On 04/20/2017 09:11 AM, Eric Blake wrote: > On 04/20/2017 09:05 AM, Fam Zheng wrote: >> On Tue, 02/28 14:35, Peter Lieven wrote: >>> img_convert has been around before there was an ImgConvertState or >>> a block backend, but it has never been modified to directly use >>> these structs. Change this by parsing parameters directly into >>> the ImgConvertState and directly use BlockBackend where possible. >>> Futhermore variable initalization has been reworked and sorted. >>> >>> Signed-off-by: Peter Lieven <p...@kamp.de> >> >> I see an iotest failure with this patch, in Kevin's block-next tree: >> >> 019 1s ... - output mismatch (see 019.out.bad) >> --- /stor/work/qemu/tests/qemu-iotests/019.out 2017-04-17 >> 16:19:56.523968474 +0800 >> +++ 019.out.bad 2017-04-20 22:03:29.868216955 +0800 >> @@ -1086,8 +1086,8 @@ >> >> Checking if backing clusters are allocated when they shouldn't >> >> -0/128 sectors allocated at offset 1 MiB >> -0/128 sectors allocated at offset 4.001 GiB >> +128/128 sectors allocated at offset 1 MiB >> +128/128 sectors allocated at offset 4.001 GiB > > Hmm - I wonder if my patch to make 'zero with unmap' on an image with no > backing file prefer pure unallocated clusters over a reads-as-zero would > make a difference. > https://lists.gnu.org/archive/html/qemu-devel/2017-04/msg01728.html > > Testing now...
Nope, did not make a difference, although it's certainly related; per my
comment in that thread that:
Note that technically, we _could_ write a cluster as unallocated
rather than zero if a backing file exists but the backing file
also reads as zero, but that's more expensive to determine, so
this optimization is limited to qcow2 without a backing file.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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