vfs: improve writing to be atomic
vfs: improve writing to be atomic

Write to temp file first, then rename

nickvanw/convoy,rancherio/volmgr,rancher/rancher-volume,rancherio/rancher-volume,moypray/convoy,rancher/rancher-volume,rancher/rancher-volume,nickvanw/convoy,nickvanw/convoy,aruneli/convoy,jinuxstyle/convoy,rancherio/volmgr,rancher/convoy,dx9/convoy,rancher/convoy,dx9/convoy,aruneli/convoy,rancherio/rancher-volume,rancherio/volmgr,rancherio/rancher-volume,dx9/convoy,jinuxstyle/convoy,mehulsbhatt/convoy,jinuxstyle/convoy,mehulsbhatt/convoy,medallia/convoy,moypray/convoy,medallia/convoy,moypray/convoy,mehulsbhatt/convoy,medallia/convoy,aruneli/convoy,rancher/convoy