Changes since v5 [1]: * Compile fixes from a much improved coccinelle semantic patch (thanks Julia!) that adds a 'flags' argument to all the ->mmap() implementations in the kernel. (0day-kbuild-robot) * Make the deprecated MAP_DENYWRITE and MAP_EXECUTABLE flags return EOPNOTSUPP with the new mmap3() syscall. (Kirill) * Minor changelog updates. * Updated cover letter with a clarified summary and checklist of questions to answer before proceeding further. --- MAP_DIRECT is a mechanism to ask the kernel to atomically manage the file-offset to physical-address block relationship of a mapping relative to any memory-mapped access. It is complimentary to the proposed MAP_SYNC mechanism which makes the same guarantee relative to cpu faults. MAP_DIRECT goes a step further and makes this guarantee for agents that may not generate mmu faults, but at the cost of restricting the kernel's ability to mutate the block-map at will. MAP_SYNC is preferred for scenarios that want full filesystem feature support while avoiding fsync/msync overhead, but also do not need to contend with hypervisors or RDMA agents that do not give the kernel an mmu fault. In other words, the need for MAP_DIRECT is driven by the scarcity of SVM capable hardware (Shared Virtual Memory, where hardware generates mmu faults), hypervisors like Xen that need to interrogate the physical address layout of a file to maintain their own physical-address mapping metadata outside the kernel, and peer-to-peer DMA use cases that always bypass the mmu. The MAP_DIRECT mechanism allows a filesystem to be used for capacity provisioning and access control where these aforementioned applications would otherwise be forced to roll a custom solution on top of a raw device-file. Questions: 1/ Is the definition of MAP_DIRECT constrained enough to allow us to make the restrictions it imposes on the kernel finer grained over time? 2/ Do the XFS changes look sane? They attempt to avoid adding any overhead to the non-MAP_DIRECT case at the expense of the new i_mapdcount atomic counter in the XFS inode. 3/ While the generic MAP_DIRECT description warns that the block-map may not be actually be immutable for the lifetime of the mapping it also does not preclude a filesystem from making that guarantee. In fact, Dave wants to be able to get a stable view of the physical mapping [2], and Xen has a need to do the same [3]. Do we want userspace to start making "XFS + MAP_DIRECT == Immutable" assumptions, or do we need a separate mechanism for that guarantee? [1]: https://lkml.org/lkml/2017/8/16/114 [2]: https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1467677.html [3]: https://lists.xen.org/archives/html/xen-devel/2017-04/msg00419.html --- Dan Williams (5): vfs: add flags parameter to ->mmap() in 'struct file_operations' fs, xfs: introduce S_IOMAP_SEALED mm: introduce mmap3 for safely defining new mmap flags fs, xfs: introduce MAP_DIRECT for creating block-map-atomic file ranges fs, fcntl: add F_MAP_DIRECT arch/arc/kernel/arc_hostlink.c | 3 - arch/mips/kernel/vdso.c | 2 arch/powerpc/kernel/proc_powerpc.c | 3 - arch/powerpc/kvm/book3s_64_vio.c | 3 - arch/powerpc/platforms/cell/spufs/file.c | 21 ++-- arch/powerpc/platforms/powernv/opal-prd.c | 3 - arch/um/drivers/mmapper_kern.c | 3 - arch/x86/entry/syscalls/syscall_32.tbl | 1 arch/x86/entry/syscalls/syscall_64.tbl | 1 drivers/android/binder.c | 3 - drivers/char/agp/frontend.c | 3 - drivers/char/bsr.c | 3 - drivers/char/hpet.c | 6 + drivers/char/mbcs.c | 3 - drivers/char/mbcs.h | 3 - drivers/char/mem.c | 11 +- drivers/char/mspec.c | 9 +- drivers/char/uv_mmtimer.c | 6 + drivers/dax/device.c | 3 - drivers/dma-buf/dma-buf.c | 4 + drivers/firewire/core-cdev.c | 3 - drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 3 - drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h | 3 - drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 5 + drivers/gpu/drm/arc/arcpgu_drv.c | 5 + drivers/gpu/drm/ast/ast_drv.h | 3 - drivers/gpu/drm/ast/ast_ttm.c | 3 - drivers/gpu/drm/bochs/bochs.h | 3 - drivers/gpu/drm/bochs/bochs_mm.c | 3 - drivers/gpu/drm/cirrus/cirrus_drv.h | 3 - drivers/gpu/drm/cirrus/cirrus_ttm.c | 3 - drivers/gpu/drm/drm_gem.c | 3 - drivers/gpu/drm/drm_gem_cma_helper.c | 6 + drivers/gpu/drm/drm_vm.c | 3 - drivers/gpu/drm/etnaviv/etnaviv_drv.h | 3 - drivers/gpu/drm/etnaviv/etnaviv_gem.c | 5 + drivers/gpu/drm/exynos/exynos_drm_gem.c | 5 + drivers/gpu/drm/exynos/exynos_drm_gem.h | 3 - drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.h | 3 - drivers/gpu/drm/hisilicon/hibmc/hibmc_ttm.c | 3 - drivers/gpu/drm/i810/i810_dma.c | 3 - drivers/gpu/drm/i915/i915_gem_dmabuf.c | 2 drivers/gpu/drm/mediatek/mtk_drm_gem.c | 5 + drivers/gpu/drm/mediatek/mtk_drm_gem.h | 3 - drivers/gpu/drm/mgag200/mgag200_drv.h | 3 - drivers/gpu/drm/mgag200/mgag200_ttm.c | 3 - drivers/gpu/drm/msm/msm_drv.h | 3 - drivers/gpu/drm/msm/msm_gem.c | 5 + drivers/gpu/drm/nouveau/nouveau_ttm.c | 5 + drivers/gpu/drm/nouveau/nouveau_ttm.h | 2 drivers/gpu/drm/omapdrm/omap_drv.h | 3 - drivers/gpu/drm/omapdrm/omap_gem.c | 5 + drivers/gpu/drm/qxl/qxl_drv.h | 3 - drivers/gpu/drm/qxl/qxl_ttm.c | 3 - drivers/gpu/drm/radeon/radeon_drv.c | 3 - drivers/gpu/drm/radeon/radeon_ttm.c | 3 - drivers/gpu/drm/rockchip/rockchip_drm_gem.c | 5 + drivers/gpu/drm/rockchip/rockchip_drm_gem.h | 3 - drivers/gpu/drm/tegra/gem.c | 5 + drivers/gpu/drm/tegra/gem.h | 3 - drivers/gpu/drm/udl/udl_drv.h | 3 - drivers/gpu/drm/udl/udl_gem.c | 5 + drivers/gpu/drm/vc4/vc4_bo.c | 5 + drivers/gpu/drm/vc4/vc4_drv.h | 3 - drivers/gpu/drm/vgem/vgem_drv.c | 7 + drivers/gpu/drm/virtio/virtgpu_drv.h | 3 - drivers/gpu/drm/virtio/virtgpu_ttm.c | 3 - drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 3 - drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 3 - drivers/hsi/clients/cmt_speech.c | 3 - drivers/hwtracing/intel_th/msu.c | 3 - drivers/hwtracing/stm/core.c | 3 - drivers/infiniband/core/uverbs_main.c | 3 - drivers/infiniband/hw/hfi1/file_ops.c | 6 + drivers/infiniband/hw/qib/qib_file_ops.c | 5 + drivers/media/v4l2-core/v4l2-dev.c | 3 - drivers/misc/aspeed-lpc-ctrl.c | 3 - drivers/misc/cxl/api.c | 5 + drivers/misc/cxl/cxl.h | 3 - drivers/misc/cxl/file.c | 3 - drivers/misc/genwqe/card_dev.c | 3 - drivers/misc/mic/scif/scif_fd.c | 3 - drivers/misc/mic/vop/vop_vringh.c | 3 - drivers/misc/sgi-gru/grufile.c | 3 - drivers/mtd/mtdchar.c | 3 - drivers/pci/proc.c | 3 - drivers/rapidio/devices/rio_mport_cdev.c | 3 - drivers/sbus/char/flash.c | 3 - drivers/sbus/char/jsflash.c | 3 - drivers/scsi/cxlflash/superpipe.c | 5 + drivers/scsi/sg.c | 3 - drivers/staging/android/ashmem.c | 3 - drivers/staging/comedi/comedi_fops.c | 3 - .../staging/lustre/lustre/llite/llite_internal.h | 3 - drivers/staging/lustre/lustre/llite/llite_mmap.c | 5 + drivers/staging/vboxvideo/vbox_drv.h | 3 - drivers/staging/vboxvideo/vbox_ttm.c | 3 - drivers/staging/vme/devices/vme_user.c | 3 - drivers/uio/uio.c | 3 - drivers/usb/core/devio.c | 3 - drivers/usb/mon/mon_bin.c | 3 - drivers/vfio/vfio.c | 7 + drivers/video/fbdev/core/fbmem.c | 3 - drivers/video/fbdev/pxa3xx-gcu.c | 3 - drivers/xen/gntalloc.c | 3 - drivers/xen/gntdev.c | 3 - drivers/xen/privcmd.c | 3 - drivers/xen/xenbus/xenbus_dev_backend.c | 3 - drivers/xen/xenfs/xenstored.c | 3 - fs/9p/vfs_file.c | 10 +- fs/aio.c | 3 - fs/attr.c | 10 ++ fs/btrfs/file.c | 3 - fs/ceph/addr.c | 3 - fs/ceph/super.h | 3 - fs/cifs/cifsfs.h | 6 + fs/cifs/file.c | 10 +- fs/coda/file.c | 5 + fs/ecryptfs/file.c | 5 + fs/ext2/file.c | 5 + fs/ext4/file.c | 3 - fs/f2fs/file.c | 3 - fs/fcntl.c | 15 +++ fs/fuse/file.c | 8 + fs/gfs2/file.c | 3 - fs/hugetlbfs/inode.c | 3 - fs/kernfs/file.c | 3 - fs/ncpfs/mmap.c | 3 - fs/ncpfs/ncp_fs.h | 2 fs/nfs/file.c | 5 + fs/nfs/internal.h | 2 fs/nilfs2/file.c | 3 - fs/ocfs2/mmap.c | 3 - fs/ocfs2/mmap.h | 3 - fs/open.c | 6 + fs/orangefs/file.c | 5 + fs/proc/inode.c | 7 + fs/proc/vmcore.c | 6 + fs/ramfs/file-nommu.c | 6 + fs/read_write.c | 3 + fs/romfs/mmap-nommu.c | 3 - fs/ubifs/file.c | 5 + fs/xfs/libxfs/xfs_bmap.c | 5 + fs/xfs/xfs_bmap_util.c | 3 + fs/xfs/xfs_file.c | 114 +++++++++++++++++++- fs/xfs/xfs_inode.h | 1 fs/xfs/xfs_ioctl.c | 6 + fs/xfs/xfs_super.c | 1 include/drm/drm_gem.h | 3 - include/drm/drm_gem_cma_helper.h | 3 - include/drm/drm_legacy.h | 3 - include/linux/fs.h | 21 ++-- include/linux/mm.h | 2 include/linux/mman.h | 46 ++++++++ include/linux/syscalls.h | 3 + include/misc/cxl.h | 3 - include/uapi/asm-generic/mman.h | 1 include/uapi/linux/fcntl.h | 5 + ipc/shm.c | 5 + kernel/events/core.c | 3 - kernel/kcov.c | 3 - kernel/relay.c | 3 - mm/filemap.c | 19 ++- mm/mmap.c | 56 +++++++++- mm/nommu.c | 4 - mm/shmem.c | 3 - net/socket.c | 6 + security/selinux/selinuxfs.c | 6 + sound/core/compress_offload.c | 3 - sound/core/hwdep.c | 3 - sound/core/info.c | 3 - sound/core/init.c | 3 - sound/core/oss/pcm_oss.c | 3 - sound/core/pcm_native.c | 3 - sound/oss/soundcard.c | 3 - sound/oss/swarm_cs4297a.c | 3 - virt/kvm/kvm_main.c | 3 - 177 files changed, 689 insertions(+), 234 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
