On 5/25/20 1:08 PM, Alberto Garcia wrote:
There are situations in which we want to know how many contiguous
subclusters of the same type there are in a given cluster. This can be
done by simply iterating over the subclusters and repeatedly calling
qcow2_get_subcluster_type() for each one of them.
However once we determined the type of a subcluster we can check the
rest efficiently by counting the number of adjacent ones (or zeroes)
in the bitmap. This is what this function does.
Signed-off-by: Alberto Garcia <be...@igalia.com>
---
block/qcow2-cluster.c | 51 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
+ if (*type == QCOW2_SUBCLUSTER_INVALID) {
+ return -EINVAL;
+ } else if (!has_subclusters(s) || *type == QCOW2_SUBCLUSTER_COMPRESSED) {
+ return s->subclusters_per_cluster - sc_from;
+ }
+
+ switch (*type) {
+ case QCOW2_SUBCLUSTER_NORMAL:
+ val = l2_bitmap | QCOW_OFLAG_SUB_ALLOC_RANGE(0, sc_from);
+ return cto32(val) - sc_from;
Slick.
Reviewed-by: Eric Blake <ebl...@redhat.com>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3226
Virtualization: qemu.org | libvirt.org
