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);
136 btrfs_abort_transaction(trans, ret);
141 btrfs_print_leaf(path->nodes[0]);
142 btrfs_crit(fs_info, "unable to update root key %llu %u %llu",
143 key->objectid, key->type, key->offset);
148 slot = path->slots[0];
149 ptr = btrfs_item_ptr_offset(l, slot);
150 old_len = btrfs_item_size_nr(l, slot);
153 * If this is the first time we update the root item which originated
154 * from an older kernel, we need to enlarge the item size to make room
155 * for the added fields.
157 if (old_len < sizeof(*item)) {
158 btrfs_release_path(path);
159 ret = btrfs_search_slot(trans, root, key, path,
162 btrfs_abort_transaction(trans, ret);
166 ret = btrfs_del_item(trans, root, path);
168 btrfs_abort_transaction(trans, ret);
171 btrfs_release_path(path);
172 ret = btrfs_insert_empty_item(trans, root, path,
175 btrfs_abort_transaction(trans, ret);
179 slot = path->slots[0];
180 ptr = btrfs_item_ptr_offset(l, slot);
184 * Update generation_v2 so at the next mount we know the new root
187 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
189 write_extent_buffer(l, item, ptr, sizeof(*item));
190 btrfs_mark_buffer_dirty(path->nodes[0]);
192 btrfs_free_path(path);
196 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
197 const struct btrfs_key *key, struct btrfs_root_item *item)
200 * Make sure generation v1 and v2 match. See update_root for details.
202 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
203 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
206 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
208 struct btrfs_root *tree_root = fs_info->tree_root;
209 struct extent_buffer *leaf;
210 struct btrfs_path *path;
211 struct btrfs_key key;
212 struct btrfs_key root_key;
213 struct btrfs_root *root;
217 path = btrfs_alloc_path();
221 key.objectid = BTRFS_ORPHAN_OBJECTID;
222 key.type = BTRFS_ORPHAN_ITEM_KEY;
225 root_key.type = BTRFS_ROOT_ITEM_KEY;
226 root_key.offset = (u64)-1;
229 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
235 leaf = path->nodes[0];
236 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
237 ret = btrfs_next_leaf(tree_root, path);
242 leaf = path->nodes[0];
245 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
246 btrfs_release_path(path);
248 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
249 key.type != BTRFS_ORPHAN_ITEM_KEY)
252 root_key.objectid = key.offset;
256 * The root might have been inserted already, as before we look
257 * for orphan roots, log replay might have happened, which
258 * triggers a transaction commit and qgroup accounting, which
259 * in turn reads and inserts fs roots while doing backref
262 root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
264 WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
266 if (btrfs_root_refs(&root->root_item) == 0)
267 btrfs_add_dead_root(root);
271 root = btrfs_read_fs_root(tree_root, &root_key);
272 err = PTR_ERR_OR_ZERO(root);
273 if (err && err != -ENOENT) {
275 } else if (err == -ENOENT) {
276 struct btrfs_trans_handle *trans;
278 btrfs_release_path(path);
280 trans = btrfs_join_transaction(tree_root);
282 err = PTR_ERR(trans);
283 btrfs_handle_fs_error(fs_info, err,
284 "Failed to start trans to delete orphan item");
287 err = btrfs_del_orphan_item(trans, tree_root,
289 btrfs_end_transaction(trans);
291 btrfs_handle_fs_error(fs_info, err,
292 "Failed to delete root orphan item");
298 err = btrfs_init_fs_root(root);
300 btrfs_free_fs_root(root);
304 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
306 err = btrfs_insert_fs_root(fs_info, root);
308 BUG_ON(err == -EEXIST);
309 btrfs_free_fs_root(root);
313 if (btrfs_root_refs(&root->root_item) == 0)
314 btrfs_add_dead_root(root);
317 btrfs_free_path(path);
321 /* drop the root item for 'key' from the tree root */
322 int btrfs_del_root(struct btrfs_trans_handle *trans,
323 const struct btrfs_key *key)
325 struct btrfs_root *root = trans->fs_info->tree_root;
326 struct btrfs_path *path;
329 path = btrfs_alloc_path();
332 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
338 ret = btrfs_del_item(trans, root, path);
340 btrfs_free_path(path);
344 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
345 u64 ref_id, u64 dirid, u64 *sequence, const char *name,
349 struct btrfs_root *tree_root = trans->fs_info->tree_root;
350 struct btrfs_path *path;
351 struct btrfs_root_ref *ref;
352 struct extent_buffer *leaf;
353 struct btrfs_key key;
358 path = btrfs_alloc_path();
362 key.objectid = root_id;
363 key.type = BTRFS_ROOT_BACKREF_KEY;
366 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
369 leaf = path->nodes[0];
370 ref = btrfs_item_ptr(leaf, path->slots[0],
371 struct btrfs_root_ref);
373 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
374 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
375 ptr = (unsigned long)(ref + 1);
376 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
377 *sequence = btrfs_root_ref_sequence(leaf, ref);
379 ret = btrfs_del_item(trans, tree_root, path);
387 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
388 btrfs_release_path(path);
389 key.objectid = ref_id;
390 key.type = BTRFS_ROOT_REF_KEY;
391 key.offset = root_id;
396 btrfs_free_path(path);
401 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
402 * or BTRFS_ROOT_BACKREF_KEY.
404 * The dirid, sequence, name and name_len refer to the directory entry
405 * that is referencing the root.
407 * For a forward ref, the root_id is the id of the tree referencing
408 * the root and ref_id is the id of the subvol or snapshot.
410 * For a back ref the root_id is the id of the subvol or snapshot and
411 * ref_id is the id of the tree referencing it.
413 * Will return 0, -ENOMEM, or anything from the CoW path
415 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
416 u64 ref_id, u64 dirid, u64 sequence, const char *name,
419 struct btrfs_root *tree_root = trans->fs_info->tree_root;
420 struct btrfs_key key;
422 struct btrfs_path *path;
423 struct btrfs_root_ref *ref;
424 struct extent_buffer *leaf;
427 path = btrfs_alloc_path();
431 key.objectid = root_id;
432 key.type = BTRFS_ROOT_BACKREF_KEY;
435 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
436 sizeof(*ref) + name_len);
438 btrfs_abort_transaction(trans, ret);
439 btrfs_free_path(path);
443 leaf = path->nodes[0];
444 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
445 btrfs_set_root_ref_dirid(leaf, ref, dirid);
446 btrfs_set_root_ref_sequence(leaf, ref, sequence);
447 btrfs_set_root_ref_name_len(leaf, ref, name_len);
448 ptr = (unsigned long)(ref + 1);
449 write_extent_buffer(leaf, name, ptr, name_len);
450 btrfs_mark_buffer_dirty(leaf);
452 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
453 btrfs_release_path(path);
454 key.objectid = ref_id;
455 key.type = BTRFS_ROOT_REF_KEY;
456 key.offset = root_id;
460 btrfs_free_path(path);
465 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
466 * for subvolumes. To work around this problem, we steal a bit from
467 * root_item->inode_item->flags, and use it to indicate if those fields
468 * have been properly initialized.
470 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
472 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
474 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
475 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
476 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
477 btrfs_set_root_flags(root_item, 0);
478 btrfs_set_root_limit(root_item, 0);
482 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
483 struct btrfs_root *root)
485 struct btrfs_root_item *item = &root->root_item;
486 struct timespec64 ct;
488 ktime_get_real_ts64(&ct);
489 spin_lock(&root->root_item_lock);
490 btrfs_set_root_ctransid(item, trans->transid);
491 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
492 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
493 spin_unlock(&root->root_item_lock);