Re: [PATCH] blk-mq: don't insert FUA request with data into scheduler queue

Tim Walker
2021-11-19T17:57:08Z

On Friday, November 19, 2021 at 11:56:55 AM Christoph Hellwig wrote:

>
>Direct reply without a quote a the formatting of your mail is completely
>messed up.

Sorry about that - hopefully this is better.

>We don't treat a FUA a a flush. If the device supports
>FUA is is just passed on.

Does this mean a FUA request for a device that natively supports FUA is eventually "passed on" to the scheduler?
Or does it go straight to dispatch?

>But if the device does not support FUA it
>is sequenced into doing the write first and then a flush before returning
>completion to the caller to guarantee the FUA semantics. Because of that
>the command needs special treatment and be handed over to the flush
>state machine, but it won't do anything interesting if FUA is actually
>natively supported.
>

Yes, I can see why this flush logic is needed for devices that don't support FUA. Thanks.