mm: bdi init hooks

provide BDI constructor/destructor hooks

[akpm@linux-foundation.org: compile fix]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c
index dbd257d..4c1ebff 100644
--- a/fs/configfs/inode.c
+++ b/fs/configfs/inode.c
@@ -256,4 +256,12 @@
 	mutex_unlock(&dir->d_inode->i_mutex);
 }
 
+int __init configfs_inode_init(void)
+{
+	return bdi_init(&configfs_backing_dev_info);
+}
 
+void __exit configfs_inode_exit(void)
+{
+	bdi_destroy(&configfs_backing_dev_info);
+}