This patch fixes a couple of bugs regarding to orphan inodes when handling
errors.

This tries to
 - call alloc_nid_done with add_orphan_inode in handle_failed_inode
 - let truncate blocks in f2fs_evict_inode
 - not make a bad inode due to i_mode change
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>