Re: [PATCH 0/2] Use multi-index entries in the page cache

[William Kucharski <william.kucharski@oracle.com>]

Another nice cleanup.

For the series:

Reviewed-by: William Kucharski <william.kucharski@oracle.com>

> On Jun 29, 2020, at 9:20 AM, Matthew Wilcox (Oracle) <willy@infradead.org> wrote:
> 
> Following Hugh's advice at LSFMM 2019, I was trying to avoid doing this,
> but it turns out to be hard to support range writeback with the pagecache
> using multiple single entries.  Of course, this isn't a problem for
> shmem because it doesn't have a real backing device (only swap), but
> real filesystems need to start writeback at arbitrary file offsets and
> have problems if we don't notice that the first (huge) page in the range
> is dirty.
> 
> Hugh, I would love it if you could test this.  It didn't introduce any new
> regressions to the xfstests, but shmem does exercise different paths and
> of course I don't have a clean xfstests run yet, so there could easily
> still be bugs.
> 
> I'd like this to be included in mmotm, but it is less urgent than the
> previous patch series that I've sent.  As far as risk, I think it only
> affects shmem/tmpfs.
> 
> Matthew Wilcox (Oracle) (2):
>  XArray: Add xas_split
>  mm: Use multi-index entries in the page cache
> 
> Documentation/core-api/xarray.rst |  16 ++--
> include/linux/xarray.h            |   2 +
> lib/test_xarray.c                 |  41 ++++++++
> lib/xarray.c                      | 153 ++++++++++++++++++++++++++++--
> mm/filemap.c                      |  42 ++++----
> mm/huge_memory.c                  |  21 +++-
> mm/khugepaged.c                   |  12 ++-
> mm/shmem.c                        |  11 +--
> 8 files changed, 245 insertions(+), 53 deletions(-)
> 
> -- 
> 2.27.0
> 
>