gfs2: Add missing truncate_inode_pages_final for sd_aspace

Gfs2 creates an address space for its rgrps called sd_aspace, but it never
called truncate_inode_pages_final on it. This confused vfs greatly which
tried to reference the address space after gfs2 had freed the superblock
that contained it.

This patch adds a call to truncate_inode_pages_final for sd_aspace, thus
avoiding the use-after-free.

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

fs/gfs2/super.c

@@ -738,6 +738,7 @@ restart:
 	gfs2_jindex_free(sdp);
 	/*  Take apart glock structures and buffer lists  */
 	gfs2_gl_hash_clear(sdp);
+	truncate_inode_pages_final(&sdp->sd_aspace);
 	gfs2_delete_debugfs_file(sdp);
 	/*  Unmount the locking protocol  */
 	gfs2_lm_unmount(sdp);