In some functions, it's unnecessary to declare 'err' and 'ret' variables
at the same time.  This patch mainly to simplify the issue of such
declarations by reusing one variable.

Link: https://lkml.kernel.org/r/20211014073014.35754-1-sj@kernel.orgSigned-off-by: NRongwei Wang <rongwei.wang@linux.alibaba.com>
Signed-off-by: NSeongJae Park <sj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>