linux-ext4 - Re: [PATCH 13/54] e2fsck: Verify inode bitmap checksum

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Date:	Mon, 12 Mar 2012 15:30:10 -0700
From:	"Darrick J. Wong" <djwong@...ibm.com>
To:	"Ted Ts'o" <tytso@....edu>
Cc:	Andreas Dilger <adilger.kernel@...ger.ca>,
	Sunil Mushran <sunil.mushran@...cle.com>,
	Amir Goldstein <amir73il@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Mingming Cao <cmm@...ibm.com>,
	Joel Becker <jlbec@...lplan.org>, linux-ext4@...r.kernel.org,
	Coly Li <colyli@...il.com>
Subject: Re: [PATCH 13/54] e2fsck: Verify inode bitmap checksum

On Mon, Mar 12, 2012 at 02:25:37PM -0700, Darrick J. Wong wrote:
> On Sat, Mar 10, 2012 at 09:11:50PM -0500, Ted Ts'o wrote:
> > On Sat, Mar 10, 2012 at 12:46:57AM -0500, Ted Ts'o wrote:
> > > 
> > > This patch just looks wrong.  RO_COMPAT_GDT_CSUM is the old feature,
> > > and doesn't imply that there will be a checksum in the inode bitmap
> > > block.  Shouldn't this be RO_COMPAT_METADATA_CSUM?
> > 
> > Correction; the big problem here is that check_inode_bitmap_checksum()
> > (and in the next e2fsck page, check_block_bitmap_checksum()) are are
> > doing their thing without actually checking for
> > RO_COMPAT_METADATA_CSUM).  These code paths shouldn't be getting
> > activated at all for non-METADATA_CSUM file systems.  But they are.
> 
> You're right, the function could be optimized to exit early if metadata_csum
> isn't set.  The bitmap verify function won't flag errors when metadata_csum is
> unset, at least, but I suppose it is unecessary looping and IO.
> 
> --D
> 
> > (And the check_block_bitmap_checksum() function is using
> > EXT2_BLOCKS_PER_GROUP where it needs to use EXT2_CLUSTERS_PER_GROUP or
> > it will end up corrupting memory which will cause the bigalloc-related
> > test f_dup_ba blow up.  But again, this code path shouldn't have been
> > getting activated in the first place.)

As for this bit -- I should have paid closer attention when bigalloc went in.
I'll send out a corrected patch.

--D
> > 
> > 					- Ted
> > --
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