Root/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 */
50int 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    if (!rl)
58        return 0;
59    for (; rl->length; rl++) {
60        int err;
61
62        if (rl->lcn < 0)
63            continue;
64        err = ntfs_bitmap_clear_run(lcnbmp_vi, rl->lcn, rl->length);
65        if (unlikely(err && (!ret || ret == -ENOMEM) && ret != err))
66            ret = err;
67    }
68    ntfs_debug("Done.");
69    return ret;
70}
71
72/**
73 * ntfs_cluster_alloc - allocate clusters on an ntfs volume
74 * @vol: mounted ntfs volume on which to allocate the clusters
75 * @start_vcn: vcn to use for the first allocated cluster
76 * @count: number of clusters to allocate
77 * @start_lcn: starting lcn at which to allocate the clusters (or -1 if none)
78 * @zone: zone from which to allocate the clusters
79 * @is_extension: if 'true', this is an attribute extension
80 *
81 * Allocate @count clusters preferably starting at cluster @start_lcn or at the
82 * current allocator position if @start_lcn is -1, on the mounted ntfs volume
83 * @vol. @zone is either DATA_ZONE for allocation of normal clusters or
84 * MFT_ZONE for allocation of clusters for the master file table, i.e. the
85 * $MFT/$DATA attribute.
86 *
87 * @start_vcn specifies the vcn of the first allocated cluster. This makes
88 * merging the resulting runlist with the old runlist easier.
89 *
90 * If @is_extension is 'true', the caller is allocating clusters to extend an
91 * attribute and if it is 'false', the caller is allocating clusters to fill a
92 * hole in an attribute. Practically the difference is that if @is_extension
93 * is 'true' the returned runlist will be terminated with LCN_ENOENT and if
94 * @is_extension is 'false' the runlist will be terminated with
95 * LCN_RL_NOT_MAPPED.
96 *
97 * You need to check the return value with IS_ERR(). If this is false, the
98 * function was successful and the return value is a runlist describing the
99 * allocated cluster(s). If IS_ERR() is true, the function failed and
100 * PTR_ERR() gives you the error code.
101 *
102 * Notes on the allocation algorithm
103 * =================================
104 *
105 * There are two data zones. First is the area between the end of the mft zone
106 * and the end of the volume, and second is the area between the start of the
107 * volume and the start of the mft zone. On unmodified/standard NTFS 1.x
108 * volumes, the second data zone does not exist due to the mft zone being
109 * expanded to cover the start of the volume in order to reserve space for the
110 * mft bitmap attribute.
111 *
112 * This is not the prettiest function but the complexity stems from the need of
113 * implementing the mft vs data zoned approach and from the fact that we have
114 * access to the lcn bitmap in portions of up to 8192 bytes at a time, so we
115 * need to cope with crossing over boundaries of two buffers. Further, the
116 * fact that the allocator allows for caller supplied hints as to the location
117 * of where allocation should begin and the fact that the allocator keeps track
118 * of where in the data zones the next natural allocation should occur,
119 * contribute to the complexity of the function. But it should all be
120 * worthwhile, because this allocator should: 1) be a full implementation of
121 * the MFT zone approach used by Windows NT, 2) cause reduction in
122 * fragmentation, and 3) be speedy in allocations (the code is not optimized
123 * for speed, but the algorithm is, so further speed improvements are probably
124 * possible).
125 *
126 * FIXME: We should be monitoring cluster allocation and increment the MFT zone
127 * size dynamically but this is something for the future. We will just cause
128 * heavier fragmentation by not doing it and I am not even sure Windows would
129 * grow the MFT zone dynamically, so it might even be correct not to do this.
130 * The overhead in doing dynamic MFT zone expansion would be very large and
131 * unlikely worth the effort. (AIA)
132 *
133 * TODO: I have added in double the required zone position pointer wrap around
134 * logic which can be optimized to having only one of the two logic sets.
135 * However, having the double logic will work fine, but if we have only one of
136 * the sets and we get it wrong somewhere, then we get into trouble, so
137 * removing the duplicate logic requires _very_ careful consideration of _all_
138 * possible code paths. So at least for now, I am leaving the double logic -
139 * better safe than sorry... (AIA)
140 *
141 * Locking: - The volume lcn bitmap must be unlocked on entry and is unlocked
142 * on return.
143 * - This function takes the volume lcn bitmap lock for writing and
144 * modifies the bitmap contents.
145 */
146runlist_element *ntfs_cluster_alloc(ntfs_volume *vol, const VCN start_vcn,
147        const s64 count, const LCN start_lcn,
148        const NTFS_CLUSTER_ALLOCATION_ZONES zone,
149        const bool is_extension)
150{
151    LCN zone_start, zone_end, bmp_pos, bmp_initial_pos, last_read_pos, lcn;
152    LCN prev_lcn = 0, prev_run_len = 0, mft_zone_size;
153    s64 clusters;
154    loff_t i_size;
155    struct inode *lcnbmp_vi;
156    runlist_element *rl = NULL;
157    struct address_space *mapping;
158    struct page *page = NULL;
159    u8 *buf, *byte;
160    int err = 0, rlpos, rlsize, buf_size;
161    u8 pass, done_zones, search_zone, need_writeback = 0, bit;
162
163    ntfs_debug("Entering for start_vcn 0x%llx, count 0x%llx, start_lcn "
164            "0x%llx, zone %s_ZONE.", (unsigned long long)start_vcn,
165            (unsigned long long)count,
166            (unsigned long long)start_lcn,
167            zone == MFT_ZONE ? "MFT" : "DATA");
168    BUG_ON(!vol);
169    lcnbmp_vi = vol->lcnbmp_ino;
170    BUG_ON(!lcnbmp_vi);
171    BUG_ON(start_vcn < 0);
172    BUG_ON(count < 0);
173    BUG_ON(start_lcn < -1);
174    BUG_ON(zone < FIRST_ZONE);
175    BUG_ON(zone > LAST_ZONE);
176
177    /* Return NULL if @count is zero. */
178    if (!count)
179        return NULL;
180    /* Take the lcnbmp lock for writing. */
181    down_write(&vol->lcnbmp_lock);
182    /*
183     * If no specific @start_lcn was requested, use the current data zone
184     * position, otherwise use the requested @start_lcn but make sure it
185     * lies outside the mft zone. Also set done_zones to 0 (no zones done)
186     * and pass depending on whether we are starting inside a zone (1) or
187     * at the beginning of a zone (2). If requesting from the MFT_ZONE,
188     * we either start at the current position within the mft zone or at
189     * the specified position. If the latter is out of bounds then we start
190     * at the beginning of the MFT_ZONE.
191     */
192    done_zones = 0;
193    pass = 1;
194    /*
195     * zone_start and zone_end are the current search range. search_zone
196     * is 1 for mft zone, 2 for data zone 1 (end of mft zone till end of
197     * volume) and 4 for data zone 2 (start of volume till start of mft
198     * zone).
199     */
200    zone_start = start_lcn;
201    if (zone_start < 0) {
202        if (zone == DATA_ZONE)
203            zone_start = vol->data1_zone_pos;
204        else
205            zone_start = vol->mft_zone_pos;
206        if (!zone_start) {
207            /*
208             * Zone starts at beginning of volume which means a
209             * single pass is sufficient.
210             */
211            pass = 2;
212        }
213    } else if (zone == DATA_ZONE && zone_start >= vol->mft_zone_start &&
214            zone_start < vol->mft_zone_end) {
215        zone_start = vol->mft_zone_end;
216        /*
217         * Starting at beginning of data1_zone which means a single
218         * pass in this zone is sufficient.
219         */
220        pass = 2;
221    } else if (zone == MFT_ZONE && (zone_start < vol->mft_zone_start ||
222            zone_start >= vol->mft_zone_end)) {
223        zone_start = vol->mft_lcn;
224        if (!vol->mft_zone_end)
225            zone_start = 0;
226        /*
227         * Starting at beginning of volume which means a single pass
228         * is sufficient.
229         */
230        pass = 2;
231    }
232    if (zone == MFT_ZONE) {
233        zone_end = vol->mft_zone_end;
234        search_zone = 1;
235    } else /* if (zone == DATA_ZONE) */ {
236        /* Skip searching the mft zone. */
237        done_zones |= 1;
238        if (zone_start >= vol->mft_zone_end) {
239            zone_end = vol->nr_clusters;
240            search_zone = 2;
241        } else {
242            zone_end = vol->mft_zone_start;
243            search_zone = 4;
244        }
245    }
246    /*
247     * bmp_pos is the current bit position inside the bitmap. We use
248     * bmp_initial_pos to determine whether or not to do a zone switch.
249     */
250    bmp_pos = bmp_initial_pos = zone_start;
251
252    /* Loop until all clusters are allocated, i.e. clusters == 0. */
253    clusters = count;
254    rlpos = rlsize = 0;
255    mapping = lcnbmp_vi->i_mapping;
256    i_size = i_size_read(lcnbmp_vi);
257    while (1) {
258        ntfs_debug("Start of outer while loop: done_zones 0x%x, "
259                "search_zone %i, pass %i, zone_start 0x%llx, "
260                "zone_end 0x%llx, bmp_initial_pos 0x%llx, "
261                "bmp_pos 0x%llx, rlpos %i, rlsize %i.",
262                done_zones, search_zone, pass,
263                (unsigned long long)zone_start,
264                (unsigned long long)zone_end,
265                (unsigned long long)bmp_initial_pos,
266                (unsigned long long)bmp_pos, rlpos, rlsize);
267        /* Loop until we run out of free clusters. */
268        last_read_pos = bmp_pos >> 3;
269        ntfs_debug("last_read_pos 0x%llx.",
270                (unsigned long long)last_read_pos);
271        if (last_read_pos > i_size) {
272            ntfs_debug("End of attribute reached. "
273                    "Skipping to zone_pass_done.");
274            goto zone_pass_done;
275        }
276        if (likely(page)) {
277            if (need_writeback) {
278                ntfs_debug("Marking page dirty.");
279                flush_dcache_page(page);
280                set_page_dirty(page);
281                need_writeback = 0;
282            }
283            ntfs_unmap_page(page);
284        }
285        page = ntfs_map_page(mapping, last_read_pos >>
286                PAGE_CACHE_SHIFT);
287        if (IS_ERR(page)) {
288            err = PTR_ERR(page);
289            ntfs_error(vol->sb, "Failed to map page.");
290            goto out;
291        }
292        buf_size = last_read_pos & ~PAGE_CACHE_MASK;
293        buf = page_address(page) + buf_size;
294        buf_size = PAGE_CACHE_SIZE - buf_size;
295        if (unlikely(last_read_pos + buf_size > i_size))
296            buf_size = i_size - last_read_pos;
297        buf_size <<= 3;
298        lcn = bmp_pos & 7;
299        bmp_pos &= ~(LCN)7;
300        ntfs_debug("Before inner while loop: buf_size %i, lcn 0x%llx, "
301                "bmp_pos 0x%llx, need_writeback %i.", buf_size,
302                (unsigned long long)lcn,
303                (unsigned long long)bmp_pos, need_writeback);
304        while (lcn < buf_size && lcn + bmp_pos < zone_end) {
305            byte = buf + (lcn >> 3);
306            ntfs_debug("In inner while loop: buf_size %i, "
307                    "lcn 0x%llx, bmp_pos 0x%llx, "
308                    "need_writeback %i, byte ofs 0x%x, "
309                    "*byte 0x%x.", buf_size,
310                    (unsigned long long)lcn,
311                    (unsigned long long)bmp_pos,
312                    need_writeback,
313                    (unsigned int)(lcn >> 3),
314                    (unsigned int)*byte);
315            /* Skip full bytes. */
316            if (*byte == 0xff) {
317                lcn = (lcn + 8) & ~(LCN)7;
318                ntfs_debug("Continuing while loop 1.");
319                continue;
320            }
321            bit = 1 << (lcn & 7);
322            ntfs_debug("bit 0x%x.", bit);
323            /* If the bit is already set, go onto the next one. */
324            if (*byte & bit) {
325                lcn++;
326                ntfs_debug("Continuing while loop 2.");
327                continue;
328            }
329            /*
330             * Allocate more memory if needed, including space for
331             * the terminator element.
332             * ntfs_malloc_nofs() operates on whole pages only.
333             */
334            if ((rlpos + 2) * sizeof(*rl) > rlsize) {
335                runlist_element *rl2;
336
337                ntfs_debug("Reallocating memory.");
338                if (!rl)
339                    ntfs_debug("First free bit is at LCN "
340                            "0x%llx.",
341                            (unsigned long long)
342                            (lcn + bmp_pos));
343                rl2 = ntfs_malloc_nofs(rlsize + (int)PAGE_SIZE);
344                if (unlikely(!rl2)) {
345                    err = -ENOMEM;
346                    ntfs_error(vol->sb, "Failed to "
347                            "allocate memory.");
348                    goto out;
349                }
350                memcpy(rl2, rl, rlsize);
351                ntfs_free(rl);
352                rl = rl2;
353                rlsize += PAGE_SIZE;
354                ntfs_debug("Reallocated memory, rlsize 0x%x.",
355                        rlsize);
356            }
357            /* Allocate the bitmap bit. */
358            *byte |= bit;
359            /* We need to write this bitmap page to disk. */
360            need_writeback = 1;
361            ntfs_debug("*byte 0x%x, need_writeback is set.",
362                    (unsigned int)*byte);
363            /*
364             * Coalesce with previous run if adjacent LCNs.
365             * Otherwise, append a new run.
366             */
367            ntfs_debug("Adding run (lcn 0x%llx, len 0x%llx), "
368                    "prev_lcn 0x%llx, lcn 0x%llx, "
369                    "bmp_pos 0x%llx, prev_run_len 0x%llx, "
370                    "rlpos %i.",
371                    (unsigned long long)(lcn + bmp_pos),
372                    1ULL, (unsigned long long)prev_lcn,
373                    (unsigned long long)lcn,
374                    (unsigned long long)bmp_pos,
375                    (unsigned long long)prev_run_len,
376                    rlpos);
377            if (prev_lcn == lcn + bmp_pos - prev_run_len && rlpos) {
378                ntfs_debug("Coalescing to run (lcn 0x%llx, "
379                        "len 0x%llx).",
380                        (unsigned long long)
381                        rl[rlpos - 1].lcn,
382                        (unsigned long long)
383                        rl[rlpos - 1].length);
384                rl[rlpos - 1].length = ++prev_run_len;
385                ntfs_debug("Run now (lcn 0x%llx, len 0x%llx), "
386                        "prev_run_len 0x%llx.",
387                        (unsigned long long)
388                        rl[rlpos - 1].lcn,
389                        (unsigned long long)
390                        rl[rlpos - 1].length,
391                        (unsigned long long)
392                        prev_run_len);
393            } else {
394                if (likely(rlpos)) {
395                    ntfs_debug("Adding new run, (previous "
396                            "run lcn 0x%llx, "
397                            "len 0x%llx).",
398                            (unsigned long long)
399                            rl[rlpos - 1].lcn,
400                            (unsigned long long)
401                            rl[rlpos - 1].length);
402                    rl[rlpos].vcn = rl[rlpos - 1].vcn +
403                            prev_run_len;
404                } else {
405                    ntfs_debug("Adding new run, is first "
406                            "run.");
407                    rl[rlpos].vcn = start_vcn;
408                }
409                rl[rlpos].lcn = prev_lcn = lcn + bmp_pos;
410                rl[rlpos].length = prev_run_len = 1;
411                rlpos++;
412            }
413            /* Done? */
414            if (!--clusters) {
415                LCN tc;
416                /*
417                 * Update the current zone position. Positions
418                 * of already scanned zones have been updated
419                 * during the respective zone switches.
420                 */
421                tc = lcn + bmp_pos + 1;
422                ntfs_debug("Done. Updating current zone "
423                        "position, tc 0x%llx, "
424                        "search_zone %i.",
425                        (unsigned long long)tc,
426                        search_zone);
427                switch (search_zone) {
428                case 1:
429                    ntfs_debug("Before checks, "
430                            "vol->mft_zone_pos "
431                            "0x%llx.",
432                            (unsigned long long)
433                            vol->mft_zone_pos);
434                    if (tc >= vol->mft_zone_end) {
435                        vol->mft_zone_pos =
436                                vol->mft_lcn;
437                        if (!vol->mft_zone_end)
438                            vol->mft_zone_pos = 0;
439                    } else if ((bmp_initial_pos >=
440                            vol->mft_zone_pos ||
441                            tc > vol->mft_zone_pos)
442                            && tc >= vol->mft_lcn)
443                        vol->mft_zone_pos = tc;
444                    ntfs_debug("After checks, "
445                            "vol->mft_zone_pos "
446                            "0x%llx.",
447                            (unsigned long long)
448                            vol->mft_zone_pos);
449                    break;
450                case 2:
451                    ntfs_debug("Before checks, "
452                            "vol->data1_zone_pos "
453                            "0x%llx.",
454                            (unsigned long long)
455                            vol->data1_zone_pos);
456                    if (tc >= vol->nr_clusters)
457                        vol->data1_zone_pos =
458                                 vol->mft_zone_end;
459                    else if ((bmp_initial_pos >=
460                            vol->data1_zone_pos ||
461                            tc > vol->data1_zone_pos)
462                            && tc >= vol->mft_zone_end)
463                        vol->data1_zone_pos = tc;
464                    ntfs_debug("After checks, "
465                            "vol->data1_zone_pos "
466                            "0x%llx.",
467                            (unsigned long long)
468                            vol->data1_zone_pos);
469                    break;
470                case 4:
471                    ntfs_debug("Before checks, "
472                            "vol->data2_zone_pos "
473                            "0x%llx.",
474                            (unsigned long long)
475                            vol->data2_zone_pos);
476                    if (tc >= vol->mft_zone_start)
477                        vol->data2_zone_pos = 0;
478                    else if (bmp_initial_pos >=
479                              vol->data2_zone_pos ||
480                              tc > vol->data2_zone_pos)
481                        vol->data2_zone_pos = tc;
482                    ntfs_debug("After checks, "
483                            "vol->data2_zone_pos "
484                            "0x%llx.",
485                            (unsigned long long)
486                            vol->data2_zone_pos);
487                    break;
488                default:
489                    BUG();
490                }
491                ntfs_debug("Finished. Going to out.");
492                goto out;
493            }
494            lcn++;
495        }
496        bmp_pos += buf_size;
497        ntfs_debug("After inner while loop: buf_size 0x%x, lcn "
498                "0x%llx, bmp_pos 0x%llx, need_writeback %i.",
499                buf_size, (unsigned long long)lcn,
500                (unsigned long long)bmp_pos, need_writeback);
501        if (bmp_pos < zone_end) {
502            ntfs_debug("Continuing outer while loop, "
503                    "bmp_pos 0x%llx, zone_end 0x%llx.",
504                    (unsigned long long)bmp_pos,
505                    (unsigned long long)zone_end);
506            continue;
507        }
508zone_pass_done: /* Finished with the current zone pass. */
509        ntfs_debug("At zone_pass_done, pass %i.", pass);
510        if (pass == 1) {
511            /*
512             * Now do pass 2, scanning the first part of the zone
513             * we omitted in pass 1.
514             */
515            pass = 2;
516            zone_end = zone_start;
517            switch (search_zone) {
518            case 1: /* mft_zone */
519                zone_start = vol->mft_zone_start;
520                break;
521            case 2: /* data1_zone */
522                zone_start = vol->mft_zone_end;
523                break;
524            case 4: /* data2_zone */
525                zone_start = 0;
526                break;
527            default:
528                BUG();
529            }
530            /* Sanity check. */
531            if (zone_end < zone_start)
532                zone_end = zone_start;
533            bmp_pos = zone_start;
534            ntfs_debug("Continuing outer while loop, pass 2, "
535                    "zone_start 0x%llx, zone_end 0x%llx, "
536                    "bmp_pos 0x%llx.",
537                    (unsigned long long)zone_start,
538                    (unsigned long long)zone_end,
539                    (unsigned long long)bmp_pos);
540            continue;
541        } /* pass == 2 */
542done_zones_check:
543        ntfs_debug("At done_zones_check, search_zone %i, done_zones "
544                "before 0x%x, done_zones after 0x%x.",
545                search_zone, done_zones,
546                done_zones | search_zone);
547        done_zones |= search_zone;
548        if (done_zones < 7) {
549            ntfs_debug("Switching zone.");
550            /* Now switch to the next zone we haven't done yet. */
551            pass = 1;
552            switch (search_zone) {
553            case 1:
554                ntfs_debug("Switching from mft zone to data1 "
555                        "zone.");
556                /* Update mft zone position. */
557                if (rlpos) {
558                    LCN tc;
559
560                    ntfs_debug("Before checks, "
561                            "vol->mft_zone_pos "
562                            "0x%llx.",
563                            (unsigned long long)
564                            vol->mft_zone_pos);
565                    tc = rl[rlpos - 1].lcn +
566                            rl[rlpos - 1].length;
567                    if (tc >= vol->mft_zone_end) {
568                        vol->mft_zone_pos =
569                                vol->mft_lcn;
570                        if (!vol->mft_zone_end)
571                            vol->mft_zone_pos = 0;
572                    } else if ((bmp_initial_pos >=
573                            vol->mft_zone_pos ||
574                            tc > vol->mft_zone_pos)
575                            && tc >= vol->mft_lcn)
576                        vol->mft_zone_pos = tc;
577                    ntfs_debug("After checks, "
578                            "vol->mft_zone_pos "
579                            "0x%llx.",
580                            (unsigned long long)
581                            vol->mft_zone_pos);
582                }
583                /* Switch from mft zone to data1 zone. */
584switch_to_data1_zone: search_zone = 2;
585                zone_start = bmp_initial_pos =
586                        vol->data1_zone_pos;
587                zone_end = vol->nr_clusters;
588                if (zone_start == vol->mft_zone_end)
589                    pass = 2;
590                if (zone_start >= zone_end) {
591                    vol->data1_zone_pos = zone_start =
592                            vol->mft_zone_end;
593                    pass = 2;
594                }
595                break;
596            case 2:
597                ntfs_debug("Switching from data1 zone to "
598                        "data2 zone.");
599                /* Update data1 zone position. */
600                if (rlpos) {
601                    LCN tc;
602
603                    ntfs_debug("Before checks, "
604                            "vol->data1_zone_pos "
605                            "0x%llx.",
606                            (unsigned long long)
607                            vol->data1_zone_pos);
608                    tc = rl[rlpos - 1].lcn +
609                            rl[rlpos - 1].length;
610                    if (tc >= vol->nr_clusters)
611                        vol->data1_zone_pos =
612                                 vol->mft_zone_end;
613                    else if ((bmp_initial_pos >=
614                            vol->data1_zone_pos ||
615                            tc > vol->data1_zone_pos)
616                            && tc >= vol->mft_zone_end)
617                        vol->data1_zone_pos = tc;
618                    ntfs_debug("After checks, "
619                            "vol->data1_zone_pos "
620                            "0x%llx.",
621                            (unsigned long long)
622                            vol->data1_zone_pos);
623                }
624                /* Switch from data1 zone to data2 zone. */
625                search_zone = 4;
626                zone_start = bmp_initial_pos =
627                        vol->data2_zone_pos;
628                zone_end = vol->mft_zone_start;
629                if (!zone_start)
630                    pass = 2;
631                if (zone_start >= zone_end) {
632                    vol->data2_zone_pos = zone_start =
633                            bmp_initial_pos = 0;
634                    pass = 2;
635                }
636                break;
637            case 4:
638                ntfs_debug("Switching from data2 zone to "
639                        "data1 zone.");
640                /* Update data2 zone position. */
641                if (rlpos) {
642                    LCN tc;
643
644                    ntfs_debug("Before checks, "
645                            "vol->data2_zone_pos "
646                            "0x%llx.",
647                            (unsigned long long)
648                            vol->data2_zone_pos);
649                    tc = rl[rlpos - 1].lcn +
650                            rl[rlpos - 1].length;
651                    if (tc >= vol->mft_zone_start)
652                        vol->data2_zone_pos = 0;
653                    else if (bmp_initial_pos >=
654                              vol->data2_zone_pos ||
655                              tc > vol->data2_zone_pos)
656                        vol->data2_zone_pos = tc;
657                    ntfs_debug("After checks, "
658                            "vol->data2_zone_pos "
659                            "0x%llx.",
660                            (unsigned long long)
661                            vol->data2_zone_pos);
662                }
663                /* Switch from data2 zone to data1 zone. */
664                goto switch_to_data1_zone;
665            default:
666                BUG();
667            }
668            ntfs_debug("After zone switch, search_zone %i, "
669                    "pass %i, bmp_initial_pos 0x%llx, "
670                    "zone_start 0x%llx, zone_end 0x%llx.",
671                    search_zone, pass,
672                    (unsigned long long)bmp_initial_pos,
673                    (unsigned long long)zone_start,
674                    (unsigned long long)zone_end);
675            bmp_pos = zone_start;
676            if (zone_start == zone_end) {
677                ntfs_debug("Empty zone, going to "
678                        "done_zones_check.");
679                /* Empty zone. Don't bother searching it. */
680                goto done_zones_check;
681            }
682            ntfs_debug("Continuing outer while loop.");
683            continue;
684        } /* done_zones == 7 */
685        ntfs_debug("All zones are finished.");
686        /*
687         * All zones are finished! If DATA_ZONE, shrink mft zone. If
688         * MFT_ZONE, we have really run out of space.
689         */
690        mft_zone_size = vol->mft_zone_end - vol->mft_zone_start;
691        ntfs_debug("vol->mft_zone_start 0x%llx, vol->mft_zone_end "
692                "0x%llx, mft_zone_size 0x%llx.",
693                (unsigned long long)vol->mft_zone_start,
694                (unsigned long long)vol->mft_zone_end,
695                (unsigned long long)mft_zone_size);
696        if (zone == MFT_ZONE || mft_zone_size <= 0) {
697            ntfs_debug("No free clusters left, going to out.");
698            /* Really no more space left on device. */
699            err = -ENOSPC;
700            goto out;
701        } /* zone == DATA_ZONE && mft_zone_size > 0 */
702        ntfs_debug("Shrinking mft zone.");
703        zone_end = vol->mft_zone_end;
704        mft_zone_size >>= 1;
705        if (mft_zone_size > 0)
706            vol->mft_zone_end = vol->mft_zone_start + mft_zone_size;
707        else /* mft zone and data2 zone no longer exist. */
708            vol->data2_zone_pos = vol->mft_zone_start =
709                    vol->mft_zone_end = 0;
710        if (vol->mft_zone_pos >= vol->mft_zone_end) {
711            vol->mft_zone_pos = vol->mft_lcn;
712            if (!vol->mft_zone_end)
713                vol->mft_zone_pos = 0;
714        }
715        bmp_pos = zone_start = bmp_initial_pos =
716                vol->data1_zone_pos = vol->mft_zone_end;
717        search_zone = 2;
718        pass = 2;
719        done_zones &= ~2;
720        ntfs_debug("After shrinking mft zone, mft_zone_size 0x%llx, "
721                "vol->mft_zone_start 0x%llx, "
722                "vol->mft_zone_end 0x%llx, "
723                "vol->mft_zone_pos 0x%llx, search_zone 2, "
724                "pass 2, dones_zones 0x%x, zone_start 0x%llx, "
725                "zone_end 0x%llx, vol->data1_zone_pos 0x%llx, "
726                "continuing outer while loop.",
727                (unsigned long long)mft_zone_size,
728                (unsigned long long)vol->mft_zone_start,
729                (unsigned long long)vol->mft_zone_end,
730                (unsigned long long)vol->mft_zone_pos,
731                done_zones, (unsigned long long)zone_start,
732                (unsigned long long)zone_end,
733                (unsigned long long)vol->data1_zone_pos);
734    }
735    ntfs_debug("After outer while loop.");
736out:
737    ntfs_debug("At out.");
738    /* Add runlist terminator element. */
739    if (likely(rl)) {
740        rl[rlpos].vcn = rl[rlpos - 1].vcn + rl[rlpos - 1].length;
741        rl[rlpos].lcn = is_extension ? LCN_ENOENT : LCN_RL_NOT_MAPPED;
742        rl[rlpos].length = 0;
743    }
744    if (likely(page && !IS_ERR(page))) {
745        if (need_writeback) {
746            ntfs_debug("Marking page dirty.");
747            flush_dcache_page(page);
748            set_page_dirty(page);
749            need_writeback = 0;
750        }
751        ntfs_unmap_page(page);
752    }
753    if (likely(!err)) {
754        up_write(&vol->lcnbmp_lock);
755        ntfs_debug("Done.");
756        return rl;
757    }
758    ntfs_error(vol->sb, "Failed to allocate clusters, aborting "
759            "(error %i).", err);
760    if (rl) {
761        int err2;
762
763        if (err == -ENOSPC)
764            ntfs_debug("Not enough space to complete allocation, "
765                    "err -ENOSPC, first free lcn 0x%llx, "
766                    "could allocate up to 0x%llx "
767                    "clusters.",
768                    (unsigned long long)rl[0].lcn,
769                    (unsigned long long)(count - clusters));
770        /* Deallocate all allocated clusters. */
771        ntfs_debug("Attempting rollback...");
772        err2 = ntfs_cluster_free_from_rl_nolock(vol, rl);
773        if (err2) {
774            ntfs_error(vol->sb, "Failed to rollback (error %i). "
775                    "Leaving inconsistent metadata! "
776                    "Unmount and run chkdsk.", err2);
777            NVolSetErrors(vol);
778        }
779        /* Free the runlist. */
780        ntfs_free(rl);
781    } else if (err == -ENOSPC)
782        ntfs_debug("No space left at all, err = -ENOSPC, first free "
783                "lcn = 0x%llx.",
784                (long long)vol->data1_zone_pos);
785    up_write(&vol->lcnbmp_lock);
786    return ERR_PTR(err);
787}
788
789/**
790 * __ntfs_cluster_free - free clusters on an ntfs volume
791 * @ni: ntfs inode whose runlist describes the clusters to free
792 * @start_vcn: vcn in the runlist of @ni at which to start freeing clusters
793 * @count: number of clusters to free or -1 for all clusters
794 * @ctx: active attribute search context if present or NULL if not
795 * @is_rollback: true if this is a rollback operation
796 *
797 * Free @count clusters starting at the cluster @start_vcn in the runlist
798 * described by the vfs inode @ni.
799 *
800 * If @count is -1, all clusters from @start_vcn to the end of the runlist are
801 * deallocated. Thus, to completely free all clusters in a runlist, use
802 * @start_vcn = 0 and @count = -1.
803 *
804 * If @ctx is specified, it is an active search context of @ni and its base mft
805 * record. This is needed when __ntfs_cluster_free() encounters unmapped
806 * runlist fragments and allows their mapping. If you do not have the mft
807 * record mapped, you can specify @ctx as NULL and __ntfs_cluster_free() will
808 * perform the necessary mapping and unmapping.
809 *
810 * Note, __ntfs_cluster_free() saves the state of @ctx on entry and restores it
811 * before returning. Thus, @ctx will be left pointing to the same attribute on
812 * return as on entry. However, the actual pointers in @ctx may point to
813 * different memory locations on return, so you must remember to reset any
814 * cached pointers from the @ctx, i.e. after the call to __ntfs_cluster_free(),
815 * you will probably want to do:
816 * m = ctx->mrec;
817 * a = ctx->attr;
818 * Assuming you cache ctx->attr in a variable @a of type ATTR_RECORD * and that
819 * you cache ctx->mrec in a variable @m of type MFT_RECORD *.
820 *
821 * @is_rollback should always be 'false', it is for internal use to rollback
822 * errors. You probably want to use ntfs_cluster_free() instead.
823 *
824 * Note, __ntfs_cluster_free() does not modify the runlist, so you have to
825 * remove from the runlist or mark sparse the freed runs later.
826 *
827 * Return the number of deallocated clusters (not counting sparse ones) on
828 * success and -errno on error.
829 *
830 * WARNING: If @ctx is supplied, regardless of whether success or failure is
831 * returned, you need to check IS_ERR(@ctx->mrec) and if 'true' the @ctx
832 * is no longer valid, i.e. you need to either call
833 * ntfs_attr_reinit_search_ctx() or ntfs_attr_put_search_ctx() on it.
834 * In that case PTR_ERR(@ctx->mrec) will give you the error code for
835 * why the mapping of the old inode failed.
836 *
837 * Locking: - The runlist described by @ni must be locked for writing on entry
838 * and is locked on return. Note the runlist may be modified when
839 * needed runlist fragments need to be mapped.
840 * - The volume lcn bitmap must be unlocked on entry and is unlocked
841 * on return.
842 * - This function takes the volume lcn bitmap lock for writing and
843 * modifies the bitmap contents.
844 * - If @ctx is NULL, the base mft record of @ni must not be mapped on
845 * entry and it will be left unmapped on return.
846 * - If @ctx is not NULL, the base mft record must be mapped on entry
847 * and it will be left mapped on return.
848 */
849s64 __ntfs_cluster_free(ntfs_inode *ni, const VCN start_vcn, s64 count,
850        ntfs_attr_search_ctx *ctx, const bool is_rollback)
851{
852    s64 delta, to_free, total_freed, real_freed;
853    ntfs_volume *vol;
854    struct inode *lcnbmp_vi;
855    runlist_element *rl;
856    int err;
857
858    BUG_ON(!ni);
859    ntfs_debug("Entering for i_ino 0x%lx, start_vcn 0x%llx, count "
860            "0x%llx.%s", ni->mft_no, (unsigned long long)start_vcn,
861            (unsigned long long)count,
862            is_rollback ? " (rollback)" : "");
863    vol = ni->vol;
864    lcnbmp_vi = vol->lcnbmp_ino;
865    BUG_ON(!lcnbmp_vi);
866    BUG_ON(start_vcn < 0);
867    BUG_ON(count < -1);
868    /*
869     * Lock the lcn bitmap for writing but only if not rolling back. We
870     * must hold the lock all the way including through rollback otherwise
871     * rollback is not possible because once we have cleared a bit and
872     * dropped the lock, anyone could have set the bit again, thus
873     * allocating the cluster for another use.
874     */
875    if (likely(!is_rollback))
876        down_write(&vol->lcnbmp_lock);
877
878    total_freed = real_freed = 0;
879
880    rl = ntfs_attr_find_vcn_nolock(ni, start_vcn, ctx);
881    if (IS_ERR(rl)) {
882        if (!is_rollback)
883            ntfs_error(vol->sb, "Failed to find first runlist "
884                    "element (error %li), aborting.",
885                    PTR_ERR(rl));
886        err = PTR_ERR(rl);
887        goto err_out;
888    }
889    if (unlikely(rl->lcn < LCN_HOLE)) {
890        if (!is_rollback)
891            ntfs_error(vol->sb, "First runlist element has "
892                    "invalid lcn, aborting.");
893        err = -EIO;
894        goto err_out;
895    }
896    /* Find the starting cluster inside the run that needs freeing. */
897    delta = start_vcn - rl->vcn;
898
899    /* The number of clusters in this run that need freeing. */
900    to_free = rl->length - delta;
901    if (count >= 0 && to_free > count)
902        to_free = count;
903
904    if (likely(rl->lcn >= 0)) {
905        /* Do the actual freeing of the clusters in this run. */
906        err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn + delta,
907                to_free, likely(!is_rollback) ? 0 : 1);
908        if (unlikely(err)) {
909            if (!is_rollback)
910                ntfs_error(vol->sb, "Failed to clear first run "
911                        "(error %i), aborting.", err);
912            goto err_out;
913        }
914        /* We have freed @to_free real clusters. */
915        real_freed = to_free;
916    };
917    /* Go to the next run and adjust the number of clusters left to free. */
918    ++rl;
919    if (count >= 0)
920        count -= to_free;
921
922    /* Keep track of the total "freed" clusters, including sparse ones. */
923    total_freed = to_free;
924    /*
925     * Loop over the remaining runs, using @count as a capping value, and
926     * free them.
927     */
928    for (; rl->length && count != 0; ++rl) {
929        if (unlikely(rl->lcn < LCN_HOLE)) {
930            VCN vcn;
931
932            /* Attempt to map runlist. */
933            vcn = rl->vcn;
934            rl = ntfs_attr_find_vcn_nolock(ni, vcn, ctx);
935            if (IS_ERR(rl)) {
936                err = PTR_ERR(rl);
937                if (!is_rollback)
938                    ntfs_error(vol->sb, "Failed to map "
939                            "runlist fragment or "
940                            "failed to find "
941                            "subsequent runlist "
942                            "element.");
943                goto err_out;
944            }
945            if (unlikely(rl->lcn < LCN_HOLE)) {
946                if (!is_rollback)
947                    ntfs_error(vol->sb, "Runlist element "
948                            "has invalid lcn "
949                            "(0x%llx).",
950                            (unsigned long long)
951                            rl->lcn);
952                err = -EIO;
953                goto err_out;
954            }
955        }
956        /* The number of clusters in this run that need freeing. */
957        to_free = rl->length;
958        if (count >= 0 && to_free > count)
959            to_free = count;
960
961        if (likely(rl->lcn >= 0)) {
962            /* Do the actual freeing of the clusters in the run. */
963            err = ntfs_bitmap_set_bits_in_run(lcnbmp_vi, rl->lcn,
964                    to_free, likely(!is_rollback) ? 0 : 1);
965            if (unlikely(err)) {
966                if (!is_rollback)
967                    ntfs_error(vol->sb, "Failed to clear "
968                            "subsequent run.");
969                goto err_out;
970            }
971            /* We have freed @to_free real clusters. */
972            real_freed += to_free;
973        }
974        /* Adjust the number of clusters left to free. */
975        if (count >= 0)
976            count -= to_free;
977    
978        /* Update the total done clusters. */
979        total_freed += to_free;
980    }
981    if (likely(!is_rollback))
982        up_write(&vol->lcnbmp_lock);
983
984    BUG_ON(count > 0);
985
986    /* We are done. Return the number of actually freed clusters. */
987    ntfs_debug("Done.");
988    return real_freed;
989err_out:
990    if (is_rollback)
991        return err;
992    /* If no real clusters were freed, no need to rollback. */
993    if (!real_freed) {
994        up_write(&vol->lcnbmp_lock);
995        return err;
996    }
997    /*
998     * Attempt to rollback and if that succeeds just return the error code.
999     * If rollback fails, set the volume errors flag, emit an error
1000     * message, and return the error code.
1001     */
1002    delta = __ntfs_cluster_free(ni, start_vcn, total_freed, ctx, true);
1003    if (delta < 0) {
1004        ntfs_error(vol->sb, "Failed to rollback (error %i). Leaving "
1005                "inconsistent metadata! Unmount and run "
1006                "chkdsk.", (int)delta);
1007        NVolSetErrors(vol);
1008    }
1009    up_write(&vol->lcnbmp_lock);
1010    ntfs_error(vol->sb, "Aborting (error %i).", err);
1011    return err;
1012}
1013
1014#endif /* NTFS_RW */
1015

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