On Tue, 01/24 12:00, Vladimir Sementsov-Ogievskiy wrote:
> > > static void coroutine_fn backup_run(void *opaque)
> > > {
> > > BackupBlockJob *job = opaque;
> > > @@ -453,20 +481,22 @@ static void coroutine_fn backup_run(void *opaque)
> > > end = DIV_ROUND_UP(job->common.len, job->cluster_size);
> > > job->copy_bitmap = hbitmap_alloc(end, 0);
> > > - hbitmap_set(job->copy_bitmap, 0, end);
> > > job->before_write.notify = backup_before_write_notify;
> > > bdrv_add_before_write_notifier(bs, &job->before_write);
> > > if (job->sync_mode == MIRROR_SYNC_MODE_NONE) {
> > > + hbitmap_set(job->copy_bitmap, 0, end);
> > This is confusing. It seems job->copy_bitmap is actually a superset of
> > clusters
> > to copy instead of the exact one? Because "none" mode doesn't need blanket
> > copy
> > - only overwritten clusters are copied...
>
> We can't guess, what clusters should be copied finally in none mode. None
> mode is done by allowing only notifier handling and no linear copying. But
> notifier handling will copy only clusters marked in copy_bitmap, so I set it
> from 0 to end.
Yes, that's how I understand it too, what I dislike is this bit of inconsistency
with it: "allowed to copy bitmap" here versus "planned to copy" in other modes.
I don't know how to improve that, but I think at least the specialty of none
mode could be mentioned in the comment of copy_bitmap.
