From dd6bd0d9c7dbb3951005db4e424abbd37c4ff801 Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Wed, 4 Jun 2014 16:07:48 -0700 Subject: [PATCH] swap: use bdev_read_page() / bdev_write_page() By calling the device driver to write the page directly, we avoid allocating a BIO, which allows us to free memory without allocating memory. [akpm@linux-foundation.org: fix used-uninitialized bug] Signed-off-by: Matthew Wilcox Cc: Dave Chinner Cc: Dheeraj Reddy Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_io.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/mm/page_io.c b/mm/page_io.c index 7c59ef681381..58b50d2901fe 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -248,11 +248,16 @@ int swap_writepage(struct page *page, struct writeback_control *wbc) return ret; } +static sector_t swap_page_sector(struct page *page) +{ + return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9); +} + int __swap_writepage(struct page *page, struct writeback_control *wbc, void (*end_write_func)(struct bio *, int)) { struct bio *bio; - int ret = 0, rw = WRITE; + int ret, rw = WRITE; struct swap_info_struct *sis = page_swap_info(page); if (sis->flags & SWP_FILE) { @@ -297,6 +302,13 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc, return ret; } + ret = bdev_write_page(sis->bdev, swap_page_sector(page), page, wbc); + if (!ret) { + count_vm_event(PSWPOUT); + return 0; + } + + ret = 0; bio = get_swap_bio(GFP_NOIO, page, end_write_func); if (bio == NULL) { set_page_dirty(page); @@ -338,6 +350,13 @@ int swap_readpage(struct page *page) return ret; } + ret = bdev_read_page(sis->bdev, swap_page_sector(page), page); + if (!ret) { + count_vm_event(PSWPIN); + return 0; + } + + ret = 0; bio = get_swap_bio(GFP_KERNEL, page, end_swap_bio_read); if (bio == NULL) { unlock_page(page);