1 files changed, 64 insertions, 53 deletions

diff --git a/mm/page_io.c b/mm/page_io.c
index b995a5ba5..985f23cfa 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -56,31 +56,20 @@ void end_swap_bio_write(struct bio *bio)
 		 * Also clear PG_reclaim to avoid rotate_reclaimable_page()
 		 */
 		set_page_dirty(page);
-		printk(KERN_ALERT "Write-error on swap-device (%u:%u:%Lu)\n",
-				imajor(bio->bi_bdev->bd_inode),
-				iminor(bio->bi_bdev->bd_inode),
-				(unsigned long long)bio->bi_iter.bi_sector);
+		pr_alert("Write-error on swap-device (%u:%u:%llu)\n",
+			 imajor(bio->bi_bdev->bd_inode),
+			 iminor(bio->bi_bdev->bd_inode),
+			 (unsigned long long)bio->bi_iter.bi_sector);
 		ClearPageReclaim(page);
 	}
 	end_page_writeback(page);
 	bio_put(bio);
 }
 
-static void end_swap_bio_read(struct bio *bio)
+static void swap_slot_free_notify(struct page *page)
 {
-	struct page *page = bio->bi_io_vec[0].bv_page;
-
-	if (bio->bi_error) {
-		SetPageError(page);
-		ClearPageUptodate(page);
-		printk(KERN_ALERT "Read-error on swap-device (%u:%u:%Lu)\n",
-				imajor(bio->bi_bdev->bd_inode),
-				iminor(bio->bi_bdev->bd_inode),
-				(unsigned long long)bio->bi_iter.bi_sector);
-		goto out;
-	}
-
-	SetPageUptodate(page);
+	struct swap_info_struct *sis;
+	struct gendisk *disk;
 
 	/*
 	 * There is no guarantee that the page is in swap cache - the software
@@ -88,42 +77,59 @@ static void end_swap_bio_read(struct bio *bio)
 	 * swapcache page.  So we must check PG_swapcache before proceeding with
 	 * this optimization.
 	 */
-	if (likely(PageSwapCache(page))) {
-		struct swap_info_struct *sis;
+	if (unlikely(!PageSwapCache(page)))
+		return;
 
-		sis = page_swap_info(page);
-		if (sis->flags & SWP_BLKDEV) {
-			/*
-			 * The swap subsystem performs lazy swap slot freeing,
-			 * expecting that the page will be swapped out again.
-			 * So we can avoid an unnecessary write if the page
-			 * isn't redirtied.
-			 * This is good for real swap storage because we can
-			 * reduce unnecessary I/O and enhance wear-leveling
-			 * if an SSD is used as the as swap device.
-			 * But if in-memory swap device (eg zram) is used,
-			 * this causes a duplicated copy between uncompressed
-			 * data in VM-owned memory and compressed data in
-			 * zram-owned memory.  So let's free zram-owned memory
-			 * and make the VM-owned decompressed page *dirty*,
-			 * so the page should be swapped out somewhere again if
-			 * we again wish to reclaim it.
-			 */
-			struct gendisk *disk = sis->bdev->bd_disk;
-			if (disk->fops->swap_slot_free_notify) {
-				swp_entry_t entry;
-				unsigned long offset;
+	sis = page_swap_info(page);
+	if (!(sis->flags & SWP_BLKDEV))
+		return;
 
-				entry.val = page_private(page);
-				offset = swp_offset(entry);
+	/*
+	 * The swap subsystem performs lazy swap slot freeing,
+	 * expecting that the page will be swapped out again.
+	 * So we can avoid an unnecessary write if the page
+	 * isn't redirtied.
+	 * This is good for real swap storage because we can
+	 * reduce unnecessary I/O and enhance wear-leveling
+	 * if an SSD is used as the as swap device.
+	 * But if in-memory swap device (eg zram) is used,
+	 * this causes a duplicated copy between uncompressed
+	 * data in VM-owned memory and compressed data in
+	 * zram-owned memory.  So let's free zram-owned memory
+	 * and make the VM-owned decompressed page *dirty*,
+	 * so the page should be swapped out somewhere again if
+	 * we again wish to reclaim it.
+	 */
+	disk = sis->bdev->bd_disk;
+	if (disk->fops->swap_slot_free_notify) {
+		swp_entry_t entry;
+		unsigned long offset;
 
-				SetPageDirty(page);
-				disk->fops->swap_slot_free_notify(sis->bdev,
-						offset);
-			}
-		}
+		entry.val = page_private(page);
+		offset = swp_offset(entry);
+
+		SetPageDirty(page);
+		disk->fops->swap_slot_free_notify(sis->bdev,
+				offset);
 	}
+}
+
+static void end_swap_bio_read(struct bio *bio)
+{
+	struct page *page = bio->bi_io_vec[0].bv_page;
 
+	if (bio->bi_error) {
+		SetPageError(page);
+		ClearPageUptodate(page);
+		pr_alert("Read-error on swap-device (%u:%u:%llu)\n",
+			 imajor(bio->bi_bdev->bd_inode),
+			 iminor(bio->bi_bdev->bd_inode),
+			 (unsigned long long)bio->bi_iter.bi_sector);
+		goto out;
+	}
+
+	SetPageUptodate(page);
+	swap_slot_free_notify(page);
 out:
 	unlock_page(page);
 	bio_put(bio);
@@ -216,7 +222,7 @@ reprobe:
 out:
 	return ret;
 bad_bmap:
-	printk(KERN_ERR "swapon: swapfile has holes\n");
+	pr_err("swapon: swapfile has holes\n");
 	ret = -EINVAL;
 	goto out;
 }
@@ -246,7 +252,7 @@ out:
 
 static sector_t swap_page_sector(struct page *page)
 {
-	return (sector_t)__page_file_index(page) << (PAGE_CACHE_SHIFT - 9);
+	return (sector_t)__page_file_index(page) << (PAGE_SHIFT - 9);
 }
 
 int __swap_writepage(struct page *page, struct writeback_control *wbc,
@@ -290,8 +296,8 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
 			 */
 			set_page_dirty(page);
 			ClearPageReclaim(page);
-			pr_err_ratelimited("Write error on dio swapfile (%Lu)\n",
-				page_file_offset(page));
+			pr_err_ratelimited("Write error on dio swapfile (%llu)\n",
+					   page_file_offset(page));
 		}
 		end_page_writeback(page);
 		return ret;
@@ -347,6 +353,11 @@ int swap_readpage(struct page *page)
 
 	ret = bdev_read_page(sis->bdev, swap_page_sector(page), page);
 	if (!ret) {
+		if (trylock_page(page)) {
+			swap_slot_free_notify(page);
+			unlock_page(page);
+		}
+
 		count_vm_event(PSWPIN);
 		return 0;
 	}