Index: stand/efi/libefi/efipart.c
===================================================================
--- stand/efi/libefi/efipart.c
+++ stand/efi/libefi/efipart.c
@@ -935,8 +935,9 @@
 static int
 efipart_close(struct open_file *f)
 {
-	struct disk_devdesc *dev;
+	struct disk_devdesc *dev, *currdev;
 	pdinfo_t *pd;
+	int rc;
 
 	dev = (struct disk_devdesc *)(f->f_devdata);
 	if (dev == NULL)
@@ -946,14 +947,33 @@
 	if (pd == NULL)
 		return (EINVAL);
 
+	if (dev->dd.d_dev->dv_type == DEVT_DISK) {
+		rc = disk_close(dev);
+		if (rc != 0)
+			return (rc);
+	}
 	pd->pd_open--;
+
+	/*
+	 * Check if this disk is our current filesystem device.
+	 * if it is, preserve pd_bcache to avoid cache flushes.
+	 */
+	rc = archsw.arch_getdev((void **)&currdev, NULL, NULL);
+	if (rc == 0) {
+		if (strcmp(dev->dd.d_dev->dv_name,
+		   currdev->dd.d_dev->dv_name) == 0 &&
+		   dev->dd.d_dev->dv_type == currdev->dd.d_dev->dv_type &&
+		   dev->dd.d_unit == currdev->dd.d_unit) {
+			return (0);
+		}
+	} else {
+		rc = 0;
+	}
+
 	if (pd->pd_open == 0) {
-		pd->pd_blkio = NULL;
 		bcache_free(pd->pd_bcache);
 		pd->pd_bcache = NULL;
 	}
-	if (dev->dd.d_dev->dv_type == DEVT_DISK)
-		return (disk_close(dev));
 	return (0);
 }
 
Index: stand/i386/libi386/biosdisk.c
===================================================================
--- stand/i386/libi386/biosdisk.c
+++ stand/i386/libi386/biosdisk.c
@@ -879,22 +879,42 @@
 static int
 bd_close(struct open_file *f)
 {
-	struct disk_devdesc *dev;
+	struct disk_devdesc *dev, *currdev;
 	bdinfo_t *bd;
-	int rc = 0;
+	int rc;
 
 	dev = (struct disk_devdesc *)f->f_devdata;
 	bd = bd_get_bdinfo(&dev->dd);
 	if (bd == NULL)
 		return (EIO);
 
+	if (dev->dd.d_dev->dv_type == DEVT_DISK) {
+		rc = disk_close(dev);
+		if (rc != 0)
+			return (rc);
+	}
 	bd->bd_open--;
+
+	/*
+	 * Check if this disk is our current filesystem device.
+	 * if it is, preserve bd_bcache to avoid cache flushes.
+	 */
+	rc = archsw.arch_getdev((void **)&currdev, NULL, NULL);
+	if (rc == 0) {
+		if (strcmp(dev->dd.d_dev->dv_name,
+		    currdev->dd.d_dev->dv_name) == 0 &&
+		    dev->dd.d_dev->dv_type == currdev->dd.d_dev->dv_type &&
+		    dev->dd.d_unit == currdev->dd.d_unit) {
+			return (0);
+		}
+	} else {
+		rc = 0;
+	}
+
 	if (bd->bd_open == 0) {
 	    bcache_free(bd->bd_bcache);
 	    bd->bd_bcache = NULL;
 	}
-	if (dev->dd.d_dev->dv_type == DEVT_DISK)
-		rc = disk_close(dev);
 	return (rc);
 }
 
Index: stand/userboot/userboot/userboot_disk.c
===================================================================
--- stand/userboot/userboot/userboot_disk.c
+++ stand/userboot/userboot/userboot_disk.c
@@ -176,15 +176,38 @@
 static int
 userdisk_close(struct open_file *f)
 {
-	struct disk_devdesc *dev;
+	struct disk_devdesc *dev, *currdev;
+	int rc;
 
 	dev = (struct disk_devdesc *)f->f_devdata;
+	if (dev->dd.d_dev->dv_type == DEVT_DISK) {
+		rc = disk_close(dev);
+		if (rc != 0)
+			return (rc);
+	}
 	ud_info[dev->dd.d_unit].ud_open--;
+
+	/*
+	 * Check if this disk is our current filesystem device.
+	 * if it is, preserve ud_bcache to avoid cache flushes.
+	 */
+	rc = archsw.arch_getdev((void **)&currdev, NULL, NULL);
+	if (rc == 0) {
+		if (strcmp(dev->dd.d_dev->dv_name,
+		    currdev->dd.d_dev->dv_name) == 0 &&
+		    dev->dd.d_dev->dv_type == currdev->dd.d_dev->dv_type &&
+		    dev->dd.d_unit == currdev->dd.d_unit) {
+			return (0);
+		}
+	} else {
+		rc = 0;
+	}
+
 	if (ud_info[dev->dd.d_unit].ud_open == 0) {
 		bcache_free(ud_info[dev->dd.d_unit].ud_bcache);
 		ud_info[dev->dd.d_unit].ud_bcache = NULL;
 	}
-	return (disk_close(dev));
+	return (rc);
 }
 
 static int