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Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax, dma-to-storage, and swap

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On Thu, Aug 03, 2017 at 07:38:11PM -0700, Dan Williams wrote:
> [ adding linux-api to the cover letter for notification, will send the
> full set to linux-api for v3 ]

Just don't send this crap ever again.  All the so called use cases in the
earlier thread were incorrect and highly dangerous.

Promising that the block map is stable is not a useful userspace API,
as it the block map is a complete internal implementation detail.

We've been through this a few times but let me repeat it:  The only
sensible API gurantee is one that is observable and usable.

so Jan's synchronous page fault flag in one form or another makes
perfect sense as it is a clear receipe for the user:  you don't
have to call msync to persist your mmap writes.  This API is not,
it guarantees that the block map does not change, but the application
has absolutely no point of even knowing about the block map.

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[PATCH v2 0/5] fs, xfs: block map immutable files for dax,  dma-to-storage, and swap Dan Williams <dan.j.williams@intel.com> - 2017-08-04 04:40 +0200
  [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP Dan Williams <dan.j.williams@intel.com> - 2017-08-04 04:40 +0200
    Re: [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-04 21:50 +0200
      Re: [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP Dan Williams <dan.j.williams@intel.com> - 2017-08-04 22:00 +0200
    Re: [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP Dave Chinner <david@fromorbit.com> - 2017-08-05 01:40 +0200
      Re: [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP Dan Williams <dan.j.williams@intel.com> - 2017-08-05 01:50 +0200
        Re: [PATCH v2 2/5] fs, xfs: introduce FALLOC_FL_SEAL_BLOCK_MAP Dave Chinner <david@fromorbit.com> - 2017-08-05 02:10 +0200
  [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE Dan Williams <dan.j.williams@intel.com> - 2017-08-04 04:40 +0200
    Re: [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-04 22:10 +0200
      Re: [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE Dan Williams <dan.j.williams@intel.com> - 2017-08-04 22:40 +0200
    Re: [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE Christoph Hellwig <hch@lst.de> - 2017-08-05 11:50 +0200
      Re: [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE Dave Chinner <david@fromorbit.com> - 2017-08-07 02:30 +0200
        Re: [PATCH v2 1/5] fs, xfs: introduce S_IOMAP_IMMUTABLE Christoph Hellwig <hch@lst.de> - 2017-08-11 12:40 +0200
  Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax,  dma-to-storage, and swap Dan Williams <dan.j.williams@intel.com> - 2017-08-04 04:40 +0200
    Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax,         dma-to-storage, and swap Christoph Hellwig <hch@lst.de> - 2017-08-05 12:00 +0200
      Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax,  dma-to-storage, and swap Dan Williams <dan.j.williams@intel.com> - 2017-08-06 21:00 +0200
        Re: [PATCH v2 0/5] fs, xfs: block map immutable files for dax,         dma-to-storage, and swap Christoph Hellwig <hch@lst.de> - 2017-08-11 12:50 +0200
  [PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in response  to fallocate Dan Williams <dan.j.williams@intel.com> - 2017-08-04 04:40 +0200
    Re: [PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in  response to fallocate "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-04 22:20 +0200
      Re: [PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in  response to fallocate Dan Williams <dan.j.williams@intel.com> - 2017-08-04 22:50 +0200
        Re: [PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in  response to fallocate Dan Williams <dan.j.williams@intel.com> - 2017-08-04 23:00 +0200
        Re: [PATCH v2 5/5] xfs: toggle XFS_DIFLAG2_IOMAP_IMMUTABLE in  response to fallocate "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-04 23:00 +0200
  [PATCH v2 4/5] xfs: introduce XFS_DIFLAG2_IOMAP_IMMUTABLE Dan Williams <dan.j.williams@intel.com> - 2017-08-04 04:40 +0200
    Re: [PATCH v2 4/5] xfs: introduce XFS_DIFLAG2_IOMAP_IMMUTABLE "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-04 22:40 +0200
      Re: [PATCH v2 4/5] xfs: introduce XFS_DIFLAG2_IOMAP_IMMUTABLE Dan Williams <dan.j.williams@intel.com> - 2017-08-04 22:50 +0200
      Re: [PATCH v2 4/5] xfs: introduce XFS_DIFLAG2_IOMAP_IMMUTABLE Dave Chinner <david@fromorbit.com> - 2017-08-05 01:50 +0200
        Re: [PATCH v2 4/5] xfs: introduce XFS_DIFLAG2_IOMAP_IMMUTABLE "Darrick J. Wong" <darrick.wong@oracle.com> - 2017-08-05 02:00 +0200

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