linux-kernel - [PATCH 14/16] GFS2: kernel panic with small gfs2 filesystems

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Message-Id: <1343030466-3053-15-git-send-email-swhiteho@redhat.com>
Date:	Mon, 23 Jul 2012 09:01:04 +0100
From:	Steven Whitehouse <swhiteho@...hat.com>
To:	linux-kernel@...r.kernel.org, cluster-devel@...hat.com
Cc:	Abhijith Das <adas@...hat.com>,
	Steven Whitehouse <swhiteho@...hat.com>
Subject: [PATCH 14/16] GFS2: kernel panic with small gfs2 filesystems - 1 RG

From: Abhijith Das <adas@...hat.com>

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.

Signed-off-by: Abhi Das <adas@...hat.com>
Signed-off-by: Steven Whitehouse <swhiteho@...hat.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;
 
-- 
1.7.4

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