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 "transaction.h"
10 #include "disk-io.h"
11 #include "print-tree.h"
12 
13 /*
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.
19  */
btrfs_read_root_item(struct extent_buffer * eb,int slot,struct btrfs_root_item * item)20 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
21 				struct btrfs_root_item *item)
22 {
23 	uuid_le uuid;
24 	int len;
25 	int need_reset = 0;
26 
27 	len = btrfs_item_size_nr(eb, slot);
28 	read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
29 			min_t(int, len, (int)sizeof(*item)));
30 	if (len < sizeof(*item))
31 		need_reset = 1;
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.");
37 		}
38 		need_reset = 1;
39 	}
40 	if (need_reset) {
41 		memset(&item->generation_v2, 0,
42 			sizeof(*item) - offsetof(struct btrfs_root_item,
43 					generation_v2));
44 
45 		uuid_le_gen(&uuid);
46 		memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
47 	}
48 }
49 
50 /*
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
57  *
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
60  * given objectid.
61  *
62  * If we find something return 0, otherwise > 0, < 0 on error.
63  */
btrfs_find_root(struct btrfs_root * root,const struct btrfs_key * search_key,struct btrfs_path * path,struct btrfs_root_item * root_item,struct btrfs_key * root_key)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)
67 {
68 	struct btrfs_key found_key;
69 	struct extent_buffer *l;
70 	int ret;
71 	int slot;
72 
73 	ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
74 	if (ret < 0)
75 		return ret;
76 
77 	if (search_key->offset != -1ULL) {	/* the search key is exact */
78 		if (ret > 0)
79 			goto out;
80 	} else {
81 		BUG_ON(ret == 0);		/* Logical error */
82 		if (path->slots[0] == 0)
83 			goto out;
84 		path->slots[0]--;
85 		ret = 0;
86 	}
87 
88 	l = path->nodes[0];
89 	slot = path->slots[0];
90 
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) {
94 		ret = 1;
95 		goto out;
96 	}
97 
98 	if (root_item)
99 		btrfs_read_root_item(l, slot, root_item);
100 	if (root_key)
101 		memcpy(root_key, &found_key, sizeof(found_key));
102 out:
103 	btrfs_release_path(path);
104 	return ret;
105 }
106 
btrfs_set_root_node(struct btrfs_root_item * item,struct extent_buffer * node)107 void btrfs_set_root_node(struct btrfs_root_item *item,
108 			 struct extent_buffer *node)
109 {
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));
113 }
114 
115 /*
116  * copy the data in 'item' into the btree
117  */
btrfs_update_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_key * key,struct btrfs_root_item * item)118 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
119 		      *root, struct btrfs_key *key, struct btrfs_root_item
120 		      *item)
121 {
122 	struct btrfs_fs_info *fs_info = root->fs_info;
123 	struct btrfs_path *path;
124 	struct extent_buffer *l;
125 	int ret;
126 	int slot;
127 	unsigned long ptr;
128 	u32 old_len;
129 
130 	path = btrfs_alloc_path();
131 	if (!path)
132 		return -ENOMEM;
133 
134 	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
135 	if (ret < 0)
136 		goto out;
137 
138 	if (ret > 0) {
139 		btrfs_crit(fs_info,
140 			"unable to find root key (%llu %u %llu) in tree %llu",
141 			key->objectid, key->type, key->offset,
142 			root->root_key.objectid);
143 		ret = -EUCLEAN;
144 		btrfs_abort_transaction(trans, ret);
145 		goto out;
146 	}
147 
148 	l = path->nodes[0];
149 	slot = path->slots[0];
150 	ptr = btrfs_item_ptr_offset(l, slot);
151 	old_len = btrfs_item_size_nr(l, slot);
152 
153 	/*
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.
157 	 */
158 	if (old_len < sizeof(*item)) {
159 		btrfs_release_path(path);
160 		ret = btrfs_search_slot(trans, root, key, path,
161 				-1, 1);
162 		if (ret < 0) {
163 			btrfs_abort_transaction(trans, ret);
164 			goto out;
165 		}
166 
167 		ret = btrfs_del_item(trans, root, path);
168 		if (ret < 0) {
169 			btrfs_abort_transaction(trans, ret);
170 			goto out;
171 		}
172 		btrfs_release_path(path);
173 		ret = btrfs_insert_empty_item(trans, root, path,
174 				key, sizeof(*item));
175 		if (ret < 0) {
176 			btrfs_abort_transaction(trans, ret);
177 			goto out;
178 		}
179 		l = path->nodes[0];
180 		slot = path->slots[0];
181 		ptr = btrfs_item_ptr_offset(l, slot);
182 	}
183 
184 	/*
185 	 * Update generation_v2 so at the next mount we know the new root
186 	 * fields are valid.
187 	 */
188 	btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
189 
190 	write_extent_buffer(l, item, ptr, sizeof(*item));
191 	btrfs_mark_buffer_dirty(path->nodes[0]);
192 out:
193 	btrfs_free_path(path);
194 	return ret;
195 }
196 
btrfs_insert_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,const struct btrfs_key * key,struct btrfs_root_item * item)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)
199 {
200 	/*
201 	 * Make sure generation v1 and v2 match. See update_root for details.
202 	 */
203 	btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
204 	return btrfs_insert_item(trans, root, key, item, sizeof(*item));
205 }
206 
btrfs_find_orphan_roots(struct btrfs_fs_info * fs_info)207 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
208 {
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;
215 	int err = 0;
216 	int ret;
217 
218 	path = btrfs_alloc_path();
219 	if (!path)
220 		return -ENOMEM;
221 
222 	key.objectid = BTRFS_ORPHAN_OBJECTID;
223 	key.type = BTRFS_ORPHAN_ITEM_KEY;
224 	key.offset = 0;
225 
226 	root_key.type = BTRFS_ROOT_ITEM_KEY;
227 	root_key.offset = (u64)-1;
228 
229 	while (1) {
230 		ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
231 		if (ret < 0) {
232 			err = ret;
233 			break;
234 		}
235 
236 		leaf = path->nodes[0];
237 		if (path->slots[0] >= btrfs_header_nritems(leaf)) {
238 			ret = btrfs_next_leaf(tree_root, path);
239 			if (ret < 0)
240 				err = ret;
241 			if (ret != 0)
242 				break;
243 			leaf = path->nodes[0];
244 		}
245 
246 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
247 		btrfs_release_path(path);
248 
249 		if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
250 		    key.type != BTRFS_ORPHAN_ITEM_KEY)
251 			break;
252 
253 		root_key.objectid = key.offset;
254 		key.offset++;
255 
256 		/*
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
261 		 * walking.
262 		 */
263 		root = btrfs_lookup_fs_root(fs_info, root_key.objectid);
264 		if (root) {
265 			WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
266 					  &root->state));
267 			if (btrfs_root_refs(&root->root_item) == 0)
268 				btrfs_add_dead_root(root);
269 			continue;
270 		}
271 
272 		root = btrfs_read_fs_root(tree_root, &root_key);
273 		err = PTR_ERR_OR_ZERO(root);
274 		if (err && err != -ENOENT) {
275 			break;
276 		} else if (err == -ENOENT) {
277 			struct btrfs_trans_handle *trans;
278 
279 			btrfs_release_path(path);
280 
281 			trans = btrfs_join_transaction(tree_root);
282 			if (IS_ERR(trans)) {
283 				err = PTR_ERR(trans);
284 				btrfs_handle_fs_error(fs_info, err,
285 					    "Failed to start trans to delete orphan item");
286 				break;
287 			}
288 			err = btrfs_del_orphan_item(trans, tree_root,
289 						    root_key.objectid);
290 			btrfs_end_transaction(trans);
291 			if (err) {
292 				btrfs_handle_fs_error(fs_info, err,
293 					    "Failed to delete root orphan item");
294 				break;
295 			}
296 			continue;
297 		}
298 
299 		err = btrfs_init_fs_root(root);
300 		if (err) {
301 			btrfs_free_fs_root(root);
302 			break;
303 		}
304 
305 		set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
306 
307 		err = btrfs_insert_fs_root(fs_info, root);
308 		if (err) {
309 			BUG_ON(err == -EEXIST);
310 			btrfs_free_fs_root(root);
311 			break;
312 		}
313 
314 		if (btrfs_root_refs(&root->root_item) == 0)
315 			btrfs_add_dead_root(root);
316 	}
317 
318 	btrfs_free_path(path);
319 	return err;
320 }
321 
322 /* drop the root item for 'key' from the tree root */
btrfs_del_root(struct btrfs_trans_handle * trans,const struct btrfs_key * key)323 int btrfs_del_root(struct btrfs_trans_handle *trans,
324 		   const struct btrfs_key *key)
325 {
326 	struct btrfs_root *root = trans->fs_info->tree_root;
327 	struct btrfs_path *path;
328 	int ret;
329 
330 	path = btrfs_alloc_path();
331 	if (!path)
332 		return -ENOMEM;
333 	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
334 	if (ret < 0)
335 		goto out;
336 
337 	BUG_ON(ret != 0);
338 
339 	ret = btrfs_del_item(trans, root, path);
340 out:
341 	btrfs_free_path(path);
342 	return ret;
343 }
344 
btrfs_del_root_ref(struct btrfs_trans_handle * trans,u64 root_id,u64 ref_id,u64 dirid,u64 * sequence,const char * name,int name_len)345 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
346 		       u64 ref_id, u64 dirid, u64 *sequence, const char *name,
347 		       int name_len)
348 
349 {
350 	struct btrfs_root *tree_root = trans->fs_info->tree_root;
351 	struct btrfs_path *path;
352 	struct btrfs_root_ref *ref;
353 	struct extent_buffer *leaf;
354 	struct btrfs_key key;
355 	unsigned long ptr;
356 	int err = 0;
357 	int ret;
358 
359 	path = btrfs_alloc_path();
360 	if (!path)
361 		return -ENOMEM;
362 
363 	key.objectid = root_id;
364 	key.type = BTRFS_ROOT_BACKREF_KEY;
365 	key.offset = ref_id;
366 again:
367 	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
368 	BUG_ON(ret < 0);
369 	if (ret == 0) {
370 		leaf = path->nodes[0];
371 		ref = btrfs_item_ptr(leaf, path->slots[0],
372 				     struct btrfs_root_ref);
373 		ptr = (unsigned long)(ref + 1);
374 		if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
375 		    (btrfs_root_ref_name_len(leaf, ref) != name_len) ||
376 		    memcmp_extent_buffer(leaf, name, ptr, name_len)) {
377 			err = -ENOENT;
378 			goto out;
379 		}
380 		*sequence = btrfs_root_ref_sequence(leaf, ref);
381 
382 		ret = btrfs_del_item(trans, tree_root, path);
383 		if (ret) {
384 			err = ret;
385 			goto out;
386 		}
387 	} else
388 		err = -ENOENT;
389 
390 	if (key.type == BTRFS_ROOT_BACKREF_KEY) {
391 		btrfs_release_path(path);
392 		key.objectid = ref_id;
393 		key.type = BTRFS_ROOT_REF_KEY;
394 		key.offset = root_id;
395 		goto again;
396 	}
397 
398 out:
399 	btrfs_free_path(path);
400 	return err;
401 }
402 
403 /*
404  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
405  * or BTRFS_ROOT_BACKREF_KEY.
406  *
407  * The dirid, sequence, name and name_len refer to the directory entry
408  * that is referencing the root.
409  *
410  * For a forward ref, the root_id is the id of the tree referencing
411  * the root and ref_id is the id of the subvol  or snapshot.
412  *
413  * For a back ref the root_id is the id of the subvol or snapshot and
414  * ref_id is the id of the tree referencing it.
415  *
416  * Will return 0, -ENOMEM, or anything from the CoW path
417  */
btrfs_add_root_ref(struct btrfs_trans_handle * trans,u64 root_id,u64 ref_id,u64 dirid,u64 sequence,const char * name,int name_len)418 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
419 		       u64 ref_id, u64 dirid, u64 sequence, const char *name,
420 		       int name_len)
421 {
422 	struct btrfs_root *tree_root = trans->fs_info->tree_root;
423 	struct btrfs_key key;
424 	int ret;
425 	struct btrfs_path *path;
426 	struct btrfs_root_ref *ref;
427 	struct extent_buffer *leaf;
428 	unsigned long ptr;
429 
430 	path = btrfs_alloc_path();
431 	if (!path)
432 		return -ENOMEM;
433 
434 	key.objectid = root_id;
435 	key.type = BTRFS_ROOT_BACKREF_KEY;
436 	key.offset = ref_id;
437 again:
438 	ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
439 				      sizeof(*ref) + name_len);
440 	if (ret) {
441 		btrfs_abort_transaction(trans, ret);
442 		btrfs_free_path(path);
443 		return ret;
444 	}
445 
446 	leaf = path->nodes[0];
447 	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
448 	btrfs_set_root_ref_dirid(leaf, ref, dirid);
449 	btrfs_set_root_ref_sequence(leaf, ref, sequence);
450 	btrfs_set_root_ref_name_len(leaf, ref, name_len);
451 	ptr = (unsigned long)(ref + 1);
452 	write_extent_buffer(leaf, name, ptr, name_len);
453 	btrfs_mark_buffer_dirty(leaf);
454 
455 	if (key.type == BTRFS_ROOT_BACKREF_KEY) {
456 		btrfs_release_path(path);
457 		key.objectid = ref_id;
458 		key.type = BTRFS_ROOT_REF_KEY;
459 		key.offset = root_id;
460 		goto again;
461 	}
462 
463 	btrfs_free_path(path);
464 	return 0;
465 }
466 
467 /*
468  * Old btrfs forgets to init root_item->flags and root_item->byte_limit
469  * for subvolumes. To work around this problem, we steal a bit from
470  * root_item->inode_item->flags, and use it to indicate if those fields
471  * have been properly initialized.
472  */
btrfs_check_and_init_root_item(struct btrfs_root_item * root_item)473 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
474 {
475 	u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
476 
477 	if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
478 		inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
479 		btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
480 		btrfs_set_root_flags(root_item, 0);
481 		btrfs_set_root_limit(root_item, 0);
482 	}
483 }
484 
btrfs_update_root_times(struct btrfs_trans_handle * trans,struct btrfs_root * root)485 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
486 			     struct btrfs_root *root)
487 {
488 	struct btrfs_root_item *item = &root->root_item;
489 	struct timespec64 ct;
490 
491 	ktime_get_real_ts64(&ct);
492 	spin_lock(&root->root_item_lock);
493 	btrfs_set_root_ctransid(item, trans->transid);
494 	btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
495 	btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
496 	spin_unlock(&root->root_item_lock);
497 }
498