Commit 5d8edfb9 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

iomap: Copy larger chunks from userspace 



If we have a large folio, we can copy in larger chunks than PAGE_SIZE.
Start at the maximum page cache size and shrink by half every time we
hit the "we are short on memory" problem.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
parent d6bb59a9

fs/iomap/buffered-io.c

+17 −15
Original line number Diff line number Diff line
@@ -769,6 +769,7 @@ static size_t iomap_write_end(struct iomap_iter *iter, loff_t pos, size_t len, 
static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i)

{

	loff_t length = iomap_length(iter);

	size_t chunk = PAGE_SIZE << MAX_PAGECACHE_ORDER;

	loff_t pos = iter->pos;

	ssize_t written = 0;

	long status = 0;
@@ -777,15 +778,12 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 


	do {

		struct folio *folio;

		struct page *page;

		unsigned long offset;	/* Offset into pagecache page */

		unsigned long bytes;	/* Bytes to write to page */

		size_t offset;		/* Offset into folio */

		size_t bytes;		/* Bytes to write to folio */

		size_t copied;		/* Bytes copied from user */



		offset = offset_in_page(pos);

		bytes = min_t(unsigned long, PAGE_SIZE - offset,

						iov_iter_count(i));

again:

		offset = pos & (chunk - 1);

		bytes = min(chunk - offset, iov_iter_count(i));

		status = balance_dirty_pages_ratelimited_flags(mapping,

							       bdp_flags);

		if (unlikely(status))
@@ -815,12 +813,14 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 
		if (iter->iomap.flags & IOMAP_F_STALE)

			break;



		page = folio_file_page(folio, pos >> PAGE_SHIFT);

		if (mapping_writably_mapped(mapping))

			flush_dcache_page(page);

		offset = offset_in_folio(folio, pos);

		if (bytes > folio_size(folio) - offset)

			bytes = folio_size(folio) - offset;



		copied = copy_page_from_iter_atomic(page, offset, bytes, i);

		if (mapping_writably_mapped(mapping))

			flush_dcache_folio(folio);



		copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);

		status = iomap_write_end(iter, pos, bytes, copied, folio);



		if (unlikely(copied != status))
@@ -836,11 +836,13 @@ static loff_t iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i) 
			 */

			if (copied)

				bytes = copied;

			goto again;

		}

			if (chunk > PAGE_SIZE)

				chunk /= 2;

		} else {

			pos += status;

			written += status;

			length -= status;

		}

	} while (iov_iter_count(i) && length);



	if (status == -EAGAIN) {