Root/lib/btree.c

1/*
2 * lib/btree.c - Simple In-memory B+Tree
3 *
4 * As should be obvious for Linux kernel code, license is GPLv2
5 *
6 * Copyright (c) 2007-2008 Joern Engel <joern@logfs.org>
7 * Bits and pieces stolen from Peter Zijlstra's code, which is
8 * Copyright 2007, Red Hat Inc. Peter Zijlstra <pzijlstr@redhat.com>
9 * GPLv2
10 *
11 * see http://programming.kicks-ass.net/kernel-patches/vma_lookup/btree.patch
12 *
13 * A relatively simple B+Tree implementation. I have written it as a learning
14 * excercise to understand how B+Trees work. Turned out to be useful as well.
15 *
16 * B+Trees can be used similar to Linux radix trees (which don't have anything
17 * in common with textbook radix trees, beware). Prerequisite for them working
18 * well is that access to a random tree node is much faster than a large number
19 * of operations within each node.
20 *
21 * Disks have fulfilled the prerequisite for a long time. More recently DRAM
22 * has gained similar properties, as memory access times, when measured in cpu
23 * cycles, have increased. Cacheline sizes have increased as well, which also
24 * helps B+Trees.
25 *
26 * Compared to radix trees, B+Trees are more efficient when dealing with a
27 * sparsely populated address space. Between 25% and 50% of the memory is
28 * occupied with valid pointers. When densely populated, radix trees contain
29 * ~98% pointers - hard to beat. Very sparse radix trees contain only ~2%
30 * pointers.
31 *
32 * This particular implementation stores pointers identified by a long value.
33 * Storing NULL pointers is illegal, lookup will return NULL when no entry
34 * was found.
35 *
36 * A tricks was used that is not commonly found in textbooks. The lowest
37 * values are to the right, not to the left. All used slots within a node
38 * are on the left, all unused slots contain NUL values. Most operations
39 * simply loop once over all slots and terminate on the first NUL.
40 */
41
42#include <linux/btree.h>
43#include <linux/cache.h>
44#include <linux/kernel.h>
45#include <linux/slab.h>
46#include <linux/module.h>
47
48#define MAX(a, b) ((a) > (b) ? (a) : (b))
49#define NODESIZE MAX(L1_CACHE_BYTES, 128)
50
51struct btree_geo {
52    int keylen;
53    int no_pairs;
54    int no_longs;
55};
56
57struct btree_geo btree_geo32 = {
58    .keylen = 1,
59    .no_pairs = NODESIZE / sizeof(long) / 2,
60    .no_longs = NODESIZE / sizeof(long) / 2,
61};
62EXPORT_SYMBOL_GPL(btree_geo32);
63
64#define LONG_PER_U64 (64 / BITS_PER_LONG)
65struct btree_geo btree_geo64 = {
66    .keylen = LONG_PER_U64,
67    .no_pairs = NODESIZE / sizeof(long) / (1 + LONG_PER_U64),
68    .no_longs = LONG_PER_U64 * (NODESIZE / sizeof(long) / (1 + LONG_PER_U64)),
69};
70EXPORT_SYMBOL_GPL(btree_geo64);
71
72struct btree_geo btree_geo128 = {
73    .keylen = 2 * LONG_PER_U64,
74    .no_pairs = NODESIZE / sizeof(long) / (1 + 2 * LONG_PER_U64),
75    .no_longs = 2 * LONG_PER_U64 * (NODESIZE / sizeof(long) / (1 + 2 * LONG_PER_U64)),
76};
77EXPORT_SYMBOL_GPL(btree_geo128);
78
79static struct kmem_cache *btree_cachep;
80
81void *btree_alloc(gfp_t gfp_mask, void *pool_data)
82{
83    return kmem_cache_alloc(btree_cachep, gfp_mask);
84}
85EXPORT_SYMBOL_GPL(btree_alloc);
86
87void btree_free(void *element, void *pool_data)
88{
89    kmem_cache_free(btree_cachep, element);
90}
91EXPORT_SYMBOL_GPL(btree_free);
92
93static unsigned long *btree_node_alloc(struct btree_head *head, gfp_t gfp)
94{
95    unsigned long *node;
96
97    node = mempool_alloc(head->mempool, gfp);
98    if (likely(node))
99        memset(node, 0, NODESIZE);
100    return node;
101}
102
103static int longcmp(const unsigned long *l1, const unsigned long *l2, size_t n)
104{
105    size_t i;
106
107    for (i = 0; i < n; i++) {
108        if (l1[i] < l2[i])
109            return -1;
110        if (l1[i] > l2[i])
111            return 1;
112    }
113    return 0;
114}
115
116static unsigned long *longcpy(unsigned long *dest, const unsigned long *src,
117        size_t n)
118{
119    size_t i;
120
121    for (i = 0; i < n; i++)
122        dest[i] = src[i];
123    return dest;
124}
125
126static unsigned long *longset(unsigned long *s, unsigned long c, size_t n)
127{
128    size_t i;
129
130    for (i = 0; i < n; i++)
131        s[i] = c;
132    return s;
133}
134
135static void dec_key(struct btree_geo *geo, unsigned long *key)
136{
137    unsigned long val;
138    int i;
139
140    for (i = geo->keylen - 1; i >= 0; i--) {
141        val = key[i];
142        key[i] = val - 1;
143        if (val)
144            break;
145    }
146}
147
148static unsigned long *bkey(struct btree_geo *geo, unsigned long *node, int n)
149{
150    return &node[n * geo->keylen];
151}
152
153static void *bval(struct btree_geo *geo, unsigned long *node, int n)
154{
155    return (void *)node[geo->no_longs + n];
156}
157
158static void setkey(struct btree_geo *geo, unsigned long *node, int n,
159           unsigned long *key)
160{
161    longcpy(bkey(geo, node, n), key, geo->keylen);
162}
163
164static void setval(struct btree_geo *geo, unsigned long *node, int n,
165           void *val)
166{
167    node[geo->no_longs + n] = (unsigned long) val;
168}
169
170static void clearpair(struct btree_geo *geo, unsigned long *node, int n)
171{
172    longset(bkey(geo, node, n), 0, geo->keylen);
173    node[geo->no_longs + n] = 0;
174}
175
176static inline void __btree_init(struct btree_head *head)
177{
178    head->node = NULL;
179    head->height = 0;
180}
181
182void btree_init_mempool(struct btree_head *head, mempool_t *mempool)
183{
184    __btree_init(head);
185    head->mempool = mempool;
186}
187EXPORT_SYMBOL_GPL(btree_init_mempool);
188
189int btree_init(struct btree_head *head)
190{
191    __btree_init(head);
192    head->mempool = mempool_create(0, btree_alloc, btree_free, NULL);
193    if (!head->mempool)
194        return -ENOMEM;
195    return 0;
196}
197EXPORT_SYMBOL_GPL(btree_init);
198
199void btree_destroy(struct btree_head *head)
200{
201    mempool_destroy(head->mempool);
202    head->mempool = NULL;
203}
204EXPORT_SYMBOL_GPL(btree_destroy);
205
206void *btree_last(struct btree_head *head, struct btree_geo *geo,
207         unsigned long *key)
208{
209    int height = head->height;
210    unsigned long *node = head->node;
211
212    if (height == 0)
213        return NULL;
214
215    for ( ; height > 1; height--)
216        node = bval(geo, node, 0);
217
218    longcpy(key, bkey(geo, node, 0), geo->keylen);
219    return bval(geo, node, 0);
220}
221EXPORT_SYMBOL_GPL(btree_last);
222
223static int keycmp(struct btree_geo *geo, unsigned long *node, int pos,
224          unsigned long *key)
225{
226    return longcmp(bkey(geo, node, pos), key, geo->keylen);
227}
228
229static int keyzero(struct btree_geo *geo, unsigned long *key)
230{
231    int i;
232
233    for (i = 0; i < geo->keylen; i++)
234        if (key[i])
235            return 0;
236
237    return 1;
238}
239
240void *btree_lookup(struct btree_head *head, struct btree_geo *geo,
241        unsigned long *key)
242{
243    int i, height = head->height;
244    unsigned long *node = head->node;
245
246    if (height == 0)
247        return NULL;
248
249    for ( ; height > 1; height--) {
250        for (i = 0; i < geo->no_pairs; i++)
251            if (keycmp(geo, node, i, key) <= 0)
252                break;
253        if (i == geo->no_pairs)
254            return NULL;
255        node = bval(geo, node, i);
256        if (!node)
257            return NULL;
258    }
259
260    if (!node)
261        return NULL;
262
263    for (i = 0; i < geo->no_pairs; i++)
264        if (keycmp(geo, node, i, key) == 0)
265            return bval(geo, node, i);
266    return NULL;
267}
268EXPORT_SYMBOL_GPL(btree_lookup);
269
270int btree_update(struct btree_head *head, struct btree_geo *geo,
271         unsigned long *key, void *val)
272{
273    int i, height = head->height;
274    unsigned long *node = head->node;
275
276    if (height == 0)
277        return -ENOENT;
278
279    for ( ; height > 1; height--) {
280        for (i = 0; i < geo->no_pairs; i++)
281            if (keycmp(geo, node, i, key) <= 0)
282                break;
283        if (i == geo->no_pairs)
284            return -ENOENT;
285        node = bval(geo, node, i);
286        if (!node)
287            return -ENOENT;
288    }
289
290    if (!node)
291        return -ENOENT;
292
293    for (i = 0; i < geo->no_pairs; i++)
294        if (keycmp(geo, node, i, key) == 0) {
295            setval(geo, node, i, val);
296            return 0;
297        }
298    return -ENOENT;
299}
300EXPORT_SYMBOL_GPL(btree_update);
301
302/*
303 * Usually this function is quite similar to normal lookup. But the key of
304 * a parent node may be smaller than the smallest key of all its siblings.
305 * In such a case we cannot just return NULL, as we have only proven that no
306 * key smaller than __key, but larger than this parent key exists.
307 * So we set __key to the parent key and retry. We have to use the smallest
308 * such parent key, which is the last parent key we encountered.
309 */
310void *btree_get_prev(struct btree_head *head, struct btree_geo *geo,
311             unsigned long *__key)
312{
313    int i, height;
314    unsigned long *node, *oldnode;
315    unsigned long *retry_key = NULL, key[geo->keylen];
316
317    if (keyzero(geo, __key))
318        return NULL;
319
320    if (head->height == 0)
321        return NULL;
322retry:
323    longcpy(key, __key, geo->keylen);
324    dec_key(geo, key);
325
326    node = head->node;
327    for (height = head->height ; height > 1; height--) {
328        for (i = 0; i < geo->no_pairs; i++)
329            if (keycmp(geo, node, i, key) <= 0)
330                break;
331        if (i == geo->no_pairs)
332            goto miss;
333        oldnode = node;
334        node = bval(geo, node, i);
335        if (!node)
336            goto miss;
337        retry_key = bkey(geo, oldnode, i);
338    }
339
340    if (!node)
341        goto miss;
342
343    for (i = 0; i < geo->no_pairs; i++) {
344        if (keycmp(geo, node, i, key) <= 0) {
345            if (bval(geo, node, i)) {
346                longcpy(__key, bkey(geo, node, i), geo->keylen);
347                return bval(geo, node, i);
348            } else
349                goto miss;
350        }
351    }
352miss:
353    if (retry_key) {
354        __key = retry_key;
355        retry_key = NULL;
356        goto retry;
357    }
358    return NULL;
359}
360
361static int getpos(struct btree_geo *geo, unsigned long *node,
362        unsigned long *key)
363{
364    int i;
365
366    for (i = 0; i < geo->no_pairs; i++) {
367        if (keycmp(geo, node, i, key) <= 0)
368            break;
369    }
370    return i;
371}
372
373static int getfill(struct btree_geo *geo, unsigned long *node, int start)
374{
375    int i;
376
377    for (i = start; i < geo->no_pairs; i++)
378        if (!bval(geo, node, i))
379            break;
380    return i;
381}
382
383/*
384 * locate the correct leaf node in the btree
385 */
386static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo,
387        unsigned long *key, int level)
388{
389    unsigned long *node = head->node;
390    int i, height;
391
392    for (height = head->height; height > level; height--) {
393        for (i = 0; i < geo->no_pairs; i++)
394            if (keycmp(geo, node, i, key) <= 0)
395                break;
396
397        if ((i == geo->no_pairs) || !bval(geo, node, i)) {
398            /* right-most key is too large, update it */
399            /* FIXME: If the right-most key on higher levels is
400             * always zero, this wouldn't be necessary. */
401            i--;
402            setkey(geo, node, i, key);
403        }
404        BUG_ON(i < 0);
405        node = bval(geo, node, i);
406    }
407    BUG_ON(!node);
408    return node;
409}
410
411static int btree_grow(struct btree_head *head, struct btree_geo *geo,
412              gfp_t gfp)
413{
414    unsigned long *node;
415    int fill;
416
417    node = btree_node_alloc(head, gfp);
418    if (!node)
419        return -ENOMEM;
420    if (head->node) {
421        fill = getfill(geo, head->node, 0);
422        setkey(geo, node, 0, bkey(geo, head->node, fill - 1));
423        setval(geo, node, 0, head->node);
424    }
425    head->node = node;
426    head->height++;
427    return 0;
428}
429
430static void btree_shrink(struct btree_head *head, struct btree_geo *geo)
431{
432    unsigned long *node;
433    int fill;
434
435    if (head->height <= 1)
436        return;
437
438    node = head->node;
439    fill = getfill(geo, node, 0);
440    BUG_ON(fill > 1);
441    head->node = bval(geo, node, 0);
442    head->height--;
443    mempool_free(node, head->mempool);
444}
445
446static int btree_insert_level(struct btree_head *head, struct btree_geo *geo,
447                  unsigned long *key, void *val, int level,
448                  gfp_t gfp)
449{
450    unsigned long *node;
451    int i, pos, fill, err;
452
453    BUG_ON(!val);
454    if (head->height < level) {
455        err = btree_grow(head, geo, gfp);
456        if (err)
457            return err;
458    }
459
460retry:
461    node = find_level(head, geo, key, level);
462    pos = getpos(geo, node, key);
463    fill = getfill(geo, node, pos);
464    /* two identical keys are not allowed */
465    BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0);
466
467    if (fill == geo->no_pairs) {
468        /* need to split node */
469        unsigned long *new;
470
471        new = btree_node_alloc(head, gfp);
472        if (!new)
473            return -ENOMEM;
474        err = btree_insert_level(head, geo,
475                bkey(geo, node, fill / 2 - 1),
476                new, level + 1, gfp);
477        if (err) {
478            mempool_free(new, head->mempool);
479            return err;
480        }
481        for (i = 0; i < fill / 2; i++) {
482            setkey(geo, new, i, bkey(geo, node, i));
483            setval(geo, new, i, bval(geo, node, i));
484            setkey(geo, node, i, bkey(geo, node, i + fill / 2));
485            setval(geo, node, i, bval(geo, node, i + fill / 2));
486            clearpair(geo, node, i + fill / 2);
487        }
488        if (fill & 1) {
489            setkey(geo, node, i, bkey(geo, node, fill - 1));
490            setval(geo, node, i, bval(geo, node, fill - 1));
491            clearpair(geo, node, fill - 1);
492        }
493        goto retry;
494    }
495    BUG_ON(fill >= geo->no_pairs);
496
497    /* shift and insert */
498    for (i = fill; i > pos; i--) {
499        setkey(geo, node, i, bkey(geo, node, i - 1));
500        setval(geo, node, i, bval(geo, node, i - 1));
501    }
502    setkey(geo, node, pos, key);
503    setval(geo, node, pos, val);
504
505    return 0;
506}
507
508int btree_insert(struct btree_head *head, struct btree_geo *geo,
509        unsigned long *key, void *val, gfp_t gfp)
510{
511    return btree_insert_level(head, geo, key, val, 1, gfp);
512}
513EXPORT_SYMBOL_GPL(btree_insert);
514
515static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo,
516        unsigned long *key, int level);
517static void merge(struct btree_head *head, struct btree_geo *geo, int level,
518        unsigned long *left, int lfill,
519        unsigned long *right, int rfill,
520        unsigned long *parent, int lpos)
521{
522    int i;
523
524    for (i = 0; i < rfill; i++) {
525        /* Move all keys to the left */
526        setkey(geo, left, lfill + i, bkey(geo, right, i));
527        setval(geo, left, lfill + i, bval(geo, right, i));
528    }
529    /* Exchange left and right child in parent */
530    setval(geo, parent, lpos, right);
531    setval(geo, parent, lpos + 1, left);
532    /* Remove left (formerly right) child from parent */
533    btree_remove_level(head, geo, bkey(geo, parent, lpos), level + 1);
534    mempool_free(right, head->mempool);
535}
536
537static void rebalance(struct btree_head *head, struct btree_geo *geo,
538        unsigned long *key, int level, unsigned long *child, int fill)
539{
540    unsigned long *parent, *left = NULL, *right = NULL;
541    int i, no_left, no_right;
542
543    if (fill == 0) {
544        /* Because we don't steal entries from a neigbour, this case
545         * can happen. Parent node contains a single child, this
546         * node, so merging with a sibling never happens.
547         */
548        btree_remove_level(head, geo, key, level + 1);
549        mempool_free(child, head->mempool);
550        return;
551    }
552
553    parent = find_level(head, geo, key, level + 1);
554    i = getpos(geo, parent, key);
555    BUG_ON(bval(geo, parent, i) != child);
556
557    if (i > 0) {
558        left = bval(geo, parent, i - 1);
559        no_left = getfill(geo, left, 0);
560        if (fill + no_left <= geo->no_pairs) {
561            merge(head, geo, level,
562                    left, no_left,
563                    child, fill,
564                    parent, i - 1);
565            return;
566        }
567    }
568    if (i + 1 < getfill(geo, parent, i)) {
569        right = bval(geo, parent, i + 1);
570        no_right = getfill(geo, right, 0);
571        if (fill + no_right <= geo->no_pairs) {
572            merge(head, geo, level,
573                    child, fill,
574                    right, no_right,
575                    parent, i);
576            return;
577        }
578    }
579    /*
580     * We could also try to steal one entry from the left or right
581     * neighbor. By not doing so we changed the invariant from
582     * "all nodes are at least half full" to "no two neighboring
583     * nodes can be merged". Which means that the average fill of
584     * all nodes is still half or better.
585     */
586}
587
588static void *btree_remove_level(struct btree_head *head, struct btree_geo *geo,
589        unsigned long *key, int level)
590{
591    unsigned long *node;
592    int i, pos, fill;
593    void *ret;
594
595    if (level > head->height) {
596        /* we recursed all the way up */
597        head->height = 0;
598        head->node = NULL;
599        return NULL;
600    }
601
602    node = find_level(head, geo, key, level);
603    pos = getpos(geo, node, key);
604    fill = getfill(geo, node, pos);
605    if ((level == 1) && (keycmp(geo, node, pos, key) != 0))
606        return NULL;
607    ret = bval(geo, node, pos);
608
609    /* remove and shift */
610    for (i = pos; i < fill - 1; i++) {
611        setkey(geo, node, i, bkey(geo, node, i + 1));
612        setval(geo, node, i, bval(geo, node, i + 1));
613    }
614    clearpair(geo, node, fill - 1);
615
616    if (fill - 1 < geo->no_pairs / 2) {
617        if (level < head->height)
618            rebalance(head, geo, key, level, node, fill - 1);
619        else if (fill - 1 == 1)
620            btree_shrink(head, geo);
621    }
622
623    return ret;
624}
625
626void *btree_remove(struct btree_head *head, struct btree_geo *geo,
627        unsigned long *key)
628{
629    if (head->height == 0)
630        return NULL;
631
632    return btree_remove_level(head, geo, key, 1);
633}
634EXPORT_SYMBOL_GPL(btree_remove);
635
636int btree_merge(struct btree_head *target, struct btree_head *victim,
637        struct btree_geo *geo, gfp_t gfp)
638{
639    unsigned long key[geo->keylen];
640    unsigned long dup[geo->keylen];
641    void *val;
642    int err;
643
644    BUG_ON(target == victim);
645
646    if (!(target->node)) {
647        /* target is empty, just copy fields over */
648        target->node = victim->node;
649        target->height = victim->height;
650        __btree_init(victim);
651        return 0;
652    }
653
654    /* TODO: This needs some optimizations. Currently we do three tree
655     * walks to remove a single object from the victim.
656     */
657    for (;;) {
658        if (!btree_last(victim, geo, key))
659            break;
660        val = btree_lookup(victim, geo, key);
661        err = btree_insert(target, geo, key, val, gfp);
662        if (err)
663            return err;
664        /* We must make a copy of the key, as the original will get
665         * mangled inside btree_remove. */
666        longcpy(dup, key, geo->keylen);
667        btree_remove(victim, geo, dup);
668    }
669    return 0;
670}
671EXPORT_SYMBOL_GPL(btree_merge);
672
673static size_t __btree_for_each(struct btree_head *head, struct btree_geo *geo,
674                   unsigned long *node, unsigned long opaque,
675                   void (*func)(void *elem, unsigned long opaque,
676                        unsigned long *key, size_t index,
677                        void *func2),
678                   void *func2, int reap, int height, size_t count)
679{
680    int i;
681    unsigned long *child;
682
683    for (i = 0; i < geo->no_pairs; i++) {
684        child = bval(geo, node, i);
685        if (!child)
686            break;
687        if (height > 1)
688            count = __btree_for_each(head, geo, child, opaque,
689                    func, func2, reap, height - 1, count);
690        else
691            func(child, opaque, bkey(geo, node, i), count++,
692                    func2);
693    }
694    if (reap)
695        mempool_free(node, head->mempool);
696    return count;
697}
698
699static void empty(void *elem, unsigned long opaque, unsigned long *key,
700          size_t index, void *func2)
701{
702}
703
704void visitorl(void *elem, unsigned long opaque, unsigned long *key,
705          size_t index, void *__func)
706{
707    visitorl_t func = __func;
708
709    func(elem, opaque, *key, index);
710}
711EXPORT_SYMBOL_GPL(visitorl);
712
713void visitor32(void *elem, unsigned long opaque, unsigned long *__key,
714           size_t index, void *__func)
715{
716    visitor32_t func = __func;
717    u32 *key = (void *)__key;
718
719    func(elem, opaque, *key, index);
720}
721EXPORT_SYMBOL_GPL(visitor32);
722
723void visitor64(void *elem, unsigned long opaque, unsigned long *__key,
724           size_t index, void *__func)
725{
726    visitor64_t func = __func;
727    u64 *key = (void *)__key;
728
729    func(elem, opaque, *key, index);
730}
731EXPORT_SYMBOL_GPL(visitor64);
732
733void visitor128(void *elem, unsigned long opaque, unsigned long *__key,
734        size_t index, void *__func)
735{
736    visitor128_t func = __func;
737    u64 *key = (void *)__key;
738
739    func(elem, opaque, key[0], key[1], index);
740}
741EXPORT_SYMBOL_GPL(visitor128);
742
743size_t btree_visitor(struct btree_head *head, struct btree_geo *geo,
744             unsigned long opaque,
745             void (*func)(void *elem, unsigned long opaque,
746                       unsigned long *key,
747                       size_t index, void *func2),
748             void *func2)
749{
750    size_t count = 0;
751
752    if (!func2)
753        func = empty;
754    if (head->node)
755        count = __btree_for_each(head, geo, head->node, opaque, func,
756                func2, 0, head->height, 0);
757    return count;
758}
759EXPORT_SYMBOL_GPL(btree_visitor);
760
761size_t btree_grim_visitor(struct btree_head *head, struct btree_geo *geo,
762              unsigned long opaque,
763              void (*func)(void *elem, unsigned long opaque,
764                       unsigned long *key,
765                       size_t index, void *func2),
766              void *func2)
767{
768    size_t count = 0;
769
770    if (!func2)
771        func = empty;
772    if (head->node)
773        count = __btree_for_each(head, geo, head->node, opaque, func,
774                func2, 1, head->height, 0);
775    __btree_init(head);
776    return count;
777}
778EXPORT_SYMBOL_GPL(btree_grim_visitor);
779
780static int __init btree_module_init(void)
781{
782    btree_cachep = kmem_cache_create("btree_node", NODESIZE, 0,
783            SLAB_HWCACHE_ALIGN, NULL);
784    return 0;
785}
786
787static void __exit btree_module_exit(void)
788{
789    kmem_cache_destroy(btree_cachep);
790}
791
792/* If core code starts using btree, initialization should happen even earlier */
793module_init(btree_module_init);
794module_exit(btree_module_exit);
795
796MODULE_AUTHOR("Joern Engel <joern@logfs.org>");
797MODULE_AUTHOR("Johannes Berg <johannes@sipsolutions.net>");
798MODULE_LICENSE("GPL");
799

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