On 02/06/2015 08:27 AM, Eric Blake wrote: >> >> - /* The cluster refcount was incremented, either by >> qcow2_alloc_clusters() >> - * or explicitly by qcow2_update_cluster_refcount(). Refcount blocks >> must >> - * be flushed before the caller's L2 table updates. >> - */ >> + assert(offset); >> + ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER); > > Case 1: This incremented the new cluster. Good > Case 2: This incremented the old cluster. Good > Case 3: This incremented the new cluster. Good > Case 4: This incremented the old cluster. But the new cluster remains at > refcount 0. BAD.
Wait. Maybe I'm confused. You are requesting an update_refcount() across size bytes, and given the offset, that means that the code will round up to cover BOTH clusters in one call. Does update_refcount() properly increment from [ 1, 0 ] to [ 2, 1 ] when given a 2-cluster size (when offset, size is rounded up to cluster boundaries)? If so, then there is no bug after all. -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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