From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 934AAC433FF for ; Tue, 6 Aug 2019 22:42:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6668B2189F for ; Tue, 6 Aug 2019 22:42:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565131359; bh=EknRqymxoTJDoep6zXcHd2kEz6NOkgX5lpboEZyvK0A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=li4hytK1BX7lbJEF3nGFO0m2tjvdqsyuqPC/2UNLvinHFoakO0wYnQDupbseK5tAn hChwGW9tpqI2ilvLRNNcJC33KTA4FNMLJDArKN3+Aj+o6SyWFkpMey1he5l5ykj4vf uy8U01B9YeZ0ErIrQUYbSngRVzrzWPLxClBNgmJo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727082AbfHFWmf (ORCPT ); Tue, 6 Aug 2019 18:42:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:50214 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725974AbfHFWmf (ORCPT ); Tue, 6 Aug 2019 18:42:35 -0400 Received: from localhost.localdomain (c-73-223-200-170.hsd1.ca.comcast.net [73.223.200.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 59715216F4; Tue, 6 Aug 2019 22:42:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565131354; bh=EknRqymxoTJDoep6zXcHd2kEz6NOkgX5lpboEZyvK0A=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cRh0QGv3KwTTqbv+C7Ks/mBaeOIGhCJHLj3nOSKzHlIKAhpFAmN1MWab7DWF8nx8I WHnTV4WsnnbNtCgS8xeKytBXCWAIaXnnmy/UCklx3tamhutLFKYv1VtIrbLYJTnU7d YG5Jq9zrIGWI62RQa/qPahOdYTKYpqWdHbsu9V0s= Date: Tue, 6 Aug 2019 15:42:33 -0700 From: Andrew Morton To: NeilBrown Cc: Alexander Viro , Sergei Turchanov , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] seq_file: fix problem when seeking mid-record. Message-Id: <20190806154233.5b16a91fd27c6cf129770566@linux-foundation.org> In-Reply-To: <87mugojl0f.fsf@notabene.neil.brown.name> References: <3bd775ab-9e31-c6b3-374e-7a9982a9a8cd@farpost.com> <5c4c0648-2a96-4132-9d22-91c22e7c7d4d@huawei.com> <877e7xl029.fsf@notabene.neil.brown.name> <2d54ca59-9c22-0b75-3087-3718b30b8d11@farpost.com> <87mugojl0f.fsf@notabene.neil.brown.name> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Mon, 05 Aug 2019 14:26:08 +1000 NeilBrown wrote: > If you use lseek or similar (e.g. pread) to access > a location in a seq_file file that is within a record, > rather than at a record boundary, then the first read > will return the remainder of the record, and the second > read will return the whole of that same record (instead > of the next record). > Whnn seeking to a record boundary, the next record is > correctly returned. ouch. I'm surprised it took this long to be noticed. Maybe we need a seqfile-basher in tools/testing/selftests/proc or somewhere.