GFS2: kernel panic with small gfs2 filesystems - 1 RG

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@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index e53d0a1c234f..fb7079263ea7 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;