fs: deduplicate noop_backing_dev_info

hugetlbfs, kernfs and dlmfs can simply use noop_backing_dev_info instead
of creating a local duplicate.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

fs/ocfs2/dlmfs/dlmfs.c

@@ -390,12 +390,6 @@ clear_fields:
 	ip->ip_conn = NULL;
 }
 
-static struct backing_dev_info dlmfs_backing_dev_info = {
-	.name		= "ocfs2-dlmfs",
-	.ra_pages	= 0,	/* No readahead */
-	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK,
-};
-
 static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 {
 	struct inode *inode = new_inode(sb);
@@ -404,7 +398,7 @@ static struct inode *dlmfs_get_root_inode(struct super_block *sb)
 	if (inode) {
 		inode->i_ino = get_next_ino();
 		inode_init_owner(inode, NULL, mode);
-		inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
+		inode->i_mapping->backing_dev_info = &noop_backing_dev_info;
 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 		inc_nlink(inode);
 
@@ -428,7 +422,7 @@ static struct inode *dlmfs_get_inode(struct inode *parent,
 
 	inode->i_ino = get_next_ino();
 	inode_init_owner(inode, parent, mode);
-	inode->i_mapping->backing_dev_info = &dlmfs_backing_dev_info;
+	inode->i_mapping->backing_dev_info = &noop_backing_dev_info;
 	inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 
 	ip = DLMFS_I(inode);
@@ -643,10 +637,6 @@ static int __init init_dlmfs_fs(void)
 	int status;
 	int cleanup_inode = 0, cleanup_worker = 0;
 
-	status = bdi_init(&dlmfs_backing_dev_info);
-	if (status)
-		return status;
-
 	dlmfs_inode_cache = kmem_cache_create("dlmfs_inode_cache",
 				sizeof(struct dlmfs_inode_private),
 				0, (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
@@ -673,7 +663,6 @@ bail:
 			kmem_cache_destroy(dlmfs_inode_cache);
 		if (cleanup_worker)
 			destroy_workqueue(user_dlm_worker);
-		bdi_destroy(&dlmfs_backing_dev_info);
 	} else
 		printk("OCFS2 User DLM kernel interface loaded\n");
 	return status;
@@ -693,7 +682,6 @@ static void __exit exit_dlmfs_fs(void)
 	rcu_barrier();
 	kmem_cache_destroy(dlmfs_inode_cache);
 
-	bdi_destroy(&dlmfs_backing_dev_info);
 }
 
 MODULE_AUTHOR("Oracle");