diff --git a/drivers/media/video/v4l2-ioctl.c b/drivers/media/video/v4l2-ioctl.c
index 175688e9489f83093d4f37c4682abdf6ff6a153e..00c0f76b9b5df18dd0a4f1c0c571728d586b4fac 100644
--- a/drivers/media/video/v4l2-ioctl.c
+++ b/drivers/media/video/v4l2-ioctl.c
@@ -726,16 +726,8 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_ENUM_FMT:
 	{
 		struct v4l2_fmtdesc *f = arg;
-		enum v4l2_buf_type type;
-		unsigned int index;
 
-		index = f->index;
-		type  = f->type;
-		memset(f, 0, sizeof(*f));
-		f->index = index;
-		f->type  = type;
-
-		switch (type) {
+		switch (f->type) {
 		case V4L2_BUF_TYPE_VIDEO_CAPTURE:
 			if (ops->vidioc_enum_fmt_vid_cap)
 				ret = ops->vidioc_enum_fmt_vid_cap(file, fh, f);
@@ -772,8 +764,6 @@ static long __video_do_ioctl(struct file *file,
 	{
 		struct v4l2_format *f = (struct v4l2_format *)arg;
 
-		memset(f->fmt.raw_data, 0, sizeof(f->fmt.raw_data));
-
 		/* FIXME: Should be one dump per type */
 		dbgarg(cmd, "type=%s\n", prt_names(f->type, v4l2_type_names));
 
@@ -969,11 +959,6 @@ static long __video_do_ioctl(struct file *file,
 		if (ret)
 			break;
 
-		/* Zero out all fields starting with bytesysed, which is
-		 * everything but index and type.  */
-		memset(0, &p->bytesused,
-		       sizeof(*p) - offsetof(typeof(*p), bytesused));
-
 		ret = ops->vidioc_querybuf(file, fh, p);
 		if (!ret)
 			dbgbuf(cmd, vfd, p);
@@ -1159,12 +1144,9 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_ENUMINPUT:
 	{
 		struct v4l2_input *p = arg;
-		int i = p->index;
 
 		if (!ops->vidioc_enum_input)
 			break;
-		memset(p, 0, sizeof(*p));
-		p->index = i;
 
 		ret = ops->vidioc_enum_input(file, fh, p);
 		if (!ret)
@@ -1203,12 +1185,9 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_ENUMOUTPUT:
 	{
 		struct v4l2_output *p = arg;
-		int i = p->index;
 
 		if (!ops->vidioc_enum_output)
 			break;
-		memset(p, 0, sizeof(*p));
-		p->index = i;
 
 		ret = ops->vidioc_enum_output(file, fh, p);
 		if (!ret)
@@ -1384,13 +1363,11 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_G_AUDIO:
 	{
 		struct v4l2_audio *p = arg;
-		__u32 index = p->index;
 
 		if (!ops->vidioc_g_audio)
 			break;
 
 		memset(p, 0, sizeof(*p));
-		p->index = index;
 		ret = ops->vidioc_g_audio(file, fh, p);
 		if (!ret)
 			dbgarg(cmd, "index=%d, name=%s, capability=0x%x, "
@@ -1485,15 +1462,10 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_G_CROP:
 	{
 		struct v4l2_crop *p = arg;
-		__u32 type;
 
 		if (!ops->vidioc_g_crop)
 			break;
 
-		type = p->type;
-		memset(p, 0, sizeof(*p));
-		p->type = type;
-
 		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
 		ret = ops->vidioc_g_crop(file, fh, p);
 		if (!ret)
@@ -1514,16 +1486,11 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_CROPCAP:
 	{
 		struct v4l2_cropcap *p = arg;
-		__u32 type;
 
 		/*FIXME: Should also show v4l2_fract pixelaspect */
 		if (!ops->vidioc_cropcap)
 			break;
 
-		type = p->type;
-		memset(p, 0, sizeof(*p));
-		p->type = type;
-
 		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
 		ret = ops->vidioc_cropcap(file, fh, p);
 		if (!ret) {
@@ -1581,7 +1548,6 @@ static long __video_do_ioctl(struct file *file,
 
 		if (!ops->vidioc_encoder_cmd)
 			break;
-		memset(&p->raw, 0, sizeof(p->raw));
 		ret = ops->vidioc_encoder_cmd(file, fh, p);
 		if (!ret)
 			dbgarg(cmd, "cmd=%d, flags=%x\n", p->cmd, p->flags);
@@ -1593,7 +1559,6 @@ static long __video_do_ioctl(struct file *file,
 
 		if (!ops->vidioc_try_encoder_cmd)
 			break;
-		memset(&p->raw, 0, sizeof(p->raw));
 		ret = ops->vidioc_try_encoder_cmd(file, fh, p);
 		if (!ret)
 			dbgarg(cmd, "cmd=%d, flags=%x\n", p->cmd, p->flags);
@@ -1602,10 +1567,6 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_G_PARM:
 	{
 		struct v4l2_streamparm *p = arg;
-		__u32 type = p->type;
-
-		memset(p, 0, sizeof(*p));
-		p->type = type;
 
 		if (ops->vidioc_g_parm) {
 			ret = ops->vidioc_g_parm(file, fh, p);
@@ -1638,14 +1599,10 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_G_TUNER:
 	{
 		struct v4l2_tuner *p = arg;
-		__u32 index = p->index;
 
 		if (!ops->vidioc_g_tuner)
 			break;
 
-		memset(p, 0, sizeof(*p));
-		p->index = index;
-
 		ret = ops->vidioc_g_tuner(file, fh, p);
 		if (!ret)
 			dbgarg(cmd, "index=%d, name=%s, type=%d, "
@@ -1682,8 +1639,6 @@ static long __video_do_ioctl(struct file *file,
 		if (!ops->vidioc_g_frequency)
 			break;
 
-		memset(p->reserved, 0, sizeof(p->reserved));
-
 		ret = ops->vidioc_g_frequency(file, fh, p);
 		if (!ret)
 			dbgarg(cmd, "tuner=%d, type=%d, frequency=%d\n",
@@ -1704,12 +1659,13 @@ static long __video_do_ioctl(struct file *file,
 	case VIDIOC_G_SLICED_VBI_CAP:
 	{
 		struct v4l2_sliced_vbi_cap *p = arg;
-		__u32 type = p->type;
 
 		if (!ops->vidioc_g_sliced_vbi_cap)
 			break;
-		memset(p, 0, sizeof(*p));
-		p->type = type;
+
+		/* Clear up to type, everything after type is zerod already */
+		memset(p, 0, offsetof(struct v4l2_sliced_vbi_cap, type));
+
 		dbgarg(cmd, "type=%s\n", prt_names(p->type, v4l2_type_names));
 		ret = ops->vidioc_g_sliced_vbi_cap(file, fh, p);
 		if (!ret)
@@ -1782,8 +1738,6 @@ static long __video_do_ioctl(struct file *file,
 		if (!ops->vidioc_enum_framesizes)
 			break;
 
-		memset(p, 0, sizeof(*p));
-
 		ret = ops->vidioc_enum_framesizes(file, fh, p);
 		dbgarg(cmd,
 			"index=%d, pixelformat=%d, type=%d ",
@@ -1815,8 +1769,6 @@ static long __video_do_ioctl(struct file *file,
 		if (!ops->vidioc_enum_frameintervals)
 			break;
 
-		memset(p, 0, sizeof(*p));
-
 		ret = ops->vidioc_enum_frameintervals(file, fh, p);
 		dbgarg(cmd,
 			"index=%d, pixelformat=%d, width=%d, height=%d, type=%d ",
@@ -1865,6 +1817,44 @@ static long __video_do_ioctl(struct file *file,
 	return ret;
 }
 
+/* In some cases, only a few fields are used as input, i.e. when the app sets
+ * "index" and then the driver fills in the rest of the structure for the thing
+ * with that index.  We only need to copy up the first non-input field.  */
+static unsigned long cmd_input_size(unsigned int cmd)
+{
+	/* Size of structure up to and including 'field' */
+#define CMDINSIZE(cmd, type, field) case _IOC_NR(VIDIOC_##cmd): return \
+		offsetof(struct v4l2_##type, field) + \
+		sizeof(((struct v4l2_##type *)0)->field);
+
+	switch (_IOC_NR(cmd)) {
+		CMDINSIZE(ENUM_FMT,		fmtdesc,	type);
+		CMDINSIZE(G_FMT,		format,		type);
+		CMDINSIZE(QUERYBUF,		buffer,		type);
+		CMDINSIZE(G_PARM,		streamparm,	type);
+		CMDINSIZE(ENUMSTD,		standard,	index);
+		CMDINSIZE(ENUMINPUT,		input,		index);
+		CMDINSIZE(G_CTRL,		control,	id);
+		CMDINSIZE(G_TUNER,		tuner,		index);
+		CMDINSIZE(QUERYCTRL,		queryctrl,	id);
+		CMDINSIZE(QUERYMENU,		querymenu,	index);
+		CMDINSIZE(ENUMOUTPUT,		output,		index);
+		CMDINSIZE(G_MODULATOR,		modulator,	index);
+		CMDINSIZE(G_FREQUENCY,		frequency,	tuner);
+		CMDINSIZE(CROPCAP,		cropcap,	type);
+		CMDINSIZE(G_CROP,		crop,		type);
+		CMDINSIZE(ENUMAUDIO,		audio, 		index);
+		CMDINSIZE(ENUMAUDOUT,		audioout, 	index);
+		CMDINSIZE(ENCODER_CMD,		encoder_cmd,	flags);
+		CMDINSIZE(TRY_ENCODER_CMD,	encoder_cmd,	flags);
+		CMDINSIZE(G_SLICED_VBI_CAP,	sliced_vbi_cap,	type);
+		CMDINSIZE(ENUM_FRAMESIZES,	frmsizeenum,	pixel_format);
+		CMDINSIZE(ENUM_FRAMEINTERVALS,	frmivalenum,	height);
+	default:
+		return _IOC_SIZE(cmd);
+	}
+}
+
 long video_ioctl2(struct file *file,
 	       unsigned int cmd, unsigned long arg)
 {
@@ -1901,9 +1891,16 @@ long video_ioctl2(struct file *file,
 		}
 
 		err = -EFAULT;
-		if (_IOC_DIR(cmd) & _IOC_WRITE)
-			if (copy_from_user(parg, (void __user *)arg, _IOC_SIZE(cmd)))
+		if (_IOC_DIR(cmd) & _IOC_WRITE) {
+			unsigned long n = cmd_input_size(cmd);
+
+			if (copy_from_user(parg, (void __user *)arg, n))
 				goto out;
+
+			/* zero out anything we don't copy from userspace */
+			if (n < _IOC_SIZE(cmd))
+				memset((u8 *)parg + n, 0, _IOC_SIZE(cmd) - n);
+		}
 		break;
 	}