mainline inclusion
from mainline-5.3-rc1
commit 87e5e6da
category: feature
bugzilla: https://bugzilla.openeuler.org/show_bug.cgi?id=27
CVE: NA
---------------------------

Currently these functions return < 0 on error, and 0 for success.
Change that so that we return < 0 on error, but number of bytes
for success.

Some callers already treat the return value that way, others need a
slight tweak.
Signed-off-by: NJens Axboe <axboe@kernel.dk>

Conflicts:
	include/linux/uio.h
	[ Patch d05f4435("iov_iter: introduce hash_and_copy_to_iter
	  helper") is not appplied. ]
Signed-off-by: NZhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Nyangerkun <yangerkun@huawei.com>
Reviewed-by: Nzhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>