xref: /openbmc/linux/fs/btrfs/root-tree.c (revision fd589a8f)
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  *  search forward for a root, starting with objectid 'search_start'
26  *  if a root key is found, the objectid we find is filled into 'found_objectid'
27  *  and 0 is returned.  < 0 is returned on error, 1 if there is nothing
28  *  left in the tree.
29  */
30 int btrfs_search_root(struct btrfs_root *root, u64 search_start,
31 		      u64 *found_objectid)
32 {
33 	struct btrfs_path *path;
34 	struct btrfs_key search_key;
35 	int ret;
36 
37 	root = root->fs_info->tree_root;
38 	search_key.objectid = search_start;
39 	search_key.type = (u8)-1;
40 	search_key.offset = (u64)-1;
41 
42 	path = btrfs_alloc_path();
43 	BUG_ON(!path);
44 again:
45 	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
46 	if (ret < 0)
47 		goto out;
48 	if (ret == 0) {
49 		ret = 1;
50 		goto out;
51 	}
52 	if (path->slots[0] >= btrfs_header_nritems(path->nodes[0])) {
53 		ret = btrfs_next_leaf(root, path);
54 		if (ret)
55 			goto out;
56 	}
57 	btrfs_item_key_to_cpu(path->nodes[0], &search_key, path->slots[0]);
58 	if (search_key.type != BTRFS_ROOT_ITEM_KEY) {
59 		search_key.offset++;
60 		btrfs_release_path(root, path);
61 		goto again;
62 	}
63 	ret = 0;
64 	*found_objectid = search_key.objectid;
65 
66 out:
67 	btrfs_free_path(path);
68 	return ret;
69 }
70 
71 /*
72  * lookup the root with the highest offset for a given objectid.  The key we do
73  * find is copied into 'key'.  If we find something return 0, otherwise 1, < 0
74  * on error.
75  */
76 int btrfs_find_last_root(struct btrfs_root *root, u64 objectid,
77 			struct btrfs_root_item *item, struct btrfs_key *key)
78 {
79 	struct btrfs_path *path;
80 	struct btrfs_key search_key;
81 	struct btrfs_key found_key;
82 	struct extent_buffer *l;
83 	int ret;
84 	int slot;
85 
86 	search_key.objectid = objectid;
87 	search_key.type = BTRFS_ROOT_ITEM_KEY;
88 	search_key.offset = (u64)-1;
89 
90 	path = btrfs_alloc_path();
91 	BUG_ON(!path);
92 	ret = btrfs_search_slot(NULL, root, &search_key, path, 0, 0);
93 	if (ret < 0)
94 		goto out;
95 
96 	BUG_ON(ret == 0);
97 	l = path->nodes[0];
98 	BUG_ON(path->slots[0] == 0);
99 	slot = path->slots[0] - 1;
100 	btrfs_item_key_to_cpu(l, &found_key, slot);
101 	if (found_key.objectid != objectid) {
102 		ret = 1;
103 		goto out;
104 	}
105 	read_extent_buffer(l, item, btrfs_item_ptr_offset(l, slot),
106 			   sizeof(*item));
107 	memcpy(key, &found_key, sizeof(found_key));
108 	ret = 0;
109 out:
110 	btrfs_free_path(path);
111 	return ret;
112 }
113 
114 int btrfs_set_root_node(struct btrfs_root_item *item,
115 			struct extent_buffer *node)
116 {
117 	btrfs_set_root_bytenr(item, node->start);
118 	btrfs_set_root_level(item, btrfs_header_level(node));
119 	btrfs_set_root_generation(item, btrfs_header_generation(node));
120 	return 0;
121 }
122 
123 /*
124  * copy the data in 'item' into the btree
125  */
126 int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root
127 		      *root, struct btrfs_key *key, struct btrfs_root_item
128 		      *item)
129 {
130 	struct btrfs_path *path;
131 	struct extent_buffer *l;
132 	int ret;
133 	int slot;
134 	unsigned long ptr;
135 
136 	path = btrfs_alloc_path();
137 	BUG_ON(!path);
138 	ret = btrfs_search_slot(trans, root, key, path, 0, 1);
139 	if (ret < 0)
140 		goto out;
141 
142 	if (ret != 0) {
143 		btrfs_print_leaf(root, path->nodes[0]);
144 		printk(KERN_CRIT "unable to update root key %llu %u %llu\n",
145 		       (unsigned long long)key->objectid, key->type,
146 		       (unsigned long long)key->offset);
147 		BUG_ON(1);
148 	}
149 
150 	l = path->nodes[0];
151 	slot = path->slots[0];
152 	ptr = btrfs_item_ptr_offset(l, slot);
153 	write_extent_buffer(l, item, ptr, sizeof(*item));
154 	btrfs_mark_buffer_dirty(path->nodes[0]);
155 out:
156 	btrfs_release_path(root, path);
157 	btrfs_free_path(path);
158 	return ret;
159 }
160 
161 int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root
162 		      *root, struct btrfs_key *key, struct btrfs_root_item
163 		      *item)
164 {
165 	int ret;
166 	ret = btrfs_insert_item(trans, root, key, item, sizeof(*item));
167 	return ret;
168 }
169 
170 /*
171  * at mount time we want to find all the old transaction snapshots that were in
172  * the process of being deleted if we crashed.  This is any root item with an
173  * offset lower than the latest root.  They need to be queued for deletion to
174  * finish what was happening when we crashed.
175  */
176 int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid)
177 {
178 	struct btrfs_root *dead_root;
179 	struct btrfs_item *item;
180 	struct btrfs_root_item *ri;
181 	struct btrfs_key key;
182 	struct btrfs_key found_key;
183 	struct btrfs_path *path;
184 	int ret;
185 	u32 nritems;
186 	struct extent_buffer *leaf;
187 	int slot;
188 
189 	key.objectid = objectid;
190 	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
191 	key.offset = 0;
192 	path = btrfs_alloc_path();
193 	if (!path)
194 		return -ENOMEM;
195 
196 again:
197 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
198 	if (ret < 0)
199 		goto err;
200 	while (1) {
201 		leaf = path->nodes[0];
202 		nritems = btrfs_header_nritems(leaf);
203 		slot = path->slots[0];
204 		if (slot >= nritems) {
205 			ret = btrfs_next_leaf(root, path);
206 			if (ret)
207 				break;
208 			leaf = path->nodes[0];
209 			nritems = btrfs_header_nritems(leaf);
210 			slot = path->slots[0];
211 		}
212 		item = btrfs_item_nr(leaf, slot);
213 		btrfs_item_key_to_cpu(leaf, &key, slot);
214 		if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)
215 			goto next;
216 
217 		if (key.objectid < objectid)
218 			goto next;
219 
220 		if (key.objectid > objectid)
221 			break;
222 
223 		ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);
224 		if (btrfs_disk_root_refs(leaf, ri) != 0)
225 			goto next;
226 
227 		memcpy(&found_key, &key, sizeof(key));
228 		key.offset++;
229 		btrfs_release_path(root, path);
230 		dead_root =
231 			btrfs_read_fs_root_no_radix(root->fs_info->tree_root,
232 						    &found_key);
233 		if (IS_ERR(dead_root)) {
234 			ret = PTR_ERR(dead_root);
235 			goto err;
236 		}
237 
238 		ret = btrfs_add_dead_root(dead_root);
239 		if (ret)
240 			goto err;
241 		goto again;
242 next:
243 		slot++;
244 		path->slots[0]++;
245 	}
246 	ret = 0;
247 err:
248 	btrfs_free_path(path);
249 	return ret;
250 }
251 
252 /* drop the root item for 'key' from 'root' */
253 int btrfs_del_root(struct btrfs_trans_handle *trans, struct btrfs_root *root,
254 		   struct btrfs_key *key)
255 {
256 	struct btrfs_path *path;
257 	int ret;
258 	u32 refs;
259 	struct btrfs_root_item *ri;
260 	struct extent_buffer *leaf;
261 
262 	path = btrfs_alloc_path();
263 	BUG_ON(!path);
264 	ret = btrfs_search_slot(trans, root, key, path, -1, 1);
265 	if (ret < 0)
266 		goto out;
267 
268 	BUG_ON(ret != 0);
269 	leaf = path->nodes[0];
270 	ri = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_item);
271 
272 	refs = btrfs_disk_root_refs(leaf, ri);
273 	BUG_ON(refs != 0);
274 	ret = btrfs_del_item(trans, root, path);
275 out:
276 	btrfs_release_path(root, path);
277 	btrfs_free_path(path);
278 	return ret;
279 }
280 
281 #if 0 /* this will get used when snapshot deletion is implemented */
282 int btrfs_del_root_ref(struct btrfs_trans_handle *trans,
283 		       struct btrfs_root *tree_root,
284 		       u64 root_id, u8 type, u64 ref_id)
285 {
286 	struct btrfs_key key;
287 	int ret;
288 	struct btrfs_path *path;
289 
290 	path = btrfs_alloc_path();
291 
292 	key.objectid = root_id;
293 	key.type = type;
294 	key.offset = ref_id;
295 
296 	ret = btrfs_search_slot(trans, tree_root, &key, path, -1, 1);
297 	BUG_ON(ret);
298 
299 	ret = btrfs_del_item(trans, tree_root, path);
300 	BUG_ON(ret);
301 
302 	btrfs_free_path(path);
303 	return ret;
304 }
305 #endif
306 
307 int btrfs_find_root_ref(struct btrfs_root *tree_root,
308 		   struct btrfs_path *path,
309 		   u64 root_id, u64 ref_id)
310 {
311 	struct btrfs_key key;
312 	int ret;
313 
314 	key.objectid = root_id;
315 	key.type = BTRFS_ROOT_REF_KEY;
316 	key.offset = ref_id;
317 
318 	ret = btrfs_search_slot(NULL, tree_root, &key, path, 0, 0);
319 	return ret;
320 }
321 
322 
323 /*
324  * add a btrfs_root_ref item.  type is either BTRFS_ROOT_REF_KEY
325  * or BTRFS_ROOT_BACKREF_KEY.
326  *
327  * The dirid, sequence, name and name_len refer to the directory entry
328  * that is referencing the root.
329  *
330  * For a forward ref, the root_id is the id of the tree referencing
331  * the root and ref_id is the id of the subvol  or snapshot.
332  *
333  * For a back ref the root_id is the id of the subvol or snapshot and
334  * ref_id is the id of the tree referencing it.
335  */
336 int btrfs_add_root_ref(struct btrfs_trans_handle *trans,
337 		       struct btrfs_root *tree_root,
338 		       u64 root_id, u8 type, u64 ref_id,
339 		       u64 dirid, u64 sequence,
340 		       const char *name, int name_len)
341 {
342 	struct btrfs_key key;
343 	int ret;
344 	struct btrfs_path *path;
345 	struct btrfs_root_ref *ref;
346 	struct extent_buffer *leaf;
347 	unsigned long ptr;
348 
349 
350 	path = btrfs_alloc_path();
351 
352 	key.objectid = root_id;
353 	key.type = type;
354 	key.offset = ref_id;
355 
356 	ret = btrfs_insert_empty_item(trans, tree_root, path, &key,
357 				      sizeof(*ref) + name_len);
358 	BUG_ON(ret);
359 
360 	leaf = path->nodes[0];
361 	ref = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_root_ref);
362 	btrfs_set_root_ref_dirid(leaf, ref, dirid);
363 	btrfs_set_root_ref_sequence(leaf, ref, sequence);
364 	btrfs_set_root_ref_name_len(leaf, ref, name_len);
365 	ptr = (unsigned long)(ref + 1);
366 	write_extent_buffer(leaf, name, ptr, name_len);
367 	btrfs_mark_buffer_dirty(leaf);
368 
369 	btrfs_free_path(path);
370 	return ret;
371 }
372