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dir-item.c
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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  int ret;
42  char *ptr;
43  struct btrfs_item *item;
44  struct extent_buffer *leaf;
45 
46  ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
47  if (ret == -EEXIST) {
48  struct btrfs_dir_item *di;
49  di = btrfs_match_dir_item_name(root, path, name, name_len);
50  if (di)
51  return ERR_PTR(-EEXIST);
52  btrfs_extend_item(trans, root, path, data_size);
53  } else if (ret < 0)
54  return ERR_PTR(ret);
55  WARN_ON(ret > 0);
56  leaf = path->nodes[0];
57  item = btrfs_item_nr(leaf, path->slots[0]);
58  ptr = btrfs_item_ptr(leaf, path->slots[0], char);
59  BUG_ON(data_size > btrfs_item_size(leaf, item));
60  ptr += btrfs_item_size(leaf, item) - data_size;
61  return (struct btrfs_dir_item *)ptr;
62 }
63 
64 /*
65  * xattrs work a lot like directories, this inserts an xattr item
66  * into the tree
67  */
69  struct btrfs_root *root,
70  struct btrfs_path *path, u64 objectid,
71  const char *name, u16 name_len,
72  const void *data, u16 data_len)
73 {
74  int ret = 0;
75  struct btrfs_dir_item *dir_item;
76  unsigned long name_ptr, data_ptr;
77  struct btrfs_key key, location;
78  struct btrfs_disk_key disk_key;
79  struct extent_buffer *leaf;
80  u32 data_size;
81 
82  BUG_ON(name_len + data_len > BTRFS_MAX_XATTR_SIZE(root));
83 
84  key.objectid = objectid;
85  btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
86  key.offset = btrfs_name_hash(name, name_len);
87 
88  data_size = sizeof(*dir_item) + name_len + data_len;
89  dir_item = insert_with_overflow(trans, root, path, &key, data_size,
90  name, name_len);
91  if (IS_ERR(dir_item))
92  return PTR_ERR(dir_item);
93  memset(&location, 0, sizeof(location));
94 
95  leaf = path->nodes[0];
96  btrfs_cpu_key_to_disk(&disk_key, &location);
97  btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
98  btrfs_set_dir_type(leaf, dir_item, BTRFS_FT_XATTR);
99  btrfs_set_dir_name_len(leaf, dir_item, name_len);
100  btrfs_set_dir_transid(leaf, dir_item, trans->transid);
101  btrfs_set_dir_data_len(leaf, dir_item, data_len);
102  name_ptr = (unsigned long)(dir_item + 1);
103  data_ptr = (unsigned long)((char *)name_ptr + name_len);
104 
105  write_extent_buffer(leaf, name, name_ptr, name_len);
106  write_extent_buffer(leaf, data, data_ptr, data_len);
107  btrfs_mark_buffer_dirty(path->nodes[0]);
108 
109  return ret;
110 }
111 
112 /*
113  * insert a directory item in the tree, doing all the magic for
114  * both indexes. 'dir' indicates which objectid to insert it into,
115  * 'location' is the key to stuff into the directory item, 'type' is the
116  * type of the inode we're pointing to, and 'index' is the sequence number
117  * to use for the second index (if one is created).
118  * Will return 0 or -ENOMEM
119  */
121  *root, const char *name, int name_len,
122  struct inode *dir, struct btrfs_key *location,
123  u8 type, u64 index)
124 {
125  int ret = 0;
126  int ret2 = 0;
127  struct btrfs_path *path;
128  struct btrfs_dir_item *dir_item;
129  struct extent_buffer *leaf;
130  unsigned long name_ptr;
131  struct btrfs_key key;
132  struct btrfs_disk_key disk_key;
133  u32 data_size;
134 
135  key.objectid = btrfs_ino(dir);
136  btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
137  key.offset = btrfs_name_hash(name, name_len);
138 
139  path = btrfs_alloc_path();
140  if (!path)
141  return -ENOMEM;
142  path->leave_spinning = 1;
143 
144  btrfs_cpu_key_to_disk(&disk_key, location);
145 
146  data_size = sizeof(*dir_item) + name_len;
147  dir_item = insert_with_overflow(trans, root, path, &key, data_size,
148  name, name_len);
149  if (IS_ERR(dir_item)) {
150  ret = PTR_ERR(dir_item);
151  if (ret == -EEXIST)
152  goto second_insert;
153  goto out_free;
154  }
155 
156  leaf = path->nodes[0];
157  btrfs_set_dir_item_key(leaf, dir_item, &disk_key);
158  btrfs_set_dir_type(leaf, dir_item, type);
159  btrfs_set_dir_data_len(leaf, dir_item, 0);
160  btrfs_set_dir_name_len(leaf, dir_item, name_len);
161  btrfs_set_dir_transid(leaf, dir_item, trans->transid);
162  name_ptr = (unsigned long)(dir_item + 1);
163 
164  write_extent_buffer(leaf, name, name_ptr, name_len);
166 
167 second_insert:
168  /* FIXME, use some real flag for selecting the extra index */
169  if (root == root->fs_info->tree_root) {
170  ret = 0;
171  goto out_free;
172  }
173  btrfs_release_path(path);
174 
175  ret2 = btrfs_insert_delayed_dir_index(trans, root, name, name_len, dir,
176  &disk_key, type, index);
177 out_free:
178  btrfs_free_path(path);
179  if (ret)
180  return ret;
181  if (ret2)
182  return ret2;
183  return 0;
184 }
185 
186 /*
187  * lookup a directory item based on name. 'dir' is the objectid
188  * we're searching in, and 'mod' tells us if you plan on deleting the
189  * item (use mod < 0) or changing the options (use mod > 0)
190  */
192  struct btrfs_root *root,
193  struct btrfs_path *path, u64 dir,
194  const char *name, int name_len,
195  int mod)
196 {
197  int ret;
198  struct btrfs_key key;
199  int ins_len = mod < 0 ? -1 : 0;
200  int cow = mod != 0;
201 
202  key.objectid = dir;
203  btrfs_set_key_type(&key, BTRFS_DIR_ITEM_KEY);
204 
205  key.offset = btrfs_name_hash(name, name_len);
206 
207  ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
208  if (ret < 0)
209  return ERR_PTR(ret);
210  if (ret > 0)
211  return NULL;
212 
213  return btrfs_match_dir_item_name(root, path, name, name_len);
214 }
215 
216 /*
217  * lookup a directory item based on index. 'dir' is the objectid
218  * we're searching in, and 'mod' tells us if you plan on deleting the
219  * item (use mod < 0) or changing the options (use mod > 0)
220  *
221  * The name is used to make sure the index really points to the name you were
222  * looking for.
223  */
224 struct btrfs_dir_item *
226  struct btrfs_root *root,
227  struct btrfs_path *path, u64 dir,
228  u64 objectid, const char *name, int name_len,
229  int mod)
230 {
231  int ret;
232  struct btrfs_key key;
233  int ins_len = mod < 0 ? -1 : 0;
234  int cow = mod != 0;
235 
236  key.objectid = dir;
237  btrfs_set_key_type(&key, BTRFS_DIR_INDEX_KEY);
238  key.offset = objectid;
239 
240  ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
241  if (ret < 0)
242  return ERR_PTR(ret);
243  if (ret > 0)
244  return ERR_PTR(-ENOENT);
245  return btrfs_match_dir_item_name(root, path, name, name_len);
246 }
247 
248 struct btrfs_dir_item *
250  struct btrfs_path *path, u64 dirid,
251  const char *name, int name_len)
252 {
253  struct extent_buffer *leaf;
254  struct btrfs_dir_item *di;
255  struct btrfs_key key;
256  u32 nritems;
257  int ret;
258 
259  key.objectid = dirid;
261  key.offset = 0;
262 
263  ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
264  if (ret < 0)
265  return ERR_PTR(ret);
266 
267  leaf = path->nodes[0];
268  nritems = btrfs_header_nritems(leaf);
269 
270  while (1) {
271  if (path->slots[0] >= nritems) {
272  ret = btrfs_next_leaf(root, path);
273  if (ret < 0)
274  return ERR_PTR(ret);
275  if (ret > 0)
276  break;
277  leaf = path->nodes[0];
278  nritems = btrfs_header_nritems(leaf);
279  continue;
280  }
281 
282  btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
283  if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
284  break;
285 
286  di = btrfs_match_dir_item_name(root, path, name, name_len);
287  if (di)
288  return di;
289 
290  path->slots[0]++;
291  }
292  return NULL;
293 }
294 
296  struct btrfs_root *root,
297  struct btrfs_path *path, u64 dir,
298  const char *name, u16 name_len,
299  int mod)
300 {
301  int ret;
302  struct btrfs_key key;
303  int ins_len = mod < 0 ? -1 : 0;
304  int cow = mod != 0;
305 
306  key.objectid = dir;
307  btrfs_set_key_type(&key, BTRFS_XATTR_ITEM_KEY);
308  key.offset = btrfs_name_hash(name, name_len);
309  ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
310  if (ret < 0)
311  return ERR_PTR(ret);
312  if (ret > 0)
313  return NULL;
314 
315  return btrfs_match_dir_item_name(root, path, name, name_len);
316 }
317 
318 /*
319  * helper function to look at the directory item pointed to by 'path'
320  * this walks through all the entries in a dir item and finds one
321  * for a specific name.
322  */
324  struct btrfs_path *path,
325  const char *name, int name_len)
326 {
327  struct btrfs_dir_item *dir_item;
328  unsigned long name_ptr;
329  u32 total_len;
330  u32 cur = 0;
331  u32 this_len;
332  struct extent_buffer *leaf;
333 
334  leaf = path->nodes[0];
335  dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
336  if (verify_dir_item(root, leaf, dir_item))
337  return NULL;
338 
339  total_len = btrfs_item_size_nr(leaf, path->slots[0]);
340  while (cur < total_len) {
341  this_len = sizeof(*dir_item) +
342  btrfs_dir_name_len(leaf, dir_item) +
343  btrfs_dir_data_len(leaf, dir_item);
344  name_ptr = (unsigned long)(dir_item + 1);
345 
346  if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
347  memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
348  return dir_item;
349 
350  cur += this_len;
351  dir_item = (struct btrfs_dir_item *)((char *)dir_item +
352  this_len);
353  }
354  return NULL;
355 }
356 
357 /*
358  * given a pointer into a directory item, delete it. This
359  * handles items that have more than one entry in them.
360  */
362  struct btrfs_root *root,
363  struct btrfs_path *path,
364  struct btrfs_dir_item *di)
365 {
366 
367  struct extent_buffer *leaf;
368  u32 sub_item_len;
369  u32 item_len;
370  int ret = 0;
371 
372  leaf = path->nodes[0];
373  sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
374  btrfs_dir_data_len(leaf, di);
375  item_len = btrfs_item_size_nr(leaf, path->slots[0]);
376  if (sub_item_len == item_len) {
377  ret = btrfs_del_item(trans, root, path);
378  } else {
379  /* MARKER */
380  unsigned long ptr = (unsigned long)di;
381  unsigned long start;
382 
383  start = btrfs_item_ptr_offset(leaf, path->slots[0]);
384  memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
385  item_len - (ptr + sub_item_len - start));
386  btrfs_truncate_item(trans, root, path,
387  item_len - sub_item_len, 1);
388  }
389  return ret;
390 }
391 
392 int verify_dir_item(struct btrfs_root *root,
393  struct extent_buffer *leaf,
394  struct btrfs_dir_item *dir_item)
395 {
397  u8 type = btrfs_dir_type(leaf, dir_item);
398 
399  if (type >= BTRFS_FT_MAX) {
400  printk(KERN_CRIT "btrfs: invalid dir item type: %d\n",
401  (int)type);
402  return 1;
403  }
404 
405  if (type == BTRFS_FT_XATTR)
406  namelen = XATTR_NAME_MAX;
407 
408  if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
409  printk(KERN_CRIT "btrfs: invalid dir item name len: %u\n",
410  (unsigned)btrfs_dir_data_len(leaf, dir_item));
411  return 1;
412  }
413 
414  /* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
415  if (btrfs_dir_data_len(leaf, dir_item) > BTRFS_MAX_XATTR_SIZE(root)) {
416  printk(KERN_CRIT "btrfs: invalid dir item data len: %u\n",
417  (unsigned)btrfs_dir_data_len(leaf, dir_item));
418  return 1;
419  }
420 
421  return 0;
422 }