[Midnightbsd-cvs] src [9385] trunk/usr.sbin/nfsd/nfsv4.4: Document the fact that an NFSv4 mount against a volume on the same host

[laffer1 at midnightbsd.org]

Revision: 9385
          http://svnweb.midnightbsd.org/src/?rev=9385
Author:   laffer1
Date:     2017-03-04 15:37:23 -0500 (Sat, 04 Mar 2017)
Log Message:
-----------
Document the fact that an NFSv4 mount against a volume on the same host
can result in a hung NFS server and is not recommended.
This is a content change.

Modified Paths:
--------------
    trunk/usr.sbin/nfsd/nfsv4.4

Modified: trunk/usr.sbin/nfsd/nfsv4.4
===================================================================
--- trunk/usr.sbin/nfsd/nfsv4.4	2017-03-04 20:36:59 UTC (rev 9384)
+++ trunk/usr.sbin/nfsd/nfsv4.4	2017-03-04 20:37:23 UTC (rev 9385)
@@ -24,7 +24,7 @@
 .\"
 .\" $MidnightBSD$
 .\"
-.Dd December 23, 2012
+.Dd May 1, 2013
 .Dt NFSV4 4
 .Os
 .Sh NAME
@@ -289,6 +289,13 @@
 daemons at boot time via the ``nfsuserd_flags'' and ``nfscbd_flags''
 .Xr rc.conf 5
 variables.
+.Pp
+NFSv4 mount(s) against exported volume(s) on the same host are not recommended,
+since this can result in a hung NFS server.
+It occurs when an nfsd thread tries to do an NFSv4 VOP_RECLAIM()/Close RPC
+as part of acquiring a new vnode.
+If all other nfsd threads are blocked waiting for lock(s) held by this nfsd
+thread, then there isn't an nfsd thread to service the Close RPC.
 .Sh FILES
 .Bl -tag -width /var/db/nfs-stablerestart.bak -compact
 .It Pa /var/db/nfs-stablerestart