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                 return -1;
  61         }
  62
  63         /*
  64          * Serve from write cache if we can.
  65          */
  66
  67         if(read_from_write_cache(fsp, data, pos, n)) {
  68                 fsp->fh->pos = pos + n;
  69                 fsp->fh->position_information = fsp->fh->pos;
  70                 return n;
  71         }
  72
  73         flush_write_cache(fsp, READ_FLUSH);
  74
  75         fsp->fh->pos = pos;
  76
  77         if (n > 0) {
  78 #ifdef DMF_FIX
  79                 int numretries = 3;
  80 tryagain:
  81                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  82
  83                 if (readret == -1) {
  84                         if ((errno == EAGAIN) && numretries) {
  85                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
  86                                 (void)sleep(10);
  87                                 --numretries;
  88                                 goto tryagain;
  89                         }
  90                         return -1;
  91                 }
  92 #else /* NO DMF fix. */
  93                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  94
  95                 if (readret == -1) {
  96                         return -1;
  97                 }
  98 #endif
  99                 if (readret > 0) {
 100                         ret += readret;
 101                 }
 102         }
 103
 104         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
 105                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 106
 107         fsp->fh->pos += ret;
 108         fsp->fh->position_information = fsp->fh->pos;
 109
 110         return(ret);
 111 }
 112
 113 /****************************************************************************
 114  *Really* write to a file.
 115 ****************************************************************************/
 116
 117 static ssize_t real_write_file(struct smb_request *req,
 118                                 files_struct *fsp,
 119                                 const char *data,
 120                                 SMB_OFF_T pos,
 121                                 size_t n)
 122 {
 123         ssize_t ret;
 124
 125         if (pos == -1) {
 126                 ret = vfs_write_data(req, fsp, data, n);
 127         } else {
 128                 fsp->fh->pos = pos;
 129                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
 130                         if (vfs_fill_sparse(fsp, pos) == -1) {
 131                                 return -1;
 132                         }
 133                 }
 134                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
 135         }
 136
 137         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 138                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 139
 140         if (ret != -1) {
 141                 fsp->fh->pos += ret;
 142
 143 /* Yes - this is correct - writes don't update this. JRA. */
 144 /* Found by Samba4 tests. */
 145 #if 0
 146                 fsp->position_information = fsp->pos;
 147 #endif
 148         }
 149
 150         return ret;
 151 }
 152
 153 /****************************************************************************
 154  File size cache change.
 155  Updates size on disk but doesn't flush the cache.
 156 ****************************************************************************/
 157
 158 static int wcp_file_size_change(files_struct *fsp)
 159 {
 160         int ret;
 161         write_cache *wcp = fsp->wcp;
 162
 163         wcp->file_size = wcp->offset + wcp->data_size;
 164         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 165         if (ret == -1) {
 166                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
 167                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
 168         }
 169         return ret;
 170 }
 171
 172 static void update_write_time_handler(struct event_context *ctx,
 173                                       struct timed_event *te,
 174                                       struct timeval now,
 175                                       void *private_data)
 176 {
 177         files_struct *fsp = (files_struct *)private_data;
 178
 179         /* Remove the timed event handler. */
 180         TALLOC_FREE(fsp->update_write_time_event);
 181         DEBUG(5, ("Update write time on %s\n", fsp->fsp_name));
 182
 183         /* change the write time if not already changed by someone else */
 184         update_write_time(fsp);
 185 }
 186
 187 /*********************************************************
 188  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
 189  in the future.
 190 *********************************************************/
 191
 192 void trigger_write_time_update(struct files_struct *fsp)
 193 {
 194         int delay;
 195
 196         if (fsp->write_time_forced) {
 197                 /* No point - "sticky" write times
 198                  * in effect.
 199                  */
 200                 return;
 201         }
 202
 203         if (fsp->update_write_time_triggered) {
 204                 /*
 205                  * We only update the write time
 206                  * on the first write. After that
 207                  * no other writes affect this.
 208                  */
 209                 return;
 210         }
 211         fsp->update_write_time_triggered = true;
 212
 213         delay = lp_parm_int(SNUM(fsp->conn),
 214                             "smbd", "writetimeupdatedelay",
 215                             WRITE_TIME_UPDATE_USEC_DELAY);
 216
 217         /* trigger the update 2 seconds later */
 218         fsp->update_write_time_on_close = true;
 219         fsp->update_write_time_event =
 220                 event_add_timed(smbd_event_context(), NULL,
 221                                 timeval_current_ofs(0, delay),
 222                                 update_write_time_handler, fsp);
 223 }
 224
 225 void trigger_write_time_update_immediate(struct files_struct *fsp)
 226 {
 227         if (fsp->write_time_forced) {
 228                 /*
 229                  * No point - "sticky" write times
 230                  * in effect.
 231                  */
 232                 return;
 233         }
 234
 235         TALLOC_FREE(fsp->update_write_time_event);
 236         DEBUG(5, ("Update write time immediate on %s\n", fsp->fsp_name));
 237
 238         fsp->update_write_time_triggered = true;
 239
 240         fsp->update_write_time_on_close = false;
 241         update_write_time(fsp);
 242 }
 243
 244 /****************************************************************************
 245  Write to a file.
 246 ****************************************************************************/
 247
 248 ssize_t write_file(struct smb_request *req,
 249                         files_struct *fsp,
 250                         const char *data,
 251                         SMB_OFF_T pos,
 252                         size_t n)
 253 {
 254         write_cache *wcp = fsp->wcp;
 255         ssize_t total_written = 0;
 256         int write_path = -1;
 257
 258         if (fsp->print_file) {
 259                 fstring sharename;
 260                 uint32 jobid;
 261
 262                 if (!rap_to_pjobid(fsp->rap_print_jobid, sharename, &jobid)) {
 263                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 264                                                 (unsigned int)fsp->rap_print_jobid ));
 265                         errno = EBADF;
 266                         return -1;
 267                 }
 268
 269                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 270         }
 271
 272         if (!fsp->can_write) {
 273                 errno = EPERM;
 274                 return -1;
 275         }
 276
 277         if (!fsp->modified) {
 278                 SMB_STRUCT_STAT st;
 279                 fsp->modified = True;
 280
 281                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
 282                         int dosmode;
 283                         trigger_write_time_update(fsp);
 284                         dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 285                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 286                                         MAP_ARCHIVE(fsp->conn)) &&
 287                                         !IS_DOS_ARCHIVE(dosmode)) {
 288                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
 289                                                 dosmode | aARCH,&st,
 290                                                 NULL,
 291                                                 false);
 292                         }
 293
 294                         /*
 295                          * If this is the first write and we have an exclusive oplock then setup
 296                          * the write cache.
 297                          */
 298
 299                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 300                                 setup_write_cache(fsp, st.st_size);
 301                                 wcp = fsp->wcp;
 302                         }
 303                 }
 304         }
 305
 306 #ifdef WITH_PROFILE
 307         DO_PROFILE_INC(writecache_total_writes);
 308         if (!fsp->oplock_type) {
 309                 DO_PROFILE_INC(writecache_non_oplock_writes);
 310         }
 311 #endif
 312
 313         /*
 314          * If this file is level II oplocked then we need
 315          * to grab the shared memory lock and inform all
 316          * other files with a level II lock that they need
 317          * to flush their read caches. We keep the lock over
 318          * the shared memory area whilst doing this.
 319          */
 320
 321         /* This should actually be improved to span the write. */
 322         contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_WRITE);
 323         contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_WRITE);
 324
 325 #ifdef WITH_PROFILE
 326         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 327                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 328 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 329                         profile_p->writecache_init_writes,
 330                         profile_p->writecache_abutted_writes,
 331                         profile_p->writecache_total_writes,
 332                         profile_p->writecache_non_oplock_writes,
 333                         profile_p->writecache_allocated_write_caches,
 334                         profile_p->writecache_num_write_caches,
 335                         profile_p->writecache_direct_writes,
 336                         profile_p->writecache_num_perfect_writes,
 337                         profile_p->writecache_read_hits ));
 338
 339                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 340                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 341                         profile_p->writecache_flushed_writes[READ_FLUSH],
 342                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 343                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 344                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 345                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 346                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 347         }
 348 #endif
 349
 350         if (wcp && req->unread_bytes) {
 351                 /* If we're using receivefile don't
 352                  * deal with a write cache.
 353                  */
 354                 flush_write_cache(fsp, WRITE_FLUSH);
 355                 delete_write_cache(fsp);
 356                 wcp = NULL;
 357         }
 358
 359         if(!wcp) {
 360                 DO_PROFILE_INC(writecache_direct_writes);
 361                 total_written = real_write_file(req, fsp, data, pos, n);
 362                 return total_written;
 363         }
 364
 365         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 366                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 367
 368         fsp->fh->pos = pos + n;
 369
 370         /*
 371          * If we have active cache and it isn't contiguous then we flush.
 372          * NOTE: There is a small problem with running out of disk ....
 373          */
 374
 375         if (wcp->data_size) {
 376                 bool cache_flush_needed = False;
 377
 378                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 379
 380                         /* ASCII art.... JRA.
 381
 382       +--------------+-----
 383       | Cached data  | Rest of allocated cache buffer....
 384       +--------------+-----
 385
 386             +-------------------+
 387             | Data to write     |
 388             +-------------------+
 389
 390                         */
 391
 392                         /*
 393                          * Start of write overlaps or abutts the existing data.
 394                          */
 395
 396                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 397
 398                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 399
 400                         /*
 401                          * Update the current buffer size with the new data.
 402                          */
 403
 404                         if(pos + data_used > wcp->offset + wcp->data_size) {
 405                                 wcp->data_size = pos + data_used - wcp->offset;
 406                         }
 407
 408                         /*
 409                          * Update the file size if changed.
 410                          */
 411
 412                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 413                                 if (wcp_file_size_change(fsp) == -1) {
 414                                         return -1;
 415                                 }
 416                         }
 417
 418                         /*
 419                          * If we used all the data then
 420                          * return here.
 421                          */
 422
 423                         if(n == data_used) {
 424                                 return n;
 425                         } else {
 426                                 cache_flush_needed = True;
 427                         }
 428                         /*
 429                          * Move the start of data forward by the amount used,
 430                          * cut down the amount left by the same amount.
 431                          */
 432
 433                         data += data_used;
 434                         pos += data_used;
 435                         n -= data_used;
 436
 437                         DO_PROFILE_INC(writecache_abutted_writes);
 438                         total_written = data_used;
 439
 440                         write_path = 1;
 441
 442                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 443                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 444
 445                         /* ASCII art.... JRA.
 446
 447                         +---------------+
 448                         | Cache buffer  |
 449                         +---------------+
 450
 451             +-------------------+
 452             | Data to write     |
 453             +-------------------+
 454
 455                         */
 456
 457                         /*
 458                          * End of write overlaps the existing data.
 459                          */
 460
 461                         size_t data_used = pos + n - wcp->offset;
 462
 463                         memcpy(wcp->data, data + n - data_used, data_used);
 464
 465                         /*
 466                          * Update the current buffer size with the new data.
 467                          */
 468
 469                         if(pos + n > wcp->offset + wcp->data_size) {
 470                                 wcp->data_size = pos + n - wcp->offset;
 471                         }
 472
 473                         /*
 474                          * Update the file size if changed.
 475                          */
 476
 477                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 478                                 if (wcp_file_size_change(fsp) == -1) {
 479                                         return -1;
 480                                 }
 481                         }
 482
 483                         /*
 484                          * We don't need to move the start of data, but we
 485                          * cut down the amount left by the amount used.
 486                          */
 487
 488                         n -= data_used;
 489
 490                         /*
 491                          * We cannot have used all the data here.
 492                          */
 493
 494                         cache_flush_needed = True;
 495
 496                         DO_PROFILE_INC(writecache_abutted_writes);
 497                         total_written = data_used;
 498
 499                         write_path = 2;
 500
 501                 } else if ( (pos >= wcp->file_size) &&
 502                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 503                                         (pos > wcp->offset + wcp->data_size) &&
 504                                         (pos < wcp->offset + wcp->alloc_size) ) {
 505
 506                         /* ASCII art.... JRA.
 507
 508                        End of file ---->|
 509
 510                         +---------------+---------------+
 511                         | Cached data   | Cache buffer  |
 512                         +---------------+---------------+
 513
 514                                               +-------------------+
 515                                               | Data to write     |
 516                                               +-------------------+
 517
 518                         */
 519
 520                         /*
 521                          * Non-contiguous write part of which fits within
 522                          * the cache buffer and is extending the file
 523                          * and the cache contents reflect the current
 524                          * data up to the current end of the file.
 525                          */
 526
 527                         size_t data_used;
 528
 529                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 530                                 data_used = n;
 531                         } else {
 532                                 data_used = wcp->offset + wcp->alloc_size - pos;
 533                         }
 534
 535                         /*
 536                          * Fill in the non-continuous area with zeros.
 537                          */
 538
 539                         memset(wcp->data + wcp->data_size, '\0',
 540                                 pos - (wcp->offset + wcp->data_size) );
 541
 542                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 543
 544                         /*
 545                          * Update the current buffer size with the new data.
 546                          */
 547
 548                         if(pos + data_used > wcp->offset + wcp->data_size) {
 549                                 wcp->data_size = pos + data_used - wcp->offset;
 550                         }
 551
 552                         /*
 553                          * Update the file size if changed.
 554                          */
 555
 556                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 557                                 if (wcp_file_size_change(fsp) == -1) {
 558                                         return -1;
 559                                 }
 560                         }
 561
 562                         /*
 563                          * If we used all the data then
 564                          * return here.
 565                          */
 566
 567                         if(n == data_used) {
 568                                 return n;
 569                         } else {
 570                                 cache_flush_needed = True;
 571                         }
 572
 573                         /*
 574                          * Move the start of data forward by the amount used,
 575                          * cut down the amount left by the same amount.
 576                          */
 577
 578                         data += data_used;
 579                         pos += data_used;
 580                         n -= data_used;
 581
 582                         DO_PROFILE_INC(writecache_abutted_writes);
 583                         total_written = data_used;
 584
 585                         write_path = 3;
 586
 587                 } else if ( (pos >= wcp->file_size) &&
 588                             (n == 1) &&
 589                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 590                             (pos < wcp->file_size + wcp->alloc_size)) {
 591
 592                         /*
 593
 594                 End of file ---->|
 595
 596                  +---------------+---------------+
 597                  | Cached data   | Cache buffer  |
 598                  +---------------+---------------+
 599
 600                                  |<------- allocated size ---------------->|
 601
 602                                                          +--------+
 603                                                          | 1 Byte |
 604                                                          +--------+
 605
 606                         MS-Office seems to do this a lot to determine if there's enough
 607                         space on the filesystem to write a new file.
 608
 609                         Change to :
 610
 611                 End of file ---->|
 612                                  +-----------------------+--------+
 613                                  | Zeroed Cached data    | 1 Byte |
 614                                  +-----------------------+--------+
 615                         */
 616
 617                         flush_write_cache(fsp, WRITE_FLUSH);
 618                         wcp->offset = wcp->file_size;
 619                         wcp->data_size = pos - wcp->file_size + 1;
 620                         memset(wcp->data, '\0', wcp->data_size);
 621                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 622
 623                         /*
 624                          * Update the file size if changed.
 625                          */
 626
 627                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 628                                 if (wcp_file_size_change(fsp) == -1) {
 629                                         return -1;
 630                                 }
 631                         }
 632
 633                         return n;
 634
 635                 } else {
 636
 637                         /* ASCII art..... JRA.
 638
 639    Case 1).
 640
 641                         +---------------+---------------+
 642                         | Cached data   | Cache buffer  |
 643                         +---------------+---------------+
 644
 645                                                               +-------------------+
 646                                                               | Data to write     |
 647                                                               +-------------------+
 648
 649    Case 2).
 650
 651                            +---------------+---------------+
 652                            | Cached data   | Cache buffer  |
 653                            +---------------+---------------+
 654
 655    +-------------------+
 656    | Data to write     |
 657    +-------------------+
 658
 659     Case 3).
 660
 661                            +---------------+---------------+
 662                            | Cached data   | Cache buffer  |
 663                            +---------------+---------------+
 664
 665                   +-----------------------------------------------------+
 666                   | Data to write                                       |
 667                   +-----------------------------------------------------+
 668
 669                   */
 670
 671                         /*
 672                          * Write is bigger than buffer, or there is no overlap on the
 673                          * low or high ends.
 674                          */
 675
 676                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 677 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 678
 679                         /*
 680                          * If write would fit in the cache, and is larger than
 681                          * the data already in the cache, flush the cache and
 682                          * preferentially copy the data new data into it. Otherwise
 683                          * just write the data directly.
 684                          */
 685
 686                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 687                                 cache_flush_needed = True;
 688                         } else {
 689                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 690
 691                                 /*
 692                                  * If the write overlaps the entire cache, then
 693                                  * discard the current contents of the cache.
 694                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 695                                  */
 696
 697                                 if ((pos <= wcp->offset) &&
 698                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 699                                         DEBUG(9,("write_file: discarding overwritten write \
 700 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 701                                         wcp->data_size = 0;
 702                                 }
 703
 704                                 DO_PROFILE_INC(writecache_direct_writes);
 705                                 if (ret == -1) {
 706                                         return ret;
 707                                 }
 708
 709                                 if (pos + ret > wcp->file_size) {
 710                                         wcp->file_size = pos + ret;
 711                                 }
 712
 713                                 return ret;
 714                         }
 715
 716                         write_path = 4;
 717
 718                 }
 719
 720                 if (cache_flush_needed) {
 721                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 722 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 723                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 724                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 725
 726                         flush_write_cache(fsp, WRITE_FLUSH);
 727                 }
 728         }
 729
 730         /*
 731          * If the write request is bigger than the cache
 732          * size, write it all out.
 733          */
 734
 735         if (n > wcp->alloc_size ) {
 736                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 737                 if (ret == -1) {
 738                         return -1;
 739                 }
 740
 741                 if (pos + ret > wcp->file_size) {
 742                         wcp->file_size = pos + n;
 743                 }
 744
 745                 DO_PROFILE_INC(writecache_direct_writes);
 746                 return total_written + n;
 747         }
 748
 749         /*
 750          * If there's any data left, cache it.
 751          */
 752
 753         if (n) {
 754 #ifdef WITH_PROFILE
 755                 if (wcp->data_size) {
 756                         DO_PROFILE_INC(writecache_abutted_writes);
 757                 } else {
 758                         DO_PROFILE_INC(writecache_init_writes);
 759                 }
 760 #endif
 761                 memcpy(wcp->data+wcp->data_size, data, n);
 762                 if (wcp->data_size == 0) {
 763                         wcp->offset = pos;
 764                         DO_PROFILE_INC(writecache_num_write_caches);
 765                 }
 766                 wcp->data_size += n;
 767
 768                 /*
 769                  * Update the file size if changed.
 770                  */
 771
 772                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 773                         if (wcp_file_size_change(fsp) == -1) {
 774                                 return -1;
 775                         }
 776                 }
 777                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 778                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 779
 780                 total_written += n;
 781                 return total_written; /* .... that's a write :) */
 782         }
 783
 784         return total_written;
 785 }
 786
 787 /****************************************************************************
 788  Delete the write cache structure.
 789 ****************************************************************************/
 790
 791 void delete_write_cache(files_struct *fsp)
 792 {
 793         write_cache *wcp;
 794
 795         if(!fsp) {
 796                 return;
 797         }
 798
 799         if(!(wcp = fsp->wcp)) {
 800                 return;
 801         }
 802
 803         DO_PROFILE_DEC(writecache_allocated_write_caches);
 804         allocated_write_caches--;
 805
 806         SMB_ASSERT(wcp->data_size == 0);
 807
 808         SAFE_FREE(wcp->data);
 809         SAFE_FREE(fsp->wcp);
 810
 811         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 812 }
 813
 814 /****************************************************************************
 815  Setup the write cache structure.
 816 ****************************************************************************/
 817
 818 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 819 {
 820         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 821         write_cache *wcp;
 822
 823         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 824                 return False;
 825         }
 826
 827         if(alloc_size == 0 || fsp->wcp) {
 828                 return False;
 829         }
 830
 831         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 832                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 833                 return False;
 834         }
 835
 836         wcp->file_size = file_size;
 837         wcp->offset = 0;
 838         wcp->alloc_size = alloc_size;
 839         wcp->data_size = 0;
 840         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 841                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 842                         (unsigned int)wcp->alloc_size ));
 843                 SAFE_FREE(wcp);
 844                 return False;
 845         }
 846
 847         memset(wcp->data, '\0', wcp->alloc_size );
 848
 849         fsp->wcp = wcp;
 850         DO_PROFILE_INC(writecache_allocated_write_caches);
 851         allocated_write_caches++;
 852
 853         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 854                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
 855
 856         return True;
 857 }
 858
 859 /****************************************************************************
 860  Cope with a size change.
 861 ****************************************************************************/
 862
 863 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 864 {
 865         if(fsp->wcp) {
 866                 /* The cache *must* have been flushed before we do this. */
 867                 if (fsp->wcp->data_size != 0) {
 868                         char *msg;
 869                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 870                                  "on file %s with write cache size = %lu\n",
 871                                  fsp->fsp_name,
 872                                  (unsigned long)fsp->wcp->data_size) != -1) {
 873                                 smb_panic(msg);
 874                         } else {
 875                                 smb_panic("set_filelen_write_cache");
 876                         }
 877                 }
 878                 fsp->wcp->file_size = file_size;
 879         }
 880 }
 881
 882 /*******************************************************************
 883  Flush a write cache struct to disk.
 884 ********************************************************************/
 885
 886 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 887 {
 888         write_cache *wcp = fsp->wcp;
 889         size_t data_size;
 890         ssize_t ret;
 891
 892         if(!wcp || !wcp->data_size) {
 893                 return 0;
 894         }
 895
 896         data_size = wcp->data_size;
 897         wcp->data_size = 0;
 898
 899         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 900
 901         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 902                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 903
 904 #ifdef WITH_PROFILE
 905         if(data_size == wcp->alloc_size) {
 906                 DO_PROFILE_INC(writecache_num_perfect_writes);
 907         }
 908 #endif
 909
 910         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 911
 912         /*
 913          * Ensure file size if kept up to date if write extends file.
 914          */
 915
 916         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 917                 wcp->file_size = wcp->offset + ret;
 918         }
 919
 920         return ret;
 921 }
 922
 923 /*******************************************************************
 924 sync a file
 925 ********************************************************************/
 926
 927 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
 928 {
 929         if (fsp->fh->fd == -1)
 930                 return NT_STATUS_INVALID_HANDLE;
 931
 932         if (lp_strict_sync(SNUM(conn)) &&
 933             (lp_syncalways(SNUM(conn)) || write_through)) {
 934                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 935                 if (ret == -1) {
 936                         return map_nt_error_from_unix(errno);
 937                 }
 938                 ret = SMB_VFS_FSYNC(fsp);
 939                 if (ret == -1) {
 940                         return map_nt_error_from_unix(errno);
 941                 }
 942         }
 943         return NT_STATUS_OK;
 944 }
 945
 946 /************************************************************
 947  Perform a stat whether a valid fd or not.
 948 ************************************************************/
 949
 950 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 951 {
 952         if (fsp->fh->fd == -1) {
 953                 return SMB_VFS_STAT(fsp->conn, fsp->fsp_name, pst);
 954         } else {
 955                 return SMB_VFS_FSTAT(fsp, pst);
 956         }
 957 }