1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/fs.h> 3 #include <linux/types.h> 4 #include "ctree.h" 5 #include "disk-io.h" 6 #include "btrfs_inode.h" 7 #include "print-tree.h" 8 #include "export.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 FILEID_INVALID; 26 } else if (len < BTRFS_FID_SIZE_NON_CONNECTABLE) { 27 *max_len = BTRFS_FID_SIZE_NON_CONNECTABLE; 28 return FILEID_INVALID; 29 } 30 31 len = BTRFS_FID_SIZE_NON_CONNECTABLE; 32 type = FILEID_BTRFS_WITHOUT_PARENT; 33 34 fid->objectid = btrfs_ino(BTRFS_I(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 key.type = 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 key.objectid = objectid; 86 key.type = BTRFS_INODE_ITEM_KEY; 87 key.offset = 0; 88 89 inode = btrfs_iget(sb, &key, root, NULL); 90 if (IS_ERR(inode)) { 91 err = PTR_ERR(inode); 92 goto fail; 93 } 94 95 srcu_read_unlock(&fs_info->subvol_srcu, index); 96 97 if (check_generation && generation != inode->i_generation) { 98 iput(inode); 99 return ERR_PTR(-ESTALE); 100 } 101 102 return d_obtain_alias(inode); 103 fail: 104 srcu_read_unlock(&fs_info->subvol_srcu, index); 105 return ERR_PTR(err); 106 } 107 108 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 109 int fh_len, int fh_type) 110 { 111 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 112 u64 objectid, root_objectid; 113 u32 generation; 114 115 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 116 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE) 117 return NULL; 118 root_objectid = fid->root_objectid; 119 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 120 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) 121 return NULL; 122 root_objectid = fid->parent_root_objectid; 123 } else 124 return NULL; 125 126 objectid = fid->parent_objectid; 127 generation = fid->parent_gen; 128 129 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 130 } 131 132 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 133 int fh_len, int fh_type) 134 { 135 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 136 u64 objectid, root_objectid; 137 u32 generation; 138 139 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 140 fh_len < BTRFS_FID_SIZE_CONNECTABLE) && 141 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 142 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 143 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 144 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE)) 145 return NULL; 146 147 objectid = fid->objectid; 148 root_objectid = fid->root_objectid; 149 generation = fid->gen; 150 151 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 152 } 153 154 static struct dentry *btrfs_get_parent(struct dentry *child) 155 { 156 struct inode *dir = d_inode(child); 157 struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); 158 struct btrfs_root *root = BTRFS_I(dir)->root; 159 struct btrfs_path *path; 160 struct extent_buffer *leaf; 161 struct btrfs_root_ref *ref; 162 struct btrfs_key key; 163 struct btrfs_key found_key; 164 int ret; 165 166 path = btrfs_alloc_path(); 167 if (!path) 168 return ERR_PTR(-ENOMEM); 169 170 if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) { 171 key.objectid = root->root_key.objectid; 172 key.type = BTRFS_ROOT_BACKREF_KEY; 173 key.offset = (u64)-1; 174 root = fs_info->tree_root; 175 } else { 176 key.objectid = btrfs_ino(BTRFS_I(dir)); 177 key.type = BTRFS_INODE_REF_KEY; 178 key.offset = (u64)-1; 179 } 180 181 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 182 if (ret < 0) 183 goto fail; 184 185 BUG_ON(ret == 0); /* Key with offset of -1 found */ 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, 0); 212 } 213 214 key.type = BTRFS_INODE_ITEM_KEY; 215 key.offset = 0; 216 return d_obtain_alias(btrfs_iget(fs_info->sb, &key, root, NULL)); 217 fail: 218 btrfs_free_path(path); 219 return ERR_PTR(ret); 220 } 221 222 static int btrfs_get_name(struct dentry *parent, char *name, 223 struct dentry *child) 224 { 225 struct inode *inode = d_inode(child); 226 struct inode *dir = d_inode(parent); 227 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 228 struct btrfs_path *path; 229 struct btrfs_root *root = BTRFS_I(dir)->root; 230 struct btrfs_inode_ref *iref; 231 struct btrfs_root_ref *rref; 232 struct extent_buffer *leaf; 233 unsigned long name_ptr; 234 struct btrfs_key key; 235 int name_len; 236 int ret; 237 u64 ino; 238 239 if (!S_ISDIR(dir->i_mode)) 240 return -EINVAL; 241 242 ino = btrfs_ino(BTRFS_I(inode)); 243 244 path = btrfs_alloc_path(); 245 if (!path) 246 return -ENOMEM; 247 path->leave_spinning = 1; 248 249 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 250 key.objectid = BTRFS_I(inode)->root->root_key.objectid; 251 key.type = BTRFS_ROOT_BACKREF_KEY; 252 key.offset = (u64)-1; 253 root = fs_info->tree_root; 254 } else { 255 key.objectid = ino; 256 key.offset = btrfs_ino(BTRFS_I(dir)); 257 key.type = BTRFS_INODE_REF_KEY; 258 } 259 260 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 261 if (ret < 0) { 262 btrfs_free_path(path); 263 return ret; 264 } else if (ret > 0) { 265 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 266 path->slots[0]--; 267 } else { 268 btrfs_free_path(path); 269 return -ENOENT; 270 } 271 } 272 leaf = path->nodes[0]; 273 274 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 275 rref = btrfs_item_ptr(leaf, path->slots[0], 276 struct btrfs_root_ref); 277 name_ptr = (unsigned long)(rref + 1); 278 name_len = btrfs_root_ref_name_len(leaf, rref); 279 } else { 280 iref = btrfs_item_ptr(leaf, path->slots[0], 281 struct btrfs_inode_ref); 282 name_ptr = (unsigned long)(iref + 1); 283 name_len = btrfs_inode_ref_name_len(leaf, iref); 284 } 285 286 read_extent_buffer(leaf, name, name_ptr, name_len); 287 btrfs_free_path(path); 288 289 /* 290 * have to add the null termination to make sure that reconnect_path 291 * gets the right len for strlen 292 */ 293 name[name_len] = '\0'; 294 295 return 0; 296 } 297 298 const struct export_operations btrfs_export_ops = { 299 .encode_fh = btrfs_encode_fh, 300 .fh_to_dentry = btrfs_fh_to_dentry, 301 .fh_to_parent = btrfs_fh_to_parent, 302 .get_parent = btrfs_get_parent, 303 .get_name = btrfs_get_name, 304 }; 305