From: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Add a helper to allow filesystems to attempt to free the 'dropbehind' folio. Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/all/5588a06f6d5a2cf6746828e2d36e7ada668b1739.1745381692.git.trond.myklebust@xxxxxxxxxxxxxxx/ Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- include/linux/pagemap.h | 1 + mm/filemap.c | 16 ++++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 12a12dae727d..201b7c6f6441 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1221,6 +1221,7 @@ void folio_wait_writeback(struct folio *folio); int folio_wait_writeback_killable(struct folio *folio); void end_page_writeback(struct page *page); void folio_end_writeback(struct folio *folio); +void folio_end_dropbehind(struct folio *folio); void folio_wait_stable(struct folio *folio); void __folio_mark_dirty(struct folio *folio, struct address_space *, int warn); void folio_account_cleaned(struct folio *folio, struct bdi_writeback *wb); diff --git a/mm/filemap.c b/mm/filemap.c index 751838ef05e5..9878ab702e54 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1603,6 +1603,22 @@ static void filemap_end_dropbehind(struct folio *folio) folio_unmap_invalidate(mapping, folio, 0); } +/* + * Helper for filesystems that want to implement dropbehind, and that + * need to keep the folio around after folio_end_writeback, e.g. due to + * the need to first commit NFS stable writes. + */ +void folio_end_dropbehind(struct folio *folio) +{ + if (folio_trylock(folio)) { + if (folio->mapping && !folio_test_dirty(folio) && + !folio_test_writeback(folio)) + folio_unmap_invalidate(folio->mapping, folio, 0); + folio_unlock(folio); + } +} +EXPORT_SYMBOL(folio_end_dropbehind); + /* * If folio was marked as dropbehind, then pages should be dropped when writeback * completes. Do that now. If we fail, it's likely because of a big folio - -- 2.50.1
