From 0682854f899d03c78befce9f5aae4a7e37655d25 Mon Sep 17 00:00:00 2001 From: Max Reitz Date: Tue, 1 May 2018 18:57:50 +0200 Subject: iotests: Test post-backing convert target behavior This adds a test case to 122 for what happens when you convert to a target with a backing file that is shorter than the target, and the image format does not support efficient zero writes (as is the case with qcow2 v2). Signed-off-by: Max Reitz Message-id: 20180501165750.19242-3-mreitz@redhat.com Reviewed-by: Eric Blake Signed-off-by: Max Reitz --- tests/qemu-iotests/122 | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) (limited to 'tests/qemu-iotests/122') diff --git a/tests/qemu-iotests/122 b/tests/qemu-iotests/122 index 45b359c..d8c8ad7 100755 --- a/tests/qemu-iotests/122 +++ b/tests/qemu-iotests/122 @@ -77,6 +77,48 @@ $QEMU_IO -c "read -P 0 0 3M" "$TEST_IMG".orig 2>&1 | _filter_qemu_io | _filter_t echo +echo "=== Converting to an overlay larger than its backing file ===" +echo + +TEST_IMG="$TEST_IMG".base _make_test_img 256M +# Needs to be at least how much an L2 table covers +# (64 kB/entry * 64 kB / 8 B/entry = 512 MB) +# That way, qcow2 will yield at least two status request responses. +# With just a single response, it would always say "Allocated in the +# backing file", so the optimization qemu-img convert tries to do is +# done automatically. Once it has to be queried twice, however (and +# one of the queries is completely after the end of the backing file), +# the block layer will automatically add a ZERO flag that qemu-img +# convert used to follow up with a zero write to the target. +# We do not want such a zero write, however, because we are past the +# end of the backing file on the target as well, so we do not need to +# write anything there. +_make_test_img -b "$TEST_IMG".base 768M + +# Use compat=0.10 as the output so there is no zero cluster support +$QEMU_IMG convert -O $IMGFMT -B "$TEST_IMG".base -o compat=0.10 \ + "$TEST_IMG" "$TEST_IMG".orig +# See that nothing has been allocated past 64M +$QEMU_IMG map "$TEST_IMG".orig | _filter_qemu_img_map + +echo + +# Just before the end of the backing file +$QEMU_IO -c 'write -P 0x11 255M 1M' "$TEST_IMG".base 2>&1 | _filter_qemu_io +# Somewhere in the second L2 table +$QEMU_IO -c 'write -P 0x22 600M 1M' "$TEST_IMG" 2>&1 | _filter_qemu_io + +$QEMU_IMG convert -O $IMGFMT -B "$TEST_IMG".base -o compat=0.10 \ + "$TEST_IMG" "$TEST_IMG".orig + +$QEMU_IMG map "$TEST_IMG".orig | _filter_qemu_img_map +$QEMU_IO -c 'read -P 0x11 255M 1M' \ + -c 'read -P 0x22 600M 1M' \ + "$TEST_IMG".orig \ + | _filter_qemu_io + + +echo echo "=== Concatenate multiple source images ===" echo -- cgit v1.1