iomap: Convert __iomap_zero_iter to use a folio

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>

diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
index 64e54981b651bc17952cc4836cb0b60988865939..9c61d12028cad307042fd0594bed35c06425520d 100644 (file)
--- a/fs/iomap/buffered-io.c
+++ b/fs/iomap/buffered-io.c
@@ -881,17 +881,20 @@ 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);
-       unsigned bytes = min_t(u64, PAGE_SIZE - offset, length);
+       size_t offset, bytes;
 
-       status = iomap_write_begin(iter, pos, bytes, &page);
+       status = iomap_write_begin(iter, pos, length, &page);
        if (status)
                return status;
+       folio = page_folio(page);
 
-       zero_user(page, offset, bytes);
-       mark_page_accessed(page);
+       offset = offset_in_folio(folio, pos);
+       bytes = min_t(u64, folio_size(folio) - offset, length);
+       folio_zero_range(folio, offset, bytes);
+       folio_mark_accessed(folio);
 
        return iomap_write_end(iter, pos, bytes, bytes, page);
 }