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Re: [Qemu-block] [PATCH v3 08/10] block: Allow changing 'discard' on reo
From: |
Alberto Garcia |
Subject: |
Re: [Qemu-block] [PATCH v3 08/10] block: Allow changing 'discard' on reopen |
Date: |
Wed, 19 Sep 2018 11:18:31 +0200 |
User-agent: |
Notmuch/0.18.2 (http://notmuchmail.org) Emacs/24.4.1 (i586-pc-linux-gnu) |
On Thu 06 Sep 2018 11:37:08 AM CEST, Alberto Garcia <address@hidden> wrote:
> 'discard' is one of the basic BlockdevOptions available for all
> drivers, but it's not handled by bdrv_reopen_prepare() so any attempt
> to change it results in an error:
>
> (qemu) qemu-io virtio0 "reopen -o discard=on"
> Cannot change the option 'discard'
>
> Since there's no reason why we shouldn't allow changing it and the
> implementation is simple let's just do it.
>
> Signed-off-by: Alberto Garcia <address@hidden>
A side effect of this change that I hadn't noticed when I sent this
patch: protocol nodes have the "discard" option set to "unmap" by
default (by bdrv_inherited_options()), and that sets the BDRV_O_UNMAP
flag.
However that flag is cleared during reopen even though the "discard"
option remains there. So thanks to this patch the flag correctly
reflects the value of the option after reopen.
Is it worth sending the patch again with an updated commit message that
explains this?
Berto
- [Qemu-block] [PATCH v3 00/10] Misc reopen-related patches, Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 05/10] block: Allow child references on reopen, Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 09/10] block: Allow changing 'detect-zeroes' on reopen, Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 02/10] file-posix: x-check-cache-dropped should default to false on reopen, Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 03/10] block: Remove child references from bs->{options, explicit_options}, Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 06/10] block: Forbid trying to change unsupported options during reopen, Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 04/10] block: Don't look for child references in append_open_options(), Alberto Garcia, 2018/09/06
- [Qemu-block] [PATCH v3 01/10] qemu-io: Fix writethrough check in reopen, Alberto Garcia, 2018/09/06