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Re: [Qemu-devel] [PATCH] nbd/server: introduce NBD_CMD_CACHE
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] nbd/server: introduce NBD_CMD_CACHE |
Date: |
Wed, 18 Apr 2018 11:37:58 -0500 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 |
On 04/13/2018 09:31 AM, Vladimir Sementsov-Ogievskiy wrote:
> Handle nbd CACHE command. Just do read, without sending read data back.
> Cache mechanism should be done by exported node driver chain.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <address@hidden>
> ---
> include/block/nbd.h | 3 ++-
> nbd/server.c | 10 ++++++----
> 2 files changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/include/block/nbd.h b/include/block/nbd.h
> index fcdcd54502..b4793d0a29 100644
> --- a/include/block/nbd.h
> +++ b/include/block/nbd.h
> @@ -135,6 +135,7 @@ typedef struct NBDExtent {
> #define NBD_FLAG_SEND_TRIM (1 << 5) /* Send TRIM (discard) */
> #define NBD_FLAG_SEND_WRITE_ZEROES (1 << 6) /* Send WRITE_ZEROES */
> #define NBD_FLAG_SEND_DF (1 << 7) /* Send DF (Do not Fragment) */
> +#define NBD_FLAG_SEND_CACHE (1 << 8) /* Send CACHE (prefetch) */
Hmm, this flag is not documented in the upstream NBD protocol yet; are
we sure it matches the xNBD implementation? We'll want at least a
documentation patch proposed for the NBD list before taking this.
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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