1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Oracle.  All rights reserved.
4 */
5
6#include <linux/err.h>
7#include <linux/uuid.h>
8#include "ctree.h"
9#include "fs.h"
10#include "messages.h"
11#include "transaction.h"
12#include "disk-io.h"
13#include "qgroup.h"
14#include "space-info.h"
15#include "accessors.h"
16#include "root-tree.h"
17#include "orphan.h"
18
19/*
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.
25 */
26static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
27				struct btrfs_root_item *item)
28{
29	u32 len;
30	int need_reset = 0;
31
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))
36		need_reset = 1;
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.");
42		}
43		need_reset = 1;
44	}
45	if (need_reset) {
46		/* Clear all members from generation_v2 onwards. */
47		memset_startat(item, 0, generation_v2);
48		generate_random_guid(item->uuid);
49	}
50}
51
52/*
53 * Lookup the root by the key.
54 *
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
60 *
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
63 * given objectid.
64 *
65 * If we find something return 0, otherwise > 0, < 0 on error.
66 */
67int 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)
70{
71	struct btrfs_key found_key;
72	struct extent_buffer *l;
73	int ret;
74	int slot;
75
76	ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
77	if (ret < 0)
78		return ret;
79
80	if (search_key->offset != -1ULL) {	/* the search key is exact */
81		if (ret > 0)
82			goto out;
83	} else {
84		/*
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.
87		 */
88		if (ret == 0) {
89			ret = -EUCLEAN;
90			goto out;
91		}
92		if (path->slots[0] == 0)
93			goto out;
94		path->slots[0]--;
95		ret = 0;
96	}
97
98	l = path->nodes[0];
99	slot = path->slots[0];
100
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) {
104		ret = 1;
105		goto out;
106	}
107
108	if (root_item)
109		btrfs_read_root_item(l, slot, root_item);
110	if (root_key)
111		memcpy(root_key, &found_key, sizeof(found_key));
112out:
113	btrfs_release_path(path);
114	return ret;
115}
116
117void btrfs_set_root_node(struct btrfs_root_item *item,
118			 struct extent_buffer *node)
119{
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));
123}
124
125/*
126 * copy the data in 'item' into the btree
127 */
128int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
129		      *root, struct btrfs_key *key, struct btrfs_root_item
130		      *item)
131{
132	struct btrfs_fs_info *fs_info = root->fs_info;
133	struct btrfs_path *path;
134	struct extent_buffer *l;
135	int ret;
136	int slot;
137	unsigned long ptr;
138	u32 old_len;
139
140	path = btrfs_alloc_path();
141	if (!path)
142		return -ENOMEM;
143
144	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
145	if (ret < 0)
146		goto out;
147
148	if (ret > 0) {
149		btrfs_crit(fs_info,
150			"unable to find root key (%llu %u %llu) in tree %llu",
151			key->objectid, key->type, key->offset,
152			root->root_key.objectid);
153		ret = -EUCLEAN;
154		btrfs_abort_transaction(trans, ret);
155		goto out;
156	}
157
158	l = path->nodes[0];
159	slot = path->slots[0];
160	ptr = btrfs_item_ptr_offset(l, slot);
161	old_len = btrfs_item_size(l, slot);
162
163	/*
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.
167	 */
168	if (old_len < sizeof(*item)) {
169		btrfs_release_path(path);
170		ret = btrfs_search_slot(trans, root, key, path,
171				-1, 1);
172		if (ret < 0) {
173			btrfs_abort_transaction(trans, ret);
174			goto out;
175		}
176
177		ret = btrfs_del_item(trans, root, path);
178		if (ret < 0) {
179			btrfs_abort_transaction(trans, ret);
180			goto out;
181		}
182		btrfs_release_path(path);
183		ret = btrfs_insert_empty_item(trans, root, path,
184				key, sizeof(*item));
185		if (ret < 0) {
186			btrfs_abort_transaction(trans, ret);
187			goto out;
188		}
189		l = path->nodes[0];
190		slot = path->slots[0];
191		ptr = btrfs_item_ptr_offset(l, slot);
192	}
193
194	/*
195	 * Update generation_v2 so at the next mount we know the new root
196	 * fields are valid.
197	 */
198	btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
199
200	write_extent_buffer(l, item, ptr, sizeof(*item));
201	btrfs_mark_buffer_dirty(trans, path->nodes[0]);
202out:
203	btrfs_free_path(path);
204	return ret;
205}
206
207int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
208		      const struct btrfs_key *key, struct btrfs_root_item *item)
209{
210	/*
211	 * Make sure generation v1 and v2 match. See update_root for details.
212	 */
213	btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
214	return btrfs_insert_item(trans, root, key, item, sizeof(*item));
215}
216
217int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
218{
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;
224	int err = 0;
225	int ret;
226
227	path = btrfs_alloc_path();
228	if (!path)
229		return -ENOMEM;
230
231	key.objectid = BTRFS_ORPHAN_OBJECTID;
232	key.type = BTRFS_ORPHAN_ITEM_KEY;
233	key.offset = 0;
234
235	while (1) {
236		u64 root_objectid;
237
238		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
239		if (ret < 0) {
240			err = ret;
241			break;
242		}
243
244		leaf = path->nodes[0];
245		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
246			ret = btrfs_next_leaf(tree_root, path);
247			if (ret < 0)
248				err = ret;
249			if (ret != 0)
250				break;
251			leaf = path->nodes[0];
252		}
253
254		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
255		btrfs_release_path(path);
256
257		if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
258		    key.type != BTRFS_ORPHAN_ITEM_KEY)
259			break;
260
261		root_objectid = key.offset;
262		key.offset++;
263
264		root = btrfs_get_fs_root(fs_info, root_objectid, false);
265		err = PTR_ERR_OR_ZERO(root);
266		if (err && err != -ENOENT) {
267			break;
268		} else if (err == -ENOENT) {
269			struct btrfs_trans_handle *trans;
270
271			btrfs_release_path(path);
272
273			trans = btrfs_join_transaction(tree_root);
274			if (IS_ERR(trans)) {
275				err = PTR_ERR(trans);
276				btrfs_handle_fs_error(fs_info, err,
277					    "Failed to start trans to delete orphan item");
278				break;
279			}
280			err = btrfs_del_orphan_item(trans, tree_root,
281						    root_objectid);
282			btrfs_end_transaction(trans);
283			if (err) {
284				btrfs_handle_fs_error(fs_info, err,
285					    "Failed to delete root orphan item");
286				break;
287			}
288			continue;
289		}
290
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;
294
295			btrfs_disk_key_to_cpu(&drop_key, &root->root_item.drop_progress);
296			/*
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.
301			 */
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);
306			}
307
308			set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
309			btrfs_add_dead_root(root);
310		}
311		btrfs_put_root(root);
312	}
313
314	btrfs_free_path(path);
315	return err;
316}
317
318/* drop the root item for 'key' from the tree root */
319int btrfs_del_root(struct btrfs_trans_handle *trans,
320		   const struct btrfs_key *key)
321{
322	struct btrfs_root *root = trans->fs_info->tree_root;
323	struct btrfs_path *path;
324	int ret;
325
326	path = btrfs_alloc_path();
327	if (!path)
328		return -ENOMEM;
329	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
330	if (ret < 0)
331		goto out;
332	if (ret != 0) {
333		/* The root must exist but we did not find it by the key. */
334		ret = -EUCLEAN;
335		goto out;
336	}
337
338	ret = btrfs_del_item(trans, root, path);
339out:
340	btrfs_free_path(path);
341	return ret;
342}
343
344int 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)
347{
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;
353	unsigned long ptr;
354	int ret;
355
356	path = btrfs_alloc_path();
357	if (!path)
358		return -ENOMEM;
359
360	key.objectid = root_id;
361	key.type = BTRFS_ROOT_BACKREF_KEY;
362	key.offset = ref_id;
363again:
364	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
365	if (ret < 0) {
366		goto out;
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)) {
375			ret = -ENOENT;
376			goto out;
377		}
378		*sequence = btrfs_root_ref_sequence(leaf, ref);
379
380		ret = btrfs_del_item(trans, tree_root, path);
381		if (ret)
382			goto out;
383	} else {
384		ret = -ENOENT;
385		goto out;
386	}
387
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;
393		goto again;
394	}
395
396out:
397	btrfs_free_path(path);
398	return ret;
399}
400
401/*
402 * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
403 * or BTRFS_ROOT_BACKREF_KEY.
404 *
405 * The dirid, sequence, name and name_len refer to the directory entry
406 * that is referencing the root.
407 *
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.
410 *
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.
413 *
414 * Will return 0, -ENOMEM, or anything from the CoW path
415 */
416int 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)
419{
420	struct btrfs_root *tree_root = trans->fs_info->tree_root;
421	struct btrfs_key key;
422	int ret;
423	struct btrfs_path *path;
424	struct btrfs_root_ref *ref;
425	struct extent_buffer *leaf;
426	unsigned long ptr;
427
428	path = btrfs_alloc_path();
429	if (!path)
430		return -ENOMEM;
431
432	key.objectid = root_id;
433	key.type = BTRFS_ROOT_BACKREF_KEY;
434	key.offset = ref_id;
435again:
436	ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
437				      sizeof(*ref) + name->len);
438	if (ret) {
439		btrfs_abort_transaction(trans, ret);
440		btrfs_free_path(path);
441		return ret;
442	}
443
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);
452
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;
458		goto again;
459	}
460
461	btrfs_free_path(path);
462	return 0;
463}
464
465/*
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.
470 */
471void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
472{
473	u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
474
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);
480	}
481}
482
483void btrfs_update_root_times(struct btrfs_trans_handle *trans,
484			     struct btrfs_root *root)
485{
486	struct btrfs_root_item *item = &root->root_item;
487	struct timespec64 ct;
488
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);
495}
496
497/*
498 * Reserve space for subvolume operation.
499 *
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
504 *
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().
511 */
512int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
513				     struct btrfs_block_rsv *rsv, int items,
514				     bool use_global_rsv)
515{
516	u64 qgroup_num_bytes = 0;
517	u64 num_bytes;
518	int ret;
519	struct btrfs_fs_info *fs_info = root->fs_info;
520	struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
521
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,
527							 false);
528		if (ret)
529			return ret;
530	}
531
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);
537
538	if (ret == -ENOSPC && use_global_rsv)
539		ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, true);
540
541	if (ret && qgroup_num_bytes)
542		btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
543
544	if (!ret) {
545		spin_lock(&rsv->lock);
546		rsv->qgroup_rsv_reserved += qgroup_num_bytes;
547		spin_unlock(&rsv->lock);
548	}
549	return ret;
550}
551