SDF_FLUSHING
sd->flags &= ~SDF_FLUSHING;
sd->flags &= ~(SDF_FLUSHING|SDF_DIRTY);
sd->flags &= ~SDF_FLUSHING;
sd->flags &= ~(SDF_FLUSHING|SDF_DIRTY);
sd->flags |= SDF_FLUSHING;
sd->flags &= ~SDF_FLUSHING;
sd->flags &= ~(SDF_FLUSHING|SDF_DIRTY);
if (sd->flags & SDF_FLUSHING) {
sd->flags &= ~(SDF_FLUSHING|SDF_DIRTY);