1 #include <linux/fs.h> 2 #include <linux/types.h> 3 #include "ctree.h" 4 #include "disk-io.h" 5 #include "btrfs_inode.h" 6 #include "print-tree.h" 7 #include "export.h" 8 #include "compat.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 dentry *dentry, u32 *fh, int *max_len, 17 int connectable) 18 { 19 struct btrfs_fid *fid = (struct btrfs_fid *)fh; 20 struct inode *inode = dentry->d_inode; 21 int len = *max_len; 22 int type; 23 24 if ((len < BTRFS_FID_SIZE_NON_CONNECTABLE) || 25 (connectable && len < BTRFS_FID_SIZE_CONNECTABLE)) 26 return 255; 27 28 len = BTRFS_FID_SIZE_NON_CONNECTABLE; 29 type = FILEID_BTRFS_WITHOUT_PARENT; 30 31 fid->objectid = inode->i_ino; 32 fid->root_objectid = BTRFS_I(inode)->root->objectid; 33 fid->gen = inode->i_generation; 34 35 if (connectable && !S_ISDIR(inode->i_mode)) { 36 struct inode *parent; 37 u64 parent_root_id; 38 39 spin_lock(&dentry->d_lock); 40 41 parent = dentry->d_parent->d_inode; 42 fid->parent_objectid = BTRFS_I(parent)->location.objectid; 43 fid->parent_gen = parent->i_generation; 44 parent_root_id = BTRFS_I(parent)->root->objectid; 45 46 spin_unlock(&dentry->d_lock); 47 48 if (parent_root_id != fid->root_objectid) { 49 fid->parent_root_objectid = parent_root_id; 50 len = BTRFS_FID_SIZE_CONNECTABLE_ROOT; 51 type = FILEID_BTRFS_WITH_PARENT_ROOT; 52 } else { 53 len = BTRFS_FID_SIZE_CONNECTABLE; 54 type = FILEID_BTRFS_WITH_PARENT; 55 } 56 } 57 58 *max_len = len; 59 return type; 60 } 61 62 static struct dentry *btrfs_get_dentry(struct super_block *sb, u64 objectid, 63 u64 root_objectid, u32 generation, 64 int check_generation) 65 { 66 struct btrfs_fs_info *fs_info = btrfs_sb(sb)->fs_info; 67 struct btrfs_root *root; 68 struct dentry *dentry; 69 struct inode *inode; 70 struct btrfs_key key; 71 int index; 72 int err = 0; 73 74 if (objectid < BTRFS_FIRST_FREE_OBJECTID) 75 return ERR_PTR(-ESTALE); 76 77 key.objectid = root_objectid; 78 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY); 79 key.offset = (u64)-1; 80 81 index = srcu_read_lock(&fs_info->subvol_srcu); 82 83 root = btrfs_read_fs_root_no_name(fs_info, &key); 84 if (IS_ERR(root)) { 85 err = PTR_ERR(root); 86 goto fail; 87 } 88 89 if (btrfs_root_refs(&root->root_item) == 0) { 90 err = -ENOENT; 91 goto fail; 92 } 93 94 key.objectid = objectid; 95 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY); 96 key.offset = 0; 97 98 inode = btrfs_iget(sb, &key, root); 99 if (IS_ERR(inode)) { 100 err = PTR_ERR(inode); 101 goto fail; 102 } 103 104 srcu_read_unlock(&fs_info->subvol_srcu, index); 105 106 if (check_generation && generation != inode->i_generation) { 107 iput(inode); 108 return ERR_PTR(-ESTALE); 109 } 110 111 dentry = d_obtain_alias(inode); 112 if (!IS_ERR(dentry)) 113 dentry->d_op = &btrfs_dentry_operations; 114 return dentry; 115 fail: 116 srcu_read_unlock(&fs_info->subvol_srcu, index); 117 return ERR_PTR(err); 118 } 119 120 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 121 int fh_len, int fh_type) 122 { 123 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 124 u64 objectid, root_objectid; 125 u32 generation; 126 127 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 128 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE) 129 return NULL; 130 root_objectid = fid->root_objectid; 131 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 132 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) 133 return NULL; 134 root_objectid = fid->parent_root_objectid; 135 } else 136 return NULL; 137 138 objectid = fid->parent_objectid; 139 generation = fid->parent_gen; 140 141 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 142 } 143 144 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 145 int fh_len, int fh_type) 146 { 147 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 148 u64 objectid, root_objectid; 149 u32 generation; 150 151 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 152 fh_len != BTRFS_FID_SIZE_CONNECTABLE) && 153 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 154 fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 155 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 156 fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE)) 157 return NULL; 158 159 objectid = fid->objectid; 160 root_objectid = fid->root_objectid; 161 generation = fid->gen; 162 163 return btrfs_get_dentry(sb, objectid, root_objectid, generation, 1); 164 } 165 166 static struct dentry *btrfs_get_parent(struct dentry *child) 167 { 168 struct inode *dir = child->d_inode; 169 static struct dentry *dentry; 170 struct btrfs_root *root = BTRFS_I(dir)->root; 171 struct btrfs_path *path; 172 struct extent_buffer *leaf; 173 struct btrfs_root_ref *ref; 174 struct btrfs_key key; 175 struct btrfs_key found_key; 176 int ret; 177 178 path = btrfs_alloc_path(); 179 180 if (dir->i_ino == BTRFS_FIRST_FREE_OBJECTID) { 181 key.objectid = root->root_key.objectid; 182 key.type = BTRFS_ROOT_BACKREF_KEY; 183 key.offset = (u64)-1; 184 root = root->fs_info->tree_root; 185 } else { 186 key.objectid = dir->i_ino; 187 key.type = BTRFS_INODE_REF_KEY; 188 key.offset = (u64)-1; 189 } 190 191 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 192 if (ret < 0) 193 goto fail; 194 195 BUG_ON(ret == 0); 196 if (path->slots[0] == 0) { 197 ret = -ENOENT; 198 goto fail; 199 } 200 201 path->slots[0]--; 202 leaf = path->nodes[0]; 203 204 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]); 205 if (found_key.objectid != key.objectid || found_key.type != key.type) { 206 ret = -ENOENT; 207 goto fail; 208 } 209 210 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 211 ref = btrfs_item_ptr(leaf, path->slots[0], 212 struct btrfs_root_ref); 213 key.objectid = btrfs_root_ref_dirid(leaf, ref); 214 } else { 215 key.objectid = found_key.offset; 216 } 217 btrfs_free_path(path); 218 219 if (found_key.type == BTRFS_ROOT_BACKREF_KEY) { 220 return btrfs_get_dentry(root->fs_info->sb, key.objectid, 221 found_key.offset, 0, 0); 222 } 223 224 key.type = BTRFS_INODE_ITEM_KEY; 225 key.offset = 0; 226 dentry = d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root)); 227 if (!IS_ERR(dentry)) 228 dentry->d_op = &btrfs_dentry_operations; 229 return dentry; 230 fail: 231 btrfs_free_path(path); 232 return ERR_PTR(ret); 233 } 234 235 const struct export_operations btrfs_export_ops = { 236 .encode_fh = btrfs_encode_fh, 237 .fh_to_dentry = btrfs_fh_to_dentry, 238 .fh_to_parent = btrfs_fh_to_parent, 239 .get_parent = btrfs_get_parent, 240 }; 241