Index: sys/dev/fdc/fdc.c
===================================================================
--- sys/dev/fdc/fdc.c
+++ sys/dev/fdc/fdc.c
@@ -73,6 +73,7 @@
 #include <sys/mutex.h>
 #include <sys/priv.h>
 #include <sys/proc.h>
+#include <sys/refcount.h>
 #include <sys/rman.h>
 #include <sys/sysctl.h>
 #include <sys/systm.h>
@@ -260,6 +261,7 @@
 	struct g_geom *fd_geom;
 	struct g_provider *fd_provider;
 	device_t dev;
+	u_int ref;
 	struct bio_queue_head fd_bq;
 };
 
@@ -1431,7 +1433,7 @@
 
 	if (ar == 0 && aw == 0 && ae == 0) {
 		fd->options &= ~(FDOPT_NORETRY | FDOPT_NOERRLOG | FDOPT_NOERROR);
-		device_unbusy(fd->dev);
+		refcount_release(&fd->ref);
 		return (0);
 	}
 
@@ -1453,13 +1455,13 @@
 			fd->flags &= ~FD_NEWDISK;
 			mtx_unlock(&fdc->fdc_mtx);
 		}
-		device_busy(fd->dev);
+		refcount_acquire(&fd->ref);
 		busy = 1;
 	}
 
 	if (w > 0 && (fd->flags & FD_WP)) {
 		if (busy)
-			device_unbusy(fd->dev);
+			refcount_release(&fd->ref);
 		return (EROFS);
 	}
 
@@ -2070,9 +2072,9 @@
 	struct	fd_data *fd;
 
 	fd = device_get_softc(dev);
+	if (refcount_load(&fd->ref))
+		return (EBUSY);
 	g_waitfor_event(fd_detach_geom, fd, M_WAITOK, NULL);
-	while (device_get_state(dev) == DS_BUSY)
-		tsleep(fd, PZERO, "fdd", hz/10);
 	callout_drain(&fd->toffhandle);
 
 	return (0);