Re: [libvirt] [PATCH v2 4/6] block/dirty-bitmap: explicitly lock bitmaps with successors
On 2/18/19 11:52 AM, Vladimir Sementsov-Ogievskiy wrote:
14.02.2019 2:23, John Snow wrote:
> Instead of implying a locked status, make it explicit.
locked interferes with bitmap mutex, so may be better "qmp_locked state", but
not sure.
I agree that "locked" has too many meanings, so in patch 5 I start using
the term "busy" instead.
> Now, bitmaps in use by migration, NBD or backup operations
> are all treated the same way with the same code paths.
>
> Signed-off-by: John Snow <jsnow(a)redhat.com>
> Reviewed-by: Eric Blake <eblake(a)redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov(a)virtuozzo.com>
Hmm. Isn't it better to make successor-related staff unrelated to locking at all?
Maybe -- but it doesn't make sense to allow users to modify bitmaps that
have a successor because we know it's definitely busy. I'll take a
further cleanup patch if you think it's better -- just be careful to
make sure that any interface calls will work gracefully with a bitmap
with a successor.
So, backup will call set_qmp_locked like others? And then do
create_successor,
abdicate, reclaim, whatever it wants, and finally set_qmp_locked(false) ?
To make it work even more in the same path. But it may be done separately, if we
want.