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    SubjectRe: 9p caching with cache=loose and cache=fscache
    On Tue, Mar 28, 2023 at 11:31:50AM +0900, Dominique Martinet wrote:
    > Luis Chamberlain wrote on Mon, Mar 27, 2023 at 10:39:54AM -0700:
    > > > I have fixed what
    > > > I hope to be my last bug with the new patch series so it should be
    > > > going into linux-next today.
    > >
    > > Nice, thanks, since kdevops relies on a host kernel though and we strive
    > > to have stability for that, I personally like to recommend distro
    > > kernels and so they're a few kernel releases out of date. So debian-testing
    > > is on 6.1 as of today for example.
    > > [...]
    > > - opts: "ro,trans=virtio,version=9p2000.L,posixacl,cache=loose"
    > > + opts: "ro,trans=virtio,version=9p2000.L,posixacl,cache=none"
    >
    > Yes, if you want something mostly coherent with the host, cache=none (or
    > cache=mmap if you need mmap, iirc linux build does for linking? if you
    > want to do that on guest...) is what you'll want to use on current
    > kernels.

    OK cool, we use 9p to build on the host and so all the guest has to do
    is just 'make modules_install install'.

    > > BTW the qemu wiki seems to suggest cache=loose and its why I used it on
    > > kdevops as a default. What about the following so to avoid folks running
    > > into similar issues? I can go and update the wiki too.
    >
    > I've added Christian in Cc for this point, he's more active on the qemu
    > side
    > (thread started here:
    > https://lkml.kernel.org/r/ZA0FEyOtRBvpIXbi@bombadil.infradead.org
    > )
    >
    > I have no opinion on the current wording, the default is there for a
    > reason and it's a safe default (none), and cache=loose is clearly
    > described with "no attempts are made at consistency, intended for
    > exclusive, read-only mounts" which I think ought to be clear enough
    > (exclusive means not shared with the host), but if you think it's not
    > clear enough it probably isn't.

    It certainly was not.

    LUis

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