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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 "ctree.h"
20#include "transaction.h"
21#include "disk-io.h"
22#include "print-tree.h"
23
24/*
25 * lookup the root with the highest offset for a given objectid. The key we do
26 * find is copied into 'key'. If we find something return 0, otherwise 1, < 0
27 * on error.
28 */
29int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
30 struct btrfs_root_item *item, struct btrfs_key *key)
31{
32 struct btrfs_path *path;
33 struct btrfs_key search_key;
34 struct btrfs_key found_key;
35 struct extent_buffer *l;
36 int ret;
37 int slot;
38
39 search_key.objectid = objectid;
40 search_key.type = BTRFS_ROOT_ITEM_KEY;
41 search_key.offset = (u64)-1;
42
43 path = btrfs_alloc_path();
44 if (!path)
45 return -ENOMEM;
46 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
47 if (ret < 0)
48 goto out;
49
50 BUG_ON(ret == 0);
51 if (path->slots[0] == 0) {
52 ret = 1;
53 goto out;
54 }
55 l = path->nodes[0];
56 slot = path->slots[0] - 1;
57 btrfs_item_key_to_cpu(l, &found_key, slot);
58 if (found_key.objectid != objectid ||
59 found_key.type != BTRFS_ROOT_ITEM_KEY) {
60 ret = 1;
61 goto out;
62 }
63 if (item)
64 read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
65 sizeof(*item));
66 if (key)
67 memcpy(key, &found_key, sizeof(found_key));
68 ret = 0;
69out:
70 btrfs_free_path(path);
71 return ret;
72}
73
74void btrfs_set_root_node(struct btrfs_root_item *item,
75 struct extent_buffer *node)
76{
77 btrfs_set_root_bytenr(item, node->start);
78 btrfs_set_root_level(item, btrfs_header_level(node));
79 btrfs_set_root_generation(item, btrfs_header_generation(node));
80}
81
82/*
83 * copy the data in 'item' into the btree
84 */
85int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
86 *root, struct btrfs_key *key, struct btrfs_root_item
87 *item)
88{
89 struct btrfs_path *path;
90 struct extent_buffer *l;
91 int ret;
92 int slot;
93 unsigned long ptr;
94
95 path = btrfs_alloc_path();
96 BUG_ON(!path);
97 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
98 if (ret < 0)
99 goto out;
100
101 if (ret != 0) {
102 btrfs_print_leaf(root, path->nodes[0]);
103 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
104 (unsigned long long)key->objectid, key->type,
105 (unsigned long long)key->offset);
106 BUG_ON(1);
107 }
108
109 l = path->nodes[0];
110 slot = path->slots[0];
111 ptr = btrfs_item_ptr_offset(l, slot);
112 write_extent_buffer(l, item, ptr, sizeof(*item));
113 btrfs_mark_buffer_dirty(path->nodes[0]);
114out:
115 btrfs_free_path(path);
116 return ret;
117}
118
119int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
120 *root, struct btrfs_key *key, struct btrfs_root_item
121 *item)
122{
123 int ret;
124 ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
125 return ret;
126}
127
128/*
129 * at mount time we want to find all the old transaction snapshots that were in
130 * the process of being deleted if we crashed. This is any root item with an
131 * offset lower than the latest root. They need to be queued for deletion to
132 * finish what was happening when we crashed.
133 */
134int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
135{
136 struct btrfs_root *dead_root;
137 struct btrfs_root_item *ri;
138 struct btrfs_key key;
139 struct btrfs_key found_key;
140 struct btrfs_path *path;
141 int ret;
142 u32 nritems;
143 struct extent_buffer *leaf;
144 int slot;
145
146 key.objectid = objectid;
147 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
148 key.offset = 0;
149 path = btrfs_alloc_path();
150 if (!path)
151 return -ENOMEM;
152
153again:
154 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
155 if (ret < 0)
156 goto err;
157 while (1) {
158 leaf = path->nodes[0];
159 nritems = btrfs_header_nritems(leaf);
160 slot = path->slots[0];
161 if (slot >= nritems) {
162 ret = btrfs_next_leaf(root, path);
163 if (ret)
164 break;
165 leaf = path->nodes[0];
166 nritems = btrfs_header_nritems(leaf);
167 slot = path->slots[0];
168 }
169 btrfs_item_key_to_cpu(leaf, &key, slot);
170 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
171 goto next;
172
173 if (key.objectid < objectid)
174 goto next;
175
176 if (key.objectid > objectid)
177 break;
178
179 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
180 if (btrfs_disk_root_refs(leaf, ri) != 0)
181 goto next;
182
183 memcpy(&found_key, &key, sizeof(key));
184 key.offset++;
185 btrfs_release_path(path);
186 dead_root =
187 btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
188 &found_key);
189 if (IS_ERR(dead_root)) {
190 ret = PTR_ERR(dead_root);
191 goto err;
192 }
193
194 ret = btrfs_add_dead_root(dead_root);
195 if (ret)
196 goto err;
197 goto again;
198next:
199 slot++;
200 path->slots[0]++;
201 }
202 ret = 0;
203err:
204 btrfs_free_path(path);
205 return ret;
206}
207
208int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
209{
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 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
257 &root_key);
258 if (!IS_ERR(root))
259 continue;
260
261 ret = PTR_ERR(root);
262 if (ret != -ENOENT) {
263 err = ret;
264 break;
265 }
266
267 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
268 if (ret) {
269 err = ret;
270 break;
271 }
272 }
273
274 btrfs_free_path(path);
275 return err;
276}
277
278/* drop the root item for 'key' from 'root' */
279int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
280 struct btrfs_key *key)
281{
282 struct btrfs_path *path;
283 int ret;
284 struct btrfs_root_item *ri;
285 struct extent_buffer *leaf;
286
287 path = btrfs_alloc_path();
288 if (!path)
289 return -ENOMEM;
290 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
291 if (ret < 0)
292 goto out;
293
294 BUG_ON(ret != 0);
295 leaf = path->nodes[0];
296 ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
297
298 ret = btrfs_del_item(trans, root, path);
299out:
300 btrfs_free_path(path);
301 return ret;
302}
303
304int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
305 struct btrfs_root *tree_root,
306 u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
307 const char *name, int name_len)
308
309{
310 struct btrfs_path *path;
311 struct btrfs_root_ref *ref;
312 struct extent_buffer *leaf;
313 struct btrfs_key key;
314 unsigned long ptr;
315 int err = 0;
316 int ret;
317
318 path = btrfs_alloc_path();
319 if (!path)
320 return -ENOMEM;
321
322 key.objectid = root_id;
323 key.type = BTRFS_ROOT_BACKREF_KEY;
324 key.offset = ref_id;
325again:
326 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
327 BUG_ON(ret < 0);
328 if (ret == 0) {
329 leaf = path->nodes[0];
330 ref = btrfs_item_ptr(leaf, path->slots[0],
331 struct btrfs_root_ref);
332
333 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
334 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
335 ptr = (unsigned long)(ref + 1);
336 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
337 *sequence = btrfs_root_ref_sequence(leaf, ref);
338
339 ret = btrfs_del_item(trans, tree_root, path);
340 if (ret) {
341 err = ret;
342 goto out;
343 }
344 } else
345 err = -ENOENT;
346
347 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
348 btrfs_release_path(path);
349 key.objectid = ref_id;
350 key.type = BTRFS_ROOT_REF_KEY;
351 key.offset = root_id;
352 goto again;
353 }
354
355out:
356 btrfs_free_path(path);
357 return err;
358}
359
360int btrfs_find_root_ref(struct btrfs_root *tree_root,
361 struct btrfs_path *path,
362 u64 root_id, u64 ref_id)
363{
364 struct btrfs_key key;
365 int ret;
366
367 key.objectid = root_id;
368 key.type = BTRFS_ROOT_REF_KEY;
369 key.offset = ref_id;
370
371 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
372 return ret;
373}
374
375/*
376 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
377 * or BTRFS_ROOT_BACKREF_KEY.
378 *
379 * The dirid, sequence, name and name_len refer to the directory entry
380 * that is referencing the root.
381 *
382 * For a forward ref, the root_id is the id of the tree referencing
383 * the root and ref_id is the id of the subvol or snapshot.
384 *
385 * For a back ref the root_id is the id of the subvol or snapshot and
386 * ref_id is the id of the tree referencing it.
387 */
388int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
389 struct btrfs_root *tree_root,
390 u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
391 const char *name, int name_len)
392{
393 struct btrfs_key key;
394 int ret;
395 struct btrfs_path *path;
396 struct btrfs_root_ref *ref;
397 struct extent_buffer *leaf;
398 unsigned long ptr;
399
400 path = btrfs_alloc_path();
401 if (!path)
402 return -ENOMEM;
403
404 key.objectid = root_id;
405 key.type = BTRFS_ROOT_BACKREF_KEY;
406 key.offset = ref_id;
407again:
408 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
409 sizeof(*ref) + name_len);
410 BUG_ON(ret);
411
412 leaf = path->nodes[0];
413 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
414 btrfs_set_root_ref_dirid(leaf, ref, dirid);
415 btrfs_set_root_ref_sequence(leaf, ref, sequence);
416 btrfs_set_root_ref_name_len(leaf, ref, name_len);
417 ptr = (unsigned long)(ref + 1);
418 write_extent_buffer(leaf, name, ptr, name_len);
419 btrfs_mark_buffer_dirty(leaf);
420
421 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
422 btrfs_release_path(path);
423 key.objectid = ref_id;
424 key.type = BTRFS_ROOT_REF_KEY;
425 key.offset = root_id;
426 goto again;
427 }
428
429 btrfs_free_path(path);
430 return 0;
431}
432
433/*
434 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
435 * for subvolumes. To work around this problem, we steal a bit from
436 * root_item->inode_item->flags, and use it to indicate if those fields
437 * have been properly initialized.
438 */
439void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
440{
441 u64 inode_flags = le64_to_cpu(root_item->inode.flags);
442
443 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
444 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
445 root_item->inode.flags = cpu_to_le64(inode_flags);
446 root_item->flags = 0;
447 root_item->byte_limit = 0;
448 }
449}
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 "ctree.h"
20#include "transaction.h"
21#include "disk-io.h"
22#include "print-tree.h"
23
24/*
25 * lookup the root with the highest offset for a given objectid. The key we do
26 * find is copied into 'key'. If we find something return 0, otherwise 1, < 0
27 * on error.
28 */
29int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
30 struct btrfs_root_item *item, struct btrfs_key *key)
31{
32 struct btrfs_path *path;
33 struct btrfs_key search_key;
34 struct btrfs_key found_key;
35 struct extent_buffer *l;
36 int ret;
37 int slot;
38
39 search_key.objectid = objectid;
40 search_key.type = BTRFS_ROOT_ITEM_KEY;
41 search_key.offset = (u64)-1;
42
43 path = btrfs_alloc_path();
44 if (!path)
45 return -ENOMEM;
46 ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
47 if (ret < 0)
48 goto out;
49
50 BUG_ON(ret == 0);
51 if (path->slots[0] == 0) {
52 ret = 1;
53 goto out;
54 }
55 l = path->nodes[0];
56 slot = path->slots[0] - 1;
57 btrfs_item_key_to_cpu(l, &found_key, slot);
58 if (found_key.objectid != objectid ||
59 found_key.type != BTRFS_ROOT_ITEM_KEY) {
60 ret = 1;
61 goto out;
62 }
63 if (item)
64 read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
65 sizeof(*item));
66 if (key)
67 memcpy(key, &found_key, sizeof(found_key));
68 ret = 0;
69out:
70 btrfs_free_path(path);
71 return ret;
72}
73
74void btrfs_set_root_node(struct btrfs_root_item *item,
75 struct extent_buffer *node)
76{
77 btrfs_set_root_bytenr(item, node->start);
78 btrfs_set_root_level(item, btrfs_header_level(node));
79 btrfs_set_root_generation(item, btrfs_header_generation(node));
80}
81
82/*
83 * copy the data in 'item' into the btree
84 */
85int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
86 *root, struct btrfs_key *key, struct btrfs_root_item
87 *item)
88{
89 struct btrfs_path *path;
90 struct extent_buffer *l;
91 int ret;
92 int slot;
93 unsigned long ptr;
94
95 path = btrfs_alloc_path();
96 if (!path)
97 return -ENOMEM;
98
99 ret = btrfs_search_slot(trans, root, key, path, 0, 1);
100 if (ret < 0) {
101 btrfs_abort_transaction(trans, root, ret);
102 goto out;
103 }
104
105 if (ret != 0) {
106 btrfs_print_leaf(root, path->nodes[0]);
107 printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
108 (unsigned long long)key->objectid, key->type,
109 (unsigned long long)key->offset);
110 BUG_ON(1);
111 }
112
113 l = path->nodes[0];
114 slot = path->slots[0];
115 ptr = btrfs_item_ptr_offset(l, slot);
116 write_extent_buffer(l, item, ptr, sizeof(*item));
117 btrfs_mark_buffer_dirty(path->nodes[0]);
118out:
119 btrfs_free_path(path);
120 return ret;
121}
122
123int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
124 struct btrfs_key *key, struct btrfs_root_item *item)
125{
126 return btrfs_insert_item(trans, root, key, item, sizeof(*item));
127}
128
129/*
130 * at mount time we want to find all the old transaction snapshots that were in
131 * the process of being deleted if we crashed. This is any root item with an
132 * offset lower than the latest root. They need to be queued for deletion to
133 * finish what was happening when we crashed.
134 */
135int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
136{
137 struct btrfs_root *dead_root;
138 struct btrfs_root_item *ri;
139 struct btrfs_key key;
140 struct btrfs_key found_key;
141 struct btrfs_path *path;
142 int ret;
143 u32 nritems;
144 struct extent_buffer *leaf;
145 int slot;
146
147 key.objectid = objectid;
148 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
149 key.offset = 0;
150 path = btrfs_alloc_path();
151 if (!path)
152 return -ENOMEM;
153
154again:
155 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
156 if (ret < 0)
157 goto err;
158 while (1) {
159 leaf = path->nodes[0];
160 nritems = btrfs_header_nritems(leaf);
161 slot = path->slots[0];
162 if (slot >= nritems) {
163 ret = btrfs_next_leaf(root, path);
164 if (ret)
165 break;
166 leaf = path->nodes[0];
167 nritems = btrfs_header_nritems(leaf);
168 slot = path->slots[0];
169 }
170 btrfs_item_key_to_cpu(leaf, &key, slot);
171 if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
172 goto next;
173
174 if (key.objectid < objectid)
175 goto next;
176
177 if (key.objectid > objectid)
178 break;
179
180 ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
181 if (btrfs_disk_root_refs(leaf, ri) != 0)
182 goto next;
183
184 memcpy(&found_key, &key, sizeof(key));
185 key.offset++;
186 btrfs_release_path(path);
187 dead_root =
188 btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
189 &found_key);
190 if (IS_ERR(dead_root)) {
191 ret = PTR_ERR(dead_root);
192 goto err;
193 }
194
195 ret = btrfs_add_dead_root(dead_root);
196 if (ret)
197 goto err;
198 goto again;
199next:
200 slot++;
201 path->slots[0]++;
202 }
203 ret = 0;
204err:
205 btrfs_free_path(path);
206 return ret;
207}
208
209int btrfs_find_orphan_roots(struct btrfs_root *tree_root)
210{
211 struct extent_buffer *leaf;
212 struct btrfs_path *path;
213 struct btrfs_key key;
214 struct btrfs_key root_key;
215 struct btrfs_root *root;
216 int err = 0;
217 int ret;
218
219 path = btrfs_alloc_path();
220 if (!path)
221 return -ENOMEM;
222
223 key.objectid = BTRFS_ORPHAN_OBJECTID;
224 key.type = BTRFS_ORPHAN_ITEM_KEY;
225 key.offset = 0;
226
227 root_key.type = BTRFS_ROOT_ITEM_KEY;
228 root_key.offset = (u64)-1;
229
230 while (1) {
231 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
232 if (ret < 0) {
233 err = ret;
234 break;
235 }
236
237 leaf = path->nodes[0];
238 if (path->slots[0] >= btrfs_header_nritems(leaf)) {
239 ret = btrfs_next_leaf(tree_root, path);
240 if (ret < 0)
241 err = ret;
242 if (ret != 0)
243 break;
244 leaf = path->nodes[0];
245 }
246
247 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
248 btrfs_release_path(path);
249
250 if (key.objectid != BTRFS_ORPHAN_OBJECTID ||
251 key.type != BTRFS_ORPHAN_ITEM_KEY)
252 break;
253
254 root_key.objectid = key.offset;
255 key.offset++;
256
257 root = btrfs_read_fs_root_no_name(tree_root->fs_info,
258 &root_key);
259 if (!IS_ERR(root))
260 continue;
261
262 ret = PTR_ERR(root);
263 if (ret != -ENOENT) {
264 err = ret;
265 break;
266 }
267
268 ret = btrfs_find_dead_roots(tree_root, root_key.objectid);
269 if (ret) {
270 err = ret;
271 break;
272 }
273 }
274
275 btrfs_free_path(path);
276 return err;
277}
278
279/* drop the root item for 'key' from 'root' */
280int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
281 struct btrfs_key *key)
282{
283 struct btrfs_path *path;
284 int ret;
285 struct btrfs_root_item *ri;
286 struct extent_buffer *leaf;
287
288 path = btrfs_alloc_path();
289 if (!path)
290 return -ENOMEM;
291 ret = btrfs_search_slot(trans, root, key, path, -1, 1);
292 if (ret < 0)
293 goto out;
294
295 BUG_ON(ret != 0);
296 leaf = path->nodes[0];
297 ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
298
299 ret = btrfs_del_item(trans, root, path);
300out:
301 btrfs_free_path(path);
302 return ret;
303}
304
305int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
306 struct btrfs_root *tree_root,
307 u64 root_id, u64 ref_id, u64 dirid, u64 *sequence,
308 const char *name, int name_len)
309
310{
311 struct btrfs_path *path;
312 struct btrfs_root_ref *ref;
313 struct extent_buffer *leaf;
314 struct btrfs_key key;
315 unsigned long ptr;
316 int err = 0;
317 int ret;
318
319 path = btrfs_alloc_path();
320 if (!path)
321 return -ENOMEM;
322
323 key.objectid = root_id;
324 key.type = BTRFS_ROOT_BACKREF_KEY;
325 key.offset = ref_id;
326again:
327 ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
328 BUG_ON(ret < 0);
329 if (ret == 0) {
330 leaf = path->nodes[0];
331 ref = btrfs_item_ptr(leaf, path->slots[0],
332 struct btrfs_root_ref);
333
334 WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
335 WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
336 ptr = (unsigned long)(ref + 1);
337 WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
338 *sequence = btrfs_root_ref_sequence(leaf, ref);
339
340 ret = btrfs_del_item(trans, tree_root, path);
341 if (ret) {
342 err = ret;
343 goto out;
344 }
345 } else
346 err = -ENOENT;
347
348 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
349 btrfs_release_path(path);
350 key.objectid = ref_id;
351 key.type = BTRFS_ROOT_REF_KEY;
352 key.offset = root_id;
353 goto again;
354 }
355
356out:
357 btrfs_free_path(path);
358 return err;
359}
360
361int btrfs_find_root_ref(struct btrfs_root *tree_root,
362 struct btrfs_path *path,
363 u64 root_id, u64 ref_id)
364{
365 struct btrfs_key key;
366 int ret;
367
368 key.objectid = root_id;
369 key.type = BTRFS_ROOT_REF_KEY;
370 key.offset = ref_id;
371
372 ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
373 return ret;
374}
375
376/*
377 * add a btrfs_root_ref item. type is either BTRFS_ROOT_REF_KEY
378 * or BTRFS_ROOT_BACKREF_KEY.
379 *
380 * The dirid, sequence, name and name_len refer to the directory entry
381 * that is referencing the root.
382 *
383 * For a forward ref, the root_id is the id of the tree referencing
384 * the root and ref_id is the id of the subvol or snapshot.
385 *
386 * For a back ref the root_id is the id of the subvol or snapshot and
387 * ref_id is the id of the tree referencing it.
388 *
389 * Will return 0, -ENOMEM, or anything from the CoW path
390 */
391int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
392 struct btrfs_root *tree_root,
393 u64 root_id, u64 ref_id, u64 dirid, u64 sequence,
394 const char *name, int name_len)
395{
396 struct btrfs_key key;
397 int ret;
398 struct btrfs_path *path;
399 struct btrfs_root_ref *ref;
400 struct extent_buffer *leaf;
401 unsigned long ptr;
402
403 path = btrfs_alloc_path();
404 if (!path)
405 return -ENOMEM;
406
407 key.objectid = root_id;
408 key.type = BTRFS_ROOT_BACKREF_KEY;
409 key.offset = ref_id;
410again:
411 ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
412 sizeof(*ref) + name_len);
413 if (ret) {
414 btrfs_abort_transaction(trans, tree_root, ret);
415 btrfs_free_path(path);
416 return ret;
417 }
418
419 leaf = path->nodes[0];
420 ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
421 btrfs_set_root_ref_dirid(leaf, ref, dirid);
422 btrfs_set_root_ref_sequence(leaf, ref, sequence);
423 btrfs_set_root_ref_name_len(leaf, ref, name_len);
424 ptr = (unsigned long)(ref + 1);
425 write_extent_buffer(leaf, name, ptr, name_len);
426 btrfs_mark_buffer_dirty(leaf);
427
428 if (key.type == BTRFS_ROOT_BACKREF_KEY) {
429 btrfs_release_path(path);
430 key.objectid = ref_id;
431 key.type = BTRFS_ROOT_REF_KEY;
432 key.offset = root_id;
433 goto again;
434 }
435
436 btrfs_free_path(path);
437 return 0;
438}
439
440/*
441 * Old btrfs forgets to init root_item->flags and root_item->byte_limit
442 * for subvolumes. To work around this problem, we steal a bit from
443 * root_item->inode_item->flags, and use it to indicate if those fields
444 * have been properly initialized.
445 */
446void btrfs_check_and_init_root_item(struct btrfs_root_item *root_item)
447{
448 u64 inode_flags = le64_to_cpu(root_item->inode.flags);
449
450 if (!(inode_flags & BTRFS_INODE_ROOT_ITEM_INIT)) {
451 inode_flags |= BTRFS_INODE_ROOT_ITEM_INIT;
452 root_item->inode.flags = cpu_to_le64(inode_flags);
453 root_item->flags = 0;
454 root_item->byte_limit = 0;
455 }
456}