Patch "dm mpath: delay requeuing while path initialization is in progress" has been added to the 4.11-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    dm mpath: delay requeuing while path initialization is in progress

to the 4.11-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dm-mpath-delay-requeuing-while-path-initialization-is-in-progress.patch
and it can be found in the queue-4.11 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From c1d7ecf7ca11d0edd3085262c8597203440d056c Mon Sep 17 00:00:00 2001
From: Bart Van Assche <bart.vanassche@sandisk.com>
Date: Thu, 27 Apr 2017 10:11:16 -0700
Subject: dm mpath: delay requeuing while path initialization is in progress

From: Bart Van Assche <bart.vanassche@sandisk.com>

commit c1d7ecf7ca11d0edd3085262c8597203440d056c upstream.

Requeuing a request immediately while path initialization is ongoing
causes high CPU usage, something that is undesired.  Hence delay
requeuing while path initialization is in progress.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/md/dm-mpath.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -322,13 +322,16 @@ static int __pg_init_all_paths(struct mu
 	return atomic_read(&m->pg_init_in_progress);
 }
 
-static void pg_init_all_paths(struct multipath *m)
+static int pg_init_all_paths(struct multipath *m)
 {
+	int ret;
 	unsigned long flags;
 
 	spin_lock_irqsave(&m->lock, flags);
-	__pg_init_all_paths(m);
+	ret = __pg_init_all_paths(m);
 	spin_unlock_irqrestore(&m->lock, flags);
+
+	return ret;
 }
 
 static void __switch_pg(struct multipath *m, struct priority_group *pg)
@@ -503,7 +506,8 @@ static int multipath_clone_and_map(struc
 		return -EIO;	/* Failed */
 	} else if (test_bit(MPATHF_QUEUE_IO, &m->flags) ||
 		   test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
-		pg_init_all_paths(m);
+		if (pg_init_all_paths(m))
+			return DM_MAPIO_DELAY_REQUEUE;
 		return DM_MAPIO_REQUEUE;
 	}
 


Patches currently in stable-queue which might be from bart.vanassche@sandisk.com are

queue-4.11/dm-mpath-requeue-after-a-small-delay-if-blk_get_request-fails.patch
queue-4.11/dm-mpath-avoid-that-path-removal-can-trigger-an-infinite-loop.patch
queue-4.11/dm-mpath-split-and-rename-activate_path-to-prepare-for-its-expanded-use.patch
queue-4.11/dm-mpath-delay-requeuing-while-path-initialization-is-in-progress.patch