Re: [PATCH 2/2] DDF: handle fake RAIDs with changing subarray UUIDs

[NeilBrown <neilb@suse.de>]

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On Mon,  9 Sep 2013 20:40:14 +0200 mwilck@arcor.de wrote:

> Some fake RAID BIOSes (in particular, LSI ones) change the
> VD GUID at every boot. These GUIDs are not suitable for
> identifying an array. Luckily the header GUID appears to
> remain constant.
> 
> We construct a pseudo-UUID from the header GUID and those
> properties of the subarray that we expect to remain constant.
> This is only array name and index; all else might change e.g.
> during grow.
> 
> Don't do this for all non-MD arrays, only for those known
> to use varying volume GUIDs.
> 
> This patch obsoletes my previous patch "DDF: new algorithm
> for subarray UUID"
> 
> Signed-off-by: Martin Wilck <mwilck@arcor.de>

Thanks.  Applied.

NeilBrown


> ---
>  super-ddf.c |   55 ++++++++++++++++++++++++++++++++++++++++++++++++++-----
>  1 files changed, 50 insertions(+), 5 deletions(-)
> 
> diff --git a/super-ddf.c b/super-ddf.c
> index 72a8351..19d8494 100644
> --- a/super-ddf.c
> +++ b/super-ddf.c
> @@ -1583,6 +1583,7 @@ static void brief_examine_subarrays_ddf(struct supertype *st, int verbose)
>  			continue;
>  		memcpy(vcl.conf.guid, ve->guid, DDF_GUID_LEN);
>  		ddf->currentconf =&vcl;
> +		vcl.vcnum = i;
>  		uuid_from_super_ddf(st, info.uuid);
>  		fname_from_uuid(st, &info, nbuf1, ':');
>  		memcpy(namebuf, ve->name, sizeof(ve->name));
> @@ -1682,6 +1683,52 @@ static void detail_super_ddf(struct supertype *st, char *homehost)
>  	 */
>  }
>  
> +static const char *vendors_with_variable_volume_UUID[] = {
> +	"LSI      ",
> +};
> +
> +static int volume_id_is_reliable(const struct ddf_super *ddf)
> +{
> +	int n = sizeof(vendors_with_variable_volume_UUID) / 
> +		sizeof(vendors_with_variable_volume_UUID[0]);
> +	int i;
> +	for (i = 0; i < n; i++)
> +		if (!memcmp(ddf->controller.guid,
> +			vendors_with_variable_volume_UUID[i], 8))
> +		return 0;
> +	return 1;
> +}
> +
> +static void uuid_of_ddf_subarray(const struct ddf_super *ddf,
> +				 unsigned int vcnum, int uuid[4])
> +{
> +	char buf[DDF_GUID_LEN+18], sha[20], *p;
> +	struct sha1_ctx ctx;
> +	if (volume_id_is_reliable(ddf)) {
> +		uuid_from_ddf_guid(ddf->virt->entries[vcnum].guid, uuid);
> +		return;
> +	}
> +	/*
> +	 * Some fake RAID BIOSes (in particular, LSI ones) change the
> +	 * VD GUID at every boot. These GUIDs are not suitable for
> +	 * identifying an array. Luckily the header GUID appears to
> +	 * remain constant.
> +	 * We construct a pseudo-UUID from the header GUID and those
> +	 * properties of the subarray that we expect to remain constant.
> +	 */
> +	memset(buf, 0, sizeof(buf));
> +	p = buf;
> +	memcpy(p, ddf->anchor.guid, DDF_GUID_LEN);
> +	p += DDF_GUID_LEN;
> +	memcpy(p, ddf->virt->entries[vcnum].name, 16);
> +	p += 16;
> +	*((__u16 *) p) = vcnum;
> +	sha1_init_ctx(&ctx);
> +	sha1_process_bytes(buf, sizeof(buf), &ctx);
> +	sha1_finish_ctx(&ctx, sha);
> +	memcpy(uuid, sha, 4*4);
> +}
> +
>  static void brief_detail_super_ddf(struct supertype *st)
>  {
>  	struct mdinfo info;
> @@ -1693,7 +1740,7 @@ static void brief_detail_super_ddf(struct supertype *st)
>  	else if (vcnum == DDF_NOTFOUND)
>  		return;
>  	else
> -		uuid_from_ddf_guid(ddf->virt->entries[vcnum].guid, info.uuid);
> +		uuid_of_ddf_subarray(ddf, vcnum, info.uuid);
>  	fname_from_uuid(st, &info, nbuf,':');
>  	printf(" UUID=%s", nbuf + 5);
>  }
> @@ -1836,13 +1883,11 @@ static void uuid_from_super_ddf(struct supertype *st, int uuid[4])
>  	 */
>  	struct ddf_super *ddf = st->sb;
>  	struct vcl *vcl = ddf->currentconf;
> -	char *guid;
>  
>  	if (vcl)
> -		guid = vcl->conf.guid;
> +		uuid_of_ddf_subarray(ddf, vcl->vcnum, uuid);
>  	else
> -		guid = ddf->anchor.guid;
> -	uuid_from_ddf_guid(guid, uuid);
> +		uuid_from_ddf_guid(ddf->anchor.guid, uuid);
>  }
>  
>  static void getinfo_super_ddf_bvd(struct supertype *st, struct mdinfo *info, char *map);


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