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