dir-item.c

  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, 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(-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
 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(dir);
124	key.type = BTRFS_DIR_ITEM_KEY;
125	key.offset = btrfs_name_hash(name->name, name->len);
126
127	path = btrfs_alloc_path();
128	if (!path)
129		return -ENOMEM;
130
131	btrfs_cpu_key_to_disk(&disk_key, location);
132
133	data_size = sizeof(*dir_item) + name->len;
134	dir_item = insert_with_overflow(trans, root, path, &key, data_size,
135					name->name, name->len);
136	if (IS_ERR(dir_item)) {
137		ret = PTR_ERR(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(leaf, dir_item, &disk_key);
148	btrfs_set_dir_flags(leaf, dir_item, type);
149	btrfs_set_dir_data_len(leaf, dir_item, 0);
150	btrfs_set_dir_name_len(leaf, dir_item, name->len);
151	btrfs_set_dir_transid(leaf, dir_item, trans->transid);
152	name_ptr = (unsigned long)(dir_item + 1);
153
154	write_extent_buffer(leaf, name->name, name_ptr, 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(path);
163
164	ret2 = btrfs_insert_delayed_dir_index(trans, name->name, name->len, dir,
165					      &disk_key, 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, path, ins_len, cow);
185	if (ret < 0)
186		return ERR_PTR(ret);
187	if (ret > 0)
188		return ERR_PTR(-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);
221
222	di = btrfs_lookup_match_dir(trans, root, path, &key, name->name,
223				    name->len, mod);
224	if (IS_ERR(di) && PTR_ERR(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);
248
249	di = btrfs_lookup_match_dir(NULL, root, path, &key, name->name,
250				    name->len, 0);
251	if (IS_ERR(di)) {
252		ret = PTR_ERR(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(leaf, slot) +
272	    sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(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, name->name,
312				    name->len, mod);
313	if (di == ERR_PTR(-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->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(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, name_len);
358
359	di = btrfs_lookup_match_dir(trans, root, path, &key, name, name_len, mod);
360	if (IS_ERR(di) && PTR_ERR(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(leaf, path->slots[0]);
385	while (cur < total_len) {
386		this_len = sizeof(*dir_item) +
387			btrfs_dir_name_len(leaf, dir_item) +
388			btrfs_dir_data_len(leaf, dir_item);
389		name_ptr = (unsigned long)(dir_item + 1);
390
391		if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
392		    memcmp_extent_buffer(leaf, name, name_ptr, 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(leaf, di) +
419		btrfs_dir_data_len(leaf, di);
420	item_len = btrfs_item_size(leaf, 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(leaf, ptr, ptr + sub_item_len,
430			item_len - (ptr + sub_item_len - start));
431		btrfs_truncate_item(trans, path, item_len - sub_item_len, 1);
432	}
433	return ret;
434}