+/*
+ * We _really_ want to just do "generic_permission()" without
+ * even looking at the inode->i_op values. So we keep a cache
+ * flag in inode->i_opflags, that says "this has not special
+ * permission function, use the fast case".
+ */
+static inline int do_inode_permission(struct inode *inode, int mask)
+{
+ if (unlikely(!(inode->i_opflags & IOP_FASTPERM))) {
+ if (likely(inode->i_op->permission))
+ return inode->i_op->permission(inode, mask);
+
+ /* This gets set once for the inode lifetime */
+ spin_lock(&inode->i_lock);
+ inode->i_opflags |= IOP_FASTPERM;
+ spin_unlock(&inode->i_lock);
+ }
+ return generic_permission(inode, mask);
+}
+