This series add support for high order folios in shmem write path when swap is disabled (noswap option). This is part of the Large Block Size (LBS) effort [1][2] and a continuation of the shmem work from Luis here [3] following Matthew Wilcox's suggestion [4] regarding the path to take for the folio allocation order calculation. [1] https://kernelnewbies.org/KernelProjects/large-block-size [2] https://docs.google.com/spreadsheets/d/e/2PACX-1vS7sQfw90S00l2rfOKm83Jlg0px8KxMQE4HHp_DKRGbAGcAV-xu6LITHBEc4xzVh9wLH6WM2lR0cZS8/pubhtml# [3] RFC v2 add support for blocksize > PAGE_SIZE https://lore.kernel.org/all/ZHBowMEDfyrAAOWH@xxxxxxxxxxxxxxxxxxxxxx/T/#md3e93ab46ce2ad9254e1eb54ffe71211988b5632 [4] https://lore.kernel.org/all/ZHD9zmIeNXICDaRJ@xxxxxxxxxxxxxxxxxxxx/ fsx and fstests has been performed on tmpfs with noswap with the following results: V2: - fsx: 4,9B - fstests: Same result as baseline for next-230918. V1: - fsx: 2d test, 21,5B - fstests: Same result as baseline for next-230911 [3][4][5] Patches have been tested and sent from next-230918. [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 Note: because of next-230918 regression in rmap, patch [8] applied. [8] 20230918151729.5A1F4C32796@xxxxxxxxxxxxxxx Daniel Changes since v1 * Order handling code simplified in shmem_get_folio_gfp after Matthew Willcox's review. * Drop patch 1/6 [6] and merge mapping_size_order code directly in shmem. * Added MAX_SHMEM_ORDER to make it explicit we don't have the same max order as in pagecache (MAX_PAGECACHE_ORDER). * Use HPAGE_PMD_ORDER-1 as MAX_SHMEM_ORDER to respect huge mount option. * Update cover letter: drop huge strategy question and add more context regarding LBS project. Add fsx and fstests summary with new baseline. * Add fixes found by Matthew in patch 3/6 [7]. * Fix length (i_size_read -> PAGE_SIZE) that is passed to shmem_get_folio_gfp in shmem_fault and shmem_read_folio_gfp to PAGE_SIZE. * Add patch as suggested by Matthew to return the number of pages freed in shmem_free_swap (instead of errno). When no pages are freed, return 0 (pages). Note: As an alternative, we can embed -ENOENT and make use of IS_ERR_VALUE. Approach discarded because little value was added. If this method is preferred, please let discuss it. [6] filemap: make the folio order calculation shareable [7] shmem: account for large order folios Daniel Gomez (5): shmem: drop BLOCKS_PER_PAGE macro shmem: return freed pages in shmem_free_swap 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 include/linux/shmem_fs.h | 2 +- mm/khugepaged.c | 2 +- mm/shmem.c | 141 ++++++++++++++++++++++++++------------- 3 files changed, 97 insertions(+), 48 deletions(-) -- 2.39.2
