From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [PATCH 5/6] Teach "fsck" not to follow subproject links Date: Wed, 11 Apr 2007 16:53:15 -0700 (PDT) Message-ID: References: <461D6432.90205@v ilain.net> <461D6858.4090 007@vilain.net> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Sam Vilain , Git Mailing List , Junio C Hamano To: David Lang X-From: git-owner@vger.kernel.org Thu Apr 12 01:53:27 2007 Return-path: Envelope-to: gcvg-git@gmane.org Received: from vger.kernel.org ([209.132.176.167]) by lo.gmane.org with esmtp (Exim 4.50) id 1Hbmcw-0005Rx-Gm for gcvg-git@gmane.org; Thu, 12 Apr 2007 01:53:26 +0200 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932195AbXDKXxX (ORCPT ); Wed, 11 Apr 2007 19:53:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932203AbXDKXxX (ORCPT ); Wed, 11 Apr 2007 19:53:23 -0400 Received: from smtp.osdl.org ([65.172.181.24]:37050 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932195AbXDKXxX (ORCPT ); Wed, 11 Apr 2007 19:53:23 -0400 Received: from shell0.pdx.osdl.net (fw.osdl.org [65.172.181.6]) by smtp.osdl.org (8.12.8/8.12.8) with ESMTP id l3BNrGVZ027188 (version=TLSv1/SSLv3 cipher=EDH-RSA-DES-CBC3-SHA bits=168 verify=NO); Wed, 11 Apr 2007 16:53:17 -0700 Received: from localhost (shell0.pdx.osdl.net [10.9.0.31]) by shell0.pdx.osdl.net (8.13.1/8.11.6) with ESMTP id l3BNrFwF018375; Wed, 11 Apr 2007 16:53:16 -0700 In-Reply-To: X-Spam-Status: No, hits=-0.957 required=5 tests=AWL,OSDL_HEADER_SUBJECT_BRACKETED X-Spam-Checker-Version: SpamAssassin 2.63-osdl_revision__1.119__ X-MIMEDefang-Filter: osdl$Revision: 1.177 $ X-Scanned-By: MIMEDefang 2.36 Sender: git-owner@vger.kernel.org Precedence: bulk X-Mailing-List: git@vger.kernel.org Archived-At: On Wed, 11 Apr 2007, David Lang wrote: > > would it make sense to have a --multiple-project option for fsck that would > let you specify multiple 'projects' that share a object set and have the > default checking not do the reachability checks that cause problems in this > case? Well, the thing is, sharing object directories actually makes things *harder* to check, rather than easier. It can be a nice space optimization, and yes, if there really is a lot of shared state, it can make it much cheaper to do some of the checks, but right now we have absolutely *no* way for fsck to then do the reachability check, because there is no way to tell fsck where all the refs are (since now the refs come in from multiple repositories!) So the individual objects get cheaper to fsck (no need to fsck shared objects over and over again), but the reachability gets much harder to fsck. It's not an insurmountable problem, or even necessarily a very large one, but it boils down to one very basic issue: - nobody seems to actually *use* the shared object directory model! The thing is, with pack-files and alternates directories, a lot of the original reasons for shared object directories simply don't exist.. Linus