fs: remove bdev->bd_inode_backing_dev_info

It has been unused since it was introduced in:

commit 520808bf20e90fdbdb320264ba7dd5cf9d47dcac
Author: Andrew Morton <akpm@osdl.org>
Date:   Fri May 21 00:46:17 2004 -0700

    [PATCH] block device layer: separate backing_dev_info infrastructure

So lets just kill it.

Acked-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 3581a4e..71e7e03 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -420,7 +420,6 @@
 {
 	struct bdev_inode *bdi = BDEV_I(inode);
 
-	bdi->bdev.bd_inode_backing_dev_info = NULL;
 	kmem_cache_free(bdev_cachep, bdi);
 }
 
diff --git a/fs/inode.c b/fs/inode.c
index ae7b67e..b2ba83d 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -182,9 +182,7 @@
 	if (sb->s_bdev) {
 		struct backing_dev_info *bdi;
 
-		bdi = sb->s_bdev->bd_inode_backing_dev_info;
-		if (!bdi)
-			bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
+		bdi = sb->s_bdev->bd_inode->i_mapping->backing_dev_info;
 		mapping->backing_dev_info = bdi;
 	}
 	inode->i_private = NULL;
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index d4168e2..ad391a8 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -591,9 +591,7 @@
 
 	nilfs->ns_mount_state = le16_to_cpu(sbp->s_state);
 
-	bdi = nilfs->ns_bdev->bd_inode_backing_dev_info;
-	if (!bdi)
-		bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
+	bdi = nilfs->ns_bdev->bd_inode->i_mapping->backing_dev_info;
 	nilfs->ns_bdi = bdi ? : &default_backing_dev_info;
 
 	/* Finding last segment */
diff --git a/include/linux/fs.h b/include/linux/fs.h
index b21cf6b..db29588 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -655,7 +655,6 @@
 	int			bd_invalidated;
 	struct gendisk *	bd_disk;
 	struct list_head	bd_list;
-	struct backing_dev_info *bd_inode_backing_dev_info;
 	/*
 	 * Private data.  You must have bd_claim'ed the block_device
 	 * to use this.  NOTE:  bd_claim allows an owner to claim