Re: [Qemu-devel] [PATCH] block migration: Allow compile time disable

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Juan Quintela (quintela@redhat.com) wrote:
> "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com> wrote:
> > From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> >
> > Many users now prefer to use drive_mirror over NBD as an
> > alternative to the older migrate -b option; drive_mirror is
> > more complex to setup but gives you more options (e.g. only
> > migrating some of the disks if some of them are shared).
> >
> > Allow the large chunk of block migration code to be compiled
> > out for those who don't use it.
> >
> > Based on a downstream-patch we've had for a while by Jeff Cody.
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> Reviewed-by: Juan Quintela <quintela@redhat.com>
> 
> > diff --git a/migration/migration.c b/migration/migration.c
> > index 353f2728cf..ffce72aabc 100644
> > --- a/migration/migration.c
> > +++ b/migration/migration.c
> > @@ -692,6 +692,7 @@ MigrationInfo *qmp_query_migrate(Error **errp)
> >  
> >          populate_ram_info(info, s);
> >  
> > +#ifdef CONFIG_LIVE_BLOCK_MIGRATION
> >          if (blk_mig_active()) {
> >              info->has_disk = true;
> >              info->disk = g_malloc0(sizeof(*info->disk));
> > @@ -699,6 +700,7 @@ MigrationInfo *qmp_query_migrate(Error **errp)
> >              info->disk->remaining = blk_mig_bytes_remaining();
> >              info->disk->total = blk_mig_bytes_total();
> >          }
> > +#endif
> 
> I think it can be cleaner to move this inside block.c and just export a
> function that is empty in case it is compiled out, but that it is just
> me, so you got the revieweb by anyways.
> 
> >          }
> >      }
> >  
> > +#ifdef CONFIG_LIVE_BLOCK_MIGRATION
> >      blk_mig_init();
> > +#endif
> >      ram_mig_init();
> >  
> >      /* If the currently selected machine wishes to override the units-per-bus
> 
> Same here, I preffer the ifdef in the header than here.

OK, done I've now got the block.h header having:
#ifdef CONFIG_LIVE_BLOCK_MIGRATION
void blk_mig_init(void);
int blk_mig_active(void);
uint64_t blk_mig_bytes_transferred(void);
uint64_t blk_mig_bytes_remaining(void);
uint64_t blk_mig_bytes_total(void);

#else
static inline void blk_mig_init(void) { };
static inline int blk_mig_active(void)
{
    return false;
}
static inline uint64_t blk_mig_bytes_transferred(void)
{
    return 0;
}

static inline uint64_t blk_mig_bytes_remaining(void)
{
    return 0;
}

static inline uint64_t blk_mig_bytes_total(void)
{
    return 0;
}
#endif /* CONFIG_LIVE_BLOCK_MIGRATION */

Dave

> Later, Juan.
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK