linux-kernel - [PATCH 0/6] shmem: high order folios support in write path

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Date:   Fri, 15 Sep 2023 09:51:21 +0000
From:   Daniel Gomez <da.gomez@...sung.com>
To:     "minchan@...nel.org" <minchan@...nel.org>,
        "senozhatsky@...omium.org" <senozhatsky@...omium.org>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "djwong@...nel.org" <djwong@...nel.org>,
        "willy@...radead.org" <willy@...radead.org>,
        "hughd@...gle.com" <hughd@...gle.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "mcgrof@...nel.org" <mcgrof@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-xfs@...r.kernel.org" <linux-xfs@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
CC:     "gost.dev@...sung.com" <gost.dev@...sung.com>,
        Pankaj Raghav <p.raghav@...sung.com>,
        Daniel Gomez <da.gomez@...sung.com>
Subject: [PATCH 0/6] shmem: high order folios support in write path

This series add support for high order folios in shmem write
path.

This is a continuation of the shmem work from Luis here [1]
following Matthew Wilcox's suggestion [2] regarding the path to take
for the folio allocation order calculation.

[1] RFC v2 add support for blocksize > PAGE_SIZE
https://lore.kernel.org/all/ZHBowMEDfyrAAOWH@bombadil.infradead.org/T/#md3e93ab46ce2ad9254e1eb54ffe71211988b5632
[2] https://lore.kernel.org/all/ZHD9zmIeNXICDaRJ@casper.infradead.org/

Patches have been tested and sent from next-230911. They do apply
cleanly to the latest next-230914.

fsx and fstests has been performed on tmpfs with noswap with the
following results:
- fsx: 2d test, 21,5B
- fstests: Same result as baseline for next-230911 [3][4][5]

[3] Baseline next-230911 failures are: generic/080 generic/126
generic/193 generic/633 generic/689
[4] fstests logs baseline: https://gitlab.com/-/snippets/3598621
[5] fstests logs patches: https://gitlab.com/-/snippets/3598628

There are at least 2 cases/topics to handle that I'd appreciate
feedback.
1. With the new strategy, you might end up with a folio order matching
HPAGE_PMD_ORDER. However, we won't respect the 'huge' flag anymore if
THP is enabled.
2. When the above (1.) occurs, the code skips the huge path, so
xa_find with hindex is skipped.

Daniel

Daniel Gomez (5):
  filemap: make the folio order calculation shareable
  shmem: drop BLOCKS_PER_PAGE macro
  shmem: add order parameter support to shmem_alloc_folio
  shmem: add file length in shmem_get_folio path
  shmem: add large folios support to the write path

Luis Chamberlain (1):
  shmem: account for large order folios

 fs/iomap/buffered-io.c   |  6 ++-
 include/linux/pagemap.h  | 42 ++++++++++++++++---
 include/linux/shmem_fs.h |  2 +-
 mm/filemap.c             |  8 ----
 mm/khugepaged.c          |  2 +-
 mm/shmem.c               | 91 +++++++++++++++++++++++++---------------
 6 files changed, 100 insertions(+), 51 deletions(-)

--
2.39.2