From: Mike Snitzer <snitzer@redhat.com>
Date: Sun, 31 Jan 2016 22:38:28 +0000 (-0500)
Subject: dm mpath: use blk_mq_alloc_request() and blk_mq_free_request() directly
X-Git-Tag: next-20160210~48^2~3
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=b6a58d6c2b4fbd8a2ac073a9aa56d8891af4a33b;p=karo-tx-linux.git

dm mpath: use blk_mq_alloc_request() and blk_mq_free_request() directly

There isn't any need to support both old .request_fn and blk-mq paths
in the blk-mq specific portion of __multipath_map().  Call
blk_mq_alloc_request() directly rather than use blk_get_request().

Similarly, call blk_mq_free_request(), rather than blk_put_request(), in
multipath_release_clone().

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
---

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 612ec571862d..798644624663 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -23,6 +23,7 @@
 #include <linux/delay.h>
 #include <scsi/scsi_dh.h>
 #include <linux/atomic.h>
+#include <linux/blk-mq.h>
 
 #define DM_MSG_PREFIX "multipath"
 #define DM_PG_INIT_DELAY_MSECS 2000
@@ -439,14 +440,22 @@ static int __multipath_map(struct dm_target *ti, struct request *clone,
 	spin_unlock_irq(&m->lock);
 
 	if (clone) {
-		/* Old request-based interface: allocated clone is passed in */
+		/*
+		 * Old request-based interface: allocated clone is passed in.
+		 * Used by both: .request_fn stacked on .request_fn path(s) and
+		 * blk-mq stacked on .request_fn path(s).
+		 */
 		clone->q = bdev_get_queue(bdev);
 		clone->rq_disk = bdev->bd_disk;
 		clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
 	} else {
-		/* blk-mq request-based interface */
-		*__clone = blk_get_request(bdev_get_queue(bdev),
-					   rq_data_dir(rq), GFP_ATOMIC);
+		/*
+		 * blk-mq request-based interface; used by both:
+		 * .request_fn stacked on blk-mq path(s) and
+		 * blk-mq stacked on blk-mq path(s).
+		 */
+		*__clone = blk_mq_alloc_request(bdev_get_queue(bdev),
+						rq_data_dir(rq), BLK_MQ_REQ_NOWAIT);
 		if (IS_ERR(*__clone)) {
 			/* ENOMEM, requeue */
 			return r;
@@ -483,7 +492,7 @@ static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
 
 static void multipath_release_clone(struct request *clone)
 {
-	blk_put_request(clone);
+	blk_mq_free_request(clone);
 }
 
 /*