diff --git a/fs/nilfs2/segment.c b/fs/nilfs2/segment.c
index fa4abfc..c4fcdd1 100644
--- a/fs/nilfs2/segment.c
+++ b/fs/nilfs2/segment.c
@@ -1937,8 +1937,7 @@
 {
 	struct nilfs_segment_buffer *segbuf;
 	struct page *bd_page = NULL, *fs_page = NULL;
-	struct nilfs_sb_info *sbi = sci->sc_sbi;
-	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
 	int update_sr = (sci->sc_super_root != NULL);
 
 	list_for_each_entry(segbuf, &sci->sc_write_logs, sb_list) {
@@ -2020,7 +2019,7 @@
 	if (update_sr) {
 		nilfs_set_last_segment(nilfs, segbuf->sb_pseg_start,
 				       segbuf->sb_sum.seg_seq, nilfs->ns_cno++);
-		sbi->s_super->s_dirt = 1;
+		set_nilfs_sb_dirty(nilfs);
 
 		clear_bit(NILFS_SC_HAVE_DELTA, &sci->sc_flags);
 		clear_bit(NILFS_SC_DIRTY, &sci->sc_flags);
@@ -2645,6 +2644,7 @@
 static int nilfs_segctor_thread(void *arg)
 {
 	struct nilfs_sc_info *sci = (struct nilfs_sc_info *)arg;
+	struct the_nilfs *nilfs = sci->sc_sbi->s_nilfs;
 	struct timer_list timer;
 	int timeout = 0;
 
@@ -2690,7 +2690,6 @@
 	} else {
 		DEFINE_WAIT(wait);
 		int should_sleep = 1;
-		struct the_nilfs *nilfs;
 
 		prepare_to_wait(&sci->sc_wait_daemon, &wait,
 				TASK_INTERRUPTIBLE);
@@ -2711,8 +2710,8 @@
 		finish_wait(&sci->sc_wait_daemon, &wait);
 		timeout = ((sci->sc_state & NILFS_SEGCTOR_COMMIT) &&
 			   time_after_eq(jiffies, sci->sc_timer->expires));
-		nilfs = sci->sc_sbi->s_nilfs;
-		if (sci->sc_super->s_dirt && nilfs_sb_need_update(nilfs))
+
+		if (nilfs_sb_dirty(nilfs) && nilfs_sb_need_update(nilfs))
 			set_nilfs_discontinued(nilfs);
 	}
 	goto loop;
diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index f068270..92579cc 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -298,7 +298,7 @@
 		memcpy(sbp[1], sbp[0], nilfs->ns_sbsize);
 		nilfs->ns_sbwtime[1] = t;
 	}
-	sbi->s_super->s_dirt = 0;
+	clear_nilfs_sb_dirty(nilfs);
 	return nilfs_sync_super(sbi, dupsb);
 }
 
@@ -342,7 +342,7 @@
 		err = nilfs_construct_segment(sb);
 
 	down_write(&nilfs->ns_sem);
-	if (sb->s_dirt)
+	if (nilfs_sb_dirty(nilfs))
 		nilfs_commit_super(sbi, 1);
 	up_write(&nilfs->ns_sem);
 
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index fd057f8..e9795f1 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -38,6 +38,7 @@
 				   the latest checkpoint was loaded */
 	THE_NILFS_DISCONTINUED,	/* 'next' pointer chain has broken */
 	THE_NILFS_GC_RUNNING,	/* gc process is running */
+	THE_NILFS_SB_DIRTY,	/* super block is dirty */
 };
 
 /**
@@ -197,6 +198,7 @@
 THE_NILFS_FNS(LOADED, loaded)
 THE_NILFS_FNS(DISCONTINUED, discontinued)
 THE_NILFS_FNS(GC_RUNNING, gc_running)
+THE_NILFS_FNS(SB_DIRTY, sb_dirty)
 
 /* Minimum interval of periodical update of superblocks (in seconds) */
 #define NILFS_SB_FREQ		10