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 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                        (unsigned long long)key->objectid, key->type,
 159                        (unsigned long long)key->offset);
 160                 BUG_ON(1);
 161         }
 162
 163         l = path->nodes[0];
 164         slot = path->slots[0];
 165         ptr = btrfs_item_ptr_offset(l, slot);
 166         old_len = btrfs_item_size_nr(l, slot);
 167
 168         /*
 169          * If this is the first time we update the root item which originated
 170          * from an older kernel, we need to enlarge the item size to make room
 171          * for the added fields.
 172          */
 173         if (old_len < sizeof(*item)) {
 174                 btrfs_release_path(path);
 175                 ret = btrfs_search_slot(trans, root, key, path,
 176                                 -1, 1);
 177                 if (ret < 0) {
 178                         btrfs_abort_transaction(trans, root, ret);
 179                         goto out;
 180                 }
 181
 182                 ret = btrfs_del_item(trans, root, path);
 183                 if (ret < 0) {
 184                         btrfs_abort_transaction(trans, root, ret);
 185                         goto out;
 186                 }
 187                 btrfs_release_path(path);
 188                 ret = btrfs_insert_empty_item(trans, root, path,
 189                                 key, sizeof(*item));
 190                 if (ret < 0) {
 191                         btrfs_abort_transaction(trans, root, ret);
 192                         goto out;
 193                 }
 194                 l = path->nodes[0];
 195                 slot = path->slots[0];
 196                 ptr = btrfs_item_ptr_offset(l, slot);
 197         }
 198
 199         /*
 200          * Update generation_v2 so at the next mount we know the new root
 201          * fields are valid.
 202          */
 203         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 204
 205         write_extent_buffer(l, item, ptr, sizeof(*item));
 206         btrfs_mark_buffer_dirty(path->nodes[0]);
 207 out:
 208         btrfs_free_path(path);
 209         return ret;
 210 }
 211
 212 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 213                       struct btrfs_key *key, struct btrfs_root_item *item)
 214 {
 215         /*
 216          * Make sure generation v1 and v2 match. See update_root for details.
 217          */
 218         btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
 219         return btrfs_insert_item(trans, root, key, item, sizeof(*item));
 220 }
 221
 222 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
 223 {
 224         struct extent_buffer *leaf;
 225         struct btrfs_path *path;
 226         struct btrfs_key key;
 227         struct btrfs_key root_key;
 228         struct btrfs_root *root;
 229         int err = 0;
 230         int ret;
 231         bool can_recover = true;
 232
 233         if (tree_root->fs_info->sb->s_flags & MS_RDONLY)
 234                 can_recover = false;
 235
 236         path = btrfs_alloc_path();
 237         if (!path)
 238                 return -ENOMEM;
 239
 240         key.objectid = BTRFS_ORPHAN_OBJECTID;
 241         key.type = BTRFS_ORPHAN_ITEM_KEY;
 242         key.offset = 0;
 243
 244         root_key.type = BTRFS_ROOT_ITEM_KEY;
 245         root_key.offset = (u64)-1;
 246
 247         while (1) {
 248                 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 249                 if (ret < 0) {
 250                         err = ret;
 251                         break;
 252                 }
 253
 254                 leaf = path->nodes[0];
 255                 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
 256                         ret = btrfs_next_leaf(tree_root, path);
 257                         if (ret < 0)
 258                                 err = ret;
 259                         if (ret != 0)
 260                                 break;
 261                         leaf = path->nodes[0];
 262                 }
 263
 264                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
 265                 btrfs_release_path(path);
 266
 267                 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
 268                     key.type != BTRFS_ORPHAN_ITEM_KEY)
 269                         break;
 270
 271                 root_key.objectid = key.offset;
 272                 key.offset++;
 273
 274                 root = btrfs_read_fs_root(tree_root, &root_key);
 275                 err = PTR_RET(root);
 276                 if (err && err != -ENOENT) {
 277                         break;
 278                 } else if (err == -ENOENT) {
 279                         struct btrfs_trans_handle *trans;
 280
 281                         btrfs_release_path(path);
 282
 283                         trans = btrfs_join_transaction(tree_root);
 284                         if (IS_ERR(trans)) {
 285                                 err = PTR_ERR(trans);
 286                                 btrfs_error(tree_root->fs_info, err,
 287                                             "Failed to start trans to delete "
 288                                             "orphan item");
 289                                 break;
 290                         }
 291                         err = btrfs_del_orphan_item(trans, tree_root,
 292                                                     root_key.objectid);
 293                         btrfs_end_transaction(trans, tree_root);
 294                         if (err) {
 295                                 btrfs_error(tree_root->fs_info, err,
 296                                             "Failed to delete root orphan "
 297                                             "item");
 298                                 break;
 299                         }
 300                         continue;
 301                 }
 302
 303                 if (btrfs_root_refs(&root->root_item) == 0) {
 304                         btrfs_add_dead_root(root);
 305                         continue;
 306                 }
 307
 308                 err = btrfs_init_fs_root(root);
 309                 if (err) {
 310                         btrfs_free_fs_root(root);
 311                         break;
 312                 }
 313
 314                 root->orphan_item_inserted = 1;
 315
 316                 err = btrfs_insert_fs_root(root->fs_info, root);
 317                 if (err) {
 318                         BUG_ON(err == -EEXIST);
 319                         btrfs_free_fs_root(root);
 320                         break;
 321                 }
 322         }
 323
 324         btrfs_free_path(path);
 325         return err;
 326 }
 327
 328 /* drop the root item for 'key' from 'root' */
 329 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 330                    struct btrfs_key *key)
 331 {
 332         struct btrfs_path *path;
 333         int ret;
 334
 335         path = btrfs_alloc_path();
 336         if (!path)
 337                 return -ENOMEM;
 338         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 339         if (ret < 0)
 340                 goto out;
 341
 342         BUG_ON(ret != 0);
 343
 344         ret = btrfs_del_item(trans, root, path);
 345 out:
 346         btrfs_free_path(path);
 347         return ret;
 348 }
 349
 350 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 351                        struct btrfs_root *tree_root,
 352                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 353                        const char *name, int name_len)
 354
 355 {
 356         struct btrfs_path *path;
 357         struct btrfs_root_ref *ref;
 358         struct extent_buffer *leaf;
 359         struct btrfs_key key;
 360         unsigned long ptr;
 361         int err = 0;
 362         int ret;
 363
 364         path = btrfs_alloc_path();
 365         if (!path)
 366                 return -ENOMEM;
 367
 368         key.objectid = root_id;
 369         key.type = BTRFS_ROOT_BACKREF_KEY;
 370         key.offset = ref_id;
 371 again:
 372         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 373         BUG_ON(ret < 0);
 374         if (ret == 0) {
 375                 leaf = path->nodes[0];
 376                 ref = btrfs_item_ptr(leaf, path->slots[0],
 377                                      struct btrfs_root_ref);
 378
 379                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 380                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 381                 ptr = (unsigned long)(ref + 1);
 382                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 383                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 384
 385                 ret = btrfs_del_item(trans, tree_root, path);
 386                 if (ret) {
 387                         err = ret;
 388                         goto out;
 389                 }
 390         } else
 391                 err = -ENOENT;
 392
 393         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 394                 btrfs_release_path(path);
 395                 key.objectid = ref_id;
 396                 key.type = BTRFS_ROOT_REF_KEY;
 397                 key.offset = root_id;
 398                 goto again;
 399         }
 400
 401 out:
 402         btrfs_free_path(path);
 403         return err;
 404 }
 405
 406 int btrfs_find_root_ref(struct btrfs_root *tree_root,
 407                    struct btrfs_path *path,
 408                    u64 root_id, u64 ref_id)
 409 {
 410         struct btrfs_key key;
 411         int ret;
 412
 413         key.objectid = root_id;
 414         key.type = BTRFS_ROOT_REF_KEY;
 415         key.offset = ref_id;
 416
 417         ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
 418         return ret;
 419 }
 420
 421 /*
 422  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 423  * or BTRFS_ROOT_BACKREF_KEY.
 424  *
 425  * The dirid, sequence, name and name_len refer to the directory entry
 426  * that is referencing the root.
 427  *
 428  * For a forward ref, the root_id is the id of the tree referencing
 429  * the root and ref_id is the id of the subvol  or snapshot.
 430  *
 431  * For a back ref the root_id is the id of the subvol or snapshot and
 432  * ref_id is the id of the tree referencing it.
 433  *
 434  * Will return 0, -ENOMEM, or anything from the CoW path
 435  */
 436 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 437                        struct btrfs_root *tree_root,
 438                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 439                        const char *name, int name_len)
 440 {
 441         struct btrfs_key key;
 442         int ret;
 443         struct btrfs_path *path;
 444         struct btrfs_root_ref *ref;
 445         struct extent_buffer *leaf;
 446         unsigned long ptr;
 447
 448         path = btrfs_alloc_path();
 449         if (!path)
 450                 return -ENOMEM;
 451
 452         key.objectid = root_id;
 453         key.type = BTRFS_ROOT_BACKREF_KEY;
 454         key.offset = ref_id;
 455 again:
 456         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 457                                       sizeof(*ref) + name_len);
 458         if (ret) {
 459                 btrfs_abort_transaction(trans, tree_root, ret);
 460                 btrfs_free_path(path);
 461                 return ret;
 462         }
 463
 464         leaf = path->nodes[0];
 465         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 466         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 467         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 468         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 469         ptr = (unsigned long)(ref + 1);
 470         write_extent_buffer(leaf, name, ptr, name_len);
 471         btrfs_mark_buffer_dirty(leaf);
 472
 473         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 474                 btrfs_release_path(path);
 475                 key.objectid = ref_id;
 476                 key.type = BTRFS_ROOT_REF_KEY;
 477                 key.offset = root_id;
 478                 goto again;
 479         }
 480
 481         btrfs_free_path(path);
 482         return 0;
 483 }
 484
 485 /*
 486  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 487  * for subvolumes. To work around this problem, we steal a bit from
 488  * root_item->inode_item->flags, and use it to indicate if those fields
 489  * have been properly initialized.
 490  */
 491 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 492 {
 493         u64 inode_flags = le64_to_cpu(root_item->inode.flags);
 494
 495         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 496                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 497                 root_item->inode.flags = cpu_to_le64(inode_flags);
 498                 root_item->flags = 0;
 499                 root_item->byte_limit = 0;
 500         }
 501 }
 502
 503 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 504                              struct btrfs_root *root)
 505 {
 506         struct btrfs_root_item *item = &root->root_item;
 507         struct timespec ct = CURRENT_TIME;
 508
 509         spin_lock(&root->root_item_lock);
 510         item->ctransid = cpu_to_le64(trans->transid);
 511         item->ctime.sec = cpu_to_le64(ct.tv_sec);
 512         item->ctime.nsec = cpu_to_le32(ct.tv_nsec);
 513         spin_unlock(&root->root_item_lock);
 514 }