1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2007 Oracle.  All rights reserved.
4 */
5
6#include "messages.h"
7#include "ctree.h"
8#include "disk-io.h"
9#include "transaction.h"
10#include "accessors.h"
11#include "dir-item.h"
12
13/*
14 * insert a name into a directory, doing overflow properly if there is a hash
15 * collision.  data_size indicates how big the item inserted should be.  On
16 * success a struct btrfs_dir_item pointer is returned, otherwise it is
17 * an ERR_PTR.
18 *
19 * The name is not copied into the dir item, you have to do that yourself.
20 */
21static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
22						   *trans,
23						   struct btrfs_root *root,
24						   struct btrfs_path *path,
25						   struct btrfs_key *cpu_key,
26						   u32 data_size,
27						   const char *name,
28						   int name_len)
29{
30	struct btrfs_fs_info *fs_info = root->fs_info;
31	int ret;
32	char *ptr;
33	struct extent_buffer *leaf;
34
35	ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
36	if (ret == -EEXIST) {
37		struct btrfs_dir_item *di;
38		di = btrfs_match_dir_item_name(fs_info, path, name, name_len);
39		if (di)
40			return ERR_PTR(-EEXIST);
41		btrfs_extend_item(trans, path, data_size);
42	} else if (ret < 0)
43		return ERR_PTR(ret);
44	WARN_ON(ret > 0);
45	leaf = path->nodes[0];
46	ptr = btrfs_item_ptr(leaf, path->slots[0], char);
47	ASSERT(data_size <= btrfs_item_size(leaf, path->slots[0]));
48	ptr += btrfs_item_size(leaf, path->slots[0]) - data_size;
49	return (struct btrfs_dir_item *)ptr;
50}
51
52/*
53 * xattrs work a lot like directories, this inserts an xattr item
54 * into the tree
55 */
56int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
57			    struct btrfs_root *root,
58			    struct btrfs_path *path, u64 objectid,
59			    const char *name, u16 name_len,
60			    const void *data, u16 data_len)
61{
62	int ret = 0;
63	struct btrfs_dir_item *dir_item;
64	unsigned long name_ptr, data_ptr;
65	struct btrfs_key key, location;
66	struct btrfs_disk_key disk_key;
67	struct extent_buffer *leaf;
68	u32 data_size;
69
70	if (name_len + data_len > BTRFS_MAX_XATTR_SIZE(root->fs_info))
71		return -ENOSPC;
72
73	key.objectid = objectid;
74	key.type = BTRFS_XATTR_ITEM_KEY;
75	key.offset = btrfs_name_hash(name, name_len);
76
77	data_size = sizeof(*dir_item) + name_len + data_len;
78	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
79					name, name_len);
80	if (IS_ERR(dir_item))
81		return PTR_ERR(dir_item);
82	memset(&location, 0, sizeof(location));
83
84	leaf = path->nodes[0];
85	btrfs_cpu_key_to_disk(&disk_key, &location);
86	btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
87	btrfs_set_dir_flags(leaf, dir_item, BTRFS_FT_XATTR);
88	btrfs_set_dir_name_len(leaf, dir_item, name_len);
89	btrfs_set_dir_transid(leaf, dir_item, trans->transid);
90	btrfs_set_dir_data_len(leaf, dir_item, data_len);
91	name_ptr = (unsigned long)(dir_item + 1);
92	data_ptr = (unsigned long)((char *)name_ptr + name_len);
93
94	write_extent_buffer(leaf, name, name_ptr, name_len);
95	write_extent_buffer(leaf, data, data_ptr, data_len);
96	btrfs_mark_buffer_dirty(trans, path->nodes[0]);
97
98	return ret;
99}
100
101/*
102 * insert a directory item in the tree, doing all the magic for
103 * both indexes. 'dir' indicates which objectid to insert it into,
104 * 'location' is the key to stuff into the directory item, 'type' is the
105 * type of the inode we're pointing to, and 'index' is the sequence number
106 * to use for the second index (if one is created).
107 * Will return 0 or -ENOMEM
108 */
109int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,
110			  const struct fscrypt_str *name, struct btrfs_inode *dir,
111			  struct btrfs_key *location, u8 type, u64 index)
112{
113	int ret = 0;
114	int ret2 = 0;
115	struct btrfs_root *root = dir->root;
116	struct btrfs_path *path;
117	struct btrfs_dir_item *dir_item;
118	struct extent_buffer *leaf;
119	unsigned long name_ptr;
120	struct btrfs_key key;
121	struct btrfs_disk_key disk_key;
122	u32 data_size;
123
124	key.objectid = btrfs_ino(dir);
125	key.type = BTRFS_DIR_ITEM_KEY;
126	key.offset = btrfs_name_hash(name->name, name->len);
127
128	path = btrfs_alloc_path();
129	if (!path)
130		return -ENOMEM;
131
132	btrfs_cpu_key_to_disk(&disk_key, location);
133
134	data_size = sizeof(*dir_item) + name->len;
135	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
136					name->name, name->len);
137	if (IS_ERR(dir_item)) {
138		ret = PTR_ERR(dir_item);
139		if (ret == -EEXIST)
140			goto second_insert;
141		goto out_free;
142	}
143
144	if (IS_ENCRYPTED(&dir->vfs_inode))
145		type |= BTRFS_FT_ENCRYPTED;
146
147	leaf = path->nodes[0];
148	btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
149	btrfs_set_dir_flags(leaf, dir_item, type);
150	btrfs_set_dir_data_len(leaf, dir_item, 0);
151	btrfs_set_dir_name_len(leaf, dir_item, name->len);
152	btrfs_set_dir_transid(leaf, dir_item, trans->transid);
153	name_ptr = (unsigned long)(dir_item + 1);
154
155	write_extent_buffer(leaf, name->name, name_ptr, name->len);
156	btrfs_mark_buffer_dirty(trans, leaf);
157
158second_insert:
159	/* FIXME, use some real flag for selecting the extra index */
160	if (root == root->fs_info->tree_root) {
161		ret = 0;
162		goto out_free;
163	}
164	btrfs_release_path(path);
165
166	ret2 = btrfs_insert_delayed_dir_index(trans, name->name, name->len, dir,
167					      &disk_key, type, index);
168out_free:
169	btrfs_free_path(path);
170	if (ret)
171		return ret;
172	if (ret2)
173		return ret2;
174	return 0;
175}
176
177static struct btrfs_dir_item *btrfs_lookup_match_dir(
178			struct btrfs_trans_handle *trans,
179			struct btrfs_root *root, struct btrfs_path *path,
180			struct btrfs_key *key, const char *name,
181			int name_len, int mod)
182{
183	const int ins_len = (mod < 0 ? -1 : 0);
184	const int cow = (mod != 0);
185	int ret;
186
187	ret = btrfs_search_slot(trans, root, key, path, ins_len, cow);
188	if (ret < 0)
189		return ERR_PTR(ret);
190	if (ret > 0)
191		return ERR_PTR(-ENOENT);
192
193	return btrfs_match_dir_item_name(root->fs_info, path, name, name_len);
194}
195
196/*
197 * Lookup for a directory item by name.
198 *
199 * @trans:	The transaction handle to use. Can be NULL if @mod is 0.
200 * @root:	The root of the target tree.
201 * @path:	Path to use for the search.
202 * @dir:	The inode number (objectid) of the directory.
203 * @name:	The name associated to the directory entry we are looking for.
204 * @name_len:	The length of the name.
205 * @mod:	Used to indicate if the tree search is meant for a read only
206 *		lookup, for a modification lookup or for a deletion lookup, so
207 *		its value should be 0, 1 or -1, respectively.
208 *
209 * Returns: NULL if the dir item does not exists, an error pointer if an error
210 * happened, or a pointer to a dir item if a dir item exists for the given name.
211 */
212struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
213					     struct btrfs_root *root,
214					     struct btrfs_path *path, u64 dir,
215					     const struct fscrypt_str *name,
216					     int mod)
217{
218	struct btrfs_key key;
219	struct btrfs_dir_item *di;
220
221	key.objectid = dir;
222	key.type = BTRFS_DIR_ITEM_KEY;
223	key.offset = btrfs_name_hash(name->name, name->len);
224
225	di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
226				    name->len, mod);
227	if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
228		return NULL;
229
230	return di;
231}
232
233int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
234				   const struct fscrypt_str *name)
235{
236	int ret;
237	struct btrfs_key key;
238	struct btrfs_dir_item *di;
239	int data_size;
240	struct extent_buffer *leaf;
241	int slot;
242	struct btrfs_path *path;
243
244	path = btrfs_alloc_path();
245	if (!path)
246		return -ENOMEM;
247
248	key.objectid = dir;
249	key.type = BTRFS_DIR_ITEM_KEY;
250	key.offset = btrfs_name_hash(name->name, name->len);
251
252	di = btrfs_lookup_match_dir(NULL, root, path, &key, name->name,
253				    name->len, 0);
254	if (IS_ERR(di)) {
255		ret = PTR_ERR(di);
256		/* Nothing found, we're safe */
257		if (ret == -ENOENT) {
258			ret = 0;
259			goto out;
260		}
261
262		if (ret < 0)
263			goto out;
264	}
265
266	/* we found an item, look for our name in the item */
267	if (di) {
268		/* our exact name was found */
269		ret = -EEXIST;
270		goto out;
271	}
272
273	/* See if there is room in the item to insert this name. */
274	data_size = sizeof(*di) + name->len;
275	leaf = path->nodes[0];
276	slot = path->slots[0];
277	if (data_size + btrfs_item_size(leaf, slot) +
278	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root->fs_info)) {
279		ret = -EOVERFLOW;
280	} else {
281		/* plenty of insertion room */
282		ret = 0;
283	}
284out:
285	btrfs_free_path(path);
286	return ret;
287}
288
289/*
290 * Lookup for a directory index item by name and index number.
291 *
292 * @trans:	The transaction handle to use. Can be NULL if @mod is 0.
293 * @root:	The root of the target tree.
294 * @path:	Path to use for the search.
295 * @dir:	The inode number (objectid) of the directory.
296 * @index:	The index number.
297 * @name:	The name associated to the directory entry we are looking for.
298 * @name_len:	The length of the name.
299 * @mod:	Used to indicate if the tree search is meant for a read only
300 *		lookup, for a modification lookup or for a deletion lookup, so
301 *		its value should be 0, 1 or -1, respectively.
302 *
303 * Returns: NULL if the dir index item does not exists, an error pointer if an
304 * error happened, or a pointer to a dir item if the dir index item exists and
305 * matches the criteria (name and index number).
306 */
307struct btrfs_dir_item *
308btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
309			    struct btrfs_root *root,
310			    struct btrfs_path *path, u64 dir,
311			    u64 index, const struct fscrypt_str *name, int mod)
312{
313	struct btrfs_dir_item *di;
314	struct btrfs_key key;
315
316	key.objectid = dir;
317	key.type = BTRFS_DIR_INDEX_KEY;
318	key.offset = index;
319
320	di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
321				    name->len, mod);
322	if (di == ERR_PTR(-ENOENT))
323		return NULL;
324
325	return di;
326}
327
328struct btrfs_dir_item *
329btrfs_search_dir_index_item(struct btrfs_root *root, struct btrfs_path *path,
330			    u64 dirid, const struct fscrypt_str *name)
331{
332	struct btrfs_dir_item *di;
333	struct btrfs_key key;
334	int ret;
335
336	key.objectid = dirid;
337	key.type = BTRFS_DIR_INDEX_KEY;
338	key.offset = 0;
339
340	btrfs_for_each_slot(root, &key, &key, path, ret) {
341		if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
342			break;
343
344		di = btrfs_match_dir_item_name(root->fs_info, path,
345					       name->name, name->len);
346		if (di)
347			return di;
348	}
349	/* Adjust return code if the key was not found in the next leaf. */
350	if (ret > 0)
351		ret = 0;
352
353	return ERR_PTR(ret);
354}
355
356struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
357					  struct btrfs_root *root,
358					  struct btrfs_path *path, u64 dir,
359					  const char *name, u16 name_len,
360					  int mod)
361{
362	struct btrfs_key key;
363	struct btrfs_dir_item *di;
364
365	key.objectid = dir;
366	key.type = BTRFS_XATTR_ITEM_KEY;
367	key.offset = btrfs_name_hash(name, name_len);
368
369	di = btrfs_lookup_match_dir(trans, root, path, &key, name, name_len, mod);
370	if (IS_ERR(di) && PTR_ERR(di) == -ENOENT)
371		return NULL;
372
373	return di;
374}
375
376/*
377 * helper function to look at the directory item pointed to by 'path'
378 * this walks through all the entries in a dir item and finds one
379 * for a specific name.
380 */
381struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
382						 struct btrfs_path *path,
383						 const char *name, int name_len)
384{
385	struct btrfs_dir_item *dir_item;
386	unsigned long name_ptr;
387	u32 total_len;
388	u32 cur = 0;
389	u32 this_len;
390	struct extent_buffer *leaf;
391
392	leaf = path->nodes[0];
393	dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
394
395	total_len = btrfs_item_size(leaf, path->slots[0]);
396	while (cur < total_len) {
397		this_len = sizeof(*dir_item) +
398			btrfs_dir_name_len(leaf, dir_item) +
399			btrfs_dir_data_len(leaf, dir_item);
400		name_ptr = (unsigned long)(dir_item + 1);
401
402		if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
403		    memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
404			return dir_item;
405
406		cur += this_len;
407		dir_item = (struct btrfs_dir_item *)((char *)dir_item +
408						     this_len);
409	}
410	return NULL;
411}
412
413/*
414 * given a pointer into a directory item, delete it.  This
415 * handles items that have more than one entry in them.
416 */
417int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
418			      struct btrfs_root *root,
419			      struct btrfs_path *path,
420			      struct btrfs_dir_item *di)
421{
422
423	struct extent_buffer *leaf;
424	u32 sub_item_len;
425	u32 item_len;
426	int ret = 0;
427
428	leaf = path->nodes[0];
429	sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
430		btrfs_dir_data_len(leaf, di);
431	item_len = btrfs_item_size(leaf, path->slots[0]);
432	if (sub_item_len == item_len) {
433		ret = btrfs_del_item(trans, root, path);
434	} else {
435		/* MARKER */
436		unsigned long ptr = (unsigned long)di;
437		unsigned long start;
438
439		start = btrfs_item_ptr_offset(leaf, path->slots[0]);
440		memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
441			item_len - (ptr + sub_item_len - start));
442		btrfs_truncate_item(trans, path, item_len - sub_item_len, 1);
443	}
444	return ret;
445}
446