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_I(inode)->root->root_key.objectid; 38 fid->gen = inode->i_generation; 39 40 if (parent) { 41 u64 parent_root_id; 42 43 fid->parent_objectid = BTRFS_I(parent)->location.objectid; 44 fid->parent_gen = parent->i_generation; 45 parent_root_id = BTRFS_I(parent)->root->root_key.objectid; 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 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(sb, objectid, root); 88 btrfs_put_root(root); 89 if (IS_ERR(inode)) 90 return ERR_CAST(inode); 91 92 if (generation != 0 && generation != inode->i_generation) { 93 iput(inode); 94 return ERR_PTR(-ESTALE); 95 } 96 97 return d_obtain_alias(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 inode *dir = d_inode(child); 149 struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); 150 struct btrfs_root *root = BTRFS_I(dir)->root; 151 struct btrfs_path *path; 152 struct extent_buffer *leaf; 153 struct btrfs_root_ref *ref; 154 struct btrfs_key key; 155 struct btrfs_key found_key; 156 int ret; 157 158 path = btrfs_alloc_path(); 159 if (!path) 160 return ERR_PTR(-ENOMEM); 161 162 if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) { 163 key.objectid = root->root_key.objectid; 164 key.type = BTRFS_ROOT_BACKREF_KEY; 165 key.offset = (u64)-1; 166 root = fs_info->tree_root; 167 } else { 168 key.objectid = btrfs_ino(BTRFS_I(dir)); 169 key.type = BTRFS_INODE_REF_KEY; 170 key.offset = (u64)-1; 171 } 172 173 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 174 if (ret < 0) 175 goto fail; 176 if (ret == 0) { 177 /* 178 * Key with offset of -1 found, there would have to exist an 179 * inode with such number or a root with such id. 180 */ 181 ret = -EUCLEAN; 182 goto fail; 183 } 184 185 if (path->slots[0] == 0) { 186 ret = -ENOENT; 187 goto fail; 188 } 189 190 path->slots[0]--; 191 leaf = path->nodes[0]; 192 193 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 194 if (found_key.objectid != key.objectid || found_key.type != key.type) { 195 ret = -ENOENT; 196 goto fail; 197 } 198 199 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 200 ref = btrfs_item_ptr(leaf, path->slots[0], 201 struct btrfs_root_ref); 202 key.objectid = btrfs_root_ref_dirid(leaf, ref); 203 } else { 204 key.objectid = found_key.offset; 205 } 206 btrfs_free_path(path); 207 208 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 209 return btrfs_get_dentry(fs_info->sb, key.objectid, 210 found_key.offset, 0); 211 } 212 213 return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root)); 214 fail: 215 btrfs_free_path(path); 216 return ERR_PTR(ret); 217 } 218 219 static int btrfs_get_name(struct dentry *parent, char *name, 220 struct dentry *child) 221 { 222 struct inode *inode = d_inode(child); 223 struct inode *dir = d_inode(parent); 224 struct btrfs_fs_info *fs_info = inode_to_fs_info(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 (!S_ISDIR(dir->i_mode)) 237 return -EINVAL; 238 239 ino = btrfs_ino(BTRFS_I(inode)); 240 241 path = btrfs_alloc_path(); 242 if (!path) 243 return -ENOMEM; 244 245 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 246 key.objectid = BTRFS_I(inode)->root->root_key.objectid; 247 key.type = BTRFS_ROOT_BACKREF_KEY; 248 key.offset = (u64)-1; 249 root = fs_info->tree_root; 250 } else { 251 key.objectid = ino; 252 key.offset = btrfs_ino(BTRFS_I(dir)); 253 key.type = BTRFS_INODE_REF_KEY; 254 } 255 256 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 257 if (ret < 0) { 258 btrfs_free_path(path); 259 return ret; 260 } else if (ret > 0) { 261 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 262 path->slots[0]--; 263 } else { 264 btrfs_free_path(path); 265 return -ENOENT; 266 } 267 } 268 leaf = path->nodes[0]; 269 270 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 271 rref = btrfs_item_ptr(leaf, path->slots[0], 272 struct btrfs_root_ref); 273 name_ptr = (unsigned long)(rref + 1); 274 name_len = btrfs_root_ref_name_len(leaf, rref); 275 } else { 276 iref = btrfs_item_ptr(leaf, path->slots[0], 277 struct btrfs_inode_ref); 278 name_ptr = (unsigned long)(iref + 1); 279 name_len = btrfs_inode_ref_name_len(leaf, iref); 280 } 281 282 read_extent_buffer(leaf, name, name_ptr, name_len); 283 btrfs_free_path(path); 284 285 /* 286 * have to add the null termination to make sure that reconnect_path 287 * gets the right len for strlen 288 */ 289 name[name_len] = '\0'; 290 291 return 0; 292 } 293 294 const struct export_operations btrfs_export_ops = { 295 .encode_fh = btrfs_encode_fh, 296 .fh_to_dentry = btrfs_fh_to_dentry, 297 .fh_to_parent = btrfs_fh_to_parent, 298 .get_parent = btrfs_get_parent, 299 .get_name = btrfs_get_name, 300 }; 301