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qcow2: make is_allocated return true for zero clusters

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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: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Paolo Bonzini 2013-03-06 18:02:01 +01:00 committed by Stefan Hajnoczi
parent 3647917919
commit 381b487d54
2 changed files with 4 additions and 5 deletions
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3
block/qcow2-cluster.c
View File

@ -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);

6
block/qcow2.c
View File

@ -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;