[PATCH 2/2] Add serial number support for virtio_blk, V2

[john cooper <john.cooper@redhat.com>]

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john.cooper@redhat.com


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 drivers/block/virtio_blk.c |   35 ++++++++++++++++++++++++++++++++---
 include/linux/virtio_blk.h |   10 ++++++++++
 2 files changed, 42 insertions(+), 3 deletions(-)
=================================================================
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -146,12 +146,40 @@ static void do_virtblk_request(struct re
 		vblk->vq->vq_ops->kick(vblk->vq);
 }
 
+/* user passes the address of a char[] for serial# return, and has set char[0]
+ * to the array size.  copy serial# to this char[] and return number of
+ * characters copied excluding any trailing '\0' pad chars in buffer.
+ */
+static int get_virtblk_sn(struct block_device *bdev, void *buf)
+{
+	struct virtio_blk *vblk = bdev->bd_disk->private_data;
+	unsigned char serial[BLOCK_SERIAL_STRLEN];
+	unsigned char snlen;
+	int rv;
+
+	if (copy_from_user(&snlen, buf, sizeof (snlen)))
+		rv = -EFAULT;
+	else if ((rv = virtio_config_val(vblk->vdev, VIRTIO_BLK_F_SN,
+		offsetof(struct virtio_blk_config, serial), &serial)))
+			;
+	else if (copy_to_user(buf, serial,
+		snlen = min(snlen, (unsigned char)sizeof (serial))))
+			rv = -EFAULT;
+	else
+		for (rv = 0; rv < snlen; ++rv)
+			if (!serial[rv])
+				break;
+	return (rv);
+}
+
 static int virtblk_ioctl(struct block_device *bdev, fmode_t mode,
 			 unsigned cmd, unsigned long data)
 {
-	return scsi_cmd_ioctl(bdev->bd_disk->queue,
-			      bdev->bd_disk, mode, cmd,
-			      (void __user *)data);
+	if (cmd == VBLK_GET_SN)
+		return (get_virtblk_sn(bdev, (void __user *)data));
+	else
+		return scsi_cmd_ioctl(bdev->bd_disk->queue, bdev->bd_disk,
+			mode, cmd, (void __user *)data);
 }
 
 /* We provide getgeo only to please some old bootloader/partitioning tools */
@@ -356,6 +384,7 @@ static struct virtio_device_id id_table[
 static unsigned int features[] = {
 	VIRTIO_BLK_F_BARRIER, VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX,
 	VIRTIO_BLK_F_GEOMETRY, VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
+	VIRTIO_BLK_F_SN
 };
 
 static struct virtio_driver virtio_blk = {
=================================================================
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -15,7 +15,16 @@
 #define VIRTIO_BLK_F_GEOMETRY	4	/* Legacy geometry available  */
 #define VIRTIO_BLK_F_RO		5	/* Disk is read-only */
 #define VIRTIO_BLK_F_BLK_SIZE	6	/* Block size of disk is available*/
+#define VIRTIO_BLK_F_SN		8	/* serial number supported */
 
+/* ioctl cmd to retrieve serial#
+*/
+#define VBLK_GET_SN ((unsigned int)('V' << 24 | 'B' << 16 | 'L' << 8 | 'K'))
+
+#define BLOCK_SERIAL_STRLEN 20
+
+/* mapped into pci i/o region 0
+ */
 struct virtio_blk_config
 {
 	/* The capacity (in 512-byte sectors). */
@@ -32,6 +41,7 @@ struct virtio_blk_config
 	} geometry;
 	/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
 	__u32 blk_size;
+	__u8 serial[BLOCK_SERIAL_STRLEN];
 } __attribute__((packed));
 
 /* These two define direction. */