[PULL,06/27] iotests/{024, 271}: add testcases for qemu-img rebase

diff --git a/tests/qemu-iotests/024 b/tests/qemu-iotests/024
index 98a7c8fd65..285f17e79f 100755
--- a/tests/qemu-iotests/024
+++ b/tests/qemu-iotests/024
@@ -257,6 +257,66 @@  $QEMU_IO "$OVERLAY" -c "read -P 0x00 $(( CLUSTER_SIZE * 4 )) $CLUSTER_SIZE" \
 
 echo
 
+# Check that rebase within the chain is working when
+# overlay cluster size > backings cluster size
+# (here overlay cluster size == 2 * backings cluster size)
+#
+# base_new <-- base_old <-- overlay
+#
+# Backing (new): -- -- -- -- -- --
+# Backing (old): -- 11 -- -- 22 --
+# Overlay:      |-- --|-- --|-- --|
+#
+# We should end up having 1st and 3rd cluster allocated, and their halves
+# being read as zeroes.
+
+echo
+echo "=== Test rebase with different cluster sizes ==="
+echo
+
+echo "Creating backing chain"
+echo
+
+TEST_IMG=$BASE_NEW _make_test_img $(( CLUSTER_SIZE * 6 ))
+TEST_IMG=$BASE_OLD _make_test_img -b "$BASE_NEW" -F $IMGFMT \
+    $(( CLUSTER_SIZE * 6 ))
+CLUSTER_SIZE=$(( CLUSTER_SIZE * 2 )) TEST_IMG=$OVERLAY \
+    _make_test_img -b "$BASE_OLD" -F $IMGFMT $(( CLUSTER_SIZE * 6 ))
+
+TEST_IMG=$OVERLAY _img_info
+
+echo
+echo "Fill backing files with data"
+echo
+
+$QEMU_IO "$BASE_OLD" -c "write -P 0x11 $CLUSTER_SIZE $CLUSTER_SIZE" \
+    -c "write -P 0x22 $(( CLUSTER_SIZE * 4 )) $CLUSTER_SIZE" \
+    | _filter_qemu_io
+
+echo
+echo "Rebase onto another image in the same chain"
+echo
+
+$QEMU_IMG rebase -b "$BASE_NEW" -F $IMGFMT "$OVERLAY"
+
+echo "Verify that data is read the same before and after rebase"
+echo
+
+$QEMU_IO "$OVERLAY" -c "read -P 0x00 0 $CLUSTER_SIZE" \
+    -c "read -P 0x11 $CLUSTER_SIZE $CLUSTER_SIZE" \
+    -c "read -P 0x00 $(( CLUSTER_SIZE * 2 )) $(( CLUSTER_SIZE * 2 ))" \
+    -c "read -P 0x22 $(( CLUSTER_SIZE * 4 )) $CLUSTER_SIZE" \
+    -c "read -P 0x00 $(( CLUSTER_SIZE * 5 )) $CLUSTER_SIZE" \
+    | _filter_qemu_io
+
+echo
+echo "Verify that untouched cluster remains unallocated"
+echo
+
+$QEMU_IMG map "$OVERLAY" | _filter_qemu_img_map
+
+echo
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/024.out b/tests/qemu-iotests/024.out
index 245fe8b1d1..e1e8eea863 100644
--- a/tests/qemu-iotests/024.out
+++ b/tests/qemu-iotests/024.out
@@ -201,4 +201,47 @@  read 262144/262144 bytes at offset 0
 read 65536/65536 bytes at offset 262144
 64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 
+
+=== Test rebase with different cluster sizes ===
+
+Creating backing chain
+
+Formatting 'TEST_DIR/subdir/t.IMGFMT.base_new', fmt=IMGFMT size=393216
+Formatting 'TEST_DIR/subdir/t.IMGFMT.base_old', fmt=IMGFMT size=393216 backing_file=TEST_DIR/subdir/t.IMGFMT.base_new backing_fmt=IMGFMT
+Formatting 'TEST_DIR/subdir/t.IMGFMT', fmt=IMGFMT size=393216 backing_file=TEST_DIR/subdir/t.IMGFMT.base_old backing_fmt=IMGFMT
+image: TEST_DIR/subdir/t.IMGFMT
+file format: IMGFMT
+virtual size: 384 KiB (393216 bytes)
+cluster_size: 131072
+backing file: TEST_DIR/subdir/t.IMGFMT.base_old
+backing file format: IMGFMT
+
+Fill backing files with data
+
+wrote 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 65536/65536 bytes at offset 262144
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+Rebase onto another image in the same chain
+
+Verify that data is read the same before and after rebase
+
+read 65536/65536 bytes at offset 0
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 131072/131072 bytes at offset 131072
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 65536/65536 bytes at offset 262144
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 65536/65536 bytes at offset 327680
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+Verify that untouched cluster remains unallocated
+
+Offset          Length          File
+0               0x20000         TEST_DIR/subdir/t.IMGFMT
+0x40000         0x20000         TEST_DIR/subdir/t.IMGFMT
+
 *** done
diff --git a/tests/qemu-iotests/271 b/tests/qemu-iotests/271
index c7c2cadda0..e243f57ba7 100755
--- a/tests/qemu-iotests/271
+++ b/tests/qemu-iotests/271
@@ -899,6 +899,72 @@  _concurrent_io     | $QEMU_IO | _filter_qemu_io | \
     sed -e 's/\(20480\|40960\)/OFFSET/'
 _concurrent_verify | $QEMU_IO | _filter_qemu_io
 
+############################################################
+############################################################
+############################################################
+
+echo
+echo "### Rebase of qcow2 images with subclusters ###"
+echo
+
+l2_offset=$((0x400000))
+
+# Check that rebase operation preserve holes between allocated subclusters
+# within one cluster (i.e. does not allocate extra space).  Check that the
+# data is preserved as well.
+#
+# Base (new backing): -- -- -- ... -- -- --
+# Mid (old backing):  -- 11 -- ... -- 22 --
+# Top:                -- -- -- ... -- -- --
+
+echo "### Preservation of unallocated holes after rebase ###"
+echo
+
+echo "# create backing chain"
+echo
+
+TEST_IMG="$TEST_IMG.base" _make_test_img -o cluster_size=1M,extended_l2=on 1M
+TEST_IMG="$TEST_IMG.mid" _make_test_img -o cluster_size=1M,extended_l2=on \
+    -b "$TEST_IMG.base" -F qcow2 1M
+TEST_IMG="$TEST_IMG.top" _make_test_img -o cluster_size=1M,extended_l2=on \
+    -b "$TEST_IMG.mid" -F qcow2 1M
+
+echo
+echo "# fill old backing with data (separate subclusters within cluster)"
+echo
+
+$QEMU_IO -c "write -P 0x11 32k 32k" \
+         -c "write -P 0x22 $(( 30 * 32 ))k 32k" \
+         "$TEST_IMG.mid" | _filter_qemu_io
+
+echo
+echo "# rebase topmost image onto the new backing"
+echo
+
+$QEMU_IMG rebase -b "$TEST_IMG.base" -F qcow2 "$TEST_IMG.top"
+
+echo "# verify that data is read the same before and after rebase"
+echo
+
+$QEMU_IO -c "read -P 0x00 0 32k" \
+         -c "read -P 0x11 32k 32k" \
+         -c "read -P 0x00 64k $(( 28 * 32 ))k" \
+         -c "read -P 0x22 $(( 30 * 32 ))k 32k" \
+         -c "read -P 0x00 $(( 31 * 32 ))k 32k" \
+         "$TEST_IMG.top" | _filter_qemu_io
+
+echo
+echo "# verify that only selected subclusters remain allocated"
+echo
+
+$QEMU_IMG map "$TEST_IMG.top" | _filter_testdir
+
+echo
+echo "# verify image bitmap"
+echo
+
+TEST_IMG="$TEST_IMG.top" alloc="1 30" zero="" _verify_l2_bitmap 0
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/271.out b/tests/qemu-iotests/271.out
index 5be780de76..c335a6c608 100644
--- a/tests/qemu-iotests/271.out
+++ b/tests/qemu-iotests/271.out
@@ -723,4 +723,46 @@  wrote 2048/2048 bytes at offset OFFSET
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 wrote 2048/2048 bytes at offset OFFSET
 2 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+### Rebase of qcow2 images with subclusters ###
+
+### Preservation of unallocated holes after rebase ###
+
+# create backing chain
+
+Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=1048576
+Formatting 'TEST_DIR/t.IMGFMT.mid', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT.base backing_fmt=IMGFMT
+Formatting 'TEST_DIR/t.IMGFMT.top', fmt=IMGFMT size=1048576 backing_file=TEST_DIR/t.IMGFMT.mid backing_fmt=IMGFMT
+
+# fill old backing with data (separate subclusters within cluster)
+
+wrote 32768/32768 bytes at offset 32768
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 32768/32768 bytes at offset 983040
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+# rebase topmost image onto the new backing
+
+# verify that data is read the same before and after rebase
+
+read 32768/32768 bytes at offset 0
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 32768/32768 bytes at offset 32768
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 917504/917504 bytes at offset 65536
+896 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 32768/32768 bytes at offset 983040
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+read 32768/32768 bytes at offset 1015808
+32 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+
+# verify that only selected subclusters remain allocated
+
+Offset          Length          Mapped to       File
+0x8000          0x8000          0x508000        TEST_DIR/t.qcow2.top
+0xf0000         0x8000          0x5f0000        TEST_DIR/t.qcow2.top
+
+# verify image bitmap
+
+L2 entry #0: 0x8000000000500000 0000000040000002
 *** done