lustre/ptlrpc/niobuf.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  *  Copyright (c) 2002, 2003 Cluster File Systems, Inc.
   5  *
   6  *   This file is part of Lustre, http://www.lustre.org.
   7  *
   8  *   Lustre is free software; you can redistribute it and/or
   9  *   modify it under the terms of version 2 of the GNU General Public
  10  *   License as published by the Free Software Foundation.
  11  *
  12  *   Lustre is distributed in the hope that it will be useful,
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *   GNU General Public License for more details.
  16  *
  17  *   You should have received a copy of the GNU General Public License
  18  *   along with Lustre; if not, write to the Free Software
  19  *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  *
  21  */
  22
  23 #define DEBUG_SUBSYSTEM S_RPC
  24 #ifndef __KERNEL__
  25 #include <liblustre.h>
  26 #endif
  27 #include <linux/obd_support.h>
  28 #include <linux/lustre_net.h>
  29 #include <linux/lustre_lib.h>
  30 #include <linux/obd.h>
  31 #include "ptlrpc_internal.h"
  32
  33 static int ptl_send_buf (ptl_handle_md_t *mdh, void *base, int len,
  34                          ptl_ack_req_t ack, struct ptlrpc_cb_id *cbid,
  35                          struct ptlrpc_connection *conn, int portal, __u64 xid)
  36 {
  37         int              rc;
  38         ptl_md_t         md;
  39         ENTRY;
  40
  41         LASSERT (portal != 0);
  42         LASSERT (conn != NULL);
  43         CDEBUG (D_INFO, "conn=%p id %s\n", conn, libcfs_id2str(conn->c_peer));
  44         md.start     = base;
  45         md.length    = len;
  46         md.threshold = (ack == PTL_ACK_REQ) ? 2 : 1;
  47         md.options   = PTLRPC_MD_OPTIONS;
  48         md.user_ptr  = cbid;
  49         md.eq_handle = ptlrpc_eq_h;
  50
  51         if (ack == PTL_ACK_REQ &&
  52             OBD_FAIL_CHECK(OBD_FAIL_PTLRPC_ACK | OBD_FAIL_ONCE)) {
  53                 /* don't ask for the ack to simulate failing client */
  54                 ack = PTL_NOACK_REQ;
  55                 obd_fail_loc |= OBD_FAIL_ONCE | OBD_FAILED;
  56         }
  57
  58         rc = PtlMDBind (ptlrpc_ni_h, md, PTL_UNLINK, mdh);
  59         if (rc != PTL_OK) {
  60                 CERROR ("PtlMDBind failed: %d\n", rc);
  61                 LASSERT (rc == PTL_NO_SPACE);
  62                 RETURN (-ENOMEM);
  63         }
  64
  65         CDEBUG(D_NET, "Sending %d bytes to portal %d, xid "LPD64"\n",
  66                len, portal, xid);
  67
  68         rc = PtlPut (*mdh, ack, conn->c_peer, portal, 0, xid, 0, 0);
  69         if (rc != PTL_OK) {
  70                 int rc2;
  71                 /* We're going to get an UNLINK event when I unlink below,
  72                  * which will complete just like any other failed send, so
  73                  * I fall through and return success here! */
  74                 CERROR("PtlPut(%s, %d, "LPD64") failed: %d\n",
  75                        libcfs_id2str(conn->c_peer), portal, xid, rc);
  76                 rc2 = PtlMDUnlink(*mdh);
  77                 LASSERTF(rc2 == PTL_OK, "rc2 = %d\n", rc2);
  78         }
  79
  80         RETURN (0);
  81 }
  82
  83 int ptlrpc_start_bulk_transfer (struct ptlrpc_bulk_desc *desc)
  84 {
  85         int                 rc;
  86         int                 rc2;
  87         ptl_process_id_t    peer;
  88         ptl_md_t            md;
  89         __u64               xid;
  90         ENTRY;
  91
  92         if (OBD_FAIL_CHECK_ONCE(OBD_FAIL_PTLRPC_BULK_PUT_NET))
  93                 RETURN(0);
  94
  95         /* NB no locking required until desc is on the network */
  96         LASSERT (!desc->bd_network_rw);
  97         LASSERT (desc->bd_type == BULK_PUT_SOURCE ||
  98                  desc->bd_type == BULK_GET_SINK);
  99         desc->bd_success = 0;
 100         peer = desc->bd_export->exp_connection->c_peer;
 101
 102         md.user_ptr = &desc->bd_cbid;
 103         md.eq_handle = ptlrpc_eq_h;
 104         md.threshold = 2; /* SENT and ACK/REPLY */
 105         md.options = PTLRPC_MD_OPTIONS;
 106         ptlrpc_fill_bulk_md(&md, desc);
 107
 108         LASSERT (desc->bd_cbid.cbid_fn == server_bulk_callback);
 109         LASSERT (desc->bd_cbid.cbid_arg == desc);
 110
 111         /* NB total length may be 0 for a read past EOF, so we send a 0
 112          * length bulk, since the client expects a bulk event. */
 113
 114         rc = PtlMDBind(ptlrpc_ni_h, md, PTL_UNLINK, &desc->bd_md_h);
 115         if (rc != PTL_OK) {
 116                 CERROR("PtlMDBind failed: %d\n", rc);
 117                 LASSERT (rc == PTL_NO_SPACE);
 118                 RETURN(-ENOMEM);
 119         }
 120
 121         /* Client's bulk and reply matchbits are the same */
 122         xid = desc->bd_req->rq_xid;
 123         CDEBUG(D_NET, "Transferring %u pages %u bytes via portal %d "
 124                "id %s xid "LPX64"\n", desc->bd_iov_count,
 125                desc->bd_nob, desc->bd_portal, libcfs_id2str(peer), xid);
 126
 127         /* Network is about to get at the memory */
 128         desc->bd_network_rw = 1;
 129
 130         if (desc->bd_type == BULK_PUT_SOURCE)
 131                 rc = PtlPut (desc->bd_md_h, PTL_ACK_REQ, peer,
 132                              desc->bd_portal, 0, xid, 0, 0);
 133         else
 134                 rc = PtlGet (desc->bd_md_h, peer,
 135                              desc->bd_portal, 0, xid, 0);
 136
 137         if (rc != PTL_OK) {
 138                 /* Can't send, so we unlink the MD bound above.  The UNLINK
 139                  * event this creates will signal completion with failure,
 140                  * so we return SUCCESS here! */
 141                 CERROR("Transfer(%s, %d, "LPX64") failed: %d\n",
 142                        libcfs_id2str(peer), desc->bd_portal, xid, rc);
 143                 rc2 = PtlMDUnlink(desc->bd_md_h);
 144                 LASSERT (rc2 == PTL_OK);
 145         }
 146
 147         RETURN(0);
 148 }
 149
 150 void ptlrpc_abort_bulk (struct ptlrpc_bulk_desc *desc)
 151 {
 152         /* Server side bulk abort. Idempotent. Not thread-safe (i.e. only
 153          * serialises with completion callback) */
 154         struct l_wait_info lwi;
 155         int                rc;
 156
 157         LASSERT (!in_interrupt ());             /* might sleep */
 158
 159         if (!ptlrpc_bulk_active(desc))          /* completed or */
 160                 return;                         /* never started */
 161
 162         /* The unlink ensures the callback happens ASAP and is the last
 163          * one.  If it fails, it must be because completion just happened,
 164          * but we must still l_wait_event() in this case, to give liblustre
 165          * a chance to run server_bulk_callback()*/
 166
 167         PtlMDUnlink (desc->bd_md_h);
 168
 169         for (;;) {
 170                 /* Network access will complete in finite time but the HUGE
 171                  * timeout lets us CWARN for visibility of sluggish NALs */
 172                 lwi = LWI_TIMEOUT (300 * HZ, NULL, NULL);
 173                 rc = l_wait_event(desc->bd_waitq,
 174                                   !ptlrpc_bulk_active(desc), &lwi);
 175                 if (rc == 0)
 176                         return;
 177
 178                 LASSERT(rc == -ETIMEDOUT);
 179                 CWARN("Unexpectedly long timeout: desc %p\n", desc);
 180         }
 181 }
 182
 183 int ptlrpc_register_bulk (struct ptlrpc_request *req)
 184 {
 185         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
 186         ptl_process_id_t peer;
 187         int rc;
 188         int rc2;
 189         ptl_handle_me_t  me_h;
 190         ptl_md_t         md;
 191         ENTRY;
 192
 193         if (OBD_FAIL_CHECK_ONCE(OBD_FAIL_PTLRPC_BULK_GET_NET))
 194                 RETURN(0);
 195
 196         /* NB no locking required until desc is on the network */
 197         LASSERT (desc->bd_nob > 0);
 198         LASSERT (!desc->bd_network_rw);
 199         LASSERT (desc->bd_iov_count <= PTLRPC_MAX_BRW_PAGES);
 200         LASSERT (desc->bd_req != NULL);
 201         LASSERT (desc->bd_type == BULK_PUT_SINK ||
 202                  desc->bd_type == BULK_GET_SOURCE);
 203
 204         desc->bd_success = 0;
 205
 206         peer = desc->bd_import->imp_connection->c_peer;
 207
 208         md.user_ptr = &desc->bd_cbid;
 209         md.eq_handle = ptlrpc_eq_h;
 210         md.threshold = 1;                       /* PUT or GET */
 211         md.options = PTLRPC_MD_OPTIONS |
 212                      ((desc->bd_type == BULK_GET_SOURCE) ?
 213                       PTL_MD_OP_GET : PTL_MD_OP_PUT);
 214         ptlrpc_fill_bulk_md(&md, desc);
 215
 216         LASSERT (desc->bd_cbid.cbid_fn == client_bulk_callback);
 217         LASSERT (desc->bd_cbid.cbid_arg == desc);
 218
 219         /* XXX Registering the same xid on retried bulk makes my head
 220          * explode trying to understand how the original request's bulk
 221          * might interfere with the retried request -eeb */
 222         LASSERTF (!desc->bd_registered || req->rq_xid != desc->bd_last_xid,
 223                   "registered: %d  rq_xid: "LPU64" bd_last_xid: "LPU64"\n",
 224                   desc->bd_registered, req->rq_xid, desc->bd_last_xid);
 225         desc->bd_registered = 1;
 226         desc->bd_last_xid = req->rq_xid;
 227
 228         rc = PtlMEAttach(ptlrpc_ni_h, desc->bd_portal, peer,
 229                          req->rq_xid, 0, PTL_UNLINK, PTL_INS_AFTER, &me_h);
 230         if (rc != PTL_OK) {
 231                 CERROR("PtlMEAttach failed: %d\n", rc);
 232                 LASSERT (rc == PTL_NO_SPACE);
 233                 RETURN (-ENOMEM);
 234         }
 235
 236         /* About to let the network at it... */
 237         desc->bd_network_rw = 1;
 238         rc = PtlMDAttach(me_h, md, PTL_UNLINK, &desc->bd_md_h);
 239         if (rc != PTL_OK) {
 240                 CERROR("PtlMDAttach failed: %d\n", rc);
 241                 LASSERT (rc == PTL_NO_SPACE);
 242                 desc->bd_network_rw = 0;
 243                 rc2 = PtlMEUnlink (me_h);
 244                 LASSERT (rc2 == PTL_OK);
 245                 RETURN (-ENOMEM);
 246         }
 247
 248         CDEBUG(D_NET, "Setup bulk %s buffers: %u pages %u bytes, xid "LPX64", "
 249                "portal %u\n",
 250                desc->bd_type == BULK_GET_SOURCE ? "get-source" : "put-sink",
 251                desc->bd_iov_count, desc->bd_nob,
 252                req->rq_xid, desc->bd_portal);
 253         RETURN(0);
 254 }
 255
 256 void ptlrpc_unregister_bulk (struct ptlrpc_request *req)
 257 {
 258         /* Disconnect a bulk desc from the network. Idempotent. Not
 259          * thread-safe (i.e. only interlocks with completion callback). */
 260         struct ptlrpc_bulk_desc *desc = req->rq_bulk;
 261         wait_queue_head_t       *wq;
 262         struct l_wait_info       lwi;
 263         int                      rc;
 264
 265         LASSERT (!in_interrupt ());     /* might sleep */
 266
 267         if (!ptlrpc_bulk_active(desc))  /* completed or */
 268                 return;                 /* never registered */
 269
 270         LASSERT (desc->bd_req == req);  /* bd_req NULL until registered */
 271
 272         /* the unlink ensures the callback happens ASAP and is the last
 273          * one.  If it fails, it must be because completion just happened,
 274          * but we must still l_wait_event() in this case to give liblustre
 275          * a chance to run client_bulk_callback() */
 276
 277         PtlMDUnlink (desc->bd_md_h);
 278
 279         if (req->rq_set != NULL)
 280                 wq = &req->rq_set->set_waitq;
 281         else
 282                 wq = &req->rq_reply_waitq;
 283
 284         for (;;) {
 285                 /* Network access will complete in finite time but the HUGE
 286                  * timeout lets us CWARN for visibility of sluggish NALs */
 287                 lwi = LWI_TIMEOUT (300 * HZ, NULL, NULL);
 288                 rc = l_wait_event(*wq, !ptlrpc_bulk_active(desc), &lwi);
 289                 if (rc == 0)
 290                         return;
 291
 292                 LASSERT (rc == -ETIMEDOUT);
 293                 DEBUG_REQ(D_WARNING,req,"Unexpectedly long timeout: desc %p\n",
 294                           desc);
 295         }
 296 }
 297
 298 int ptlrpc_send_reply (struct ptlrpc_request *req, int may_be_difficult)
 299 {
 300         struct ptlrpc_service     *svc = req->rq_rqbd->rqbd_service;
 301         struct ptlrpc_reply_state *rs = req->rq_reply_state;
 302         struct ptlrpc_connection  *conn;
 303         int                        rc;
 304
 305         /* We must already have a reply buffer (only ptlrpc_error() may be
 306          * called without one).  We must also have a request buffer which
 307          * is either the actual (swabbed) incoming request, or a saved copy
 308          * if this is a req saved in target_queue_final_reply(). */
 309         LASSERT (req->rq_reqmsg != NULL);
 310         LASSERT (rs != NULL);
 311         LASSERT (req->rq_repmsg != NULL);
 312         LASSERT (may_be_difficult || !rs->rs_difficult);
 313         LASSERT (req->rq_repmsg == &rs->rs_msg);
 314         LASSERT (rs->rs_cb_id.cbid_fn == reply_out_callback);
 315         LASSERT (rs->rs_cb_id.cbid_arg == rs);
 316         LASSERT (req->rq_repmsg != NULL);
 317
 318         if (req->rq_export && req->rq_export->exp_obd &&
 319             req->rq_export->exp_obd->obd_fail) {
 320                 /* Failed obd's only send ENODEV */
 321                 req->rq_type = PTL_RPC_MSG_ERR;
 322                 req->rq_status = -ENODEV;
 323                 CDEBUG(D_HA, "sending ENODEV from failed obd %d\n",
 324                        req->rq_export->exp_obd->obd_minor);
 325         }
 326
 327         if (req->rq_type != PTL_RPC_MSG_ERR)
 328                 req->rq_type = PTL_RPC_MSG_REPLY;
 329
 330         req->rq_repmsg->type   = req->rq_type;
 331         req->rq_repmsg->status = req->rq_status;
 332         req->rq_repmsg->opc    = req->rq_reqmsg->opc;
 333
 334         if (req->rq_export == NULL)
 335                 conn = ptlrpc_get_connection(req->rq_peer, NULL);
 336         else
 337                 conn = ptlrpc_connection_addref(req->rq_export->exp_connection);
 338
 339         atomic_inc (&svc->srv_outstanding_replies);
 340         ptlrpc_rs_addref(rs);                   /* +1 ref for the network */
 341
 342         rc = ptl_send_buf (&rs->rs_md_h, req->rq_repmsg, req->rq_replen,
 343                            rs->rs_difficult ? PTL_ACK_REQ : PTL_NOACK_REQ,
 344                            &rs->rs_cb_id, conn,
 345                            svc->srv_rep_portal, req->rq_xid);
 346         if (rc != 0) {
 347                 atomic_dec (&svc->srv_outstanding_replies);
 348                 ptlrpc_rs_decref(rs);
 349         }
 350         ptlrpc_put_connection(conn);
 351         return rc;
 352 }
 353
 354 int ptlrpc_reply (struct ptlrpc_request *req)
 355 {
 356         return (ptlrpc_send_reply (req, 0));
 357 }
 358
 359 int ptlrpc_error(struct ptlrpc_request *req)
 360 {
 361         int rc;
 362         ENTRY;
 363
 364         if (!req->rq_repmsg) {
 365                 rc = lustre_pack_reply(req, 0, NULL, NULL);
 366                 if (rc)
 367                         RETURN(rc);
 368         }
 369
 370         req->rq_type = PTL_RPC_MSG_ERR;
 371
 372         rc = ptlrpc_send_reply (req, 0);
 373         RETURN(rc);
 374 }
 375
 376 int ptl_send_rpc(struct ptlrpc_request *request)
 377 {
 378         int rc;
 379         int rc2;
 380         struct ptlrpc_connection *connection;
 381         unsigned long flags;
 382         ptl_handle_me_t  reply_me_h;
 383         ptl_md_t         reply_md;
 384         ENTRY;
 385
 386         OBD_FAIL_RETURN(OBD_FAIL_PTLRPC_DROP_RPC, 0);
 387
 388         LASSERT (request->rq_type == PTL_RPC_MSG_REQUEST);
 389
 390         /* If this is a re-transmit, we're required to have disengaged
 391          * cleanly from the previous attempt */
 392         LASSERT (!request->rq_receiving_reply);
 393
 394         if (request->rq_import->imp_obd &&
 395             request->rq_import->imp_obd->obd_fail) {
 396                 CDEBUG(D_HA, "muting rpc for failed imp obd %s\n",
 397                        request->rq_import->imp_obd->obd_name);
 398                 /* this prevents us from waiting in ptlrpc_queue_wait */
 399                 request->rq_err = 1;
 400                 RETURN(-ENODEV);
 401         }
 402
 403         connection = request->rq_import->imp_connection;
 404
 405         if (request->rq_bulk != NULL) {
 406                 rc = ptlrpc_register_bulk (request);
 407                 if (rc != 0)
 408                         RETURN(rc);
 409         }
 410
 411         request->rq_reqmsg->handle = request->rq_import->imp_remote_handle;
 412         request->rq_reqmsg->type = PTL_RPC_MSG_REQUEST;
 413         request->rq_reqmsg->conn_cnt = request->rq_import->imp_conn_cnt;
 414
 415         LASSERT (request->rq_replen != 0);
 416         if (request->rq_repmsg == NULL)
 417                 OBD_ALLOC(request->rq_repmsg, request->rq_replen);
 418         if (request->rq_repmsg == NULL)
 419                 GOTO(cleanup_bulk, rc = -ENOMEM);
 420
 421         rc = PtlMEAttach(ptlrpc_ni_h,
 422                          request->rq_reply_portal, /* XXX FIXME bug 249 */
 423                          connection->c_peer, request->rq_xid, 0,
 424                          PTL_UNLINK, PTL_INS_AFTER, &reply_me_h);
 425         if (rc != PTL_OK) {
 426                 CERROR("PtlMEAttach failed: %d\n", rc);
 427                 LASSERT (rc == PTL_NO_SPACE);
 428                 GOTO(cleanup_repmsg, rc = -ENOMEM);
 429         }
 430
 431         spin_lock_irqsave (&request->rq_lock, flags);
 432         /* If the MD attach succeeds, there _will_ be a reply_in callback */
 433         request->rq_receiving_reply = 1;
 434         /* Clear any flags that may be present from previous sends. */
 435         request->rq_replied = 0;
 436         request->rq_err = 0;
 437         request->rq_timedout = 0;
 438         request->rq_net_err = 0;
 439         request->rq_resend = 0;
 440         request->rq_restart = 0;
 441         spin_unlock_irqrestore (&request->rq_lock, flags);
 442
 443         reply_md.start     = request->rq_repmsg;
 444         reply_md.length    = request->rq_replen;
 445         reply_md.threshold = 1;
 446         reply_md.options   = PTLRPC_MD_OPTIONS | PTL_MD_OP_PUT;
 447         reply_md.user_ptr  = &request->rq_reply_cbid;
 448         reply_md.eq_handle = ptlrpc_eq_h;
 449
 450         rc = PtlMDAttach(reply_me_h, reply_md, PTL_UNLINK,
 451                          &request->rq_reply_md_h);
 452         if (rc != PTL_OK) {
 453                 CERROR("PtlMDAttach failed: %d\n", rc);
 454                 LASSERT (rc == PTL_NO_SPACE);
 455                 spin_lock_irqsave (&request->rq_lock, flags);
 456                 /* ...but the MD attach didn't succeed... */
 457                 request->rq_receiving_reply = 0;
 458                 spin_unlock_irqrestore (&request->rq_lock, flags);
 459                 GOTO(cleanup_me, rc -ENOMEM);
 460         }
 461
 462         CDEBUG(D_NET, "Setup reply buffer: %u bytes, xid "LPU64
 463                ", portal %u\n",
 464                request->rq_replen, request->rq_xid,
 465                request->rq_reply_portal);
 466
 467         ptlrpc_request_addref(request);       /* +1 ref for the SENT callback */
 468
 469         request->rq_sent = CURRENT_SECONDS;
 470         ptlrpc_pinger_sending_on_import(request->rq_import);
 471         rc = ptl_send_buf(&request->rq_req_md_h,
 472                           request->rq_reqmsg, request->rq_reqlen,
 473                           PTL_NOACK_REQ, &request->rq_req_cbid,
 474                           connection,
 475                           request->rq_request_portal,
 476                           request->rq_xid);
 477         if (rc == 0) {
 478                 ptlrpc_lprocfs_rpc_sent(request);
 479                 RETURN(rc);
 480         }
 481
 482         ptlrpc_req_finished (request);          /* drop callback ref */
 483
 484  cleanup_me:
 485         /* MEUnlink is safe; the PUT didn't even get off the ground, and
 486          * nobody apart from the PUT's target has the right nid+XID to
 487          * access the reply buffer. */
 488         rc2 = PtlMEUnlink(reply_me_h);
 489         LASSERT (rc2 == PTL_OK);
 490         /* UNLINKED callback called synchronously */
 491         LASSERT (!request->rq_receiving_reply);
 492
 493  cleanup_repmsg:
 494         OBD_FREE(request->rq_repmsg, request->rq_replen);
 495         request->rq_repmsg = NULL;
 496
 497  cleanup_bulk:
 498         if (request->rq_bulk != NULL)
 499                 ptlrpc_unregister_bulk(request);
 500
 501         return rc;
 502 }
 503
 504 int ptlrpc_register_rqbd (struct ptlrpc_request_buffer_desc *rqbd)
 505 {
 506         struct ptlrpc_service   *service = rqbd->rqbd_service;
 507         static ptl_process_id_t  match_id = {PTL_NID_ANY, PTL_PID_ANY};
 508         int                      rc;
 509         ptl_md_t                 md;
 510         ptl_handle_me_t          me_h;
 511
 512         CDEBUG(D_NET, "PtlMEAttach: portal %d\n",
 513                service->srv_req_portal);
 514
 515         if (OBD_FAIL_CHECK_ONCE(OBD_FAIL_PTLRPC_RQBD))
 516                 return (-ENOMEM);
 517
 518         rc = PtlMEAttach(ptlrpc_ni_h, service->srv_req_portal,
 519                          match_id, 0, ~0, PTL_UNLINK, PTL_INS_AFTER, &me_h);
 520         if (rc != PTL_OK) {
 521                 CERROR("PtlMEAttach failed: %d\n", rc);
 522                 return (-ENOMEM);
 523         }
 524
 525         LASSERT(rqbd->rqbd_refcount == 0);
 526         rqbd->rqbd_refcount = 1;
 527
 528         md.start     = rqbd->rqbd_buffer;
 529         md.length    = service->srv_buf_size;
 530         md.max_size  = service->srv_max_req_size;
 531         md.threshold = PTL_MD_THRESH_INF;
 532         md.options   = PTLRPC_MD_OPTIONS | PTL_MD_OP_PUT | PTL_MD_MAX_SIZE;
 533         md.user_ptr  = &rqbd->rqbd_cbid;
 534         md.eq_handle = ptlrpc_eq_h;
 535
 536         rc = PtlMDAttach(me_h, md, PTL_UNLINK, &rqbd->rqbd_md_h);
 537         if (rc == PTL_OK)
 538                 return (0);
 539
 540         CERROR("PtlMDAttach failed: %d; \n", rc);
 541         LASSERT (rc == PTL_NO_SPACE);
 542         rc = PtlMEUnlink (me_h);
 543         LASSERT (rc == PTL_OK);
 544         rqbd->rqbd_refcount = 0;
 545
 546         return (-ENOMEM);
 547 }