config logging, which is usefull when error happens, otherwise the error message printing will cause the exit of the application
allocate dataspace when creating image
set no_thread to True, otherwise it causes problem even when only one hypervisor is allowed. It seems that the operating system will use multi-threads to accomplish a single operation. To reproduce the error: execute "qemu-img info image01", three pairs of open/release are issued, and they may not be in sequence. Execute the command a few times, eventually something like: open1/open2/release1/release2 may happen and then the fuse fails.
rtt
revert the setting of creating file when creating image
merge the changes from shima-san
minor change: remove unused import
add total storage size query
remove the debug printing