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

source code of linux/fs/btrfs/dir-item.c