source/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 2 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, write to the Free Software
  20    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "includes.h"
  24
  25 static BOOL setup_write_cache(files_struct *, SMB_OFF_T);
  26
  27 /****************************************************************************
  28  Seek a file. Try to avoid the seek if possible.
  29 ****************************************************************************/
  30
  31 static SMB_OFF_T seek_file(files_struct *fsp,SMB_OFF_T pos)
  32 {
  33         SMB_OFF_T offset = 0;
  34         SMB_OFF_T seek_ret;
  35
  36         if (fsp->print_file && lp_postscript(fsp->conn->service))
  37                 offset = 3;
  38
  39         seek_ret = fsp->conn->vfs_ops.lseek(fsp,fsp->fd,pos+offset,SEEK_SET);
  40
  41         if(seek_ret == -1) {
  42                 DEBUG(0,("seek_file: (%s) sys_lseek failed. Error was %s\n",
  43                         fsp->fsp_name, strerror(errno) ));
  44                 fsp->pos = -1;
  45                 return -1;
  46         }
  47
  48         fsp->pos = seek_ret - offset;
  49
  50         DEBUG(10,("seek_file (%s): requested pos = %.0f, new pos = %.0f\n",
  51                 fsp->fsp_name, (double)(pos+offset), (double)fsp->pos ));
  52
  53         return(fsp->pos);
  54 }
  55
  56 /****************************************************************************
  57  Read from write cache if we can.
  58 ****************************************************************************/
  59
  60
  61 static BOOL read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  62 {
  63         write_cache *wcp = fsp->wcp;
  64
  65         if(!wcp)
  66                 return False;
  67
  68         if(n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size)
  69                 return False;
  70
  71         memcpy(data, wcp->data + (pos - wcp->offset), n);
  72
  73         DO_PROFILE_INC(writecache_read_hits);
  74
  75         return True;
  76 }
  77
  78 /****************************************************************************
  79  Read from a file.
  80 ****************************************************************************/
  81
  82 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  83 {
  84         ssize_t ret=0,readret;
  85
  86         /* you can't read from print files */
  87         if (fsp->print_file)
  88                 return -1;
  89
  90         /*
  91          * Serve from write cache if we can.
  92          */
  93
  94         if(read_from_write_cache(fsp, data, pos, n))
  95                 return n;
  96
  97         flush_write_cache(fsp, READ_FLUSH);
  98
  99         if (seek_file(fsp,pos) == -1) {
 100                 DEBUG(3,("read_file: Failed to seek to %.0f\n",(double)pos));
 101                 return(ret);
 102         }
 103
 104         if (n > 0) {
 105 #ifdef DMF_FIX
 106                 int numretries = 3;
 107 tryagain:
 108                 readret = fsp->conn->vfs_ops.read(fsp,fsp->fd,data,n);
 109                 if (readret == -1) {
 110                         if ((errno == EAGAIN) && numretries) {
 111                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
 112                                 (void)sleep(10);
 113                                 --numretries;
 114                                 goto tryagain;
 115                         }
 116                         return -1;
 117                 }
 118 #else /* NO DMF fix. */
 119                 readret = fsp->conn->vfs_ops.read(fsp,fsp->fd,data,n);
 120                 if (readret == -1)
 121                         return -1;
 122 #endif
 123                 if (readret > 0)
 124                         ret += readret;
 125         }
 126
 127         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
 128                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 129
 130         return(ret);
 131 }
 132
 133 /* how many write cache buffers have been allocated */
 134 static unsigned int allocated_write_caches;
 135
 136 /****************************************************************************
 137  *Really* write to a file.
 138 ****************************************************************************/
 139
 140 static ssize_t real_write_file(files_struct *fsp,char *data,SMB_OFF_T pos, size_t n)
 141 {
 142         ssize_t ret;
 143
 144         if ((pos != -1) && (seek_file(fsp,pos) == -1))
 145                 return -1;
 146
 147         ret = vfs_write_data(fsp,data,n);
 148
 149         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 150                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
 151
 152         return ret;
 153 }
 154
 155 /****************************************************************************
 156 write to a file
 157 ****************************************************************************/
 158
 159 ssize_t write_file(files_struct *fsp, char *data, SMB_OFF_T pos, size_t n)
 160 {
 161         write_cache *wcp = fsp->wcp;
 162         ssize_t total_written = 0;
 163         int write_path = -1;
 164
 165         if (fsp->print_file)
 166                 return print_job_write(SNUM(fsp->conn), fsp->print_jobid, data, n);
 167
 168         if (!fsp->can_write) {
 169                 errno = EPERM;
 170                 return(0);
 171         }
 172
 173         if (!fsp->modified) {
 174                 SMB_STRUCT_STAT st;
 175                 fsp->modified = True;
 176
 177                 if (fsp->conn->vfs_ops.fstat(fsp,fsp->fd,&st) == 0) {
 178                         int dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
 179                         fsp->size = st.st_size;
 180                         if (MAP_ARCHIVE(fsp->conn) && !IS_DOS_ARCHIVE(dosmode))
 181                                 file_chmod(fsp->conn,fsp->fsp_name,dosmode | aARCH,&st);
 182
 183                         /*
 184                          * If this is the first write and we have an exclusive oplock then setup
 185                          * the write cache.
 186                          */
 187
 188                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 189                                 setup_write_cache(fsp, st.st_size);
 190                                 wcp = fsp->wcp;
 191                         }
 192                 }
 193         }
 194
 195 #ifdef WITH_PROFILE
 196         DO_PROFILE_INC(writecache_total_writes);
 197         if (!fsp->oplock_type) {
 198                 DO_PROFILE_INC(writecache_non_oplock_writes);
 199         }
 200 #endif
 201
 202         /*
 203          * If this file is level II oplocked then we need
 204          * to grab the shared memory lock and inform all
 205          * other files with a level II lock that they need
 206          * to flush their read caches. We keep the lock over
 207          * the shared memory area whilst doing this.
 208          */
 209
 210         release_level_2_oplocks_on_change(fsp);
 211
 212 #ifdef WITH_PROFILE
 213         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 214                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 215 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 216                         profile_p->writecache_init_writes,
 217                         profile_p->writecache_abutted_writes,
 218                         profile_p->writecache_total_writes,
 219                         profile_p->writecache_non_oplock_writes,
 220                         profile_p->writecache_allocated_write_caches,
 221                         profile_p->writecache_num_write_caches,
 222                         profile_p->writecache_direct_writes,
 223                         profile_p->writecache_num_perfect_writes,
 224                         profile_p->writecache_read_hits ));
 225
 226                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 227                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 228                         profile_p->writecache_flushed_writes[READ_FLUSH],
 229                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 230                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 231                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 232                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 233                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 234         }
 235 #endif
 236
 237         if(!wcp) {
 238                 DO_PROFILE_INC(writecache_direct_writes);
 239                 total_written = real_write_file(fsp, data, pos, n);
 240                 if ((total_written != -1) && (pos + total_written > fsp->size))
 241                         fsp->size = pos + total_written;
 242                 return total_written;
 243         }
 244
 245         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
 246                 fsp->fsp_name, fsp->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
 247
 248         /*
 249          * If we have active cache and it isn't contiguous then we flush.
 250          * NOTE: There is a small problem with running out of disk ....
 251          */
 252
 253         if (wcp->data_size) {
 254
 255                 BOOL cache_flush_needed = False;
 256
 257                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 258
 259                         /*
 260                          * Start of write overlaps or abutts the existing data.
 261                          */
 262
 263                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 264
 265                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 266
 267                         /*
 268                          * Update the current buffer size with the new data.
 269                          */
 270
 271                         if(pos + data_used > wcp->offset + wcp->data_size)
 272                                 wcp->data_size = pos + data_used - wcp->offset;
 273
 274                         /*
 275                          * Update the file size if changed.
 276                          */
 277
 278                         if (wcp->offset + wcp->data_size > wcp->file_size)
 279                                 fsp->size = wcp->file_size = wcp->offset + wcp->data_size;
 280
 281                         /*
 282                          * If we used all the data then
 283                          * return here.
 284                          */
 285
 286                         if(n == data_used)
 287                                 return n;
 288                         else
 289                                 cache_flush_needed = True;
 290
 291                         /*
 292                          * Move the start of data forward by the amount used,
 293                          * cut down the amount left by the same amount.
 294                          */
 295
 296                         data += data_used;
 297                         pos += data_used;
 298                         n -= data_used;
 299
 300                         DO_PROFILE_INC(writecache_abutted_writes);
 301                         total_written = data_used;
 302
 303                         write_path = 1;
 304
 305                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 306                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 307
 308                         /*
 309                          * End of write overlaps the existing data.
 310                          */
 311
 312                         size_t data_used = pos + n - wcp->offset;
 313
 314                         memcpy(wcp->data, data + n - data_used, data_used);
 315
 316                         /*
 317                          * Update the current buffer size with the new data.
 318                          */
 319
 320                         if(pos + n > wcp->offset + wcp->data_size)
 321                                 wcp->data_size = pos + n - wcp->offset;
 322
 323                         /*
 324                          * Update the file size if changed.
 325                          */
 326
 327                         if (wcp->offset + wcp->data_size > wcp->file_size)
 328                                 fsp->size = wcp->file_size = wcp->offset + wcp->data_size;
 329
 330                         /*
 331                          * We don't need to move the start of data, but we
 332                          * cut down the amount left by the amount used.
 333                          */
 334
 335                         n -= data_used;
 336
 337                         /*
 338                          * We cannot have used all the data here.
 339                          */
 340
 341                         cache_flush_needed = True;
 342
 343                         DO_PROFILE_INC(writecache_abutted_writes);
 344                         total_written = data_used;
 345
 346                         write_path = 2;
 347
 348                 } else if ( (pos >= wcp->file_size) &&
 349                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 350                                         (pos > wcp->offset + wcp->data_size) &&
 351                                         (pos < wcp->offset + wcp->alloc_size) ) {
 352
 353                         /*
 354                          * Non-contiguous write part of which fits within
 355                          * the cache buffer and is extending the file
 356                          * and the cache contents reflect the current
 357                          * data up to the current end of the file.
 358                          */
 359
 360                         size_t data_used;
 361
 362                         if(pos + n <= wcp->offset + wcp->alloc_size)
 363                                 data_used = n;
 364                         else
 365                                 data_used = wcp->offset + wcp->alloc_size - pos;
 366
 367                         /*
 368                          * Fill in the non-continuous area with zeros.
 369                          */
 370
 371                         memset(wcp->data + wcp->data_size, '\0',
 372                                 pos - (wcp->offset + wcp->data_size) );
 373
 374                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 375
 376                         /*
 377                          * Update the current buffer size with the new data.
 378                          */
 379
 380                         if(pos + data_used > wcp->offset + wcp->data_size)
 381                                 wcp->data_size = pos + data_used - wcp->offset;
 382
 383                         /*
 384                          * Update the file size if changed.
 385                          */
 386
 387                         if (wcp->offset + wcp->data_size > wcp->file_size)
 388                                 fsp->size = wcp->file_size = wcp->offset + wcp->data_size;
 389
 390                         /*
 391                          * If we used all the data then
 392                          * return here.
 393                          */
 394
 395                         if(n == data_used)
 396                                 return n;
 397                         else
 398                                 cache_flush_needed = True;
 399
 400                         /*
 401                          * Move the start of data forward by the amount used,
 402                          * cut down the amount left by the same amount.
 403                          */
 404
 405                         data += data_used;
 406                         pos += data_used;
 407                         n -= data_used;
 408
 409                         DO_PROFILE_INC(writecache_abutted_writes);
 410                         total_written = data_used;
 411
 412                         write_path = 3;
 413
 414                 } else {
 415
 416                         /*
 417                          * Write is bigger than buffer, or there is no overlap on the
 418                          * low or high ends.
 419                          */
 420
 421                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 422 len = %u\n",fsp->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 423
 424                         /*
 425                          * Update the file size if needed.
 426                          */
 427
 428                         if(pos + n > wcp->file_size)
 429                                 fsp->size = wcp->file_size = pos + n;
 430
 431                         /*
 432                          * If write would fit in the cache, and is larger than
 433                          * the data already in the cache, flush the cache and
 434                          * preferentially copy the data new data into it. Otherwise
 435                          * just write the data directly.
 436                          */
 437
 438                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 439                                 cache_flush_needed = True;
 440                         } else {
 441                                 ssize_t ret = real_write_file(fsp, data, pos, n);
 442
 443                                 /*
 444                                  * If the write overlaps the entire cache, then
 445                                  * discard the current contents of the cache.
 446                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 447                                  */
 448
 449                                 if ((pos <= wcp->offset) &&
 450                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 451                                         DEBUG(9,("write_file: discarding overwritten write \
 452 cache: fd = %d, off=%.0f, size=%u\n", fsp->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 453                                         wcp->data_size = 0;
 454                                 }
 455
 456                                 DO_PROFILE_INC(writecache_direct_writes);
 457                                 if (ret == -1)
 458                                         return ret;
 459
 460                                 if (pos + ret > wcp->file_size)
 461                                         fsp->size = wcp->file_size = pos + ret;
 462
 463                                 return ret;
 464                         }
 465
 466                         write_path = 4;
 467
 468                 }
 469
 470                 if(wcp->data_size > wcp->file_size)
 471                         fsp->size = wcp->file_size = wcp->data_size;
 472
 473                 if (cache_flush_needed) {
 474                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 475 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 476                                 write_path, fsp->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 477                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 478
 479                         flush_write_cache(fsp, WRITE_FLUSH);
 480                 }
 481         }
 482
 483         /*
 484          * If the write request is bigger than the cache
 485          * size, write it all out.
 486          */
 487
 488         if (n > wcp->alloc_size ) {
 489                 ssize_t ret = real_write_file(fsp, data, pos, n);
 490                 if (ret == -1)
 491                         return -1;
 492
 493                 if (pos + ret > wcp->file_size)
 494                         fsp->size = wcp->file_size = pos + n;
 495
 496                 DO_PROFILE_INC(writecache_direct_writes);
 497                 return total_written + n;
 498         }
 499
 500         /*
 501          * If there's any data left, cache it.
 502          */
 503
 504         if (n) {
 505 #ifdef WITH_PROFILE
 506                 if (wcp->data_size) {
 507                         DO_PROFILE_INC(writecache_abutted_writes);
 508                 } else {
 509                         DO_PROFILE_INC(writecache_init_writes);
 510                 }
 511 #endif
 512                 memcpy(wcp->data+wcp->data_size, data, n);
 513                 if (wcp->data_size == 0) {
 514                         wcp->offset = pos;
 515                         DO_PROFILE_INC(writecache_num_write_caches);
 516                 }
 517                 wcp->data_size += n;
 518
 519                 /*
 520                  * Update the file size if changed.
 521                  */
 522
 523                 if (wcp->offset + wcp->data_size > wcp->file_size)
 524                         fsp->size = wcp->file_size = wcp->offset + wcp->data_size;
 525                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 526                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 527
 528                 total_written += n;
 529                 return total_written; /* .... that's a write :) */
 530         }
 531
 532         return total_written;
 533 }
 534
 535 /****************************************************************************
 536  Delete the write cache structure.
 537 ****************************************************************************/
 538
 539 void delete_write_cache(files_struct *fsp)
 540 {
 541         write_cache *wcp;
 542
 543         if(!fsp)
 544                 return;
 545
 546         if(!(wcp = fsp->wcp))
 547                 return;
 548
 549         DO_PROFILE_DEC(writecache_allocated_write_caches);
 550         allocated_write_caches--;
 551
 552         SMB_ASSERT(wcp->data_size == 0);
 553
 554         SAFE_FREE(wcp->data);
 555         SAFE_FREE(fsp->wcp);
 556
 557         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
 558 }
 559
 560 /****************************************************************************
 561  Setup the write cache structure.
 562 ****************************************************************************/
 563
 564 static BOOL setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 565 {
 566         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 567         write_cache *wcp;
 568
 569         if (allocated_write_caches >= MAX_WRITE_CACHES)
 570                 return False;
 571
 572         if(alloc_size == 0 || fsp->wcp)
 573                 return False;
 574
 575         if((wcp = (write_cache *)malloc(sizeof(write_cache))) == NULL) {
 576                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 577                 return False;
 578         }
 579
 580         wcp->file_size = file_size;
 581         wcp->offset = 0;
 582         wcp->alloc_size = alloc_size;
 583         wcp->data_size = 0;
 584         if((wcp->data = malloc(wcp->alloc_size)) == NULL) {
 585                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 586                         (unsigned int)wcp->alloc_size ));
 587                 SAFE_FREE(wcp);
 588                 return False;
 589         }
 590
 591         memset(wcp->data, '\0', wcp->alloc_size );
 592
 593         fsp->wcp = wcp;
 594         DO_PROFILE_INC(writecache_allocated_write_caches);
 595         allocated_write_caches++;
 596
 597         DEBUG(10,("setup_write_cache: File %s allocated write cache size %u\n",
 598                 fsp->fsp_name, wcp->alloc_size ));
 599
 600         return True;
 601 }
 602
 603 /****************************************************************************
 604  Cope with a size change.
 605 ****************************************************************************/
 606
 607 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 608 {
 609         fsp->size = file_size;
 610         if(fsp->wcp) {
 611                 /* The cache *must* have been flushed before we do this. */
 612                 if (fsp->wcp->data_size != 0) {
 613                         pstring msg;
 614                         slprintf(msg, sizeof(msg)-1, "set_filelen_write_cache: size change \
 615 on file %s with write cache size = %u\n", fsp->fsp_name, fsp->wcp->data_size );
 616                         smb_panic(msg);
 617                 }
 618                 fsp->wcp->file_size = file_size;
 619         }
 620 }
 621
 622 /*******************************************************************
 623  Flush a write cache struct to disk.
 624 ********************************************************************/
 625
 626 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 627 {
 628         write_cache *wcp = fsp->wcp;
 629         size_t data_size;
 630         ssize_t ret;
 631
 632         if(!wcp || !wcp->data_size)
 633                 return 0;
 634
 635         data_size = wcp->data_size;
 636         wcp->data_size = 0;
 637
 638         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 639
 640         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 641                 fsp->fd, (double)wcp->offset, (unsigned int)data_size));
 642
 643 #ifdef WITH_PROFILE
 644         if(data_size == wcp->alloc_size)
 645                 DO_PROFILE_INC(writecache_num_perfect_writes);
 646 #endif
 647
 648         ret = real_write_file(fsp, wcp->data, wcp->offset, data_size);
 649
 650         /*
 651          * Ensure file size if kept up to date if write extends file.
 652          */
 653
 654         if ((ret != -1) && (wcp->offset + ret > wcp->file_size))
 655                 wcp->file_size = wcp->offset + ret;
 656
 657         return ret;
 658 }
 659
 660 /*******************************************************************
 661 sync a file
 662 ********************************************************************/
 663
 664 void sync_file(connection_struct *conn, files_struct *fsp)
 665 {
 666         if(lp_strict_sync(SNUM(conn)) && fsp->fd != -1) {
 667                 flush_write_cache(fsp, SYNC_FLUSH);
 668                 conn->vfs_ops.fsync(fsp,fsp->fd);
 669         }
 670 }
 671
 672
 673 /************************************************************
 674  Perform a stat whether a valid fd or not.
 675 ************************************************************/
 676
 677 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
 678 {
 679         if (fsp->fd == -1)
 680                 return vfs_stat(fsp->conn, fsp->fsp_name, pst);
 681         else
 682                 return vfs_fstat(fsp,fsp->fd, pst);
 683 }