Re: [Nbd] Block layer - meaning of REQ_FUA on not write requests
- To: Alex Bligh <alex@...872...>
- Cc: nbd-general@lists.sourceforge.net, "linux-kernel@...25..." <linux-kernel@...25...>
- Subject: Re: [Nbd] Block layer - meaning of REQ_FUA on not write requests
- From: Jeff Moyer <jmoyer@...696...>
- Date: Fri, 01 Apr 2016 12:06:09 -0400
- Message-id: <x49fuv5uxe6.fsf@...2355...>
- In-reply-to: <FA28BBF6-1D91-4F9B-99DF-5C46F27E2D44@...872...> (Alex Bligh's message of "Fri, 1 Apr 2016 16:27:35 +0100")
- References: <FA28BBF6-1D91-4F9B-99DF-5C46F27E2D44@...872...>
Alex Bligh <alex@...872...> writes:
> I am trying to clean up the documentation of the NBD protocol. NBD's
> support for Force Unit Access (FUA) was modelled on the linux kernel
> block layer. When I added support a few years ago, I omitted to find
> out exactly what types of request it applies to. Obviously it applies
> to write requests, but how about others (e.g. read)?
Any request with REQ_FUA set will be treated as a flush by the block
layer. As such, we do not expect reads to have this bit set.
Cheers,
Jeff
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