Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_blist.c
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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("$FreeBSD$"); 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 #include <stdbool.h> 109 110 #define bitcount64(x) __bitcount64((uint64_t)(x)) 111 #define malloc(a,b,c) calloc(a, 1) 112 #define free(a,b) free(a) 113 114 #include <sys/blist.h> 115 116 void panic(const char *ctl, ...); 117 118 #endif 119 120 /* 121 * static support functions 122 */ 123 124 static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count, 125 daddr_t cursor); 126 static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk, daddr_t count, 127 daddr_t radix, daddr_t skip, daddr_t cursor); 128 static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count); 129 static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, 130 daddr_t radix, daddr_t skip, daddr_t blk); 131 static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, 132 daddr_t skip, blist_t dest, daddr_t count); 133 static daddr_t blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count); 134 static daddr_t blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, 135 daddr_t radix, daddr_t skip, daddr_t blk); 136 static daddr_t blst_radix_init(blmeta_t *scan, daddr_t radix, daddr_t skip, 137 daddr_t count); 138 #ifndef _KERNEL 139 static void blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, 140 daddr_t skip, int tab); 141 #endif 142 143 #ifdef _KERNEL 144 static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space"); 145 #endif 146 147 /* 148 * blist_create() - create a blist capable of handling up to the specified 149 * number of blocks 150 * 151 * blocks - must be greater than 0 152 * flags - malloc flags 153 * 154 * The smallest blist consists of a single leaf node capable of 155 * managing BLIST_BMAP_RADIX blocks. 156 */ 157 158 blist_t 159 blist_create(daddr_t blocks, int flags) 160 { 161 blist_t bl; 162 daddr_t nodes, radix, skip; 163 164 /* 165 * Calculate radix and skip field used for scanning. 166 */ 167 radix = BLIST_BMAP_RADIX; 168 skip = 0; 169 while (radix < blocks) { 170 radix *= BLIST_META_RADIX; 171 skip = (skip + 1) * BLIST_META_RADIX; 172 } 173 nodes = 1 + blst_radix_init(NULL, radix, skip, blocks); 174 175 bl = malloc(sizeof(struct blist), M_SWAP, flags); 176 if (bl == NULL) 177 return (NULL); 178 179 bl->bl_blocks = blocks; 180 bl->bl_radix = radix; 181 bl->bl_skip = skip; 182 bl->bl_cursor = 0; 183 bl->bl_root = malloc(nodes * sizeof(blmeta_t), M_SWAP, flags); 184 if (bl->bl_root == NULL) { 185 free(bl, M_SWAP); 186 return (NULL); 187 } 188 blst_radix_init(bl->bl_root, radix, skip, blocks); 189 190 #if defined(BLIST_DEBUG) 191 printf( 192 "BLIST representing %lld blocks (%lld MB of swap)" 193 ", requiring %lldK of ram\n", 194 (long long)bl->bl_blocks, 195 (long long)bl->bl_blocks * 4 / 1024, 196 (long long)(nodes * sizeof(blmeta_t) + 1023) / 1024 197 ); 198 printf("BLIST raw radix tree contains %lld records\n", 199 (long long)nodes); 200 #endif 201 202 return (bl); 203 } 204 205 void 206 blist_destroy(blist_t bl) 207 { 208 free(bl->bl_root, M_SWAP); 209 free(bl, M_SWAP); 210 } 211 212 /* 213 * blist_alloc() - reserve space in the block bitmap. Return the base 214 * of a contiguous region or SWAPBLK_NONE if space could 215 * not be allocated. 216 */ 217 218 daddr_t 219 blist_alloc(blist_t bl, daddr_t count) 220 { 221 daddr_t blk; 222 223 /* 224 * This loop iterates at most twice. An allocation failure in the 225 * first iteration leads to a second iteration only if the cursor was 226 * non-zero. When the cursor is zero, an allocation failure will 227 * reduce the hint, stopping further iterations. 228 */ 229 while (count <= bl->bl_root->bm_bighint) { 230 if (bl->bl_radix == BLIST_BMAP_RADIX) 231 blk = blst_leaf_alloc(bl->bl_root, 0, count, 232 bl->bl_cursor); 233 else 234 blk = blst_meta_alloc(bl->bl_root, 0, count, 235 bl->bl_radix, bl->bl_skip, bl->bl_cursor); 236 if (blk != SWAPBLK_NONE) { 237 bl->bl_cursor = blk + count; 238 return (blk); 239 } else if (bl->bl_cursor != 0) 240 bl->bl_cursor = 0; 241 } 242 return (SWAPBLK_NONE); 243 } 244 245 /* 246 * blist_avail() - return the number of free blocks. 247 */ 248 249 daddr_t 250 blist_avail(blist_t bl) 251 { 252 253 if (bl->bl_radix == BLIST_BMAP_RADIX) 254 return (bitcount64(bl->bl_root->u.bmu_bitmap)); 255 else 256 return (bl->bl_root->u.bmu_avail); 257 } 258 259 /* 260 * blist_free() - free up space in the block bitmap. Return the base 261 * of a contiguous region. Panic if an inconsistancy is 262 * found. 263 */ 264 265 void 266 blist_free(blist_t bl, daddr_t blkno, daddr_t count) 267 { 268 if (bl) { 269 if (bl->bl_radix == BLIST_BMAP_RADIX) 270 blst_leaf_free(bl->bl_root, blkno, count); 271 else 272 blst_meta_free(bl->bl_root, blkno, count, 273 bl->bl_radix, bl->bl_skip, 0); 274 } 275 } 276 277 /* 278 * blist_fill() - mark a region in the block bitmap as off-limits 279 * to the allocator (i.e. allocate it), ignoring any 280 * existing allocations. Return the number of blocks 281 * actually filled that were free before the call. 282 */ 283 284 daddr_t 285 blist_fill(blist_t bl, daddr_t blkno, daddr_t count) 286 { 287 daddr_t filled; 288 289 if (bl) { 290 if (bl->bl_radix == BLIST_BMAP_RADIX) 291 filled = blst_leaf_fill(bl->bl_root, blkno, count); 292 else 293 filled = blst_meta_fill(bl->bl_root, blkno, count, 294 bl->bl_radix, bl->bl_skip, 0); 295 return (filled); 296 } 297 return (0); 298 } 299 300 /* 301 * blist_resize() - resize an existing radix tree to handle the 302 * specified number of blocks. This will reallocate 303 * the tree and transfer the previous bitmap to the new 304 * one. When extending the tree you can specify whether 305 * the new blocks are to left allocated or freed. 306 */ 307 308 void 309 blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags) 310 { 311 blist_t newbl = blist_create(count, flags); 312 blist_t save = *pbl; 313 314 *pbl = newbl; 315 if (count > save->bl_blocks) 316 count = save->bl_blocks; 317 blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count); 318 319 /* 320 * If resizing upwards, should we free the new space or not? 321 */ 322 if (freenew && count < newbl->bl_blocks) { 323 blist_free(newbl, count, newbl->bl_blocks - count); 324 } 325 blist_destroy(save); 326 } 327 328 #ifdef BLIST_DEBUG 329 330 /* 331 * blist_print() - dump radix tree 332 */ 333 334 void 335 blist_print(blist_t bl) 336 { 337 printf("BLIST {\n"); 338 blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4); 339 printf("}\n"); 340 } 341 342 #endif 343 344 /************************************************************************ 345 * ALLOCATION SUPPORT FUNCTIONS * 346 ************************************************************************ 347 * 348 * These support functions do all the actual work. They may seem 349 * rather longish, but that's because I've commented them up. The 350 * actual code is straight forward. 351 * 352 */ 353 354 /* 355 * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap). 356 * 357 * This is the core of the allocator and is optimized for the 358 * BLIST_BMAP_RADIX block allocation case. Otherwise, execution 359 * time is proportional to log2(count) + log2(BLIST_BMAP_RADIX). 360 */ 361 362 static daddr_t 363 blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count, daddr_t cursor) 364 { 365 u_daddr_t mask; 366 int count1, hi, lo, mid, num_shifts, range1, range_ext; 367 368 if (count == BLIST_BMAP_RADIX) { 369 /* 370 * Optimize allocation of BLIST_BMAP_RADIX bits. If this wasn't 371 * a special case, then forming the final value of 'mask' below 372 * would require special handling to avoid an invalid left shift 373 * when count equals the number of bits in mask. 374 */ 375 if (~scan->u.bmu_bitmap != 0) { 376 scan->bm_bighint = BLIST_BMAP_RADIX - 1; 377 return (SWAPBLK_NONE); 378 } 379 if (cursor != blk) 380 return (SWAPBLK_NONE); 381 scan->u.bmu_bitmap = 0; 382 scan->bm_bighint = 0; 383 return (blk); 384 } 385 range1 = 0; 386 count1 = count - 1; 387 num_shifts = fls(count1); 388 mask = scan->u.bmu_bitmap; 389 while (mask != 0 && num_shifts > 0) { 390 /* 391 * If bit i is set in mask, then bits in [i, i+range1] are set 392 * in scan->u.bmu_bitmap. The value of range1 is equal to 393 * count1 >> num_shifts. Grow range and reduce num_shifts to 0, 394 * while preserving these invariants. The updates to mask leave 395 * fewer bits set, but each bit that remains set represents a 396 * longer string of consecutive bits set in scan->u.bmu_bitmap. 397 */ 398 num_shifts--; 399 range_ext = range1 + ((count1 >> num_shifts) & 1); 400 mask &= mask >> range_ext; 401 range1 += range_ext; 402 } 403 if (mask == 0) { 404 /* 405 * Update bighint. There is no allocation bigger than range1 406 * available in this leaf. 407 */ 408 scan->bm_bighint = range1; 409 return (SWAPBLK_NONE); 410 } 411 412 /* 413 * Discard any candidates that appear before the cursor. 414 */ 415 lo = cursor - blk; 416 mask &= ~(u_daddr_t)0 << lo; 417 418 if (mask == 0) 419 return (SWAPBLK_NONE); 420 421 /* 422 * The least significant set bit in mask marks the start of the first 423 * available range of sufficient size. Clear all the bits but that one, 424 * and then perform a binary search to find its position. 425 */ 426 mask &= -mask; 427 hi = BLIST_BMAP_RADIX - count1; 428 while (lo + 1 < hi) { 429 mid = (lo + hi) >> 1; 430 if ((mask >> mid) != 0) 431 lo = mid; 432 else 433 hi = mid; 434 } 435 436 /* 437 * Set in mask exactly the bits being allocated, and clear them from 438 * the set of available bits. 439 */ 440 mask = (mask << count) - mask; 441 scan->u.bmu_bitmap &= ~mask; 442 return (blk + lo); 443 } 444 445 /* 446 * blist_meta_alloc() - allocate at a meta in the radix tree. 447 * 448 * Attempt to allocate at a meta node. If we can't, we update 449 * bighint and return a failure. Updating bighint optimize future 450 * calls that hit this node. We have to check for our collapse cases 451 * and we have a few optimizations strewn in as well. 452 */ 453 454 static daddr_t 455 blst_meta_alloc(blmeta_t *scan, daddr_t blk, daddr_t count, daddr_t radix, 456 daddr_t skip, daddr_t cursor) 457 { 458 daddr_t i, next_skip, r; 459 int child; 460 bool scan_from_start; 461 462 if (scan->u.bmu_avail < count) { 463 /* 464 * The meta node's hint must be too large if the allocation 465 * exceeds the number of free blocks. Reduce the hint, and 466 * return failure. 467 */ 468 scan->bm_bighint = scan->u.bmu_avail; 469 return (SWAPBLK_NONE); 470 } 471 next_skip = skip / BLIST_META_RADIX; 472 473 /* 474 * An ALL-FREE meta node requires special handling before allocating 475 * any of its blocks. 476 */ 477 if (scan->u.bmu_avail == radix) { 478 radix /= BLIST_META_RADIX; 479 480 /* 481 * Reinitialize each of the meta node's children. An ALL-FREE 482 * meta node cannot have a terminator in any subtree. 483 */ 484 for (i = 1; i <= skip; i += next_skip) { 485 if (next_skip == 1) 486 scan[i].u.bmu_bitmap = (u_daddr_t)-1; 487 else 488 scan[i].u.bmu_avail = radix; 489 scan[i].bm_bighint = radix; 490 } 491 } else { 492 radix /= BLIST_META_RADIX; 493 } 494 495 if (count > radix) { 496 /* 497 * The allocation exceeds the number of blocks that are 498 * managed by a subtree of this meta node. 499 */ 500 panic("allocation too large"); 501 } 502 scan_from_start = cursor == blk; 503 child = (cursor - blk) / radix; 504 blk += child * radix; 505 for (i = 1 + child * next_skip; i <= skip; i += next_skip) { 506 if (count <= scan[i].bm_bighint) { 507 /* 508 * The allocation might fit in the i'th subtree. 509 */ 510 if (next_skip == 1) { 511 r = blst_leaf_alloc(&scan[i], blk, count, 512 cursor > blk ? cursor : blk); 513 } else { 514 r = blst_meta_alloc(&scan[i], blk, count, 515 radix, next_skip - 1, cursor > blk ? 516 cursor : blk); 517 } 518 if (r != SWAPBLK_NONE) { 519 scan->u.bmu_avail -= count; 520 return (r); 521 } 522 } else if (scan[i].bm_bighint == (daddr_t)-1) { 523 /* 524 * Terminator 525 */ 526 break; 527 } 528 blk += radix; 529 } 530 531 /* 532 * We couldn't allocate count in this subtree, update bighint. 533 */ 534 if (scan_from_start && scan->bm_bighint >= count) 535 scan->bm_bighint = count - 1; 536 537 return (SWAPBLK_NONE); 538 } 539 540 /* 541 * BLST_LEAF_FREE() - free allocated block from leaf bitmap 542 * 543 */ 544 545 static void 546 blst_leaf_free( 547 blmeta_t *scan, 548 daddr_t blk, 549 int count 550 ) { 551 /* 552 * free some data in this bitmap 553 * 554 * e.g. 555 * 0000111111111110000 556 * \_________/\__/ 557 * v n 558 */ 559 int n = blk & (BLIST_BMAP_RADIX - 1); 560 u_daddr_t mask; 561 562 mask = ((u_daddr_t)-1 << n) & 563 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n)); 564 565 if (scan->u.bmu_bitmap & mask) 566 panic("blst_radix_free: freeing free block"); 567 scan->u.bmu_bitmap |= mask; 568 569 /* 570 * We could probably do a better job here. We are required to make 571 * bighint at least as large as the biggest contiguous block of 572 * data. If we just shoehorn it, a little extra overhead will 573 * be incured on the next allocation (but only that one typically). 574 */ 575 scan->bm_bighint = BLIST_BMAP_RADIX; 576 } 577 578 /* 579 * BLST_META_FREE() - free allocated blocks from radix tree meta info 580 * 581 * This support routine frees a range of blocks from the bitmap. 582 * The range must be entirely enclosed by this radix node. If a 583 * meta node, we break the range down recursively to free blocks 584 * in subnodes (which means that this code can free an arbitrary 585 * range whereas the allocation code cannot allocate an arbitrary 586 * range). 587 */ 588 589 static void 590 blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, daddr_t radix, 591 daddr_t skip, daddr_t blk) 592 { 593 daddr_t i, next_skip, v; 594 int child; 595 596 #if 0 597 printf("free (%llx,%lld) FROM (%llx,%lld)\n", 598 (long long)freeBlk, (long long)count, 599 (long long)blk, (long long)radix 600 ); 601 #endif 602 next_skip = skip / BLIST_META_RADIX; 603 604 if (scan->u.bmu_avail == 0) { 605 /* 606 * ALL-ALLOCATED special case, with possible 607 * shortcut to ALL-FREE special case. 608 */ 609 scan->u.bmu_avail = count; 610 scan->bm_bighint = count; 611 612 if (count != radix) { 613 for (i = 1; i <= skip; i += next_skip) { 614 if (scan[i].bm_bighint == (daddr_t)-1) 615 break; 616 scan[i].bm_bighint = 0; 617 if (next_skip == 1) { 618 scan[i].u.bmu_bitmap = 0; 619 } else { 620 scan[i].u.bmu_avail = 0; 621 } 622 } 623 /* fall through */ 624 } 625 } else { 626 scan->u.bmu_avail += count; 627 /* scan->bm_bighint = radix; */ 628 } 629 630 /* 631 * ALL-FREE special case. 632 */ 633 634 if (scan->u.bmu_avail == radix) 635 return; 636 if (scan->u.bmu_avail > radix) 637 panic("blst_meta_free: freeing already free blocks (%lld) %lld/%lld", 638 (long long)count, (long long)scan->u.bmu_avail, 639 (long long)radix); 640 641 /* 642 * Break the free down into its components 643 */ 644 645 radix /= BLIST_META_RADIX; 646 647 child = (freeBlk - blk) / radix; 648 blk += child * radix; 649 i = 1 + child * next_skip; 650 while (i <= skip && blk < freeBlk + count) { 651 v = blk + radix - freeBlk; 652 if (v > count) 653 v = count; 654 655 if (scan->bm_bighint == (daddr_t)-1) 656 panic("blst_meta_free: freeing unexpected range"); 657 658 if (next_skip == 1) { 659 blst_leaf_free(&scan[i], freeBlk, v); 660 } else { 661 blst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk); 662 } 663 if (scan->bm_bighint < scan[i].bm_bighint) 664 scan->bm_bighint = scan[i].bm_bighint; 665 count -= v; 666 freeBlk += v; 667 blk += radix; 668 i += next_skip; 669 } 670 } 671 672 /* 673 * BLIST_RADIX_COPY() - copy one radix tree to another 674 * 675 * Locates free space in the source tree and frees it in the destination 676 * tree. The space may not already be free in the destination. 677 */ 678 679 static void blst_copy( 680 blmeta_t *scan, 681 daddr_t blk, 682 daddr_t radix, 683 daddr_t skip, 684 blist_t dest, 685 daddr_t count 686 ) { 687 daddr_t i, next_skip; 688 689 /* 690 * Leaf node 691 */ 692 693 if (radix == BLIST_BMAP_RADIX) { 694 u_daddr_t v = scan->u.bmu_bitmap; 695 696 if (v == (u_daddr_t)-1) { 697 blist_free(dest, blk, count); 698 } else if (v != 0) { 699 int i; 700 701 for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) { 702 if (v & ((u_daddr_t)1 << i)) 703 blist_free(dest, blk + i, 1); 704 } 705 } 706 return; 707 } 708 709 /* 710 * Meta node 711 */ 712 713 if (scan->u.bmu_avail == 0) { 714 /* 715 * Source all allocated, leave dest allocated 716 */ 717 return; 718 } 719 if (scan->u.bmu_avail == radix) { 720 /* 721 * Source all free, free entire dest 722 */ 723 if (count < radix) 724 blist_free(dest, blk, count); 725 else 726 blist_free(dest, blk, radix); 727 return; 728 } 729 730 731 radix /= BLIST_META_RADIX; 732 next_skip = skip / BLIST_META_RADIX; 733 734 for (i = 1; count && i <= skip; i += next_skip) { 735 if (scan[i].bm_bighint == (daddr_t)-1) 736 break; 737 738 if (count >= radix) { 739 blst_copy( 740 &scan[i], 741 blk, 742 radix, 743 next_skip - 1, 744 dest, 745 radix 746 ); 747 count -= radix; 748 } else { 749 if (count) { 750 blst_copy( 751 &scan[i], 752 blk, 753 radix, 754 next_skip - 1, 755 dest, 756 count 757 ); 758 } 759 count = 0; 760 } 761 blk += radix; 762 } 763 } 764 765 /* 766 * BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap 767 * 768 * This routine allocates all blocks in the specified range 769 * regardless of any existing allocations in that range. Returns 770 * the number of blocks allocated by the call. 771 */ 772 773 static daddr_t 774 blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count) 775 { 776 int n = blk & (BLIST_BMAP_RADIX - 1); 777 daddr_t nblks; 778 u_daddr_t mask; 779 780 mask = ((u_daddr_t)-1 << n) & 781 ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n)); 782 783 /* Count the number of blocks that we are allocating. */ 784 nblks = bitcount64(scan->u.bmu_bitmap & mask); 785 786 scan->u.bmu_bitmap &= ~mask; 787 return (nblks); 788 } 789 790 /* 791 * BLIST_META_FILL() - allocate specific blocks at a meta node 792 * 793 * This routine allocates the specified range of blocks, 794 * regardless of any existing allocations in the range. The 795 * range must be within the extent of this node. Returns the 796 * number of blocks allocated by the call. 797 */ 798 static daddr_t 799 blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, daddr_t radix, 800 daddr_t skip, daddr_t blk) 801 { 802 daddr_t i, nblks, next_skip, v; 803 int child; 804 805 if (count > radix) { 806 /* 807 * The allocation exceeds the number of blocks that are 808 * managed by this meta node. 809 */ 810 panic("allocation too large"); 811 } 812 if (count == radix || scan->u.bmu_avail == 0) { 813 /* 814 * ALL-ALLOCATED special case 815 */ 816 nblks = scan->u.bmu_avail; 817 scan->u.bmu_avail = 0; 818 scan->bm_bighint = 0; 819 return nblks; 820 } 821 next_skip = skip / BLIST_META_RADIX; 822 823 /* 824 * An ALL-FREE meta node requires special handling before allocating 825 * any of its blocks. 826 */ 827 if (scan->u.bmu_avail == radix) { 828 radix /= BLIST_META_RADIX; 829 830 /* 831 * Reinitialize each of the meta node's children. An ALL-FREE 832 * meta node cannot have a terminator in any subtree. 833 */ 834 for (i = 1; i <= skip; i += next_skip) { 835 if (next_skip == 1) { 836 scan[i].u.bmu_bitmap = (u_daddr_t)-1; 837 scan[i].bm_bighint = BLIST_BMAP_RADIX; 838 } else { 839 scan[i].bm_bighint = radix; 840 scan[i].u.bmu_avail = radix; 841 } 842 } 843 } else { 844 radix /= BLIST_META_RADIX; 845 } 846 847 nblks = 0; 848 child = (allocBlk - blk) / radix; 849 blk += child * radix; 850 i = 1 + child * next_skip; 851 while (i <= skip && blk < allocBlk + count) { 852 v = blk + radix - allocBlk; 853 if (v > count) 854 v = count; 855 856 if (scan->bm_bighint == (daddr_t)-1) 857 panic("blst_meta_fill: filling unexpected range"); 858 859 if (next_skip == 1) { 860 nblks += blst_leaf_fill(&scan[i], allocBlk, v); 861 } else { 862 nblks += blst_meta_fill(&scan[i], allocBlk, v, 863 radix, next_skip - 1, blk); 864 } 865 count -= v; 866 allocBlk += v; 867 blk += radix; 868 i += next_skip; 869 } 870 scan->u.bmu_avail -= nblks; 871 return nblks; 872 } 873 874 /* 875 * BLST_RADIX_INIT() - initialize radix tree 876 * 877 * Initialize our meta structures and bitmaps and calculate the exact 878 * amount of space required to manage 'count' blocks - this space may 879 * be considerably less than the calculated radix due to the large 880 * RADIX values we use. 881 */ 882 883 static daddr_t 884 blst_radix_init(blmeta_t *scan, daddr_t radix, daddr_t skip, daddr_t count) 885 { 886 daddr_t i, memindex, next_skip; 887 888 memindex = 0; 889 890 /* 891 * Leaf node 892 */ 893 894 if (radix == BLIST_BMAP_RADIX) { 895 if (scan) { 896 scan->bm_bighint = 0; 897 scan->u.bmu_bitmap = 0; 898 } 899 return(memindex); 900 } 901 902 /* 903 * Meta node. If allocating the entire object we can special 904 * case it. However, we need to figure out how much memory 905 * is required to manage 'count' blocks, so we continue on anyway. 906 */ 907 908 if (scan) { 909 scan->bm_bighint = 0; 910 scan->u.bmu_avail = 0; 911 } 912 913 radix /= BLIST_META_RADIX; 914 next_skip = skip / BLIST_META_RADIX; 915 916 for (i = 1; i <= skip; i += next_skip) { 917 if (count >= radix) { 918 /* 919 * Allocate the entire object 920 */ 921 memindex = i + blst_radix_init( 922 ((scan) ? &scan[i] : NULL), 923 radix, 924 next_skip - 1, 925 radix 926 ); 927 count -= radix; 928 } else if (count > 0) { 929 /* 930 * Allocate a partial object 931 */ 932 memindex = i + blst_radix_init( 933 ((scan) ? &scan[i] : NULL), 934 radix, 935 next_skip - 1, 936 count 937 ); 938 count = 0; 939 } else { 940 /* 941 * Add terminator and break out 942 */ 943 if (scan) 944 scan[i].bm_bighint = (daddr_t)-1; 945 break; 946 } 947 } 948 if (memindex < i) 949 memindex = i; 950 return(memindex); 951 } 952 953 #ifdef BLIST_DEBUG 954 955 static void 956 blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, daddr_t skip, 957 int tab) 958 { 959 daddr_t i, next_skip; 960 961 if (radix == BLIST_BMAP_RADIX) { 962 printf( 963 "%*.*s(%08llx,%lld): bitmap %016llx big=%lld\n", 964 tab, tab, "", 965 (long long)blk, (long long)radix, 966 (long long)scan->u.bmu_bitmap, 967 (long long)scan->bm_bighint 968 ); 969 return; 970 } 971 972 if (scan->u.bmu_avail == 0) { 973 printf( 974 "%*.*s(%08llx,%lld) ALL ALLOCATED\n", 975 tab, tab, "", 976 (long long)blk, 977 (long long)radix 978 ); 979 return; 980 } 981 if (scan->u.bmu_avail == radix) { 982 printf( 983 "%*.*s(%08llx,%lld) ALL FREE\n", 984 tab, tab, "", 985 (long long)blk, 986 (long long)radix 987 ); 988 return; 989 } 990 991 printf( 992 "%*.*s(%08llx,%lld): subtree (%lld/%lld) big=%lld {\n", 993 tab, tab, "", 994 (long long)blk, (long long)radix, 995 (long long)scan->u.bmu_avail, 996 (long long)radix, 997 (long long)scan->bm_bighint 998 ); 999 1000 radix /= BLIST_META_RADIX; 1001 next_skip = skip / BLIST_META_RADIX; 1002 tab += 4; 1003 1004 for (i = 1; i <= skip; i += next_skip) { 1005 if (scan[i].bm_bighint == (daddr_t)-1) { 1006 printf( 1007 "%*.*s(%08llx,%lld): Terminator\n", 1008 tab, tab, "", 1009 (long long)blk, (long long)radix 1010 ); 1011 break; 1012 } 1013 blst_radix_print( 1014 &scan[i], 1015 blk, 1016 radix, 1017 next_skip - 1, 1018 tab 1019 ); 1020 blk += radix; 1021 } 1022 tab -= 4; 1023 1024 printf( 1025 "%*.*s}\n", 1026 tab, tab, "" 1027 ); 1028 } 1029 1030 #endif 1031 1032 #ifdef BLIST_DEBUG 1033 1034 int 1035 main(int ac, char **av) 1036 { 1037 int size = 1024; 1038 int i; 1039 blist_t bl; 1040 1041 for (i = 1; i < ac; ++i) { 1042 const char *ptr = av[i]; 1043 if (*ptr != '-') { 1044 size = strtol(ptr, NULL, 0); 1045 continue; 1046 } 1047 ptr += 2; 1048 fprintf(stderr, "Bad option: %s\n", ptr - 2); 1049 exit(1); 1050 } 1051 bl = blist_create(size, M_WAITOK); 1052 blist_free(bl, 0, size); 1053 1054 for (;;) { 1055 char buf[1024]; 1056 long long da = 0; 1057 long long count = 0; 1058 1059 printf("%lld/%lld/%lld> ", (long long)blist_avail(bl), 1060 (long long)size, (long long)bl->bl_radix); 1061 fflush(stdout); 1062 if (fgets(buf, sizeof(buf), stdin) == NULL) 1063 break; 1064 switch(buf[0]) { 1065 case 'r': 1066 if (sscanf(buf + 1, "%lld", &count) == 1) { 1067 blist_resize(&bl, count, 1, M_WAITOK); 1068 } else { 1069 printf("?\n"); 1070 } 1071 case 'p': 1072 blist_print(bl); 1073 break; 1074 case 'a': 1075 if (sscanf(buf + 1, "%lld", &count) == 1) { 1076 daddr_t blk = blist_alloc(bl, count); 1077 printf(" R=%08llx\n", (long long)blk); 1078 } else { 1079 printf("?\n"); 1080 } 1081 break; 1082 case 'f': 1083 if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) { 1084 blist_free(bl, da, count); 1085 } else { 1086 printf("?\n"); 1087 } 1088 break; 1089 case 'l': 1090 if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) { 1091 printf(" n=%jd\n", 1092 (intmax_t)blist_fill(bl, da, count)); 1093 } else { 1094 printf("?\n"); 1095 } 1096 break; 1097 case '?': 1098 case 'h': 1099 puts( 1100 "p -print\n" 1101 "a %d -allocate\n" 1102 "f %x %d -free\n" 1103 "l %x %d -fill\n" 1104 "r %d -resize\n" 1105 "h/? -help" 1106 ); 1107 break; 1108 default: 1109 printf("?\n"); 1110 break; 1111 } 1112 } 1113 return(0); 1114 } 1115 1116 void 1117 panic(const char *ctl, ...) 1118 { 1119 va_list va; 1120 1121 va_start(va, ctl); 1122 vfprintf(stderr, ctl, va); 1123 fprintf(stderr, "\n"); 1124 va_end(va); 1125 exit(1); 1126 } 1127 1128 #endif 1129
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