Automatic merge of rsync://rsync.kernel.org/pub/scm/linux/kernel/git/shaggy/jfs-2...
[sfrench/cifs-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 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         struct inode *lcnbmp_vi;
144         runlist_element *rl = NULL;
145         struct address_space *mapping;
146         struct page *page = NULL;
147         u8 *buf, *byte;
148         int err = 0, rlpos, rlsize, buf_size;
149         u8 pass, done_zones, search_zone, need_writeback = 0, bit;
150
151         ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
152                         "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
153                         (unsigned long long)count,
154                         (unsigned long long)start_lcn,
155                         zone == MFT_ZONE ? "MFT" : "DATA");
156         BUG_ON(!vol);
157         lcnbmp_vi = vol->lcnbmp_ino;
158         BUG_ON(!lcnbmp_vi);
159         BUG_ON(start_vcn < 0);
160         BUG_ON(count < 0);
161         BUG_ON(start_lcn < -1);
162         BUG_ON(zone < FIRST_ZONE);
163         BUG_ON(zone > LAST_ZONE);
164
165         /* Return empty runlist if @count == 0 */
166         // FIXME: Do we want to just return NULL instead? (AIA)
167         if (!count) {
168                 rl = ntfs_malloc_nofs(PAGE_SIZE);
169                 if (!rl)
170                         return ERR_PTR(-ENOMEM);
171                 rl[0].vcn = start_vcn;
172                 rl[0].lcn = LCN_RL_NOT_MAPPED;
173                 rl[0].length = 0;
174                 return rl;
175         }
176         /* Take the lcnbmp lock for writing. */
177         down_write(&vol->lcnbmp_lock);
178         /*
179          * If no specific @start_lcn was requested, use the current data zone
180          * position, otherwise use the requested @start_lcn but make sure it
181          * lies outside the mft zone.  Also set done_zones to 0 (no zones done)
182          * and pass depending on whether we are starting inside a zone (1) or
183          * at the beginning of a zone (2).  If requesting from the MFT_ZONE,
184          * we either start at the current position within the mft zone or at
185          * the specified position.  If the latter is out of bounds then we start
186          * at the beginning of the MFT_ZONE.
187          */
188         done_zones = 0;
189         pass = 1;
190         /*
191          * zone_start and zone_end are the current search range.  search_zone
192          * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
193          * volume) and 4 for data zone 2 (start of volume till start of mft
194          * zone).
195          */
196         zone_start = start_lcn;
197         if (zone_start < 0) {
198                 if (zone == DATA_ZONE)
199                         zone_start = vol->data1_zone_pos;
200                 else
201                         zone_start = vol->mft_zone_pos;
202                 if (!zone_start) {
203                         /*
204                          * Zone starts at beginning of volume which means a
205                          * single pass is sufficient.
206                          */
207                         pass = 2;
208                 }
209         } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
210                         zone_start < vol->mft_zone_end) {
211                 zone_start = vol->mft_zone_end;
212                 /*
213                  * Starting at beginning of data1_zone which means a single
214                  * pass in this zone is sufficient.
215                  */
216                 pass = 2;
217         } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
218                         zone_start >= vol->mft_zone_end)) {
219                 zone_start = vol->mft_lcn;
220                 if (!vol->mft_zone_end)
221                         zone_start = 0;
222                 /*
223                  * Starting at beginning of volume which means a single pass
224                  * is sufficient.
225                  */
226                 pass = 2;
227         }
228         if (zone == MFT_ZONE) {
229                 zone_end = vol->mft_zone_end;
230                 search_zone = 1;
231         } else /* if (zone == DATA_ZONE) */ {
232                 /* Skip searching the mft zone. */
233                 done_zones |= 1;
234                 if (zone_start >= vol->mft_zone_end) {
235                         zone_end = vol->nr_clusters;
236                         search_zone = 2;
237                 } else {
238                         zone_end = vol->mft_zone_start;
239                         search_zone = 4;
240                 }
241         }
242         /*
243          * bmp_pos is the current bit position inside the bitmap.  We use
244          * bmp_initial_pos to determine whether or not to do a zone switch.
245          */
246         bmp_pos = bmp_initial_pos = zone_start;
247
248         /* Loop until all clusters are allocated, i.e. clusters == 0. */
249         clusters = count;
250         rlpos = rlsize = 0;
251         mapping = lcnbmp_vi->i_mapping;
252         while (1) {
253                 ntfs_debug("Start of outer while loop: done_zones 0x%x, "
254                                 "search_zone %i, pass %i, zone_start 0x%llx, "
255                                 "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
256                                 "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
257                                 done_zones, search_zone, pass,
258                                 (unsigned long long)zone_start,
259                                 (unsigned long long)zone_end,
260                                 (unsigned long long)bmp_initial_pos,
261                                 (unsigned long long)bmp_pos, rlpos, rlsize);
262                 /* Loop until we run out of free clusters. */
263                 last_read_pos = bmp_pos >> 3;
264                 ntfs_debug("last_read_pos 0x%llx.",
265                                 (unsigned long long)last_read_pos);
266                 if (last_read_pos > lcnbmp_vi->i_size) {
267                         ntfs_debug("End of attribute reached.  "
268                                         "Skipping to zone_pass_done.");
269                         goto zone_pass_done;
270                 }
271                 if (likely(page)) {
272                         if (need_writeback) {
273                                 ntfs_debug("Marking page dirty.");
274                                 flush_dcache_page(page);
275                                 set_page_dirty(page);
276                                 need_writeback = 0;
277                         }
278                         ntfs_unmap_page(page);
279                 }
280                 page = ntfs_map_page(mapping, last_read_pos >>
281                                 PAGE_CACHE_SHIFT);
282                 if (IS_ERR(page)) {
283                         err = PTR_ERR(page);
284                         ntfs_error(vol->sb, "Failed to map page.");
285                         goto out;
286                 }
287                 buf_size = last_read_pos & ~PAGE_CACHE_MASK;
288                 buf = page_address(page) + buf_size;
289                 buf_size = PAGE_CACHE_SIZE - buf_size;
290                 if (unlikely(last_read_pos + buf_size > lcnbmp_vi->i_size))
291                         buf_size = lcnbmp_vi->i_size - last_read_pos;
292                 buf_size <<= 3;
293                 lcn = bmp_pos & 7;
294                 bmp_pos &= ~7;
295                 ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
296                                 "bmp_pos 0x%llx, need_writeback %i.", buf_size,
297                                 (unsigned long long)lcn,
298                                 (unsigned long long)bmp_pos, need_writeback);
299                 while (lcn < buf_size && lcn + bmp_pos < zone_end) {
300                         byte = buf + (lcn >> 3);
301                         ntfs_debug("In inner while loop: buf_size %i, "
302                                         "lcn 0x%llx, bmp_pos 0x%llx, "
303                                         "need_writeback %i, byte ofs 0x%x, "
304                                         "*byte 0x%x.", buf_size,
305                                         (unsigned long long)lcn,
306                                         (unsigned long long)bmp_pos,
307                                         need_writeback,
308                                         (unsigned int)(lcn >> 3),
309                                         (unsigned int)*byte);
310                         /* Skip full bytes. */
311                         if (*byte == 0xff) {
312                                 lcn = (lcn + 8) & ~7;
313                                 ntfs_debug("Continuing while loop 1.");
314                                 continue;
315                         }
316                         bit = 1 << (lcn & 7);
317                         ntfs_debug("bit %i.", bit);
318                         /* If the bit is already set, go onto the next one. */
319                         if (*byte & bit) {
320                                 lcn++;
321                                 ntfs_debug("Continuing while loop 2.");
322                                 continue;
323                         }
324                         /*
325                          * Allocate more memory if needed, including space for
326                          * the terminator element.
327                          * ntfs_malloc_nofs() operates on whole pages only.
328                          */
329                         if ((rlpos + 2) * sizeof(*rl) > rlsize) {
330                                 runlist_element *rl2;
331
332                                 ntfs_debug("Reallocating memory.");
333                                 if (!rl)
334                                         ntfs_debug("First free bit is at LCN "
335                                                         "0x%llx.",
336                                                         (unsigned long long)
337                                                         (lcn + bmp_pos));
338                                 rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
339                                 if (unlikely(!rl2)) {
340                                         err = -ENOMEM;
341                                         ntfs_error(vol->sb, "Failed to "
342                                                         "allocate memory.");
343                                         goto out;
344                                 }
345                                 memcpy(rl2, rl, rlsize);
346                                 ntfs_free(rl);
347                                 rl = rl2;
348                                 rlsize += PAGE_SIZE;
349                                 ntfs_debug("Reallocated memory, rlsize 0x%x.",
350                                                 rlsize);
351                         }
352                         /* Allocate the bitmap bit. */
353                         *byte |= bit;
354                         /* We need to write this bitmap page to disk. */
355                         need_writeback = 1;
356                         ntfs_debug("*byte 0x%x, need_writeback is set.",
357                                         (unsigned int)*byte);
358                         /*
359                          * Coalesce with previous run if adjacent LCNs.
360                          * Otherwise, append a new run.
361                          */
362                         ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
363                                         "prev_lcn 0x%llx, lcn 0x%llx, "
364                                         "bmp_pos 0x%llx, prev_run_len 0x%llx, "
365                                         "rlpos %i.",
366                                         (unsigned long long)(lcn + bmp_pos),
367                                         1ULL, (unsigned long long)prev_lcn,
368                                         (unsigned long long)lcn,
369                                         (unsigned long long)bmp_pos,
370                                         (unsigned long long)prev_run_len,
371                                         rlpos);
372                         if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
373                                 ntfs_debug("Coalescing to run (lcn 0x%llx, "
374                                                 "len 0x%llx).",
375                                                 (unsigned long long)
376                                                 rl[rlpos - 1].lcn,
377                                                 (unsigned long long)
378                                                 rl[rlpos - 1].length);
379                                 rl[rlpos - 1].length = ++prev_run_len;
380                                 ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
381                                                 "prev_run_len 0x%llx.",
382                                                 (unsigned long long)
383                                                 rl[rlpos - 1].lcn,
384                                                 (unsigned long long)
385                                                 rl[rlpos - 1].length,
386                                                 (unsigned long long)
387                                                 prev_run_len);
388                         } else {
389                                 if (likely(rlpos)) {
390                                         ntfs_debug("Adding new run, (previous "
391                                                         "run lcn 0x%llx, "
392                                                         "len 0x%llx).",
393                                                         (unsigned long long)
394                                                         rl[rlpos - 1].lcn,
395                                                         (unsigned long long)
396                                                         rl[rlpos - 1].length);
397                                         rl[rlpos].vcn = rl[rlpos - 1].vcn +
398                                                         prev_run_len;
399                                 } else {
400                                         ntfs_debug("Adding new run, is first "
401                                                         "run.");
402                                         rl[rlpos].vcn = start_vcn;
403                                 }
404                                 rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
405                                 rl[rlpos].length = prev_run_len = 1;
406                                 rlpos++;
407                         }
408                         /* Done? */
409                         if (!--clusters) {
410                                 LCN tc;
411                                 /*
412                                  * Update the current zone position.  Positions
413                                  * of already scanned zones have been updated
414                                  * during the respective zone switches.
415                                  */
416                                 tc = lcn + bmp_pos + 1;
417                                 ntfs_debug("Done. Updating current zone "
418                                                 "position, tc 0x%llx, "
419                                                 "search_zone %i.",
420                                                 (unsigned long long)tc,
421                                                 search_zone);
422                                 switch (search_zone) {
423                                 case 1:
424                                         ntfs_debug("Before checks, "
425                                                         "vol->mft_zone_pos "
426                                                         "0x%llx.",
427                                                         (unsigned long long)
428                                                         vol->mft_zone_pos);
429                                         if (tc >= vol->mft_zone_end) {
430                                                 vol->mft_zone_pos =
431                                                                 vol->mft_lcn;
432                                                 if (!vol->mft_zone_end)
433                                                         vol->mft_zone_pos = 0;
434                                         } else if ((bmp_initial_pos >=
435                                                         vol->mft_zone_pos ||
436                                                         tc > vol->mft_zone_pos)
437                                                         && tc >= vol->mft_lcn)
438                                                 vol->mft_zone_pos = tc;
439                                         ntfs_debug("After checks, "
440                                                         "vol->mft_zone_pos "
441                                                         "0x%llx.",
442                                                         (unsigned long long)
443                                                         vol->mft_zone_pos);
444                                         break;
445                                 case 2:
446                                         ntfs_debug("Before checks, "
447                                                         "vol->data1_zone_pos "
448                                                         "0x%llx.",
449                                                         (unsigned long long)
450                                                         vol->data1_zone_pos);
451                                         if (tc >= vol->nr_clusters)
452                                                 vol->data1_zone_pos =
453                                                              vol->mft_zone_end;
454                                         else if ((bmp_initial_pos >=
455                                                     vol->data1_zone_pos ||
456                                                     tc > vol->data1_zone_pos)
457                                                     && tc >= vol->mft_zone_end)
458                                                 vol->data1_zone_pos = tc;
459                                         ntfs_debug("After checks, "
460                                                         "vol->data1_zone_pos "
461                                                         "0x%llx.",
462                                                         (unsigned long long)
463                                                         vol->data1_zone_pos);
464                                         break;
465                                 case 4:
466                                         ntfs_debug("Before checks, "
467                                                         "vol->data2_zone_pos "
468                                                         "0x%llx.",
469                                                         (unsigned long long)
470                                                         vol->data2_zone_pos);
471                                         if (tc >= vol->mft_zone_start)
472                                                 vol->data2_zone_pos = 0;
473                                         else if (bmp_initial_pos >=
474                                                       vol->data2_zone_pos ||
475                                                       tc > vol->data2_zone_pos)
476                                                 vol->data2_zone_pos = tc;
477                                         ntfs_debug("After checks, "
478                                                         "vol->data2_zone_pos "
479                                                         "0x%llx.",
480                                                         (unsigned long long)
481                                                         vol->data2_zone_pos);
482                                         break;
483                                 default:
484                                         BUG();
485                                 }
486                                 ntfs_debug("Finished.  Going to out.");
487                                 goto out;
488                         }
489                         lcn++;
490                 }
491                 bmp_pos += buf_size;
492                 ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
493                                 "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
494                                 buf_size, (unsigned long long)lcn,
495                                 (unsigned long long)bmp_pos, need_writeback);
496                 if (bmp_pos < zone_end) {
497                         ntfs_debug("Continuing outer while loop, "
498                                         "bmp_pos 0x%llx, zone_end 0x%llx.",
499                                         (unsigned long long)bmp_pos,
500                                         (unsigned long long)zone_end);
501                         continue;
502                 }
503 zone_pass_done: /* Finished with the current zone pass. */
504                 ntfs_debug("At zone_pass_done, pass %i.", pass);
505                 if (pass == 1) {
506                         /*
507                          * Now do pass 2, scanning the first part of the zone
508                          * we omitted in pass 1.
509                          */
510                         pass = 2;
511                         zone_end = zone_start;
512                         switch (search_zone) {
513                         case 1: /* mft_zone */
514                                 zone_start = vol->mft_zone_start;
515                                 break;
516                         case 2: /* data1_zone */
517                                 zone_start = vol->mft_zone_end;
518                                 break;
519                         case 4: /* data2_zone */
520                                 zone_start = 0;
521                                 break;
522                         default:
523                                 BUG();
524                         }
525                         /* Sanity check. */
526                         if (zone_end < zone_start)
527                                 zone_end = zone_start;
528                         bmp_pos = zone_start;
529                         ntfs_debug("Continuing outer while loop, pass 2, "
530                                         "zone_start 0x%llx, zone_end 0x%llx, "
531                                         "bmp_pos 0x%llx.",
532                                         (unsigned long long)zone_start,
533                                         (unsigned long long)zone_end,
534                                         (unsigned long long)bmp_pos);
535                         continue;
536                 } /* pass == 2 */
537 done_zones_check:
538                 ntfs_debug("At done_zones_check, search_zone %i, done_zones "
539                                 "before 0x%x, done_zones after 0x%x.",
540                                 search_zone, done_zones,
541                                 done_zones | search_zone);
542                 done_zones |= search_zone;
543                 if (done_zones < 7) {
544                         ntfs_debug("Switching zone.");
545                         /* Now switch to the next zone we haven't done yet. */
546                         pass = 1;
547                         switch (search_zone) {
548                         case 1:
549                                 ntfs_debug("Switching from mft zone to data1 "
550                                                 "zone.");
551                                 /* Update mft zone position. */
552                                 if (rlpos) {
553                                         LCN tc;
554
555                                         ntfs_debug("Before checks, "
556                                                         "vol->mft_zone_pos "
557                                                         "0x%llx.",
558                                                         (unsigned long long)
559                                                         vol->mft_zone_pos);
560                                         tc = rl[rlpos - 1].lcn +
561                                                         rl[rlpos - 1].length;
562                                         if (tc >= vol->mft_zone_end) {
563                                                 vol->mft_zone_pos =
564                                                                 vol->mft_lcn;
565                                                 if (!vol->mft_zone_end)
566                                                         vol->mft_zone_pos = 0;
567                                         } else if ((bmp_initial_pos >=
568                                                         vol->mft_zone_pos ||
569                                                         tc > vol->mft_zone_pos)
570                                                         && tc >= vol->mft_lcn)
571                                                 vol->mft_zone_pos = tc;
572                                         ntfs_debug("After checks, "
573                                                         "vol->mft_zone_pos "
574                                                         "0x%llx.",
575                                                         (unsigned long long)
576                                                         vol->mft_zone_pos);
577                                 }
578                                 /* Switch from mft zone to data1 zone. */
579 switch_to_data1_zone:           search_zone = 2;
580                                 zone_start = bmp_initial_pos =
581                                                 vol->data1_zone_pos;
582                                 zone_end = vol->nr_clusters;
583                                 if (zone_start == vol->mft_zone_end)
584                                         pass = 2;
585                                 if (zone_start >= zone_end) {
586                                         vol->data1_zone_pos = zone_start =
587                                                         vol->mft_zone_end;
588                                         pass = 2;
589                                 }
590                                 break;
591                         case 2:
592                                 ntfs_debug("Switching from data1 zone to "
593                                                 "data2 zone.");
594                                 /* Update data1 zone position. */
595                                 if (rlpos) {
596                                         LCN tc;
597
598                                         ntfs_debug("Before checks, "
599                                                         "vol->data1_zone_pos "
600                                                         "0x%llx.",
601                                                         (unsigned long long)
602                                                         vol->data1_zone_pos);
603                                         tc = rl[rlpos - 1].lcn +
604                                                         rl[rlpos - 1].length;
605                                         if (tc >= vol->nr_clusters)
606                                                 vol->data1_zone_pos =
607                                                              vol->mft_zone_end;
608                                         else if ((bmp_initial_pos >=
609                                                     vol->data1_zone_pos ||
610                                                     tc > vol->data1_zone_pos)
611                                                     && tc >= vol->mft_zone_end)
612                                                 vol->data1_zone_pos = tc;
613                                         ntfs_debug("After checks, "
614                                                         "vol->data1_zone_pos "
615                                                         "0x%llx.",
616                                                         (unsigned long long)
617                                                         vol->data1_zone_pos);
618                                 }
619                                 /* Switch from data1 zone to data2 zone. */
620                                 search_zone = 4;
621                                 zone_start = bmp_initial_pos =
622                                                 vol->data2_zone_pos;
623                                 zone_end = vol->mft_zone_start;
624                                 if (!zone_start)
625                                         pass = 2;
626                                 if (zone_start >= zone_end) {
627                                         vol->data2_zone_pos = zone_start =
628                                                         bmp_initial_pos = 0;
629                                         pass = 2;
630                                 }
631                                 break;
632                         case 4:
633                                 ntfs_debug("Switching from data2 zone to "
634                                                 "data1 zone.");
635                                 /* Update data2 zone position. */
636                                 if (rlpos) {
637                                         LCN tc;
638
639                                         ntfs_debug("Before checks, "
640                                                         "vol->data2_zone_pos "
641                                                         "0x%llx.",
642                                                         (unsigned long long)
643                                                         vol->data2_zone_pos);
644                                         tc = rl[rlpos - 1].lcn +
645                                                         rl[rlpos - 1].length;
646                                         if (tc >= vol->mft_zone_start)
647                                                 vol->data2_zone_pos = 0;
648                                         else if (bmp_initial_pos >=
649                                                       vol->data2_zone_pos ||
650                                                       tc > vol->data2_zone_pos)
651                                                 vol->data2_zone_pos = tc;
652                                         ntfs_debug("After checks, "
653                                                         "vol->data2_zone_pos "
654                                                         "0x%llx.",
655                                                         (unsigned long long)
656                                                         vol->data2_zone_pos);
657                                 }
658                                 /* Switch from data2 zone to data1 zone. */
659                                 goto switch_to_data1_zone;
660                         default:
661                                 BUG();
662                         }
663                         ntfs_debug("After zone switch, search_zone %i, "
664                                         "pass %i, bmp_initial_pos 0x%llx, "
665                                         "zone_start 0x%llx, zone_end 0x%llx.",
666                                         search_zone, pass,
667                                         (unsigned long long)bmp_initial_pos,
668                                         (unsigned long long)zone_start,
669                                         (unsigned long long)zone_end);
670                         bmp_pos = zone_start;
671                         if (zone_start == zone_end) {
672                                 ntfs_debug("Empty zone, going to "
673                                                 "done_zones_check.");
674                                 /* Empty zone. Don't bother searching it. */
675                                 goto done_zones_check;
676                         }
677                         ntfs_debug("Continuing outer while loop.");
678                         continue;
679                 } /* done_zones == 7 */
680                 ntfs_debug("All zones are finished.");
681                 /*
682                  * All zones are finished!  If DATA_ZONE, shrink mft zone.  If
683                  * MFT_ZONE, we have really run out of space.
684                  */
685                 mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
686                 ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
687                                 "0x%llx, mft_zone_size 0x%llx.",
688                                 (unsigned long long)vol->mft_zone_start,
689                                 (unsigned long long)vol->mft_zone_end,
690                                 (unsigned long long)mft_zone_size);
691                 if (zone == MFT_ZONE || mft_zone_size <= 0) {
692                         ntfs_debug("No free clusters left, going to out.");
693                         /* Really no more space left on device. */
694                         err = ENOSPC;
695                         goto out;
696                 } /* zone == DATA_ZONE && mft_zone_size > 0 */
697                 ntfs_debug("Shrinking mft zone.");
698                 zone_end = vol->mft_zone_end;
699                 mft_zone_size >>= 1;
700                 if (mft_zone_size > 0)
701                         vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
702                 else /* mft zone and data2 zone no longer exist. */
703                         vol->data2_zone_pos = vol->mft_zone_start =
704                                         vol->mft_zone_end = 0;
705                 if (vol->mft_zone_pos >= vol->mft_zone_end) {
706                         vol->mft_zone_pos = vol->mft_lcn;
707                         if (!vol->mft_zone_end)
708                                 vol->mft_zone_pos = 0;
709                 }
710                 bmp_pos = zone_start = bmp_initial_pos =
711                                 vol->data1_zone_pos = vol->mft_zone_end;
712                 search_zone = 2;
713                 pass = 2;
714                 done_zones &= ~2;
715                 ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
716                                 "vol->mft_zone_start 0x%llx, "
717                                 "vol->mft_zone_end 0x%llx, "
718                                 "vol->mft_zone_pos 0x%llx, search_zone 2, "
719                                 "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
720                                 "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
721                                 "continuing outer while loop.",
722                                 (unsigned long long)mft_zone_size,
723                                 (unsigned long long)vol->mft_zone_start,
724                                 (unsigned long long)vol->mft_zone_end,
725                                 (unsigned long long)vol->mft_zone_pos,
726                                 done_zones, (unsigned long long)zone_start,
727                                 (unsigned long long)zone_end,
728                                 (unsigned long long)vol->data1_zone_pos);
729         }
730         ntfs_debug("After outer while loop.");
731 out:
732         ntfs_debug("At out.");
733         /* Add runlist terminator element. */
734         if (likely(rl)) {
735                 rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
736                 rl[rlpos].lcn = LCN_RL_NOT_MAPPED;
737                 rl[rlpos].length = 0;
738         }
739         if (likely(page && !IS_ERR(page))) {
740                 if (need_writeback) {
741                         ntfs_debug("Marking page dirty.");
742                         flush_dcache_page(page);
743                         set_page_dirty(page);
744                         need_writeback = 0;
745                 }
746                 ntfs_unmap_page(page);
747         }
748         if (likely(!err)) {
749                 up_write(&vol->lcnbmp_lock);
750                 ntfs_debug("Done.");
751                 return rl;
752         }
753         ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
754                         "(error %i).", err);
755         if (rl) {
756                 int err2;
757
758                 if (err == ENOSPC)
759                         ntfs_debug("Not enough space to complete allocation, "
760                                         "err ENOSPC, first free lcn 0x%llx, "
761                                         "could allocate up to 0x%llx "
762                                         "clusters.",
763                                         (unsigned long long)rl[0].lcn,
764                                         (unsigned long long)count - clusters);
765                 /* Deallocate all allocated clusters. */
766                 ntfs_debug("Attempting rollback...");
767                 err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
768                 if (err2) {
769                         ntfs_error(vol->sb, "Failed to rollback (error %i).  "
770                                         "Leaving inconsistent metadata!  "
771                                         "Unmount and run chkdsk.", err2);
772                         NVolSetErrors(vol);
773                 }
774                 /* Free the runlist. */
775                 ntfs_free(rl);
776         } else if (err == ENOSPC)
777                 ntfs_debug("No space left at all, err = ENOSPC, "
778                                 "first free lcn = 0x%llx.",
779                                 (unsigned long long)vol->data1_zone_pos);
780         up_write(&vol->lcnbmp_lock);
781         return ERR_PTR(err);
782 }
783
784 /**
785  * __ntfs_cluster_free - free clusters on an ntfs volume
786  * @vi:         vfs inode whose runlist describes the clusters to free
787  * @start_vcn:  vcn in the runlist of @vi at which to start freeing clusters
788  * @count:      number of clusters to free or -1 for all clusters
789  * @is_rollback:        if TRUE this is a rollback operation
790  *
791  * Free @count clusters starting at the cluster @start_vcn in the runlist
792  * described by the vfs inode @vi.
793  *
794  * If @count is -1, all clusters from @start_vcn to the end of the runlist are
795  * deallocated.  Thus, to completely free all clusters in a runlist, use
796  * @start_vcn = 0 and @count = -1.
797  *
798  * @is_rollback should always be FALSE, it is for internal use to rollback
799  * errors.  You probably want to use ntfs_cluster_free() instead.
800  *
801  * Note, ntfs_cluster_free() does not modify the runlist at all, so the caller
802  * has to deal with it later.
803  *
804  * Return the number of deallocated clusters (not counting sparse ones) on
805  * success and -errno on error.
806  *
807  * Locking: - The runlist described by @vi must be unlocked on entry and is
808  *            unlocked on return.
809  *          - This function takes the runlist lock of @vi for reading and
810  *            sometimes for writing and sometimes modifies the runlist.
811  *          - The volume lcn bitmap must be unlocked on entry and is unlocked
812  *            on return.
813  *          - This function takes the volume lcn bitmap lock for writing and
814  *            modifies the bitmap contents.
815  */
816 s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
817                 const BOOL is_rollback)
818 {
819         s64 delta, to_free, total_freed, real_freed;
820         ntfs_inode *ni;
821         ntfs_volume *vol;
822         struct inode *lcnbmp_vi;
823         runlist_element *rl;
824         int err;
825
826         BUG_ON(!vi);
827         ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
828                         "0x%llx.%s", vi->i_ino, (unsigned long long)start_vcn,
829                         (unsigned long long)count,
830                         is_rollback ? " (rollback)" : "");
831         ni = NTFS_I(vi);
832         vol = ni->vol;
833         lcnbmp_vi = vol->lcnbmp_ino;
834         BUG_ON(!lcnbmp_vi);
835         BUG_ON(start_vcn < 0);
836         BUG_ON(count < -1);
837         /*
838          * Lock the lcn bitmap for writing but only if not rolling back.  We
839          * must hold the lock all the way including through rollback otherwise
840          * rollback is not possible because once we have cleared a bit and
841          * dropped the lock, anyone could have set the bit again, thus
842          * allocating the cluster for another use.
843          */
844         if (likely(!is_rollback))
845                 down_write(&vol->lcnbmp_lock);
846
847         total_freed = real_freed = 0;
848
849         /* This returns with ni->runlist locked for reading on success. */
850         rl = ntfs_find_vcn(ni, start_vcn, FALSE);
851         if (IS_ERR(rl)) {
852                 if (!is_rollback)
853                         ntfs_error(vol->sb, "Failed to find first runlist "
854                                         "element (error %li), aborting.",
855                                         PTR_ERR(rl));
856                 err = PTR_ERR(rl);
857                 goto err_out;
858         }
859         if (unlikely(rl->lcn < LCN_HOLE)) {
860                 if (!is_rollback)
861                         ntfs_error(vol->sb, "First runlist element has "
862                                         "invalid lcn, aborting.");
863                 err = -EIO;
864                 goto unl_err_out;
865         }
866         /* Find the starting cluster inside the run that needs freeing. */
867         delta = start_vcn - rl->vcn;
868
869         /* The number of clusters in this run that need freeing. */
870         to_free = rl->length - delta;
871         if (count >= 0 && to_free > count)
872                 to_free = count;
873
874         if (likely(rl->lcn >= 0)) {
875                 /* Do the actual freeing of the clusters in this run. */
876                 err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
877                                 to_free, likely(!is_rollback) ? 0 : 1);
878                 if (unlikely(err)) {
879                         if (!is_rollback)
880                                 ntfs_error(vol->sb, "Failed to clear first run "
881                                                 "(error %i), aborting.", err);
882                         goto unl_err_out;
883                 }
884                 /* We have freed @to_free real clusters. */
885                 real_freed = to_free;
886         };
887         /* Go to the next run and adjust the number of clusters left to free. */
888         ++rl;
889         if (count >= 0)
890                 count -= to_free;
891
892         /* Keep track of the total "freed" clusters, including sparse ones. */
893         total_freed = to_free;
894         /*
895          * Loop over the remaining runs, using @count as a capping value, and
896          * free them.
897          */
898         for (; rl->length && count != 0; ++rl) {
899                 if (unlikely(rl->lcn < LCN_HOLE)) {
900                         VCN vcn;
901
902                         /*
903                          * Attempt to map runlist, dropping runlist lock for
904                          * the duration.
905                          */
906                         vcn = rl->vcn;
907                         up_read(&ni->runlist.lock);
908                         err = ntfs_map_runlist(ni, vcn);
909                         if (err) {
910                                 if (!is_rollback)
911                                         ntfs_error(vol->sb, "Failed to map "
912                                                         "runlist fragment.");
913                                 if (err == -EINVAL || err == -ENOENT)
914                                         err = -EIO;
915                                 goto err_out;
916                         }
917                         /*
918                          * This returns with ni->runlist locked for reading on
919                          * success.
920                          */
921                         rl = ntfs_find_vcn(ni, vcn, FALSE);
922                         if (IS_ERR(rl)) {
923                                 err = PTR_ERR(rl);
924                                 if (!is_rollback)
925                                         ntfs_error(vol->sb, "Failed to find "
926                                                         "subsequent runlist "
927                                                         "element.");
928                                 goto err_out;
929                         }
930                         if (unlikely(rl->lcn < LCN_HOLE)) {
931                                 if (!is_rollback)
932                                         ntfs_error(vol->sb, "Runlist element "
933                                                         "has invalid lcn "
934                                                         "(0x%llx).",
935                                                         (unsigned long long)
936                                                         rl->lcn);
937                                 err = -EIO;
938                                 goto unl_err_out;
939                         }
940                 }
941                 /* The number of clusters in this run that need freeing. */
942                 to_free = rl->length;
943                 if (count >= 0 && to_free > count)
944                         to_free = count;
945
946                 if (likely(rl->lcn >= 0)) {
947                         /* Do the actual freeing of the clusters in the run. */
948                         err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
949                                         to_free, likely(!is_rollback) ? 0 : 1);
950                         if (unlikely(err)) {
951                                 if (!is_rollback)
952                                         ntfs_error(vol->sb, "Failed to clear "
953                                                         "subsequent run.");
954                                 goto unl_err_out;
955                         }
956                         /* We have freed @to_free real clusters. */
957                         real_freed += to_free;
958                 }
959                 /* Adjust the number of clusters left to free. */
960                 if (count >= 0)
961                         count -= to_free;
962         
963                 /* Update the total done clusters. */
964                 total_freed += to_free;
965         }
966         up_read(&ni->runlist.lock);
967         if (likely(!is_rollback))
968                 up_write(&vol->lcnbmp_lock);
969
970         BUG_ON(count > 0);
971
972         /* We are done.  Return the number of actually freed clusters. */
973         ntfs_debug("Done.");
974         return real_freed;
975 unl_err_out:
976         up_read(&ni->runlist.lock);
977 err_out:
978         if (is_rollback)
979                 return err;
980         /* If no real clusters were freed, no need to rollback. */
981         if (!real_freed) {
982                 up_write(&vol->lcnbmp_lock);
983                 return err;
984         }
985         /*
986          * Attempt to rollback and if that succeeds just return the error code.
987          * If rollback fails, set the volume errors flag, emit an error
988          * message, and return the error code.
989          */
990         delta = __ntfs_cluster_free(vi, start_vcn, total_freed, TRUE);
991         if (delta < 0) {
992                 ntfs_error(vol->sb, "Failed to rollback (error %i).  Leaving "
993                                 "inconsistent metadata!  Unmount and run "
994                                 "chkdsk.", (int)delta);
995                 NVolSetErrors(vol);
996         }
997         up_write(&vol->lcnbmp_lock);
998         ntfs_error(vol->sb, "Aborting (error %i).", err);
999         return err;
1000 }
1001
1002 #endif /* NTFS_RW */