Re: [Qemu-devel] [PATCH 1/1] block: add block device shared field

[Fam Zheng <famz@redhat.com>]

On Tue, 09/05 10:56, Stefan Hajnoczi wrote:
> On Fri, Sep 01, 2017 at 08:10:54PM +0000, Brian Steffens wrote:
> > This adds a boolean option called 'shared' to block devices. It defaults
> > to off/false. When enabled for a particular block device, the 'shared' option
> > causes the block migration code to skip over syncing of that device. This
> > allows controlling exactly which block devices get synced during a migration.
> > 
> > Signed-off-by: Brian Steffens <briansteffens@gmail.com>
> > ---
> >  block.c                   | 7 +++++++
> >  block/qapi.c              | 2 ++
> >  include/block/block.h     | 1 +
> >  include/block/block_int.h | 3 +++
> >  migration/block.c         | 4 ++++
> >  qapi/block-core.json      | 2 +-
> >  6 files changed, 18 insertions(+), 1 deletion(-)
> 
> Thanks for the patch!  Please email the relevant maintainers:
> 
>   $ scripts/get_maintainer.pl -f block.c
>   Kevin Wolf <kwolf@redhat.com> (supporter:Block layer core)
>   Max Reitz <mreitz@redhat.com> (supporter:Block layer core)
>   qemu-block@nongnu.org (open list:Block layer core)
>   qemu-devel@nongnu.org (open list:All patches CC here)
> 
> I have CCed them so they see this email.
> 
> > diff --git a/migration/block.c b/migration/block.c
> > index 9171f60028..b347c3dc61 100644
> > --- a/migration/block.c
> > +++ b/migration/block.c
> > @@ -402,6 +402,10 @@ static int init_blk_migration(QEMUFile *f)
> >      bmds_bs = g_malloc0(num_bs * sizeof(*bmds_bs));
> >  
> >      for (i = 0, bs = bdrv_first(&it); bs; bs = bdrv_next(&it), i++) {
> > +        if (bs->shared) {

If we go with this approach, I'd prefer a more specific name like
bs->skip_block_migration; "shared" has a lot meanings so is less readable.

Fam

> > +            continue;
> > +        }
> > +