ocfs2: do not use ocfs2_zero_extend during direct IO

In ocfs2_direct_IO_write, we use ocfs2_zero_extend to zero allocated
clusters in case of cluster not aligned.  But ocfs2_zero_extend uses page
cache, this may happen that it clears the data which blockdev_direct_IO
has already written.

We should use blkdev_issue_zeroout instead of ocfs2_zero_extend during
direct IO.

So fix this issue by introducing ocfs2_direct_IO_zero_extend and
ocfs2_direct_IO_extend_no_holes.

Reported-by: Yiwen Jiang <jiangyiwen@huawei.com>
Signed-off-by: Joseph Qi <joseph.qi@huawei.com>
Tested-by: Yiwen Jiang <jiangyiwen@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>