From 94fe9f959c04586f1f19759af3945534fbfab984 Mon Sep 17 00:00:00 2001
From: Alexander Motin <mav@FreeBSD.org>
Date: Wed, 4 Jun 2014 12:05:47 +0000
Subject: [PATCH] - Add support for SG_GET_SG_TABLESIZE IOCTL to report that we
 don't support scatter/gather lists. - Return error for still unsupported SG
 3.x API read/write calls.

MFC after:	1 month
---
 sys/cam/scsi/scsi_sg.c         | 14 +++++++++++++-
 sys/compat/linux/linux_ioctl.c |  3 +++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/sys/cam/scsi/scsi_sg.c b/sys/cam/scsi/scsi_sg.c
index 715b48a1b885..3e80ac3e763f 100644
--- a/sys/cam/scsi/scsi_sg.c
+++ b/sys/cam/scsi/scsi_sg.c
@@ -627,6 +627,13 @@ sgioctl(struct cdev *dev, u_long cmd, caddr_t arg, int flag, struct thread *td)
 		break;
 	}
 
+	case SG_GET_SG_TABLESIZE:
+	{
+		int *size = (int *)arg;
+		*size = 0;
+		break;
+	}
+
 	case SG_EMULATED_HOST:
 	case SG_SET_TRANSFORM:
 	case SG_GET_TRANSFORM:
@@ -638,7 +645,6 @@ sgioctl(struct cdev *dev, u_long cmd, caddr_t arg, int flag, struct thread *td)
 	case SG_GET_ACCESS_COUNT:
 	case SG_SET_FORCE_LOW_DMA:
 	case SG_GET_LOW_DMA:
-	case SG_GET_SG_TABLESIZE:
 	case SG_SET_FORCE_PACK_ID:
 	case SG_GET_PACK_ID:
 	case SG_SET_RESERVED_SIZE:
@@ -684,6 +690,12 @@ sgwrite(struct cdev *dev, struct uio *uio, int ioflag)
 	if (error)
 		goto out_hdr;
 
+	/* XXX: We don't support SG 3.x read/write API. */
+	if (hdr->reply_len < 0) {
+		error = ENODEV;
+		goto out_hdr;
+	}
+
 	ccb = xpt_alloc_ccb();
 	if (ccb == NULL) {
 		error = ENOMEM;
diff --git a/sys/compat/linux/linux_ioctl.c b/sys/compat/linux/linux_ioctl.c
index e1e13716aa1a..77feed0870ee 100644
--- a/sys/compat/linux/linux_ioctl.c
+++ b/sys/compat/linux/linux_ioctl.c
@@ -2751,6 +2751,9 @@ linux_ioctl_sg(struct thread *td, struct linux_ioctl_args *args)
 	case LINUX_SG_GET_SCSI_ID:
 		args->cmd = SG_GET_SCSI_ID;
 		break;
+	case LINUX_SG_GET_SG_TABLESIZE:
+		args->cmd = SG_GET_SG_TABLESIZE;
+		break;
 	default:
 		return (ENODEV);
 	}