On 01/16/2013 09:24 AM, Benoît Canet wrote: > A new physical cluster with the same hash value will be used for further > occurence of this hash.
s/occurence/occurrence/
> ---
> block/qcow2-dedup.c | 32 ++++++++++++++++++++++++++++++++
> block/qcow2-refcount.c | 3 +++
> block/qcow2.h | 4 ++++
> 3 files changed, 39 insertions(+)
>
> +++ b/block/qcow2-refcount.c
> @@ -489,6 +489,9 @@ int QEMU_WARN_UNUSED_RESULT
> update_refcount(BlockDriverState *bs,
> ret = -EINVAL;
> goto fail;
> }
> + if (s->has_dedup && deduplication && refcount >= 0xFFFF/2) {
> + qcow2_dedup_refcount_half_max_reached(bs, cluster_index);
You are hardcoding to a width of 16 bits; however, version 3 makes the
refcount field variable-sized:
96 - 99: refcount_order
Describes the width of a reference count block entry
(width
in bits = 1 << refcount_order). For version 2
images, the
order is always assumed to be 4 (i.e. the width is
16 bits).
Hmm, what happens if refcount_order is 0 to disable reference counting?
That setting is valid for creating a qcow2 file that can't be used for
internal snapshots. But it also interferes with dedup; so you probably
want to add some additional requirements in the spec (patch 1/36) that
when dedup is in use, refcount_order must be a minimum value (or require
that it be exactly 4, for a width of 16 bits).
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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