Commit a5eb9e4f authored Jun 23, 2010 by Ryan Harper Committed by Rusty Russell Aug 05, 2010

virtio_blk: Add 'serial' attribute to virtio-blk devices (v2)



Create a new attribute for virtio-blk devices that will fetch the serial number
of the block device.  This attribute can be used by udev to create disk/by-id
symlinks for devices that don't have a UUID (filesystem) associated with them.

ATA_IDENTIFY strings are special in that they can be up to 20 chars long
and aren't required to be nul-terminated.  The buffer is also zero-padded
meaning that if the serial is 19 chars or less that we get a nul-terminated
string.  When copying this value into a string buffer, we must be careful to
copy up to the nul (if it present) and only 20 if it is longer and not to
attempt to nul terminate; this isn't needed.

Changes since v1:
- Added BUILD_BUG_ON() for PAGE_SIZE check
- Removed min() since BUILD_BUG_ON() handles the check
- Replaced serial_sysfs() by copying id directly to buffer

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>
Signed-off-by: john cooper <john.cooper@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

parent 10bc310c

drivers/block/virtio_blk.c

+28 −0

Original line number	Diff line number	Diff line
		@@ -281,6 +281,27 @@ static int index_to_minor(int index)
		return index << PART_BITS;
		}

		static ssize_t virtblk_serial_show(struct device *dev,
		struct device_attribute attr, char buf)
		{
		struct gendisk *disk = dev_to_disk(dev);
		int err;

		/* sysfs gives us a PAGE_SIZE buffer */
		BUILD_BUG_ON(PAGE_SIZE < VIRTIO_BLK_ID_BYTES);

		buf[VIRTIO_BLK_ID_BYTES] = '\0';
		err = virtblk_get_id(disk, buf);
		if (!err)
		return strlen(buf);

		if (err == -EIO) /* Unsupported? Make it empty. */
		return 0;

		return err;
		}
		DEVICE_ATTR(serial, S_IRUGO, virtblk_serial_show, NULL);

		static int __devinit virtblk_probe(struct virtio_device *vdev)
		{
		struct virtio_blk *vblk;
		@@ -465,8 +486,15 @@ static int __devinit virtblk_probe(struct virtio_device *vdev)


		add_disk(vblk->disk);
		err = device_create_file(disk_to_dev(vblk->disk), &dev_attr_serial);
		if (err)
		goto out_del_disk;

		return 0;

		out_del_disk:
		del_gendisk(vblk->disk);
		blk_cleanup_queue(vblk->disk->queue);
		out_put_disk:
		put_disk(vblk->disk);
		out_mempool: