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    SubjectRe: [PATCH 0/5] bio: Direct IO: convert to pin_user_pages_fast()
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    On 8/24/20 6:54 PM, Al Viro wrote:
    > On Fri, Aug 21, 2020 at 09:20:54PM -0700, John Hubbard wrote:
    >
    >> Direct IO behavior:
    >>
    >> ITER_IOVEC:
    >> pin_user_pages_fast();
    >> break;
    >>
    >> ITER_KVEC: // already elevated page refcount, leave alone
    >> ITER_BVEC: // already elevated page refcount, leave alone
    >> ITER_PIPE: // just, no :)
    >
    > Why? What's wrong with splice to O_DIRECT file?
    >

    Oh! I'll take a look. Is this the fs/splice.c stuff? I ruled this out early
    mainly based on Christoph's comment in [1] ("ITER_PIPE is rejected іn the
    direct I/O path"), but if it's supportable then I'll hook it up.

    (As you can see, I'm still very much coming up to speed on the various things
    that invoke iov_iter_get_pages*().)

    [1] https://lore.kernel.org/kvm/20190724061750.GA19397@infradead.org/

    thanks,
    --
    John Hubbard
    NVIDIA

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