qemu-img: Check for backing image if specified during create

Or, rather, force the open of a backing image if one was specified
for creation. Using a similar -unsafe option as rebase, allow qemu-img
to ignore the backing file validation if possible.

It may not always be possible, as in the existing case when a filesize
for the new image was not specified.

This is accomplished by shifting around the conditionals in
bdrv_img_create, such that a backing file is always opened unless we
provide BDRV_O_NO_BACKING. qemu-img is adjusted to pass this new flag
when -u is provided to create.

Sorry for the heinous looking diffstat, but it's mostly whitespace.

Inspired by: https://bugzilla.redhat.com/show_bug.cgi?id=1213786

Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

8 files changed, 10 insertions, 9 deletions

diff --git a/tests/qemu-iotests/082 b/tests/qemu-iotests/082
index ad1d9fa..d5c83d4 100755
--- a/tests/qemu-iotests/082
+++ b/tests/qemu-iotests/082
@@ -85,8 +85,8 @@ run_qemu_img create -f $IMGFMT -o cluster_size=4k -o help "$TEST_IMG" $size
 run_qemu_img create -f $IMGFMT -o cluster_size=4k -o \? "$TEST_IMG" $size
 
 # Looks like a help option, but is part of the backing file name
-run_qemu_img create -f $IMGFMT -o backing_file="$TEST_IMG",,help "$TEST_IMG" $size
-run_qemu_img create -f $IMGFMT -o backing_file="$TEST_IMG",,\? "$TEST_IMG" $size
+run_qemu_img create -f $IMGFMT -u -o backing_file="$TEST_IMG",,help "$TEST_IMG" $size
+run_qemu_img create -f $IMGFMT -u -o backing_file="$TEST_IMG",,\? "$TEST_IMG" $size
 
 # Try to trick qemu-img into creating escaped commas
 run_qemu_img create -f $IMGFMT -o backing_file="$TEST_IMG", -o help "$TEST_IMG" $size
diff --git a/tests/qemu-iotests/082.out b/tests/qemu-iotests/082.out
index dbed67f..1527fbe 100644
--- a/tests/qemu-iotests/082.out
+++ b/tests/qemu-iotests/082.out
@@ -210,10 +210,10 @@ lazy_refcounts   Postpone refcount updates
 refcount_bits    Width of a reference count entry in bits
 nocow            Turn off copy-on-write (valid only on btrfs)
 
-Testing: create -f qcow2 -o backing_file=TEST_DIR/t.qcow2,,help TEST_DIR/t.qcow2 128M
+Testing: create -f qcow2 -u -o backing_file=TEST_DIR/t.qcow2,,help TEST_DIR/t.qcow2 128M
 Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 backing_file=TEST_DIR/t.qcow2,,help cluster_size=65536 lazy_refcounts=off refcount_bits=16
 
-Testing: create -f qcow2 -o backing_file=TEST_DIR/t.qcow2,,? TEST_DIR/t.qcow2 128M
+Testing: create -f qcow2 -u -o backing_file=TEST_DIR/t.qcow2,,? TEST_DIR/t.qcow2 128M
 Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 size=134217728 backing_file=TEST_DIR/t.qcow2,,? cluster_size=65536 lazy_refcounts=off refcount_bits=16
 
 Testing: create -f qcow2 -o backing_file=TEST_DIR/t.qcow2, -o help TEST_DIR/t.qcow2 128M
diff --git a/tests/qemu-iotests/085 b/tests/qemu-iotests/085
index b97adcd..71efe50 100755
--- a/tests/qemu-iotests/085
+++ b/tests/qemu-iotests/085
@@ -104,7 +104,7 @@ function add_snapshot_image()
 {
     base_image="${TEST_DIR}/$((${1}-1))-${snapshot_virt0}"
     snapshot_file="${TEST_DIR}/${1}-${snapshot_virt0}"
-    _make_test_img -b "${base_image}" "$size"
+    _make_test_img -u -b "${base_image}" "$size"
     mv "${TEST_IMG}" "${snapshot_file}"
     do_blockdev_add "$1" "'backing': '', " "${snapshot_file}"
 }
diff --git a/tests/qemu-iotests/111.out b/tests/qemu-iotests/111.out
index 683c01a..5279c46 100644
--- a/tests/qemu-iotests/111.out
+++ b/tests/qemu-iotests/111.out
@@ -1,3 +1,4 @@
 QA output created by 111
 qemu-img: TEST_DIR/t.IMGFMT: Could not open 'TEST_DIR/t.IMGFMT.inexistent': No such file or directory
+Could not open backing image to determine size.
 *** done
diff --git a/tests/qemu-iotests/139 b/tests/qemu-iotests/139
index 175d8f0..9ff51d9 100644
--- a/tests/qemu-iotests/139
+++ b/tests/qemu-iotests/139
@@ -65,7 +65,7 @@ class TestBlockdevDel(iotests.QMPTestCase):
     # Add a BlockDriverState that will be used as overlay for the base_img BDS
     def addBlockDriverStateOverlay(self, node):
         self.checkBlockDriverState(node, False)
-        iotests.qemu_img('create', '-f', iotests.imgfmt,
+        iotests.qemu_img('create', '-u', '-f', iotests.imgfmt,
                          '-b', base_img, new_img, '1M')
         opts = {'driver': iotests.imgfmt,
                 'node-name': node,
diff --git a/tests/qemu-iotests/156 b/tests/qemu-iotests/156
index d799b73..2c4a06e 100755
--- a/tests/qemu-iotests/156
+++ b/tests/qemu-iotests/156
@@ -66,7 +66,7 @@ _send_qemu_cmd $QEMU_HANDLE \
     'return'
 
 # Create snapshot
-TEST_IMG="$TEST_IMG.overlay" _make_test_img -b "$TEST_IMG" 1M
+TEST_IMG="$TEST_IMG.overlay" _make_test_img -u -b "$TEST_IMG" 1M
 _send_qemu_cmd $QEMU_HANDLE \
     "{ 'execute': 'blockdev-snapshot-sync',
        'arguments': { 'device': 'source',
diff --git a/tests/qemu-iotests/158 b/tests/qemu-iotests/158
index 823c120..24ac600 100755
--- a/tests/qemu-iotests/158
+++ b/tests/qemu-iotests/158
@@ -66,7 +66,7 @@ echo "== verify pattern =="
 $QEMU_IO --object $SECRET -c "read -P 0xa 0 $size" --image-opts $IMGSPECBASE | _filter_qemu_io | _filter_testdir
 
 echo "== create overlay =="
-_make_test_img --object $SECRET -o "encryption=on,encrypt.key-secret=sec0" -b "$TEST_IMG_BASE" $size
+_make_test_img -u --object $SECRET -o "encryption=on,encrypt.key-secret=sec0" -b "$TEST_IMG_BASE" $size
 
 echo
 echo "== writing part of a cluster =="
diff --git a/tests/qemu-iotests/189 b/tests/qemu-iotests/189
index 54ad980..e695475 100755
--- a/tests/qemu-iotests/189
+++ b/tests/qemu-iotests/189
@@ -66,7 +66,7 @@ echo "== verify pattern =="
 $QEMU_IO --object $SECRET0 -c "read -P 0xa 0 $size" --image-opts $IMGSPECBASE | _filter_qemu_io | _filter_testdir
 
 echo "== create overlay =="
-_make_test_img --object $SECRET1 -o "encrypt.format=luks,encrypt.key-secret=sec1,encrypt.iter-time=10" -b "$TEST_IMG_BASE" $size
+_make_test_img --object $SECRET1 -o "encrypt.format=luks,encrypt.key-secret=sec1,encrypt.iter-time=10" -u -b "$TEST_IMG_BASE" $size
 
 echo
 echo "== writing part of a cluster =="