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>

mm/shmem.c

@@ -2464,6 +2464,10 @@ static int __init init_tmpfs(void)
 {
 	int error;
 
+	error = bdi_init(&shmem_backing_dev_info);
+	if (error)
+		goto out4;
+
 	error = init_inodecache();
 	if (error)
 		goto out3;
@@ -2488,6 +2492,8 @@ out1:
 out2:
 	destroy_inodecache();
 out3:
+	bdi_destroy(&shmem_backing_dev_info);
+out4:
 	shm_mnt = ERR_PTR(error);
 	return error;
 }