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    SubjectRe: [ckrm-tech] [PATCH 0/5] Allow more than PAGESIZE data read in configfs
    On Tue, Oct 10, 2006 at 02:31:43PM -0700, Paul Menage wrote:
    > > NAK. This forces a complex and inappropriate interface on the
    > >majority of users, and doesn't honor configfs' simplicity-first design.
    > How is the seq_file interface complex and inappropriate? For the
    > configfs clients it's basically a drop-in replacement for sprintf(),
    > as Chandra's patches show.

    Well, they now have to learn seq_file. They now get to assume
    that "spewing large amounts of junk" is the default rather than "single
    attribute", which is correct. None of it is relevant for the majority
    of correct users.
    It exposes the "I'm a file" knowledge down to the client module.
    The entire point of configfs is that the "filesystem bits" are
    independant of the "client bits". To the client, it's an item
    hierarchy. To the user, the interface happens to be a filesystem.
    Technically, the seq_printf() as a drop-in replacement seems to
    be functional. I'm worried about lifetiming, but I think it's OK (what
    do I mean? If I open the file, I'd better not be able to remove the
    client module until everything is torn down. If I close the file, it
    had better get all torn down before module_put() so that when
    ->release() returns, te module can safely be removed. I *think* this
    change satisfies these worries, but it's something that absolutely has
    to be done right. Yes, I'm very paranoid about this).
    My bigger worry is that we haven't solved the write side. How
    does one *set* a large attribute? It had better not be multiple
    attributes. I know that your module doesn't set it, but hey, we don't
    codify that requirement. Perhaps a patch where we say "if you are a
    large display attribute, we'll use seq_file and error on write because
    it isn't allowed" but that leaves the old buffer-based approach for
    normal-sized read-write attributes.



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