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Re: [Qemu-devel] [PATCH] luks: Allow share-rw=on
From: |
Daniel P . Berrangé |
Subject: |
Re: [Qemu-devel] [PATCH] luks: Allow share-rw=on |
Date: |
Tue, 14 Aug 2018 08:27:49 +0100 |
User-agent: |
Mutt/1.10.1 (2018-07-13) |
On Tue, Aug 14, 2018 at 03:25:51PM +0800, Fam Zheng wrote:
> Format drivers such as qcow2 don't allow sharing the same image between
> two QEMU instances in order to prevent image corruptions, because of
> metadata cache. LUKS driver don't modify metadata except for when
> creating image, so it is safe to relax the permission. This makes
> share-rw=on property work on virtual devices.
>
> Suggested-by: Daniel P. Berrangé <address@hidden>
> Signed-off-by: Fam Zheng <address@hidden>
> ---
> block/crypto.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/block/crypto.c b/block/crypto.c
> index 146d81c90a..33ee01bebd 100644
> --- a/block/crypto.c
> +++ b/block/crypto.c
> @@ -627,7 +627,9 @@ BlockDriver bdrv_crypto_luks = {
> .bdrv_probe = block_crypto_probe_luks,
> .bdrv_open = block_crypto_open_luks,
> .bdrv_close = block_crypto_close,
> - .bdrv_child_perm = bdrv_format_default_perms,
> + /* This driver doesn't modify LUKS metadata except when creating image.
> + * Allow share-rw=on as a special case. */
> + .bdrv_child_perm = bdrv_filter_default_perms,
> .bdrv_co_create = block_crypto_co_create_luks,
> .bdrv_co_create_opts = block_crypto_co_create_opts_luks,
> .bdrv_co_truncate = block_crypto_co_truncate,
Reviewed-by: Daniel P. Berrangé <address@hidden>
Regards,
Daniel
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