1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2007 Oracle. All rights reserved.
4 */
5
6 #include "ctree.h"
7 #include "disk-io.h"
8 #include "transaction.h"
9 #include "print-tree.h"
10
btrfs_find_name_in_backref(struct extent_buffer * leaf,int slot,const char * name,int name_len)11 struct btrfs_inode_ref *btrfs_find_name_in_backref(struct extent_buffer *leaf,
12 int slot, const char *name,
13 int name_len)
14 {
15 struct btrfs_inode_ref *ref;
16 unsigned long ptr;
17 unsigned long name_ptr;
18 u32 item_size;
19 u32 cur_offset = 0;
20 int len;
21
22 item_size = btrfs_item_size_nr(leaf, slot);
23 ptr = btrfs_item_ptr_offset(leaf, slot);
24 while (cur_offset < item_size) {
25 ref = (struct btrfs_inode_ref *)(ptr + cur_offset);
26 len = btrfs_inode_ref_name_len(leaf, ref);
27 name_ptr = (unsigned long)(ref + 1);
28 cur_offset += len + sizeof(*ref);
29 if (len != name_len)
30 continue;
31 if (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0)
32 return ref;
33 }
34 return NULL;
35 }
36
btrfs_find_name_in_ext_backref(struct extent_buffer * leaf,int slot,u64 ref_objectid,const char * name,int name_len)37 struct btrfs_inode_extref *btrfs_find_name_in_ext_backref(
38 struct extent_buffer *leaf, int slot, u64 ref_objectid,
39 const char *name, int name_len)
40 {
41 struct btrfs_inode_extref *extref;
42 unsigned long ptr;
43 unsigned long name_ptr;
44 u32 item_size;
45 u32 cur_offset = 0;
46 int ref_name_len;
47
48 item_size = btrfs_item_size_nr(leaf, slot);
49 ptr = btrfs_item_ptr_offset(leaf, slot);
50
51 /*
52 * Search all extended backrefs in this item. We're only
53 * looking through any collisions so most of the time this is
54 * just going to compare against one buffer. If all is well,
55 * we'll return success and the inode ref object.
56 */
57 while (cur_offset < item_size) {
58 extref = (struct btrfs_inode_extref *) (ptr + cur_offset);
59 name_ptr = (unsigned long)(&extref->name);
60 ref_name_len = btrfs_inode_extref_name_len(leaf, extref);
61
62 if (ref_name_len == name_len &&
63 btrfs_inode_extref_parent(leaf, extref) == ref_objectid &&
64 (memcmp_extent_buffer(leaf, name, name_ptr, name_len) == 0))
65 return extref;
66
67 cur_offset += ref_name_len + sizeof(*extref);
68 }
69 return NULL;
70 }
71
72 /* Returns NULL if no extref found */
73 struct btrfs_inode_extref *
btrfs_lookup_inode_extref(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,const char * name,int name_len,u64 inode_objectid,u64 ref_objectid,int ins_len,int cow)74 btrfs_lookup_inode_extref(struct btrfs_trans_handle *trans,
75 struct btrfs_root *root,
76 struct btrfs_path *path,
77 const char *name, int name_len,
78 u64 inode_objectid, u64 ref_objectid, int ins_len,
79 int cow)
80 {
81 int ret;
82 struct btrfs_key key;
83
84 key.objectid = inode_objectid;
85 key.type = BTRFS_INODE_EXTREF_KEY;
86 key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
87
88 ret = btrfs_search_slot(trans, root, &key, path, ins_len, cow);
89 if (ret < 0)
90 return ERR_PTR(ret);
91 if (ret > 0)
92 return NULL;
93 return btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
94 ref_objectid, name, name_len);
95
96 }
97
btrfs_del_inode_extref(struct btrfs_trans_handle * trans,struct btrfs_root * root,const char * name,int name_len,u64 inode_objectid,u64 ref_objectid,u64 * index)98 static int btrfs_del_inode_extref(struct btrfs_trans_handle *trans,
99 struct btrfs_root *root,
100 const char *name, int name_len,
101 u64 inode_objectid, u64 ref_objectid,
102 u64 *index)
103 {
104 struct btrfs_path *path;
105 struct btrfs_key key;
106 struct btrfs_inode_extref *extref;
107 struct extent_buffer *leaf;
108 int ret;
109 int del_len = name_len + sizeof(*extref);
110 unsigned long ptr;
111 unsigned long item_start;
112 u32 item_size;
113
114 key.objectid = inode_objectid;
115 key.type = BTRFS_INODE_EXTREF_KEY;
116 key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
117
118 path = btrfs_alloc_path();
119 if (!path)
120 return -ENOMEM;
121
122 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
123 if (ret > 0)
124 ret = -ENOENT;
125 if (ret < 0)
126 goto out;
127
128 /*
129 * Sanity check - did we find the right item for this name?
130 * This should always succeed so error here will make the FS
131 * readonly.
132 */
133 extref = btrfs_find_name_in_ext_backref(path->nodes[0], path->slots[0],
134 ref_objectid, name, name_len);
135 if (!extref) {
136 btrfs_handle_fs_error(root->fs_info, -ENOENT, NULL);
137 ret = -EROFS;
138 goto out;
139 }
140
141 leaf = path->nodes[0];
142 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
143 if (index)
144 *index = btrfs_inode_extref_index(leaf, extref);
145
146 if (del_len == item_size) {
147 /*
148 * Common case only one ref in the item, remove the
149 * whole item.
150 */
151 ret = btrfs_del_item(trans, root, path);
152 goto out;
153 }
154
155 ptr = (unsigned long)extref;
156 item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
157
158 memmove_extent_buffer(leaf, ptr, ptr + del_len,
159 item_size - (ptr + del_len - item_start));
160
161 btrfs_truncate_item(path, item_size - del_len, 1);
162
163 out:
164 btrfs_free_path(path);
165
166 return ret;
167 }
168
btrfs_del_inode_ref(struct btrfs_trans_handle * trans,struct btrfs_root * root,const char * name,int name_len,u64 inode_objectid,u64 ref_objectid,u64 * index)169 int btrfs_del_inode_ref(struct btrfs_trans_handle *trans,
170 struct btrfs_root *root,
171 const char *name, int name_len,
172 u64 inode_objectid, u64 ref_objectid, u64 *index)
173 {
174 struct btrfs_path *path;
175 struct btrfs_key key;
176 struct btrfs_inode_ref *ref;
177 struct extent_buffer *leaf;
178 unsigned long ptr;
179 unsigned long item_start;
180 u32 item_size;
181 u32 sub_item_len;
182 int ret;
183 int search_ext_refs = 0;
184 int del_len = name_len + sizeof(*ref);
185
186 key.objectid = inode_objectid;
187 key.offset = ref_objectid;
188 key.type = BTRFS_INODE_REF_KEY;
189
190 path = btrfs_alloc_path();
191 if (!path)
192 return -ENOMEM;
193
194 ret = btrfs_search_slot(trans, root, &key, path, -1, 1);
195 if (ret > 0) {
196 ret = -ENOENT;
197 search_ext_refs = 1;
198 goto out;
199 } else if (ret < 0) {
200 goto out;
201 }
202
203 ref = btrfs_find_name_in_backref(path->nodes[0], path->slots[0], name,
204 name_len);
205 if (!ref) {
206 ret = -ENOENT;
207 search_ext_refs = 1;
208 goto out;
209 }
210 leaf = path->nodes[0];
211 item_size = btrfs_item_size_nr(leaf, path->slots[0]);
212
213 if (index)
214 *index = btrfs_inode_ref_index(leaf, ref);
215
216 if (del_len == item_size) {
217 ret = btrfs_del_item(trans, root, path);
218 goto out;
219 }
220 ptr = (unsigned long)ref;
221 sub_item_len = name_len + sizeof(*ref);
222 item_start = btrfs_item_ptr_offset(leaf, path->slots[0]);
223 memmove_extent_buffer(leaf, ptr, ptr + sub_item_len,
224 item_size - (ptr + sub_item_len - item_start));
225 btrfs_truncate_item(path, item_size - sub_item_len, 1);
226 out:
227 btrfs_free_path(path);
228
229 if (search_ext_refs) {
230 /*
231 * No refs were found, or we could not find the
232 * name in our ref array. Find and remove the extended
233 * inode ref then.
234 */
235 return btrfs_del_inode_extref(trans, root, name, name_len,
236 inode_objectid, ref_objectid, index);
237 }
238
239 return ret;
240 }
241
242 /*
243 * btrfs_insert_inode_extref() - Inserts an extended inode ref into a tree.
244 *
245 * The caller must have checked against BTRFS_LINK_MAX already.
246 */
btrfs_insert_inode_extref(struct btrfs_trans_handle * trans,struct btrfs_root * root,const char * name,int name_len,u64 inode_objectid,u64 ref_objectid,u64 index)247 static int btrfs_insert_inode_extref(struct btrfs_trans_handle *trans,
248 struct btrfs_root *root,
249 const char *name, int name_len,
250 u64 inode_objectid, u64 ref_objectid, u64 index)
251 {
252 struct btrfs_inode_extref *extref;
253 int ret;
254 int ins_len = name_len + sizeof(*extref);
255 unsigned long ptr;
256 struct btrfs_path *path;
257 struct btrfs_key key;
258 struct extent_buffer *leaf;
259 struct btrfs_item *item;
260
261 key.objectid = inode_objectid;
262 key.type = BTRFS_INODE_EXTREF_KEY;
263 key.offset = btrfs_extref_hash(ref_objectid, name, name_len);
264
265 path = btrfs_alloc_path();
266 if (!path)
267 return -ENOMEM;
268
269 ret = btrfs_insert_empty_item(trans, root, path, &key,
270 ins_len);
271 if (ret == -EEXIST) {
272 if (btrfs_find_name_in_ext_backref(path->nodes[0],
273 path->slots[0],
274 ref_objectid,
275 name, name_len))
276 goto out;
277
278 btrfs_extend_item(path, ins_len);
279 ret = 0;
280 }
281 if (ret < 0)
282 goto out;
283
284 leaf = path->nodes[0];
285 item = btrfs_item_nr(path->slots[0]);
286 ptr = (unsigned long)btrfs_item_ptr(leaf, path->slots[0], char);
287 ptr += btrfs_item_size(leaf, item) - ins_len;
288 extref = (struct btrfs_inode_extref *)ptr;
289
290 btrfs_set_inode_extref_name_len(path->nodes[0], extref, name_len);
291 btrfs_set_inode_extref_index(path->nodes[0], extref, index);
292 btrfs_set_inode_extref_parent(path->nodes[0], extref, ref_objectid);
293
294 ptr = (unsigned long)&extref->name;
295 write_extent_buffer(path->nodes[0], name, ptr, name_len);
296 btrfs_mark_buffer_dirty(path->nodes[0]);
297
298 out:
299 btrfs_free_path(path);
300 return ret;
301 }
302
303 /* Will return 0, -ENOMEM, -EMLINK, or -EEXIST or anything from the CoW path */
btrfs_insert_inode_ref(struct btrfs_trans_handle * trans,struct btrfs_root * root,const char * name,int name_len,u64 inode_objectid,u64 ref_objectid,u64 index)304 int btrfs_insert_inode_ref(struct btrfs_trans_handle *trans,
305 struct btrfs_root *root,
306 const char *name, int name_len,
307 u64 inode_objectid, u64 ref_objectid, u64 index)
308 {
309 struct btrfs_fs_info *fs_info = root->fs_info;
310 struct btrfs_path *path;
311 struct btrfs_key key;
312 struct btrfs_inode_ref *ref;
313 unsigned long ptr;
314 int ret;
315 int ins_len = name_len + sizeof(*ref);
316
317 key.objectid = inode_objectid;
318 key.offset = ref_objectid;
319 key.type = BTRFS_INODE_REF_KEY;
320
321 path = btrfs_alloc_path();
322 if (!path)
323 return -ENOMEM;
324
325 path->skip_release_on_error = 1;
326 ret = btrfs_insert_empty_item(trans, root, path, &key,
327 ins_len);
328 if (ret == -EEXIST) {
329 u32 old_size;
330 ref = btrfs_find_name_in_backref(path->nodes[0], path->slots[0],
331 name, name_len);
332 if (ref)
333 goto out;
334
335 old_size = btrfs_item_size_nr(path->nodes[0], path->slots[0]);
336 btrfs_extend_item(path, ins_len);
337 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
338 struct btrfs_inode_ref);
339 ref = (struct btrfs_inode_ref *)((unsigned long)ref + old_size);
340 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
341 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
342 ptr = (unsigned long)(ref + 1);
343 ret = 0;
344 } else if (ret < 0) {
345 if (ret == -EOVERFLOW) {
346 if (btrfs_find_name_in_backref(path->nodes[0],
347 path->slots[0],
348 name, name_len))
349 ret = -EEXIST;
350 else
351 ret = -EMLINK;
352 }
353 goto out;
354 } else {
355 ref = btrfs_item_ptr(path->nodes[0], path->slots[0],
356 struct btrfs_inode_ref);
357 btrfs_set_inode_ref_name_len(path->nodes[0], ref, name_len);
358 btrfs_set_inode_ref_index(path->nodes[0], ref, index);
359 ptr = (unsigned long)(ref + 1);
360 }
361 write_extent_buffer(path->nodes[0], name, ptr, name_len);
362 btrfs_mark_buffer_dirty(path->nodes[0]);
363
364 out:
365 btrfs_free_path(path);
366
367 if (ret == -EMLINK) {
368 struct btrfs_super_block *disk_super = fs_info->super_copy;
369 /* We ran out of space in the ref array. Need to
370 * add an extended ref. */
371 if (btrfs_super_incompat_flags(disk_super)
372 & BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
373 ret = btrfs_insert_inode_extref(trans, root, name,
374 name_len,
375 inode_objectid,
376 ref_objectid, index);
377 }
378
379 return ret;
380 }
381
btrfs_insert_empty_inode(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,u64 objectid)382 int btrfs_insert_empty_inode(struct btrfs_trans_handle *trans,
383 struct btrfs_root *root,
384 struct btrfs_path *path, u64 objectid)
385 {
386 struct btrfs_key key;
387 int ret;
388 key.objectid = objectid;
389 key.type = BTRFS_INODE_ITEM_KEY;
390 key.offset = 0;
391
392 ret = btrfs_insert_empty_item(trans, root, path, &key,
393 sizeof(struct btrfs_inode_item));
394 return ret;
395 }
396
btrfs_lookup_inode(struct btrfs_trans_handle * trans,struct btrfs_root * root,struct btrfs_path * path,struct btrfs_key * location,int mod)397 int btrfs_lookup_inode(struct btrfs_trans_handle *trans, struct btrfs_root
398 *root, struct btrfs_path *path,
399 struct btrfs_key *location, int mod)
400 {
401 int ins_len = mod < 0 ? -1 : 0;
402 int cow = mod != 0;
403 int ret;
404 int slot;
405 struct extent_buffer *leaf;
406 struct btrfs_key found_key;
407
408 ret = btrfs_search_slot(trans, root, location, path, ins_len, cow);
409 if (ret > 0 && location->type == BTRFS_ROOT_ITEM_KEY &&
410 location->offset == (u64)-1 && path->slots[0] != 0) {
411 slot = path->slots[0] - 1;
412 leaf = path->nodes[0];
413 btrfs_item_key_to_cpu(leaf, &found_key, slot);
414 if (found_key.objectid == location->objectid &&
415 found_key.type == location->type) {
416 path->slots[0]--;
417 return 0;
418 }
419 }
420 return ret;
421 }
422