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TOMOYO Linux Cross Reference
Linux/fs/btrfs/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(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(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  */
 68 int btrfs_insert_xattr_item(struct btrfs_trans_handle *trans,
 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         key.type = 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  */
120 int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root
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         key.type = 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);
165         btrfs_mark_buffer_dirty(leaf);
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  */
191 struct btrfs_dir_item *btrfs_lookup_dir_item(struct btrfs_trans_handle *trans,
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         key.type = 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 int btrfs_check_dir_item_collision(struct btrfs_root *root, u64 dir,
217                                    const char *name, int name_len)
218 {
219         int ret;
220         struct btrfs_key key;
221         struct btrfs_dir_item *di;
222         int data_size;
223         struct extent_buffer *leaf;
224         int slot;
225         struct btrfs_path *path;
226 
227 
228         path = btrfs_alloc_path();
229         if (!path)
230                 return -ENOMEM;
231 
232         key.objectid = dir;
233         key.type = BTRFS_DIR_ITEM_KEY;
234         key.offset = btrfs_name_hash(name, name_len);
235 
236         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
237 
238         /* return back any errors */
239         if (ret < 0)
240                 goto out;
241 
242         /* nothing found, we're safe */
243         if (ret > 0) {
244                 ret = 0;
245                 goto out;
246         }
247 
248         /* we found an item, look for our name in the item */
249         di = btrfs_match_dir_item_name(root, path, name, name_len);
250         if (di) {
251                 /* our exact name was found */
252                 ret = -EEXIST;
253                 goto out;
254         }
255 
256         /*
257          * see if there is room in the item to insert this
258          * name
259          */
260         data_size = sizeof(*di) + name_len;
261         leaf = path->nodes[0];
262         slot = path->slots[0];
263         if (data_size + btrfs_item_size_nr(leaf, slot) +
264             sizeof(struct btrfs_item) > BTRFS_LEAF_DATA_SIZE(root)) {
265                 ret = -EOVERFLOW;
266         } else {
267                 /* plenty of insertion room */
268                 ret = 0;
269         }
270 out:
271         btrfs_free_path(path);
272         return ret;
273 }
274 
275 /*
276  * lookup a directory item based on index.  'dir' is the objectid
277  * we're searching in, and 'mod' tells us if you plan on deleting the
278  * item (use mod < 0) or changing the options (use mod > 0)
279  *
280  * The name is used to make sure the index really points to the name you were
281  * looking for.
282  */
283 struct btrfs_dir_item *
284 btrfs_lookup_dir_index_item(struct btrfs_trans_handle *trans,
285                             struct btrfs_root *root,
286                             struct btrfs_path *path, u64 dir,
287                             u64 objectid, const char *name, int name_len,
288                             int mod)
289 {
290         int ret;
291         struct btrfs_key key;
292         int ins_len = mod < 0 ? -1 : 0;
293         int cow = mod != 0;
294 
295         key.objectid = dir;
296         key.type = BTRFS_DIR_INDEX_KEY;
297         key.offset = objectid;
298 
299         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
300         if (ret < 0)
301                 return ERR_PTR(ret);
302         if (ret > 0)
303                 return ERR_PTR(-ENOENT);
304         return btrfs_match_dir_item_name(root, path, name, name_len);
305 }
306 
307 struct btrfs_dir_item *
308 btrfs_search_dir_index_item(struct btrfs_root *root,
309                             struct btrfs_path *path, u64 dirid,
310                             const char *name, int name_len)
311 {
312         struct extent_buffer *leaf;
313         struct btrfs_dir_item *di;
314         struct btrfs_key key;
315         u32 nritems;
316         int ret;
317 
318         key.objectid = dirid;
319         key.type = BTRFS_DIR_INDEX_KEY;
320         key.offset = 0;
321 
322         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
323         if (ret < 0)
324                 return ERR_PTR(ret);
325 
326         leaf = path->nodes[0];
327         nritems = btrfs_header_nritems(leaf);
328 
329         while (1) {
330                 if (path->slots[0] >= nritems) {
331                         ret = btrfs_next_leaf(root, path);
332                         if (ret < 0)
333                                 return ERR_PTR(ret);
334                         if (ret > 0)
335                                 break;
336                         leaf = path->nodes[0];
337                         nritems = btrfs_header_nritems(leaf);
338                         continue;
339                 }
340 
341                 btrfs_item_key_to_cpu(leaf, &key, path->slots[0]);
342                 if (key.objectid != dirid || key.type != BTRFS_DIR_INDEX_KEY)
343                         break;
344 
345                 di = btrfs_match_dir_item_name(root, path, name, name_len);
346                 if (di)
347                         return di;
348 
349                 path->slots[0]++;
350         }
351         return NULL;
352 }
353 
354 struct btrfs_dir_item *btrfs_lookup_xattr(struct btrfs_trans_handle *trans,
355                                           struct btrfs_root *root,
356                                           struct btrfs_path *path, u64 dir,
357                                           const char *name, u16 name_len,
358                                           int mod)
359 {
360         int ret;
361         struct btrfs_key key;
362         int ins_len = mod < 0 ? -1 : 0;
363         int cow = mod != 0;
364 
365         key.objectid = dir;
366         key.type = BTRFS_XATTR_ITEM_KEY;
367         key.offset = btrfs_name_hash(name, name_len);
368         ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
369         if (ret < 0)
370                 return ERR_PTR(ret);
371         if (ret > 0)
372                 return NULL;
373 
374         return btrfs_match_dir_item_name(root, path, name, name_len);
375 }
376 
377 /*
378  * helper function to look at the directory item pointed to by 'path'
379  * this walks through all the entries in a dir item and finds one
380  * for a specific name.
381  */
382 struct btrfs_dir_item *btrfs_match_dir_item_name(struct btrfs_root *root,
383                                                  struct btrfs_path *path,
384                                                  const char *name, int name_len)
385 {
386         struct btrfs_dir_item *dir_item;
387         unsigned long name_ptr;
388         u32 total_len;
389         u32 cur = 0;
390         u32 this_len;
391         struct extent_buffer *leaf;
392 
393         leaf = path->nodes[0];
394         dir_item = btrfs_item_ptr(leaf, path->slots[0], struct btrfs_dir_item);
395         if (verify_dir_item(root, leaf, dir_item))
396                 return NULL;
397 
398         total_len = btrfs_item_size_nr(leaf, path->slots[0]);
399         while (cur < total_len) {
400                 this_len = sizeof(*dir_item) +
401                         btrfs_dir_name_len(leaf, dir_item) +
402                         btrfs_dir_data_len(leaf, dir_item);
403                 name_ptr = (unsigned long)(dir_item + 1);
404 
405                 if (btrfs_dir_name_len(leaf, dir_item) == name_len &&
406                     memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
407                         return dir_item;
408 
409                 cur += this_len;
410                 dir_item = (struct btrfs_dir_item *)((char *)dir_item +
411                                                      this_len);
412         }
413         return NULL;
414 }
415 
416 /*
417  * given a pointer into a directory item, delete it.  This
418  * handles items that have more than one entry in them.
419  */
420 int btrfs_delete_one_dir_name(struct btrfs_trans_handle *trans,
421                               struct btrfs_root *root,
422                               struct btrfs_path *path,
423                               struct btrfs_dir_item *di)
424 {
425 
426         struct extent_buffer *leaf;
427         u32 sub_item_len;
428         u32 item_len;
429         int ret = 0;
430 
431         leaf = path->nodes[0];
432         sub_item_len = sizeof(*di) + btrfs_dir_name_len(leaf, di) +
433                 btrfs_dir_data_len(leaf, di);
434         item_len = btrfs_item_size_nr(leaf, path->slots[0]);
435         if (sub_item_len == item_len) {
436                 ret = btrfs_del_item(trans, root, path);
437         } else {
438                 /* MARKER */
439                 unsigned long ptr = (unsigned long)di;
440                 unsigned long start;
441 
442                 start = btrfs_item_ptr_offset(leaf, path->slots[0]);
443                 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
444                         item_len - (ptr + sub_item_len - start));
445                 btrfs_truncate_item(root, path, item_len - sub_item_len, 1);
446         }
447         return ret;
448 }
449 
450 int verify_dir_item(struct btrfs_root *root,
451                     struct extent_buffer *leaf,
452                     struct btrfs_dir_item *dir_item)
453 {
454         u16 namelen = BTRFS_NAME_LEN;
455         u8 type = btrfs_dir_type(leaf, dir_item);
456 
457         if (type >= BTRFS_FT_MAX) {
458                 btrfs_crit(root->fs_info, "invalid dir item type: %d",
459                        (int)type);
460                 return 1;
461         }
462 
463         if (type == BTRFS_FT_XATTR)
464                 namelen = XATTR_NAME_MAX;
465 
466         if (btrfs_dir_name_len(leaf, dir_item) > namelen) {
467                 btrfs_crit(root->fs_info, "invalid dir item name len: %u",
468                        (unsigned)btrfs_dir_data_len(leaf, dir_item));
469                 return 1;
470         }
471 
472         /* BTRFS_MAX_XATTR_SIZE is the same for all dir items */
473         if ((btrfs_dir_data_len(leaf, dir_item) +
474              btrfs_dir_name_len(leaf, dir_item)) > BTRFS_MAX_XATTR_SIZE(root)) {
475                 btrfs_crit(root->fs_info, "invalid dir item name + data len: %u + %u",
476                        (unsigned)btrfs_dir_name_len(leaf, dir_item),
477                        (unsigned)btrfs_dir_data_len(leaf, dir_item));
478                 return 1;
479         }
480 
481         return 0;
482 }
483 

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