Commit 381b487d authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Stefan Hajnoczi
Browse files

qcow2: make is_allocated return true for zero clusters 



Otherwise, live migration of the top layer will miss zero clusters and
let the backing file show through.  This also matches what is done in qed.

QCOW2_CLUSTER_ZERO clusters are invalid in v2 image files.  Check this
directly in qcow2_get_cluster_offset instead of replicating the test
everywhere.

Cc: qemu-stable@nongnu.org
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarStefan Hajnoczi <stefanha@redhat.com>
parent 36479179

block/qcow2-cluster.c

+3 −0
Original line number Diff line number Diff line
@@ -454,6 +454,9 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, 
        *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;

        break;

    case QCOW2_CLUSTER_ZERO:

        if (s->qcow_version < 3) {

            return -EIO;

        }

        c = count_contiguous_clusters(nb_clusters, s->cluster_size,

                &l2_table[l2_index], 0,

                QCOW_OFLAG_COMPRESSED | QCOW_OFLAG_ZERO);

block/qcow2.c

+1 −5
Original line number Diff line number Diff line
@@ -621,7 +621,7 @@ static int coroutine_fn qcow2_co_is_allocated(BlockDriverState *bs, 
        *pnum = 0;

    }



    return (cluster_offset != 0);

    return (cluster_offset != 0) || (ret == QCOW2_CLUSTER_ZERO);

}



/* handle reading after the end of the backing file */
@@ -702,10 +702,6 @@ static coroutine_fn int qcow2_co_readv(BlockDriverState *bs, int64_t sector_num, 
            break;



        case QCOW2_CLUSTER_ZERO:

            if (s->qcow_version < 3) {

                ret = -EIO;

                goto fail;

            }

            qemu_iovec_memset(&hd_qiov, 0, 0, 512 * cur_nr_sectors);

            break;