fix comment in generic_permission()

CAP_DAC_OVERRIDE is enough for MAY_EXEC on directory, even if
no exec bits are set.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -238,7 +238,8 @@ int generic_permission(struct inode *inode, int mask, unsigned int flags,
 
 	/*
 	 * Read/write DACs are always overridable.
-	 * Executable DACs are overridable if at least one exec bit is set.
+	 * Executable DACs are overridable for all directories and
+	 * for non-directories that have least one exec bit set.
 	 */
 	if (!(mask & MAY_EXEC) || execute_ok(inode))
 		if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE))