From 6bccc8b4e3887923e300c6b280e4fef631c3149c Mon Sep 17 00:00:00 2001
From: Jens Axboe <jaxboe@fusionio.com>
Date: Fri, 19 Aug 2011 08:34:48 +0200
Subject: [PATCH] --- yaml --- r: 263151 b: refs/heads/master c:
 b53d1ed734a2b9af8da115b836b658daa7d47a48 h: refs/heads/master i:   263149:
 9990249477e9a7118f9ff15ecf1e8ad59d5401e6   263147:
 12517167f342e8cfbf0cc8d6e081452a2ce44ce1   263143:
 978250c85db5e10412e7b2f9364220e0c7f5078d   263135:
 e8ff49b04a75d8e8a17bad4258e8798ef30aafbc v: v3

---
 [refs]                    |  2 +-
 trunk/block/cfq-iosched.c | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 25524e4b2173..eea792d62bf9 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 4853abaae7e4a2af938115ce9071ef8684fb7af4
+refs/heads/master: b53d1ed734a2b9af8da115b836b658daa7d47a48
diff --git a/trunk/block/cfq-iosched.c b/trunk/block/cfq-iosched.c
index 650834537606..a33bd4377c61 100644
--- a/trunk/block/cfq-iosched.c
+++ b/trunk/block/cfq-iosched.c
@@ -130,6 +130,8 @@ struct cfq_queue {
 	unsigned long slice_end;
 	long slice_resid;
 
+	/* pending metadata requests */
+	int meta_pending;
 	/* number of requests that are on the dispatch list or inside driver */
 	int dispatched;
 
@@ -682,6 +684,9 @@ cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2,
 	if (rq_is_sync(rq1) != rq_is_sync(rq2))
 		return rq_is_sync(rq1) ? rq1 : rq2;
 
+	if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_META)
+		return rq1->cmd_flags & REQ_META ? rq1 : rq2;
+
 	s1 = blk_rq_pos(rq1);
 	s2 = blk_rq_pos(rq2);
 
@@ -1607,6 +1612,10 @@ static void cfq_remove_request(struct request *rq)
 	cfqq->cfqd->rq_queued--;
 	cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg,
 					rq_data_dir(rq), rq_is_sync(rq));
+	if (rq->cmd_flags & REQ_META) {
+		WARN_ON(!cfqq->meta_pending);
+		cfqq->meta_pending--;
+	}
 }
 
 static int cfq_merge(struct request_queue *q, struct request **req,
@@ -3359,6 +3368,13 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
 	    RB_EMPTY_ROOT(&cfqq->sort_list))
 		return true;
 
+	/*
+	 * So both queues are sync. Let the new request get disk time if
+	 * it's a metadata request and the current queue is doing regular IO.
+	 */
+	if ((rq->cmd_flags & REQ_META) && !cfqq->meta_pending)
+		return true;
+
 	/*
 	 * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice.
 	 */
@@ -3423,6 +3439,8 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
 	struct cfq_io_context *cic = RQ_CIC(rq);
 
 	cfqd->rq_queued++;
+	if (rq->cmd_flags & REQ_META)
+		cfqq->meta_pending++;
 
 	cfq_update_io_thinktime(cfqd, cfqq, cic);
 	cfq_update_io_seektime(cfqd, cfqq, rq);