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    Subject[PATCH v3 16/25] iomap: Convert __iomap_zero_iter to use a folio
    Date
    The zero iterator can work in folio-sized chunks instead of page-sized
    chunks. This will save a lot of page cache lookups if the file is cached
    in large folios.

    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    Reviewed-by: Christoph Hellwig <hch@lst.de>
    Reviewed-by: Darrick J. Wong <djwong@kernel.org>
    ---
    fs/iomap/buffered-io.c | 14 +++++++++-----
    1 file changed, 9 insertions(+), 5 deletions(-)

    diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
    index b1ded5204d1c..47cf558244f4 100644
    --- a/fs/iomap/buffered-io.c
    +++ b/fs/iomap/buffered-io.c
    @@ -893,19 +893,23 @@ EXPORT_SYMBOL_GPL(iomap_file_unshare);

    static s64 __iomap_zero_iter(struct iomap_iter *iter, loff_t pos, u64 length)
    {
    + struct folio *folio;
    struct page *page;
    int status;
    - unsigned offset = offset_in_page(pos);
    + size_t offset;
    unsigned bytes = min_t(u64, UINT_MAX, length);

    status = iomap_write_begin(iter, pos, bytes, &page);
    if (status)
    return status;
    - if (bytes > PAGE_SIZE - offset)
    - bytes = PAGE_SIZE - offset;
    + folio = page_folio(page);
    +
    + offset = offset_in_folio(folio, pos);
    + if (bytes > folio_size(folio) - offset)
    + bytes = folio_size(folio) - offset;

    - zero_user(page, offset, bytes);
    - mark_page_accessed(page);
    + folio_zero_range(folio, offset, bytes);
    + folio_mark_accessed(folio);

    return iomap_write_end(iter, pos, bytes, bytes, page);
    }
    --
    2.33.0
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