Commit 75c34cab authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Liu Shixin
Browse files

filemap: Convert generic_perform_write() to support large folios 

mainline inclusion
from mainline-v6.11-rc1
commit 9aac777aaf9459786bc8463e6cbfc7e7e1abd1f9
category: performance
bugzilla: https://gitee.com/openeuler/kernel/issues/IAHY3K

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9aac777aaf9459786bc8463e6cbfc7e7e1abd1f9



--------------------------------

Modelled after the loop in iomap_write_iter(), copy larger chunks from
userspace if the filesystem has created large folios.

[hch: use mapping_max_folio_size to keep supporting file systems that do
 not support large folios]

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Tested-by: default avatarShaun Tancheff <shaun.tancheff@hpe.com>
Tested-by: default avatarSagi Grimberg <sagi@grimberg.me>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: default avatarLiu Shixin <liushixin2@huawei.com>
parent 20b40e9c

mm/filemap.c

+25 −15
Original line number Diff line number Diff line
@@ -4038,21 +4038,24 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) 
	loff_t pos = iocb->ki_pos;

	struct address_space *mapping = file->f_mapping;

	const struct address_space_operations *a_ops = mapping->a_ops;

	size_t chunk = mapping_max_folio_size(mapping);

	long status = 0;

	ssize_t written = 0;



	do {

		struct page *page;

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

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

		struct folio *folio;

		size_t offset;		/* Offset into folio */

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

		size_t copied;		/* Bytes copied from user */

		void *fsdata = NULL;



		offset = (pos & (PAGE_SIZE - 1));

		bytes = min_t(unsigned long, PAGE_SIZE - offset,

						iov_iter_count(i));

		bytes = iov_iter_count(i);

retry:

		offset = pos & (chunk - 1);

		bytes = min(chunk - offset, bytes);

		balance_dirty_pages_ratelimited(mapping);



again:

		/*

		 * Bring in the user page that we will copy from _first_.

		 * Otherwise there's a nasty deadlock on copying from the
@@ -4074,11 +4077,16 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) 
		if (unlikely(status < 0))

			break;



		folio = page_folio(page);

		offset = offset_in_folio(folio, pos);

		if (bytes > folio_size(folio) - offset)

			bytes = folio_size(folio) - offset;



		if (mapping_writably_mapped(mapping))

			flush_dcache_page(page);

			flush_dcache_folio(folio);



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

		flush_dcache_page(page);

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

		flush_dcache_folio(folio);



		status = a_ops->write_end(file, mapping, pos, bytes, copied,

						page, fsdata);
@@ -4096,14 +4104,16 @@ ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i) 
			 * halfway through, might be a race with munmap,

			 * might be severe memory pressure.

			 */

			if (copied)

			if (chunk > PAGE_SIZE)

				chunk /= 2;

			if (copied) {

				bytes = copied;

			goto again;

				goto retry;

			}

		} else {

			pos += status;

			written += status;



		balance_dirty_pages_ratelimited(mapping);

		}

	} while (iov_iter_count(i));



	if (!written)