From 17c775db9da42f82dcb1b6aee8b895a326711fb6 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@suse.de>
Date: Sat, 4 Feb 2006 23:27:38 -0800
Subject: [PATCH] --- yaml --- r: 19790 b: refs/heads/master c:
 9a7a67af8bb02106f0fb01dd9d237332f874be9a h: refs/heads/master v: v3

---
 [refs]                  |  2 +-
 trunk/block/ll_rw_blk.c | 38 ++++++++++++++++----------------------
 2 files changed, 17 insertions(+), 23 deletions(-)

diff --git a/[refs] b/[refs]
index 9f116bde97dd..e510ad876993 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 88a2a4ac6b671a4b0dd5d2d762418904c05f4104
+refs/heads/master: 9a7a67af8bb02106f0fb01dd9d237332f874be9a
diff --git a/trunk/block/ll_rw_blk.c b/trunk/block/ll_rw_blk.c
index e5aad8314585..ee5ed98db4cd 100644
--- a/trunk/block/ll_rw_blk.c
+++ b/trunk/block/ll_rw_blk.c
@@ -508,7 +508,7 @@ static inline struct request *start_ordered(request_queue_t *q,
 
 int blk_do_ordered(request_queue_t *q, struct request **rqp)
 {
-	struct request *rq = *rqp, *allowed_rq;
+	struct request *rq = *rqp;
 	int is_barrier = blk_fs_request(rq) && blk_barrier_rq(rq);
 
 	if (!q->ordseq) {
@@ -532,32 +532,26 @@ int blk_do_ordered(request_queue_t *q, struct request **rqp)
 		}
 	}
 
+	/*
+	 * Ordered sequence in progress
+	 */
+
+	/* Special requests are not subject to ordering rules. */
+	if (!blk_fs_request(rq) &&
+	    rq != &q->pre_flush_rq && rq != &q->post_flush_rq)
+		return 1;
+
 	if (q->ordered & QUEUE_ORDERED_TAG) {
+		/* Ordered by tag.  Blocking the next barrier is enough. */
 		if (is_barrier && rq != &q->bar_rq)
 			*rqp = NULL;
-		return 1;
+	} else {
+		/* Ordered by draining.  Wait for turn. */
+		WARN_ON(blk_ordered_req_seq(rq) < blk_ordered_cur_seq(q));
+		if (blk_ordered_req_seq(rq) > blk_ordered_cur_seq(q))
+			*rqp = NULL;
 	}
 
-	switch (blk_ordered_cur_seq(q)) {
-	case QUEUE_ORDSEQ_PREFLUSH:
-		allowed_rq = &q->pre_flush_rq;
-		break;
-	case QUEUE_ORDSEQ_BAR:
-		allowed_rq = &q->bar_rq;
-		break;
-	case QUEUE_ORDSEQ_POSTFLUSH:
-		allowed_rq = &q->post_flush_rq;
-		break;
-	default:
-		allowed_rq = NULL;
-		break;
-	}
-
-	if (rq != allowed_rq &&
-	    (blk_fs_request(rq) || rq == &q->pre_flush_rq ||
-	     rq == &q->post_flush_rq))
-		*rqp = NULL;
-
 	return 1;
 }