[GFS2] Allocate gfs2_rgrpd from slab memory

This patch moves the gfs2_rgrpd structure to its own slab
memory.  This makes it easier to control and monitor, and
yields less memory fragmentation.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>
diff --git a/fs/gfs2/rgrp.c b/fs/gfs2/rgrp.c
index 7b9d6f1..dc7e83e 100644
--- a/fs/gfs2/rgrp.c
+++ b/fs/gfs2/rgrp.c
@@ -353,7 +353,7 @@
 		}
 
 		kfree(rgd->rd_bits);
-		kfree(rgd);
+		kmem_cache_free(gfs2_rgrpd_cachep, rgd);
 	}
 }
 
@@ -516,7 +516,7 @@
 		return error;
 	}
 
-	rgd = kzalloc(sizeof(struct gfs2_rgrpd), GFP_NOFS);
+	rgd = kmem_cache_zalloc(gfs2_rgrpd_cachep, GFP_NOFS);
 	error = -ENOMEM;
 	if (!rgd)
 		return error;