| From | Dan Williams <> | Date | Thu, 13 Dec 2018 11:55:47 -0800 | Subject | Re: [PATCH 15/52] fuse: map virtio_fs DAX window BAR |
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On Mon, Dec 10, 2018 at 9:22 AM Vivek Goyal <vgoyal@redhat.com> wrote: > > From: Stefan Hajnoczi <stefanha@redhat.com> > > Experimental QEMU code introduces an MMIO BAR for mapping portions of > files in the virtio-fs device. Map this BAR so that FUSE DAX can access > file contents from the host page cache.
FUSE DAX sounds terrifying, can you explain a bit more about what this is?
> The DAX window is accessed by the fs/dax.c infrastructure and must have > struct pages (at least on x86). Use devm_memremap_pages() to map the > DAX window PCI BAR and allocate struct page.
PCI BAR space is not cache coherent, what prevents these pages from being used in paths that would do:
object = page_address(pfn_to_page(virtio_fs_pfn));
...?
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