1 files changed, 62 insertions, 6 deletions

diff --git a/mm/page_io.c b/mm/page_io.c
index 77fa0fb263f4..2724d6389104 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -235,6 +235,25 @@ static void bio_associate_blkg_from_page(struct bio *bio, struct page *page)
 #define bio_associate_blkg_from_page(bio, page)		do { } while (0)
 #endif /* CONFIG_MEMCG && CONFIG_BLK_CGROUP */
 
+struct swap_iocb {
+	struct kiocb		iocb;
+	struct bio_vec		bvec;
+};
+static mempool_t *sio_pool;
+
+int sio_pool_init(void)
+{
+	if (!sio_pool) {
+		mempool_t *pool = mempool_create_kmalloc_pool(
+			SWAP_CLUSTER_MAX, sizeof(struct swap_iocb));
+		if (cmpxchg(&sio_pool, NULL, pool))
+			mempool_destroy(pool);
+	}
+	if (!sio_pool)
+		return -ENOMEM;
+	return 0;
+}
+
 int __swap_writepage(struct page *page, struct writeback_control *wbc,
 		bio_end_io_t end_write_func)
 {
@@ -306,6 +325,48 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
 	return 0;
 }
 
+static void sio_read_complete(struct kiocb *iocb, long ret)
+{
+	struct swap_iocb *sio = container_of(iocb, struct swap_iocb, iocb);
+	struct page *page = sio->bvec.bv_page;
+
+	if (ret != 0 && ret != PAGE_SIZE) {
+		SetPageError(page);
+		ClearPageUptodate(page);
+		pr_alert_ratelimited("Read-error on swap-device\n");
+	} else {
+		SetPageUptodate(page);
+		count_vm_event(PSWPIN);
+	}
+	unlock_page(page);
+	mempool_free(sio, sio_pool);
+}
+
+static int swap_readpage_fs(struct page *page)
+{
+	struct swap_info_struct *sis = page_swap_info(page);
+	struct file *swap_file = sis->swap_file;
+	struct address_space *mapping = swap_file->f_mapping;
+	struct iov_iter from;
+	struct swap_iocb *sio;
+	loff_t pos = page_file_offset(page);
+	int ret;
+
+	sio = mempool_alloc(sio_pool, GFP_KERNEL);
+	init_sync_kiocb(&sio->iocb, swap_file);
+	sio->iocb.ki_pos = pos;
+	sio->iocb.ki_complete = sio_read_complete;
+	sio->bvec.bv_page = page;
+	sio->bvec.bv_len = PAGE_SIZE;
+	sio->bvec.bv_offset = 0;
+
+	iov_iter_bvec(&from, READ, &sio->bvec, 1, PAGE_SIZE);
+	ret = mapping->a_ops->swap_rw(&sio->iocb, &from);
+	if (ret != -EIOCBQUEUED)
+		sio_read_complete(&sio->iocb, ret);
+	return ret;
+}
+
 int swap_readpage(struct page *page, bool synchronous)
 {
 	struct bio *bio;
@@ -334,12 +395,7 @@ int swap_readpage(struct page *page, bool synchronous)
 	}
 
 	if (data_race(sis->flags & SWP_FS_OPS)) {
-		struct file *swap_file = sis->swap_file;
-		struct address_space *mapping = swap_file->f_mapping;
-
-		ret = mapping->a_ops->readpage(swap_file, page);
-		if (!ret)
-			count_vm_event(PSWPIN);
+		ret = swap_readpage_fs(page);
 		goto out;
 	}