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    Subject[PATCH 00/30] Read-only bind mounts (-mm resend)
    This is against current Linus git.

    Miklos, if you send me a copy of your current unprivledged mount
    code merged against mainline, I'll merge with this.


    This rolls up all the -mm bugfixes that were accumulated, and
    addresses some new review comments from Al. Also contains some
    reworking from hch and a patch from Jeff Dike.

    Just posting here to let everyone have a sniff before we resend
    it back to -mm.


    Why do we need r/o bind mounts?

    This feature allows a read-only view into a read-write filesystem.
    In the process of doing that, it also provides infrastructure for
    keeping track of the number of writers to any given mount.

    This has a number of uses. It allows chroots to have parts of
    filesystems writable. It will be useful for containers in the future
    because users may have root inside a container, but should not
    be allowed to write to somefilesystems. This also replaces
    patches that vserver has had out of the tree for several years.

    It allows security enhancement by making sure that parts of
    your filesystem are read-only (such as when you don't trust your
    FTP server), when you don't want to have entire new filesystems
    mounted, or when you want atime selectively updated.
    I've been using this script:

    to test that the feature is working as desired. It takes a
    directory and makes a regular bind and a r/o bind mount of it.
    It then performs some normal filesystem operations on the
    three directories, including ones that are expected to fail,
    like creating a file on the r/o mount.

    Acked-by: Al Viro <>
    Signed-off-by: Christoph Hellwig <>
    Signed-off-by: Dave Hansen <>

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      Last update: 2008-02-15 23:41    [W:0.026 / U:11.764 seconds]
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