Block driver using virtio.
The block driver uses scatter-gather lists with sg[0] being the
request information (struct virtio_blk_outhdr) with the type, sector
and inbuf id. The next N sg entries are the bio itself, then the last
sg is the status byte. Whether the N entries are in or out depends on
whether it's a read or a write.
We accept the normal (SCSI) ioctls: they get handed through to the other
side which can then handle it or reply that it's unsupported. It's
not clear that this actually works in general, since I don't know
if blk_pc_request() requests have an accurate rq_data_dir().
Although we try to reply -ENOTTY on unsupported commands, ioctl(fd,
CDROMEJECT) returns success to userspace. This needs a separate
patch.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index ce4b1e4..4d0119e 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -425,4 +425,10 @@
block device driver. It communicates with a back-end driver
in another domain which drives the actual block device.
+config VIRTIO_BLK
+ tristate "Virtio block driver (EXPERIMENTAL)"
+ depends on EXPERIMENTAL && VIRTIO
+ ---help---
+ This is the virtual block driver for lguest. Say Y or M.
+
endif # BLK_DEV