1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (C) 2007 Oracle. All rights reserved.
7 #include <linux/uuid.h>
11 #include "transaction.h"
14 #include "space-info.h"
15 #include "accessors.h"
16 #include "root-tree.h"
20 * Read a root item from the tree. In case we detect a root item smaller then
21 * sizeof(root_item), we know it's an old version of the root structure and
22 * initialize all new fields to zero. The same happens if we detect mismatching
23 * generation numbers as then we know the root was once mounted with an older
24 * kernel that was not aware of the root item structure change.
26 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
27 struct btrfs_root_item *item)
32 len = btrfs_item_size(eb, slot);
33 read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
34 min_t(u32, len, sizeof(*item)));
35 if (len < sizeof(*item))
37 if (!need_reset && btrfs_root_generation(item)
38 != btrfs_root_generation_v2(item)) {
39 if (btrfs_root_generation_v2(item) != 0) {
40 btrfs_warn(eb->fs_info,
41 "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
46 /* Clear all members from generation_v2 onwards. */
47 memset_startat(item, 0, generation_v2);
48 generate_random_guid(item->uuid);
53 * Lookup the root by the key.
55 * root: the root of the root tree
56 * search_key: the key to search
57 * path: the path we search
58 * root_item: the root item of the tree we look for
59 * root_key: the root key of the tree we look for
61 * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
62 * of the search key, just lookup the root with the highest offset for a
65 * If we find something return 0, otherwise > 0, < 0 on error.
67 int btrfs_find_root(struct btrfs_root *root, const struct btrfs_key *search_key,
68 struct btrfs_path *path, struct btrfs_root_item *root_item,
69 struct btrfs_key *root_key)
71 struct btrfs_key found_key;
72 struct extent_buffer *l;
76 ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
80 if (search_key->offset != -1ULL) { /* the search key is exact */
85 * Key with offset -1 found, there would have to exist a root
86 * with such id, but this is out of the valid range.
92 if (path->slots[0] == 0)
99 slot = path->slots[0];
101 btrfs_item_key_to_cpu(l, &found_key, slot);
102 if (found_key.objectid != search_key->objectid ||
103 found_key.type != BTRFS_ROOT_ITEM_KEY) {
109 btrfs_read_root_item(l, slot, root_item);
111 memcpy(root_key, &found_key, sizeof(found_key));
113 btrfs_release_path(path);
117 void btrfs_set_root_node(struct btrfs_root_item *item,
118 struct extent_buffer *node)
120 btrfs_set_root_bytenr(item, node->start);
121 btrfs_set_root_level(item, btrfs_header_level(node));
122 btrfs_set_root_generation(item, btrfs_header_generation(node));
126 * copy the data in 'item' into the btree
128 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
129 *root, struct btrfs_key *key, struct btrfs_root_item
132 struct btrfs_fs_info *fs_info = root->fs_info;
133 struct btrfs_path *path;
134 struct extent_buffer *l;
140 path = btrfs_alloc_path();
144 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
150 "unable to find root key (%llu %u %llu) in tree %llu",
151 key->objectid, key->type, key->offset,
152 root->root_key.objectid);
154 btrfs_abort_transaction(trans, ret);
159 slot = path->slots[0];
160 ptr = btrfs_item_ptr_offset(l, slot);
161 old_len = btrfs_item_size(l, slot);
164 * If this is the first time we update the root item which originated
165 * from an older kernel, we need to enlarge the item size to make room
166 * for the added fields.
168 if (old_len < sizeof(*item)) {
169 btrfs_release_path(path);
170 ret = btrfs_search_slot(trans, root, key, path,
173 btrfs_abort_transaction(trans, ret);
177 ret = btrfs_del_item(trans, root, path);
179 btrfs_abort_transaction(trans, ret);
182 btrfs_release_path(path);
183 ret = btrfs_insert_empty_item(trans, root, path,
186 btrfs_abort_transaction(trans, ret);
190 slot = path->slots[0];
191 ptr = btrfs_item_ptr_offset(l, slot);
195 * Update generation_v2 so at the next mount we know the new root
198 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
200 write_extent_buffer(l, item, ptr, sizeof(*item));
201 btrfs_mark_buffer_dirty(trans, path->nodes[0]);
203 btrfs_free_path(path);
207 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
208 const struct btrfs_key *key, struct btrfs_root_item *item)
211 * Make sure generation v1 and v2 match. See update_root for details.
213 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
214 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
217 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
219 struct btrfs_root *tree_root = fs_info->tree_root;
220 struct extent_buffer *leaf;
221 struct btrfs_path *path;
222 struct btrfs_key key;
223 struct btrfs_root *root;
227 path = btrfs_alloc_path();
231 key.objectid = BTRFS_ORPHAN_OBJECTID;
232 key.type = BTRFS_ORPHAN_ITEM_KEY;
238 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
244 leaf = path->nodes[0];
245 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
246 ret = btrfs_next_leaf(tree_root, path);
251 leaf = path->nodes[0];
254 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
255 btrfs_release_path(path);
257 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
258 key.type != BTRFS_ORPHAN_ITEM_KEY)
261 root_objectid = key.offset;
264 root = btrfs_get_fs_root(fs_info, root_objectid, false);
265 err = PTR_ERR_OR_ZERO(root);
266 if (err && err != -ENOENT) {
268 } else if (err == -ENOENT) {
269 struct btrfs_trans_handle *trans;
271 btrfs_release_path(path);
273 trans = btrfs_join_transaction(tree_root);
275 err = PTR_ERR(trans);
276 btrfs_handle_fs_error(fs_info, err,
277 "Failed to start trans to delete orphan item");
280 err = btrfs_del_orphan_item(trans, tree_root,
282 btrfs_end_transaction(trans);
284 btrfs_handle_fs_error(fs_info, err,
285 "Failed to delete root orphan item");
291 WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state));
292 if (btrfs_root_refs(&root->root_item) == 0) {
293 struct btrfs_key drop_key;
295 btrfs_disk_key_to_cpu(&drop_key, &root->root_item.drop_progress);
297 * If we have a non-zero drop_progress then we know we
298 * made it partly through deleting this snapshot, and
299 * thus we need to make sure we block any balance from
300 * happening until this snapshot is completely dropped.
302 if (drop_key.objectid != 0 || drop_key.type != 0 ||
303 drop_key.offset != 0) {
304 set_bit(BTRFS_FS_UNFINISHED_DROPS, &fs_info->flags);
305 set_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state);
308 set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
309 btrfs_add_dead_root(root);
311 btrfs_put_root(root);
314 btrfs_free_path(path);
318 /* drop the root item for 'key' from the tree root */
319 int btrfs_del_root(struct btrfs_trans_handle *trans,
320 const struct btrfs_key *key)
322 struct btrfs_root *root = trans->fs_info->tree_root;
323 struct btrfs_path *path;
326 path = btrfs_alloc_path();
329 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
333 /* The root must exist but we did not find it by the key. */
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,
346 const struct fscrypt_str *name)
348 struct btrfs_root *tree_root = trans->fs_info->tree_root;
349 struct btrfs_path *path;
350 struct btrfs_root_ref *ref;
351 struct extent_buffer *leaf;
352 struct btrfs_key key;
356 path = btrfs_alloc_path();
360 key.objectid = root_id;
361 key.type = BTRFS_ROOT_BACKREF_KEY;
364 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
367 } else if (ret == 0) {
368 leaf = path->nodes[0];
369 ref = btrfs_item_ptr(leaf, path->slots[0],
370 struct btrfs_root_ref);
371 ptr = (unsigned long)(ref + 1);
372 if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
373 (btrfs_root_ref_name_len(leaf, ref) != name->len) ||
374 memcmp_extent_buffer(leaf, name->name, ptr, name->len)) {
378 *sequence = btrfs_root_ref_sequence(leaf, ref);
380 ret = btrfs_del_item(trans, tree_root, path);
388 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
389 btrfs_release_path(path);
390 key.objectid = ref_id;
391 key.type = BTRFS_ROOT_REF_KEY;
392 key.offset = root_id;
397 btrfs_free_path(path);
402 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
403 * or BTRFS_ROOT_BACKREF_KEY.
405 * The dirid, sequence, name and name_len refer to the directory entry
406 * that is referencing the root.
408 * For a forward ref, the root_id is the id of the tree referencing
409 * the root and ref_id is the id of the subvol or snapshot.
411 * For a back ref the root_id is the id of the subvol or snapshot and
412 * ref_id is the id of the tree referencing it.
414 * Will return 0, -ENOMEM, or anything from the CoW path
416 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
417 u64 ref_id, u64 dirid, u64 sequence,
418 const struct fscrypt_str *name)
420 struct btrfs_root *tree_root = trans->fs_info->tree_root;
421 struct btrfs_key key;
423 struct btrfs_path *path;
424 struct btrfs_root_ref *ref;
425 struct extent_buffer *leaf;
428 path = btrfs_alloc_path();
432 key.objectid = root_id;
433 key.type = BTRFS_ROOT_BACKREF_KEY;
436 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
437 sizeof(*ref) + name->len);
439 btrfs_abort_transaction(trans, ret);
440 btrfs_free_path(path);
444 leaf = path->nodes[0];
445 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
446 btrfs_set_root_ref_dirid(leaf, ref, dirid);
447 btrfs_set_root_ref_sequence(leaf, ref, sequence);
448 btrfs_set_root_ref_name_len(leaf, ref, name->len);
449 ptr = (unsigned long)(ref + 1);
450 write_extent_buffer(leaf, name->name, ptr, name->len);
451 btrfs_mark_buffer_dirty(trans, leaf);
453 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
454 btrfs_release_path(path);
455 key.objectid = ref_id;
456 key.type = BTRFS_ROOT_REF_KEY;
457 key.offset = root_id;
461 btrfs_free_path(path);
466 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
467 * for subvolumes. To work around this problem, we steal a bit from
468 * root_item->inode_item->flags, and use it to indicate if those fields
469 * have been properly initialized.
471 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
473 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
475 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
476 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
477 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
478 btrfs_set_root_flags(root_item, 0);
479 btrfs_set_root_limit(root_item, 0);
483 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
484 struct btrfs_root *root)
486 struct btrfs_root_item *item = &root->root_item;
487 struct timespec64 ct;
489 ktime_get_real_ts64(&ct);
490 spin_lock(&root->root_item_lock);
491 btrfs_set_root_ctransid(item, trans->transid);
492 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
493 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
494 spin_unlock(&root->root_item_lock);
498 * Reserve space for subvolume operation.
500 * root: the root of the parent directory
501 * rsv: block reservation
502 * items: the number of items that we need do reservation
503 * use_global_rsv: allow fallback to the global block reservation
505 * This function is used to reserve the space for snapshot/subvolume
506 * creation and deletion. Those operations are different with the
507 * common file/directory operations, they change two fs/file trees
508 * and root tree, the number of items that the qgroup reserves is
509 * different with the free space reservation. So we can not use
510 * the space reservation mechanism in start_transaction().
512 int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
513 struct btrfs_block_rsv *rsv, int items,
516 u64 qgroup_num_bytes = 0;
519 struct btrfs_fs_info *fs_info = root->fs_info;
520 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
522 if (btrfs_qgroup_enabled(fs_info)) {
523 /* One for parent inode, two for dir entries */
524 qgroup_num_bytes = 3 * fs_info->nodesize;
525 ret = btrfs_qgroup_reserve_meta_prealloc(root,
526 qgroup_num_bytes, true,
532 num_bytes = btrfs_calc_insert_metadata_size(fs_info, items);
533 rsv->space_info = btrfs_find_space_info(fs_info,
534 BTRFS_BLOCK_GROUP_METADATA);
535 ret = btrfs_block_rsv_add(fs_info, rsv, num_bytes,
536 BTRFS_RESERVE_FLUSH_ALL);
538 if (ret == -ENOSPC && use_global_rsv)
539 ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, true);
541 if (ret && qgroup_num_bytes)
542 btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
545 spin_lock(&rsv->lock);
546 rsv->qgroup_rsv_reserved += qgroup_num_bytes;
547 spin_unlock(&rsv->lock);
552 void btrfs_subvolume_release_metadata(struct btrfs_root *root,
553 struct btrfs_block_rsv *rsv)
555 struct btrfs_fs_info *fs_info = root->fs_info;
556 u64 qgroup_to_release;
558 btrfs_block_rsv_release(fs_info, rsv, (u64)-1, &qgroup_to_release);
559 btrfs_qgroup_convert_reserved_meta(root, qgroup_to_release);