On Mon, Jul 09, 2012 at 04:33:25PM -0000, Peter Petrakis wrote: > I'm not familiar with the cookie feature you mentioned, but we appear to have > some of the > capability here. I haven't compared it to upstream yet. The code issuing the removal ioctl specfies a cookie (a semaphore with a positive value). It then waits until the semaphore drops to 0.
The last thing the udev rules do after they've updated /dev is decrement the semaphore, which wakes up the original code. There are libdevmapper calls and dmsetup commands to update/query cookie state. udev 'watch' rules can run out-of-band and need careful configuration to avoid problems. If libvirt is issuing dm ioctls or dmsetup commands itself then it might also need to be udevcookie-aware - not something that's arisen in any discussions yet - there is some default udevcookie handling built into dmsetup commands. I was assured the upstream multipath udevcookie support was complete, but I've not verified that personally - perhaps we have a situation that's overlooked here. -- You received this bug notification because you are a member of Ubuntu Server Team, which is subscribed to multipath-tools in Ubuntu. https://bugs.launchpad.net/bugs/585027 Title: Race condition with dmsetup causes 'map already present' messages To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/multipath-tools/+bug/585027/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs
