source3/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 = (void *)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 = (void *)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 #ifdef ENABLE_BUILD_FARM_HACKS
 347                         ret_struct.size = MAX(1, ret_struct.size * 0.9);
 348 #endif
 349                 }
 350                 else {
 351                         ret_struct.size = sys_pwrite(
 352                                 fd, (void *)map->ptr, cmd_struct.n,
 353                                 cmd_struct.offset);
 354                 }
 355
 356                 DEBUG(10, ("aio_child_loop: syscall returned %d\n",
 357                            (int)ret_struct.size));
 358
 359                 if (ret_struct.size == -1) {
 360                         ret_struct.ret_errno = errno;
 361                 }
 362
 363                 /*
 364                  * Close the fd before telling our parent we're done. The
 365                  * parent might close and re-open the file very quickly, and
 366                  * with system-level share modes (GPFS) we would get an
 367                  * unjustified SHARING_VIOLATION.
 368                  */
 369                 close(fd);
 370
 371                 ret = write_data(sockfd, (char *)&ret_struct,
 372                                  sizeof(ret_struct));
 373                 if (ret != sizeof(ret_struct)) {
 374                         DEBUG(10, ("could not write ret_struct: %s\n",
 375                                    strerror(errno)));
 376                         exit(2);
 377                 }
 378         }
 379 }
 380
 381 static void handle_aio_completion(struct event_context *event_ctx,
 382                                   struct fd_event *event, uint16 flags,
 383                                   void *p)
 384 {
 385         struct aio_child *child = (struct aio_child *)p;
 386         uint16 mid;
 387
 388         DEBUG(10, ("handle_aio_completion called with flags=%d\n", flags));
 389
 390         if ((flags & EVENT_FD_READ) == 0) {
 391                 return;
 392         }
 393
 394         if (!NT_STATUS_IS_OK(read_data(child->sockfd,
 395                                        (char *)&child->retval,
 396                                        sizeof(child->retval)))) {
 397                 DEBUG(0, ("aio child %d died\n", (int)child->pid));
 398                 child->retval.size = -1;
 399                 child->retval.ret_errno = EIO;
 400         }
 401
 402         if (child->cancelled) {
 403                 child->aiocb = NULL;
 404                 child->cancelled = false;
 405                 return;
 406         }
 407
 408         if (child->read_cmd && (child->retval.size > 0)) {
 409                 SMB_ASSERT(child->retval.size <= child->aiocb->aio_nbytes);
 410                 memcpy((void *)child->aiocb->aio_buf, (void *)child->map->ptr,
 411                        child->retval.size);
 412         }
 413
 414         mid = child->aiocb->aio_sigevent.sigev_value.sival_int;
 415
 416         DEBUG(10, ("mid %d finished\n", (int)mid));
 417
 418         smbd_aio_complete_mid(mid);
 419 }
 420
 421 static int aio_child_destructor(struct aio_child *child)
 422 {
 423         SMB_ASSERT((child->aiocb == NULL) || child->cancelled);
 424         close(child->sockfd);
 425         DLIST_REMOVE(child->list->children, child);
 426         return 0;
 427 }
 428
 429 /*
 430  * We have to close all fd's in open files, we might incorrectly hold a system
 431  * level share mode on a file.
 432  */
 433
 434 static struct files_struct *close_fsp_fd(struct files_struct *fsp,
 435                                          void *private_data)
 436 {
 437         if ((fsp->fh != NULL) && (fsp->fh->fd != -1)) {
 438                 close(fsp->fh->fd);
 439                 fsp->fh->fd = -1;
 440         }
 441         return NULL;
 442 }
 443
 444 static NTSTATUS create_aio_child(struct aio_child_list *children,
 445                                  size_t map_size,
 446                                  struct aio_child **presult)
 447 {
 448         struct aio_child *result;
 449         int fdpair[2];
 450         NTSTATUS status;
 451
 452         fdpair[0] = fdpair[1] = -1;
 453
 454         result = TALLOC_ZERO_P(children, struct aio_child);
 455         NT_STATUS_HAVE_NO_MEMORY(result);
 456
 457         if (socketpair(AF_UNIX, SOCK_STREAM, 0, fdpair) == -1) {
 458                 status = map_nt_error_from_unix(errno);
 459                 DEBUG(10, ("socketpair() failed: %s\n", strerror(errno)));
 460                 goto fail;
 461         }
 462
 463         DEBUG(10, ("fdpair = %d/%d\n", fdpair[0], fdpair[1]));
 464
 465         result->map = mmap_area_init(result, map_size);
 466         if (result->map == NULL) {
 467                 status = map_nt_error_from_unix(errno);
 468                 DEBUG(0, ("Could not create mmap area\n"));
 469                 goto fail;
 470         }
 471
 472         result->pid = sys_fork();
 473         if (result->pid == -1) {
 474                 status = map_nt_error_from_unix(errno);
 475                 DEBUG(0, ("fork failed: %s\n", strerror(errno)));
 476                 goto fail;
 477         }
 478
 479         if (result->pid == 0) {
 480                 close(fdpair[0]);
 481                 result->sockfd = fdpair[1];
 482                 file_walk_table(close_fsp_fd, NULL);
 483                 aio_child_loop(result->sockfd, result->map);
 484         }
 485
 486         DEBUG(10, ("Child %d created\n", result->pid));
 487
 488         result->sockfd = fdpair[0];
 489         close(fdpair[1]);
 490
 491         result->sock_event = event_add_fd(smbd_event_context(), result,
 492                                           result->sockfd, EVENT_FD_READ,
 493                                           handle_aio_completion,
 494                                           result);
 495         if (result->sock_event == NULL) {
 496                 status = NT_STATUS_NO_MEMORY;
 497                 DEBUG(0, ("event_add_fd failed\n"));
 498                 goto fail;
 499         }
 500
 501         result->list = children;
 502         DLIST_ADD(children->children, result);
 503
 504         talloc_set_destructor(result, aio_child_destructor);
 505
 506         *presult = result;
 507
 508         return NT_STATUS_OK;
 509
 510  fail:
 511         if (fdpair[0] != -1) close(fdpair[0]);
 512         if (fdpair[1] != -1) close(fdpair[1]);
 513         TALLOC_FREE(result);
 514
 515         return status;
 516 }
 517
 518 static NTSTATUS get_idle_child(struct vfs_handle_struct *handle,
 519                                struct aio_child **pchild)
 520 {
 521         struct aio_child_list *children;
 522         struct aio_child *child;
 523         NTSTATUS status;
 524
 525         children = init_aio_children(handle);
 526         if (children == NULL) {
 527                 return NT_STATUS_NO_MEMORY;
 528         }
 529
 530         for (child = children->children; child != NULL; child = child->next) {
 531                 if (child->aiocb == NULL) {
 532                         /* idle */
 533                         break;
 534                 }
 535         }
 536
 537         if (child == NULL) {
 538                 DEBUG(10, ("no idle child found, creating new one\n"));
 539
 540                 status = create_aio_child(children, 128*1024, &child);
 541                 if (!NT_STATUS_IS_OK(status)) {
 542                         DEBUG(10, ("create_aio_child failed: %s\n",
 543                                    nt_errstr(status)));
 544                         return status;
 545                 }
 546         }
 547
 548         child->dont_delete = true;
 549
 550         *pchild = child;
 551         return NT_STATUS_OK;
 552 }
 553
 554 static int aio_fork_read(struct vfs_handle_struct *handle,
 555                          struct files_struct *fsp, SMB_STRUCT_AIOCB *aiocb)
 556 {
 557         struct aio_child *child;
 558         struct rw_cmd cmd;
 559         ssize_t ret;
 560         NTSTATUS status;
 561
 562         if (aiocb->aio_nbytes > 128*1024) {
 563                 /* TODO: support variable buffers */
 564                 errno = EINVAL;
 565                 return -1;
 566         }
 567
 568         status = get_idle_child(handle, &child);
 569         if (!NT_STATUS_IS_OK(status)) {
 570                 DEBUG(10, ("Could not get an idle child\n"));
 571                 return -1;
 572         }
 573
 574         child->read_cmd = true;
 575         child->aiocb = aiocb;
 576         child->retval.ret_errno = EINPROGRESS;
 577
 578         ZERO_STRUCT(cmd);
 579         cmd.n = aiocb->aio_nbytes;
 580         cmd.offset = aiocb->aio_offset;
 581         cmd.read_cmd = child->read_cmd;
 582
 583         DEBUG(10, ("sending fd %d to child %d\n", fsp->fh->fd,
 584                    (int)child->pid));
 585
 586         ret = write_fd(child->sockfd, &cmd, sizeof(cmd), fsp->fh->fd);
 587         if (ret == -1) {
 588                 DEBUG(10, ("write_fd failed: %s\n", strerror(errno)));
 589                 return -1;
 590         }
 591
 592         return 0;
 593 }
 594
 595 static int aio_fork_write(struct vfs_handle_struct *handle,
 596                           struct files_struct *fsp, SMB_STRUCT_AIOCB *aiocb)
 597 {
 598         struct aio_child *child;
 599         struct rw_cmd cmd;
 600         ssize_t ret;
 601         NTSTATUS status;
 602
 603         if (aiocb->aio_nbytes > 128*1024) {
 604                 /* TODO: support variable buffers */
 605                 errno = EINVAL;
 606                 return -1;
 607         }
 608
 609         status = get_idle_child(handle, &child);
 610         if (!NT_STATUS_IS_OK(status)) {
 611                 DEBUG(10, ("Could not get an idle child\n"));
 612                 return -1;
 613         }
 614
 615         child->read_cmd = false;
 616         child->aiocb = aiocb;
 617         child->retval.ret_errno = EINPROGRESS;
 618
 619         memcpy((void *)child->map->ptr, (void *)aiocb->aio_buf,
 620                aiocb->aio_nbytes);
 621
 622         ZERO_STRUCT(cmd);
 623         cmd.n = aiocb->aio_nbytes;
 624         cmd.offset = aiocb->aio_offset;
 625         cmd.read_cmd = child->read_cmd;
 626
 627         DEBUG(10, ("sending fd %d to child %d\n", fsp->fh->fd,
 628                    (int)child->pid));
 629
 630         ret = write_fd(child->sockfd, &cmd, sizeof(cmd), fsp->fh->fd);
 631         if (ret == -1) {
 632                 DEBUG(10, ("write_fd failed: %s\n", strerror(errno)));
 633                 return -1;
 634         }
 635
 636         return 0;
 637 }
 638
 639 static struct aio_child *aio_fork_find_child(struct vfs_handle_struct *handle,
 640                                              SMB_STRUCT_AIOCB *aiocb)
 641 {
 642         struct aio_child_list *children;
 643         struct aio_child *child;
 644
 645         children = init_aio_children(handle);
 646         if (children == NULL) {
 647                 return NULL;
 648         }
 649
 650         for (child = children->children; child != NULL; child = child->next) {
 651                 if (child->aiocb == aiocb) {
 652                         return child;
 653                 }
 654         }
 655
 656         return NULL;
 657 }
 658
 659 static ssize_t aio_fork_return_fn(struct vfs_handle_struct *handle,
 660                                   struct files_struct *fsp,
 661                                   SMB_STRUCT_AIOCB *aiocb)
 662 {
 663         struct aio_child *child = aio_fork_find_child(handle, aiocb);
 664
 665         if (child == NULL) {
 666                 errno = EINVAL;
 667                 DEBUG(0, ("returning EINVAL\n"));
 668                 return -1;
 669         }
 670
 671         child->aiocb = NULL;
 672
 673         if (child->retval.size == -1) {
 674                 errno = child->retval.ret_errno;
 675         }
 676
 677         return child->retval.size;
 678 }
 679
 680 static int aio_fork_cancel(struct vfs_handle_struct *handle,
 681                            struct files_struct *fsp,
 682                            SMB_STRUCT_AIOCB *aiocb)
 683 {
 684         struct aio_child_list *children;
 685         struct aio_child *child;
 686
 687         children = init_aio_children(handle);
 688         if (children == NULL) {
 689                 errno = EINVAL;
 690                 return -1;
 691         }
 692
 693         for (child = children->children; child != NULL; child = child->next) {
 694                 if (child->aiocb == NULL) {
 695                         continue;
 696                 }
 697                 if (child->aiocb->aio_fildes != fsp->fh->fd) {
 698                         continue;
 699                 }
 700                 if ((aiocb != NULL) && (child->aiocb != aiocb)) {
 701                         continue;
 702                 }
 703
 704                 /*
 705                  * We let the child do its job, but we discard the result when
 706                  * it's finished.
 707                  */
 708
 709                 child->cancelled = true;
 710         }
 711
 712         return AIO_CANCELED;
 713 }
 714
 715 static int aio_fork_error_fn(struct vfs_handle_struct *handle,
 716                              struct files_struct *fsp,
 717                              SMB_STRUCT_AIOCB *aiocb)
 718 {
 719         struct aio_child *child = aio_fork_find_child(handle, aiocb);
 720
 721         if (child == NULL) {
 722                 errno = EINVAL;
 723                 return -1;
 724         }
 725
 726         return child->retval.ret_errno;
 727 }
 728
 729 static struct vfs_fn_pointers vfs_aio_fork_fns = {
 730         .aio_read = aio_fork_read,
 731         .aio_write = aio_fork_write,
 732         .aio_return_fn = aio_fork_return_fn,
 733         .aio_cancel = aio_fork_cancel,
 734         .aio_error_fn = aio_fork_error_fn,
 735 };
 736
 737 NTSTATUS vfs_aio_fork_init(void);
 738 NTSTATUS vfs_aio_fork_init(void)
 739 {
 740         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 741                                 "aio_fork", &vfs_aio_fork_fns);
 742 }