Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753368Ab1EISak (ORCPT ); Mon, 9 May 2011 14:30:40 -0400 Received: from mx3-phx2.redhat.com ([209.132.183.24]:38286 "EHLO mx3-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751911Ab1EISaj (ORCPT ); Mon, 9 May 2011 14:30:39 -0400 Date: Mon, 9 May 2011 14:30:39 -0400 (EDT) From: Dave Anderson To: Josef Bacik Cc: linux-kernel@vger.kernel.org, Josef Bacik Message-ID: <843658708.415439.1304965839290.JavaMail.root@zmail05.collab.prod.int.phx2.redhat.com> In-Reply-To: <4DC82E3B.2090501@redhat.com> Subject: Re: [PATCH] fs: kill default_llseek MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [10.5.5.71] X-Mailer: Zimbra 6.0.9_GA_2686 (ZimbraWebClient - FF3.0 (Linux)/6.0.9_GA_2686) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3385 Lines: 104 ----- Original Message ----- > On 05/09/2011 02:03 PM, Dave Anderson wrote: > > > > On Thursday 05 May 2011 16:27:57 Josef Bacik wrote: > >> Looking at this llseek stuff I noticed that default_llseek is the > >> exact same as > >> generic_file_llseek, so kill default_llseek. I patched this using > >> spatch with > >> just a simple > >> > >> @@ > >> @@ > >> > >> - default_llseek > >> + generic_file_llseek > > > > ... > > > >> diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > >> index d245cb2..6f37c39 100644 > >> --- a/fs/proc/kcore.c > >> +++ b/fs/proc/kcore.c > >> @@ -558,7 +558,7 @@ static int open_kcore(struct inode *inode, > >> struct file *filp) > >> static const struct file_operations proc_kcore_operations = { > >> .read = read_kcore, > >> .open = open_kcore, > >> - .llseek = default_llseek, > >> + .llseek = generic_file_llseek, > >> }; > > > >> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c > >> index 74802bc5..0cafd9e 100644 > >> --- a/fs/proc/vmcore.c > >> +++ b/fs/proc/vmcore.c > >> @@ -163,7 +163,7 @@ static ssize_t read_vmcore(struct file *file, > >> char __user *buffer, > >> > >> static const struct file_operations proc_vmcore_operations = { > >> .read = read_vmcore, > >> - .llseek = default_llseek, > >> + .llseek = generic_file_llseek, > >> }; > > > > Both /proc/kcore and /proc/vmcore currently require > > default_llseek(). > > They were both changed to use generic_file_llseek(), but then > > subsequently > > reverted back to default_llseek(): > > > > commit c227e69028473c7c7994a9b0a2cc0034f3f7e0fe > > Author: Arnd Bergmann > > Date: Wed Sep 22 13:04:54 2010 -0700 > > > > /proc/vmcore: fix seeking > > > > Commit 73296bc611 ("procfs: Use generic_file_llseek in > > /proc/vmcore") > > broke seeking on /proc/vmcore. This changes it back to use > > default_llseek > > in order to restore the original behaviour. > > ... > > > > > > commit ceff1a770933e2ca2bf995b453dade4ec47a9878 > > Author: Dave Anderson > > Date: Wed Jan 12 17:00:36 2011 -0800 > > > > /proc/kcore: fix seeking > > > > Commit 34aacb2920 ("procfs: Use generic_file_llseek in > > /proc/kcore") broke > > seeking on /proc/kcore. This changes it back to use > > default_llseek in > > order to restore the original behavior. > > ... > > > > How is it getting s_maxbytes set to 0? I'm looking everywhere and I > can't see how that can happen. It seems that anybody using sget should > be getting it set to MAX_NONLFS so they should all be ok. I'm looking > at proc in particular and it doesn't do anything special, so it should > be ok. (Obviously it wasn't, I'm just trying to understand how we're > getting s_maxbytes == 0 so we can fix that and kill default_llseek). > Thanks, > > Josef Well, in the case of /proc/kcore, it was set to MAX_NON_LFS (2GB-1) which is too small because the file offset values in the /proc/kcore PT_LOAD segments may exceed or start beyond that offset value. I guessing the same thing was seen with /proc/vmcore, even though Arnd's commit message implies that it was 0? Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/