From owner-freebsd-fs@FreeBSD.ORG Thu Feb 15 10:45:59 2007 Return-Path: X-Original-To: freebsd-fs@freebsd.org Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 0CD7716A400 for ; Thu, 15 Feb 2007 10:45:59 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from relay02.kiev.sovam.com (relay02.kiev.sovam.com [62.64.120.197]) by mx1.freebsd.org (Postfix) with ESMTP id 99FF313C4B4 for ; Thu, 15 Feb 2007 10:45:58 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from [212.82.216.227] (helo=fw.zoral.com.ua) by relay02.kiev.sovam.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.60) (envelope-from ) id 1HHe7Z-000LfV-5X for freebsd-fs@freebsd.org; Thu, 15 Feb 2007 12:45:57 +0200 Received: from deviant.kiev.zoral.com.ua (root@deviant.kiev.zoral.com.ua [10.1.1.148]) by fw.zoral.com.ua (8.13.4/8.13.4) with ESMTP id l1FAjchC098938 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 15 Feb 2007 12:45:38 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: from deviant.kiev.zoral.com.ua (kostik@localhost [127.0.0.1]) by deviant.kiev.zoral.com.ua (8.13.8/8.13.8) with ESMTP id l1FAjcPK084447; Thu, 15 Feb 2007 12:45:38 +0200 (EET) (envelope-from kostikbel@gmail.com) Received: (from kostik@localhost) by deviant.kiev.zoral.com.ua (8.13.8/8.13.8/Submit) id l1FAjbrR084446; Thu, 15 Feb 2007 12:45:38 +0200 (EET) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: deviant.kiev.zoral.com.ua: kostik set sender to kostikbel@gmail.com using -f Date: Thu, 15 Feb 2007 12:45:37 +0200 From: Kostik Belousov To: Tomas Olsson Message-ID: <20070215104537.GC39168@deviant.kiev.zoral.com.ua> References: <6FC9F9894A9F8C49A722CF9F2132FC2204C9DAB6@ms05.mailstreet2003.net> <45D1F30A.6080403@freebsd.org> <20070213192906.U726@chrishome.localnet> <20070214162938.GA96725@keira.kiwi-computer.com> <20070214173211.L1054@chrishome.localnet> <20070214170808.GC96725@keira.kiwi-computer.com> <20070215044707.GA39168@deviant.kiev.zoral.com.ua> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="p2kqVDKq5asng8Dg" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.2i X-Virus-Scanned: ClamAV version 0.88.7, clamav-milter version 0.88.7 on fw.zoral.com.ua X-Virus-Status: Clean X-Spam-Status: No, score=-0.1 required=5.0 tests=ALL_TRUSTED,SPF_NEUTRAL autolearn=failed version=3.1.7 X-Spam-Checker-Version: SpamAssassin 3.1.7 (2006-10-05) on fw.zoral.com.ua X-Scanner-Signature: cdcac4e9833a162831dcdc7415f73b92 X-DrWeb-checked: yes X-SpamTest-Envelope-From: kostikbel@gmail.com X-SpamTest-Group-ID: 00000000 X-SpamTest-Info: Profiles 775 [Feb 15 2007] X-SpamTest-Info: helo_type=3 X-SpamTest-Info: {received from trusted relay: not dialup} X-SpamTest-Method: none X-SpamTest-Method: Local Lists X-SpamTest-Rate: 0 X-SpamTest-Status: Not detected X-SpamTest-Status-Extended: not_detected X-SpamTest-Version: SMTP-Filter Version 3.0.0 [0255], KAS30/Release Cc: freebsd-fs@freebsd.org, "Rick C. Petty" , arla-drinkers@stacken.kth.se Subject: Re: Arla on FreeBSD X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 15 Feb 2007 10:45:59 -0000 --p2kqVDKq5asng8Dg Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Feb 15, 2007 at 11:16:00AM +0100, Tomas Olsson wrote: > Kostik Belousov writes: > > > I'm already funded and can work full time on this, but a FreeBSD hack= er > > > would help a lot. Any volunteers? > >=20 > > Sorry for me pointing out obvious, why not continue to use fs@ as place > > where to ask ? > > > You're very right, I'm just to shy to do it... Thanks. >=20 > Anyway; >=20 > Arla is built around a "small" caching fs driver (nnpfs) servicing user > requests by asking the 'arlad' daemon for help or just operating on local > files created/fetched by arlad. They communicate over a char device. >=20 > A simple read would be handled as such: > getnode/getdata rpc to arlad > installnode/installdata + wakeup msgs from arlad > VOP_READ() on newly fetched cache file >=20 > Subsequent reads on the same data would skip the rpc part, unless arlad h= as > invalidated the node. >=20 > Previously, there was a 1:1 mapping between nnpfs vnode and cache file. T= he > installdata message was then handled by fetching the cache file's vnode (= in > arlad's context), storing it in the nnpfs_node for future reference/acces= s. > Now we ended up with one cache file per "block" (large) of data, and > decided that it would be better to open/access/close the cache "block" fi= le > on each access. The closest we could get to the olden ways was to open t= he > directory where a node's cache blocks reside, in arlad's context. >=20 > The interesting part is how we open and access the cache files, and from > what context. arlad is in chroot() to avoid recursive lookups across /, a= nd > it seems like a good idea to avoid such lookups now too. >=20 > So the main question is how to properly do VOP_{LOOKUP,CREATE,WRITE} etc = on > cache files in this dual context world, without mixing identities in bad > ways or confusing the OS too much. >=20 > The currently messed up code lives in > http://cvsweb.stacken.kth.se/cvsweb.cgi/arla/nnpfs/bsd/ >=20 > Most interesting is nnpfs_vnodeops-common.c (nnpfs_write_common()) and > nnpfs_blocks.c (open_file()) I made really quick look at the places you mentioned. I have some comment for open_file(). For FreeBSD >=3D 6.x, the right way to open vnode from the kernel code is to use vn_open() (and then vn_close()) API. Something along the lines (this is for already existing file): td =3D curthread; NDINIT(&nd, LOOKUP, FOLLOW | MPSAFE, UIO_USERSPACE, fname, td); flags =3D FREAD | FWRITE; error =3D vn_open(&nd, &flags, 0, -1); if (error) return (error); vfslocked =3D NDHASGIANT(&nd); NDFREE(&nd, NDF_ONLY_PNBUF); vp =3D nd.ni_vp; vp is now locked, shall be unlocked by VOP_UNLOCK() before returning to usermode. Giant is conditionally locked based on MP-safeness of the fs vp belongs to. When Giant-protected region shall be leaved, use VFS_UNLOCK_GIANT(vfslocked); To close the vnode, use vn_close(vp, FREAD|FWRITE, td->td_ucred, td); See, for instance, kern/kern_ktrace.c, ufs/ufs/ufs_quota.c or security/audit/audit_syscalls.c for real code that does this. --p2kqVDKq5asng8Dg Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (FreeBSD) iD8DBQFF1DnRC3+MBN1Mb4gRAiqAAKCSlzaxnV3rWWufc/oKuB54/U0/sgCg3gY0 jAtwlMRvtskEz0U0iWUVkuA= =jnpE -----END PGP SIGNATURE----- --p2kqVDKq5asng8Dg--