From mboxrd@z Thu Jan 1 00:00:00 1970 From: Junio C Hamano Subject: Re: pread() over NFS (again) [1.5.5.4] Date: Thu, 26 Jun 2008 15:04:25 -0700 Message-ID: <7vod5nq2dy.fsf@gitster.siamese.dyndns.org> References: <6F25C1B4-85DE-4559-9471-BCD453FEB174@gmail.com> <20080626204606.GX11793@spearce.org> <7vskuzq5ix.fsf@gitster.siamese.dyndns.org> <20080626210556.GZ11793@spearce.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christian Holtje , git@vger.kernel.org To: "Shawn O. Pearce" X-From: git-owner@vger.kernel.org Fri Jun 27 00:06:05 2008 Return-path: Envelope-to: gcvg-git-2@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1KBzb8-0001UJ-3k for gcvg-git-2@gmane.org; Fri, 27 Jun 2008 00:05:54 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751921AbYFZWEf (ORCPT ); Thu, 26 Jun 2008 18:04:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752000AbYFZWEf (ORCPT ); Thu, 26 Jun 2008 18:04:35 -0400 Received: from a-sasl-fastnet.sasl.smtp.pobox.com ([207.106.133.19]:62675 "EHLO sasl.smtp.pobox.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751921AbYFZWEe (ORCPT ); Thu, 26 Jun 2008 18:04:34 -0400 Received: from localhost.localdomain (localhost [127.0.0.1]) by a-sasl-fastnet.sasl.smtp.pobox.com (Postfix) with ESMTP id E8CE623995; Thu, 26 Jun 2008 18:04:32 -0400 (EDT) Received: from pobox.com (ip68-225-240-77.oc.oc.cox.net [68.225.240.77]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by a-sasl-fastnet.sasl.smtp.pobox.com (Postfix) with ESMTPSA id 2DD8B23994; Thu, 26 Jun 2008 18:04:29 -0400 (EDT) In-Reply-To: <20080626210556.GZ11793@spearce.org> (Shawn O. Pearce's message of "Thu, 26 Jun 2008 17:05:56 -0400") User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) X-Pobox-Relay-ID: DB679D7C-43CB-11DD-9B09-CE28B26B55AE-77302942!a-sasl-fastnet.pobox.com Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Archived-At: "Shawn O. Pearce" writes: > We have a file position we saw once before as the start of a delta. > We wrote it down to disk. We want to go back and open it up, as > we have the base decompressed and in memory and need to compute > the SHA-1 of the object that resides at this offset. > > And *wham* we get an EOF. Where there should be data. Where we > know there is data. We have written that earlier in the same process? Are we playing games with mixed mmap() and pread()? Is fsync() or msync() or unmap/remap needed? > Actually, I think the last time someone reported something like this > in Git it turned out to be an NFS kernel bug. I didn't quote it > in my reply to him, but I think he did say this was a linux client, > linux server. This is getting into the area Linus would immediately know the answer to, but he is away for this week.