linux-kernel - Re: [PATCH v2 2/3] genhd, efi: add efi partition metadata to hd

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Message-ID: <20100804090049.GH5464@nb.net.home>
Date:	Wed, 4 Aug 2010 11:00:49 +0200
From:	Karel Zak <kzak@...hat.com>
To:	Will Drewry <wad@...omium.org>
Cc:	linux-kernel@...r.kernel.org, Kay Sievers <kay.sievers@...y.org>,
	Jens Axboe <axboe@...nel.dk>, Tejun Heo <tj@...nel.org>,
	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Joe Perches <joe@...ches.com>, Jan Blunck <jblunck@...e.de>,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [PATCH v2 2/3] genhd, efi: add efi partition metadata to
	hd_structs

On Tue, Aug 03, 2010 at 09:04:42PM -0500, Will Drewry wrote:
> This change extends the partition_meta_info structure to
> support EFI GPT-specific metadata and ensures that data
> is copied in on partition scanning.

Why do want to store GPT-specific data (efi_guid_t) to
partition_meta_info? I think it would be better to use label and uuid
in a generic format (e.g. string or u8 uuid[16]) -- then you don't
have to use things like union, disklabel specific code to compare
uuids, etc.  IMHO your current code is too complicated.

> +		info = alloc_part_info(NULL);
> +		if (!info) {
> +			printk(KERN_WARNING
> +			       "unable to allocate memory for part->info\n");
> +			continue;
> +		}
> +		info->format = PARTITION_META_INFO_FORMAT_EFI;
> +		memcpy(info->efi.uuid.b, ptes[i].unique_partition_guid.b,
> +			sizeof(info->efi.uuid.b));
> +		memcpy(info->efi.type.b, ptes[i].partition_type_guid.b,
> +			sizeof(info->efi.type.b));

why do you need to partition type?

> +		memcpy(info->efi.label, ptes[i].partition_name,
> +			sizeof(info->efi.label));

the partition name is in UTF8LE, is it correct to use it in raw
format?

> +		state->parts[i + 1].info = info;
>  	}
>  	kfree(ptes);
>  	kfree(gpt);
> diff --git a/include/linux/genhd.h b/include/linux/genhd.h
> index 7b6644a..beb98e3 100644
> --- a/include/linux/genhd.h
> +++ b/include/linux/genhd.h
> @@ -91,11 +91,25 @@ struct disk_stats {
>  enum partition_meta_info_format_t {
>  	/* Partition info format */
>  	PARTITION_META_INFO_FORMAT_NONE = 0,
> +	PARTITION_META_INFO_FORMAT_EFI,
> +	/* Place additional formats here. */
> +	PARTITION_META_INFO_FORMAT_MAX,
>  };
>  
> +#ifdef CONFIG_EFI_PARTITION
> +#include <linux/efi.h>
> +#endif
> +
>  struct partition_meta_info {
>  	enum partition_meta_info_format_t format;
>  	union {
> +#ifdef CONFIG_EFI_PARTITION
> +		struct {
> +			efi_guid_t uuid;
> +			efi_guid_t type;
> +			efi_char16_t label[72 / sizeof(efi_char16_t)];
> +		} efi;
> +#endif
>  	};
>  };
>  
> -- 
> 1.7.0.4
> 

-- 
 Karel Zak  <kzak@...hat.com>
 http://karelzak.blogspot.com
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