diff --git a/sys/dev/md/md.c b/sys/dev/md/md.c
--- a/sys/dev/md/md.c
+++ b/sys/dev/md/md.c
@@ -887,23 +887,6 @@
 	int ma_offs, npages;
 	bool mapped;
 
-	switch (bp->bio_cmd) {
-	case BIO_READ:
-		auio.uio_rw = UIO_READ;
-		break;
-	case BIO_WRITE:
-		auio.uio_rw = UIO_WRITE;
-		break;
-	case BIO_FLUSH:
-		break;
-	case BIO_DELETE:
-		if (sc->candelete)
-			break;
-		/* FALLTHROUGH */
-	default:
-		return (EOPNOTSUPP);
-	}
-
 	td = curthread;
 	vp = sc->vnode;
 	piov = NULL;
@@ -920,7 +903,14 @@
 	 * still valid.
 	 */
 
-	if (bp->bio_cmd == BIO_FLUSH) {
+	switch (bp->bio_cmd) {
+	case BIO_READ:
+		auio.uio_rw = UIO_READ;
+		break;
+	case BIO_WRITE:
+		auio.uio_rw = UIO_WRITE;
+		break;
+	case BIO_FLUSH:
 		do {
 			(void)vn_start_write(vp, &mp, V_WAIT);
 			vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
@@ -929,11 +919,17 @@
 			vn_finished_write(mp);
 		} while (error == ERELOOKUP);
 		return (error);
-	} else if (bp->bio_cmd == BIO_DELETE) {
-		error = vn_deallocate(vp, &off, &len, 0,
-		    sc->flags & MD_ASYNC ? 0 : IO_SYNC, sc->cred, NOCRED);
-		bp->bio_resid = len;
-		return (error);
+	case BIO_DELETE:
+		if (sc->candelete) {
+			error = vn_deallocate(vp, &off, &len, 0,
+			    sc->flags & MD_ASYNC ? 0 : IO_SYNC, sc->cred,
+			    NOCRED);
+			bp->bio_resid = len;
+			return (error);
+		}
+		/* FALLTHROUGH */
+	default:
+		return (EOPNOTSUPP);
 	}
 
 	auio.uio_offset = (vm_ooffset_t)bp->bio_offset;
@@ -981,7 +977,7 @@
 		auio.uio_iovcnt = 1;
 	}
 	iostart = auio.uio_offset;
-	if (auio.uio_rw == UIO_READ) {
+	if (bp->bio_cmd == BIO_READ) {
 		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 		error = VOP_READ(vp, &auio, 0, sc->cred);
 		VOP_UNLOCK(vp);