source/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,fsp->fh->fd,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,fsp->fh->fd,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(files_struct *fsp,const char *data, SMB_OFF_T pos, size_t n)
 120 {
 121         ssize_t ret;
 122
 123         if (pos == -1) {
 124                 ret = vfs_write_data(fsp, data, n);
 125         } else {
 126                 fsp->fh->pos = pos;
 127                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
 128                         if (vfs_fill_sparse(fsp, pos) == -1) {
 129                                 return -1;
 130                         }
 131                 }
 132                 ret = vfs_pwrite_data(fsp, data, n, pos);
 133         }
 134
 135         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 136                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 137
 138         if (ret != -1) {
 139                 fsp->fh->pos += ret;
 140
 141                 /*
 142                  * It turns out that setting the last write time from a Windows
 143                  * client stops any subsequent writes from updating the write time.
 144                  * Doing this after the write gives a race condition here where
 145                  * a stat may see the changed write time before we reset it here,
 146                  * but it's cheaper than having to store the write time in shared
 147                  * memory and look it up using dev/inode across all running smbd's.
 148                  * The 99% solution will hopefully be good enough in this case. JRA.
 149                  */
 150
 151                 if (!null_timespec(fsp->pending_modtime)) {
 152                         set_filetime(fsp->conn, fsp->fsp_name, fsp->pending_modtime);
 153
 154                         /* If we didn't get the "set modtime" call ourselves, we must
 155                            store the last write time to restore on close. JRA. */
 156                         if (!fsp->pending_modtime_owner) {
 157                                 fsp->last_write_time = timespec_current();
 158                         }
 159                 }
 160
 161 /* Yes - this is correct - writes don't update this. JRA. */
 162 /* Found by Samba4 tests. */
 163 #if 0
 164                 fsp->position_information = fsp->pos;
 165 #endif
 166         }
 167
 168         return ret;
 169 }
 170
 171 /****************************************************************************
 172  File size cache change.
 173  Updates size on disk but doesn't flush the cache.
 174 ****************************************************************************/
 175
 176 static int wcp_file_size_change(files_struct *fsp)
 177 {
 178         int ret;
 179         write_cache *wcp = fsp->wcp;
 180
 181         wcp->file_size = wcp->offset + wcp->data_size;
 182         ret = SMB_VFS_FTRUNCATE(fsp, fsp->fh->fd, wcp->file_size);
 183         if (ret == -1) {
 184                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
 185                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
 186         }
 187         return ret;
 188 }
 189
 190 /****************************************************************************
 191  Write to a file.
 192 ****************************************************************************/
 193
 194 ssize_t write_file(files_struct *fsp, const char *data, SMB_OFF_T pos, size_t n)
 195 {
 196         write_cache *wcp = fsp->wcp;
 197         ssize_t total_written = 0;
 198         int write_path = -1;
 199
 200         if (fsp->print_file) {
 201                 fstring sharename;
 202                 uint32 jobid;
 203
 204                 if (!rap_to_pjobid(fsp->rap_print_jobid, sharename, &jobid)) {
 205                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 206                                                 (unsigned int)fsp->rap_print_jobid ));
 207                         errno = EBADF;
 208                         return -1;
 209                 }
 210
 211                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 212         }
 213
 214         if (!fsp->can_write) {
 215                 errno = EPERM;
 216                 return -1;
 217         }
 218
 219         if (!fsp->modified) {
 220                 SMB_STRUCT_STAT st;
 221                 fsp->modified = True;
 222
 223                 if (SMB_VFS_FSTAT(fsp,fsp->fh->fd,&st) == 0) {
 224                         int dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 225                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) || MAP_ARCHIVE(fsp->conn)) && !IS_DOS_ARCHIVE(dosmode)) {
 226                                 file_set_dosmode(fsp->conn,fsp->fsp_name,dosmode | aARCH,&st, False);
 227                         }
 228
 229                         /*
 230                          * If this is the first write and we have an exclusive oplock then setup
 231                          * the write cache.
 232                          */
 233
 234                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 235                                 setup_write_cache(fsp, st.st_size);
 236                                 wcp = fsp->wcp;
 237                         }
 238                 }
 239         }
 240
 241 #ifdef WITH_PROFILE
 242         DO_PROFILE_INC(writecache_total_writes);
 243         if (!fsp->oplock_type) {
 244                 DO_PROFILE_INC(writecache_non_oplock_writes);
 245         }
 246 #endif
 247
 248         /*
 249          * If this file is level II oplocked then we need
 250          * to grab the shared memory lock and inform all
 251          * other files with a level II lock that they need
 252          * to flush their read caches. We keep the lock over
 253          * the shared memory area whilst doing this.
 254          */
 255
 256         release_level_2_oplocks_on_change(fsp);
 257
 258 #ifdef WITH_PROFILE
 259         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 260                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 261 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 262                         profile_p->writecache_init_writes,
 263                         profile_p->writecache_abutted_writes,
 264                         profile_p->writecache_total_writes,
 265                         profile_p->writecache_non_oplock_writes,
 266                         profile_p->writecache_allocated_write_caches,
 267                         profile_p->writecache_num_write_caches,
 268                         profile_p->writecache_direct_writes,
 269                         profile_p->writecache_num_perfect_writes,
 270                         profile_p->writecache_read_hits ));
 271
 272                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 273                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 274                         profile_p->writecache_flushed_writes[READ_FLUSH],
 275                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 276                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 277                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 278                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 279                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 280         }
 281 #endif
 282
 283         if(!wcp) {
 284                 DO_PROFILE_INC(writecache_direct_writes);
 285                 total_written = real_write_file(fsp, data, pos, n);
 286                 return total_written;
 287         }
 288
 289         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 290                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 291
 292         fsp->fh->pos = pos + n;
 293
 294         /*
 295          * If we have active cache and it isn't contiguous then we flush.
 296          * NOTE: There is a small problem with running out of disk ....
 297          */
 298
 299         if (wcp->data_size) {
 300                 BOOL cache_flush_needed = False;
 301
 302                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 303
 304                         /* ASCII art.... JRA.
 305
 306       +--------------+-----
 307       | Cached data  | Rest of allocated cache buffer....
 308       +--------------+-----
 309
 310             +-------------------+
 311             | Data to write     |
 312             +-------------------+
 313
 314                         */
 315
 316                         /*
 317                          * Start of write overlaps or abutts the existing data.
 318                          */
 319
 320                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 321
 322                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 323
 324                         /*
 325                          * Update the current buffer size with the new data.
 326                          */
 327
 328                         if(pos + data_used > wcp->offset + wcp->data_size) {
 329                                 wcp->data_size = pos + data_used - wcp->offset;
 330                         }
 331
 332                         /*
 333                          * Update the file size if changed.
 334                          */
 335
 336                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 337                                 if (wcp_file_size_change(fsp) == -1) {
 338                                         return -1;
 339                                 }
 340                         }
 341
 342                         /*
 343                          * If we used all the data then
 344                          * return here.
 345                          */
 346
 347                         if(n == data_used) {
 348                                 return n;
 349                         } else {
 350                                 cache_flush_needed = True;
 351                         }
 352                         /*
 353                          * Move the start of data forward by the amount used,
 354                          * cut down the amount left by the same amount.
 355                          */
 356
 357                         data += data_used;
 358                         pos += data_used;
 359                         n -= data_used;
 360
 361                         DO_PROFILE_INC(writecache_abutted_writes);
 362                         total_written = data_used;
 363
 364                         write_path = 1;
 365
 366                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 367                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 368
 369                         /* ASCII art.... JRA.
 370
 371                         +---------------+
 372                         | Cache buffer  |
 373                         +---------------+
 374
 375             +-------------------+
 376             | Data to write     |
 377             +-------------------+
 378
 379                         */
 380
 381                         /*
 382                          * End of write overlaps the existing data.
 383                          */
 384
 385                         size_t data_used = pos + n - wcp->offset;
 386
 387                         memcpy(wcp->data, data + n - data_used, data_used);
 388
 389                         /*
 390                          * Update the current buffer size with the new data.
 391                          */
 392
 393                         if(pos + n > wcp->offset + wcp->data_size) {
 394                                 wcp->data_size = pos + n - wcp->offset;
 395                         }
 396
 397                         /*
 398                          * Update the file size if changed.
 399                          */
 400
 401                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 402                                 if (wcp_file_size_change(fsp) == -1) {
 403                                         return -1;
 404                                 }
 405                         }
 406
 407                         /*
 408                          * We don't need to move the start of data, but we
 409                          * cut down the amount left by the amount used.
 410                          */
 411
 412                         n -= data_used;
 413
 414                         /*
 415                          * We cannot have used all the data here.
 416                          */
 417
 418                         cache_flush_needed = True;
 419
 420                         DO_PROFILE_INC(writecache_abutted_writes);
 421                         total_written = data_used;
 422
 423                         write_path = 2;
 424
 425                 } else if ( (pos >= wcp->file_size) &&
 426                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 427                                         (pos > wcp->offset + wcp->data_size) &&
 428                                         (pos < wcp->offset + wcp->alloc_size) ) {
 429
 430                         /* ASCII art.... JRA.
 431
 432                        End of file ---->|
 433
 434                         +---------------+---------------+
 435                         | Cached data   | Cache buffer  |
 436                         +---------------+---------------+
 437
 438                                               +-------------------+
 439                                               | Data to write     |
 440                                               +-------------------+
 441
 442                         */
 443
 444                         /*
 445                          * Non-contiguous write part of which fits within
 446                          * the cache buffer and is extending the file
 447                          * and the cache contents reflect the current
 448                          * data up to the current end of the file.
 449                          */
 450
 451                         size_t data_used;
 452
 453                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 454                                 data_used = n;
 455                         } else {
 456                                 data_used = wcp->offset + wcp->alloc_size - pos;
 457                         }
 458
 459                         /*
 460                          * Fill in the non-continuous area with zeros.
 461                          */
 462
 463                         memset(wcp->data + wcp->data_size, '\0',
 464                                 pos - (wcp->offset + wcp->data_size) );
 465
 466                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 467
 468                         /*
 469                          * Update the current buffer size with the new data.
 470                          */
 471
 472                         if(pos + data_used > wcp->offset + wcp->data_size) {
 473                                 wcp->data_size = pos + data_used - wcp->offset;
 474                         }
 475
 476                         /*
 477                          * Update the file size if changed.
 478                          */
 479
 480                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 481                                 if (wcp_file_size_change(fsp) == -1) {
 482                                         return -1;
 483                                 }
 484                         }
 485
 486                         /*
 487                          * If we used all the data then
 488                          * return here.
 489                          */
 490
 491                         if(n == data_used) {
 492                                 return n;
 493                         } else {
 494                                 cache_flush_needed = True;
 495                         }
 496
 497                         /*
 498                          * Move the start of data forward by the amount used,
 499                          * cut down the amount left by the same amount.
 500                          */
 501
 502                         data += data_used;
 503                         pos += data_used;
 504                         n -= data_used;
 505
 506                         DO_PROFILE_INC(writecache_abutted_writes);
 507                         total_written = data_used;
 508
 509                         write_path = 3;
 510
 511                 } else if ( (pos >= wcp->file_size) &&
 512                             (n == 1) &&
 513                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 514                             (pos < wcp->file_size + wcp->alloc_size)) {
 515
 516                         /*
 517
 518                 End of file ---->|
 519
 520                  +---------------+---------------+
 521                  | Cached data   | Cache buffer  |
 522                  +---------------+---------------+
 523
 524                                  |<------- allocated size ---------------->|
 525
 526                                                          +--------+
 527                                                          | 1 Byte |
 528                                                          +--------+
 529
 530                         MS-Office seems to do this a lot to determine if there's enough
 531                         space on the filesystem to write a new file.
 532
 533                         Change to :
 534
 535                 End of file ---->|
 536                                  +-----------------------+--------+
 537                                  | Zeroed Cached data    | 1 Byte |
 538                                  +-----------------------+--------+
 539                         */
 540
 541                         flush_write_cache(fsp, WRITE_FLUSH);
 542                         wcp->offset = wcp->file_size;
 543                         wcp->data_size = pos - wcp->file_size + 1;
 544                         memset(wcp->data, '\0', wcp->data_size);
 545                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 546
 547                         /*
 548                          * Update the file size if changed.
 549                          */
 550
 551                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 552                                 if (wcp_file_size_change(fsp) == -1) {
 553                                         return -1;
 554                                 }
 555                         }
 556
 557                         return n;
 558
 559                 } else {
 560
 561                         /* ASCII art..... JRA.
 562
 563    Case 1).
 564
 565                         +---------------+---------------+
 566                         | Cached data   | Cache buffer  |
 567                         +---------------+---------------+
 568
 569                                                               +-------------------+
 570                                                               | Data to write     |
 571                                                               +-------------------+
 572
 573    Case 2).
 574
 575                            +---------------+---------------+
 576                            | Cached data   | Cache buffer  |
 577                            +---------------+---------------+
 578
 579    +-------------------+
 580    | Data to write     |
 581    +-------------------+
 582
 583     Case 3).
 584
 585                            +---------------+---------------+
 586                            | Cached data   | Cache buffer  |
 587                            +---------------+---------------+
 588
 589                   +-----------------------------------------------------+
 590                   | Data to write                                       |
 591                   +-----------------------------------------------------+
 592
 593                   */
 594
 595                         /*
 596                          * Write is bigger than buffer, or there is no overlap on the
 597                          * low or high ends.
 598                          */
 599
 600                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 601 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 602
 603                         /*
 604                          * If write would fit in the cache, and is larger than
 605                          * the data already in the cache, flush the cache and
 606                          * preferentially copy the data new data into it. Otherwise
 607                          * just write the data directly.
 608                          */
 609
 610                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 611                                 cache_flush_needed = True;
 612                         } else {
 613                                 ssize_t ret = real_write_file(fsp, data, pos, n);
 614
 615                                 /*
 616                                  * If the write overlaps the entire cache, then
 617                                  * discard the current contents of the cache.
 618                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 619                                  */
 620
 621                                 if ((pos <= wcp->offset) &&
 622                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 623                                         DEBUG(9,("write_file: discarding overwritten write \
 624 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 625                                         wcp->data_size = 0;
 626                                 }
 627
 628                                 DO_PROFILE_INC(writecache_direct_writes);
 629                                 if (ret == -1) {
 630                                         return ret;
 631                                 }
 632
 633                                 if (pos + ret > wcp->file_size) {
 634                                         wcp->file_size = pos + ret;
 635                                 }
 636
 637                                 return ret;
 638                         }
 639
 640                         write_path = 4;
 641
 642                 }
 643
 644                 if (cache_flush_needed) {
 645                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 646 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 647                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 648                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 649
 650                         flush_write_cache(fsp, WRITE_FLUSH);
 651                 }
 652         }
 653
 654         /*
 655          * If the write request is bigger than the cache
 656          * size, write it all out.
 657          */
 658
 659         if (n > wcp->alloc_size ) {
 660                 ssize_t ret = real_write_file(fsp, data, pos, n);
 661                 if (ret == -1) {
 662                         return -1;
 663                 }
 664
 665                 if (pos + ret > wcp->file_size) {
 666                         wcp->file_size = pos + n;
 667                 }
 668
 669                 DO_PROFILE_INC(writecache_direct_writes);
 670                 return total_written + n;
 671         }
 672
 673         /*
 674          * If there's any data left, cache it.
 675          */
 676
 677         if (n) {
 678 #ifdef WITH_PROFILE
 679                 if (wcp->data_size) {
 680                         DO_PROFILE_INC(writecache_abutted_writes);
 681                 } else {
 682                         DO_PROFILE_INC(writecache_init_writes);
 683                 }
 684 #endif
 685                 memcpy(wcp->data+wcp->data_size, data, n);
 686                 if (wcp->data_size == 0) {
 687                         wcp->offset = pos;
 688                         DO_PROFILE_INC(writecache_num_write_caches);
 689                 }
 690                 wcp->data_size += n;
 691
 692                 /*
 693                  * Update the file size if changed.
 694                  */
 695
 696                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 697                         if (wcp_file_size_change(fsp) == -1) {
 698                                 return -1;
 699                         }
 700                 }
 701                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 702                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 703
 704                 total_written += n;
 705                 return total_written; /* .... that's a write :) */
 706         }
 707
 708         return total_written;
 709 }
 710
 711 /****************************************************************************
 712  Delete the write cache structure.
 713 ****************************************************************************/
 714
 715 void delete_write_cache(files_struct *fsp)
 716 {
 717         write_cache *wcp;
 718
 719         if(!fsp) {
 720                 return;
 721         }
 722
 723         if(!(wcp = fsp->wcp)) {
 724                 return;
 725         }
 726
 727         DO_PROFILE_DEC(writecache_allocated_write_caches);
 728         allocated_write_caches--;
 729
 730         SMB_ASSERT(wcp->data_size == 0);
 731
 732         SAFE_FREE(wcp->data);
 733         SAFE_FREE(fsp->wcp);
 734
 735         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 736 }
 737
 738 /****************************************************************************
 739  Setup the write cache structure.
 740 ****************************************************************************/
 741
 742 static BOOL setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 743 {
 744         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 745         write_cache *wcp;
 746
 747         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 748                 return False;
 749         }
 750
 751         if(alloc_size == 0 || fsp->wcp) {
 752                 return False;
 753         }
 754
 755         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 756                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 757                 return False;
 758         }
 759
 760         wcp->file_size = file_size;
 761         wcp->offset = 0;
 762         wcp->alloc_size = alloc_size;
 763         wcp->data_size = 0;
 764         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 765                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 766                         (unsigned int)wcp->alloc_size ));
 767                 SAFE_FREE(wcp);
 768                 return False;
 769         }
 770
 771         memset(wcp->data, '\0', wcp->alloc_size );
 772
 773         fsp->wcp = wcp;
 774         DO_PROFILE_INC(writecache_allocated_write_caches);
 775         allocated_write_caches++;
 776
 777         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 778                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
 779
 780         return True;
 781 }
 782
 783 /****************************************************************************
 784  Cope with a size change.
 785 ****************************************************************************/
 786
 787 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 788 {
 789         if(fsp->wcp) {
 790                 /* The cache *must* have been flushed before we do this. */
 791                 if (fsp->wcp->data_size != 0) {
 792                         char *msg;
 793                         asprintf(&msg, "set_filelen_write_cache: size change "
 794                                  "on file %s with write cache size = %lu\n",
 795                                  fsp->fsp_name,
 796                                  (unsigned long)fsp->wcp->data_size);
 797                         smb_panic(msg);
 798                 }
 799                 fsp->wcp->file_size = file_size;
 800         }
 801 }
 802
 803 /*******************************************************************
 804  Flush a write cache struct to disk.
 805 ********************************************************************/
 806
 807 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 808 {
 809         write_cache *wcp = fsp->wcp;
 810         size_t data_size;
 811         ssize_t ret;
 812
 813         if(!wcp || !wcp->data_size) {
 814                 return 0;
 815         }
 816
 817         data_size = wcp->data_size;
 818         wcp->data_size = 0;
 819
 820         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 821
 822         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 823                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 824
 825 #ifdef WITH_PROFILE
 826         if(data_size == wcp->alloc_size) {
 827                 DO_PROFILE_INC(writecache_num_perfect_writes);
 828         }
 829 #endif
 830
 831         ret = real_write_file(fsp, wcp->data, wcp->offset, data_size);
 832
 833         /*
 834          * Ensure file size if kept up to date if write extends file.
 835          */
 836
 837         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 838                 wcp->file_size = wcp->offset + ret;
 839         }
 840
 841         return ret;
 842 }
 843
 844 /*******************************************************************
 845 sync a file
 846 ********************************************************************/
 847
 848 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, BOOL write_through)
 849 {
 850         if (fsp->fh->fd == -1)
 851                 return NT_STATUS_INVALID_HANDLE;
 852
 853         if (lp_strict_sync(SNUM(conn)) &&
 854             (lp_syncalways(SNUM(conn)) || write_through)) {
 855                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 856                 if (ret == -1) {
 857                         return map_nt_error_from_unix(errno);
 858                 }
 859                 ret = SMB_VFS_FSYNC(fsp,fsp->fh->fd);
 860                 if (ret == -1) {
 861                         return map_nt_error_from_unix(errno);
 862                 }
 863         }
 864         return NT_STATUS_OK;
 865 }
 866
 867 /************************************************************
 868  Perform a stat whether a valid fd or not.
 869 ************************************************************/
 870
 871 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 872 {
 873         if (fsp->fh->fd == -1) {
 874                 return SMB_VFS_STAT(fsp->conn, fsp->fsp_name, pst);
 875         } else {
 876                 return SMB_VFS_FSTAT(fsp,fsp->fh->fd, pst);
 877         }
 878 }