[PATCH v10 00/21] Support ext4 on NV-DIMMs

Matthew Wilcox
2014-08-27T04:34:54Z

One of the primary uses for NV-DIMMs is to expose them as a block device
and use a filesystem to store files on the NV-DIMM. While that works,
it currently wastes memory and CPU time buffering the files in the page
cache. We have support in ext2 for bypassing the page cache, but it
has some races which are unfixable in the current design. This series
of patches rewrite the underlying support, and add support for direct
access to ext4.

Note that patch 6/21 has been included in
https://git.kernel.org/cgit/linux/kernel/git/viro/vfs.git/log/?h=for-next-candidate

This iteration of the patchset rebases to 3.17-rc2, changes the page fault
locking, fixes a couple of bugs and makes a few other minor changes.

- Move the calculation of the maximum size available at the requested
location from the ->direct_access implementations to bdev_direct_access()
- Fix a comment typo (Ross Zwisler)
- Check that the requested length is positive in bdev_direct_access(). If
it is not, assume that it's an errno, and just return it.
- Fix some whitespace issues flagged by checkpatch
- Added the Acked-by responses from Kirill that I forget in the last round
- Added myself to MAINTAINERS for DAX
- Fixed compilation with !CONFIG_DAX (Vishal Verma)
- Revert the locking in the page fault handler back to an earlier version.
If we hit the race that we were trying to protect against, we will leave
blocks allocated past the end of the file. They will be removed on file
removal, the next truncate, or fsck.

Matthew Wilcox (20):
axonram: Fix bug in direct_access
Change direct_access calling convention
Fix XIP fault vs truncate race
Allow page fault handlers to perform the COW
Introduce IS_DAX(inode)
Add copy_to_iter(), copy_from_iter() and iov_iter_zero()
Replace XIP read and write with DAX I/O
Replace ext2_clear_xip_target with dax_clear_blocks
Replace the XIP page fault handler with the DAX page fault handler
Replace xip_truncate_page with dax_truncate_page
Replace XIP documentation with DAX documentation
Remove get_xip_mem
ext2: Remove ext2_xip_verify_sb()
ext2: Remove ext2_use_xip
ext2: Remove xip.c and xip.h
Remove CONFIG_EXT2_FS_XIP and rename CONFIG_FS_XIP to CONFIG_FS_DAX
ext2: Remove ext2_aops_xip
Get rid of most mentions of XIP in ext2
xip: Add xip_zero_page_range
brd: Rename XIP to DAX

Ross Zwisler (1):
ext4: Add DAX functionality

Documentation/filesystems/Locking | 3 -
Documentation/filesystems/dax.txt | 91 +++++++
Documentation/filesystems/ext4.txt | 2 +
Documentation/filesystems/xip.txt | 68 -----
MAINTAINERS | 6 +
arch/powerpc/sysdev/axonram.c | 19 +-
drivers/block/Kconfig | 13 +-
drivers/block/brd.c | 26 +-
drivers/s390/block/dcssblk.c | 21 +-
fs/Kconfig | 21 +-
fs/Makefile | 1 +
fs/block_dev.c | 40 +++
fs/dax.c | 497 +++++++++++++++++++++++++++++++++++++
fs/exofs/inode.c | 1 -
fs/ext2/Kconfig | 11 -
fs/ext2/Makefile | 1 -
fs/ext2/ext2.h | 10 +-
fs/ext2/file.c | 45 +++-
fs/ext2/inode.c | 38 +--
fs/ext2/namei.c | 13 +-
fs/ext2/super.c | 53 ++--
fs/ext2/xip.c | 91 -------
fs/ext2/xip.h | 26 --
fs/ext4/ext4.h | 6 +
fs/ext4/file.c | 49 +++-
fs/ext4/indirect.c | 18 +-
fs/ext4/inode.c | 51 ++--
fs/ext4/namei.c | 10 +-
fs/ext4/super.c | 39 ++-
fs/open.c | 5 +-
include/linux/blkdev.h | 6 +-
include/linux/fs.h | 49 +++-
include/linux/mm.h | 1 +
include/linux/uio.h | 3 +
mm/Makefile | 1 -
mm/fadvise.c | 6 +-
mm/filemap.c | 6 +-
mm/filemap_xip.c | 483 -----------------------------------
mm/iov_iter.c | 237 ++++++++++++++++--
mm/madvise.c | 2 +-
mm/memory.c | 33 ++-
41 files changed, 1229 insertions(+), 873 deletions(-)
create mode 100644 Documentation/filesystems/dax.txt
delete mode 100644 Documentation/filesystems/xip.txt
create mode 100644 fs/dax.c
delete mode 100644 fs/ext2/xip.c
delete mode 100644 fs/ext2/xip.h
delete mode 100644 mm/filemap_xip.c

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2.0.0