Without conv=notrunc, dd will automatically truncate the output file to the @seek value at least. We want to test post-EOF I/O, not truncate, so pass conv=notrunc.
(It does not make a difference in practice because we only seek to the EOF, so the truncate effectively does nothing, but this is still cleaner.) Signed-off-by: Hanna Czenczek <[email protected]> --- tests/qemu-iotests/308 | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/tests/qemu-iotests/308 b/tests/qemu-iotests/308 index 033d5cbe22..6ecb275555 100755 --- a/tests/qemu-iotests/308 +++ b/tests/qemu-iotests/308 @@ -296,7 +296,8 @@ orig_disk_usage=$(disk_usage "$TEST_IMG") # Should fail (exports are non-growable by default) # (Note that qemu-io can never write beyond the EOF, so we have to use # dd here) -dd if=/dev/zero of="$EXT_MP" bs=1 count=64k seek=$orig_len 2>&1 \ +dd if=/dev/zero of="$EXT_MP" bs=1 count=64k seek=$orig_len \ + conv=notrunc 2>&1 \ | _filter_testdir | _filter_imgfmt echo @@ -333,7 +334,7 @@ fuse_export_add \ 'node-protocol' # Now we should be able to write beyond the EOF -dd if=/dev/zero of="$EXT_MP" bs=1 count=64k seek=$new_len 2>&1 \ +dd if=/dev/zero of="$EXT_MP" bs=1 count=64k seek=$new_len conv=notrunc 2>&1 \ | _filter_testdir | _filter_imgfmt new_len=$(get_proto_len "$EXT_MP" "$TEST_IMG") -- 2.53.0
