This patch fixes two issues with persistent grants and the disk PV backend
(Qdisk):
- Keep track of memory regions where persistent grants have been mapped
since we need to unmap them as a whole. It is not possible to unmap a
single grant if it has been batch-mapped. A new check has also been added
to make sure persistent grants are only used if the whole mapped region
can be persistently mapped in the batch_maps case.
- Unmap persistent grants before switching to the closed state, so the
frontend can also free them.
Signed-off-by: Roger Pau Monné <address@hidden>
Reported-by: George Dunlap <address@hidden>