Commit 4601e2fc authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

shmem: convert shmem_file_read_iter() to use shmem_get_folio() 

Use a folio throughout, saving five calls to compound_head().

Link: https://lkml.kernel.org/r/20220902194653.1739778-28-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent eff1f906

mm/shmem.c

+11 −9
Original line number Diff line number Diff line
@@ -2577,6 +2577,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
	offset = *ppos & ~PAGE_MASK;



	for (;;) {

		struct folio *folio = NULL;

		struct page *page = NULL;

		pgoff_t end_index;

		unsigned long nr, ret;
@@ -2591,17 +2592,18 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
				break;

		}



		error = shmem_getpage(inode, index, &page, SGP_READ);

		error = shmem_get_folio(inode, index, &folio, SGP_READ);

		if (error) {

			if (error == -EINVAL)

				error = 0;

			break;

		}

		if (page) {

			unlock_page(page);

		if (folio) {

			folio_unlock(folio);



			page = folio_file_page(folio, index);

			if (PageHWPoison(page)) {

				put_page(page);

				folio_put(folio);

				error = -EIO;

				break;

			}
@@ -2617,14 +2619,14 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
		if (index == end_index) {

			nr = i_size & ~PAGE_MASK;

			if (nr <= offset) {

				if (page)

					put_page(page);

				if (folio)

					folio_put(folio);

				break;

			}

		}

		nr -= offset;



		if (page) {

		if (folio) {

			/*

			 * If users can be writing to this page using arbitrary

			 * virtual addresses, take care about potential aliasing
@@ -2636,13 +2638,13 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to) 
			 * Mark the page accessed if we read the beginning.

			 */

			if (!offset)

				mark_page_accessed(page);

				folio_mark_accessed(folio);

			/*

			 * Ok, we have the page, and it's up-to-date, so

			 * now we can copy it to user space...

			 */

			ret = copy_page_to_iter(page, offset, nr, to);

			put_page(page);

			folio_put(folio);



		} else if (user_backed_iter(to)) {

			/*