On Thu, 30 Mar 2023, Xiao Ni wrote:

On Thu, Mar 30, 2023 at 5:52 AM NeilBrown [off-list ref] wrote:

quoted

On Wed, 22 Mar 2023, NeilBrown wrote:

quoted

On Wed, 22 Mar 2023, Xiao Ni wrote:

quoted

Second, are there possibilities that the arguments "dev" and "name" of
function create_mddev
are null at the same time?

No.  For Build or Create, dev is never NULL.  For Assemble and
Incremental, name is never NULL.

I should clarify this a bit.  For Assemble and Incremental, "name" is
never NULL *but* it might be an empty string.
So:
        if (name && name[0] == 0)
                name = NULL;

might cause it to become NULL.  So you cannot assume there is always
either a valid "dev" or a valid "name".  "dev" might be NULL, and "name"
might be "".

NeilBrown

Hi Neil

The input argument name should be the metadata name. For incremental
and assemble, why are there possibilities that the metadata name is
invalid? A raid device should have a valid metadata name, right?

"should" do, yes.  But you can never completely trust data on disk.  It
is safest to be prepared for "name" being "".

NeilBrown