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 inode *inode, u32 *fh, int *max_len, 17 struct inode *parent) 18 { 19 struct btrfs_fid *fid = (struct btrfs_fid *)fh; 20 int len = *max_len; 21 int type; 22 23 if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) { 24 *max_len = BTRFS_FID_SIZE_CONNECTABLE; 25 return 255; 26 } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) { 27 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE; 28 return 255; 29 } 30 31 len = BTRFS_FID_SIZE_NON_CONNECTABLE; 32 type = FILEID_BTRFS_WITHOUT_PARENT; 33 34 fid->objectid = btrfs_ino(inode); 35 fid->root_objectid = BTRFS_I(inode)->root->objectid; 36 fid->gen = inode->i_generation; 37 38 if (parent) { 39 u64 parent_root_id; 40 41 fid->parent_objectid = BTRFS_I(parent)->location.objectid; 42 fid->parent_gen = parent->i_generation; 43 parent_root_id = BTRFS_I(parent)->root->objectid; 44 45 if (parent_root_id != fid->root_objectid) { 46 fid->parent_root_objectid = parent_root_id; 47 len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; 48 type = FILEID_BTRFS_WITH_PARENT_ROOT; 49 } else { 50 len = BTRFS_FID_SIZE_CONNECTABLE; 51 type = FILEID_BTRFS_WITH_PARENT; 52 } 53 } 54 55 *max_len = len; 56 return type; 57 } 58 59 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, 60 u64 root_objectid, u32 generation, 61 int check_generation) 62 { 63 struct btrfs_fs_info *fs_info = btrfs_sb(sb); 64 struct btrfs_root *root; 65 struct inode *inode; 66 struct btrfs_key key; 67 int index; 68 int err = 0; 69 70 if (objectid < BTRFS_FIRST_FREE_OBJECTID) 71 return ERR_PTR(-ESTALE); 72 73 key.objectid = root_objectid; 74 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY); 75 key.offset = (u64)-1; 76 77 index = srcu_read_lock(&fs_info->subvol_srcu); 78 79 root = btrfs_read_fs_root_no_name(fs_info, &key); 80 if (IS_ERR(root)) { 81 err = PTR_ERR(root); 82 goto fail; 83 } 84 85 if (btrfs_root_refs(&root->root_item) == 0) { 86 err = -ENOENT; 87 goto fail; 88 } 89 90 key.objectid = objectid; 91 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY); 92 key.offset = 0; 93 94 inode = btrfs_iget(sb, &key, root, NULL); 95 if (IS_ERR(inode)) { 96 err = PTR_ERR(inode); 97 goto fail; 98 } 99 100 srcu_read_unlock(&fs_info->subvol_srcu, index); 101 102 if (check_generation && generation != inode->i_generation) { 103 iput(inode); 104 return ERR_PTR(-ESTALE); 105 } 106 107 return d_obtain_alias(inode); 108 fail: 109 srcu_read_unlock(&fs_info->subvol_srcu, index); 110 return ERR_PTR(err); 111 } 112 113 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 114 int fh_len, int fh_type) 115 { 116 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 117 u64 objectid, root_objectid; 118 u32 generation; 119 120 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 121 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE) 122 return NULL; 123 root_objectid = fid->root_objectid; 124 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 125 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) 126 return NULL; 127 root_objectid = fid->parent_root_objectid; 128 } else 129 return NULL; 130 131 objectid = fid->parent_objectid; 132 generation = fid->parent_gen; 133 134 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 135 } 136 137 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 138 int fh_len, int fh_type) 139 { 140 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 141 u64 objectid, root_objectid; 142 u32 generation; 143 144 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 145 fh_len != BTRFS_FID_SIZE_CONNECTABLE) && 146 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 147 fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 148 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 149 fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE)) 150 return NULL; 151 152 objectid = fid->objectid; 153 root_objectid = fid->root_objectid; 154 generation = fid->gen; 155 156 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 157 } 158 159 static struct dentry *btrfs_get_parent(struct dentry *child) 160 { 161 struct inode *dir = child->d_inode; 162 struct btrfs_root *root = BTRFS_I(dir)->root; 163 struct btrfs_path *path; 164 struct extent_buffer *leaf; 165 struct btrfs_root_ref *ref; 166 struct btrfs_key key; 167 struct btrfs_key found_key; 168 int ret; 169 170 path = btrfs_alloc_path(); 171 if (!path) 172 return ERR_PTR(-ENOMEM); 173 174 if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) { 175 key.objectid = root->root_key.objectid; 176 key.type = BTRFS_ROOT_BACKREF_KEY; 177 key.offset = (u64)-1; 178 root = root->fs_info->tree_root; 179 } else { 180 key.objectid = btrfs_ino(dir); 181 key.type = BTRFS_INODE_REF_KEY; 182 key.offset = (u64)-1; 183 } 184 185 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 186 if (ret < 0) 187 goto fail; 188 189 BUG_ON(ret == 0); /* Key with offset of -1 found */ 190 if (path->slots[0] == 0) { 191 ret = -ENOENT; 192 goto fail; 193 } 194 195 path->slots[0]--; 196 leaf = path->nodes[0]; 197 198 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 199 if (found_key.objectid != key.objectid || found_key.type != key.type) { 200 ret = -ENOENT; 201 goto fail; 202 } 203 204 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 205 ref = btrfs_item_ptr(leaf, path->slots[0], 206 struct btrfs_root_ref); 207 key.objectid = btrfs_root_ref_dirid(leaf, ref); 208 } else { 209 key.objectid = found_key.offset; 210 } 211 btrfs_free_path(path); 212 213 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 214 return btrfs_get_dentry(root->fs_info->sb, key.objectid, 215 found_key.offset, 0, 0); 216 } 217 218 key.type = BTRFS_INODE_ITEM_KEY; 219 key.offset = 0; 220 return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL)); 221 fail: 222 btrfs_free_path(path); 223 return ERR_PTR(ret); 224 } 225 226 static int btrfs_get_name(struct dentry *parent, char *name, 227 struct dentry *child) 228 { 229 struct inode *inode = child->d_inode; 230 struct inode *dir = parent->d_inode; 231 struct btrfs_path *path; 232 struct btrfs_root *root = BTRFS_I(dir)->root; 233 struct btrfs_inode_ref *iref; 234 struct btrfs_root_ref *rref; 235 struct extent_buffer *leaf; 236 unsigned long name_ptr; 237 struct btrfs_key key; 238 int name_len; 239 int ret; 240 u64 ino; 241 242 if (!dir || !inode) 243 return -EINVAL; 244 245 if (!S_ISDIR(dir->i_mode)) 246 return -EINVAL; 247 248 ino = btrfs_ino(inode); 249 250 path = btrfs_alloc_path(); 251 if (!path) 252 return -ENOMEM; 253 path->leave_spinning = 1; 254 255 if (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 = ino; 262 key.offset = btrfs_ino(dir); 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 (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 (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 }; 311