1 files changed, 49 insertions, 36 deletions

diff --git a/block/blk-core.c b/block/blk-core.c
index 2f4002f79a24..3cc17e6064d6 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -149,39 +149,29 @@ EXPORT_SYMBOL(blk_rq_init);
 static void req_bio_endio(struct request *rq, struct bio *bio,
 			  unsigned int nbytes, int error)
 {
-	struct request_queue *q = rq->q;
-
-	if (&q->flush_rq != rq) {
-		if (error)
-			clear_bit(BIO_UPTODATE, &bio->bi_flags);
-		else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
-			error = -EIO;
-
-		if (unlikely(nbytes > bio->bi_size)) {
-			printk(KERN_ERR "%s: want %u bytes done, %u left\n",
-			       __func__, nbytes, bio->bi_size);
-			nbytes = bio->bi_size;
-		}
+	if (error)
+		clear_bit(BIO_UPTODATE, &bio->bi_flags);
+	else if (!test_bit(BIO_UPTODATE, &bio->bi_flags))
+		error = -EIO;
+
+	if (unlikely(nbytes > bio->bi_size)) {
+		printk(KERN_ERR "%s: want %u bytes done, %u left\n",
+		       __func__, nbytes, bio->bi_size);
+		nbytes = bio->bi_size;
+	}
 
-		if (unlikely(rq->cmd_flags & REQ_QUIET))
-			set_bit(BIO_QUIET, &bio->bi_flags);
+	if (unlikely(rq->cmd_flags & REQ_QUIET))
+		set_bit(BIO_QUIET, &bio->bi_flags);
 
-		bio->bi_size -= nbytes;
-		bio->bi_sector += (nbytes >> 9);
+	bio->bi_size -= nbytes;
+	bio->bi_sector += (nbytes >> 9);
 
-		if (bio_integrity(bio))
-			bio_integrity_advance(bio, nbytes);
+	if (bio_integrity(bio))
+		bio_integrity_advance(bio, nbytes);
 
-		if (bio->bi_size == 0)
-			bio_endio(bio, error);
-	} else {
-		/*
-		 * Okay, this is the sequenced flush request in
-		 * progress, just record the error;
-		 */
-		if (error && !q->flush_err)
-			q->flush_err = error;
-	}
+	/* don't actually finish bio if it's part of flush sequence */
+	if (bio->bi_size == 0 && !(rq->cmd_flags & REQ_FLUSH_SEQ))
+		bio_endio(bio, error);
 }
 
 void blk_dump_rq_flags(struct request *rq, char *msg)
@@ -540,7 +530,9 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 	init_timer(&q->unplug_timer);
 	setup_timer(&q->timeout, blk_rq_timed_out_timer, (unsigned long) q);
 	INIT_LIST_HEAD(&q->timeout_list);
-	INIT_LIST_HEAD(&q->pending_flushes);
+	INIT_LIST_HEAD(&q->flush_queue[0]);
+	INIT_LIST_HEAD(&q->flush_queue[1]);
+	INIT_LIST_HEAD(&q->flush_data_in_flight);
 	INIT_WORK(&q->unplug_work, blk_unplug_work);
 
 	kobject_init(&q->kobj, &blk_queue_ktype);
@@ -761,6 +753,25 @@ static void freed_request(struct request_queue *q, int sync, int priv)
 }
 
 /*
+ * Determine if elevator data should be initialized when allocating the
+ * request associated with @bio.
+ */
+static bool blk_rq_should_init_elevator(struct bio *bio)
+{
+	if (!bio)
+		return true;
+
+	/*
+	 * Flush requests do not use the elevator so skip initialization.
+	 * This allows a request to share the flush and elevator data.
+	 */
+	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA))
+		return false;
+
+	return true;
+}
+
+/*
  * Get a free request, queue_lock must be held.
  * Returns NULL on failure, with queue_lock held.
  * Returns !NULL on success, with queue_lock *not held*.
@@ -772,7 +783,7 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	struct request_list *rl = &q->rq;
 	struct io_context *ioc = NULL;
 	const bool is_sync = rw_is_sync(rw_flags) != 0;
-	int may_queue, priv;
+	int may_queue, priv = 0;
 
 	may_queue = elv_may_queue(q, rw_flags);
 	if (may_queue == ELV_MQUEUE_NO)
@@ -816,9 +827,11 @@ static struct request *get_request(struct request_queue *q, int rw_flags,
 	rl->count[is_sync]++;
 	rl->starved[is_sync] = 0;
 
-	priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
-	if (priv)
-		rl->elvpriv++;
+	if (blk_rq_should_init_elevator(bio)) {
+		priv = !test_bit(QUEUE_FLAG_ELVSWITCH, &q->queue_flags);
+		if (priv)
+			rl->elvpriv++;
+	}
 
 	if (blk_queue_io_stat(q))
 		rw_flags |= REQ_IO_STAT;
@@ -1219,7 +1232,7 @@ static int __make_request(struct request_queue *q, struct bio *bio)
 	spin_lock_irq(q->queue_lock);
 
 	if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
-		where = ELEVATOR_INSERT_FRONT;
+		where = ELEVATOR_INSERT_FLUSH;
 		goto get_rq;
 	}
 
@@ -1804,7 +1817,7 @@ static void blk_account_io_done(struct request *req)
 	 * normal IO on queueing nor completion.  Accounting the
 	 * containing request is enough.
 	 */
-	if (blk_do_io_stat(req) && req != &req->q->flush_rq) {
+	if (blk_do_io_stat(req) && !(req->cmd_flags & REQ_FLUSH_SEQ)) {
 		unsigned long duration = jiffies - req->start_time;
 		const int rw = rq_data_dir(req);
 		struct hd_struct *part;