Re: [PATCH v2 3/6] migration: Remove 'blk/-b' option from migrate commands

[Fabiano Rosas <farosas@suse.de>]

Peter Xu <peterx@redhat.com> writes:

> On Mon, Apr 29, 2024 at 02:18:57PM -0300, Fabiano Rosas wrote:
>> Peter Xu <peterx@redhat.com> writes:
>> 
>> > On Fri, Apr 26, 2024 at 10:14:05AM -0300, Fabiano Rosas wrote:
>> >> @@ -2003,21 +1997,7 @@ static bool migrate_prepare(MigrationState *s, bool blk, bool resume,
>> >>          }
>> >>      }
>> >>  
>> >> -    if (blk) {
>> >> -        if (migrate_colo()) {
>> >> -            error_setg(errp, "No disk migration is required in COLO mode");
>> >> -            return false;
>> >> -        }
>> >> -        if (migrate_block()) {
>> >> -            error_setg(errp, "Command options are incompatible with "
>> >> -                       "current migration capabilities");
>> >> -            return false;
>> >> -        }
>> >> -        if (!migrate_cap_set(MIGRATION_CAPABILITY_BLOCK, true, errp)) {
>> >> -            return false;
>> >> -        }
>> >> -        s->must_remove_block_options = true;
>> >> -    }
>> >> +    s->must_remove_block_options = true;
>> >
>> > Can we drop this var too?  Perhaps with block_cleanup_parameters()?
>> 
>> Yes, Markus mentioned it in v1 already. Take a look there. There's
>> several other declarations I missed. v3 is coming soon.
>
> Right, noticed that it's removed actually in the next patch.
>
> But iiuc it can already been removed in this patch.  If we want to remove
> it in the next, logically we should set must_remove_block_options=false
> here, though..  So maybe easier to just drop it here.

Ah I see what you mean. I thought you're just asking for the removal
overall.

But block_cleanup_parameters sets the block capability to false and the
whole block migration only goes away in the next patch. I think we need
to keep this as true to preserve behavior. In theory, after this patch
people could still use the block migration just fine by setting the cap.