This is kind of a big batch of patches, but they all depend on eachother so it was hard to tease out the fixes from the enhancements without making my life miserable. FIXES: nbd: set queue timeout properly nbd: handle ERESTARTSYS properly The ERSTARTSYS one in particular is pretty awful as we can tear down a whole device if a userspace app has a signal pending while submitting IO. This is big and scary but I had a debug patch on top of this to randomly induce ERESTARTSYS to make sure it was behaving properly. ENHANCEMENTS: 1) Handle signle path failures gracefully. This is the first step to handling reconnects gracefully, but for right now we can easily fall back on other connections if we happen to lose one connection. 2) Ref counting and bdev change. This is in preparation for the netlink patch and handling reconnects and the such better. 3) Netlink interface. Trying to add the nbd-control thing was controversial, and I realized the more I wanted to do with monitoring and stuff I would need to use netlink for anyway. With this new interface we can easily configure and disconnect devices, dynamically add devices if we are past our pre-allocated limit, and dynamically find free devices to use if we don't want to try and hunt for a device. The userspace patch to utilize this is kind of rough but can be found in my github tree https://github.com/josefbacik/nbd These have been pretty well tested, but I'd like to hear any thoughts on the new interface. Thanks, Josef
