diff --git a/block/block-backend.c b/block/block-backend.c
index 1ac6982..6f9309f 100644
--- a/block/block-backend.c
+++ b/block/block-backend.c
@@ -189,6 +189,11 @@
     g_free(dinfo);
 }
 
+int blk_get_refcnt(BlockBackend *blk)
+{
+    return blk ? blk->refcnt : 0;
+}
+
 /*
  * Increment @blk's reference count.
  * @blk must not be null.
diff --git a/block/mirror.c b/block/mirror.c
index b1252a1..60f1cb5 100644
--- a/block/mirror.c
+++ b/block/mirror.c
@@ -384,6 +384,7 @@
         aio_context_release(replace_aio_context);
     }
     g_free(s->replaces);
+    bdrv_op_unblock_all(s->target, s->common.blocker);
     bdrv_unref(s->target);
     block_job_completed(&s->common, data->ret);
     g_free(data);
@@ -744,6 +745,9 @@
         block_job_release(bs);
         return;
     }
+
+    bdrv_op_block_all(s->target, s->common.blocker);
+
     bdrv_set_enable_write_cache(s->target, true);
     if (s->target->blk) {
         blk_set_on_error(s->target->blk, on_target_error, on_target_error);
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 67be0ce..24a60e2 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -312,7 +312,7 @@
     if (!offset)
         return 0;
 
-    assert(qcow2_get_cluster_type(first_entry) != QCOW2_CLUSTER_COMPRESSED);
+    assert(qcow2_get_cluster_type(first_entry) == QCOW2_CLUSTER_NORMAL);
 
     for (i = 0; i < nb_clusters; i++) {
         uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask;
@@ -324,14 +324,16 @@
 	return i;
 }
 
-static int count_contiguous_free_clusters(int nb_clusters, uint64_t *l2_table)
+static int count_contiguous_clusters_by_type(int nb_clusters,
+                                             uint64_t *l2_table,
+                                             int wanted_type)
 {
     int i;
 
     for (i = 0; i < nb_clusters; i++) {
         int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
 
-        if (type != QCOW2_CLUSTER_UNALLOCATED) {
+        if (type != wanted_type) {
             break;
         }
     }
@@ -554,13 +556,14 @@
             ret = -EIO;
             goto fail;
         }
-        c = count_contiguous_clusters(nb_clusters, s->cluster_size,
-                &l2_table[l2_index], QCOW_OFLAG_ZERO);
+        c = count_contiguous_clusters_by_type(nb_clusters, &l2_table[l2_index],
+                                              QCOW2_CLUSTER_ZERO);
         *cluster_offset = 0;
         break;
     case QCOW2_CLUSTER_UNALLOCATED:
         /* how many empty clusters ? */
-        c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]);
+        c = count_contiguous_clusters_by_type(nb_clusters, &l2_table[l2_index],
+                                              QCOW2_CLUSTER_UNALLOCATED);
         *cluster_offset = 0;
         break;
     case QCOW2_CLUSTER_NORMAL:
diff --git a/blockdev.c b/blockdev.c
index 3197791..8607df9 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3479,6 +3479,72 @@
     qmp_output_visitor_cleanup(ov);
 }
 
+void qmp_x_blockdev_del(bool has_id, const char *id,
+                        bool has_node_name, const char *node_name, Error **errp)
+{
+    AioContext *aio_context;
+    BlockBackend *blk;
+    BlockDriverState *bs;
+
+    if (has_id && has_node_name) {
+        error_setg(errp, "Only one of id and node-name must be specified");
+        return;
+    } else if (!has_id && !has_node_name) {
+        error_setg(errp, "No block device specified");
+        return;
+    }
+
+    if (has_id) {
+        blk = blk_by_name(id);
+        if (!blk) {
+            error_setg(errp, "Cannot find block backend %s", id);
+            return;
+        }
+        if (blk_get_refcnt(blk) > 1) {
+            error_setg(errp, "Block backend %s is in use", id);
+            return;
+        }
+        bs = blk_bs(blk);
+        aio_context = blk_get_aio_context(blk);
+    } else {
+        bs = bdrv_find_node(node_name);
+        if (!bs) {
+            error_setg(errp, "Cannot find node %s", node_name);
+            return;
+        }
+        blk = bs->blk;
+        if (blk) {
+            error_setg(errp, "Node %s is in use by %s",
+                       node_name, blk_name(blk));
+            return;
+        }
+        aio_context = bdrv_get_aio_context(bs);
+    }
+
+    aio_context_acquire(aio_context);
+
+    if (bs) {
+        if (bdrv_op_is_blocked(bs, BLOCK_OP_TYPE_DRIVE_DEL, errp)) {
+            goto out;
+        }
+
+        if (bs->refcnt > 1 || !QLIST_EMPTY(&bs->parents)) {
+            error_setg(errp, "Block device %s is in use",
+                       bdrv_get_device_or_node_name(bs));
+            goto out;
+        }
+    }
+
+    if (blk) {
+        blk_unref(blk);
+    } else {
+        bdrv_unref(bs);
+    }
+
+out:
+    aio_context_release(aio_context);
+}
+
 BlockJobInfoList *qmp_query_block_jobs(Error **errp)
 {
     BlockJobInfoList *head = NULL, **p_next = &head;
diff --git a/include/sysemu/block-backend.h b/include/sysemu/block-backend.h
index 40e315b..f4a68e2 100644
--- a/include/sysemu/block-backend.h
+++ b/include/sysemu/block-backend.h
@@ -65,6 +65,7 @@
 BlockBackend *blk_new_open(const char *name, const char *filename,
                            const char *reference, QDict *options, int flags,
                            Error **errp);
+int blk_get_refcnt(BlockBackend *blk);
 void blk_ref(BlockBackend *blk);
 void blk_unref(BlockBackend *blk);
 const char *blk_name(BlockBackend *blk);
diff --git a/qapi/block-core.json b/qapi/block-core.json
index 083d2cd..470e86c 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1895,8 +1895,8 @@
 # level and no BlockBackend will be created.
 #
 # This command is still a work in progress.  It doesn't support all
-# block drivers, it lacks a matching blockdev-del, and more.  Stay
-# away from it unless you want to help with its development.
+# block drivers among other things.  Stay away from it unless you want
+# to help with its development.
 #
 # @options: block device options for the new device
 #
@@ -1905,6 +1905,34 @@
 { 'command': 'blockdev-add', 'data': { 'options': 'BlockdevOptions' } }
 
 ##
+# @x-blockdev-del:
+#
+# Deletes a block device that has been added using blockdev-add.
+# The selected device can be either a block backend or a graph node.
+#
+# In the former case the backend will be destroyed, along with its
+# inserted medium if there's any. The command will fail if the backend
+# or its medium are in use.
+#
+# In the latter case the node will be destroyed. The command will fail
+# if the node is attached to a block backend or is otherwise being
+# used.
+#
+# One of @id or @node-name must be specified, but not both.
+#
+# This command is still a work in progress and is considered
+# experimental. Stay away from it unless you want to help with its
+# development.
+#
+# @id: #optional Name of the block backend device to delete.
+#
+# @node-name: #optional Name of the graph node to delete.
+#
+# Since: 2.5
+##
+{ 'command': 'x-blockdev-del', 'data': { '*id': 'str', '*node-name': 'str' } }
+
+##
 # @blockdev-open-tray:
 #
 # Opens a block device's tray. If there is a block driver state tree inserted as
diff --git a/qmp-commands.hx b/qmp-commands.hx
index 5fd6f9c..02c0c5b 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -3946,8 +3946,8 @@
 Add a block device.
 
 This command is still a work in progress.  It doesn't support all
-block drivers, it lacks a matching blockdev-del, and more.  Stay away
-from it unless you want to help with its development.
+block drivers among other things.  Stay away from it unless you want
+to help with its development.
 
 Arguments:
 
@@ -3993,6 +3993,63 @@
 EQMP
 
     {
+        .name       = "x-blockdev-del",
+        .args_type  = "id:s?,node-name:s?",
+        .mhandler.cmd_new = qmp_marshal_x_blockdev_del,
+    },
+
+SQMP
+x-blockdev-del
+------------
+Since 2.5
+
+Deletes a block device thas has been added using blockdev-add.
+The selected device can be either a block backend or a graph node.
+
+In the former case the backend will be destroyed, along with its
+inserted medium if there's any. The command will fail if the backend
+or its medium are in use.
+
+In the latter case the node will be destroyed. The command will fail
+if the node is attached to a block backend or is otherwise being
+used.
+
+One of "id" or "node-name" must be specified, but not both.
+
+This command is still a work in progress and is considered
+experimental. Stay away from it unless you want to help with its
+development.
+
+Arguments:
+
+- "id": Name of the block backend device to delete (json-string, optional)
+- "node-name": Name of the graph node to delete (json-string, optional)
+
+Example:
+
+-> { "execute": "blockdev-add",
+     "arguments": {
+         "options": {
+             "driver": "qcow2",
+             "id": "drive0",
+             "file": {
+                 "driver": "file",
+                 "filename": "test.qcow2"
+             }
+         }
+     }
+   }
+
+<- { "return": {} }
+
+-> { "execute": "x-blockdev-del",
+     "arguments": { "id": "drive0" }
+   }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "blockdev-open-tray",
         .args_type  = "device:s,force:b?",
         .mhandler.cmd_new = qmp_marshal_blockdev_open_tray,
diff --git a/tests/qemu-iotests/039.out b/tests/qemu-iotests/039.out
index 03a31c5..32c8846 100644
--- a/tests/qemu-iotests/039.out
+++ b/tests/qemu-iotests/039.out
@@ -11,7 +11,11 @@
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-./common.config: Killed                  ( exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@" )
+./common.config: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
+    exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+else
+    exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+fi )
 incompatible_features     0x1
 ERROR cluster 5 refcount=0 reference=1
 ERROR OFLAG_COPIED data cluster: l2_entry=8000000000050000 refcount=0
@@ -46,7 +50,11 @@
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-./common.config: Killed                  ( exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@" )
+./common.config: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
+    exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+else
+    exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+fi )
 incompatible_features     0x1
 ERROR cluster 5 refcount=0 reference=1
 Rebuilding refcount structure
@@ -60,7 +68,11 @@
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-./common.config: Killed                  ( exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@" )
+./common.config: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
+    exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+else
+    exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+fi )
 incompatible_features     0x0
 No errors were found on the image.
 
@@ -79,7 +91,11 @@
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-./common.config: Killed                  ( exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@" )
+./common.config: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
+    exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+else
+    exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+fi )
 incompatible_features     0x1
 ERROR cluster 5 refcount=0 reference=1
 ERROR OFLAG_COPIED data cluster: l2_entry=8000000000050000 refcount=0
@@ -89,7 +105,11 @@
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-./common.config: Killed                  ( exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@" )
+./common.config: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
+    exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+else
+    exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+fi )
 incompatible_features     0x0
 No errors were found on the image.
 *** done
diff --git a/tests/qemu-iotests/058 b/tests/qemu-iotests/058
index f2bdd0b..63a6598 100755
--- a/tests/qemu-iotests/058
+++ b/tests/qemu-iotests/058
@@ -32,11 +32,17 @@
 
 nbd_unix_socket=$TEST_DIR/test_qemu_nbd_socket
 nbd_snapshot_img="nbd:unix:$nbd_unix_socket"
+rm -f "${TEST_DIR}/qemu-nbd.pid"
 
 _cleanup_nbd()
 {
-    if [ -n "$NBD_SNAPSHOT_PID" ]; then
-        kill "$NBD_SNAPSHOT_PID"
+    local NBD_SNAPSHOT_PID
+    if [ -f "${TEST_DIR}/qemu-nbd.pid" ]; then
+        read NBD_SNAPSHOT_PID < "${TEST_DIR}/qemu-nbd.pid"
+        rm -f "${TEST_DIR}/qemu-nbd.pid"
+        if [ -n "$NBD_SNAPSHOT_PID" ]; then
+            kill "$NBD_SNAPSHOT_PID"
+        fi
     fi
     rm -f "$nbd_unix_socket"
 }
@@ -60,7 +66,6 @@
 {
     _cleanup_nbd
     $QEMU_NBD -v -t -k "$nbd_unix_socket" "$TEST_IMG" -l $1 &
-    NBD_SNAPSHOT_PID=$!
     _wait_for_nbd
 }
 
@@ -68,7 +73,6 @@
 {
     _cleanup_nbd
     $QEMU_NBD -v -t -k "$nbd_unix_socket" "$TEST_IMG" -l snapshot.name=$1 &
-    NBD_SNAPSHOT_PID=$!
     _wait_for_nbd
 }
 
diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out
index b16bea9..f2598a8 100644
--- a/tests/qemu-iotests/061.out
+++ b/tests/qemu-iotests/061.out
Binary files differ
diff --git a/tests/qemu-iotests/137.out b/tests/qemu-iotests/137.out
index cf55a41..88c702c 100644
--- a/tests/qemu-iotests/137.out
+++ b/tests/qemu-iotests/137.out
@@ -31,7 +31,11 @@
 Unsupported value 'blubb' for qcow2 option 'overlap-check'. Allowed are any of the following: none, constant, cached, all
 wrote 512/512 bytes at offset 0
 512 bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-./common.config: Killed                  ( exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@" )
+./common.config: Killed                  ( if [ "${VALGRIND_QEMU}" == "y" ]; then
+    exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+else
+    exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@";
+fi )
 incompatible_features     0x0
 Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864
 wrote 65536/65536 bytes at offset 0
diff --git a/tests/qemu-iotests/139 b/tests/qemu-iotests/139
new file mode 100644
index 0000000..42f78c7
--- /dev/null
+++ b/tests/qemu-iotests/139
@@ -0,0 +1,416 @@
+#!/usr/bin/env python
+#
+# Test cases for the QMP 'x-blockdev-del' command
+#
+# Copyright (C) 2015 Igalia, S.L.
+# Author: Alberto Garcia <berto@igalia.com>
+#
+# 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
+import time
+
+base_img = os.path.join(iotests.test_dir, 'base.img')
+new_img = os.path.join(iotests.test_dir, 'new.img')
+
+class TestBlockdevDel(iotests.QMPTestCase):
+
+    def setUp(self):
+        iotests.qemu_img('create', '-f', iotests.imgfmt, base_img, '1M')
+        self.vm = iotests.VM()
+        self.vm.launch()
+
+    def tearDown(self):
+        self.vm.shutdown()
+        os.remove(base_img)
+        if os.path.isfile(new_img):
+            os.remove(new_img)
+
+    # Check whether a BlockBackend exists
+    def checkBlockBackend(self, backend, node, must_exist = True):
+        result = self.vm.qmp('query-block')
+        backends = filter(lambda x: x['device'] == backend, result['return'])
+        self.assertLessEqual(len(backends), 1)
+        self.assertEqual(must_exist, len(backends) == 1)
+        if must_exist:
+            if node:
+                self.assertEqual(backends[0]['inserted']['node-name'], node)
+            else:
+                self.assertFalse(backends[0].has_key('inserted'))
+
+    # Check whether a BlockDriverState exists
+    def checkBlockDriverState(self, node, must_exist = True):
+        result = self.vm.qmp('query-named-block-nodes')
+        nodes = filter(lambda x: x['node-name'] == node, result['return'])
+        self.assertLessEqual(len(nodes), 1)
+        self.assertEqual(must_exist, len(nodes) == 1)
+
+    # Add a new BlockBackend (with its attached BlockDriverState)
+    def addBlockBackend(self, backend, node):
+        file_node = '%s_file' % node
+        self.checkBlockBackend(backend, node, False)
+        self.checkBlockDriverState(node, False)
+        self.checkBlockDriverState(file_node, False)
+        opts = {'driver': iotests.imgfmt,
+                'id': backend,
+                'node-name': node,
+                'file': {'driver': 'file',
+                         'node-name': file_node,
+                         'filename': base_img}}
+        result = self.vm.qmp('blockdev-add', conv_keys = False, options = opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockBackend(backend, node)
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(file_node)
+
+    # Add a BlockDriverState without a BlockBackend
+    def addBlockDriverState(self, node):
+        file_node = '%s_file' % node
+        self.checkBlockDriverState(node, False)
+        self.checkBlockDriverState(file_node, False)
+        opts = {'driver': iotests.imgfmt,
+                'node-name': node,
+                'file': {'driver': 'file',
+                         'node-name': file_node,
+                         'filename': base_img}}
+        result = self.vm.qmp('blockdev-add', conv_keys = False, options = opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(file_node)
+
+    # Add a BlockDriverState that will be used as overlay for the base_img BDS
+    def addBlockDriverStateOverlay(self, node):
+        self.checkBlockDriverState(node, False)
+        iotests.qemu_img('create', '-f', iotests.imgfmt,
+                         '-b', base_img, new_img, '1M')
+        opts = {'driver': iotests.imgfmt,
+                'node-name': node,
+                'backing': '',
+                'file': {'driver': 'file',
+                         'filename': new_img}}
+        result = self.vm.qmp('blockdev-add', conv_keys = False, options = opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(node)
+
+    # Delete a BlockBackend
+    def delBlockBackend(self, backend, node, expect_error = False,
+                        destroys_media = True):
+        self.checkBlockBackend(backend, node)
+        if node:
+            self.checkBlockDriverState(node)
+        result = self.vm.qmp('x-blockdev-del', id = backend)
+        if expect_error:
+            self.assert_qmp(result, 'error/class', 'GenericError')
+            if node:
+                self.checkBlockDriverState(node)
+        else:
+            self.assert_qmp(result, 'return', {})
+            if node:
+                self.checkBlockDriverState(node, not destroys_media)
+        self.checkBlockBackend(backend, node, must_exist = expect_error)
+
+    # Delete a BlockDriverState
+    def delBlockDriverState(self, node, expect_error = False):
+        self.checkBlockDriverState(node)
+        result = self.vm.qmp('x-blockdev-del', node_name = node)
+        if expect_error:
+            self.assert_qmp(result, 'error/class', 'GenericError')
+        else:
+            self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(node, expect_error)
+
+    # Add a device model
+    def addDeviceModel(self, device, backend):
+        result = self.vm.qmp('device_add', id = device,
+                             driver = 'virtio-blk-pci', drive = backend)
+        self.assert_qmp(result, 'return', {})
+
+    # Delete a device model
+    def delDeviceModel(self, device):
+        result = self.vm.qmp('device_del', id = device)
+        self.assert_qmp(result, 'return', {})
+
+        result = self.vm.qmp('system_reset')
+        self.assert_qmp(result, 'return', {})
+
+        device_path = '/machine/peripheral/%s/virtio-backend' % device
+        event = self.vm.event_wait(name="DEVICE_DELETED",
+                                   match={'data': {'path': device_path}})
+        self.assertNotEqual(event, None)
+
+        event = self.vm.event_wait(name="DEVICE_DELETED",
+                                   match={'data': {'device': device}})
+        self.assertNotEqual(event, None)
+
+    # Remove a BlockDriverState
+    def ejectDrive(self, backend, node, expect_error = False,
+                   destroys_media = True):
+        self.checkBlockBackend(backend, node)
+        self.checkBlockDriverState(node)
+        result = self.vm.qmp('eject', device = backend)
+        if expect_error:
+            self.assert_qmp(result, 'error/class', 'GenericError')
+            self.checkBlockDriverState(node)
+            self.checkBlockBackend(backend, node)
+        else:
+            self.assert_qmp(result, 'return', {})
+            self.checkBlockDriverState(node, not destroys_media)
+            self.checkBlockBackend(backend, None)
+
+    # Insert a BlockDriverState
+    def insertDrive(self, backend, node):
+        self.checkBlockBackend(backend, None)
+        self.checkBlockDriverState(node)
+        result = self.vm.qmp('blockdev-insert-medium',
+                             device = backend, node_name = node)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockBackend(backend, node)
+        self.checkBlockDriverState(node)
+
+    # Create a snapshot using 'blockdev-snapshot-sync'
+    def createSnapshotSync(self, node, overlay):
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(overlay, False)
+        opts = {'node-name': node,
+                'snapshot-file': new_img,
+                'snapshot-node-name': overlay,
+                'format': iotests.imgfmt}
+        result = self.vm.qmp('blockdev-snapshot-sync', conv_keys=False, **opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(overlay)
+
+    # Create a snapshot using 'blockdev-snapshot'
+    def createSnapshot(self, node, overlay):
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(overlay)
+        result = self.vm.qmp('blockdev-snapshot',
+                             node = node, overlay = overlay)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(overlay)
+
+    # Create a mirror
+    def createMirror(self, backend, node, new_node):
+        self.checkBlockBackend(backend, node)
+        self.checkBlockDriverState(new_node, False)
+        opts = {'device': backend,
+                'target': new_img,
+                'node-name': new_node,
+                'sync': 'top',
+                'format': iotests.imgfmt}
+        result = self.vm.qmp('drive-mirror', conv_keys=False, **opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockBackend(backend, node)
+        self.checkBlockDriverState(new_node)
+
+    # Complete an existing block job
+    def completeBlockJob(self, backend, node_before, node_after):
+        self.checkBlockBackend(backend, node_before)
+        result = self.vm.qmp('block-job-complete', device=backend)
+        self.assert_qmp(result, 'return', {})
+        self.wait_until_completed(backend)
+        self.checkBlockBackend(backend, node_after)
+
+    # Add a BlkDebug node
+    # Note that the purpose of this is to test the x-blockdev-del
+    # sanity checks, not to create a usable blkdebug drive
+    def addBlkDebug(self, debug, node):
+        self.checkBlockDriverState(node, False)
+        self.checkBlockDriverState(debug, False)
+        image = {'driver': iotests.imgfmt,
+                 'node-name': node,
+                 'file': {'driver': 'file',
+                          'filename': base_img}}
+        opts = {'driver': 'blkdebug',
+                'node-name': debug,
+                'image': image}
+        result = self.vm.qmp('blockdev-add', conv_keys = False, options = opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(node)
+        self.checkBlockDriverState(debug)
+
+    # Add a BlkVerify node
+    # Note that the purpose of this is to test the x-blockdev-del
+    # sanity checks, not to create a usable blkverify drive
+    def addBlkVerify(self, blkverify, test, raw):
+        self.checkBlockDriverState(test, False)
+        self.checkBlockDriverState(raw, False)
+        self.checkBlockDriverState(blkverify, False)
+        iotests.qemu_img('create', '-f', iotests.imgfmt, new_img, '1M')
+        node_0 = {'driver': iotests.imgfmt,
+                  'node-name': test,
+                  'file': {'driver': 'file',
+                           'filename': base_img}}
+        node_1 = {'driver': iotests.imgfmt,
+                  'node-name': raw,
+                  'file': {'driver': 'file',
+                           'filename': new_img}}
+        opts = {'driver': 'blkverify',
+                'node-name': blkverify,
+                'test': node_0,
+                'raw': node_1}
+        result = self.vm.qmp('blockdev-add', conv_keys = False, options = opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(test)
+        self.checkBlockDriverState(raw)
+        self.checkBlockDriverState(blkverify)
+
+    # Add a Quorum node
+    def addQuorum(self, quorum, child0, child1):
+        self.checkBlockDriverState(child0, False)
+        self.checkBlockDriverState(child1, False)
+        self.checkBlockDriverState(quorum, False)
+        iotests.qemu_img('create', '-f', iotests.imgfmt, new_img, '1M')
+        child_0 = {'driver': iotests.imgfmt,
+                   'node-name': child0,
+                   'file': {'driver': 'file',
+                            'filename': base_img}}
+        child_1 = {'driver': iotests.imgfmt,
+                   'node-name': child1,
+                   'file': {'driver': 'file',
+                            'filename': new_img}}
+        opts = {'driver': 'quorum',
+                'node-name': quorum,
+                'vote-threshold': 1,
+                'children': [ child_0, child_1 ]}
+        result = self.vm.qmp('blockdev-add', conv_keys = False, options = opts)
+        self.assert_qmp(result, 'return', {})
+        self.checkBlockDriverState(child0)
+        self.checkBlockDriverState(child1)
+        self.checkBlockDriverState(quorum)
+
+    ########################
+    # The tests start here #
+    ########################
+
+    def testWrongParameters(self):
+        self.addBlockBackend('drive0', 'node0')
+        result = self.vm.qmp('x-blockdev-del')
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        result = self.vm.qmp('x-blockdev-del', id='drive0', node_name='node0')
+        self.assert_qmp(result, 'error/class', 'GenericError')
+        self.delBlockBackend('drive0', 'node0')
+
+    def testBlockBackend(self):
+        self.addBlockBackend('drive0', 'node0')
+        # You cannot delete a BDS that is attached to a backend
+        self.delBlockDriverState('node0', expect_error = True)
+        self.delBlockBackend('drive0', 'node0')
+
+    def testBlockDriverState(self):
+        self.addBlockDriverState('node0')
+        # You cannot delete a file BDS directly
+        self.delBlockDriverState('node0_file', expect_error = True)
+        self.delBlockDriverState('node0')
+
+    def testEject(self):
+        self.addBlockBackend('drive0', 'node0')
+        self.ejectDrive('drive0', 'node0')
+        self.delBlockBackend('drive0', None)
+
+    def testDeviceModel(self):
+        self.addBlockBackend('drive0', 'node0')
+        self.addDeviceModel('device0', 'drive0')
+        self.ejectDrive('drive0', 'node0', expect_error = True)
+        self.delBlockBackend('drive0', 'node0', expect_error = True)
+        self.delDeviceModel('device0')
+        self.delBlockBackend('drive0', 'node0')
+
+    def testAttachMedia(self):
+        # This creates a BlockBackend and removes its media
+        self.addBlockBackend('drive0', 'node0')
+        self.ejectDrive('drive0', 'node0')
+        # This creates a new BlockDriverState and inserts it into the backend
+        self.addBlockDriverState('node1')
+        self.insertDrive('drive0', 'node1')
+        # The backend can't be removed: the new BDS has an extra reference
+        self.delBlockBackend('drive0', 'node1', expect_error = True)
+        self.delBlockDriverState('node1', expect_error = True)
+        # The BDS still exists after being ejected, but now it can be removed
+        self.ejectDrive('drive0', 'node1', destroys_media = False)
+        self.delBlockDriverState('node1')
+        self.delBlockBackend('drive0', None)
+
+    def testSnapshotSync(self):
+        self.addBlockBackend('drive0', 'node0')
+        self.createSnapshotSync('node0', 'overlay0')
+        # This fails because node0 is now being used as a backing image
+        self.delBlockDriverState('node0', expect_error = True)
+        # This succeeds because overlay0 only has the backend reference
+        self.delBlockBackend('drive0', 'overlay0')
+        self.checkBlockDriverState('node0', False)
+
+    def testSnapshot(self):
+        self.addBlockBackend('drive0', 'node0')
+        self.addBlockDriverStateOverlay('overlay0')
+        self.createSnapshot('node0', 'overlay0')
+        self.delBlockBackend('drive0', 'overlay0', expect_error = True)
+        self.delBlockDriverState('node0', expect_error = True)
+        self.delBlockDriverState('overlay0', expect_error = True)
+        self.ejectDrive('drive0', 'overlay0', destroys_media = False)
+        self.delBlockBackend('drive0', None)
+        self.delBlockDriverState('node0', expect_error = True)
+        self.delBlockDriverState('overlay0')
+        self.checkBlockDriverState('node0', False)
+
+    def testMirror(self):
+        self.addBlockBackend('drive0', 'node0')
+        self.createMirror('drive0', 'node0', 'mirror0')
+        # The block job prevents removing the device
+        self.delBlockBackend('drive0', 'node0', expect_error = True)
+        self.delBlockDriverState('node0', expect_error = True)
+        self.delBlockDriverState('mirror0', expect_error = True)
+        self.wait_ready('drive0')
+        self.completeBlockJob('drive0', 'node0', 'mirror0')
+        self.assert_no_active_block_jobs()
+        self.checkBlockDriverState('node0', False)
+        # This succeeds because the backend now points to mirror0
+        self.delBlockBackend('drive0', 'mirror0')
+
+    def testBlkDebug(self):
+        self.addBlkDebug('debug0', 'node0')
+        # 'node0' is used by the blkdebug node
+        self.delBlockDriverState('node0', expect_error = True)
+        # But we can remove the blkdebug node directly
+        self.delBlockDriverState('debug0')
+        self.checkBlockDriverState('node0', False)
+
+    def testBlkVerify(self):
+        self.addBlkVerify('verify0', 'node0', 'node1')
+        # We cannot remove the children of a blkverify device
+        self.delBlockDriverState('node0', expect_error = True)
+        self.delBlockDriverState('node1', expect_error = True)
+        # But we can remove the blkverify node directly
+        self.delBlockDriverState('verify0')
+        self.checkBlockDriverState('node0', False)
+        self.checkBlockDriverState('node1', False)
+
+    def testQuorum(self):
+        if not 'quorum' in iotests.qemu_img_pipe('--help'):
+            return
+        self.addQuorum('quorum0', 'node0', 'node1')
+        # We cannot remove the children of a Quorum device
+        self.delBlockDriverState('node0', expect_error = True)
+        self.delBlockDriverState('node1', expect_error = True)
+        # But we can remove the Quorum node directly
+        self.delBlockDriverState('quorum0')
+        self.checkBlockDriverState('node0', False)
+        self.checkBlockDriverState('node1', False)
+
+
+if __name__ == '__main__':
+    iotests.main(supported_fmts=["qcow2"])
diff --git a/tests/qemu-iotests/139.out b/tests/qemu-iotests/139.out
new file mode 100644
index 0000000..281b69e
--- /dev/null
+++ b/tests/qemu-iotests/139.out
@@ -0,0 +1,5 @@
+............
+----------------------------------------------------------------------
+Ran 12 tests
+
+OK
diff --git a/tests/qemu-iotests/common b/tests/qemu-iotests/common
index 25c351b..ff84f4b 100644
--- a/tests/qemu-iotests/common
+++ b/tests/qemu-iotests/common
@@ -41,7 +41,6 @@
 expunge=true
 have_test_arg=false
 randomize=false
-valgrind=false
 cachemode=false
 rm -f $tmp.list $tmp.tmp $tmp.sed
 
@@ -53,6 +52,7 @@
 export QEMU_IO_OPTIONS=""
 export CACHEMODE_IS_DEFAULT=true
 export QEMU_OPTIONS="-nodefaults"
+export VALGRIND_QEMU=
 
 for r
 do
@@ -278,7 +278,7 @@
             ;;
 
         -valgrind)
-            valgrind=true
+            VALGRIND_QEMU='y'
             xpand=false
             ;;
 
@@ -436,8 +436,3 @@
 if [ "$IMGPROTO" = "nbd" ] ; then
     [ "$QEMU_NBD" = "" ] && _fatal "qemu-nbd not found"
 fi
-
-if $valgrind; then
-    export REAL_QEMU_IO="$QEMU_IO_PROG"
-    export QEMU_IO_PROG=valgrind_qemu_io
-fi
diff --git a/tests/qemu-iotests/common.config b/tests/qemu-iotests/common.config
index 596bb2b..3ed51b8 100644
--- a/tests/qemu-iotests/common.config
+++ b/tests/qemu-iotests/common.config
@@ -44,6 +44,8 @@
 export CHECK_OPTIONS=${CHECK_OPTIONS:="-g auto"}
 export PWD=`pwd`
 
+export _QEMU_HANDLE=0
+
 # $1 = prog to look for, $2* = default pathnames if not found in $PATH
 set_prog_path()
 {
@@ -105,7 +107,12 @@
 
 _qemu_wrapper()
 {
-    (exec "$QEMU_PROG" $QEMU_OPTIONS "$@")
+    (
+        if [ -n "${QEMU_NEED_PID}" ]; then
+            echo $BASHPID > "${TEST_DIR}/qemu-${_QEMU_HANDLE}.pid"
+        fi
+        exec "$QEMU_PROG" $QEMU_OPTIONS "$@"
+    )
 }
 
 _qemu_img_wrapper()
@@ -115,12 +122,31 @@
 
 _qemu_io_wrapper()
 {
-    (exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@")
+    local VALGRIND_LOGFILE=/tmp/$$.valgrind
+    local RETVAL
+    (
+        if [ "${VALGRIND_QEMU}" == "y" ]; then
+            exec valgrind --log-file="${VALGRIND_LOGFILE}" --error-exitcode=99 "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@"
+        else
+            exec "$QEMU_IO_PROG" $QEMU_IO_OPTIONS "$@"
+        fi
+    )
+    RETVAL=$?
+    if [ "${VALGRIND_QEMU}" == "y" ]; then
+        if [ $RETVAL == 99 ]; then
+            cat "${VALGRIND_LOGFILE}"
+        fi
+        rm -f "${VALGRIND_LOGFILE}"
+    fi
+    (exit $RETVAL)
 }
 
 _qemu_nbd_wrapper()
 {
-    (exec "$QEMU_NBD_PROG" $QEMU_NBD_OPTIONS "$@")
+    (
+        echo $BASHPID > "${TEST_DIR}/qemu-nbd.pid"
+        exec "$QEMU_NBD_PROG" $QEMU_NBD_OPTIONS "$@"
+    )
 }
 
 export QEMU=_qemu_wrapper
diff --git a/tests/qemu-iotests/common.qemu b/tests/qemu-iotests/common.qemu
index e3faa53..8bf3969 100644
--- a/tests/qemu-iotests/common.qemu
+++ b/tests/qemu-iotests/common.qemu
@@ -30,8 +30,6 @@
 QEMU_FIFO_IN="${TEST_DIR}/qmp-in-$$"
 QEMU_FIFO_OUT="${TEST_DIR}/qmp-out-$$"
 
-QEMU_PID=
-_QEMU_HANDLE=0
 QEMU_HANDLE=0
 
 # If bash version is >= 4.1, these will be overwritten and dynamic
@@ -153,11 +151,11 @@
     mkfifo "${fifo_out}"
     mkfifo "${fifo_in}"
 
+    QEMU_NEED_PID='y'\
     ${QEMU} -nographic -serial none ${comm} -machine accel=qtest "${@}" \
                                                                 >"${fifo_out}" \
                                                                 2>&1 \
                                                                 <"${fifo_in}" &
-    QEMU_PID[${_QEMU_HANDLE}]=$!
 
     if [[ "${BASH_VERSINFO[0]}" -ge "5" ||
         ("${BASH_VERSINFO[0]}" -ge "4"  &&  "${BASH_VERSINFO[1]}" -ge "1") ]]
@@ -196,10 +194,18 @@
     # QEMU_PID[], QEMU_IN[], QEMU_OUT[] all use same indices
     for i in "${!QEMU_OUT[@]}"
     do
-        if [ -z "${wait}" ]; then
-            kill -KILL ${QEMU_PID[$i]} 2>/dev/null
+        local QEMU_PID
+        if [ -f "${TEST_DIR}/qemu-${i}.pid" ]; then
+            read QEMU_PID < "${TEST_DIR}/qemu-${i}.pid"
+            rm -f "${TEST_DIR}/qemu-${i}.pid"
+            if [ -z "${wait}" ] && [ -n "${QEMU_PID}" ]; then
+                kill -KILL ${QEMU_PID} 2>/dev/null
+            fi
+            if [ -n "${QEMU_PID}" ]; then
+                wait ${QEMU_PID} 2>/dev/null # silent kill
+            fi
         fi
-        wait ${QEMU_PID[$i]} 2>/dev/null # silent kill
+
         if [ -n "${wait}" ]; then
             cat <&${QEMU_OUT[$i]} | _filter_testdir | _filter_qemu \
                                   | _filter_qemu_io | _filter_qmp
diff --git a/tests/qemu-iotests/common.rc b/tests/qemu-iotests/common.rc
index 28e4bea..d9913f8 100644
--- a/tests/qemu-iotests/common.rc
+++ b/tests/qemu-iotests/common.rc
@@ -70,16 +70,6 @@
     TEST_IMG=$IMGPROTO:$TEST_DIR/t.$IMGFMT
 fi
 
-function valgrind_qemu_io()
-{
-    valgrind --log-file=/tmp/$$.valgrind --error-exitcode=99 $REAL_QEMU_IO "$@"
-    if [ $? != 0 ]; then
-        cat /tmp/$$.valgrind
-    fi
-    rm -f /tmp/$$.valgrind
-}
-
-
 _optstr_add()
 {
     if [ -n "$1" ]; then
@@ -154,7 +144,6 @@
     # Start an NBD server on the image file, which is what we'll be talking to
     if [ $IMGPROTO = "nbd" ]; then
         eval "$QEMU_NBD -v -t -b 127.0.0.1 -p 10810 -f $IMGFMT  $TEST_IMG_FILE &"
-        QEMU_NBD_PID=$!
         sleep 1 # FIXME: qemu-nbd needs to be listening before we continue
     fi
 }
@@ -175,8 +164,11 @@
     case "$IMGPROTO" in
 
         nbd)
-            if [ -n "$QEMU_NBD_PID" ]; then
-                kill $QEMU_NBD_PID
+            if [ -f "${TEST_DIR}/qemu-nbd.pid" ]; then
+                local QEMU_NBD_PID
+                read QEMU_NBD_PID < "${TEST_DIR}/qemu-nbd.pid"
+                kill ${QEMU_NBD_PID}
+                rm -f "${TEST_DIR}/qemu-nbd.pid"
             fi
             rm -f "$TEST_IMG_FILE"
             ;;
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index a6a61ae..c69265d 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -138,3 +138,4 @@
 135 rw auto
 137 rw auto
 138 rw auto quick
+139 rw auto quick