[PATCH] virtio_blk: support barriers without FLUSH feature

2010-06-15 Thread Christoph Hellwig
If we want to support barriers with the cache=writethrough mode in qemu we need to tell the block layer that we only need queue drains to implement a barrier. Follow the model set by SCSI and IDE and assume that there is no volatile write cache if the host doesn't advertize it. While this might

Re: [PATCH] virtio_blk: support barriers without FLUSH feature

2010-06-15 Thread Rusty Russell
On Tue, 15 Jun 2010 10:13:48 pm Christoph Hellwig wrote: If we want to support barriers with the cache=writethrough mode in qemu we need to tell the block layer that we only need queue drains to implement a barrier. Follow the model set by SCSI and IDE and assume that there is no volatile