On 07/28/2012 02:42 PM, Paolo Bonzini wrote:
I'm not sure what the correct behavior for bio & cacheflush is, if
any.
REQ_FLUSH is not supported in the bio path.
Ouch, that's correct:
@@ -414,7 +529,7 @@ static void virtblk_update_cache_mode(struct virtio_device
*vdev)
u8 writeback = virtblk_get_cache_mode(vdev);
struct virtio_blk *vblk = vdev->priv;
- if (writeback)
+ if (writeback && !use_bio)
blk_queue_flush(vblk->disk->queue, REQ_FLUSH);
else
blk_queue_flush(vblk->disk->queue, 0);
then it is not safe against power losses.
Yes. Something like this:
qemu -drive file=foo.img,cache=writeback/unsafe
is not safe against power losses also?
I think we can add REQ_FLUSH & REQ_FUA support to bio path and that
deserves another patch.
--
Asias
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