NFS: Add method to detect whether an FSID is still on the server

Introduce a mechanism for probing a server to determine if an FSID
is present or absent.

The on-the-wire compound is different between minor version 0 and 1.
Minor version 0 appends a RENEW operation to identify which client
ID is probing.  Minor version 1 has a SEQUENCE operation in the
compound which effectively carries the same information.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index e36dee52f224..c56fa8fedce9 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -460,6 +460,7 @@ enum {
         NFSPROC4_CLNT_FS_LOCATIONS,
         NFSPROC4_CLNT_RELEASE_LOCKOWNER,
         NFSPROC4_CLNT_SECINFO,
+        NFSPROC4_CLNT_FSID_PRESENT,
 
         /* nfs41 */
         NFSPROC4_CLNT_EXCHANGE_ID,