gfs2: Protect gl->gl_object by spin lock

Put all remaining accesses to gl->gl_object under the
gl->gl_lockref.lock spinlock to prevent races.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Bob Peterson <rpeterso@redhat.com>

fs/gfs2/incore.h

@@ -857,5 +857,7 @@ static inline void gfs2_sbstats_inc(const struct gfs2_glock *gl, int which)
 	preempt_enable();
 }
 
+extern struct gfs2_rgrpd *gfs2_glock2rgrp(struct gfs2_glock *gl);
+
 #endif /* __INCORE_DOT_H__ */