Tag: KERNEL-2-2-18-PRE11-PATCH-8
Patch: IO-wait-2
From: Andrea Arcangeli <andrea@suse.de>

Avoid spurious unplug of the I/O queue.


Index: linux/fs/buffer.c
diff -u linux/fs/buffer.c:1.2 linux/fs/buffer.c:1.2.14.1
--- linux/fs/buffer.c:1.2	Thu Jul  6 22:41:37 2000
+++ linux/fs/buffer.c	Wed Sep 27 23:57:09 2000
@@ -143,13 +143,14 @@
 	bh->b_count++;
 	wait.task = tsk;
 	add_wait_queue(&bh->b_wait, &wait);
-repeat:
-	tsk->state = TASK_UNINTERRUPTIBLE;
-	run_task_queue(&tq_disk);
-	if (buffer_locked(bh)) {
+	do {
+		run_task_queue(&tq_disk);
+		tsk->state = TASK_UNINTERRUPTIBLE;
+		mb();
+		if (!buffer_locked(bh))
+			break;
 		schedule();
-		goto repeat;
-	}
+	} while (buffer_locked(bh));
 	tsk->state = TASK_RUNNING;
 	remove_wait_queue(&bh->b_wait, &wait);
 	bh->b_count--;

Index: linux/mm/filemap.c
diff -u linux/mm/filemap.c:1.4 linux/mm/filemap.c:1.4.4.1
--- linux/mm/filemap.c:1.4	Thu Sep 21 19:43:11 2000
+++ linux/mm/filemap.c	Wed Sep 27 23:57:09 2000
@@ -357,13 +357,14 @@
 
 	wait.task = tsk;
 	add_wait_queue(&page->wait, &wait);
-repeat:
-	tsk->state = TASK_UNINTERRUPTIBLE;
-	sync_page(page);
-	if (PageLocked(page)) {
+	do {
+		sync_page(page);
+		tsk->state = TASK_UNINTERRUPTIBLE;
+		mb();
+		if (!PageLocked(page))
+			break;
 		schedule();
-		goto repeat;
-	}
+	} while (PageLocked(page));
 	tsk->state = TASK_RUNNING;
 	remove_wait_queue(&page->wait, &wait);
 }