recovery: support for CLAIM_DELEGATE_PREV, DELEGPURGE

10.2.1. Delegation Recovery (re: client restart/lease expiration)
A server MAY support claim types of CLAIM_DELEGATE_PREV and CLAIM_DELEG_PREV_FH, and if it does, it MUST NOT remove delegations upon a CREATE_SESSION that confirm a client ID created by EXCHANGE_ID.  Instead, the server MUST, for a period of time no less than that of the value of the lease_time attribute, maintain the client's delegations to allow time for the client to send CLAIM_DELEGATE_PREV and/or CLAIM_DELEG_PREV_FH requests.  The server that supports CLAIM_DELEGATE_PREV and/or CLAIM_DELEG_PREV_FH MUST support the DELEGPURGE operation.

if there's a delegation to reclaim, recover_open_no_grace() now tries CLAIM_DELEGATE_PREV (supported by emc server, but not linux) before falling back to CLAIM_NULL
nfs41_client_delegation_recovery() sends DELEGPURGE to indicate that we're finished reclaiming delegations

Signed-off-by: Casey Bodley <cbodley@citi.umich.edu>

daemon/delegation.c

@@ -669,7 +669,15 @@ int nfs41_client_delegation_recovery(
         }
 
         if (status == NFS4ERR_BADSESSION)
-            break;
+            goto out;
     }
+
+    /* use DELEGPURGE to indicate that we're done reclaiming delegations */
+    status = nfs41_delegpurge(client->session);
+
+    /* support for DELEGPURGE is optional; ignore any errors but BADSESSION */
+    if (status != NFS4ERR_BADSESSION)
+        status = NFS4_OK;
+out:
     return status;
 }

daemon/nfs41_ops.c

@@ -1527,6 +1527,35 @@ out:
     return status;
 }
 
+int nfs41_delegpurge(
+    IN nfs41_session *session)
+{
+    int status;
+    nfs41_compound compound;
+    nfs_argop4 argops[2];
+    nfs_resop4 resops[2];
+    nfs41_sequence_args sequence_args;
+    nfs41_sequence_res sequence_res;
+    nfs41_delegpurge_res dp_res;
+
+    compound_init(&compound, argops, resops, "delegpurge");
+
+    compound_add_op(&compound, OP_SEQUENCE, &sequence_args, &sequence_res);
+    status = nfs41_session_sequence(&sequence_args, session, 0);
+    if (status)
+        goto out;
+
+    compound_add_op(&compound, OP_DELEGPURGE, NULL, &dp_res);
+
+    status = compound_encode_send_decode(session, &compound, TRUE);
+    if (status)
+        goto out;
+
+    compound_error(status = compound.res.status);
+out:
+    return status;
+}
+
 int nfs41_delegreturn(
     IN nfs41_session *session,
     IN nfs41_path_fh *file,

daemon/nfs41_ops.h

@@ -373,6 +373,12 @@ typedef struct __nfs41_create_res {
 } nfs41_create_res;
 
 
+/* OP_DELEGPURGE */
+typedef struct __nfs41_delegpurge_res {
+    uint32_t                status;
+} nfs41_delegpurge_res;
+
+
 /* OP_DELEGRETURN */
 typedef struct __nfs41_delegreturn_args {
     stateid_arg             *stateid;
@@ -1152,6 +1158,9 @@ int nfs41_access(
     OUT uint32_t *supported OPTIONAL,
     OUT uint32_t *access OPTIONAL);
 
+int nfs41_delegpurge(
+    IN nfs41_session *session);
+
 int nfs41_delegreturn(
     IN nfs41_session *session,
     IN nfs41_path_fh *file,

daemon/nfs41_xdr.c

@@ -1632,6 +1632,36 @@ static bool_t decode_op_locku(
 }
 
 
+/*
+ * OP_DELEGPURGE
+ */
+static bool_t encode_op_delegpurge(
+    XDR *xdr,
+    nfs_argop4 *argop)
+{
+    uint64_t zero = 0;
+
+    if (unexpected_op(argop->op, OP_DELEGPURGE))
+        return FALSE;
+
+    /* The client SHOULD set the client field to zero,
+     * and the server MUST ignore the clientid field. */
+    return xdr_u_int64_t(xdr, &zero);
+}
+
+static bool_t decode_op_delegpurge(
+    XDR *xdr,
+    nfs_resop4 *resop)
+{
+    nfs41_delegpurge_res *res = (nfs41_delegpurge_res*)resop->res;
+
+    if (unexpected_op(resop->op, OP_DELEGPURGE))
+        return FALSE;
+
+    return xdr_u_int32_t(xdr, &res->status);
+}
+
+
 /*
  * OP_DELEGRETURN
  */
@@ -3347,7 +3377,7 @@ static const op_table_entry g_op_table[] = {
     { encode_op_close, decode_op_close }, /* OP_CLOSE = 4 */
     { encode_op_commit, decode_op_commit }, /* OP_COMMIT = 5 */
     { encode_op_create, decode_op_create }, /* OP_CREATE = 6 */
-    { NULL, NULL }, /* OP_DELEGPURGE = 7 */
+    { encode_op_delegpurge, decode_op_delegpurge }, /* OP_DELEGPURGE = 7 */
     { encode_op_delegreturn, decode_op_delegreturn }, /* OP_DELEGRETURN = 8 */
     { encode_op_getattr, decode_op_getattr }, /* OP_GETATTR = 9 */
     { encode_op_getfh, decode_op_getfh }, /* OP_GETFH = 10 */

daemon/recovery.c

@@ -101,8 +101,22 @@ static int recover_open_no_grace(
     OUT open_delegation4 *delegation)
 {
     open_claim4 claim;
+    int status;
 
-    /* TODO: try CLAIM_DELEGATE_PREV / CLAIM_DELEG_PREV_FH first */
+    if (delegate_type != OPEN_DELEGATE_NONE) {
+        /* attempt out-of-grace recovery with CLAIM_DELEGATE_PREV */
+        claim.claim = CLAIM_DELEGATE_PREV;
+        claim.u.deleg_prev.filename = &file->name;
+
+        status = nfs41_open(session, parent, file, owner,
+            &claim, access, deny, OPEN4_NOCREATE, 0, 0, FALSE,
+            stateid, delegation, NULL);
+        if (status == NFS4_OK || status == NFS4ERR_BADSESSION)
+            goto out;
+
+        /* server support for CLAIM_DELEGATE_PREV is optional;
+         * fall back to CLAIM_NULL on errors */
+    }
 
     /* attempt out-of-grace recovery with CLAIM_NULL */
     claim.claim = CLAIM_NULL;
@@ -114,9 +128,11 @@ static int recover_open_no_grace(
     else if (delegate_type == OPEN_DELEGATE_WRITE)
         access |= OPEN4_SHARE_ACCESS_WANT_WRITE_DELEG;
 
-    return nfs41_open(session, parent, file, owner,
+    status = nfs41_open(session, parent, file, owner,
         &claim, access, deny, OPEN4_NOCREATE, 0, 0, FALSE,
         stateid, delegation, NULL);
+out:
+    return status;
 }
 
 static int recover_open(