From owner-freebsd-questions@FreeBSD.ORG Thu Jan 19 00:43:23 2006 Return-Path: X-Original-To: freebsd-questions@FreeBSD.org Delivered-To: freebsd-questions@FreeBSD.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 4A2A416A420 for ; Thu, 19 Jan 2006 00:43:23 +0000 (GMT) (envelope-from kris@obsecurity.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.FreeBSD.org (Postfix) with ESMTP id E016043D53 for ; Thu, 19 Jan 2006 00:43:22 +0000 (GMT) (envelope-from kris@obsecurity.org) Received: from obsecurity.dyndns.org (elvis.mu.org [192.203.228.196]) by elvis.mu.org (Postfix) with ESMTP id AC4A01A3C1F; Wed, 18 Jan 2006 16:43:22 -0800 (PST) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id AB8E25154A; Wed, 18 Jan 2006 19:43:21 -0500 (EST) Date: Wed, 18 Jan 2006 19:43:21 -0500 From: Kris Kennaway To: "Shin,Hee-Sub" Message-ID: <20060119004321.GA58284@xor.obsecurity.org> References: <000001c61c89$0da481a0$19a5580a@swcenter.sec.samsung.co.kr> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="9amGYk9869ThD9tj" Content-Disposition: inline In-Reply-To: <000001c61c89$0da481a0$19a5580a@swcenter.sec.samsung.co.kr> User-Agent: Mutt/1.4.2.1i Cc: freebsd-questions@FreeBSD.org Subject: Re: About VFS locking strategy... X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 19 Jan 2006 00:43:23 -0000 --9amGYk9869ThD9tj Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jan 19, 2006 at 08:43:55AM +0900, Shin,Hee-Sub wrote: > Hi all.=20 >=20 > =20 >=20 > I'm speluking with source code of FreeBSD now, comparing VFS of FBSD and > the linux's.=20 >=20 > =20 >=20 > I have a question related with concurrent accesses to the file system. It > is seemed that VFS locks and unlocks each VNODEs before calling VNODE OPS > provided by underlying FS. For example, it calls vn_lock(vp, ...) before > jumps to VOP_READ() in vn_read().=20 >=20 > =20 >=20 > WindowsCE kernel also has a component that is responsible for switching FS > requests to appropriate file-system underlying and similar with VFS of ma= ny > UNIX variants, but it's not perfectly same. In WindowsCE world, file syst= em > driver code can be called on re-entry and file system programmer should > keep this in mind. The manager does not manage any synchronization proble= ms > that can be occurred when multiple threads access to the file system. It > has only a few locks for protecting its own data structures.=20 >=20 > =20 >=20 > How does it manage synchronization problems in the VFS of FreeBSD?=20 >=20 > =20 >=20 > Please give me a detailed description about lock strategy the FreeBSD use= s.=20 This question might be too general to get any replies, but it would still be better asked on fs@ or hackers@. Kris --9amGYk9869ThD9tj Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (FreeBSD) iD8DBQFDzuCpWry0BWjoQKURAgsJAKCm5XsvtC34txjnfOx7IO7X54dymgCeMDIc BejZJeE9I9s/IK67DRL4ZTc= =loE4 -----END PGP SIGNATURE----- --9amGYk9869ThD9tj--