xfs: fix memcpy fortify errors in RUI log format copying

mainline inclusion
from mainline-v6.1-rc1
commit b45ca961
category: bugfix
bugzilla: 188220, https://gitee.com/openeuler/kernel/issues/I4KIAO
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b45ca961e94673df83ab1900802afe82776966e6



--------------------------------

Starting in 6.1, CONFIG_FORTIFY_SOURCE checks the length parameter of
memcpy.  Since we're already fixing problems with BUI item copying, we
should fix it everything else.

Refactor the xfs_rui_copy_format function to handle the copying of the
head and the flex array members separately.  While we're at it, fix a
minor validation deficiency in the recovery function.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Long Li <leo.lilong@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>