Recently there was an effort to introduce dax_operations to unwind the abuse of the user-copy api in the pmem api [1]. Christoph noted that we should not add new block-dax operations as it is further abuse of struct block_device [2]. The ->direct_access() method in block_device_operations was an expedient way to get the filesystem-dax capability bootstrapped. However, looking forward to native persistent memory filesystems, they can forgo the block layer and mount directly on a provider of dax services, a dax inode. For the time being, since current dax capable filesystems are block based, we need a facility to look up this dax object via the block-device name. If this approach looks reasonable I'll follow up with reworking the proposed ->copy_from_iter(), ->flush(), and ->clear() dax operations into this new scheme. These patches survive a run of the libnvdimm unit tests, but I have not tested the non-libnvdimm dax drivers. [1]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008586.html [2]: https://lists.01.org/pipermail/linux-nvdimm/2017-January/008638.html --- Dan Williams (17): dax: refactor dax-fs into a generic provider of dax inodes dax: convert dax_inode locking to srcu dax: add a facility to lookup a dax inode 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() block: introduce bdev_dax_direct_access() dm: add dax_operations support (producer) dm: add dax_operations support (consumer) fs: update mount_bdev() to lookup dax infrastructure ext2, ext4, xfs: retrieve dax_inode through iomap operations Revert "block: use DAX for partition table reads" fs, dax: convert filesystem-dax to bdev_dax_direct_access block: remove block_device_operations.direct_access and related infrastructure arch/powerpc/platforms/Kconfig | 1 arch/powerpc/sysdev/axonram.c | 37 +++ block/Kconfig | 1 block/partition-generic.c | 17 -- drivers/Makefile | 2 drivers/block/Kconfig | 1 drivers/block/brd.c | 48 +++- drivers/dax/Kconfig | 9 + drivers/dax/Makefile | 5 drivers/dax/dax.h | 19 +- drivers/dax/device-dax.h | 25 ++ drivers/dax/device.c | 257 ++++------------------- drivers/dax/pmem.c | 2 drivers/dax/super.c | 434 +++++++++++++++++++++++++++++++++++++++ drivers/md/Kconfig | 1 drivers/md/dm-core.h | 3 drivers/md/dm-linear.c | 15 + drivers/md/dm-snap.c | 8 + drivers/md/dm-stripe.c | 16 + drivers/md/dm-table.c | 2 drivers/md/dm-target.c | 10 + drivers/md/dm.c | 43 +++- drivers/nvdimm/Kconfig | 1 drivers/nvdimm/pmem.c | 46 +++- drivers/nvdimm/pmem.h | 7 - drivers/s390/block/Kconfig | 1 drivers/s390/block/dcssblk.c | 41 +++- fs/block_dev.c | 75 ++----- fs/dax.c | 149 ++++++------- fs/ext2/inode.c | 1 fs/ext4/inode.c | 1 fs/iomap.c | 3 fs/super.c | 32 +++ fs/xfs/xfs_aops.c | 13 + fs/xfs/xfs_aops.h | 1 fs/xfs/xfs_buf.h | 1 fs/xfs/xfs_iomap.c | 1 fs/xfs/xfs_super.c | 3 include/linux/blkdev.h | 7 - include/linux/dax.h | 29 ++- include/linux/device-mapper.h | 16 + include/linux/fs.h | 1 include/linux/iomap.h | 1 tools/testing/nvdimm/Kbuild | 6 - tools/testing/nvdimm/pmem-dax.c | 12 - 45 files changed, 927 insertions(+), 477 deletions(-) create mode 100644 drivers/dax/device-dax.h rename drivers/dax/{dax.c => device.c} (74%) create mode 100644 drivers/dax/super.c -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
