Date: Wed, 07 Aug 2002 21:13:39 -0400 From: "David E. Cross" <crossd@cs.rpi.edu> To: Terry Lambert <tlambert2@mindspring.com> Cc: "David E. Cross" <crossd@cs.rpi.edu>, Kelly Yancey <kbyanc@posi.net>, fs@FreeBSD.ORG, guptar@cs.rpi.edu, crossd@cs.rpi.edu Subject: Re: vnodes (UFS journaling)? Message-ID: <200208080113.g781Ddu79224@monica.cs.rpi.edu> In-Reply-To: Message from Terry Lambert <tlambert2@mindspring.com> of "Wed, 07 Aug 2002 17:54:05 PDT." <3D51C12D.354F6D99@mindspring.com> References: <20020807170230.Y6264-100000@gateway.posi.net> <200208080037.g780b9H79114@monica.cs.rpi.edu> <3D51C12D.354F6D99@mindspring.com>
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What we are currently doing is at filesystem mount we construct a
vnode-pointer to the journal file. Then we use that vp to
use VOP_WRITE (and maybe VOP_READ in the future).
I take it that this isn't kosher, and we will need to rework this to use
low-level UFS calls?
> Your question still makes no sense.
>
> What does doing this have to do with vnodes?
>
> It sounds like you are trying to use a vnode to represent a
> journal entry, rather than an abstract reference to a file
> in a file system.
>
> Vnodes are the OS's idea of a file stream. It's the VFS's
> job to translate a vnode argument to a file stream operation
> (VOP_*) into a reference to a VFS implementation-specific
> backing object (e.g. an inode reference), and it's *that*
> object off of which your journal extents have to be referenced.
>
> Basically, this comes down to your internal implementation
> of VOP_GETPAGES, VOP_READ, VOP_PUTPAGES, and VOP_WRITE, and
> how these get translated into journal references and writes,
> respectively.
>
> Maybe the problem is that you are using the default version
> of the {get|put}pages, such that vmo_bject_t page references
> are translated into raw device page writes, instead of going
> thorugh your VFS specific versions and turning into journal
> entries as a result of pages being dirtied?
--
David Cross | email: crossd@cs.rpi.edu
Lab Director | Rm: 308 Lally Hall
Rensselaer Polytechnic Institute, | Ph: 518.276.2860
Department of Computer Science | Fax: 518.276.4033
I speak only for myself. | WinNT:Linux::Linux:FreeBSD
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