[Unionfs] Unionfs on preempt RT

[Stephen Hemminger]

I wanted to test -RT kernel with unionfs. Since RT kernel
changes inode definition slightly, the following is needed.

Don't bother putting it in main version, but others may
need it.

diff --git a/fs/unionfs/super.c b/fs/unionfs/super.c
index 5fa4253..6f384e7 100644
--- a/fs/unionfs/super.c
+++ b/fs/unionfs/super.c
@@ -92,7 +92,7 @@ static void unionfs_delete_inode(struct inode *inode)
 	spin_unlock(&inode->i_lock);
 #endif
 
-	if (inode->i_data.nrpages)
+	if (mapping_nrpages(&inode->i_data))
 		truncate_inode_pages(&inode->i_data, 0);
 
 	clear_inode(inode);