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 static 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 int index; 69 int err = 0; 70 71 if (objectid < BTRFS_FIRST_FREE_OBJECTID) 72 return ERR_PTR(-ESTALE); 73 74 key.objectid = root_objectid; 75 key.type = BTRFS_ROOT_ITEM_KEY; 76 key.offset = (u64)-1; 77 78 index = srcu_read_lock(&fs_info->subvol_srcu); 79 80 root = btrfs_read_fs_root_no_name(fs_info, &key); 81 if (IS_ERR(root)) { 82 err = PTR_ERR(root); 83 goto fail; 84 } 85 86 key.objectid = objectid; 87 key.type = BTRFS_INODE_ITEM_KEY; 88 key.offset = 0; 89 90 inode = btrfs_iget(sb, &key, root, NULL); 91 if (IS_ERR(inode)) { 92 err = PTR_ERR(inode); 93 goto fail; 94 } 95 96 srcu_read_unlock(&fs_info->subvol_srcu, index); 97 98 if (check_generation && generation != inode->i_generation) { 99 iput(inode); 100 return ERR_PTR(-ESTALE); 101 } 102 103 return d_obtain_alias(inode); 104 fail: 105 srcu_read_unlock(&fs_info->subvol_srcu, index); 106 return ERR_PTR(err); 107 } 108 109 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 110 int fh_len, int fh_type) 111 { 112 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 113 u64 objectid, root_objectid; 114 u32 generation; 115 116 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 117 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE) 118 return NULL; 119 root_objectid = fid->root_objectid; 120 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 121 if (fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) 122 return NULL; 123 root_objectid = fid->parent_root_objectid; 124 } else 125 return NULL; 126 127 objectid = fid->parent_objectid; 128 generation = fid->parent_gen; 129 130 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 131 } 132 133 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 134 int fh_len, int fh_type) 135 { 136 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 137 u64 objectid, root_objectid; 138 u32 generation; 139 140 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 141 fh_len < BTRFS_FID_SIZE_CONNECTABLE) && 142 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 143 fh_len < BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 144 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 145 fh_len < BTRFS_FID_SIZE_NON_CONNECTABLE)) 146 return NULL; 147 148 objectid = fid->objectid; 149 root_objectid = fid->root_objectid; 150 generation = fid->gen; 151 152 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 153 } 154 155 static struct dentry *btrfs_get_parent(struct dentry *child) 156 { 157 struct inode *dir = d_inode(child); 158 struct btrfs_fs_info *fs_info = btrfs_sb(dir->i_sb); 159 struct btrfs_root *root = BTRFS_I(dir)->root; 160 struct btrfs_path *path; 161 struct extent_buffer *leaf; 162 struct btrfs_root_ref *ref; 163 struct btrfs_key key; 164 struct btrfs_key found_key; 165 int ret; 166 167 path = btrfs_alloc_path(); 168 if (!path) 169 return ERR_PTR(-ENOMEM); 170 171 if (btrfs_ino(BTRFS_I(dir)) == BTRFS_FIRST_FREE_OBJECTID) { 172 key.objectid = root->root_key.objectid; 173 key.type = BTRFS_ROOT_BACKREF_KEY; 174 key.offset = (u64)-1; 175 root = fs_info->tree_root; 176 } else { 177 key.objectid = btrfs_ino(BTRFS_I(dir)); 178 key.type = BTRFS_INODE_REF_KEY; 179 key.offset = (u64)-1; 180 } 181 182 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 183 if (ret < 0) 184 goto fail; 185 186 BUG_ON(ret == 0); /* Key with offset of -1 found */ 187 if (path->slots[0] == 0) { 188 ret = -ENOENT; 189 goto fail; 190 } 191 192 path->slots[0]--; 193 leaf = path->nodes[0]; 194 195 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 196 if (found_key.objectid != key.objectid || found_key.type != key.type) { 197 ret = -ENOENT; 198 goto fail; 199 } 200 201 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 202 ref = btrfs_item_ptr(leaf, path->slots[0], 203 struct btrfs_root_ref); 204 key.objectid = btrfs_root_ref_dirid(leaf, ref); 205 } else { 206 key.objectid = found_key.offset; 207 } 208 btrfs_free_path(path); 209 210 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 211 return btrfs_get_dentry(fs_info->sb, key.objectid, 212 found_key.offset, 0, 0); 213 } 214 215 key.type = BTRFS_INODE_ITEM_KEY; 216 key.offset = 0; 217 return d_obtain_alias(btrfs_iget(fs_info->sb, &key, root, NULL)); 218 fail: 219 btrfs_free_path(path); 220 return ERR_PTR(ret); 221 } 222 223 static int btrfs_get_name(struct dentry *parent, char *name, 224 struct dentry *child) 225 { 226 struct inode *inode = d_inode(child); 227 struct inode *dir = d_inode(parent); 228 struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb); 229 struct btrfs_path *path; 230 struct btrfs_root *root = BTRFS_I(dir)->root; 231 struct btrfs_inode_ref *iref; 232 struct btrfs_root_ref *rref; 233 struct extent_buffer *leaf; 234 unsigned long name_ptr; 235 struct btrfs_key key; 236 int name_len; 237 int ret; 238 u64 ino; 239 240 if (!S_ISDIR(dir->i_mode)) 241 return -EINVAL; 242 243 ino = btrfs_ino(BTRFS_I(inode)); 244 245 path = btrfs_alloc_path(); 246 if (!path) 247 return -ENOMEM; 248 path->leave_spinning = 1; 249 250 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 251 key.objectid = BTRFS_I(inode)->root->root_key.objectid; 252 key.type = BTRFS_ROOT_BACKREF_KEY; 253 key.offset = (u64)-1; 254 root = fs_info->tree_root; 255 } else { 256 key.objectid = ino; 257 key.offset = btrfs_ino(BTRFS_I(dir)); 258 key.type = BTRFS_INODE_REF_KEY; 259 } 260 261 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 262 if (ret < 0) { 263 btrfs_free_path(path); 264 return ret; 265 } else if (ret > 0) { 266 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 267 path->slots[0]--; 268 } else { 269 btrfs_free_path(path); 270 return -ENOENT; 271 } 272 } 273 leaf = path->nodes[0]; 274 275 if (ino == BTRFS_FIRST_FREE_OBJECTID) { 276 rref = btrfs_item_ptr(leaf, path->slots[0], 277 struct btrfs_root_ref); 278 name_ptr = (unsigned long)(rref + 1); 279 name_len = btrfs_root_ref_name_len(leaf, rref); 280 } else { 281 iref = btrfs_item_ptr(leaf, path->slots[0], 282 struct btrfs_inode_ref); 283 name_ptr = (unsigned long)(iref + 1); 284 name_len = btrfs_inode_ref_name_len(leaf, iref); 285 } 286 287 read_extent_buffer(leaf, name, name_ptr, name_len); 288 btrfs_free_path(path); 289 290 /* 291 * have to add the null termination to make sure that reconnect_path 292 * gets the right len for strlen 293 */ 294 name[name_len] = '\0'; 295 296 return 0; 297 } 298 299 const struct export_operations btrfs_export_ops = { 300 .encode_fh = btrfs_encode_fh, 301 .fh_to_dentry = btrfs_fh_to_dentry, 302 .fh_to_parent = btrfs_fh_to_parent, 303 .get_parent = btrfs_get_parent, 304 .get_name = btrfs_get_name, 305 }; 306