Re: [PATCH v2] block: make BlockConf.*_size properties 32-bit

[Eric Blake]

On 3/26/20 1:52 AM, Roman Kagan wrote:
> Devices (virtio-blk, scsi, etc.) and the block layer are happy to use
> 32-bit for logical_block_size, physical_block_size, and min_io_size.
> However, the properties in BlockConf are defined as uint16_t limiting
> the values to 32768.
>
> This appears unnecessary tight, and we've seen bigger block sizes handy
> at times.
>
> Make them 32 bit instead and lift the limitation up to 2 MiB which
> appears to be good enough for everybody.

and matches the current qemu limit for qcow2 cluster sizes

> As the values can now be fairly big and awkward to type, make the
> property setter accept common size suffixes (k, m).
>
> Signed-off-by: Roman Kagan <address@hidden>
> ---
> v1 -> v2:
> - cap the property at 2 MiB [Eric]
> - accept size suffixes

> +++ b/hw/core/qdev-properties.c
> @@ -14,6 +14,7 @@
>   #include "qapi/visitor.h"
>   #include "chardev/char.h"
>   #include "qemu/uuid.h"
> +#include "qemu/units.h"
>   
>   void qdev_prop_set_after_realize(DeviceState *dev, const char *name,
>                                     Error **errp)
> @@ -729,30 +730,39 @@ const PropertyInfo qdev_prop_pci_devfn = {
>   
>   /* --- blocksize --- */
>   
> +/* lower limit is sector size */
> +#define MIN_BLOCK_SIZE          512
> +#define MIN_BLOCK_SIZE_STR      "512 B"
> +/* upper limit is arbitrary, 2 MiB looks sufficient */
> +#define MAX_BLOCK_SIZE          (2 * MiB)
> +#define MAX_BLOCK_SIZE_STR      "2 MiB"

For this comment, I might add that it matches our limit for qcow2 
cluster size.

Reviewed-by: Eric Blake <address@hidden>

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3226
Virtualization:  qemu.org | libvirt.org