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 */
26 static 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 */
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)
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));
112 out:
113 btrfs_release_path(path);
114 return ret;
115 }
116
117 void 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 */
128 int 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, btrfs_root_id(root));
152 ret = -EUCLEAN;
153 btrfs_abort_transaction(trans, ret);
154 goto out;
155 }
156
157 l = path->nodes[0];
158 slot = path->slots[0];
159 ptr = btrfs_item_ptr_offset(l, slot);
160 old_len = btrfs_item_size(l, slot);
161
162 /*
163 * If this is the first time we update the root item which originated
164 * from an older kernel, we need to enlarge the item size to make room
165 * for the added fields.
166 */
167 if (old_len < sizeof(*item)) {
168 btrfs_release_path(path);
169 ret = btrfs_search_slot(trans, root, key, path,
170 -1, 1);
171 if (ret < 0) {
172 btrfs_abort_transaction(trans, ret);
173 goto out;
174 }
175
176 ret = btrfs_del_item(trans, root, path);
177 if (ret < 0) {
178 btrfs_abort_transaction(trans, ret);
179 goto out;
180 }
181 btrfs_release_path(path);
182 ret = btrfs_insert_empty_item(trans, root, path,
183 key, sizeof(*item));
184 if (ret < 0) {
185 btrfs_abort_transaction(trans, ret);
186 goto out;
187 }
188 l = path->nodes[0];
189 slot = path->slots[0];
190 ptr = btrfs_item_ptr_offset(l, slot);
191 }
192
193 /*
194 * Update generation_v2 so at the next mount we know the new root
195 * fields are valid.
196 */
197 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
198
199 write_extent_buffer(l, item, ptr, sizeof(*item));
200 btrfs_mark_buffer_dirty(trans, path->nodes[0]);
201 out:
202 btrfs_free_path(path);
203 return ret;
204 }
205
206 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
207 const struct btrfs_key *key, struct btrfs_root_item *item)
208 {
209 /*
210 * Make sure generation v1 and v2 match. See update_root for details.
211 */
212 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
213 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
214 }
215
216 int btrfs_find_orphan_roots(struct btrfs_fs_info *fs_info)
217 {
218 struct btrfs_root *tree_root = fs_info->tree_root;
219 struct extent_buffer *leaf;
220 struct btrfs_path *path;
221 struct btrfs_key key;
222 struct btrfs_root *root;
223 int err = 0;
224 int ret;
225
226 path = btrfs_alloc_path();
227 if (!path)
228 return -ENOMEM;
229
230 key.objectid = BTRFS_ORPHAN_OBJECTID;
231 key.type = BTRFS_ORPHAN_ITEM_KEY;
232 key.offset = 0;
233
234 while (1) {
235 u64 root_objectid;
236
237 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
238 if (ret < 0) {
239 err = ret;
240 break;
241 }
242
243 leaf = path->nodes[0];
244 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
245 ret = btrfs_next_leaf(tree_root, path);
246 if (ret < 0)
247 err = ret;
248 if (ret != 0)
249 break;
250 leaf = path->nodes[0];
251 }
252
253 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
254 btrfs_release_path(path);
255
256 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
257 key.type != BTRFS_ORPHAN_ITEM_KEY)
258 break;
259
260 root_objectid = key.offset;
261 key.offset++;
262
263 root = btrfs_get_fs_root(fs_info, root_objectid, false);
264 err = PTR_ERR_OR_ZERO(root);
265 if (err && err != -ENOENT) {
266 break;
267 } else if (err == -ENOENT) {
268 struct btrfs_trans_handle *trans;
269
270 btrfs_release_path(path);
271
272 trans = btrfs_join_transaction(tree_root);
273 if (IS_ERR(trans)) {
274 err = PTR_ERR(trans);
275 btrfs_handle_fs_error(fs_info, err,
276 "Failed to start trans to delete orphan item");
277 break;
278 }
279 err = btrfs_del_orphan_item(trans, tree_root,
280 root_objectid);
281 btrfs_end_transaction(trans);
282 if (err) {
283 btrfs_handle_fs_error(fs_info, err,
284 "Failed to delete root orphan item");
285 break;
286 }
287 continue;
288 }
289
290 WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state));
291 if (btrfs_root_refs(&root->root_item) == 0) {
292 struct btrfs_key drop_key;
293
294 btrfs_disk_key_to_cpu(&drop_key, &root->root_item.drop_progress);
295 /*
296 * If we have a non-zero drop_progress then we know we
297 * made it partly through deleting this snapshot, and
298 * thus we need to make sure we block any balance from
299 * happening until this snapshot is completely dropped.
300 */
301 if (drop_key.objectid != 0 || drop_key.type != 0 ||
302 drop_key.offset != 0) {
303 set_bit(BTRFS_FS_UNFINISHED_DROPS, &fs_info->flags);
304 set_bit(BTRFS_ROOT_UNFINISHED_DROP, &root->state);
305 }
306
307 set_bit(BTRFS_ROOT_DEAD_TREE, &root->state);
308 btrfs_add_dead_root(root);
309 }
310 btrfs_put_root(root);
311 }
312
313 btrfs_free_path(path);
314 return err;
315 }
316
317 /* drop the root item for 'key' from the tree root */
318 int btrfs_del_root(struct btrfs_trans_handle *trans,
319 const struct btrfs_key *key)
320 {
321 struct btrfs_root *root = trans->fs_info->tree_root;
322 struct btrfs_path *path;
323 int ret;
324
325 path = btrfs_alloc_path();
326 if (!path)
327 return -ENOMEM;
328 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
329 if (ret < 0)
330 goto out;
331 if (ret != 0) {
332 /* The root must exist but we did not find it by the key. */
333 ret = -EUCLEAN;
334 goto out;
335 }
336
337 ret = btrfs_del_item(trans, root, path);
338 out:
339 btrfs_free_path(path);
340 return ret;
341 }
342
343 int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
344 u64 ref_id, u64 dirid, u64 *sequence,
345 const struct fscrypt_str *name)
346 {
347 struct btrfs_root *tree_root = trans->fs_info->tree_root;
348 struct btrfs_path *path;
349 struct btrfs_root_ref *ref;
350 struct extent_buffer *leaf;
351 struct btrfs_key key;
352 unsigned long ptr;
353 int ret;
354
355 path = btrfs_alloc_path();
356 if (!path)
357 return -ENOMEM;
358
359 key.objectid = root_id;
360 key.type = BTRFS_ROOT_BACKREF_KEY;
361 key.offset = ref_id;
362 again:
363 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
364 if (ret < 0) {
365 goto out;
366 } else if (ret == 0) {
367 leaf = path->nodes[0];
368 ref = btrfs_item_ptr(leaf, path->slots[0],
369 struct btrfs_root_ref);
370 ptr = (unsigned long)(ref + 1);
371 if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
372 (btrfs_root_ref_name_len(leaf, ref) != name->len) ||
373 memcmp_extent_buffer(leaf, name->name, ptr, name->len)) {
374 ret = -ENOENT;
375 goto out;
376 }
377 *sequence = btrfs_root_ref_sequence(leaf, ref);
378
379 ret = btrfs_del_item(trans, tree_root, path);
380 if (ret)
381 goto out;
382 } else {
383 ret = -ENOENT;
384 goto out;
385 }
386
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;
392 goto again;
393 }
394
395 out:
396 btrfs_free_path(path);
397 return ret;
398 }
399
400 /*
401 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
402 * or BTRFS_ROOT_BACKREF_KEY.
403 *
404 * The dirid, sequence, name and name_len refer to the directory entry
405 * that is referencing the root.
406 *
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.
409 *
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.
412 *
413 * Will return 0, -ENOMEM, or anything from the CoW path
414 */
415 int btrfs_add_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
416 u64 ref_id, u64 dirid, u64 sequence,
417 const struct fscrypt_str *name)
418 {
419 struct btrfs_root *tree_root = trans->fs_info->tree_root;
420 struct btrfs_key key;
421 int ret;
422 struct btrfs_path *path;
423 struct btrfs_root_ref *ref;
424 struct extent_buffer *leaf;
425 unsigned long ptr;
426
427 path = btrfs_alloc_path();
428 if (!path)
429 return -ENOMEM;
430
431 key.objectid = root_id;
432 key.type = BTRFS_ROOT_BACKREF_KEY;
433 key.offset = ref_id;
434 again:
435 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
436 sizeof(*ref) + name->len);
437 if (ret) {
438 btrfs_abort_transaction(trans, ret);
439 btrfs_free_path(path);
440 return ret;
441 }
442
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->name, ptr, name->len);
450 btrfs_mark_buffer_dirty(trans, leaf);
451
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;
457 goto again;
458 }
459
460 btrfs_free_path(path);
461 return 0;
462 }
463
464 /*
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.
469 */
470 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
471 {
472 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
473
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);
479 }
480 }
481
482 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
483 struct btrfs_root *root)
484 {
485 struct btrfs_root_item *item = &root->root_item;
486 struct timespec64 ct;
487
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);
494 }
495
496 /*
497 * Reserve space for subvolume operation.
498 *
499 * root: the root of the parent directory
500 * rsv: block reservation
501 * items: the number of items that we need do reservation
502 * use_global_rsv: allow fallback to the global block reservation
503 *
504 * This function is used to reserve the space for snapshot/subvolume
505 * creation and deletion. Those operations are different with the
506 * common file/directory operations, they change two fs/file trees
507 * and root tree, the number of items that the qgroup reserves is
508 * different with the free space reservation. So we can not use
509 * the space reservation mechanism in start_transaction().
510 */
511 int btrfs_subvolume_reserve_metadata(struct btrfs_root *root,
512 struct btrfs_block_rsv *rsv, int items,
513 bool use_global_rsv)
514 {
515 u64 qgroup_num_bytes = 0;
516 u64 num_bytes;
517 int ret;
518 struct btrfs_fs_info *fs_info = root->fs_info;
519 struct btrfs_block_rsv *global_rsv = &fs_info->global_block_rsv;
520
521 if (btrfs_qgroup_enabled(fs_info)) {
522 /* One for parent inode, two for dir entries */
523 qgroup_num_bytes = 3 * fs_info->nodesize;
524 ret = btrfs_qgroup_reserve_meta_prealloc(root,
525 qgroup_num_bytes, true,
526 false);
527 if (ret)
528 return ret;
529 }
530
531 num_bytes = btrfs_calc_insert_metadata_size(fs_info, items);
532 rsv->space_info = btrfs_find_space_info(fs_info,
533 BTRFS_BLOCK_GROUP_METADATA);
534 ret = btrfs_block_rsv_add(fs_info, rsv, num_bytes,
535 BTRFS_RESERVE_FLUSH_ALL);
536
537 if (ret == -ENOSPC && use_global_rsv)
538 ret = btrfs_block_rsv_migrate(global_rsv, rsv, num_bytes, true);
539
540 if (ret && qgroup_num_bytes)
541 btrfs_qgroup_free_meta_prealloc(root, qgroup_num_bytes);
542
543 if (!ret) {
544 spin_lock(&rsv->lock);
545 rsv->qgroup_rsv_reserved += qgroup_num_bytes;
546 spin_unlock(&rsv->lock);
547 }
548 return ret;
549 }
550
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