4 files changed, 34 insertions, 2 deletions
diff --git a/usr/src/cmd/truss/codes.c b/usr/src/cmd/truss/codes.c
index 888e6c9caf..9e7d513178 100644
--- a/usr/src/cmd/truss/codes.c
+++ b/usr/src/cmd/truss/codes.c
@@ -1380,6 +1380,10 @@ const struct ioc {
 		NULL},
 	{ (uint_t)DKIOCREADONLY,	"DKIOCREADONLY",
 		NULL},
+	{ (uint_t)DKIOCFREE,		"DKIOCFREE",
+		NULL},
+	{ (uint_t)DKIOC_CANFREE,	"DKIOC_CANFREE",
+		NULL},
 
 	/* disk ioctls - (0x04 << 8) - fdio.h */
 	{ (uint_t)FDIOGCHAR,		"FDIOGCHAR",
diff --git a/usr/src/uts/common/fs/zfs/zvol.c b/usr/src/uts/common/fs/zfs/zvol.c
index 2ac660e9f7..b61e000f9c 100644
--- a/usr/src/uts/common/fs/zfs/zvol.c
+++ b/usr/src/uts/common/fs/zfs/zvol.c
@@ -1663,7 +1663,7 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int flag, cred_t *cr, int *rvalp)
 {
 	zvol_state_t *zv;
 	struct dk_callback *dkc;
-	int error = 0;
+	int i, error = 0;
 	locked_range_t *lr;
 
 	mutex_enter(&zfsdev_state_lock);
@@ -1889,6 +1889,15 @@ zvol_ioctl(dev_t dev, int cmd, intptr_t arg, int flag, cred_t *cr, int *rvalp)
 		return (error);
 	}
 
+	case DKIOC_CANFREE:
+		i = zvol_unmap_enabled ? 1 : 0;
+		if (ddi_copyout(&i, (void *)arg, sizeof (int), flag) != 0) {
+			error = EFAULT;
+		} else {
+			error = 0;
+		}
+		break;
+
 	default:
 		error = SET_ERROR(ENOTTY);
 		break;
diff --git a/usr/src/uts/common/io/scsi/targets/sd.c b/usr/src/uts/common/io/scsi/targets/sd.c
index 51058cf50a..c4bc51a385 100644
--- a/usr/src/uts/common/io/scsi/targets/sd.c
+++ b/usr/src/uts/common/io/scsi/targets/sd.c
@@ -26,7 +26,7 @@
  * Copyright (c) 2011 Bayard G. Bell.  All rights reserved.
  * Copyright (c) 2012, 2016 by Delphix. All rights reserved.
  * Copyright 2012 DEY Storage Systems, Inc.  All rights reserved.
- * Copyright 2016 Joyent, Inc.
+ * Copyright 2019 Joyent, Inc.
  * Copyright 2017 Nexenta Systems, Inc.
  * Copyright 2019 Racktop Systems
  */
@@ -22635,6 +22635,7 @@ sdioctl(dev_t dev, int cmd, intptr_t arg, int flag, cred_t *cred_p, int *rval_p)
 		case DKIOCGMEDIAINFO:
 		case DKIOCGMEDIAINFOEXT:
 		case DKIOCSOLIDSTATE:
+		case DKIOC_CANFREE:
 		case MHIOCENFAILFAST:
 		case MHIOCSTATUS:
 		case MHIOCTKOWN:
@@ -23484,6 +23485,16 @@ skip_ready_valid:
 		}
 		break;
 
+	case DKIOC_CANFREE:
+		SD_TRACE(SD_LOG_IOCTL, un, "DKIOC_CANFREE\n");
+		i = (un->un_thin_flags & SD_THIN_PROV_ENABLED) ? 1 : 0;
+		if (ddi_copyout(&i, (void *)arg, sizeof (int), flag) != 0) {
+			err = EFAULT;
+		} else {
+			err = 0;
+		}
+		break;
+
 	case DKIOCGETWCE: {
 
 		int wce;
diff --git a/usr/src/uts/common/sys/dkio.h b/usr/src/uts/common/sys/dkio.h
index 7a9bbc3f15..9d88731c5d 100644
--- a/usr/src/uts/common/sys/dkio.h
+++ b/usr/src/uts/common/sys/dkio.h
@@ -24,6 +24,7 @@
  *
  * Copyright 2017 Nexenta Systems, Inc.  All rights reserved.
  * Copyright 2012 DEY Storage Systems, Inc.  All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #ifndef _SYS_DKIO_H
@@ -543,6 +544,13 @@ typedef struct dkioc_free_list_s {
 	(sizeof (dkioc_free_list_t) + \
 	(num_exts - 1) * sizeof (dkioc_free_list_ext_t))
 
+/*
+ * ioctl to determine if free (e.g. SCSI UNMAP) is supported.
+ * See FDIOC ioctls for why we're not using '51' here.
+ */
+#define	DKIOC_CANFREE	(DKIOC|60)
+
+
 #ifdef	__cplusplus
 }
 #endif