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 = BTRFS_I(inode)->location.objectid; 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 { 65 struct btrfs_root *root; 66 struct inode *inode; 67 struct btrfs_key key; 68 69 key.objectid = root_objectid; 70 btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY); 71 key.offset = (u64)-1; 72 73 root = btrfs_read_fs_root_no_name(btrfs_sb(sb)->fs_info, &key); 74 if (IS_ERR(root)) 75 return ERR_CAST(root); 76 77 key.objectid = objectid; 78 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY); 79 key.offset = 0; 80 81 inode = btrfs_iget(sb, &key, root, NULL); 82 if (IS_ERR(inode)) 83 return (void *)inode; 84 85 if (generation != inode->i_generation) { 86 iput(inode); 87 return ERR_PTR(-ESTALE); 88 } 89 90 return d_obtain_alias(inode); 91 } 92 93 static struct dentry *btrfs_fh_to_parent(struct super_block *sb, struct fid *fh, 94 int fh_len, int fh_type) 95 { 96 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 97 u64 objectid, root_objectid; 98 u32 generation; 99 100 if (fh_type == FILEID_BTRFS_WITH_PARENT) { 101 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE) 102 return NULL; 103 root_objectid = fid->root_objectid; 104 } else if (fh_type == FILEID_BTRFS_WITH_PARENT_ROOT) { 105 if (fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) 106 return NULL; 107 root_objectid = fid->parent_root_objectid; 108 } else 109 return NULL; 110 111 objectid = fid->parent_objectid; 112 generation = fid->parent_gen; 113 114 return btrfs_get_dentry(sb, objectid, root_objectid, generation); 115 } 116 117 static struct dentry *btrfs_fh_to_dentry(struct super_block *sb, struct fid *fh, 118 int fh_len, int fh_type) 119 { 120 struct btrfs_fid *fid = (struct btrfs_fid *) fh; 121 u64 objectid, root_objectid; 122 u32 generation; 123 124 if ((fh_type != FILEID_BTRFS_WITH_PARENT || 125 fh_len != BTRFS_FID_SIZE_CONNECTABLE) && 126 (fh_type != FILEID_BTRFS_WITH_PARENT_ROOT || 127 fh_len != BTRFS_FID_SIZE_CONNECTABLE_ROOT) && 128 (fh_type != FILEID_BTRFS_WITHOUT_PARENT || 129 fh_len != BTRFS_FID_SIZE_NON_CONNECTABLE)) 130 return NULL; 131 132 objectid = fid->objectid; 133 root_objectid = fid->root_objectid; 134 generation = fid->gen; 135 136 return btrfs_get_dentry(sb, objectid, root_objectid, generation); 137 } 138 139 static struct dentry *btrfs_get_parent(struct dentry *child) 140 { 141 struct inode *dir = child->d_inode; 142 struct btrfs_root *root = BTRFS_I(dir)->root; 143 struct btrfs_key key; 144 struct btrfs_path *path; 145 struct extent_buffer *leaf; 146 int slot; 147 u64 objectid; 148 int ret; 149 150 path = btrfs_alloc_path(); 151 152 key.objectid = dir->i_ino; 153 btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY); 154 key.offset = (u64)-1; 155 156 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0); 157 if (ret < 0) { 158 /* Error */ 159 btrfs_free_path(path); 160 return ERR_PTR(ret); 161 } 162 leaf = path->nodes[0]; 163 slot = path->slots[0]; 164 if (ret) { 165 /* btrfs_search_slot() returns the slot where we'd want to 166 insert a backref for parent inode #0xFFFFFFFFFFFFFFFF. 167 The _real_ backref, telling us what the parent inode 168 _actually_ is, will be in the slot _before_ the one 169 that btrfs_search_slot() returns. */ 170 if (!slot) { 171 /* Unless there is _no_ key in the tree before... */ 172 btrfs_free_path(path); 173 return ERR_PTR(-EIO); 174 } 175 slot--; 176 } 177 178 btrfs_item_key_to_cpu(leaf, &key, slot); 179 btrfs_free_path(path); 180 181 if (key.objectid != dir->i_ino || key.type != BTRFS_INODE_REF_KEY) 182 return ERR_PTR(-EINVAL); 183 184 objectid = key.offset; 185 186 /* If we are already at the root of a subvol, return the real root */ 187 if (objectid == dir->i_ino) 188 return dget(dir->i_sb->s_root); 189 190 /* Build a new key for the inode item */ 191 key.objectid = objectid; 192 btrfs_set_key_type(&key, BTRFS_INODE_ITEM_KEY); 193 key.offset = 0; 194 195 return d_obtain_alias(btrfs_iget(root->fs_info->sb, &key, root, NULL)); 196 } 197 198 const struct export_operations btrfs_export_ops = { 199 .encode_fh = btrfs_encode_fh, 200 .fh_to_dentry = btrfs_fh_to_dentry, 201 .fh_to_parent = btrfs_fh_to_parent, 202 .get_parent = btrfs_get_parent, 203 }; 204