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. (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
