Re: Implementing Meta File information in Linux

Hans Reiser (reiser@idiom.com)
Sun, 13 Sep 1998 18:41:53 -0700


To risk repeating, storing metadata or forks in well named files in directories would solve the problem.
It would be cleaner than anything you are suggesting.

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Hans

Jens-Uwe Mager wrote:

> In article <mng==199809131913.PAA25548@hilfy.ece.cmu.edu>, "Brandon S.
> Allbery KF8NH" <allbery@kf8nh.apk.net> wrote:
>
> > No, this won't help if the user isn't logged in when a deletion occurs that
> > would affect their personal desktop database. Then again, OS/2 has similar
> > issues (delete a file with WPS information when the WPS isn't running; not
> > all WPS information is stored in extended attributes) and nevertheless
> > survives --- in this case by not doing anything about it, hence the market
> > for third-party products that clean up the desktop database. On Linux it
> > would be better to have a low-priority process running alongside the desktop
> > which cleans the database, or perhaps a cron job that runs weekly.
>
> I promise to you that any such scheme will be a maintenance nightmare. One
> of the really interesting calls is rename, this really makes any external
> meta data storage concept problematic. In particular imagine a larger
> departmental server hosting the files of a bunch of people. All these
> people do work concurrently and add, delete and rename files. You can not
> easily make that a cleanup task from cron, it has to happen in real time.
> Users just expect to have changes pop up in their windows automatically.
>
> Renames in particular have the nice semantic to be atomic, if you keep
> meta data externally that breaks. Imagine one person saving a file, an app
> renaming the old version and renaming the new version properly saved to
> disk to the desired file name. Another user might at the same time move
> the file to a different directory, which is a rename as well. There is a
> hell of race conditions in that if meta data is not renamed transparently
> with the main data.
>
> The Mac file system handles this transparently for the users, one of the
> strong points of this system.
> --
> Jens-Uwe Mager <pgp-mailto:62CFDB25>
>
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