Description of problem:
VDO's post-suspend function does a flush to the storage under it. It allocates memory to do this flush, and does not enter read-only mode if it gets an error on this flush. It shouldn't allocate, and should enter read-only.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Make VDO suspend in a memory-constrained environment, or where it gets an io error on its final flush.
Observe hanging for mem allocation, or failure to enter read only mode.
No memory allocation, and read-only mode upon error.
Regression testing passed with following versions: