From: Jens Axboe <axboe@kernel.dk>
Date: Tue, 16 Oct 2018 08:37:23 -0600
Subject: [PATCH] scsi: fnic: replace gross legacy tag hack with blk-mq hack
Git-commit: 4d5b4ac1eae471bcd0fa381ab4099cc33e94e15d
Patch-mainline: v4.20-rc1
References: bsc#1104967,FATE#325924

Would be nice to fix up the SCSI midlayer instead, but this will do for
now.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Satish Kharat <satishkh@cisco.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Hannes Reinecke <hare@suse.com>
---
 drivers/scsi/fnic/fnic_scsi.c | 61 +++++++++----------------------------------
 1 file changed, 12 insertions(+), 49 deletions(-)

diff --git a/drivers/scsi/fnic/fnic_scsi.c b/drivers/scsi/fnic/fnic_scsi.c
index 12a2f8fa4d19..96acfcecd540 100644
--- a/drivers/scsi/fnic/fnic_scsi.c
+++ b/drivers/scsi/fnic/fnic_scsi.c
@@ -2266,33 +2266,17 @@ static int fnic_clean_pending_aborts(struct fnic *fnic,
 static inline int
 fnic_scsi_host_start_tag(struct fnic *fnic, struct scsi_cmnd *sc)
 {
-	struct blk_queue_tag *bqt = fnic->lport->host->bqt;
-	int tag, ret = SCSI_NO_TAG;
+	struct request_queue *q = sc->request->q;
+	struct request *dummy;
 
-	BUG_ON(!bqt);
-	if (!bqt) {
-		pr_err("Tags are not supported\n");
-		goto end;
-	}
-
-	do {
-		tag = find_next_zero_bit(bqt->tag_map, bqt->max_depth, 1);
-		if (tag >= bqt->max_depth) {
-			pr_err("Tag allocation failure\n");
-			goto end;
-		}
-	} while (test_and_set_bit(tag, bqt->tag_map));
+	dummy = blk_mq_alloc_request(q, REQ_OP_WRITE, BLK_MQ_REQ_NOWAIT);
+	if (IS_ERR(dummy))
+		return SCSI_NO_TAG;
 
-	bqt->tag_index[tag] = sc->request;
-	sc->request->tag = tag;
-	sc->tag = tag;
-	if (!sc->request->special)
-		sc->request->special = sc;
+	sc->tag = sc->request->tag = dummy->tag;
+	sc->request->special = sc;
 
-	ret = tag;
-
-end:
-	return ret;
+	return dummy->tag;
 }
 
 /**
@@ -2302,20 +2286,9 @@ fnic_scsi_host_start_tag(struct fnic *fnic, struct scsi_cmnd *sc)
 static inline void
 fnic_scsi_host_end_tag(struct fnic *fnic, struct scsi_cmnd *sc)
 {
-	struct blk_queue_tag *bqt = fnic->lport->host->bqt;
-	int tag = sc->request->tag;
-
-	if (tag == SCSI_NO_TAG)
-		return;
-
-	BUG_ON(!bqt || !bqt->tag_index[tag]);
-	if (!bqt)
-		return;
+	struct request *dummy = sc->request->special;
 
-	bqt->tag_index[tag] = NULL;
-	clear_bit(tag, bqt->tag_map);
-
-	return;
+	blk_mq_free_request(dummy);
 }
 
 /*
@@ -2374,19 +2347,9 @@ int fnic_device_reset(struct scsi_cmnd *sc)
 	tag = sc->request->tag;
 	if (unlikely(tag < 0)) {
 		/*
-		 * XXX(hch): current the midlayer fakes up a struct
-		 * request for the explicit reset ioctls, and those
-		 * don't have a tag allocated to them.  The below
-		 * code pokes into midlayer structures to paper over
-		 * this design issue, but that won't work for blk-mq.
-		 *
-		 * Either someone who can actually test the hardware
-		 * will have to come up with a similar hack for the
-		 * blk-mq case, or we'll have to bite the bullet and
-		 * fix the way the EH ioctls work for real, but until
-		 * that happens we fail these explicit requests here.
+		 * Really should fix the midlayer to pass in a proper
+		 * request for ioctls...
 		 */
-
 		tag = fnic_scsi_host_start_tag(fnic, sc);
 		if (unlikely(tag == SCSI_NO_TAG))
 			goto fnic_device_reset_end;
-- 
2.16.4