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
