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Date: Thu, 25 Mar 2010 01:34:02 -0400
From: john cooper <john.cooper@redhat.com>
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Subject: [Qemu-devel] [PATCH 4/4] Add virtio disk identification support
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To: Rusty Russell <rusty@rustcorp.com.au>
Cc: john.cooper@redhat.com, Marc Haber <mh+qemu-devel@zugschlus.de>, qemu-devel@nongnu.org

Return serial string to the guest application via
ioctl driver call.

Note this form of interface to the guest userland
was the consensus when the prior version using
the ATA_IDENTIFY came under dispute.

Signed-off-by: john cooper <john.cooper@redhat.com>
---

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index cd66806..0954193 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -225,6 +225,21 @@ static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
 	struct gendisk *disk = bdev->bd_disk;
 	struct virtio_blk *vblk = disk->private_data;
 
+	if (cmd == 'VBID') {
+		void *usr_data = (void __user *)data;
+		char *id_str;
+		int err;
+
+		if (!(id_str = kmalloc(VIRTIO_BLK_ID_BYTES, GFP_KERNEL)))
+			err = -ENOMEM;
+		else if ((err = virtblk_get_id(disk, id_str)))
+			;
+		else if (copy_to_user(usr_data, id_str, VIRTIO_BLK_ID_BYTES))
+			err = -EFAULT;
+		if (id_str)
+			kfree(id_str);
+		return err;
+	}
 	/*
 	 * Only allow the generic SCSI ioctls if the host can support it.
 	 */
-- 
john.cooper@redhat.com