From 2e0358cbcab49f7be18762e8cb51e642188709e7 Mon Sep 17 00:00:00 2001
From: Brian Behlendorf <behlendorf1@llnl.gov>
Date: Fri, 13 Dec 2013 14:49:33 -0800
Subject: [PATCH] Sync /dev/zfs ioctl ordering

In order to minimize any future disruption caused by the addition
and removal /dev/zfs ioctls this patch makes the following changes.

1) Sync ZoL's ioctl ordering such that it matches Illumos.  For
   historic reasons the ZFS_IOC_DESTROY_SNAPS and ZFS_IOC_POOL_REGUID
   ioctls were out of order.

2) Move Linux and FreeBSD specific ioctls in to their own reserved
   ranges.  This allows us to preserve the existing ordering when
   new ioctls are added by either Illumos or FreeBSD.  When an
   ioctl is no longer needed it should be retired in place.

This change alters the ZFS user/kernel ABI so make sure you rebuild
both your user and kernel modules.  However, it should allow for a
much stabler interface going forward.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ned Bass <bass6@llnl.gov>
Closes #1973
---
 include/sys/fs/zfs.h   | 22 ++++++++++++++++++----
 module/zfs/zfs_ioctl.c |  7 +++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/include/sys/fs/zfs.h b/include/sys/fs/zfs.h
index 08076bc09..b19ebb6fe 100644
--- a/include/sys/fs/zfs.h
+++ b/include/sys/fs/zfs.h
@@ -768,6 +768,9 @@ typedef struct ddt_histogram {
  * /dev/zfs ioctl numbers.
  */
 typedef enum zfs_ioc {
+	/*
+	 * Illumos - 69/128 numbers reserved.
+	 */
 	ZFS_IOC_FIRST =	('Z' << 8),
 	ZFS_IOC = ZFS_IOC_FIRST,
 	ZFS_IOC_POOL_CREATE = ZFS_IOC_FIRST,
@@ -805,7 +808,6 @@ typedef enum zfs_ioc {
 	ZFS_IOC_ERROR_LOG,
 	ZFS_IOC_CLEAR,
 	ZFS_IOC_PROMOTE,
-	ZFS_IOC_DESTROY_SNAPS,
 	ZFS_IOC_SNAPSHOT,
 	ZFS_IOC_DSOBJ_TO_DSNAME,
 	ZFS_IOC_OBJ_TO_PATH,
@@ -828,17 +830,29 @@ typedef enum zfs_ioc {
 	ZFS_IOC_DIFF,
 	ZFS_IOC_TMP_SNAPSHOT,
 	ZFS_IOC_OBJ_TO_STATS,
-	ZFS_IOC_EVENTS_NEXT,
-	ZFS_IOC_EVENTS_CLEAR,
-	ZFS_IOC_POOL_REGUID,
 	ZFS_IOC_SPACE_WRITTEN,
 	ZFS_IOC_SPACE_SNAPS,
+	ZFS_IOC_DESTROY_SNAPS,
+	ZFS_IOC_POOL_REGUID,
 	ZFS_IOC_POOL_REOPEN,
 	ZFS_IOC_SEND_PROGRESS,
 	ZFS_IOC_LOG_HISTORY,
 	ZFS_IOC_SEND_NEW,
 	ZFS_IOC_SEND_SPACE,
 	ZFS_IOC_CLONE,
+
+	/*
+	 * Linux - 3/64 numbers reserved.
+	 */
+	ZFS_IOC_LINUX = ('Z' << 8) + 0x80,
+	ZFS_IOC_EVENTS_NEXT,
+	ZFS_IOC_EVENTS_CLEAR,
+
+	/*
+	 * FreeBSD - 1/64 numbers reserved.
+	 */
+	ZFS_IOC_FREEBSD = ('Z' << 8) + 0xC0,
+
 	ZFS_IOC_LAST
 } zfs_ioc_t;
 
diff --git a/module/zfs/zfs_ioctl.c b/module/zfs/zfs_ioctl.c
index 9b084632f..924151480 100644
--- a/module/zfs/zfs_ioctl.c
+++ b/module/zfs/zfs_ioctl.c
@@ -5565,6 +5565,13 @@ zfsdev_ioctl(struct file *filp, unsigned cmd, unsigned long arg)
 		return (-SET_ERROR(EINVAL));
 	vec = &zfs_ioc_vec[vecnum];
 
+	/*
+	 * The registered ioctl list may be sparse, verify that either
+	 * a normal or legacy handler are registered.
+	 */
+	if (vec->zvec_func == NULL && vec->zvec_legacy_func == NULL)
+		return (-SET_ERROR(EINVAL));
+
 	zc = kmem_zalloc(sizeof (zfs_cmd_t), KM_SLEEP | KM_NODEBUG);
 	saved_poolname = kmem_alloc(MAXNAMELEN, KM_SLEEP);