diff --git a/tests/qemu-iotests/046 b/tests/qemu-iotests/046
new file mode 100755
index 0000000..e0176f4
--- /dev/null
+++ b/tests/qemu-iotests/046
@@ -0,0 +1,215 @@
+#!/bin/bash
+#
+# Test concurrent cluster allocations
+#
+# Copyright (C) 2012 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=kwolf@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
+
+_supported_fmt qcow2
+_supported_proto generic
+_supported_os Linux
+
+CLUSTER_SIZE=64k
+size=128M
+
+echo
+echo "== creating backing file for COW tests =="
+
+_make_test_img $size
+
+function backing_io()
+{
+    local offset=$1
+    local sectors=$2
+    local op=$3
+    local pattern=0
+    local cur_sec=0
+
+    for i in $(seq 0 $((sectors - 1))); do
+        cur_sec=$((offset / 65536 + i))
+        pattern=$(( ( (cur_sec % 128) + (cur_sec / 128)) % 128 ))
+
+        echo "$op -P $pattern $((cur_sec * 64))k 64k"
+    done
+}
+
+backing_io 0 16 write | $QEMU_IO $TEST_IMG | _filter_qemu_io
+
+mv $TEST_IMG $TEST_IMG.base
+
+_make_test_img -b $TEST_IMG.base 6G
+
+echo
+echo "== Some concurrent requests touching the same cluster =="
+
+function overlay_io()
+{
+# Allocate middle of cluster 1, then write to somewhere before and after it
+cat  <<EOF
+break write_aio A
+aio_write -P 10 0x18000 0x2000
+wait_break A
+
+aio_write -P 11 0x12000 0x2000
+aio_write -P 12 0x1c000 0x2000
+
+resume A
+aio_flush
+EOF
+
+# Sequential write case: Alloc middle of cluster 2, then write overlapping
+# to next cluster
+cat  <<EOF
+break write_aio A
+aio_write -P 20 0x28000 0x2000
+wait_break A
+aio_write -P 21 0x2a000 0x10000
+resume A
+aio_flush
+EOF
+
+# The same with a gap between both requests
+cat  <<EOF
+break write_aio A
+aio_write -P 40 0x48000 0x2000
+wait_break A
+aio_write -P 41 0x4c000 0x10000
+resume A
+aio_flush
+EOF
+
+# Sequential write, but the next cluster is already allocated
+cat  <<EOF
+write -P 70 0x76000 0x8000
+aio_flush
+break write_aio A
+aio_write -P 60 0x66000 0x2000
+wait_break A
+aio_write -P 61 0x6a000 0xe000
+resume A
+aio_flush
+EOF
+
+# Sequential write, but the next cluster is already allocated
+# and phyiscally in the right position
+cat  <<EOF
+write -P 89 0x80000 0x1000
+write -P 90 0x96000 0x8000
+aio_flush
+discard 0x80000 0x10000
+aio_flush
+break write_aio A
+aio_write -P 80 0x86000 0x2000
+wait_break A
+aio_write -P 81 0x8a000 0xe000
+resume A
+aio_flush
+EOF
+
+# Sequential write, and the next cluster is compressed
+cat  <<EOF
+write    -P 109 0xa0000 0x1000
+write -c -P 110 0xb0000 0x10000
+aio_flush
+discard 0xa0000 0x10000
+aio_flush
+break write_aio A
+aio_write -P 100 0xa6000 0x2000
+wait_break A
+aio_write -P 101 0xaa000 0xe000
+resume A
+aio_flush
+EOF
+}
+
+overlay_io | $QEMU_IO blkdebug::$TEST_IMG | _filter_qemu_io |\
+	sed -e 's/bytes at offset [0-9]*/bytes at offset XXX/g'
+
+echo
+echo "== Verify image content =="
+
+function verify_io()
+{
+    echo read -P 0 0 0x10000
+
+    echo read -P 1  0x10000 0x2000
+    echo read -P 11 0x12000 0x2000
+    echo read -P 1  0x14000 0x4000
+    echo read -P 10 0x18000 0x2000
+    echo read -P 1  0x1a000 0x2000
+    echo read -P 12 0x1c000 0x2000
+    echo read -P 1  0x1e000 0x2000
+
+    echo read -P 2  0x20000 0x8000
+    echo read -P 20 0x28000 0x2000
+    echo read -P 21 0x2a000 0x10000
+    echo read -P 3  0x3a000 0x6000
+
+    echo read -P 4  0x40000 0x8000
+    echo read -P 40 0x48000 0x2000
+    echo read -P 4  0x4a000 0x2000
+    echo read -P 41 0x4c000 0x10000
+    echo read -P 5  0x5c000 0x4000
+
+    echo read -P 6  0x60000 0x6000
+    echo read -P 60 0x66000 0x2000
+    echo read -P 6  0x68000 0x2000
+    echo read -P 61 0x6a000 0xe000
+    echo read -P 70 0x78000 0x6000
+    echo read -P 7  0x7e000 0x2000
+
+    echo read -P 8  0x80000 0x6000
+    echo read -P 80 0x86000 0x2000
+    echo read -P 8  0x88000 0x2000
+    echo read -P 81 0x8a000 0xe000
+    echo read -P 90 0x98000 0x6000
+    echo read -P 9  0x9e000 0x2000
+
+    echo read -P 10  0xa0000 0x6000
+    echo read -P 100 0xa6000 0x2000
+    echo read -P 10  0xa8000 0x2000
+    echo read -P 101 0xaa000 0xe000
+    echo read -P 110 0xb8000 0x8000
+}
+
+verify_io | $QEMU_IO $TEST_IMG | _filter_qemu_io
+
+_check_test_img
+
+# success, all done
+echo "*** done"
+rm -f $seq.full
+status=0
diff --git a/tests/qemu-iotests/046.out b/tests/qemu-iotests/046.out
new file mode 100644
index 0000000..565360f
--- /dev/null
+++ b/tests/qemu-iotests/046.out
@@ -0,0 +1,163 @@
+QA output created by 046
+
+== creating backing file for COW tests ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728 
+qemu-io> wrote 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 131072
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 196608
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 262144
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 327680
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 393216
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 458752
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 524288
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 589824
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 655360
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 720896
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 786432
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 851968
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 917504
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset 983040
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=6442450944 backing_file='TEST_DIR/t.IMGFMT.base' 
+
+== Some concurrent requests touching the same cluster ==
+qemu-io> qemu-io> qemu-io> blkdebug: Suspended request 'A'
+qemu-io> qemu-io> qemu-io> qemu-io> qemu-io> blkdebug: Resuming request 'A'
+qemu-io> wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> blkdebug: Suspended request 'A'
+qemu-io> qemu-io> qemu-io> blkdebug: Resuming request 'A'
+qemu-io> wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset XXX
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> blkdebug: Suspended request 'A'
+qemu-io> qemu-io> qemu-io> blkdebug: Resuming request 'A'
+qemu-io> wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset XXX
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 32768/32768 bytes at offset XXX
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> qemu-io> blkdebug: Suspended request 'A'
+qemu-io> qemu-io> qemu-io> blkdebug: Resuming request 'A'
+qemu-io> wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 57344/57344 bytes at offset XXX
+56 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 4096/4096 bytes at offset XXX
+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 32768/32768 bytes at offset XXX
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> discard 65536/65536 bytes at offset XXX
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> qemu-io> blkdebug: Suspended request 'A'
+qemu-io> qemu-io> qemu-io> blkdebug: Resuming request 'A'
+qemu-io> wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 57344/57344 bytes at offset XXX
+56 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 4096/4096 bytes at offset XXX
+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> wrote 65536/65536 bytes at offset XXX
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> discard 65536/65536 bytes at offset XXX
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> qemu-io> qemu-io> blkdebug: Suspended request 'A'
+qemu-io> qemu-io> qemu-io> blkdebug: Resuming request 'A'
+qemu-io> wrote 8192/8192 bytes at offset XXX
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 57344/57344 bytes at offset XXX
+56 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> 
+== Verify image content ==
+qemu-io> read 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 65536
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 73728
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 16384/16384 bytes at offset 81920
+16 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 98304
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 106496
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 114688
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 122880
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 32768/32768 bytes at offset 131072
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 163840
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 65536/65536 bytes at offset 172032
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 24576/24576 bytes at offset 237568
+24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 32768/32768 bytes at offset 262144
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 294912
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 303104
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 65536/65536 bytes at offset 311296
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 16384/16384 bytes at offset 376832
+16 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 24576/24576 bytes at offset 393216
+24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 417792
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 425984
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 57344/57344 bytes at offset 434176
+56 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 24576/24576 bytes at offset 491520
+24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 516096
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 24576/24576 bytes at offset 524288
+24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 548864
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 557056
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 57344/57344 bytes at offset 565248
+56 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 24576/24576 bytes at offset 622592
+24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 647168
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 24576/24576 bytes at offset 655360
+24 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 679936
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 8192/8192 bytes at offset 688128
+8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 57344/57344 bytes at offset 696320
+56 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> read 32768/32768 bytes at offset 753664
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+qemu-io> No errors were found on the image.
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 74a1852..580a2ee 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -53,3 +53,4 @@
 045 rw auto
 044 rw auto
 045 rw auto
+046 rw auto aio
