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"
13 #include "space-info.h"
16 * Read a root item from the tree. In case we detect a root item smaller then
17 * sizeof(root_item), we know it's an old version of the root structure and
18 * initialize all new fields to zero. The same happens if we detect mismatching
19 * generation numbers as then we know the root was once mounted with an older
20 * kernel that was not aware of the root item structure change.
22 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
23 struct btrfs_root_item *item)
28 len = btrfs_item_size(eb, slot);
29 read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
30 min_t(u32, len, sizeof(*item)));
31 if (len < sizeof(*item))
33 if (!need_reset && btrfs_root_generation(item)
34 != btrfs_root_generation_v2(item)) {
35 if (btrfs_root_generation_v2(item) != 0) {
36 btrfs_warn(eb->fs_info,
37 "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
42 /* Clear all members from generation_v2 onwards. */
43 memset_startat(item, 0, generation_v2);
44 generate_random_guid(item->uuid);
49 * btrfs_find_root - lookup the root by the key.
50 * root: the root of the root tree
51 * search_key: the key to search
52 * path: the path we search
53 * root_item: the root item of the tree we look for
54 * root_key: the root key of the tree we look for
56 * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
57 * of the search key, just lookup the root with the highest offset for a
60 * If we find something return 0, otherwise > 0, < 0 on error.
62 int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
63 struct btrfs_path *path, struct btrfs_root_item *root_item,
64 struct btrfs_key *root_key)
66 struct btrfs_key found_key;
67 struct extent_buffer *l;
71 ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
75 if (search_key->offset != -1ULL) { /* the search key is exact */
79 BUG_ON(ret == 0); /* Logical error */
80 if (path->slots[0] == 0)
87 slot = path->slots[0];
89 btrfs_item_key_to_cpu(l, &found_key, slot);
90 if (found_key.objectid != search_key->objectid ||
91 found_key.type != BTRFS_ROOT_ITEM_KEY) {
97 btrfs_read_root_item(l, slot, root_item);
99 memcpy(root_key, &found_key, sizeof(found_key));
101 btrfs_release_path(path);
105 void btrfs_set_root_node(struct btrfs_root_item *item,
106 struct extent_buffer *node)
108 btrfs_set_root_bytenr(item, node->start);
109 btrfs_set_root_level(item, btrfs_header_level(node));
110 btrfs_set_root_generation(item, btrfs_header_generation(node));
114 * copy the data in 'item' into the btree
116 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
117 *root, struct btrfs_key *key, struct btrfs_root_item
120 struct btrfs_fs_info *fs_info = root->fs_info;
121 struct btrfs_path *path;
122 struct extent_buffer *l;
128 path = btrfs_alloc_path();
132 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
138 "unable to find root key (%llu %u %llu) in tree %llu",
139 key->objectid, key->type, key->offset,
140 root->root_key.objectid);
142 btrfs_abort_transaction(trans, ret);
147 slot = path->slots[0];
148 ptr = btrfs_item_ptr_offset(l, slot);
149 old_len = btrfs_item_size(l, slot);
152 * If this is the first time we update the root item which originated
153 * from an older kernel, we need to enlarge the item size to make room
154 * for the added fields.
156 if (old_len < sizeof(*item)) {
157 btrfs_release_path(path);
158 ret = btrfs_search_slot(trans, root, key, path,
161 btrfs_abort_transaction(trans, ret);
165 ret = btrfs_del_item(trans, root, path);
167 btrfs_abort_transaction(trans, ret);
170 btrfs_release_path(path);
171 ret = btrfs_insert_empty_item(trans, root, path,
174 btrfs_abort_transaction(trans, ret);
178 slot = path->slots[0];
179 ptr = btrfs_item_ptr_offset(l, slot);
183 * Update generation_v2 so at the next mount we know the new root
186 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
188 write_extent_buffer(l, item, ptr, sizeof(*item));
189 btrfs_mark_buffer_dirty(path->nodes[0]);
191 btrfs_free_path(path);
195 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
196 const struct btrfs_key *key, struct btrfs_root_item *item)
199 * Make sure generation v1 and v2 match. See update_root for details.
201 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
202 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
205 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
207 struct btrfs_root *tree_root = fs_info->tree_root;
208 struct extent_buffer *leaf;
209 struct btrfs_path *path;
210 struct btrfs_key key;
211 struct btrfs_root *root;
215 path = btrfs_alloc_path();
219 key.objectid = BTRFS_ORPHAN_OBJECTID;
220 key.type = BTRFS_ORPHAN_ITEM_KEY;
226 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
232 leaf = path->nodes[0];
233 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
234 ret = btrfs_next_leaf(tree_root, path);
239 leaf = path->nodes[0];
242 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
243 btrfs_release_path(path);
245 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
246 key.type != BTRFS_ORPHAN_ITEM_KEY)
249 root_objectid = key.offset;
252 root = btrfs_get_fs_root(fs_info, root_objectid, false);
253 err = PTR_ERR_OR_ZERO(root);
254 if (err && err != -ENOENT) {
256 } else if (err == -ENOENT) {
257 struct btrfs_trans_handle *trans;
259 btrfs_release_path(path);
261 trans = btrfs_join_transaction(tree_root);
263 err = PTR_ERR(trans);
264 btrfs_handle_fs_error(fs_info, err,
265 "Failed to start trans to delete orphan item");
268 err = btrfs_del_orphan_item(trans, tree_root,
270 btrfs_end_transaction(trans);
272 btrfs_handle_fs_error(fs_info, err,
273 "Failed to delete root orphan item");
279 WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state));
280 if (btrfs_root_refs(&root->root_item) == 0) {
281 set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
282 btrfs_add_dead_root(root);
284 btrfs_put_root(root);
287 btrfs_free_path(path);
291 /* drop the root item for 'key' from the tree root */
292 int btrfs_del_root(struct btrfs_trans_handle *trans,
293 const struct btrfs_key *key)
295 struct btrfs_root *root = trans->fs_info->tree_root;
296 struct btrfs_path *path;
299 path = btrfs_alloc_path();
302 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
308 ret = btrfs_del_item(trans, root, path);
310 btrfs_free_path(path);
314 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
315 u64 ref_id, u64 dirid, u64 *sequence, const char *name,
319 struct btrfs_root *tree_root = trans->fs_info->tree_root;
320 struct btrfs_path *path;
321 struct btrfs_root_ref *ref;
322 struct extent_buffer *leaf;
323 struct btrfs_key key;
328 path = btrfs_alloc_path();
332 key.objectid = root_id;
333 key.type = BTRFS_ROOT_BACKREF_KEY;
336 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
340 leaf = path->nodes[0];
341 ref = btrfs_item_ptr(leaf, path->slots[0],
342 struct btrfs_root_ref);
343 ptr = (unsigned long)(ref + 1);
344 if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
345 (btrfs_root_ref_name_len(leaf, ref) != name_len) ||
346 memcmp_extent_buffer(leaf, name, ptr, name_len)) {
350 *sequence = btrfs_root_ref_sequence(leaf, ref);
352 ret = btrfs_del_item(trans, tree_root, path);
360 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
361 btrfs_release_path(path);
362 key.objectid = ref_id;
363 key.type = BTRFS_ROOT_REF_KEY;
364 key.offset = root_id;
369 btrfs_free_path(path);
374 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
375 * or BTRFS_ROOT_BACKREF_KEY.
377 * The dirid, sequence, name and name_len refer to the directory entry
378 * that is referencing the root.
380 * For a forward ref, the root_id is the id of the tree referencing
381 * the root and ref_id is the id of the subvol or snapshot.
383 * For a back ref the root_id is the id of the subvol or snapshot and
384 * ref_id is the id of the tree referencing it.
386 * Will return 0, -ENOMEM, or anything from the CoW path
388 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
389 u64 ref_id, u64 dirid, u64 sequence, const char *name,
392 struct btrfs_root *tree_root = trans->fs_info->tree_root;
393 struct btrfs_key key;
395 struct btrfs_path *path;
396 struct btrfs_root_ref *ref;
397 struct extent_buffer *leaf;
400 path = btrfs_alloc_path();
404 key.objectid = root_id;
405 key.type = BTRFS_ROOT_BACKREF_KEY;
408 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
409 sizeof(*ref) + name_len);
411 btrfs_abort_transaction(trans, ret);
412 btrfs_free_path(path);
416 leaf = path->nodes[0];
417 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
418 btrfs_set_root_ref_dirid(leaf, ref, dirid);
419 btrfs_set_root_ref_sequence(leaf, ref, sequence);
420 btrfs_set_root_ref_name_len(leaf, ref, name_len);
421 ptr = (unsigned long)(ref + 1);
422 write_extent_buffer(leaf, name, ptr, name_len);
423 btrfs_mark_buffer_dirty(leaf);
425 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
426 btrfs_release_path(path);
427 key.objectid = ref_id;
428 key.type = BTRFS_ROOT_REF_KEY;
429 key.offset = root_id;
433 btrfs_free_path(path);
438 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
439 * for subvolumes. To work around this problem, we steal a bit from
440 * root_item->inode_item->flags, and use it to indicate if those fields
441 * have been properly initialized.
443 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
445 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
447 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
448 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
449 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
450 btrfs_set_root_flags(root_item, 0);
451 btrfs_set_root_limit(root_item, 0);
455 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
456 struct btrfs_root *root)
458 struct btrfs_root_item *item = &root->root_item;
459 struct timespec64 ct;
461 ktime_get_real_ts64(&ct);
462 spin_lock(&root->root_item_lock);
463 btrfs_set_root_ctransid(item, trans->transid);
464 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
465 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
466 spin_unlock(&root->root_item_lock);
470 * btrfs_subvolume_reserve_metadata() - reserve space for subvolume operation
471 * root: the root of the parent directory
472 * rsv: block reservation
473 * items: the number of items that we need do reservation
474 * use_global_rsv: allow fallback to the global block reservation
476 * This function is used to reserve the space for snapshot/subvolume
477 * creation and deletion. Those operations are different with the
478 * common file/directory operations, they change two fs/file trees
479 * and root tree, the number of items that the qgroup reserves is
480 * different with the free space reservation. So we can not use
481 * the space reservation mechanism in start_transaction().
483 int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
484 struct btrfs_block_rsv *rsv, int items,
487 u64 qgroup_num_bytes = 0;
490 struct btrfs_fs_info *fs_info = root->fs_info;
491 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
493 if (test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags)) {
494 /* One for parent inode, two for dir entries */
495 qgroup_num_bytes = 3 * fs_info->nodesize;
496 ret = btrfs_qgroup_reserve_meta_prealloc(root,
497 qgroup_num_bytes, true);
502 num_bytes = btrfs_calc_insert_metadata_size(fs_info, items);
503 rsv->space_info = btrfs_find_space_info(fs_info,
504 BTRFS_BLOCK_GROUP_METADATA);
505 ret = btrfs_block_rsv_add(fs_info, rsv, num_bytes,
506 BTRFS_RESERVE_FLUSH_ALL);
508 if (ret == -ENOSPC && use_global_rsv)
509 ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, true);
511 if (ret && qgroup_num_bytes)
512 btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
515 spin_lock(&rsv->lock);
516 rsv->qgroup_rsv_reserved += qgroup_num_bytes;
517 spin_unlock(&rsv->lock);
522 void btrfs_subvolume_release_metadata(struct btrfs_root *root,
523 struct btrfs_block_rsv *rsv)
525 struct btrfs_fs_info *fs_info = root->fs_info;
526 u64 qgroup_to_release;
528 btrfs_block_rsv_release(fs_info, rsv, (u64)-1, &qgroup_to_release);
529 btrfs_qgroup_convert_reserved_meta(root, qgroup_to_release);