Re: squashfs seems nfs-incompatible

From: Jan Engelhardt (jengelh_at_linux01.gwdg.de)
Date: 08/05/05

  • Next message: Davy Durham: "/proc question" 
    Date:	Fri, 5 Aug 2005 08:08:07 +0200 (MEST)
To: Phillip Lougher <phil.lougher@gmail.com>

    Hi,

    >> I found out that you cannot mount an exported squash fs. The exports(5) fsid=
    >> parameter does not help it [like it did with unionfs].
    >
    >The exports(5) man page says fsid=num is necessary for filesystems on
    >non-block devices - I don't know whether this includes loopback
    >filesystems. Have you tried exporting a Squashfs filesystem mounted
    >on a real block device?

    Loopback is a real block device, and no, fsid= does not help it. I have talked
    with the unionfs people, because it works for them. After a short flash of
    idea and comparison, it turns out that squashfs is missing
    sb->s_export->get_parent (the only requirement as it seems). Includes that you
    have sb->s_export non-null, of course. sb->s_export can be set within
    fill_super().

    >I've never tried to export a Squashfs filesystem, and so I don't know
    >if it works. If it doesn't, I would say it is because Squashfs (like
    >Cramfs) doesn't store correct nlink information for directories.
    >
    >The next release does store nlink information, has support for > 4GB
    >files/filesystems, and other nice improvements. I'm hoping to release
    >an alpha release soon.

    FTR, I currently cheated by using
    `mount -t unionfs -o dirs=/squash=ro none /squash` to get the export working.

    Jan Engelhardt 

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