The wrapper in setattr_more that translates the operations to attr_x
needs to decide whether to ask attr_x to perform a change to any of
the fields passed to it or not. For the date and size fields this
is implicit - we always tell attr_x to change them. For any of the
other fields, it should be explicit.
The only field that is in the struct that this applies to is
data_version. Because the data version field by default is zero,
we use that as condition to decide whether to pass the data_version
down to attr_x.
Previously, the code would always pass a data_version=0 down to attr_x,
triggering one of the validity checks, making it return -EINVAL. We
add a simple test case to test for this issue.
Signed-off-by: Auke Kok <auke.kok@versity.com>