linux-kernel - Re: GPT detection regression in efi.c from commit 27a7c64

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Date:	Fri, 13 Sep 2013 11:29:32 -0700
From:	Davidlohr Bueso <davidlohr@...com>
To:	Karel Zak <kzak@...hat.com>
Cc:	Matt Porter <matt.porter@...aro.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	torvalds@...ux-foundation.org
Subject: Re: GPT detection regression in efi.c from commit 27a7c64

On Fri, 2013-09-13 at 20:17 +0200, Karel Zak wrote:
> On Fri, Sep 13, 2013 at 02:09:55PM -0400, Matt Porter wrote:
> > >Come to think of it, we do have a long existing workaround: the
> > >force_gpt option. Setting it will bypass any MBR checking
> > >(is_pmbr_valid(), specifically).
> > 
> > Yes, that's what I used at first after seeing what the problem was. But then
> > I opted to fix my PMBR.
> > 
> > I felt like it was a regression since it required a new option passed on the
> > cmdline.
> 
>  Yep, it is *regression* and I guess Davidlohr is going to fix it asap :-)

I was doing a git revert, but what would you guys think of keeping the
check but making it more flexible? Instead of enforcing the minimum,
just make sure that the size_in_lba is either the whole disk or 2 TiB,
that should take care of Matt's issue.

diff --git a/block/partitions/efi.c b/block/partitions/efi.c
index 1a5ec9a..df2fca1 100644
--- a/block/partitions/efi.c
+++ b/block/partitions/efi.c
@@ -220,8 +220,8 @@ check_hybrid:
         * Hybrid MBRs do not necessarily comply with this.
         */
        if (ret == GPT_MBR_PROTECTIVE) {
-               if (le32_to_cpu(mbr->partition_record[part].size_in_lba) !=
-                   min((uint32_t) total_sectors - 1, 0xFFFFFFFF))
+               if (le32_to_cpu(mbr->partition_record[part].size_in_lba) != (uint32_t) total_sectors - 1 ||
+                   le32_to_cpu(mbr->partition_record[part].size_in_lba) != 0xFFFFFFFF)
                        ret = 0;
        }
 done:

Karel, I guess any changes that we do here should apply to fdisk :)

Thanks,
Davidlohr

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