vfs: make argument of d_real_inode() const

d_op->d_real() leaves the dentry alone except if the third argument is
non-zero.  Unfortunately very difficult to explain to the compiler without
a cast.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Acked-by: Jeff Layton <jlayton@poochiereds.net>

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 5ff3e9a..5beed7b 100644 (file)
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -584,9 +584,10 @@ static inline struct dentry *d_real(struct dentry *dentry,
  * If dentry is on an union/overlay, then return the underlying, real inode.
  * Otherwise return d_inode().
  */
-static inline struct inode *d_real_inode(struct dentry *dentry)
+static inline struct inode *d_real_inode(const struct dentry *dentry)
 {
-       return d_backing_inode(d_real(dentry, NULL, 0));
+       /* This usage of d_real() results in const dentry */
+       return d_backing_inode(d_real((struct dentry *) dentry, NULL, 0));
 }