1#include <linux/fs.h>
2#include <linux/types.h>
3#include "ctree.h"
4#include "disk-io.h"
5#include "btrfs_inode.h"
6#include "print-tree.h"
7#include "export.h"
8
9#define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
10						 parent_objectid) / 4)
11#define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
12					     parent_root_objectid) / 4)
13#define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
14
15static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
16			   struct inode *parent)
17{
18	struct btrfs_fid *fid = (struct btrfs_fid *)fh;
19	int len = *max_len;
20	int type;
21
22	if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
23		*max_len = BTRFS_FID_SIZE_CONNECTABLE;
24		return FILEID_INVALID;
25	} else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
26		*max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
27		return FILEID_INVALID;
28	}
29
30	len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
31	type = FILEID_BTRFS_WITHOUT_PARENT;
32
33	fid->objectid = btrfs_ino(inode);
34	fid->root_objectid = BTRFS_I(inode)->root->objectid;
35	fid->gen = inode->i_generation;
36
37	if (parent) {
38		u64 parent_root_id;
39
40		fid->parent_objectid = BTRFS_I(parent)->location.objectid;
41		fid->parent_gen = parent->i_generation;
42		parent_root_id = BTRFS_I(parent)->root->objectid;
43
44		if (parent_root_id != fid->root_objectid) {
45			fid->parent_root_objectid = parent_root_id;
46			len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
47			type = FILEID_BTRFS_WITH_PARENT_ROOT;
48		} else {
49			len = BTRFS_FID_SIZE_CONNECTABLE;
50			type = FILEID_BTRFS_WITH_PARENT;
51		}
52	}
53
54	*max_len = len;
55	return type;
56}
57
58static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
59				       u64 root_objectid, u32 generation,
60				       int check_generation)
61{
62	struct btrfs_fs_info *fs_info = btrfs_sb(sb);
63	struct btrfs_root *root;
64	struct inode *inode;
65	struct btrfs_key key;
66	int index;
67	int err = 0;
68
69	if (objectid < BTRFS_FIRST_FREE_OBJECTID)
70		return ERR_PTR(-ESTALE);
71
72	key.objectid = root_objectid;
73	key.type = BTRFS_ROOT_ITEM_KEY;
74	key.offset = (u64)-1;
75
76	index = srcu_read_lock(&fs_info->subvol_srcu);
77
78	root = btrfs_read_fs_root_no_name(fs_info, &key);
79	if (IS_ERR(root)) {
80		err = PTR_ERR(root);
81		goto fail;
82	}
83
84	key.objectid = objectid;
85	key.type = BTRFS_INODE_ITEM_KEY;
86	key.offset = 0;
87
88	inode = btrfs_iget(sb, &key, root, NULL);
89	if (IS_ERR(inode)) {
90		err = PTR_ERR(inode);
91		goto fail;
92	}
93
94	srcu_read_unlock(&fs_info->subvol_srcu, index);
95
96	if (check_generation && generation != inode->i_generation) {
97		iput(inode);
98		return ERR_PTR(-ESTALE);
99	}
100
101	return d_obtain_alias(inode);
102fail:
103	srcu_read_unlock(&fs_info->subvol_srcu, index);
104	return ERR_PTR(err);
105}
106
107static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
108					 int fh_len, int fh_type)
109{
110	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
111	u64 objectid, root_objectid;
112	u32 generation;
113
114	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
115		if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
116			return NULL;
117		root_objectid = fid->root_objectid;
118	} else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
119		if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
120			return NULL;
121		root_objectid = fid->parent_root_objectid;
122	} else
123		return NULL;
124
125	objectid = fid->parent_objectid;
126	generation = fid->parent_gen;
127
128	return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
129}
130
131static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
132					 int fh_len, int fh_type)
133{
134	struct btrfs_fid *fid = (struct btrfs_fid *) fh;
135	u64 objectid, root_objectid;
136	u32 generation;
137
138	if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
139	     fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
140	    (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
141	     fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
142	    (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
143	     fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
144		return NULL;
145
146	objectid = fid->objectid;
147	root_objectid = fid->root_objectid;
148	generation = fid->gen;
149
150	return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
151}
152
153static struct dentry *btrfs_get_parent(struct dentry *child)
154{
155	struct inode *dir = d_inode(child);
156	struct btrfs_root *root = BTRFS_I(dir)->root;
157	struct btrfs_path *path;
158	struct extent_buffer *leaf;
159	struct btrfs_root_ref *ref;
160	struct btrfs_key key;
161	struct btrfs_key found_key;
162	int ret;
163
164	path = btrfs_alloc_path();
165	if (!path)
166		return ERR_PTR(-ENOMEM);
167
168	if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) {
169		key.objectid = root->root_key.objectid;
170		key.type = BTRFS_ROOT_BACKREF_KEY;
171		key.offset = (u64)-1;
172		root = root->fs_info->tree_root;
173	} else {
174		key.objectid = btrfs_ino(dir);
175		key.type = BTRFS_INODE_REF_KEY;
176		key.offset = (u64)-1;
177	}
178
179	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
180	if (ret < 0)
181		goto fail;
182
183	BUG_ON(ret == 0); /* Key with offset of -1 found */
184	if (path->slots[0] == 0) {
185		ret = -ENOENT;
186		goto fail;
187	}
188
189	path->slots[0]--;
190	leaf = path->nodes[0];
191
192	btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
193	if (found_key.objectid != key.objectid || found_key.type != key.type) {
194		ret = -ENOENT;
195		goto fail;
196	}
197
198	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
199		ref = btrfs_item_ptr(leaf, path->slots[0],
200				     struct btrfs_root_ref);
201		key.objectid = btrfs_root_ref_dirid(leaf, ref);
202	} else {
203		key.objectid = found_key.offset;
204	}
205	btrfs_free_path(path);
206
207	if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
208		return btrfs_get_dentry(root->fs_info->sb, key.objectid,
209					found_key.offset, 0, 0);
210	}
211
212	key.type = BTRFS_INODE_ITEM_KEY;
213	key.offset = 0;
214	return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
215fail:
216	btrfs_free_path(path);
217	return ERR_PTR(ret);
218}
219
220static 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_path *path;
226	struct btrfs_root *root = BTRFS_I(dir)->root;
227	struct btrfs_inode_ref *iref;
228	struct btrfs_root_ref *rref;
229	struct extent_buffer *leaf;
230	unsigned long name_ptr;
231	struct btrfs_key key;
232	int name_len;
233	int ret;
234	u64 ino;
235
236	if (!dir || !inode)
237		return -EINVAL;
238
239	if (!S_ISDIR(dir->i_mode))
240		return -EINVAL;
241
242	ino = btrfs_ino(inode);
243
244	path = btrfs_alloc_path();
245	if (!path)
246		return -ENOMEM;
247	path->leave_spinning = 1;
248
249	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
250		key.objectid = BTRFS_I(inode)->root->root_key.objectid;
251		key.type = BTRFS_ROOT_BACKREF_KEY;
252		key.offset = (u64)-1;
253		root = root->fs_info->tree_root;
254	} else {
255		key.objectid = ino;
256		key.offset = btrfs_ino(dir);
257		key.type = BTRFS_INODE_REF_KEY;
258	}
259
260	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
261	if (ret < 0) {
262		btrfs_free_path(path);
263		return ret;
264	} else if (ret > 0) {
265		if (ino == BTRFS_FIRST_FREE_OBJECTID) {
266			path->slots[0]--;
267		} else {
268			btrfs_free_path(path);
269			return -ENOENT;
270		}
271	}
272	leaf = path->nodes[0];
273
274	if (ino == BTRFS_FIRST_FREE_OBJECTID) {
275		rref = btrfs_item_ptr(leaf, path->slots[0],
276				     struct btrfs_root_ref);
277		name_ptr = (unsigned long)(rref + 1);
278		name_len = btrfs_root_ref_name_len(leaf, rref);
279	} else {
280		iref = btrfs_item_ptr(leaf, path->slots[0],
281				      struct btrfs_inode_ref);
282		name_ptr = (unsigned long)(iref + 1);
283		name_len = btrfs_inode_ref_name_len(leaf, iref);
284	}
285
286	read_extent_buffer(leaf, name, name_ptr, name_len);
287	btrfs_free_path(path);
288
289	/*
290	 * have to add the null termination to make sure that reconnect_path
291	 * gets the right len for strlen
292	 */
293	name[name_len] = '\0';
294
295	return 0;
296}
297
298const struct export_operations btrfs_export_ops = {
299	.encode_fh	= btrfs_encode_fh,
300	.fh_to_dentry	= btrfs_fh_to_dentry,
301	.fh_to_parent	= btrfs_fh_to_parent,
302	.get_parent	= btrfs_get_parent,
303	.get_name	= btrfs_get_name,
304};
305