[PATCH 4/4] dm: support I/O polling

[Mikulas Patocka <mpatocka@redhat.com>]

[-- Attachment #1: dm-poll.patch --]
[-- Type: text/plain, Size: 760 bytes --]

Support I/O polling if submit_bio_noacct_mq_direct returned non-empty
cookie.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/md/dm.c |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6/drivers/md/dm.c
===================================================================
--- linux-2.6.orig/drivers/md/dm.c	2021-03-02 19:26:34.000000000 +0100
+++ linux-2.6/drivers/md/dm.c	2021-03-02 19:26:34.000000000 +0100
@@ -1682,6 +1682,11 @@ static void __split_and_process_bio(stru
 		}
 	}
 
+	if (ci.poll_cookie != BLK_QC_T_NONE) {
+		while (atomic_read(&ci.io->io_count) > 1 &&
+		       blk_poll(ci.poll_queue, ci.poll_cookie, true)) ;
+	}
+
 	/* drop the extra reference count */
 	dec_pending(ci.io, errno_to_blk_status(error));
 }