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/aoe.h

@@ -1,4 +1,6 @@
 /* Copyright (c) 2013 Coraid, Inc.  See COPYING for GPL terms. */
+#include <linux/blk-mq.h>
+
 #define VERSION "85"
 #define AOE_MAJOR 152
 #define DEVICE_NAME "aoe"
@@ -164,6 +166,8 @@ struct aoedev {
 	struct gendisk *gd;
 	struct dentry *debugfs;
 	struct request_queue *blkq;
+	struct list_head rq_list;
+	struct blk_mq_tag_set tag_set;
 	struct hd_geometry geo;
 	sector_t ssize;
 	struct timer_list timer;

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;
 	}
 

drivers/block/aoe/aoecmd.c

@@ -7,7 +7,7 @@
 #include <linux/ata.h>
 #include <linux/slab.h>
 #include <linux/hdreg.h>
-#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
 #include <linux/skbuff.h>
 #include <linux/netdevice.h>
 #include <linux/genhd.h>
@@ -813,7 +813,7 @@ rexmit_timer(struct timer_list *timer)
 out:
 	if ((d->flags & DEVFL_KICKME) && d->blkq) {
 		d->flags &= ~DEVFL_KICKME;
-		d->blkq->request_fn(d->blkq);
+		blk_mq_run_hw_queues(d->blkq, true);
 	}
 
 	d->timer.expires = jiffies + TIMERTICK;
@@ -857,10 +857,12 @@ nextbuf(struct aoedev *d)
 		return d->ip.buf;
 	rq = d->ip.rq;
 	if (rq == NULL) {
-		rq = blk_peek_request(q);
+		rq = list_first_entry_or_null(&d->rq_list, struct request,
+						queuelist);
 		if (rq == NULL)
 			return NULL;
-		blk_start_request(rq);
+		list_del_init(&rq->queuelist);
+		blk_mq_start_request(rq);
 		d->ip.rq = rq;
 		d->ip.nxbio = rq->bio;
 		rq->special = (void *) rqbiocnt(rq);
@@ -1045,6 +1047,7 @@ aoe_end_request(struct aoedev *d, struct request *rq, int fastfail)
 	struct bio *bio;
 	int bok;
 	struct request_queue *q;
+	blk_status_t err = BLK_STS_OK;
 
 	q = d->blkq;
 	if (rq == d->ip.rq)
@@ -1052,11 +1055,15 @@ aoe_end_request(struct aoedev *d, struct request *rq, int fastfail)
 	do {
 		bio = rq->bio;
 		bok = !fastfail && !bio->bi_status;
-	} while (__blk_end_request(rq, bok ? BLK_STS_OK : BLK_STS_IOERR, bio->bi_iter.bi_size));
+		if (!bok)
+			err = BLK_STS_IOERR;
+	} while (blk_update_request(rq, bok ? BLK_STS_OK : BLK_STS_IOERR, bio->bi_iter.bi_size));
+
+	__blk_mq_end_request(rq, err);
 
 	/* cf. http://lkml.org/lkml/2006/10/31/28 */
 	if (!fastfail)
-		__blk_run_queue(q);
+		blk_mq_run_hw_queues(q, true);
 }
 
 static void

drivers/block/aoe/aoedev.c

@@ -5,7 +5,7 @@
  */
 
 #include <linux/hdreg.h>
-#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
 #include <linux/netdevice.h>
 #include <linux/delay.h>
 #include <linux/slab.h>
@@ -197,7 +197,6 @@ aoedev_downdev(struct aoedev *d)
 {
 	struct aoetgt *t, **tt, **te;
 	struct list_head *head, *pos, *nx;
-	struct request *rq;
 	int i;
 
 	d->flags &= ~DEVFL_UP;
@@ -225,10 +224,11 @@ aoedev_downdev(struct aoedev *d)
 
 	/* fast fail all pending I/O */
 	if (d->blkq) {
-		while ((rq = blk_peek_request(d->blkq))) {
-			blk_start_request(rq);
-			aoe_end_request(d, rq, 1);
-		}
+		/* UP is cleared, freeze+quiesce to insure all are errored */
+		blk_mq_freeze_queue(d->blkq);
+		blk_mq_quiesce_queue(d->blkq);
+		blk_mq_unquiesce_queue(d->blkq);
+		blk_mq_unfreeze_queue(d->blkq);
 	}
 
 	if (d->gd)
@@ -277,6 +277,7 @@ freedev(struct aoedev *d)
 		aoedisk_rm_debugfs(d);
 		del_gendisk(d->gd);
 		put_disk(d->gd);
+		blk_mq_free_tag_set(&d->tag_set);
 		blk_cleanup_queue(d->blkq);
 	}
 	t = d->targets;
@@ -463,6 +464,7 @@ aoedev_by_aoeaddr(ulong maj, int min, int do_alloc)
 	d->ntargets = NTARGETS;
 	INIT_WORK(&d->work, aoecmd_sleepwork);
 	spin_lock_init(&d->lock);
+	INIT_LIST_HEAD(&d->rq_list);
 	skb_queue_head_init(&d->skbpool);
 	timer_setup(&d->timer, dummy_timer, 0);
 	d->timer.expires = jiffies + HZ;