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 #include "smbd/globals.h"
  24
  25 static bool setup_write_cache(files_struct *, SMB_OFF_T);
  26
  27 /****************************************************************************
  28  Read from write cache if we can.
  29 ****************************************************************************/
  30
  31 static bool read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  32 {
  33         write_cache *wcp = fsp->wcp;
  34
  35         if(!wcp) {
  36                 return False;
  37         }
  38
  39         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
  40                 return False;
  41         }
  42
  43         memcpy(data, wcp->data + (pos - wcp->offset), n);
  44
  45         DO_PROFILE_INC(writecache_read_hits);
  46
  47         return True;
  48 }
  49
  50 /****************************************************************************
  51  Read from a file.
  52 ****************************************************************************/
  53
  54 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  55 {
  56         ssize_t ret=0,readret;
  57
  58         /* you can't read from print files */
  59         if (fsp->print_file) {
  60                 errno = EBADF;
  61                 return -1;
  62         }
  63
  64         /*
  65          * Serve from write cache if we can.
  66          */
  67
  68         if(read_from_write_cache(fsp, data, pos, n)) {
  69                 fsp->fh->pos = pos + n;
  70                 fsp->fh->position_information = fsp->fh->pos;
  71                 return n;
  72         }
  73
  74         flush_write_cache(fsp, READ_FLUSH);
  75
  76         fsp->fh->pos = pos;
  77
  78         if (n > 0) {
  79 #ifdef DMF_FIX
  80                 int numretries = 3;
  81 tryagain:
  82                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  83
  84                 if (readret == -1) {
  85                         if ((errno == EAGAIN) && numretries) {
  86                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
  87                                 (void)sleep(10);
  88                                 --numretries;
  89                                 goto tryagain;
  90                         }
  91                         return -1;
  92                 }
  93 #else /* NO DMF fix. */
  94                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  95
  96                 if (readret == -1) {
  97                         return -1;
  98                 }
  99 #endif
 100                 if (readret > 0) {
 101                         ret += readret;
 102                 }
 103         }
 104
 105         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
 106                   fsp_str_dbg(fsp), (double)pos, (unsigned long)n, (long)ret));
 107
 108         fsp->fh->pos += ret;
 109         fsp->fh->position_information = fsp->fh->pos;
 110
 111         return(ret);
 112 }
 113
 114 /****************************************************************************
 115  *Really* write to a file.
 116 ****************************************************************************/
 117
 118 static ssize_t real_write_file(struct smb_request *req,
 119                                 files_struct *fsp,
 120                                 const char *data,
 121                                 SMB_OFF_T pos,
 122                                 size_t n)
 123 {
 124         ssize_t ret;
 125
 126         if (pos == -1) {
 127                 ret = vfs_write_data(req, fsp, data, n);
 128         } else {
 129                 fsp->fh->pos = pos;
 130                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
 131                         if (vfs_fill_sparse(fsp, pos) == -1) {
 132                                 return -1;
 133                         }
 134                 }
 135                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
 136         }
 137
 138         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 139                   fsp_str_dbg(fsp), (double)pos, (unsigned long)n, (long)ret));
 140
 141         if (ret != -1) {
 142                 fsp->fh->pos += ret;
 143
 144 /* Yes - this is correct - writes don't update this. JRA. */
 145 /* Found by Samba4 tests. */
 146 #if 0
 147                 fsp->position_information = fsp->pos;
 148 #endif
 149         }
 150
 151         return ret;
 152 }
 153
 154 /****************************************************************************
 155  File size cache change.
 156  Updates size on disk but doesn't flush the cache.
 157 ****************************************************************************/
 158
 159 static int wcp_file_size_change(files_struct *fsp)
 160 {
 161         int ret;
 162         write_cache *wcp = fsp->wcp;
 163
 164         wcp->file_size = wcp->offset + wcp->data_size;
 165         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 166         if (ret == -1) {
 167                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f "
 168                          "error %s\n", fsp_str_dbg(fsp),
 169                          (double)wcp->file_size, strerror(errno)));
 170         }
 171         return ret;
 172 }
 173
 174 static void update_write_time_handler(struct event_context *ctx,
 175                                       struct timed_event *te,
 176                                       struct timeval now,
 177                                       void *private_data)
 178 {
 179         files_struct *fsp = (files_struct *)private_data;
 180
 181         /* Remove the timed event handler. */
 182         TALLOC_FREE(fsp->update_write_time_event);
 183         DEBUG(5, ("Update write time on %s\n", fsp_str_dbg(fsp)));
 184
 185         /* change the write time if not already changed by someone else */
 186         update_write_time(fsp);
 187 }
 188
 189 /*********************************************************
 190  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
 191  in the future.
 192 *********************************************************/
 193
 194 void trigger_write_time_update(struct files_struct *fsp)
 195 {
 196         int delay;
 197
 198         if (fsp->posix_open) {
 199                 /* Don't use delayed writes on POSIX files. */
 200                 return;
 201         }
 202
 203         if (fsp->write_time_forced) {
 204                 /* No point - "sticky" write times
 205                  * in effect.
 206                  */
 207                 return;
 208         }
 209
 210         if (fsp->update_write_time_triggered) {
 211                 /*
 212                  * We only update the write time
 213                  * on the first write. After that
 214                  * no other writes affect this.
 215                  */
 216                 return;
 217         }
 218         fsp->update_write_time_triggered = true;
 219
 220         delay = lp_parm_int(SNUM(fsp->conn),
 221                             "smbd", "writetimeupdatedelay",
 222                             WRITE_TIME_UPDATE_USEC_DELAY);
 223
 224         /* trigger the update 2 seconds later */
 225         fsp->update_write_time_on_close = true;
 226         fsp->update_write_time_event =
 227                 event_add_timed(smbd_event_context(), NULL,
 228                                 timeval_current_ofs(0, delay),
 229                                 update_write_time_handler, fsp);
 230 }
 231
 232 void trigger_write_time_update_immediate(struct files_struct *fsp)
 233 {
 234         if (fsp->posix_open) {
 235                 /* Don't use delayed writes on POSIX files. */
 236                 return;
 237         }
 238
 239         if (fsp->write_time_forced) {
 240                 /*
 241                  * No point - "sticky" write times
 242                  * in effect.
 243                  */
 244                 return;
 245         }
 246
 247         TALLOC_FREE(fsp->update_write_time_event);
 248         DEBUG(5, ("Update write time immediate on %s\n",
 249                   fsp_str_dbg(fsp)));
 250
 251         fsp->update_write_time_triggered = true;
 252
 253         fsp->update_write_time_on_close = false;
 254         update_write_time(fsp);
 255 }
 256
 257 /****************************************************************************
 258  Write to a file.
 259 ****************************************************************************/
 260
 261 ssize_t write_file(struct smb_request *req,
 262                         files_struct *fsp,
 263                         const char *data,
 264                         SMB_OFF_T pos,
 265                         size_t n)
 266 {
 267         write_cache *wcp = fsp->wcp;
 268         ssize_t total_written = 0;
 269         int write_path = -1;
 270
 271         if (fsp->print_file) {
 272                 uint32 jobid;
 273
 274                 if (!rap_to_pjobid(fsp->rap_print_jobid, NULL, &jobid)) {
 275                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 276                                                 (unsigned int)fsp->rap_print_jobid ));
 277                         errno = EBADF;
 278                         return -1;
 279                 }
 280
 281                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 282         }
 283
 284         if (!fsp->can_write) {
 285                 errno = EPERM;
 286                 return -1;
 287         }
 288
 289         if (!fsp->modified) {
 290                 fsp->modified = True;
 291
 292                 if (SMB_VFS_FSTAT(fsp, &fsp->fsp_name->st) == 0) {
 293                         int dosmode;
 294                         trigger_write_time_update(fsp);
 295                         dosmode = dos_mode(fsp->conn, fsp->fsp_name);
 296                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 297                                         MAP_ARCHIVE(fsp->conn)) &&
 298                                         !IS_DOS_ARCHIVE(dosmode)) {
 299                                 file_set_dosmode(fsp->conn, fsp->fsp_name,
 300                                                  dosmode | aARCH, NULL, false);
 301                         }
 302
 303                         /*
 304                          * If this is the first write and we have an exclusive oplock then setup
 305                          * the write cache.
 306                          */
 307
 308                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 309                                 setup_write_cache(fsp,
 310                                                  fsp->fsp_name->st.st_ex_size);
 311                                 wcp = fsp->wcp;
 312                         }
 313                 }
 314         }
 315
 316 #ifdef WITH_PROFILE
 317         DO_PROFILE_INC(writecache_total_writes);
 318         if (!fsp->oplock_type) {
 319                 DO_PROFILE_INC(writecache_non_oplock_writes);
 320         }
 321 #endif
 322
 323         /*
 324          * If this file is level II oplocked then we need
 325          * to grab the shared memory lock and inform all
 326          * other files with a level II lock that they need
 327          * to flush their read caches. We keep the lock over
 328          * the shared memory area whilst doing this.
 329          */
 330
 331         /* This should actually be improved to span the write. */
 332         contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_WRITE);
 333         contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_WRITE);
 334
 335 #ifdef WITH_PROFILE
 336         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 337                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 338 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 339                         profile_p->writecache_init_writes,
 340                         profile_p->writecache_abutted_writes,
 341                         profile_p->writecache_total_writes,
 342                         profile_p->writecache_non_oplock_writes,
 343                         profile_p->writecache_allocated_write_caches,
 344                         profile_p->writecache_num_write_caches,
 345                         profile_p->writecache_direct_writes,
 346                         profile_p->writecache_num_perfect_writes,
 347                         profile_p->writecache_read_hits ));
 348
 349                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 350                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 351                         profile_p->writecache_flushed_writes[READ_FLUSH],
 352                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 353                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 354                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 355                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 356                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 357         }
 358 #endif
 359
 360         if (wcp && req->unread_bytes) {
 361                 /* If we're using receivefile don't
 362                  * deal with a write cache.
 363                  */
 364                 flush_write_cache(fsp, WRITE_FLUSH);
 365                 delete_write_cache(fsp);
 366                 wcp = NULL;
 367         }
 368
 369         if(!wcp) {
 370                 DO_PROFILE_INC(writecache_direct_writes);
 371                 total_written = real_write_file(req, fsp, data, pos, n);
 372                 return total_written;
 373         }
 374
 375         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f "
 376                  "wcp->data_size=%u\n", fsp_str_dbg(fsp), fsp->fh->fd,
 377                  (double)pos, (unsigned int)n, (double)wcp->offset,
 378                  (unsigned int)wcp->data_size));
 379
 380         fsp->fh->pos = pos + n;
 381
 382         /*
 383          * If we have active cache and it isn't contiguous then we flush.
 384          * NOTE: There is a small problem with running out of disk ....
 385          */
 386
 387         if (wcp->data_size) {
 388                 bool cache_flush_needed = False;
 389
 390                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 391
 392                         /* ASCII art.... JRA.
 393
 394       +--------------+-----
 395       | Cached data  | Rest of allocated cache buffer....
 396       +--------------+-----
 397
 398             +-------------------+
 399             | Data to write     |
 400             +-------------------+
 401
 402                         */
 403
 404                         /*
 405                          * Start of write overlaps or abutts the existing data.
 406                          */
 407
 408                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 409
 410                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 411
 412                         /*
 413                          * Update the current buffer size with the new data.
 414                          */
 415
 416                         if(pos + data_used > wcp->offset + wcp->data_size) {
 417                                 wcp->data_size = pos + data_used - 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                          * If we used all the data then
 432                          * return here.
 433                          */
 434
 435                         if(n == data_used) {
 436                                 return n;
 437                         } else {
 438                                 cache_flush_needed = True;
 439                         }
 440                         /*
 441                          * Move the start of data forward by the amount used,
 442                          * cut down the amount left by the same amount.
 443                          */
 444
 445                         data += data_used;
 446                         pos += data_used;
 447                         n -= data_used;
 448
 449                         DO_PROFILE_INC(writecache_abutted_writes);
 450                         total_written = data_used;
 451
 452                         write_path = 1;
 453
 454                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 455                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 456
 457                         /* ASCII art.... JRA.
 458
 459                         +---------------+
 460                         | Cache buffer  |
 461                         +---------------+
 462
 463             +-------------------+
 464             | Data to write     |
 465             +-------------------+
 466
 467                         */
 468
 469                         /*
 470                          * End of write overlaps the existing data.
 471                          */
 472
 473                         size_t data_used = pos + n - wcp->offset;
 474
 475                         memcpy(wcp->data, data + n - data_used, data_used);
 476
 477                         /*
 478                          * Update the current buffer size with the new data.
 479                          */
 480
 481                         if(pos + n > wcp->offset + wcp->data_size) {
 482                                 wcp->data_size = pos + n - wcp->offset;
 483                         }
 484
 485                         /*
 486                          * Update the file size if changed.
 487                          */
 488
 489                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 490                                 if (wcp_file_size_change(fsp) == -1) {
 491                                         return -1;
 492                                 }
 493                         }
 494
 495                         /*
 496                          * We don't need to move the start of data, but we
 497                          * cut down the amount left by the amount used.
 498                          */
 499
 500                         n -= data_used;
 501
 502                         /*
 503                          * We cannot have used all the data here.
 504                          */
 505
 506                         cache_flush_needed = True;
 507
 508                         DO_PROFILE_INC(writecache_abutted_writes);
 509                         total_written = data_used;
 510
 511                         write_path = 2;
 512
 513                 } else if ( (pos >= wcp->file_size) &&
 514                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 515                                         (pos > wcp->offset + wcp->data_size) &&
 516                                         (pos < wcp->offset + wcp->alloc_size) ) {
 517
 518                         /* ASCII art.... JRA.
 519
 520                        End of file ---->|
 521
 522                         +---------------+---------------+
 523                         | Cached data   | Cache buffer  |
 524                         +---------------+---------------+
 525
 526                                               +-------------------+
 527                                               | Data to write     |
 528                                               +-------------------+
 529
 530                         */
 531
 532                         /*
 533                          * Non-contiguous write part of which fits within
 534                          * the cache buffer and is extending the file
 535                          * and the cache contents reflect the current
 536                          * data up to the current end of the file.
 537                          */
 538
 539                         size_t data_used;
 540
 541                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 542                                 data_used = n;
 543                         } else {
 544                                 data_used = wcp->offset + wcp->alloc_size - pos;
 545                         }
 546
 547                         /*
 548                          * Fill in the non-continuous area with zeros.
 549                          */
 550
 551                         memset(wcp->data + wcp->data_size, '\0',
 552                                 pos - (wcp->offset + wcp->data_size) );
 553
 554                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 555
 556                         /*
 557                          * Update the current buffer size with the new data.
 558                          */
 559
 560                         if(pos + data_used > wcp->offset + wcp->data_size) {
 561                                 wcp->data_size = pos + data_used - wcp->offset;
 562                         }
 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                         /*
 575                          * If we used all the data then
 576                          * return here.
 577                          */
 578
 579                         if(n == data_used) {
 580                                 return n;
 581                         } else {
 582                                 cache_flush_needed = True;
 583                         }
 584
 585                         /*
 586                          * Move the start of data forward by the amount used,
 587                          * cut down the amount left by the same amount.
 588                          */
 589
 590                         data += data_used;
 591                         pos += data_used;
 592                         n -= data_used;
 593
 594                         DO_PROFILE_INC(writecache_abutted_writes);
 595                         total_written = data_used;
 596
 597                         write_path = 3;
 598
 599                 } else if ( (pos >= wcp->file_size) &&
 600                             (n == 1) &&
 601                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 602                             (pos < wcp->file_size + wcp->alloc_size)) {
 603
 604                         /*
 605
 606                 End of file ---->|
 607
 608                  +---------------+---------------+
 609                  | Cached data   | Cache buffer  |
 610                  +---------------+---------------+
 611
 612                                  |<------- allocated size ---------------->|
 613
 614                                                          +--------+
 615                                                          | 1 Byte |
 616                                                          +--------+
 617
 618                         MS-Office seems to do this a lot to determine if there's enough
 619                         space on the filesystem to write a new file.
 620
 621                         Change to :
 622
 623                 End of file ---->|
 624                                  +-----------------------+--------+
 625                                  | Zeroed Cached data    | 1 Byte |
 626                                  +-----------------------+--------+
 627                         */
 628
 629                         flush_write_cache(fsp, WRITE_FLUSH);
 630                         wcp->offset = wcp->file_size;
 631                         wcp->data_size = pos - wcp->file_size + 1;
 632                         memset(wcp->data, '\0', wcp->data_size);
 633                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 634
 635                         /*
 636                          * Update the file size if changed.
 637                          */
 638
 639                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 640                                 if (wcp_file_size_change(fsp) == -1) {
 641                                         return -1;
 642                                 }
 643                         }
 644
 645                         return n;
 646
 647                 } else {
 648
 649                         /* ASCII art..... JRA.
 650
 651    Case 1).
 652
 653                         +---------------+---------------+
 654                         | Cached data   | Cache buffer  |
 655                         +---------------+---------------+
 656
 657                                                               +-------------------+
 658                                                               | Data to write     |
 659                                                               +-------------------+
 660
 661    Case 2).
 662
 663                            +---------------+---------------+
 664                            | Cached data   | Cache buffer  |
 665                            +---------------+---------------+
 666
 667    +-------------------+
 668    | Data to write     |
 669    +-------------------+
 670
 671     Case 3).
 672
 673                            +---------------+---------------+
 674                            | Cached data   | Cache buffer  |
 675                            +---------------+---------------+
 676
 677                   +-----------------------------------------------------+
 678                   | Data to write                                       |
 679                   +-----------------------------------------------------+
 680
 681                   */
 682
 683                         /*
 684                          * Write is bigger than buffer, or there is no overlap on the
 685                          * low or high ends.
 686                          */
 687
 688                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 689 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 690
 691                         /*
 692                          * If write would fit in the cache, and is larger than
 693                          * the data already in the cache, flush the cache and
 694                          * preferentially copy the data new data into it. Otherwise
 695                          * just write the data directly.
 696                          */
 697
 698                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 699                                 cache_flush_needed = True;
 700                         } else {
 701                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 702
 703                                 /*
 704                                  * If the write overlaps the entire cache, then
 705                                  * discard the current contents of the cache.
 706                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 707                                  */
 708
 709                                 if ((pos <= wcp->offset) &&
 710                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 711                                         DEBUG(9,("write_file: discarding overwritten write \
 712 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 713                                         wcp->data_size = 0;
 714                                 }
 715
 716                                 DO_PROFILE_INC(writecache_direct_writes);
 717                                 if (ret == -1) {
 718                                         return ret;
 719                                 }
 720
 721                                 if (pos + ret > wcp->file_size) {
 722                                         wcp->file_size = pos + ret;
 723                                 }
 724
 725                                 return ret;
 726                         }
 727
 728                         write_path = 4;
 729
 730                 }
 731
 732                 if (cache_flush_needed) {
 733                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 734 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 735                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 736                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 737
 738                         flush_write_cache(fsp, WRITE_FLUSH);
 739                 }
 740         }
 741
 742         /*
 743          * If the write request is bigger than the cache
 744          * size, write it all out.
 745          */
 746
 747         if (n > wcp->alloc_size ) {
 748                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 749                 if (ret == -1) {
 750                         return -1;
 751                 }
 752
 753                 if (pos + ret > wcp->file_size) {
 754                         wcp->file_size = pos + n;
 755                 }
 756
 757                 DO_PROFILE_INC(writecache_direct_writes);
 758                 return total_written + n;
 759         }
 760
 761         /*
 762          * If there's any data left, cache it.
 763          */
 764
 765         if (n) {
 766 #ifdef WITH_PROFILE
 767                 if (wcp->data_size) {
 768                         DO_PROFILE_INC(writecache_abutted_writes);
 769                 } else {
 770                         DO_PROFILE_INC(writecache_init_writes);
 771                 }
 772 #endif
 773                 memcpy(wcp->data+wcp->data_size, data, n);
 774                 if (wcp->data_size == 0) {
 775                         wcp->offset = pos;
 776                         DO_PROFILE_INC(writecache_num_write_caches);
 777                 }
 778                 wcp->data_size += n;
 779
 780                 /*
 781                  * Update the file size if changed.
 782                  */
 783
 784                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 785                         if (wcp_file_size_change(fsp) == -1) {
 786                                 return -1;
 787                         }
 788                 }
 789                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 790                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 791
 792                 total_written += n;
 793                 return total_written; /* .... that's a write :) */
 794         }
 795
 796         return total_written;
 797 }
 798
 799 /****************************************************************************
 800  Delete the write cache structure.
 801 ****************************************************************************/
 802
 803 void delete_write_cache(files_struct *fsp)
 804 {
 805         write_cache *wcp;
 806
 807         if(!fsp) {
 808                 return;
 809         }
 810
 811         if(!(wcp = fsp->wcp)) {
 812                 return;
 813         }
 814
 815         DO_PROFILE_DEC(writecache_allocated_write_caches);
 816         allocated_write_caches--;
 817
 818         SMB_ASSERT(wcp->data_size == 0);
 819
 820         SAFE_FREE(wcp->data);
 821         SAFE_FREE(fsp->wcp);
 822
 823         DEBUG(10,("delete_write_cache: File %s deleted write cache\n",
 824                   fsp_str_dbg(fsp)));
 825 }
 826
 827 /****************************************************************************
 828  Setup the write cache structure.
 829 ****************************************************************************/
 830
 831 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 832 {
 833         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 834         write_cache *wcp;
 835
 836         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 837                 return False;
 838         }
 839
 840         if(alloc_size == 0 || fsp->wcp) {
 841                 return False;
 842         }
 843
 844         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 845                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 846                 return False;
 847         }
 848
 849         wcp->file_size = file_size;
 850         wcp->offset = 0;
 851         wcp->alloc_size = alloc_size;
 852         wcp->data_size = 0;
 853         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 854                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 855                         (unsigned int)wcp->alloc_size ));
 856                 SAFE_FREE(wcp);
 857                 return False;
 858         }
 859
 860         memset(wcp->data, '\0', wcp->alloc_size );
 861
 862         fsp->wcp = wcp;
 863         DO_PROFILE_INC(writecache_allocated_write_caches);
 864         allocated_write_caches++;
 865
 866         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 867                   fsp_str_dbg(fsp), (unsigned long)wcp->alloc_size));
 868
 869         return True;
 870 }
 871
 872 /****************************************************************************
 873  Cope with a size change.
 874 ****************************************************************************/
 875
 876 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 877 {
 878         if(fsp->wcp) {
 879                 /* The cache *must* have been flushed before we do this. */
 880                 if (fsp->wcp->data_size != 0) {
 881                         char *msg;
 882                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 883                                  "on file %s with write cache size = %lu\n",
 884                                  fsp->fsp_name->base_name,
 885                                  (unsigned long)fsp->wcp->data_size) != -1) {
 886                                 smb_panic(msg);
 887                         } else {
 888                                 smb_panic("set_filelen_write_cache");
 889                         }
 890                 }
 891                 fsp->wcp->file_size = file_size;
 892         }
 893 }
 894
 895 /*******************************************************************
 896  Flush a write cache struct to disk.
 897 ********************************************************************/
 898
 899 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 900 {
 901         write_cache *wcp = fsp->wcp;
 902         size_t data_size;
 903         ssize_t ret;
 904
 905         if(!wcp || !wcp->data_size) {
 906                 return 0;
 907         }
 908
 909         data_size = wcp->data_size;
 910         wcp->data_size = 0;
 911
 912         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 913
 914         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 915                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 916
 917 #ifdef WITH_PROFILE
 918         if(data_size == wcp->alloc_size) {
 919                 DO_PROFILE_INC(writecache_num_perfect_writes);
 920         }
 921 #endif
 922
 923         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 924
 925         /*
 926          * Ensure file size if kept up to date if write extends file.
 927          */
 928
 929         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 930                 wcp->file_size = wcp->offset + ret;
 931         }
 932
 933         return ret;
 934 }
 935
 936 /*******************************************************************
 937 sync a file
 938 ********************************************************************/
 939
 940 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
 941 {
 942         if (fsp->fh->fd == -1)
 943                 return NT_STATUS_INVALID_HANDLE;
 944
 945         if (lp_strict_sync(SNUM(conn)) &&
 946             (lp_syncalways(SNUM(conn)) || write_through)) {
 947                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 948                 if (ret == -1) {
 949                         return map_nt_error_from_unix(errno);
 950                 }
 951                 ret = SMB_VFS_FSYNC(fsp);
 952                 if (ret == -1) {
 953                         return map_nt_error_from_unix(errno);
 954                 }
 955         }
 956         return NT_STATUS_OK;
 957 }
 958
 959 /************************************************************
 960  Perform a stat whether a valid fd or not.
 961 ************************************************************/
 962
 963 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 964 {
 965         if (fsp->fh->fd == -1) {
 966                 int ret;
 967
 968                 ret = SMB_VFS_STAT(fsp->conn, fsp->fsp_name);
 969                 if (ret != -1) {
 970                         *pst = fsp->fsp_name->st;
 971                 }
 972                 return ret;
 973         } else {
 974                 return SMB_VFS_FSTAT(fsp, pst);
 975         }
 976 }