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 struct btrfs_key key; 68 69 if (objectid < BTRFS_FIRST_FREE_OBJECTID) 70 return ERR_PTR(-ESTALE); 71 72 key.objectid = root_objectid; 73 key.type = BTRFS_ROOT_ITEM_KEY; 74 key.offset = (u64)-1; 75 76 root = btrfs_get_fs_root(fs_info, &key, true); 77 if (IS_ERR(root)) 78 return ERR_CAST(root); 79 80 key.objectid = objectid; 81 key.type = BTRFS_INODE_ITEM_KEY; 82 key.offset = 0; 83 84 inode = btrfs_iget(sb, &key, root); 85 btrfs_put_root(root); 86 if (IS_ERR(inode)) 87 return ERR_CAST(inode); 88 89 if (check_generation && generation != inode->i_generation) { 90 iput(inode); 91 return ERR_PTR(-ESTALE); 92 } 93 94 return d_obtain_alias(inode); 95 } 96 97 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 98 int fh_len, int fh_type) 99 { 100 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 101 u64 objectid, root_objectid; 102 u32 generation; 103 104 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 105 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE) 106 return NULL; 107 root_objectid = fid->root_objectid; 108 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 109 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) 110 return NULL; 111 root_objectid = fid->parent_root_objectid; 112 } else 113 return NULL; 114 115 objectid = fid->parent_objectid; 116 generation = fid->parent_gen; 117 118 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 119 } 120 121 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 122 int fh_len, int fh_type) 123 { 124 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 125 u64 objectid, root_objectid; 126 u32 generation; 127 128 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 129 fh_len < BTRFS_FID_SIZE_CONNECTABLE) && 130 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 131 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 132 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 133 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE)) 134 return NULL; 135 136 objectid = fid->objectid; 137 root_objectid = fid->root_objectid; 138 generation = fid->gen; 139 140 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 141 } 142 143 struct dentry *btrfs_get_parent(struct dentry *child) 144 { 145 struct inode *dir = d_inode(child); 146 struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); 147 struct btrfs_root *root = BTRFS_I(dir)->root; 148 struct btrfs_path *path; 149 struct extent_buffer *leaf; 150 struct btrfs_root_ref *ref; 151 struct btrfs_key key; 152 struct btrfs_key found_key; 153 int ret; 154 155 path = btrfs_alloc_path(); 156 if (!path) 157 return ERR_PTR(-ENOMEM); 158 159 if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) { 160 key.objectid = root->root_key.objectid; 161 key.type = BTRFS_ROOT_BACKREF_KEY; 162 key.offset = (u64)-1; 163 root = fs_info->tree_root; 164 } else { 165 key.objectid = btrfs_ino(BTRFS_I(dir)); 166 key.type = BTRFS_INODE_REF_KEY; 167 key.offset = (u64)-1; 168 } 169 170 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 171 if (ret < 0) 172 goto fail; 173 174 BUG_ON(ret == 0); /* Key with offset of -1 found */ 175 if (path->slots[0] == 0) { 176 ret = -ENOENT; 177 goto fail; 178 } 179 180 path->slots[0]--; 181 leaf = path->nodes[0]; 182 183 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 184 if (found_key.objectid != key.objectid || found_key.type != key.type) { 185 ret = -ENOENT; 186 goto fail; 187 } 188 189 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 190 ref = btrfs_item_ptr(leaf, path->slots[0], 191 struct btrfs_root_ref); 192 key.objectid = btrfs_root_ref_dirid(leaf, ref); 193 } else { 194 key.objectid = found_key.offset; 195 } 196 btrfs_free_path(path); 197 198 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 199 return btrfs_get_dentry(fs_info->sb, key.objectid, 200 found_key.offset, 0, 0); 201 } 202 203 key.type = BTRFS_INODE_ITEM_KEY; 204 key.offset = 0; 205 return d_obtain_alias(btrfs_iget(fs_info->sb, &key, root)); 206 fail: 207 btrfs_free_path(path); 208 return ERR_PTR(ret); 209 } 210 211 static int btrfs_get_name(struct dentry *parent, char *name, 212 struct dentry *child) 213 { 214 struct inode *inode = d_inode(child); 215 struct inode *dir = d_inode(parent); 216 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 217 struct btrfs_path *path; 218 struct btrfs_root *root = BTRFS_I(dir)->root; 219 struct btrfs_inode_ref *iref; 220 struct btrfs_root_ref *rref; 221 struct extent_buffer *leaf; 222 unsigned long name_ptr; 223 struct btrfs_key key; 224 int name_len; 225 int ret; 226 u64 ino; 227 228 if (!S_ISDIR(dir->i_mode)) 229 return -EINVAL; 230 231 ino = btrfs_ino(BTRFS_I(inode)); 232 233 path = btrfs_alloc_path(); 234 if (!path) 235 return -ENOMEM; 236 path->leave_spinning = 1; 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