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

Jan Kara
2021-02-08T15:39:18Z

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.

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