diff options
| author | Anton Nefedov <anton.nefedov@virtuozzo.com> | 2019-05-16 17:27:49 +0300 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2019-05-28 20:30:55 +0200 |
| commit | c8bb23cbdbe32f5c326365e0a82e1b0e68cdcd8a (patch) | |
| tree | 7169d73a97be9364e328610798c54f8af16b6fa4 /tests/qemu-iotests/060 | |
| parent | 330c72957196e0ae382abcaa97ebf4eb9bc8574f (diff) | |
qcow2: skip writing zero buffers to empty COW areas
If COW areas of the newly allocated clusters are zeroes on the backing
image, efficient bdrv_write_zeroes(flags=BDRV_REQ_NO_FALLBACK) can be
used on the whole cluster instead of writing explicit zero buffers later
in perform_cow().
iotest 060:
write to the discarded cluster does not trigger COW anymore.
Use a backing image instead.
Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Message-id: 20190516142749.81019-2-anton.nefedov@virtuozzo.com
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Alberto Garcia <berto@igalia.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'tests/qemu-iotests/060')
| -rwxr-xr-x | tests/qemu-iotests/060 | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/tests/qemu-iotests/060 b/tests/qemu-iotests/060 index 89e911400c..b91d8321bb 100755 --- a/tests/qemu-iotests/060 +++ b/tests/qemu-iotests/060 @@ -150,10 +150,15 @@ $QEMU_IO -c "$OPEN_RO" -c "read -P 1 0 512" | _filter_qemu_io echo echo "=== Testing overlap while COW is in flight ===" echo +BACKING_IMG=$TEST_IMG.base +TEST_IMG=$BACKING_IMG _make_test_img 1G + +$QEMU_IO -c 'write 0k 64k' "$BACKING_IMG" | _filter_qemu_io + # compat=0.10 is required in order to make the following discard actually # unallocate the sector rather than make it a zero sector - we want COW, after # all. -IMGOPTS='compat=0.10' _make_test_img 1G +IMGOPTS='compat=0.10' _make_test_img -b "$BACKING_IMG" 1G # Write two clusters, the second one enforces creation of an L2 table after # the first data cluster. $QEMU_IO -c 'write 0k 64k' -c 'write 512M 64k' "$TEST_IMG" | _filter_qemu_io |