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

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
		if (btrfs_root_id(BTRFS_I(inode)->root) !=
27
		    btrfs_root_id(BTRFS_I(parent)->root))
28
			*max_len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
29
		else
30
			*max_len = BTRFS_FID_SIZE_CONNECTABLE;
31
		return FILEID_INVALID;
32
	} else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
33
		*max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
34
		return FILEID_INVALID;
35
	}
36

37
	len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
38
	type = FILEID_BTRFS_WITHOUT_PARENT;
39

40
	fid->objectid = btrfs_ino(BTRFS_I(inode));
41
	fid->root_objectid = btrfs_root_id(BTRFS_I(inode)->root);
42
	fid->gen = inode->i_generation;
43

44
	if (parent) {
45
		u64 parent_root_id;
46

47
		fid->parent_objectid = btrfs_ino(BTRFS_I(parent));
48
		fid->parent_gen = parent->i_generation;
49
		parent_root_id = btrfs_root_id(BTRFS_I(parent)->root);
50

51
		if (parent_root_id != fid->root_objectid) {
52
			if (*max_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
53
				return FILEID_INVALID;
54
			fid->parent_root_objectid = parent_root_id;
55
			len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
56
			type = FILEID_BTRFS_WITH_PARENT_ROOT;
57
		} else {
58
			len = BTRFS_FID_SIZE_CONNECTABLE;
59
			type = FILEID_BTRFS_WITH_PARENT;
60
		}
61
	}
62

63
	*max_len = len;
64
	return type;
65
}
66

67
/*
68
 * Read dentry of inode with @objectid from filesystem root @root_objectid.
69
 *
70
 * @sb:             the filesystem super block
71
 * @objectid:       inode objectid
72
 * @root_objectid:  object id of the subvolume root where to look up the inode
73
 * @generation:     optional, if not zero, verify that the found inode
74
 *                  generation matches
75
 *
76
 * Return dentry alias for the inode, otherwise an error. In case the
77
 * generation does not match return ESTALE.
78
 */
79
struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
80
				u64 root_objectid, u64 generation)
81
{
82
	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
83
	struct btrfs_root *root;
84
	struct btrfs_inode *inode;
85

86
	if (objectid < BTRFS_FIRST_FREE_OBJECTID)
87
		return ERR_PTR(-ESTALE);
88

89
	root = btrfs_get_fs_root(fs_info, root_objectid, true);
90
	if (IS_ERR(root))
91
		return ERR_CAST(root);
92

93
	inode = btrfs_iget(objectid, root);
94
	btrfs_put_root(root);
95
	if (IS_ERR(inode))
96
		return ERR_CAST(inode);
97

98
	if (generation != 0 && generation != inode->vfs_inode.i_generation) {
99
		iput(&inode->vfs_inode);
100
		return ERR_PTR(-ESTALE);
101
	}
102

103
	return d_obtain_alias(&inode->vfs_inode);
104
}
105

106
static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
107
					 int fh_len, int fh_type)
108
{
109
	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
110
	u64 objectid, root_objectid;
111
	u32 generation;
112

113
	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
114
		if (fh_len <  BTRFS_FID_SIZE_CONNECTABLE)
115
			return NULL;
116
		root_objectid = fid->root_objectid;
117
	} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
118
		if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
119
			return NULL;
120
		root_objectid = fid->parent_root_objectid;
121
	} else
122
		return NULL;
123

124
	objectid = fid->parent_objectid;
125
	generation = fid->parent_gen;
126

127
	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
128
}
129

130
static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
131
					 int fh_len, int fh_type)
132
{
133
	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
134
	u64 objectid, root_objectid;
135
	u32 generation;
136

137
	if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
138
	     fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
139
	    (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
140
	     fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
141
	    (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
142
	     fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
143
		return NULL;
144

145
	objectid = fid->objectid;
146
	root_objectid = fid->root_objectid;
147
	generation = fid->gen;
148

149
	return btrfs_get_dentry(sb, objectid, root_objectid, generation);
150
}
151

152
struct dentry *btrfs_get_parent(struct dentry *child)
153
{
154
	struct btrfs_inode *dir = BTRFS_I(d_inode(child));
155
	struct btrfs_inode *inode;
156
	struct btrfs_root *root = dir->root;
157
	struct btrfs_fs_info *fs_info = root->fs_info;
158
	struct btrfs_path *path;
159
	struct extent_buffer *leaf;
160
	struct btrfs_root_ref *ref;
161
	struct btrfs_key key;
162
	struct btrfs_key found_key;
163
	int ret;
164

165
	path = btrfs_alloc_path();
166
	if (!path)
167
		return ERR_PTR(-ENOMEM);
168

169
	if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) {
170
		key.objectid = btrfs_root_id(root);
171
		key.type = BTRFS_ROOT_BACKREF_KEY;
172
		key.offset = (u64)-1;
173
		root = fs_info->tree_root;
174
	} else {
175
		key.objectid = btrfs_ino(dir);
176
		key.type = BTRFS_INODE_REF_KEY;
177
		key.offset = (u64)-1;
178
	}
179

180
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
181
	if (ret < 0)
182
		goto fail;
183
	if (unlikely(ret == 0)) {
184
		/*
185
		 * Key with offset of -1 found, there would have to exist an
186
		 * inode with such number or a root with such id.
187
		 */
188
		ret = -EUCLEAN;
189
		goto fail;
190
	}
191

192
	if (path->slots[0] == 0) {
193
		ret = -ENOENT;
194
		goto fail;
195
	}
196

197
	path->slots[0]--;
198
	leaf = path->nodes[0];
199

200
	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
201
	if (found_key.objectid != key.objectid || found_key.type != key.type) {
202
		ret = -ENOENT;
203
		goto fail;
204
	}
205

206
	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
207
		ref = btrfs_item_ptr(leaf, path->slots[0],
208
				     struct btrfs_root_ref);
209
		key.objectid = btrfs_root_ref_dirid(leaf, ref);
210
	} else {
211
		key.objectid = found_key.offset;
212
	}
213
	btrfs_free_path(path);
214

215
	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
216
		return btrfs_get_dentry(fs_info->sb, key.objectid,
217
					found_key.offset, 0);
218
	}
219

220
	inode = btrfs_iget(key.objectid, root);
221
	if (IS_ERR(inode))
222
		return ERR_CAST(inode);
223

224
	return d_obtain_alias(&inode->vfs_inode);
225
fail:
226
	btrfs_free_path(path);
227
	return ERR_PTR(ret);
228
}
229

230
static int btrfs_get_name(struct dentry *parent, char *name,
231
			  struct dentry *child)
232
{
233
	struct btrfs_inode *inode = BTRFS_I(d_inode(child));
234
	struct btrfs_inode *dir = BTRFS_I(d_inode(parent));
235
	struct btrfs_root *root = dir->root;
236
	struct btrfs_fs_info *fs_info = root->fs_info;
237
	BTRFS_PATH_AUTO_FREE(path);
238
	struct btrfs_inode_ref *iref;
239
	struct btrfs_root_ref *rref;
240
	struct extent_buffer *leaf;
241
	unsigned long name_ptr;
242
	struct btrfs_key key;
243
	int name_len;
244
	int ret;
245
	u64 ino;
246

247
	if (!S_ISDIR(dir->vfs_inode.i_mode))
248
		return -EINVAL;
249

250
	ino = btrfs_ino(inode);
251

252
	path = btrfs_alloc_path();
253
	if (!path)
254
		return -ENOMEM;
255

256
	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
257
		key.objectid = btrfs_root_id(inode->root);
258
		key.type = BTRFS_ROOT_BACKREF_KEY;
259
		key.offset = (u64)-1;
260
		root = fs_info->tree_root;
261
	} else {
262
		key.objectid = ino;
263
		key.type = BTRFS_INODE_REF_KEY;
264
		key.offset = btrfs_ino(dir);
265
	}
266

267
	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
268
	if (ret < 0) {
269
		return ret;
270
	} else if (ret > 0) {
271
		if (ino == BTRFS_FIRST_FREE_OBJECTID)
272
			path->slots[0]--;
273
		else
274
			return -ENOENT;
275
	}
276
	leaf = path->nodes[0];
277

278
	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
279
		rref = btrfs_item_ptr(leaf, path->slots[0],
280
				     struct btrfs_root_ref);
281
		name_ptr = (unsigned long)(rref + 1);
282
		name_len = btrfs_root_ref_name_len(leaf, rref);
283
	} else {
284
		iref = btrfs_item_ptr(leaf, path->slots[0],
285
				      struct btrfs_inode_ref);
286
		name_ptr = (unsigned long)(iref + 1);
287
		name_len = btrfs_inode_ref_name_len(leaf, iref);
288
	}
289

290
	read_extent_buffer(leaf, name, name_ptr, name_len);
291

292
	/*
293
	 * have to add the null termination to make sure that reconnect_path
294
	 * gets the right len for strlen
295
	 */
296
	name[name_len] = '\0';
297

298
	return 0;
299
}
300

301
const struct export_operations btrfs_export_ops = {
302
	.encode_fh	= btrfs_encode_fh,
303
	.fh_to_dentry	= btrfs_fh_to_dentry,
304
	.fh_to_parent	= btrfs_fh_to_parent,
305
	.get_parent	= btrfs_get_parent,
306
	.get_name	= btrfs_get_name,
307
};
308

309