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 "printing.h"
  24 #include "smbd/smbd.h"
  25 #include "smbd/globals.h"
  26 #include "smbprofile.h"
  27
  28 struct write_cache {
  29         off_t file_size;
  30         off_t offset;
  31         size_t alloc_size;
  32         size_t data_size;
  33         char *data;
  34 };
  35
  36 static bool setup_write_cache(files_struct *, off_t);
  37
  38 /****************************************************************************
  39  Read from write cache if we can.
  40 ****************************************************************************/
  41
  42 static bool read_from_write_cache(files_struct *fsp,char *data,off_t pos,size_t n)
  43 {
  44         struct write_cache *wcp = fsp->wcp;
  45
  46         if(!wcp) {
  47                 return False;
  48         }
  49
  50         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
  51                 return False;
  52         }
  53
  54         memcpy(data, wcp->data + (pos - wcp->offset), n);
  55
  56         DO_PROFILE_INC(writecache_read_hits);
  57
  58         return True;
  59 }
  60
  61 /****************************************************************************
  62  Read from a file.
  63 ****************************************************************************/
  64
  65 ssize_t read_file(files_struct *fsp,char *data,off_t pos,size_t n)
  66 {
  67         ssize_t ret = 0;
  68
  69         /* you can't read from print files */
  70         if (fsp->print_file) {
  71                 errno = EBADF;
  72                 return -1;
  73         }
  74
  75         /*
  76          * Serve from write cache if we can.
  77          */
  78
  79         if(read_from_write_cache(fsp, data, pos, n)) {
  80                 fsp->fh->pos = pos + n;
  81                 fsp->fh->position_information = fsp->fh->pos;
  82                 return n;
  83         }
  84
  85         flush_write_cache(fsp, READ_FLUSH);
  86
  87         fsp->fh->pos = pos;
  88
  89         if (n > 0) {
  90                 ret = SMB_VFS_PREAD(fsp,data,n,pos);
  91
  92                 if (ret == -1) {
  93                         return -1;
  94                 }
  95         }
  96
  97         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
  98                   fsp_str_dbg(fsp), (double)pos, (unsigned long)n, (long)ret));
  99
 100         fsp->fh->pos += ret;
 101         fsp->fh->position_information = fsp->fh->pos;
 102
 103         return(ret);
 104 }
 105
 106 /****************************************************************************
 107  *Really* write to a file.
 108 ****************************************************************************/
 109
 110 static ssize_t real_write_file(struct smb_request *req,
 111                                 files_struct *fsp,
 112                                 const char *data,
 113                                 off_t pos,
 114                                 size_t n)
 115 {
 116         ssize_t ret;
 117
 118         if (pos == -1) {
 119                 ret = vfs_write_data(req, fsp, data, n);
 120         } else {
 121                 fsp->fh->pos = pos;
 122                 if (pos && lp_strict_allocate(SNUM(fsp->conn) &&
 123                                 !fsp->is_sparse)) {
 124                         if (vfs_fill_sparse(fsp, pos) == -1) {
 125                                 return -1;
 126                         }
 127                 }
 128                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
 129         }
 130
 131         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 132                   fsp_str_dbg(fsp), (double)pos, (unsigned long)n, (long)ret));
 133
 134         if (ret != -1) {
 135                 fsp->fh->pos += ret;
 136
 137 /* Yes - this is correct - writes don't update this. JRA. */
 138 /* Found by Samba4 tests. */
 139 #if 0
 140                 fsp->position_information = fsp->pos;
 141 #endif
 142         }
 143
 144         return ret;
 145 }
 146
 147 /****************************************************************************
 148  File size cache change.
 149  Updates size on disk but doesn't flush the cache.
 150 ****************************************************************************/
 151
 152 static int wcp_file_size_change(files_struct *fsp)
 153 {
 154         int ret;
 155         struct write_cache *wcp = fsp->wcp;
 156
 157         wcp->file_size = wcp->offset + wcp->data_size;
 158         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 159         if (ret == -1) {
 160                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f "
 161                          "error %s\n", fsp_str_dbg(fsp),
 162                          (double)wcp->file_size, strerror(errno)));
 163         }
 164         return ret;
 165 }
 166
 167 void update_write_time_handler(struct tevent_context *ctx,
 168                                       struct tevent_timer *te,
 169                                       struct timeval now,
 170                                       void *private_data)
 171 {
 172         files_struct *fsp = (files_struct *)private_data;
 173
 174         DEBUG(5, ("Update write time on %s\n", fsp_str_dbg(fsp)));
 175
 176         /* change the write time in the open file db. */
 177         (void)set_write_time(fsp->file_id, timespec_current());
 178
 179         /* And notify. */
 180         notify_fname(fsp->conn, NOTIFY_ACTION_MODIFIED,
 181                      FILE_NOTIFY_CHANGE_LAST_WRITE, fsp->fsp_name->base_name);
 182
 183         /* Remove the timed event handler. */
 184         TALLOC_FREE(fsp->update_write_time_event);
 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         /* We need to remember someone did a write
 209          * and update to current time on close. */
 210
 211         fsp->update_write_time_on_close = true;
 212
 213         if (fsp->update_write_time_triggered) {
 214                 /*
 215                  * We only update the write time after 2 seconds
 216                  * on the first normal write. After that
 217                  * no other writes affect this until close.
 218                  */
 219                 return;
 220         }
 221         fsp->update_write_time_triggered = true;
 222
 223         delay = lp_parm_int(SNUM(fsp->conn),
 224                             "smbd", "writetimeupdatedelay",
 225                             WRITE_TIME_UPDATE_USEC_DELAY);
 226
 227         DEBUG(5, ("Update write time %d usec later on %s\n",
 228                   delay, fsp_str_dbg(fsp)));
 229
 230         /* trigger the update 2 seconds later */
 231         fsp->update_write_time_event =
 232                 tevent_add_timer(fsp->conn->sconn->ev_ctx, NULL,
 233                                  timeval_current_ofs_usec(delay),
 234                                  update_write_time_handler, fsp);
 235 }
 236
 237 void trigger_write_time_update_immediate(struct files_struct *fsp)
 238 {
 239         struct smb_file_time ft;
 240
 241         if (fsp->posix_open) {
 242                 /* Don't use delayed writes on POSIX files. */
 243                 return;
 244         }
 245
 246         if (fsp->write_time_forced) {
 247                 /*
 248                  * No point - "sticky" write times
 249                  * in effect.
 250                  */
 251                 return;
 252         }
 253
 254         TALLOC_FREE(fsp->update_write_time_event);
 255         DEBUG(5, ("Update write time immediate on %s\n",
 256                   fsp_str_dbg(fsp)));
 257
 258         /* After an immediate update, reset the trigger. */
 259         fsp->update_write_time_triggered = true;
 260         fsp->update_write_time_on_close = false;
 261
 262         ZERO_STRUCT(ft);
 263         ft.mtime = timespec_current();
 264
 265         /* Update the time in the open file db. */
 266         (void)set_write_time(fsp->file_id, ft.mtime);
 267
 268         /* Now set on disk - takes care of notify. */
 269         (void)smb_set_file_time(fsp->conn, fsp, fsp->fsp_name, &ft, false);
 270 }
 271
 272 void mark_file_modified(files_struct *fsp)
 273 {
 274         int dosmode;
 275
 276         if (fsp->modified) {
 277                 return;
 278         }
 279
 280         fsp->modified = true;
 281
 282         if (SMB_VFS_FSTAT(fsp, &fsp->fsp_name->st) != 0) {
 283                 return;
 284         }
 285         trigger_write_time_update(fsp);
 286
 287         if (fsp->posix_open) {
 288                 return;
 289         }
 290         if (!(lp_store_dos_attributes(SNUM(fsp->conn)) ||
 291               MAP_ARCHIVE(fsp->conn))) {
 292                 return;
 293         }
 294
 295         dosmode = dos_mode(fsp->conn, fsp->fsp_name);
 296         if (IS_DOS_ARCHIVE(dosmode)) {
 297                 return;
 298         }
 299         file_set_dosmode(fsp->conn, fsp->fsp_name,
 300                          dosmode | FILE_ATTRIBUTE_ARCHIVE, NULL, false);
 301 }
 302
 303 /****************************************************************************
 304  Write to a file.
 305 ****************************************************************************/
 306
 307 ssize_t write_file(struct smb_request *req,
 308                         files_struct *fsp,
 309                         const char *data,
 310                         off_t pos,
 311                         size_t n)
 312 {
 313         struct write_cache *wcp = fsp->wcp;
 314         ssize_t total_written = 0;
 315         int write_path = -1;
 316
 317         if (fsp->print_file) {
 318                 uint32_t t;
 319                 int ret;
 320
 321                 ret = print_spool_write(fsp, data, n, pos, &t);
 322                 if (ret) {
 323                         errno = ret;
 324                         return -1;
 325                 }
 326                 return t;
 327         }
 328
 329         if (!fsp->can_write) {
 330                 errno = EPERM;
 331                 return -1;
 332         }
 333
 334         /*
 335          * If this is the first write and we have an exclusive oplock
 336          * then setup the write cache.
 337          */
 338
 339         if (!fsp->modified &&
 340             EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) &&
 341             (wcp == NULL)) {
 342                 setup_write_cache(fsp, fsp->fsp_name->st.st_ex_size);
 343                 wcp = fsp->wcp;
 344         }
 345
 346         mark_file_modified(fsp);
 347
 348 #ifdef WITH_PROFILE
 349         DO_PROFILE_INC(writecache_total_writes);
 350         if (!fsp->oplock_type) {
 351                 DO_PROFILE_INC(writecache_non_oplock_writes);
 352         }
 353 #endif
 354
 355         /*
 356          * If this file is level II oplocked then we need
 357          * to grab the shared memory lock and inform all
 358          * other files with a level II lock that they need
 359          * to flush their read caches. We keep the lock over
 360          * the shared memory area whilst doing this.
 361          */
 362
 363         /* This should actually be improved to span the write. */
 364         contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_WRITE);
 365         contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_WRITE);
 366
 367 #ifdef WITH_PROFILE
 368         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 369                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 370 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 371                         profile_p->writecache_init_writes,
 372                         profile_p->writecache_abutted_writes,
 373                         profile_p->writecache_total_writes,
 374                         profile_p->writecache_non_oplock_writes,
 375                         profile_p->writecache_allocated_write_caches,
 376                         profile_p->writecache_num_write_caches,
 377                         profile_p->writecache_direct_writes,
 378                         profile_p->writecache_num_perfect_writes,
 379                         profile_p->writecache_read_hits ));
 380
 381                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 382                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 383                         profile_p->writecache_flushed_writes[READ_FLUSH],
 384                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 385                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 386                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 387                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 388                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 389         }
 390 #endif
 391
 392         if (wcp && req->unread_bytes) {
 393                 /* If we're using receivefile don't
 394                  * deal with a write cache.
 395                  */
 396                 flush_write_cache(fsp, WRITE_FLUSH);
 397                 delete_write_cache(fsp);
 398                 wcp = NULL;
 399         }
 400
 401         if(!wcp) {
 402                 DO_PROFILE_INC(writecache_direct_writes);
 403                 total_written = real_write_file(req, fsp, data, pos, n);
 404                 return total_written;
 405         }
 406
 407         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f "
 408                  "wcp->data_size=%u\n", fsp_str_dbg(fsp), fsp->fh->fd,
 409                  (double)pos, (unsigned int)n, (double)wcp->offset,
 410                  (unsigned int)wcp->data_size));
 411
 412         fsp->fh->pos = pos + n;
 413
 414         if ((n == 1) && (data[0] == '\0') && (pos > wcp->file_size)) {
 415                 int ret;
 416
 417                 /*
 418                  * This is a 1-byte write of a 0 beyond the EOF and
 419                  * thus implicitly also beyond the current active
 420                  * write cache, the typical file-extending (and
 421                  * allocating, but we're using the write cache here)
 422                  * write done by Windows. We just have to ftruncate
 423                  * the file and rely on posix semantics to return
 424                  * zeros for non-written file data that is within the
 425                  * file length.
 426                  *
 427                  * We can not use wcp_file_size_change here because we
 428                  * might have an existing write cache, and
 429                  * wcp_file_size_change assumes a change to just the
 430                  * end of the current write cache.
 431                  */
 432
 433                 wcp->file_size = pos + 1;
 434                 ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 435                 if (ret == -1) {
 436                         DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f"
 437                                  "error %s\n", fsp_str_dbg(fsp),
 438                                  (double)wcp->file_size, strerror(errno)));
 439                         return -1;
 440                 }
 441                 return 1;
 442         }
 443
 444
 445         /*
 446          * If we have active cache and it isn't contiguous then we flush.
 447          * NOTE: There is a small problem with running out of disk ....
 448          */
 449
 450         if (wcp->data_size) {
 451                 bool cache_flush_needed = False;
 452
 453                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 454
 455                         /* ASCII art.... JRA.
 456
 457       +--------------+-----
 458       | Cached data  | Rest of allocated cache buffer....
 459       +--------------+-----
 460
 461             +-------------------+
 462             | Data to write     |
 463             +-------------------+
 464
 465                         */
 466
 467                         /*
 468                          * Start of write overlaps or abutts the existing data.
 469                          */
 470
 471                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 472
 473                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 474
 475                         /*
 476                          * Update the current buffer size with the new data.
 477                          */
 478
 479                         if(pos + data_used > wcp->offset + wcp->data_size) {
 480                                 wcp->data_size = pos + data_used - wcp->offset;
 481                         }
 482
 483                         /*
 484                          * Update the file size if changed.
 485                          */
 486
 487                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 488                                 if (wcp_file_size_change(fsp) == -1) {
 489                                         return -1;
 490                                 }
 491                         }
 492
 493                         /*
 494                          * If we used all the data then
 495                          * return here.
 496                          */
 497
 498                         if(n == data_used) {
 499                                 return n;
 500                         } else {
 501                                 cache_flush_needed = True;
 502                         }
 503                         /*
 504                          * Move the start of data forward by the amount used,
 505                          * cut down the amount left by the same amount.
 506                          */
 507
 508                         data += data_used;
 509                         pos += data_used;
 510                         n -= data_used;
 511
 512                         DO_PROFILE_INC(writecache_abutted_writes);
 513                         total_written = data_used;
 514
 515                         write_path = 1;
 516
 517                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 518                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 519
 520                         /* ASCII art.... JRA.
 521
 522                         +---------------+
 523                         | Cache buffer  |
 524                         +---------------+
 525
 526             +-------------------+
 527             | Data to write     |
 528             +-------------------+
 529
 530                         */
 531
 532                         /*
 533                          * End of write overlaps the existing data.
 534                          */
 535
 536                         size_t data_used = pos + n - wcp->offset;
 537
 538                         memcpy(wcp->data, data + n - data_used, data_used);
 539
 540                         /*
 541                          * Update the current buffer size with the new data.
 542                          */
 543
 544                         if(pos + n > wcp->offset + wcp->data_size) {
 545                                 wcp->data_size = pos + n - wcp->offset;
 546                         }
 547
 548                         /*
 549                          * Update the file size if changed.
 550                          */
 551
 552                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 553                                 if (wcp_file_size_change(fsp) == -1) {
 554                                         return -1;
 555                                 }
 556                         }
 557
 558                         /*
 559                          * We don't need to move the start of data, but we
 560                          * cut down the amount left by the amount used.
 561                          */
 562
 563                         n -= data_used;
 564
 565                         /*
 566                          * We cannot have used all the data here.
 567                          */
 568
 569                         cache_flush_needed = True;
 570
 571                         DO_PROFILE_INC(writecache_abutted_writes);
 572                         total_written = data_used;
 573
 574                         write_path = 2;
 575
 576                 } else if ( (pos >= wcp->file_size) &&
 577                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 578                                         (pos > wcp->offset + wcp->data_size) &&
 579                                         (pos < wcp->offset + wcp->alloc_size) ) {
 580
 581                         /* ASCII art.... JRA.
 582
 583                        End of file ---->|
 584
 585                         +---------------+---------------+
 586                         | Cached data   | Cache buffer  |
 587                         +---------------+---------------+
 588
 589                                               +-------------------+
 590                                               | Data to write     |
 591                                               +-------------------+
 592
 593                         */
 594
 595                         /*
 596                          * Non-contiguous write part of which fits within
 597                          * the cache buffer and is extending the file
 598                          * and the cache contents reflect the current
 599                          * data up to the current end of the file.
 600                          */
 601
 602                         size_t data_used;
 603
 604                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 605                                 data_used = n;
 606                         } else {
 607                                 data_used = wcp->offset + wcp->alloc_size - pos;
 608                         }
 609
 610                         /*
 611                          * Fill in the non-continuous area with zeros.
 612                          */
 613
 614                         memset(wcp->data + wcp->data_size, '\0',
 615                                 pos - (wcp->offset + wcp->data_size) );
 616
 617                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 618
 619                         /*
 620                          * Update the current buffer size with the new data.
 621                          */
 622
 623                         if(pos + data_used > wcp->offset + wcp->data_size) {
 624                                 wcp->data_size = pos + data_used - wcp->offset;
 625                         }
 626
 627                         /*
 628                          * Update the file size if changed.
 629                          */
 630
 631                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 632                                 if (wcp_file_size_change(fsp) == -1) {
 633                                         return -1;
 634                                 }
 635                         }
 636
 637                         /*
 638                          * If we used all the data then
 639                          * return here.
 640                          */
 641
 642                         if(n == data_used) {
 643                                 return n;
 644                         } else {
 645                                 cache_flush_needed = True;
 646                         }
 647
 648                         /*
 649                          * Move the start of data forward by the amount used,
 650                          * cut down the amount left by the same amount.
 651                          */
 652
 653                         data += data_used;
 654                         pos += data_used;
 655                         n -= data_used;
 656
 657                         DO_PROFILE_INC(writecache_abutted_writes);
 658                         total_written = data_used;
 659
 660                         write_path = 3;
 661
 662                 } else if ( (pos >= wcp->file_size) &&
 663                             (n == 1) &&
 664                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 665                             (pos < wcp->file_size + wcp->alloc_size)) {
 666
 667                         /*
 668
 669                 End of file ---->|
 670
 671                  +---------------+---------------+
 672                  | Cached data   | Cache buffer  |
 673                  +---------------+---------------+
 674
 675                                  |<------- allocated size ---------------->|
 676
 677                                                          +--------+
 678                                                          | 1 Byte |
 679                                                          +--------+
 680
 681                         MS-Office seems to do this a lot to determine if there's enough
 682                         space on the filesystem to write a new file.
 683
 684                         Change to :
 685
 686                 End of file ---->|
 687                                  +-----------------------+--------+
 688                                  | Zeroed Cached data    | 1 Byte |
 689                                  +-----------------------+--------+
 690                         */
 691
 692                         flush_write_cache(fsp, WRITE_FLUSH);
 693                         wcp->offset = wcp->file_size;
 694                         wcp->data_size = pos - wcp->file_size + 1;
 695                         memset(wcp->data, '\0', wcp->data_size);
 696                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 697
 698                         /*
 699                          * Update the file size if changed.
 700                          */
 701
 702                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 703                                 if (wcp_file_size_change(fsp) == -1) {
 704                                         return -1;
 705                                 }
 706                         }
 707
 708                         return n;
 709
 710                 } else {
 711
 712                         /* ASCII art..... JRA.
 713
 714    Case 1).
 715
 716                         +---------------+---------------+
 717                         | Cached data   | Cache buffer  |
 718                         +---------------+---------------+
 719
 720                                                               +-------------------+
 721                                                               | Data to write     |
 722                                                               +-------------------+
 723
 724    Case 2).
 725
 726                            +---------------+---------------+
 727                            | Cached data   | Cache buffer  |
 728                            +---------------+---------------+
 729
 730    +-------------------+
 731    | Data to write     |
 732    +-------------------+
 733
 734     Case 3).
 735
 736                            +---------------+---------------+
 737                            | Cached data   | Cache buffer  |
 738                            +---------------+---------------+
 739
 740                   +-----------------------------------------------------+
 741                   | Data to write                                       |
 742                   +-----------------------------------------------------+
 743
 744                   */
 745
 746                         /*
 747                          * Write is bigger than buffer, or there is no overlap on the
 748                          * low or high ends.
 749                          */
 750
 751                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 752 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 753
 754                         /*
 755                          * If write would fit in the cache, and is larger than
 756                          * the data already in the cache, flush the cache and
 757                          * preferentially copy the data new data into it. Otherwise
 758                          * just write the data directly.
 759                          */
 760
 761                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 762                                 cache_flush_needed = True;
 763                         } else {
 764                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 765
 766                                 /*
 767                                  * If the write overlaps the entire cache, then
 768                                  * discard the current contents of the cache.
 769                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 770                                  */
 771
 772                                 if ((pos <= wcp->offset) &&
 773                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 774                                         DEBUG(9,("write_file: discarding overwritten write \
 775 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 776                                         wcp->data_size = 0;
 777                                 }
 778
 779                                 DO_PROFILE_INC(writecache_direct_writes);
 780                                 if (ret == -1) {
 781                                         return ret;
 782                                 }
 783
 784                                 if (pos + ret > wcp->file_size) {
 785                                         wcp->file_size = pos + ret;
 786                                 }
 787
 788                                 return ret;
 789                         }
 790
 791                         write_path = 4;
 792
 793                 }
 794
 795                 if (cache_flush_needed) {
 796                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 797 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 798                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 799                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 800
 801                         flush_write_cache(fsp, WRITE_FLUSH);
 802                 }
 803         }
 804
 805         /*
 806          * If the write request is bigger than the cache
 807          * size, write it all out.
 808          */
 809
 810         if (n > wcp->alloc_size ) {
 811                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 812                 if (ret == -1) {
 813                         return -1;
 814                 }
 815
 816                 if (pos + ret > wcp->file_size) {
 817                         wcp->file_size = pos + n;
 818                 }
 819
 820                 DO_PROFILE_INC(writecache_direct_writes);
 821                 return total_written + n;
 822         }
 823
 824         /*
 825          * If there's any data left, cache it.
 826          */
 827
 828         if (n) {
 829 #ifdef WITH_PROFILE
 830                 if (wcp->data_size) {
 831                         DO_PROFILE_INC(writecache_abutted_writes);
 832                 } else {
 833                         DO_PROFILE_INC(writecache_init_writes);
 834                 }
 835 #endif
 836
 837                 if ((wcp->data_size == 0)
 838                     && (pos > wcp->file_size)
 839                     && (pos + n <= wcp->file_size + wcp->alloc_size)) {
 840                         /*
 841                          * This is a write completely beyond the
 842                          * current EOF, but within reach of the write
 843                          * cache. We expect fill-up writes pretty
 844                          * soon, so it does not make sense to start
 845                          * the write cache at the current
 846                          * offset. These fill-up writes would trigger
 847                          * separate pwrites or even unnecessary cache
 848                          * flushes because they overlap if this is a
 849                          * one-byte allocating write.
 850                          */
 851                         wcp->offset = wcp->file_size;
 852                         wcp->data_size = pos - wcp->file_size;
 853                         memset(wcp->data, 0, wcp->data_size);
 854                 }
 855
 856                 memcpy(wcp->data+wcp->data_size, data, n);
 857                 if (wcp->data_size == 0) {
 858                         wcp->offset = pos;
 859                         DO_PROFILE_INC(writecache_num_write_caches);
 860                 }
 861                 wcp->data_size += n;
 862
 863                 /*
 864                  * Update the file size if changed.
 865                  */
 866
 867                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 868                         if (wcp_file_size_change(fsp) == -1) {
 869                                 return -1;
 870                         }
 871                 }
 872                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 873                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 874
 875                 total_written += n;
 876                 return total_written; /* .... that's a write :) */
 877         }
 878
 879         return total_written;
 880 }
 881
 882 /****************************************************************************
 883  Delete the write cache structure.
 884 ****************************************************************************/
 885
 886 void delete_write_cache(files_struct *fsp)
 887 {
 888         struct write_cache *wcp;
 889
 890         if(!fsp) {
 891                 return;
 892         }
 893
 894         if(!(wcp = fsp->wcp)) {
 895                 return;
 896         }
 897
 898         DO_PROFILE_DEC(writecache_allocated_write_caches);
 899         allocated_write_caches--;
 900
 901         SMB_ASSERT(wcp->data_size == 0);
 902
 903         SAFE_FREE(wcp->data);
 904         SAFE_FREE(fsp->wcp);
 905
 906         DEBUG(10,("delete_write_cache: File %s deleted write cache\n",
 907                   fsp_str_dbg(fsp)));
 908 }
 909
 910 /****************************************************************************
 911  Setup the write cache structure.
 912 ****************************************************************************/
 913
 914 static bool setup_write_cache(files_struct *fsp, off_t file_size)
 915 {
 916         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 917         struct write_cache *wcp;
 918
 919         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 920                 return False;
 921         }
 922
 923         if(alloc_size == 0 || fsp->wcp) {
 924                 return False;
 925         }
 926
 927         if((wcp = SMB_MALLOC_P(struct write_cache)) == NULL) {
 928                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 929                 return False;
 930         }
 931
 932         wcp->file_size = file_size;
 933         wcp->offset = 0;
 934         wcp->alloc_size = alloc_size;
 935         wcp->data_size = 0;
 936         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 937                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 938                         (unsigned int)wcp->alloc_size ));
 939                 SAFE_FREE(wcp);
 940                 return False;
 941         }
 942
 943         memset(wcp->data, '\0', wcp->alloc_size );
 944
 945         fsp->wcp = wcp;
 946         DO_PROFILE_INC(writecache_allocated_write_caches);
 947         allocated_write_caches++;
 948
 949         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 950                   fsp_str_dbg(fsp), (unsigned long)wcp->alloc_size));
 951
 952         return True;
 953 }
 954
 955 /****************************************************************************
 956  Cope with a size change.
 957 ****************************************************************************/
 958
 959 void set_filelen_write_cache(files_struct *fsp, off_t file_size)
 960 {
 961         if(fsp->wcp) {
 962                 /* The cache *must* have been flushed before we do this. */
 963                 if (fsp->wcp->data_size != 0) {
 964                         char *msg;
 965                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 966                                  "on file %s with write cache size = %lu\n",
 967                                  fsp->fsp_name->base_name,
 968                                  (unsigned long)fsp->wcp->data_size) != -1) {
 969                                 smb_panic(msg);
 970                         } else {
 971                                 smb_panic("set_filelen_write_cache");
 972                         }
 973                 }
 974                 fsp->wcp->file_size = file_size;
 975         }
 976 }
 977
 978 /*******************************************************************
 979  Flush a write cache struct to disk.
 980 ********************************************************************/
 981
 982 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 983 {
 984         struct write_cache *wcp = fsp->wcp;
 985         size_t data_size;
 986         ssize_t ret;
 987
 988         if(!wcp || !wcp->data_size) {
 989                 return 0;
 990         }
 991
 992         data_size = wcp->data_size;
 993         wcp->data_size = 0;
 994
 995         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 996
 997         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 998                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 999
1000 #ifdef WITH_PROFILE
1001         if(data_size == wcp->alloc_size) {
1002                 DO_PROFILE_INC(writecache_num_perfect_writes);
1003         }
1004 #endif
1005
1006         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
1007
1008         /*
1009          * Ensure file size if kept up to date if write extends file.
1010          */
1011
1012         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
1013                 wcp->file_size = wcp->offset + ret;
1014         }
1015
1016         return ret;
1017 }
1018
1019 /*******************************************************************
1020 sync a file
1021 ********************************************************************/
1022
1023 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
1024 {
1025         if (fsp->fh->fd == -1)
1026                 return NT_STATUS_INVALID_HANDLE;
1027
1028         if (lp_strict_sync(SNUM(conn)) &&
1029             (lp_syncalways(SNUM(conn)) || write_through)) {
1030                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
1031                 if (ret == -1) {
1032                         return map_nt_error_from_unix(errno);
1033                 }
1034                 ret = SMB_VFS_FSYNC(fsp);
1035                 if (ret == -1) {
1036                         return map_nt_error_from_unix(errno);
1037                 }
1038         }
1039         return NT_STATUS_OK;
1040 }
1041
1042 /************************************************************
1043  Perform a stat whether a valid fd or not.
1044 ************************************************************/
1045
1046 int fsp_stat(files_struct *fsp)
1047 {
1048         if (fsp->fh->fd == -1) {
1049                 if (fsp->posix_open) {
1050                         return SMB_VFS_LSTAT(fsp->conn, fsp->fsp_name);
1051                 } else {
1052                         return SMB_VFS_STAT(fsp->conn, fsp->fsp_name);
1053                 }
1054         } else {
1055                 return SMB_VFS_FSTAT(fsp, &fsp->fsp_name->st);
1056         }
1057 }