This patch series enables AF_VSOCK address family support in the NFS client. You can also get the commits from the vsock-nfs branch at https://github.com/stefanha/linux.git. The AF_VSOCK address family provides dgram and stream socket communication between virtual machines and hypervisors. VMware VMCI and virtio (for KVM) transports are available, see net/vmw_vsock. The goal of this work is sharing files between virtual machines and hypervisors. AF_VSOCK is well-suited to this because it requires no configuration inside the virtual machine, making it simple to manage and reliable. Why NFS over AF_VSOCK? ---------------------- It is unusual to add a new NFS transport, only TCP, RDMA, and UDP are currently supported. Here is the rationale for adding AF_VSOCK. Sharing files with a virtual machine can be configured manually: 1. Add a dedicated network card to the virtual machine. It will be used for NFS traffic. 2. Configure a local subnet and assign IP addresses to the virtual machine and hypervisor 3. Configure an NFS export on the hypervisor and start the NFS server 4. Mount the export inside the virtual machine Automating these steps poses a problem: modifying network configuration inside the virtual machine is invasive. It's hard to add a network interface to an arbitrary running system in an automated fashion, considering the network management tools, firewall rules, IP address usage, etc. Furthermore, the user may disrupt file sharing by accident when they add firewall rules, restart networking, etc because the NFS network interface is visible alongside the network interfaces managed by the user. AF_VSOCK is a zero-configuration network transport that avoids these problems. Adding it to a virtual machine is non-invasive. It also avoids accidental misconfiguration by the user. This is why "guest agents" and other services in various hypervisors (KVM, Xen, VMware, VirtualBox) do not use regular network interfaces. This is why AF_VSOCK is appropriate for providing shared files as a hypervisor service. The approach in this series --------------------------- AF_VSOCK stream sockets can be used for NFSv4.1 much in the same way as TCP. RFC 1831 record fragments divide messages since SOCK_STREAM semantics are present. The backchannel shares the connection just like the default TCP configuration. Addresses are <Context ID, Port Number> pairs. These patches use "vsock:<cid>" string representation to distinguish AF_VSOCK addresses from IPv4 and IPv6 numeric addresses. The following example mounts /export from the hypervisor (CID 2) inside the virtual machine (CID 3): # /sbin/mount.nfs 2:/export /mnt -o clientaddr=3,proto=vsock Please see the nfs-utils patch series I have just sent to linux-nfs@xxxxxxxxxxxxxxx for the necessary patches. Status ------ The virtio-vsock transport was merged in Linux 4.8 and the vhost-vsock-pci device is available in QEMU git master. This means the underlying AF_VSOCK transport for KVM is now available upstream. I have begun work on nfsd support in the kernel and nfs-utils. This is not complete yet and will be sent as separate patch series. Stefan Hajnoczi (10): SUNRPC: add AF_VSOCK support to addr.[ch] SUNRPC: rename "TCP" record parser to "stream" parser SUNRPC: abstract tcp_read_sock() in record fragment parser SUNRPC: extract xs_stream_reset_state() VSOCK: add tcp_read_sock()-like vsock_read_sock() function SUNRPC: add AF_VSOCK support to xprtsock.c SUNRPC: drop unnecessary svc_bc_tcp_create() helper SUNRPC: add AF_VSOCK support to svc_xprt.c SUNRPC: add AF_VSOCK backchannel support NFS: add AF_VSOCK support to NFS client drivers/vhost/vsock.c | 1 + fs/nfs/client.c | 2 + fs/nfs/super.c | 11 +- include/linux/sunrpc/addr.h | 44 ++ include/linux/sunrpc/svc_xprt.h | 12 + include/linux/sunrpc/xprt.h | 1 + include/linux/sunrpc/xprtsock.h | 36 +- include/linux/virtio_vsock.h | 4 + include/net/af_vsock.h | 5 + include/trace/events/sunrpc.h | 28 +- net/sunrpc/Kconfig | 10 + net/sunrpc/addr.c | 57 +++ net/sunrpc/svc_xprt.c | 18 + net/sunrpc/svcsock.c | 48 ++- net/sunrpc/xprtsock.c | 703 +++++++++++++++++++++++++------- net/vmw_vsock/af_vsock.c | 16 + net/vmw_vsock/virtio_transport.c | 1 + net/vmw_vsock/virtio_transport_common.c | 66 +++ net/vmw_vsock/vmci_transport.c | 8 + 19 files changed, 880 insertions(+), 191 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
