Re: [PATCH] raid superblock sanity checking (validate_sb)

On Fri, Aug 16, 2002 at 10:03:05AM -0700, Cress, Andrew R wrote:

Neil,

The problem is due to several md kernel bugs that corrupt the superblock.
And, since my target environment is a raid1 root mirror, it's a bigger deal
to reboot to a removable and manually fix it from userspace with mdadm.  

With the corruption I encountered, the kernel would panic on autodetecting
the raid, since the superblock on disk got corrupted. Yes, the original
cause should be fixed, but IMHO, the kernel should never dereference a
bogus pointer because of corrupt data on the superblock. Spit out a big
fat warning, and maybe panic after that yes.

It's a can of worms, but you are right, the right approach is to fix all of
the locations where a blind increment or decrement of the values takes
place, which I guess are the same locations where I put the validate_sb
routine.  I'll drill down further to try to fix the root problems.

Andy

-----Original Message-----
From: Neil Brown [mailto:neilb@cse.unsw.edu.au] 
Sent: Thursday, August 15, 2002 9:43 PM
To: Cress, Andrew R
Cc: 'Troy Benjegerdes'; linux-raid@vger.kernel.org
Subject: Re: [PATCH] raid superblock sanity checking (validate_sb)

On Monday August 12, andrew.r.cress@intel.com wrote:

quoted

I've written a patch to help this problem.  [...]
Neil, 

You've seen a lot of these type problems corrected with mdadm.  Does this
cover most of the cases?

If there is a kernel bug that corrupts the superblock, then we should
fix the bug, not put in lots of validation to see if the bug has hit..

And if a superblock did get corrupted, then fixing it is a userspace
(mdadm) issue, not kernel.

Or maybe I'm not understanding what problem you are trying to solve.

NeilBrown

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