xref: /openbmc/linux/fs/btrfs/props.c (revision de2bdb3d) 
1 /*
2  * Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
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/hashtable.h>
20 #include "props.h"
21 #include "btrfs_inode.h"
22 #include "hash.h"
23 #include "transaction.h"
24 #include "xattr.h"
25 #include "compression.h"
26 
27 #define BTRFS_PROP_HANDLERS_HT_BITS 8
28 static DEFINE_HASHTABLE(prop_handlers_ht, BTRFS_PROP_HANDLERS_HT_BITS);
29 
30 struct prop_handler {
31 	struct hlist_node node;
32 	const char *xattr_name;
33 	int (*validate)(const char *value, size_t len);
34 	int (*apply)(struct inode *inode, const char *value, size_t len);
35 	const char *(*extract)(struct inode *inode);
36 	int inheritable;
37 };
38 
39 static int prop_compression_validate(const char *value, size_t len);
40 static int prop_compression_apply(struct inode *inode,
41 				  const char *value,
42 				  size_t len);
43 static const char *prop_compression_extract(struct inode *inode);
44 
45 static struct prop_handler prop_handlers[] = {
46 	{
47 		.xattr_name = XATTR_BTRFS_PREFIX "compression",
48 		.validate = prop_compression_validate,
49 		.apply = prop_compression_apply,
50 		.extract = prop_compression_extract,
51 		.inheritable = 1
52 	},
53 };
54 
55 void __init btrfs_props_init(void)
56 {
57 	int i;
58 
59 	hash_init(prop_handlers_ht);
60 
61 	for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
62 		struct prop_handler *p = &prop_handlers[i];
63 		u64 h = btrfs_name_hash(p->xattr_name, strlen(p->xattr_name));
64 
65 		hash_add(prop_handlers_ht, &p->node, h);
66 	}
67 }
68 
69 static const struct hlist_head *find_prop_handlers_by_hash(const u64 hash)
70 {
71 	struct hlist_head *h;
72 
73 	h = &prop_handlers_ht[hash_min(hash, BTRFS_PROP_HANDLERS_HT_BITS)];
74 	if (hlist_empty(h))
75 		return NULL;
76 
77 	return h;
78 }
79 
80 static const struct prop_handler *
81 find_prop_handler(const char *name,
82 		  const struct hlist_head *handlers)
83 {
84 	struct prop_handler *h;
85 
86 	if (!handlers) {
87 		u64 hash = btrfs_name_hash(name, strlen(name));
88 
89 		handlers = find_prop_handlers_by_hash(hash);
90 		if (!handlers)
91 			return NULL;
92 	}
93 
94 	hlist_for_each_entry(h, handlers, node)
95 		if (!strcmp(h->xattr_name, name))
96 			return h;
97 
98 	return NULL;
99 }
100 
101 static int __btrfs_set_prop(struct btrfs_trans_handle *trans,
102 			    struct inode *inode,
103 			    const char *name,
104 			    const char *value,
105 			    size_t value_len,
106 			    int flags)
107 {
108 	const struct prop_handler *handler;
109 	int ret;
110 
111 	if (strlen(name) <= XATTR_BTRFS_PREFIX_LEN)
112 		return -EINVAL;
113 
114 	handler = find_prop_handler(name, NULL);
115 	if (!handler)
116 		return -EINVAL;
117 
118 	if (value_len == 0) {
119 		ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
120 				       NULL, 0, flags);
121 		if (ret)
122 			return ret;
123 
124 		ret = handler->apply(inode, NULL, 0);
125 		ASSERT(ret == 0);
126 
127 		return ret;
128 	}
129 
130 	ret = handler->validate(value, value_len);
131 	if (ret)
132 		return ret;
133 	ret = __btrfs_setxattr(trans, inode, handler->xattr_name,
134 			       value, value_len, flags);
135 	if (ret)
136 		return ret;
137 	ret = handler->apply(inode, value, value_len);
138 	if (ret) {
139 		__btrfs_setxattr(trans, inode, handler->xattr_name,
140 				 NULL, 0, flags);
141 		return ret;
142 	}
143 
144 	set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
145 
146 	return 0;
147 }
148 
149 int btrfs_set_prop(struct inode *inode,
150 		   const char *name,
151 		   const char *value,
152 		   size_t value_len,
153 		   int flags)
154 {
155 	return __btrfs_set_prop(NULL, inode, name, value, value_len, flags);
156 }
157 
158 static int iterate_object_props(struct btrfs_root *root,
159 				struct btrfs_path *path,
160 				u64 objectid,
161 				void (*iterator)(void *,
162 						 const struct prop_handler *,
163 						 const char *,
164 						 size_t),
165 				void *ctx)
166 {
167 	int ret;
168 	char *name_buf = NULL;
169 	char *value_buf = NULL;
170 	int name_buf_len = 0;
171 	int value_buf_len = 0;
172 
173 	while (1) {
174 		struct btrfs_key key;
175 		struct btrfs_dir_item *di;
176 		struct extent_buffer *leaf;
177 		u32 total_len, cur, this_len;
178 		int slot;
179 		const struct hlist_head *handlers;
180 
181 		slot = path->slots[0];
182 		leaf = path->nodes[0];
183 
184 		if (slot >= btrfs_header_nritems(leaf)) {
185 			ret = btrfs_next_leaf(root, path);
186 			if (ret < 0)
187 				goto out;
188 			else if (ret > 0)
189 				break;
190 			continue;
191 		}
192 
193 		btrfs_item_key_to_cpu(leaf, &key, slot);
194 		if (key.objectid != objectid)
195 			break;
196 		if (key.type != BTRFS_XATTR_ITEM_KEY)
197 			break;
198 
199 		handlers = find_prop_handlers_by_hash(key.offset);
200 		if (!handlers)
201 			goto next_slot;
202 
203 		di = btrfs_item_ptr(leaf, slot, struct btrfs_dir_item);
204 		cur = 0;
205 		total_len = btrfs_item_size_nr(leaf, slot);
206 
207 		while (cur < total_len) {
208 			u32 name_len = btrfs_dir_name_len(leaf, di);
209 			u32 data_len = btrfs_dir_data_len(leaf, di);
210 			unsigned long name_ptr, data_ptr;
211 			const struct prop_handler *handler;
212 
213 			this_len = sizeof(*di) + name_len + data_len;
214 			name_ptr = (unsigned long)(di + 1);
215 			data_ptr = name_ptr + name_len;
216 
217 			if (name_len <= XATTR_BTRFS_PREFIX_LEN ||
218 			    memcmp_extent_buffer(leaf, XATTR_BTRFS_PREFIX,
219 						 name_ptr,
220 						 XATTR_BTRFS_PREFIX_LEN))
221 				goto next_dir_item;
222 
223 			if (name_len >= name_buf_len) {
224 				kfree(name_buf);
225 				name_buf_len = name_len + 1;
226 				name_buf = kmalloc(name_buf_len, GFP_NOFS);
227 				if (!name_buf) {
228 					ret = -ENOMEM;
229 					goto out;
230 				}
231 			}
232 			read_extent_buffer(leaf, name_buf, name_ptr, name_len);
233 			name_buf[name_len] = '\0';
234 
235 			handler = find_prop_handler(name_buf, handlers);
236 			if (!handler)
237 				goto next_dir_item;
238 
239 			if (data_len > value_buf_len) {
240 				kfree(value_buf);
241 				value_buf_len = data_len;
242 				value_buf = kmalloc(data_len, GFP_NOFS);
243 				if (!value_buf) {
244 					ret = -ENOMEM;
245 					goto out;
246 				}
247 			}
248 			read_extent_buffer(leaf, value_buf, data_ptr, data_len);
249 
250 			iterator(ctx, handler, value_buf, data_len);
251 next_dir_item:
252 			cur += this_len;
253 			di = (struct btrfs_dir_item *)((char *) di + this_len);
254 		}
255 
256 next_slot:
257 		path->slots[0]++;
258 	}
259 
260 	ret = 0;
261 out:
262 	btrfs_release_path(path);
263 	kfree(name_buf);
264 	kfree(value_buf);
265 
266 	return ret;
267 }
268 
269 static void inode_prop_iterator(void *ctx,
270 				const struct prop_handler *handler,
271 				const char *value,
272 				size_t len)
273 {
274 	struct inode *inode = ctx;
275 	struct btrfs_root *root = BTRFS_I(inode)->root;
276 	int ret;
277 
278 	ret = handler->apply(inode, value, len);
279 	if (unlikely(ret))
280 		btrfs_warn(root->fs_info,
281 			   "error applying prop %s to ino %llu (root %llu): %d",
282 			   handler->xattr_name, btrfs_ino(inode),
283 			   root->root_key.objectid, ret);
284 	else
285 		set_bit(BTRFS_INODE_HAS_PROPS, &BTRFS_I(inode)->runtime_flags);
286 }
287 
288 int btrfs_load_inode_props(struct inode *inode, struct btrfs_path *path)
289 {
290 	struct btrfs_root *root = BTRFS_I(inode)->root;
291 	u64 ino = btrfs_ino(inode);
292 	int ret;
293 
294 	ret = iterate_object_props(root, path, ino, inode_prop_iterator, inode);
295 
296 	return ret;
297 }
298 
299 static int inherit_props(struct btrfs_trans_handle *trans,
300 			 struct inode *inode,
301 			 struct inode *parent)
302 {
303 	struct btrfs_root *root = BTRFS_I(inode)->root;
304 	int ret;
305 	int i;
306 
307 	if (!test_bit(BTRFS_INODE_HAS_PROPS,
308 		      &BTRFS_I(parent)->runtime_flags))
309 		return 0;
310 
311 	for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
312 		const struct prop_handler *h = &prop_handlers[i];
313 		const char *value;
314 		u64 num_bytes;
315 
316 		if (!h->inheritable)
317 			continue;
318 
319 		value = h->extract(parent);
320 		if (!value)
321 			continue;
322 
323 		num_bytes = btrfs_calc_trans_metadata_size(root, 1);
324 		ret = btrfs_block_rsv_add(root, trans->block_rsv,
325 					  num_bytes, BTRFS_RESERVE_NO_FLUSH);
326 		if (ret)
327 			goto out;
328 		ret = __btrfs_set_prop(trans, inode, h->xattr_name,
329 				       value, strlen(value), 0);
330 		btrfs_block_rsv_release(root, trans->block_rsv, num_bytes);
331 		if (ret)
332 			goto out;
333 	}
334 	ret = 0;
335 out:
336 	return ret;
337 }
338 
339 int btrfs_inode_inherit_props(struct btrfs_trans_handle *trans,
340 			      struct inode *inode,
341 			      struct inode *dir)
342 {
343 	if (!dir)
344 		return 0;
345 
346 	return inherit_props(trans, inode, dir);
347 }
348 
349 int btrfs_subvol_inherit_props(struct btrfs_trans_handle *trans,
350 			       struct btrfs_root *root,
351 			       struct btrfs_root *parent_root)
352 {
353 	struct super_block *sb = root->fs_info->sb;
354 	struct btrfs_key key;
355 	struct inode *parent_inode, *child_inode;
356 	int ret;
357 
358 	key.objectid = BTRFS_FIRST_FREE_OBJECTID;
359 	key.type = BTRFS_INODE_ITEM_KEY;
360 	key.offset = 0;
361 
362 	parent_inode = btrfs_iget(sb, &key, parent_root, NULL);
363 	if (IS_ERR(parent_inode))
364 		return PTR_ERR(parent_inode);
365 
366 	child_inode = btrfs_iget(sb, &key, root, NULL);
367 	if (IS_ERR(child_inode)) {
368 		iput(parent_inode);
369 		return PTR_ERR(child_inode);
370 	}
371 
372 	ret = inherit_props(trans, child_inode, parent_inode);
373 	iput(child_inode);
374 	iput(parent_inode);
375 
376 	return ret;
377 }
378 
379 static int prop_compression_validate(const char *value, size_t len)
380 {
381 	if (!strncmp("lzo", value, len))
382 		return 0;
383 	else if (!strncmp("zlib", value, len))
384 		return 0;
385 
386 	return -EINVAL;
387 }
388 
389 static int prop_compression_apply(struct inode *inode,
390 				  const char *value,
391 				  size_t len)
392 {
393 	int type;
394 
395 	if (len == 0) {
396 		BTRFS_I(inode)->flags |= BTRFS_INODE_NOCOMPRESS;
397 		BTRFS_I(inode)->flags &= ~BTRFS_INODE_COMPRESS;
398 		BTRFS_I(inode)->force_compress = BTRFS_COMPRESS_NONE;
399 
400 		return 0;
401 	}
402 
403 	if (!strncmp("lzo", value, len))
404 		type = BTRFS_COMPRESS_LZO;
405 	else if (!strncmp("zlib", value, len))
406 		type = BTRFS_COMPRESS_ZLIB;
407 	else
408 		return -EINVAL;
409 
410 	BTRFS_I(inode)->flags &= ~BTRFS_INODE_NOCOMPRESS;
411 	BTRFS_I(inode)->flags |= BTRFS_INODE_COMPRESS;
412 	BTRFS_I(inode)->force_compress = type;
413 
414 	return 0;
415 }
416 
417 static const char *prop_compression_extract(struct inode *inode)
418 {
419 	switch (BTRFS_I(inode)->force_compress) {
420 	case BTRFS_COMPRESS_ZLIB:
421 		return "zlib";
422 	case BTRFS_COMPRESS_LZO:
423 		return "lzo";
424 	}
425 
426 	return NULL;
427 }
428 
429 
430