Re: [Qemu-devel] [PATCH] xen_disk: convert discard input to byte ranges

[Olaf Hering]

Am 18. November 2016 14:43:18 MEZ, schrieb Eric Blake <address@hidden>:
>On 11/18/2016 04:24 AM, Olaf Hering wrote:
>> The guest sends discard requests as u64 sector/count pairs, but the
>> block layer operates internally with s64/s32 pairs. The conversion
>> leads to IO errors in the guest, the discard request is not
>processed.
>
>Doesn't the block layer already split discard requests into 2^31 byte
>chunks?

How would it do that without valid input?  It was wrong before the sectors to 
bytes conversion, and now its even worse given that all the world fits into an 
int.

Remember that there is no API to let the guest know about the limitations of 
the host. 

Olaf