From 415b806de5576b656f3ff94366589af9a161d0c8 Mon Sep 17 00:00:00 2001
From: Sagi Grimberg <sagi@grimberg.me>
Date: Mon, 27 Feb 2017 10:04:39 -0700
Subject: [PATCH] blk-mq-sched: Allocate sched reserved tags as specified in
 the original queue tagset

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>

Modified by me to also check at driver tag allocation time if the
original request was reserved, so we can be sure to allocate a
properly reserved tag at that point in time, too.

Signed-off-by: Jens Axboe <axboe@fb.com>
---
 block/blk-mq-sched.c | 3 ++-
 block/blk-mq-tag.c   | 2 +-
 block/blk-mq-tag.h   | 6 ++++++
 block/blk-mq.c       | 3 +++
 4 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 98c7b061781e..46ca965fff5c 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -454,7 +454,8 @@ int blk_mq_sched_setup(struct request_queue *q)
 	 */
 	ret = 0;
 	queue_for_each_hw_ctx(q, hctx, i) {
-		hctx->sched_tags = blk_mq_alloc_rq_map(set, i, q->nr_requests, 0);
+		hctx->sched_tags = blk_mq_alloc_rq_map(set, i,
+				q->nr_requests, set->reserved_tags);
 		if (!hctx->sched_tags) {
 			ret = -ENOMEM;
 			break;
diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c
index 54c84363c1b2..e48bc2c72615 100644
--- a/block/blk-mq-tag.c
+++ b/block/blk-mq-tag.c
@@ -181,7 +181,7 @@ found_tag:
 void blk_mq_put_tag(struct blk_mq_hw_ctx *hctx, struct blk_mq_tags *tags,
 		    struct blk_mq_ctx *ctx, unsigned int tag)
 {
-	if (tag >= tags->nr_reserved_tags) {
+	if (!blk_mq_tag_is_reserved(tags, tag)) {
 		const int real_tag = tag - tags->nr_reserved_tags;
 
 		BUG_ON(real_tag >= tags->nr_tags);
diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h
index 63497423c5cd..5cb51e53cc03 100644
--- a/block/blk-mq-tag.h
+++ b/block/blk-mq-tag.h
@@ -85,4 +85,10 @@ static inline void blk_mq_tag_set_rq(struct blk_mq_hw_ctx *hctx,
 	hctx->tags->rqs[tag] = rq;
 }
 
+static inline bool blk_mq_tag_is_reserved(struct blk_mq_tags *tags,
+					  unsigned int tag)
+{
+	return tag < tags->nr_reserved_tags;
+}
+
 #endif
diff --git a/block/blk-mq.c b/block/blk-mq.c
index d84c66fb37b7..4df5fb42c74f 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -852,6 +852,9 @@ done:
 		return true;
 	}
 
+	if (blk_mq_tag_is_reserved(data.hctx->sched_tags, rq->internal_tag))
+		data.flags |= BLK_MQ_REQ_RESERVED;
+
 	rq->tag = blk_mq_get_tag(&data);
 	if (rq->tag >= 0) {
 		if (blk_mq_tag_busy(data.hctx)) {