Re: [PATCH 4/6] virtio block driver

Jens Axboe
2007-09-20T12:27:13Z

On Thu, Sep 20 2007, Rusty Russell wrote:
> 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().

They should, if they imply a data transfer.

> Although we try to reply -ENOTTY on unsupported commands, the block
> layer in its infinite wisdom suppressed the error so ioctl(fd,
> CDROMEJECT) returns success to userspace.

How about ever submitting a patch for that, instead of just repeatedly
complaining about it?

--
Jens Axboe