lustre/mdc/mdc_locks.c

   1 /* -*- mode: c; c-basic-offset: 8; indent-tabs-mode: nil; -*-
   2  * vim:expandtab:shiftwidth=8:tabstop=8:
   3  *
   4  * Copyright (C) 2001-2003 Cluster File Systems, Inc.
   5  *
   6  *   This file is part of Lustre, http://www.sf.net/projects/lustre/
   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 #ifndef EXPORT_SYMTAB
  23 # define EXPORT_SYMTAB
  24 #endif
  25 #define DEBUG_SUBSYSTEM S_MDC
  26
  27 #ifdef __KERNEL__
  28 # include <linux/module.h>
  29 # include <linux/pagemap.h>
  30 # include <linux/miscdevice.h>
  31 # include <linux/init.h>
  32 #else
  33 # include <liblustre.h>
  34 #endif
  35
  36 #include <linux/obd_class.h>
  37 #include <linux/lustre_mds.h>
  38 #include <linux/lustre_dlm.h>
  39 #include <linux/lprocfs_status.h>
  40 #include "mdc_internal.h"
  41
  42 int it_disposition(struct lookup_intent *it, int flag)
  43 {
  44         return it->d.lustre.it_disposition & flag;
  45 }
  46 EXPORT_SYMBOL(it_disposition);
  47
  48 void it_set_disposition(struct lookup_intent *it, int flag)
  49 {
  50         it->d.lustre.it_disposition |= flag;
  51 }
  52 EXPORT_SYMBOL(it_set_disposition);
  53
  54 static void mdc_fid2mdc_op_data(struct mdc_op_data *data, struct ll_uctxt *ctxt,
  55                                 struct ll_fid *f1, struct ll_fid *f2,
  56                                 const char *name, int namelen, int mode)
  57 {
  58         LASSERT(data);
  59         LASSERT(ctxt);
  60         LASSERT(f1);
  61
  62         data->ctxt = *ctxt;
  63         data->fid1 = *f1;
  64         if (f2)
  65                 data->fid2 = *f2;
  66         else
  67                 memset(&data->fid2, 0, sizeof(data->fid2));
  68         data->name = name;
  69         data->namelen = namelen;
  70         data->create_mode = mode;
  71         data->mod_time = CURRENT_SECONDS;
  72 }
  73
  74 static int it_to_lock_mode(struct lookup_intent *it)
  75 {
  76         /* CREAT needs to be tested before open (both could be set) */
  77         if (it->it_op & IT_CREAT)
  78                 return LCK_PW;
  79         else if (it->it_op & (IT_READDIR | IT_GETATTR | IT_OPEN | IT_LOOKUP))
  80                 return LCK_PR;
  81
  82         LBUG();
  83         RETURN(-EINVAL);
  84 }
  85
  86 int it_open_error(int phase, struct lookup_intent *it)
  87 {
  88         if (it_disposition(it, DISP_OPEN_OPEN)) {
  89                 if (phase == DISP_OPEN_OPEN)
  90                         return it->d.lustre.it_status;
  91                 else
  92                         return 0;
  93         }
  94
  95         if (it_disposition(it, DISP_OPEN_CREATE)) {
  96                 if (phase == DISP_OPEN_CREATE)
  97                         return it->d.lustre.it_status;
  98                 else
  99                         return 0;
 100         }
 101
 102         if (it_disposition(it, DISP_LOOKUP_EXECD)) {
 103                 if (phase == DISP_LOOKUP_EXECD)
 104                         return it->d.lustre.it_status;
 105                 else
 106                         return 0;
 107         }
 108
 109         if (it_disposition(it, DISP_IT_EXECD)) {
 110                 if (phase == DISP_IT_EXECD)
 111                         return it->d.lustre.it_status;
 112                 else
 113                         return 0;
 114         }
 115         CERROR("it disp: %X, status: %d\n", it->d.lustre.it_disposition,
 116                it->d.lustre.it_status);
 117         LBUG();
 118         return 0;
 119 }
 120 EXPORT_SYMBOL(it_open_error);
 121
 122 /* this must be called on a lockh that is known to have a referenced lock */
 123 void mdc_set_lock_data(__u64 *l, void *data)
 124 {
 125         struct ldlm_lock *lock;
 126         struct lustre_handle *lockh = (struct lustre_handle *)l;
 127         ENTRY;
 128
 129         if (!*l) {
 130                 EXIT;
 131                 return;
 132         }
 133
 134         lock = ldlm_handle2lock(lockh);
 135
 136         LASSERT(lock != NULL);
 137         l_lock(&lock->l_resource->lr_namespace->ns_lock);
 138 #ifdef __KERNEL__
 139         if (lock->l_ast_data && lock->l_ast_data != data) {
 140                 struct inode *new_inode = data;
 141                 struct inode *old_inode = lock->l_ast_data;
 142                 LASSERTF(old_inode->i_state & I_FREEING,
 143                          "Found existing inode %p/%lu/%u state %lu in lock: "
 144                          "setting data to %p/%lu/%u\n", old_inode,
 145                          old_inode->i_ino, old_inode->i_generation,
 146                          old_inode->i_state,
 147                          new_inode, new_inode->i_ino, new_inode->i_generation);
 148         }
 149 #endif
 150         lock->l_ast_data = data;
 151         l_unlock(&lock->l_resource->lr_namespace->ns_lock);
 152         LDLM_LOCK_PUT(lock);
 153
 154         EXIT;
 155 }
 156 EXPORT_SYMBOL(mdc_set_lock_data);
 157
 158 int mdc_change_cbdata(struct obd_export *exp, struct ll_fid *fid,
 159                       ldlm_iterator_t it, void *data)
 160 {
 161         struct ldlm_res_id res_id = { .name = {0} };
 162         ENTRY;
 163
 164         res_id.name[0] = fid->id;
 165         res_id.name[1] = fid->generation;
 166
 167         ldlm_change_cbdata(class_exp2obd(exp)->obd_namespace, &res_id, it,
 168                            data);
 169
 170         EXIT;
 171         return 0;
 172 }
 173
 174 static inline void mdc_clear_replay_flag(struct ptlrpc_request *req, int rc)
 175 {
 176         /* Don't hold error requests for replay. */
 177         if (req->rq_replay) {
 178                 unsigned long irqflags;
 179                 spin_lock_irqsave(&req->rq_lock, irqflags);
 180                 req->rq_replay = 0;
 181                 spin_unlock_irqrestore(&req->rq_lock, irqflags);
 182         }
 183         if (rc && req->rq_transno != 0) {
 184                 DEBUG_REQ(D_ERROR, req, "transno returned on error rc %d", rc);
 185                 LBUG();
 186         }
 187 }
 188
 189 static int round_up(int val)
 190 {
 191         int ret = 1;
 192         while (val) {
 193                 val >>= 1;
 194                 ret <<= 1;
 195         }
 196         return ret;
 197 }
 198
 199 /* Save a large LOV EA into the request buffer so that it is available
 200  * for replay.  We don't do this in the initial request because the
 201  * original request doesn't need this buffer (at most it sends just the
 202  * lov_mds_md) and it is a waste of RAM/bandwidth to send the empty
 203  * buffer and may also be difficult to allocate and save a very large
 204  * request buffer for each open. (bug 5707)
 205  *
 206  * OOM here may cause recovery failure if lmm is needed (only for the
 207  * original open if the MDS crashed just when this client also OOM'd)
 208  * but this is incredibly unlikely, and questionable whether the client
 209  * could do MDS recovery under OOM anyways... */
 210 static void mdc_realloc_openmsg(struct ptlrpc_request *req,
 211                                 struct mds_body *body, int size[5])
 212 {
 213         int new_size, old_size;
 214         struct lustre_msg *new_msg;
 215
 216         /* save old size */
 217         old_size = lustre_msg_size(5, size);
 218
 219         size[4] = body->eadatasize;
 220         new_size = lustre_msg_size(5, size);
 221         OBD_ALLOC(new_msg, new_size);
 222         if (new_msg != NULL) {
 223                 struct lustre_msg *old_msg = req->rq_reqmsg;
 224                 long irqflags;
 225
 226                 DEBUG_REQ(D_INFO, req, "replace reqmsg for larger EA %u\n",
 227                           body->eadatasize);
 228                 memcpy(new_msg, old_msg, old_size);
 229                 new_msg->buflens[4] = body->eadatasize;
 230
 231                 spin_lock_irqsave(&req->rq_lock, irqflags);
 232                 req->rq_reqmsg = new_msg;
 233                 req->rq_reqlen = new_size;
 234                 spin_unlock_irqrestore(&req->rq_lock, irqflags);
 235
 236                 OBD_FREE(old_msg, old_size);
 237         } else {
 238                 body->valid &= ~OBD_MD_FLEASIZE;
 239                 body->eadatasize = 0;
 240         }
 241 }
 242
 243 /* We always reserve enough space in the reply packet for a stripe MD, because
 244  * we don't know in advance the file type. */
 245 int mdc_enqueue(struct obd_export *exp,
 246                 int lock_type,
 247                 struct lookup_intent *it,
 248                 int lock_mode,
 249                 struct mdc_op_data *data,
 250                 struct lustre_handle *lockh,
 251                 void *lmm,
 252                 int lmmsize,
 253                 ldlm_completion_callback cb_completion,
 254                 ldlm_blocking_callback cb_blocking,
 255                 void *cb_data)
 256 {
 257         struct ptlrpc_request *req;
 258         struct obd_device *obddev = class_exp2obd(exp);
 259         struct ldlm_res_id res_id =
 260                 { .name = {data->fid1.id, data->fid1.generation} };
 261         int size[5] = {sizeof(struct ldlm_request), sizeof(struct ldlm_intent)};
 262         int rc, flags = LDLM_FL_HAS_INTENT;
 263         int repsize[4] = {sizeof(struct ldlm_reply),
 264                           sizeof(struct mds_body),
 265                           obddev->u.cli.cl_max_mds_easize,
 266                           obddev->u.cli.cl_max_mds_cookiesize};
 267         struct ldlm_reply *dlm_rep;
 268         struct ldlm_intent *lit;
 269         struct ldlm_request *lockreq;
 270         void *eadata;
 271         unsigned long irqflags;
 272         int   reply_buffers = 0;
 273         ENTRY;
 274
 275 //        LDLM_DEBUG_NOLOCK("mdsintent=%s,name=%s,dir=%lu",
 276 //                          ldlm_it2str(it->it_op), it_name, it_inode->i_ino);
 277
 278         if (it->it_op & IT_OPEN) {
 279                 it->it_create_mode |= S_IFREG;
 280                 it->it_create_mode &= ~current->fs->umask;
 281
 282                 size[2] = sizeof(struct mds_rec_create);
 283                 size[3] = data->namelen + 1;
 284                 /* As an optimization, we allocate an RPC request buffer for
 285                  * at least a default-sized LOV EA even if we aren't sending
 286                  * one.  We grow the whole request to the next power-of-two
 287                  * size since we get that much from a slab allocation anyways.
 288                  * This avoids an allocation below in the common case where
 289                  * we need to save a default-sized LOV EA for open replay. */
 290                 size[4] = max(lmmsize, obddev->u.cli.cl_default_mds_easize);
 291                 rc = lustre_msg_size(5, size);
 292                 if (rc & (rc - 1))
 293                         size[4] = min(size[4] + round_up(rc) - rc,
 294                                       obddev->u.cli.cl_max_mds_easize);
 295                 req = ptlrpc_prep_req(class_exp2cliimp(exp), LDLM_ENQUEUE,
 296                                       5, size, NULL);
 297                 if (!req)
 298                         RETURN(-ENOMEM);
 299
 300                 spin_lock_irqsave (&req->rq_lock, irqflags);
 301                 req->rq_replay = 1;
 302                 spin_unlock_irqrestore (&req->rq_lock, irqflags);
 303
 304                 /* pack the intent */
 305                 lit = lustre_msg_buf(req->rq_reqmsg, 1, sizeof (*lit));
 306                 lit->opc = (__u64)it->it_op;
 307
 308                 /* pack the intended request */
 309                 mdc_open_pack(req, 2, data, it->it_create_mode, 0,
 310                               it->it_flags, lmm, lmmsize);
 311                 /* get ready for the reply */
 312                 reply_buffers = 3;
 313                 req->rq_replen = lustre_msg_size(3, repsize);
 314         } else if (it->it_op & IT_UNLINK) {
 315                 size[2] = sizeof(struct mds_rec_unlink);
 316                 size[3] = data->namelen + 1;
 317                 req = ptlrpc_prep_req(class_exp2cliimp(exp), LDLM_ENQUEUE, 4,
 318                                       size, NULL);
 319                 if (!req)
 320                         RETURN(-ENOMEM);
 321
 322                 /* pack the intent */
 323                 lit = lustre_msg_buf(req->rq_reqmsg, 1, sizeof (*lit));
 324                 lit->opc = (__u64)it->it_op;
 325
 326                 /* pack the intended request */
 327                 mdc_unlink_pack(req, 2, data);
 328                 /* get ready for the reply */
 329                 reply_buffers = 4;
 330                 req->rq_replen = lustre_msg_size(4, repsize);
 331         } else if (it->it_op & (IT_GETATTR | IT_LOOKUP)) {
 332                 int valid = OBD_MD_FLNOTOBD | OBD_MD_FLEASIZE;
 333                 size[2] = sizeof(struct mds_body);
 334                 size[3] = data->namelen + 1;
 335
 336                 req = ptlrpc_prep_req(class_exp2cliimp(exp), LDLM_ENQUEUE, 4,
 337                                       size, NULL);
 338                 if (!req)
 339                         RETURN(-ENOMEM);
 340
 341                 /* pack the intent */
 342                 lit = lustre_msg_buf(req->rq_reqmsg, 1, sizeof (*lit));
 343                 lit->opc = (__u64)it->it_op;
 344
 345                 /* pack the intended request */
 346                 mdc_getattr_pack(req, valid, 2, it->it_flags, data);
 347                 /* get ready for the reply */
 348                 reply_buffers = 3;
 349                 req->rq_replen = lustre_msg_size(3, repsize);
 350         } else if (it->it_op == IT_READDIR) {
 351                 req = ptlrpc_prep_req(class_exp2cliimp(exp), LDLM_ENQUEUE, 1,
 352                                       size, NULL);
 353                 if (!req)
 354                         RETURN(-ENOMEM);
 355
 356                 /* get ready for the reply */
 357                 reply_buffers = 1;
 358                 req->rq_replen = lustre_msg_size(1, repsize);
 359         }  else {
 360                 LBUG();
 361                 RETURN(-EINVAL);
 362         }
 363
 364         mdc_get_rpc_lock(obddev->u.cli.cl_rpc_lock, it);
 365         rc = ldlm_cli_enqueue(exp, req, obddev->obd_namespace, res_id,
 366                               lock_type, NULL, lock_mode, &flags, cb_blocking,
 367                               cb_completion, NULL, cb_data, NULL, 0, NULL,
 368                               lockh);
 369         mdc_put_rpc_lock(obddev->u.cli.cl_rpc_lock, it);
 370
 371         /* Similarly, if we're going to replay this request, we don't want to
 372          * actually get a lock, just perform the intent. */
 373         if (req->rq_transno || req->rq_replay) {
 374                 lockreq = lustre_msg_buf(req->rq_reqmsg, 0, sizeof (*lockreq));
 375                 lockreq->lock_flags |= LDLM_FL_INTENT_ONLY;
 376         }
 377
 378         /* This can go when we're sure that this can never happen */
 379         LASSERT(rc != -ENOENT);
 380         if (rc == ELDLM_LOCK_ABORTED) {
 381                 lock_mode = 0;
 382                 memset(lockh, 0, sizeof(*lockh));
 383                 rc = 0;
 384         } else if (rc != 0) {
 385                 CERROR("ldlm_cli_enqueue: %d\n", rc);
 386                 LASSERTF(rc < 0, "rc %d\n", rc);
 387                 mdc_clear_replay_flag(req, rc);
 388                 ptlrpc_req_finished(req);
 389                 RETURN(rc);
 390         } else { /* rc = 0 */
 391                 struct ldlm_lock *lock = ldlm_handle2lock(lockh);
 392                 LASSERT(lock);
 393
 394                 /* If the server gave us back a different lock mode, we should
 395                  * fix up our variables. */
 396                 if (lock->l_req_mode != lock_mode) {
 397                         ldlm_lock_addref(lockh, lock->l_req_mode);
 398                         ldlm_lock_decref(lockh, lock_mode);
 399                         lock_mode = lock->l_req_mode;
 400                 }
 401
 402                 ldlm_lock_allow_match(lock);
 403                 LDLM_LOCK_PUT(lock);
 404         }
 405
 406         dlm_rep = lustre_msg_buf(req->rq_repmsg, 0, sizeof (*dlm_rep));
 407         LASSERT(dlm_rep != NULL);           /* checked by ldlm_cli_enqueue() */
 408         LASSERT_REPSWABBED(req, 0);         /* swabbed by ldlm_cli_enqueue() */
 409
 410         it->d.lustre.it_disposition = (int) dlm_rep->lock_policy_res1;
 411         it->d.lustre.it_status = (int) dlm_rep->lock_policy_res2;
 412         it->d.lustre.it_lock_mode = lock_mode;
 413         it->d.lustre.it_data = req;
 414
 415         if (it->d.lustre.it_status < 0 && req->rq_replay)
 416                 mdc_clear_replay_flag(req, it->d.lustre.it_status);
 417
 418         DEBUG_REQ(D_RPCTRACE, req, "op: %d disposition: %x, status: %d",
 419                   it->it_op,it->d.lustre.it_disposition,it->d.lustre.it_status);
 420
 421         /* We know what to expect, so we do any byte flipping required here */
 422         LASSERT(reply_buffers == 4 || reply_buffers == 3 || reply_buffers == 1);
 423         if (reply_buffers >= 3) {
 424                 struct mds_body *body;
 425
 426                 body = lustre_swab_repbuf(req, 1, sizeof (*body),
 427                                           lustre_swab_mds_body);
 428                 if (body == NULL) {
 429                         CERROR ("Can't swab mds_body\n");
 430                         RETURN (-EPROTO);
 431                 }
 432
 433                 if ((body->valid & OBD_MD_FLEASIZE) != 0) {
 434                         /* The eadata is opaque; just check that it is
 435                          * there.  Eventually, obd_unpackmd() will check
 436                          * the contents */
 437                         eadata = lustre_swab_repbuf(req, 2, body->eadatasize,
 438                                                     NULL);
 439                         if (eadata == NULL) {
 440                                 CERROR ("Missing/short eadata\n");
 441                                 RETURN (-EPROTO);
 442                         }
 443                         /* We save the reply LOV EA in case we have to replay
 444                          * a create for recovery.  If we didn't allocate a
 445                          * large enough request buffer above we need to
 446                          * reallocate it here to hold the actual LOV EA. */
 447                         if (it->it_op & IT_OPEN) {
 448                                 if (req->rq_reqmsg->buflens[4] <
 449                                     body->eadatasize)
 450                                         mdc_realloc_openmsg(req, body, size);
 451
 452                                 lmm = lustre_msg_buf(req->rq_reqmsg, 4,
 453                                                      body->eadatasize);
 454                                 if (lmm)
 455                                         memcpy(lmm, eadata, body->eadatasize);
 456                         }
 457                 }
 458         }
 459
 460         RETURN(rc);
 461 }
 462 EXPORT_SYMBOL(mdc_enqueue);
 463
 464 /*
 465  * This long block is all about fixing up the lock and request state
 466  * so that it is correct as of the moment _before_ the operation was
 467  * applied; that way, the VFS will think that everything is normal and
 468  * call Lustre's regular VFS methods.
 469  *
 470  * If we're performing a creation, that means that unless the creation
 471  * failed with EEXIST, we should fake up a negative dentry.
 472  *
 473  * For everything else, we want to lookup to succeed.
 474  *
 475  * One additional note: if CREATE or OPEN succeeded, we add an extra
 476  * reference to the request because we need to keep it around until
 477  * ll_create/ll_open gets called.
 478  *
 479  * The server will return to us, in it_disposition, an indication of
 480  * exactly what d.lustre.it_status refers to.
 481  *
 482  * If DISP_OPEN_OPEN is set, then d.lustre.it_status refers to the open() call,
 483  * otherwise if DISP_OPEN_CREATE is set, then it status is the
 484  * creation failure mode.  In either case, one of DISP_LOOKUP_NEG or
 485  * DISP_LOOKUP_POS will be set, indicating whether the child lookup
 486  * was successful.
 487  *
 488  * Else, if DISP_LOOKUP_EXECD then d.lustre.it_status is the rc of the
 489  * child lookup.
 490  */
 491 int mdc_intent_lock(struct obd_export *exp, struct ll_uctxt *uctxt,
 492                     struct ll_fid *pfid, const char *name, int len,
 493                     void *lmm, int lmmsize,
 494                     struct ll_fid *cfid, struct lookup_intent *it,
 495                     int lookup_flags, struct ptlrpc_request **reqp,
 496                     ldlm_blocking_callback cb_blocking)
 497 {
 498         struct lustre_handle lockh;
 499         struct ptlrpc_request *request;
 500         int rc = 0;
 501         struct mds_body *mds_body;
 502         struct lustre_handle old_lock;
 503         struct ldlm_lock *lock;
 504         ENTRY;
 505         LASSERT(it);
 506
 507         CDEBUG(D_DLMTRACE,"name: %.*s in inode "LPU64", intent: %s flags %#o\n",
 508                len, name, pfid->id, ldlm_it2str(it->it_op), it->it_flags);
 509
 510         if (cfid && (it->it_op == IT_LOOKUP || it->it_op == IT_GETATTR)) {
 511                 /* We could just return 1 immediately, but since we should only
 512                  * be called in revalidate_it if we already have a lock, let's
 513                  * verify that. */
 514                 struct ldlm_res_id res_id = { .name = { cfid->id,
 515                                                         cfid->generation}};
 516                 struct lustre_handle lockh;
 517                 int mode = LCK_PR;
 518
 519                 rc = ldlm_lock_match(exp->exp_obd->obd_namespace,
 520                                      LDLM_FL_BLOCK_GRANTED, &res_id,
 521                                      LDLM_PLAIN, NULL, LCK_PR, &lockh);
 522                 if (!rc) {
 523                         mode = LCK_PW;
 524                         rc = ldlm_lock_match(exp->exp_obd->obd_namespace,
 525                                              LDLM_FL_BLOCK_GRANTED, &res_id,
 526                                              LDLM_PLAIN, NULL, LCK_PW, &lockh);
 527                 }
 528                 if (rc) {
 529                         memcpy(&it->d.lustre.it_lock_handle, &lockh,
 530                                sizeof(lockh));
 531                         it->d.lustre.it_lock_mode = mode;
 532                 }
 533                 RETURN(rc);
 534         }
 535
 536         /* lookup_it may be called only after revalidate_it has run, because
 537          * revalidate_it cannot return errors, only zero.  Returning zero causes
 538          * this call to lookup, which *can* return an error.
 539          *
 540          * We only want to execute the request associated with the intent one
 541          * time, however, so don't send the request again.  Instead, skip past
 542          * this and use the request from revalidate.  In this case, revalidate
 543          * never dropped its reference, so the refcounts are all OK */
 544         if (!it_disposition(it, DISP_ENQ_COMPLETE)) {
 545                 struct mdc_op_data op_data;
 546                 mdc_fid2mdc_op_data(&op_data, uctxt, pfid, cfid, name, len, 0);
 547
 548                 rc = mdc_enqueue(exp, LDLM_PLAIN, it, it_to_lock_mode(it),
 549                                  &op_data, &lockh, lmm, lmmsize,
 550                                  ldlm_completion_ast, cb_blocking, NULL);
 551                 if (rc < 0)
 552                         RETURN(rc);
 553                 memcpy(&it->d.lustre.it_lock_handle, &lockh, sizeof(lockh));
 554         }
 555         request = *reqp = it->d.lustre.it_data;
 556         LASSERT(request != NULL);
 557         LASSERT(request != LP_POISON);
 558
 559         /* If we're doing an IT_OPEN which did not result in an actual
 560          * successful open, then we need to remove the bit which saves
 561          * this request for unconditional replay.
 562          *
 563          * It's important that we do this first!  Otherwise we might exit the
 564          * function without doing so, and try to replay a failed create
 565          * (bug 3440) */
 566         if (it->it_op & IT_OPEN && request->rq_replay &&
 567             (!it_disposition(it, DISP_OPEN_OPEN) ||it->d.lustre.it_status != 0))
 568                 mdc_clear_replay_flag(request, it->d.lustre.it_status);
 569
 570         if (!it_disposition(it, DISP_IT_EXECD)) {
 571                 /* The server failed before it even started executing the
 572                  * intent, i.e. because it couldn't unpack the request. */
 573                 LASSERT(it->d.lustre.it_status != 0);
 574                 RETURN(it->d.lustre.it_status);
 575         }
 576         rc = it_open_error(DISP_IT_EXECD, it);
 577         if (rc)
 578                 RETURN(rc);
 579
 580         mds_body = lustre_msg_buf(request->rq_repmsg, 1, sizeof(*mds_body));
 581         LASSERT(mds_body != NULL);           /* mdc_enqueue checked */
 582         LASSERT_REPSWABBED(request, 1); /* mdc_enqueue swabbed */
 583
 584         /* If we were revalidating a fid/name pair, mark the intent in
 585          * case we fail and get called again from lookup */
 586         if (cfid != NULL) {
 587                 it_set_disposition(it, DISP_ENQ_COMPLETE);
 588                 /* Also: did we find the same inode? */
 589                 if (memcmp(cfid, &mds_body->fid1, sizeof(*cfid)))
 590                         RETURN(-ESTALE);
 591         }
 592
 593         rc = it_open_error(DISP_LOOKUP_EXECD, it);
 594         if (rc)
 595                 RETURN(rc);
 596
 597         /* keep requests around for the multiple phases of the call
 598          * this shows the DISP_XX must guarantee we make it into the call
 599          */
 600         if (it_disposition(it, DISP_OPEN_CREATE) &&
 601             !it_open_error(DISP_OPEN_CREATE, it))
 602                 ptlrpc_request_addref(request); /* balanced in ll_create_node */
 603         if (it_disposition(it, DISP_OPEN_OPEN) &&
 604             !it_open_error(DISP_OPEN_OPEN, it))
 605                 ptlrpc_request_addref(request); /* balanced in ll_file_open */
 606
 607         if (it->it_op & IT_CREAT) {
 608                 /* XXX this belongs in ll_create_it */
 609         } else if (it->it_op == IT_OPEN) {
 610                 LASSERT(!it_disposition(it, DISP_OPEN_CREATE));
 611         } else {
 612                 LASSERT(it->it_op & (IT_GETATTR | IT_LOOKUP));
 613         }
 614
 615         /* If we already have a matching lock, then cancel the new
 616          * one.  We have to set the data here instead of in
 617          * mdc_enqueue, because we need to use the child's inode as
 618          * the l_ast_data to match, and that's not available until
 619          * intent_finish has performed the iget().) */
 620         lock = ldlm_handle2lock(&lockh);
 621         if (lock) {
 622                 LDLM_DEBUG(lock, "matching against this");
 623                 LDLM_LOCK_PUT(lock);
 624                 memcpy(&old_lock, &lockh, sizeof(lockh));
 625                 if (ldlm_lock_match(NULL, LDLM_FL_BLOCK_GRANTED, NULL,
 626                                     LDLM_PLAIN, NULL, LCK_NL, &old_lock)) {
 627                         ldlm_lock_decref_and_cancel(&lockh,
 628                                                     it->d.lustre.it_lock_mode);
 629                         memcpy(&lockh, &old_lock, sizeof(old_lock));
 630                         memcpy(&it->d.lustre.it_lock_handle, &lockh,
 631                                sizeof(lockh));
 632                 }
 633         }
 634         CDEBUG(D_DENTRY, "D_IT dentry %.*s intent: %s status %d disp %x rc %d\n",
 635                len, name, ldlm_it2str(it->it_op), it->d.lustre.it_status,
 636                it->d.lustre.it_disposition, rc);
 637
 638         RETURN(rc);
 639 }
 640 EXPORT_SYMBOL(mdc_intent_lock);