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->posix_open) {
 197                 /* Don't use delayed writes on POSIX files. */
 198                 return;
 199         }
 200
 201         if (fsp->write_time_forced) {
 202                 /* No point - "sticky" write times
 203                  * in effect.
 204                  */
 205                 return;
 206         }
 207
 208         if (fsp->update_write_time_triggered) {
 209                 /*
 210                  * We only update the write time
 211                  * on the first write. After that
 212                  * no other writes affect this.
 213                  */
 214                 return;
 215         }
 216         fsp->update_write_time_triggered = true;
 217
 218         delay = lp_parm_int(SNUM(fsp->conn),
 219                             "smbd", "writetimeupdatedelay",
 220                             WRITE_TIME_UPDATE_USEC_DELAY);
 221
 222         /* trigger the update 2 seconds later */
 223         fsp->update_write_time_on_close = true;
 224         fsp->update_write_time_event =
 225                 event_add_timed(smbd_event_context(), NULL,
 226                                 timeval_current_ofs(0, delay),
 227                                 update_write_time_handler, fsp);
 228 }
 229
 230 void trigger_write_time_update_immediate(struct files_struct *fsp)
 231 {
 232         if (fsp->posix_open) {
 233                 /* Don't use delayed writes on POSIX files. */
 234                 return;
 235         }
 236
 237         if (fsp->write_time_forced) {
 238                 /*
 239                  * No point - "sticky" write times
 240                  * in effect.
 241                  */
 242                 return;
 243         }
 244
 245         TALLOC_FREE(fsp->update_write_time_event);
 246         DEBUG(5, ("Update write time immediate on %s\n", fsp->fsp_name));
 247
 248         fsp->update_write_time_triggered = true;
 249
 250         fsp->update_write_time_on_close = false;
 251         update_write_time(fsp);
 252 }
 253
 254 /****************************************************************************
 255  Write to a file.
 256 ****************************************************************************/
 257
 258 ssize_t write_file(struct smb_request *req,
 259                         files_struct *fsp,
 260                         const char *data,
 261                         SMB_OFF_T pos,
 262                         size_t n)
 263 {
 264         write_cache *wcp = fsp->wcp;
 265         ssize_t total_written = 0;
 266         int write_path = -1;
 267
 268         if (fsp->print_file) {
 269                 uint32 jobid;
 270
 271                 if (!rap_to_pjobid(fsp->rap_print_jobid, NULL, &jobid)) {
 272                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
 273                                                 (unsigned int)fsp->rap_print_jobid ));
 274                         errno = EBADF;
 275                         return -1;
 276                 }
 277
 278                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
 279         }
 280
 281         if (!fsp->can_write) {
 282                 errno = EPERM;
 283                 return -1;
 284         }
 285
 286         if (!fsp->modified) {
 287                 SMB_STRUCT_STAT st;
 288                 fsp->modified = True;
 289
 290                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
 291                         int dosmode;
 292                         trigger_write_time_update(fsp);
 293                         dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 294                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 295                                         MAP_ARCHIVE(fsp->conn)) &&
 296                                         !IS_DOS_ARCHIVE(dosmode)) {
 297                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
 298                                                 dosmode | aARCH,&st,
 299                                                 NULL,
 300                                                 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, st.st_ex_size);
 310                                 wcp = fsp->wcp;
 311                         }
 312                 }
 313         }
 314
 315 #ifdef WITH_PROFILE
 316         DO_PROFILE_INC(writecache_total_writes);
 317         if (!fsp->oplock_type) {
 318                 DO_PROFILE_INC(writecache_non_oplock_writes);
 319         }
 320 #endif
 321
 322         /*
 323          * If this file is level II oplocked then we need
 324          * to grab the shared memory lock and inform all
 325          * other files with a level II lock that they need
 326          * to flush their read caches. We keep the lock over
 327          * the shared memory area whilst doing this.
 328          */
 329
 330         /* This should actually be improved to span the write. */
 331         contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_WRITE);
 332         contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_WRITE);
 333
 334 #ifdef WITH_PROFILE
 335         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 336                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 337 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 338                         profile_p->writecache_init_writes,
 339                         profile_p->writecache_abutted_writes,
 340                         profile_p->writecache_total_writes,
 341                         profile_p->writecache_non_oplock_writes,
 342                         profile_p->writecache_allocated_write_caches,
 343                         profile_p->writecache_num_write_caches,
 344                         profile_p->writecache_direct_writes,
 345                         profile_p->writecache_num_perfect_writes,
 346                         profile_p->writecache_read_hits ));
 347
 348                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 349                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 350                         profile_p->writecache_flushed_writes[READ_FLUSH],
 351                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 352                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 353                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 354                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 355                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 356         }
 357 #endif
 358
 359         if (wcp && req->unread_bytes) {
 360                 /* If we're using receivefile don't
 361                  * deal with a write cache.
 362                  */
 363                 flush_write_cache(fsp, WRITE_FLUSH);
 364                 delete_write_cache(fsp);
 365                 wcp = NULL;
 366         }
 367
 368         if(!wcp) {
 369                 DO_PROFILE_INC(writecache_direct_writes);
 370                 total_written = real_write_file(req, fsp, data, pos, n);
 371                 return total_written;
 372         }
 373
 374         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 375                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 376
 377         fsp->fh->pos = pos + n;
 378
 379         /*
 380          * If we have active cache and it isn't contiguous then we flush.
 381          * NOTE: There is a small problem with running out of disk ....
 382          */
 383
 384         if (wcp->data_size) {
 385                 bool cache_flush_needed = False;
 386
 387                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 388
 389                         /* ASCII art.... JRA.
 390
 391       +--------------+-----
 392       | Cached data  | Rest of allocated cache buffer....
 393       +--------------+-----
 394
 395             +-------------------+
 396             | Data to write     |
 397             +-------------------+
 398
 399                         */
 400
 401                         /*
 402                          * Start of write overlaps or abutts the existing data.
 403                          */
 404
 405                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 406
 407                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 408
 409                         /*
 410                          * Update the current buffer size with the new data.
 411                          */
 412
 413                         if(pos + data_used > wcp->offset + wcp->data_size) {
 414                                 wcp->data_size = pos + data_used - wcp->offset;
 415                         }
 416
 417                         /*
 418                          * Update the file size if changed.
 419                          */
 420
 421                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 422                                 if (wcp_file_size_change(fsp) == -1) {
 423                                         return -1;
 424                                 }
 425                         }
 426
 427                         /*
 428                          * If we used all the data then
 429                          * return here.
 430                          */
 431
 432                         if(n == data_used) {
 433                                 return n;
 434                         } else {
 435                                 cache_flush_needed = True;
 436                         }
 437                         /*
 438                          * Move the start of data forward by the amount used,
 439                          * cut down the amount left by the same amount.
 440                          */
 441
 442                         data += data_used;
 443                         pos += data_used;
 444                         n -= data_used;
 445
 446                         DO_PROFILE_INC(writecache_abutted_writes);
 447                         total_written = data_used;
 448
 449                         write_path = 1;
 450
 451                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 452                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 453
 454                         /* ASCII art.... JRA.
 455
 456                         +---------------+
 457                         | Cache buffer  |
 458                         +---------------+
 459
 460             +-------------------+
 461             | Data to write     |
 462             +-------------------+
 463
 464                         */
 465
 466                         /*
 467                          * End of write overlaps the existing data.
 468                          */
 469
 470                         size_t data_used = pos + n - wcp->offset;
 471
 472                         memcpy(wcp->data, data + n - data_used, data_used);
 473
 474                         /*
 475                          * Update the current buffer size with the new data.
 476                          */
 477
 478                         if(pos + n > wcp->offset + wcp->data_size) {
 479                                 wcp->data_size = pos + n - wcp->offset;
 480                         }
 481
 482                         /*
 483                          * Update the file size if changed.
 484                          */
 485
 486                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 487                                 if (wcp_file_size_change(fsp) == -1) {
 488                                         return -1;
 489                                 }
 490                         }
 491
 492                         /*
 493                          * We don't need to move the start of data, but we
 494                          * cut down the amount left by the amount used.
 495                          */
 496
 497                         n -= data_used;
 498
 499                         /*
 500                          * We cannot have used all the data here.
 501                          */
 502
 503                         cache_flush_needed = True;
 504
 505                         DO_PROFILE_INC(writecache_abutted_writes);
 506                         total_written = data_used;
 507
 508                         write_path = 2;
 509
 510                 } else if ( (pos >= wcp->file_size) &&
 511                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 512                                         (pos > wcp->offset + wcp->data_size) &&
 513                                         (pos < wcp->offset + wcp->alloc_size) ) {
 514
 515                         /* ASCII art.... JRA.
 516
 517                        End of file ---->|
 518
 519                         +---------------+---------------+
 520                         | Cached data   | Cache buffer  |
 521                         +---------------+---------------+
 522
 523                                               +-------------------+
 524                                               | Data to write     |
 525                                               +-------------------+
 526
 527                         */
 528
 529                         /*
 530                          * Non-contiguous write part of which fits within
 531                          * the cache buffer and is extending the file
 532                          * and the cache contents reflect the current
 533                          * data up to the current end of the file.
 534                          */
 535
 536                         size_t data_used;
 537
 538                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 539                                 data_used = n;
 540                         } else {
 541                                 data_used = wcp->offset + wcp->alloc_size - pos;
 542                         }
 543
 544                         /*
 545                          * Fill in the non-continuous area with zeros.
 546                          */
 547
 548                         memset(wcp->data + wcp->data_size, '\0',
 549                                 pos - (wcp->offset + wcp->data_size) );
 550
 551                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 552
 553                         /*
 554                          * Update the current buffer size with the new data.
 555                          */
 556
 557                         if(pos + data_used > wcp->offset + wcp->data_size) {
 558                                 wcp->data_size = pos + data_used - wcp->offset;
 559                         }
 560
 561                         /*
 562                          * Update the file size if changed.
 563                          */
 564
 565                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 566                                 if (wcp_file_size_change(fsp) == -1) {
 567                                         return -1;
 568                                 }
 569                         }
 570
 571                         /*
 572                          * If we used all the data then
 573                          * return here.
 574                          */
 575
 576                         if(n == data_used) {
 577                                 return n;
 578                         } else {
 579                                 cache_flush_needed = True;
 580                         }
 581
 582                         /*
 583                          * Move the start of data forward by the amount used,
 584                          * cut down the amount left by the same amount.
 585                          */
 586
 587                         data += data_used;
 588                         pos += data_used;
 589                         n -= data_used;
 590
 591                         DO_PROFILE_INC(writecache_abutted_writes);
 592                         total_written = data_used;
 593
 594                         write_path = 3;
 595
 596                 } else if ( (pos >= wcp->file_size) &&
 597                             (n == 1) &&
 598                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 599                             (pos < wcp->file_size + wcp->alloc_size)) {
 600
 601                         /*
 602
 603                 End of file ---->|
 604
 605                  +---------------+---------------+
 606                  | Cached data   | Cache buffer  |
 607                  +---------------+---------------+
 608
 609                                  |<------- allocated size ---------------->|
 610
 611                                                          +--------+
 612                                                          | 1 Byte |
 613                                                          +--------+
 614
 615                         MS-Office seems to do this a lot to determine if there's enough
 616                         space on the filesystem to write a new file.
 617
 618                         Change to :
 619
 620                 End of file ---->|
 621                                  +-----------------------+--------+
 622                                  | Zeroed Cached data    | 1 Byte |
 623                                  +-----------------------+--------+
 624                         */
 625
 626                         flush_write_cache(fsp, WRITE_FLUSH);
 627                         wcp->offset = wcp->file_size;
 628                         wcp->data_size = pos - wcp->file_size + 1;
 629                         memset(wcp->data, '\0', wcp->data_size);
 630                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 631
 632                         /*
 633                          * Update the file size if changed.
 634                          */
 635
 636                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 637                                 if (wcp_file_size_change(fsp) == -1) {
 638                                         return -1;
 639                                 }
 640                         }
 641
 642                         return n;
 643
 644                 } else {
 645
 646                         /* ASCII art..... JRA.
 647
 648    Case 1).
 649
 650                         +---------------+---------------+
 651                         | Cached data   | Cache buffer  |
 652                         +---------------+---------------+
 653
 654                                                               +-------------------+
 655                                                               | Data to write     |
 656                                                               +-------------------+
 657
 658    Case 2).
 659
 660                            +---------------+---------------+
 661                            | Cached data   | Cache buffer  |
 662                            +---------------+---------------+
 663
 664    +-------------------+
 665    | Data to write     |
 666    +-------------------+
 667
 668     Case 3).
 669
 670                            +---------------+---------------+
 671                            | Cached data   | Cache buffer  |
 672                            +---------------+---------------+
 673
 674                   +-----------------------------------------------------+
 675                   | Data to write                                       |
 676                   +-----------------------------------------------------+
 677
 678                   */
 679
 680                         /*
 681                          * Write is bigger than buffer, or there is no overlap on the
 682                          * low or high ends.
 683                          */
 684
 685                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 686 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 687
 688                         /*
 689                          * If write would fit in the cache, and is larger than
 690                          * the data already in the cache, flush the cache and
 691                          * preferentially copy the data new data into it. Otherwise
 692                          * just write the data directly.
 693                          */
 694
 695                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 696                                 cache_flush_needed = True;
 697                         } else {
 698                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 699
 700                                 /*
 701                                  * If the write overlaps the entire cache, then
 702                                  * discard the current contents of the cache.
 703                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 704                                  */
 705
 706                                 if ((pos <= wcp->offset) &&
 707                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 708                                         DEBUG(9,("write_file: discarding overwritten write \
 709 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 710                                         wcp->data_size = 0;
 711                                 }
 712
 713                                 DO_PROFILE_INC(writecache_direct_writes);
 714                                 if (ret == -1) {
 715                                         return ret;
 716                                 }
 717
 718                                 if (pos + ret > wcp->file_size) {
 719                                         wcp->file_size = pos + ret;
 720                                 }
 721
 722                                 return ret;
 723                         }
 724
 725                         write_path = 4;
 726
 727                 }
 728
 729                 if (cache_flush_needed) {
 730                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 731 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 732                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 733                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 734
 735                         flush_write_cache(fsp, WRITE_FLUSH);
 736                 }
 737         }
 738
 739         /*
 740          * If the write request is bigger than the cache
 741          * size, write it all out.
 742          */
 743
 744         if (n > wcp->alloc_size ) {
 745                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 746                 if (ret == -1) {
 747                         return -1;
 748                 }
 749
 750                 if (pos + ret > wcp->file_size) {
 751                         wcp->file_size = pos + n;
 752                 }
 753
 754                 DO_PROFILE_INC(writecache_direct_writes);
 755                 return total_written + n;
 756         }
 757
 758         /*
 759          * If there's any data left, cache it.
 760          */
 761
 762         if (n) {
 763 #ifdef WITH_PROFILE
 764                 if (wcp->data_size) {
 765                         DO_PROFILE_INC(writecache_abutted_writes);
 766                 } else {
 767                         DO_PROFILE_INC(writecache_init_writes);
 768                 }
 769 #endif
 770                 memcpy(wcp->data+wcp->data_size, data, n);
 771                 if (wcp->data_size == 0) {
 772                         wcp->offset = pos;
 773                         DO_PROFILE_INC(writecache_num_write_caches);
 774                 }
 775                 wcp->data_size += n;
 776
 777                 /*
 778                  * Update the file size if changed.
 779                  */
 780
 781                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 782                         if (wcp_file_size_change(fsp) == -1) {
 783                                 return -1;
 784                         }
 785                 }
 786                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 787                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 788
 789                 total_written += n;
 790                 return total_written; /* .... that's a write :) */
 791         }
 792
 793         return total_written;
 794 }
 795
 796 /****************************************************************************
 797  Delete the write cache structure.
 798 ****************************************************************************/
 799
 800 void delete_write_cache(files_struct *fsp)
 801 {
 802         write_cache *wcp;
 803
 804         if(!fsp) {
 805                 return;
 806         }
 807
 808         if(!(wcp = fsp->wcp)) {
 809                 return;
 810         }
 811
 812         DO_PROFILE_DEC(writecache_allocated_write_caches);
 813         allocated_write_caches--;
 814
 815         SMB_ASSERT(wcp->data_size == 0);
 816
 817         SAFE_FREE(wcp->data);
 818         SAFE_FREE(fsp->wcp);
 819
 820         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 821 }
 822
 823 /****************************************************************************
 824  Setup the write cache structure.
 825 ****************************************************************************/
 826
 827 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 828 {
 829         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 830         write_cache *wcp;
 831
 832         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 833                 return False;
 834         }
 835
 836         if(alloc_size == 0 || fsp->wcp) {
 837                 return False;
 838         }
 839
 840         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 841                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 842                 return False;
 843         }
 844
 845         wcp->file_size = file_size;
 846         wcp->offset = 0;
 847         wcp->alloc_size = alloc_size;
 848         wcp->data_size = 0;
 849         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 850                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 851                         (unsigned int)wcp->alloc_size ));
 852                 SAFE_FREE(wcp);
 853                 return False;
 854         }
 855
 856         memset(wcp->data, '\0', wcp->alloc_size );
 857
 858         fsp->wcp = wcp;
 859         DO_PROFILE_INC(writecache_allocated_write_caches);
 860         allocated_write_caches++;
 861
 862         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 863                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
 864
 865         return True;
 866 }
 867
 868 /****************************************************************************
 869  Cope with a size change.
 870 ****************************************************************************/
 871
 872 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 873 {
 874         if(fsp->wcp) {
 875                 /* The cache *must* have been flushed before we do this. */
 876                 if (fsp->wcp->data_size != 0) {
 877                         char *msg;
 878                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 879                                  "on file %s with write cache size = %lu\n",
 880                                  fsp->fsp_name,
 881                                  (unsigned long)fsp->wcp->data_size) != -1) {
 882                                 smb_panic(msg);
 883                         } else {
 884                                 smb_panic("set_filelen_write_cache");
 885                         }
 886                 }
 887                 fsp->wcp->file_size = file_size;
 888         }
 889 }
 890
 891 /*******************************************************************
 892  Flush a write cache struct to disk.
 893 ********************************************************************/
 894
 895 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 896 {
 897         write_cache *wcp = fsp->wcp;
 898         size_t data_size;
 899         ssize_t ret;
 900
 901         if(!wcp || !wcp->data_size) {
 902                 return 0;
 903         }
 904
 905         data_size = wcp->data_size;
 906         wcp->data_size = 0;
 907
 908         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 909
 910         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 911                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 912
 913 #ifdef WITH_PROFILE
 914         if(data_size == wcp->alloc_size) {
 915                 DO_PROFILE_INC(writecache_num_perfect_writes);
 916         }
 917 #endif
 918
 919         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 920
 921         /*
 922          * Ensure file size if kept up to date if write extends file.
 923          */
 924
 925         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
 926                 wcp->file_size = wcp->offset + ret;
 927         }
 928
 929         return ret;
 930 }
 931
 932 /*******************************************************************
 933 sync a file
 934 ********************************************************************/
 935
 936 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
 937 {
 938         if (fsp->fh->fd == -1)
 939                 return NT_STATUS_INVALID_HANDLE;
 940
 941         if (lp_strict_sync(SNUM(conn)) &&
 942             (lp_syncalways(SNUM(conn)) || write_through)) {
 943                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
 944                 if (ret == -1) {
 945                         return map_nt_error_from_unix(errno);
 946                 }
 947                 ret = SMB_VFS_FSYNC(fsp);
 948                 if (ret == -1) {
 949                         return map_nt_error_from_unix(errno);
 950                 }
 951         }
 952         return NT_STATUS_OK;
 953 }
 954
 955 /************************************************************
 956  Perform a stat whether a valid fd or not.
 957 ************************************************************/
 958
 959 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 960 {
 961         if (fsp->fh->fd == -1) {
 962                 return vfs_stat_smb_fname(fsp->conn, fsp->fsp_name, pst);
 963         } else {
 964                 return SMB_VFS_FSTAT(fsp, pst);
 965         }
 966 }