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[Qemu-devel] Re: [PATCH 2/3] block-nbd: fix use of protocols in backing
From: |
Kevin Wolf |
Subject: |
[Qemu-devel] Re: [PATCH 2/3] block-nbd: fix use of protocols in backing files and nbd probing |
Date: |
Thu, 16 Sep 2010 10:08:59 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.12) Gecko/20100907 Fedora/3.0.7-1.fc12 Thunderbird/3.0.7 |
Am 11.09.2010 16:04, schrieb Anthony Liguori:
> The use of protocols in backing_files is currently broken because of some
> checks for adjusting relative pathnames.
>
> Additionally, there's a spurious read when using an nbd protocol that can be
> quite destructive when using copy-on-read. Potentially, this can lead to
> probing an image file over top of NBD but this is completely wrong as NBD
> devices are not growable.
>
> Signed-off-by: Anthony Liguori <address@hidden>
> ---
> NB: this is absolutely not ideal. A more elegant suggestion would be
> appreciated. I don't think NBD cleanly fits the model of a protocol as it
> stands today.
>
> diff --git a/block.c b/block.c
> index cd2ee31..a32d5dd 100644
> --- a/block.c
> +++ b/block.c
> @@ -344,6 +344,12 @@ static int find_image_format(const char *filename,
> BlockDriver **pdrv)
> return ret;
> }
>
> + if (strcmp(bs->drv->protocol_name, "nbd") == 0) {
> + drv = bs->drv;
> + bdrv_delete(bs);
> + goto out;
> + }
Is nbd really the only protocol that behaves like this? I don't like
hardcoding driver names in generic block layer code.
Kevin
[Qemu-devel] [PATCH 3/3] disk: don't read from disk until the guest starts, Anthony Liguori, 2010/09/11