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 "
  50                                         "generation and generation_v2 "
  51                                         "found in root item. This root "
  52                                         "was probably mounted with an "
  53                                         "older kernel. Resetting all "
  54                                         "new fields.");
  55                 }
  56                 need_reset = 1;
  57         }
  58         if (need_reset) {
  59                 memset(&item->generation_v2, 0,
  60                         sizeof(*item) - offsetof(struct btrfs_root_item,
  61                                         generation_v2));
  62
  63                 uuid_le_gen(&uuid);
  64                 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
  65         }
  66 }
  67
  68 /*
  69  * btrfs_find_root - lookup the root by the key.
  70  * root: the root of the root tree
  71  * search_key: the key to search
  72  * path: the path we search
  73  * root_item: the root item of the tree we look for
  74  * root_key: the reak key of the tree we look for
  75  *
  76  * If ->offset of 'seach_key' is -1ULL, it means we are not sure the offset
  77  * of the search key, just lookup the root with the highest offset for a
  78  * given objectid.
  79  *
  80  * If we find something return 0, otherwise > 0, < 0 on error.
  81  */
  82 int btrfs_find_root(struct btrfs_root *root, struct btrfs_key *search_key,
  83                     struct btrfs_path *path, struct btrfs_root_item *root_item,
  84                     struct btrfs_key *root_key)
  85 {
  86         struct btrfs_key found_key;
  87         struct extent_buffer *l;
  88         int ret;
  89         int slot;
  90
  91         ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
  92         if (ret < 0)
  93                 return ret;
  94
  95         if (search_key->offset != -1ULL) {      /* the search key is exact */
  96                 if (ret > 0)
  97                         goto out;
  98         } else {
  99                 BUG_ON(ret == 0);               /* Logical error */
 100                 if (path->slots[0] == 0)
 101                         goto out;
 102                 path->slots[0]--;
 103                 ret = 0;
 104         }
 105
 106         l = path->nodes[0];
 107         slot = path->slots[0];
 108
 109         btrfs_item_key_to_cpu(l, &found_key, slot);
 110         if (found_key.objectid != search_key->objectid ||
 111             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 112                 ret = 1;
 113                 goto out;
 114         }
 115
 116         if (root_item)
 117                 btrfs_read_root_item(l, slot, root_item);
 118         if (root_key)
 119                 memcpy(root_key, &found_key, sizeof(found_key));
 120 out:
 121         btrfs_release_path(path);
 122         return ret;
 123 }
 124
 125 void btrfs_set_root_node(struct btrfs_root_item *item,
 126                          struct extent_buffer *node)
 127 {
 128         btrfs_set_root_bytenr(item, node->start);
 129         btrfs_set_root_level(item, btrfs_header_level(node));
 130         btrfs_set_root_generation(item, btrfs_header_generation(node));
 131 }
 132
 133 /*
 134  * copy the data in 'item' into the btree
 135  */
 136 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 137                       *root, struct btrfs_key *key, struct btrfs_root_item
 138                       *item)
 139 {
 140         struct btrfs_path *path;
 141         struct extent_buffer *l;
 142         int ret;
 143         int slot;
 144         unsigned long ptr;
 145         u32 old_len;
 146
 147         path = btrfs_alloc_path();
 148         if (!path)
 149                 return -ENOMEM;
 150
 151         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 152         if (ret < 0) {
 153                 btrfs_abort_transaction(trans, root, ret);
 154                 goto out;
 155         }
 156
 157         if (ret != 0) {
 158                 btrfs_print_leaf(root, path->nodes[0]);
 159                 btrfs_crit(root->fs_info, "unable to update root key %llu %u %llu",
 160                        key->objectid, key->type, key->offset);
 161                 BUG_ON(1);
 162         }
 163
 164         l = path->nodes[0];
 165         slot = path->slots[0];
 166         ptr = btrfs_item_ptr_offset(l, slot);
 167         old_len = btrfs_item_size_nr(l, slot);
 168
 169         /*
 170          * If this is the first time we update the root item which originated
 171          * from an older kernel, we need to enlarge the item size to make room
 172          * for the added fields.
 173          */
 174         if (old_len < sizeof(*item)) {
 175                 btrfs_release_path(path);
 176                 ret = btrfs_search_slot(trans, root, key, path,
 177                                 -1, 1);
 178                 if (ret < 0) {
 179                         btrfs_abort_transaction(trans, root, ret);
 180                         goto out;
 181                 }
 182
 183                 ret = btrfs_del_item(trans, root, path);
 184                 if (ret < 0) {
 185                         btrfs_abort_transaction(trans, root, ret);
 186                         goto out;
 187                 }
 188                 btrfs_release_path(path);
 189                 ret = btrfs_insert_empty_item(trans, root, path,
 190                                 key, sizeof(*item));
 191                 if (ret < 0) {
 192                         btrfs_abort_transaction(trans, root, ret);
 193                         goto out;
 194                 }
 195                 l = path->nodes[0];
 196                 slot = path->slots[0];
 197                 ptr = btrfs_item_ptr_offset(l, slot);
 198         }
 199
 200         /*
 201          * Update generation_v2 so at the next mount we know the new root
 202          * fields are valid.
 203          */
 204         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 205
 206         write_extent_buffer(l, item, ptr, sizeof(*item));
 207         btrfs_mark_buffer_dirty(path->nodes[0]);
 208 out:
 209         btrfs_free_path(path);
 210         return ret;
 211 }
 212
 213 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 214                       struct btrfs_key *key, struct btrfs_root_item *item)
 215 {
 216         /*
 217          * Make sure generation v1 and v2 match. See update_root for details.
 218          */
 219         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 220         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 221 }
 222
 223 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 224 {
 225         struct extent_buffer *leaf;
 226         struct btrfs_path *path;
 227         struct btrfs_key key;
 228         struct btrfs_key root_key;
 229         struct btrfs_root *root;
 230         int err = 0;
 231         int ret;
 232         bool can_recover = true;
 233
 234         if (tree_root->fs_info->sb->s_flags & MS_RDONLY)
 235                 can_recover = false;
 236
 237         path = btrfs_alloc_path();
 238         if (!path)
 239                 return -ENOMEM;
 240
 241         key.objectid = BTRFS_ORPHAN_OBJECTID;
 242         key.type = BTRFS_ORPHAN_ITEM_KEY;
 243         key.offset = 0;
 244
 245         root_key.type = BTRFS_ROOT_ITEM_KEY;
 246         root_key.offset = (u64)-1;
 247
 248         while (1) {
 249                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 250                 if (ret < 0) {
 251                         err = ret;
 252                         break;
 253                 }
 254
 255                 leaf = path->nodes[0];
 256                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 257                         ret = btrfs_next_leaf(tree_root, path);
 258                         if (ret < 0)
 259                                 err = ret;
 260                         if (ret != 0)
 261                                 break;
 262                         leaf = path->nodes[0];
 263                 }
 264
 265                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 266                 btrfs_release_path(path);
 267
 268                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 269                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 270                         break;
 271
 272                 root_key.objectid = key.offset;
 273                 key.offset++;
 274
 275                 /*
 276                  * The root might have been inserted already, as before we look
 277                  * for orphan roots, log replay might have happened, which
 278                  * triggers a transaction commit and qgroup accounting, which
 279                  * in turn reads and inserts fs roots while doing backref
 280                  * walking.
 281                  */
 282                 root = btrfs_lookup_fs_root(tree_root->fs_info,
 283                                             root_key.objectid);
 284                 if (root) {
 285                         WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
 286                                           &root->state));
 287                         if (btrfs_root_refs(&root->root_item) == 0)
 288                                 btrfs_add_dead_root(root);
 289                         continue;
 290                 }
 291
 292                 root = btrfs_read_fs_root(tree_root, &root_key);
 293                 err = PTR_ERR_OR_ZERO(root);
 294                 if (err && err != -ENOENT) {
 295                         break;
 296                 } else if (err == -ENOENT) {
 297                         struct btrfs_trans_handle *trans;
 298
 299                         btrfs_release_path(path);
 300
 301                         trans = btrfs_join_transaction(tree_root);
 302                         if (IS_ERR(trans)) {
 303                                 err = PTR_ERR(trans);
 304                                 btrfs_std_error(tree_root->fs_info, err,
 305                                             "Failed to start trans to delete "
 306                                             "orphan item");
 307                                 break;
 308                         }
 309                         err = btrfs_del_orphan_item(trans, tree_root,
 310                                                     root_key.objectid);
 311                         btrfs_end_transaction(trans, tree_root);
 312                         if (err) {
 313                                 btrfs_std_error(tree_root->fs_info, err,
 314                                             "Failed to delete root orphan "
 315                                             "item");
 316                                 break;
 317                         }
 318                         continue;
 319                 }
 320
 321                 err = btrfs_init_fs_root(root);
 322                 if (err) {
 323                         btrfs_free_fs_root(root);
 324                         break;
 325                 }
 326
 327                 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
 328
 329                 err = btrfs_insert_fs_root(root->fs_info, root);
 330                 if (err) {
 331                         BUG_ON(err == -EEXIST);
 332                         btrfs_free_fs_root(root);
 333                         break;
 334                 }
 335
 336                 if (btrfs_root_refs(&root->root_item) == 0)
 337                         btrfs_add_dead_root(root);
 338         }
 339
 340         btrfs_free_path(path);
 341         return err;
 342 }
 343
 344 /* drop the root item for 'key' from 'root' */
 345 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 346                    struct btrfs_key *key)
 347 {
 348         struct btrfs_path *path;
 349         int ret;
 350
 351         path = btrfs_alloc_path();
 352         if (!path)
 353                 return -ENOMEM;
 354         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 355         if (ret < 0)
 356                 goto out;
 357
 358         BUG_ON(ret != 0);
 359
 360         ret = btrfs_del_item(trans, root, path);
 361 out:
 362         btrfs_free_path(path);
 363         return ret;
 364 }
 365
 366 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 367                        struct btrfs_root *tree_root,
 368                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 369                        const char *name, int name_len)
 370
 371 {
 372         struct btrfs_path *path;
 373         struct btrfs_root_ref *ref;
 374         struct extent_buffer *leaf;
 375         struct btrfs_key key;
 376         unsigned long ptr;
 377         int err = 0;
 378         int ret;
 379
 380         path = btrfs_alloc_path();
 381         if (!path)
 382                 return -ENOMEM;
 383
 384         key.objectid = root_id;
 385         key.type = BTRFS_ROOT_BACKREF_KEY;
 386         key.offset = ref_id;
 387 again:
 388         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 389         BUG_ON(ret < 0);
 390         if (ret == 0) {
 391                 leaf = path->nodes[0];
 392                 ref = btrfs_item_ptr(leaf, path->slots[0],
 393                                      struct btrfs_root_ref);
 394
 395                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 396                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 397                 ptr = (unsigned long)(ref + 1);
 398                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 399                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 400
 401                 ret = btrfs_del_item(trans, tree_root, path);
 402                 if (ret) {
 403                         err = ret;
 404                         goto out;
 405                 }
 406         } else
 407                 err = -ENOENT;
 408
 409         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 410                 btrfs_release_path(path);
 411                 key.objectid = ref_id;
 412                 key.type = BTRFS_ROOT_REF_KEY;
 413                 key.offset = root_id;
 414                 goto again;
 415         }
 416
 417 out:
 418         btrfs_free_path(path);
 419         return err;
 420 }
 421
 422 /*
 423  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 424  * or BTRFS_ROOT_BACKREF_KEY.
 425  *
 426  * The dirid, sequence, name and name_len refer to the directory entry
 427  * that is referencing the root.
 428  *
 429  * For a forward ref, the root_id is the id of the tree referencing
 430  * the root and ref_id is the id of the subvol  or snapshot.
 431  *
 432  * For a back ref the root_id is the id of the subvol or snapshot and
 433  * ref_id is the id of the tree referencing it.
 434  *
 435  * Will return 0, -ENOMEM, or anything from the CoW path
 436  */
 437 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 438                        struct btrfs_root *tree_root,
 439                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 440                        const char *name, int name_len)
 441 {
 442         struct btrfs_key key;
 443         int ret;
 444         struct btrfs_path *path;
 445         struct btrfs_root_ref *ref;
 446         struct extent_buffer *leaf;
 447         unsigned long ptr;
 448
 449         path = btrfs_alloc_path();
 450         if (!path)
 451                 return -ENOMEM;
 452
 453         key.objectid = root_id;
 454         key.type = BTRFS_ROOT_BACKREF_KEY;
 455         key.offset = ref_id;
 456 again:
 457         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 458                                       sizeof(*ref) + name_len);
 459         if (ret) {
 460                 btrfs_abort_transaction(trans, tree_root, ret);
 461                 btrfs_free_path(path);
 462                 return ret;
 463         }
 464
 465         leaf = path->nodes[0];
 466         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 467         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 468         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 469         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 470         ptr = (unsigned long)(ref + 1);
 471         write_extent_buffer(leaf, name, ptr, name_len);
 472         btrfs_mark_buffer_dirty(leaf);
 473
 474         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 475                 btrfs_release_path(path);
 476                 key.objectid = ref_id;
 477                 key.type = BTRFS_ROOT_REF_KEY;
 478                 key.offset = root_id;
 479                 goto again;
 480         }
 481
 482         btrfs_free_path(path);
 483         return 0;
 484 }
 485
 486 /*
 487  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 488  * for subvolumes. To work around this problem, we steal a bit from
 489  * root_item->inode_item->flags, and use it to indicate if those fields
 490  * have been properly initialized.
 491  */
 492 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 493 {
 494         u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
 495
 496         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 497                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 498                 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
 499                 btrfs_set_root_flags(root_item, 0);
 500                 btrfs_set_root_limit(root_item, 0);
 501         }
 502 }
 503
 504 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 505                              struct btrfs_root *root)
 506 {
 507         struct btrfs_root_item *item = &root->root_item;
 508         struct timespec ct = CURRENT_TIME;
 509
 510         spin_lock(&root->root_item_lock);
 511         btrfs_set_root_ctransid(item, trans->transid);
 512         btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
 513         btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
 514         spin_unlock(&root->root_item_lock);
 515 }