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qcow2: Split cluster_needs_cow() out of count_cow_clusters()

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We are going to need it in other places.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <65e5d9627ca2ebe7e62deaeddf60949c33067d9d.1594396418.git.berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Alberto Garcia 2020-07-10 18:12:46 +02:00 committed by Max Reitz
parent 8f91d6906c
commit c1587d877e
1 changed files with 19 additions and 15 deletions
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34
block/qcow2-cluster.c
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@ -1088,6 +1088,24 @@ static void calculate_l2_meta(BlockDriverState *bs,
QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
}
/* Returns true if writing to a cluster requires COW */
static bool cluster_needs_cow(BlockDriverState *bs, uint64_t l2_entry)
{
switch (qcow2_get_cluster_type(bs, l2_entry)) {
case QCOW2_CLUSTER_NORMAL:
if (l2_entry & QCOW_OFLAG_COPIED) {
return false;
}
case QCOW2_CLUSTER_UNALLOCATED:
case QCOW2_CLUSTER_COMPRESSED:
case QCOW2_CLUSTER_ZERO_PLAIN:
case QCOW2_CLUSTER_ZERO_ALLOC:
return true;
default:
abort();
}
}
/*
* Returns the number of contiguous clusters that can be used for an allocating
* write, but require COW to be performed (this includes yet unallocated space,
@ -1100,25 +1118,11 @@ static int count_cow_clusters(BlockDriverState *bs, int nb_clusters,
for (i = 0; i < nb_clusters; i++) {
uint64_t l2_entry = be64_to_cpu(l2_slice[l2_index + i]);
QCow2ClusterType cluster_type = qcow2_get_cluster_type(bs, l2_entry);
switch(cluster_type) {
case QCOW2_CLUSTER_NORMAL:
if (l2_entry & QCOW_OFLAG_COPIED) {
goto out;
}
if (!cluster_needs_cow(bs, l2_entry)) {
break;
case QCOW2_CLUSTER_UNALLOCATED:
case QCOW2_CLUSTER_COMPRESSED:
case QCOW2_CLUSTER_ZERO_PLAIN:
case QCOW2_CLUSTER_ZERO_ALLOC:
break;
default:
abort();
}
}
out:
assert(i <= nb_clusters);
return i;
}