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>

2 files changed, 14 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,
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 405dfadcbc3b..8fe5b940c5f2 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1088,6 +1088,19 @@ struct nfs4_secinfo_res {
         struct nfs4_secinfo_flavors     *flavors;
 };
 
+struct nfs4_fsid_present_arg {
+        struct nfs4_sequence_args       seq_args;
+        const struct nfs_fh             *fh;
+        clientid4                       clientid;
+        unsigned char                   renew:1;
+};
+
+struct nfs4_fsid_present_res {
+        struct nfs4_sequence_res        seq_res;
+        struct nfs_fh                   *fh;
+        unsigned char                   renew:1;
+};
+
 #endif /* CONFIG_NFS_V4 */
 
 struct nfstime4 {