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Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite()

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On Tue 25-07-17 10:01:58, Christoph Hellwig wrote:
> On Tue, Jul 25, 2017 at 01:14:00AM +0300, Kirill A. Shutemov wrote:
> > I guess it's up to filesystem if it wants to reuse the same spot to write
> > data or not. I think your assumptions works for ext4 and xfs. I wouldn't
> > be that sure for btrfs or other filesystems with CoW support.
> 
> Or XFS with reflinks for that matter.  Which currently can't be
> combined with DAX, but I had a somewhat working version a few month
> ago.

But in cases like COW when the block mapping changes, the process
must run unmap_mapping_range() before installing the new PTE so that all
processes mapping this file offset actually refault and see the new
mapping. So this would go through pte_none() case. Am I missing something?

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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[PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() Ross Zwisler <ross.zwisler@linux.intel.com> - 2017-07-24 19:10 +0200
  Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-07-25 00:20 +0200
    Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() Christoph Hellwig <hch@lst.de> - 2017-07-25 10:10 +0200
      Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() Jan Kara <jack@suse.cz> - 2017-07-25 11:40 +0200
        Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() Christoph Hellwig <hch@lst.de> - 2017-07-25 14:20 +0200
          Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() Jan Kara <jack@suse.cz> - 2017-07-25 15:00 +0200
            Re: [PATCH v5 1/5] mm: add vm_insert_mixed_mkwrite() "Kirill A. Shutemov" <kirill@shutemov.name> - 2017-07-25 16:40 +0200

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