Re: [Qemu-devel] [PATCH 1/2] iscsi: Use bs->sg for everything else than disks

[Peter Lieven]

Am 05.03.2014 16:00, schrieb Kevin Wolf:
> The current iscsi block driver code makes the rather arbitrary decision
> that TYPE_MEDIUM_CHANGER and TYPE_TAPE devices have bs->sg = 1 and all
> other device types are disks.
>
> Instead of this, check for TYPE_DISK to expose the disk interface and
> make everything else bs->sg = 1. In particular, this includes devices
> with TYPE_STORAGE_ARRAY, which is what LUN 0 of an iscsi target is.
> (See https://bugzilla.redhat.com/show_bug.cgi?id=1067784 for the exact
> scenario.)
>
> Signed-off-by: Kevin Wolf <address@hidden>
> ---
>  block/iscsi.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/block/iscsi.c b/block/iscsi.c
> index 0a15f53..b490e98 100644
> --- a/block/iscsi.c
> +++ b/block/iscsi.c
> @@ -1231,12 +1231,11 @@ static int iscsi_open(BlockDriverState *bs, QDict 
> *options, int flags,
>      bs->total_sectors = sector_lun2qemu(iscsilun->num_blocks, iscsilun);
>      bs->request_alignment = iscsilun->block_size;
>  
> -    /* Medium changer or tape. We dont have any emulation for this so this 
> must
> -     * be sg ioctl compatible. We force it to be sg, otherwise qemu will try
> -     * to read from the device to guess the image format.
> +    /* We don't have any emulation for devices other than disks and CD-ROMs, 
> so
> +     * this must be sg ioctl compatible. We force it to be sg, otherwise qemu
> +     * will try to read from the device to guess the image format.
>       */
> -    if (iscsilun->type == TYPE_MEDIUM_CHANGER ||
> -        iscsilun->type == TYPE_TAPE) {
> +    if (iscsilun->type != TYPE_DISK && iscsilun->type != TYPE_ROM) {
>          bs->sg = 1;
>      }
>  
We have ioctl support in the iscsi block driver only for Linux. Is this a 
problem?

Peter