[RFC PATCH 09/15] virtio: virtio_mem: use PAGES_PER_SECTION instead of MAX_ORDER_NR_PAGES

[Zi Yan]

From: Zi Yan <ziy@xxxxxxxxxx>

It keeps the existing behavior when MAX_ORDER grows beyond a section
size.

Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Cc: Jason Wang <jasowang@xxxxxxxxxx>
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
 drivers/virtio/virtio_mem.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 19036922f7ef..bab5a81fa796 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -1105,11 +1105,11 @@ static void virtio_mem_clear_fake_offline(unsigned long pfn,
  */
 static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
 {
-	const unsigned long max_nr_pages = MAX_ORDER_NR_PAGES;
+	const unsigned long max_nr_pages = PAGES_PER_SECTION;
 	unsigned long i;
 
 	/*
-	 * We are always called at least with MAX_ORDER_NR_PAGES
+	 * We are always called at least with PAGES_PER_SECTION
 	 * granularity/alignment (e.g., the way subblocks work). All pages
 	 * inside such a block are alike.
 	 */
@@ -1125,7 +1125,7 @@ static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
 		if (PageDirty(page)) {
 			virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
 						      false);
-			generic_online_page(page, MAX_ORDER - 1);
+			generic_online_page(page, PAGES_PER_SECTION - 1);
 		} else {
 			virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
 						      true);
@@ -1228,7 +1228,7 @@ static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
 		if (vm->in_sbm) {
 			/*
 			 * We exploit here that subblocks have at least
-			 * MAX_ORDER_NR_PAGES size/alignment - so we cannot
+			 * PAGES_PER_SECTION size/alignment - so we cannot
 			 * cross subblocks within one call.
 			 */
 			id = virtio_mem_phys_to_mb_id(addr);
@@ -2438,14 +2438,14 @@ static int virtio_mem_init(struct virtio_mem *vm)
 				      VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);
 
 	/*
-	 * We want subblocks to span at least MAX_ORDER_NR_PAGES and
+	 * We want subblocks to span at least PAGES_PER_SECTION and
 	 * pageblock_nr_pages pages. This:
 	 * - Simplifies our page onlining code (virtio_mem_online_page_cb)
 	 *   and fake page onlining code (virtio_mem_fake_online).
 	 * - Is required for now for alloc_contig_range() to work reliably -
 	 *   it doesn't properly handle smaller granularity on ZONE_NORMAL.
 	 */
-	sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
+	sb_size = max_t(uint64_t, PAGES_PER_SECTION,
 			pageblock_nr_pages) * PAGE_SIZE;
 	sb_size = max_t(uint64_t, vm->device_block_size, sb_size);
 
-- 
2.30.2