Handle the BLKTRACESETUP2 ioctl, requesting an extended version of the
blktrace protocol from user-space.

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 block/ioctl.c           |  1 +
 kernel/trace/blktrace.c | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/block/ioctl.c b/block/ioctl.c
index d7489a56b33c..3927ca4707d0 100644
--- a/block/ioctl.c
+++ b/block/ioctl.c
@@ -691,6 +691,7 @@ long blkdev_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 
 	/* Incompatible alignment on i386 */
 	case BLKTRACESETUP:
+	case BLKTRACESETUP2:
 		return blk_trace_ioctl(bdev, cmd, argp);
 	default:
 		break;
diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
index 6bfe1b36a1d3..6ad3807a5b73 100644
--- a/kernel/trace/blktrace.c
+++ b/kernel/trace/blktrace.c
@@ -749,6 +749,38 @@ int blk_trace_setup(struct request_queue *q, char *name, dev_t dev,
 }
 EXPORT_SYMBOL_GPL(blk_trace_setup);
 
+static int blk_trace_setup2(struct request_queue *q, char *name, dev_t dev,
+			    struct block_device *bdev, char __user *arg)
+{
+	struct blk_user_trace_setup2 buts2;
+	struct blk_trace *bt;
+
+	if (copy_from_user(&buts2, arg, sizeof(buts2)))
+		return -EFAULT;
+
+	if (!buts2.buf_size || !buts2.buf_nr)
+		return -EINVAL;
+
+	if (buts2.flags != 0)
+		return -EINVAL;
+
+	mutex_lock(&q->debugfs_mutex);
+	bt = blk_trace_setup_prepare(q, name, dev, buts2.buf_size, buts2.buf_nr,
+				     bdev);
+	if (IS_ERR(bt)) {
+		mutex_unlock(&q->debugfs_mutex);
+		return PTR_ERR(bt);
+	}
+	blk_trace_setup_finalize(q, name, 2, bt, &buts2);
+	mutex_unlock(&q->debugfs_mutex);
+
+	if (copy_to_user(arg, &buts2, sizeof(buts2))) {
+		blk_trace_remove(q);
+		return -EFAULT;
+	}
+	return 0;
+}
+
 #if defined(CONFIG_COMPAT) && defined(CONFIG_X86_64)
 static int compat_blk_trace_setup(struct request_queue *q, char *name,
 				  dev_t dev, struct block_device *bdev,
@@ -839,6 +871,10 @@ int blk_trace_ioctl(struct block_device *bdev, unsigned cmd, char __user *arg)
 	char b[BDEVNAME_SIZE];
 
 	switch (cmd) {
+	case BLKTRACESETUP2:
+		snprintf(b, sizeof(b), "%pg", bdev);
+		ret = blk_trace_setup2(q, b, bdev->bd_dev, bdev, arg);
+		break;
 	case BLKTRACESETUP:
 		snprintf(b, sizeof(b), "%pg", bdev);
 		ret = blk_trace_setup(q, b, bdev->bd_dev, bdev, arg);
-- 
2.51.0