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Re: [Qemu-devel] [PATCH] block: implement the bdrv_reopen_prepare helper
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] block: implement the bdrv_reopen_prepare helper for LUKS driver |
Date: |
Thu, 18 Jan 2018 13:51:36 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.2 |
On 01/18/2018 04:31 AM, Daniel P. Berrange wrote:
> If the bdrv_reopen_prepare helper isn't provided, the qemu-img commit
> command fails to re-open the base layer after committing changes into
> it. Provide a no-op implementation for the LUKS driver, since there
> is not any custom work that needs doing to re-open it.
>
> Signed-off-by: Daniel P. Berrange <address@hidden>
> ---
> block/crypto.c | 7 +++++++
> 1 file changed, 7 insertions(+)
I'm hoping another block-layer expert chimes in, as I'm not quite sure
what the full reopen rules are; but the idea makes sense to me.
>
> diff --git a/block/crypto.c b/block/crypto.c
> index 60ddf8623e..bb9a8f5376 100644
> --- a/block/crypto.c
> +++ b/block/crypto.c
> @@ -382,6 +382,12 @@ static void block_crypto_close(BlockDriverState *bs)
> qcrypto_block_free(crypto->block);
> }
>
> +static int block_crypto_reopen_prepare(BDRVReopenState *state,
> + BlockReopenQueue *queue, Error **errp)
> +{
> + /* nothing needs checking */
Are we sure that even changes such as moving from read-only to
read-write need no checking?
> + return 0;
> +}
>
> /*
> * 1 MB bounce buffer gives good performance / memory tradeoff
> @@ -620,6 +626,7 @@ BlockDriver bdrv_crypto_luks = {
> .bdrv_truncate = block_crypto_truncate,
> .create_opts = &block_crypto_create_opts_luks,
>
> + .bdrv_reopen_prepare = block_crypto_reopen_prepare,
> .bdrv_refresh_limits = block_crypto_refresh_limits,
> .bdrv_co_preadv = block_crypto_co_preadv,
> .bdrv_co_pwritev = block_crypto_co_pwritev,
>
--
Eric Blake, Principal Software Engineer
Red Hat, Inc. +1-919-301-3266
Virtualization: qemu.org | libvirt.org
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