From owner-freebsd-hackers@FreeBSD.ORG Sun Dec 9 21:41:20 2007 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 203F416A417 for ; Sun, 9 Dec 2007 21:41:20 +0000 (UTC) (envelope-from BearPerson@gmx.net) Received: from mail.gmx.net (mail.gmx.net [213.165.64.20]) by mx1.freebsd.org (Postfix) with SMTP id 8515A13C43E for ; Sun, 9 Dec 2007 21:41:19 +0000 (UTC) (envelope-from BearPerson@gmx.net) Received: (qmail invoked by alias); 09 Dec 2007 21:14:37 -0000 Received: from port-83-236-56-222.dynamic.qsc.de (EHLO gmx.net) [83.236.56.222] by mail.gmx.net (mp048) with SMTP; 09 Dec 2007 22:14:37 +0100 X-Authenticated: #20254835 X-Provags-ID: V01U2FsdGVkX188tGMSgBs8vFesxbzz3CwYOghTb8xaTL0P/TTzIf oW7StTlNfgYF3z Date: Sun, 9 Dec 2007 22:14:33 +0100 From: Karsten Behrmann To: freebsd-hackers@freebsd.org Message-ID: <20071209221433.216218d7@Karsten.Behrmanns.Kasten> In-Reply-To: References: X-Mailer: Claws Mail 2.9.2 (GTK+ 2.8.18; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: multipart/signed; boundary=Sig_qCfLlgaMlXqmI5rVZAy9BR8; protocol="application/pgp-signature"; micalg=PGP-SHA1 X-Y-GMX-Trusted: 0 Subject: Re: unionfs & kqueue? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 09 Dec 2007 21:41:20 -0000 --Sig_qCfLlgaMlXqmI5rVZAy9BR8 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Heya, > Does unionfs work with kqueue? When I run `tail -f` on a file residing > on unionfs with cd9660 underneeth and md+ufs over it, it doesn't detect > changes. The changes are immediately visible, just not with tail -f. Hmm. When you start the tail -f, does the file reside on the cd9660 or already on the md? See if tail -F does a better job. My guess would be that, since you cannot modify a file on any filesystem except the top one, unionfs must change semantics of open so that even opening for writing or appending silently creates a new copy of the file on the top filesystem (if the file didn't reside there already). As tail -f still has the lower-layer file open, it never notices that there's a new file by the name. (this behavior is the same as echo foo >foo tail -f foo # in another terminal echo bar >bar mv bar foo which also "fails" to notice the new data) So Far, Karsten "BearPerson" Behrmann p.s.: this is probably why the -F option was added to tail --=20 Open source is not about suing someone who sells your software. It is about being able to walk behind him, grinning, and waving free CDs with the equivalent of what he is trying to sell. --Sig_qCfLlgaMlXqmI5rVZAy9BR8 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (GNU/Linux) iD8DBQFHXFq8AksKLoO3vywRAktuAJ0a8m5P4GRw+EylQyUQloyMQwe3nwCeK5Ys qJbIV9IH8DFmKDjzuUCuDO4= =ZZDb -----END PGP SIGNATURE----- --Sig_qCfLlgaMlXqmI5rVZAy9BR8--