Configuring the cluster size of an image may have performance implications. This patch allows us to detect cluster size for existing images so that we will be able to propagate it to new images which are based on existing images e.g. during snapshots/block-copy/etc. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; --- src/qemu/qemu_monitor.h | 3 +++ src/qemu/qemu_monitor_json.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/src/qemu/qemu_monitor.h b/src/qemu/qemu_monitor.h index d20a15c202..369d63ce12 100644 --- a/src/qemu/qemu_monitor.h +++ b/src/qemu/qemu_monitor.h @@ -696,6 +696,9 @@ struct _qemuBlockNamedNodeData { qemuBlockNamedNodeDataBitmapPtr *bitmaps; size_t nbitmaps; + + /* the cluster size of the image is valid only when > 0 */ + unsigned long long clusterSize; }; virHashTablePtr diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c index 9cdf6c0f7f..e6d2e7d4db 100644 --- a/src/qemu/qemu_monitor_json.c +++ b/src/qemu/qemu_monitor_json.c @@ -2997,6 +2997,9 @@ qemuMonitorJSONBlockGetNamedNodeDataWorker(size_t pos G_GNUC_UNUSED, if (virJSONValueObjectGetNumberUlong(img, "actual-size", &ent->physical) < 0) ent->physical = ent->capacity; + /* try looking up the cluster size */ + ignore_value(virJSONValueObjectGetNumberUlong(img, "cluster-size", &ent->clusterSize)); + if ((bitmaps = virJSONValueObjectGetArray(val, "dirty-bitmaps"))) qemuMonitorJSONBlockGetNamedNodeDataBitmaps(bitmaps, ent); -- 2.26.2

Propagate the cluster size from the original image as the user might have configured a custom cluster size for performance reasons. Propagate the cluster size of a qcow2 image to the new overlay or copy. Signed-off-by: Peter Krempa <pkrempa(a)redhat.com&gt; --- src/qemu/qemu_block.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/src/qemu/qemu_block.c b/src/qemu/qemu_block.c index 0113c64f0f..6e8fe545b4 100644 --- a/src/qemu/qemu_block.c +++ b/src/qemu/qemu_block.c @@ -2789,6 +2789,11 @@ qemuBlockStorageSourceCreateDetectSize(virHashTablePtr blockNamedNodeData, return -1; } + /* propagate cluster size if the images are compatible */ + if (templ->format == VIR_STORAGE_FILE_QCOW2 && + src->format == VIR_STORAGE_FILE_QCOW2) + src->clusterSize = entry->clusterSize; + if (src->format == VIR_STORAGE_FILE_RAW) { src->physical = entry->capacity; } else { -- 2.26.2