Messages in this thread | | | Date | Fri, 11 Jun 1999 10:35:01 +0200 (CET) | From | Juan Antonio Martinez <> | Subject | Re: cachefs module for linux? |
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On Thu, 10 Jun 1999, August Hörandl wrote:
> Date: Thu, 10 Jun 1999 22:41:09 +0200 > From: August Hörandl <hoerandl@elina.htlw1.ac.at> > To: linux-kernel@vger.rutgers.edu, Jeff Garzik <jgarzik@pobox.com> > Subject: Re: cachefs module for linux? > > > There is a filesystem cache for NFS -but i am not sure if it is still useable.
Is not only for nfs but isofs, smbfs an so
> It is mentioned in the HOWTO at > http://cuiwww.unige.ch/info/pc/remote-boot/howto-4.html#ss4.4 > and it worked with (early) 2.0 kernels; it consists of an executable > - no source > :-(
I've asked for sources. no response yet
> and a kernel patch
But doesn't work on 2.2.X kernels :(
Their idea is simple:
a) Starting on an empty directory do a readdir() on it and makes symlinks on every entry to the real file b) If open regular file is made the symlink is removed and replaced with the whole file. If the file already exists just use cached copy. No consistency check are done over the original and cached files. c) If opendir is requested, directory is created in the cache and cachefs daemon performs a) on the newly created directory d) Only cache copies are performed on directories and regular files. Symlinks sockets, special files and so are redirected to the real file e) when cache space is next to go out, cachefs daemon performs an unlink of files cached ( not directories ) using a First-in-Fisrt-out algorithm. This is the major problem: the entire cachefs is stopped during the cleanning process ( what about a cache clean thread... a really big error ) f) Access, creation, and modification times are not consistent between cached and original files. Lack of lock control, so we must ensure that original files won't change and are mounted readonly (just as /usr or /opt directory)
Seems not to be very difficult patch the provided patch and create a GPL'd source available cachefs daemon.... but not sure if the limitations on this package make it good for starting job
Ideas?
Juan Antonio \|||/ / _ _ \ \ o o / =========================o00o===U===o00o====================================== Juan Antonio Martínez Universidad Politécnica de Madrid email: jantonio@dit.upm.es E.T.S.I Telecomunicación http://www.dit.upm.es/~jantonio Ciudad Universitaria s/n Tel: 34-1-5495700 ext 328 Centro de Cálculo Fax: 34-1-3367333 Madrid, Spain ============================================================================== God Bless the pesimists... because their backups will work
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