1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2007 Oracle. All rights reserved.
7 #include <linux/uuid.h>
9 #include "transaction.h"
11 #include "print-tree.h"
14 * Read a root item from the tree. In case we detect a root item smaller then
15 * sizeof(root_item), we know it's an old version of the root structure and
16 * initialize all new fields to zero. The same happens if we detect mismatching
17 * generation numbers as then we know the root was once mounted with an older
18 * kernel that was not aware of the root item structure change.
20 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
21 struct btrfs_root_item *item)
27 len = btrfs_item_size_nr(eb, slot);
28 read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
29 min_t(u32, len, sizeof(*item)));
30 if (len < sizeof(*item))
32 if (!need_reset && btrfs_root_generation(item)
33 != btrfs_root_generation_v2(item)) {
34 if (btrfs_root_generation_v2(item) != 0) {
35 btrfs_warn(eb->fs_info,
36 "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
41 memset(&item->generation_v2, 0,
42 sizeof(*item) - offsetof(struct btrfs_root_item,
46 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
51 * btrfs_find_root - lookup the root by the key.
52 * root: the root of the root tree
53 * search_key: the key to search
54 * path: the path we search
55 * root_item: the root item of the tree we look for
56 * root_key: the root key of the tree we look for
58 * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
59 * of the search key, just lookup the root with the highest offset for a
62 * If we find something return 0, otherwise > 0, < 0 on error.
64 int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
65 struct btrfs_path *path, struct btrfs_root_item *root_item,
66 struct btrfs_key *root_key)
68 struct btrfs_key found_key;
69 struct extent_buffer *l;
73 ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
77 if (search_key->offset != -1ULL) { /* the search key is exact */
81 BUG_ON(ret == 0); /* Logical error */
82 if (path->slots[0] == 0)
89 slot = path->slots[0];
91 btrfs_item_key_to_cpu(l, &found_key, slot);
92 if (found_key.objectid != search_key->objectid ||
93 found_key.type != BTRFS_ROOT_ITEM_KEY) {
99 btrfs_read_root_item(l, slot, root_item);
101 memcpy(root_key, &found_key, sizeof(found_key));
103 btrfs_release_path(path);
107 void btrfs_set_root_node(struct btrfs_root_item *item,
108 struct extent_buffer *node)
110 btrfs_set_root_bytenr(item, node->start);
111 btrfs_set_root_level(item, btrfs_header_level(node));
112 btrfs_set_root_generation(item, btrfs_header_generation(node));
116 * copy the data in 'item' into the btree
118 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
119 *root, struct btrfs_key *key, struct btrfs_root_item
122 struct btrfs_fs_info *fs_info = root->fs_info;
123 struct btrfs_path *path;
124 struct extent_buffer *l;
130 path = btrfs_alloc_path();
134 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
140 "unable to find root key (%llu %u %llu) in tree %llu",
141 key->objectid, key->type, key->offset,
142 root->root_key.objectid);
144 btrfs_abort_transaction(trans, ret);
149 slot = path->slots[0];
150 ptr = btrfs_item_ptr_offset(l, slot);
151 old_len = btrfs_item_size_nr(l, slot);
154 * If this is the first time we update the root item which originated
155 * from an older kernel, we need to enlarge the item size to make room
156 * for the added fields.
158 if (old_len < sizeof(*item)) {
159 btrfs_release_path(path);
160 ret = btrfs_search_slot(trans, root, key, path,
163 btrfs_abort_transaction(trans, ret);
167 ret = btrfs_del_item(trans, root, path);
169 btrfs_abort_transaction(trans, ret);
172 btrfs_release_path(path);
173 ret = btrfs_insert_empty_item(trans, root, path,
176 btrfs_abort_transaction(trans, ret);
180 slot = path->slots[0];
181 ptr = btrfs_item_ptr_offset(l, slot);
185 * Update generation_v2 so at the next mount we know the new root
188 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
190 write_extent_buffer(l, item, ptr, sizeof(*item));
191 btrfs_mark_buffer_dirty(path->nodes[0]);
193 btrfs_free_path(path);
197 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
198 const struct btrfs_key *key, struct btrfs_root_item *item)
201 * Make sure generation v1 and v2 match. See update_root for details.
203 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
204 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
207 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
209 struct btrfs_root *tree_root = fs_info->tree_root;
210 struct extent_buffer *leaf;
211 struct btrfs_path *path;
212 struct btrfs_key key;
213 struct btrfs_key root_key;
214 struct btrfs_root *root;
218 path = btrfs_alloc_path();
222 key.objectid = BTRFS_ORPHAN_OBJECTID;
223 key.type = BTRFS_ORPHAN_ITEM_KEY;
226 root_key.type = BTRFS_ROOT_ITEM_KEY;
227 root_key.offset = (u64)-1;
230 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
236 leaf = path->nodes[0];
237 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
238 ret = btrfs_next_leaf(tree_root, path);
243 leaf = path->nodes[0];
246 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
247 btrfs_release_path(path);
249 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
250 key.type != BTRFS_ORPHAN_ITEM_KEY)
253 root_key.objectid = key.offset;
257 * The root might have been inserted already, as before we look
258 * for orphan roots, log replay might have happened, which
259 * triggers a transaction commit and qgroup accounting, which
260 * in turn reads and inserts fs roots while doing backref
263 root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
265 WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
267 if (btrfs_root_refs(&root->root_item) == 0) {
268 set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
269 btrfs_add_dead_root(root);
274 root = btrfs_read_fs_root(tree_root, &root_key);
275 err = PTR_ERR_OR_ZERO(root);
276 if (err && err != -ENOENT) {
278 } else if (err == -ENOENT) {
279 struct btrfs_trans_handle *trans;
281 btrfs_release_path(path);
283 trans = btrfs_join_transaction(tree_root);
285 err = PTR_ERR(trans);
286 btrfs_handle_fs_error(fs_info, err,
287 "Failed to start trans to delete orphan item");
290 err = btrfs_del_orphan_item(trans, tree_root,
292 btrfs_end_transaction(trans);
294 btrfs_handle_fs_error(fs_info, err,
295 "Failed to delete root orphan item");
301 err = btrfs_init_fs_root(root);
303 btrfs_free_fs_root(root);
307 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
309 err = btrfs_insert_fs_root(fs_info, root);
311 BUG_ON(err == -EEXIST);
312 btrfs_free_fs_root(root);
316 if (btrfs_root_refs(&root->root_item) == 0) {
317 set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
318 btrfs_add_dead_root(root);
322 btrfs_free_path(path);
326 /* drop the root item for 'key' from the tree root */
327 int btrfs_del_root(struct btrfs_trans_handle *trans,
328 const struct btrfs_key *key)
330 struct btrfs_root *root = trans->fs_info->tree_root;
331 struct btrfs_path *path;
334 path = btrfs_alloc_path();
337 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
343 ret = btrfs_del_item(trans, root, path);
345 btrfs_free_path(path);
349 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
350 u64 ref_id, u64 dirid, u64 *sequence, const char *name,
354 struct btrfs_root *tree_root = trans->fs_info->tree_root;
355 struct btrfs_path *path;
356 struct btrfs_root_ref *ref;
357 struct extent_buffer *leaf;
358 struct btrfs_key key;
363 path = btrfs_alloc_path();
367 key.objectid = root_id;
368 key.type = BTRFS_ROOT_BACKREF_KEY;
371 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
374 leaf = path->nodes[0];
375 ref = btrfs_item_ptr(leaf, path->slots[0],
376 struct btrfs_root_ref);
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);
384 ret = btrfs_del_item(trans, tree_root, path);
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;
401 btrfs_free_path(path);
406 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
407 * or BTRFS_ROOT_BACKREF_KEY.
409 * The dirid, sequence, name and name_len refer to the directory entry
410 * that is referencing the root.
412 * For a forward ref, the root_id is the id of the tree referencing
413 * the root and ref_id is the id of the subvol or snapshot.
415 * For a back ref the root_id is the id of the subvol or snapshot and
416 * ref_id is the id of the tree referencing it.
418 * Will return 0, -ENOMEM, or anything from the CoW path
420 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
421 u64 ref_id, u64 dirid, u64 sequence, const char *name,
424 struct btrfs_root *tree_root = trans->fs_info->tree_root;
425 struct btrfs_key key;
427 struct btrfs_path *path;
428 struct btrfs_root_ref *ref;
429 struct extent_buffer *leaf;
432 path = btrfs_alloc_path();
436 key.objectid = root_id;
437 key.type = BTRFS_ROOT_BACKREF_KEY;
440 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
441 sizeof(*ref) + name_len);
443 btrfs_abort_transaction(trans, ret);
444 btrfs_free_path(path);
448 leaf = path->nodes[0];
449 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
450 btrfs_set_root_ref_dirid(leaf, ref, dirid);
451 btrfs_set_root_ref_sequence(leaf, ref, sequence);
452 btrfs_set_root_ref_name_len(leaf, ref, name_len);
453 ptr = (unsigned long)(ref + 1);
454 write_extent_buffer(leaf, name, ptr, name_len);
455 btrfs_mark_buffer_dirty(leaf);
457 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
458 btrfs_release_path(path);
459 key.objectid = ref_id;
460 key.type = BTRFS_ROOT_REF_KEY;
461 key.offset = root_id;
465 btrfs_free_path(path);
470 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
471 * for subvolumes. To work around this problem, we steal a bit from
472 * root_item->inode_item->flags, and use it to indicate if those fields
473 * have been properly initialized.
475 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
477 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
479 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
480 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
481 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
482 btrfs_set_root_flags(root_item, 0);
483 btrfs_set_root_limit(root_item, 0);
487 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
488 struct btrfs_root *root)
490 struct btrfs_root_item *item = &root->root_item;
491 struct timespec64 ct;
493 ktime_get_real_ts64(&ct);
494 spin_lock(&root->root_item_lock);
495 btrfs_set_root_ctransid(item, trans->transid);
496 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
497 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
498 spin_unlock(&root->root_item_lock);