Failed writes to block devices don't report an error

[Chris Johns]

On 23/06/10 5:32 PM, Sebastian Huber wrote:
>> I also think we should think about adding error stat reporting at the
>> device layer in a standard manner. A little like network drivers have so
>> application can monitor the devices and manage any issues it sees as
>> important. I see this as a device issue not a a bdbuf thing. You open
>> the device node and perform the error stat ioctl call to get the stats.
> [...]
>
> We should also consider to add statistics to bdbuf to measure errors and
> performance.
>

Yes bdbuf stats would be good. They should be only those it has and not 
ones returned from the devices attached. This avoids the bdbuf 
allocating space for all possible devices so per device errors can be 
maintained.

Chris