diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 0639024d83a98e95a69c2be9bac2c8c548c0de43..c403b66ec83c6525532c25decbe923c32356649b 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -319,7 +319,7 @@ sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
 
 		if (!bdi_cap_writeback_dirty(bdi)) {
 			list_move(&inode->i_list, &sb->s_dirty);
-			if (sb == blockdev_superblock) {
+			if (sb_is_blkdev_sb(sb)) {
 				/*
 				 * Dirty memory-backed blockdev: the ramdisk
 				 * driver does this.  Skip just this inode
@@ -336,14 +336,14 @@ sync_sb_inodes(struct super_block *sb, struct writeback_control *wbc)
 
 		if (wbc->nonblocking && bdi_write_congested(bdi)) {
 			wbc->encountered_congestion = 1;
-			if (sb != blockdev_superblock)
+			if (!sb_is_blkdev_sb(sb))
 				break;		/* Skip a congested fs */
 			list_move(&inode->i_list, &sb->s_dirty);
 			continue;		/* Skip a congested blockdev */
 		}
 
 		if (wbc->bdi && bdi != wbc->bdi) {
-			if (sb != blockdev_superblock)
+			if (!sb_is_blkdev_sb(sb))
 				break;		/* fs has the wrong queue */
 			list_move(&inode->i_list, &sb->s_dirty);
 			continue;		/* blockdev has wrong queue */
diff --git a/fs/internal.h b/fs/internal.h
index c21ecd37b1e79d9104d326a25d5cb4ebba2f576c..f662b703bb97bcdbebe41c20f187fcdb9d5e4106 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -17,6 +17,8 @@
 extern struct super_block *blockdev_superblock;
 extern void __init bdev_cache_init(void);
 
+#define sb_is_blkdev_sb(sb) ((sb) == blockdev_superblock)
+
 /*
  * char_dev.c
  */