Re: [libvirt] [PATCH] blockcopy: check dst = identical device

<eblake(a)redhat.com&gt; wrote: Update: 1. identical device with exactly the same spelled name. e.g. source is /dev/sda4, dest is /dev/sda4: * 'lockd' manager is working well with --reuse-external. * my previous testing result which makes the VM cannot be started successfully after doing blockcopy to same device and shutdown VM and start VM again, because I didn't add --reuse-external option. Then in code, it considers the dest as a new created file, when error happens, it unlinks the dest, which is actually also my source disk. 2. identical device with not exactly the same spelling. e.g. source is /dev/sda4, dest is /dev///sda4, or a softlink: 'lockd' manager is not working. Both hashtable check and fcntl can't give right result. * HashTable checks the resource in the locked list depending on the name. If name is not exactly the same, it will treat as 'not found in locked list'. * In fcntl stage, since fcntl is to one process, in the same process, do two times fcntl F_SETLK, both will succeed. Since everytime it's virtlockd tries fcntl, so in this case, 1st time fcntl /dev/sda4, it succeeds; 2nd time fcntl /dev///sda4, also succeeds. Not as we expected 'cannot get the lock'.