1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/fs.h>
4 #include <linux/types.h>
5 #include "ctree.h"
6 #include "disk-io.h"
7 #include "btrfs_inode.h"
8 #include "print-tree.h"
9 #include "export.h"
10 #include "accessors.h"
11 #include "super.h"
12
13 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
14 parent_objectid) / 4)
15 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
16 parent_root_objectid) / 4)
17 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
18
btrfs_encode_fh(struct inode * inode,u32 * fh,int * max_len,struct inode * parent)19 static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
20 struct inode *parent)
21 {
22 struct btrfs_fid *fid = (struct btrfs_fid *)fh;
23 int len = *max_len;
24 int type;
25
26 if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
27 *max_len = BTRFS_FID_SIZE_CONNECTABLE;
28 return FILEID_INVALID;
29 } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
30 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
31 return FILEID_INVALID;
32 }
33
34 len = BTRFS_FID_SIZE_NON_CONNECTABLE;
35 type = FILEID_BTRFS_WITHOUT_PARENT;
36
37 fid->objectid = btrfs_ino(BTRFS_I(inode));
38 fid->root_objectid = BTRFS_I(inode)->root->root_key.objectid;
39 fid->gen = inode->i_generation;
40
41 if (parent) {
42 u64 parent_root_id;
43
44 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
45 fid->parent_gen = parent->i_generation;
46 parent_root_id = BTRFS_I(parent)->root->root_key.objectid;
47
48 if (parent_root_id != fid->root_objectid) {
49 fid->parent_root_objectid = parent_root_id;
50 len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
51 type = FILEID_BTRFS_WITH_PARENT_ROOT;
52 } else {
53 len = BTRFS_FID_SIZE_CONNECTABLE;
54 type = FILEID_BTRFS_WITH_PARENT;
55 }
56 }
57
58 *max_len = len;
59 return type;
60 }
61
62 /*
63 * Read dentry of inode with @objectid from filesystem root @root_objectid.
64 *
65 * @sb: the filesystem super block
66 * @objectid: inode objectid
67 * @root_objectid: object id of the subvolume root where to look up the inode
68 * @generation: optional, if not zero, verify that the found inode
69 * generation matches
70 *
71 * Return dentry alias for the inode, otherwise an error. In case the
72 * generation does not match return ESTALE.
73 */
btrfs_get_dentry(struct super_block * sb,u64 objectid,u64 root_objectid,u64 generation)74 struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
75 u64 root_objectid, u64 generation)
76 {
77 struct btrfs_fs_info *fs_info = btrfs_sb(sb);
78 struct btrfs_root *root;
79 struct inode *inode;
80
81 if (objectid < BTRFS_FIRST_FREE_OBJECTID)
82 return ERR_PTR(-ESTALE);
83
84 root = btrfs_get_fs_root(fs_info, root_objectid, true);
85 if (IS_ERR(root))
86 return ERR_CAST(root);
87
88 inode = btrfs_iget(sb, objectid, root);
89 btrfs_put_root(root);
90 if (IS_ERR(inode))
91 return ERR_CAST(inode);
92
93 if (generation != 0 && generation != inode->i_generation) {
94 iput(inode);
95 return ERR_PTR(-ESTALE);
96 }
97
98 return d_obtain_alias(inode);
99 }
100
btrfs_fh_to_parent(struct super_block * sb,struct fid * fh,int fh_len,int fh_type)101 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
102 int fh_len, int fh_type)
103 {
104 struct btrfs_fid *fid = (struct btrfs_fid *) fh;
105 u64 objectid, root_objectid;
106 u32 generation;
107
108 if (fh_type == FILEID_BTRFS_WITH_PARENT) {
109 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE)
110 return NULL;
111 root_objectid = fid->root_objectid;
112 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
113 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
114 return NULL;
115 root_objectid = fid->parent_root_objectid;
116 } else
117 return NULL;
118
119 objectid = fid->parent_objectid;
120 generation = fid->parent_gen;
121
122 return btrfs_get_dentry(sb, objectid, root_objectid, generation);
123 }
124
btrfs_fh_to_dentry(struct super_block * sb,struct fid * fh,int fh_len,int fh_type)125 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
126 int fh_len, int fh_type)
127 {
128 struct btrfs_fid *fid = (struct btrfs_fid *) fh;
129 u64 objectid, root_objectid;
130 u32 generation;
131
132 if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
133 fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
134 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
135 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
136 (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
137 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
138 return NULL;
139
140 objectid = fid->objectid;
141 root_objectid = fid->root_objectid;
142 generation = fid->gen;
143
144 return btrfs_get_dentry(sb, objectid, root_objectid, generation);
145 }
146
btrfs_get_parent(struct dentry * child)147 struct dentry *btrfs_get_parent(struct dentry *child)
148 {
149 struct inode *dir = d_inode(child);
150 struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
151 struct btrfs_root *root = BTRFS_I(dir)->root;
152 struct btrfs_path *path;
153 struct extent_buffer *leaf;
154 struct btrfs_root_ref *ref;
155 struct btrfs_key key;
156 struct btrfs_key found_key;
157 int ret;
158
159 path = btrfs_alloc_path();
160 if (!path)
161 return ERR_PTR(-ENOMEM);
162
163 if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
164 key.objectid = root->root_key.objectid;
165 key.type = BTRFS_ROOT_BACKREF_KEY;
166 key.offset = (u64)-1;
167 root = fs_info->tree_root;
168 } else {
169 key.objectid = btrfs_ino(BTRFS_I(dir));
170 key.type = BTRFS_INODE_REF_KEY;
171 key.offset = (u64)-1;
172 }
173
174 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
175 if (ret < 0)
176 goto fail;
177 if (ret == 0) {
178 /*
179 * Key with offset of -1 found, there would have to exist an
180 * inode with such number or a root with such id.
181 */
182 ret = -EUCLEAN;
183 goto fail;
184 }
185
186 if (path->slots[0] == 0) {
187 ret = -ENOENT;
188 goto fail;
189 }
190
191 path->slots[0]--;
192 leaf = path->nodes[0];
193
194 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
195 if (found_key.objectid != key.objectid || found_key.type != key.type) {
196 ret = -ENOENT;
197 goto fail;
198 }
199
200 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
201 ref = btrfs_item_ptr(leaf, path->slots[0],
202 struct btrfs_root_ref);
203 key.objectid = btrfs_root_ref_dirid(leaf, ref);
204 } else {
205 key.objectid = found_key.offset;
206 }
207 btrfs_free_path(path);
208
209 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
210 return btrfs_get_dentry(fs_info->sb, key.objectid,
211 found_key.offset, 0);
212 }
213
214 return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root));
215 fail:
216 btrfs_free_path(path);
217 return ERR_PTR(ret);
218 }
219
btrfs_get_name(struct dentry * parent,char * name,struct dentry * child)220 static int btrfs_get_name(struct dentry *parent, char *name,
221 struct dentry *child)
222 {
223 struct inode *inode = d_inode(child);
224 struct inode *dir = d_inode(parent);
225 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
226 struct btrfs_path *path;
227 struct btrfs_root *root = BTRFS_I(dir)->root;
228 struct btrfs_inode_ref *iref;
229 struct btrfs_root_ref *rref;
230 struct extent_buffer *leaf;
231 unsigned long name_ptr;
232 struct btrfs_key key;
233 int name_len;
234 int ret;
235 u64 ino;
236
237 if (!S_ISDIR(dir->i_mode))
238 return -EINVAL;
239
240 ino = btrfs_ino(BTRFS_I(inode));
241
242 path = btrfs_alloc_path();
243 if (!path)
244 return -ENOMEM;
245
246 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
247 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
248 key.type = BTRFS_ROOT_BACKREF_KEY;
249 key.offset = (u64)-1;
250 root = fs_info->tree_root;
251 } else {
252 key.objectid = ino;
253 key.offset = btrfs_ino(BTRFS_I(dir));
254 key.type = BTRFS_INODE_REF_KEY;
255 }
256
257 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
258 if (ret < 0) {
259 btrfs_free_path(path);
260 return ret;
261 } else if (ret > 0) {
262 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
263 path->slots[0]--;
264 } else {
265 btrfs_free_path(path);
266 return -ENOENT;
267 }
268 }
269 leaf = path->nodes[0];
270
271 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
272 rref = btrfs_item_ptr(leaf, path->slots[0],
273 struct btrfs_root_ref);
274 name_ptr = (unsigned long)(rref + 1);
275 name_len = btrfs_root_ref_name_len(leaf, rref);
276 } else {
277 iref = btrfs_item_ptr(leaf, path->slots[0],
278 struct btrfs_inode_ref);
279 name_ptr = (unsigned long)(iref + 1);
280 name_len = btrfs_inode_ref_name_len(leaf, iref);
281 }
282
283 read_extent_buffer(leaf, name, name_ptr, name_len);
284 btrfs_free_path(path);
285
286 /*
287 * have to add the null termination to make sure that reconnect_path
288 * gets the right len for strlen
289 */
290 name[name_len] = '\0';
291
292 return 0;
293 }
294
295 const struct export_operations btrfs_export_ops = {
296 .encode_fh = btrfs_encode_fh,
297 .fh_to_dentry = btrfs_fh_to_dentry,
298 .fh_to_parent = btrfs_fh_to_parent,
299 .get_parent = btrfs_get_parent,
300 .get_name = btrfs_get_name,
301 };
302