Changes since v1 [1]: * Fix the detection of device-dax file instances in vma_is_fsdax(). (Haozhong, Gerd) * Fix 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 (5): dax: fix vma_is_fsdax() helper dax: fix dax_mapping() definition in the FS_DAX=n + DEV_DAX=y case 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 +++++++++++++++--- include/linux/dax.h | 9 ++++++--- include/linux/fs.h | 6 ++++-- 3 files changed, 25 insertions(+), 8 deletions(-)