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

[Petr Uzel]

Hi,

On Fri, Feb 13, 2009 at 08:15:54AM -0500, Joel Granados wrote:
> 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.

Nice to hear that. But please note that I have not tested the patch
much as I do not have access to the affected fakeraid controller.
However, synthetic tests with linear DM seemed to work fine.

> 
> thx for the report.

thx for the reply :)

> 
> ----- "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
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