Merge tag 'locks-v3.15-3' of git://git.samba.org/jlayton/linux
[firefly-linux-kernel-4.4.55.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(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         btrfs_set_key_type(&key, 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         btrfs_set_key_type(&key, 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 = child->d_inode;
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));
215 fail:
216         btrfs_free_path(path);
217         return ERR_PTR(ret);
218 }
219
220 static int btrfs_get_name(struct dentry *parent, char *name,
221                           struct dentry *child)
222 {
223         struct inode *inode = child->d_inode;
224         struct inode *dir = parent->d_inode;
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
298 const 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 };