From 6afd9210909a1a7f6ed5e5a15fc9d1cf815a555e Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Wed, 30 Jan 2019 17:24:50 +0000
Subject: [PATCH] Only sort requests of types that have concept of offset.

Other types, such as BIO_FLUSH or BIO_ZONE, or especially new/unknown ones,
may imply some degree of ordering even if strict ordering is not requested
explicitly.

MFC after:	2 weeks
Sponsored by:	iXsystems, Inc.
---
 sys/kern/subr_disk.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sys/kern/subr_disk.c b/sys/kern/subr_disk.c
index 328111337c93..ea364a2a1dfa 100644
--- a/sys/kern/subr_disk.c
+++ b/sys/kern/subr_disk.c
@@ -259,6 +259,17 @@ bioq_disksort(struct bio_queue_head *head, struct bio *bp)
 		return;
 	}
 
+	/*
+	 * We should only sort requests of types that have concept of offset.
+	 * Other types, such as BIO_FLUSH or BIO_ZONE, may imply some degree
+	 * of ordering even if strict ordering is not requested explicitly.
+	 */
+	if (bp->bio_cmd != BIO_READ && bp->bio_cmd != BIO_WRITE &&
+	    bp->bio_cmd != BIO_DELETE) {
+		bioq_insert_tail(head, bp);
+		return;
+	}
+
 	if (bioq_batchsize > 0 && head->batched > bioq_batchsize) {
 		bioq_insert_tail(head, bp);
 		return;