Introduce VOP_UNP_BIND(), VOP_UNP_CONNECT(), and VOP_UNP_DETACH()

operations for setting and accessing vnode's v_socket field.

The operations are necessary to implement proper unix socket handling
on layered file systems like nullfs(5).

This change fixes the long standing issue with nullfs(5) being in that
unix sockets did not work between lower and upper layers: if we bound
to a socket on the lower layer we could connect only to the lower
path; if we bound to the upper layer we could connect only to the
upper path. The new behavior is one can connect to both the lower and
the upper paths regardless what layer path one binds to.

PR:		kern/51583, kern/159663
Suggested by:	kib
Reviewed by:	arch
MFC after:	2 weeks

1 files changed, 8 insertions, 0 deletions

diff --git a/UPDATING b/UPDATING
index 9da1e29..edb8d76 100644
--- a/UPDATING
+++ b/UPDATING
@@ -22,6 +22,14 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 10.x IS SLOW:
 	machines to maximize performance.  (To disable malloc debugging, run
 	ln -s aj /etc/malloc.conf.)
 
+20120229:
+	Now unix domain sockets behave "as expected" on	nullfs(5). Previously
+	nullfs(5) did not pass through all behaviours to the underlying layer,
+	as a result if we bound to a socket on the lower layer we could connect
+	only to the lower path; if we bound to the upper layer we could connect
+	only to	the upper path. The new behavior is one can connect to both the
+	lower and the upper paths regardless what layer path one binds to.
+
 20120211:
 	The getifaddrs upgrade path broken with 20111215 has been restored.
 	If you have upgraded in between 20111215 and 20120209 you need to