From 3582dd291788e9441c3ba9047e55089edb98da5c Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Fri, 12 Oct 2018 10:03:14 -0600
Subject: aoe: convert aoeblk to blk-mq

Straight forward conversion - instead of rewriting the internal buffer
retrieval logic, just replace the previous elevator peeking with an
internal list of requests.

Reviewed-by: "Ed L. Cashin" <ed.cashin@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 drivers/block/aoe/aoeblk.c | 49 ++++++++++++++++++++++++++++++++++------------
 1 file changed, 36 insertions(+), 13 deletions(-)

(limited to 'drivers/block/aoe/aoeblk.c')

diff --git a/drivers/block/aoe/aoeblk.c b/drivers/block/aoe/aoeblk.c
index ff770e7d9e52..ed26b7287256 100644
--- a/drivers/block/aoe/aoeblk.c
+++ b/drivers/block/aoe/aoeblk.c
@@ -6,7 +6,7 @@
 
 #include <linux/kernel.h>
 #include <linux/hdreg.h>
-#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
 #include <linux/backing-dev.h>
 #include <linux/fs.h>
 #include <linux/ioctl.h>
@@ -268,23 +268,25 @@ aoeblk_release(struct gendisk *disk, fmode_t mode)
 	spin_unlock_irqrestore(&d->lock, flags);
 }
 
-static void
-aoeblk_request(struct request_queue *q)
+static blk_status_t aoeblk_queue_rq(struct blk_mq_hw_ctx *hctx,
+				    const struct blk_mq_queue_data *bd)
 {
-	struct aoedev *d;
-	struct request *rq;
+	struct aoedev *d = hctx->queue->queuedata;
+
+	spin_lock_irq(&d->lock);
 
-	d = q->queuedata;
 	if ((d->flags & DEVFL_UP) == 0) {
 		pr_info_ratelimited("aoe: device %ld.%d is not up\n",
 			d->aoemajor, d->aoeminor);
-		while ((rq = blk_peek_request(q))) {
-			blk_start_request(rq);
-			aoe_end_request(d, rq, 1);
-		}
-		return;
+		spin_unlock_irq(&d->lock);
+		blk_mq_start_request(bd->rq);
+		return BLK_STS_IOERR;
 	}
+
+	list_add_tail(&bd->rq->queuelist, &d->rq_list);
 	aoecmd_work(d);
+	spin_unlock_irq(&d->lock);
+	return BLK_STS_OK;
 }
 
 static int
@@ -339,6 +341,10 @@ static const struct block_device_operations aoe_bdops = {
 	.owner = THIS_MODULE,
 };
 
+static const struct blk_mq_ops aoeblk_mq_ops = {
+	.queue_rq	= aoeblk_queue_rq,
+};
+
 /* alloc_disk and add_disk can sleep */
 void
 aoeblk_gdalloc(void *vp)
@@ -347,9 +353,11 @@ aoeblk_gdalloc(void *vp)
 	struct gendisk *gd;
 	mempool_t *mp;
 	struct request_queue *q;
+	struct blk_mq_tag_set *set;
 	enum { KB = 1024, MB = KB * KB, READ_AHEAD = 2 * MB, };
 	ulong flags;
 	int late = 0;
+	int err;
 
 	spin_lock_irqsave(&d->lock, flags);
 	if (d->flags & DEVFL_GDALLOC
@@ -376,10 +384,25 @@ aoeblk_gdalloc(void *vp)
 			d->aoemajor, d->aoeminor);
 		goto err_disk;
 	}
-	q = blk_init_queue(aoeblk_request, &d->lock);
-	if (q == NULL) {
+
+	set = &d->tag_set;
+	set->ops = &aoeblk_mq_ops;
+	set->nr_hw_queues = 1;
+	set->queue_depth = 128;
+	set->numa_node = NUMA_NO_NODE;
+	set->flags = BLK_MQ_F_SHOULD_MERGE;
+	err = blk_mq_alloc_tag_set(set);
+	if (err) {
+		pr_err("aoe: cannot allocate tag set for %ld.%d\n",
+			d->aoemajor, d->aoeminor);
+		goto err_mempool;
+	}
+
+	q = blk_mq_init_queue(set);
+	if (IS_ERR(q)) {
 		pr_err("aoe: cannot allocate block queue for %ld.%d\n",
 			d->aoemajor, d->aoeminor);
+		blk_mq_free_tag_set(set);
 		goto err_mempool;
 	}
 
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