[PATCH] blk_run_page() race fix

blk_run_page() is incorrectly using page->mapping, which makes it racy against
removal from swapcache.

Make block_sync_page() use page_mapping(), and remove bkl_run_page(), which
only had one caller.

1 files changed, 6 insertions, 1 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 8c6abdcb22cf..9f76190d4654 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2960,7 +2960,12 @@ EXPORT_SYMBOL(try_to_free_buffers);
 
 int block_sync_page(struct page *page)
 {
-	blk_run_page(page);
+	struct address_space *mapping;
+
+	smp_mb();
+	mapping = page_mapping(page);
+	if (mapping)
+		blk_run_backing_dev(mapping->backing_dev_info, page);
 	return 0;
 }