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 68 if (objectid < BTRFS_FIRST_FREE_OBJECTID) 69 return ERR_PTR(-ESTALE); 70 71 root = btrfs_get_fs_root(fs_info, root_objectid, true); 72 if (IS_ERR(root)) 73 return ERR_CAST(root); 74 75 inode = btrfs_iget(sb, objectid, root); 76 btrfs_put_root(root); 77 if (IS_ERR(inode)) 78 return ERR_CAST(inode); 79 80 if (check_generation && generation != inode->i_generation) { 81 iput(inode); 82 return ERR_PTR(-ESTALE); 83 } 84 85 return d_obtain_alias(inode); 86 } 87 88 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 89 int fh_len, int fh_type) 90 { 91 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 92 u64 objectid, root_objectid; 93 u32 generation; 94 95 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 96 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE) 97 return NULL; 98 root_objectid = fid->root_objectid; 99 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 100 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) 101 return NULL; 102 root_objectid = fid->parent_root_objectid; 103 } else 104 return NULL; 105 106 objectid = fid->parent_objectid; 107 generation = fid->parent_gen; 108 109 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 110 } 111 112 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 113 int fh_len, int fh_type) 114 { 115 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 116 u64 objectid, root_objectid; 117 u32 generation; 118 119 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 120 fh_len < BTRFS_FID_SIZE_CONNECTABLE) && 121 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 122 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 123 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 124 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE)) 125 return NULL; 126 127 objectid = fid->objectid; 128 root_objectid = fid->root_objectid; 129 generation = fid->gen; 130 131 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 132 } 133 134 struct dentry *btrfs_get_parent(struct dentry *child) 135 { 136 struct inode *dir = d_inode(child); 137 struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); 138 struct btrfs_root *root = BTRFS_I(dir)->root; 139 struct btrfs_path *path; 140 struct extent_buffer *leaf; 141 struct btrfs_root_ref *ref; 142 struct btrfs_key key; 143 struct btrfs_key found_key; 144 int ret; 145 146 path = btrfs_alloc_path(); 147 if (!path) 148 return ERR_PTR(-ENOMEM); 149 150 if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) { 151 key.objectid = root->root_key.objectid; 152 key.type = BTRFS_ROOT_BACKREF_KEY; 153 key.offset = (u64)-1; 154 root = fs_info->tree_root; 155 } else { 156 key.objectid = btrfs_ino(BTRFS_I(dir)); 157 key.type = BTRFS_INODE_REF_KEY; 158 key.offset = (u64)-1; 159 } 160 161 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 162 if (ret < 0) 163 goto fail; 164 165 BUG_ON(ret == 0); /* Key with offset of -1 found */ 166 if (path->slots[0] == 0) { 167 ret = -ENOENT; 168 goto fail; 169 } 170 171 path->slots[0]--; 172 leaf = path->nodes[0]; 173 174 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 175 if (found_key.objectid != key.objectid || found_key.type != key.type) { 176 ret = -ENOENT; 177 goto fail; 178 } 179 180 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 181 ref = btrfs_item_ptr(leaf, path->slots[0], 182 struct btrfs_root_ref); 183 key.objectid = btrfs_root_ref_dirid(leaf, ref); 184 } else { 185 key.objectid = found_key.offset; 186 } 187 btrfs_free_path(path); 188 189 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 190 return btrfs_get_dentry(fs_info->sb, key.objectid, 191 found_key.offset, 0, 0); 192 } 193 194 return d_obtain_alias(btrfs_iget(fs_info->sb, key.objectid, root)); 195 fail: 196 btrfs_free_path(path); 197 return ERR_PTR(ret); 198 } 199 200 static int btrfs_get_name(struct dentry *parent, char *name, 201 struct dentry *child) 202 { 203 struct inode *inode = d_inode(child); 204 struct inode *dir = d_inode(parent); 205 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 206 struct btrfs_path *path; 207 struct btrfs_root *root = BTRFS_I(dir)->root; 208 struct btrfs_inode_ref *iref; 209 struct btrfs_root_ref *rref; 210 struct extent_buffer *leaf; 211 unsigned long name_ptr; 212 struct btrfs_key key; 213 int name_len; 214 int ret; 215 u64 ino; 216 217 if (!S_ISDIR(dir->i_mode)) 218 return -EINVAL; 219 220 ino = btrfs_ino(BTRFS_I(inode)); 221 222 path = btrfs_alloc_path(); 223 if (!path) 224 return -ENOMEM; 225 path->leave_spinning = 1; 226 227 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 228 key.objectid = BTRFS_I(inode)->root->root_key.objectid; 229 key.type = BTRFS_ROOT_BACKREF_KEY; 230 key.offset = (u64)-1; 231 root = fs_info->tree_root; 232 } else { 233 key.objectid = ino; 234 key.offset = btrfs_ino(BTRFS_I(dir)); 235 key.type = BTRFS_INODE_REF_KEY; 236 } 237 238 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 239 if (ret < 0) { 240 btrfs_free_path(path); 241 return ret; 242 } else if (ret > 0) { 243 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 244 path->slots[0]--; 245 } else { 246 btrfs_free_path(path); 247 return -ENOENT; 248 } 249 } 250 leaf = path->nodes[0]; 251 252 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 253 rref = btrfs_item_ptr(leaf, path->slots[0], 254 struct btrfs_root_ref); 255 name_ptr = (unsigned long)(rref + 1); 256 name_len = btrfs_root_ref_name_len(leaf, rref); 257 } else { 258 iref = btrfs_item_ptr(leaf, path->slots[0], 259 struct btrfs_inode_ref); 260 name_ptr = (unsigned long)(iref + 1); 261 name_len = btrfs_inode_ref_name_len(leaf, iref); 262 } 263 264 read_extent_buffer(leaf, name, name_ptr, name_len); 265 btrfs_free_path(path); 266 267 /* 268 * have to add the null termination to make sure that reconnect_path 269 * gets the right len for strlen 270 */ 271 name[name_len] = '\0'; 272 273 return 0; 274 } 275 276 const struct export_operations btrfs_export_ops = { 277 .encode_fh = btrfs_encode_fh, 278 .fh_to_dentry = btrfs_fh_to_dentry, 279 .fh_to_parent = btrfs_fh_to_parent, 280 .get_parent = btrfs_get_parent, 281 .get_name = btrfs_get_name, 282 }; 283