Root/fs/ocfs2/reservations.c

1/* -*- mode: c; c-basic-offset: 8; -*-
2 * vim: noexpandtab sw=8 ts=8 sts=0:
3 *
4 * reservations.c
5 *
6 * Allocation reservations implementation
7 *
8 * Some code borrowed from fs/ext3/balloc.c and is:
9 *
10 * Copyright (C) 1992, 1993, 1994, 1995
11 * Remy Card (card@masi.ibp.fr)
12 * Laboratoire MASI - Institut Blaise Pascal
13 * Universite Pierre et Marie Curie (Paris VI)
14 *
15 * The rest is copyright (C) 2010 Novell. All rights reserved.
16 *
17 * This program is free software; you can redistribute it and/or
18 * modify it under the terms of the GNU General Public
19 * License version 2 as published by the Free Software Foundation.
20 *
21 * This program is distributed in the hope that it will be useful,
22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
24 * General Public License for more details.
25 */
26
27#include <linux/fs.h>
28#include <linux/types.h>
29#include <linux/highmem.h>
30#include <linux/bitops.h>
31#include <linux/list.h>
32
33#include <cluster/masklog.h>
34
35#include "ocfs2.h"
36#include "ocfs2_trace.h"
37
38#ifdef CONFIG_OCFS2_DEBUG_FS
39#define OCFS2_CHECK_RESERVATIONS
40#endif
41
42DEFINE_SPINLOCK(resv_lock);
43
44#define OCFS2_MIN_RESV_WINDOW_BITS 8
45#define OCFS2_MAX_RESV_WINDOW_BITS 1024
46
47int ocfs2_dir_resv_allowed(struct ocfs2_super *osb)
48{
49    return (osb->osb_resv_level && osb->osb_dir_resv_level);
50}
51
52static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap,
53                       struct ocfs2_alloc_reservation *resv)
54{
55    struct ocfs2_super *osb = resmap->m_osb;
56    unsigned int bits;
57
58    if (!(resv->r_flags & OCFS2_RESV_FLAG_DIR)) {
59        /* 8, 16, 32, 64, 128, 256, 512, 1024 */
60        bits = 4 << osb->osb_resv_level;
61    } else {
62        bits = 4 << osb->osb_dir_resv_level;
63    }
64    return bits;
65}
66
67static inline unsigned int ocfs2_resv_end(struct ocfs2_alloc_reservation *resv)
68{
69    if (resv->r_len)
70        return resv->r_start + resv->r_len - 1;
71    return resv->r_start;
72}
73
74static inline int ocfs2_resv_empty(struct ocfs2_alloc_reservation *resv)
75{
76    return !!(resv->r_len == 0);
77}
78
79static inline int ocfs2_resmap_disabled(struct ocfs2_reservation_map *resmap)
80{
81    if (resmap->m_osb->osb_resv_level == 0)
82        return 1;
83    return 0;
84}
85
86static void ocfs2_dump_resv(struct ocfs2_reservation_map *resmap)
87{
88    struct ocfs2_super *osb = resmap->m_osb;
89    struct rb_node *node;
90    struct ocfs2_alloc_reservation *resv;
91    int i = 0;
92
93    mlog(ML_NOTICE, "Dumping resmap for device %s. Bitmap length: %u\n",
94         osb->dev_str, resmap->m_bitmap_len);
95
96    node = rb_first(&resmap->m_reservations);
97    while (node) {
98        resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
99
100        mlog(ML_NOTICE, "start: %u\tend: %u\tlen: %u\tlast_start: %u"
101             "\tlast_len: %u\n", resv->r_start,
102             ocfs2_resv_end(resv), resv->r_len, resv->r_last_start,
103             resv->r_last_len);
104
105        node = rb_next(node);
106        i++;
107    }
108
109    mlog(ML_NOTICE, "%d reservations found. LRU follows\n", i);
110
111    i = 0;
112    list_for_each_entry(resv, &resmap->m_lru, r_lru) {
113        mlog(ML_NOTICE, "LRU(%d) start: %u\tend: %u\tlen: %u\t"
114             "last_start: %u\tlast_len: %u\n", i, resv->r_start,
115             ocfs2_resv_end(resv), resv->r_len, resv->r_last_start,
116             resv->r_last_len);
117
118        i++;
119    }
120}
121
122#ifdef OCFS2_CHECK_RESERVATIONS
123static int ocfs2_validate_resmap_bits(struct ocfs2_reservation_map *resmap,
124                      int i,
125                      struct ocfs2_alloc_reservation *resv)
126{
127    char *disk_bitmap = resmap->m_disk_bitmap;
128    unsigned int start = resv->r_start;
129    unsigned int end = ocfs2_resv_end(resv);
130
131    while (start <= end) {
132        if (ocfs2_test_bit(start, disk_bitmap)) {
133            mlog(ML_ERROR,
134                 "reservation %d covers an allocated area "
135                 "starting at bit %u!\n", i, start);
136            return 1;
137        }
138
139        start++;
140    }
141    return 0;
142}
143
144static void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap)
145{
146    unsigned int off = 0;
147    int i = 0;
148    struct rb_node *node;
149    struct ocfs2_alloc_reservation *resv;
150
151    node = rb_first(&resmap->m_reservations);
152    while (node) {
153        resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
154
155        if (i > 0 && resv->r_start <= off) {
156            mlog(ML_ERROR, "reservation %d has bad start off!\n",
157                 i);
158            goto bad;
159        }
160
161        if (resv->r_len == 0) {
162            mlog(ML_ERROR, "reservation %d has no length!\n",
163                 i);
164            goto bad;
165        }
166
167        if (resv->r_start > ocfs2_resv_end(resv)) {
168            mlog(ML_ERROR, "reservation %d has invalid range!\n",
169                 i);
170            goto bad;
171        }
172
173        if (ocfs2_resv_end(resv) >= resmap->m_bitmap_len) {
174            mlog(ML_ERROR, "reservation %d extends past bitmap!\n",
175                 i);
176            goto bad;
177        }
178
179        if (ocfs2_validate_resmap_bits(resmap, i, resv))
180            goto bad;
181
182        off = ocfs2_resv_end(resv);
183        node = rb_next(node);
184
185        i++;
186    }
187    return;
188
189bad:
190    ocfs2_dump_resv(resmap);
191    BUG();
192}
193#else
194static inline void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap)
195{
196
197}
198#endif
199
200void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv)
201{
202    memset(resv, 0, sizeof(*resv));
203    INIT_LIST_HEAD(&resv->r_lru);
204}
205
206void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
207             unsigned int flags)
208{
209    BUG_ON(flags & ~OCFS2_RESV_TYPES);
210
211    resv->r_flags |= flags;
212}
213
214int ocfs2_resmap_init(struct ocfs2_super *osb,
215              struct ocfs2_reservation_map *resmap)
216{
217    memset(resmap, 0, sizeof(*resmap));
218
219    resmap->m_osb = osb;
220    resmap->m_reservations = RB_ROOT;
221    /* m_bitmap_len is initialized to zero by the above memset. */
222    INIT_LIST_HEAD(&resmap->m_lru);
223
224    return 0;
225}
226
227static void ocfs2_resv_mark_lru(struct ocfs2_reservation_map *resmap,
228                struct ocfs2_alloc_reservation *resv)
229{
230    assert_spin_locked(&resv_lock);
231
232    if (!list_empty(&resv->r_lru))
233        list_del_init(&resv->r_lru);
234
235    list_add_tail(&resv->r_lru, &resmap->m_lru);
236}
237
238static void __ocfs2_resv_trunc(struct ocfs2_alloc_reservation *resv)
239{
240    resv->r_len = 0;
241    resv->r_start = 0;
242}
243
244static void ocfs2_resv_remove(struct ocfs2_reservation_map *resmap,
245                  struct ocfs2_alloc_reservation *resv)
246{
247    if (resv->r_flags & OCFS2_RESV_FLAG_INUSE) {
248        list_del_init(&resv->r_lru);
249        rb_erase(&resv->r_node, &resmap->m_reservations);
250        resv->r_flags &= ~OCFS2_RESV_FLAG_INUSE;
251    }
252}
253
254static void __ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
255                 struct ocfs2_alloc_reservation *resv)
256{
257    assert_spin_locked(&resv_lock);
258
259    __ocfs2_resv_trunc(resv);
260    /*
261     * last_len and last_start no longer make sense if
262     * we're changing the range of our allocations.
263     */
264    resv->r_last_len = resv->r_last_start = 0;
265
266    ocfs2_resv_remove(resmap, resv);
267}
268
269/* does nothing if 'resv' is null */
270void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap,
271            struct ocfs2_alloc_reservation *resv)
272{
273    if (resv) {
274        spin_lock(&resv_lock);
275        __ocfs2_resv_discard(resmap, resv);
276        spin_unlock(&resv_lock);
277    }
278}
279
280static void ocfs2_resmap_clear_all_resv(struct ocfs2_reservation_map *resmap)
281{
282    struct rb_node *node;
283    struct ocfs2_alloc_reservation *resv;
284
285    assert_spin_locked(&resv_lock);
286
287    while ((node = rb_last(&resmap->m_reservations)) != NULL) {
288        resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
289
290        __ocfs2_resv_discard(resmap, resv);
291    }
292}
293
294void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap,
295              unsigned int clen, char *disk_bitmap)
296{
297    if (ocfs2_resmap_disabled(resmap))
298        return;
299
300    spin_lock(&resv_lock);
301
302    ocfs2_resmap_clear_all_resv(resmap);
303    resmap->m_bitmap_len = clen;
304    resmap->m_disk_bitmap = disk_bitmap;
305
306    spin_unlock(&resv_lock);
307}
308
309void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap)
310{
311    /* Does nothing for now. Keep this around for API symmetry */
312}
313
314static void ocfs2_resv_insert(struct ocfs2_reservation_map *resmap,
315                  struct ocfs2_alloc_reservation *new)
316{
317    struct rb_root *root = &resmap->m_reservations;
318    struct rb_node *parent = NULL;
319    struct rb_node **p = &root->rb_node;
320    struct ocfs2_alloc_reservation *tmp;
321
322    assert_spin_locked(&resv_lock);
323
324    trace_ocfs2_resv_insert(new->r_start, new->r_len);
325
326    while (*p) {
327        parent = *p;
328
329        tmp = rb_entry(parent, struct ocfs2_alloc_reservation, r_node);
330
331        if (new->r_start < tmp->r_start) {
332            p = &(*p)->rb_left;
333
334            /*
335             * This is a good place to check for
336             * overlapping reservations.
337             */
338            BUG_ON(ocfs2_resv_end(new) >= tmp->r_start);
339        } else if (new->r_start > ocfs2_resv_end(tmp)) {
340            p = &(*p)->rb_right;
341        } else {
342            /* This should never happen! */
343            mlog(ML_ERROR, "Duplicate reservation window!\n");
344            BUG();
345        }
346    }
347
348    rb_link_node(&new->r_node, parent, p);
349    rb_insert_color(&new->r_node, root);
350    new->r_flags |= OCFS2_RESV_FLAG_INUSE;
351
352    ocfs2_resv_mark_lru(resmap, new);
353
354    ocfs2_check_resmap(resmap);
355}
356
357/**
358 * ocfs2_find_resv_lhs() - find the window which contains goal
359 * @resmap: reservation map to search
360 * @goal: which bit to search for
361 *
362 * If a window containing that goal is not found, we return the window
363 * which comes before goal. Returns NULL on empty rbtree or no window
364 * before goal.
365 */
366static struct ocfs2_alloc_reservation *
367ocfs2_find_resv_lhs(struct ocfs2_reservation_map *resmap, unsigned int goal)
368{
369    struct ocfs2_alloc_reservation *resv = NULL;
370    struct ocfs2_alloc_reservation *prev_resv = NULL;
371    struct rb_node *node = resmap->m_reservations.rb_node;
372
373    assert_spin_locked(&resv_lock);
374
375    if (!node)
376        return NULL;
377
378    node = rb_first(&resmap->m_reservations);
379    while (node) {
380        resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node);
381
382        if (resv->r_start <= goal && ocfs2_resv_end(resv) >= goal)
383            break;
384
385        /* Check if we overshot the reservation just before goal? */
386        if (resv->r_start > goal) {
387            resv = prev_resv;
388            break;
389        }
390
391        prev_resv = resv;
392        node = rb_next(node);
393    }
394
395    return resv;
396}
397
398/*
399 * We are given a range within the bitmap, which corresponds to a gap
400 * inside the reservations tree (search_start, search_len). The range
401 * can be anything from the whole bitmap, to a gap between
402 * reservations.
403 *
404 * The start value of *rstart is insignificant.
405 *
406 * This function searches the bitmap range starting at search_start
407 * with length search_len for a set of contiguous free bits. We try
408 * to find up to 'wanted' bits, but can sometimes return less.
409 *
410 * Returns the length of allocation, 0 if no free bits are found.
411 *
412 * *cstart and *clen will also be populated with the result.
413 */
414static int ocfs2_resmap_find_free_bits(struct ocfs2_reservation_map *resmap,
415                       unsigned int wanted,
416                       unsigned int search_start,
417                       unsigned int search_len,
418                       unsigned int *rstart,
419                       unsigned int *rlen)
420{
421    void *bitmap = resmap->m_disk_bitmap;
422    unsigned int best_start, best_len = 0;
423    int offset, start, found;
424
425    trace_ocfs2_resmap_find_free_bits_begin(search_start, search_len,
426                        wanted, resmap->m_bitmap_len);
427
428    found = best_start = best_len = 0;
429
430    start = search_start;
431    while ((offset = ocfs2_find_next_zero_bit(bitmap, resmap->m_bitmap_len,
432                         start)) != -1) {
433        /* Search reached end of the region */
434        if (offset >= (search_start + search_len))
435            break;
436
437        if (offset == start) {
438            /* we found a zero */
439            found++;
440            /* move start to the next bit to test */
441            start++;
442        } else {
443            /* got a zero after some ones */
444            found = 1;
445            start = offset + 1;
446        }
447        if (found > best_len) {
448            best_len = found;
449            best_start = start - found;
450        }
451
452        if (found >= wanted)
453            break;
454    }
455
456    if (best_len == 0)
457        return 0;
458
459    if (best_len >= wanted)
460        best_len = wanted;
461
462    *rlen = best_len;
463    *rstart = best_start;
464
465    trace_ocfs2_resmap_find_free_bits_end(best_start, best_len);
466
467    return *rlen;
468}
469
470static void __ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap,
471                     struct ocfs2_alloc_reservation *resv,
472                     unsigned int goal, unsigned int wanted)
473{
474    struct rb_root *root = &resmap->m_reservations;
475    unsigned int gap_start, gap_end, gap_len;
476    struct ocfs2_alloc_reservation *prev_resv, *next_resv;
477    struct rb_node *prev, *next;
478    unsigned int cstart, clen;
479    unsigned int best_start = 0, best_len = 0;
480
481    /*
482     * Nasty cases to consider:
483     *
484     * - rbtree is empty
485     * - our window should be first in all reservations
486     * - our window should be last in all reservations
487     * - need to make sure we don't go past end of bitmap
488     */
489    trace_ocfs2_resv_find_window_begin(resv->r_start, ocfs2_resv_end(resv),
490                       goal, wanted, RB_EMPTY_ROOT(root));
491
492    assert_spin_locked(&resv_lock);
493
494    if (RB_EMPTY_ROOT(root)) {
495        /*
496         * Easiest case - empty tree. We can just take
497         * whatever window of free bits we want.
498         */
499        clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal,
500                           resmap->m_bitmap_len - goal,
501                           &cstart, &clen);
502
503        /*
504         * This should never happen - the local alloc window
505         * will always have free bits when we're called.
506         */
507        BUG_ON(goal == 0 && clen == 0);
508
509        if (clen == 0)
510            return;
511
512        resv->r_start = cstart;
513        resv->r_len = clen;
514
515        ocfs2_resv_insert(resmap, resv);
516        return;
517    }
518
519    prev_resv = ocfs2_find_resv_lhs(resmap, goal);
520
521    if (prev_resv == NULL) {
522        /*
523         * A NULL here means that the search code couldn't
524         * find a window that starts before goal.
525         *
526         * However, we can take the first window after goal,
527         * which is also by definition, the leftmost window in
528         * the entire tree. If we can find free bits in the
529         * gap between goal and the LHS window, then the
530         * reservation can safely be placed there.
531         *
532         * Otherwise we fall back to a linear search, checking
533         * the gaps in between windows for a place to
534         * allocate.
535         */
536
537        next = rb_first(root);
538        next_resv = rb_entry(next, struct ocfs2_alloc_reservation,
539                     r_node);
540
541        /*
542         * The search should never return such a window. (see
543         * comment above
544         */
545        if (next_resv->r_start <= goal) {
546            mlog(ML_ERROR, "goal: %u next_resv: start %u len %u\n",
547                 goal, next_resv->r_start, next_resv->r_len);
548            ocfs2_dump_resv(resmap);
549            BUG();
550        }
551
552        clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal,
553                           next_resv->r_start - goal,
554                           &cstart, &clen);
555        if (clen) {
556            best_len = clen;
557            best_start = cstart;
558            if (best_len == wanted)
559                goto out_insert;
560        }
561
562        prev_resv = next_resv;
563        next_resv = NULL;
564    }
565
566    trace_ocfs2_resv_find_window_prev(prev_resv->r_start,
567                      ocfs2_resv_end(prev_resv));
568
569    prev = &prev_resv->r_node;
570
571    /* Now we do a linear search for a window, starting at 'prev_rsv' */
572    while (1) {
573        next = rb_next(prev);
574        if (next) {
575            next_resv = rb_entry(next,
576                         struct ocfs2_alloc_reservation,
577                         r_node);
578
579            gap_start = ocfs2_resv_end(prev_resv) + 1;
580            gap_end = next_resv->r_start - 1;
581            gap_len = gap_end - gap_start + 1;
582        } else {
583            /*
584             * We're at the rightmost edge of the
585             * tree. See if a reservation between this
586             * window and the end of the bitmap will work.
587             */
588            gap_start = ocfs2_resv_end(prev_resv) + 1;
589            gap_len = resmap->m_bitmap_len - gap_start;
590            gap_end = resmap->m_bitmap_len - 1;
591        }
592
593        trace_ocfs2_resv_find_window_next(next ? next_resv->r_start: -1,
594                    next ? ocfs2_resv_end(next_resv) : -1);
595        /*
596         * No need to check this gap if we have already found
597         * a larger region of free bits.
598         */
599        if (gap_len <= best_len)
600            goto next_resv;
601
602        clen = ocfs2_resmap_find_free_bits(resmap, wanted, gap_start,
603                           gap_len, &cstart, &clen);
604        if (clen == wanted) {
605            best_len = clen;
606            best_start = cstart;
607            goto out_insert;
608        } else if (clen > best_len) {
609            best_len = clen;
610            best_start = cstart;
611        }
612
613next_resv:
614        if (!next)
615            break;
616
617        prev = next;
618        prev_resv = rb_entry(prev, struct ocfs2_alloc_reservation,
619                     r_node);
620    }
621
622out_insert:
623    if (best_len) {
624        resv->r_start = best_start;
625        resv->r_len = best_len;
626        ocfs2_resv_insert(resmap, resv);
627    }
628}
629
630static void ocfs2_cannibalize_resv(struct ocfs2_reservation_map *resmap,
631                   struct ocfs2_alloc_reservation *resv,
632                   unsigned int wanted)
633{
634    struct ocfs2_alloc_reservation *lru_resv;
635    int tmpwindow = !!(resv->r_flags & OCFS2_RESV_FLAG_TMP);
636    unsigned int min_bits;
637
638    if (!tmpwindow)
639        min_bits = ocfs2_resv_window_bits(resmap, resv) >> 1;
640    else
641        min_bits = wanted; /* We at know the temp window will use all
642                    * of these bits */
643
644    /*
645     * Take the first reservation off the LRU as our 'target'. We
646     * don't try to be smart about it. There might be a case for
647     * searching based on size but I don't have enough data to be
648     * sure. --Mark (3/16/2010)
649     */
650    lru_resv = list_first_entry(&resmap->m_lru,
651                    struct ocfs2_alloc_reservation, r_lru);
652
653    trace_ocfs2_cannibalize_resv_begin(lru_resv->r_start,
654                       lru_resv->r_len,
655                       ocfs2_resv_end(lru_resv));
656
657    /*
658     * Cannibalize (some or all) of the target reservation and
659     * feed it to the current window.
660     */
661    if (lru_resv->r_len <= min_bits) {
662        /*
663         * Discard completely if size is less than or equal to a
664         * reasonable threshold - 50% of window bits for non temporary
665         * windows.
666         */
667        resv->r_start = lru_resv->r_start;
668        resv->r_len = lru_resv->r_len;
669
670        __ocfs2_resv_discard(resmap, lru_resv);
671    } else {
672        unsigned int shrink;
673        if (tmpwindow)
674            shrink = min_bits;
675        else
676            shrink = lru_resv->r_len / 2;
677
678        lru_resv->r_len -= shrink;
679
680        resv->r_start = ocfs2_resv_end(lru_resv) + 1;
681        resv->r_len = shrink;
682    }
683
684    trace_ocfs2_cannibalize_resv_end(resv->r_start, ocfs2_resv_end(resv),
685                     resv->r_len, resv->r_last_start,
686                     resv->r_last_len);
687
688    ocfs2_resv_insert(resmap, resv);
689}
690
691static void ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap,
692                   struct ocfs2_alloc_reservation *resv,
693                   unsigned int wanted)
694{
695    unsigned int goal = 0;
696
697    BUG_ON(!ocfs2_resv_empty(resv));
698
699    /*
700     * Begin by trying to get a window as close to the previous
701     * one as possible. Using the most recent allocation as a
702     * start goal makes sense.
703     */
704    if (resv->r_last_len) {
705        goal = resv->r_last_start + resv->r_last_len;
706        if (goal >= resmap->m_bitmap_len)
707            goal = 0;
708    }
709
710    __ocfs2_resv_find_window(resmap, resv, goal, wanted);
711
712    /* Search from last alloc didn't work, try once more from beginning. */
713    if (ocfs2_resv_empty(resv) && goal != 0)
714        __ocfs2_resv_find_window(resmap, resv, 0, wanted);
715
716    if (ocfs2_resv_empty(resv)) {
717        /*
718         * Still empty? Pull oldest one off the LRU, remove it from
719         * tree, put this one in it's place.
720         */
721        ocfs2_cannibalize_resv(resmap, resv, wanted);
722    }
723
724    BUG_ON(ocfs2_resv_empty(resv));
725}
726
727int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap,
728               struct ocfs2_alloc_reservation *resv,
729               int *cstart, int *clen)
730{
731    if (resv == NULL || ocfs2_resmap_disabled(resmap))
732        return -ENOSPC;
733
734    spin_lock(&resv_lock);
735
736    if (ocfs2_resv_empty(resv)) {
737        /*
738         * We don't want to over-allocate for temporary
739         * windows. Otherwise, we run the risk of fragmenting the
740         * allocation space.
741         */
742        unsigned int wanted = ocfs2_resv_window_bits(resmap, resv);
743
744        if ((resv->r_flags & OCFS2_RESV_FLAG_TMP) || wanted < *clen)
745            wanted = *clen;
746
747        /*
748         * Try to get a window here. If it works, we must fall
749         * through and test the bitmap . This avoids some
750         * ping-ponging of windows due to non-reserved space
751         * being allocation before we initialize a window for
752         * that inode.
753         */
754        ocfs2_resv_find_window(resmap, resv, wanted);
755        trace_ocfs2_resmap_resv_bits(resv->r_start, resv->r_len);
756    }
757
758    BUG_ON(ocfs2_resv_empty(resv));
759
760    *cstart = resv->r_start;
761    *clen = resv->r_len;
762
763    spin_unlock(&resv_lock);
764    return 0;
765}
766
767static void
768    ocfs2_adjust_resv_from_alloc(struct ocfs2_reservation_map *resmap,
769                     struct ocfs2_alloc_reservation *resv,
770                     unsigned int start, unsigned int end)
771{
772    unsigned int rhs = 0;
773    unsigned int old_end = ocfs2_resv_end(resv);
774
775    BUG_ON(start != resv->r_start || old_end < end);
776
777    /*
778     * Completely used? We can remove it then.
779     */
780    if (old_end == end) {
781        __ocfs2_resv_discard(resmap, resv);
782        return;
783    }
784
785    rhs = old_end - end;
786
787    /*
788     * This should have been trapped above.
789     */
790    BUG_ON(rhs == 0);
791
792    resv->r_start = end + 1;
793    resv->r_len = old_end - resv->r_start + 1;
794}
795
796void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap,
797                   struct ocfs2_alloc_reservation *resv,
798                   u32 cstart, u32 clen)
799{
800    unsigned int cend = cstart + clen - 1;
801
802    if (resmap == NULL || ocfs2_resmap_disabled(resmap))
803        return;
804
805    if (resv == NULL)
806        return;
807
808    BUG_ON(cstart != resv->r_start);
809
810    spin_lock(&resv_lock);
811
812    trace_ocfs2_resmap_claimed_bits_begin(cstart, cend, clen, resv->r_start,
813                          ocfs2_resv_end(resv), resv->r_len,
814                          resv->r_last_start,
815                          resv->r_last_len);
816
817    BUG_ON(cstart < resv->r_start);
818    BUG_ON(cstart > ocfs2_resv_end(resv));
819    BUG_ON(cend > ocfs2_resv_end(resv));
820
821    ocfs2_adjust_resv_from_alloc(resmap, resv, cstart, cend);
822    resv->r_last_start = cstart;
823    resv->r_last_len = clen;
824
825    /*
826     * May have been discarded above from
827     * ocfs2_adjust_resv_from_alloc().
828     */
829    if (!ocfs2_resv_empty(resv))
830        ocfs2_resv_mark_lru(resmap, resv);
831
832    trace_ocfs2_resmap_claimed_bits_end(resv->r_start, ocfs2_resv_end(resv),
833                        resv->r_len, resv->r_last_start,
834                        resv->r_last_len);
835
836    ocfs2_check_resmap(resmap);
837
838    spin_unlock(&resv_lock);
839}
840

Archive Download this file



interactive