1 /*
2 * Copyright (C) 2007 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/err.h>
20 #include <linux/uuid.h>
21 #include "ctree.h"
22 #include "transaction.h"
23 #include "disk-io.h"
24 #include "print-tree.h"
25
26 /*
27 * Read a root item from the tree. In case we detect a root item smaller then
28 * sizeof(root_item), we know it's an old version of the root structure and
29 * initialize all new fields to zero. The same happens if we detect mismatching
30 * generation numbers as then we know the root was once mounted with an older
31 * kernel that was not aware of the root item structure change.
32 */
btrfs_read_root_item(struct extent_buffer * eb,int slot,struct btrfs_root_item * item)33 static void btrfs_read_root_item(struct extent_buffer *eb, int slot,
34 struct btrfs_root_item *item)
35 {
36 uuid_le uuid;
37 int len;
38 int need_reset = 0;
39
40 len = btrfs_item_size_nr(eb, slot);
41 read_extent_buffer(eb, item, btrfs_item_ptr_offset(eb, slot),
42 min_t(int, len, (int)sizeof(*item)));
43 if (len < sizeof(*item))
44 need_reset = 1;
45 if (!need_reset && btrfs_root_generation(item)
46 != btrfs_root_generation_v2(item)) {
47 if (btrfs_root_generation_v2(item) != 0) {
48 btrfs_warn(eb->fs_info,
49 "mismatching generation and generation_v2 found in root item. This root was probably mounted with an older kernel. Resetting all new fields.");
50 }
51 need_reset = 1;
52 }
53 if (need_reset) {
54 memset(&item->generation_v2, 0,
55 sizeof(*item) - offsetof(struct btrfs_root_item,
56 generation_v2));
57
58 uuid_le_gen(&uuid);
59 memcpy(item->uuid, uuid.b, BTRFS_UUID_SIZE);
60 }
61 }
62
63 /*
64 * btrfs_find_root - lookup the root by the key.
65 * root: the root of the root tree
66 * search_key: the key to search
67 * path: the path we search
68 * root_item: the root item of the tree we look for
69 * root_key: the root key of the tree we look for
70 *
71 * If ->offset of 'search_key' is -1ULL, it means we are not sure the offset
72 * of the search key, just lookup the root with the highest offset for a
73 * given objectid.
74 *
75 * If we find something return 0, otherwise > 0, < 0 on error.
76 */
btrfs_find_root(struct btrfs_root * root,struct btrfs_key * search_key,struct btrfs_path * path,struct btrfs_root_item * root_item,struct btrfs_key * root_key)77 int btrfs_find_root(struct btrfs_root *root, struct btrfs_key *search_key,
78 struct btrfs_path *path, struct btrfs_root_item *root_item,
79 struct btrfs_key *root_key)
80 {
81 struct btrfs_key found_key;
82 struct extent_buffer *l;
83 int ret;
84 int slot;
85
86 ret = btrfs_search_slot(NULL, root, search_key, path, 0, 0);
87 if (ret < 0)
88 return ret;
89
90 if (search_key->offset != -1ULL) { /* the search key is exact */
91 if (ret > 0)
92 goto out;
93 } else {
94 BUG_ON(ret == 0); /* Logical error */
95 if (path->slots[0] == 0)
96 goto out;
97 path->slots[0]--;
98 ret = 0;
99 }
100
101 l = path->nodes[0];
102 slot = path->slots[0];
103
104 btrfs_item_key_to_cpu(l, &found_key, slot);
105 if (found_key.objectid != search_key->objectid ||
106 found_key.type != BTRFS_ROOT_ITEM_KEY) {
107 ret = 1;
108 goto out;
109 }
110
111 if (root_item)
112 btrfs_read_root_item(l, slot, root_item);
113 if (root_key)
114 memcpy(root_key, &found_key, sizeof(found_key));
115 out:
116 btrfs_release_path(path);
117 return ret;
118 }
119
btrfs_set_root_node(struct btrfs_root_item * item,struct extent_buffer * node)120 void btrfs_set_root_node(struct btrfs_root_item *item,
121 struct extent_buffer *node)
122 {
123 btrfs_set_root_bytenr(item, node->start);
124 btrfs_set_root_level(item, btrfs_header_level(node));
125 btrfs_set_root_generation(item, btrfs_header_generation(node));
126 }
127
128 /*
129 * copy the data in 'item' into the btree
130 */
btrfs_update_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_key * key,struct btrfs_root_item * item)131 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
132 *root, struct btrfs_key *key, struct btrfs_root_item
133 *item)
134 {
135 struct btrfs_path *path;
136 struct extent_buffer *l;
137 int ret;
138 int slot;
139 unsigned long ptr;
140 u32 old_len;
141
142 path = btrfs_alloc_path();
143 if (!path)
144 return -ENOMEM;
145
146 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
147 if (ret < 0) {
148 btrfs_abort_transaction(trans, ret);
149 goto out;
150 }
151
152 if (ret != 0) {
153 btrfs_print_leaf(root, path->nodes[0]);
154 btrfs_crit(root->fs_info,
155 "unable to update root key %llu %u %llu",
156 key->objectid, key->type, key->offset);
157 BUG_ON(1);
158 }
159
160 l = path->nodes[0];
161 slot = path->slots[0];
162 ptr = btrfs_item_ptr_offset(l, slot);
163 old_len = btrfs_item_size_nr(l, slot);
164
165 /*
166 * If this is the first time we update the root item which originated
167 * from an older kernel, we need to enlarge the item size to make room
168 * for the added fields.
169 */
170 if (old_len < sizeof(*item)) {
171 btrfs_release_path(path);
172 ret = btrfs_search_slot(trans, root, key, path,
173 -1, 1);
174 if (ret < 0) {
175 btrfs_abort_transaction(trans, ret);
176 goto out;
177 }
178
179 ret = btrfs_del_item(trans, root, path);
180 if (ret < 0) {
181 btrfs_abort_transaction(trans, ret);
182 goto out;
183 }
184 btrfs_release_path(path);
185 ret = btrfs_insert_empty_item(trans, root, path,
186 key, sizeof(*item));
187 if (ret < 0) {
188 btrfs_abort_transaction(trans, ret);
189 goto out;
190 }
191 l = path->nodes[0];
192 slot = path->slots[0];
193 ptr = btrfs_item_ptr_offset(l, slot);
194 }
195
196 /*
197 * Update generation_v2 so at the next mount we know the new root
198 * fields are valid.
199 */
200 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
201
202 write_extent_buffer(l, item, ptr, sizeof(*item));
203 btrfs_mark_buffer_dirty(path->nodes[0]);
204 out:
205 btrfs_free_path(path);
206 return ret;
207 }
208
btrfs_insert_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_key * key,struct btrfs_root_item * item)209 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
210 struct btrfs_key *key, struct btrfs_root_item *item)
211 {
212 /*
213 * Make sure generation v1 and v2 match. See update_root for details.
214 */
215 btrfs_set_root_generation_v2(item, btrfs_root_generation(item));
216 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
217 }
218
btrfs_find_orphan_roots(struct btrfs_root * tree_root)219 int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
220 {
221 struct extent_buffer *leaf;
222 struct btrfs_path *path;
223 struct btrfs_key key;
224 struct btrfs_key root_key;
225 struct btrfs_root *root;
226 int err = 0;
227 int ret;
228 bool can_recover = true;
229
230 if (tree_root->fs_info->sb->s_flags & MS_RDONLY)
231 can_recover = false;
232
233 path = btrfs_alloc_path();
234 if (!path)
235 return -ENOMEM;
236
237 key.objectid = BTRFS_ORPHAN_OBJECTID;
238 key.type = BTRFS_ORPHAN_ITEM_KEY;
239 key.offset = 0;
240
241 root_key.type = BTRFS_ROOT_ITEM_KEY;
242 root_key.offset = (u64)-1;
243
244 while (1) {
245 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
246 if (ret < 0) {
247 err = ret;
248 break;
249 }
250
251 leaf = path->nodes[0];
252 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
253 ret = btrfs_next_leaf(tree_root, path);
254 if (ret < 0)
255 err = ret;
256 if (ret != 0)
257 break;
258 leaf = path->nodes[0];
259 }
260
261 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
262 btrfs_release_path(path);
263
264 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
265 key.type != BTRFS_ORPHAN_ITEM_KEY)
266 break;
267
268 root_key.objectid = key.offset;
269 key.offset++;
270
271 /*
272 * The root might have been inserted already, as before we look
273 * for orphan roots, log replay might have happened, which
274 * triggers a transaction commit and qgroup accounting, which
275 * in turn reads and inserts fs roots while doing backref
276 * walking.
277 */
278 root = btrfs_lookup_fs_root(tree_root->fs_info,
279 root_key.objectid);
280 if (root) {
281 WARN_ON(!test_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED,
282 &root->state));
283 if (btrfs_root_refs(&root->root_item) == 0)
284 btrfs_add_dead_root(root);
285 continue;
286 }
287
288 root = btrfs_read_fs_root(tree_root, &root_key);
289 err = PTR_ERR_OR_ZERO(root);
290 if (err && err != -ENOENT) {
291 break;
292 } else if (err == -ENOENT) {
293 struct btrfs_trans_handle *trans;
294
295 btrfs_release_path(path);
296
297 trans = btrfs_join_transaction(tree_root);
298 if (IS_ERR(trans)) {
299 err = PTR_ERR(trans);
300 btrfs_handle_fs_error(tree_root->fs_info, err,
301 "Failed to start trans to delete orphan item");
302 break;
303 }
304 err = btrfs_del_orphan_item(trans, tree_root,
305 root_key.objectid);
306 btrfs_end_transaction(trans, tree_root);
307 if (err) {
308 btrfs_handle_fs_error(tree_root->fs_info, err,
309 "Failed to delete root orphan item");
310 break;
311 }
312 continue;
313 }
314
315 err = btrfs_init_fs_root(root);
316 if (err) {
317 btrfs_free_fs_root(root);
318 break;
319 }
320
321 set_bit(BTRFS_ROOT_ORPHAN_ITEM_INSERTED, &root->state);
322
323 err = btrfs_insert_fs_root(root->fs_info, root);
324 if (err) {
325 BUG_ON(err == -EEXIST);
326 btrfs_free_fs_root(root);
327 break;
328 }
329
330 if (btrfs_root_refs(&root->root_item) == 0)
331 btrfs_add_dead_root(root);
332 }
333
334 btrfs_free_path(path);
335 return err;
336 }
337
338 /* drop the root item for 'key' from 'root' */
btrfs_del_root(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_key * key)339 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
340 struct btrfs_key *key)
341 {
342 struct btrfs_path *path;
343 int ret;
344
345 path = btrfs_alloc_path();
346 if (!path)
347 return -ENOMEM;
348 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
349 if (ret < 0)
350 goto out;
351
352 BUG_ON(ret != 0);
353
354 ret = btrfs_del_item(trans, root, path);
355 out:
356 btrfs_free_path(path);
357 return ret;
358 }
359
btrfs_del_root_ref(struct btrfs_trans_handle * trans,struct btrfs_root * tree_root,u64 root_id,u64 ref_id,u64 dirid,u64 * sequence,const char * name,int name_len)360 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
361 struct btrfs_root *tree_root,
362 u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
363 const char *name, int name_len)
364
365 {
366 struct btrfs_path *path;
367 struct btrfs_root_ref *ref;
368 struct extent_buffer *leaf;
369 struct btrfs_key key;
370 unsigned long ptr;
371 int err = 0;
372 int ret;
373
374 path = btrfs_alloc_path();
375 if (!path)
376 return -ENOMEM;
377
378 key.objectid = root_id;
379 key.type = BTRFS_ROOT_BACKREF_KEY;
380 key.offset = ref_id;
381 again:
382 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
383 BUG_ON(ret < 0);
384 if (ret == 0) {
385 leaf = path->nodes[0];
386 ref = btrfs_item_ptr(leaf, path->slots[0],
387 struct btrfs_root_ref);
388
389 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
390 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
391 ptr = (unsigned long)(ref + 1);
392 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
393 *sequence = btrfs_root_ref_sequence(leaf, ref);
394
395 ret = btrfs_del_item(trans, tree_root, path);
396 if (ret) {
397 err = ret;
398 goto out;
399 }
400 } else
401 err = -ENOENT;
402
403 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
404 btrfs_release_path(path);
405 key.objectid = ref_id;
406 key.type = BTRFS_ROOT_REF_KEY;
407 key.offset = root_id;
408 goto again;
409 }
410
411 out:
412 btrfs_free_path(path);
413 return err;
414 }
415
416 /*
417 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
418 * or BTRFS_ROOT_BACKREF_KEY.
419 *
420 * The dirid, sequence, name and name_len refer to the directory entry
421 * that is referencing the root.
422 *
423 * For a forward ref, the root_id is the id of the tree referencing
424 * the root and ref_id is the id of the subvol or snapshot.
425 *
426 * For a back ref the root_id is the id of the subvol or snapshot and
427 * ref_id is the id of the tree referencing it.
428 *
429 * Will return 0, -ENOMEM, or anything from the CoW path
430 */
btrfs_add_root_ref(struct btrfs_trans_handle * trans,struct btrfs_root * tree_root,u64 root_id,u64 ref_id,u64 dirid,u64 sequence,const char * name,int name_len)431 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
432 struct btrfs_root *tree_root,
433 u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
434 const char *name, int name_len)
435 {
436 struct btrfs_key key;
437 int ret;
438 struct btrfs_path *path;
439 struct btrfs_root_ref *ref;
440 struct extent_buffer *leaf;
441 unsigned long ptr;
442
443 path = btrfs_alloc_path();
444 if (!path)
445 return -ENOMEM;
446
447 key.objectid = root_id;
448 key.type = BTRFS_ROOT_BACKREF_KEY;
449 key.offset = ref_id;
450 again:
451 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
452 sizeof(*ref) + name_len);
453 if (ret) {
454 btrfs_abort_transaction(trans, ret);
455 btrfs_free_path(path);
456 return ret;
457 }
458
459 leaf = path->nodes[0];
460 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
461 btrfs_set_root_ref_dirid(leaf, ref, dirid);
462 btrfs_set_root_ref_sequence(leaf, ref, sequence);
463 btrfs_set_root_ref_name_len(leaf, ref, name_len);
464 ptr = (unsigned long)(ref + 1);
465 write_extent_buffer(leaf, name, ptr, name_len);
466 btrfs_mark_buffer_dirty(leaf);
467
468 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
469 btrfs_release_path(path);
470 key.objectid = ref_id;
471 key.type = BTRFS_ROOT_REF_KEY;
472 key.offset = root_id;
473 goto again;
474 }
475
476 btrfs_free_path(path);
477 return 0;
478 }
479
480 /*
481 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
482 * for subvolumes. To work around this problem, we steal a bit from
483 * root_item->inode_item->flags, and use it to indicate if those fields
484 * have been properly initialized.
485 */
btrfs_check_and_init_root_item(struct btrfs_root_item * root_item)486 void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
487 {
488 u64 inode_flags = btrfs_stack_inode_flags(&root_item->inode);
489
490 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
491 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
492 btrfs_set_stack_inode_flags(&root_item->inode, inode_flags);
493 btrfs_set_root_flags(root_item, 0);
494 btrfs_set_root_limit(root_item, 0);
495 }
496 }
497
btrfs_update_root_times(struct btrfs_trans_handle * trans,struct btrfs_root * root)498 void btrfs_update_root_times(struct btrfs_trans_handle *trans,
499 struct btrfs_root *root)
500 {
501 struct btrfs_root_item *item = &root->root_item;
502 struct timespec ct = current_fs_time(root->fs_info->sb);
503
504 spin_lock(&root->root_item_lock);
505 btrfs_set_root_ctransid(item, trans->transid);
506 btrfs_set_stack_timespec_sec(&item->ctime, ct.tv_sec);
507 btrfs_set_stack_timespec_nsec(&item->ctime, ct.tv_nsec);
508 spin_unlock(&root->root_item_lock);
509 }
510