Re: [Qemu-devel] [PATCH RFC 2/2] tests/virtio-blk: add test for WRITE_ZEROES command

[Thomas Huth <thuth@redhat.com>]

On 2019-01-25 07:01, Thomas Huth wrote:
> On 2019-01-24 18:23, Stefano Garzarella wrote:
>> If the WRITE_ZEROES feature is enabled, we check this
>> command in the test_basic().
>>
>> Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
>> ---
>>  tests/virtio-blk-test.c | 63 +++++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 63 insertions(+)
>>
>> diff --git a/tests/virtio-blk-test.c b/tests/virtio-blk-test.c
>> index 04c608764b..8cabbcb85a 100644
>> --- a/tests/virtio-blk-test.c
>> +++ b/tests/virtio-blk-test.c
>> @@ -231,6 +231,69 @@ static void test_basic(QVirtioDevice *dev, QGuestAllocator *alloc,
>>  
>>      guest_free(alloc, req_addr);
>>  
>> +    if (features & (1u << VIRTIO_BLK_F_WRITE_ZEROES)) {
>> +        struct virtio_blk_discard_write_zeroes *dwz_hdr;
>> +        void *expected;
>> +
>> +        /*
>> +         * WRITE_ZEROES request on the same sector of previous test where
>> +         * we wrote "TEST".
>> +         */
>> +        req.type = VIRTIO_BLK_T_WRITE_ZEROES;
>> +        req.data = g_malloc0(512);
> 
> Wouldn't it be more interesting to do a memset(req.data, 0xaa, 512) or
> something similar here, to see whether zeroes or 0xaa is written?

Ah, never mind, I thought req.data would be a sector buffer here, but
looking at the lines below, it apparently is something different.

Why do you allocate 512 bytes here? I'd rather expect
g_malloc0(sizeof(struct virtio_blk_discard_write_zeroes)) here. ... and
then you could also use a local "struct virtio_blk_discard_write_zeroes
dwz_hdr" variable instead of a pointer, and drop the g_malloc0() completely?

>> +        dwz_hdr = (struct virtio_blk_discard_write_zeroes *)req.data;
>> +        dwz_hdr->sector = 0;
>> +        dwz_hdr->num_sectors = 1;
>> +        dwz_hdr->flags = 0;
>> +
>> +        req_addr = virtio_blk_request(alloc, dev, &req, 512);
>> +
>> +        g_free(req.data);
>> +
>> +        free_head = qvirtqueue_add(vq, req_addr, 16, false, true);
>> +        qvirtqueue_add(vq, req_addr + 16, 512, false, true);
>> +        qvirtqueue_add(vq, req_addr + 528, 1, true, false);
>> +
>> +        qvirtqueue_kick(dev, vq, free_head);
>> +
>> +        qvirtio_wait_used_elem(dev, vq, free_head, NULL,
>> +                               QVIRTIO_BLK_TIMEOUT_US);
>> +        status = readb(req_addr + 528);
>> +        g_assert_cmpint(status, ==, 0);
>> +
>> +        guest_free(alloc, req_addr);
>> +
>> +        /* Read request to check if the sector contains all zeroes */
>> +        req.type = VIRTIO_BLK_T_IN;
>> +        req.ioprio = 1;
>> +        req.sector = 0;
>> +        req.data = g_malloc0(512);
>> +
>> +        req_addr = virtio_blk_request(alloc, dev, &req, 512);
>> +
>> +        g_free(req.data);
>> +
>> +        free_head = qvirtqueue_add(vq, req_addr, 16, false, true);
>> +        qvirtqueue_add(vq, req_addr + 16, 512, true, true);
>> +        qvirtqueue_add(vq, req_addr + 528, 1, true, false);
>> +
>> +        qvirtqueue_kick(dev, vq, free_head);
>> +
>> +        qvirtio_wait_used_elem(dev, vq, free_head, NULL,
>> +                               QVIRTIO_BLK_TIMEOUT_US);
>> +        status = readb(req_addr + 528);
>> +        g_assert_cmpint(status, ==, 0);
>> +
>> +        data = g_malloc(512);
>> +        expected = g_malloc0(512);
>> +        memread(req_addr + 16, data, 512);
>> +        g_assert_cmpmem(data, 512, expected, 512);
>> +        g_free(expected);
>> +        g_free(data);
>> +
>> +        guest_free(alloc, req_addr);
>> +    }
>> +
>>      if (features & (1u << VIRTIO_F_ANY_LAYOUT)) {
>>          /* Write and read with 2 descriptor layout */
>>          /* Write request */
>>
> 
>