xref: /openbmc/linux/fs/btrfs/dir-item.c (revision 1164a9fb)
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 "disk-io.h"
21 #include "hash.h"
22 #include "transaction.h"
23 
24 /*
25  * insert a name into a directory, doing overflow properly if there is a hash
26  * collision.  data_size indicates how big the item inserted should be.  On
27  * success a struct btrfs_dir_item pointer is returned, otherwise it is
28  * an ERR_PTR.
29  *
30  * The name is not copied into the dir item, you have to do that yourself.
31  */
32 static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
33 						   *trans,
34 						   struct btrfs_root *root,
35 						   struct btrfs_path *path,
36 						   struct btrfs_key *cpu_key,
37 						   u32 data_size,
38 						   const char *name,
39 						   int name_len)
40 {
41 	struct btrfs_fs_info *fs_info = root->fs_info;
42 	int ret;
43 	char *ptr;
44 	struct btrfs_item *item;
45 	struct extent_buffer *leaf;
46 
47 	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
48 	if (ret == -EEXIST) {
49 		struct btrfs_dir_item *di;
50 		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
51 		if (di)
52 			return ERR_PTR(-EEXIST);
53 		btrfs_extend_item(fs_info, path, data_size);
54 	} else if (ret < 0)
55 		return ERR_PTR(ret);
56 	WARN_ON(ret > 0);
57 	leaf = path->nodes[0];
58 	item = btrfs_item_nr(path->slots[0]);
59 	ptr = btrfs_item_ptr(leaf, path->slots[0], char);
60 	BUG_ON(data_size > btrfs_item_size(leaf, item));
61 	ptr += btrfs_item_size(leaf, item) - data_size;
62 	return (struct btrfs_dir_item *)ptr;
63 }
64 
65 /*
66  * xattrs work a lot like directories, this inserts an xattr item
67  * into the tree
68  */
69 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
70 			    struct btrfs_root *root,
71 			    struct btrfs_path *path, u64 objectid,
72 			    const char *name, u16 name_len,
73 			    const void *data, u16 data_len)
74 {
75 	int ret = 0;
76 	struct btrfs_dir_item *dir_item;
77 	unsigned long name_ptr, data_ptr;
78 	struct btrfs_key key, location;
79 	struct btrfs_disk_key disk_key;
80 	struct extent_buffer *leaf;
81 	u32 data_size;
82 
83 	if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
84 		return -ENOSPC;
85 
86 	key.objectid = objectid;
87 	key.type = BTRFS_XATTR_ITEM_KEY;
88 	key.offset = btrfs_name_hash(name, name_len);
89 
90 	data_size = sizeof(*dir_item) + name_len + data_len;
91 	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
92 					name, name_len);
93 	if (IS_ERR(dir_item))
94 		return PTR_ERR(dir_item);
95 	memset(&location, 0, sizeof(location));
96 
97 	leaf = path->nodes[0];
98 	btrfs_cpu_key_to_disk(&disk_key, &location);
99 	btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
100 	btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
101 	btrfs_set_dir_name_len(leaf, dir_item, name_len);
102 	btrfs_set_dir_transid(leaf, dir_item, trans->transid);
103 	btrfs_set_dir_data_len(leaf, dir_item, data_len);
104 	name_ptr = (unsigned long)(dir_item + 1);
105 	data_ptr = (unsigned long)((char *)name_ptr + name_len);
106 
107 	write_extent_buffer(leaf, name, name_ptr, name_len);
108 	write_extent_buffer(leaf, data, data_ptr, data_len);
109 	btrfs_mark_buffer_dirty(path->nodes[0]);
110 
111 	return ret;
112 }
113 
114 /*
115  * insert a directory item in the tree, doing all the magic for
116  * both indexes. 'dir' indicates which objectid to insert it into,
117  * 'location' is the key to stuff into the directory item, 'type' is the
118  * type of the inode we're pointing to, and 'index' is the sequence number
119  * to use for the second index (if one is created).
120  * Will return 0 or -ENOMEM
121  */
122 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
123 			  *root, const char *name, int name_len,
124 			  struct btrfs_inode *dir, struct btrfs_key *location,
125 			  u8 type, u64 index)
126 {
127 	int ret = 0;
128 	int ret2 = 0;
129 	struct btrfs_path *path;
130 	struct btrfs_dir_item *dir_item;
131 	struct extent_buffer *leaf;
132 	unsigned long name_ptr;
133 	struct btrfs_key key;
134 	struct btrfs_disk_key disk_key;
135 	u32 data_size;
136 
137 	key.objectid = btrfs_ino(dir);
138 	key.type = BTRFS_DIR_ITEM_KEY;
139 	key.offset = btrfs_name_hash(name, name_len);
140 
141 	path = btrfs_alloc_path();
142 	if (!path)
143 		return -ENOMEM;
144 	path->leave_spinning = 1;
145 
146 	btrfs_cpu_key_to_disk(&disk_key, location);
147 
148 	data_size = sizeof(*dir_item) + name_len;
149 	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
150 					name, name_len);
151 	if (IS_ERR(dir_item)) {
152 		ret = PTR_ERR(dir_item);
153 		if (ret == -EEXIST)
154 			goto second_insert;
155 		goto out_free;
156 	}
157 
158 	leaf = path->nodes[0];
159 	btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
160 	btrfs_set_dir_type(leaf, dir_item, type);
161 	btrfs_set_dir_data_len(leaf, dir_item, 0);
162 	btrfs_set_dir_name_len(leaf, dir_item, name_len);
163 	btrfs_set_dir_transid(leaf, dir_item, trans->transid);
164 	name_ptr = (unsigned long)(dir_item + 1);
165 
166 	write_extent_buffer(leaf, name, name_ptr, name_len);
167 	btrfs_mark_buffer_dirty(leaf);
168 
169 second_insert:
170 	/* FIXME, use some real flag for selecting the extra index */
171 	if (root == root->fs_info->tree_root) {
172 		ret = 0;
173 		goto out_free;
174 	}
175 	btrfs_release_path(path);
176 
177 	ret2 = btrfs_insert_delayed_dir_index(trans, root->fs_info, name,
178 			name_len, dir, &disk_key, type, index);
179 out_free:
180 	btrfs_free_path(path);
181 	if (ret)
182 		return ret;
183 	if (ret2)
184 		return ret2;
185 	return 0;
186 }
187 
188 /*
189  * lookup a directory item based on name.  'dir' is the objectid
190  * we're searching in, and 'mod' tells us if you plan on deleting the
191  * item (use mod < 0) or changing the options (use mod > 0)
192  */
193 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
194 					     struct btrfs_root *root,
195 					     struct btrfs_path *path, u64 dir,
196 					     const char *name, int name_len,
197 					     int mod)
198 {
199 	int ret;
200 	struct btrfs_key key;
201 	int ins_len = mod < 0 ? -1 : 0;
202 	int cow = mod != 0;
203 
204 	key.objectid = dir;
205 	key.type = BTRFS_DIR_ITEM_KEY;
206 
207 	key.offset = btrfs_name_hash(name, name_len);
208 
209 	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
210 	if (ret < 0)
211 		return ERR_PTR(ret);
212 	if (ret > 0)
213 		return NULL;
214 
215 	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
216 }
217 
218 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
219 				   const char *name, int name_len)
220 {
221 	int ret;
222 	struct btrfs_key key;
223 	struct btrfs_dir_item *di;
224 	int data_size;
225 	struct extent_buffer *leaf;
226 	int slot;
227 	struct btrfs_path *path;
228 
229 
230 	path = btrfs_alloc_path();
231 	if (!path)
232 		return -ENOMEM;
233 
234 	key.objectid = dir;
235 	key.type = BTRFS_DIR_ITEM_KEY;
236 	key.offset = btrfs_name_hash(name, name_len);
237 
238 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
239 
240 	/* return back any errors */
241 	if (ret < 0)
242 		goto out;
243 
244 	/* nothing found, we're safe */
245 	if (ret > 0) {
246 		ret = 0;
247 		goto out;
248 	}
249 
250 	/* we found an item, look for our name in the item */
251 	di = btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
252 	if (di) {
253 		/* our exact name was found */
254 		ret = -EEXIST;
255 		goto out;
256 	}
257 
258 	/*
259 	 * see if there is room in the item to insert this
260 	 * name
261 	 */
262 	data_size = sizeof(*di) + name_len;
263 	leaf = path->nodes[0];
264 	slot = path->slots[0];
265 	if (data_size + btrfs_item_size_nr(leaf, slot) +
266 	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
267 		ret = -EOVERFLOW;
268 	} else {
269 		/* plenty of insertion room */
270 		ret = 0;
271 	}
272 out:
273 	btrfs_free_path(path);
274 	return ret;
275 }
276 
277 /*
278  * lookup a directory item based on index.  'dir' is the objectid
279  * we're searching in, and 'mod' tells us if you plan on deleting the
280  * item (use mod < 0) or changing the options (use mod > 0)
281  *
282  * The name is used to make sure the index really points to the name you were
283  * looking for.
284  */
285 struct btrfs_dir_item *
286 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
287 			    struct btrfs_root *root,
288 			    struct btrfs_path *path, u64 dir,
289 			    u64 objectid, const char *name, int name_len,
290 			    int mod)
291 {
292 	int ret;
293 	struct btrfs_key key;
294 	int ins_len = mod < 0 ? -1 : 0;
295 	int cow = mod != 0;
296 
297 	key.objectid = dir;
298 	key.type = BTRFS_DIR_INDEX_KEY;
299 	key.offset = objectid;
300 
301 	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
302 	if (ret < 0)
303 		return ERR_PTR(ret);
304 	if (ret > 0)
305 		return ERR_PTR(-ENOENT);
306 	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
307 }
308 
309 struct btrfs_dir_item *
310 btrfs_search_dir_index_item(struct btrfs_root *root,
311 			    struct btrfs_path *path, u64 dirid,
312 			    const char *name, int name_len)
313 {
314 	struct extent_buffer *leaf;
315 	struct btrfs_dir_item *di;
316 	struct btrfs_key key;
317 	u32 nritems;
318 	int ret;
319 
320 	key.objectid = dirid;
321 	key.type = BTRFS_DIR_INDEX_KEY;
322 	key.offset = 0;
323 
324 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
325 	if (ret < 0)
326 		return ERR_PTR(ret);
327 
328 	leaf = path->nodes[0];
329 	nritems = btrfs_header_nritems(leaf);
330 
331 	while (1) {
332 		if (path->slots[0] >= nritems) {
333 			ret = btrfs_next_leaf(root, path);
334 			if (ret < 0)
335 				return ERR_PTR(ret);
336 			if (ret > 0)
337 				break;
338 			leaf = path->nodes[0];
339 			nritems = btrfs_header_nritems(leaf);
340 			continue;
341 		}
342 
343 		btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
344 		if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
345 			break;
346 
347 		di = btrfs_match_dir_item_name(root->fs_info, path,
348 					       name, name_len);
349 		if (di)
350 			return di;
351 
352 		path->slots[0]++;
353 	}
354 	return NULL;
355 }
356 
357 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
358 					  struct btrfs_root *root,
359 					  struct btrfs_path *path, u64 dir,
360 					  const char *name, u16 name_len,
361 					  int mod)
362 {
363 	int ret;
364 	struct btrfs_key key;
365 	int ins_len = mod < 0 ? -1 : 0;
366 	int cow = mod != 0;
367 
368 	key.objectid = dir;
369 	key.type = BTRFS_XATTR_ITEM_KEY;
370 	key.offset = btrfs_name_hash(name, name_len);
371 	ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
372 	if (ret < 0)
373 		return ERR_PTR(ret);
374 	if (ret > 0)
375 		return NULL;
376 
377 	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
378 }
379 
380 /*
381  * helper function to look at the directory item pointed to by 'path'
382  * this walks through all the entries in a dir item and finds one
383  * for a specific name.
384  */
385 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
386 						 struct btrfs_path *path,
387 						 const char *name, int name_len)
388 {
389 	struct btrfs_dir_item *dir_item;
390 	unsigned long name_ptr;
391 	u32 total_len;
392 	u32 cur = 0;
393 	u32 this_len;
394 	struct extent_buffer *leaf;
395 
396 	leaf = path->nodes[0];
397 	dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
398 
399 	total_len = btrfs_item_size_nr(leaf, path->slots[0]);
400 	while (cur < total_len) {
401 		this_len = sizeof(*dir_item) +
402 			btrfs_dir_name_len(leaf, dir_item) +
403 			btrfs_dir_data_len(leaf, dir_item);
404 		name_ptr = (unsigned long)(dir_item + 1);
405 
406 		if (verify_dir_item(fs_info, leaf, path->slots[0], dir_item))
407 			return NULL;
408 		if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
409 		    memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
410 			return dir_item;
411 
412 		cur += this_len;
413 		dir_item = (struct btrfs_dir_item *)((char *)dir_item +
414 						     this_len);
415 	}
416 	return NULL;
417 }
418 
419 /*
420  * given a pointer into a directory item, delete it.  This
421  * handles items that have more than one entry in them.
422  */
423 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
424 			      struct btrfs_root *root,
425 			      struct btrfs_path *path,
426 			      struct btrfs_dir_item *di)
427 {
428 
429 	struct extent_buffer *leaf;
430 	u32 sub_item_len;
431 	u32 item_len;
432 	int ret = 0;
433 
434 	leaf = path->nodes[0];
435 	sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
436 		btrfs_dir_data_len(leaf, di);
437 	item_len = btrfs_item_size_nr(leaf, path->slots[0]);
438 	if (sub_item_len == item_len) {
439 		ret = btrfs_del_item(trans, root, path);
440 	} else {
441 		/* MARKER */
442 		unsigned long ptr = (unsigned long)di;
443 		unsigned long start;
444 
445 		start = btrfs_item_ptr_offset(leaf, path->slots[0]);
446 		memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
447 			item_len - (ptr + sub_item_len - start));
448 		btrfs_truncate_item(root->fs_info, path,
449 				    item_len - sub_item_len, 1);
450 	}
451 	return ret;
452 }
453 
454 int verify_dir_item(struct btrfs_fs_info *fs_info,
455 		    struct extent_buffer *leaf,
456 		    int slot,
457 		    struct btrfs_dir_item *dir_item)
458 {
459 	u16 namelen = BTRFS_NAME_LEN;
460 	int ret;
461 	u8 type = btrfs_dir_type(leaf, dir_item);
462 
463 	if (type >= BTRFS_FT_MAX) {
464 		btrfs_crit(fs_info, "invalid dir item type: %d", (int)type);
465 		return 1;
466 	}
467 
468 	if (type == BTRFS_FT_XATTR)
469 		namelen = XATTR_NAME_MAX;
470 
471 	if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
472 		btrfs_crit(fs_info, "invalid dir item name len: %u",
473 		       (unsigned)btrfs_dir_name_len(leaf, dir_item));
474 		return 1;
475 	}
476 
477 	namelen = btrfs_dir_name_len(leaf, dir_item);
478 	ret = btrfs_is_name_len_valid(leaf, slot,
479 				      (unsigned long)(dir_item + 1), namelen);
480 	if (!ret)
481 		return 1;
482 
483 	/* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
484 	if ((btrfs_dir_data_len(leaf, dir_item) +
485 	     btrfs_dir_name_len(leaf, dir_item)) >
486 					BTRFS_MAX_XATTR_SIZE(fs_info)) {
487 		btrfs_crit(fs_info, "invalid dir item name + data len: %u + %u",
488 			   (unsigned)btrfs_dir_name_len(leaf, dir_item),
489 			   (unsigned)btrfs_dir_data_len(leaf, dir_item));
490 		return 1;
491 	}
492 
493 	return 0;
494 }
495 
496 bool btrfs_is_name_len_valid(struct extent_buffer *leaf, int slot,
497 			     unsigned long start, u16 name_len)
498 {
499 	struct btrfs_fs_info *fs_info = leaf->fs_info;
500 	struct btrfs_key key;
501 	u32 read_start;
502 	u32 read_end;
503 	u32 item_start;
504 	u32 item_end;
505 	u32 size;
506 	bool ret = true;
507 
508 	ASSERT(start > BTRFS_LEAF_DATA_OFFSET);
509 
510 	read_start = start - BTRFS_LEAF_DATA_OFFSET;
511 	read_end = read_start + name_len;
512 	item_start = btrfs_item_offset_nr(leaf, slot);
513 	item_end = btrfs_item_end_nr(leaf, slot);
514 
515 	btrfs_item_key_to_cpu(leaf, &key, slot);
516 
517 	switch (key.type) {
518 	case BTRFS_DIR_ITEM_KEY:
519 	case BTRFS_XATTR_ITEM_KEY:
520 	case BTRFS_DIR_INDEX_KEY:
521 		size = sizeof(struct btrfs_dir_item);
522 		break;
523 	case BTRFS_INODE_REF_KEY:
524 		size = sizeof(struct btrfs_inode_ref);
525 		break;
526 	case BTRFS_INODE_EXTREF_KEY:
527 		size = sizeof(struct btrfs_inode_extref);
528 		break;
529 	case BTRFS_ROOT_REF_KEY:
530 	case BTRFS_ROOT_BACKREF_KEY:
531 		size = sizeof(struct btrfs_root_ref);
532 		break;
533 	default:
534 		ret = false;
535 		goto out;
536 	}
537 
538 	if (read_start < item_start) {
539 		ret = false;
540 		goto out;
541 	}
542 	if (read_end > item_end) {
543 		ret = false;
544 		goto out;
545 	}
546 
547 	/* there shall be item(s) before name */
548 	if (read_start - item_start < size) {
549 		ret = false;
550 		goto out;
551 	}
552 
553 out:
554 	if (!ret)
555 		btrfs_crit(fs_info, "invalid dir item name len: %u",
556 			   (unsigned int)name_len);
557 	return ret;
558 }
559