Line data Source code
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 :
19 11821 : static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
20 : struct inode *parent)
21 : {
22 11821 : struct btrfs_fid *fid = (struct btrfs_fid *)fh;
23 11821 : int len = *max_len;
24 11821 : int type;
25 :
26 11821 : if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
27 0 : *max_len = BTRFS_FID_SIZE_CONNECTABLE;
28 0 : return FILEID_INVALID;
29 11821 : } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
30 0 : *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
31 0 : return FILEID_INVALID;
32 : }
33 :
34 11821 : len = BTRFS_FID_SIZE_NON_CONNECTABLE;
35 11821 : type = FILEID_BTRFS_WITHOUT_PARENT;
36 :
37 11821 : fid->objectid = btrfs_ino(BTRFS_I(inode));
38 11821 : fid->root_objectid = BTRFS_I(inode)->root->root_key.objectid;
39 11821 : fid->gen = inode->i_generation;
40 :
41 11821 : if (parent) {
42 0 : u64 parent_root_id;
43 :
44 0 : fid->parent_objectid = BTRFS_I(parent)->location.objectid;
45 0 : fid->parent_gen = parent->i_generation;
46 0 : parent_root_id = BTRFS_I(parent)->root->root_key.objectid;
47 :
48 0 : if (parent_root_id != fid->root_objectid) {
49 0 : fid->parent_root_objectid = parent_root_id;
50 0 : len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
51 0 : type = FILEID_BTRFS_WITH_PARENT_ROOT;
52 : } else {
53 : len = BTRFS_FID_SIZE_CONNECTABLE;
54 : type = FILEID_BTRFS_WITH_PARENT;
55 : }
56 : }
57 :
58 11821 : *max_len = len;
59 11821 : 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 : */
74 4235 : struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
75 : u64 root_objectid, u64 generation)
76 : {
77 4235 : struct btrfs_fs_info *fs_info = btrfs_sb(sb);
78 4235 : struct btrfs_root *root;
79 4235 : struct inode *inode;
80 :
81 4235 : if (objectid < BTRFS_FIRST_FREE_OBJECTID)
82 : return ERR_PTR(-ESTALE);
83 :
84 4235 : root = btrfs_get_fs_root(fs_info, root_objectid, true);
85 4235 : if (IS_ERR(root))
86 : return ERR_CAST(root);
87 :
88 4235 : inode = btrfs_iget(sb, objectid, root);
89 4235 : btrfs_put_root(root);
90 4235 : if (IS_ERR(inode))
91 : return ERR_CAST(inode);
92 :
93 3200 : if (generation != 0 && generation != inode->i_generation) {
94 0 : iput(inode);
95 0 : return ERR_PTR(-ESTALE);
96 : }
97 :
98 3200 : return d_obtain_alias(inode);
99 : }
100 :
101 0 : static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
102 : int fh_len, int fh_type)
103 : {
104 0 : struct btrfs_fid *fid = (struct btrfs_fid *) fh;
105 0 : u64 objectid, root_objectid;
106 0 : u32 generation;
107 :
108 0 : if (fh_type == FILEID_BTRFS_WITH_PARENT) {
109 0 : if (fh_len < BTRFS_FID_SIZE_CONNECTABLE)
110 : return NULL;
111 0 : root_objectid = fid->root_objectid;
112 0 : } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
113 0 : if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
114 : return NULL;
115 0 : root_objectid = fid->parent_root_objectid;
116 : } else
117 : return NULL;
118 :
119 0 : objectid = fid->parent_objectid;
120 0 : generation = fid->parent_gen;
121 :
122 0 : return btrfs_get_dentry(sb, objectid, root_objectid, generation);
123 : }
124 :
125 4223 : static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
126 : int fh_len, int fh_type)
127 : {
128 4223 : struct btrfs_fid *fid = (struct btrfs_fid *) fh;
129 4223 : u64 objectid, root_objectid;
130 4223 : u32 generation;
131 :
132 4223 : if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
133 4223 : fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
134 4223 : (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
135 4223 : fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
136 4223 : (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
137 4223 : fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
138 : return NULL;
139 :
140 4223 : objectid = fid->objectid;
141 4223 : root_objectid = fid->root_objectid;
142 4223 : generation = fid->gen;
143 :
144 4223 : return btrfs_get_dentry(sb, objectid, root_objectid, generation);
145 : }
146 :
147 15 : struct dentry *btrfs_get_parent(struct dentry *child)
148 : {
149 15 : struct inode *dir = d_inode(child);
150 15 : struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
151 15 : struct btrfs_root *root = BTRFS_I(dir)->root;
152 15 : struct btrfs_path *path;
153 15 : struct extent_buffer *leaf;
154 15 : struct btrfs_root_ref *ref;
155 15 : struct btrfs_key key;
156 15 : struct btrfs_key found_key;
157 15 : int ret;
158 :
159 15 : path = btrfs_alloc_path();
160 15 : if (!path)
161 : return ERR_PTR(-ENOMEM);
162 :
163 15 : if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
164 6 : key.objectid = root->root_key.objectid;
165 6 : key.type = BTRFS_ROOT_BACKREF_KEY;
166 6 : key.offset = (u64)-1;
167 6 : root = fs_info->tree_root;
168 : } else {
169 9 : key.objectid = btrfs_ino(BTRFS_I(dir));
170 9 : key.type = BTRFS_INODE_REF_KEY;
171 9 : key.offset = (u64)-1;
172 : }
173 :
174 15 : ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
175 15 : if (ret < 0)
176 0 : goto fail;
177 :
178 15 : BUG_ON(ret == 0); /* Key with offset of -1 found */
179 15 : if (path->slots[0] == 0) {
180 0 : ret = -ENOENT;
181 0 : goto fail;
182 : }
183 :
184 15 : path->slots[0]--;
185 15 : leaf = path->nodes[0];
186 :
187 15 : btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
188 15 : if (found_key.objectid != key.objectid || found_key.type != key.type) {
189 0 : ret = -ENOENT;
190 0 : goto fail;
191 : }
192 :
193 15 : if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
194 6 : ref = btrfs_item_ptr(leaf, path->slots[0],
195 : struct btrfs_root_ref);
196 6 : key.objectid = btrfs_root_ref_dirid(leaf, ref);
197 : } else {
198 9 : key.objectid = found_key.offset;
199 : }
200 15 : btrfs_free_path(path);
201 :
202 15 : if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
203 6 : return btrfs_get_dentry(fs_info->sb, key.objectid,
204 : found_key.offset, 0);
205 : }
206 :
207 9 : return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root));
208 0 : fail:
209 0 : btrfs_free_path(path);
210 0 : return ERR_PTR(ret);
211 : }
212 :
213 9 : static int btrfs_get_name(struct dentry *parent, char *name,
214 : struct dentry *child)
215 : {
216 9 : struct inode *inode = d_inode(child);
217 9 : struct inode *dir = d_inode(parent);
218 9 : struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
219 9 : struct btrfs_path *path;
220 9 : struct btrfs_root *root = BTRFS_I(dir)->root;
221 9 : struct btrfs_inode_ref *iref;
222 9 : struct btrfs_root_ref *rref;
223 9 : struct extent_buffer *leaf;
224 9 : unsigned long name_ptr;
225 9 : struct btrfs_key key;
226 9 : int name_len;
227 9 : int ret;
228 9 : u64 ino;
229 :
230 9 : if (!S_ISDIR(dir->i_mode))
231 : return -EINVAL;
232 :
233 9 : ino = btrfs_ino(BTRFS_I(inode));
234 :
235 9 : path = btrfs_alloc_path();
236 9 : if (!path)
237 : return -ENOMEM;
238 :
239 9 : if (ino == BTRFS_FIRST_FREE_OBJECTID) {
240 0 : key.objectid = BTRFS_I(inode)->root->root_key.objectid;
241 0 : key.type = BTRFS_ROOT_BACKREF_KEY;
242 0 : key.offset = (u64)-1;
243 0 : root = fs_info->tree_root;
244 : } else {
245 9 : key.objectid = ino;
246 9 : key.offset = btrfs_ino(BTRFS_I(dir));
247 9 : key.type = BTRFS_INODE_REF_KEY;
248 : }
249 :
250 9 : ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
251 9 : if (ret < 0) {
252 0 : btrfs_free_path(path);
253 0 : return ret;
254 9 : } else if (ret > 0) {
255 0 : if (ino == BTRFS_FIRST_FREE_OBJECTID) {
256 0 : path->slots[0]--;
257 : } else {
258 0 : btrfs_free_path(path);
259 0 : return -ENOENT;
260 : }
261 : }
262 9 : leaf = path->nodes[0];
263 :
264 9 : if (ino == BTRFS_FIRST_FREE_OBJECTID) {
265 0 : rref = btrfs_item_ptr(leaf, path->slots[0],
266 : struct btrfs_root_ref);
267 0 : name_ptr = (unsigned long)(rref + 1);
268 0 : name_len = btrfs_root_ref_name_len(leaf, rref);
269 : } else {
270 9 : iref = btrfs_item_ptr(leaf, path->slots[0],
271 : struct btrfs_inode_ref);
272 9 : name_ptr = (unsigned long)(iref + 1);
273 9 : name_len = btrfs_inode_ref_name_len(leaf, iref);
274 : }
275 :
276 9 : read_extent_buffer(leaf, name, name_ptr, name_len);
277 9 : btrfs_free_path(path);
278 :
279 : /*
280 : * have to add the null termination to make sure that reconnect_path
281 : * gets the right len for strlen
282 : */
283 9 : name[name_len] = '\0';
284 :
285 9 : return 0;
286 : }
287 :
288 : const struct export_operations btrfs_export_ops = {
289 : .encode_fh = btrfs_encode_fh,
290 : .fh_to_dentry = btrfs_fh_to_dentry,
291 : .fh_to_parent = btrfs_fh_to_parent,
292 : .get_parent = btrfs_get_parent,
293 : .get_name = btrfs_get_name,
294 : };
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