Btrfs: zero unused bytes in inode item

The otime field is not zeroed, so users will see random otime in an old
filesystem with a new kernel which has otime support in the future.

The reserved bytes are also not zeroed, and we'll have compatibility
issue if we make use of those bytes.

Signed-off-by: Li Zefan <lizefan@huawei.com>

diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 21d91a8..335605c 100644 (file)
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -62,6 +62,7 @@ static inline void btrfs_init_delayed_node(
        INIT_LIST_HEAD(&delayed_node->n_list);
        INIT_LIST_HEAD(&delayed_node->p_list);
        delayed_node->bytes_reserved = 0;
+       memset(&delayed_node->inode_item, 0, sizeof(delayed_node->inode_item));
 }
 
 static inline int btrfs_is_continuous_delayed_item(

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index ee45ebf..144f464 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4693,6 +4693,8 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
        inode_item = btrfs_item_ptr(path->nodes[0], path->slots[0],
                                  struct btrfs_inode_item);
+       memset_extent_buffer(path->nodes[0], 0, (unsigned long)inode_item,
+                            sizeof(*inode_item));
        fill_inode_item(trans, path->nodes[0], inode_item, inode);
 
        ref = btrfs_item_ptr(path->nodes[0], path->slots[0] + 1,