Re: [PATCH v4 4/9] qcow2: Support BDRV_REQ_ZERO_WRITE for truncate

[Vladimir Sementsov-Ogievskiy]

21.04.2020 13:50, Alberto Garcia wrote:

On Tue 21 Apr 2020 10:47:17 AM CEST, Vladimir Sementsov-Ogievskiy 
<vsement...@virtuozzo.com> wrote:

+    if ((flags & BDRV_REQ_ZERO_WRITE) && offset > old_length) {
+        ret = qcow2_cluster_zeroize(bs, old_length, offset - old_length, 0);

Hmm. As I understand, qcow2_cluster_zeroize is unprepared to
cluster-unaligned offset/size. I think we should handle it somehow.

You're right, it actually hits an assertion :-/

I suppose you can simply round the size up to the next cluster.

But we also need to handle unaligned old_length, we can't just align it down, 
we should write zero to existing cluster if it is NORMAL cluster..


--
Best regards,
Vladimir