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 <kw...@redhat.com> Reviewed-by: Benoit Canet <ben...@irqsave.net> Acked-by: Paolo Bonzini <pbonz...@redhat.com> --- 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; } -- 1.8.1.4
