[ resend to add dm-devel, linux-block, and fs-devel, apologies for the duplicates ] Changes since v1 [1] and the dax-fs RFC [2]: * rename struct dax_inode to struct dax_device (Christoph) * rewrite arch_memcpy_to_pmem() in C with inline asm * use QUEUE_FLAG_WC to gate dax cache management (Jeff) * add device-mapper plumbing for the ->copy_from_iter() and ->flush() dax_operations * kill struct blk_dax_ctl and bdev_direct_access (Christoph) * cleanup the ->direct_access() calling convention to be page based (Christoph) * introduce dax_get_by_host() and don't pollute struct super_block with dax_device details (Christoph) [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008586.html [2]: https://lwn.net/Articles/713064/ --- A few months back, in the course of reviewing the memcpy_nocache() proposal from Brian, Linus proposed that the pmem specific memcpy_to_pmem() routine be moved to be implemented at the driver level [3]: "Quite frankly, the whole 'memcpy_nocache()' idea or (ab-)using copy_user_nocache() just needs to die. It's idiotic. As you point out, it's also fundamentally buggy crap. Throw it away. There is no possible way this is ever valid or portable. We're not going to lie and claim that it is. If some driver ends up using 'movnt' by hand, that is up to that *driver*. But no way in hell should we care about this one whit in the sense of <linux/uaccess.h>." This feedback also dovetails with another fs/dax.c design wart of being hard coded to assume the backing device is pmem. We call the pmem specific copy, clear, and flush routines even if the backing device driver is one of the other 3 dax drivers (axonram, dccssblk, or brd). There is no reason to spend cpu cycles flushing the cache after writing to brd, for example, since it is using volatile memory for storage. Moreover, the pmem driver might be fronting a volatile memory range published by the ACPI NFIT, or the platform might have arranged to flush cpu caches on power fail. This latter capability is a feature that has appeared in embedded storage appliances (pre-ACPI-NFIT nvdimm platforms). So, this series: 1/ moves what was previously named "the pmem api" out of the global namespace and into drivers that need to be concerned with architecture specific persistent memory considerations. 2/ arranges for dax to stop abusing __copy_user_nocache() and implements a libnvdimm-local memcpy that uses 'movnt' on x86_64. This might be expanded in the future to use 'movntdqa' if the copy size is above some threshold, or expanded with support for other architectures [4]. 3/ makes cache maintenance optional by arranging for dax to call driver specific copy and flush operations only if the driver publishes them. 4/ allows filesytem-dax cache management to be controlled by the block device write-cache queue flag. The pmem driver is updated to clear that flag by default when pmem is driving volatile memory. [3]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008364.html [4]: https://lists.01.org/pipermail/linux-nvdimm/2017-April/009478.html These patches have been through a round of build regression fixes notified by the 0day robot. All review welcome, but the patches that need extra attention are the device-mapper and uio changes (copy_from_iter_ops). This series is based on a merge of char-misc-next (for cdev api reworks) and libnvdimm-fixes (dax locking and __copy_user_nocache fixes). --- Dan Williams (33): device-dax: rename 'dax_dev' to 'dev_dax' dax: refactor dax-fs into a generic provider of 'struct dax_device' instances dax: add a facility to lookup a dax device by 'host' device name dax: introduce dax_operations pmem: add dax_operations support axon_ram: add dax_operations support brd: add dax_operations support dcssblk: add dax_operations support block: kill bdev_dax_capable() dax: introduce dax_direct_access() dm: add dax_device and dax_operations support dm: teach dm-targets to use a dax_device + dax_operations ext2, ext4, xfs: retrieve dax_device for iomap operations Revert "block: use DAX for partition table reads" filesystem-dax: convert to dax_direct_access() block, dax: convert bdev_dax_supported() to dax_direct_access() block: remove block_device_operations ->direct_access() x86, dax, pmem: remove indirection around memcpy_from_pmem() dax, pmem: introduce 'copy_from_iter' dax operation dm: add ->copy_from_iter() dax operation support filesystem-dax: convert to dax_copy_from_iter() dax, pmem: introduce an optional 'flush' dax_operation dm: add ->flush() dax operation support filesystem-dax: convert to dax_flush() x86, dax: replace clear_pmem() with open coded memset + dax_ops->flush x86, dax, libnvdimm: move wb_cache_pmem() to libnvdimm x86, libnvdimm, pmem: move arch_invalidate_pmem() to libnvdimm x86, libnvdimm, dax: stop abusing __copy_user_nocache uio, libnvdimm, pmem: implement cache bypass for all copy_from_iter() operations libnvdimm, pmem: fix persistence warning libnvdimm, nfit: enable support for volatile ranges filesystem-dax: gate calls to dax_flush() on QUEUE_FLAG_WC libnvdimm, pmem: disable dax flushing when pmem is fronting a volatile region MAINTAINERS | 2 arch/powerpc/platforms/Kconfig | 1 arch/powerpc/sysdev/axonram.c | 45 +++- arch/x86/Kconfig | 1 arch/x86/include/asm/pmem.h | 141 ------------ arch/x86/include/asm/string_64.h | 1 block/Kconfig | 1 block/partition-generic.c | 17 - drivers/Makefile | 2 drivers/acpi/nfit/core.c | 15 + drivers/block/Kconfig | 1 drivers/block/brd.c | 52 +++- drivers/dax/Kconfig | 10 + drivers/dax/Makefile | 5 drivers/dax/dax.h | 15 - drivers/dax/device-dax.h | 25 ++ drivers/dax/device.c | 415 +++++++++++------------------------ drivers/dax/pmem.c | 10 - drivers/dax/super.c | 445 ++++++++++++++++++++++++++++++++++++++ drivers/md/Kconfig | 1 drivers/md/dm-core.h | 1 drivers/md/dm-linear.c | 53 ++++- drivers/md/dm-snap.c | 6 - drivers/md/dm-stripe.c | 65 ++++-- drivers/md/dm-target.c | 6 - drivers/md/dm.c | 112 ++++++++-- drivers/nvdimm/Kconfig | 6 + drivers/nvdimm/Makefile | 1 drivers/nvdimm/bus.c | 10 - drivers/nvdimm/claim.c | 9 - drivers/nvdimm/core.c | 2 drivers/nvdimm/dax_devs.c | 2 drivers/nvdimm/dimm_devs.c | 2 drivers/nvdimm/namespace_devs.c | 9 - drivers/nvdimm/nd-core.h | 9 + drivers/nvdimm/pfn_devs.c | 4 drivers/nvdimm/pmem.c | 82 +++++-- drivers/nvdimm/pmem.h | 26 ++ drivers/nvdimm/region_devs.c | 39 ++- drivers/nvdimm/x86.c | 155 +++++++++++++ drivers/s390/block/Kconfig | 1 drivers/s390/block/dcssblk.c | 44 +++- fs/block_dev.c | 117 +++------- fs/dax.c | 302 ++++++++++++++------------ fs/ext2/inode.c | 9 + fs/ext4/inode.c | 9 + fs/iomap.c | 3 fs/xfs/xfs_iomap.c | 10 + include/linux/blkdev.h | 19 -- include/linux/dax.h | 43 +++- include/linux/device-mapper.h | 14 + include/linux/iomap.h | 1 include/linux/libnvdimm.h | 10 + include/linux/pmem.h | 165 -------------- include/linux/string.h | 8 + include/linux/uio.h | 4 lib/Kconfig | 6 - lib/iov_iter.c | 25 ++ tools/testing/nvdimm/Kbuild | 11 + tools/testing/nvdimm/pmem-dax.c | 21 +- 60 files changed, 1584 insertions(+), 1042 deletions(-) delete mode 100644 arch/x86/include/asm/pmem.h create mode 100644 drivers/dax/device-dax.h rename drivers/dax/{dax.c => device.c} (60%) create mode 100644 drivers/dax/super.c create mode 100644 drivers/nvdimm/x86.c delete mode 100644 include/linux/pmem.h
