Re: [PATCH 0/7] fsdax,xfs: Add reflink&dedupe support for fsdax

[Ruan Shiyang]

On 2021/2/8 下午11:39, Jan Kara wrote:
> On Mon 08-02-21 01:09:17, Shiyang Ruan wrote:
> > This patchset is attempt to add CoW support for fsdax, and take XFS,
> > which has both reflink and fsdax feature, as an example.
> >
> > One of the key mechanism need to be implemented in fsdax is CoW.  Copy
> > the data from srcmap before we actually write data to the destance
> > iomap.  And we just copy range in which data won't be changed.
> >
> > Another mechanism is range comparison .  In page cache case, readpage()
> > is used to load data on disk to page cache in order to be able to
> > compare data.  In fsdax case, readpage() does not work.  So, we need
> > another compare data with direct access support.
> >
> > With the two mechanism implemented in fsdax, we are able to make reflink
> > and fsdax work together in XFS.
> >
> > Some of the patches are picked up from Goldwyn's patchset.  I made some
> > changes to adapt to this patchset.
>
> How do you deal with HWPoison code trying to reverse-map struct page back
> to inode-offset pair? This also needs to be fixed for reflink to work with
> DAX.

I have posted v3 patchset to add reverse-map support for dax page 
yesterday.  Please take a look at this:

  https://lkml.org/lkml/2021/2/8/347


--
Thanks,
Ruan Shiyang.

> 								Honza
>
> > (Rebased on v5.10)
> > ==
> >
> > Shiyang Ruan (7):
> >    fsdax: Output address in dax_iomap_pfn() and rename it
> >    fsdax: Introduce dax_copy_edges() for CoW
> >    fsdax: Copy data before write
> >    fsdax: Replace mmap entry in case of CoW
> >    fsdax: Dedup file range to use a compare function
> >    fs/xfs: Handle CoW for fsdax write() path
> >    fs/xfs: Add dedupe support for fsdax
> >
> >   fs/btrfs/reflink.c     |   3 +-
> >   fs/dax.c               | 188 ++++++++++++++++++++++++++++++++++++++---
> >   fs/ocfs2/file.c        |   2 +-
> >   fs/remap_range.c       |  14 +--
> >   fs/xfs/xfs_bmap_util.c |   6 +-
> >   fs/xfs/xfs_file.c      |  30 ++++++-
> >   fs/xfs/xfs_inode.c     |   8 +-
> >   fs/xfs/xfs_inode.h     |   1 +
> >   fs/xfs/xfs_iomap.c     |   3 +-
> >   fs/xfs/xfs_iops.c      |  11 ++-
> >   fs/xfs/xfs_reflink.c   |  23 ++++-
> >   include/linux/dax.h    |   5 ++
> >   include/linux/fs.h     |   9 +-
> >   13 files changed, 270 insertions(+), 33 deletions(-)
> >
> > --
> > 2.30.0