Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161089AbXAENMs (ORCPT ); Fri, 5 Jan 2007 08:12:48 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161083AbXAENMr (ORCPT ); Fri, 5 Jan 2007 08:12:47 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:1465 "EHLO spitz.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S965152AbXAENMq (ORCPT ); Fri, 5 Jan 2007 08:12:46 -0500 Date: Fri, 5 Jan 2007 13:12:35 +0000 From: Pavel Machek To: Miklos Szeredi Cc: matthew@wil.cx, bhalevy@panasas.com, arjan@infradead.org, mikulas@artax.karlin.mff.cuni.cz, jaharkes@cs.cmu.edu, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, nfsv4@ietf.org Subject: Re: Finding hardlinks Message-ID: <20070105131235.GB4662@ucw.cz> References: <4593E1B7.6080408@panasas.com> <20070102191504.GA5276@ucw.cz> <20070103115632.GA3062@elf.ucw.cz> <20070103135455.GA24620@parisc-linux.org> <20070104225929.GC8243@elf.ucw.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1435 Lines: 32 Hi! > > > > Some of us have machines designed to cope with cosmic rays, and would be > > > > unimpressed with a decrease in reliability. > > > > > > With the suggested samefile() interface you'd get a failure with just > > > about 100% reliability for any application which needs to compare a > > > more than a few files. The fact is open files are _very_ expensive, > > > no wonder they are limited in various ways. > > > > > > What should 'tar' do when it runs out of open files, while searching > > > for hardlinks? Should it just give up? Then the samefile() interface > > > would be _less_ reliable than the st_ino one by a significant margin. > > > > You need at most two simultenaously open files for examining any > > number of hardlinks. So yes, you can make it reliable. > > Well, sort of. Samefile without keeping fds open doesn't have any > protection against the tree changing underneath between first > registering a file and later opening it. The inode number is more You only need to keep one-file-per-hardlink-group open during final verification, checking that inode hashing produced reasonable results. Pavel -- Thanks for all the (sleeping) penguins. - 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/