recovery: support for WANT_DELEGATION

for delegations without an associated open, try the optional WANT_DELEGATION operation with CLAIM_PREVIOUS before falling back to OPEN/CLAIM_PREVIOUS.  the advantage of WANT_DELEGATION is that it doesn't generate an open stateid, so we don't need the corresponding CLOSE as in recover_delegation_open().  if WANT_DELEGATION fails with NFS4ERR_NOTSUPP, don't try it again during that round of state recovery

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

daemon/nfs41_ops.c

@@ -1527,6 +1527,50 @@ out:
     return status;
 }
 
+enum nfsstat4 nfs41_want_delegation(
+    IN nfs41_session *session,
+    IN nfs41_path_fh *file,
+    IN deleg_claim4 *claim,
+    IN uint32_t want,
+    IN bool_t try_recovery,
+    OUT open_delegation4 *delegation)
+{
+    enum nfsstat4 status;
+    nfs41_compound compound;
+    nfs_argop4 argops[3];
+    nfs_resop4 resops[3];
+    nfs41_sequence_args sequence_args;
+    nfs41_sequence_res sequence_res;
+    nfs41_putfh_args putfh_args;
+    nfs41_putfh_res putfh_res;
+    nfs41_want_delegation_args wd_args;
+    nfs41_want_delegation_res wd_res;
+
+    compound_init(&compound, argops, resops, "want_delegation");
+
+    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_PUTFH, &putfh_args, &putfh_res);
+    putfh_args.file = file;
+    putfh_args.in_recovery = 0;
+
+    compound_add_op(&compound, OP_WANT_DELEGATION, &wd_args, &wd_res);
+    wd_args.claim = claim;
+    wd_args.want = want;
+    wd_res.delegation = delegation;
+
+    status = compound_encode_send_decode(session, &compound, try_recovery);
+    if (status)
+        goto out;
+
+    compound_error(status = compound.res.status);
+out:
+    return status;
+}
+
 int nfs41_delegpurge(
     IN nfs41_session *session)
 {

daemon/nfs41_ops.h

@@ -667,8 +667,6 @@ typedef struct __nfs41_op_open_res_ok {
     uint32_t                rflags;
     bitmap4                 attrset;
     open_delegation4        *delegation;
-    uint32_t                why_no_deleg;
-    uint32_t                why_none_flag;
 } nfs41_op_open_res_ok;
 
 typedef struct __nfs41_op_open_res {
@@ -798,6 +796,25 @@ typedef struct __nfs41_setattr_res {
 } nfs41_setattr_res;
 
 
+/* OP_WANT_DELEGATION */
+typedef struct __deleg_claim4 {
+    uint32_t                claim;
+    /* case CLAIM_PREVIOUS: */
+    uint32_t                prev_delegate_type;
+} deleg_claim4;
+
+typedef struct __nfs41_want_delegation_args {
+    uint32_t                want;
+    deleg_claim4            *claim;
+} nfs41_want_delegation_args;
+
+typedef struct __nfs41_want_delegation_res {
+    uint32_t                status;
+    /* case NFS4_OK: */
+    open_delegation4        *delegation;
+} nfs41_want_delegation_res;
+
+
 /* OP_WRITE */
 enum stable_how4 {
     UNSTABLE4       = 0,
@@ -1158,6 +1175,14 @@ int nfs41_access(
     OUT uint32_t *supported OPTIONAL,
     OUT uint32_t *access OPTIONAL);
 
+enum nfsstat4 nfs41_want_delegation(
+    IN nfs41_session *session,
+    IN nfs41_path_fh *file,
+    IN deleg_claim4 *claim,
+    IN uint32_t want,
+    IN bool_t try_recovery,
+    OUT open_delegation4 *delegation);
+
 int nfs41_delegpurge(
     IN nfs41_session *session);
 

daemon/nfs41_xdr.c

@@ -2005,22 +2005,22 @@ static bool_t encode_op_open(
 
 static bool_t decode_open_none_delegation4(
     XDR *xdr,
-    nfs41_op_open_res_ok *res)
+    open_delegation4 *delegation)
 {
-    bool_t result = TRUE;
+    enum_t why_no_deleg;
+    bool_t will_signal;
 
-    if (!xdr_u_int32_t(xdr, &res->why_no_deleg))
+    if (!xdr_enum(xdr, (enum_t*)&why_no_deleg))
         return FALSE;
-    switch (res->why_no_deleg)
+
+    switch (why_no_deleg)
     {
     case WND4_CONTENTION:
     case WND4_RESOURCE:
-        result = xdr_u_int32_t(xdr, &res->why_none_flag);
+        return xdr_bool(xdr, &will_signal);
-        break;
     default:
-        break;
+        return TRUE;
     }
-    return result;
 }
 
 static bool_t decode_open_read_delegation4(
@@ -2037,14 +2037,19 @@ static bool_t decode_open_read_delegation4(
 }
 
 static bool_t decode_modified_limit4(
-    XDR *xdr)
+    XDR *xdr,
+    uint64_t *filesize)
 {
-    uint32_t tmp;
+    uint32_t blocks, bytes_per_block;
 
-    if (!xdr_u_int32_t(xdr, &tmp))
+    if (!xdr_u_int32_t(xdr, &blocks))
         return FALSE;
 
-    return xdr_u_int32_t(xdr, &tmp);
+    if (!xdr_u_int32_t(xdr, &bytes_per_block))
+        return FALSE;
+
+    *filesize = blocks * bytes_per_block;
+    return TRUE;
 }
 
 enum limit_by4 {
@@ -2053,27 +2058,23 @@ enum limit_by4 {
 };
 
 static bool_t decode_space_limit4(
-    XDR *xdr)
+    XDR *xdr,
+    uint64_t *filesize)
 {
-    uint32_t tmp_limitby;
+    uint32_t limitby;
-    uint64_t tmp_filesize;
 
-    if (!xdr_u_int32_t(xdr, &tmp_limitby))
+    if (!xdr_u_int32_t(xdr, &limitby))
         return FALSE;
 
-    switch (tmp_limitby)
+    switch (limitby)
     {
     case NFS_LIMIT_SIZE:
-        return xdr_u_hyper(xdr, &tmp_filesize);
+        return xdr_u_hyper(xdr, filesize);
-        break;
     case NFS_LIMIT_BLOCKS:
-        return decode_modified_limit4(xdr);
+        return decode_modified_limit4(xdr, filesize);
-        break;
     default:
-        eprintf("decode_space_limit4: limitby %d invalid\n",
+        eprintf("decode_space_limit4: limitby %d invalid\n", limitby);
-            tmp_limitby);
         return FALSE;
-        break;
     }
 }
 
@@ -2081,13 +2082,15 @@ static bool_t decode_open_write_delegation4(
     XDR *xdr,
     open_delegation4 *delegation)
 {
+    uint64_t size_limit;
+
     if (!xdr_stateid4(xdr, &delegation->stateid))
         return FALSE;
 
     if (!xdr_bool(xdr, &delegation->recalled))
         return FALSE;
 
-    if (!decode_space_limit4(xdr))
+    if (!decode_space_limit4(xdr, &size_limit))
         return FALSE;
 
     return xdr_nfsace4(xdr, &delegation->permissions);
@@ -2097,8 +2100,6 @@ static bool_t decode_open_res_ok(
     XDR *xdr,
     nfs41_op_open_res_ok *res)
 {
-    bool_t result = TRUE;
-
     if (!xdr_stateid4(xdr, res->stateid))
         return FALSE;
 
@@ -2117,23 +2118,18 @@ static bool_t decode_open_res_ok(
     switch (res->delegation->type)
     {
     case OPEN_DELEGATE_NONE:
-        break;
+        return TRUE;
     case OPEN_DELEGATE_NONE_EXT:
-        result = decode_open_none_delegation4(xdr, res);
+        return decode_open_none_delegation4(xdr, res->delegation);
-        break;
     case OPEN_DELEGATE_READ:
-        result = decode_open_read_delegation4(xdr, res->delegation);
+        return decode_open_read_delegation4(xdr, res->delegation);
-        break;
     case OPEN_DELEGATE_WRITE:
-        result = decode_open_write_delegation4(xdr, res->delegation);
+        return decode_open_write_delegation4(xdr, res->delegation);
-        break;
     default:
         eprintf("decode_open_res_ok: delegation type %d not "
             "supported.\n", res->delegation->type);
-        result = FALSE;
+        return FALSE;
-        break;
     }
-    return result;
 }
 
 static bool_t decode_op_open(
@@ -2681,6 +2677,64 @@ static bool_t decode_op_setattr(
 }
 
 
+/*
+ * OP_WANT_DELEGATION
+ */
+static bool_t encode_op_want_delegation(
+    XDR *xdr,
+    nfs_argop4 *argop)
+{
+    nfs41_want_delegation_args *args = (nfs41_want_delegation_args*)argop->arg;
+
+    if (unexpected_op(argop->op, OP_WANT_DELEGATION))
+        return FALSE;
+
+    if (!xdr_u_int32_t(xdr, &args->want))
+        return FALSE;
+
+    if (!xdr_u_int32_t(xdr, &args->claim->claim))
+        return FALSE;
+
+    return args->claim->claim != CLAIM_PREVIOUS ||
+        xdr_u_int32_t(xdr, &args->claim->prev_delegate_type);
+}
+
+static bool_t decode_op_want_delegation(
+    XDR *xdr,
+    nfs_resop4 *resop)
+{
+    nfs41_want_delegation_res *res = (nfs41_want_delegation_res*)resop->res;
+
+    if (unexpected_op(resop->op, OP_WANT_DELEGATION))
+        return FALSE;
+
+    if (!xdr_u_int32_t(xdr, &res->status))
+        return FALSE;
+
+    if (res->status)
+        return TRUE;
+
+    if (!xdr_enum(xdr, (enum_t*)&res->delegation->type))
+        return FALSE;
+
+    switch (res->delegation->type)
+    {
+    case OPEN_DELEGATE_NONE:
+        return TRUE;
+    case OPEN_DELEGATE_NONE_EXT:
+        return decode_open_none_delegation4(xdr, res->delegation);
+    case OPEN_DELEGATE_READ:
+        return decode_open_read_delegation4(xdr, res->delegation);
+    case OPEN_DELEGATE_WRITE:
+        return decode_open_write_delegation4(xdr, res->delegation);
+    default:
+        eprintf("decode_open_res_ok: delegation type %d not "
+            "supported.\n", res->delegation->type);
+        return FALSE;
+    }
+}
+
+
 /*
  * OP_WRITE
  */
@@ -3426,7 +3480,7 @@ static const op_table_entry g_op_table[] = {
     { encode_op_sequence, decode_op_sequence }, /* OP_SEQUENCE = 53 */
     { NULL, NULL }, /* OP_SET_SSV = 54 */
     { NULL, NULL }, /* OP_TEST_STATEID = 55 */
-    { NULL, NULL }, /* OP_WANT_DELEGATION = 56 */
+    { encode_op_want_delegation, decode_op_want_delegation }, /* OP_WANT_DELEGATION = 56 */
     { encode_op_destroy_clientid, decode_op_destroy_clientid }, /* OP_DESTROY_CLIENTID = 57 */
     { encode_op_reclaim_complete, decode_op_reclaim_complete }, /* OP_RECLAIM_COMPLETE = 58 */
 };

daemon/recovery.c

@@ -262,6 +262,63 @@ static int recover_locks(
     return status;
 }
 
+/* delegation recovery via WANT_DELEGATION */
+static int recover_delegation_want(
+    IN nfs41_session *session,
+    IN nfs41_delegation_state *deleg,
+    IN OUT bool_t *grace)
+{
+    deleg_claim4 claim;
+    open_delegation4 delegation = { 0 };
+    enum open_delegation_type4 delegate_type;
+    uint32_t want_flags = 0;
+    int status = NFS4_OK;
+
+    AcquireSRWLockShared(&deleg->lock);
+    delegate_type = deleg->state.type;
+    ReleaseSRWLockShared(&deleg->lock);
+
+    if (delegate_type == OPEN_DELEGATE_READ)
+        want_flags |= OPEN4_SHARE_ACCESS_WANT_READ_DELEG;
+    else
+        want_flags |= OPEN4_SHARE_ACCESS_WANT_WRITE_DELEG;
+
+    if (*grace) {
+        /* recover the delegation with WANT_DELEGATION/CLAIM_PREVIOUS */
+        claim.claim = CLAIM_PREVIOUS;
+        claim.prev_delegate_type = delegate_type;
+
+        status = nfs41_want_delegation(session, &deleg->file,
+            &claim, want_flags, FALSE, &delegation);
+    } else
+        status = NFS4ERR_NO_GRACE;
+
+    if (status == NFS4ERR_NO_GRACE) {
+        *grace = FALSE;
+        /* attempt out-of-grace recovery with with CLAIM_DELEG_PREV_FH */
+        claim.claim = CLAIM_DELEG_PREV_FH;
+
+        status = nfs41_want_delegation(session, &deleg->file,
+            &claim, want_flags, FALSE, &delegation);
+    }
+    if (status)
+        goto out;
+    
+    /* update delegation state */
+    AcquireSRWLockExclusive(&deleg->lock);
+    if (delegation.type != OPEN_DELEGATE_READ &&
+        delegation.type != OPEN_DELEGATE_WRITE) {
+        eprintf("recover_delegation_want() got delegation type %u, "
+            "expected %u\n", delegation.type, deleg->state.type);
+    } else {
+        memcpy(&deleg->state, &delegation, sizeof(open_delegation4));
+        deleg->revoked = FALSE;
+    }
+    ReleaseSRWLockExclusive(&deleg->lock);
+out:
+    return status;
+}
+
 /* delegation recovery via OPEN (requires corresponding CLOSE) */
 static int recover_delegation_open(
     IN nfs41_session *session,
@@ -337,6 +394,7 @@ int nfs41_recover_client_state(
     nfs41_open_state *open;
     nfs41_delegation_state *deleg;
     bool_t grace = TRUE;
+    bool_t want_supported = TRUE;
     int status = NFS4_OK;
 
     EnterCriticalSection(&state->lock);
@@ -362,9 +420,24 @@ int nfs41_recover_client_state(
     /* recover delegations that weren't associated with any opens */
     list_for_each(entry, &state->delegations) {
         deleg = list_container(entry, nfs41_delegation_state, client_entry);
+
+        /* 10.2.1. Delegation Recovery
+         * When a client needs to reclaim a delegation and there is no
+         * associated open, the client may use the CLAIM_PREVIOUS variant
+         * of the WANT_DELEGATION operation.  However, since the server is
+         * not required to support this operation, an alternative is to
+         * reclaim via a dummy OPEN together with the delegation using an
+         * OPEN of type CLAIM_PREVIOUS. */
         if (deleg->revoked) {
-            /* TODO: try WANT_DELEGATION (server support is optional) */
+            if (want_supported)
+                status = recover_delegation_want(session, deleg, &grace);
+            else
+                status = NFS4ERR_NOTSUPP;
+
+            if (status == NFS4ERR_NOTSUPP) {
+                want_supported = FALSE;
                 status = recover_delegation_open(session, deleg, &grace);
+            }
             if (status == NFS4ERR_BADSESSION)
                 goto unlock;
         }