From mboxrd@z Thu Jan  1 00:00:00 1970
From: Steven Whitehouse <swhiteho@redhat.com>
Date: Wed, 18 Jul 2012 17:16:51 +0100
Subject: [Cluster-devel] [GFS2 PATCH] - kernel panic with small gfs2
 filesystems - 1 RG
In-Reply-To: <9d2529a5-926d-4920-b0bc-0d77a4964f64@zmail12.collab.prod.int.phx2.redhat.com>
References: <9d2529a5-926d-4920-b0bc-0d77a4964f64@zmail12.collab.prod.int.phx2.redhat.com>
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Hi,

Now in the -nmw tree. Thanks,

Steve.

On Wed, 2012-07-18 at 11:56 -0400, Abhijith Das wrote:
> In the unlikely setup where there's only one resource group in the gfs2 filesystem, gfs2_rgrpd_get_next() returns a NULL rgd that is not dealt with properly, causing a kernel NULL ptr dereference. This patch fixes this issue.
> 
> This bug was reported in rhel6: https://bugzilla.redhat.com/show_bug.cgi?id=838638
> 
> Signed-off-by: Abhi Das <adas@redhat.com>
> 
> 
> diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
> index e53d0a1..fb70792 100644
> --- a/fs/gfs2/rgrp.c
> +++ b/fs/gfs2/rgrp.c
> @@ -1276,6 +1276,7 @@ int gfs2_inplace_reserve(struct gfs2_inode *ip, u32 requested)
>  			/* fall through */
>  		case GLR_TRYFAILED:
>  			rgd = gfs2_rgrpd_get_next(rgd);
> +			rgd = rgd ? : begin; /* if NULL, wrap */
>  			if (rgd != begin) /* If we didn't wrap */
>  				break;
>  
>