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 "export.h" 9 #include "accessors.h" 10 #include "super.h" 11 12 #define BTRFS_FID_SIZE_NON_CONNECTABLE (offsetof(struct btrfs_fid, \ 13 parent_objectid) / 4) 14 #define BTRFS_FID_SIZE_CONNECTABLE (offsetof(struct btrfs_fid, \ 15 parent_root_objectid) / 4) 16 #define BTRFS_FID_SIZE_CONNECTABLE_ROOT (sizeof(struct btrfs_fid) / 4) 17 18 static int btrfs_encode_fh(struct inode *inode, u32 *fh, int *max_len, 19 struct inode *parent) 20 { 21 struct btrfs_fid *fid = (struct btrfs_fid *)fh; 22 int len = *max_len; 23 int type; 24 25 if (parent && (len < BTRFS_FID_SIZE_CONNECTABLE)) { 26 *max_len = BTRFS_FID_SIZE_CONNECTABLE; 27 return FILEID_INVALID; 28 } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) { 29 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE; 30 return FILEID_INVALID; 31 } 32 33 len = BTRFS_FID_SIZE_NON_CONNECTABLE; 34 type = FILEID_BTRFS_WITHOUT_PARENT; 35 36 fid->objectid = btrfs_ino(BTRFS_I(inode)); 37 fid->root_objectid = btrfs_root_id(BTRFS_I(inode)->root); 38 fid->gen = inode->i_generation; 39 40 if (parent) { 41 u64 parent_root_id; 42 43 fid->parent_objectid = btrfs_ino(BTRFS_I(parent)); 44 fid->parent_gen = parent->i_generation; 45 parent_root_id = btrfs_root_id(BTRFS_I(parent)->root); 46 47 if (parent_root_id != fid->root_objectid) { 48 fid->parent_root_objectid = parent_root_id; 49 len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; 50 type = FILEID_BTRFS_WITH_PARENT_ROOT; 51 } else { 52 len = BTRFS_FID_SIZE_CONNECTABLE; 53 type = FILEID_BTRFS_WITH_PARENT; 54 } 55 } 56 57 *max_len = len; 58 return type; 59 } 60 61 /* 62 * Read dentry of inode with @objectid from filesystem root @root_objectid. 63 * 64 * @sb: the filesystem super block 65 * @objectid: inode objectid 66 * @root_objectid: object id of the subvolume root where to look up the inode 67 * @generation: optional, if not zero, verify that the found inode 68 * generation matches 69 * 70 * Return dentry alias for the inode, otherwise an error. In case the 71 * generation does not match return ESTALE. 72 */ 73 struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, 74 u64 root_objectid, u64 generation) 75 { 76 struct btrfs_fs_info *fs_info = btrfs_sb(sb); 77 struct btrfs_root *root; 78 struct btrfs_inode *inode; 79 80 if (objectid < BTRFS_FIRST_FREE_OBJECTID) 81 return ERR_PTR(-ESTALE); 82 83 root = btrfs_get_fs_root(fs_info, root_objectid, true); 84 if (IS_ERR(root)) 85 return ERR_CAST(root); 86 87 inode = btrfs_iget(objectid, root); 88 btrfs_put_root(root); 89 if (IS_ERR(inode)) 90 return ERR_CAST(inode); 91 92 if (generation != 0 && generation != inode->vfs_inode.i_generation) { 93 iput(&inode->vfs_inode); 94 return ERR_PTR(-ESTALE); 95 } 96 97 return d_obtain_alias(&inode->vfs_inode); 98 } 99 100 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 101 int fh_len, int fh_type) 102 { 103 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 104 u64 objectid, root_objectid; 105 u32 generation; 106 107 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 108 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE) 109 return NULL; 110 root_objectid = fid->root_objectid; 111 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 112 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) 113 return NULL; 114 root_objectid = fid->parent_root_objectid; 115 } else 116 return NULL; 117 118 objectid = fid->parent_objectid; 119 generation = fid->parent_gen; 120 121 return btrfs_get_dentry(sb, objectid, root_objectid, generation); 122 } 123 124 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 125 int fh_len, int fh_type) 126 { 127 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 128 u64 objectid, root_objectid; 129 u32 generation; 130 131 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 132 fh_len < BTRFS_FID_SIZE_CONNECTABLE) && 133 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 134 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 135 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 136 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE)) 137 return NULL; 138 139 objectid = fid->objectid; 140 root_objectid = fid->root_objectid; 141 generation = fid->gen; 142 143 return btrfs_get_dentry(sb, objectid, root_objectid, generation); 144 } 145 146 struct dentry *btrfs_get_parent(struct dentry *child) 147 { 148 struct btrfs_inode *dir = BTRFS_I(d_inode(child)); 149 struct btrfs_inode *inode; 150 struct btrfs_root *root = dir->root; 151 struct btrfs_fs_info *fs_info = root->fs_info; 152 struct btrfs_path *path; 153 struct extent_buffer *leaf; 154 struct btrfs_root_ref *ref; 155 struct btrfs_key key; 156 struct btrfs_key found_key; 157 int ret; 158 159 path = btrfs_alloc_path(); 160 if (!path) 161 return ERR_PTR(-ENOMEM); 162 163 if (btrfs_ino(dir) == BTRFS_FIRST_FREE_OBJECTID) { 164 key.objectid = btrfs_root_id(root); 165 key.type = BTRFS_ROOT_BACKREF_KEY; 166 key.offset = (u64)-1; 167 root = fs_info->tree_root; 168 } else { 169 key.objectid = btrfs_ino(dir); 170 key.type = BTRFS_INODE_REF_KEY; 171 key.offset = (u64)-1; 172 } 173 174 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 175 if (ret < 0) 176 goto fail; 177 if (ret == 0) { 178 /* 179 * Key with offset of -1 found, there would have to exist an 180 * inode with such number or a root with such id. 181 */ 182 ret = -EUCLEAN; 183 goto fail; 184 } 185 186 if (path->slots[0] == 0) { 187 ret = -ENOENT; 188 goto fail; 189 } 190 191 path->slots[0]--; 192 leaf = path->nodes[0]; 193 194 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 195 if (found_key.objectid != key.objectid || found_key.type != key.type) { 196 ret = -ENOENT; 197 goto fail; 198 } 199 200 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 201 ref = btrfs_item_ptr(leaf, path->slots[0], 202 struct btrfs_root_ref); 203 key.objectid = btrfs_root_ref_dirid(leaf, ref); 204 } else { 205 key.objectid = found_key.offset; 206 } 207 btrfs_free_path(path); 208 209 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 210 return btrfs_get_dentry(fs_info->sb, key.objectid, 211 found_key.offset, 0); 212 } 213 214 inode = btrfs_iget(key.objectid, root); 215 if (IS_ERR(inode)) 216 return ERR_CAST(inode); 217 218 return d_obtain_alias(&inode->vfs_inode); 219 fail: 220 btrfs_free_path(path); 221 return ERR_PTR(ret); 222 } 223 224 static int btrfs_get_name(struct dentry *parent, char *name, 225 struct dentry *child) 226 { 227 struct btrfs_inode *inode = BTRFS_I(d_inode(child)); 228 struct btrfs_inode *dir = BTRFS_I(d_inode(parent)); 229 struct btrfs_root *root = dir->root; 230 struct btrfs_fs_info *fs_info = root->fs_info; 231 BTRFS_PATH_AUTO_FREE(path); 232 struct btrfs_inode_ref *iref; 233 struct btrfs_root_ref *rref; 234 struct extent_buffer *leaf; 235 unsigned long name_ptr; 236 struct btrfs_key key; 237 int name_len; 238 int ret; 239 u64 ino; 240 241 if (!S_ISDIR(dir->vfs_inode.i_mode)) 242 return -EINVAL; 243 244 ino = btrfs_ino(inode); 245 246 path = btrfs_alloc_path(); 247 if (!path) 248 return -ENOMEM; 249 250 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 251 key.objectid = btrfs_root_id(inode->root); 252 key.type = BTRFS_ROOT_BACKREF_KEY; 253 key.offset = (u64)-1; 254 root = fs_info->tree_root; 255 } else { 256 key.objectid = ino; 257 key.type = BTRFS_INODE_REF_KEY; 258 key.offset = btrfs_ino(dir); 259 } 260 261 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 262 if (ret < 0) { 263 return ret; 264 } else if (ret > 0) { 265 if (ino == BTRFS_FIRST_FREE_OBJECTID) 266 path->slots[0]--; 267 else 268 return -ENOENT; 269 } 270 leaf = path->nodes[0]; 271 272 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 273 rref = btrfs_item_ptr(leaf, path->slots[0], 274 struct btrfs_root_ref); 275 name_ptr = (unsigned long)(rref + 1); 276 name_len = btrfs_root_ref_name_len(leaf, rref); 277 } else { 278 iref = btrfs_item_ptr(leaf, path->slots[0], 279 struct btrfs_inode_ref); 280 name_ptr = (unsigned long)(iref + 1); 281 name_len = btrfs_inode_ref_name_len(leaf, iref); 282 } 283 284 read_extent_buffer(leaf, name, name_ptr, name_len); 285 286 /* 287 * have to add the null termination to make sure that reconnect_path 288 * gets the right len for strlen 289 */ 290 name[name_len] = '\0'; 291 292 return 0; 293 } 294 295 const struct export_operations btrfs_export_ops = { 296 .encode_fh = btrfs_encode_fh, 297 .fh_to_dentry = btrfs_fh_to_dentry, 298 .fh_to_parent = btrfs_fh_to_parent, 299 .get_parent = btrfs_get_parent, 300 .get_name = btrfs_get_name, 301 }; 302