ceph: revert commit 22cddde1

commit 22cddde1 breaks the atomicity of write operation, it also
introduces a deadlock between write and truncate.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
Reviewed-by: Greg Farnum <greg@inktank.com>

Conflicts:
	fs/ceph/addr.c