device-dax/kmem: use struct_size()
[linux-2.6-microblaze.git] / fs / btrfs / export.c
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 "print-tree.h"
9 #include "export.h"
10
11 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \
12                                                  parent_objectid) / 4)
13 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \
14                                              parent_root_objectid) / 4)
15 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4)
16
17 static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
18                            struct inode *parent)
19 {
20         struct btrfs_fid *fid = (struct btrfs_fid *)fh;
21         int len = *max_len;
22         int type;
23
24         if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) {
25                 *max_len = BTRFS_FID_SIZE_CONNECTABLE;
26                 return FILEID_INVALID;
27         } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) {
28                 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE;
29                 return FILEID_INVALID;
30         }
31
32         len  = BTRFS_FID_SIZE_NON_CONNECTABLE;
33         type = FILEID_BTRFS_WITHOUT_PARENT;
34
35         fid->objectid = btrfs_ino(BTRFS_I(inode));
36         fid->root_objectid = BTRFS_I(inode)->root->root_key.objectid;
37         fid->gen = inode->i_generation;
38
39         if (parent) {
40                 u64 parent_root_id;
41
42                 fid->parent_objectid = BTRFS_I(parent)->location.objectid;
43                 fid->parent_gen = parent->i_generation;
44                 parent_root_id = BTRFS_I(parent)->root->root_key.objectid;
45
46                 if (parent_root_id != fid->root_objectid) {
47                         fid->parent_root_objectid = parent_root_id;
48                         len = BTRFS_FID_SIZE_CONNECTABLE_ROOT;
49                         type = FILEID_BTRFS_WITH_PARENT_ROOT;
50                 } else {
51                         len = BTRFS_FID_SIZE_CONNECTABLE;
52                         type = FILEID_BTRFS_WITH_PARENT;
53                 }
54         }
55
56         *max_len = len;
57         return type;
58 }
59
60 struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid,
61                                 u64 root_objectid, u32 generation,
62                                 int check_generation)
63 {
64         struct btrfs_fs_info *fs_info = btrfs_sb(sb);
65         struct btrfs_root *root;
66         struct inode *inode;
67
68         if (objectid < BTRFS_FIRST_FREE_OBJECTID)
69                 return ERR_PTR(-ESTALE);
70
71         root = btrfs_get_fs_root(fs_info, root_objectid, true);
72         if (IS_ERR(root))
73                 return ERR_CAST(root);
74
75         inode = btrfs_iget(sb, objectid, root);
76         btrfs_put_root(root);
77         if (IS_ERR(inode))
78                 return ERR_CAST(inode);
79
80         if (check_generation && generation != inode->i_generation) {
81                 iput(inode);
82                 return ERR_PTR(-ESTALE);
83         }
84
85         return d_obtain_alias(inode);
86 }
87
88 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh,
89                                          int fh_len, int fh_type)
90 {
91         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
92         u64 objectid, root_objectid;
93         u32 generation;
94
95         if (fh_type == FILEID_BTRFS_WITH_PARENT) {
96                 if (fh_len <  BTRFS_FID_SIZE_CONNECTABLE)
97                         return NULL;
98                 root_objectid = fid->root_objectid;
99         } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) {
100                 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT)
101                         return NULL;
102                 root_objectid = fid->parent_root_objectid;
103         } else
104                 return NULL;
105
106         objectid = fid->parent_objectid;
107         generation = fid->parent_gen;
108
109         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
110 }
111
112 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh,
113                                          int fh_len, int fh_type)
114 {
115         struct btrfs_fid *fid = (struct btrfs_fid *) fh;
116         u64 objectid, root_objectid;
117         u32 generation;
118
119         if ((fh_type != FILEID_BTRFS_WITH_PARENT ||
120              fh_len < BTRFS_FID_SIZE_CONNECTABLE) &&
121             (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT ||
122              fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) &&
123             (fh_type != FILEID_BTRFS_WITHOUT_PARENT ||
124              fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE))
125                 return NULL;
126
127         objectid = fid->objectid;
128         root_objectid = fid->root_objectid;
129         generation = fid->gen;
130
131         return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1);
132 }
133
134 struct dentry *btrfs_get_parent(struct dentry *child)
135 {
136         struct inode *dir = d_inode(child);
137         struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb);
138         struct btrfs_root *root = BTRFS_I(dir)->root;
139         struct btrfs_path *path;
140         struct extent_buffer *leaf;
141         struct btrfs_root_ref *ref;
142         struct btrfs_key key;
143         struct btrfs_key found_key;
144         int ret;
145
146         path = btrfs_alloc_path();
147         if (!path)
148                 return ERR_PTR(-ENOMEM);
149
150         if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) {
151                 key.objectid = root->root_key.objectid;
152                 key.type = BTRFS_ROOT_BACKREF_KEY;
153                 key.offset = (u64)-1;
154                 root = fs_info->tree_root;
155         } else {
156                 key.objectid = btrfs_ino(BTRFS_I(dir));
157                 key.type = BTRFS_INODE_REF_KEY;
158                 key.offset = (u64)-1;
159         }
160
161         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
162         if (ret < 0)
163                 goto fail;
164
165         BUG_ON(ret == 0); /* Key with offset of -1 found */
166         if (path->slots[0] == 0) {
167                 ret = -ENOENT;
168                 goto fail;
169         }
170
171         path->slots[0]--;
172         leaf = path->nodes[0];
173
174         btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
175         if (found_key.objectid != key.objectid || found_key.type != key.type) {
176                 ret = -ENOENT;
177                 goto fail;
178         }
179
180         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
181                 ref = btrfs_item_ptr(leaf, path->slots[0],
182                                      struct btrfs_root_ref);
183                 key.objectid = btrfs_root_ref_dirid(leaf, ref);
184         } else {
185                 key.objectid = found_key.offset;
186         }
187         btrfs_free_path(path);
188
189         if (found_key.type == BTRFS_ROOT_BACKREF_KEY) {
190                 return btrfs_get_dentry(fs_info->sb, key.objectid,
191                                         found_key.offset, 0, 0);
192         }
193
194         return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root));
195 fail:
196         btrfs_free_path(path);
197         return ERR_PTR(ret);
198 }
199
200 static int btrfs_get_name(struct dentry *parent, char *name,
201                           struct dentry *child)
202 {
203         struct inode *inode = d_inode(child);
204         struct inode *dir = d_inode(parent);
205         struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
206         struct btrfs_path *path;
207         struct btrfs_root *root = BTRFS_I(dir)->root;
208         struct btrfs_inode_ref *iref;
209         struct btrfs_root_ref *rref;
210         struct extent_buffer *leaf;
211         unsigned long name_ptr;
212         struct btrfs_key key;
213         int name_len;
214         int ret;
215         u64 ino;
216
217         if (!S_ISDIR(dir->i_mode))
218                 return -EINVAL;
219
220         ino = btrfs_ino(BTRFS_I(inode));
221
222         path = btrfs_alloc_path();
223         if (!path)
224                 return -ENOMEM;
225         path->leave_spinning = 1;
226
227         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
228                 key.objectid = BTRFS_I(inode)->root->root_key.objectid;
229                 key.type = BTRFS_ROOT_BACKREF_KEY;
230                 key.offset = (u64)-1;
231                 root = fs_info->tree_root;
232         } else {
233                 key.objectid = ino;
234                 key.offset = btrfs_ino(BTRFS_I(dir));
235                 key.type = BTRFS_INODE_REF_KEY;
236         }
237
238         ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
239         if (ret < 0) {
240                 btrfs_free_path(path);
241                 return ret;
242         } else if (ret > 0) {
243                 if (ino == BTRFS_FIRST_FREE_OBJECTID) {
244                         path->slots[0]--;
245                 } else {
246                         btrfs_free_path(path);
247                         return -ENOENT;
248                 }
249         }
250         leaf = path->nodes[0];
251
252         if (ino == BTRFS_FIRST_FREE_OBJECTID) {
253                 rref = btrfs_item_ptr(leaf, path->slots[0],
254                                      struct btrfs_root_ref);
255                 name_ptr = (unsigned long)(rref + 1);
256                 name_len = btrfs_root_ref_name_len(leaf, rref);
257         } else {
258                 iref = btrfs_item_ptr(leaf, path->slots[0],
259                                       struct btrfs_inode_ref);
260                 name_ptr = (unsigned long)(iref + 1);
261                 name_len = btrfs_inode_ref_name_len(leaf, iref);
262         }
263
264         read_extent_buffer(leaf, name, name_ptr, name_len);
265         btrfs_free_path(path);
266
267         /*
268          * have to add the null termination to make sure that reconnect_path
269          * gets the right len for strlen
270          */
271         name[name_len] = '\0';
272
273         return 0;
274 }
275
276 const struct export_operations btrfs_export_ops = {
277         .encode_fh      = btrfs_encode_fh,
278         .fh_to_dentry   = btrfs_fh_to_dentry,
279         .fh_to_parent   = btrfs_fh_to_parent,
280         .get_parent     = btrfs_get_parent,
281         .get_name       = btrfs_get_name,
282 };