kill d_backing_dentry()

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

include/linux/dcache.h

@@ -530,21 +530,6 @@ static inline struct inode *d_backing_inode(const struct dentry *upper)
 	return inode;
 }
 
-/**
- * d_backing_dentry - Get upper or lower dentry we should be using
- * @upper: The upper layer
- *
- * This is the helper that should be used to get the dentry of the inode that
- * will be used if this dentry were opened as a file.  It may be the upper
- * dentry or it may be a lower dentry pinned by the upper.
- *
- * Normal filesystems should not use this to access their own dentries.
- */
-static inline struct dentry *d_backing_dentry(struct dentry *upper)
-{
-	return upper;
-}
-
 /**
  * d_real - Return the real dentry
  * @dentry: the dentry to query