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From: tytso@mit.edu
To: Andreas Dilger <andreas.dilger@oracle.com>
Cc: Eric Sandeen <sandeen@redhat.com>,
	ext4 development <linux-ext4@vger.kernel.org>,
	Alessandro Polverini <alex@nibbles.it>,
	Christoph Biedl <bugzilla.kernel.bpeb@manchmal.in-ulm.de>
Subject: Re: [PATCH] resize: check s_log_groups_per_flex before accessing flex groups
Date: Sat, 3 Apr 2010 22:11:01 -0400	[thread overview]
Message-ID: <20100404021101.GD18524@thunk.org> (raw)
In-Reply-To: <96C33B08-CDC5-48B3-98C0-479F230E7F98@oracle.com>

On Sun, Mar 28, 2010 at 09:14:07AM -0600, Andreas Dilger wrote:
> On 2010-03-27, at 13:32, Eric Sandeen wrote:
> >#13549, Kernel oops while online resizing of an ext4 filesystem
> >
> >if groups_per_flex < 2, sbi->s_flex_groups[] doesn't get filled out,
> >and every other access to this first tests s_log_groups_per_flex;
> >same thing needs to happen in resize or we'll wander off into
> >a null pointer.
> 
> Does it even make sense to set INCOMPAT_FLEX_BG if we only have a
> single group per flexbg?  That is just a normal filesystem then.
> That would be a separate bug in mke2fs.

Yes, it does make sense to set flex_bg in this case; it allows the
group metadata to be stored outside of a blockgroup, which is helpful
to e2fsck in some cases when it needs to relocate an inode table and
there's no contiguous free space available in the block group.

	   	      	   	 	   - Ted

  parent reply	other threads:[~2010-04-04  2:11 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-27 19:32 [PATCH] resize: check s_log_groups_per_flex before accessing flex groups Eric Sandeen
2010-03-28 15:14 ` Andreas Dilger
2010-03-28 15:26   ` Eric Sandeen
2010-04-04  2:11   ` tytso [this message]
2010-04-04  2:17 ` tytso

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