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 #include "accessors.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; 176 177 BUG_ON(ret == 0); /* Key with offset of -1 found */ 178 if (path->slots[0] == 0) { 179 ret = -ENOENT; 180 goto fail; 181 } 182 183 path->slots[0]--; 184 leaf = path->nodes[0]; 185 186 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 187 if (found_key.objectid != key.objectid || found_key.type != key.type) { 188 ret = -ENOENT; 189 goto fail; 190 } 191 192 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 193 ref = btrfs_item_ptr(leaf, path->slots[0], 194 struct btrfs_root_ref); 195 key.objectid = btrfs_root_ref_dirid(leaf, ref); 196 } else { 197 key.objectid = found_key.offset; 198 } 199 btrfs_free_path(path); 200 201 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 202 return btrfs_get_dentry(fs_info->sb, key.objectid, 203 found_key.offset, 0); 204 } 205 206 return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root)); 207 fail: 208 btrfs_free_path(path); 209 return ERR_PTR(ret); 210 } 211 212 static int btrfs_get_name(struct dentry *parent, char *name, 213 struct dentry *child) 214 { 215 struct inode *inode = d_inode(child); 216 struct inode *dir = d_inode(parent); 217 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 218 struct btrfs_path *path; 219 struct btrfs_root *root = BTRFS_I(dir)->root; 220 struct btrfs_inode_ref *iref; 221 struct btrfs_root_ref *rref; 222 struct extent_buffer *leaf; 223 unsigned long name_ptr; 224 struct btrfs_key key; 225 int name_len; 226 int ret; 227 u64 ino; 228 229 if (!S_ISDIR(dir->i_mode)) 230 return -EINVAL; 231 232 ino = btrfs_ino(BTRFS_I(inode)); 233 234 path = btrfs_alloc_path(); 235 if (!path) 236 return -ENOMEM; 237 238 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 239 key.objectid = BTRFS_I(inode)->root->root_key.objectid; 240 key.type = BTRFS_ROOT_BACKREF_KEY; 241 key.offset = (u64)-1; 242 root = fs_info->tree_root; 243 } else { 244 key.objectid = ino; 245 key.offset = btrfs_ino(BTRFS_I(dir)); 246 key.type = BTRFS_INODE_REF_KEY; 247 } 248 249 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 250 if (ret < 0) { 251 btrfs_free_path(path); 252 return ret; 253 } else if (ret > 0) { 254 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 255 path->slots[0]--; 256 } else { 257 btrfs_free_path(path); 258 return -ENOENT; 259 } 260 } 261 leaf = path->nodes[0]; 262 263 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 264 rref = btrfs_item_ptr(leaf, path->slots[0], 265 struct btrfs_root_ref); 266 name_ptr = (unsigned long)(rref + 1); 267 name_len = btrfs_root_ref_name_len(leaf, rref); 268 } else { 269 iref = btrfs_item_ptr(leaf, path->slots[0], 270 struct btrfs_inode_ref); 271 name_ptr = (unsigned long)(iref + 1); 272 name_len = btrfs_inode_ref_name_len(leaf, iref); 273 } 274 275 read_extent_buffer(leaf, name, name_ptr, name_len); 276 btrfs_free_path(path); 277 278 /* 279 * have to add the null termination to make sure that reconnect_path 280 * gets the right len for strlen 281 */ 282 name[name_len] = '\0'; 283 284 return 0; 285 } 286 287 const struct export_operations btrfs_export_ops = { 288 .encode_fh = btrfs_encode_fh, 289 .fh_to_dentry = btrfs_fh_to_dentry, 290 .fh_to_parent = btrfs_fh_to_parent, 291 .get_parent = btrfs_get_parent, 292 .get_name = btrfs_get_name, 293 }; 294