source3/smbd/fileio.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    read/write to a files_struct
   5    Copyright (C) Andrew Tridgell 1992-1998
   6    Copyright (C) Jeremy Allison 2000-2002. - write cache.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23
  24 static bool setup_write_cache(files_struct *, SMB_OFF_T);
  25
  26 /****************************************************************************
  27  Read from write cache if we can.
  28 ****************************************************************************/
  29
  30 static bool read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  31 {
  32         write_cache *wcp = fsp->wcp;
  33
  34         if(!wcp) {
  35                 return False;
  36         }
  37
  38         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
  39                 return False;
  40         }
  41
  42         memcpy(data, wcp->data + (pos - wcp->offset), n);
  43
  44         DO_PROFILE_INC(writecache_read_hits);
  45
  46         return True;
  47 }
  48
  49 /****************************************************************************
  50  Read from a file.
  51 ****************************************************************************/
  52
  53 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  54 {
  55         ssize_t ret=0,readret;
  56
  57         /* you can't read from print files */
  58         if (fsp->print_file) {
  59                 return -1;
  60         }
  61
  62         /*
  63          * Serve from write cache if we can.
  64          */
  65
  66         if(read_from_write_cache(fsp, data, pos, n)) {
  67                 fsp->fh->pos = pos + n;
  68                 fsp->fh->position_information = fsp->fh->pos;
  69                 return n;
  70         }
  71
  72         flush_write_cache(fsp, READ_FLUSH);
  73
  74         fsp->fh->pos = pos;
  75
  76         if (n > 0) {
  77 #ifdef DMF_FIX
  78                 int numretries = 3;
  79 tryagain:
  80                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  81
  82                 if (readret == -1) {
  83                         if ((errno == EAGAIN) && numretries) {
  84                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
  85                                 (void)sleep(10);
  86                                 --numretries;
  87                                 goto tryagain;
  88                         }
  89                         return -1;
  90                 }
  91 #else /* NO DMF fix. */
  92                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  93
  94                 if (readret == -1) {
  95                         return -1;
  96                 }
  97 #endif
  98                 if (readret > 0) {
  99                         ret += readret;
 100                 }
 101         }
 102
 103         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
 104                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 105
 106         fsp->fh->pos += ret;
 107         fsp->fh->position_information = fsp->fh->pos;
 108
 109         return(ret);
 110 }
 111
 112 /* how many write cache buffers have been allocated */
 113 static unsigned int allocated_write_caches;
 114
 115 /****************************************************************************
 116  *Really* write to a file.
 117 ****************************************************************************/
 118
 119 static ssize_t real_write_file(struct smb_request *req,
 120                                 files_struct *fsp,
 121                                 const char *data,
 122                                 SMB_OFF_T pos,
 123                                 size_t n)
 124 {
 125         ssize_t ret;
 126
 127         if (pos == -1) {
 128                 ret = vfs_write_data(req, fsp, data, n);
 129         } else {
 130                 fsp->fh->pos = pos;
 131                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
 132                         if (vfs_fill_sparse(fsp, pos) == -1) {
 133                                 return -1;
 134                         }
 135                 }
 136                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
 137         }
 138
 139         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 140                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 141
 142         if (ret != -1) {
 143                 fsp->fh->pos += ret;
 144
 145 /* Yes - this is correct - writes don't update this. JRA. */
 146 /* Found by Samba4 tests. */
 147 #if 0
 148                 fsp->position_information = fsp->pos;
 149 #endif
 150         }
 151
 152         return ret;
 153 }
 154
 155 /****************************************************************************
 156  File size cache change.
 157  Updates size on disk but doesn't flush the cache.
 158 ****************************************************************************/
 159
 160 static int wcp_file_size_change(files_struct *fsp)
 161 {
 162         int ret;
 163         write_cache *wcp = fsp->wcp;
 164
 165         wcp->file_size = wcp->offset + wcp->data_size;
 166         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 167         if (ret == -1) {
 168                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
 169                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
 170         }
 171         return ret;
 172 }
 173
 174 static void update_write_time_handler(struct event_context *ctx,
 175                                       struct timed_event *te,
 176                                       const struct timeval *now,
 177                                       void *private_data)
 178 {
 179         files_struct *fsp = (files_struct *)private_data;
 180
 181         /* Remove the timed event handler. */
 182         TALLOC_FREE(fsp->update_write_time_event);
 183         DEBUG(5, ("Update write time on %s\n", fsp->fsp_name));
 184
 185         /* change the write time if not already changed by someone else */
 186         update_write_time(fsp);
 187 }
 188
 189 /*********************************************************
 190  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
 191  in the future.
 192 *********************************************************/
 193
 194 void trigger_write_time_update(struct files_struct *fsp)
 195 {
 196         int delay;
 197
 198         if (fsp->write_time_forced) {
 199                 /* No point - "sticky" write times
 200                  * in effect.
 201                  */
 202                 return;
 203         }
 204
 205         if (fsp->update_write_time_triggered) {
 206                 /*
 207                  * We only update the write time
 208                  * on the first write. After that
 209                  * no other writes affect this.
 210                  */
 211                 return;
 212         }
 213         fsp->update_write_time_triggered = true;
 214
 215         delay = lp_parm_int(SNUM(fsp->conn),
 216                             "smbd", "writetimeupdatedelay",
 217                             WRITE_TIME_UPDATE_USEC_DELAY);
 218
 219         /* trigger the update 2 seconds later */
 220         fsp->update_write_time_on_close = true;
 221         fsp->update_write_time_event =
 222                 event_add_timed(smbd_event_context(), NULL,
 223                                 timeval_current_ofs(0, delay),
 224                                 "update_write_time_handler",
 225                                 update_write_time_handler, fsp);
 226 }
 227
 228 void trigger_write_time_update_immediate(struct files_struct *fsp)
 229 {
 230         if (fsp->write_time_forced) {
 231                 /*
 232                  * No point - "sticky" write times
 233                  * in effect.
 234                  */
 235                 return;
 236         }
 237
 238         TALLOC_FREE(fsp->update_write_time_event);
 239         DEBUG(5, ("Update write time immediate on %s\n", fsp->fsp_name));
 240
 241         fsp->update_write_time_triggered = true;
 242
 243         fsp->update_write_time_on_close = false;
 244         update_write_time(fsp);
 245 }
 246
 247 /****************************************************************************
 248  Write to a file.
 249 ****************************************************************************/
 250
 251 ssize_t write_file(struct smb_request *req,
 252                         files_struct *fsp,
 253                         const char *data,
 254                         SMB_OFF_T pos,
 255                         size_t n)
 256 {
 257         write_cache *wcp = fsp->wcp;
 258         ssize_t total_written = 0;
 259         int write_path = -1;
 260
 261         if (fsp->print_file) {
 262                 fstring sharename;
 263                 uint32 jobid;
 264
 265                 if (!rap_to_pjobid(fsp->rap_print_jobid, sharename, &jobid)) {
 266                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 267                                                 (unsigned int)fsp->rap_print_jobid ));
 268                         errno = EBADF;
 269                         return -1;
 270                 }
 271
 272                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 273         }
 274
 275         if (!fsp->can_write) {
 276                 errno = EPERM;
 277                 return -1;
 278         }
 279
 280         if (!fsp->modified) {
 281                 SMB_STRUCT_STAT st;
 282                 fsp->modified = True;
 283
 284                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
 285                         int dosmode;
 286                         trigger_write_time_update(fsp);
 287                         dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 288                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 289                                         MAP_ARCHIVE(fsp->conn)) &&
 290                                         !IS_DOS_ARCHIVE(dosmode)) {
 291                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
 292                                                 dosmode | aARCH,&st,
 293                                                 NULL,
 294                                                 false);
 295                         }
 296
 297                         /*
 298                          * If this is the first write and we have an exclusive oplock then setup
 299                          * the write cache.
 300                          */
 301
 302                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 303                                 setup_write_cache(fsp, st.st_size);
 304                                 wcp = fsp->wcp;
 305                         }
 306                 }
 307         }
 308
 309 #ifdef WITH_PROFILE
 310         DO_PROFILE_INC(writecache_total_writes);
 311         if (!fsp->oplock_type) {
 312                 DO_PROFILE_INC(writecache_non_oplock_writes);
 313         }
 314 #endif
 315
 316         /*
 317          * If this file is level II oplocked then we need
 318          * to grab the shared memory lock and inform all
 319          * other files with a level II lock that they need
 320          * to flush their read caches. We keep the lock over
 321          * the shared memory area whilst doing this.
 322          */
 323
 324         release_level_2_oplocks_on_change(fsp);
 325
 326 #ifdef WITH_PROFILE
 327         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 328                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 329 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 330                         profile_p->writecache_init_writes,
 331                         profile_p->writecache_abutted_writes,
 332                         profile_p->writecache_total_writes,
 333                         profile_p->writecache_non_oplock_writes,
 334                         profile_p->writecache_allocated_write_caches,
 335                         profile_p->writecache_num_write_caches,
 336                         profile_p->writecache_direct_writes,
 337                         profile_p->writecache_num_perfect_writes,
 338                         profile_p->writecache_read_hits ));
 339
 340                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 341                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 342                         profile_p->writecache_flushed_writes[READ_FLUSH],
 343                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 344                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 345                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 346                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 347                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 348         }
 349 #endif
 350
 351         if (wcp && req->unread_bytes) {
 352                 /* If we're using receivefile don't
 353                  * deal with a write cache.
 354                  */
 355                 flush_write_cache(fsp, WRITE_FLUSH);
 356                 delete_write_cache(fsp);
 357                 wcp = NULL;
 358         }
 359
 360         if(!wcp) {
 361                 DO_PROFILE_INC(writecache_direct_writes);
 362                 total_written = real_write_file(req, fsp, data, pos, n);
 363                 return total_written;
 364         }
 365
 366         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 367                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 368
 369         fsp->fh->pos = pos + n;
 370
 371         /*
 372          * If we have active cache and it isn't contiguous then we flush.
 373          * NOTE: There is a small problem with running out of disk ....
 374          */
 375
 376         if (wcp->data_size) {
 377                 bool cache_flush_needed = False;
 378
 379                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 380
 381                         /* ASCII art.... JRA.
 382
 383       +--------------+-----
 384       | Cached data  | Rest of allocated cache buffer....
 385       +--------------+-----
 386
 387             +-------------------+
 388             | Data to write     |
 389             +-------------------+
 390
 391                         */
 392
 393                         /*
 394                          * Start of write overlaps or abutts the existing data.
 395                          */
 396
 397                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 398
 399                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 400
 401                         /*
 402                          * Update the current buffer size with the new data.
 403                          */
 404
 405                         if(pos + data_used > wcp->offset + wcp->data_size) {
 406                                 wcp->data_size = pos + data_used - wcp->offset;
 407                         }
 408
 409                         /*
 410                          * Update the file size if changed.
 411                          */
 412
 413                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 414                                 if (wcp_file_size_change(fsp) == -1) {
 415                                         return -1;
 416                                 }
 417                         }
 418
 419                         /*
 420                          * If we used all the data then
 421                          * return here.
 422                          */
 423
 424                         if(n == data_used) {
 425                                 return n;
 426                         } else {
 427                                 cache_flush_needed = True;
 428                         }
 429                         /*
 430                          * Move the start of data forward by the amount used,
 431                          * cut down the amount left by the same amount.
 432                          */
 433
 434                         data += data_used;
 435                         pos += data_used;
 436                         n -= data_used;
 437
 438                         DO_PROFILE_INC(writecache_abutted_writes);
 439                         total_written = data_used;
 440
 441                         write_path = 1;
 442
 443                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 444                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 445
 446                         /* ASCII art.... JRA.
 447
 448                         +---------------+
 449                         | Cache buffer  |
 450                         +---------------+
 451
 452             +-------------------+
 453             | Data to write     |
 454             +-------------------+
 455
 456                         */
 457
 458                         /*
 459                          * End of write overlaps the existing data.
 460                          */
 461
 462                         size_t data_used = pos + n - wcp->offset;
 463
 464                         memcpy(wcp->data, data + n - data_used, data_used);
 465
 466                         /*
 467                          * Update the current buffer size with the new data.
 468                          */
 469
 470                         if(pos + n > wcp->offset + wcp->data_size) {
 471                                 wcp->data_size = pos + n - wcp->offset;
 472                         }
 473
 474                         /*
 475                          * Update the file size if changed.
 476                          */
 477
 478                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 479                                 if (wcp_file_size_change(fsp) == -1) {
 480                                         return -1;
 481                                 }
 482                         }
 483
 484                         /*
 485                          * We don't need to move the start of data, but we
 486                          * cut down the amount left by the amount used.
 487                          */
 488
 489                         n -= data_used;
 490
 491                         /*
 492                          * We cannot have used all the data here.
 493                          */
 494
 495                         cache_flush_needed = True;
 496
 497                         DO_PROFILE_INC(writecache_abutted_writes);
 498                         total_written = data_used;
 499
 500                         write_path = 2;
 501
 502                 } else if ( (pos >= wcp->file_size) &&
 503                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 504                                         (pos > wcp->offset + wcp->data_size) &&
 505                                         (pos < wcp->offset + wcp->alloc_size) ) {
 506
 507                         /* ASCII art.... JRA.
 508
 509                        End of file ---->|
 510
 511                         +---------------+---------------+
 512                         | Cached data   | Cache buffer  |
 513                         +---------------+---------------+
 514
 515                                               +-------------------+
 516                                               | Data to write     |
 517                                               +-------------------+
 518
 519                         */
 520
 521                         /*
 522                          * Non-contiguous write part of which fits within
 523                          * the cache buffer and is extending the file
 524                          * and the cache contents reflect the current
 525                          * data up to the current end of the file.
 526                          */
 527
 528                         size_t data_used;
 529
 530                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 531                                 data_used = n;
 532                         } else {
 533                                 data_used = wcp->offset + wcp->alloc_size - pos;
 534                         }
 535
 536                         /*
 537                          * Fill in the non-continuous area with zeros.
 538                          */
 539
 540                         memset(wcp->data + wcp->data_size, '\0',
 541                                 pos - (wcp->offset + wcp->data_size) );
 542
 543                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 544
 545                         /*
 546                          * Update the current buffer size with the new data.
 547                          */
 548
 549                         if(pos + data_used > wcp->offset + wcp->data_size) {
 550                                 wcp->data_size = pos + data_used - wcp->offset;
 551                         }
 552
 553                         /*
 554                          * Update the file size if changed.
 555                          */
 556
 557                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 558                                 if (wcp_file_size_change(fsp) == -1) {
 559                                         return -1;
 560                                 }
 561                         }
 562
 563                         /*
 564                          * If we used all the data then
 565                          * return here.
 566                          */
 567
 568                         if(n == data_used) {
 569                                 return n;
 570                         } else {
 571                                 cache_flush_needed = True;
 572                         }
 573
 574                         /*
 575                          * Move the start of data forward by the amount used,
 576                          * cut down the amount left by the same amount.
 577                          */
 578
 579                         data += data_used;
 580                         pos += data_used;
 581                         n -= data_used;
 582
 583                         DO_PROFILE_INC(writecache_abutted_writes);
 584                         total_written = data_used;
 585
 586                         write_path = 3;
 587
 588                 } else if ( (pos >= wcp->file_size) &&
 589                             (n == 1) &&
 590                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 591                             (pos < wcp->file_size + wcp->alloc_size)) {
 592
 593                         /*
 594
 595                 End of file ---->|
 596
 597                  +---------------+---------------+
 598                  | Cached data   | Cache buffer  |
 599                  +---------------+---------------+
 600
 601                                  |<------- allocated size ---------------->|
 602
 603                                                          +--------+
 604                                                          | 1 Byte |
 605                                                          +--------+
 606
 607                         MS-Office seems to do this a lot to determine if there's enough
 608                         space on the filesystem to write a new file.
 609
 610                         Change to :
 611
 612                 End of file ---->|
 613                                  +-----------------------+--------+
 614                                  | Zeroed Cached data    | 1 Byte |
 615                                  +-----------------------+--------+
 616                         */
 617
 618                         flush_write_cache(fsp, WRITE_FLUSH);
 619                         wcp->offset = wcp->file_size;
 620                         wcp->data_size = pos - wcp->file_size + 1;
 621                         memset(wcp->data, '\0', wcp->data_size);
 622                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 623
 624                         /*
 625                          * Update the file size if changed.
 626                          */
 627
 628                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 629                                 if (wcp_file_size_change(fsp) == -1) {
 630                                         return -1;
 631                                 }
 632                         }
 633
 634                         return n;
 635
 636                 } else {
 637
 638                         /* ASCII art..... JRA.
 639
 640    Case 1).
 641
 642                         +---------------+---------------+
 643                         | Cached data   | Cache buffer  |
 644                         +---------------+---------------+
 645
 646                                                               +-------------------+
 647                                                               | Data to write     |
 648                                                               +-------------------+
 649
 650    Case 2).
 651
 652                            +---------------+---------------+
 653                            | Cached data   | Cache buffer  |
 654                            +---------------+---------------+
 655
 656    +-------------------+
 657    | Data to write     |
 658    +-------------------+
 659
 660     Case 3).
 661
 662                            +---------------+---------------+
 663                            | Cached data   | Cache buffer  |
 664                            +---------------+---------------+
 665
 666                   +-----------------------------------------------------+
 667                   | Data to write                                       |
 668                   +-----------------------------------------------------+
 669
 670                   */
 671
 672                         /*
 673                          * Write is bigger than buffer, or there is no overlap on the
 674                          * low or high ends.
 675                          */
 676
 677                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 678 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 679
 680                         /*
 681                          * If write would fit in the cache, and is larger than
 682                          * the data already in the cache, flush the cache and
 683                          * preferentially copy the data new data into it. Otherwise
 684                          * just write the data directly.
 685                          */
 686
 687                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 688                                 cache_flush_needed = True;
 689                         } else {
 690                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 691
 692                                 /*
 693                                  * If the write overlaps the entire cache, then
 694                                  * discard the current contents of the cache.
 695                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 696                                  */
 697
 698                                 if ((pos <= wcp->offset) &&
 699                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 700                                         DEBUG(9,("write_file: discarding overwritten write \
 701 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 702                                         wcp->data_size = 0;
 703                                 }
 704
 705                                 DO_PROFILE_INC(writecache_direct_writes);
 706                                 if (ret == -1) {
 707                                         return ret;
 708                                 }
 709
 710                                 if (pos + ret > wcp->file_size) {
 711                                         wcp->file_size = pos + ret;
 712                                 }
 713
 714                                 return ret;
 715                         }
 716
 717                         write_path = 4;
 718
 719                 }
 720
 721                 if (cache_flush_needed) {
 722                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 723 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 724                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 725                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 726
 727                         flush_write_cache(fsp, WRITE_FLUSH);
 728                 }
 729         }
 730
 731         /*
 732          * If the write request is bigger than the cache
 733          * size, write it all out.
 734          */
 735
 736         if (n > wcp->alloc_size ) {
 737                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 738                 if (ret == -1) {
 739                         return -1;
 740                 }
 741
 742                 if (pos + ret > wcp->file_size) {
 743                         wcp->file_size = pos + n;
 744                 }
 745
 746                 DO_PROFILE_INC(writecache_direct_writes);
 747                 return total_written + n;
 748         }
 749
 750         /*
 751          * If there's any data left, cache it.
 752          */
 753
 754         if (n) {
 755 #ifdef WITH_PROFILE
 756                 if (wcp->data_size) {
 757                         DO_PROFILE_INC(writecache_abutted_writes);
 758                 } else {
 759                         DO_PROFILE_INC(writecache_init_writes);
 760                 }
 761 #endif
 762                 memcpy(wcp->data+wcp->data_size, data, n);
 763                 if (wcp->data_size == 0) {
 764                         wcp->offset = pos;
 765                         DO_PROFILE_INC(writecache_num_write_caches);
 766                 }
 767                 wcp->data_size += n;
 768
 769                 /*
 770                  * Update the file size if changed.
 771                  */
 772
 773                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 774                         if (wcp_file_size_change(fsp) == -1) {
 775                                 return -1;
 776                         }
 777                 }
 778                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 779                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 780
 781                 total_written += n;
 782                 return total_written; /* .... that's a write :) */
 783         }
 784
 785         return total_written;
 786 }
 787
 788 /****************************************************************************
 789  Delete the write cache structure.
 790 ****************************************************************************/
 791
 792 void delete_write_cache(files_struct *fsp)
 793 {
 794         write_cache *wcp;
 795
 796         if(!fsp) {
 797                 return;
 798         }
 799
 800         if(!(wcp = fsp->wcp)) {
 801                 return;
 802         }
 803
 804         DO_PROFILE_DEC(writecache_allocated_write_caches);
 805         allocated_write_caches--;
 806
 807         SMB_ASSERT(wcp->data_size == 0);
 808
 809         SAFE_FREE(wcp->data);
 810         SAFE_FREE(fsp->wcp);
 811
 812         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 813 }
 814
 815 /****************************************************************************
 816  Setup the write cache structure.
 817 ****************************************************************************/
 818
 819 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 820 {
 821         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 822         write_cache *wcp;
 823
 824         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 825                 return False;
 826         }
 827
 828         if(alloc_size == 0 || fsp->wcp) {
 829                 return False;
 830         }
 831
 832         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 833                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 834                 return False;
 835         }
 836
 837         wcp->file_size = file_size;
 838         wcp->offset = 0;
 839         wcp->alloc_size = alloc_size;
 840         wcp->data_size = 0;
 841         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 842                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 843                         (unsigned int)wcp->alloc_size ));
 844                 SAFE_FREE(wcp);
 845                 return False;
 846         }
 847
 848         memset(wcp->data, '\0', wcp->alloc_size );
 849
 850         fsp->wcp = wcp;
 851         DO_PROFILE_INC(writecache_allocated_write_caches);
 852         allocated_write_caches++;
 853
 854         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 855                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
 856
 857         return True;
 858 }
 859
 860 /****************************************************************************
 861  Cope with a size change.
 862 ****************************************************************************/
 863
 864 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 865 {
 866         if(fsp->wcp) {
 867                 /* The cache *must* have been flushed before we do this. */
 868                 if (fsp->wcp->data_size != 0) {
 869                         char *msg;
 870                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 871                                  "on file %s with write cache size = %lu\n",
 872                                  fsp->fsp_name,
 873                                  (unsigned long)fsp->wcp->data_size) != -1) {
 874                                 smb_panic(msg);
 875                         } else {
 876                                 smb_panic("set_filelen_write_cache");
 877                         }
 878                 }
 879                 fsp->wcp->file_size = file_size;
 880         }
 881 }
 882
 883 /*******************************************************************
 884  Flush a write cache struct to disk.
 885 ********************************************************************/
 886
 887 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 888 {
 889         write_cache *wcp = fsp->wcp;
 890         size_t data_size;
 891         ssize_t ret;
 892
 893         if(!wcp || !wcp->data_size) {
 894                 return 0;
 895         }
 896
 897         data_size = wcp->data_size;
 898         wcp->data_size = 0;
 899
 900         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 901
 902         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 903                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 904
 905 #ifdef WITH_PROFILE
 906         if(data_size == wcp->alloc_size) {
 907                 DO_PROFILE_INC(writecache_num_perfect_writes);
 908         }
 909 #endif
 910
 911         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 912
 913         /*
 914          * Ensure file size if kept up to date if write extends file.
 915          */
 916
 917         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 918                 wcp->file_size = wcp->offset + ret;
 919         }
 920
 921         return ret;
 922 }
 923
 924 /*******************************************************************
 925 sync a file
 926 ********************************************************************/
 927
 928 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
 929 {
 930         if (fsp->fh->fd == -1)
 931                 return NT_STATUS_INVALID_HANDLE;
 932
 933         if (lp_strict_sync(SNUM(conn)) &&
 934             (lp_syncalways(SNUM(conn)) || write_through)) {
 935                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 936                 if (ret == -1) {
 937                         return map_nt_error_from_unix(errno);
 938                 }
 939                 ret = SMB_VFS_FSYNC(fsp);
 940                 if (ret == -1) {
 941                         return map_nt_error_from_unix(errno);
 942                 }
 943         }
 944         return NT_STATUS_OK;
 945 }
 946
 947 /************************************************************
 948  Perform a stat whether a valid fd or not.
 949 ************************************************************/
 950
 951 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 952 {
 953         if (fsp->fh->fd == -1) {
 954                 return SMB_VFS_STAT(fsp->conn, fsp->fsp_name, pst);
 955         } else {
 956                 return SMB_VFS_FSTAT(fsp, pst);
 957         }
 958 }