Commit bf319ece authored by Kevin Wolf's avatar Kevin Wolf
Browse files

qcow2: Factor out count_cow_clusters 



Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
parent 6cc2a415

block/qcow2-cluster.c

+36 −19
Original line number Diff line number Diff line
@@ -676,6 +676,41 @@ err: 
    return ret;

 }



/*

 * 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,

 * which must copy from the backing file)

 */

static int count_cow_clusters(BDRVQcowState *s, int nb_clusters,

    uint64_t *l2_table, int l2_index)

{

    int i = 0;

    uint64_t cluster_offset;



    while (i < nb_clusters) {

        i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,

                &l2_table[l2_index], i, 0);

        if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) {

            break;

        }



        i += count_contiguous_free_clusters(nb_clusters - i,

                &l2_table[l2_index + i]);

        if (i >= nb_clusters) {

            break;

        }



        cluster_offset = be64_to_cpu(l2_table[l2_index + i]);



        if ((cluster_offset & QCOW_OFLAG_COPIED) ||

                (cluster_offset & QCOW_OFLAG_COMPRESSED))

            break;

    }



    assert(i <= nb_clusters);

    return i;

}



/*

 * alloc_cluster_offset

 *
@@ -739,25 +774,7 @@ again: 


    /* how many available clusters ? */



    while (i < nb_clusters) {

        i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,

                &l2_table[l2_index], i, 0);

        if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) {

            break;

        }



        i += count_contiguous_free_clusters(nb_clusters - i,

                &l2_table[l2_index + i]);

        if (i >= nb_clusters) {

            break;

        }



        cluster_offset = be64_to_cpu(l2_table[l2_index + i]);



        if ((cluster_offset & QCOW_OFLAG_COPIED) ||

                (cluster_offset & QCOW_OFLAG_COMPRESSED))

            break;

    }

    i = count_cow_clusters(s, nb_clusters, l2_table, l2_index);

    assert(i <= nb_clusters);

    nb_clusters = i;