Re: [PATCH] sg, bsg: mitigate read/write abuse, block uaccess in release

Jens Axboe
2018-06-18T16:23:53Z

On 6/18/18 10:16 AM, Al Viro wrote:
> On Mon, Jun 18, 2018 at 09:37:01AM -0600, Jens Axboe wrote:
>
>>> The folks responsible are no longer active in kernel development ***
>>> but as far as I know the async write(command), read(response) were
>>> added to bsg over 10 years ago as proof-of-concept and never properly
>>> worked in this async mode. The biggest design problem with it that I'm
>>
>> It was born with that mode, but I don't think anyone ever really used it.
>> So it might feasible to simply yank it. That said, just doing a prune
>> mode at ->release() time doesn't seem like such a hard task.
>
> "prune mode" being...?

Basically what Jann posted, not doing any copy-back of data. Need to
verify if the bio unmapping is handled correctly, as some of those
will also copy when the end_io handling is invoked.

--
Jens Axboe