Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753675Ab0HDP0f (ORCPT ); Wed, 4 Aug 2010 11:26:35 -0400 Received: from fxip-0047f.externet.hu ([88.209.222.127]:42594 "EHLO pomaz-ex.szeredi.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752288Ab0HDP0e (ORCPT ); Wed, 4 Aug 2010 11:26:34 -0400 To: Valerie Aurora CC: viro@zeniv.linux.org.uk, miklos@szeredi.hu, jblunck@suse.de, hch@infradead.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, vaurora@redhat.com, Valdis.Kletnieks@vt.edu In-reply-to: <1276627208-17242-28-git-send-email-vaurora@redhat.com> (message from Valerie Aurora on Tue, 15 Jun 2010 11:39:57 -0700) Subject: Re: [PATCH 27/38] union-mount: In-kernel file copyup routines References: <1276627208-17242-1-git-send-email-vaurora@redhat.com> <1276627208-17242-28-git-send-email-vaurora@redhat.com> Message-Id: From: Miklos Szeredi Date: Wed, 04 Aug 2010 17:26:28 +0200 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 796 Lines: 19 On Tue, 15 Jun 2010, Valerie Aurora wrote: > When a file on the read-only layer of a union mount is altered, it > must be copied up to the topmost read-write layer. This patch creates > union_copyup() and its supporting routines. > > Thanks to Valdis Kletnieks for a bug fix. What happens if there's a crash in the middle of the copyup? Possible solution is using rename to atomically "replace" the underlying file. That however introduces namespace issues: where to put the temporary file which then needs to be deleted on "fsck.union"? Miklos -- 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/