source/modules/vfs_aio_fork.c

   1 /*
   2  * Simulate the Posix AIO using mmap/fork
   3  *
   4  * Copyright (C) Volker Lendecke 2008
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include "includes.h"
  22
  23 struct mmap_area {
  24         size_t size;
  25         volatile void *ptr;
  26 };
  27
  28 static int mmap_area_destructor(struct mmap_area *area)
  29 {
  30         munmap((void *)area->ptr, area->size);
  31         return 0;
  32 }
  33
  34 static struct mmap_area *mmap_area_init(TALLOC_CTX *mem_ctx, size_t size)
  35 {
  36         struct mmap_area *result;
  37         int fd;
  38
  39         result = talloc(mem_ctx, struct mmap_area);
  40         if (result == NULL) {
  41                 DEBUG(0, ("talloc failed\n"));
  42                 goto fail;
  43         }
  44
  45         fd = open("/dev/zero", O_RDWR);
  46         if (fd == -1) {
  47                 DEBUG(3, ("open(\"/dev/zero\") failed: %s\n",
  48                           strerror(errno)));
  49                 goto fail;
  50         }
  51
  52         result->ptr = mmap(NULL, size, PROT_READ|PROT_WRITE,
  53                            MAP_SHARED|MAP_FILE, fd, 0);
  54         if (result->ptr == MAP_FAILED) {
  55                 DEBUG(1, ("mmap failed: %s\n", strerror(errno)));
  56                 goto fail;
  57         }
  58
  59         close(fd);
  60
  61         result->size = size;
  62         talloc_set_destructor(result, mmap_area_destructor);
  63
  64         return result;
  65
  66 fail:
  67         TALLOC_FREE(result);
  68         return NULL;
  69 }
  70
  71 struct rw_cmd {
  72         size_t n;
  73         SMB_OFF_T offset;
  74         bool read_cmd;
  75 };
  76
  77 struct rw_ret {
  78         ssize_t size;
  79         int ret_errno;
  80 };
  81
  82 struct aio_child_list;
  83
  84 struct aio_child {
  85         struct aio_child *prev, *next;
  86         struct aio_child_list *list;
  87         SMB_STRUCT_AIOCB *aiocb;
  88         pid_t pid;
  89         int sockfd;
  90         struct fd_event *sock_event;
  91         struct rw_ret retval;
  92         struct mmap_area *map;  /* ==NULL means write request */
  93         bool dont_delete;       /* Marked as in use since last cleanup */
  94         bool cancelled;
  95         bool read_cmd;
  96 };
  97
  98 struct aio_child_list {
  99         struct aio_child *children;
 100         struct timed_event *cleanup_event;
 101 };
 102
 103 static void free_aio_children(void **p)
 104 {
 105         TALLOC_FREE(*p);
 106 }
 107
 108 static ssize_t read_fd(int fd, void *ptr, size_t nbytes, int *recvfd)
 109 {
 110         struct msghdr msg;
 111         struct iovec iov[1];
 112         ssize_t n;
 113 #ifndef HAVE_MSGHDR_MSG_CONTROL
 114         int newfd;
 115 #endif
 116
 117 #ifdef  HAVE_MSGHDR_MSG_CONTROL
 118         union {
 119           struct cmsghdr        cm;
 120           char                          control[CMSG_SPACE(sizeof(int))];
 121         } control_un;
 122         struct cmsghdr  *cmptr;
 123
 124         msg.msg_control = control_un.control;
 125         msg.msg_controllen = sizeof(control_un.control);
 126 #else
 127 #if HAVE_MSGHDR_MSG_ACCTRIGHTS
 128         msg.msg_accrights = (caddr_t) &newfd;
 129         msg.msg_accrightslen = sizeof(int);
 130 #else
 131 #error Can not pass file descriptors
 132 #endif
 133 #endif
 134
 135         msg.msg_name = NULL;
 136         msg.msg_namelen = 0;
 137
 138         iov[0].iov_base = ptr;
 139         iov[0].iov_len = nbytes;
 140         msg.msg_iov = iov;
 141         msg.msg_iovlen = 1;
 142
 143         if ( (n = recvmsg(fd, &msg, 0)) <= 0) {
 144                 return(n);
 145         }
 146
 147 #ifdef  HAVE_MSGHDR_MSG_CONTROL
 148         if ((cmptr = CMSG_FIRSTHDR(&msg)) != NULL
 149             && cmptr->cmsg_len == CMSG_LEN(sizeof(int))) {
 150                 if (cmptr->cmsg_level != SOL_SOCKET) {
 151                         DEBUG(10, ("control level != SOL_SOCKET"));
 152                         errno = EINVAL;
 153                         return -1;
 154                 }
 155                 if (cmptr->cmsg_type != SCM_RIGHTS) {
 156                         DEBUG(10, ("control type != SCM_RIGHTS"));
 157                         errno = EINVAL;
 158                         return -1;
 159                 }
 160                 *recvfd = *((int *) CMSG_DATA(cmptr));
 161         } else {
 162                 *recvfd = -1;           /* descriptor was not passed */
 163         }
 164 #else
 165         if (msg.msg_accrightslen == sizeof(int)) {
 166                 *recvfd = newfd;
 167         }
 168         else {
 169                 *recvfd = -1;           /* descriptor was not passed */
 170         }
 171 #endif
 172
 173         return(n);
 174 }
 175
 176 static ssize_t write_fd(int fd, void *ptr, size_t nbytes, int sendfd)
 177 {
 178         struct msghdr   msg;
 179         struct iovec    iov[1];
 180
 181 #ifdef  HAVE_MSGHDR_MSG_CONTROL
 182         union {
 183                 struct cmsghdr  cm;
 184                 char control[CMSG_SPACE(sizeof(int))];
 185         } control_un;
 186         struct cmsghdr  *cmptr;
 187
 188         ZERO_STRUCT(msg);
 189         ZERO_STRUCT(control_un);
 190
 191         msg.msg_control = control_un.control;
 192         msg.msg_controllen = sizeof(control_un.control);
 193
 194         cmptr = CMSG_FIRSTHDR(&msg);
 195         cmptr->cmsg_len = CMSG_LEN(sizeof(int));
 196         cmptr->cmsg_level = SOL_SOCKET;
 197         cmptr->cmsg_type = SCM_RIGHTS;
 198         *((int *) CMSG_DATA(cmptr)) = sendfd;
 199 #else
 200         ZERO_STRUCT(msg);
 201         msg.msg_accrights = (caddr_t) &sendfd;
 202         msg.msg_accrightslen = sizeof(int);
 203 #endif
 204
 205         msg.msg_name = NULL;
 206         msg.msg_namelen = 0;
 207
 208         ZERO_STRUCT(iov);
 209         iov[0].iov_base = ptr;
 210         iov[0].iov_len = nbytes;
 211         msg.msg_iov = iov;
 212         msg.msg_iovlen = 1;
 213
 214         return (sendmsg(fd, &msg, 0));
 215 }
 216
 217 static void aio_child_cleanup(struct event_context *event_ctx,
 218                               struct timed_event *te,
 219                               struct timeval now,
 220                               void *private_data)
 221 {
 222         struct aio_child_list *list = talloc_get_type_abort(
 223                 private_data, struct aio_child_list);
 224         struct aio_child *child, *next;
 225
 226         TALLOC_FREE(list->cleanup_event);
 227
 228         for (child = list->children; child != NULL; child = next) {
 229                 next = child->next;
 230
 231                 if (child->aiocb != NULL) {
 232                         DEBUG(10, ("child %d currently active\n",
 233                                    (int)child->pid));
 234                         continue;
 235                 }
 236
 237                 if (child->dont_delete) {
 238                         DEBUG(10, ("Child %d was active since last cleanup\n",
 239                                    (int)child->pid));
 240                         child->dont_delete = false;
 241                         continue;
 242                 }
 243
 244                 DEBUG(10, ("Child %d idle for more than 30 seconds, "
 245                            "deleting\n", (int)child->pid));
 246
 247                 TALLOC_FREE(child);
 248         }
 249
 250         if (list->children != NULL) {
 251                 /*
 252                  * Re-schedule the next cleanup round
 253                  */
 254                 list->cleanup_event = event_add_timed(smbd_event_context(), list,
 255                                                       timeval_add(&now, 30, 0),
 256                                                       aio_child_cleanup, list);
 257
 258         }
 259 }
 260
 261 static struct aio_child_list *init_aio_children(struct vfs_handle_struct *handle)
 262 {
 263         struct aio_child_list *data = NULL;
 264
 265         if (SMB_VFS_HANDLE_TEST_DATA(handle)) {
 266                 SMB_VFS_HANDLE_GET_DATA(handle, data, struct aio_child_list,
 267                                         return NULL);
 268         }
 269
 270         if (data == NULL) {
 271                 data = TALLOC_ZERO_P(NULL, struct aio_child_list);
 272                 if (data == NULL) {
 273                         return NULL;
 274                 }
 275         }
 276
 277         /*
 278          * Regardless of whether the child_list had been around or not, make
 279          * sure that we have a cleanup timed event. This timed event will
 280          * delete itself when it finds that no children are around anymore.
 281          */
 282
 283         if (data->cleanup_event == NULL) {
 284                 data->cleanup_event = event_add_timed(smbd_event_context(), data,
 285                                                       timeval_current_ofs(30, 0),
 286                                                       aio_child_cleanup, data);
 287                 if (data->cleanup_event == NULL) {
 288                         TALLOC_FREE(data);
 289                         return NULL;
 290                 }
 291         }
 292
 293         if (!SMB_VFS_HANDLE_TEST_DATA(handle)) {
 294                 SMB_VFS_HANDLE_SET_DATA(handle, data, free_aio_children,
 295                                         struct aio_child_list, return False);
 296         }
 297
 298         return data;
 299 }
 300
 301 static void aio_child_loop(int sockfd, struct mmap_area *map)
 302 {
 303         while (true) {
 304                 int fd = -1;
 305                 ssize_t ret;
 306                 struct rw_cmd cmd_struct;
 307                 struct rw_ret ret_struct;
 308
 309                 ret = read_fd(sockfd, &cmd_struct, sizeof(cmd_struct), &fd);
 310                 if (ret != sizeof(cmd_struct)) {
 311                         DEBUG(10, ("read_fd returned %d: %s\n", (int)ret,
 312                                    strerror(errno)));
 313                         exit(1);
 314                 }
 315
 316                 DEBUG(10, ("aio_child_loop: %s %d bytes at %d from fd %d\n",
 317                            cmd_struct.read_cmd ? "read" : "write",
 318                            (int)cmd_struct.n, (int)cmd_struct.offset, fd));
 319
 320 #ifdef ENABLE_BUILD_FARM_HACKS
 321                 {
 322                         /*
 323                          * In the build farm, we want erratic behaviour for
 324                          * async I/O times
 325                          */
 326                         uint8_t randval;
 327                         unsigned msecs;
 328                         /*
 329                          * use generate_random_buffer, we just forked from a
 330                          * common parent state
 331                          */
 332                         generate_random_buffer(&randval, sizeof(randval));
 333                         msecs = randval + 20;
 334                         DEBUG(10, ("delaying for %u msecs\n", msecs));
 335                         smb_msleep(msecs);
 336                 }
 337 #endif
 338
 339
 340                 ZERO_STRUCT(ret_struct);
 341
 342                 if (cmd_struct.read_cmd) {
 343                         ret_struct.size = sys_pread(
 344                                 fd, (void *)map->ptr, cmd_struct.n,
 345                                 cmd_struct.offset);
 346                 }
 347                 else {
 348                         ret_struct.size = sys_pwrite(
 349                                 fd, (void *)map->ptr, cmd_struct.n,
 350                                 cmd_struct.offset);
 351                 }
 352
 353                 DEBUG(10, ("aio_child_loop: syscall returned %d\n",
 354                            (int)ret_struct.size));
 355
 356                 if (ret_struct.size == -1) {
 357                         ret_struct.ret_errno = errno;
 358                 }
 359
 360                 ret = write_data(sockfd, (char *)&ret_struct,
 361                                  sizeof(ret_struct));
 362                 if (ret != sizeof(ret_struct)) {
 363                         DEBUG(10, ("could not write ret_struct: %s\n",
 364                                    strerror(errno)));
 365                         exit(2);
 366                 }
 367
 368                 close(fd);
 369         }
 370 }
 371
 372 static void handle_aio_completion(struct event_context *event_ctx,
 373                                   struct fd_event *event, uint16 flags,
 374                                   void *p)
 375 {
 376         struct aio_child *child = (struct aio_child *)p;
 377         uint16 mid;
 378
 379         DEBUG(10, ("handle_aio_completion called with flags=%d\n", flags));
 380
 381         if ((flags & EVENT_FD_READ) == 0) {
 382                 return;
 383         }
 384
 385         if (!NT_STATUS_IS_OK(read_data(child->sockfd,
 386                                        (char *)&child->retval,
 387                                        sizeof(child->retval)))) {
 388                 DEBUG(0, ("aio child %d died\n", (int)child->pid));
 389                 child->retval.size = -1;
 390                 child->retval.ret_errno = EIO;
 391         }
 392
 393         if (child->cancelled) {
 394                 child->aiocb = NULL;
 395                 child->cancelled = false;
 396                 return;
 397         }
 398
 399         if (child->read_cmd && (child->retval.size > 0)) {
 400                 SMB_ASSERT(child->retval.size <= child->aiocb->aio_nbytes);
 401                 memcpy((void *)child->aiocb->aio_buf, (void *)child->map->ptr,
 402                        child->retval.size);
 403         }
 404
 405         mid = child->aiocb->aio_sigevent.sigev_value.sival_int;
 406
 407         DEBUG(10, ("mid %d finished\n", (int)mid));
 408
 409         aio_request_done(mid);
 410         process_aio_queue();
 411 }
 412
 413 static int aio_child_destructor(struct aio_child *child)
 414 {
 415         SMB_ASSERT((child->aiocb == NULL) || child->cancelled);
 416         close(child->sockfd);
 417         DLIST_REMOVE(child->list->children, child);
 418         return 0;
 419 }
 420
 421 static NTSTATUS create_aio_child(struct aio_child_list *children,
 422                                  size_t map_size,
 423                                  struct aio_child **presult)
 424 {
 425         struct aio_child *result;
 426         int fdpair[2];
 427         NTSTATUS status;
 428
 429         fdpair[0] = fdpair[1] = -1;
 430
 431         result = TALLOC_ZERO_P(children, struct aio_child);
 432         NT_STATUS_HAVE_NO_MEMORY(result);
 433
 434         if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
 435                 status = map_nt_error_from_unix(errno);
 436                 DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
 437                 goto fail;
 438         }
 439
 440         DEBUG(10, ("fdpair = %d/%d\n", fdpair[0], fdpair[1]));
 441
 442         result->map = mmap_area_init(result, map_size);
 443         if (result->map == NULL) {
 444                 status = map_nt_error_from_unix(errno);
 445                 DEBUG(0, ("Could not create mmap area\n"));
 446                 goto fail;
 447         }
 448
 449         result->pid = sys_fork();
 450         if (result->pid == -1) {
 451                 status = map_nt_error_from_unix(errno);
 452                 DEBUG(0, ("fork failed: %s\n", strerror(errno)));
 453                 goto fail;
 454         }
 455
 456         if (result->pid == 0) {
 457                 close(fdpair[0]);
 458                 result->sockfd = fdpair[1];
 459                 aio_child_loop(result->sockfd, result->map);
 460         }
 461
 462         DEBUG(10, ("Child %d created\n", result->pid));
 463
 464         result->sockfd = fdpair[0];
 465         close(fdpair[1]);
 466
 467         result->sock_event = event_add_fd(smbd_event_context(), result,
 468                                           result->sockfd, EVENT_FD_READ,
 469                                           handle_aio_completion,
 470                                           result);
 471         if (result->sock_event == NULL) {
 472                 status = NT_STATUS_NO_MEMORY;
 473                 DEBUG(0, ("event_add_fd failed\n"));
 474                 goto fail;
 475         }
 476
 477         result->list = children;
 478         DLIST_ADD(children->children, result);
 479
 480         talloc_set_destructor(result, aio_child_destructor);
 481
 482         *presult = result;
 483
 484         return NT_STATUS_OK;
 485
 486  fail:
 487         if (fdpair[0] != -1) close(fdpair[0]);
 488         if (fdpair[1] != -1) close(fdpair[1]);
 489         TALLOC_FREE(result);
 490
 491         return status;
 492 }
 493
 494 static NTSTATUS get_idle_child(struct vfs_handle_struct *handle,
 495                                struct aio_child **pchild)
 496 {
 497         struct aio_child_list *children;
 498         struct aio_child *child;
 499         NTSTATUS status;
 500
 501         children = init_aio_children(handle);
 502         if (children == NULL) {
 503                 return NT_STATUS_NO_MEMORY;
 504         }
 505
 506         for (child = children->children; child != NULL; child = child->next) {
 507                 if (child->aiocb == NULL) {
 508                         /* idle */
 509                         break;
 510                 }
 511         }
 512
 513         if (child == NULL) {
 514                 DEBUG(10, ("no idle child found, creating new one\n"));
 515
 516                 status = create_aio_child(children, 128*1024, &child);
 517                 if (!NT_STATUS_IS_OK(status)) {
 518                         DEBUG(10, ("create_aio_child failed: %s\n",
 519                                    nt_errstr(status)));
 520                         return status;
 521                 }
 522         }
 523
 524         child->dont_delete = true;
 525
 526         *pchild = child;
 527         return NT_STATUS_OK;
 528 }
 529
 530 static int aio_fork_read(struct vfs_handle_struct *handle,
 531                          struct files_struct *fsp, SMB_STRUCT_AIOCB *aiocb)
 532 {
 533         struct aio_child *child;
 534         struct rw_cmd cmd;
 535         ssize_t ret;
 536         NTSTATUS status;
 537
 538         if (aiocb->aio_nbytes > 128*1024) {
 539                 /* TODO: support variable buffers */
 540                 errno = EINVAL;
 541                 return -1;
 542         }
 543
 544         status = get_idle_child(handle, &child);
 545         if (!NT_STATUS_IS_OK(status)) {
 546                 DEBUG(10, ("Could not get an idle child\n"));
 547                 return -1;
 548         }
 549
 550         child->read_cmd = true;
 551         child->aiocb = aiocb;
 552         child->retval.ret_errno = EINPROGRESS;
 553
 554         ZERO_STRUCT(cmd);
 555         cmd.n = aiocb->aio_nbytes;
 556         cmd.offset = aiocb->aio_offset;
 557         cmd.read_cmd = child->read_cmd;
 558
 559         DEBUG(10, ("sending fd %d to child %d\n", fsp->fh->fd,
 560                    (int)child->pid));
 561
 562         ret = write_fd(child->sockfd, &cmd, sizeof(cmd), fsp->fh->fd);
 563         if (ret == -1) {
 564                 DEBUG(10, ("write_fd failed: %s\n", strerror(errno)));
 565                 return -1;
 566         }
 567
 568         return 0;
 569 }
 570
 571 static int aio_fork_write(struct vfs_handle_struct *handle,
 572                           struct files_struct *fsp, SMB_STRUCT_AIOCB *aiocb)
 573 {
 574         struct aio_child *child;
 575         struct rw_cmd cmd;
 576         ssize_t ret;
 577         NTSTATUS status;
 578
 579         if (aiocb->aio_nbytes > 128*1024) {
 580                 /* TODO: support variable buffers */
 581                 errno = EINVAL;
 582                 return -1;
 583         }
 584
 585         status = get_idle_child(handle, &child);
 586         if (!NT_STATUS_IS_OK(status)) {
 587                 DEBUG(10, ("Could not get an idle child\n"));
 588                 return -1;
 589         }
 590
 591         child->read_cmd = false;
 592         child->aiocb = aiocb;
 593         child->retval.ret_errno = EINPROGRESS;
 594
 595         memcpy((void *)child->map->ptr, (void *)aiocb->aio_buf,
 596                aiocb->aio_nbytes);
 597
 598         ZERO_STRUCT(cmd);
 599         cmd.n = aiocb->aio_nbytes;
 600         cmd.offset = aiocb->aio_offset;
 601         cmd.read_cmd = child->read_cmd;
 602
 603         DEBUG(10, ("sending fd %d to child %d\n", fsp->fh->fd,
 604                    (int)child->pid));
 605
 606         ret = write_fd(child->sockfd, &cmd, sizeof(cmd), fsp->fh->fd);
 607         if (ret == -1) {
 608                 DEBUG(10, ("write_fd failed: %s\n", strerror(errno)));
 609                 return -1;
 610         }
 611
 612         return 0;
 613 }
 614
 615 static struct aio_child *aio_fork_find_child(struct vfs_handle_struct *handle,
 616                                              SMB_STRUCT_AIOCB *aiocb)
 617 {
 618         struct aio_child_list *children;
 619         struct aio_child *child;
 620
 621         children = init_aio_children(handle);
 622         if (children == NULL) {
 623                 return NULL;
 624         }
 625
 626         for (child = children->children; child != NULL; child = child->next) {
 627                 if (child->aiocb == aiocb) {
 628                         return child;
 629                 }
 630         }
 631
 632         return NULL;
 633 }
 634
 635 static ssize_t aio_fork_return_fn(struct vfs_handle_struct *handle,
 636                                   struct files_struct *fsp,
 637                                   SMB_STRUCT_AIOCB *aiocb)
 638 {
 639         struct aio_child *child = aio_fork_find_child(handle, aiocb);
 640
 641         if (child == NULL) {
 642                 errno = EINVAL;
 643                 DEBUG(0, ("returning EINVAL\n"));
 644                 return -1;
 645         }
 646
 647         child->aiocb = NULL;
 648
 649         if (child->retval.size == -1) {
 650                 errno = child->retval.ret_errno;
 651         }
 652
 653         return child->retval.size;
 654 }
 655
 656 static int aio_fork_cancel(struct vfs_handle_struct *handle,
 657                            struct files_struct *fsp,
 658                            SMB_STRUCT_AIOCB *aiocb)
 659 {
 660         struct aio_child_list *children;
 661         struct aio_child *child;
 662
 663         children = init_aio_children(handle);
 664         if (children == NULL) {
 665                 errno = EINVAL;
 666                 return -1;
 667         }
 668
 669         for (child = children->children; child != NULL; child = child->next) {
 670                 if (child->aiocb == NULL) {
 671                         continue;
 672                 }
 673                 if (child->aiocb->aio_fildes != fsp->fh->fd) {
 674                         continue;
 675                 }
 676                 if ((aiocb != NULL) && (child->aiocb != aiocb)) {
 677                         continue;
 678                 }
 679
 680                 /*
 681                  * We let the child do its job, but we discard the result when
 682                  * it's finished.
 683                  */
 684
 685                 child->cancelled = true;
 686         }
 687
 688         return AIO_CANCELED;
 689 }
 690
 691 static int aio_fork_error_fn(struct vfs_handle_struct *handle,
 692                              struct files_struct *fsp,
 693                              SMB_STRUCT_AIOCB *aiocb)
 694 {
 695         struct aio_child *child = aio_fork_find_child(handle, aiocb);
 696
 697         if (child == NULL) {
 698                 errno = EINVAL;
 699                 return -1;
 700         }
 701
 702         return child->retval.ret_errno;
 703 }
 704
 705 /* VFS operations structure */
 706
 707 static vfs_op_tuple aio_fork_ops[] = {
 708         {SMB_VFS_OP(aio_fork_read),     SMB_VFS_OP_AIO_READ,
 709          SMB_VFS_LAYER_TRANSPARENT},
 710         {SMB_VFS_OP(aio_fork_write),    SMB_VFS_OP_AIO_WRITE,
 711          SMB_VFS_LAYER_TRANSPARENT},
 712         {SMB_VFS_OP(aio_fork_return_fn), SMB_VFS_OP_AIO_RETURN,
 713          SMB_VFS_LAYER_TRANSPARENT},
 714         {SMB_VFS_OP(aio_fork_cancel),   SMB_VFS_OP_AIO_CANCEL,
 715          SMB_VFS_LAYER_TRANSPARENT},
 716         {SMB_VFS_OP(aio_fork_error_fn), SMB_VFS_OP_AIO_ERROR,
 717          SMB_VFS_LAYER_TRANSPARENT},
 718         {SMB_VFS_OP(NULL),              SMB_VFS_OP_NOOP,
 719          SMB_VFS_LAYER_NOOP}
 720 };
 721
 722 NTSTATUS vfs_aio_fork_init(void);
 723 NTSTATUS vfs_aio_fork_init(void)
 724 {
 725         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 726                                 "aio_fork", aio_fork_ops);
 727 }