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 <mreitz@redhat.com>
Message-id: 20180501165750.19242-3-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
This commit is contained in:
Max Reitz 2018-05-01 18:57:50 +02:00
parent 351c8efff9
commit 0682854f89
2 changed files with 60 additions and 0 deletions

View file

@ -76,6 +76,48 @@ $QEMU_IMG convert -O $IMGFMT -c -B "$TEST_IMG".base "$TEST_IMG" "$TEST_IMG".orig
$QEMU_IO -c "read -P 0 0 3M" "$TEST_IMG".orig 2>&1 | _filter_qemu_io | _filter_testdir
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

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@ -28,6 +28,24 @@ read 3145728/3145728 bytes at offset 0
read 3145728/3145728 bytes at offset 0
3 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
=== Converting to an overlay larger than its backing file ===
Formatting 'TEST_DIR/t.IMGFMT.base', fmt=IMGFMT size=268435456
Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=805306368 backing_file=TEST_DIR/t.IMGFMT.base
Offset Length File
wrote 1048576/1048576 bytes at offset 267386880
1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
wrote 1048576/1048576 bytes at offset 629145600
1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
Offset Length File
0xff00000 0x100000 TEST_DIR/t.IMGFMT.base
0x25800000 0x100000 TEST_DIR/t.IMGFMT.orig
read 1048576/1048576 bytes at offset 267386880
1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
read 1048576/1048576 bytes at offset 629145600
1 MiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec)
=== Concatenate multiple source images ===
Formatting 'TEST_DIR/t.IMGFMT.1', fmt=IMGFMT size=4194304