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    Subject[PATCH v3 0/6] vfio, dax: prevent long term filesystem-dax pins and other fixes
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    Changes since v2 [1]:

    * Fix yet more compile breakage in the FS_DAX=n and DEV_DAX=y case.
    (0day robot)

    [1]: https://lists.01.org/pipermail/linux-nvdimm/2018-February/014046.html

    ---

    The vfio interface, like RDMA, wants to setup long term (indefinite)
    pins of the pages backing an address range so that a guest or userspace
    driver can perform DMA to the with physical address. Given that this
    pinning may lead to filesystem operations deadlocking in the
    filesystem-dax case, the pinning request needs to be rejected.

    The longer term fix for vfio, RDMA, and any other long term pin user, is
    to provide a 'pin with lease' mechanism. Similar to the leases that are
    hold for pNFS RDMA layouts, this userspace lease gives the kernel a way
    to notify userspace that the block layout of the file is changing and
    the kernel is revoking access to pinned pages.

    ---

    Dan Williams (6):
    dax: fix vma_is_fsdax() helper
    dax: fix dax_mapping() definition in the FS_DAX=n + DEV_DAX=y case
    xfs, dax: introduce IS_FSDAX()
    dax: fix S_DAX definition
    dax: short circuit vma_is_fsdax() in the CONFIG_FS_DAX=n case
    vfio: disable filesystem-dax page pinning


    drivers/vfio/vfio_iommu_type1.c | 18 +++++++++++++++---
    fs/xfs/xfs_file.c | 14 +++++++-------
    fs/xfs/xfs_ioctl.c | 4 ++--
    fs/xfs/xfs_iomap.c | 6 +++---
    fs/xfs/xfs_reflink.c | 2 +-
    include/linux/dax.h | 9 ++++++---
    include/linux/fs.h | 8 ++++++--
    7 files changed, 40 insertions(+), 21 deletions(-)

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