RE: [PATCH v5 0/7] fsdax,xfs: Add reflink&dedupe support for fsdax

-----Original Message----- From: Darrick J. Wong <djwong(a)kernel.org&gt; Sent: Tuesday, May 11, 2021 11:57 AM Subject: Re: [PATCH v5 0/7] fsdax,xfs: Add reflink&dedupe support for fsdax On Tue, May 11, 2021 at 11:09:26AM +0800, 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. Slightly off topic, but I noticed all my pmem disappeared once I rolled forward to 5.13-rc1. Am I the only lucky one? Qemu 4.2, with fake memory devices backed by tmpfs files -- info qtree says they're there, but the kernel doesn't show anything in /proc/iomem.

--D > Changes from V4: > - Fix the mistake of breaking dax layout for two inodes > - Add CONFIG_FS_DAX judgement for fsdax code in remap_range.c > - Fix other small problems and mistakes > > Changes from V3: > - Take out the first 3 patches as a cleanup patchset[1], which has been > sent yesterday. > - Fix usage of code in dax_iomap_cow_copy() > - Add comments for macro definitions > - Fix other code style problems and mistakes > > 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 mechanisms 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 v5.13-rc1 and patchset[1]) > [1]: https://lkml.org/lkml/2021/4/22/575 > > Shiyang Ruan (7): > fsdax: Introduce dax_iomap_cow_copy() > fsdax: Replace mmap entry in case of CoW > fsdax: Add dax_iomap_cow_copy() for dax_iomap_zero > iomap: Introduce iomap_apply2() for operations on two files > fsdax: Dedup file range to use a compare function > fs/xfs: Handle CoW for fsdax write() path > fs/xfs: Add dax dedupe support > > fs/dax.c | 206 +++++++++++++++++++++++++++++++++++------ > fs/iomap/apply.c | 52 +++++++++++ > fs/iomap/buffered-io.c | 2 +- > fs/remap_range.c | 57 ++++++++++-- > fs/xfs/xfs_bmap_util.c | 3 +- > fs/xfs/xfs_file.c | 11 +-- > fs/xfs/xfs_inode.c | 66 ++++++++++++- > fs/xfs/xfs_inode.h | 1 + > fs/xfs/xfs_iomap.c | 61 +++++++++++- > fs/xfs/xfs_iomap.h | 4 + > fs/xfs/xfs_iops.c | 7 +- > fs/xfs/xfs_reflink.c | 15 +-- > include/linux/dax.h | 7 +- > include/linux/fs.h | 12 ++- > include/linux/iomap.h | 7 +- > 15 files changed, 449 insertions(+), 62 deletions(-) > > -- > 2.31.1 > > >