linux-next: manual merge of the block tree with the rr tree
in [Kernel]
|
Prev: net/ne: fix memory leak in ne_drv_probe()
Next: linux-next: manual merge of the device-mapper tree with the block tree
From: Stephen Rothwell on 6 Jul 2010 00:30 Hi Jens, Today's linux-next merge of the block tree got a conflict in drivers/block/virtio_blk.c between commit 0e41b2d3ea0f5bf472a2b163c54305f62ab7b776 ("virtio_blk: support barriers without FLUSH feature") from the rr tree and commits 3789fdefa13bcaa7ad06d952ac6010f0a81bf04e ("virtio_blk: stop using q->prepare_flush_fn") and 5e27e27e73b5bff903b3c30ffd5a0e17eb95c087 ("block: remove q->prepare_flush_fn completely") from the block tree. I fixed it up (see below) and can carry the fix as necessary. -- Cheers, Stephen Rothwell sfr(a)canb.auug.org.au diff --cc drivers/block/virtio_blk.c index 23b7c48,0a3222f..0000000 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@@ -377,32 -364,11 +375,31 @@@ static int __devinit virtblk_probe(stru vblk->disk->driverfs_dev = &vdev->dev; index++; - /* If barriers are supported, tell block layer that queue is ordered */ - if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) + if (virtio_has_feature(vdev, VIRTIO_BLK_F_FLUSH)) { + /* + * If the FLUSH feature is supported we do have support for + * flushing a volatile write cache on the host. Use that + * to implement write barrier support. + */ - blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH, - virtblk_prepare_flush); + blk_queue_ordered(q, QUEUE_ORDERED_DRAIN_FLUSH); - else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) + } else if (virtio_has_feature(vdev, VIRTIO_BLK_F_BARRIER)) { + /* + * If the BARRIER feature is supported the host expects us + * to order request by tags. This implies there is not + * volatile write cache on the host, and that the host + * never re-orders outstanding I/O. This feature is not + * useful for real life scenarious and deprecated. + */ - blk_queue_ordered(q, QUEUE_ORDERED_TAG, NULL); + blk_queue_ordered(q, QUEUE_ORDERED_TAG); + } else { + /* + * If the FLUSH feature is not supported we must assume that + * the host does not perform any kind of volatile write + * caching. We still need to drain the queue to provider + * proper barrier semantics. + */ - blk_queue_ordered(q, QUEUE_ORDERED_DRAIN, NULL); ++ blk_queue_ordered(q, QUEUE_ORDERED_DRAIN); + } /* If disk is read-only in the host, the guest should obey */ if (virtio_has_feature(vdev, VIRTIO_BLK_F_RO)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |