[Qemu-devel] [PATCH for-2.6 v2 0/3] block: Fix drive-mirror with image size unaligned with granularity

[Qemu-devel] [PATCH for-2.6 v2 0/3] block: Fix drive-mirror with image size unaligned with granularity

[Fam Zheng]

v2: Move the mirror_clip_sectors() to mirror_iteration. [Max]

This fixes the bug introduced in e5b43573e28 and lately noticed by Kevin.

Fam Zheng (3):
  mirror: Don't extend the last sub-chunk
  iotests: Add iotests.image_size
  iotests: Test case for drive-mirror with unaligned image size

 block/mirror.c                | 15 +++++++++++--
 tests/qemu-iotests/109.out    | 44 ++++++++++++++++++-------------------
 tests/qemu-iotests/152        | 51 +++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/152.out    |  5 +++++
 tests/qemu-iotests/group      |  1 +
 tests/qemu-iotests/iotests.py |  6 +++++
 6 files changed, 98 insertions(+), 24 deletions(-)
 create mode 100644 tests/qemu-iotests/152
 create mode 100644 tests/qemu-iotests/152.out

-- 
2.5.5

[Qemu-devel] [PATCH for-2.6 v2 1/3] mirror: Don't extend the last sub-chunk

[Fam Zheng]

The last sub-chunk is rounded up to the copy granularity in the target
image, resulting in a larger size than the source.

Add a function to clip the copied sectors to the end.

This undoes the "wrong" changes to tests/qemu-iotests/109.out in
e5b43573e28. The remaining two offset changes are okay.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 block/mirror.c             | 15 +++++++++++++--
 tests/qemu-iotests/109.out | 44 ++++++++++++++++++++++----------------------
 2 files changed, 35 insertions(+), 24 deletions(-)

diff --git a/block/mirror.c b/block/mirror.c
index c2cfc1a..2dd6216 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -161,6 +161,14 @@ static void mirror_read_complete(void *opaque, int ret)
                     mirror_write_complete, op);
 }
 
+static inline void mirror_clip_sectors(MirrorBlockJob *s,
+                                       int64_t sector_num,
+                                       int *nb_sectors)
+{
+    *nb_sectors = MIN(*nb_sectors,
+                      s->bdev_length / BDRV_SECTOR_SIZE - sector_num);
+}
+
 /* Round sector_num and/or nb_sectors to target cluster if COW is needed, and
  * return the offset of the adjusted tail sector against original. */
 static int mirror_cow_align(MirrorBlockJob *s,
@@ -189,6 +197,9 @@ static int mirror_cow_align(MirrorBlockJob *s,
                                                s->target_cluster_sectors);
         }
     }
+    /* Clipping may result in align_nb_sectors unaligned to chunk boundary, but
+     * that doesn't matter because it's already the end of source image. */
+    mirror_clip_sectors(s, align_sector_num, &align_nb_sectors);
 
     ret = align_sector_num + align_nb_sectors - (*sector_num + *nb_sectors);
     *sector_num = align_sector_num;
@@ -231,9 +242,8 @@ static int mirror_do_read(MirrorBlockJob *s, int64_t sector_num,
     /* The sector range must meet granularity because:
      * 1) Caller passes in aligned values;
      * 2) mirror_cow_align is used only when target cluster is larger. */
-    assert(!(nb_sectors % sectors_per_chunk));
     assert(!(sector_num % sectors_per_chunk));
-    nb_chunks = nb_sectors / sectors_per_chunk;
+    nb_chunks = DIV_ROUND_UP(nb_sectors, sectors_per_chunk);
 
     while (s->buf_free_count < nb_chunks) {
         trace_mirror_yield_in_flight(s, sector_num, s->in_flight);
@@ -378,6 +388,7 @@ static uint64_t coroutine_fn mirror_iteration(MirrorBlockJob *s)
             }
         }
 
+        mirror_clip_sectors(s, sector_num, &io_sectors);
         switch (mirror_method) {
         case MIRROR_METHOD_COPY:
             io_sectors = mirror_do_read(s, sector_num, io_sectors);
diff --git a/tests/qemu-iotests/109.out b/tests/qemu-iotests/109.out
index b3358de..38bc073 100644
--- a/tests/qemu-iotests/109.out
+++ b/tests/qemu-iotests/109.out
@@ -10,14 +10,14 @@ Automatically detecting the format is dangerous for raw images, write operations
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action": "report"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 1024, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
 {"return": []}
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 1024, "offset": 1024, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 1024, "offset": 1024, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Warning: Image size mismatch!
 Images are identical.
 
@@ -31,14 +31,14 @@ Automatically detecting the format is dangerous for raw images, write operations
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action": "report"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 262144, "offset": 65536, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 197120, "offset": 512, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
 {"return": []}
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 262144, "offset": 262144, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 262144, "offset": 262144, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 197120, "offset": 197120, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 197120, "offset": 197120, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Warning: Image size mismatch!
 Images are identical.
 
@@ -73,14 +73,14 @@ Automatically detecting the format is dangerous for raw images, write operations
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action": "report"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 1024, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
 {"return": []}
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 1024, "offset": 1024, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 1024, "offset": 1024, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Warning: Image size mismatch!
 Images are identical.
 
@@ -115,14 +115,14 @@ Automatically detecting the format is dangerous for raw images, write operations
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action": "report"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 2560, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
 {"return": []}
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 2560, "offset": 2560, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 2560, "offset": 2560, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Warning: Image size mismatch!
 Images are identical.
 
@@ -135,14 +135,14 @@ Automatically detecting the format is dangerous for raw images, write operations
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action": "report"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 2560, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
 {"return": []}
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 2560, "offset": 2560, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 2560, "offset": 2560, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Image resized.
 Warning: Image size mismatch!
 Images are identical.
@@ -198,14 +198,14 @@ Automatically detecting the format is dangerous for raw images, write operations
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_ERROR", "data": {"device": "src", "operation": "write", "action": "report"}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 65536, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_COMPLETED", "data": {"device": "src", "len": 2048, "offset": 0, "speed": 0, "type": "mirror", "error": "Operation not permitted"}}
 {"return": []}
 read 65536/65536 bytes at offset 0
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 2048, "offset": 2048, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 2048, "offset": 2048, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Image resized.
 Warning: Image size mismatch!
 Images are identical.
@@ -218,14 +218,14 @@ WARNING: Image format was not specified for 'TEST_DIR/t.raw' and probing guessed
 Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
 Specify the 'raw' format explicitly to remove the restrictions.
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 512, "offset": 512, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 512, "offset": 512, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Warning: Image size mismatch!
 Images are identical.
 {"return": {}}
 {"return": {}}
-{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 65536, "offset": 65536, "speed": 0, "type": "mirror"}}
-{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 65536, "offset": 65536, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
+{"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 512, "offset": 512, "speed": 0, "type": "mirror"}}
+{"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 512, "offset": 512, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
 Warning: Image size mismatch!
 Images are identical.
 *** done
-- 
2.5.5

[Qemu-devel] [PATCH for-2.6 v2 2/3] iotests: Add iotests.image_size

[Fam Zheng]

This retrieves the virtual size of the image out of qemu-img info.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 tests/qemu-iotests/iotests.py | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tests/qemu-iotests/iotests.py b/tests/qemu-iotests/iotests.py
index d9ef60e..56f988a 100644
--- a/tests/qemu-iotests/iotests.py
+++ b/tests/qemu-iotests/iotests.py
@@ -28,6 +28,7 @@ sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'scripts', '
 import qmp
 import qtest
 import struct
+import json
 
 
 # This will not work if arguments contain spaces but is necessary if we
@@ -103,6 +104,11 @@ def create_image(name, size):
         i = i + 512
     file.close()
 
+def image_size(img):
+    '''Return image's virtual size'''
+    r = qemu_img_pipe('info', '--output=json', '-f', imgfmt, img)
+    return json.loads(r)['virtual-size']
+
 test_dir_re = re.compile(r"%s" % test_dir)
 def filter_test_dir(msg):
     return test_dir_re.sub("TEST_DIR", msg)
-- 
2.5.5

[Qemu-devel] [PATCH for-2.6 v2 3/3] iotests: Test case for drive-mirror with unaligned image size

[Fam Zheng]

This is the regression test for the virtual size mismatch issue between
target and source images.

Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
---
 tests/qemu-iotests/152     | 51 ++++++++++++++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/152.out |  5 +++++
 tests/qemu-iotests/group   |  1 +
 3 files changed, 57 insertions(+)
 create mode 100644 tests/qemu-iotests/152
 create mode 100644 tests/qemu-iotests/152.out

diff --git a/tests/qemu-iotests/152 b/tests/qemu-iotests/152
new file mode 100644
index 0000000..923beb5
--- /dev/null
+++ b/tests/qemu-iotests/152
@@ -0,0 +1,51 @@
+#!/usr/bin/env python
+#
+# Tests for drive-mirror with source size unaligned to granularity
+#
+# Copyright (C) 2016 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/>.
+#
+
+import os
+import iotests
+from iotests import qemu_img
+
+test_img = os.path.join(iotests.test_dir, 'test.img')
+target_img = os.path.join(iotests.test_dir, 'target.img')
+
+class TestUnaligned(iotests.QMPTestCase):
+    def setUp(self):
+        qemu_img('create', '-f', iotests.imgfmt, test_img, '512')
+        self.vm = iotests.VM().add_drive(test_img)
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(test_img)
+        try:
+            os.remove(target_img)
+        except OSError:
+            pass
+
+    def test_unaligned(self):
+        result = self.vm.qmp('drive-mirror', device='drive0', sync='full',
+                             granularity=65536, target=target_img)
+        self.complete_and_wait()
+        self.vm.shutdown()
+        self.assertEqual(iotests.image_size(test_img), iotests.image_size(target_img),
+                         "Target size doesn't match source when granularity when unaligend")
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=['raw', 'qcow2'])
diff --git a/tests/qemu-iotests/152.out b/tests/qemu-iotests/152.out
new file mode 100644
index 0000000..ae1213e
--- /dev/null
+++ b/tests/qemu-iotests/152.out
@@ -0,0 +1,5 @@
+.
+----------------------------------------------------------------------
+Ran 1 tests
+
+OK
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 2952b9d..822953b 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -152,3 +152,4 @@
 148 rw auto quick
 149 rw auto sudo
 150 rw auto quick
+152 rw auto quick
-- 
2.5.5

Re: [Qemu-devel] [PATCH for-2.6 v2 1/3] mirror: Don't extend the last sub-chunk

[Kevin Wolf]

Am 20.04.2016 um 04:48 hat Fam Zheng geschrieben:
> The last sub-chunk is rounded up to the copy granularity in the target
> image, resulting in a larger size than the source.
> 
> Add a function to clip the copied sectors to the end.
> 
> This undoes the "wrong" changes to tests/qemu-iotests/109.out in
> e5b43573e28. The remaining two offset changes are okay.
> 
> Reported-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Fam Zheng <famz@redhat.com>

I think you're missing at least one place where we need DIV_ROUND_UP
now. Specifically I'm talking about the calculation of nb_chunks in
mirror_iteration_done(), which causes the partial last cluster to stay
marked as in-flight forever.

I would also have used DIV_ROUND_UP in mirror_iteration(), but there we
have a sector_num < end check which saves us from an endless loop.

In order to reproduce the bug, this hangs for me without DIV_ROUND_UP:

$ ls -l /tmp/test.raw
-rw-r--r--. 1 kwolf kwolf 1049600 20. Apr 15:57 /tmp/test.raw
$ (echo -e "drive_mirror none0 /tmp/copy.raw raw\n"; sleep 1; echo -e 'qemu-io none0 "write 1M 512"\nblock_job_complete none0\nquit') | x86_64-softmmu/qemu-system-x86_64 -drive if=none,file=/tmp/test.raw -monitor stdio

Kevin