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

Ruan Shiyang
2021-02-09T01:51:13Z

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
>>
>>
>>