Patch "fs/mpage.c: fix mpage_writepage() for pages with buffers" has been added to the 4.9-stable tree

@@ -450,10 +450,12 @@ int bdev_write_page(struct block_device
 
 	set_page_writeback(page);
 	result = ops->rw_page(bdev, sector + get_start_sect(bdev), page, true);
-	if (result)
+	if (result) {
 		end_page_writeback(page);
-	else
+	} else {
+		clean_page_buffers(page);
 		unlock_page(page);
+	}
 	blk_queue_exit(bdev->bd_queue);
 	return result;
 }

@@ -466,6 +466,16 @@ static void clean_buffers(struct page *p
 		try_to_free_buffers(page);
 }
 
+/*
+ * For situations where we want to clean all buffers attached to a page.
+ * We don't need to calculate how many buffers are attached to the page,
+ * we just need to specify a number larger than the maximum number of buffers.
+ */
+void clean_page_buffers(struct page *page)
+{
+	clean_buffers(page, ~0U);
+}
+
 static int __mpage_writepage(struct page *page, struct writeback_control *wbc,
 		      void *data)
 {

@@ -604,10 +614,8 @@ alloc_new:
 	if (bio == NULL) {
 		if (first_unmapped == blocks_per_page) {
 			if (!bdev_write_page(bdev, blocks[0] << (blkbits - 9),
-								page, wbc)) {
-				clean_buffers(page, first_unmapped);
+								page, wbc))
 				goto out;
-			}
 		}
 		bio = mpage_alloc(bdev, blocks[0] << (blkbits - 9),
 				BIO_MAX_PAGES, GFP_NOFS|__GFP_HIGH);

@@ -226,6 +226,7 @@ int generic_write_end(struct file *, str
 				loff_t, unsigned, unsigned,
 				struct page *, void *);
 void page_zero_new_buffers(struct page *page, unsigned from, unsigned to);
+void clean_page_buffers(struct page *page);
 int cont_write_begin(struct file *, struct address_space *, loff_t,
 			unsigned, unsigned, struct page **, void **,
 			get_block_t *, loff_t *);