NTFS: Fix compilation when configured read-only.
[linux-2.6.git] / fs / ntfs / lcnalloc.c
1 /*
2  * lcnalloc.c - Cluster (de)allocation code.  Part of the Linux-NTFS project.
3  *
4  * Copyright (c) 2004-2005 Anton Altaparmakov
5  *
6  * This program/include file is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU General Public License as published
8  * by the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program/include file is distributed in the hope that it will be
12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program (in the main directory of the Linux-NTFS
18  * distribution in the file COPYING); if not, write to the Free Software
19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
20  */
21
22 #ifdef NTFS_RW
23
24 #include <linux/pagemap.h>
25
26 #include "lcnalloc.h"
27 #include "debug.h"
28 #include "bitmap.h"
29 #include "inode.h"
30 #include "volume.h"
31 #include "attrib.h"
32 #include "malloc.h"
33 #include "aops.h"
34 #include "ntfs.h"
35
36 /**
37  * ntfs_cluster_free_from_rl_nolock - free clusters from runlist
38  * @vol:        mounted ntfs volume on which to free the clusters
39  * @rl:         runlist describing the clusters to free
40  *
41  * Free all the clusters described by the runlist @rl on the volume @vol.  In
42  * the case of an error being returned, at least some of the clusters were not
43  * freed.
44  *
45  * Return 0 on success and -errno on error.
46  *
47  * Locking: - The volume lcn bitmap must be locked for writing on entry and is
48  *            left locked on return.
49  */
50 int ntfs_cluster_free_from_rl_nolock(ntfs_volume *vol,
51                 const runlist_element *rl)
52 {
53         struct inode *lcnbmp_vi = vol->lcnbmp_ino;
54         int ret = 0;
55
56         ntfs_debug("Entering.");
57         for (; rl->length; rl++) {
58                 int err;
59
60                 if (rl->lcn < 0)
61                         continue;
62                 err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
63                 if (unlikely(err && (!ret || ret == -ENOMEM) && ret != err))
64                         ret = err;
65         }
66         ntfs_debug("Done.");
67         return ret;
68 }
69
70 /**
71  * ntfs_cluster_alloc - allocate clusters on an ntfs volume
72  * @vol:        mounted ntfs volume on which to allocate the clusters
73  * @start_vcn:  vcn to use for the first allocated cluster
74  * @count:      number of clusters to allocate
75  * @start_lcn:  starting lcn at which to allocate the clusters (or -1 if none)
76  * @zone:       zone from which to allocate the clusters
77  *
78  * Allocate @count clusters preferably starting at cluster @start_lcn or at the
79  * current allocator position if @start_lcn is -1, on the mounted ntfs volume
80  * @vol. @zone is either DATA_ZONE for allocation of normal clusters or
81  * MFT_ZONE for allocation of clusters for the master file table, i.e. the
82  * $MFT/$DATA attribute.
83  *
84  * @start_vcn specifies the vcn of the first allocated cluster.  This makes
85  * merging the resulting runlist with the old runlist easier.
86  *
87  * You need to check the return value with IS_ERR().  If this is false, the
88  * function was successful and the return value is a runlist describing the
89  * allocated cluster(s).  If IS_ERR() is true, the function failed and
90  * PTR_ERR() gives you the error code.
91  *
92  * Notes on the allocation algorithm
93  * =================================
94  *
95  * There are two data zones.  First is the area between the end of the mft zone
96  * and the end of the volume, and second is the area between the start of the
97  * volume and the start of the mft zone.  On unmodified/standard NTFS 1.x
98  * volumes, the second data zone does not exist due to the mft zone being
99  * expanded to cover the start of the volume in order to reserve space for the
100  * mft bitmap attribute.
101  *
102  * This is not the prettiest function but the complexity stems from the need of
103  * implementing the mft vs data zoned approach and from the fact that we have
104  * access to the lcn bitmap in portions of up to 8192 bytes at a time, so we
105  * need to cope with crossing over boundaries of two buffers.  Further, the
106  * fact that the allocator allows for caller supplied hints as to the location
107  * of where allocation should begin and the fact that the allocator keeps track
108  * of where in the data zones the next natural allocation should occur,
109  * contribute to the complexity of the function.  But it should all be
110  * worthwhile, because this allocator should: 1) be a full implementation of
111  * the MFT zone approach used by Windows NT, 2) cause reduction in
112  * fragmentation, and 3) be speedy in allocations (the code is not optimized
113  * for speed, but the algorithm is, so further speed improvements are probably
114  * possible).
115  *
116  * FIXME: We should be monitoring cluster allocation and increment the MFT zone
117  * size dynamically but this is something for the future.  We will just cause
118  * heavier fragmentation by not doing it and I am not even sure Windows would
119  * grow the MFT zone dynamically, so it might even be correct not to do this.
120  * The overhead in doing dynamic MFT zone expansion would be very large and
121  * unlikely worth the effort. (AIA)
122  *
123  * TODO: I have added in double the required zone position pointer wrap around
124  * logic which can be optimized to having only one of the two logic sets.
125  * However, having the double logic will work fine, but if we have only one of
126  * the sets and we get it wrong somewhere, then we get into trouble, so
127  * removing the duplicate logic requires _very_ careful consideration of _all_
128  * possible code paths.  So at least for now, I am leaving the double logic -
129  * better safe than sorry... (AIA)
130  *
131  * Locking: - The volume lcn bitmap must be unlocked on entry and is unlocked
132  *            on return.
133  *          - This function takes the volume lcn bitmap lock for writing and
134  *            modifies the bitmap contents.
135  */
136 runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
137                 const s64 count, const LCN start_lcn,
138                 const NTFS_CLUSTER_ALLOCATION_ZONES zone)
139 {
140         LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
141         LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
142         s64 clusters;
143         loff_t i_size;
144         struct inode *lcnbmp_vi;
145         runlist_element *rl = NULL;
146         struct address_space *mapping;
147         struct page *page = NULL;
148         u8 *buf, *byte;
149         int err = 0, rlpos, rlsize, buf_size;
150         u8 pass, done_zones, search_zone, need_writeback = 0, bit;
151
152         ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
153                         "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
154                         (unsigned long long)count,
155                         (unsigned long long)start_lcn,
156                         zone == MFT_ZONE ? "MFT" : "DATA");
157         BUG_ON(!vol);
158         lcnbmp_vi = vol->lcnbmp_ino;
159         BUG_ON(!lcnbmp_vi);
160         BUG_ON(start_vcn < 0);
161         BUG_ON(count < 0);
162         BUG_ON(start_lcn < -1);
163         BUG_ON(zone < FIRST_ZONE);
164         BUG_ON(zone > LAST_ZONE);
165
166         /* Return empty runlist if @count == 0 */
167         // FIXME: Do we want to just return NULL instead? (AIA)
168         if (!count) {
169                 rl = ntfs_malloc_nofs(PAGE_SIZE);
170                 if (!rl)
171                         return ERR_PTR(-ENOMEM);
172                 rl[0].vcn = start_vcn;
173                 rl[0].lcn = LCN_RL_NOT_MAPPED;
174                 rl[0].length = 0;
175                 return rl;
176         }
177         /* Take the lcnbmp lock for writing. */
178         down_write(&vol->lcnbmp_lock);
179         /*
180          * If no specific @start_lcn was requested, use the current data zone
181          * position, otherwise use the requested @start_lcn but make sure it
182          * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
183          * and pass depending on whether we are starting inside a zone (1) or
184          * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
185          * we either start at the current position within the mft zone or at
186          * the specified position.  If the latter is out of bounds then we start
187          * at the beginning of the MFT_ZONE.
188          */
189         done_zones = 0;
190         pass = 1;
191         /*
192          * zone_start and zone_end are the current search range.  search_zone
193          * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
194          * volume) and 4 for data zone 2 (start of volume till start of mft
195          * zone).
196          */
197         zone_start = start_lcn;
198         if (zone_start < 0) {
199                 if (zone == DATA_ZONE)
200                         zone_start = vol->data1_zone_pos;
201                 else
202                         zone_start = vol->mft_zone_pos;
203                 if (!zone_start) {
204                         /*
205                          * Zone starts at beginning of volume which means a
206                          * single pass is sufficient.
207                          */
208                         pass = 2;
209                 }
210         } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
211                         zone_start < vol->mft_zone_end) {
212                 zone_start = vol->mft_zone_end;
213                 /*
214                  * Starting at beginning of data1_zone which means a single
215                  * pass in this zone is sufficient.
216                  */
217                 pass = 2;
218         } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
219                         zone_start >= vol->mft_zone_end)) {
220                 zone_start = vol->mft_lcn;
221                 if (!vol->mft_zone_end)
222                         zone_start = 0;
223                 /*
224                  * Starting at beginning of volume which means a single pass
225                  * is sufficient.
226                  */
227                 pass = 2;
228         }
229         if (zone == MFT_ZONE) {
230                 zone_end = vol->mft_zone_end;
231                 search_zone = 1;
232         } else /* if (zone == DATA_ZONE) */ {
233                 /* Skip searching the mft zone. */
234                 done_zones |= 1;
235                 if (zone_start >= vol->mft_zone_end) {
236                         zone_end = vol->nr_clusters;
237                         search_zone = 2;
238                 } else {
239                         zone_end = vol->mft_zone_start;
240                         search_zone = 4;
241                 }
242         }
243         /*
244          * bmp_pos is the current bit position inside the bitmap.  We use
245          * bmp_initial_pos to determine whether or not to do a zone switch.
246          */
247         bmp_pos = bmp_initial_pos = zone_start;
248
249         /* Loop until all clusters are allocated, i.e. clusters == 0. */
250         clusters = count;
251         rlpos = rlsize = 0;
252         mapping = lcnbmp_vi->i_mapping;
253         i_size = i_size_read(lcnbmp_vi);
254         while (1) {
255                 ntfs_debug("Start of outer while loop: done_zones 0x%x, "
256                                 "search_zone %i, pass %i, zone_start 0x%llx, "
257                                 "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
258                                 "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
259                                 done_zones, search_zone, pass,
260                                 (unsigned long long)zone_start,
261                                 (unsigned long long)zone_end,
262                                 (unsigned long long)bmp_initial_pos,
263                                 (unsigned long long)bmp_pos, rlpos, rlsize);
264                 /* Loop until we run out of free clusters. */
265                 last_read_pos = bmp_pos >> 3;
266                 ntfs_debug("last_read_pos 0x%llx.",
267                                 (unsigned long long)last_read_pos);
268                 if (last_read_pos > i_size) {
269                         ntfs_debug("End of attribute reached.  "
270                                         "Skipping to zone_pass_done.");
271                         goto zone_pass_done;
272                 }
273                 if (likely(page)) {
274                         if (need_writeback) {
275                                 ntfs_debug("Marking page dirty.");
276                                 flush_dcache_page(page);
277                                 set_page_dirty(page);
278                                 need_writeback = 0;
279                         }
280                         ntfs_unmap_page(page);
281                 }
282                 page = ntfs_map_page(mapping, last_read_pos >>
283                                 PAGE_CACHE_SHIFT);
284                 if (IS_ERR(page)) {
285                         err = PTR_ERR(page);
286                         ntfs_error(vol->sb, "Failed to map page.");
287                         goto out;
288                 }
289                 buf_size = last_read_pos & ~PAGE_CACHE_MASK;
290                 buf = page_address(page) + buf_size;
291                 buf_size = PAGE_CACHE_SIZE - buf_size;
292                 if (unlikely(last_read_pos + buf_size > i_size))
293                         buf_size = i_size - last_read_pos;
294                 buf_size <<= 3;
295                 lcn = bmp_pos & 7;
296                 bmp_pos &= ~7;
297                 ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
298                                 "bmp_pos 0x%llx, need_writeback %i.", buf_size,
299                                 (unsigned long long)lcn,
300                                 (unsigned long long)bmp_pos, need_writeback);
301                 while (lcn < buf_size && lcn + bmp_pos < zone_end) {
302                         byte = buf + (lcn >> 3);
303                         ntfs_debug("In inner while loop: buf_size %i, "
304                                         "lcn 0x%llx, bmp_pos 0x%llx, "
305                                         "need_writeback %i, byte ofs 0x%x, "
306                                         "*byte 0x%x.", buf_size,
307                                         (unsigned long long)lcn,
308                                         (unsigned long long)bmp_pos,
309                                         need_writeback,
310                                         (unsigned int)(lcn >> 3),
311                                         (unsigned int)*byte);
312                         /* Skip full bytes. */
313                         if (*byte == 0xff) {
314                                 lcn = (lcn + 8) & ~7;
315                                 ntfs_debug("Continuing while loop 1.");
316                                 continue;
317                         }
318                         bit = 1 << (lcn & 7);
319                         ntfs_debug("bit %i.", bit);
320                         /* If the bit is already set, go onto the next one. */
321                         if (*byte & bit) {
322                                 lcn++;
323                                 ntfs_debug("Continuing while loop 2.");
324                                 continue;
325                         }
326                         /*
327                          * Allocate more memory if needed, including space for
328                          * the terminator element.
329                          * ntfs_malloc_nofs() operates on whole pages only.
330                          */
331                         if ((rlpos + 2) * sizeof(*rl) > rlsize) {
332                                 runlist_element *rl2;
333
334                                 ntfs_debug("Reallocating memory.");
335                                 if (!rl)
336                                         ntfs_debug("First free bit is at LCN "
337                                                         "0x%llx.",
338                                                         (unsigned long long)
339                                                         (lcn + bmp_pos));
340                                 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
341                                 if (unlikely(!rl2)) {
342                                         err = -ENOMEM;
343                                         ntfs_error(vol->sb, "Failed to "
344                                                         "allocate memory.");
345                                         goto out;
346                                 }
347                                 memcpy(rl2, rl, rlsize);
348                                 ntfs_free(rl);
349                                 rl = rl2;
350                                 rlsize += PAGE_SIZE;
351                                 ntfs_debug("Reallocated memory, rlsize 0x%x.",
352                                                 rlsize);
353                         }
354                         /* Allocate the bitmap bit. */
355                         *byte |= bit;
356                         /* We need to write this bitmap page to disk. */
357                         need_writeback = 1;
358                         ntfs_debug("*byte 0x%x, need_writeback is set.",
359                                         (unsigned int)*byte);
360                         /*
361                          * Coalesce with previous run if adjacent LCNs.
362                          * Otherwise, append a new run.
363                          */
364                         ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
365                                         "prev_lcn 0x%llx, lcn 0x%llx, "
366                                         "bmp_pos 0x%llx, prev_run_len 0x%llx, "
367                                         "rlpos %i.",
368                                         (unsigned long long)(lcn + bmp_pos),
369                                         1ULL, (unsigned long long)prev_lcn,
370                                         (unsigned long long)lcn,
371                                         (unsigned long long)bmp_pos,
372                                         (unsigned long long)prev_run_len,
373                                         rlpos);
374                         if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
375                                 ntfs_debug("Coalescing to run (lcn 0x%llx, "
376                                                 "len 0x%llx).",
377                                                 (unsigned long long)
378                                                 rl[rlpos - 1].lcn,
379                                                 (unsigned long long)
380                                                 rl[rlpos - 1].length);
381                                 rl[rlpos - 1].length = ++prev_run_len;
382                                 ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
383                                                 "prev_run_len 0x%llx.",
384                                                 (unsigned long long)
385                                                 rl[rlpos - 1].lcn,
386                                                 (unsigned long long)
387                                                 rl[rlpos - 1].length,
388                                                 (unsigned long long)
389                                                 prev_run_len);
390                         } else {
391                                 if (likely(rlpos)) {
392                                         ntfs_debug("Adding new run, (previous "
393                                                         "run lcn 0x%llx, "
394                                                         "len 0x%llx).",
395                                                         (unsigned long long)
396                                                         rl[rlpos - 1].lcn,
397                                                         (unsigned long long)
398                                                         rl[rlpos - 1].length);
399                                         rl[rlpos].vcn = rl[rlpos - 1].vcn +
400                                                         prev_run_len;
401                                 } else {
402                                         ntfs_debug("Adding new run, is first "
403                                                         "run.");
404                                         rl[rlpos].vcn = start_vcn;
405                                 }
406                                 rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
407                                 rl[rlpos].length = prev_run_len = 1;
408                                 rlpos++;
409                         }
410                         /* Done? */
411                         if (!--clusters) {
412                                 LCN tc;
413                                 /*
414                                  * Update the current zone position.  Positions
415                                  * of already scanned zones have been updated
416                                  * during the respective zone switches.
417                                  */
418                                 tc = lcn + bmp_pos + 1;
419                                 ntfs_debug("Done. Updating current zone "
420                                                 "position, tc 0x%llx, "
421                                                 "search_zone %i.",
422                                                 (unsigned long long)tc,
423                                                 search_zone);
424                                 switch (search_zone) {
425                                 case 1:
426                                         ntfs_debug("Before checks, "
427                                                         "vol->mft_zone_pos "
428                                                         "0x%llx.",
429                                                         (unsigned long long)
430                                                         vol->mft_zone_pos);
431                                         if (tc >= vol->mft_zone_end) {
432                                                 vol->mft_zone_pos =
433                                                                 vol->mft_lcn;
434                                                 if (!vol->mft_zone_end)
435                                                         vol->mft_zone_pos = 0;
436                                         } else if ((bmp_initial_pos >=
437                                                         vol->mft_zone_pos ||
438                                                         tc > vol->mft_zone_pos)
439                                                         && tc >= vol->mft_lcn)
440                                                 vol->mft_zone_pos = tc;
441                                         ntfs_debug("After checks, "
442                                                         "vol->mft_zone_pos "
443                                                         "0x%llx.",
444                                                         (unsigned long long)
445                                                         vol->mft_zone_pos);
446                                         break;
447                                 case 2:
448                                         ntfs_debug("Before checks, "
449                                                         "vol->data1_zone_pos "
450                                                         "0x%llx.",
451                                                         (unsigned long long)
452                                                         vol->data1_zone_pos);
453                                         if (tc >= vol->nr_clusters)
454                                                 vol->data1_zone_pos =
455                                                              vol->mft_zone_end;
456                                         else if ((bmp_initial_pos >=
457                                                     vol->data1_zone_pos ||
458                                                     tc > vol->data1_zone_pos)
459                                                     && tc >= vol->mft_zone_end)
460                                                 vol->data1_zone_pos = tc;
461                                         ntfs_debug("After checks, "
462                                                         "vol->data1_zone_pos "
463                                                         "0x%llx.",
464                                                         (unsigned long long)
465                                                         vol->data1_zone_pos);
466                                         break;
467                                 case 4:
468                                         ntfs_debug("Before checks, "
469                                                         "vol->data2_zone_pos "
470                                                         "0x%llx.",
471                                                         (unsigned long long)
472                                                         vol->data2_zone_pos);
473                                         if (tc >= vol->mft_zone_start)
474                                                 vol->data2_zone_pos = 0;
475                                         else if (bmp_initial_pos >=
476                                                       vol->data2_zone_pos ||
477                                                       tc > vol->data2_zone_pos)
478                                                 vol->data2_zone_pos = tc;
479                                         ntfs_debug("After checks, "
480                                                         "vol->data2_zone_pos "
481                                                         "0x%llx.",
482                                                         (unsigned long long)
483                                                         vol->data2_zone_pos);
484                                         break;
485                                 default:
486                                         BUG();
487                                 }
488                                 ntfs_debug("Finished.  Going to out.");
489                                 goto out;
490                         }
491                         lcn++;
492                 }
493                 bmp_pos += buf_size;
494                 ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
495                                 "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
496                                 buf_size, (unsigned long long)lcn,
497                                 (unsigned long long)bmp_pos, need_writeback);
498                 if (bmp_pos < zone_end) {
499                         ntfs_debug("Continuing outer while loop, "
500                                         "bmp_pos 0x%llx, zone_end 0x%llx.",
501                                         (unsigned long long)bmp_pos,
502                                         (unsigned long long)zone_end);
503                         continue;
504                 }
505 zone_pass_done: /* Finished with the current zone pass. */
506                 ntfs_debug("At zone_pass_done, pass %i.", pass);
507                 if (pass == 1) {
508                         /*
509                          * Now do pass 2, scanning the first part of the zone
510                          * we omitted in pass 1.
511                          */
512                         pass = 2;
513                         zone_end = zone_start;
514                         switch (search_zone) {
515                         case 1: /* mft_zone */
516                                 zone_start = vol->mft_zone_start;
517                                 break;
518                         case 2: /* data1_zone */
519                                 zone_start = vol->mft_zone_end;
520                                 break;
521                         case 4: /* data2_zone */
522                                 zone_start = 0;
523                                 break;
524                         default:
525                                 BUG();
526                         }
527                         /* Sanity check. */
528                         if (zone_end < zone_start)
529                                 zone_end = zone_start;
530                         bmp_pos = zone_start;
531                         ntfs_debug("Continuing outer while loop, pass 2, "
532                                         "zone_start 0x%llx, zone_end 0x%llx, "
533                                         "bmp_pos 0x%llx.",
534                                         (unsigned long long)zone_start,
535                                         (unsigned long long)zone_end,
536                                         (unsigned long long)bmp_pos);
537                         continue;
538                 } /* pass == 2 */
539 done_zones_check:
540                 ntfs_debug("At done_zones_check, search_zone %i, done_zones "
541                                 "before 0x%x, done_zones after 0x%x.",
542                                 search_zone, done_zones,
543                                 done_zones | search_zone);
544                 done_zones |= search_zone;
545                 if (done_zones < 7) {
546                         ntfs_debug("Switching zone.");
547                         /* Now switch to the next zone we haven't done yet. */
548                         pass = 1;
549                         switch (search_zone) {
550                         case 1:
551                                 ntfs_debug("Switching from mft zone to data1 "
552                                                 "zone.");
553                                 /* Update mft zone position. */
554                                 if (rlpos) {
555                                         LCN tc;
556
557                                         ntfs_debug("Before checks, "
558                                                         "vol->mft_zone_pos "
559                                                         "0x%llx.",
560                                                         (unsigned long long)
561                                                         vol->mft_zone_pos);
562                                         tc = rl[rlpos - 1].lcn +
563                                                         rl[rlpos - 1].length;
564                                         if (tc >= vol->mft_zone_end) {
565                                                 vol->mft_zone_pos =
566                                                                 vol->mft_lcn;
567                                                 if (!vol->mft_zone_end)
568                                                         vol->mft_zone_pos = 0;
569                                         } else if ((bmp_initial_pos >=
570                                                         vol->mft_zone_pos ||
571                                                         tc > vol->mft_zone_pos)
572                                                         && tc >= vol->mft_lcn)
573                                                 vol->mft_zone_pos = tc;
574                                         ntfs_debug("After checks, "
575                                                         "vol->mft_zone_pos "
576                                                         "0x%llx.",
577                                                         (unsigned long long)
578                                                         vol->mft_zone_pos);
579                                 }
580                                 /* Switch from mft zone to data1 zone. */
581 switch_to_data1_zone:           search_zone = 2;
582                                 zone_start = bmp_initial_pos =
583                                                 vol->data1_zone_pos;
584                                 zone_end = vol->nr_clusters;
585                                 if (zone_start == vol->mft_zone_end)
586                                         pass = 2;
587                                 if (zone_start >= zone_end) {
588                                         vol->data1_zone_pos = zone_start =
589                                                         vol->mft_zone_end;
590                                         pass = 2;
591                                 }
592                                 break;
593                         case 2:
594                                 ntfs_debug("Switching from data1 zone to "
595                                                 "data2 zone.");
596                                 /* Update data1 zone position. */
597                                 if (rlpos) {
598                                         LCN tc;
599
600                                         ntfs_debug("Before checks, "
601                                                         "vol->data1_zone_pos "
602                                                         "0x%llx.",
603                                                         (unsigned long long)
604                                                         vol->data1_zone_pos);
605                                         tc = rl[rlpos - 1].lcn +
606                                                         rl[rlpos - 1].length;
607                                         if (tc >= vol->nr_clusters)
608                                                 vol->data1_zone_pos =
609                                                              vol->mft_zone_end;
610                                         else if ((bmp_initial_pos >=
611                                                     vol->data1_zone_pos ||
612                                                     tc > vol->data1_zone_pos)
613                                                     && tc >= vol->mft_zone_end)
614                                                 vol->data1_zone_pos = tc;
615                                         ntfs_debug("After checks, "
616                                                         "vol->data1_zone_pos "
617                                                         "0x%llx.",
618                                                         (unsigned long long)
619                                                         vol->data1_zone_pos);
620                                 }
621                                 /* Switch from data1 zone to data2 zone. */
622                                 search_zone = 4;
623                                 zone_start = bmp_initial_pos =
624                                                 vol->data2_zone_pos;
625                                 zone_end = vol->mft_zone_start;
626                                 if (!zone_start)
627                                         pass = 2;
628                                 if (zone_start >= zone_end) {
629                                         vol->data2_zone_pos = zone_start =
630                                                         bmp_initial_pos = 0;
631                                         pass = 2;
632                                 }
633                                 break;
634                         case 4:
635                                 ntfs_debug("Switching from data2 zone to "
636                                                 "data1 zone.");
637                                 /* Update data2 zone position. */
638                                 if (rlpos) {
639                                         LCN tc;
640
641                                         ntfs_debug("Before checks, "
642                                                         "vol->data2_zone_pos "
643                                                         "0x%llx.",
644                                                         (unsigned long long)
645                                                         vol->data2_zone_pos);
646                                         tc = rl[rlpos - 1].lcn +
647                                                         rl[rlpos - 1].length;
648                                         if (tc >= vol->mft_zone_start)
649                                                 vol->data2_zone_pos = 0;
650                                         else if (bmp_initial_pos >=
651                                                       vol->data2_zone_pos ||
652                                                       tc > vol->data2_zone_pos)
653                                                 vol->data2_zone_pos = tc;
654                                         ntfs_debug("After checks, "
655                                                         "vol->data2_zone_pos "
656                                                         "0x%llx.",
657                                                         (unsigned long long)
658                                                         vol->data2_zone_pos);
659                                 }
660                                 /* Switch from data2 zone to data1 zone. */
661                                 goto switch_to_data1_zone;
662                         default:
663                                 BUG();
664                         }
665                         ntfs_debug("After zone switch, search_zone %i, "
666                                         "pass %i, bmp_initial_pos 0x%llx, "
667                                         "zone_start 0x%llx, zone_end 0x%llx.",
668                                         search_zone, pass,
669                                         (unsigned long long)bmp_initial_pos,
670                                         (unsigned long long)zone_start,
671                                         (unsigned long long)zone_end);
672                         bmp_pos = zone_start;
673                         if (zone_start == zone_end) {
674                                 ntfs_debug("Empty zone, going to "
675                                                 "done_zones_check.");
676                                 /* Empty zone. Don't bother searching it. */
677                                 goto done_zones_check;
678                         }
679                         ntfs_debug("Continuing outer while loop.");
680                         continue;
681                 } /* done_zones == 7 */
682                 ntfs_debug("All zones are finished.");
683                 /*
684                  * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
685                  * MFT_ZONE, we have really run out of space.
686                  */
687                 mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
688                 ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
689                                 "0x%llx, mft_zone_size 0x%llx.",
690                                 (unsigned long long)vol->mft_zone_start,
691                                 (unsigned long long)vol->mft_zone_end,
692                                 (unsigned long long)mft_zone_size);
693                 if (zone == MFT_ZONE || mft_zone_size <= 0) {
694                         ntfs_debug("No free clusters left, going to out.");
695                         /* Really no more space left on device. */
696                         err = -ENOSPC;
697                         goto out;
698                 } /* zone == DATA_ZONE && mft_zone_size > 0 */
699                 ntfs_debug("Shrinking mft zone.");
700                 zone_end = vol->mft_zone_end;
701                 mft_zone_size >>= 1;
702                 if (mft_zone_size > 0)
703                         vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
704                 else /* mft zone and data2 zone no longer exist. */
705                         vol->data2_zone_pos = vol->mft_zone_start =
706                                         vol->mft_zone_end = 0;
707                 if (vol->mft_zone_pos >= vol->mft_zone_end) {
708                         vol->mft_zone_pos = vol->mft_lcn;
709                         if (!vol->mft_zone_end)
710                                 vol->mft_zone_pos = 0;
711                 }
712                 bmp_pos = zone_start = bmp_initial_pos =
713                                 vol->data1_zone_pos = vol->mft_zone_end;
714                 search_zone = 2;
715                 pass = 2;
716                 done_zones &= ~2;
717                 ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
718                                 "vol->mft_zone_start 0x%llx, "
719                                 "vol->mft_zone_end 0x%llx, "
720                                 "vol->mft_zone_pos 0x%llx, search_zone 2, "
721                                 "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
722                                 "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
723                                 "continuing outer while loop.",
724                                 (unsigned long long)mft_zone_size,
725                                 (unsigned long long)vol->mft_zone_start,
726                                 (unsigned long long)vol->mft_zone_end,
727                                 (unsigned long long)vol->mft_zone_pos,
728                                 done_zones, (unsigned long long)zone_start,
729                                 (unsigned long long)zone_end,
730                                 (unsigned long long)vol->data1_zone_pos);
731         }
732         ntfs_debug("After outer while loop.");
733 out:
734         ntfs_debug("At out.");
735         /* Add runlist terminator element. */
736         if (likely(rl)) {
737                 rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
738                 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
739                 rl[rlpos].length = 0;
740         }
741         if (likely(page && !IS_ERR(page))) {
742                 if (need_writeback) {
743                         ntfs_debug("Marking page dirty.");
744                         flush_dcache_page(page);
745                         set_page_dirty(page);
746                         need_writeback = 0;
747                 }
748                 ntfs_unmap_page(page);
749         }
750         if (likely(!err)) {
751                 up_write(&vol->lcnbmp_lock);
752                 ntfs_debug("Done.");
753                 return rl;
754         }
755         ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
756                         "(error %i).", err);
757         if (rl) {
758                 int err2;
759
760                 if (err == -ENOSPC)
761                         ntfs_debug("Not enough space to complete allocation, "
762                                         "err -ENOSPC, first free lcn 0x%llx, "
763                                         "could allocate up to 0x%llx "
764                                         "clusters.",
765                                         (unsigned long long)rl[0].lcn,
766                                         (unsigned long long)(count - clusters));
767                 /* Deallocate all allocated clusters. */
768                 ntfs_debug("Attempting rollback...");
769                 err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
770                 if (err2) {
771                         ntfs_error(vol->sb, "Failed to rollback (error %i).  "
772                                         "Leaving inconsistent metadata!  "
773                                         "Unmount and run chkdsk.", err2);
774                         NVolSetErrors(vol);
775                 }
776                 /* Free the runlist. */
777                 ntfs_free(rl);
778         } else if (err == -ENOSPC)
779                 ntfs_debug("No space left at all, err = -ENOSPC, first free "
780                                 "lcn = 0x%llx.",
781                                 (long long)vol->data1_zone_pos);
782         up_write(&vol->lcnbmp_lock);
783         return ERR_PTR(err);
784 }
785
786 /**
787  * __ntfs_cluster_free - free clusters on an ntfs volume
788  * @vi:         vfs inode whose runlist describes the clusters to free
789  * @start_vcn:  vcn in the runlist of @vi at which to start freeing clusters
790  * @count:      number of clusters to free or -1 for all clusters
791  * @is_rollback:        if TRUE this is a rollback operation
792  *
793  * Free @count clusters starting at the cluster @start_vcn in the runlist
794  * described by the vfs inode @vi.
795  *
796  * If @count is -1, all clusters from @start_vcn to the end of the runlist are
797  * deallocated.  Thus, to completely free all clusters in a runlist, use
798  * @start_vcn = 0 and @count = -1.
799  *
800  * @is_rollback should always be FALSE, it is for internal use to rollback
801  * errors.  You probably want to use ntfs_cluster_free() instead.
802  *
803  * Note, ntfs_cluster_free() does not modify the runlist at all, so the caller
804  * has to deal with it later.
805  *
806  * Return the number of deallocated clusters (not counting sparse ones) on
807  * success and -errno on error.
808  *
809  * Locking: - The runlist described by @vi must be unlocked on entry and is
810  *            unlocked on return.
811  *          - This function takes the runlist lock of @vi for reading and
812  *            sometimes for writing and sometimes modifies the runlist.
813  *          - The volume lcn bitmap must be unlocked on entry and is unlocked
814  *            on return.
815  *          - This function takes the volume lcn bitmap lock for writing and
816  *            modifies the bitmap contents.
817  */
818 s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
819                 const BOOL is_rollback)
820 {
821         s64 delta, to_free, total_freed, real_freed;
822         ntfs_inode *ni;
823         ntfs_volume *vol;
824         struct inode *lcnbmp_vi;
825         runlist_element *rl;
826         int err;
827
828         BUG_ON(!vi);
829         ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
830                         "0x%llx.%s", vi->i_ino, (unsigned long long)start_vcn,
831                         (unsigned long long)count,
832                         is_rollback ? " (rollback)" : "");
833         ni = NTFS_I(vi);
834         vol = ni->vol;
835         lcnbmp_vi = vol->lcnbmp_ino;
836         BUG_ON(!lcnbmp_vi);
837         BUG_ON(start_vcn < 0);
838         BUG_ON(count < -1);
839         /*
840          * Lock the lcn bitmap for writing but only if not rolling back.  We
841          * must hold the lock all the way including through rollback otherwise
842          * rollback is not possible because once we have cleared a bit and
843          * dropped the lock, anyone could have set the bit again, thus
844          * allocating the cluster for another use.
845          */
846         if (likely(!is_rollback))
847                 down_write(&vol->lcnbmp_lock);
848
849         total_freed = real_freed = 0;
850
851         down_read(&ni->runlist.lock);
852         rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, FALSE);
853         if (IS_ERR(rl)) {
854                 if (!is_rollback)
855                         ntfs_error(vol->sb, "Failed to find first runlist "
856                                         "element (error %li), aborting.",
857                                         PTR_ERR(rl));
858                 err = PTR_ERR(rl);
859                 goto err_out;
860         }
861         if (unlikely(rl->lcn < LCN_HOLE)) {
862                 if (!is_rollback)
863                         ntfs_error(vol->sb, "First runlist element has "
864                                         "invalid lcn, aborting.");
865                 err = -EIO;
866                 goto err_out;
867         }
868         /* Find the starting cluster inside the run that needs freeing. */
869         delta = start_vcn - rl->vcn;
870
871         /* The number of clusters in this run that need freeing. */
872         to_free = rl->length - delta;
873         if (count >= 0 && to_free > count)
874                 to_free = count;
875
876         if (likely(rl->lcn >= 0)) {
877                 /* Do the actual freeing of the clusters in this run. */
878                 err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
879                                 to_free, likely(!is_rollback) ? 0 : 1);
880                 if (unlikely(err)) {
881                         if (!is_rollback)
882                                 ntfs_error(vol->sb, "Failed to clear first run "
883                                                 "(error %i), aborting.", err);
884                         goto err_out;
885                 }
886                 /* We have freed @to_free real clusters. */
887                 real_freed = to_free;
888         };
889         /* Go to the next run and adjust the number of clusters left to free. */
890         ++rl;
891         if (count >= 0)
892                 count -= to_free;
893
894         /* Keep track of the total "freed" clusters, including sparse ones. */
895         total_freed = to_free;
896         /*
897          * Loop over the remaining runs, using @count as a capping value, and
898          * free them.
899          */
900         for (; rl->length && count != 0; ++rl) {
901                 if (unlikely(rl->lcn < LCN_HOLE)) {
902                         VCN vcn;
903
904                         /* Attempt to map runlist. */
905                         vcn = rl->vcn;
906                         rl = ntfs_attr_find_vcn_nolock(ni, vcn, FALSE);
907                         if (IS_ERR(rl)) {
908                                 err = PTR_ERR(rl);
909                                 if (!is_rollback)
910                                         ntfs_error(vol->sb, "Failed to map "
911                                                         "runlist fragment or "
912                                                         "failed to find "
913                                                         "subsequent runlist "
914                                                         "element.");
915                                 goto err_out;
916                         }
917                         if (unlikely(rl->lcn < LCN_HOLE)) {
918                                 if (!is_rollback)
919                                         ntfs_error(vol->sb, "Runlist element "
920                                                         "has invalid lcn "
921                                                         "(0x%llx).",
922                                                         (unsigned long long)
923                                                         rl->lcn);
924                                 err = -EIO;
925                                 goto err_out;
926                         }
927                 }
928                 /* The number of clusters in this run that need freeing. */
929                 to_free = rl->length;
930                 if (count >= 0 && to_free > count)
931                         to_free = count;
932
933                 if (likely(rl->lcn >= 0)) {
934                         /* Do the actual freeing of the clusters in the run. */
935                         err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
936                                         to_free, likely(!is_rollback) ? 0 : 1);
937                         if (unlikely(err)) {
938                                 if (!is_rollback)
939                                         ntfs_error(vol->sb, "Failed to clear "
940                                                         "subsequent run.");
941                                 goto err_out;
942                         }
943                         /* We have freed @to_free real clusters. */
944                         real_freed += to_free;
945                 }
946                 /* Adjust the number of clusters left to free. */
947                 if (count >= 0)
948                         count -= to_free;
949         
950                 /* Update the total done clusters. */
951                 total_freed += to_free;
952         }
953         up_read(&ni->runlist.lock);
954         if (likely(!is_rollback))
955                 up_write(&vol->lcnbmp_lock);
956
957         BUG_ON(count > 0);
958
959         /* We are done.  Return the number of actually freed clusters. */
960         ntfs_debug("Done.");
961         return real_freed;
962 err_out:
963         up_read(&ni->runlist.lock);
964         if (is_rollback)
965                 return err;
966         /* If no real clusters were freed, no need to rollback. */
967         if (!real_freed) {
968                 up_write(&vol->lcnbmp_lock);
969                 return err;
970         }
971         /*
972          * Attempt to rollback and if that succeeds just return the error code.
973          * If rollback fails, set the volume errors flag, emit an error
974          * message, and return the error code.
975          */
976         delta = __ntfs_cluster_free(vi, start_vcn, total_freed, TRUE);
977         if (delta < 0) {
978                 ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
979                                 "inconsistent metadata!  Unmount and run "
980                                 "chkdsk.", (int)delta);
981                 NVolSetErrors(vol);
982         }
983         up_write(&vol->lcnbmp_lock);
984         ntfs_error(vol->sb, "Aborting (error %i).", err);
985         return err;
986 }
987
988 #endif /* NTFS_RW */