We won't wait DIO synchronously when doing AIO, so there will be potential
IO reorder in between AIO and GC, which will cause data corruption.

This patch adds inode_dio_wait to serialize aio and data GC to avoid this
issue.
Signed-off-by: NChao Yu <yuchao0@huawei.com>
Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>