63850f24eba7234eb0b834b4a17664ea1dcb21ae
[tprouty/samba.git] / 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 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
24 static bool setup_write_cache(files_struct *, SMB_OFF_T);
25
26 /****************************************************************************
27  Read from write cache if we can.
28 ****************************************************************************/
29
30 static bool read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
31 {
32         write_cache *wcp = fsp->wcp;
33
34         if(!wcp) {
35                 return False;
36         }
37
38         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
39                 return False;
40         }
41
42         memcpy(data, wcp->data + (pos - wcp->offset), n);
43
44         DO_PROFILE_INC(writecache_read_hits);
45
46         return True;
47 }
48
49 /****************************************************************************
50  Read from a file.
51 ****************************************************************************/
52
53 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
54 {
55         ssize_t ret=0,readret;
56
57         /* you can't read from print files */
58         if (fsp->print_file) {
59                 return -1;
60         }
61
62         /*
63          * Serve from write cache if we can.
64          */
65
66         if(read_from_write_cache(fsp, data, pos, n)) {
67                 fsp->fh->pos = pos + n;
68                 fsp->fh->position_information = fsp->fh->pos;
69                 return n;
70         }
71
72         flush_write_cache(fsp, READ_FLUSH);
73
74         fsp->fh->pos = pos;
75
76         if (n > 0) {
77 #ifdef DMF_FIX
78                 int numretries = 3;
79 tryagain:
80                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
81
82                 if (readret == -1) {
83                         if ((errno == EAGAIN) && numretries) {
84                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
85                                 (void)sleep(10);
86                                 --numretries;
87                                 goto tryagain;
88                         }
89                         return -1;
90                 }
91 #else /* NO DMF fix. */
92                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
93
94                 if (readret == -1) {
95                         return -1;
96                 }
97 #endif
98                 if (readret > 0) {
99                         ret += readret;
100                 }
101         }
102
103         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
104                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
105
106         fsp->fh->pos += ret;
107         fsp->fh->position_information = fsp->fh->pos;
108
109         return(ret);
110 }
111
112 /* how many write cache buffers have been allocated */
113 static unsigned int allocated_write_caches;
114
115 /****************************************************************************
116  *Really* write to a file.
117 ****************************************************************************/
118
119 static ssize_t real_write_file(struct smb_request *req,
120                                 files_struct *fsp,
121                                 const char *data,
122                                 SMB_OFF_T pos,
123                                 size_t n)
124 {
125         ssize_t ret;
126
127         if (pos == -1) {
128                 ret = vfs_write_data(req, fsp, data, n);
129         } else {
130                 fsp->fh->pos = pos;
131                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
132                         if (vfs_fill_sparse(fsp, pos) == -1) {
133                                 return -1;
134                         }
135                 }
136                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
137         }
138
139         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
140                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
141
142         if (ret != -1) {
143                 fsp->fh->pos += ret;
144
145 /* Yes - this is correct - writes don't update this. JRA. */
146 /* Found by Samba4 tests. */
147 #if 0
148                 fsp->position_information = fsp->pos;
149 #endif
150         }
151
152         return ret;
153 }
154
155 /****************************************************************************
156  File size cache change.
157  Updates size on disk but doesn't flush the cache.
158 ****************************************************************************/
159
160 static int wcp_file_size_change(files_struct *fsp)
161 {
162         int ret;
163         write_cache *wcp = fsp->wcp;
164
165         wcp->file_size = wcp->offset + wcp->data_size;
166         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
167         if (ret == -1) {
168                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
169                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
170         }
171         return ret;
172 }
173
174 static void update_write_time_handler(struct event_context *ctx,
175                                       struct timed_event *te,
176                                       const struct timeval *now,
177                                       void *private_data)
178 {
179         files_struct *fsp = (files_struct *)private_data;
180
181         /* Remove the timed event handler. */
182         TALLOC_FREE(fsp->update_write_time_event);
183         DEBUG(5, ("Update write time on %s\n", fsp->fsp_name));
184
185         /* change the write time if not already changed by someone else */
186         update_write_time(fsp);
187 }
188
189 /*********************************************************
190  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
191  in the future.
192 *********************************************************/
193
194 void trigger_write_time_update(struct files_struct *fsp)
195 {
196         int delay;
197
198         if (fsp->write_time_forced) {
199                 /* No point - "sticky" write times
200                  * in effect.
201                  */
202                 return;
203         }
204
205         if (fsp->update_write_time_event) {
206                 /*
207                  * No point - an event is already scheduled.
208                  */
209                 return;
210         }
211
212         delay = lp_parm_int(SNUM(fsp->conn),
213                             "smbd", "writetimeupdatedelay",
214                             WRITE_TIME_UPDATE_USEC_DELAY);
215
216         /* trigger the update 2 seconds later */
217         fsp->update_write_time_on_close = true;
218         fsp->update_write_time_event =
219                 event_add_timed(smbd_event_context(), NULL,
220                                 timeval_current_ofs(0, delay),
221                                 "update_write_time_handler",
222                                 update_write_time_handler, fsp);
223 }
224
225 void trigger_write_time_update_immediate(struct files_struct *fsp)
226 {
227         if (fsp->write_time_forced) {
228                 /*
229                  * No point - "sticky" write times
230                  * in effect.
231                  */
232                 return;
233         }
234
235         if (fsp->update_write_time_event) {
236                 /*
237                  * No point - an event is already scheduled.
238                  */
239                 return;
240         }
241
242         fsp->update_write_time_on_close = true;
243         update_write_time(fsp);
244 }
245
246 /****************************************************************************
247  Write to a file.
248 ****************************************************************************/
249
250 ssize_t write_file(struct smb_request *req,
251                         files_struct *fsp,
252                         const char *data,
253                         SMB_OFF_T pos,
254                         size_t n)
255 {
256         write_cache *wcp = fsp->wcp;
257         ssize_t total_written = 0;
258         int write_path = -1;
259
260         if (fsp->print_file) {
261                 fstring sharename;
262                 uint32 jobid;
263
264                 if (!rap_to_pjobid(fsp->rap_print_jobid, sharename, &jobid)) {
265                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
266                                                 (unsigned int)fsp->rap_print_jobid ));
267                         errno = EBADF;
268                         return -1;
269                 }
270
271                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
272         }
273
274         if (!fsp->can_write) {
275                 errno = EPERM;
276                 return -1;
277         }
278
279         if (!fsp->modified) {
280                 SMB_STRUCT_STAT st;
281                 fsp->modified = True;
282
283                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
284                         int dosmode;
285                         trigger_write_time_update(fsp);
286                         dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
287                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
288                                         MAP_ARCHIVE(fsp->conn)) &&
289                                         !IS_DOS_ARCHIVE(dosmode)) {
290                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
291                                                 dosmode | aARCH,&st,
292                                                 NULL,
293                                                 false);
294                         }
295
296                         /*
297                          * If this is the first write and we have an exclusive oplock then setup
298                          * the write cache.
299                          */
300
301                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
302                                 setup_write_cache(fsp, st.st_size);
303                                 wcp = fsp->wcp;
304                         }
305                 }
306         }
307
308 #ifdef WITH_PROFILE
309         DO_PROFILE_INC(writecache_total_writes);
310         if (!fsp->oplock_type) {
311                 DO_PROFILE_INC(writecache_non_oplock_writes);
312         }
313 #endif
314
315         /*
316          * If this file is level II oplocked then we need
317          * to grab the shared memory lock and inform all
318          * other files with a level II lock that they need
319          * to flush their read caches. We keep the lock over
320          * the shared memory area whilst doing this.
321          */
322
323         release_level_2_oplocks_on_change(fsp);
324
325 #ifdef WITH_PROFILE
326         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
327                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
328 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
329                         profile_p->writecache_init_writes,
330                         profile_p->writecache_abutted_writes,
331                         profile_p->writecache_total_writes,
332                         profile_p->writecache_non_oplock_writes,
333                         profile_p->writecache_allocated_write_caches,
334                         profile_p->writecache_num_write_caches,
335                         profile_p->writecache_direct_writes,
336                         profile_p->writecache_num_perfect_writes,
337                         profile_p->writecache_read_hits ));
338
339                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
340                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
341                         profile_p->writecache_flushed_writes[READ_FLUSH],
342                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
343                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
344                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
345                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
346                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
347         }
348 #endif
349
350         if (wcp && req->unread_bytes) {
351                 /* If we're using receivefile don't
352                  * deal with a write cache.
353                  */
354                 flush_write_cache(fsp, WRITE_FLUSH);
355                 delete_write_cache(fsp);
356                 wcp = NULL;
357         }
358
359         if(!wcp) {
360                 DO_PROFILE_INC(writecache_direct_writes);
361                 total_written = real_write_file(req, fsp, data, pos, n);
362                 return total_written;
363         }
364
365         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
366                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
367
368         fsp->fh->pos = pos + n;
369
370         /*
371          * If we have active cache and it isn't contiguous then we flush.
372          * NOTE: There is a small problem with running out of disk ....
373          */
374
375         if (wcp->data_size) {
376                 bool cache_flush_needed = False;
377
378                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
379       
380                         /* ASCII art.... JRA.
381
382       +--------------+-----
383       | Cached data  | Rest of allocated cache buffer....
384       +--------------+-----
385
386             +-------------------+
387             | Data to write     |
388             +-------------------+
389
390                         */
391
392                         /*
393                          * Start of write overlaps or abutts the existing data.
394                          */
395
396                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
397
398                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
399
400                         /*
401                          * Update the current buffer size with the new data.
402                          */
403
404                         if(pos + data_used > wcp->offset + wcp->data_size) {
405                                 wcp->data_size = pos + data_used - wcp->offset;
406                         }
407
408                         /*
409                          * Update the file size if changed.
410                          */
411
412                         if (wcp->offset + wcp->data_size > wcp->file_size) {
413                                 if (wcp_file_size_change(fsp) == -1) {
414                                         return -1;
415                                 }
416                         }
417
418                         /*
419                          * If we used all the data then
420                          * return here.
421                          */
422
423                         if(n == data_used) {
424                                 return n;
425                         } else {
426                                 cache_flush_needed = True;
427                         }
428                         /*
429                          * Move the start of data forward by the amount used,
430                          * cut down the amount left by the same amount.
431                          */
432
433                         data += data_used;
434                         pos += data_used;
435                         n -= data_used;
436
437                         DO_PROFILE_INC(writecache_abutted_writes);
438                         total_written = data_used;
439
440                         write_path = 1;
441
442                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) && 
443                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
444
445                         /* ASCII art.... JRA.
446
447                         +---------------+
448                         | Cache buffer  |
449                         +---------------+
450
451             +-------------------+
452             | Data to write     |
453             +-------------------+
454
455                         */
456
457                         /*
458                          * End of write overlaps the existing data.
459                          */
460
461                         size_t data_used = pos + n - wcp->offset;
462
463                         memcpy(wcp->data, data + n - data_used, data_used);
464
465                         /*
466                          * Update the current buffer size with the new data.
467                          */
468
469                         if(pos + n > wcp->offset + wcp->data_size) {
470                                 wcp->data_size = pos + n - wcp->offset;
471                         }
472
473                         /*
474                          * Update the file size if changed.
475                          */
476
477                         if (wcp->offset + wcp->data_size > wcp->file_size) {
478                                 if (wcp_file_size_change(fsp) == -1) {
479                                         return -1;
480                                 }
481                         }
482
483                         /*
484                          * We don't need to move the start of data, but we
485                          * cut down the amount left by the amount used.
486                          */
487
488                         n -= data_used;
489
490                         /*
491                          * We cannot have used all the data here.
492                          */
493
494                         cache_flush_needed = True;
495
496                         DO_PROFILE_INC(writecache_abutted_writes);
497                         total_written = data_used;
498
499                         write_path = 2;
500
501                 } else if ( (pos >= wcp->file_size) && 
502                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
503                                         (pos > wcp->offset + wcp->data_size) && 
504                                         (pos < wcp->offset + wcp->alloc_size) ) {
505
506                         /* ASCII art.... JRA.
507
508                        End of file ---->|
509
510                         +---------------+---------------+
511                         | Cached data   | Cache buffer  |
512                         +---------------+---------------+
513
514                                               +-------------------+
515                                               | Data to write     |
516                                               +-------------------+
517
518                         */
519
520                         /*
521                          * Non-contiguous write part of which fits within
522                          * the cache buffer and is extending the file
523                          * and the cache contents reflect the current
524                          * data up to the current end of the file.
525                          */
526
527                         size_t data_used;
528
529                         if(pos + n <= wcp->offset + wcp->alloc_size) {
530                                 data_used = n;
531                         } else {
532                                 data_used = wcp->offset + wcp->alloc_size - pos;
533                         }
534
535                         /*
536                          * Fill in the non-continuous area with zeros.
537                          */
538
539                         memset(wcp->data + wcp->data_size, '\0',
540                                 pos - (wcp->offset + wcp->data_size) );
541
542                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
543
544                         /*
545                          * Update the current buffer size with the new data.
546                          */
547
548                         if(pos + data_used > wcp->offset + wcp->data_size) {
549                                 wcp->data_size = pos + data_used - wcp->offset;
550                         }
551
552                         /*
553                          * Update the file size if changed.
554                          */
555
556                         if (wcp->offset + wcp->data_size > wcp->file_size) {
557                                 if (wcp_file_size_change(fsp) == -1) {
558                                         return -1;
559                                 }
560                         }
561
562                         /*
563                          * If we used all the data then
564                          * return here.
565                          */
566
567                         if(n == data_used) {
568                                 return n;
569                         } else {
570                                 cache_flush_needed = True;
571                         }
572
573                         /*
574                          * Move the start of data forward by the amount used,
575                          * cut down the amount left by the same amount.
576                          */
577
578                         data += data_used;
579                         pos += data_used;
580                         n -= data_used;
581
582                         DO_PROFILE_INC(writecache_abutted_writes);
583                         total_written = data_used;
584
585                         write_path = 3;
586
587                 } else if ( (pos >= wcp->file_size) &&
588                             (n == 1) &&
589                             (wcp->file_size == wcp->offset + wcp->data_size) &&
590                             (pos < wcp->file_size + wcp->alloc_size)) {
591
592                         /*
593
594                 End of file ---->|
595
596                  +---------------+---------------+
597                  | Cached data   | Cache buffer  |
598                  +---------------+---------------+
599
600                                  |<------- allocated size ---------------->|
601
602                                                          +--------+
603                                                          | 1 Byte |
604                                                          +--------+
605
606                         MS-Office seems to do this a lot to determine if there's enough
607                         space on the filesystem to write a new file.
608
609                         Change to :
610
611                 End of file ---->|
612                                  +-----------------------+--------+
613                                  | Zeroed Cached data    | 1 Byte |
614                                  +-----------------------+--------+
615                         */
616
617                         flush_write_cache(fsp, WRITE_FLUSH);
618                         wcp->offset = wcp->file_size;
619                         wcp->data_size = pos - wcp->file_size + 1;
620                         memset(wcp->data, '\0', wcp->data_size);
621                         memcpy(wcp->data + wcp->data_size-1, data, 1);
622
623                         /*
624                          * Update the file size if changed.
625                          */
626
627                         if (wcp->offset + wcp->data_size > wcp->file_size) {
628                                 if (wcp_file_size_change(fsp) == -1) {
629                                         return -1;
630                                 }
631                         }
632
633                         return n;
634
635                 } else {
636
637                         /* ASCII art..... JRA.
638
639    Case 1).
640
641                         +---------------+---------------+
642                         | Cached data   | Cache buffer  |
643                         +---------------+---------------+
644
645                                                               +-------------------+
646                                                               | Data to write     |
647                                                               +-------------------+
648
649    Case 2).
650
651                            +---------------+---------------+
652                            | Cached data   | Cache buffer  |
653                            +---------------+---------------+
654
655    +-------------------+
656    | Data to write     |
657    +-------------------+
658
659     Case 3).
660
661                            +---------------+---------------+
662                            | Cached data   | Cache buffer  |
663                            +---------------+---------------+
664
665                   +-----------------------------------------------------+
666                   | Data to write                                       |
667                   +-----------------------------------------------------+
668
669                   */
670
671                         /*
672                          * Write is bigger than buffer, or there is no overlap on the
673                          * low or high ends.
674                          */
675
676                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
677 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
678
679                         /*
680                          * If write would fit in the cache, and is larger than
681                          * the data already in the cache, flush the cache and
682                          * preferentially copy the data new data into it. Otherwise
683                          * just write the data directly.
684                          */
685
686                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
687                                 cache_flush_needed = True;
688                         } else {
689                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
690
691                                 /*
692                                  * If the write overlaps the entire cache, then
693                                  * discard the current contents of the cache.
694                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
695                                  */
696
697                                 if ((pos <= wcp->offset) &&
698                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
699                                         DEBUG(9,("write_file: discarding overwritten write \
700 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
701                                         wcp->data_size = 0;
702                                 }
703
704                                 DO_PROFILE_INC(writecache_direct_writes);
705                                 if (ret == -1) {
706                                         return ret;
707                                 }
708
709                                 if (pos + ret > wcp->file_size) {
710                                         wcp->file_size = pos + ret;
711                                 }
712
713                                 return ret;
714                         }
715
716                         write_path = 4;
717
718                 }
719
720                 if (cache_flush_needed) {
721                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
722 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
723                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
724                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
725
726                         flush_write_cache(fsp, WRITE_FLUSH);
727                 }
728         }
729
730         /*
731          * If the write request is bigger than the cache
732          * size, write it all out.
733          */
734
735         if (n > wcp->alloc_size ) {
736                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
737                 if (ret == -1) {
738                         return -1;
739                 }
740
741                 if (pos + ret > wcp->file_size) {
742                         wcp->file_size = pos + n;
743                 }
744
745                 DO_PROFILE_INC(writecache_direct_writes);
746                 return total_written + n;
747         }
748
749         /*
750          * If there's any data left, cache it.
751          */
752
753         if (n) {
754 #ifdef WITH_PROFILE
755                 if (wcp->data_size) {
756                         DO_PROFILE_INC(writecache_abutted_writes);
757                 } else {
758                         DO_PROFILE_INC(writecache_init_writes);
759                 }
760 #endif
761                 memcpy(wcp->data+wcp->data_size, data, n);
762                 if (wcp->data_size == 0) {
763                         wcp->offset = pos;
764                         DO_PROFILE_INC(writecache_num_write_caches);
765                 }
766                 wcp->data_size += n;
767
768                 /*
769                  * Update the file size if changed.
770                  */
771
772                 if (wcp->offset + wcp->data_size > wcp->file_size) {
773                         if (wcp_file_size_change(fsp) == -1) {
774                                 return -1;
775                         }
776                 }
777                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
778                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
779
780                 total_written += n;
781                 return total_written; /* .... that's a write :) */
782         }
783   
784         return total_written;
785 }
786
787 /****************************************************************************
788  Delete the write cache structure.
789 ****************************************************************************/
790
791 void delete_write_cache(files_struct *fsp)
792 {
793         write_cache *wcp;
794
795         if(!fsp) {
796                 return;
797         }
798
799         if(!(wcp = fsp->wcp)) {
800                 return;
801         }
802
803         DO_PROFILE_DEC(writecache_allocated_write_caches);
804         allocated_write_caches--;
805
806         SMB_ASSERT(wcp->data_size == 0);
807
808         SAFE_FREE(wcp->data);
809         SAFE_FREE(fsp->wcp);
810
811         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
812 }
813
814 /****************************************************************************
815  Setup the write cache structure.
816 ****************************************************************************/
817
818 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
819 {
820         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
821         write_cache *wcp;
822
823         if (allocated_write_caches >= MAX_WRITE_CACHES) {
824                 return False;
825         }
826
827         if(alloc_size == 0 || fsp->wcp) {
828                 return False;
829         }
830
831         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
832                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
833                 return False;
834         }
835
836         wcp->file_size = file_size;
837         wcp->offset = 0;
838         wcp->alloc_size = alloc_size;
839         wcp->data_size = 0;
840         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
841                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
842                         (unsigned int)wcp->alloc_size ));
843                 SAFE_FREE(wcp);
844                 return False;
845         }
846
847         memset(wcp->data, '\0', wcp->alloc_size );
848
849         fsp->wcp = wcp;
850         DO_PROFILE_INC(writecache_allocated_write_caches);
851         allocated_write_caches++;
852
853         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
854                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
855
856         return True;
857 }
858
859 /****************************************************************************
860  Cope with a size change.
861 ****************************************************************************/
862
863 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
864 {
865         if(fsp->wcp) {
866                 /* The cache *must* have been flushed before we do this. */
867                 if (fsp->wcp->data_size != 0) {
868                         char *msg;
869                         asprintf(&msg, "set_filelen_write_cache: size change "
870                                  "on file %s with write cache size = %lu\n",
871                                  fsp->fsp_name,
872                                  (unsigned long)fsp->wcp->data_size);
873                         smb_panic(msg);
874                 }
875                 fsp->wcp->file_size = file_size;
876         }
877 }
878
879 /*******************************************************************
880  Flush a write cache struct to disk.
881 ********************************************************************/
882
883 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
884 {
885         write_cache *wcp = fsp->wcp;
886         size_t data_size;
887         ssize_t ret;
888
889         if(!wcp || !wcp->data_size) {
890                 return 0;
891         }
892
893         data_size = wcp->data_size;
894         wcp->data_size = 0;
895
896         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
897
898         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
899                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
900
901 #ifdef WITH_PROFILE
902         if(data_size == wcp->alloc_size) {
903                 DO_PROFILE_INC(writecache_num_perfect_writes);
904         }
905 #endif
906
907         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
908
909         /*
910          * Ensure file size if kept up to date if write extends file.
911          */
912
913         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
914                 wcp->file_size = wcp->offset + ret;
915         }
916
917         return ret;
918 }
919
920 /*******************************************************************
921 sync a file
922 ********************************************************************/
923
924 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
925 {
926         if (fsp->fh->fd == -1)
927                 return NT_STATUS_INVALID_HANDLE;
928
929         if (lp_strict_sync(SNUM(conn)) &&
930             (lp_syncalways(SNUM(conn)) || write_through)) {
931                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
932                 if (ret == -1) {
933                         return map_nt_error_from_unix(errno);
934                 }
935                 ret = SMB_VFS_FSYNC(fsp);
936                 if (ret == -1) {
937                         return map_nt_error_from_unix(errno);
938                 }
939         }
940         return NT_STATUS_OK;
941 }
942
943 /************************************************************
944  Perform a stat whether a valid fd or not.
945 ************************************************************/
946
947 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
948 {
949         if (fsp->fh->fd == -1) {
950                 return SMB_VFS_STAT(fsp->conn, fsp->fsp_name, pst);
951         } else {
952                 return SMB_VFS_FSTAT(fsp, pst);
953         }
954 }