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dax: remove VM_MIXEDMAP for fsdax and device dax
authorDave Jiang <dave.jiang@intel.com>
Fri, 17 Aug 2018 22:43:40 +0000 (15:43 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 17 Aug 2018 23:20:27 +0000 (16:20 -0700)
commite1fb4a0864958fac2fb1b23f9f4562a9f90e3e8f
tree58c58654235f9432d77f73cfc14a1e07ae7bbcc6
parente36488c83b6d871b35dd555afb2d434bd61687cf
dax: remove VM_MIXEDMAP for fsdax and device dax

This patch is reworked from an earlier patch that Dan has posted:
https://patchwork.kernel.org/patch/10131727/

VM_MIXEDMAP is used by dax to direct mm paths like vm_normal_page() that
the memory page it is dealing with is not typical memory from the linear
map.  The get_user_pages_fast() path, since it does not resolve the vma,
is already using {pte,pmd}_devmap() as a stand-in for VM_MIXEDMAP, so we
use that as a VM_MIXEDMAP replacement in some locations.  In the cases
where there is no pte to consult we fallback to using vma_is_dax() to
detect the VM_MIXEDMAP special case.

Now that we have explicit driver pfn_t-flag opt-in/opt-out for
get_user_pages() support for DAX we can stop setting VM_MIXEDMAP.  This
also means we no longer need to worry about safely manipulating vm_flags
in a future where we support dynamically changing the dax mode of a
file.

DAX should also now be supported with madvise_behavior(), vma_merge(),
and copy_page_range().

This patch has been tested against ndctl unit test.  It has also been
tested against xfstests commit: 625515d using fake pmem created by
memmap and no additional issues have been observed.

Link: http://lkml.kernel.org/r/152847720311.55924.16999195879201817653.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
drivers/dax/device.c
fs/ext2/file.c
fs/ext4/file.c
fs/xfs/xfs_file.c
mm/hmm.c
mm/huge_memory.c
mm/ksm.c
mm/memory.c
mm/migrate.c
mm/mlock.c
mm/mmap.c