The lvm(8) family of commands can leave a truncated /etc/lvm/.cache file if the 
root filesystem becomes full while the file is being written. If the system is 
rebooted at that point it will fail to boot because the subsequent vgscan(8) 
will croak when it attempts to parse the incomplete cache file.

The problem is that the persistent_filter_dump() function does not check the 
return value of any of the writes or fclose(). In fact, simply checking the 
return value of the fclose() and not renaming the temporary file if the close 
fails should be sufficient. This obviously assumes persistent_filter_dump() has 
already been augmented to write to a temporary file and call rename() before 
returning (a change that has already been submitted).