[PATCH v2 06/11] iotests/290: add test case to check 'discard-no-unref' option behavior

[Andrey Drobyshev]

We basically fill 2 images with identical data and perform discard
operations with and without 'discard-no-unref' enabled.  Then we check
that images still read identically, that their disk usage is the same
(i.e. fallocate(FALLOC_FL_PUNCH_HOLE|FALLOC_FL_KEEP_SIZE) is called for
both) and that with the option enabled cluster is still marked as
allocated in "qemu-img map" output.  We also check that the option
doesn't work with qcow2 v2 images.

Signed-off-by: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>
---
 tests/qemu-iotests/290     | 34 ++++++++++++++++++++++++++++++++++
 tests/qemu-iotests/290.out | 28 ++++++++++++++++++++++++++++
 2 files changed, 62 insertions(+)

diff --git a/tests/qemu-iotests/290 b/tests/qemu-iotests/290
index 776b59de1b..4eb929d15f 100755
--- a/tests/qemu-iotests/290
+++ b/tests/qemu-iotests/290
@@ -92,6 +92,40 @@ for qcow2_compat in 0.10 1.1; do
     $QEMU_IMG map "$TEST_IMG" | _filter_testdir
 done
 
+echo
+echo "### Test 'qemu-io -c discard' with 'discard-no-unref' option enabled"
+echo
+
+echo "# Check that qcow2 v2 images don't support 'discard-no-unref' option"
+NOUNREF_IMG="$TEST_IMG.nounref"
+TEST_IMG="$NOUNREF_IMG" _make_test_img -o "compat=0.10" 128k
+# This should immediately fail with an error
+$QEMU_IO -c 'reopen -o discard-no-unref=on' "$NOUNREF_IMG" | _filter_qemu_io
+
+echo "# Create two compat=1.1 images and fill them with identical data"
+_make_test_img -o "compat=1.1" 128k
+TEST_IMG="$NOUNREF_IMG" _make_test_img -o "compat=1.1" 128k
+$QEMU_IO -c 'write -P 0xaa 0 128k' "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c 'write -P 0xaa 0 128k' "$NOUNREF_IMG" | _filter_qemu_io
+
+echo "# Enable 'discard-no-unref' in one of them, discard 2nd cluster in both"
+$QEMU_IO -c 'discard 64k 64k' "$TEST_IMG" | _filter_qemu_io
+$QEMU_IO -c 'reopen -o discard-no-unref=on' \
+         -c 'discard 64k 64k' "$NOUNREF_IMG" | _filter_qemu_io
+
+echo "# Compare disk usage of the 2 images"
+# Don't check the exact disk usage values but rather that they're equal
+echo "disk_usage(`basename $TEST_IMG`) - disk_usage(`basename $NOUNREF_IMG`)" \
+     "= $(( `disk_usage $TEST_IMG` - `disk_usage $NOUNREF_IMG`))"
+
+echo "# Check that images are still identical"
+$QEMU_IMG compare "$TEST_IMG" "$NOUNREF_IMG"
+
+echo "# Output of qemu-img map for the image with dropped reference"
+$QEMU_IMG map --output=json "$TEST_IMG" | _filter_qemu_img_map
+echo "# Output of qemu-img map for the image with kept reference"
+$QEMU_IMG map --output=json "$NOUNREF_IMG" | _filter_qemu_img_map
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/290.out b/tests/qemu-iotests/290.out
index 22b476594f..f790feae81 100644
--- a/tests/qemu-iotests/290.out
+++ b/tests/qemu-iotests/290.out
@@ -58,4 +58,32 @@ read 131072/131072 bytes at offset 0
 128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
 # Output of qemu-img map
 Offset          Length          Mapped to       File
+
+### Test 'qemu-io -c discard' with 'discard-no-unref' option enabled
+
+# Check that qcow2 v2 images don't support 'discard-no-unref' option
+Formatting 'TEST_DIR/t.IMGFMT.nounref', fmt=IMGFMT size=131072
+qemu-io: discard-no-unref is only supported since qcow2 version 3
+# Create two compat=1.1 images and fill them with identical data
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=131072
+Formatting 'TEST_DIR/t.IMGFMT.nounref', fmt=IMGFMT size=131072
+wrote 131072/131072 bytes at offset 0
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+wrote 131072/131072 bytes at offset 0
+128 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+# Enable 'discard-no-unref' in one of them, discard 2nd cluster in both
+discard 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+discard 65536/65536 bytes at offset 65536
+64 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
+# Compare disk usage of the 2 images
+disk_usage(t.qcow2) - disk_usage(t.qcow2.nounref) = 0
+# Check that images are still identical
+Images are identical.
+# Output of qemu-img map for the image with dropped reference
+[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": false, 
"data": true, "compressed": false, "offset": OFFSET},
+{ "start": 65536, "length": 65536, "depth": 0, "present": true, "zero": true, 
"data": false, "compressed": false}]
+# Output of qemu-img map for the image with kept reference
+[{ "start": 0, "length": 65536, "depth": 0, "present": true, "zero": false, 
"data": true, "compressed": false, "offset": OFFSET},
+{ "start": 65536, "length": 65536, "depth": 0, "present": true, "zero": true, 
"data": false, "compressed": false, "offset": OFFSET}]
 *** done
-- 
2.39.3