Add serial number support for virtio_blk, V3

[Rework of earlier patch, 2/2 modified to use an existing interface]

This patch allows passing of a virtio_blk drive serial number from qemu into a guest's virtio_blk driver, and provides a means to access the serial number from a guest's userspace.

Equivalent functionality currently exists for IDE and SCSI, however it is not yet implemented for virtio. Scenarios exist where guest code relies on a unique drive serial number to correctly identify the machine environment in which it exists.

The following two patches implement the above:

qemu-vblk-serial-3.patch

which provides the qemu missing bits to interpret a '-drive .. serial=XYZ ..' flag, and:

virtio_blk-serial-3.patch

which extracts this information and makes it available to guest userspace via an HDIO_GET_IDENTITY ioctl, eg: 'hdparm -i /dev/vda'.

The above patches are relative to qemu-kvm.git and 2.6.29.3 respectively.

-john

[email protected]