On Wed, Jan 23, 2019 at 10:31:39PM +0100, Christoph Hellwig wrote:
> On Wed, Jan 23, 2019 at 05:30:49PM +0100, Joerg Roedel wrote:
> > + max_size = virtio_max_dma_size(vdev);
> > +
> > /* Host can optionally specify maximum segment size and number of
> > * segments. */
> > err = virtio_cread_feature(vdev, VIRTIO_BLK_F_SIZE_MAX,
> > struct virtio_blk_config, size_max, &v);
> > if (!err)
> > - blk_queue_max_segment_size(q, v);
> > - else
> > - blk_queue_max_segment_size(q, -1U);
> > + max_size = min(max_size, v);
> > +
> > + blk_queue_max_segment_size(q, max_size);
>
> I wonder if we should just move the dma max segment size check
> into blk_queue_max_segment_size so that all block drivers benefit
> from it. Even if not I think at least the SCSI midlayer should
> be updated to support it.
In that case the limit would also apply to virtio-blk even if it doesn't
use the DMA-API. If that is acceptable we can move the check to
blk_queue_max_segment_size().
Regards,
Joerg
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