From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754942Ab0I2TSM (ORCPT ); Wed, 29 Sep 2010 15:18:12 -0400 Received: from moutng.kundenserver.de ([212.227.126.171]:53239 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754662Ab0I2TSL (ORCPT ); Wed, 29 Sep 2010 15:18:11 -0400 From: Arnd Bergmann To: Roland Dreier Subject: Re: [PATCH] RDMA/cxgb4: Add default_llseek to debugfs files. Date: Wed, 29 Sep 2010 21:17:54 +0200 User-Agent: KMail/1.13.5 (Linux/2.6.36-rc5+; KDE/4.5.1; x86_64; ; ) Cc: Steve Wise , linux-rdma@vger.kernel.org, linux-next@vger.kernel.org, linux-kernel@vger.kernel.org References: <20100929141112.26944.21931.stgit@build.ogc.int> In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <201009292117.54828.arnd@arndb.de> X-Provags-ID: V02:K0:UqHGOPAdJlgqrHsuUVjRAFJFb7+1vCiCfvNL1A0GLyl B30C6pIDld8dOW9p5Mfyd1LdR29NtF23iXWJ+uc9XZzV7X32UF rnpIEccTEu9fa6PEdH6+tI8/pWunz/texYGomm3hzw36qJi5xV soY834iuBl0vRGlYtakqfJe+VUGVhI0ocPwhUjc+ohd+0hfyPG Z4qzsGUX2TO4j1BK5K+rg== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday 29 September 2010 19:19:32 Roland Dreier wrote: > > @@ -182,6 +182,7 @@ static const struct file_operations qp_debugfs_fops = { > > .open = qp_open, > > .release = qp_release, > > .read = debugfs_read, > > + .llseek = default_llseek, > > }; > > I think this could actually be generic_file_llseek (right, Arnd?). The main difference between default_llseek and generic_file_llseek is that default_llseek doesn't care about the maximum file size of the underlying file system, which is ULONG_MAX on debugfs, so they are equivalent. In general, the preferred one is no_llseek for those files where you know you do not need to seek. If you do, I'd use default_llseek for character devices and generic_file_llseek for file systems that set the s_maxbytes. Arnd