We now print disk probe information like:

virtio-scsi: Add scsi device target=1, lun=0   as vblk0, devsize=10842275840

Disable it by default. The --verbose option will make this info
available which is useful when debug.

Reported-by: Pekka Enberg <penberg@cloudius-systems.com>
Signed-off-by: Asias He <asias@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>

Set req->cdb_len to the actual size of the scsi command and only copy
the actual size of the command.

This reduces the number of bytes we copy.

This also fixes the warning in pvscsi which complains the size of the
cdb is larger than expected.

Signed-off-by: Asias He <asias@cloudius-systems.com>

This is used to tell lower-level scsi driver to free the request,
otherwise the scsi layer will free the request.

read/write/flush scsi are async request, they are freed by the
lower-level scsi driver. Other scsi request are freed by the scsi layer.

Signed-off-by: Asias He <asias@cloudius-systems.com>

This eliminates duplicated code in make_request() of scsi driver.

Signed-off-by: Asias He <asias@cloudius-systems.com>

VMware supports only 1 lun per target. Limit the max_lun to speed up
probe.

Signed-off-by: Asias He <asias@cloudius-systems.com>

Use this to limit max number of target to scan.

Signed-off-by: Asias He <asias@cloudius-systems.com>

This driver is for VMware's pvscsi disk. It has better performance than
using AHCI device in VMware. This driver uses the common scsi code in
scsi-common.

This driver is written from scratch. QEMU and Linux pvscsi drivers were
used as reference as there's no specification available.

Tested on QEMU's pvscsi implementation and VMware Workstation.

Signed-off-by: Asias He <asias@cloudius-systems.com>