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Re: [Qemu-devel] [PATCH 3/5] block: Remove cache.writeback from blockdev
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH 3/5] block: Remove cache.writeback from blockdev-add |
Date: |
Mon, 14 Mar 2016 17:22:50 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
Am 14.03.2016 um 17:10 hat Eric Blake geschrieben:
> On 03/14/2016 09:44 AM, Kevin Wolf wrote:
> > The WCE bit is a frontend property and should not be part of the backend
> > configuration. This is especially important because the same BDS can be
> > used by different users with different WCE requirements.
> >
> > Signed-off-by: Kevin Wolf <address@hidden>
> > ---
> > qapi/block-core.json | 4 +---
> > 1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/qapi/block-core.json b/qapi/block-core.json
> > index 9bf1b22..e3617e2 100644
> > --- a/qapi/block-core.json
> > +++ b/qapi/block-core.json
> > @@ -1614,7 +1614,6 @@
> > #
> > # Includes cache-related options for block devices
> > #
> > -# @writeback: #optional enables writeback mode for any caches (default:
> > true)
> > # @direct: #optional enables use of O_DIRECT (bypass the host page
> > cache;
> > # default: false)
> > # @no-flush: #optional ignore any flush requests for the device
> > (default:
> > @@ -1623,8 +1622,7 @@
> > # Since: 1.7
> > ##
> > { 'struct': 'BlockdevCacheOptions',
> > - 'data': { '*writeback': 'bool',
> > - '*direct': 'bool',
> > + 'data': { '*direct': 'bool',
> > '*no-flush': 'bool' } }
>
> Observable through introspection. Not quite backwards-compatible, but
> at least clients can learn about it, and arguably clients shouldn't have
> been using it. I can accept it as a bug fix, even though it does risk
> breaking old clients that were trying to use it.
>
> If it helps, libvirt does not seem to have been using it.
I think we declared that blockdev-add is still experimental, so it
should be okay.
And I was actually pondering whether this struct even makes sense any
more or whether we should move 'direct' and 'no-flush' directly to the
parent struct.
Kevin
pgpMtYp_tYL31.pgp
Description: PGP signature
- [Qemu-devel] [PATCH 0/5] block: API changes for 2.6, Kevin Wolf, 2016/03/14
- [Qemu-devel] [PATCH 2/5] block: Remove dirty bitmaps from bdrv_move_feature_fields(), Kevin Wolf, 2016/03/14
- [Qemu-devel] [PATCH 1/5] block: Remove copy-on-read from bdrv_move_feature_fields(), Kevin Wolf, 2016/03/14
- [Qemu-devel] [PATCH 4/5] block: Make backing files always writeback, Kevin Wolf, 2016/03/14
- [Qemu-devel] [PATCH 3/5] block: Remove cache.writeback from blockdev-add, Kevin Wolf, 2016/03/14
- [Qemu-devel] [PATCH 5/5] block: Reject writethrough mode except at the root, Kevin Wolf, 2016/03/14
- Re: [Qemu-devel] [PATCH 0/5] block: API changes for 2.6, Kevin Wolf, 2016/03/18