qcow2: fix image corruption after committing qcow2 image into base

After committing the qcow2 image contents into the base image, qemu-img
will call bdrv_make_empty to drop the payload in the layered image.

When this is done for qcow2 images, it blows away the LUKS encryption
header, making the resulting image unusable. There are two codepaths
for emptying a qcow2 image, and the second (slower) codepath leaves
the LUKS header intact, so force use of that codepath.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 126 insertions, 0 deletions

diff --git a/tests/qemu-iotests/198.out b/tests/qemu-iotests/198.out
new file mode 100644
index 0000000000..2db565e16b
--- /dev/null
+++ b/tests/qemu-iotests/198.out
@@ -0,0 +1,126 @@
+QA output created by 198
+== create base ==
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=16777216 encrypt.format=luks encrypt.key-secret=sec0 encrypt.iter-time=10
+
+== writing whole image base ==
+wrote 16777216/16777216 bytes at offset 0
+16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+== create overlay ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=16777216 backing_file=TEST_DIR/t.IMGFMT.base encrypt.format=luks encrypt.key-secret=sec1 encrypt.iter-time=10
+
+== writing whole image layer ==
+wrote 16777216/16777216 bytes at offset 0
+16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verify pattern base ==
+read 16777216/16777216 bytes at offset 0
+16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verify pattern layer ==
+read 16777216/16777216 bytes at offset 0
+16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== committing layer into base ==
+Image committed.
+
+== verify pattern base ==
+read 16777216/16777216 bytes at offset 0
+16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verify pattern layer ==
+read 16777216/16777216 bytes at offset 0
+16 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== checking image base ==
+image: json:{"encrypt.key-secret": "sec0", "driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT.base"}}
+file format: IMGFMT
+virtual size: 16M (16777216 bytes)
+Format specific information:
+    compat: 1.1
+    lazy refcounts: false
+    refcount bits: 16
+    encrypt:
+        ivgen alg: plain64
+        hash alg: sha256
+        cipher alg: aes-256
+        uuid: 00000000-0000-0000-0000-000000000000
+        format: luks
+        cipher mode: xts
+        slots:
+            [0]:
+                active: true
+                iters: 1024
+                key offset: 4096
+                stripes: 4000
+            [1]:
+                active: false
+                key offset: 262144
+            [2]:
+                active: false
+                key offset: 520192
+            [3]:
+                active: false
+                key offset: 778240
+            [4]:
+                active: false
+                key offset: 1036288
+            [5]:
+                active: false
+                key offset: 1294336
+            [6]:
+                active: false
+                key offset: 1552384
+            [7]:
+                active: false
+                key offset: 1810432
+        payload offset: 2068480
+        master key iters: 1024
+    corrupt: false
+
+== checking image layer ==
+image: json:{"encrypt.key-secret": "sec1", "driver": "IMGFMT", "file": {"driver": "file", "filename": "TEST_DIR/t.IMGFMT"}}
+file format: IMGFMT
+virtual size: 16M (16777216 bytes)
+backing file: TEST_DIR/t.IMGFMT.base
+Format specific information:
+    compat: 1.1
+    lazy refcounts: false
+    refcount bits: 16
+    encrypt:
+        ivgen alg: plain64
+        hash alg: sha256
+        cipher alg: aes-256
+        uuid: 00000000-0000-0000-0000-000000000000
+        format: luks
+        cipher mode: xts
+        slots:
+            [0]:
+                active: true
+                iters: 1024
+                key offset: 4096
+                stripes: 4000
+            [1]:
+                active: false
+                key offset: 262144
+            [2]:
+                active: false
+                key offset: 520192
+            [3]:
+                active: false
+                key offset: 778240
+            [4]:
+                active: false
+                key offset: 1036288
+            [5]:
+                active: false
+                key offset: 1294336
+            [6]:
+                active: false
+                key offset: 1552384
+            [7]:
+                active: false
+                key offset: 1810432
+        payload offset: 2068480
+        master key iters: 1024
+    corrupt: false
+*** done