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

Block layer patches

# gpg: Signature made Thu 19 May 2016 16:09:27 BST using RSA key ID C88F2FD6
# gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>"

* remotes/kevin/tags/for-upstream: (31 commits)
  qemu-iotests: Fix regression in 136 on aio_read invalid
  qemu-iotests: Simplify 109 with unaligned qemu-img compare
  qemu-io: Fix recent UI updates
  block: clarify error message for qmp-eject
  qemu-iotests: Some more write_zeroes tests
  qcow2: Fix write_zeroes with partially allocated backing file cluster
  qcow2: fix condition in is_zero_cluster
  block: Propagate AioContext change to all children
  block: Remove BlockDriverState.blk
  block: Don't return throttling info in query-named-block-nodes
  block: Avoid bs->blk in bdrv_next()
  block: Add bdrv_has_blk()
  block: Remove bdrv_aio_multiwrite()
  blockjob: Don't touch BDS iostatus
  blockjob: Don't set iostatus of target
  block: User BdrvChild callback for device name
  block: Use BdrvChild callbacks for change_media/resize
  block: Don't check throttled reqs in bdrv_requests_pending()
  Revert "block: Forbid I/O throttling on nodes with multiple parents for 2.6"
  block: Remove bdrv_move_feature_fields()
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

11 files changed, 555 insertions, 320 deletions

diff --git a/tests/qemu-iotests/096 b/tests/qemu-iotests/096
index e34204b8ff..aeeb3753cf 100644
--- a/tests/qemu-iotests/096
+++ b/tests/qemu-iotests/096
@@ -45,8 +45,9 @@ class TestLiveSnapshot(iotests.QMPTestCase):
         os.remove(self.target_img)
 
     def checkConfig(self, active_layer):
-        result = self.vm.qmp('query-named-block-nodes')
+        result = self.vm.qmp('query-block')
         for r in result['return']:
+            r = r['inserted']
             if r['node-name'] == active_layer:
                 self.assertEqual(r['group'], self.group)
                 self.assertEqual(r['iops'], self.iops)
diff --git a/tests/qemu-iotests/100 b/tests/qemu-iotests/100
deleted file mode 100755
index e66db07982..0000000000
--- a/tests/qemu-iotests/100
+++ /dev/null
@@ -1,152 +0,0 @@
-#!/bin/bash
-#
-# Test simple read/write using plain bdrv_read/bdrv_write
-#
-# Copyright (C) 2014 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=stefanha@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 generic
-_supported_proto generic
-_supported_os Linux
-
-
-size=128M
-
-echo
-echo "== Single request =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 8k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 0 4k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-$QEMU_IO -c "read -P 0xcd 0 4k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 4k 4k" "$TEST_IMG" | _filter_qemu_io
-
-_cleanup_test_img
-
-echo
-echo "== Sequential requests =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 12k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 0 4k ; 4k 4k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-$QEMU_IO -c "read -P 0xcd 0 4k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0xce 4k 4k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 8k 4k" "$TEST_IMG" | _filter_qemu_io
-
-_cleanup_test_img
-
-echo
-echo "== Superset overlapping requests =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 8k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 0 4k ; 1k 2k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-# Order of overlapping in-flight requests is not guaranteed so we cannot verify
-# [1k, 3k) since it could have either pattern 0xcd or 0xce.
-$QEMU_IO -c "read -P 0xcd 0 1k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0xcd 3k 1k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 4k 4k" "$TEST_IMG" | _filter_qemu_io
-
-_cleanup_test_img
-
-echo
-echo "== Subset overlapping requests =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 8k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 1k 2k ; 0k 4k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-# Order of overlapping in-flight requests is not guaranteed so we cannot verify
-# [1k, 3k) since it could have either pattern 0xcd or 0xce.
-$QEMU_IO -c "read -P 0xce 0 1k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0xce 3k 1k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 4k 4k" "$TEST_IMG" | _filter_qemu_io
-
-_cleanup_test_img
-
-echo
-echo "== Head overlapping requests =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 8k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 0k 2k ; 0k 4k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-# Order of overlapping in-flight requests is not guaranteed so we cannot verify
-# [0k, 2k) since it could have either pattern 0xcd or 0xce.
-$QEMU_IO -c "read -P 0xce 2k 2k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 4k 4k" "$TEST_IMG" | _filter_qemu_io
-
-_cleanup_test_img
-
-echo
-echo "== Tail overlapping requests =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 8k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 2k 2k ; 0k 4k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-# Order of overlapping in-flight requests is not guaranteed so we cannot verify
-# [2k, 4k) since it could have either pattern 0xcd or 0xce.
-$QEMU_IO -c "read -P 0xce 0k 2k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 4k 4k" "$TEST_IMG" | _filter_qemu_io
-
-_cleanup_test_img
-
-echo
-echo "== Disjoint requests =="
-_make_test_img $size
-$QEMU_IO -c "write -z 0 72k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "multiwrite 0 4k ; 64k 4k" "$TEST_IMG" | _filter_qemu_io
-
-echo
-echo "== verify pattern =="
-$QEMU_IO -c "read -P 0xcd 0 4k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 4k 60k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0xce 64k 4k" "$TEST_IMG" | _filter_qemu_io
-$QEMU_IO -c "read -P 0 68k 4k" "$TEST_IMG" | _filter_qemu_io
-
-# success, all done
-echo "*** done"
-rm -f $seq.full
-status=0
diff --git a/tests/qemu-iotests/100.out b/tests/qemu-iotests/100.out
deleted file mode 100644
index a44cae40db..0000000000
--- a/tests/qemu-iotests/100.out
+++ /dev/null
@@ -1,103 +0,0 @@
-QA output created by 100
-
-== Single request ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 4096/4096 bytes at offset 0
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 4096/4096 bytes at offset 0
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 4096
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== Sequential requests ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 12288/12288 bytes at offset 0
-12 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 4096/4096 bytes at offset 0
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 4096
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 8192
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== Superset overlapping requests ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 6144/6144 bytes at offset 0
-6 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 1024/1024 bytes at offset 0
-1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 1024/1024 bytes at offset 3072
-1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 4096
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== Subset overlapping requests ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 6144/6144 bytes at offset 1024
-6 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 1024/1024 bytes at offset 0
-1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 1024/1024 bytes at offset 3072
-1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 4096
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== Head overlapping requests ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 6144/6144 bytes at offset 0
-6 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 2048/2048 bytes at offset 2048
-2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 4096
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== Tail overlapping requests ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 6144/6144 bytes at offset 2048
-6 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 2048/2048 bytes at offset 0
-2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 4096
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== Disjoint requests ==
-Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=134217728
-wrote 73728/73728 bytes at offset 0
-72 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-wrote 8192/8192 bytes at offset 0
-8 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-
-== verify pattern ==
-read 4096/4096 bytes at offset 0
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 61440/61440 bytes at offset 4096
-60 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 65536
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-read 4096/4096 bytes at offset 69632
-4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
-*** done
diff --git a/tests/qemu-iotests/109 b/tests/qemu-iotests/109
index f980b0c9e5..adf98892f0 100755
--- a/tests/qemu-iotests/109
+++ b/tests/qemu-iotests/109
@@ -104,8 +104,6 @@ for sample_img in empty.bochs iotest-dirtylog-10G-4M.vhdx parallels-v1 \
     $QEMU_IO -c 'read -P 0 0 64k' "$TEST_IMG" | _filter_qemu_io
 
     run_qemu "$TEST_IMG" "$TEST_IMG.src" "'format': 'raw'," "BLOCK_JOB_READY"
-    # qemu-img compare can't handle unaligned file sizes
-    $QEMU_IMG resize -f raw "$TEST_IMG.src" +0
     $QEMU_IMG compare -f raw -F raw "$TEST_IMG" "$TEST_IMG.src"
 done
 
diff --git a/tests/qemu-iotests/109.out b/tests/qemu-iotests/109.out
index 38bc073a37..7c797ed31c 100644
--- a/tests/qemu-iotests/109.out
+++ b/tests/qemu-iotests/109.out
@@ -143,7 +143,6 @@ read 65536/65536 bytes at offset 0
 {"return": {}}
 {"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.
 
@@ -164,7 +163,6 @@ read 65536/65536 bytes at offset 0
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 31457280, "offset": 31457280, "speed": 0, "type": "mirror"}}
 {"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 31457280, "offset": 31457280, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
-Image resized.
 Warning: Image size mismatch!
 Images are identical.
 
@@ -185,7 +183,6 @@ read 65536/65536 bytes at offset 0
 {"return": {}}
 {"timestamp": {"seconds":  TIMESTAMP, "microseconds":  TIMESTAMP}, "event": "BLOCK_JOB_READY", "data": {"device": "src", "len": 327680, "offset": 327680, "speed": 0, "type": "mirror"}}
 {"return": [{"io-status": "ok", "device": "src", "busy": false, "len": 327680, "offset": 327680, "paused": false, "speed": 0, "ready": true, "type": "mirror"}]}
-Image resized.
 Warning: Image size mismatch!
 Images are identical.
 
@@ -206,7 +203,6 @@ read 65536/65536 bytes at offset 0
 {"return": {}}
 {"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.
 
diff --git a/tests/qemu-iotests/136 b/tests/qemu-iotests/136
index e8c6937fc9..635b977552 100644
--- a/tests/qemu-iotests/136
+++ b/tests/qemu-iotests/136
@@ -226,18 +226,11 @@ sector = "%d"
 
         highest_offset = wr_ops * wr_size
 
-        # Two types of invalid operations: unaligned length and unaligned offset
-        for i in range(invalid_rd_ops / 2):
-            ops.append("aio_read 0 511")
+        for i in range(invalid_rd_ops):
+            ops.append("aio_read -i 0 512")
 
-        for i in range(invalid_rd_ops / 2, invalid_rd_ops):
-            ops.append("aio_read 13 512")
-
-        for i in range(invalid_wr_ops / 2):
-            ops.append("aio_write 0 511")
-
-        for i in range(invalid_wr_ops / 2, invalid_wr_ops):
-            ops.append("aio_write 13 512")
+        for i in range(invalid_wr_ops):
+            ops.append("aio_write -i 0 512")
 
         for i in range(failed_rd_ops):
             ops.append("aio_read %d 512" % bad_offset)
@@ -248,14 +241,6 @@ sector = "%d"
         if failed_wr_ops > 0:
             highest_offset = max(highest_offset, bad_offset + 512)
 
-        for i in range(wr_merged):
-            first = i * wr_size * 2
-            second = first + wr_size
-            ops.append("multiwrite %d %d ; %d %d" %
-                       (first, wr_size, second, wr_size))
-
-        highest_offset = max(highest_offset, wr_merged * wr_size * 2)
-
         # Now perform all operations
         for op in ops:
             self.vm.hmp_qemu_io("drive0", op)
@@ -309,19 +294,15 @@ sector = "%d"
     def test_flush(self):
         self.do_test_stats(flush_ops = 8)
 
-    def test_merged(self):
-        for i in range(5):
-            self.do_test_stats(wr_merged = i * 3)
-
     def test_all(self):
         # rd_size, rd_ops, wr_size, wr_ops, flush_ops
         # invalid_rd_ops,  invalid_wr_ops,
         # failed_rd_ops,   failed_wr_ops
         # wr_merged
-        test_values = [[512,    1, 512,   1, 1, 4, 7, 5, 2, 1],
-                       [65536,  1, 2048, 12, 7, 7, 5, 2, 5, 5],
-                       [32768,  9, 8192,  1, 4, 3, 2, 4, 6, 4],
-                       [16384, 11, 3584, 16, 9, 8, 6, 7, 3, 4]]
+        test_values = [[512,    1, 512,   1, 1, 4, 7, 5, 2, 0],
+                       [65536,  1, 2048, 12, 7, 7, 5, 2, 5, 0],
+                       [32768,  9, 8192,  1, 4, 3, 2, 4, 6, 0],
+                       [16384, 11, 3584, 16, 9, 8, 6, 7, 3, 0]]
         for i in test_values:
             self.do_test_stats(*i)
 
diff --git a/tests/qemu-iotests/136.out b/tests/qemu-iotests/136.out
index 0a5e9583a4..cfa5c0d0e6 100644
--- a/tests/qemu-iotests/136.out
+++ b/tests/qemu-iotests/136.out
@@ -1,5 +1,5 @@
-........................................
+...................................
 ----------------------------------------------------------------------
-Ran 40 tests
+Ran 35 tests
 
 OK
diff --git a/tests/qemu-iotests/154 b/tests/qemu-iotests/154
new file mode 100755
index 0000000000..23f1b3ab16
--- /dev/null
+++ b/tests/qemu-iotests/154
@@ -0,0 +1,265 @@
+#!/bin/bash
+#
+# qcow2 specific bdrv_write_zeroes tests with backing files (complements 034)
+#
+# 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/>.
+#
+
+# creator
+owner=kwolf@redhat.com
+
+seq=`basename $0`
+echo "QA output created by $seq"
+
+here=`pwd`
+status=1	# failure is the default!
+
+_cleanup()
+{
+	_cleanup_test_img
+}
+trap "_cleanup; exit \$status" 0 1 2 3 15
+
+# get standard environment, filters and checks
+. ./common.rc
+. ./common.filter
+
+_supported_fmt qcow2
+_supported_proto file
+_supported_os Linux
+
+CLUSTER_SIZE=4k
+size=128M
+
+echo
+echo == backing file contains zeros ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Make sure that the whole cluster is allocated even for partial write_zeroes
+# when the backing file contains zeros
+
+# X = non-zero data sector in backing file
+# - = sector unallocated in whole backing chain
+# 0 = sector touched by write_zeroes request
+
+# 1. Tail unaligned:    00 00 -- --
+# 2. Head unaligned:    -- -- 00 00
+# 3. Both unaligned:    -- 00 00 --
+# 4. Both, 2 clusters:  -- -- -- 00 | 00 -- -- --
+
+$QEMU_IO -c "write -z 0 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z 10k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z 17k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "write -z 27k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == backing file contains non-zero data before write_zeroes ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Single cluster; non-zero data at the cluster start
+# ... | XX -- 00 -- | ...
+$QEMU_IO -c "write -P 0x11 32k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 34k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 32k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 33k 3k" "$TEST_IMG" | _filter_qemu_io
+
+# Single cluster; non-zero data exists, but not at the cluster start
+# ... | -- XX 00 -- | ...
+$QEMU_IO -c "write -P 0x11 65k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 66k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 65k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 64k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 66k 2k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == backing file contains non-zero data after write_zeroes ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Single cluster; non-zero data directly after request
+# ... | -- 00 XX -- | ...
+$QEMU_IO -c "write -P 0x11 34k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 33k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 32k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 34k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 35k 1k" "$TEST_IMG" | _filter_qemu_io
+
+# Single cluster; non-zero data exists, but not directly after request
+# ... | -- 00 -- XX | ...
+$QEMU_IO -c "write -P 0x11 43k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 41k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 43k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 40k 3k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning two clusters, non-zero before request ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Two clusters; non-zero data before request:
+# 1. At cluster start:          32k: XX -- -- 00 | 00 -- -- --
+# 2. Between unallocated space: 48k: -- XX -- 00 | 00 -- -- --
+# 3. Directly before request:   64k: -- -- XX 00 | 00 -- -- --
+
+$QEMU_IO -c "write -P 0x11 32k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 35k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 32k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 33k 7k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IO -c "write -P 0x11 49k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 51k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 48k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 49k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 50k 6k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IO -c "write -P 0x11 66k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 67k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 64k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 66k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 67k 5k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning two clusters, non-zero after request ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Two clusters; non-zero data after request:
+# 1. Directly after request:    32k: -- -- -- 00 | 00 XX -- --
+# 2. Between unallocated space: 48k: -- -- -- 00 | 00 -- XX --
+# 3. At cluster end:            64k: -- -- -- 00 | 00 -- -- XX
+
+$QEMU_IO -c "write -P 0x11 37k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 35k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 32k 5k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 37k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 38k 2k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IO -c "write -P 0x11 54k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 51k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 48k 6k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 54k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 55k 1k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IO -c "write -P 0x11 71k 1k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 67k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 64k 7k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 71k 1k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning two clusters, partially overwriting backing file ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Backing file: -- -- XX XX | XX XX -- --
+# Active layer: -- -- XX 00 | 00 XX -- --
+
+$QEMU_IO -c "write -P 0x11 2k 4k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 3k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 0k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 2k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 3k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 5k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 6k 2k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning multiple clusters, non-zero in first cluster ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Backing file: 64k: XX XX -- -- | -- -- -- -- | -- -- -- --
+# Active layer: 64k: XX XX 00 00 | 00 00 00 00 | 00 -- -- --
+
+$QEMU_IO -c "write -P 0x11 64k 2k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 64k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 66k 10k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning multiple clusters, non-zero in intermediate cluster ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Backing file: 64k: -- -- -- -- | -- XX XX -- | -- -- -- --
+# Active layer: 64k: -- -- 00 00 | 00 00 00 00 | 00 -- -- --
+
+$QEMU_IO -c "write -P 0x11 69k 2k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 64k 12k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning multiple clusters, non-zero in final cluster ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Backing file: 64k: -- -- -- -- | -- -- -- -- | -- -- XX XX
+# Active layer: 64k: -- -- 00 00 | 00 00 00 00 | 00 -- XX XX
+
+$QEMU_IO -c "write -P 0x11 74k 2k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 64k 10k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 74k 2k" "$TEST_IMG" | _filter_qemu_io
+
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+
+echo
+echo == spanning multiple clusters, partially overwriting backing file ==
+
+CLUSTER_SIZE=512 TEST_IMG="$TEST_IMG.base" _make_test_img $size
+_make_test_img -b "$TEST_IMG.base"
+
+# Backing file: 64k: -- XX XX XX | XX XX XX XX | XX XX XX --
+# Active layer: 64k: -- XX 00 00 | 00 00 00 00 | 00 XX XX --
+
+$QEMU_IO -c "write -P 0x11 65k 10k" "$TEST_IMG.base" | _filter_qemu_io
+$QEMU_IO -c "write -z 66k 7k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 64k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 65k 1k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 66k 7k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0x11 73k 2k" "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c "read -P 0 75k 1k" "$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
+status=0
diff --git a/tests/qemu-iotests/154.out b/tests/qemu-iotests/154.out
new file mode 100644
index 0000000000..8946b734ac
--- /dev/null
+++ b/tests/qemu-iotests/154.out
@@ -0,0 +1,242 @@
+QA output created by 154
+
+== backing file contains zeros ==
+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
+wrote 2048/2048 bytes at offset 0
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 10240
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 17408
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 27648
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+[{ "start": 0, "length": 4096, "depth": 0, "zero": true, "data": false},
+{ "start": 4096, "length": 4096, "depth": 1, "zero": true, "data": false},
+{ "start": 8192, "length": 4096, "depth": 0, "zero": true, "data": false},
+{ "start": 12288, "length": 4096, "depth": 1, "zero": true, "data": false},
+{ "start": 16384, "length": 4096, "depth": 0, "zero": true, "data": false},
+{ "start": 20480, "length": 4096, "depth": 1, "zero": true, "data": false},
+{ "start": 24576, "length": 8192, "depth": 0, "zero": true, "data": false},
+{ "start": 32768, "length": 134184960, "depth": 1, "zero": true, "data": false}]
+
+== backing file contains non-zero data before write_zeroes ==
+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
+wrote 1024/1024 bytes at offset 32768
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 34816
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 32768
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 3072/3072 bytes at offset 33792
+3 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 66560
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 67584
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 66560
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 65536
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 36864, "length": 28672, "depth": 1, "zero": true, "data": false},
+{ "start": 65536, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 69632, "length": 134148096, "depth": 1, "zero": true, "data": false}]
+
+== backing file contains non-zero data after write_zeroes ==
+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
+wrote 1024/1024 bytes at offset 34816
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 33792
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 32768
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 34816
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 35840
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 44032
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 41984
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 44032
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 36864, "length": 4096, "depth": 1, "zero": true, "data": false},
+{ "start": 40960, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 45056, "length": 134172672, "depth": 1, "zero": true, "data": false}]
+
+== spanning two clusters, non-zero before request ==
+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
+wrote 1024/1024 bytes at offset 32768
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 35840
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 32768
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 7168/7168 bytes at offset 33792
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 50176
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 52224
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 49152
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 50176
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 6144/6144 bytes at offset 51200
+6 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 67584
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 68608
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 65536
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 67584
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 8192, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 40960, "length": 8192, "depth": 1, "zero": true, "data": false},
+{ "start": 49152, "length": 8192, "depth": 0, "zero": false, "data": true, "offset": 28672},
+{ "start": 57344, "length": 8192, "depth": 1, "zero": true, "data": false},
+{ "start": 65536, "length": 8192, "depth": 0, "zero": false, "data": true, "offset": 36864},
+{ "start": 73728, "length": 134144000, "depth": 1, "zero": true, "data": false}]
+
+== spanning two clusters, non-zero after request ==
+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
+wrote 1024/1024 bytes at offset 37888
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 35840
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 5120/5120 bytes at offset 32768
+5 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 37888
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 38912
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 55296
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 52224
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 6144/6144 bytes at offset 49152
+6 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 55296
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 56320
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 1024/1024 bytes at offset 72704
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 68608
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 7168/7168 bytes at offset 65536
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 8192, "depth": 0, "zero": false, "data": true, "offset": 20480},
+{ "start": 40960, "length": 8192, "depth": 1, "zero": true, "data": false},
+{ "start": 49152, "length": 8192, "depth": 0, "zero": false, "data": true, "offset": 28672},
+{ "start": 57344, "length": 8192, "depth": 1, "zero": true, "data": false},
+{ "start": 65536, "length": 8192, "depth": 0, "zero": false, "data": true, "offset": 36864},
+{ "start": 73728, "length": 134144000, "depth": 1, "zero": true, "data": false}]
+
+== spanning two clusters, partially overwriting backing file ==
+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
+wrote 4096/4096 bytes at offset 2048
+4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 2048/2048 bytes at offset 3072
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 0
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 2048
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 3072
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 8192, "length": 134209536, "depth": 1, "zero": true, "data": false}]
+
+== spanning multiple clusters, non-zero in first cluster ==
+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
+wrote 2048/2048 bytes at offset 65536
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 7168/7168 bytes at offset 67584
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 65536
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 69632, "length": 8192, "depth": 0, "zero": true, "data": false},
+{ "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
+
+== spanning multiple clusters, non-zero in intermediate cluster ==
+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
+wrote 2048/2048 bytes at offset 70656
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 7168/7168 bytes at offset 67584
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 12288/12288 bytes at offset 65536
+12 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": 12288, "depth": 0, "zero": true, "data": false},
+{ "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
+
+== spanning multiple clusters, non-zero in final cluster ==
+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
+wrote 2048/2048 bytes at offset 75776
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 7168/7168 bytes at offset 67584
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 10240/10240 bytes at offset 65536
+10 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
+
+== spanning multiple clusters, partially overwriting backing file ==
+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
+wrote 10240/10240 bytes at offset 66560
+10 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 7168/7168 bytes at offset 67584
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 65536
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 1024/1024 bytes at offset 66560
+1 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 7168/7168 bytes at offset 67584
+7 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 2048/2048 bytes at offset 74752
+2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+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": 69632, "length": 4096, "depth": 0, "zero": true, "data": false},
+{ "start": 73728, "length": 4096, "depth": 0, "zero": false, "data": true, "offset": 24576},
+{ "start": 77824, "length": 134139904, "depth": 1, "zero": true, "data": false}]
+*** done
diff --git a/tests/qemu-iotests/group b/tests/qemu-iotests/group
index 822953b6fa..ab1d76efdf 100644
--- a/tests/qemu-iotests/group
+++ b/tests/qemu-iotests/group
@@ -106,7 +106,7 @@
 097 rw auto backing
 098 rw auto backing quick
 099 rw auto quick
-100 rw auto quick
+# 100 was removed, do not reuse
 101 rw auto quick
 102 rw auto quick
 103 rw auto quick
@@ -153,3 +153,4 @@
 149 rw auto sudo
 150 rw auto quick
 152 rw auto quick
+154 rw auto backing quick
diff --git a/tests/test-throttle.c b/tests/test-throttle.c
index 744a524368..5ec966c8a4 100644
--- a/tests/test-throttle.c
+++ b/tests/test-throttle.c
@@ -20,6 +20,7 @@
 #include "qemu/throttle.h"
 #include "qemu/error-report.h"
 #include "block/throttle-groups.h"
+#include "sysemu/block-backend.h"
 
 static AioContext     *ctx;
 static LeakyBucket    bkt;
@@ -574,27 +575,32 @@ static void test_accounting(void)
 static void test_groups(void)
 {
     ThrottleConfig cfg1, cfg2;
-    BlockDriverState *bdrv1, *bdrv2, *bdrv3;
+    BlockBackend *blk1, *blk2, *blk3;
+    BlockBackendPublic *blkp1, *blkp2, *blkp3;
 
-    bdrv1 = bdrv_new();
-    bdrv2 = bdrv_new();
-    bdrv3 = bdrv_new();
+    blk1 = blk_new_with_bs(&error_abort);
+    blk2 = blk_new_with_bs(&error_abort);
+    blk3 = blk_new_with_bs(&error_abort);
 
-    g_assert(bdrv1->throttle_state == NULL);
-    g_assert(bdrv2->throttle_state == NULL);
-    g_assert(bdrv3->throttle_state == NULL);
+    blkp1 = blk_get_public(blk1);
+    blkp2 = blk_get_public(blk2);
+    blkp3 = blk_get_public(blk3);
 
-    throttle_group_register_bs(bdrv1, "bar");
-    throttle_group_register_bs(bdrv2, "foo");
-    throttle_group_register_bs(bdrv3, "bar");
+    g_assert(blkp1->throttle_state == NULL);
+    g_assert(blkp2->throttle_state == NULL);
+    g_assert(blkp3->throttle_state == NULL);
 
-    g_assert(bdrv1->throttle_state != NULL);
-    g_assert(bdrv2->throttle_state != NULL);
-    g_assert(bdrv3->throttle_state != NULL);
+    throttle_group_register_blk(blk1, "bar");
+    throttle_group_register_blk(blk2, "foo");
+    throttle_group_register_blk(blk3, "bar");
 
-    g_assert(!strcmp(throttle_group_get_name(bdrv1), "bar"));
-    g_assert(!strcmp(throttle_group_get_name(bdrv2), "foo"));
-    g_assert(bdrv1->throttle_state == bdrv3->throttle_state);
+    g_assert(blkp1->throttle_state != NULL);
+    g_assert(blkp2->throttle_state != NULL);
+    g_assert(blkp3->throttle_state != NULL);
+
+    g_assert(!strcmp(throttle_group_get_name(blk1), "bar"));
+    g_assert(!strcmp(throttle_group_get_name(blk2), "foo"));
+    g_assert(blkp1->throttle_state == blkp3->throttle_state);
 
     /* Setting the config of a group member affects the whole group */
     throttle_config_init(&cfg1);
@@ -602,29 +608,29 @@ static void test_groups(void)
     cfg1.buckets[THROTTLE_BPS_WRITE].avg = 285000;
     cfg1.buckets[THROTTLE_OPS_READ].avg  = 20000;
     cfg1.buckets[THROTTLE_OPS_WRITE].avg = 12000;
-    throttle_group_config(bdrv1, &cfg1);
+    throttle_group_config(blk1, &cfg1);
 
-    throttle_group_get_config(bdrv1, &cfg1);
-    throttle_group_get_config(bdrv3, &cfg2);
+    throttle_group_get_config(blk1, &cfg1);
+    throttle_group_get_config(blk3, &cfg2);
     g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
 
     cfg2.buckets[THROTTLE_BPS_READ].avg  = 4547;
     cfg2.buckets[THROTTLE_BPS_WRITE].avg = 1349;
     cfg2.buckets[THROTTLE_OPS_READ].avg  = 123;
     cfg2.buckets[THROTTLE_OPS_WRITE].avg = 86;
-    throttle_group_config(bdrv3, &cfg1);
+    throttle_group_config(blk3, &cfg1);
 
-    throttle_group_get_config(bdrv1, &cfg1);
-    throttle_group_get_config(bdrv3, &cfg2);
+    throttle_group_get_config(blk1, &cfg1);
+    throttle_group_get_config(blk3, &cfg2);
     g_assert(!memcmp(&cfg1, &cfg2, sizeof(cfg1)));
 
-    throttle_group_unregister_bs(bdrv1);
-    throttle_group_unregister_bs(bdrv2);
-    throttle_group_unregister_bs(bdrv3);
+    throttle_group_unregister_blk(blk1);
+    throttle_group_unregister_blk(blk2);
+    throttle_group_unregister_blk(blk3);
 
-    g_assert(bdrv1->throttle_state == NULL);
-    g_assert(bdrv2->throttle_state == NULL);
-    g_assert(bdrv3->throttle_state == NULL);
+    g_assert(blkp1->throttle_state == NULL);
+    g_assert(blkp2->throttle_state == NULL);
+    g_assert(blkp3->throttle_state == NULL);
 }
 
 int main(int argc, char **argv)