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                         printk(KERN_WARNING "BTRFS: mismatching "
  49                                         "generation and generation_v2 "
  50                                         "found in root item. This root "
  51                                         "was probably mounted with an "
  52                                         "older kernel. Resetting all "
  53                                         "new fields.\n");
  54                 }
  55                 need_reset = 1;
  56         }
  57         if (need_reset) {
  58                 memset(&item->generation_v2, 0,
  59                         sizeof(*item) - offsetof(struct btrfs_root_item,
  60                                         generation_v2));
  61
  62                 uuid_le_gen(&uuid);
  63                 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
  64         }
  65 }
  66
  67 /*
  68  * btrfs_find_root - lookup the root by the key.
  69  * root: the root of the root tree
  70  * search_key: the key to search
  71  * path: the path we search
  72  * root_item: the root item of the tree we look for
  73  * root_key: the reak key of the tree we look for
  74  *
  75  * If ->offset of 'seach_key' is -1ULL, it means we are not sure the offset
  76  * of the search key, just lookup the root with the highest offset for a
  77  * given objectid.
  78  *
  79  * If we find something return 0, otherwise > 0, < 0 on error.
  80  */
  81 int btrfs_find_root(struct btrfs_root *root, struct btrfs_key *search_key,
  82                     struct btrfs_path *path, struct btrfs_root_item *root_item,
  83                     struct btrfs_key *root_key)
  84 {
  85         struct btrfs_key found_key;
  86         struct extent_buffer *l;
  87         int ret;
  88         int slot;
  89
  90         ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
  91         if (ret < 0)
  92                 return ret;
  93
  94         if (search_key->offset != -1ULL) {      /* the search key is exact */
  95                 if (ret > 0)
  96                         goto out;
  97         } else {
  98                 BUG_ON(ret == 0);               /* Logical error */
  99                 if (path->slots[0] == 0)
 100                         goto out;
 101                 path->slots[0]--;
 102                 ret = 0;
 103         }
 104
 105         l = path->nodes[0];
 106         slot = path->slots[0];
 107
 108         btrfs_item_key_to_cpu(l, &found_key, slot);
 109         if (found_key.objectid != search_key->objectid ||
 110             found_key.type != BTRFS_ROOT_ITEM_KEY) {
 111                 ret = 1;
 112                 goto out;
 113         }
 114
 115         if (root_item)
 116                 btrfs_read_root_item(l, slot, root_item);
 117         if (root_key)
 118                 memcpy(root_key, &found_key, sizeof(found_key));
 119 out:
 120         btrfs_release_path(path);
 121         return ret;
 122 }
 123
 124 void btrfs_set_root_node(struct btrfs_root_item *item,
 125                          struct extent_buffer *node)
 126 {
 127         btrfs_set_root_bytenr(item, node->start);
 128         btrfs_set_root_level(item, btrfs_header_level(node));
 129         btrfs_set_root_generation(item, btrfs_header_generation(node));
 130 }
 131
 132 /*
 133  * copy the data in 'item' into the btree
 134  */
 135 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
 136                       *root, struct btrfs_key *key, struct btrfs_root_item
 137                       *item)
 138 {
 139         struct btrfs_path *path;
 140         struct extent_buffer *l;
 141         int ret;
 142         int slot;
 143         unsigned long ptr;
 144         int old_len;
 145
 146         path = btrfs_alloc_path();
 147         if (!path)
 148                 return -ENOMEM;
 149
 150         ret = btrfs_search_slot(trans, root, key, path, 0, 1);
 151         if (ret < 0) {
 152                 btrfs_abort_transaction(trans, root, ret);
 153                 goto out;
 154         }
 155
 156         if (ret != 0) {
 157                 btrfs_print_leaf(root, path->nodes[0]);
 158                 btrfs_crit(root->fs_info, "unable to update root key %llu %u %llu",
 159                        key->objectid, key->type, 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_ERR_OR_ZERO(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                 err = btrfs_init_fs_root(root);
 304                 if (err) {
 305                         btrfs_free_fs_root(root);
 306                         break;
 307                 }
 308
 309                 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
 310
 311                 err = btrfs_insert_fs_root(root->fs_info, root);
 312                 if (err) {
 313                         BUG_ON(err == -EEXIST);
 314                         btrfs_free_fs_root(root);
 315                         break;
 316                 }
 317
 318                 if (btrfs_root_refs(&root->root_item) == 0)
 319                         btrfs_add_dead_root(root);
 320         }
 321
 322         btrfs_free_path(path);
 323         return err;
 324 }
 325
 326 /* drop the root item for 'key' from 'root' */
 327 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
 328                    struct btrfs_key *key)
 329 {
 330         struct btrfs_path *path;
 331         int ret;
 332
 333         path = btrfs_alloc_path();
 334         if (!path)
 335                 return -ENOMEM;
 336         ret = btrfs_search_slot(trans, root, key, path, -1, 1);
 337         if (ret < 0)
 338                 goto out;
 339
 340         BUG_ON(ret != 0);
 341
 342         ret = btrfs_del_item(trans, root, path);
 343 out:
 344         btrfs_free_path(path);
 345         return ret;
 346 }
 347
 348 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
 349                        struct btrfs_root *tree_root,
 350                        u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
 351                        const char *name, int name_len)
 352
 353 {
 354         struct btrfs_path *path;
 355         struct btrfs_root_ref *ref;
 356         struct extent_buffer *leaf;
 357         struct btrfs_key key;
 358         unsigned long ptr;
 359         int err = 0;
 360         int ret;
 361
 362         path = btrfs_alloc_path();
 363         if (!path)
 364                 return -ENOMEM;
 365
 366         key.objectid = root_id;
 367         key.type = BTRFS_ROOT_BACKREF_KEY;
 368         key.offset = ref_id;
 369 again:
 370         ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
 371         BUG_ON(ret < 0);
 372         if (ret == 0) {
 373                 leaf = path->nodes[0];
 374                 ref = btrfs_item_ptr(leaf, path->slots[0],
 375                                      struct btrfs_root_ref);
 376
 377                 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
 378                 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 379                 ptr = (unsigned long)(ref + 1);
 380                 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
 381                 *sequence = btrfs_root_ref_sequence(leaf, ref);
 382
 383                 ret = btrfs_del_item(trans, tree_root, path);
 384                 if (ret) {
 385                         err = ret;
 386                         goto out;
 387                 }
 388         } else
 389                 err = -ENOENT;
 390
 391         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 392                 btrfs_release_path(path);
 393                 key.objectid = ref_id;
 394                 key.type = BTRFS_ROOT_REF_KEY;
 395                 key.offset = root_id;
 396                 goto again;
 397         }
 398
 399 out:
 400         btrfs_free_path(path);
 401         return err;
 402 }
 403
 404 /*
 405  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
 406  * or BTRFS_ROOT_BACKREF_KEY.
 407  *
 408  * The dirid, sequence, name and name_len refer to the directory entry
 409  * that is referencing the root.
 410  *
 411  * For a forward ref, the root_id is the id of the tree referencing
 412  * the root and ref_id is the id of the subvol  or snapshot.
 413  *
 414  * For a back ref the root_id is the id of the subvol or snapshot and
 415  * ref_id is the id of the tree referencing it.
 416  *
 417  * Will return 0, -ENOMEM, or anything from the CoW path
 418  */
 419 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
 420                        struct btrfs_root *tree_root,
 421                        u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
 422                        const char *name, int name_len)
 423 {
 424         struct btrfs_key key;
 425         int ret;
 426         struct btrfs_path *path;
 427         struct btrfs_root_ref *ref;
 428         struct extent_buffer *leaf;
 429         unsigned long ptr;
 430
 431         path = btrfs_alloc_path();
 432         if (!path)
 433                 return -ENOMEM;
 434
 435         key.objectid = root_id;
 436         key.type = BTRFS_ROOT_BACKREF_KEY;
 437         key.offset = ref_id;
 438 again:
 439         ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
 440                                       sizeof(*ref) + name_len);
 441         if (ret) {
 442                 btrfs_abort_transaction(trans, tree_root, ret);
 443                 btrfs_free_path(path);
 444                 return ret;
 445         }
 446
 447         leaf = path->nodes[0];
 448         ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
 449         btrfs_set_root_ref_dirid(leaf, ref, dirid);
 450         btrfs_set_root_ref_sequence(leaf, ref, sequence);
 451         btrfs_set_root_ref_name_len(leaf, ref, name_len);
 452         ptr = (unsigned long)(ref + 1);
 453         write_extent_buffer(leaf, name, ptr, name_len);
 454         btrfs_mark_buffer_dirty(leaf);
 455
 456         if (key.type == BTRFS_ROOT_BACKREF_KEY) {
 457                 btrfs_release_path(path);
 458                 key.objectid = ref_id;
 459                 key.type = BTRFS_ROOT_REF_KEY;
 460                 key.offset = root_id;
 461                 goto again;
 462         }
 463
 464         btrfs_free_path(path);
 465         return 0;
 466 }
 467
 468 /*
 469  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
 470  * for subvolumes. To work around this problem, we steal a bit from
 471  * root_item->inode_item->flags, and use it to indicate if those fields
 472  * have been properly initialized.
 473  */
 474 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
 475 {
 476         u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
 477
 478         if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
 479                 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
 480                 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
 481                 btrfs_set_root_flags(root_item, 0);
 482                 btrfs_set_root_limit(root_item, 0);
 483         }
 484 }
 485
 486 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
 487                              struct btrfs_root *root)
 488 {
 489         struct btrfs_root_item *item = &root->root_item;
 490         struct timespec ct = CURRENT_TIME;
 491
 492         spin_lock(&root->root_item_lock);
 493         btrfs_set_root_ctransid(item, trans->transid);
 494         btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
 495         btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
 496         spin_unlock(&root->root_item_lock);
 497 }