Re: [libvirt PATCH v2 2/2] storage_file: add support to probe cluster_size from QCOW2 images

On Thu, May 20, 2021 at 17:14:32 +0200, Pavel Hrdina wrote: > >From QEMU docs/interop/qcow2.txt : > > Byte 20 - 23: cluster_bits > Number of bits that are used for addressing an offset > within a cluster (1 << cluster_bits is the cluster size). > > With this patch libvirt will be able to report the current cluster_size > for all existing storage volumes managed by storage driver. > > Signed-off-by: Pavel Hrdina <phrdina(a)redhat.com&gt; > --- > > Changes in v2: > - Reworkded to use callback. > > src/storage/storage_util.c | 3 ++ > src/storage_file/storage_file_probe.c | 70 ++++++++++++++++++++------- > 2 files changed, 56 insertions(+), 17 deletions(-) [...] > @@ -468,6 +477,28 @@ qcow2GetExtensions(const char *buf, > } > > > +static unsigned long long > +qcow2GetClusterSize(const char *buf, > + size_t buf_size, > + int endian) The 'endian' argument makes sense only for generic getters. You know that qcow2 has always LV_BIG_ENDIAN set. > +{ > + int clusterBits = 0; > + > + if ((QCOWX_HDR_CLUSTER_BITS_OFFSET + 4) > buf_size) > + return 0; > + > + if (endian == LV_LITTLE_ENDIAN) > + clusterBits = virReadBufInt32LE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); > + else > + clusterBits = virReadBufInt32BE(buf + QCOWX_HDR_CLUSTER_BITS_OFFSET); > + > + if (clusterBits > 0) > + return 1 << clusterBits; > + > + return 0; > +} Drop the 'endian' argument with appropriate cleanup and: Reviewed-by: Peter Krempa <pkrempa(a)redhat.com&gt;