[PATCH] manpage: explain why showmount doesn't really work against a v4-only server

[Jeff Layton <jlayton@kernel.org>]

From: Jeff Layton <jlayton@redhat.com>

I occasionally see people that expect valid info when running showmount
against a server that may export some or all filesystems via NFSv4.
Let's make it clear that it only works by talking to the remote MNT
service, and that that may not be available from a v4-only server.

Cc: Jan Fajerski <jfajerski@suse.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
---
 utils/showmount/showmount.man | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/utils/showmount/showmount.man b/utils/showmount/showmount.man
index a2f510fb5617..35818e1b61c5 100644
--- a/utils/showmount/showmount.man
+++ b/utils/showmount/showmount.man
@@ -56,5 +56,10 @@ Because
 .B showmount
 sorts and uniqs the output, it is impossible to determine from
 the output whether a client is mounting the same directory more than once.
+.P
+.B showmount
+works by contacting the server's MNT service directly. NFSv4-only servers have
+no need to advertise their exported root filehandles via this method, and may
+not expose their MNT service to clients.
 .SH AUTHOR
 Rick Sladkey <jrs@world.std.com>
-- 
2.21.0