87144c9f9593823922161c61a687c19ab13e7e71
[sfrench/cifs-2.6.git] / fs / btrfs / export.c
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
15 static 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(BTRFS_I(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
58 static 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);
102 fail:
103         srcu_read_unlock(&fs_info->subvol_srcu, index);
104         return ERR_PTR(err);
105 }
106
107 static 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
131 static 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
153 static struct dentry *btrfs_get_parent(struct dentry *child)
154 {
155         struct inode *dir = d_inode(child);
156         struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
157         struct btrfs_root *root = BTRFS_I(dir)->root;
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(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
170                 key.objectid = root->root_key.objectid;
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(BTRFS_I(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
184         BUG_ON(ret == 0); /* Key with offset of -1 found */
185         if (path->slots[0] == 0) {
186                 ret = -ENOENT;
187                 goto fail;
188         }
189
190         path->slots[0]--;
191         leaf = path->nodes[0];
192
193         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
194         if (found_key.objectid != key.objectid || found_key.type != key.type) {
195                 ret = -ENOENT;
196                 goto fail;
197         }
198
199         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
200                 ref = btrfs_item_ptr(leaf, path->slots[0],
201                                      struct btrfs_root_ref);
202                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
203         } else {
204                 key.objectid = found_key.offset;
205         }
206         btrfs_free_path(path);
207
208         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
209                 return btrfs_get_dentry(fs_info->sb, key.objectid,
210                                         found_key.offset, 0, 0);
211         }
212
213         key.type = BTRFS_INODE_ITEM_KEY;
214         key.offset = 0;
215         return d_obtain_alias(btrfs_iget(fs_info->sb, &key, root, NULL));
216 fail:
217         btrfs_free_path(path);
218         return ERR_PTR(ret);
219 }
220
221 static int btrfs_get_name(struct dentry *parent, char *name,
222                           struct dentry *child)
223 {
224         struct inode *inode = d_inode(child);
225         struct inode *dir = d_inode(parent);
226         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
227         struct btrfs_path *path;
228         struct btrfs_root *root = BTRFS_I(dir)->root;
229         struct btrfs_inode_ref *iref;
230         struct btrfs_root_ref *rref;
231         struct extent_buffer *leaf;
232         unsigned long name_ptr;
233         struct btrfs_key key;
234         int name_len;
235         int ret;
236         u64 ino;
237
238         if (!S_ISDIR(dir->i_mode))
239                 return -EINVAL;
240
241         ino = btrfs_ino(BTRFS_I(inode));
242
243         path = btrfs_alloc_path();
244         if (!path)
245                 return -ENOMEM;
246         path->leave_spinning = 1;
247
248         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
249                 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
250                 key.type = BTRFS_ROOT_BACKREF_KEY;
251                 key.offset = (u64)-1;
252                 root = fs_info->tree_root;
253         } else {
254                 key.objectid = ino;
255                 key.offset = btrfs_ino(BTRFS_I(dir));
256                 key.type = BTRFS_INODE_REF_KEY;
257         }
258
259         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
260         if (ret < 0) {
261                 btrfs_free_path(path);
262                 return ret;
263         } else if (ret > 0) {
264                 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
265                         path->slots[0]--;
266                 } else {
267                         btrfs_free_path(path);
268                         return -ENOENT;
269                 }
270         }
271         leaf = path->nodes[0];
272
273         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
274                 rref = btrfs_item_ptr(leaf, path->slots[0],
275                                      struct btrfs_root_ref);
276                 name_ptr = (unsigned long)(rref + 1);
277                 name_len = btrfs_root_ref_name_len(leaf, rref);
278         } else {
279                 iref = btrfs_item_ptr(leaf, path->slots[0],
280                                       struct btrfs_inode_ref);
281                 name_ptr = (unsigned long)(iref + 1);
282                 name_len = btrfs_inode_ref_name_len(leaf, iref);
283         }
284
285         read_extent_buffer(leaf, name, name_ptr, name_len);
286         btrfs_free_path(path);
287
288         /*
289          * have to add the null termination to make sure that reconnect_path
290          * gets the right len for strlen
291          */
292         name[name_len] = '\0';
293
294         return 0;
295 }
296
297 const struct export_operations btrfs_export_ops = {
298         .encode_fh      = btrfs_encode_fh,
299         .fh_to_dentry   = btrfs_fh_to_dentry,
300         .fh_to_parent   = btrfs_fh_to_parent,
301         .get_parent     = btrfs_get_parent,
302         .get_name       = btrfs_get_name,
303 };