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authorKevin Wolf <kwolf@redhat.com>2015-11-04 18:16:24 +0100
committerMax Reitz <mreitz@redhat.com>2015-11-11 16:55:29 +0100
commita99dfb45f26bface6830ee5465e57bcdbc53c6c8 (patch)
treee6d948e6c24c2e01fc0c1316b172e916328e6123 /block
parent342075fd0ec9dce87139d71a81e1dbbe5ab5d021 (diff)
qcow2: Fix qcow2_get_cluster_offset() for zero clusters
When searching for contiguous zero clusters, we only need to check the cluster type. Before this patch, an increasing offset (L2E_OFFSET_MASK) was expected, so that the function never returned more than a single zero cluster in practice. This patch fixes it to actually return as many contiguous zero clusters as it can. Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> Message-id: 1446657384-5907-1-git-send-email-kwolf@redhat.com Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block')
-rw-r--r--block/qcow2-cluster.c15
1 files changed, 9 insertions, 6 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 67be0ce2c9..24a60e2236 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -312,7 +312,7 @@ static int count_contiguous_clusters(int nb_clusters, int cluster_size,
if (!offset)
return 0;
- assert(qcow2_get_cluster_type(first_entry) != QCOW2_CLUSTER_COMPRESSED);
+ assert(qcow2_get_cluster_type(first_entry) == QCOW2_CLUSTER_NORMAL);
for (i = 0; i < nb_clusters; i++) {
uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask;
@@ -324,14 +324,16 @@ static int count_contiguous_clusters(int nb_clusters, int cluster_size,
return i;
}
-static int count_contiguous_free_clusters(int nb_clusters, uint64_t *l2_table)
+static int count_contiguous_clusters_by_type(int nb_clusters,
+ uint64_t *l2_table,
+ int wanted_type)
{
int i;
for (i = 0; i < nb_clusters; i++) {
int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
- if (type != QCOW2_CLUSTER_UNALLOCATED) {
+ if (type != wanted_type) {
break;
}
}
@@ -554,13 +556,14 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
ret = -EIO;
goto fail;
}
- c = count_contiguous_clusters(nb_clusters, s->cluster_size,
- &l2_table[l2_index], QCOW_OFLAG_ZERO);
+ c = count_contiguous_clusters_by_type(nb_clusters, &l2_table[l2_index],
+ QCOW2_CLUSTER_ZERO);
*cluster_offset = 0;
break;
case QCOW2_CLUSTER_UNALLOCATED:
/* how many empty clusters ? */
- c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]);
+ c = count_contiguous_clusters_by_type(nb_clusters, &l2_table[l2_index],
+ QCOW2_CLUSTER_UNALLOCATED);
*cluster_offset = 0;
break;
case QCOW2_CLUSTER_NORMAL: