This function compiles to 1402 bytes of machine code.

It has 2 callsites, and also a not-inlined copy gets created by compiler
anyway since its address gets passed as a parameter to block_truncate_page().
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
CC: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>