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 */
21 static struct btrfs_dir_item *insert_with_overflow(struct btrfs_trans_handle
22 *trans,
23 struct btrfs_root *root,
24 struct btrfs_path *path,
25 const 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 */
56 int 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 */
109 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans,
110 const struct fscrypt_str *name, struct btrfs_inode *dir,
111 const 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
158 second_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);
168 out_free:
169 btrfs_free_path(path);
170 if (ret)
171 return ret;
172 if (ret2)
173 return ret2;
174 return 0;
175 }
176
177 static 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 */
212 struct 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
233 int 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 }
284 out:
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 */
307 struct btrfs_dir_item *
308 btrfs_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
328 struct btrfs_dir_item *
329 btrfs_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
356 struct 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 */
381 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_fs_info *fs_info,
382 const 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 */
417 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
418 struct btrfs_root *root,
419 struct btrfs_path *path,
420 const 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
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