linux-kernel - Re: [PATCH 15/24] compat_ioctl: scsi: move ioctl handling into drivers

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Date:   Thu, 12 Dec 2019 10:17:44 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        Jens Axboe <axboe@...nel.dk>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jason Wang <jasowang@...hat.com>,
        Doug Gilbert <dgilbert@...erlog.com>,
        Kai Mäkisara <Kai.Makisara@...umbus.fi>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        y2038 Mailman List <y2038@...ts.linaro.org>,
        Stefan Hajnoczi <stefanha@...hat.com>,
        Bart Van Assche <bvanassche@....org>,
        Hannes Reinecke <hare@...e.com>,
        Damien Le Moal <damien.lemoal@....com>,
        John Garry <john.garry@...wei.com>,
        virtualization@...ts.linux-foundation.org,
        linux-block <linux-block@...r.kernel.org>,
        linux-scsi <linux-scsi@...r.kernel.org>,
        Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 15/24] compat_ioctl: scsi: move ioctl handling into drivers

On Thu, Dec 12, 2019 at 1:28 AM Paolo Bonzini <pbonzini@...hat.com> wrote:
> On 12/12/19 00:05, Michael S. Tsirkin wrote:
> >> @@ -405,6 +405,9 @@ static int virtblk_getgeo(struct block_device *bd, struct hd_geometry *geo)
> >>
> >>  static const struct block_device_operations virtblk_fops = {
> >>      .ioctl  = virtblk_ioctl,
> >> +#ifdef CONFIG_COMPAT
> >> +    .compat_ioctl = blkdev_compat_ptr_ioctl,
> >> +#endif
> >>      .owner  = THIS_MODULE,
> >>      .getgeo = virtblk_getgeo,
> >>  };
> > Hmm - is virtio blk lumped in with scsi things intentionally?
>
> I think it's because the only ioctl for virtio-blk is SG_IO.  It makes
> sense to lump it in with scsi, but I wouldn't mind getting rid of
> CONFIG_VIRTIO_BLK_SCSI altogether.

It currently calls scsi_cmd_blk_ioctl(), which implements a bunch of ioctl
commands, including some that are unrelated to SG_IO:

                case SG_GET_VERSION_NUM:
                case SCSI_IOCTL_GET_IDLUN:
                case SCSI_IOCTL_GET_BUS_NUMBER:
                case SG_SET_TIMEOUT:
                case SG_GET_TIMEOUT:
                case SG_GET_RESERVED_SIZE:
                case SG_SET_RESERVED_SIZE:
                case SG_EMULATED_HOST:
                case SG_IO: {
                case CDROM_SEND_PACKET:
                case SCSI_IOCTL_SEND_COMMAND:
                case CDROMCLOSETRAY:
                case CDROMEJECT:

My patch changes all callers of this function, and the idea is
to preserve the existing behavior through my series, so I think
it makes sense to keep my patch as is.

I would assume that calling scsi_cmd_blk_ioctl() is harmless
here, but if you want to remove it or limit the set of supported
commands, that should be independent of my change.

       Arnd