From: Catalin Marinas <catalin.marinas@arm.com>
Date: Tue, 18 Sep 2012 18:02:06 +0100

This function is used by sparc, powerpc and arm64 for compat support.
The patch adds a generic implementation which calls do_sendfile()
directly and avoids set_fs().

The sparc architecture has wrappers for the sign extensions while
powerpc relies on the compiler to do the this. The patch adds a wrapper
for powerpc to handle the u32->int type conversion.

compat_sys_sendfile64() can be replaced by a sys_sendfile() call since
compat_loff_t has the same size as off_t on a 64-bit system. On powerpc,
similar wrapper needs to be added for the u32->int conversion.

The reason for a single patch covering both powerpc and sparc is to keep
it bisectable (and simple), otherwise kernel building may fail with
mismatched function declarations.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Acked-by: David S. Miller <davem@davemloft.net>