diff --git a/config/kernel-bio-rw-syncio.m4 b/config/kernel-bio-rw-syncio.m4
deleted file mode 100644
index 4bff80a8f..000000000
--- a/config/kernel-bio-rw-syncio.m4
+++ /dev/null
@@ -1,50 +0,0 @@
-dnl #
-dnl # Preferred interface for flagging a synchronous bio:
-dnl # 2.6.12-2.6.29: BIO_RW_SYNC
-dnl # 2.6.30-2.6.35: BIO_RW_SYNCIO
-dnl # 2.6.36-2.6.xx: REQ_SYNC
-dnl #
-AC_DEFUN([ZFS_AC_KERNEL_BIO_RW_SYNC], [
-	AC_MSG_CHECKING([whether BIO_RW_SYNC is defined])
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/bio.h>
-	],[
-		int flags __attribute__ ((unused));
-		flags = BIO_RW_SYNC;
-	],[
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_BIO_RW_SYNC, 1, [BIO_RW_SYNC is defined])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])
-
-AC_DEFUN([ZFS_AC_KERNEL_BIO_RW_SYNCIO], [
-	AC_MSG_CHECKING([whether BIO_RW_SYNCIO is defined])
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/bio.h>
-	],[
-		int flags __attribute__ ((unused));
-		flags = BIO_RW_SYNCIO;
-	],[
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_BIO_RW_SYNCIO, 1, [BIO_RW_SYNCIO is defined])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])
-
-AC_DEFUN([ZFS_AC_KERNEL_REQ_SYNC], [
-	AC_MSG_CHECKING([whether REQ_SYNC is defined])
-	ZFS_LINUX_TRY_COMPILE([
-		#include <linux/bio.h>
-	],[
-		int flags __attribute__ ((unused));
-		flags = REQ_SYNC;
-	],[
-		AC_MSG_RESULT(yes)
-		AC_DEFINE(HAVE_REQ_SYNC, 1, [REQ_SYNC is defined])
-	],[
-		AC_MSG_RESULT(no)
-	])
-])
diff --git a/config/kernel.m4 b/config/kernel.m4
index e088c4da3..0a65f39ef 100644
--- a/config/kernel.m4
+++ b/config/kernel.m4
@@ -25,9 +25,6 @@ AC_DEFUN([ZFS_AC_CONFIG_KERNEL], [
 	ZFS_AC_KERNEL_BIO_END_IO_T_ARGS
 	ZFS_AC_KERNEL_BIO_RW_BARRIER
 	ZFS_AC_KERNEL_BIO_RW_DISCARD
-	ZFS_AC_KERNEL_BIO_RW_SYNC
-	ZFS_AC_KERNEL_BIO_RW_SYNCIO
-	ZFS_AC_KERNEL_REQ_SYNC
 	ZFS_AC_KERNEL_BLK_QUEUE_FLUSH
 	ZFS_AC_KERNEL_BLK_QUEUE_MAX_HW_SECTORS
 	ZFS_AC_KERNEL_BLK_QUEUE_MAX_SEGMENTS
diff --git a/module/zfs/vdev_disk.c b/module/zfs/vdev_disk.c
index eac0f296e..5fb218f73 100644
--- a/module/zfs/vdev_disk.c
+++ b/module/zfs/vdev_disk.c
@@ -369,27 +369,6 @@ vdev_disk_dio_free(dio_request_t *dr)
 	    sizeof (struct bio *) * dr->dr_bio_count);
 }
 
-static int
-vdev_disk_dio_is_sync(dio_request_t *dr)
-{
-#ifdef HAVE_BIO_RW_SYNC
-	/* BIO_RW_SYNC preferred interface from 2.6.12-2.6.29 */
-	return (dr->dr_rw & (1 << BIO_RW_SYNC));
-#else
-#ifdef HAVE_BIO_RW_SYNCIO
-	/* BIO_RW_SYNCIO preferred interface from 2.6.30-2.6.35 */
-	return (dr->dr_rw & (1 << BIO_RW_SYNCIO));
-#else
-#ifdef HAVE_REQ_SYNC
-	/* REQ_SYNC preferred interface from 2.6.36-2.6.xx */
-	return (dr->dr_rw & REQ_SYNC);
-#else
-#error "Unable to determine bio sync flag"
-#endif /* HAVE_REQ_SYNC */
-#endif /* HAVE_BIO_RW_SYNC */
-#endif /* HAVE_BIO_RW_SYNCIO */
-}
-
 static void
 vdev_disk_dio_get(dio_request_t *dr)
 {
@@ -444,7 +423,7 @@ BIO_END_IO_PROTO(vdev_disk_physio_completion, bio, error)
 	rc = vdev_disk_dio_put(dr);
 
 	/* Wake up synchronous waiter this is the last outstanding bio */
-	if ((rc == 1) && vdev_disk_dio_is_sync(dr))
+	if (rc == 1)
 		complete(&dr->dr_comp);
 }
 
@@ -512,7 +491,7 @@ vdev_submit_bio(int rw, struct bio *bio)
 
 static int
 __vdev_disk_physio(struct block_device *bdev, zio_t *zio, caddr_t kbuf_ptr,
-    size_t kbuf_size, uint64_t kbuf_offset, int flags)
+    size_t kbuf_size, uint64_t kbuf_offset, int flags, int wait)
 {
 	dio_request_t *dr;
 	caddr_t bio_ptr;
@@ -603,7 +582,7 @@ retry:
 	 * only synchronous consumer is vdev_disk_read_rootlabel() all other
 	 * IO originating from vdev_disk_io_start() is asynchronous.
 	 */
-	if (vdev_disk_dio_is_sync(dr)) {
+	if (wait) {
 		wait_for_completion(&dr->dr_comp);
 		error = dr->dr_error;
 		ASSERT3S(atomic_read(&dr->dr_ref), ==, 1);
@@ -619,7 +598,7 @@ vdev_disk_physio(struct block_device *bdev, caddr_t kbuf,
     size_t size, uint64_t offset, int flags)
 {
 	bio_set_flags_failfast(bdev, &flags);
-	return (__vdev_disk_physio(bdev, NULL, kbuf, size, offset, flags));
+	return (__vdev_disk_physio(bdev, NULL, kbuf, size, offset, flags, 1));
 }
 
 BIO_END_IO_PROTO(vdev_disk_io_flush_completion, bio, rc)
@@ -671,6 +650,7 @@ vdev_disk_io_start(zio_t *zio)
 {
 	vdev_t *v = zio->io_vd;
 	vdev_disk_t *vd = v->vdev_tsd;
+	zio_priority_t pri = zio->io_priority;
 	int flags, error;
 
 	switch (zio->io_type) {
@@ -710,14 +690,14 @@ vdev_disk_io_start(zio_t *zio)
 		zio_execute(zio);
 		return;
 	case ZIO_TYPE_WRITE:
-		if (zio->io_priority == ZIO_PRIORITY_SYNC_WRITE)
+		if ((pri == ZIO_PRIORITY_SYNC_WRITE) && (v->vdev_nonrot))
 			flags = WRITE_SYNC;
 		else
 			flags = WRITE;
 		break;
 
 	case ZIO_TYPE_READ:
-		if (zio->io_priority == ZIO_PRIORITY_SYNC_READ)
+		if ((pri == ZIO_PRIORITY_SYNC_READ) && (v->vdev_nonrot))
 			flags = READ_SYNC;
 		else
 			flags = READ;
@@ -730,7 +710,7 @@ vdev_disk_io_start(zio_t *zio)
 	}
 
 	error = __vdev_disk_physio(vd->vd_bdev, zio, zio->io_data,
-	    zio->io_size, zio->io_offset, flags);
+	    zio->io_size, zio->io_offset, flags, 0);
 	if (error) {
 		zio->io_error = error;
 		zio_interrupt(zio);