vfs: add vfs_select_inode() helper

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.2+
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 4bb4de8..7e9422c 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -565,4 +565,16 @@
 		return dentry;
 }
 
+static inline struct inode *vfs_select_inode(struct dentry *dentry,
+					     unsigned open_flags)
+{
+	struct inode *inode = d_inode(dentry);
+
+	if (inode && unlikely(dentry->d_flags & DCACHE_OP_SELECT_INODE))
+		inode = dentry->d_op->d_select_inode(dentry, open_flags);
+
+	return inode;
+}
+
+
 #endif	/* __LINUX_DCACHE_H */