted with an older
  31  * kernel that was not aware of the root item structure change.
  32  */
  33 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
  34                                 struct btrfs_root_item *item)
  35 {
  36         uuid_le uuid;
  37         int len;
  38         int need_reset = 0;
  39
  40         len = btrfs_item_size_nr(eb, slot);
  41         read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
  42                         min_t(int, len, (int)sizeof(*item)));
  43         if (len < sizeof(*item))
  44                 need_reset = 1;
  45         if (!need_reset && btrfs_root_generation(item)
  46                 != btrfs_root_generation_v2(item)) {
  47                 if (btrfs_root_generation_v2(item) != 0) {
  48                         btrfs_warn(eb->fs_info,
  49                                         "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
  50                 }
  51                 need_reset = 1;
  52         }
  53         if (need_reset) {
  54                 memset(&item->generation_v2, 0,
  55                         sizeof(*item) - offsetof(struct btrfs_root_item,
  56                                         generation_v2));
  57
  58                 uuid_le_gen(&uuid);
  59                 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
  60         }
  61 }
  62
  63 /*
  64  * btrfs_find_root - lookup the root by the key.
  65  * root: the root of the root tree
  66  * search_key: the key to search
  67  * path: the path we search
  68  * root_item: the root item of the tree we look for
  69  * root_key: the root key of the tree we look for
  70  *
  71  * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
  72  * of the search key, just lookup the root with the highest offset for a
  73  * given objectid.
  74  *
  75  * If we find something return 0, otherwise > 0, < 0 on error.
  76  */
  77 int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
  78                     struct btrfs_path *path, struct btrfs_root_item *root_item,
  79                     struct btrfs_key *root_key)
  80 {
  81         struct btrfs_key found_key;
  82         struct extent_buffer *l;
  83         int ret;
  84         int slot;
  85
  86         ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
  87         if (ret < 0)
  88                 return ret;
  89
  90         if (search_key->offset != -1ULL) {      /* the search key is exact */
  91                 if (ret > 0)
  92                         goto out;
  93         } else {
  94                 BUG_ON(ret == 0);               /* Logical error */
  95                 if (path->slots[0] == 0)
  96                         goto out;
  97                 path->slots[0]--;
  98                 ret = 0;
  99         }
 100
 101         l = path->nodes[0];
 102         slot = path->slots[0];
 103
 104         btrfs_item_key_to_cpu(l, &found_key, slot);
 105         if (found_key.objectid != search_key->objectid ||
 106             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 107                 ret = 1;
 108                 goto out;
 109         }
 110
 111         if (root_item)
 112                 btrfs_read_root_item(l, slot, root_item);
 113         if (root_key)
 114                 memcpy(root_key, &found_key, sizeof(found_key));
 115 out:
 116         btrfs_release_path(path);
 117         return ret;
 118 }
 119
 120 void 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 }
 127
 128 /*
 129  * copy the data in 'item' into the btree
 130  */
 131 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 132                       *root, struct btrfs_key *key, struct btrfs_root_item
 133                       *item)
 134 {
 135         struct btrfs_fs_info *fs_info = root->fs_info;
 136         struct btrfs_path *path;
 137         struct extent_buffer *l;
 138         int ret;
 139         int slot;
 140         unsigned long ptr;
 141         u32 old_len;
 142
 143         path = btrfs_alloc_path();
 144         if (!path)
 145                 return -ENOMEM;
 146
 147         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 148         if (ret < 0) {
 149                 btrfs_abort_transaction(trans, ret);
 150                 goto out;
 151         }
 152
 153         if (ret != 0) {
 154                 btrfs_print_leaf(path->nodes[0]);
 155                 btrfs_crit(fs_info, "unable to update root key %llu %u %llu",
 156                            key->objectid, key->type, key->offset);
 157                 BUG_ON(1);
 158         }
 159
 160         l = path->nodes[0];
 161         slot = path->slots[0];
 162         ptr = btrfs_item_ptr_offset(l, slot);
 163         old_len = btrfs_item_size_nr(l, slot);
 164
 165         /*
 166          * If this is the first time we update the root item which originated
 167          * from an older kernel, we need to enlarge the item size to make room
 168          * for the added fields.
 169          */
 170         if (old_len < sizeof(*item)) {
 171                 btrfs_release_path(path);
 172                 ret = btrfs_search_slot(trans, root, key, path,
 173                                 -1, 1);
 174                 if (ret < 0) {
 175                         btrfs_abort_transaction(trans, ret);
 176                         goto out;
 177                 }
 178
 179                 ret = btrfs_del_item(trans, root, path);
 180                 if (ret < 0) {
 181                         btrfs_abort_transaction(trans, ret);
 182                         goto out;
 183                 }
 184                 btrfs_release_path(path);
 185                 ret = btrfs_insert_empty_item(trans, root, path,
 186                                 key, sizeof(*item));
 187                 if (ret < 0) {
 188                         btrfs_abort_transaction(trans, ret);
 189                         goto out;
 190                 }
 191                 l = path->nodes[0];
 192                 slot = path->slots[0];
 193                 ptr = btrfs_item_ptr_offset(l, slot);
 194         }
 195
 196         /*
 197          * Update generation_v2 so at the next mount we know the new root
 198          * fields are valid.
 199          */
 200         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 201
 202         write_extent_buffer(l, item, ptr, sizeof(*item));
 203         btrfs_mark_buffer_dirty(path->nodes[0]);
 204 out:
 205         btrfs_free_path(path);
 206         return ret;
 207 }
 208
 209 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 210                       const struct btrfs_key *key, struct btrfs_root_item *item)
 211 {
 212         /*
 213          * Make sure generation v1 and v2 match. See update_root for details.
 214          */
 215         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 216         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 217 }
 218
 219 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
 220 {
 221         struct btrfs_root *tree_root = fs_info->tree_root;
 222         struct extent_buffer *leaf;
 223         struct btrfs_path *path;
 224         struct btrfs_key key;
 225         struct btrfs_key root_key;
 226         struct btrfs_root *root;
 227         int err = 0;
 228         int ret;
 229
 230         path = btrfs_alloc_path();
 231         if (!path)
 232                 return -ENOMEM;
 233
 234         key.objectid = BTRFS_ORPHAN_OBJECTID;
 235         key.type = BTRFS_ORPHAN_ITEM_KEY;
 236         key.offset = 0;
 237
 238         root_key.type = BTRFS_ROOT_ITEM_KEY;
 239         root_key.offset = (u64)-1;
 240
 241         while (1) {
 242                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 243                 if (ret < 0) {
 244                         err = ret;
 245                         break;
 246                 }
 247
 248                 leaf = path->nodes[0];
 249                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 250                         ret = btrfs_next_leaf(tree_root, path);
 251                         if (ret < 0)
 252                                 err = ret;
 253                         if (ret != 0)
 254                                 break;
 255                         leaf = path->nodes[0];
 256                 }
 257
 258                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 259                 btrfs_release_path(path);
 260
 261                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 262                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 263                         break;
 264
 265                 root_key.objectid = key.offset;
 266                 key.offset++;
 267
 268                 /*
 269                  * The root might have been inserted already, as before we look
 270                  * for orphan roots, log replay might have happened, which
 271                  * triggers a transaction commit and qgroup accounting, which
 272                  * in turn reads and inserts fs roots while doing backref
 273                  * walking.
 274                  */
 275                 root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
 276                 if (root) {
 277                         WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
 278                                           &root->state));
 279                         if (btrfs_root_refs(&root->root_item) == 0)
 280                                 btrfs_add_dead_root(root);
 281                         continue;
 282                 }
 283
 284                 root = btrfs_read_fs_root(tree_root, &root_key);
 285                 err = PTR_ERR_OR_ZERO(root);
 286                 if (err && err != -ENOENT) {
 287                         break;
 288                 } else if (err == -ENOENT) {
 289                         struct btrfs_trans_handle *trans;
 290
 291                         btrfs_release_path(path);
 292
 293                         trans = btrfs_join_transaction(tree_root);
 294                         if (IS_ERR(trans)) {
 295                                 err = PTR_ERR(trans);
 296                                 btrfs_handle_fs_error(fs_info, err,
 297                                             "Failed to start trans to delete orphan item");
 298                                 break;
 299                         }
 300                         err = btrfs_del_orphan_item(trans, tree_root,
 301                                                     root_key.objectid);
 302                         btrfs_end_transaction(trans);
 303                         if (err) {
 304                                 btrfs_handle_fs_error(fs_info, err,
 305                                             "Failed to delete root orphan item");
 306                                 break;
 307                         }
 308                         continue;
 309                 }
 310
 311                 err = btrfs_init_fs_root(root);
 312                 if (err) {
 313                         btrfs_free_fs_root(root);
 314                         break;
 315                 }
 316
 317                 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
 318
 319                 err = btrfs_insert_fs_root(fs_info, root);
 320                 if (err) {
 321                         BUG_ON(err == -EEXIST);
 322                         btrfs_free_fs_root(root);
 323                         break;
 324                 }
 325
 326                 if (btrfs_root_refs(&root->root_item) == 0)
 327                         btrfs_add_dead_root(root);
 328         }
 329
 330         btrfs_free_path(path);
 331         return err;
 332 }
 333
 334 /* drop the root item for 'key' from the tree root */
 335 int btrfs_del_root(struct btrfs_trans_handle *trans,
 336                    struct btrfs_fs_info *fs_info, const struct btrfs_key *key)
 337 {
 338         struct btrfs_root *root = fs_info->tree_root;
 339         struct btrfs_path *path;
 340         int ret;
 341
 342         path = btrfs_alloc_path();
 343         if (!path)
 344                 return -ENOMEM;
 345         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 346         if (ret < 0)
 347                 goto out;
 348
 349         BUG_ON(ret != 0);
 350
 351         ret = btrfs_del_item(trans, root, path);
 352 out:
 353         btrfs_free_path(path);
 354         return ret;
 355 }
 356
 357 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 358                        struct btrfs_fs_info *fs_info,
 359                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 360                        const char *name, int name_len)
 361
 362 {
 363         struct btrfs_root *tree_root = fs_info->tree_root;
 364         struct btrfs_path *path;
 365         struct btrfs_root_ref *ref;
 366         struct extent_buffer *leaf;
 367         struct btrfs_key key;
 368         unsigned long ptr;
 369         int err = 0;
 370         int ret;
 371
 372         path = btrfs_alloc_path();
 373         if (!path)
 374                 return -ENOMEM;
 375
 376         key.objectid = root_id;
 377         key.type = BTRFS_ROOT_BACKREF_KEY;
 378         key.offset = ref_id;
 379 again:
 380         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 381         BUG_ON(ret < 0);
 382         if (ret == 0) {
 383                 leaf = path->nodes[0];
 384                 ref = btrfs_item_ptr(leaf, path->slots[0],
 385                                      struct btrfs_root_ref);
 386
 387                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 388                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 389                 ptr = (unsigned long)(ref + 1);
 390                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 391                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 392
 393                 ret = btrfs_del_item(trans, tree_root, path);
 394                 if (ret) {
 395                         err = ret;
 396                         goto out;
 397                 }
 398         } else
 399                 err = -ENOENT;
 400
 401         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 402                 btrfs_release_path(path);
 403                 key.objectid = ref_id;
 404                 key.type = BTRFS_ROOT_REF_KEY;
 405                 key.offset = root_id;
 406                 goto again;
 407         }
 408
 409 out:
 410         btrfs_free_path(path);
 411         return err;
 412 }
 413
 414 /*
 415  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 416  * or BTRFS_ROOT_BACKREF_KEY.
 417  *
 418  * The dirid, sequence, name and name_len refer to the directory entry
 419  * that is referencing the root.
 420  *
 421  * For a forward ref, the root_id is the id of the tree referencing
 422  * the root and ref_id is the id of the subvol  or snapshot.
 423  *
 424  * For a back ref the root_id is the id of the subvol or snapshot and
 425  * ref_id is the id of the tree referencing it.
 426  *
 427  * Will return 0, -ENOMEM, or anything from the CoW path
 428  */
 429 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 430                        struct btrfs_fs_info *fs_info,
 431                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 432                        const char *name, int name_len)
 433 {
 434         struct btrfs_root *tree_root = fs_info->tree_root;
 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         if (ret) {
 453                 btrfs_abort_transaction(trans, ret);
 454                 btrfs_free_path(path);
 455                 return ret;
 456         }
 457
 458         leaf = path->nodes[0];
 459         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 460         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 461         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 462         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 463         ptr = (unsigned long)(ref + 1);
 464         write_extent_buffer(leaf, name, ptr, name_len);
 465         btrfs_mark_buffer_dirty(leaf);
 466
 467         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 468                 btrfs_release_path(path);
 469                 key.objectid = ref_id;
 470                 key.type = BTRFS_ROOT_REF_KEY;
 471                 key.offset = root_id;
 472                 goto again;
 473         }
 474
 475         btrfs_free_path(path);
 476         return 0;
 477 }
 478
 479 /*
 480  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 481  * for subvolumes. To work around this problem, we steal a bit from
 482  * root_item->inode_item->flags, and use it to indicate if those fields
 483  * have been properly initialized.
 484  */
 485 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 486 {
 487         u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
 488
 489         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 490                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 491                 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
 492                 btrfs_set_root_flags(root_item, 0);
 493                 btrfs_set_root_limit(root_item, 0);
 494         }
 495 }
 496
 497 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 498                              struct btrfs_root *root)
 499 {
 500         struct btrfs_root_item *item = &root->root_item;
 501         struct timespec ct;
 502
 503         ktime_get_real_ts(&ct);
 504         spin_lock(&root->root_item_lock);
 505         btrfs_set_root_ctransid(item, trans->transid);
 506         btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
 507         btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
 508         spin_unlock(&root->root_item_lock);
 509 }