From eda95bc98497387e6b23e870c95867fa560793c7 Mon Sep 17 00:00:00 2001 Message-Id: In-Reply-To: <67968bc615637394c3ef7dfefa360dab90f33d5d.1429902956.git.jen@redhat.com> References: <67968bc615637394c3ef7dfefa360dab90f33d5d.1429902956.git.jen@redhat.com> From: Max Reitz Date: Wed, 18 Mar 2015 19:21:47 -0500 Subject: [CHANGE 04/42] qcow2: Fail write_compressed when overwriting data To: rhvirt-patches@redhat.com, jen@redhat.com RH-Author: Max Reitz Message-id: <1426706542-30384-5-git-send-email-mreitz@redhat.com> Patchwork-id: 64469 O-Subject: [RHEL-6.7 qemu-kvm PATCH v2 04/39] qcow2: Fail write_compressed when overwriting data Bugzilla: 1129892 RH-Acked-by: Jeffrey Cody RH-Acked-by: Kevin Wolf RH-Acked-by: Stefan Hajnoczi From: Kevin Wolf BZ: 1129892 qcow2_alloc_compressed_cluster_offset() already fails if the copied flag is set, because qcow2_write_compressed() doesn't perform COW as it would have to do to allow this. However, what we really want to check here is whether the cluster is allocated or not. With internal snapshots the copied flag may not be set on allocated clusters. Check the cluster offset instead. Signed-off-by: Kevin Wolf (cherry picked from commit b0b6862e5e1a1394e0ab3d5da94ba8b0da8664e2) Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) Signed-off-by: Jeff E. Nelson --- block/qcow2-cluster.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 7ff8b50..f973b54 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -623,15 +623,14 @@ uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs, return 0; } + /* Compression can't overwrite anything. Fail if the cluster was already + * allocated. */ cluster_offset = be64_to_cpu(l2_table[l2_index]); - if (cluster_offset & QCOW_OFLAG_COPIED) { + if (cluster_offset & L2E_OFFSET_MASK) { qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); return 0; } - if (cluster_offset) - qcow2_free_any_clusters(bs, cluster_offset, 1); - cluster_offset = qcow2_alloc_bytes(bs, compressed_size); if (cluster_offset < 0) { qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); -- 2.1.0