[parted-devel] [PATCH] [RFC] Do not automatically update GPT label in interactive mode.

[Joel Granados]

Hi Peter.

I agree with you on this.  This patch is part of the set of patches I will propose for parted for version 1.8.9.

thx for the report.

----- "Petr Uzel" <petr.uzel at suse.cz> wrote:

> Hi all,
> 
> 
> Previously, when parted was invoked in interactive mode on disk with
> GPT
> label and the backup GPT was not in the last sector of the disk,
> parted
> fixed this automatically. This behavior might be undesirable in the
> following situation:
> 
> dm-raid on top of block device. The dm-raid is partitioned with GPT.
> If
> the dm-raid starts on the first block of underlying device (AFAIK this
> is
> the case with FastTrack controllers) and the user runs parted on the
> dm-raid, it will identify the physical device as being partitioned
> with
> GPT and see the backup GPT table not to be in the last sector of the
> physical device and thus move it to this location (which may lead to
> destruction of dm-raid metadata in case they are located at the end
> of
> physical device).
> 
> This patch modifies parted's behavior to ignore fixing of backup GPT
> position by default.
> ---
>  libparted/labels/gpt.c |   23 +++++++++++++----------
>  1 files changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/libparted/labels/gpt.c b/libparted/labels/gpt.c
> index 13d2e88..2e765b4 100644
> --- a/libparted/labels/gpt.c
> +++ b/libparted/labels/gpt.c
> @@ -831,21 +831,24 @@ gpt_read (PedDisk * disk)
>  			char* zeros = ped_malloc (pth_get_size (disk->dev));
>  
>  #ifndef DISCOVER_ONLY
> -			if (ped_exception_throw (
> +			switch (ped_exception_throw (
>  				PED_EXCEPTION_ERROR,
> -				PED_EXCEPTION_FIX | PED_EXCEPTION_CANCEL,
> +				PED_EXCEPTION_FIX | PED_EXCEPTION_CANCEL | PED_EXCEPTION_IGNORE,
>  		_("The backup GPT table is not at the end of the disk, as it "
>  		  "should be.  This might mean that another operating system "
>  		  "believes the disk is smaller.  Fix, by moving the backup "
> -		  "to the end (and removing the old backup)?"))
> -					== PED_EXCEPTION_CANCEL)
> -				goto error_free_gpt;
> +		  "to the end (and removing the old backup)?"))) {
> +				case PED_EXCEPTION_CANCEL:
> +					goto error_free_gpt;
> +				case PED_EXCEPTION_FIX:
> +					write_back = 1;
> +					memset (zeros, 0, disk->dev->sector_size);
> +					ped_device_write (disk->dev, zeros,
> +							  PED_LE64_TO_CPU (gpt->AlternateLBA),
> +							  1);
> +					break;
> +			}
>  
> -			write_back = 1;
> -			memset (zeros, 0, disk->dev->sector_size);
> -			ped_device_write (disk->dev, zeros,
> -					  PED_LE64_TO_CPU (gpt->AlternateLBA),
> -					  1);
>  #endif /* !DISCOVER_ONLY */
>  		}
>  	} else { /* primary GPT *not* ok */
> -- 
> 1.6.0.2
> 
> 
> -- 
> Best regards / s pozdravem
> 
> Petr Uzel, Packages maintainer
> ---------------------------------------------------------------------
> SUSE LINUX, s.r.o.                          e-mail: puzel at suse.cz
> Lihovarská 1060/12                          tel: +420 284 028 964
> 190 00 Prague 9                             fax: +420 284 028 951
> Czech Republic                              http://www.suse.cz
> 
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-- 
Joel Andres Granados
Red Hat / Brno Czech Republic