[GFS2] Fix memory allocation in glock.c

Change from GFP_KERNEL to GFP_NOFS as this was causing a
slow down when trying to push inodes from cache.
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/glock.c

@@ -769,7 +769,7 @@ static void handle_callback(struct gfs2_glock *gl, unsigned int state)
 	} else {
 		spin_unlock(&gl->gl_spin);
 
-		new_gh = gfs2_holder_get(gl, state, LM_FLAG_TRY, GFP_KERNEL);
+		new_gh = gfs2_holder_get(gl, state, LM_FLAG_TRY, GFP_NOFS);
 		if (!new_gh)
 			return;
 		set_bit(HIF_DEMOTE, &new_gh->gh_iflags);