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    Subject[PATCH v2 01/12] mm: Make pagecache tagged lookups return only head pages
    Date
    Pagecache tags are used for dirty page writeback.  Since dirtiness is
    tracked on a per-THP basis, we only want to return the head page rather
    than each subpage of a tagged page. All the filesystems which use huge
    pages today are in-memory, so there are no tagged huge pages today.

    Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
    ---
    mm/filemap.c | 10 +++++-----
    1 file changed, 5 insertions(+), 5 deletions(-)

    diff --git a/mm/filemap.c b/mm/filemap.c
    index f5fda3038782..7d8cf1a25628 100644
    --- a/mm/filemap.c
    +++ b/mm/filemap.c
    @@ -1968,7 +1968,7 @@ unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
    EXPORT_SYMBOL(find_get_pages_contig);

    /**
    - * find_get_pages_range_tag - find and return pages in given range matching @tag
    + * find_get_pages_range_tag - Find and return head pages matching @tag.
    * @mapping: the address_space to search
    * @index: the starting page index
    * @end: The final page index (inclusive)
    @@ -1976,8 +1976,8 @@ EXPORT_SYMBOL(find_get_pages_contig);
    * @nr_pages: the maximum number of pages
    * @pages: where the resulting pages are placed
    *
    - * Like find_get_pages, except we only return pages which are tagged with
    - * @tag. We update @index to index the next page for the traversal.
    + * Like find_get_pages(), except we only return head pages which are tagged
    + * with @tag. We update @index to index the next page for the traversal.
    *
    * Return: the number of pages which were found.
    */
    @@ -2011,9 +2011,9 @@ unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
    if (unlikely(page != xas_reload(&xas)))
    goto put_page;

    - pages[ret] = find_subpage(page, xas.xa_index);
    + pages[ret] = page;
    if (++ret == nr_pages) {
    - *index = xas.xa_index + 1;
    + *index = page->index + thp_nr_pages(page);
    goto out;
    }
    continue;
    --
    2.28.0
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