Red Hat Bugzilla – Bug 526869
Add virtio_blk support cache flush (VIRTIO_BLK_F_FLUSH)
Last modified: 2009-10-06 10:45:45 EDT
See discussion in bug #525890
We should backport:
virtio_blk: add support for cache flush
Recent qemu has added a VIRTIO_BLK_F_FLUSH flag to advertise that the
virtual disk has a volatile write cache that needs to be flushed. In case
we see this feature implement tell the Linux block layer about the fact
and use the new VIRTIO_BLK_T_FLUSH to flush the cache when required. This
allows for an correct and simple implementation of write barriers.
This mail from Christoph is a good writeup on the background:
We should get this into F-12 GA even if qemu doesn't yet support it in F-12 so that F-12 guest installer kernels have this feature.
This has been added to the F-12 kernel and should be available in the next kernel tagged.