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 "export.h"
9 #include "accessors.h"
10 #include "super.h"
11
12 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
13 parent_objectid) / 4)
14 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
15 parent_root_objectid) / 4)
16 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
17
btrfs_encode_fh(struct inode * inode,u32 * fh,int * max_len,struct inode * parent)18 static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
19 struct inode *parent)
20 {
21 struct btrfs_fid *fid = (struct btrfs_fid *)fh;
22 int len = *max_len;
23 int type;
24
25 if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
26 *max_len = BTRFS_FID_SIZE_CONNECTABLE;
27 return FILEID_INVALID;
28 } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
29 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
30 return FILEID_INVALID;
31 }
32
33 len = BTRFS_FID_SIZE_NON_CONNECTABLE;
34 type = FILEID_BTRFS_WITHOUT_PARENT;
35
36 fid->objectid = btrfs_ino(BTRFS_I(inode));
37 fid->root_objectid = btrfs_root_id(BTRFS_I(inode)->root);
38 fid->gen = inode->i_generation;
39
40 if (parent) {
41 u64 parent_root_id;
42
43 fid->parent_objectid = btrfs_ino(BTRFS_I(parent));
44 fid->parent_gen = parent->i_generation;
45 parent_root_id = btrfs_root_id(BTRFS_I(parent)->root);
46
47 if (parent_root_id != fid->root_objectid) {
48 fid->parent_root_objectid = parent_root_id;
49 len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
50 type = FILEID_BTRFS_WITH_PARENT_ROOT;
51 } else {
52 len = BTRFS_FID_SIZE_CONNECTABLE;
53 type = FILEID_BTRFS_WITH_PARENT;
54 }
55 }
56
57 *max_len = len;
58 return type;
59 }
60
61 /*
62 * Read dentry of inode with @objectid from filesystem root @root_objectid.
63 *
64 * @sb: the filesystem super block
65 * @objectid: inode objectid
66 * @root_objectid: object id of the subvolume root where to look up the inode
67 * @generation: optional, if not zero, verify that the found inode
68 * generation matches
69 *
70 * Return dentry alias for the inode, otherwise an error. In case the
71 * generation does not match return ESTALE.
72 */
btrfs_get_dentry(struct super_block * sb,u64 objectid,u64 root_objectid,u64 generation)73 struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
74 u64 root_objectid, u64 generation)
75 {
76 struct btrfs_fs_info *fs_info = btrfs_sb(sb);
77 struct btrfs_root *root;
78 struct btrfs_inode *inode;
79
80 if (objectid < BTRFS_FIRST_FREE_OBJECTID)
81 return ERR_PTR(-ESTALE);
82
83 root = btrfs_get_fs_root(fs_info, root_objectid, true);
84 if (IS_ERR(root))
85 return ERR_CAST(root);
86
87 inode = btrfs_iget(objectid, root);
88 btrfs_put_root(root);
89 if (IS_ERR(inode))
90 return ERR_CAST(inode);
91
92 if (generation != 0 && generation != inode->vfs_inode.i_generation) {
93 iput(&inode->vfs_inode);
94 return ERR_PTR(-ESTALE);
95 }
96
97 return d_obtain_alias(&inode->vfs_inode);
98 }
99
btrfs_fh_to_parent(struct super_block * sb,struct fid * fh,int fh_len,int fh_type)100 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
101 int fh_len, int fh_type)
102 {
103 struct btrfs_fid *fid = (struct btrfs_fid *) fh;
104 u64 objectid, root_objectid;
105 u32 generation;
106
107 if (fh_type == FILEID_BTRFS_WITH_PARENT) {
108 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE)
109 return NULL;
110 root_objectid = fid->root_objectid;
111 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
112 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
113 return NULL;
114 root_objectid = fid->parent_root_objectid;
115 } else
116 return NULL;
117
118 objectid = fid->parent_objectid;
119 generation = fid->parent_gen;
120
121 return btrfs_get_dentry(sb, objectid, root_objectid, generation);
122 }
123
btrfs_fh_to_dentry(struct super_block * sb,struct fid * fh,int fh_len,int fh_type)124 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
125 int fh_len, int fh_type)
126 {
127 struct btrfs_fid *fid = (struct btrfs_fid *) fh;
128 u64 objectid, root_objectid;
129 u32 generation;
130
131 if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
132 fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
133 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
134 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
135 (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
136 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
137 return NULL;
138
139 objectid = fid->objectid;
140 root_objectid = fid->root_objectid;
141 generation = fid->gen;
142
143 return btrfs_get_dentry(sb, objectid, root_objectid, generation);
144 }
145
btrfs_get_parent(struct dentry * child)146 struct dentry *btrfs_get_parent(struct dentry *child)
147 {
148 struct btrfs_inode *dir = BTRFS_I(d_inode(child));
149 struct btrfs_inode *inode;
150 struct btrfs_root *root = dir->root;
151 struct btrfs_fs_info *fs_info = root->fs_info;
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(dir) == BTRFS_FIRST_FREE_OBJECTID) {
164 key.objectid = btrfs_root_id(root);
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(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 inode = btrfs_iget(key.objectid, root);
215 if (IS_ERR(inode))
216 return ERR_CAST(inode);
217
218 return d_obtain_alias(&inode->vfs_inode);
219 fail:
220 btrfs_free_path(path);
221 return ERR_PTR(ret);
222 }
223
btrfs_get_name(struct dentry * parent,char * name,struct dentry * child)224 static int btrfs_get_name(struct dentry *parent, char *name,
225 struct dentry *child)
226 {
227 struct btrfs_inode *inode = BTRFS_I(d_inode(child));
228 struct btrfs_inode *dir = BTRFS_I(d_inode(parent));
229 struct btrfs_root *root = dir->root;
230 struct btrfs_fs_info *fs_info = root->fs_info;
231 BTRFS_PATH_AUTO_FREE(path);
232 struct btrfs_inode_ref *iref;
233 struct btrfs_root_ref *rref;
234 struct extent_buffer *leaf;
235 unsigned long name_ptr;
236 struct btrfs_key key;
237 int name_len;
238 int ret;
239 u64 ino;
240
241 if (!S_ISDIR(dir->vfs_inode.i_mode))
242 return -EINVAL;
243
244 ino = btrfs_ino(inode);
245
246 path = btrfs_alloc_path();
247 if (!path)
248 return -ENOMEM;
249
250 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
251 key.objectid = btrfs_root_id(inode->root);
252 key.type = BTRFS_ROOT_BACKREF_KEY;
253 key.offset = (u64)-1;
254 root = fs_info->tree_root;
255 } else {
256 key.objectid = ino;
257 key.type = BTRFS_INODE_REF_KEY;
258 key.offset = btrfs_ino(dir);
259 }
260
261 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
262 if (ret < 0) {
263 return ret;
264 } else if (ret > 0) {
265 if (ino == BTRFS_FIRST_FREE_OBJECTID)
266 path->slots[0]--;
267 else
268 return -ENOENT;
269 }
270 leaf = path->nodes[0];
271
272 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
273 rref = btrfs_item_ptr(leaf, path->slots[0],
274 struct btrfs_root_ref);
275 name_ptr = (unsigned long)(rref + 1);
276 name_len = btrfs_root_ref_name_len(leaf, rref);
277 } else {
278 iref = btrfs_item_ptr(leaf, path->slots[0],
279 struct btrfs_inode_ref);
280 name_ptr = (unsigned long)(iref + 1);
281 name_len = btrfs_inode_ref_name_len(leaf, iref);
282 }
283
284 read_extent_buffer(leaf, name, name_ptr, name_len);
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