Merge git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable
[~shefty/rdma-dev.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 #include "compat.h"
9
10 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
11                                                  parent_objectid) / 4)
12 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
13                                              parent_root_objectid) / 4)
14 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
15
16 static int btrfs_encode_fh(struct dentry *dentry, u32 *fh, int *max_len,
17                            int connectable)
18 {
19         struct btrfs_fid *fid = (struct btrfs_fid *)fh;
20         struct inode *inode = dentry->d_inode;
21         int len = *max_len;
22         int type;
23
24         if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) ||
25             (connectable && len < BTRFS_FID_SIZE_CONNECTABLE))
26                 return 255;
27
28         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
29         type = FILEID_BTRFS_WITHOUT_PARENT;
30
31         fid->objectid = inode->i_ino;
32         fid->root_objectid = BTRFS_I(inode)->root->objectid;
33         fid->gen = inode->i_generation;
34
35         if (connectable && !S_ISDIR(inode->i_mode)) {
36                 struct inode *parent;
37                 u64 parent_root_id;
38
39                 spin_lock(&dentry->d_lock);
40
41                 parent = dentry->d_parent->d_inode;
42                 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
43                 fid->parent_gen = parent->i_generation;
44                 parent_root_id = BTRFS_I(parent)->root->objectid;
45
46                 spin_unlock(&dentry->d_lock);
47
48                 if (parent_root_id != fid->root_objectid) {
49                         fid->parent_root_objectid = parent_root_id;
50                         len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
51                         type = FILEID_BTRFS_WITH_PARENT_ROOT;
52                 } else {
53                         len = BTRFS_FID_SIZE_CONNECTABLE;
54                         type = FILEID_BTRFS_WITH_PARENT;
55                 }
56         }
57
58         *max_len = len;
59         return type;
60 }
61
62 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
63                                        u64 root_objectid, u32 generation,
64                                        int check_generation)
65 {
66         struct btrfs_fs_info *fs_info = btrfs_sb(sb)->fs_info;
67         struct btrfs_root *root;
68         struct inode *inode;
69         struct btrfs_key key;
70         int index;
71         int err = 0;
72
73         if (objectid < BTRFS_FIRST_FREE_OBJECTID)
74                 return ERR_PTR(-ESTALE);
75
76         key.objectid = root_objectid;
77         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
78         key.offset = (u64)-1;
79
80         index = srcu_read_lock(&fs_info->subvol_srcu);
81
82         root = btrfs_read_fs_root_no_name(fs_info, &key);
83         if (IS_ERR(root)) {
84                 err = PTR_ERR(root);
85                 goto fail;
86         }
87
88         if (btrfs_root_refs(&root->root_item) == 0) {
89                 err = -ENOENT;
90                 goto fail;
91         }
92
93         key.objectid = objectid;
94         btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY);
95         key.offset = 0;
96
97         inode = btrfs_iget(sb, &key, root, NULL);
98         if (IS_ERR(inode)) {
99                 err = PTR_ERR(inode);
100                 goto fail;
101         }
102
103         srcu_read_unlock(&fs_info->subvol_srcu, index);
104
105         if (check_generation && generation != inode->i_generation) {
106                 iput(inode);
107                 return ERR_PTR(-ESTALE);
108         }
109
110         return d_obtain_alias(inode);
111 fail:
112         srcu_read_unlock(&fs_info->subvol_srcu, index);
113         return ERR_PTR(err);
114 }
115
116 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
117                                          int fh_len, int fh_type)
118 {
119         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
120         u64 objectid, root_objectid;
121         u32 generation;
122
123         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
124                 if (fh_len !=  BTRFS_FID_SIZE_CONNECTABLE)
125                         return NULL;
126                 root_objectid = fid->root_objectid;
127         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
128                 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT)
129                         return NULL;
130                 root_objectid = fid->parent_root_objectid;
131         } else
132                 return NULL;
133
134         objectid = fid->parent_objectid;
135         generation = fid->parent_gen;
136
137         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
138 }
139
140 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
141                                          int fh_len, int fh_type)
142 {
143         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
144         u64 objectid, root_objectid;
145         u32 generation;
146
147         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
148              fh_len != BTRFS_FID_SIZE_CONNECTABLE) &&
149             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
150              fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
151             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
152              fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE))
153                 return NULL;
154
155         objectid = fid->objectid;
156         root_objectid = fid->root_objectid;
157         generation = fid->gen;
158
159         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
160 }
161
162 static struct dentry *btrfs_get_parent(struct dentry *child)
163 {
164         struct inode *dir = child->d_inode;
165         struct btrfs_root *root = BTRFS_I(dir)->root;
166         struct btrfs_path *path;
167         struct extent_buffer *leaf;
168         struct btrfs_root_ref *ref;
169         struct btrfs_key key;
170         struct btrfs_key found_key;
171         int ret;
172
173         path = btrfs_alloc_path();
174         if (!path)
175                 return ERR_PTR(-ENOMEM);
176
177         if (dir->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
178                 key.objectid = root->root_key.objectid;
179                 key.type = BTRFS_ROOT_BACKREF_KEY;
180                 key.offset = (u64)-1;
181                 root = root->fs_info->tree_root;
182         } else {
183                 key.objectid = dir->i_ino;
184                 key.type = BTRFS_INODE_REF_KEY;
185                 key.offset = (u64)-1;
186         }
187
188         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
189         if (ret < 0)
190                 goto fail;
191
192         BUG_ON(ret == 0);
193         if (path->slots[0] == 0) {
194                 ret = -ENOENT;
195                 goto fail;
196         }
197
198         path->slots[0]--;
199         leaf = path->nodes[0];
200
201         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
202         if (found_key.objectid != key.objectid || found_key.type != key.type) {
203                 ret = -ENOENT;
204                 goto fail;
205         }
206
207         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
208                 ref = btrfs_item_ptr(leaf, path->slots[0],
209                                      struct btrfs_root_ref);
210                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
211         } else {
212                 key.objectid = found_key.offset;
213         }
214         btrfs_free_path(path);
215
216         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
217                 return btrfs_get_dentry(root->fs_info->sb, key.objectid,
218                                         found_key.offset, 0, 0);
219         }
220
221         key.type = BTRFS_INODE_ITEM_KEY;
222         key.offset = 0;
223         return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL));
224 fail:
225         btrfs_free_path(path);
226         return ERR_PTR(ret);
227 }
228
229 static int btrfs_get_name(struct dentry *parent, char *name,
230                           struct dentry *child)
231 {
232         struct inode *inode = child->d_inode;
233         struct inode *dir = parent->d_inode;
234         struct btrfs_path *path;
235         struct btrfs_root *root = BTRFS_I(dir)->root;
236         struct btrfs_inode_ref *iref;
237         struct btrfs_root_ref *rref;
238         struct extent_buffer *leaf;
239         unsigned long name_ptr;
240         struct btrfs_key key;
241         int name_len;
242         int ret;
243
244         if (!dir || !inode)
245                 return -EINVAL;
246
247         if (!S_ISDIR(dir->i_mode))
248                 return -EINVAL;
249
250         path = btrfs_alloc_path();
251         if (!path)
252                 return -ENOMEM;
253         path->leave_spinning = 1;
254
255         if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
256                 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
257                 key.type = BTRFS_ROOT_BACKREF_KEY;
258                 key.offset = (u64)-1;
259                 root = root->fs_info->tree_root;
260         } else {
261                 key.objectid = inode->i_ino;
262                 key.offset = dir->i_ino;
263                 key.type = BTRFS_INODE_REF_KEY;
264         }
265
266         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
267         if (ret < 0) {
268                 btrfs_free_path(path);
269                 return ret;
270         } else if (ret > 0) {
271                 if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
272                         path->slots[0]--;
273                 } else {
274                         btrfs_free_path(path);
275                         return -ENOENT;
276                 }
277         }
278         leaf = path->nodes[0];
279
280         if (inode->i_ino == BTRFS_FIRST_FREE_OBJECTID) {
281                rref = btrfs_item_ptr(leaf, path->slots[0],
282                                      struct btrfs_root_ref);
283                name_ptr = (unsigned long)(rref + 1);
284                name_len = btrfs_root_ref_name_len(leaf, rref);
285         } else {
286                 iref = btrfs_item_ptr(leaf, path->slots[0],
287                                       struct btrfs_inode_ref);
288                 name_ptr = (unsigned long)(iref + 1);
289                 name_len = btrfs_inode_ref_name_len(leaf, iref);
290         }
291
292         read_extent_buffer(leaf, name, name_ptr, name_len);
293         btrfs_free_path(path);
294
295         /*
296          * have to add the null termination to make sure that reconnect_path
297          * gets the right len for strlen
298          */
299         name[name_len] = '\0';
300
301         return 0;
302 }
303
304 const struct export_operations btrfs_export_ops = {
305         .encode_fh      = btrfs_encode_fh,
306         .fh_to_dentry   = btrfs_fh_to_dentry,
307         .fh_to_parent   = btrfs_fh_to_parent,
308         .get_parent     = btrfs_get_parent,
309         .get_name       = btrfs_get_name,
310 };