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Re: [Qemu-block] [PATCH v2 14/20] nbd: Support BDRV_REQ_FUA

From: Max Reitz
Subject: Re: [Qemu-block] [PATCH v2 14/20] nbd: Support BDRV_REQ_FUA
Date: Tue, 29 Mar 2016 15:44:34 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.0

On 29.03.2016 15:30, Kevin Wolf wrote:
> The NBD server already used to send a FUA flag when the writethrough
> mode was set. This code was a remnant from the times where protocol
> drivers actually had to implement writethrough modes. Since nowadays the
> block layer sends flushes in writethrough mode and non-root nodes are
> always writeback, this was mostly dead code - only mostly because if NBD
> was configured to be used without a format, we sent _both_ FUA and an
> explicit flush afterwards, which makes the code not technically dead,
> but useless overhead.
> This patch changes the code so that the block layer's FUA flag is
> recognised and translated into a NBD FUA flag. The additional flush is
> avoided now.
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  block/nbd-client.c | 13 +++++++------
>  block/nbd-client.h |  2 +-
>  block/nbd.c        | 27 ++++++++++++++++++++++++++-
>  3 files changed, 34 insertions(+), 8 deletions(-)

Reviewed-by: Max Reitz <address@hidden>

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