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,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                 /*
 146                  * It turns out that setting the last write time from a Windows
 147                  * client stops any subsequent writes from updating the write time.
 148                  * Doing this after the write gives a race condition here where
 149                  * a stat may see the changed write time before we reset it here,
 150                  * but it's cheaper than having to store the write time in shared
 151                  * memory and look it up using dev/inode across all running smbd's.
 152                  * The 99% solution will hopefully be good enough in this case. JRA.
 153                  */
 154
 155                 if (!null_timespec(fsp->pending_modtime)) {
 156                         set_filetime(fsp->conn, fsp->fsp_name,
 157                                         fsp->pending_modtime);
 158
 159                         /* If we didn't get the "set modtime" call ourselves, we must
 160                            store the last write time to restore on close. JRA. */
 161                         if (!fsp->pending_modtime_owner) {
 162                                 fsp->last_write_time = timespec_current();
 163                         }
 164                 }
 165
 166 /* Yes - this is correct - writes don't update this. JRA. */
 167 /* Found by Samba4 tests. */
 168 #if 0
 169                 fsp->position_information = fsp->pos;
 170 #endif
 171         }
 172
 173         return ret;
 174 }
 175
 176 /****************************************************************************
 177  File size cache change.
 178  Updates size on disk but doesn't flush the cache.
 179 ****************************************************************************/
 180
 181 static int wcp_file_size_change(files_struct *fsp)
 182 {
 183         int ret;
 184         write_cache *wcp = fsp->wcp;
 185
 186         wcp->file_size = wcp->offset + wcp->data_size;
 187         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 188         if (ret == -1) {
 189                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
 190                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
 191         }
 192         return ret;
 193 }
 194
 195 /****************************************************************************
 196  Write to a file.
 197 ****************************************************************************/
 198
 199 ssize_t write_file(struct smb_request *req,
 200                         files_struct *fsp,
 201                         const char *data,
 202                         SMB_OFF_T pos,
 203                         size_t n)
 204 {
 205         write_cache *wcp = fsp->wcp;
 206         ssize_t total_written = 0;
 207         int write_path = -1;
 208
 209         if (fsp->print_file) {
 210                 fstring sharename;
 211                 uint32 jobid;
 212
 213                 if (!rap_to_pjobid(fsp->rap_print_jobid, sharename, &jobid)) {
 214                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 215                                                 (unsigned int)fsp->rap_print_jobid ));
 216                         errno = EBADF;
 217                         return -1;
 218                 }
 219
 220                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 221         }
 222
 223         if (!fsp->can_write) {
 224                 errno = EPERM;
 225                 return -1;
 226         }
 227
 228         if (!fsp->modified) {
 229                 SMB_STRUCT_STAT st;
 230                 fsp->modified = True;
 231
 232                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
 233                         int dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 234                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 235                                         MAP_ARCHIVE(fsp->conn)) &&
 236                                         !IS_DOS_ARCHIVE(dosmode)) {
 237                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
 238                                                 dosmode | aARCH,&st,
 239                                                 NULL,
 240                                                 false);
 241                         }
 242
 243                         /*
 244                          * If this is the first write and we have an exclusive oplock then setup
 245                          * the write cache.
 246                          */
 247
 248                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 249                                 setup_write_cache(fsp, st.st_size);
 250                                 wcp = fsp->wcp;
 251                         }
 252                 }
 253         }
 254
 255 #ifdef WITH_PROFILE
 256         DO_PROFILE_INC(writecache_total_writes);
 257         if (!fsp->oplock_type) {
 258                 DO_PROFILE_INC(writecache_non_oplock_writes);
 259         }
 260 #endif
 261
 262         /*
 263          * If this file is level II oplocked then we need
 264          * to grab the shared memory lock and inform all
 265          * other files with a level II lock that they need
 266          * to flush their read caches. We keep the lock over
 267          * the shared memory area whilst doing this.
 268          */
 269
 270         release_level_2_oplocks_on_change(fsp);
 271
 272 #ifdef WITH_PROFILE
 273         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 274                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 275 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 276                         profile_p->writecache_init_writes,
 277                         profile_p->writecache_abutted_writes,
 278                         profile_p->writecache_total_writes,
 279                         profile_p->writecache_non_oplock_writes,
 280                         profile_p->writecache_allocated_write_caches,
 281                         profile_p->writecache_num_write_caches,
 282                         profile_p->writecache_direct_writes,
 283                         profile_p->writecache_num_perfect_writes,
 284                         profile_p->writecache_read_hits ));
 285
 286                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 287                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 288                         profile_p->writecache_flushed_writes[READ_FLUSH],
 289                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 290                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 291                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 292                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 293                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 294         }
 295 #endif
 296
 297         if (wcp && req->unread_bytes) {
 298                 /* If we're using receivefile don't
 299                  * deal with a write cache.
 300                  */
 301                 flush_write_cache(fsp, WRITE_FLUSH);
 302                 delete_write_cache(fsp);
 303                 wcp = NULL;
 304         }
 305
 306         if(!wcp) {
 307                 DO_PROFILE_INC(writecache_direct_writes);
 308                 total_written = real_write_file(req, fsp, data, pos, n);
 309                 return total_written;
 310         }
 311
 312         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 313                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 314
 315         fsp->fh->pos = pos + n;
 316
 317         /*
 318          * If we have active cache and it isn't contiguous then we flush.
 319          * NOTE: There is a small problem with running out of disk ....
 320          */
 321
 322         if (wcp->data_size) {
 323                 bool cache_flush_needed = False;
 324
 325                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 326
 327                         /* ASCII art.... JRA.
 328
 329       +--------------+-----
 330       | Cached data  | Rest of allocated cache buffer....
 331       +--------------+-----
 332
 333             +-------------------+
 334             | Data to write     |
 335             +-------------------+
 336
 337                         */
 338
 339                         /*
 340                          * Start of write overlaps or abutts the existing data.
 341                          */
 342
 343                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 344
 345                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 346
 347                         /*
 348                          * Update the current buffer size with the new data.
 349                          */
 350
 351                         if(pos + data_used > wcp->offset + wcp->data_size) {
 352                                 wcp->data_size = pos + data_used - wcp->offset;
 353                         }
 354
 355                         /*
 356                          * Update the file size if changed.
 357                          */
 358
 359                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 360                                 if (wcp_file_size_change(fsp) == -1) {
 361                                         return -1;
 362                                 }
 363                         }
 364
 365                         /*
 366                          * If we used all the data then
 367                          * return here.
 368                          */
 369
 370                         if(n == data_used) {
 371                                 return n;
 372                         } else {
 373                                 cache_flush_needed = True;
 374                         }
 375                         /*
 376                          * Move the start of data forward by the amount used,
 377                          * cut down the amount left by the same amount.
 378                          */
 379
 380                         data += data_used;
 381                         pos += data_used;
 382                         n -= data_used;
 383
 384                         DO_PROFILE_INC(writecache_abutted_writes);
 385                         total_written = data_used;
 386
 387                         write_path = 1;
 388
 389                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 390                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 391
 392                         /* ASCII art.... JRA.
 393
 394                         +---------------+
 395                         | Cache buffer  |
 396                         +---------------+
 397
 398             +-------------------+
 399             | Data to write     |
 400             +-------------------+
 401
 402                         */
 403
 404                         /*
 405                          * End of write overlaps the existing data.
 406                          */
 407
 408                         size_t data_used = pos + n - wcp->offset;
 409
 410                         memcpy(wcp->data, data + n - data_used, data_used);
 411
 412                         /*
 413                          * Update the current buffer size with the new data.
 414                          */
 415
 416                         if(pos + n > wcp->offset + wcp->data_size) {
 417                                 wcp->data_size = pos + n - wcp->offset;
 418                         }
 419
 420                         /*
 421                          * Update the file size if changed.
 422                          */
 423
 424                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 425                                 if (wcp_file_size_change(fsp) == -1) {
 426                                         return -1;
 427                                 }
 428                         }
 429
 430                         /*
 431                          * We don't need to move the start of data, but we
 432                          * cut down the amount left by the amount used.
 433                          */
 434
 435                         n -= data_used;
 436
 437                         /*
 438                          * We cannot have used all the data here.
 439                          */
 440
 441                         cache_flush_needed = True;
 442
 443                         DO_PROFILE_INC(writecache_abutted_writes);
 444                         total_written = data_used;
 445
 446                         write_path = 2;
 447
 448                 } else if ( (pos >= wcp->file_size) &&
 449                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 450                                         (pos > wcp->offset + wcp->data_size) &&
 451                                         (pos < wcp->offset + wcp->alloc_size) ) {
 452
 453                         /* ASCII art.... JRA.
 454
 455                        End of file ---->|
 456
 457                         +---------------+---------------+
 458                         | Cached data   | Cache buffer  |
 459                         +---------------+---------------+
 460
 461                                               +-------------------+
 462                                               | Data to write     |
 463                                               +-------------------+
 464
 465                         */
 466
 467                         /*
 468                          * Non-contiguous write part of which fits within
 469                          * the cache buffer and is extending the file
 470                          * and the cache contents reflect the current
 471                          * data up to the current end of the file.
 472                          */
 473
 474                         size_t data_used;
 475
 476                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 477                                 data_used = n;
 478                         } else {
 479                                 data_used = wcp->offset + wcp->alloc_size - pos;
 480                         }
 481
 482                         /*
 483                          * Fill in the non-continuous area with zeros.
 484                          */
 485
 486                         memset(wcp->data + wcp->data_size, '\0',
 487                                 pos - (wcp->offset + wcp->data_size) );
 488
 489                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 490
 491                         /*
 492                          * Update the current buffer size with the new data.
 493                          */
 494
 495                         if(pos + data_used > wcp->offset + wcp->data_size) {
 496                                 wcp->data_size = pos + data_used - wcp->offset;
 497                         }
 498
 499                         /*
 500                          * Update the file size if changed.
 501                          */
 502
 503                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 504                                 if (wcp_file_size_change(fsp) == -1) {
 505                                         return -1;
 506                                 }
 507                         }
 508
 509                         /*
 510                          * If we used all the data then
 511                          * return here.
 512                          */
 513
 514                         if(n == data_used) {
 515                                 return n;
 516                         } else {
 517                                 cache_flush_needed = True;
 518                         }
 519
 520                         /*
 521                          * Move the start of data forward by the amount used,
 522                          * cut down the amount left by the same amount.
 523                          */
 524
 525                         data += data_used;
 526                         pos += data_used;
 527                         n -= data_used;
 528
 529                         DO_PROFILE_INC(writecache_abutted_writes);
 530                         total_written = data_used;
 531
 532                         write_path = 3;
 533
 534                 } else if ( (pos >= wcp->file_size) &&
 535                             (n == 1) &&
 536                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 537                             (pos < wcp->file_size + wcp->alloc_size)) {
 538
 539                         /*
 540
 541                 End of file ---->|
 542
 543                  +---------------+---------------+
 544                  | Cached data   | Cache buffer  |
 545                  +---------------+---------------+
 546
 547                                  |<------- allocated size ---------------->|
 548
 549                                                          +--------+
 550                                                          | 1 Byte |
 551                                                          +--------+
 552
 553                         MS-Office seems to do this a lot to determine if there's enough
 554                         space on the filesystem to write a new file.
 555
 556                         Change to :
 557
 558                 End of file ---->|
 559                                  +-----------------------+--------+
 560                                  | Zeroed Cached data    | 1 Byte |
 561                                  +-----------------------+--------+
 562                         */
 563
 564                         flush_write_cache(fsp, WRITE_FLUSH);
 565                         wcp->offset = wcp->file_size;
 566                         wcp->data_size = pos - wcp->file_size + 1;
 567                         memset(wcp->data, '\0', wcp->data_size);
 568                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 569
 570                         /*
 571                          * Update the file size if changed.
 572                          */
 573
 574                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 575                                 if (wcp_file_size_change(fsp) == -1) {
 576                                         return -1;
 577                                 }
 578                         }
 579
 580                         return n;
 581
 582                 } else {
 583
 584                         /* ASCII art..... JRA.
 585
 586    Case 1).
 587
 588                         +---------------+---------------+
 589                         | Cached data   | Cache buffer  |
 590                         +---------------+---------------+
 591
 592                                                               +-------------------+
 593                                                               | Data to write     |
 594                                                               +-------------------+
 595
 596    Case 2).
 597
 598                            +---------------+---------------+
 599                            | Cached data   | Cache buffer  |
 600                            +---------------+---------------+
 601
 602    +-------------------+
 603    | Data to write     |
 604    +-------------------+
 605
 606     Case 3).
 607
 608                            +---------------+---------------+
 609                            | Cached data   | Cache buffer  |
 610                            +---------------+---------------+
 611
 612                   +-----------------------------------------------------+
 613                   | Data to write                                       |
 614                   +-----------------------------------------------------+
 615
 616                   */
 617
 618                         /*
 619                          * Write is bigger than buffer, or there is no overlap on the
 620                          * low or high ends.
 621                          */
 622
 623                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 624 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 625
 626                         /*
 627                          * If write would fit in the cache, and is larger than
 628                          * the data already in the cache, flush the cache and
 629                          * preferentially copy the data new data into it. Otherwise
 630                          * just write the data directly.
 631                          */
 632
 633                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 634                                 cache_flush_needed = True;
 635                         } else {
 636                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 637
 638                                 /*
 639                                  * If the write overlaps the entire cache, then
 640                                  * discard the current contents of the cache.
 641                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 642                                  */
 643
 644                                 if ((pos <= wcp->offset) &&
 645                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 646                                         DEBUG(9,("write_file: discarding overwritten write \
 647 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 648                                         wcp->data_size = 0;
 649                                 }
 650
 651                                 DO_PROFILE_INC(writecache_direct_writes);
 652                                 if (ret == -1) {
 653                                         return ret;
 654                                 }
 655
 656                                 if (pos + ret > wcp->file_size) {
 657                                         wcp->file_size = pos + ret;
 658                                 }
 659
 660                                 return ret;
 661                         }
 662
 663                         write_path = 4;
 664
 665                 }
 666
 667                 if (cache_flush_needed) {
 668                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 669 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 670                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 671                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 672
 673                         flush_write_cache(fsp, WRITE_FLUSH);
 674                 }
 675         }
 676
 677         /*
 678          * If the write request is bigger than the cache
 679          * size, write it all out.
 680          */
 681
 682         if (n > wcp->alloc_size ) {
 683                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 684                 if (ret == -1) {
 685                         return -1;
 686                 }
 687
 688                 if (pos + ret > wcp->file_size) {
 689                         wcp->file_size = pos + n;
 690                 }
 691
 692                 DO_PROFILE_INC(writecache_direct_writes);
 693                 return total_written + n;
 694         }
 695
 696         /*
 697          * If there's any data left, cache it.
 698          */
 699
 700         if (n) {
 701 #ifdef WITH_PROFILE
 702                 if (wcp->data_size) {
 703                         DO_PROFILE_INC(writecache_abutted_writes);
 704                 } else {
 705                         DO_PROFILE_INC(writecache_init_writes);
 706                 }
 707 #endif
 708                 memcpy(wcp->data+wcp->data_size, data, n);
 709                 if (wcp->data_size == 0) {
 710                         wcp->offset = pos;
 711                         DO_PROFILE_INC(writecache_num_write_caches);
 712                 }
 713                 wcp->data_size += n;
 714
 715                 /*
 716                  * Update the file size if changed.
 717                  */
 718
 719                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 720                         if (wcp_file_size_change(fsp) == -1) {
 721                                 return -1;
 722                         }
 723                 }
 724                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 725                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 726
 727                 total_written += n;
 728                 return total_written; /* .... that's a write :) */
 729         }
 730
 731         return total_written;
 732 }
 733
 734 /****************************************************************************
 735  Delete the write cache structure.
 736 ****************************************************************************/
 737
 738 void delete_write_cache(files_struct *fsp)
 739 {
 740         write_cache *wcp;
 741
 742         if(!fsp) {
 743                 return;
 744         }
 745
 746         if(!(wcp = fsp->wcp)) {
 747                 return;
 748         }
 749
 750         DO_PROFILE_DEC(writecache_allocated_write_caches);
 751         allocated_write_caches--;
 752
 753         SMB_ASSERT(wcp->data_size == 0);
 754
 755         SAFE_FREE(wcp->data);
 756         SAFE_FREE(fsp->wcp);
 757
 758         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 759 }
 760
 761 /****************************************************************************
 762  Setup the write cache structure.
 763 ****************************************************************************/
 764
 765 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 766 {
 767         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 768         write_cache *wcp;
 769
 770         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 771                 return False;
 772         }
 773
 774         if(alloc_size == 0 || fsp->wcp) {
 775                 return False;
 776         }
 777
 778         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 779                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 780                 return False;
 781         }
 782
 783         wcp->file_size = file_size;
 784         wcp->offset = 0;
 785         wcp->alloc_size = alloc_size;
 786         wcp->data_size = 0;
 787         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 788                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 789                         (unsigned int)wcp->alloc_size ));
 790                 SAFE_FREE(wcp);
 791                 return False;
 792         }
 793
 794         memset(wcp->data, '\0', wcp->alloc_size );
 795
 796         fsp->wcp = wcp;
 797         DO_PROFILE_INC(writecache_allocated_write_caches);
 798         allocated_write_caches++;
 799
 800         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 801                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
 802
 803         return True;
 804 }
 805
 806 /****************************************************************************
 807  Cope with a size change.
 808 ****************************************************************************/
 809
 810 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 811 {
 812         if(fsp->wcp) {
 813                 /* The cache *must* have been flushed before we do this. */
 814                 if (fsp->wcp->data_size != 0) {
 815                         char *msg;
 816                         asprintf(&msg, "set_filelen_write_cache: size change "
 817                                  "on file %s with write cache size = %lu\n",
 818                                  fsp->fsp_name,
 819                                  (unsigned long)fsp->wcp->data_size);
 820                         smb_panic(msg);
 821                 }
 822                 fsp->wcp->file_size = file_size;
 823         }
 824 }
 825
 826 /*******************************************************************
 827  Flush a write cache struct to disk.
 828 ********************************************************************/
 829
 830 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 831 {
 832         write_cache *wcp = fsp->wcp;
 833         size_t data_size;
 834         ssize_t ret;
 835
 836         if(!wcp || !wcp->data_size) {
 837                 return 0;
 838         }
 839
 840         data_size = wcp->data_size;
 841         wcp->data_size = 0;
 842
 843         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 844
 845         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 846                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 847
 848 #ifdef WITH_PROFILE
 849         if(data_size == wcp->alloc_size) {
 850                 DO_PROFILE_INC(writecache_num_perfect_writes);
 851         }
 852 #endif
 853
 854         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 855
 856         /*
 857          * Ensure file size if kept up to date if write extends file.
 858          */
 859
 860         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 861                 wcp->file_size = wcp->offset + ret;
 862         }
 863
 864         return ret;
 865 }
 866
 867 /*******************************************************************
 868 sync a file
 869 ********************************************************************/
 870
 871 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
 872 {
 873         if (fsp->fh->fd == -1)
 874                 return NT_STATUS_INVALID_HANDLE;
 875
 876         if (lp_strict_sync(SNUM(conn)) &&
 877             (lp_syncalways(SNUM(conn)) || write_through)) {
 878                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 879                 if (ret == -1) {
 880                         return map_nt_error_from_unix(errno);
 881                 }
 882                 ret = SMB_VFS_FSYNC(fsp);
 883                 if (ret == -1) {
 884                         return map_nt_error_from_unix(errno);
 885                 }
 886         }
 887         return NT_STATUS_OK;
 888 }
 889
 890 /************************************************************
 891  Perform a stat whether a valid fd or not.
 892 ************************************************************/
 893
 894 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 895 {
 896         if (fsp->fh->fd == -1) {
 897                 return SMB_VFS_STAT(fsp->conn, fsp->fsp_name, pst);
 898         } else {
 899                 return SMB_VFS_FSTAT(fsp, pst);
 900         }
 901 }