From owner-freebsd-fs@FreeBSD.ORG Fri Feb 1 10:27:19 2008 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 521A916A419; Fri, 1 Feb 2008 10:27:19 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from falcon.cybervisiontech.com (falcon.cybervisiontech.com [217.20.163.9]) by mx1.freebsd.org (Postfix) with ESMTP id 049C413C461; Fri, 1 Feb 2008 10:27:18 +0000 (UTC) (envelope-from avg@icyb.net.ua) Received: from localhost (localhost [127.0.0.1]) by falcon.cybervisiontech.com (Postfix) with ESMTP id 252E443E519; Fri, 1 Feb 2008 12:27:18 +0200 (EET) X-Virus-Scanned: Debian amavisd-new at falcon.cybervisiontech.com Received: from falcon.cybervisiontech.com ([127.0.0.1]) by localhost (falcon.cybervisiontech.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id b5m+0X1hyfDH; Fri, 1 Feb 2008 12:27:18 +0200 (EET) Received: from [10.2.1.87] (gateway.cybervisiontech.com.ua [88.81.251.18]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by falcon.cybervisiontech.com (Postfix) with ESMTP id 76D8A43E50E; Fri, 1 Feb 2008 12:27:17 +0200 (EET) Message-ID: <47A2F404.7010208@icyb.net.ua> Date: Fri, 01 Feb 2008 12:27:16 +0200 From: Andriy Gapon User-Agent: Thunderbird 2.0.0.9 (X11/20080123) MIME-Version: 1.0 To: Remko Lodder , scottl@FreeBSD.org, freebsd-fs@freebsd.org References: <200612221824.kBMIOhfM049471@freefall.freebsd.org> <47A2EDB0.8000801@icyb.net.ua> In-Reply-To: <47A2EDB0.8000801@icyb.net.ua> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Bruce Evans Subject: Re: kern/84983: [udf] [patch] udf filesystem: stat-ting files could randomly fail X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Feb 2008 10:27:19 -0000 on 01/02/2008 12:00 Andriy Gapon said the following: > ---- a different, under-debugged problem ----- > BTW, on some smaller directories (but still large ones) I get some very > strange problems with reading a directory too. It seems like some bad > interaction between udf and buffer cache system. I added a lot of > debugging prints and the problems looks like the following: > > read starting at physical sector (2048-byte one) N, size is ~20K, N%4=0 > bread(4 * N, some_big_size) > correct data is read > repeat the above couple dozen times > read starting at physical sector (2048-byte one) N+1, size is ~20K > bread(4 * (N+1), some_big_size) > data is read from physical sector N+4 (instead of N+1) > > I remember that Bruce Evance warned me that something like this could > happen but I couldn't understand him, because I don't understand > VM/buffer subsystem. I'll try to dig up the email. > Sorry for the flood - additional info: if I limit max read size in udf_readatoffset() to 2048 (instead of MAXBSIZE), then large directories can be read OK. Seems like something with overlapping buffers, maybe? BTW, here's how I created test environment for the described issues (in tcsh): mkdir /tmp/bigdir cd /tmp/bigdir set i=1 while ($i < NNNNN) touch file.$i set i=`expr $i + 1` end cd /tmp mkisofs -udf -o test.iso bigdir mdconfig -a -t vnode -f test.iso -S 2048 -u 0 mount_udf /dev/md0 /mnt ls -l /mnt -- Andriy Gapon