Merge remote-tracking branch 'kwolf/tags/for-upstream' into staging

Block layer patches # gpg: Signature made Thu 11 May 2017 10:31:37 AM EDT # gpg: using RSA key 0x7F09B272C88F2FD6 # gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" # Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6 * kwolf/tags/for-upstream: (58 commits) MAINTAINERS: Add qemu-progress to the block layer qcow2: Discard/zero clusters by byte count qcow2: Assert that cluster operations are aligned qcow2: Optimize write zero of unaligned tail cluster iotests: Add test 179 to cover write zeroes with unmap iotests: Improve _filter_qemu_img_map qcow2: Optimize zero_single_l2() to minimize L2 churn qcow2: Make distinction between zero cluster types obvious qcow2: Name typedef for cluster type qcow2: Correctly report status of preallocated zero clusters block: Update comments on BDRV_BLOCK_* meanings qcow2: Use consistent switch indentation qcow2: Nicer variable names in qcow2_update_snapshot_refcount() tests: Add coverage for recent block geometry fixes blkdebug: Add ability to override unmap geometries blkdebug: Simplify override logic blkdebug: Add pass-through write_zero and discard support blkdebug: Refactor error injection blkdebug: Sanity check block layer guarantees qemu-io: Switch 'map' output to byte-based reporting ... Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
author: Stefan Hajnoczi <stefanha@redhat.com> 2017-05-12 09:29:49 -0400
committer: Stefan Hajnoczi <stefanha@redhat.com> 2017-05-12 10:39:08 -0400
commit: 3753e255da8f6a654c3e7b650a2d27734bec15f9 (patch)
tree: e2cb28dba28a48ecb3c9912900f74c861620d03a /tests
parent: ecc1f5adeec4e3324d1b695a7c54e3967c526949 (diff)
parent: d541e201bd3ad888f02abeddf0e14f7b0c126529 (diff)
36 files changed, 1786 insertions, 153 deletions
diff --git a/tests/drive_del-test.c b/tests/drive_del-test.c
index 121b9c917e..2175139abb 100644
--- a/tests/drive_del-test.c
+++ b/tests/drive_del-test.c
@@ -92,7 +92,7 @@ static void test_after_failed_device_add(void)
 static void test_drive_del_device_del(void)
 {
     /* Start with a drive used by a device that unplugs instantaneously */
-    qtest_start("-drive if=none,id=drive0,file=/dev/null,format=raw"
+    qtest_start("-drive if=none,id=drive0,file=null-co://,format=raw"
                 " -device virtio-scsi-pci"
                 " -device scsi-hd,drive=drive0,id=dev0");
 
diff --git a/tests/nvme-test.c b/tests/nvme-test.c
index c8bece4434..7674a446e4 100644
--- a/tests/nvme-test.c
+++ b/tests/nvme-test.c
@@ -22,7 +22,7 @@ int main(int argc, char **argv)
     g_test_init(&argc, &argv, NULL);
     qtest_add_func("/nvme/nop", nop);
 
-    qtest_start("-drive id=drv0,if=none,file=/dev/null,format=raw "
+    qtest_start("-drive id=drv0,if=none,file=null-co://,format=raw "
                 "-device nvme,drive=drv0,serial=foo");
     ret = g_test_run();
 
diff --git a/tests/qemu-iotests/019.out b/tests/qemu-iotests/019.out
index 0124264975..17a7c036b9 100644
--- a/tests/qemu-iotests/019.out
+++ b/tests/qemu-iotests/019.out
@@ -542,8 +542,8 @@ Testing conversion with -B TEST_DIR/t.IMGFMT.base
 
 Checking if backing clusters are allocated when they shouldn't
 
-0/128 sectors allocated at offset 1 MiB
-0/128 sectors allocated at offset 4.001 GiB
+0/65536 bytes allocated at offset 1 MiB
+0/65536 bytes allocated at offset 4.001 GiB
 Reading
 
 === IO: pattern 42
@@ -1086,8 +1086,8 @@ Testing conversion with -o backing_file=TEST_DIR/t.IMGFMT.base
 
 Checking if backing clusters are allocated when they shouldn't
 
-0/128 sectors allocated at offset 1 MiB
-0/128 sectors allocated at offset 4.001 GiB
+0/65536 bytes allocated at offset 1 MiB
+0/65536 bytes allocated at offset 4.001 GiB
 Reading
 
 === IO: pattern 42
diff --git a/tests/qemu-iotests/030 b/tests/qemu-iotests/030
index 0d472d5f27..e00c11b804 100755
--- a/tests/qemu-iotests/030
+++ b/tests/qemu-iotests/030
@@ -63,8 +63,8 @@ class TestSingleDrive(iotests.QMPTestCase):
     def test_stream_intermediate(self):
         self.assert_no_active_block_jobs()
 
-        self.assertNotEqual(qemu_io('-f', 'raw', '-c', 'map', backing_img),
-                            qemu_io('-f', iotests.imgfmt, '-c', 'map', mid_img),
+        self.assertNotEqual(qemu_io('-f', 'raw', '-rU', '-c', 'map', backing_img),
+                            qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', mid_img),
                             'image file map matches backing file before streaming')
 
         result = self.vm.qmp('block-stream', device='mid', job_id='stream-mid')
@@ -114,7 +114,7 @@ class TestSingleDrive(iotests.QMPTestCase):
         self.assert_no_active_block_jobs()
 
         # The image map is empty before the operation
-        empty_map = qemu_io('-f', iotests.imgfmt, '-c', 'map', test_img)
+        empty_map = qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', test_img)
 
         # This is a no-op: no data should ever be copied from the base image
         result = self.vm.qmp('block-stream', device='drive0', base=mid_img)
@@ -197,8 +197,8 @@ class TestParallelOps(iotests.QMPTestCase):
 
         # Check that the maps don't match before the streaming operations
         for i in range(2, self.num_imgs, 2):
-            self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-c', 'map', self.imgs[i]),
-                                qemu_io('-f', iotests.imgfmt, '-c', 'map', self.imgs[i-1]),
+            self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', self.imgs[i]),
+                                qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', self.imgs[i-1]),
                                 'image file map matches backing file before streaming')
 
         # Create all streaming jobs
@@ -351,8 +351,8 @@ class TestParallelOps(iotests.QMPTestCase):
     def test_stream_base_node_name(self):
         self.assert_no_active_block_jobs()
 
-        self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-c', 'map', self.imgs[4]),
-                            qemu_io('-f', iotests.imgfmt, '-c', 'map', self.imgs[3]),
+        self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', self.imgs[4]),
+                            qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', self.imgs[3]),
                             'image file map matches backing file before streaming')
 
         # Error: the base node does not exist
@@ -422,8 +422,8 @@ class TestQuorum(iotests.QMPTestCase):
         if not iotests.supports_quorum():
             return
 
-        self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-c', 'map', self.children[0]),
-                            qemu_io('-f', iotests.imgfmt, '-c', 'map', self.backing[0]),
+        self.assertNotEqual(qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', self.children[0]),
+                            qemu_io('-f', iotests.imgfmt, '-rU', '-c', 'map', self.backing[0]),
                             'image file map matches backing file before streaming')
 
         self.assert_no_active_block_jobs()
diff --git a/tests/qemu-iotests/046 b/tests/qemu-iotests/046
index e528b67cc6..f2ebecf24c 100755
--- a/tests/qemu-iotests/046
+++ b/tests/qemu-iotests/046
@@ -192,7 +192,7 @@ echo "== Verify image content =="
 
 function verify_io()
 {
-    if ($QEMU_IMG info -f "$IMGFMT" "$TEST_IMG" | grep "compat: 0.10" > /dev/null); then
+    if ($QEMU_IMG info -U -f "$IMGFMT" "$TEST_IMG" | grep "compat: 0.10" > /dev/null); then
         # For v2 images, discarded clusters are read from the backing file
         # Keep the variable empty so that the backing file value can be used as
         # the default below
diff --git a/tests/qemu-iotests/055 b/tests/qemu-iotests/055
index aafcd249f6..ba4da65c77 100755
--- a/tests/qemu-iotests/055
+++ b/tests/qemu-iotests/055
@@ -458,17 +458,18 @@ class TestDriveCompression(iotests.QMPTestCase):
         except OSError:
             pass
 
-    def do_prepare_drives(self, fmt, args):
+    def do_prepare_drives(self, fmt, args, attach_target):
         self.vm = iotests.VM().add_drive(test_img)
 
         qemu_img('create', '-f', fmt, blockdev_target_img,
                  str(TestDriveCompression.image_len), *args)
-        self.vm.add_drive(blockdev_target_img, format=fmt, interface="none")
+        if attach_target:
+            self.vm.add_drive(blockdev_target_img, format=fmt, interface="none")
 
         self.vm.launch()
 
-    def do_test_compress_complete(self, cmd, format, **args):
-        self.do_prepare_drives(format['type'], format['args'])
+    def do_test_compress_complete(self, cmd, format, attach_target, **args):
+        self.do_prepare_drives(format['type'], format['args'], attach_target)
 
         self.assert_no_active_block_jobs()
 
@@ -484,15 +485,16 @@ class TestDriveCompression(iotests.QMPTestCase):
 
     def test_complete_compress_drive_backup(self):
         for format in TestDriveCompression.fmt_supports_compression:
-            self.do_test_compress_complete('drive-backup', format,
+            self.do_test_compress_complete('drive-backup', format, False,
                                            target=blockdev_target_img, mode='existing')
 
     def test_complete_compress_blockdev_backup(self):
         for format in TestDriveCompression.fmt_supports_compression:
-            self.do_test_compress_complete('blockdev-backup', format, target='drive1')
+            self.do_test_compress_complete('blockdev-backup', format, True,
+                                           target='drive1')
 
-    def do_test_compress_cancel(self, cmd, format, **args):
-        self.do_prepare_drives(format['type'], format['args'])
+    def do_test_compress_cancel(self, cmd, format, attach_target, **args):
+        self.do_prepare_drives(format['type'], format['args'], attach_target)
 
         self.assert_no_active_block_jobs()
 
@@ -506,15 +508,16 @@ class TestDriveCompression(iotests.QMPTestCase):
 
     def test_compress_cancel_drive_backup(self):
         for format in TestDriveCompression.fmt_supports_compression:
-            self.do_test_compress_cancel('drive-backup', format,
+            self.do_test_compress_cancel('drive-backup', format, False,
                                          target=blockdev_target_img, mode='existing')
 
     def test_compress_cancel_blockdev_backup(self):
        for format in TestDriveCompression.fmt_supports_compression:
-            self.do_test_compress_cancel('blockdev-backup', format, target='drive1')
+            self.do_test_compress_cancel('blockdev-backup', format, True,
+                                         target='drive1')
 
-    def do_test_compress_pause(self, cmd, format, **args):
-        self.do_prepare_drives(format['type'], format['args'])
+    def do_test_compress_pause(self, cmd, format, attach_target, **args):
+        self.do_prepare_drives(format['type'], format['args'], attach_target)
 
         self.assert_no_active_block_jobs()
 
@@ -546,12 +549,13 @@ class TestDriveCompression(iotests.QMPTestCase):
 
     def test_compress_pause_drive_backup(self):
         for format in TestDriveCompression.fmt_supports_compression:
-            self.do_test_compress_pause('drive-backup', format,
+            self.do_test_compress_pause('drive-backup', format, False,
                                         target=blockdev_target_img, mode='existing')
 
     def test_compress_pause_blockdev_backup(self):
         for format in TestDriveCompression.fmt_supports_compression:
-            self.do_test_compress_pause('blockdev-backup', format, target='drive1')
+            self.do_test_compress_pause('blockdev-backup', format, True,
+                                        target='drive1')
 
 if __name__ == '__main__':
     iotests.main(supported_fmts=['raw', 'qcow2'])
diff --git a/tests/qemu-iotests/060.out b/tests/qemu-iotests/060.out
index 5d40206ef8..9e8f5b9d79 100644
--- a/tests/qemu-iotests/060.out
+++ b/tests/qemu-iotests/060.out
@@ -135,7 +135,7 @@ qemu-img: Error while amending options: Input/output error
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-qcow2: Marking image as corrupt: Data cluster offset 0x52a00 unaligned (L2 offset: 0x40000, L2 index: 0); further corruption events will be suppressed
+qcow2: Marking image as corrupt: Cluster allocation offset 0x52a00 unaligned (L2 offset: 0x40000, L2 index: 0); further corruption events will be suppressed
 read failed: Input/output error
 
 === Testing unaligned pre-allocated zero cluster ===
@@ -166,7 +166,7 @@ discard 65536/65536 bytes at offset 0
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-qcow2: Image is corrupt: Data cluster offset 0x52a00 unaligned (L2 offset: 0x40000, L2 index: 0); further non-fatal corruption events will be suppressed
+qcow2: Image is corrupt: Cluster allocation offset 0x52a00 unaligned (L2 offset: 0x40000, L2 index: 0); further non-fatal corruption events will be suppressed
 read failed: Input/output error
 read failed: Input/output error
 
@@ -176,7 +176,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 wrote 131072/131072 bytes at offset 0
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 qcow2: Image is corrupt: Cannot free unaligned cluster 0x52a00; further non-fatal corruption events will be suppressed
-qcow2: Marking image as corrupt: Data cluster offset 0x62a00 unaligned (L2 offset: 0x40000, L2 index: 0x1); further corruption events will be suppressed
+qcow2: Marking image as corrupt: Cluster allocation offset 0x62a00 unaligned (L2 offset: 0x40000, L2 index: 0x1); further corruption events will be suppressed
 discard 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read failed: Input/output error
diff --git a/tests/qemu-iotests/066 b/tests/qemu-iotests/066
index c2116a3088..8638217736 100755
--- a/tests/qemu-iotests/066
+++ b/tests/qemu-iotests/066
@@ -1,6 +1,6 @@
 #!/bin/bash
 #
-# Test case for discarding preallocated zero clusters in qcow2
+# Test case for preallocated zero clusters in qcow2
 #
 # Copyright (C) 2013 Red Hat, Inc.
 #
@@ -55,8 +55,134 @@ _make_test_img $IMG_SIZE
 $QEMU_IO -c "write 0 256k" -c "write -z 0 256k" -c "write 64M 512" \
 	 -c "discard 0 $IMG_SIZE" -c "read -P 0 0 $IMG_SIZE" "$TEST_IMG" \
          | _filter_qemu_io
+
 # Check the image (there shouldn't be any leaks)
 _check_test_img
+# Map the image (we want all clusters to be gone)
+$QEMU_IMG map "$TEST_IMG"
+
+_cleanup_test_img
+
+
+echo
+echo '=== Writing to preallocated zero clusters ==='
+echo
+
+_make_test_img $IMG_SIZE
+
+# Create data clusters (not aligned to an L2 table)
+$QEMU_IO -c 'write -P 42 1M 256k' "$TEST_IMG" | _filter_qemu_io
+orig_map=$($QEMU_IMG map --output=json "$TEST_IMG")
+
+# Convert the data clusters to preallocated zero clusters
+$QEMU_IO -c 'write -z 1M 256k' "$TEST_IMG" | _filter_qemu_io
+
+# Now write to them (with a COW needed for the head and tail)
+$QEMU_IO -c "write -P 23 $(((1024 + 32) * 1024)) 192k" "$TEST_IMG" \
+    | _filter_qemu_io
+
+# Check metadata correctness
+_check_test_img
+
+# Check data correctness
+$QEMU_IO -c "read -P  0 $(( 1024             * 1024)) 32k" \
+         -c "read -P 23 $(((1024 + 32)       * 1024)) 192k" \
+         -c "read -P  0 $(((1024 + 32 + 192) * 1024)) 32k" \
+         "$TEST_IMG" \
+         | _filter_qemu_io
+
+# Check that we have actually reused the original area
+new_map=$($QEMU_IMG map --output=json "$TEST_IMG")
+if [ "$new_map" = "$orig_map" ]; then
+    echo 'Successfully reused original clusters.'
+else
+    echo 'Failed to reuse original clusters.'
+    echo 'Original map:'
+    echo "$orig_map"
+    echo 'New map:'
+    echo "$new_map"
+fi
+
+_cleanup_test_img
+
+
+echo
+echo '=== Writing to a snapshotted preallocated zero cluster ==='
+echo
+
+_make_test_img 64k
+
+# Create a preallocated zero cluster
+$QEMU_IO -c 'write -P 42 0 64k' -c 'write -z 0 64k' "$TEST_IMG" \
+    | _filter_qemu_io
+
+# Snapshot it
+$QEMU_IMG snapshot -c foo "$TEST_IMG"
+
+# Write to the cluster
+$QEMU_IO -c 'write -P 23 0 64k' "$TEST_IMG" | _filter_qemu_io
+
+# Check metadata correctness
+_check_test_img
+
+# Check data correctness
+$QEMU_IO -c 'read -P 23 0 64k' "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG snapshot -a foo "$TEST_IMG"
+$QEMU_IO -c 'read -P 0 0 64k' "$TEST_IMG" | _filter_qemu_io
+
+_cleanup_test_img
+
+
+echo
+echo '=== Consecutive write to a preallocated zero cluster ==='
+echo
+
+_make_test_img 192k
+
+# Create three normal clusters
+$QEMU_IO -c 'write -P 42 0 192k' "$TEST_IMG" | _filter_qemu_io
+orig_map=$($QEMU_IMG map --output=json "$TEST_IMG")
+
+# Make the middle cluster a preallocated zero cluster
+$QEMU_IO -c 'write -z 64k 64k' "$TEST_IMG" | _filter_qemu_io
+
+# Try to overwrite everything: This should reuse the whole range. To test that
+# this only issues a single continuous write request, use blkdebug.
+$QEMU_IO -c 'write -P 42 0 192k' \
+    "json:{
+        'driver': '$IMGFMT',
+        'file': {
+            'driver': 'blkdebug',
+            'image.filename': '$TEST_IMG',
+            'set-state': [{
+                'event': 'write_aio',
+                'new_state': 2
+            }],
+            'inject-error': [{
+                'event': 'write_aio',
+                'state': 2
+            }]
+        }
+    }" \
+    | _filter_qemu_io
+
+# Check metadata correctness
+_check_test_img
+
+# Check that we have actually reused the original area
+new_map=$($QEMU_IMG map --output=json "$TEST_IMG")
+if [ "$new_map" = "$orig_map" ]; then
+    echo 'Successfully reused original clusters.'
+else
+    echo 'Failed to reuse original clusters.'
+    echo 'Original map:'
+    echo "$orig_map"
+    echo 'New map:'
+    echo "$new_map"
+fi
+
+_cleanup_test_img
+
 
 # success, all done
 echo "*** done"
diff --git a/tests/qemu-iotests/066.out b/tests/qemu-iotests/066.out
index 7c1f31a1b1..3d9da9bd0b 100644
--- a/tests/qemu-iotests/066.out
+++ b/tests/qemu-iotests/066.out
@@ -14,4 +14,50 @@ discard 67109376/67109376 bytes at offset 0
 read 67109376/67109376 bytes at offset 0
 64 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 No errors were found on the image.
+Offset          Length          Mapped to       File
+
+=== Writing to preallocated zero clusters ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67109376
+wrote 262144/262144 bytes at offset 1048576
+256 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 262144/262144 bytes at offset 1048576
+256 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 196608/196608 bytes at offset 1081344
+192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+No errors were found on the image.
+read 32768/32768 bytes at offset 1048576
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 196608/196608 bytes at offset 1081344
+192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 32768/32768 bytes at offset 1277952
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Successfully reused original clusters.
+
+=== Writing to a snapshotted preallocated zero cluster ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=65536
+wrote 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+No errors were found on the image.
+read 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+=== Consecutive write to a preallocated zero cluster ===
+
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=196608
+wrote 196608/196608 bytes at offset 0
+192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 196608/196608 bytes at offset 0
+192 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+No errors were found on the image.
+Successfully reused original clusters.
 *** done
diff --git a/tests/qemu-iotests/085 b/tests/qemu-iotests/085
index c53e97f067..b97adcd8db 100755
--- a/tests/qemu-iotests/085
+++ b/tests/qemu-iotests/085
@@ -45,7 +45,7 @@ _cleanup()
         rm -f "${TEST_DIR}/${i}-${snapshot_virt0}"
         rm -f "${TEST_DIR}/${i}-${snapshot_virt1}"
     done
-    rm -f "${TEST_IMG}.1" "${TEST_IMG}.2"
+    rm -f "${TEST_IMG}" "${TEST_IMG}.1" "${TEST_IMG}.2" "${TEST_IMG}.base"
 
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15
@@ -87,24 +87,26 @@ function create_group_snapshot()
 }
 
 # ${1}: unique identifier for the snapshot filename
-# ${2}: true: open backing images; false: don't open them (default)
+# ${2}: extra_params to the blockdev-add command
+# ${3}: filename
+function do_blockdev_add()
+{
+    cmd="{ 'execute': 'blockdev-add', 'arguments':
+           { 'driver': 'qcow2', 'node-name': 'snap_${1}', ${2}
+             'file':
+             { 'driver': 'file', 'filename': '${3}',
+               'node-name': 'file_${1}' } } }"
+    _send_qemu_cmd $h "${cmd}" "return"
+}
+
+# ${1}: unique identifier for the snapshot filename
 function add_snapshot_image()
 {
-    if [ "${2}" = "true" ]; then
-        extra_params=""
-    else
-        extra_params="'backing': '', "
-    fi
     base_image="${TEST_DIR}/$((${1}-1))-${snapshot_virt0}"
     snapshot_file="${TEST_DIR}/${1}-${snapshot_virt0}"
     _make_test_img -b "${base_image}" "$size"
     mv "${TEST_IMG}" "${snapshot_file}"
-    cmd="{ 'execute': 'blockdev-add', 'arguments':
-           { 'driver': 'qcow2', 'node-name': 'snap_${1}', ${extra_params}
-             'file':
-             { 'driver': 'file', 'filename': '${snapshot_file}',
-               'node-name': 'file_${1}' } } }"
-    _send_qemu_cmd $h "${cmd}" "return"
+    do_blockdev_add "$1" "'backing': '', " "${snapshot_file}"
 }
 
 # ${1}: unique identifier for the snapshot filename
@@ -222,7 +224,10 @@ echo === Invalid command - snapshot node has a backing image ===
 echo
 
 SNAPSHOTS=$((${SNAPSHOTS}+1))
-add_snapshot_image ${SNAPSHOTS} true
+
+TEST_IMG="$TEST_IMG.base" _make_test_img "$size"
+_make_test_img -b "${TEST_IMG}.base" "$size"
+do_blockdev_add ${SNAPSHOTS} "" "${TEST_IMG}"
 blockdev_snapshot ${SNAPSHOTS} error
 
 echo
diff --git a/tests/qemu-iotests/085.out b/tests/qemu-iotests/085.out
index 182acb42cf..a5d4cc3494 100644
--- a/tests/qemu-iotests/085.out
+++ b/tests/qemu-iotests/085.out
@@ -78,7 +78,8 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/
 
 === Invalid command - snapshot node has a backing image ===
 
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/12-snapshot-v0.IMGFMT
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/t.IMGFMT.base
 {"return": {}}
 {"error": {"class": "GenericError", "desc": "The snapshot already has a backing image"}}
 
diff --git a/tests/qemu-iotests/087 b/tests/qemu-iotests/087
index 9de57ddf6d..6d52f7d1b7 100755
--- a/tests/qemu-iotests/087
+++ b/tests/qemu-iotests/087
@@ -82,8 +82,7 @@ run_qemu -drive driver=$IMGFMT,id=disk,node-name=test-node,file="$TEST_IMG" <<EO
       "driver": "$IMGFMT",
       "node-name": "disk",
       "file": {
-          "driver": "file",
-          "filename": "$TEST_IMG"
+          "driver": "null-co"
       }
     }
   }
@@ -92,8 +91,7 @@ run_qemu -drive driver=$IMGFMT,id=disk,node-name=test-node,file="$TEST_IMG" <<EO
       "driver": "$IMGFMT",
       "node-name": "test-node",
       "file": {
-          "driver": "file",
-          "filename": "$TEST_IMG"
+          "driver": "null-co"
       }
     }
   }
diff --git a/tests/qemu-iotests/091 b/tests/qemu-iotests/091
index 32bbd56975..10ac4a8d73 100755
--- a/tests/qemu-iotests/091
+++ b/tests/qemu-iotests/091
@@ -95,7 +95,9 @@ echo "vm2: qemu process running successfully"
 echo "vm2: flush io, and quit"
 _send_qemu_cmd $h2 'qemu-io disk flush' "(qemu)"
 _send_qemu_cmd $h2 'quit' ""
+_send_qemu_cmd $h1 'quit' ""
 
+wait
 echo "Check image pattern"
 ${QEMU_IO} -c "read -P 0x22 0 4M" "${TEST_IMG}" | _filter_testdir | _filter_qemu_io
 
diff --git a/tests/qemu-iotests/102.out b/tests/qemu-iotests/102.out
index eecde16ad5..ccf172abd9 100644
--- a/tests/qemu-iotests/102.out
+++ b/tests/qemu-iotests/102.out
@@ -6,7 +6,7 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=65536
 wrote 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 Image resized.
-[                       0]      128/     128 sectors     allocated at offset 0 bytes (1)
+64 KiB (0x10000) bytes     allocated at offset 0 bytes (0x0)
 Offset          Length          Mapped to       File
 
 === Testing map on an image file truncated outside of qemu ===
@@ -17,5 +17,5 @@ wrote 65536/65536 bytes at offset 0
 Image resized.
 QEMU X.Y.Z monitor - type 'help' for more information
 (qemu) qemu-io drv0 map
-[                       0]      128/     128 sectors     allocated at offset 0 bytes (1)
+64 KiB (0x10000) bytes     allocated at offset 0 bytes (0x0)
 *** done
diff --git a/tests/qemu-iotests/122.out b/tests/qemu-iotests/122.out
index 9317d801ad..47d8656db8 100644
--- a/tests/qemu-iotests/122.out
+++ b/tests/qemu-iotests/122.out
@@ -112,7 +112,7 @@ read 3145728/3145728 bytes at offset 0
 3 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 63963136/63963136 bytes at offset 3145728
 61 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
 
 convert -c -S 0:
 read 3145728/3145728 bytes at offset 0
@@ -134,7 +134,7 @@ read 30408704/30408704 bytes at offset 3145728
 29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 33554432/33554432 bytes at offset 33554432
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
 
 convert -c -S 0 with source backing file:
 read 3145728/3145728 bytes at offset 0
@@ -152,7 +152,7 @@ read 30408704/30408704 bytes at offset 3145728
 29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 33554432/33554432 bytes at offset 33554432
 32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": 327680}]
+[{ "start": 0, "length": 67108864, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
 
 convert -c -S 0 -B ...
 read 3145728/3145728 bytes at offset 0
@@ -176,11 +176,11 @@ wrote 1024/1024 bytes at offset 17408
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
 convert -S 4k
-[{ "start": 0, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": 8192},
+[{ "start": 0, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 1024, "length": 7168, "depth": 0, "zero": true, "data": false},
-{ "start": 8192, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": 9216},
+{ "start": 8192, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 9216, "length": 8192, "depth": 0, "zero": true, "data": false},
-{ "start": 17408, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": 10240},
+{ "start": 17408, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 18432, "length": 67090432, "depth": 0, "zero": true, "data": false}]
 
 convert -c -S 4k
@@ -192,9 +192,9 @@ convert -c -S 4k
 { "start": 18432, "length": 67090432, "depth": 0, "zero": true, "data": false}]
 
 convert -S 8k
-[{ "start": 0, "length": 9216, "depth": 0, "zero": false, "data": true, "offset": 8192},
+[{ "start": 0, "length": 9216, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 9216, "length": 8192, "depth": 0, "zero": true, "data": false},
-{ "start": 17408, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": 17408},
+{ "start": 17408, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 18432, "length": 67090432, "depth": 0, "zero": true, "data": false}]
 
 convert -c -S 8k
diff --git a/tests/qemu-iotests/146.out b/tests/qemu-iotests/146.out
index 4f334d86bc..db6b296b9e 100644
--- a/tests/qemu-iotests/146.out
+++ b/tests/qemu-iotests/146.out
@@ -2,39 +2,39 @@ QA output created by 146
 
 === Testing VPC Autodetect ===
 
-[                       0]  266334240/ 266334240 sectors not allocated at offset 0 bytes (0)
+126.998 GiB (0x1fbfe04000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing VPC with current_size force ===
 
-[                       0]  266338304/ 266338304 sectors not allocated at offset 0 bytes (0)
+127 GiB (0x1fc0000000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing VPC with chs force ===
 
-[                       0]  266334240/ 266334240 sectors not allocated at offset 0 bytes (0)
+126.998 GiB (0x1fbfe04000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing Hyper-V Autodetect ===
 
-[                       0]  266338304/ 266338304 sectors not allocated at offset 0 bytes (0)
+127 GiB (0x1fc0000000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing Hyper-V with current_size force ===
 
-[                       0]  266338304/ 266338304 sectors not allocated at offset 0 bytes (0)
+127 GiB (0x1fc0000000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing Hyper-V with chs force ===
 
-[                       0]  266334240/ 266334240 sectors not allocated at offset 0 bytes (0)
+126.998 GiB (0x1fbfe04000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing d2v Autodetect ===
 
-[                       0]   514560/  514560 sectors     allocated at offset 0 bytes (1)
+251.250 MiB (0xfb40000) bytes     allocated at offset 0 bytes (0x0)
 
 === Testing d2v with current_size force ===
 
-[                       0]   514560/  514560 sectors     allocated at offset 0 bytes (1)
+251.250 MiB (0xfb40000) bytes     allocated at offset 0 bytes (0x0)
 
 === Testing d2v with chs force ===
 
-[                       0]   514560/  514560 sectors     allocated at offset 0 bytes (1)
+251.250 MiB (0xfb40000) bytes     allocated at offset 0 bytes (0x0)
 
 === Testing Image create, default ===
 
@@ -42,15 +42,15 @@ Formatting 'TEST_DIR/IMGFMT-create-test.IMGFMT', fmt=IMGFMT size=4294967296
 
 === Read created image, default opts ====
 
-[                       0]  8389584/ 8389584 sectors not allocated at offset 0 bytes (0)
+4 GiB (0x10007a000) bytes not allocated at offset 0 bytes (0x0)
 
 === Read created image, force_size_calc=chs ====
 
-[                       0]  8389584/ 8389584 sectors not allocated at offset 0 bytes (0)
+4 GiB (0x10007a000) bytes not allocated at offset 0 bytes (0x0)
 
 === Read created image, force_size_calc=current_size ====
 
-[                       0]  8389584/ 8389584 sectors not allocated at offset 0 bytes (0)
+4 GiB (0x10007a000) bytes not allocated at offset 0 bytes (0x0)
 
 === Testing Image create, force_size ===
 
@@ -58,13 +58,13 @@ Formatting 'TEST_DIR/IMGFMT-create-test.IMGFMT', fmt=IMGFMT size=4294967296 forc
 
 === Read created image, default opts ====
 
-[                       0]  8388608/ 8388608 sectors not allocated at offset 0 bytes (0)
+4 GiB (0x100000000) bytes not allocated at offset 0 bytes (0x0)
 
 === Read created image, force_size_calc=chs ====
 
-[                       0]  8388608/ 8388608 sectors not allocated at offset 0 bytes (0)
+4 GiB (0x100000000) bytes not allocated at offset 0 bytes (0x0)
 
 === Read created image, force_size_calc=current_size ====
 
-[                       0]  8388608/ 8388608 sectors not allocated at offset 0 bytes (0)
+4 GiB (0x100000000) bytes not allocated at offset 0 bytes (0x0)
 *** done
diff --git a/tests/qemu-iotests/153 b/tests/qemu-iotests/153
new file mode 100755
index 0000000000..0b45d78ea3
--- /dev/null
+++ b/tests/qemu-iotests/153
@@ -0,0 +1,233 @@
+#!/bin/bash
+#
+# Test image locking
+#
+# Copyright 2016, 2017 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=famz@redhat.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+here="$PWD"
+tmp=/tmp/$$
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+    rm -f "${TEST_IMG}.base"
+    rm -f "${TEST_IMG}.convert"
+    rm -f "${TEST_IMG}.a"
+    rm -f "${TEST_IMG}.b"
+    rm -f "${TEST_IMG}.lnk"
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+. ./common.qemu
+
+size=32M
+
+_check_ofd()
+{
+    _make_test_img $size >/dev/null
+    if $QEMU_IMG_PROG info --image-opts "driver=file,locking=on,filename=$TEST_IMG" 2>&1 |
+        grep -q 'falling back to POSIX file'; then
+        return 1
+    else
+        return 0
+    fi
+}
+
+_check_ofd || _notrun "OFD lock not available"
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+_run_cmd()
+{
+    echo
+    (echo "$@"; "$@" 2>&1 1>/dev/null) | _filter_testdir
+}
+
+function _do_run_qemu()
+{
+    (
+        if ! test -t 0; then
+            while read cmd; do
+                echo $cmd
+            done
+        fi
+        echo quit
+    ) | $QEMU -nographic -monitor stdio -serial none "$@" 1>/dev/null
+}
+
+function _run_qemu_with_images()
+{
+    _do_run_qemu \
+        $(for i in $@; do echo "-drive if=none,file=$i"; done) 2>&1 \
+        | _filter_testdir | _filter_qemu
+}
+
+echo "== readonly=off,force-share=on should be rejected =="
+_run_qemu_with_images null-co://,readonly=off,force-share=on
+
+for opts1 in "" "read-only=on" "read-only=on,force-share=on"; do
+    echo
+    echo "== Creating base image =="
+    TEST_IMG="${TEST_IMG}.base" _make_test_img $size
+
+    echo
+    echo "== Creating test image =="
+    $QEMU_IMG create -f $IMGFMT "${TEST_IMG}" -b ${TEST_IMG}.base | _filter_img_create
+
+    echo
+    echo "== Launching QEMU, opts: '$opts1' =="
+    _launch_qemu -drive file="${TEST_IMG}",if=none,$opts1
+    h=$QEMU_HANDLE
+
+    for opts2 in "" "read-only=on" "read-only=on,force-share=on"; do
+        echo
+        echo "== Launching another QEMU, opts: '$opts2' =="
+        echo "quit" | \
+            $QEMU -nographic -monitor stdio \
+            -drive file="${TEST_IMG}",if=none,$opts2 2>&1 1>/dev/null | \
+            _filter_testdir | _filter_qemu
+    done
+
+    for L in "" "-U"; do
+
+        echo
+        echo "== Running utility commands $L =="
+        _run_cmd $QEMU_IO $L -c "read 0 512" "${TEST_IMG}"
+        _run_cmd $QEMU_IO $L -r -c "read 0 512" "${TEST_IMG}"
+        _run_cmd $QEMU_IO -c "open $L ${TEST_IMG}" -c "read 0 512"
+        _run_cmd $QEMU_IO -c "open -r $L ${TEST_IMG}" -c "read 0 512"
+        _run_cmd $QEMU_IMG info        $L "${TEST_IMG}"
+        _run_cmd $QEMU_IMG check       $L "${TEST_IMG}"
+        _run_cmd $QEMU_IMG compare     $L "${TEST_IMG}" "${TEST_IMG}"
+        _run_cmd $QEMU_IMG map         $L "${TEST_IMG}"
+        _run_cmd $QEMU_IMG amend -o "" $L "${TEST_IMG}"
+        _run_cmd $QEMU_IMG commit      $L "${TEST_IMG}"
+        _run_cmd $QEMU_IMG resize      $L "${TEST_IMG}" $size
+        _run_cmd $QEMU_IMG rebase      $L "${TEST_IMG}" -b "${TEST_IMG}.base"
+        _run_cmd $QEMU_IMG snapshot -l $L "${TEST_IMG}"
+        _run_cmd $QEMU_IMG convert     $L "${TEST_IMG}" "${TEST_IMG}.convert"
+        _run_cmd $QEMU_IMG dd          $L if="${TEST_IMG}" of="${TEST_IMG}.convert" bs=512 count=1
+        _run_cmd $QEMU_IMG bench       $L -c 1 "${TEST_IMG}"
+        _run_cmd $QEMU_IMG bench       $L -w -c 1 "${TEST_IMG}"
+    done
+    _send_qemu_cmd $h "{ 'execute': 'quit', }" ""
+    echo
+    echo "Round done"
+    _cleanup_qemu
+done
+
+for opt1 in $test_opts; do
+    for opt2 in $test_opts; do
+        echo
+        echo "== Two devices with the same image ($opt1 - $opt2) =="
+        _run_qemu_with_images "${TEST_IMG},$opt1" "${TEST_IMG},$opt2"
+    done
+done
+
+echo "== Creating ${TEST_IMG}.[abc] ==" | _filter_testdir
+(
+    $QEMU_IMG create -f qcow2 "${TEST_IMG}.a" -b "${TEST_IMG}"
+    $QEMU_IMG create -f qcow2 "${TEST_IMG}.b" -b "${TEST_IMG}"
+    $QEMU_IMG create -f qcow2 "${TEST_IMG}.c" -b "${TEST_IMG}.b"
+) | _filter_img_create
+
+echo
+echo "== Two devices sharing the same file in backing chain =="
+_run_qemu_with_images "${TEST_IMG}.a" "${TEST_IMG}.b"
+_run_qemu_with_images "${TEST_IMG}.a" "${TEST_IMG}.c"
+
+echo
+echo "== Backing image also as an active device =="
+_run_qemu_with_images "${TEST_IMG}.a" "${TEST_IMG}"
+
+echo
+echo "== Backing image also as an active device (ro) =="
+_run_qemu_with_images "${TEST_IMG}.a" "${TEST_IMG},readonly=on"
+
+echo
+echo "== Symbolic link =="
+rm -f "${TEST_IMG}.lnk" &>/dev/null
+ln -s ${TEST_IMG} "${TEST_IMG}.lnk" || echo "Failed to create link"
+_run_qemu_with_images "${TEST_IMG}.lnk" "${TEST_IMG}"
+
+echo
+echo "== Closing an image should unlock it =="
+_launch_qemu
+
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'qmp_capabilities' }" \
+    'return'
+
+echo "Adding drive"
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': { 'command-line': 'drive_add 0 if=none,id=d0,file=${TEST_IMG}' } }" \
+    ""
+
+_run_cmd $QEMU_IO "${TEST_IMG}" -c 'write 0 512'
+
+echo "Closing drive"
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': { 'command-line': 'drive_del d0' } }" \
+    ""
+
+_run_cmd $QEMU_IO "${TEST_IMG}" -c 'write 0 512'
+
+echo "Adding two and closing one"
+for d in d0 d1; do
+    _send_qemu_cmd $QEMU_HANDLE \
+        "{ 'execute': 'human-monitor-command',
+           'arguments': { 'command-line': 'drive_add 0 if=none,id=$d,file=${TEST_IMG},readonly=on' } }" \
+        ""
+done
+
+_run_cmd $QEMU_IMG info "${TEST_IMG}"
+
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': { 'command-line': 'drive_del d0' } }" \
+    ""
+
+_run_cmd $QEMU_IO "${TEST_IMG}" -c 'write 0 512'
+
+echo "Closing the other"
+_send_qemu_cmd $QEMU_HANDLE \
+    "{ 'execute': 'human-monitor-command',
+       'arguments': { 'command-line': 'drive_del d1' } }" \
+    ""
+
+_run_cmd $QEMU_IO "${TEST_IMG}" -c 'write 0 512'
+
+_cleanup_qemu
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/153.out b/tests/qemu-iotests/153.out
new file mode 100644
index 0000000000..5ba0b63867
--- /dev/null
+++ b/tests/qemu-iotests/153.out
@@ -0,0 +1,390 @@
+QA output created by 153
+== readonly=off,force-share=on should be rejected ==
+QEMU_PROG: -drive if=none,file=null-co://,readonly=off,force-share=on: force-share=on can only be used with read-only images
+
+== Creating base image ==
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=33554432
+
+== Creating test image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base
+
+== Launching QEMU, opts: '' ==
+
+== Launching another QEMU, opts: '' ==
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,if=none,: Failed to get "write" lock
+Is another process using the image?
+
+== Launching another QEMU, opts: 'read-only=on' ==
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,if=none,read-only=on: Failed to get shared "write" lock
+Is another process using the image?
+
+== Launching another QEMU, opts: 'read-only=on,force-share=on' ==
+
+== Running utility commands  ==
+
+_qemu_io_wrapper -c read 0 512 TEST_DIR/t.qcow2
+can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+
+_qemu_io_wrapper -r -c read 0 512 TEST_DIR/t.qcow2
+can't open device TEST_DIR/t.qcow2: Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_io_wrapper -c open  TEST_DIR/t.qcow2 -c read 0 512
+can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+
+_qemu_io_wrapper -c open -r  TEST_DIR/t.qcow2 -c read 0 512
+can't open device TEST_DIR/t.qcow2: Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper info TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper check TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper compare TEST_DIR/t.qcow2 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper map TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper amend -o  TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper commit TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper resize TEST_DIR/t.qcow2 32M
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper rebase TEST_DIR/t.qcow2 -b TEST_DIR/t.qcow2.base
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper snapshot -l TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper convert TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.convert
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper dd if=TEST_DIR/t.qcow2 of=TEST_DIR/t.qcow2.convert bs=512 count=1
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper bench -c 1 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get shared "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper bench -w -c 1 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+== Running utility commands -U ==
+
+_qemu_io_wrapper -U -c read 0 512 TEST_DIR/t.qcow2
+can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+
+_qemu_io_wrapper -U -r -c read 0 512 TEST_DIR/t.qcow2
+
+_qemu_io_wrapper -c open -U TEST_DIR/t.qcow2 -c read 0 512
+can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+
+_qemu_io_wrapper -c open -r -U TEST_DIR/t.qcow2 -c read 0 512
+
+_qemu_img_wrapper info -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper check -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper compare -U TEST_DIR/t.qcow2 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper map -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper amend -o  -U TEST_DIR/t.qcow2
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper commit -U TEST_DIR/t.qcow2
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper resize -U TEST_DIR/t.qcow2 32M
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper rebase -U TEST_DIR/t.qcow2 -b TEST_DIR/t.qcow2.base
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper snapshot -l -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper convert -U TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.convert
+
+_qemu_img_wrapper dd -U if=TEST_DIR/t.qcow2 of=TEST_DIR/t.qcow2.convert bs=512 count=1
+
+_qemu_img_wrapper bench -U -c 1 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper bench -U -w -c 1 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': force-share=on can only be used with read-only images
+
+Round done
+
+== Creating base image ==
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=33554432
+
+== Creating test image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base
+
+== Launching QEMU, opts: 'read-only=on' ==
+
+== Launching another QEMU, opts: '' ==
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,if=none,: Failed to get "write" lock
+Is another process using the image?
+
+== Launching another QEMU, opts: 'read-only=on' ==
+
+== Launching another QEMU, opts: 'read-only=on,force-share=on' ==
+
+== Running utility commands  ==
+
+_qemu_io_wrapper -c read 0 512 TEST_DIR/t.qcow2
+can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+
+_qemu_io_wrapper -r -c read 0 512 TEST_DIR/t.qcow2
+
+_qemu_io_wrapper -c open  TEST_DIR/t.qcow2 -c read 0 512
+can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+
+_qemu_io_wrapper -c open -r  TEST_DIR/t.qcow2 -c read 0 512
+
+_qemu_img_wrapper info TEST_DIR/t.qcow2
+
+_qemu_img_wrapper check TEST_DIR/t.qcow2
+
+_qemu_img_wrapper compare TEST_DIR/t.qcow2 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper map TEST_DIR/t.qcow2
+
+_qemu_img_wrapper amend -o  TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper commit TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper resize TEST_DIR/t.qcow2 32M
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper rebase TEST_DIR/t.qcow2 -b TEST_DIR/t.qcow2.base
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper snapshot -l TEST_DIR/t.qcow2
+
+_qemu_img_wrapper convert TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.convert
+
+_qemu_img_wrapper dd if=TEST_DIR/t.qcow2 of=TEST_DIR/t.qcow2.convert bs=512 count=1
+
+_qemu_img_wrapper bench -c 1 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper bench -w -c 1 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+== Running utility commands -U ==
+
+_qemu_io_wrapper -U -c read 0 512 TEST_DIR/t.qcow2
+can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+
+_qemu_io_wrapper -U -r -c read 0 512 TEST_DIR/t.qcow2
+
+_qemu_io_wrapper -c open -U TEST_DIR/t.qcow2 -c read 0 512
+can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+
+_qemu_io_wrapper -c open -r -U TEST_DIR/t.qcow2 -c read 0 512
+
+_qemu_img_wrapper info -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper check -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper compare -U TEST_DIR/t.qcow2 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper map -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper amend -o  -U TEST_DIR/t.qcow2
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper commit -U TEST_DIR/t.qcow2
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper resize -U TEST_DIR/t.qcow2 32M
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper rebase -U TEST_DIR/t.qcow2 -b TEST_DIR/t.qcow2.base
+qemu-img: Could not open 'TEST_DIR/t.qcow2': Failed to get "write" lock
+Is another process using the image?
+
+_qemu_img_wrapper snapshot -l -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper convert -U TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.convert
+
+_qemu_img_wrapper dd -U if=TEST_DIR/t.qcow2 of=TEST_DIR/t.qcow2.convert bs=512 count=1
+
+_qemu_img_wrapper bench -U -c 1 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper bench -U -w -c 1 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': force-share=on can only be used with read-only images
+
+Round done
+
+== Creating base image ==
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=33554432
+
+== Creating test image ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.base
+
+== Launching QEMU, opts: 'read-only=on,force-share=on' ==
+
+== Launching another QEMU, opts: '' ==
+
+== Launching another QEMU, opts: 'read-only=on' ==
+
+== Launching another QEMU, opts: 'read-only=on,force-share=on' ==
+
+== Running utility commands  ==
+
+_qemu_io_wrapper -c read 0 512 TEST_DIR/t.qcow2
+
+_qemu_io_wrapper -r -c read 0 512 TEST_DIR/t.qcow2
+
+_qemu_io_wrapper -c open  TEST_DIR/t.qcow2 -c read 0 512
+
+_qemu_io_wrapper -c open -r  TEST_DIR/t.qcow2 -c read 0 512
+
+_qemu_img_wrapper info TEST_DIR/t.qcow2
+
+_qemu_img_wrapper check TEST_DIR/t.qcow2
+
+_qemu_img_wrapper compare TEST_DIR/t.qcow2 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper map TEST_DIR/t.qcow2
+
+_qemu_img_wrapper amend -o  TEST_DIR/t.qcow2
+
+_qemu_img_wrapper commit TEST_DIR/t.qcow2
+
+_qemu_img_wrapper resize TEST_DIR/t.qcow2 32M
+
+_qemu_img_wrapper rebase TEST_DIR/t.qcow2 -b TEST_DIR/t.qcow2.base
+
+_qemu_img_wrapper snapshot -l TEST_DIR/t.qcow2
+
+_qemu_img_wrapper convert TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.convert
+
+_qemu_img_wrapper dd if=TEST_DIR/t.qcow2 of=TEST_DIR/t.qcow2.convert bs=512 count=1
+
+_qemu_img_wrapper bench -c 1 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper bench -w -c 1 TEST_DIR/t.qcow2
+
+== Running utility commands -U ==
+
+_qemu_io_wrapper -U -c read 0 512 TEST_DIR/t.qcow2
+can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+
+_qemu_io_wrapper -U -r -c read 0 512 TEST_DIR/t.qcow2
+
+_qemu_io_wrapper -c open -U TEST_DIR/t.qcow2 -c read 0 512
+can't open device TEST_DIR/t.qcow2: force-share=on can only be used with read-only images
+
+_qemu_io_wrapper -c open -r -U TEST_DIR/t.qcow2 -c read 0 512
+
+_qemu_img_wrapper info -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper check -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper compare -U TEST_DIR/t.qcow2 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper map -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper amend -o  -U TEST_DIR/t.qcow2
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper commit -U TEST_DIR/t.qcow2
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper resize -U TEST_DIR/t.qcow2 32M
+qemu-img: unrecognized option '-U'
+Try 'qemu-img --help' for more information
+
+_qemu_img_wrapper rebase -U TEST_DIR/t.qcow2 -b TEST_DIR/t.qcow2.base
+
+_qemu_img_wrapper snapshot -l -U TEST_DIR/t.qcow2
+
+_qemu_img_wrapper convert -U TEST_DIR/t.qcow2 TEST_DIR/t.qcow2.convert
+
+_qemu_img_wrapper dd -U if=TEST_DIR/t.qcow2 of=TEST_DIR/t.qcow2.convert bs=512 count=1
+
+_qemu_img_wrapper bench -U -c 1 TEST_DIR/t.qcow2
+
+_qemu_img_wrapper bench -U -w -c 1 TEST_DIR/t.qcow2
+qemu-img: Could not open 'TEST_DIR/t.qcow2': force-share=on can only be used with read-only images
+
+Round done
+== Creating TEST_DIR/t.qcow2.[abc] ==
+Formatting 'TEST_DIR/t.IMGFMT.a', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT
+Formatting 'TEST_DIR/t.IMGFMT.b', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT
+Formatting 'TEST_DIR/t.IMGFMT.c', fmt=IMGFMT size=33554432 backing_file=TEST_DIR/t.IMGFMT.b
+
+== Two devices sharing the same file in backing chain ==
+
+== Backing image also as an active device ==
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+
+== Backing image also as an active device (ro) ==
+
+== Symbolic link ==
+QEMU_PROG: -drive if=none,file=TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+
+== Closing an image should unlock it ==
+{"return": {}}
+Adding drive
+
+_qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
+can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+Closing drive
+
+_qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
+Adding two and closing one
+
+_qemu_img_wrapper info TEST_DIR/t.qcow2
+
+_qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
+can't open device TEST_DIR/t.qcow2: Failed to get "write" lock
+Is another process using the image?
+Closing the other
+
+_qemu_io_wrapper TEST_DIR/t.qcow2 -c write 0 512
+*** done
diff --git a/tests/qemu-iotests/154 b/tests/qemu-iotests/154
index 7ca7219f08..dd8a426dad 100755
--- a/tests/qemu-iotests/154
+++ b/tests/qemu-iotests/154
@@ -2,7 +2,7 @@
 #
 # qcow2 specific bdrv_pwrite_zeroes tests with backing files (complements 034)
 #
-# Copyright (C) 2016 Red Hat, Inc.
+# Copyright (C) 2016-2017 Red Hat, Inc.
 #
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License as published by
@@ -42,7 +42,10 @@ _supported_proto file
 _supported_os Linux
 
 CLUSTER_SIZE=4k
-size=128M
+size=$((128 * 1024 * 1024))
+
+# This test requires zero clusters, added in v3 images
+_unsupported_imgopts compat=0.10
 
 echo
 echo == backing file contains zeros ==
@@ -299,6 +302,159 @@ $QEMU_IO -c "read -P 0 75k 1k" "$TEST_IMG" | _filter_qemu_io
 
 $QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
 
+echo
+echo == unaligned image tail cluster, no allocation needed ==
+
+# With no backing file, write to all or part of unallocated partial cluster
+# will mark the cluster as zero, but does not allocate.
+# Re-create the image each time to get back to unallocated clusters.
+
+# Write at the front: sector-wise, the request is: 128m... | 00 -- -- --
+_make_test_img $((size + 2048))
+$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write at the back: sector-wise, the request is: 128m... | -- -- -- 00
+_make_test_img $((size + 2048))
+$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write at middle: sector-wise, the request is: 128m... | -- 00 00 --
+_make_test_img $((size + 2048))
+$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write entire cluster: sector-wise, the request is: 128m... | 00 00 00 00
+_make_test_img $((size + 2048))
+$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Repeat with backing file holding unallocated cluster.
+# TODO: Note that this forces an allocation, because we aren't yet able to
+# quickly detect that reads beyond EOF of the backing file are always zero
+CLUSTER_SIZE=2048 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
+
+# Write at the front: sector-wise, the request is:
+# backing: 128m... | -- --
+# active:  128m... | 00 -- -- --
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write at the back: sector-wise, the request is:
+# backing: 128m... | -- --
+# active:  128m... | -- -- -- 00
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write at middle: sector-wise, the request is:
+# backing: 128m... | -- --
+# active:  128m... | -- 00 00 --
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write entire cluster: sector-wise, the request is:
+# backing: 128m... | -- --
+# active:  128m... | 00 00 00 00
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Repeat with backing file holding zero'd cluster
+# TODO: Note that this forces an allocation, because we aren't yet able to
+# quickly detect that reads beyond EOF of the backing file are always zero
+$QEMU_IO -c "write -z $size 512" "$TEST_IMG.base" | _filter_qemu_io
+
+# Write at the front: sector-wise, the request is:
+# backing: 128m... | 00 00
+# active:  128m... | 00 -- -- --
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $size 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write at the back: sector-wise, the request is:
+# backing: 128m... | 00 00
+# active:  128m... | -- -- -- 00
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write at middle: sector-wise, the request is:
+# backing: 128m... | 00 00
+# active:  128m... | -- 00 00 --
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $((size + 512)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Write entire cluster: sector-wise, the request is:
+# backing: 128m... | 00 00
+# active:  128m... | 00 00 00 00
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -z $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 2048" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# A preallocated cluster maintains its allocation, whether it stays as
+# data due to a partial write:
+# Convert 128m... | XX XX => ... | XX 00
+_make_test_img $((size + 1024))
+$QEMU_IO -c "write -P 1 $((size)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 1 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# or because it is the entire cluster and can use the zero flag:
+# Convert 128m... | XX XX => ... | 00 00
+$QEMU_IO -c "write -z $((size)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "alloc $size 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $size 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == unaligned image tail cluster, allocation required ==
+
+# Write beyond backing file must COW
+# Backing file: 128m... | XX --
+# Active layer: 128m... | -- -- 00 --
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -P 1 $((size)) 512" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z $((size + 1024)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 1 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $((size + 512)) 1536" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Writes at boundaries of (partial) cluster must not lose mid-cluster data
+# Backing file: 128m: ... | -- XX
+# Active layer: 128m: ... | 00 -- -- 00
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $((size + 1024))
+_make_test_img -b "$TEST_IMG.base" $((size + 2048))
+$QEMU_IO -c "write -P 1 $((size + 512)) 512" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z $((size)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 1 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $((size + 1024)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z $((size + 1536)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $((size)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 1 $((size + 512)) 512" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 $((size + 1024)) 1024" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/154.out b/tests/qemu-iotests/154.out
index da9eabdda8..d8485eeff2 100644
--- a/tests/qemu-iotests/154.out
+++ b/tests/qemu-iotests/154.out
@@ -42,9 +42,9 @@ read 1024/1024 bytes at offset 65536
 read 2048/2048 bytes at offset 67584
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 32768, "depth": 1, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 32768, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 36864, "length": 28672, "depth": 1, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 69632, "length": 134148096, "depth": 1, "zero": true, "data": false}]
 
 == backing file contains non-zero data after write_zeroes ==
@@ -69,9 +69,9 @@ read 1024/1024 bytes at offset 44032
 read 3072/3072 bytes at offset 40960
 3 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 32768, "depth": 1, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 32768, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 36864, "length": 4096, "depth": 1, "zero": true, "data": false},
-{ "start": 40960, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 40960, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 45056, "length": 134172672, "depth": 1, "zero": true, "data": false}]
 
 == write_zeroes covers non-zero data ==
@@ -143,13 +143,13 @@ read 1024/1024 bytes at offset 67584
 read 5120/5120 bytes at offset 68608
 5 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 32768, "depth": 1, "zero": true, "data": false},
-{ "start": 32768, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 32768, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 36864, "length": 4096, "depth": 0, "zero": true, "data": false},
 { "start": 40960, "length": 8192, "depth": 1, "zero": true, "data": false},
-{ "start": 49152, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 49152, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 53248, "length": 4096, "depth": 0, "zero": true, "data": false},
 { "start": 57344, "length": 8192, "depth": 1, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 28672},
+{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 69632, "length": 4096, "depth": 0, "zero": true, "data": false},
 { "start": 73728, "length": 134144000, "depth": 1, "zero": true, "data": false}]
 
@@ -186,13 +186,13 @@ read 1024/1024 bytes at offset 72704
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 32768, "depth": 1, "zero": true, "data": false},
 { "start": 32768, "length": 4096, "depth": 0, "zero": true, "data": false},
-{ "start": 36864, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 36864, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 40960, "length": 8192, "depth": 1, "zero": true, "data": false},
 { "start": 49152, "length": 4096, "depth": 0, "zero": true, "data": false},
-{ "start": 53248, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 53248, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 57344, "length": 8192, "depth": 1, "zero": true, "data": false},
 { "start": 65536, "length": 4096, "depth": 0, "zero": true, "data": false},
-{ "start": 69632, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 28672},
+{ "start": 69632, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 73728, "length": 134144000, "depth": 1, "zero": true, "data": false}]
 
 == spanning two clusters, partially overwriting backing file ==
@@ -212,7 +212,7 @@ read 1024/1024 bytes at offset 5120
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 read 2048/2048 bytes at offset 6144
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-[{ "start": 0, "length": 8192, "depth": 0, "zero": false, "data": true, "offset": 20480},
+[{ "start": 0, "length": 8192, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 8192, "length": 134209536, "depth": 1, "zero": true, "data": false}]
 
 == spanning multiple clusters, non-zero in first cluster ==
@@ -227,7 +227,7 @@ read 2048/2048 bytes at offset 65536
 read 10240/10240 bytes at offset 67584
 10 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 65536, "depth": 1, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 69632, "length": 8192, "depth": 0, "zero": true, "data": false},
 { "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
 
@@ -257,7 +257,7 @@ read 2048/2048 bytes at offset 75776
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 65536, "depth": 1, "zero": true, "data": false},
 { "start": 65536, "length": 8192, "depth": 0, "zero": true, "data": false},
-{ "start": 73728, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 73728, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
 
 == spanning multiple clusters, partially overwriting backing file ==
@@ -278,8 +278,136 @@ read 2048/2048 bytes at offset 74752
 read 1024/1024 bytes at offset 76800
 1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 [{ "start": 0, "length": 65536, "depth": 1, "zero": true, "data": false},
-{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 69632, "length": 4096, "depth": 0, "zero": true, "data": false},
-{ "start": 73728, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 73728, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
 { "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
+
+== unaligned image tail cluster, no allocation needed ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
+wrote 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
+wrote 512/512 bytes at offset 134219264
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
+wrote 1024/1024 bytes at offset 134218240
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776
+wrote 2048/2048 bytes at offset 134217728
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134219776, "depth": 0, "zero": true, "data": false}]
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 512/512 bytes at offset 134219264
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 1024/1024 bytes at offset 134218240
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 2048/2048 bytes at offset 134217728
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
+wrote 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 512/512 bytes at offset 134219264
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 1024/1024 bytes at offset 134218240
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 2048/2048 bytes at offset 134217728
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2048/2048 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": true, "data": false}]
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134218752
+wrote 1024/1024 bytes at offset 134217728
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 512/512 bytes at offset 134218240
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134218240
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+1024/1024 bytes allocated at offset 128 MiB
+[{ "start": 0, "length": 134217728, "depth": 0, "zero": true, "data": false},
+{ "start": 134217728, "length": 1024, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+wrote 1024/1024 bytes at offset 134217728
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+1024/1024 bytes allocated at offset 128 MiB
+read 1024/1024 bytes at offset 134217728
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+[{ "start": 0, "length": 134217728, "depth": 0, "zero": true, "data": false},
+{ "start": 134217728, "length": 1024, "depth": 0, "zero": true, "data": false, "offset": OFFSET}]
+
+== unaligned image tail cluster, allocation required ==
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 512/512 bytes at offset 134218752
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1536/1536 bytes at offset 134218240
+1.500 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134218752
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134219776 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 512/512 bytes at offset 134218240
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134218240
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 134218752
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 512/512 bytes at offset 134219264
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134217728
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 512/512 bytes at offset 134218240
+512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 134218752
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+[{ "start": 0, "length": 134217728, "depth": 1, "zero": true, "data": false},
+{ "start": 134217728, "length": 2048, "depth": 0, "zero": false, "data": true, "offset": OFFSET}]
 *** done
diff --git a/tests/qemu-iotests/172 b/tests/qemu-iotests/172
index 1b7d3a194d..826d6fecd3 100755
--- a/tests/qemu-iotests/172
+++ b/tests/qemu-iotests/172
@@ -30,6 +30,8 @@ status=1	# failure is the default!
 _cleanup()
 {
 	_cleanup_test_img
+    rm -f "$TEST_IMG.2"
+    rm -f "$TEST_IMG.3"
 }
 trap "_cleanup; exit \$status" 0 1 2 3 15
 
@@ -86,6 +88,9 @@ size=720k
 
 _make_test_img $size
 
+TEST_IMG="$TEST_IMG.2" _make_test_img $size
+TEST_IMG="$TEST_IMG.3" _make_test_img $size
+
 # Default drive semantics:
 #
 # By default you get a single empty floppy drive. You can override it with
@@ -105,7 +110,7 @@ echo === Using -fda/-fdb options ===
 
 check_floppy_qtree -fda "$TEST_IMG"
 check_floppy_qtree -fdb "$TEST_IMG"
-check_floppy_qtree -fda "$TEST_IMG" -fdb "$TEST_IMG"
+check_floppy_qtree -fda "$TEST_IMG" -fdb "$TEST_IMG.2"
 
 
 echo
@@ -114,7 +119,7 @@ echo === Using -drive options ===
 
 check_floppy_qtree -drive if=floppy,file="$TEST_IMG"
 check_floppy_qtree -drive if=floppy,file="$TEST_IMG",index=1
-check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=floppy,file="$TEST_IMG",index=1
+check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=floppy,file="$TEST_IMG.2",index=1
 
 echo
 echo
@@ -122,7 +127,7 @@ echo === Using -drive if=none and -global ===
 
 check_floppy_qtree -drive if=none,file="$TEST_IMG" -global isa-fdc.driveA=none0
 check_floppy_qtree -drive if=none,file="$TEST_IMG" -global isa-fdc.driveB=none0
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveA=none0 -global isa-fdc.driveB=none1
 
 echo
@@ -131,7 +136,7 @@ echo === Using -drive if=none and -device ===
 
 check_floppy_qtree -drive if=none,file="$TEST_IMG" -device floppy,drive=none0
 check_floppy_qtree -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=1
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -device floppy,drive=none0 -device floppy,drive=none1,unit=1
 
 echo
@@ -139,58 +144,58 @@ echo
 echo === Mixing -fdX and -global ===
 
 # Working
-check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG" -global isa-fdc.driveB=none0
-check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG" -global isa-fdc.driveA=none0
+check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -global isa-fdc.driveB=none0
+check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -global isa-fdc.driveA=none0
 
 # Conflicting (-fdX wins)
-check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG" -global isa-fdc.driveA=none0
-check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG" -global isa-fdc.driveB=none0
+check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -global isa-fdc.driveA=none0
+check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -global isa-fdc.driveB=none0
 
 echo
 echo
 echo === Mixing -fdX and -device ===
 
 # Working
-check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0
-check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=1
+check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0
+check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0,unit=1
 
-check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0
-check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=0
+check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0
+check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0,unit=0
 
 # Conflicting
-check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=0
-check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=1
+check_floppy_qtree -fda "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0,unit=0
+check_floppy_qtree -fdb "$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0,unit=1
 
 echo
 echo
 echo === Mixing -drive and -device ===
 
 # Working
-check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0
-check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=1
+check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0
+check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0,unit=1
 
 # Conflicting
-check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" -device floppy,drive=none0,unit=0
+check_floppy_qtree -drive if=floppy,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" -device floppy,drive=none0,unit=0
 
 echo
 echo
 echo === Mixing -global and -device ===
 
 # Working
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveA=none0 -device floppy,drive=none1
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveA=none0 -device floppy,drive=none1,unit=1
 
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveB=none0 -device floppy,drive=none1
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveB=none0 -device floppy,drive=none1,unit=0
 
 # Conflicting
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveA=none0 -device floppy,drive=none1,unit=0
-check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG" \
+check_floppy_qtree -drive if=none,file="$TEST_IMG" -drive if=none,file="$TEST_IMG.2" \
                    -global isa-fdc.driveB=none0 -device floppy,drive=none1,unit=1
 
 echo
@@ -199,8 +204,8 @@ echo === Too many floppy drives ===
 
 # Working
 check_floppy_qtree -drive if=floppy,file="$TEST_IMG" \
-                   -drive if=none,file="$TEST_IMG" \
-                   -drive if=none,file="$TEST_IMG" \
+                   -drive if=none,file="$TEST_IMG.2" \
+                   -drive if=none,file="$TEST_IMG.3" \
                    -global isa-fdc.driveB=none0 \
                    -device floppy,drive=none1
 
diff --git a/tests/qemu-iotests/172.out b/tests/qemu-iotests/172.out
index 54b53293d7..2732966166 100644
--- a/tests/qemu-iotests/172.out
+++ b/tests/qemu-iotests/172.out
@@ -1,5 +1,7 @@
 QA output created by 172
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=737280
+Formatting 'TEST_DIR/t.IMGFMT.2', fmt=IMGFMT size=737280
+Formatting 'TEST_DIR/t.IMGFMT.3', fmt=IMGFMT size=737280
 
 
 === Default ===
@@ -99,7 +101,7 @@ Testing: -fdb TEST_DIR/t.qcow2
                 share-rw = false
                 drive-type = "288"
 
-Testing: -fda TEST_DIR/t.qcow2 -fdb TEST_DIR/t.qcow2
+Testing: -fda TEST_DIR/t.qcow2 -fdb TEST_DIR/t.qcow2.2
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -205,7 +207,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2,index=1
                 share-rw = false
                 drive-type = "288"
 
-Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=floppy,file=TEST_DIR/t.qcow2,index=1
+Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=floppy,file=TEST_DIR/t.qcow2.2,index=1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -300,7 +302,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveA=none0 -global isa-fdc.driveB=none1
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveA=none0 -global isa-fdc.driveB=none1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -395,7 +397,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=1
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0 -device floppy,drive=none1,unit=1
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0 -device floppy,drive=none1,unit=1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -436,7 +438,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
 
 === Mixing -fdX and -global ===
 
-Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0
+Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveB=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -474,7 +476,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveA=none0
+Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveA=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -512,7 +514,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveA=none0
+Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveA=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -539,7 +541,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0
+Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveB=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -569,7 +571,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-
 
 === Mixing -fdX and -device ===
 
-Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0
+Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -607,7 +609,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device flop
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=1
+Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0,unit=1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -645,7 +647,7 @@ Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device flop
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0
+Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -683,7 +685,7 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device flop
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=0
+Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0,unit=0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -721,18 +723,18 @@ Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device flop
                 share-rw = false
                 drive-type = "144"
 
-Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=0
+Testing: -fda TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0,unit=0
 QEMU_PROG: -device floppy,drive=none0,unit=0: Floppy unit 0 is in use
 QEMU_PROG: -device floppy,drive=none0,unit=0: Device initialization failed.
 
-Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=1
+Testing: -fdb TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0,unit=1
 QEMU_PROG: -device floppy,drive=none0,unit=1: Floppy unit 1 is in use
 QEMU_PROG: -device floppy,drive=none0,unit=1: Device initialization failed.
 
 
 === Mixing -drive and -device ===
 
-Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0
+Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -770,7 +772,7 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.q
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=1
+Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0,unit=1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -808,14 +810,14 @@ Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.q
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -device floppy,drive=none0,unit=0
+Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -device floppy,drive=none0,unit=0
 QEMU_PROG: -device floppy,drive=none0,unit=0: Floppy unit 0 is in use
 QEMU_PROG: -device floppy,drive=none0,unit=0: Device initialization failed.
 
 
 === Mixing -global and -device ===
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveA=none0 -device floppy,drive=none1
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveA=none0 -device floppy,drive=none1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -853,7 +855,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveA=none0 -device floppy,drive=none1,unit=1
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveA=none0 -device floppy,drive=none1,unit=1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -891,7 +893,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0 -device floppy,drive=none1
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveB=none0 -device floppy,drive=none1
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -929,7 +931,7 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0 -device floppy,drive=none1,unit=0
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveB=none0 -device floppy,drive=none1,unit=0
 
           dev: isa-fdc, id ""
             iobase = 1008 (0x3f0)
@@ -967,18 +969,18 @@ Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qco
                 share-rw = false
                 drive-type = "144"
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveA=none0 -device floppy,drive=none1,unit=0
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveA=none0 -device floppy,drive=none1,unit=0
 QEMU_PROG: -device floppy,drive=none1,unit=0: Floppy unit 0 is in use
 QEMU_PROG: -device floppy,drive=none1,unit=0: Device initialization failed.
 
-Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0 -device floppy,drive=none1,unit=1
+Testing: -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -global isa-fdc.driveB=none0 -device floppy,drive=none1,unit=1
 QEMU_PROG: -device floppy,drive=none1,unit=1: Floppy unit 1 is in use
 QEMU_PROG: -device floppy,drive=none1,unit=1: Device initialization failed.
 
 
 === Too many floppy drives ===
 
-Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2 -global isa-fdc.driveB=none0 -device floppy,drive=none1
+Testing: -drive if=floppy,file=TEST_DIR/t.qcow2 -drive if=none,file=TEST_DIR/t.qcow2.2 -drive if=none,file=TEST_DIR/t.qcow2.3 -global isa-fdc.driveB=none0 -device floppy,drive=none1
 QEMU_PROG: -device floppy,drive=none1: Can't create floppy unit 2, bus supports only 2 units
 QEMU_PROG: -device floppy,drive=none1: Device initialization failed.
 
diff --git a/tests/qemu-iotests/177 b/tests/qemu-iotests/177
new file mode 100755
index 0000000000..2005c174f2
--- /dev/null
+++ b/tests/qemu-iotests/177
@@ -0,0 +1,114 @@
+#!/bin/bash
+#
+# Test corner cases with unusual block geometries
+#
+# Copyright (C) 2016-2017 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=eblake@redhat.com
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+here=`pwd`
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt qcow2
+_supported_proto file
+
+CLUSTER_SIZE=1M
+size=128M
+options=driver=blkdebug,image.driver=qcow2
+
+echo
+echo "== setting up files =="
+
+TEST_IMG="$TEST_IMG.base" _make_test_img $size
+$QEMU_IO -c "write -P 11 0 $size" "$TEST_IMG.base" | _filter_qemu_io
+_make_test_img -b "$TEST_IMG.base"
+$QEMU_IO -c "write -P 22 0 $size" "$TEST_IMG" | _filter_qemu_io
+
+# Limited to 64k max-transfer
+echo
+echo "== constrained alignment and max-transfer =="
+limits=align=4k,max-transfer=64k
+$QEMU_IO -c "open -o $options,$limits blkdebug::$TEST_IMG" \
+         -c "write -P 33 1000 128k" -c "read -P 33 1000 128k" | _filter_qemu_io
+
+echo
+echo "== write zero with constrained max-transfer =="
+limits=align=512,max-transfer=64k,opt-write-zero=$CLUSTER_SIZE
+$QEMU_IO -c "open -o $options,$limits blkdebug::$TEST_IMG" \
+         -c "write -z 8003584 2093056" | _filter_qemu_io
+
+# non-power-of-2 write-zero/discard alignments
+echo
+echo "== non-power-of-2 write zeroes limits =="
+
+limits=align=512,opt-write-zero=15M,max-write-zero=15M,opt-discard=15M,max-discard=15M
+$QEMU_IO -c "open -o $options,$limits blkdebug::$TEST_IMG" \
+         -c "write -z 32M 32M" | _filter_qemu_io
+
+echo
+echo "== non-power-of-2 discard limits =="
+
+limits=align=512,opt-write-zero=15M,max-write-zero=15M,opt-discard=15M,max-discard=15M
+$QEMU_IO -c "open -o $options,$limits blkdebug::$TEST_IMG" \
+         -c "discard 80000001 30M" | _filter_qemu_io
+
+echo
+echo "== verify image content =="
+
+function verify_io()
+{
+    if ($QEMU_IMG info -f "$IMGFMT" "$TEST_IMG" |
+	    grep "compat: 0.10" > /dev/null); then
+        # For v2 images, discarded clusters are read from the backing file
+        discarded=11
+    else
+        # Discarded clusters are zeroed for v3 or later
+        discarded=0
+    fi
+
+    echo read -P 22 0 1000
+    echo read -P 33 1000 128k
+    echo read -P 22 132072 7871512
+    echo read -P 0 8003584 2093056
+    echo read -P 22 10096640 23457792
+    echo read -P 0 32M 32M
+    echo read -P 22 64M 13M
+    echo read -P $discarded 77M 29M
+    echo read -P 22 106M 22M
+}
+
+verify_io | $QEMU_IO -r "$TEST_IMG" | _filter_qemu_io
+
+_check_test_img
+
+# success, all done
+echo "*** done"
+status=0
diff --git a/tests/qemu-iotests/177.out b/tests/qemu-iotests/177.out
new file mode 100644
index 0000000000..e887542678
--- /dev/null
+++ b/tests/qemu-iotests/177.out
@@ -0,0 +1,49 @@
+QA output created by 177
+
+== setting up files ==
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=134217728
+wrote 134217728/134217728 bytes at offset 0
+128 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 134217728/134217728 bytes at offset 0
+128 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== constrained alignment and max-transfer ==
+wrote 131072/131072 bytes at offset 1000
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 131072/131072 bytes at offset 1000
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== write zero with constrained max-transfer ==
+wrote 2093056/2093056 bytes at offset 8003584
+1.996 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== non-power-of-2 write zeroes limits ==
+wrote 33554432/33554432 bytes at offset 33554432
+32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== non-power-of-2 discard limits ==
+discard 31457280/31457280 bytes at offset 80000001
+30 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+== verify image content ==
+read 1000/1000 bytes at offset 0
+1000 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 131072/131072 bytes at offset 1000
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 7871512/7871512 bytes at offset 132072
+7.507 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2093056/2093056 bytes at offset 8003584
+1.996 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 23457792/23457792 bytes at offset 10096640
+22.371 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 33554432/33554432 bytes at offset 33554432
+32 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 13631488/13631488 bytes at offset 67108864
+13 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 30408704/30408704 bytes at offset 80740352
+29 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 23068672/23068672 bytes at offset 111149056
+22 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+No errors were found on the image.
+*** done
diff --git a/tests/qemu-iotests/179 b/tests/qemu-iotests/179
new file mode 100755
index 0000000000..7bc8db8fe0
--- /dev/null
+++ b/tests/qemu-iotests/179
@@ -0,0 +1,130 @@
+#!/bin/bash
+#
+# Test case for write zeroes with unmap
+#
+# Copyright (C) 2017 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=eblake@redhat.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+here="$PWD"
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+# v2 images can't mark clusters as zero
+_unsupported_imgopts compat=0.10
+
+echo
+echo '=== Testing write zeroes with unmap ==='
+echo
+
+TEST_IMG="$TEST_IMG.base" _make_test_img 64M
+_make_test_img -b "$TEST_IMG.base"
+
+# Offsets chosen at or near 2M boundaries so test works at all cluster sizes
+# 8k and larger (smaller clusters fail due to non-contiguous allocations)
+
+# Aligned writes to unallocated cluster should not allocate mapping, but must
+# mark cluster as zero, whether or not unmap was requested
+$QEMU_IO -c "write -z -u 2M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 6M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
+
+# Unaligned writes need not allocate mapping if the cluster already reads
+# as zero, but must mark cluster as zero, whether or not unmap was requested
+$QEMU_IO -c "write -z -u 10485761 2097150" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 14680065 2097150" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
+
+# Requesting unmap of normal data must deallocate; omitting unmap should
+# preserve the mapping
+$QEMU_IO -c "write 18M 14M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z -u 20M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 24M 6M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
+
+# Likewise when writing on already-mapped zero data
+$QEMU_IO -c "write -z -u 26M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 28M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
+
+# Writing on unmapped zeroes does not allocate
+$QEMU_IO -c "write -z 32M 8M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z -u 34M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 36M 2M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "map" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG.base" | _filter_qemu_img_map
+
+# Writing zero overrides a backing file, regardless of backing cluster type
+$QEMU_IO -c "write -z 40M 8M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write 48M 8M" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z -u 42M 2M" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z 44M 2M" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z -u 50M 2M" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z 52M 2M" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z -u 58M 2M" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z 60M 2M" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "map" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+# Final check that mappings are correct and images are still sane
+TEST_IMG="$TEST_IMG.base" _check_test_img
+_check_test_img
+
+echo
+echo '=== Testing cache optimization ==='
+echo
+
+BLKDBG_TEST_IMG="blkdebug:$TEST_DIR/blkdebug.conf:$TEST_IMG.base"
+
+cat > "$TEST_DIR/blkdebug.conf" <<EOF
+[inject-error]
+event = "l2_update"
+errno = "5"
+immediately = "on"
+once = "off"
+EOF
+
+# None of the following writes should trigger an L2 update, because the
+# cluster already reads as zero, and we don't have to change allocation
+$QEMU_IO -c "w -z -u 20M 2M" "$BLKDBG_TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "w -z 20M 2M" "$BLKDBG_TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "w -z 28M 2M" "$BLKDBG_TEST_IMG" | _filter_qemu_io
+
+# success, all done
+echo '*** done'
+status=0
diff --git a/tests/qemu-iotests/179.out b/tests/qemu-iotests/179.out
new file mode 100644
index 0000000000..80722b2289
--- /dev/null
+++ b/tests/qemu-iotests/179.out
@@ -0,0 +1,156 @@
+QA output created by 179
+
+=== Testing write zeroes with unmap ===
+
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=67108864
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 backing_file=TEST_DIR/t.IMGFMT.base
+wrote 2097152/2097152 bytes at offset 2097152
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 6291456
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2 MiB (0x200000) bytes not allocated at offset 0 bytes (0x0)
+2 MiB (0x200000) bytes     allocated at offset 2 MiB (0x200000)
+2 MiB (0x200000) bytes not allocated at offset 4 MiB (0x400000)
+2 MiB (0x200000) bytes     allocated at offset 6 MiB (0x600000)
+56 MiB (0x3800000) bytes not allocated at offset 8 MiB (0x800000)
+[{ "start": 0, "length": 67108864, "depth": 0, "zero": true, "data": false}]
+wrote 2097150/2097150 bytes at offset 10485761
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097150/2097150 bytes at offset 14680065
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2 MiB (0x200000) bytes not allocated at offset 0 bytes (0x0)
+2 MiB (0x200000) bytes     allocated at offset 2 MiB (0x200000)
+2 MiB (0x200000) bytes not allocated at offset 4 MiB (0x400000)
+2 MiB (0x200000) bytes     allocated at offset 6 MiB (0x600000)
+2 MiB (0x200000) bytes not allocated at offset 8 MiB (0x800000)
+2 MiB (0x200000) bytes     allocated at offset 10 MiB (0xa00000)
+2 MiB (0x200000) bytes not allocated at offset 12 MiB (0xc00000)
+2 MiB (0x200000) bytes     allocated at offset 14 MiB (0xe00000)
+48 MiB (0x3000000) bytes not allocated at offset 16 MiB (0x1000000)
+[{ "start": 0, "length": 67108864, "depth": 0, "zero": true, "data": false}]
+wrote 14680064/14680064 bytes at offset 18874368
+14 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 20971520
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 6291456/6291456 bytes at offset 25165824
+6 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2 MiB (0x200000) bytes not allocated at offset 0 bytes (0x0)
+2 MiB (0x200000) bytes     allocated at offset 2 MiB (0x200000)
+2 MiB (0x200000) bytes not allocated at offset 4 MiB (0x400000)
+2 MiB (0x200000) bytes     allocated at offset 6 MiB (0x600000)
+2 MiB (0x200000) bytes not allocated at offset 8 MiB (0x800000)
+2 MiB (0x200000) bytes     allocated at offset 10 MiB (0xa00000)
+2 MiB (0x200000) bytes not allocated at offset 12 MiB (0xc00000)
+2 MiB (0x200000) bytes     allocated at offset 14 MiB (0xe00000)
+2 MiB (0x200000) bytes not allocated at offset 16 MiB (0x1000000)
+14 MiB (0xe00000) bytes     allocated at offset 18 MiB (0x1200000)
+32 MiB (0x2000000) bytes not allocated at offset 32 MiB (0x2000000)
+[{ "start": 0, "length": 18874368, "depth": 0, "zero": true, "data": false},
+{ "start": 18874368, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 0, "zero": true, "data": false},
+{ "start": 23068672, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 25165824, "length": 6291456, "depth": 0, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 33554432, "length": 33554432, "depth": 0, "zero": true, "data": false}]
+wrote 2097152/2097152 bytes at offset 27262976
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 29360128
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2 MiB (0x200000) bytes not allocated at offset 0 bytes (0x0)
+2 MiB (0x200000) bytes     allocated at offset 2 MiB (0x200000)
+2 MiB (0x200000) bytes not allocated at offset 4 MiB (0x400000)
+2 MiB (0x200000) bytes     allocated at offset 6 MiB (0x600000)
+2 MiB (0x200000) bytes not allocated at offset 8 MiB (0x800000)
+2 MiB (0x200000) bytes     allocated at offset 10 MiB (0xa00000)
+2 MiB (0x200000) bytes not allocated at offset 12 MiB (0xc00000)
+2 MiB (0x200000) bytes     allocated at offset 14 MiB (0xe00000)
+2 MiB (0x200000) bytes not allocated at offset 16 MiB (0x1000000)
+14 MiB (0xe00000) bytes     allocated at offset 18 MiB (0x1200000)
+32 MiB (0x2000000) bytes not allocated at offset 32 MiB (0x2000000)
+[{ "start": 0, "length": 18874368, "depth": 0, "zero": true, "data": false},
+{ "start": 18874368, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 0, "zero": true, "data": false},
+{ "start": 23068672, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 25165824, "length": 2097152, "depth": 0, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 27262976, "length": 2097152, "depth": 0, "zero": true, "data": false},
+{ "start": 29360128, "length": 2097152, "depth": 0, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 33554432, "length": 33554432, "depth": 0, "zero": true, "data": false}]
+wrote 8388608/8388608 bytes at offset 33554432
+8 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 35651584
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 37748736
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+2 MiB (0x200000) bytes not allocated at offset 0 bytes (0x0)
+2 MiB (0x200000) bytes     allocated at offset 2 MiB (0x200000)
+2 MiB (0x200000) bytes not allocated at offset 4 MiB (0x400000)
+2 MiB (0x200000) bytes     allocated at offset 6 MiB (0x600000)
+2 MiB (0x200000) bytes not allocated at offset 8 MiB (0x800000)
+2 MiB (0x200000) bytes     allocated at offset 10 MiB (0xa00000)
+2 MiB (0x200000) bytes not allocated at offset 12 MiB (0xc00000)
+2 MiB (0x200000) bytes     allocated at offset 14 MiB (0xe00000)
+2 MiB (0x200000) bytes not allocated at offset 16 MiB (0x1000000)
+22 MiB (0x1600000) bytes     allocated at offset 18 MiB (0x1200000)
+24 MiB (0x1800000) bytes not allocated at offset 40 MiB (0x2800000)
+[{ "start": 0, "length": 18874368, "depth": 0, "zero": true, "data": false},
+{ "start": 18874368, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 0, "zero": true, "data": false},
+{ "start": 23068672, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 25165824, "length": 2097152, "depth": 0, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 27262976, "length": 2097152, "depth": 0, "zero": true, "data": false},
+{ "start": 29360128, "length": 2097152, "depth": 0, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 0, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 33554432, "length": 33554432, "depth": 0, "zero": true, "data": false}]
+wrote 8388608/8388608 bytes at offset 41943040
+8 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 8388608/8388608 bytes at offset 50331648
+8 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 44040192
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 46137344
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 52428800
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 54525952
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 60817408
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 62914560
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+42 MiB (0x2a00000) bytes not allocated at offset 0 bytes (0x0)
+4 MiB (0x400000) bytes     allocated at offset 42 MiB (0x2a00000)
+4 MiB (0x400000) bytes not allocated at offset 46 MiB (0x2e00000)
+4 MiB (0x400000) bytes     allocated at offset 50 MiB (0x3200000)
+4 MiB (0x400000) bytes not allocated at offset 54 MiB (0x3600000)
+4 MiB (0x400000) bytes     allocated at offset 58 MiB (0x3a00000)
+2 MiB (0x200000) bytes not allocated at offset 62 MiB (0x3e00000)
+[{ "start": 0, "length": 18874368, "depth": 1, "zero": true, "data": false},
+{ "start": 18874368, "length": 2097152, "depth": 1, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 20971520, "length": 2097152, "depth": 1, "zero": true, "data": false},
+{ "start": 23068672, "length": 2097152, "depth": 1, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 25165824, "length": 2097152, "depth": 1, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 27262976, "length": 2097152, "depth": 1, "zero": true, "data": false},
+{ "start": 29360128, "length": 2097152, "depth": 1, "zero": true, "data": false, "offset": OFFSET},
+{ "start": 31457280, "length": 2097152, "depth": 1, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 33554432, "length": 10485760, "depth": 1, "zero": true, "data": false},
+{ "start": 44040192, "length": 4194304, "depth": 0, "zero": true, "data": false},
+{ "start": 48234496, "length": 2097152, "depth": 1, "zero": true, "data": false},
+{ "start": 50331648, "length": 2097152, "depth": 1, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 52428800, "length": 4194304, "depth": 0, "zero": true, "data": false},
+{ "start": 56623104, "length": 2097152, "depth": 1, "zero": false, "data": true, "offset": OFFSET},
+{ "start": 58720256, "length": 2097152, "depth": 1, "zero": true, "data": false},
+{ "start": 60817408, "length": 4194304, "depth": 0, "zero": true, "data": false},
+{ "start": 65011712, "length": 2097152, "depth": 1, "zero": true, "data": false}]
+No errors were found on the image.
+No errors were found on the image.
+
+=== Testing cache optimization ===
+
+wrote 2097152/2097152 bytes at offset 20971520
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 20971520
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2097152/2097152 bytes at offset 29360128
+2 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+*** done
diff --git a/tests/qemu-iotests/182 b/tests/qemu-iotests/182
new file mode 100755
index 0000000000..7ecbb22604
--- /dev/null
+++ b/tests/qemu-iotests/182
@@ -0,0 +1,68 @@
+#!/bin/bash
+#
+# Test image locking for POSIX locks
+#
+# Copyright 2017 Red Hat, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+# creator
+owner=famz@redhat.com
+
+seq="$(basename $0)"
+echo "QA output created by $seq"
+
+here="$PWD"
+tmp=/tmp/$$
+status=1	# failure is the default!
+
+_cleanup()
+{
+    _cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+. ./common.qemu
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+size=32M
+
+_make_test_img $size
+
+echo "Starting QEMU"
+_launch_qemu -drive file=$TEST_IMG,if=none,id=drive0,file.locking=on \
+    -device virtio-blk-pci,drive=drive0
+
+echo
+echo "Starting a second QEMU using the same image should fail"
+echo 'quit' | $QEMU -monitor stdio \
+    -drive file=$TEST_IMG,if=none,id=drive0,file.locking=on \
+    -device virtio-blk-pci,drive=drive0 2>&1 | _filter_testdir 2>&1 |
+    _filter_qemu |
+    sed -e '/falling back to POSIX file/d' \
+        -e '/locks can be lost unexpectedly/d'
+
+_cleanup_qemu
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/182.out b/tests/qemu-iotests/182.out
new file mode 100644
index 0000000000..23a4dbf809
--- /dev/null
+++ b/tests/qemu-iotests/182.out
@@ -0,0 +1,8 @@
+QA output created by 182
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=33554432
+Starting QEMU
+
+Starting a second QEMU using the same image should fail
+QEMU_PROG: -drive file=TEST_DIR/t.qcow2,if=none,id=drive0,file.locking=on: Failed to get "write" lock
+Is another process using the image?
+*** done
diff --git a/tests/qemu-iotests/common.filter b/tests/qemu-iotests/common.filter
index f58548dc44..2f595b2ce2 100644
--- a/tests/qemu-iotests/common.filter
+++ b/tests/qemu-iotests/common.filter
@@ -152,10 +152,12 @@ _filter_img_info()
         -e "/log_size: [0-9]\\+/d"
 }
 
-# filter out offsets and file names from qemu-img map
+# filter out offsets and file names from qemu-img map; good for both
+# human and json output
 _filter_qemu_img_map()
 {
     sed -e 's/\([0-9a-fx]* *[0-9a-fx]* *\)[0-9a-fx]* */\1/g' \
+        -e 's/"offset": [0-9]\+/"offset": OFFSET/g' \
         -e 's/Mapped to *//' | _filter_testdir | _filter_imgfmt
 }
 
diff --git a/tests/qemu-iotests/common.pattern b/tests/qemu-iotests/common.pattern
index ddfbca1b76..34f4a8dc9b 100644
--- a/tests/qemu-iotests/common.pattern
+++ b/tests/qemu-iotests/common.pattern
@@ -18,7 +18,7 @@
 
 function do_is_allocated() {
     local start=$1
-    local size=$(( $2 / 512))
+    local size=$2
     local step=$3
     local count=$4
 
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 893962d41e..5c8ea0f95c 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -154,6 +154,7 @@
 149 rw auto sudo
 150 rw auto quick
 152 rw auto quick
+153 rw auto quick
 154 rw auto backing quick
 155 rw auto
 156 rw auto quick
@@ -169,4 +170,7 @@
 174 auto
 175 auto quick
 176 rw auto backing
+177 rw auto quick
+179 rw auto quick
 181 rw auto migration
+182 rw auto quick
diff --git a/tests/test-replication.c b/tests/test-replication.c
index 3016c6f2e0..cebeb793b0 100644
--- a/tests/test-replication.c
+++ b/tests/test-replication.c
@@ -179,7 +179,8 @@ static BlockBackend *start_primary(void)
     char *cmdline;
 
     cmdline = g_strdup_printf("driver=replication,mode=primary,node-name=xxx,"
-                              "file.driver=qcow2,file.file.filename=%s"
+                              "file.driver=qcow2,file.file.filename=%s,"
+                              "file.file.locking=off"
                               , p_local_disk);
     opts = qemu_opts_parse_noisily(&qemu_drive_opts, cmdline, false);
     g_free(cmdline);
@@ -310,7 +311,9 @@ static BlockBackend *start_secondary(void)
     Error *local_err = NULL;
 
     /* add s_local_disk and forge S_LOCAL_DISK_ID */
-    cmdline = g_strdup_printf("file.filename=%s,driver=qcow2", s_local_disk);
+    cmdline = g_strdup_printf("file.filename=%s,driver=qcow2,"
+                              "file.locking=off",
+                              s_local_disk);
     opts = qemu_opts_parse_noisily(&qemu_drive_opts, cmdline, false);
     g_free(cmdline);
 
@@ -331,8 +334,10 @@ static BlockBackend *start_secondary(void)
     /* add S_(ACTIVE/HIDDEN)_DISK and forge S_ID */
     cmdline = g_strdup_printf("driver=replication,mode=secondary,top-id=%s,"
                               "file.driver=qcow2,file.file.filename=%s,"
+                              "file.file.locking=off,"
                               "file.backing.driver=qcow2,"
                               "file.backing.file.filename=%s,"
+                              "file.backing.file.locking=off,"
                               "file.backing.backing=%s"
                               , S_ID, s_active_disk, s_hidden_disk
                               , S_LOCAL_DISK_ID);
diff --git a/tests/usb-hcd-uhci-test.c b/tests/usb-hcd-uhci-test.c
index f25bae5e6c..5b500fedb0 100644
--- a/tests/usb-hcd-uhci-test.c
+++ b/tests/usb-hcd-uhci-test.c
@@ -79,7 +79,7 @@ int main(int argc, char **argv)
 {
     const char *arch = qtest_get_arch();
     const char *cmd = "-device piix3-usb-uhci,id=uhci,addr=1d.0"
-                      " -drive id=drive0,if=none,file=/dev/null,format=raw"
+                      " -drive id=drive0,if=none,file=null-co://,format=raw"
                       " -device usb-tablet,bus=uhci.0,port=1";
     int ret;
 
diff --git a/tests/usb-hcd-xhci-test.c b/tests/usb-hcd-xhci-test.c
index 22513e9eb5..031764da6d 100644
--- a/tests/usb-hcd-xhci-test.c
+++ b/tests/usb-hcd-xhci-test.c
@@ -89,7 +89,7 @@ int main(int argc, char **argv)
     qtest_add_func("/xhci/pci/hotplug/usb-uas", test_usb_uas_hotplug);
 
     qtest_start("-device nec-usb-xhci,id=xhci"
-                " -drive id=drive0,if=none,file=/dev/null,format=raw");
+                " -drive id=drive0,if=none,file=null-co://,format=raw");
     ret = g_test_run();
     qtest_end();
 
diff --git a/tests/virtio-blk-test.c b/tests/virtio-blk-test.c
index 1eee95df49..fd2078c9da 100644
--- a/tests/virtio-blk-test.c
+++ b/tests/virtio-blk-test.c
@@ -63,7 +63,7 @@ static QOSState *pci_test_start(void)
     const char *arch = qtest_get_arch();
     char *tmp_path;
     const char *cmd = "-drive if=none,id=drive0,file=%s,format=raw "
-                      "-drive if=none,id=drive1,file=/dev/null,format=raw "
+                      "-drive if=none,id=drive1,file=null-co://,format=raw "
                       "-device virtio-blk-pci,id=drv0,drive=drive0,"
                       "addr=%x.%x";
 
diff --git a/tests/virtio-scsi-test.c b/tests/virtio-scsi-test.c
index 0eabd56fd9..8b0f77a63e 100644
--- a/tests/virtio-scsi-test.c
+++ b/tests/virtio-scsi-test.c
@@ -35,7 +35,7 @@ typedef struct {
 static QOSState *qvirtio_scsi_start(const char *extra_opts)
 {
     const char *arch = qtest_get_arch();
-    const char *cmd = "-drive id=drv0,if=none,file=/dev/null,format=raw "
+    const char *cmd = "-drive id=drv0,if=none,file=null-co://,format=raw "
                       "-device virtio-scsi-pci,id=vs0 "
                       "-device scsi-hd,bus=vs0.0,drive=drv0 %s";
 
@@ -195,7 +195,8 @@ static void hotplug(void)
     QDict *response;
     QOSState *qs;
 
-    qs = qvirtio_scsi_start("-drive id=drv1,if=none,file=/dev/null,format=raw");
+    qs = qvirtio_scsi_start(
+            "-drive id=drv1,if=none,file=null-co://,format=raw");
     response = qmp("{\"execute\": \"device_add\","
                    " \"arguments\": {"
                    "   \"driver\": \"scsi-hd\","
author	Stefan Hajnoczi <stefanha@redhat.com>	2017-05-12 09:29:49 -0400
committer	Stefan Hajnoczi <stefanha@redhat.com>	2017-05-12 10:39:08 -0400
commit	3753e255da8f6a654c3e7b650a2d27734bec15f9 (patch)
tree	e2cb28dba28a48ecb3c9912900f74c861620d03a /tests
parent	ecc1f5adeec4e3324d1b695a7c54e3967c526949 (diff)
parent	d541e201bd3ad888f02abeddf0e14f7b0c126529 (diff)