linux-kernel - Re: [PATCH v2] libata: Don't trust current capacity values in identify words 57-58

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Date:	Mon, 02 Mar 2009 18:53:14 -0600
From:	Robert Hancock <hancockrwd@...il.com>
To:	unlisted-recipients:; (no To-header on input)
CC:	Sergei Shtylyov <sshtylyov@...mvista.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	ide <linux-ide@...r.kernel.org>, Jeff Garzik <jeff@...zik.org>,
	Mark Lord <liml@....ca>,
	Hanno Böck <hanno@...eck.de>
Subject: Re: [PATCH v2] libata: Don't trust current capacity values in identify
   words 57-58

Robert Hancock wrote:
> Hanno Böck reported a problem where an old Conner CP30254 240MB hard drive
> was reported as 1.1TB in capacity by libata:
> 
> http://lkml.org/lkml/2009/2/13/134
> 
> This was caused by libata trusting the drive's reported current capacity in 
> sectors in identify words 57 and 58 if the drive does not support LBA and the
> current CHS translation values appear valid. Unfortunately it seems older
> ATA specs were vague about what this field should contain and a number of drives
> used values with wrong byte order or that were totally bogus. There's no
> unique information that it conveys and so we can just calculate the number
> of sectors from the reported current CHS values.
> 
> While we're at it, clean up this function to use named constants for the
> identify word values.
> 
> Signed-off-by: Robert Hancock <hancockrwd@...il.com>

Jeff, any thoughts on this one? I would suggest it's -upstream material 
(for .30)..

> 
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 9fbf059..33b5549 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -1322,14 +1322,16 @@ static u64 ata_id_n_sectors(const u16 *id)
>  {
>  	if (ata_id_has_lba(id)) {
>  		if (ata_id_has_lba48(id))
> -			return ata_id_u64(id, 100);
> +			return ata_id_u64(id, ATA_ID_LBA_CAPACITY_2);
>  		else
> -			return ata_id_u32(id, 60);
> +			return ata_id_u32(id, ATA_ID_LBA_CAPACITY);
>  	} else {
>  		if (ata_id_current_chs_valid(id))
> -			return ata_id_u32(id, 57);
> +			return id[ATA_ID_CUR_CYLS] * id[ATA_ID_CUR_HEADS] *
> +			       id[ATA_ID_CUR_SECTORS];
>  		else
> -			return id[1] * id[3] * id[6];
> +			return id[ATA_ID_CYLS] * id[ATA_ID_HEADS] *
> +			       id[ATA_ID_SECTORS];
>  	}
>  }
>  
> --
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