GFS2: Fix address space from page function

Now that rgrps use the address space which is part of the super
block, we need to update gfs2_mapping2sbd() to take account of
that. The only way to do that easily is to use a different set
of address_space_operations for rgrps.

Reported-by: Abhi Das <adas@redhat.com>
Tested-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

fs/gfs2/meta_io.c

@@ -97,6 +97,11 @@ const struct address_space_operations gfs2_meta_aops = {
 	.releasepage = gfs2_releasepage,
 };
 
+const struct address_space_operations gfs2_rgrp_aops = {
+	.writepage = gfs2_aspace_writepage,
+	.releasepage = gfs2_releasepage,
+};
+
 /**
  * gfs2_getbuf - Get a buffer with a given address space
  * @gl: the glock