Changes

== Unix sockets initial support ==

== Unix sockets initial support ==

Currently it can only work with stream and dgram sockets, which have no skbs in queues

Currently we support Unix socket of all kinds, UDP both IPv4 and IPv6, TCP in Listen and (!) [[TCP connection|Established states]] and Netlink ones.

(listening or established -- both work OK). If there are skbs in queue the dumping

procedure will fail.

The cpt part uses the sock_diag engine that was merged to Dave recently to

The cpt part uses the sock_diag engine to collect extended information about socket, then CRIU uses the files dumping engine to get access to sockets state.

collect sockets. Then it dumps sockets by checking the filesystem ID of a

failed-to-open through /proc/pid/fd descriptors (sockets do not allow for

such tricks with opens through proc) against SOCKFS_TYPE.

The restore part is more tricky. Listen sockets are just restored, this is simple.

The restore part of Unix sockets is the most tricky part. Listen sockets are just restored, this is simple.

Connected sockets are restored like this:

Connected sockets are restored like this:

# ... all listening sockets call accept() and ... dup2 the new fd into the accepting end.

# ... all listening sockets call accept() and ... dup2 the new fd into the accepting end.

There's a problem with this approach -- socket names are not preserved, but

There's a problem with this approach -- socket names are not preserved, but looking into our OpenVZ implementation I think this is OK for existing apps.

looking into our OpenVZ implementation I think this is OK for existing apps.

[[Category:Under the hood]]

 

[[Category:Sockets]]

* Need to merge the file IDs patches in our tree and make Andrey to support files sharing. This will solve the

 

 

case. Currently it simply doesn't work :(