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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>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-11-05 14:24:09 -04:00
parent d454ab82bc
commit a25def1fe5
1 changed files with 9 additions and 5 deletions
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14
fs/iomap/buffered-io.c
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@ -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);
zero_user(page, offset, bytes);
mark_page_accessed(page);
offset = offset_in_folio(folio, pos);
if (bytes > folio_size(folio) - offset)
bytes = folio_size(folio) - offset;
folio_zero_range(folio, offset, bytes);
folio_mark_accessed(folio);
return iomap_write_end(iter, pos, bytes, bytes, page);
}