FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_blist.c
1 /*-
2 * Copyright (c) 1998 Matthew Dillon. All Rights Reserved.
3 * Redistribution and use in source and binary forms, with or without
4 * modification, are permitted provided that the following conditions
5 * are met:
6 * 1. Redistributions of source code must retain the above copyright
7 * notice, this list of conditions and the following disclaimer.
8 * 2. Redistributions in binary form must reproduce the above copyright
9 * notice, this list of conditions and the following disclaimer in the
10 * documentation and/or other materials provided with the distribution.
11 * 4. Neither the name of the University nor the names of its contributors
12 * may be used to endorse or promote products derived from this software
13 * without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
19 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
21 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
24 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
25 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27 /*
28 * BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting
29 *
30 * This module implements a general bitmap allocator/deallocator. The
31 * allocator eats around 2 bits per 'block'. The module does not
32 * try to interpret the meaning of a 'block' other than to return
33 * SWAPBLK_NONE on an allocation failure.
34 *
35 * A radix tree is used to maintain the bitmap. Two radix constants are
36 * involved: One for the bitmaps contained in the leaf nodes (typically
37 * 32), and one for the meta nodes (typically 16). Both meta and leaf
38 * nodes have a hint field. This field gives us a hint as to the largest
39 * free contiguous range of blocks under the node. It may contain a
40 * value that is too high, but will never contain a value that is too
41 * low. When the radix tree is searched, allocation failures in subtrees
42 * update the hint.
43 *
44 * The radix tree also implements two collapsed states for meta nodes:
45 * the ALL-ALLOCATED state and the ALL-FREE state. If a meta node is
46 * in either of these two states, all information contained underneath
47 * the node is considered stale. These states are used to optimize
48 * allocation and freeing operations.
49 *
50 * The hinting greatly increases code efficiency for allocations while
51 * the general radix structure optimizes both allocations and frees. The
52 * radix tree should be able to operate well no matter how much
53 * fragmentation there is and no matter how large a bitmap is used.
54 *
55 * The blist code wires all necessary memory at creation time. Neither
56 * allocations nor frees require interaction with the memory subsystem.
57 * The non-blocking features of the blist code are used in the swap code
58 * (vm/swap_pager.c).
59 *
60 * LAYOUT: The radix tree is laid out recursively using a
61 * linear array. Each meta node is immediately followed (laid out
62 * sequentially in memory) by BLIST_META_RADIX lower level nodes. This
63 * is a recursive structure but one that can be easily scanned through
64 * a very simple 'skip' calculation. In order to support large radixes,
65 * portions of the tree may reside outside our memory allocation. We
66 * handle this with an early-termination optimization (when bighint is
67 * set to -1) on the scan. The memory allocation is only large enough
68 * to cover the number of blocks requested at creation time even if it
69 * must be encompassed in larger root-node radix.
70 *
71 * NOTE: the allocator cannot currently allocate more than
72 * BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too
73 * large' if you try. This is an area that could use improvement. The
74 * radix is large enough that this restriction does not effect the swap
75 * system, though. Currently only the allocation code is effected by
76 * this algorithmic unfeature. The freeing code can handle arbitrary
77 * ranges.
78 *
79 * This code can be compiled stand-alone for debugging.
80 */
81
82 #include <sys/cdefs.h>
83 __FBSDID("$FreeBSD: releng/11.1/sys/kern/subr_blist.c 319981 2017-06-15 17:06:04Z alc $");
84
85 #ifdef _KERNEL
86
87 #include <sys/param.h>
88 #include <sys/systm.h>
89 #include <sys/lock.h>
90 #include <sys/kernel.h>
91 #include <sys/blist.h>
92 #include <sys/malloc.h>
93 #include <sys/proc.h>
94 #include <sys/mutex.h>
95
96 #else
97
98 #ifndef BLIST_NO_DEBUG
99 #define BLIST_DEBUG
100 #endif
101
102 #include <sys/types.h>
103 #include <sys/malloc.h>
104 #include <stdio.h>
105 #include <string.h>
106 #include <stdlib.h>
107 #include <stdarg.h>
108
109 #define malloc(a,b,c) calloc(a, 1)
110 #define free(a,b) free(a)
111
112 #include <sys/blist.h>
113
114 void panic(const char *ctl, ...);
115
116 #endif
117
118 /*
119 * static support functions
120 */
121
122 static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count);
123 static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk,
124 daddr_t count, daddr_t radix, int skip);
125 static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
126 static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count,
127 daddr_t radix, int skip, daddr_t blk);
128 static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix,
129 daddr_t skip, blist_t dest, daddr_t count);
130 static int blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count);
131 static int blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count,
132 daddr_t radix, int skip, daddr_t blk);
133 static daddr_t blst_radix_init(blmeta_t *scan, daddr_t radix,
134 int skip, daddr_t count);
135 #ifndef _KERNEL
136 static void blst_radix_print(blmeta_t *scan, daddr_t blk,
137 daddr_t radix, int skip, int tab);
138 #endif
139
140 #ifdef _KERNEL
141 static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
142 #endif
143
144 /*
145 * blist_create() - create a blist capable of handling up to the specified
146 * number of blocks
147 *
148 * blocks - must be greater than 0
149 * flags - malloc flags
150 *
151 * The smallest blist consists of a single leaf node capable of
152 * managing BLIST_BMAP_RADIX blocks.
153 */
154
155 blist_t
156 blist_create(daddr_t blocks, int flags)
157 {
158 blist_t bl;
159 int radix;
160 int skip = 0;
161
162 /*
163 * Calculate radix and skip field used for scanning.
164 */
165 radix = BLIST_BMAP_RADIX;
166
167 while (radix < blocks) {
168 radix *= BLIST_META_RADIX;
169 skip = (skip + 1) * BLIST_META_RADIX;
170 }
171
172 bl = malloc(sizeof(struct blist), M_SWAP, flags | M_ZERO);
173
174 bl->bl_blocks = blocks;
175 bl->bl_radix = radix;
176 bl->bl_skip = skip;
177 bl->bl_rootblks = 1 +
178 blst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks);
179 bl->bl_root = malloc(sizeof(blmeta_t) * bl->bl_rootblks, M_SWAP, flags);
180
181 #if defined(BLIST_DEBUG)
182 printf(
183 "BLIST representing %lld blocks (%lld MB of swap)"
184 ", requiring %lldK of ram\n",
185 (long long)bl->bl_blocks,
186 (long long)bl->bl_blocks * 4 / 1024,
187 (long long)(bl->bl_rootblks * sizeof(blmeta_t) + 1023) / 1024
188 );
189 printf("BLIST raw radix tree contains %lld records\n",
190 (long long)bl->bl_rootblks);
191 #endif
192 blst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks);
193
194 return(bl);
195 }
196
197 void
198 blist_destroy(blist_t bl)
199 {
200 free(bl->bl_root, M_SWAP);
201 free(bl, M_SWAP);
202 }
203
204 /*
205 * blist_alloc() - reserve space in the block bitmap. Return the base
206 * of a contiguous region or SWAPBLK_NONE if space could
207 * not be allocated.
208 */
209
210 daddr_t
211 blist_alloc(blist_t bl, daddr_t count)
212 {
213 daddr_t blk = SWAPBLK_NONE;
214
215 if (bl) {
216 if (bl->bl_radix == BLIST_BMAP_RADIX)
217 blk = blst_leaf_alloc(bl->bl_root, 0, count);
218 else
219 blk = blst_meta_alloc(bl->bl_root, 0, count, bl->bl_radix, bl->bl_skip);
220 if (blk != SWAPBLK_NONE)
221 bl->bl_free -= count;
222 }
223 return(blk);
224 }
225
226 /*
227 * blist_free() - free up space in the block bitmap. Return the base
228 * of a contiguous region. Panic if an inconsistancy is
229 * found.
230 */
231
232 void
233 blist_free(blist_t bl, daddr_t blkno, daddr_t count)
234 {
235 if (bl) {
236 if (bl->bl_radix == BLIST_BMAP_RADIX)
237 blst_leaf_free(bl->bl_root, blkno, count);
238 else
239 blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0);
240 bl->bl_free += count;
241 }
242 }
243
244 /*
245 * blist_fill() - mark a region in the block bitmap as off-limits
246 * to the allocator (i.e. allocate it), ignoring any
247 * existing allocations. Return the number of blocks
248 * actually filled that were free before the call.
249 */
250
251 int
252 blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
253 {
254 int filled;
255
256 if (bl) {
257 if (bl->bl_radix == BLIST_BMAP_RADIX)
258 filled = blst_leaf_fill(bl->bl_root, blkno, count);
259 else
260 filled = blst_meta_fill(bl->bl_root, blkno, count,
261 bl->bl_radix, bl->bl_skip, 0);
262 bl->bl_free -= filled;
263 return filled;
264 } else
265 return 0;
266 }
267
268 /*
269 * blist_resize() - resize an existing radix tree to handle the
270 * specified number of blocks. This will reallocate
271 * the tree and transfer the previous bitmap to the new
272 * one. When extending the tree you can specify whether
273 * the new blocks are to left allocated or freed.
274 */
275
276 void
277 blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags)
278 {
279 blist_t newbl = blist_create(count, flags);
280 blist_t save = *pbl;
281
282 *pbl = newbl;
283 if (count > save->bl_blocks)
284 count = save->bl_blocks;
285 blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count);
286
287 /*
288 * If resizing upwards, should we free the new space or not?
289 */
290 if (freenew && count < newbl->bl_blocks) {
291 blist_free(newbl, count, newbl->bl_blocks - count);
292 }
293 blist_destroy(save);
294 }
295
296 #ifdef BLIST_DEBUG
297
298 /*
299 * blist_print() - dump radix tree
300 */
301
302 void
303 blist_print(blist_t bl)
304 {
305 printf("BLIST {\n");
306 blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4);
307 printf("}\n");
308 }
309
310 #endif
311
312 /************************************************************************
313 * ALLOCATION SUPPORT FUNCTIONS *
314 ************************************************************************
315 *
316 * These support functions do all the actual work. They may seem
317 * rather longish, but that's because I've commented them up. The
318 * actual code is straight forward.
319 *
320 */
321
322 /*
323 * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap).
324 *
325 * This is the core of the allocator and is optimized for the 1 block
326 * and the BLIST_BMAP_RADIX block allocation cases. Other cases are
327 * somewhat slower. The 1 block allocation case is log2 and extremely
328 * quick.
329 */
330
331 static daddr_t
332 blst_leaf_alloc(
333 blmeta_t *scan,
334 daddr_t blk,
335 int count
336 ) {
337 u_daddr_t orig = scan->u.bmu_bitmap;
338
339 if (orig == 0) {
340 /*
341 * Optimize bitmap all-allocated case. Also, count = 1
342 * case assumes at least 1 bit is free in the bitmap, so
343 * we have to take care of this case here.
344 */
345 scan->bm_bighint = 0;
346 return(SWAPBLK_NONE);
347 }
348 if (count == 1) {
349 /*
350 * Optimized code to allocate one bit out of the bitmap
351 */
352 u_daddr_t mask;
353 int j = BLIST_BMAP_RADIX/2;
354 int r = 0;
355
356 mask = (u_daddr_t)-1 >> (BLIST_BMAP_RADIX/2);
357
358 while (j) {
359 if ((orig & mask) == 0) {
360 r += j;
361 orig >>= j;
362 }
363 j >>= 1;
364 mask >>= j;
365 }
366 scan->u.bmu_bitmap &= ~((u_daddr_t)1 << r);
367 return(blk + r);
368 }
369 if (count <= BLIST_BMAP_RADIX) {
370 /*
371 * non-optimized code to allocate N bits out of the bitmap.
372 * The more bits, the faster the code runs. It will run
373 * the slowest allocating 2 bits, but since there aren't any
374 * memory ops in the core loop (or shouldn't be, anyway),
375 * you probably won't notice the difference.
376 */
377 int j;
378 int n = BLIST_BMAP_RADIX - count;
379 u_daddr_t mask;
380
381 mask = (u_daddr_t)-1 >> n;
382
383 for (j = 0; j <= n; ++j) {
384 if ((orig & mask) == mask) {
385 scan->u.bmu_bitmap &= ~mask;
386 return(blk + j);
387 }
388 mask = (mask << 1);
389 }
390 }
391 /*
392 * We couldn't allocate count in this subtree, update bighint.
393 */
394 scan->bm_bighint = count - 1;
395 return(SWAPBLK_NONE);
396 }
397
398 /*
399 * blist_meta_alloc() - allocate at a meta in the radix tree.
400 *
401 * Attempt to allocate at a meta node. If we can't, we update
402 * bighint and return a failure. Updating bighint optimize future
403 * calls that hit this node. We have to check for our collapse cases
404 * and we have a few optimizations strewn in as well.
405 */
406
407 static daddr_t
408 blst_meta_alloc(
409 blmeta_t *scan,
410 daddr_t blk,
411 daddr_t count,
412 daddr_t radix,
413 int skip
414 ) {
415 int i;
416 int next_skip = ((u_int)skip / BLIST_META_RADIX);
417
418 if (scan->u.bmu_avail == 0) {
419 /*
420 * ALL-ALLOCATED special case
421 */
422 scan->bm_bighint = count;
423 return(SWAPBLK_NONE);
424 }
425
426 if (scan->u.bmu_avail == radix) {
427 radix /= BLIST_META_RADIX;
428
429 /*
430 * ALL-FREE special case, initialize uninitialize
431 * sublevel.
432 */
433 for (i = 1; i <= skip; i += next_skip) {
434 if (scan[i].bm_bighint == (daddr_t)-1)
435 break;
436 if (next_skip == 1) {
437 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
438 scan[i].bm_bighint = BLIST_BMAP_RADIX;
439 } else {
440 scan[i].bm_bighint = radix;
441 scan[i].u.bmu_avail = radix;
442 }
443 }
444 } else {
445 radix /= BLIST_META_RADIX;
446 }
447
448 for (i = 1; i <= skip; i += next_skip) {
449 if (count <= scan[i].bm_bighint) {
450 /*
451 * count fits in object
452 */
453 daddr_t r;
454 if (next_skip == 1) {
455 r = blst_leaf_alloc(&scan[i], blk, count);
456 } else {
457 r = blst_meta_alloc(&scan[i], blk, count, radix, next_skip - 1);
458 }
459 if (r != SWAPBLK_NONE) {
460 scan->u.bmu_avail -= count;
461 if (scan->bm_bighint > scan->u.bmu_avail)
462 scan->bm_bighint = scan->u.bmu_avail;
463 return(r);
464 }
465 } else if (scan[i].bm_bighint == (daddr_t)-1) {
466 /*
467 * Terminator
468 */
469 break;
470 } else if (count > radix) {
471 /*
472 * count does not fit in object even if it were
473 * complete free.
474 */
475 panic("blist_meta_alloc: allocation too large");
476 }
477 blk += radix;
478 }
479
480 /*
481 * We couldn't allocate count in this subtree, update bighint.
482 */
483 if (scan->bm_bighint >= count)
484 scan->bm_bighint = count - 1;
485 return(SWAPBLK_NONE);
486 }
487
488 /*
489 * BLST_LEAF_FREE() - free allocated block from leaf bitmap
490 *
491 */
492
493 static void
494 blst_leaf_free(
495 blmeta_t *scan,
496 daddr_t blk,
497 int count
498 ) {
499 /*
500 * free some data in this bitmap
501 *
502 * e.g.
503 * 0000111111111110000
504 * \_________/\__/
505 * v n
506 */
507 int n = blk & (BLIST_BMAP_RADIX - 1);
508 u_daddr_t mask;
509
510 mask = ((u_daddr_t)-1 << n) &
511 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
512
513 if (scan->u.bmu_bitmap & mask)
514 panic("blst_radix_free: freeing free block");
515 scan->u.bmu_bitmap |= mask;
516
517 /*
518 * We could probably do a better job here. We are required to make
519 * bighint at least as large as the biggest contiguous block of
520 * data. If we just shoehorn it, a little extra overhead will
521 * be incured on the next allocation (but only that one typically).
522 */
523 scan->bm_bighint = BLIST_BMAP_RADIX;
524 }
525
526 /*
527 * BLST_META_FREE() - free allocated blocks from radix tree meta info
528 *
529 * This support routine frees a range of blocks from the bitmap.
530 * The range must be entirely enclosed by this radix node. If a
531 * meta node, we break the range down recursively to free blocks
532 * in subnodes (which means that this code can free an arbitrary
533 * range whereas the allocation code cannot allocate an arbitrary
534 * range).
535 */
536
537 static void
538 blst_meta_free(
539 blmeta_t *scan,
540 daddr_t freeBlk,
541 daddr_t count,
542 daddr_t radix,
543 int skip,
544 daddr_t blk
545 ) {
546 int i;
547 int next_skip = ((u_int)skip / BLIST_META_RADIX);
548
549 #if 0
550 printf("free (%llx,%lld) FROM (%llx,%lld)\n",
551 (long long)freeBlk, (long long)count,
552 (long long)blk, (long long)radix
553 );
554 #endif
555
556 if (scan->u.bmu_avail == 0) {
557 /*
558 * ALL-ALLOCATED special case, with possible
559 * shortcut to ALL-FREE special case.
560 */
561 scan->u.bmu_avail = count;
562 scan->bm_bighint = count;
563
564 if (count != radix) {
565 for (i = 1; i <= skip; i += next_skip) {
566 if (scan[i].bm_bighint == (daddr_t)-1)
567 break;
568 scan[i].bm_bighint = 0;
569 if (next_skip == 1) {
570 scan[i].u.bmu_bitmap = 0;
571 } else {
572 scan[i].u.bmu_avail = 0;
573 }
574 }
575 /* fall through */
576 }
577 } else {
578 scan->u.bmu_avail += count;
579 /* scan->bm_bighint = radix; */
580 }
581
582 /*
583 * ALL-FREE special case.
584 */
585
586 if (scan->u.bmu_avail == radix)
587 return;
588 if (scan->u.bmu_avail > radix)
589 panic("blst_meta_free: freeing already free blocks (%lld) %lld/%lld",
590 (long long)count, (long long)scan->u.bmu_avail,
591 (long long)radix);
592
593 /*
594 * Break the free down into its components
595 */
596
597 radix /= BLIST_META_RADIX;
598
599 i = (freeBlk - blk) / radix;
600 blk += i * radix;
601 i = i * next_skip + 1;
602
603 while (i <= skip && blk < freeBlk + count) {
604 daddr_t v;
605
606 v = blk + radix - freeBlk;
607 if (v > count)
608 v = count;
609
610 if (scan->bm_bighint == (daddr_t)-1)
611 panic("blst_meta_free: freeing unexpected range");
612
613 if (next_skip == 1) {
614 blst_leaf_free(&scan[i], freeBlk, v);
615 } else {
616 blst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk);
617 }
618 if (scan->bm_bighint < scan[i].bm_bighint)
619 scan->bm_bighint = scan[i].bm_bighint;
620 count -= v;
621 freeBlk += v;
622 blk += radix;
623 i += next_skip;
624 }
625 }
626
627 /*
628 * BLIST_RADIX_COPY() - copy one radix tree to another
629 *
630 * Locates free space in the source tree and frees it in the destination
631 * tree. The space may not already be free in the destination.
632 */
633
634 static void blst_copy(
635 blmeta_t *scan,
636 daddr_t blk,
637 daddr_t radix,
638 daddr_t skip,
639 blist_t dest,
640 daddr_t count
641 ) {
642 int next_skip;
643 int i;
644
645 /*
646 * Leaf node
647 */
648
649 if (radix == BLIST_BMAP_RADIX) {
650 u_daddr_t v = scan->u.bmu_bitmap;
651
652 if (v == (u_daddr_t)-1) {
653 blist_free(dest, blk, count);
654 } else if (v != 0) {
655 int i;
656
657 for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) {
658 if (v & ((u_daddr_t)1 << i))
659 blist_free(dest, blk + i, 1);
660 }
661 }
662 return;
663 }
664
665 /*
666 * Meta node
667 */
668
669 if (scan->u.bmu_avail == 0) {
670 /*
671 * Source all allocated, leave dest allocated
672 */
673 return;
674 }
675 if (scan->u.bmu_avail == radix) {
676 /*
677 * Source all free, free entire dest
678 */
679 if (count < radix)
680 blist_free(dest, blk, count);
681 else
682 blist_free(dest, blk, radix);
683 return;
684 }
685
686
687 radix /= BLIST_META_RADIX;
688 next_skip = ((u_int)skip / BLIST_META_RADIX);
689
690 for (i = 1; count && i <= skip; i += next_skip) {
691 if (scan[i].bm_bighint == (daddr_t)-1)
692 break;
693
694 if (count >= radix) {
695 blst_copy(
696 &scan[i],
697 blk,
698 radix,
699 next_skip - 1,
700 dest,
701 radix
702 );
703 count -= radix;
704 } else {
705 if (count) {
706 blst_copy(
707 &scan[i],
708 blk,
709 radix,
710 next_skip - 1,
711 dest,
712 count
713 );
714 }
715 count = 0;
716 }
717 blk += radix;
718 }
719 }
720
721 /*
722 * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap
723 *
724 * This routine allocates all blocks in the specified range
725 * regardless of any existing allocations in that range. Returns
726 * the number of blocks allocated by the call.
727 */
728
729 static int
730 blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)
731 {
732 int n = blk & (BLIST_BMAP_RADIX - 1);
733 int nblks;
734 u_daddr_t mask, bitmap;
735
736 mask = ((u_daddr_t)-1 << n) &
737 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
738
739 /* Count the number of blocks we're about to allocate */
740 bitmap = scan->u.bmu_bitmap & mask;
741 for (nblks = 0; bitmap != 0; nblks++)
742 bitmap &= bitmap - 1;
743
744 scan->u.bmu_bitmap &= ~mask;
745 return nblks;
746 }
747
748 /*
749 * BLIST_META_FILL() - allocate specific blocks at a meta node
750 *
751 * This routine allocates the specified range of blocks,
752 * regardless of any existing allocations in the range. The
753 * range must be within the extent of this node. Returns the
754 * number of blocks allocated by the call.
755 */
756 static int
757 blst_meta_fill(
758 blmeta_t *scan,
759 daddr_t allocBlk,
760 daddr_t count,
761 daddr_t radix,
762 int skip,
763 daddr_t blk
764 ) {
765 int i;
766 int next_skip = ((u_int)skip / BLIST_META_RADIX);
767 int nblks = 0;
768
769 if (count > radix)
770 panic("blist_meta_fill: allocation too large");
771 if (count == radix || scan->u.bmu_avail == 0) {
772 /*
773 * ALL-ALLOCATED special case
774 */
775 nblks = scan->u.bmu_avail;
776 scan->u.bmu_avail = 0;
777 scan->bm_bighint = count;
778 return nblks;
779 }
780
781 if (scan->u.bmu_avail == radix) {
782 radix /= BLIST_META_RADIX;
783
784 /*
785 * ALL-FREE special case, initialize sublevel
786 */
787 for (i = 1; i <= skip; i += next_skip) {
788 if (scan[i].bm_bighint == (daddr_t)-1)
789 break;
790 if (next_skip == 1) {
791 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
792 scan[i].bm_bighint = BLIST_BMAP_RADIX;
793 } else {
794 scan[i].bm_bighint = radix;
795 scan[i].u.bmu_avail = radix;
796 }
797 }
798 } else {
799 radix /= BLIST_META_RADIX;
800 }
801
802 i = (allocBlk - blk) / radix;
803 blk += i * radix;
804 i = i * next_skip + 1;
805
806 while (i <= skip && blk < allocBlk + count) {
807 daddr_t v;
808
809 v = blk + radix - allocBlk;
810 if (v > count)
811 v = count;
812
813 if (scan->bm_bighint == (daddr_t)-1)
814 panic("blst_meta_fill: filling unexpected range");
815
816 if (next_skip == 1) {
817 nblks += blst_leaf_fill(&scan[i], allocBlk, v);
818 } else {
819 nblks += blst_meta_fill(&scan[i], allocBlk, v,
820 radix, next_skip - 1, blk);
821 }
822 count -= v;
823 allocBlk += v;
824 blk += radix;
825 i += next_skip;
826 }
827 scan->u.bmu_avail -= nblks;
828 return nblks;
829 }
830
831 /*
832 * BLST_RADIX_INIT() - initialize radix tree
833 *
834 * Initialize our meta structures and bitmaps and calculate the exact
835 * amount of space required to manage 'count' blocks - this space may
836 * be considerably less than the calculated radix due to the large
837 * RADIX values we use.
838 */
839
840 static daddr_t
841 blst_radix_init(blmeta_t *scan, daddr_t radix, int skip, daddr_t count)
842 {
843 int i;
844 int next_skip;
845 daddr_t memindex = 0;
846
847 /*
848 * Leaf node
849 */
850
851 if (radix == BLIST_BMAP_RADIX) {
852 if (scan) {
853 scan->bm_bighint = 0;
854 scan->u.bmu_bitmap = 0;
855 }
856 return(memindex);
857 }
858
859 /*
860 * Meta node. If allocating the entire object we can special
861 * case it. However, we need to figure out how much memory
862 * is required to manage 'count' blocks, so we continue on anyway.
863 */
864
865 if (scan) {
866 scan->bm_bighint = 0;
867 scan->u.bmu_avail = 0;
868 }
869
870 radix /= BLIST_META_RADIX;
871 next_skip = ((u_int)skip / BLIST_META_RADIX);
872
873 for (i = 1; i <= skip; i += next_skip) {
874 if (count >= radix) {
875 /*
876 * Allocate the entire object
877 */
878 memindex = i + blst_radix_init(
879 ((scan) ? &scan[i] : NULL),
880 radix,
881 next_skip - 1,
882 radix
883 );
884 count -= radix;
885 } else if (count > 0) {
886 /*
887 * Allocate a partial object
888 */
889 memindex = i + blst_radix_init(
890 ((scan) ? &scan[i] : NULL),
891 radix,
892 next_skip - 1,
893 count
894 );
895 count = 0;
896 } else {
897 /*
898 * Add terminator and break out
899 */
900 if (scan)
901 scan[i].bm_bighint = (daddr_t)-1;
902 break;
903 }
904 }
905 if (memindex < i)
906 memindex = i;
907 return(memindex);
908 }
909
910 #ifdef BLIST_DEBUG
911
912 static void
913 blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int skip, int tab)
914 {
915 int i;
916 int next_skip;
917 int lastState = 0;
918
919 if (radix == BLIST_BMAP_RADIX) {
920 printf(
921 "%*.*s(%08llx,%lld): bitmap %016llx big=%lld\n",
922 tab, tab, "",
923 (long long)blk, (long long)radix,
924 (long long)scan->u.bmu_bitmap,
925 (long long)scan->bm_bighint
926 );
927 return;
928 }
929
930 if (scan->u.bmu_avail == 0) {
931 printf(
932 "%*.*s(%08llx,%lld) ALL ALLOCATED\n",
933 tab, tab, "",
934 (long long)blk,
935 (long long)radix
936 );
937 return;
938 }
939 if (scan->u.bmu_avail == radix) {
940 printf(
941 "%*.*s(%08llx,%lld) ALL FREE\n",
942 tab, tab, "",
943 (long long)blk,
944 (long long)radix
945 );
946 return;
947 }
948
949 printf(
950 "%*.*s(%08llx,%lld): subtree (%lld/%lld) big=%lld {\n",
951 tab, tab, "",
952 (long long)blk, (long long)radix,
953 (long long)scan->u.bmu_avail,
954 (long long)radix,
955 (long long)scan->bm_bighint
956 );
957
958 radix /= BLIST_META_RADIX;
959 next_skip = ((u_int)skip / BLIST_META_RADIX);
960 tab += 4;
961
962 for (i = 1; i <= skip; i += next_skip) {
963 if (scan[i].bm_bighint == (daddr_t)-1) {
964 printf(
965 "%*.*s(%08llx,%lld): Terminator\n",
966 tab, tab, "",
967 (long long)blk, (long long)radix
968 );
969 lastState = 0;
970 break;
971 }
972 blst_radix_print(
973 &scan[i],
974 blk,
975 radix,
976 next_skip - 1,
977 tab
978 );
979 blk += radix;
980 }
981 tab -= 4;
982
983 printf(
984 "%*.*s}\n",
985 tab, tab, ""
986 );
987 }
988
989 #endif
990
991 #ifdef BLIST_DEBUG
992
993 int
994 main(int ac, char **av)
995 {
996 int size = 1024;
997 int i;
998 blist_t bl;
999
1000 for (i = 1; i < ac; ++i) {
1001 const char *ptr = av[i];
1002 if (*ptr != '-') {
1003 size = strtol(ptr, NULL, 0);
1004 continue;
1005 }
1006 ptr += 2;
1007 fprintf(stderr, "Bad option: %s\n", ptr - 2);
1008 exit(1);
1009 }
1010 bl = blist_create(size, M_WAITOK);
1011 blist_free(bl, 0, size);
1012
1013 for (;;) {
1014 char buf[1024];
1015 long long da = 0;
1016 long long count = 0;
1017
1018 printf("%lld/%lld/%lld> ", (long long)bl->bl_free,
1019 (long long)size, (long long)bl->bl_radix);
1020 fflush(stdout);
1021 if (fgets(buf, sizeof(buf), stdin) == NULL)
1022 break;
1023 switch(buf[0]) {
1024 case 'r':
1025 if (sscanf(buf + 1, "%lld", &count) == 1) {
1026 blist_resize(&bl, count, 1, M_WAITOK);
1027 } else {
1028 printf("?\n");
1029 }
1030 case 'p':
1031 blist_print(bl);
1032 break;
1033 case 'a':
1034 if (sscanf(buf + 1, "%lld", &count) == 1) {
1035 daddr_t blk = blist_alloc(bl, count);
1036 printf(" R=%08llx\n", (long long)blk);
1037 } else {
1038 printf("?\n");
1039 }
1040 break;
1041 case 'f':
1042 if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
1043 blist_free(bl, da, count);
1044 } else {
1045 printf("?\n");
1046 }
1047 break;
1048 case 'l':
1049 if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
1050 printf(" n=%d\n",
1051 blist_fill(bl, da, count));
1052 } else {
1053 printf("?\n");
1054 }
1055 break;
1056 case '?':
1057 case 'h':
1058 puts(
1059 "p -print\n"
1060 "a %d -allocate\n"
1061 "f %x %d -free\n"
1062 "l %x %d -fill\n"
1063 "r %d -resize\n"
1064 "h/? -help"
1065 );
1066 break;
1067 default:
1068 printf("?\n");
1069 break;
1070 }
1071 }
1072 return(0);
1073 }
1074
1075 void
1076 panic(const char *ctl, ...)
1077 {
1078 va_list va;
1079
1080 va_start(va, ctl);
1081 vfprintf(stderr, ctl, va);
1082 fprintf(stderr, "\n");
1083 va_end(va);
1084 exit(1);
1085 }
1086
1087 #endif
1088
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