xref: /openbmc/linux/fs/btrfs/uuid-tree.c (revision eb3fcf00)
1 /*
2  * Copyright (C) STRATO AG 2013.  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 #include <linux/uuid.h>
19 #include <asm/unaligned.h>
20 #include "ctree.h"
21 #include "transaction.h"
22 #include "disk-io.h"
23 #include "print-tree.h"
24 
25 
26 static void btrfs_uuid_to_key(u8 *uuid, u8 type, struct btrfs_key *key)
27 {
28 	key->type = type;
29 	key->objectid = get_unaligned_le64(uuid);
30 	key->offset = get_unaligned_le64(uuid + sizeof(u64));
31 }
32 
33 /* return -ENOENT for !found, < 0 for errors, or 0 if an item was found */
34 static int btrfs_uuid_tree_lookup(struct btrfs_root *uuid_root, u8 *uuid,
35 				  u8 type, u64 subid)
36 {
37 	int ret;
38 	struct btrfs_path *path = NULL;
39 	struct extent_buffer *eb;
40 	int slot;
41 	u32 item_size;
42 	unsigned long offset;
43 	struct btrfs_key key;
44 
45 	if (WARN_ON_ONCE(!uuid_root)) {
46 		ret = -ENOENT;
47 		goto out;
48 	}
49 
50 	path = btrfs_alloc_path();
51 	if (!path) {
52 		ret = -ENOMEM;
53 		goto out;
54 	}
55 
56 	btrfs_uuid_to_key(uuid, type, &key);
57 	ret = btrfs_search_slot(NULL, uuid_root, &key, path, 0, 0);
58 	if (ret < 0) {
59 		goto out;
60 	} else if (ret > 0) {
61 		ret = -ENOENT;
62 		goto out;
63 	}
64 
65 	eb = path->nodes[0];
66 	slot = path->slots[0];
67 	item_size = btrfs_item_size_nr(eb, slot);
68 	offset = btrfs_item_ptr_offset(eb, slot);
69 	ret = -ENOENT;
70 
71 	if (!IS_ALIGNED(item_size, sizeof(u64))) {
72 		btrfs_warn(uuid_root->fs_info, "uuid item with illegal size %lu!",
73 			(unsigned long)item_size);
74 		goto out;
75 	}
76 	while (item_size) {
77 		__le64 data;
78 
79 		read_extent_buffer(eb, &data, offset, sizeof(data));
80 		if (le64_to_cpu(data) == subid) {
81 			ret = 0;
82 			break;
83 		}
84 		offset += sizeof(data);
85 		item_size -= sizeof(data);
86 	}
87 
88 out:
89 	btrfs_free_path(path);
90 	return ret;
91 }
92 
93 int btrfs_uuid_tree_add(struct btrfs_trans_handle *trans,
94 			struct btrfs_root *uuid_root, u8 *uuid, u8 type,
95 			u64 subid_cpu)
96 {
97 	int ret;
98 	struct btrfs_path *path = NULL;
99 	struct btrfs_key key;
100 	struct extent_buffer *eb;
101 	int slot;
102 	unsigned long offset;
103 	__le64 subid_le;
104 
105 	ret = btrfs_uuid_tree_lookup(uuid_root, uuid, type, subid_cpu);
106 	if (ret != -ENOENT)
107 		return ret;
108 
109 	if (WARN_ON_ONCE(!uuid_root)) {
110 		ret = -EINVAL;
111 		goto out;
112 	}
113 
114 	btrfs_uuid_to_key(uuid, type, &key);
115 
116 	path = btrfs_alloc_path();
117 	if (!path) {
118 		ret = -ENOMEM;
119 		goto out;
120 	}
121 
122 	ret = btrfs_insert_empty_item(trans, uuid_root, path, &key,
123 				      sizeof(subid_le));
124 	if (ret >= 0) {
125 		/* Add an item for the type for the first time */
126 		eb = path->nodes[0];
127 		slot = path->slots[0];
128 		offset = btrfs_item_ptr_offset(eb, slot);
129 	} else if (ret == -EEXIST) {
130 		/*
131 		 * An item with that type already exists.
132 		 * Extend the item and store the new subid at the end.
133 		 */
134 		btrfs_extend_item(uuid_root, path, sizeof(subid_le));
135 		eb = path->nodes[0];
136 		slot = path->slots[0];
137 		offset = btrfs_item_ptr_offset(eb, slot);
138 		offset += btrfs_item_size_nr(eb, slot) - sizeof(subid_le);
139 	} else if (ret < 0) {
140 		btrfs_warn(uuid_root->fs_info, "insert uuid item failed %d "
141 			"(0x%016llx, 0x%016llx) type %u!",
142 			ret, (unsigned long long)key.objectid,
143 			(unsigned long long)key.offset, type);
144 		goto out;
145 	}
146 
147 	ret = 0;
148 	subid_le = cpu_to_le64(subid_cpu);
149 	write_extent_buffer(eb, &subid_le, offset, sizeof(subid_le));
150 	btrfs_mark_buffer_dirty(eb);
151 
152 out:
153 	btrfs_free_path(path);
154 	return ret;
155 }
156 
157 int btrfs_uuid_tree_rem(struct btrfs_trans_handle *trans,
158 			struct btrfs_root *uuid_root, u8 *uuid, u8 type,
159 			u64 subid)
160 {
161 	int ret;
162 	struct btrfs_path *path = NULL;
163 	struct btrfs_key key;
164 	struct extent_buffer *eb;
165 	int slot;
166 	unsigned long offset;
167 	u32 item_size;
168 	unsigned long move_dst;
169 	unsigned long move_src;
170 	unsigned long move_len;
171 
172 	if (WARN_ON_ONCE(!uuid_root)) {
173 		ret = -EINVAL;
174 		goto out;
175 	}
176 
177 	btrfs_uuid_to_key(uuid, type, &key);
178 
179 	path = btrfs_alloc_path();
180 	if (!path) {
181 		ret = -ENOMEM;
182 		goto out;
183 	}
184 
185 	ret = btrfs_search_slot(trans, uuid_root, &key, path, -1, 1);
186 	if (ret < 0) {
187 		btrfs_warn(uuid_root->fs_info, "error %d while searching for uuid item!",
188 			ret);
189 		goto out;
190 	}
191 	if (ret > 0) {
192 		ret = -ENOENT;
193 		goto out;
194 	}
195 
196 	eb = path->nodes[0];
197 	slot = path->slots[0];
198 	offset = btrfs_item_ptr_offset(eb, slot);
199 	item_size = btrfs_item_size_nr(eb, slot);
200 	if (!IS_ALIGNED(item_size, sizeof(u64))) {
201 		btrfs_warn(uuid_root->fs_info, "uuid item with illegal size %lu!",
202 			(unsigned long)item_size);
203 		ret = -ENOENT;
204 		goto out;
205 	}
206 	while (item_size) {
207 		__le64 read_subid;
208 
209 		read_extent_buffer(eb, &read_subid, offset, sizeof(read_subid));
210 		if (le64_to_cpu(read_subid) == subid)
211 			break;
212 		offset += sizeof(read_subid);
213 		item_size -= sizeof(read_subid);
214 	}
215 
216 	if (!item_size) {
217 		ret = -ENOENT;
218 		goto out;
219 	}
220 
221 	item_size = btrfs_item_size_nr(eb, slot);
222 	if (item_size == sizeof(subid)) {
223 		ret = btrfs_del_item(trans, uuid_root, path);
224 		goto out;
225 	}
226 
227 	move_dst = offset;
228 	move_src = offset + sizeof(subid);
229 	move_len = item_size - (move_src - btrfs_item_ptr_offset(eb, slot));
230 	memmove_extent_buffer(eb, move_dst, move_src, move_len);
231 	btrfs_truncate_item(uuid_root, path, item_size - sizeof(subid), 1);
232 
233 out:
234 	btrfs_free_path(path);
235 	return ret;
236 }
237 
238 static int btrfs_uuid_iter_rem(struct btrfs_root *uuid_root, u8 *uuid, u8 type,
239 			       u64 subid)
240 {
241 	struct btrfs_trans_handle *trans;
242 	int ret;
243 
244 	/* 1 - for the uuid item */
245 	trans = btrfs_start_transaction(uuid_root, 1);
246 	if (IS_ERR(trans)) {
247 		ret = PTR_ERR(trans);
248 		goto out;
249 	}
250 
251 	ret = btrfs_uuid_tree_rem(trans, uuid_root, uuid, type, subid);
252 	btrfs_end_transaction(trans, uuid_root);
253 
254 out:
255 	return ret;
256 }
257 
258 int btrfs_uuid_tree_iterate(struct btrfs_fs_info *fs_info,
259 			    int (*check_func)(struct btrfs_fs_info *, u8 *, u8,
260 					      u64))
261 {
262 	struct btrfs_root *root = fs_info->uuid_root;
263 	struct btrfs_key key;
264 	struct btrfs_path *path;
265 	int ret = 0;
266 	struct extent_buffer *leaf;
267 	int slot;
268 	u32 item_size;
269 	unsigned long offset;
270 
271 	path = btrfs_alloc_path();
272 	if (!path) {
273 		ret = -ENOMEM;
274 		goto out;
275 	}
276 
277 	key.objectid = 0;
278 	key.type = 0;
279 	key.offset = 0;
280 
281 again_search_slot:
282 	ret = btrfs_search_forward(root, &key, path, 0);
283 	if (ret) {
284 		if (ret > 0)
285 			ret = 0;
286 		goto out;
287 	}
288 
289 	while (1) {
290 		cond_resched();
291 		leaf = path->nodes[0];
292 		slot = path->slots[0];
293 		btrfs_item_key_to_cpu(leaf, &key, slot);
294 
295 		if (key.type != BTRFS_UUID_KEY_SUBVOL &&
296 		    key.type != BTRFS_UUID_KEY_RECEIVED_SUBVOL)
297 			goto skip;
298 
299 		offset = btrfs_item_ptr_offset(leaf, slot);
300 		item_size = btrfs_item_size_nr(leaf, slot);
301 		if (!IS_ALIGNED(item_size, sizeof(u64))) {
302 			btrfs_warn(fs_info, "uuid item with illegal size %lu!",
303 				(unsigned long)item_size);
304 			goto skip;
305 		}
306 		while (item_size) {
307 			u8 uuid[BTRFS_UUID_SIZE];
308 			__le64 subid_le;
309 			u64 subid_cpu;
310 
311 			put_unaligned_le64(key.objectid, uuid);
312 			put_unaligned_le64(key.offset, uuid + sizeof(u64));
313 			read_extent_buffer(leaf, &subid_le, offset,
314 					   sizeof(subid_le));
315 			subid_cpu = le64_to_cpu(subid_le);
316 			ret = check_func(fs_info, uuid, key.type, subid_cpu);
317 			if (ret < 0)
318 				goto out;
319 			if (ret > 0) {
320 				btrfs_release_path(path);
321 				ret = btrfs_uuid_iter_rem(root, uuid, key.type,
322 							  subid_cpu);
323 				if (ret == 0) {
324 					/*
325 					 * this might look inefficient, but the
326 					 * justification is that it is an
327 					 * exception that check_func returns 1,
328 					 * and that in the regular case only one
329 					 * entry per UUID exists.
330 					 */
331 					goto again_search_slot;
332 				}
333 				if (ret < 0 && ret != -ENOENT)
334 					goto out;
335 			}
336 			item_size -= sizeof(subid_le);
337 			offset += sizeof(subid_le);
338 		}
339 
340 skip:
341 		ret = btrfs_next_item(root, path);
342 		if (ret == 0)
343 			continue;
344 		else if (ret > 0)
345 			ret = 0;
346 		break;
347 	}
348 
349 out:
350 	btrfs_free_path(path);
351 	if (ret)
352 		btrfs_warn(fs_info, "btrfs_uuid_tree_iterate failed %d", ret);
353 	return 0;
354 }
355