--- 1.87/fs/buffer.c	Thu Jul  3 13:43:56 2003
+++ edited/fs/buffer.c	Fri Jul  4 13:01:28 2003
@@ -83,6 +83,8 @@
 static int nr_unused_buffer_heads;
 static spinlock_t unused_list_lock = SPIN_LOCK_UNLOCKED;
 static DECLARE_WAIT_QUEUE_HEAD(buffer_wait);
+static DECLARE_WAIT_QUEUE_HEAD(bdflush_progress_wait);
+static atomic_t bdflush_generation = ATOMIC_INIT(0);
 
 static int grow_buffers(kdev_t dev, unsigned long block, int size);
 static int osync_buffers_list(struct list_head *);
@@ -1036,7 +1038,6 @@
 	if (state < 0)
 		return;
 
-	wakeup_bdflush();
 
 	/*
 	 * And if we're _really_ out of balance, wait for
@@ -1044,9 +1045,20 @@
 	 * This will throttle heavy writers.
 	 */
 	if (state > 0) {
-		spin_lock(&lru_list_lock);
-		write_some_buffers(NODEV);
-	}
+		int gen = atomic_read(&bdflush_generation);
+		DECLARE_WAITQUEUE(wait, current);
+		add_wait_queue_exclusive(&bdflush_progress_wait, &wait);
+		do {
+			set_current_state(TASK_UNINTERRUPTIBLE);
+			wakeup_bdflush();
+			if (gen != atomic_read(&bdflush_generation))
+				break;
+			schedule();
+		} while(gen == atomic_read(&bdflush_generation));
+		remove_wait_queue(&bdflush_progress_wait, &wait);
+		set_current_state(TASK_RUNNING);
+	} else
+		wakeup_bdflush();
 }
 EXPORT_SYMBOL(balance_dirty);
 
@@ -2947,6 +2959,16 @@
 	return 0;
 }
 
+static void poke_throttled_writers(int all) {
+	atomic_inc(&bdflush_generation);
+	smp_mb();
+	if (waitqueue_active(&bdflush_progress_wait)) {
+		if (all)
+			wake_up_all(&bdflush_progress_wait);
+		else
+			wake_up(&bdflush_progress_wait);
+	}
+}
 /*
  * This is the actual bdflush daemon itself. It used to be started from
  * the syscall above, but now we launch it ourselves internally with
@@ -2955,6 +2977,7 @@
 int bdflush(void *startup)
 {
 	struct task_struct *tsk = current;
+	DECLARE_WAITQUEUE(wait, tsk);
 
 	/*
 	 *	We have a bare-bones task_struct, and really should fill
@@ -2992,12 +3015,21 @@
 
 		while (ndirty > 0) {
 			spin_lock(&lru_list_lock);
-			if (!write_some_buffers(NODEV))
+			if (!write_some_buffers(NODEV)) {
+				poke_throttled_writers(0);
 				break;
+			} 
+			poke_throttled_writers(0);
 			ndirty -= NRSYNC;
 		}
-		if (ndirty > 0 || bdflush_stop())
-			interruptible_sleep_on(&bdflush_wait);
+		if (ndirty > 0 || bdflush_stop()) {
+			add_wait_queue(&bdflush_wait, &wait);
+			set_current_state(TASK_INTERRUPTIBLE);
+			poke_throttled_writers(1);
+			schedule();
+			remove_wait_queue(&bdflush_wait, &wait);
+			set_current_state(TASK_RUNNING);
+		}
 	}
 }