The Design and Implementation of the FreeBSD Operating System, Second Edition
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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 then 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  *      Unlike the rlist code, the blist code wires all necessary memory at
   56  *      creation time.  Neither allocations nor frees require interaction with
   57  *      the memory subsystem.  In contrast, the rlist code may allocate memory 
   58  *      on an rlist_free() call.  The non-blocking features of the blist code
   59  *      are used to great advantage in the swap code (vm/nswap_pager.c).  The
   60  *      rlist code uses a little less overall memory then the blist code (but
   61  *      due to swap interleaving not all that much less), but the blist code 
   62  *      scales much, much better.
   63  *
   64  *      LAYOUT: The radix tree is layed out recursively using a
   65  *      linear array.  Each meta node is immediately followed (layed out
   66  *      sequentially in memory) by BLIST_META_RADIX lower level nodes.  This
   67  *      is a recursive structure but one that can be easily scanned through
   68  *      a very simple 'skip' calculation.  In order to support large radixes, 
   69  *      portions of the tree may reside outside our memory allocation.  We 
   70  *      handle this with an early-termination optimization (when bighint is 
   71  *      set to -1) on the scan.  The memory allocation is only large enough 
   72  *      to cover the number of blocks requested at creation time even if it
   73  *      must be encompassed in larger root-node radix.
   74  *
   75  *      NOTE: the allocator cannot currently allocate more then 
   76  *      BLIST_BMAP_RADIX blocks per call.  It will panic with 'allocation too 
   77  *      large' if you try.  This is an area that could use improvement.  The 
   78  *      radix is large enough that this restriction does not effect the swap 
   79  *      system, though.  Currently only the allocation code is effected by
   80  *      this algorithmic unfeature.  The freeing code can handle arbitrary
   81  *      ranges.
   82  *
   83  *      This code can be compiled stand-alone for debugging.
   84  */
   85 
   86 #include <sys/cdefs.h>
   87 __FBSDID("$FreeBSD$");
   88 
   89 #ifdef _KERNEL
   90 
   91 #include <sys/param.h>
   92 #include <sys/systm.h>
   93 #include <sys/lock.h>
   94 #include <sys/kernel.h>
   95 #include <sys/blist.h>
   96 #include <sys/malloc.h>
   97 #include <sys/proc.h>
   98 #include <sys/mutex.h> 
   99 
  100 #else
  101 
  102 #ifndef BLIST_NO_DEBUG
  103 #define BLIST_DEBUG
  104 #endif
  105 
  106 #define SWAPBLK_NONE ((daddr_t)-1)
  107 
  108 #include <sys/types.h>
  109 #include <stdio.h>
  110 #include <string.h>
  111 #include <stdlib.h>
  112 #include <stdarg.h>
  113 
  114 #define malloc(a,b,c)   calloc(a, 1)
  115 #define free(a,b)       free(a)
  116 
  117 typedef unsigned int u_daddr_t;
  118 
  119 #include <sys/blist.h>
  120 
  121 void panic(const char *ctl, ...);
  122 
  123 #endif
  124 
  125 /*
  126  * static support functions
  127  */
  128 
  129 static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count);
  130 static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t blk, 
  131                                 daddr_t count, daddr_t radix, int skip);
  132 static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
  133 static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, 
  134                                         daddr_t radix, int skip, daddr_t blk);
  135 static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, 
  136                                 daddr_t skip, blist_t dest, daddr_t count);
  137 static int blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count);
  138 static int blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count,
  139                                 daddr_t radix, int skip, daddr_t blk);
  140 static daddr_t  blst_radix_init(blmeta_t *scan, daddr_t radix, 
  141                                                 int skip, daddr_t count);
  142 #ifndef _KERNEL
  143 static void     blst_radix_print(blmeta_t *scan, daddr_t blk, 
  144                                         daddr_t radix, int skip, int tab);
  145 #endif
  146 
  147 #ifdef _KERNEL
  148 static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
  149 #endif
  150 
  151 /*
  152  * blist_create() - create a blist capable of handling up to the specified
  153  *                  number of blocks
  154  *
  155  *      blocks must be greater then 0
  156  *
  157  *      The smallest blist consists of a single leaf node capable of 
  158  *      managing BLIST_BMAP_RADIX blocks.
  159  */
  160 
  161 blist_t 
  162 blist_create(daddr_t blocks)
  163 {
  164         blist_t bl;
  165         int radix;
  166         int skip = 0;
  167 
  168         /*
  169          * Calculate radix and skip field used for scanning.
  170          */
  171         radix = BLIST_BMAP_RADIX;
  172 
  173         while (radix < blocks) {
  174                 radix *= BLIST_META_RADIX;
  175                 skip = (skip + 1) * BLIST_META_RADIX;
  176         }
  177 
  178         bl = malloc(sizeof(struct blist), M_SWAP, M_WAITOK | M_ZERO);
  179 
  180         bl->bl_blocks = blocks;
  181         bl->bl_radix = radix;
  182         bl->bl_skip = skip;
  183         bl->bl_rootblks = 1 +
  184             blst_radix_init(NULL, bl->bl_radix, bl->bl_skip, blocks);
  185         bl->bl_root = malloc(sizeof(blmeta_t) * bl->bl_rootblks, M_SWAP, M_WAITOK);
  186 
  187 #if defined(BLIST_DEBUG)
  188         printf(
  189                 "BLIST representing %lld blocks (%lld MB of swap)"
  190                 ", requiring %lldK of ram\n",
  191                 (long long)bl->bl_blocks,
  192                 (long long)bl->bl_blocks * 4 / 1024,
  193                 (long long)(bl->bl_rootblks * sizeof(blmeta_t) + 1023) / 1024
  194         );
  195         printf("BLIST raw radix tree contains %lld records\n",
  196             (long long)bl->bl_rootblks);
  197 #endif
  198         blst_radix_init(bl->bl_root, bl->bl_radix, bl->bl_skip, blocks);
  199 
  200         return(bl);
  201 }
  202 
  203 void 
  204 blist_destroy(blist_t bl)
  205 {
  206         free(bl->bl_root, M_SWAP);
  207         free(bl, M_SWAP);
  208 }
  209 
  210 /*
  211  * blist_alloc() - reserve space in the block bitmap.  Return the base
  212  *                   of a contiguous region or SWAPBLK_NONE if space could
  213  *                   not be allocated.
  214  */
  215 
  216 daddr_t 
  217 blist_alloc(blist_t bl, daddr_t count)
  218 {
  219         daddr_t blk = SWAPBLK_NONE;
  220 
  221         if (bl) {
  222                 if (bl->bl_radix == BLIST_BMAP_RADIX)
  223                         blk = blst_leaf_alloc(bl->bl_root, 0, count);
  224                 else
  225                         blk = blst_meta_alloc(bl->bl_root, 0, count, bl->bl_radix, bl->bl_skip);
  226                 if (blk != SWAPBLK_NONE)
  227                         bl->bl_free -= count;
  228         }
  229         return(blk);
  230 }
  231 
  232 /*
  233  * blist_free() -       free up space in the block bitmap.  Return the base
  234  *                      of a contiguous region.  Panic if an inconsistancy is
  235  *                      found.
  236  */
  237 
  238 void 
  239 blist_free(blist_t bl, daddr_t blkno, daddr_t count)
  240 {
  241         if (bl) {
  242                 if (bl->bl_radix == BLIST_BMAP_RADIX)
  243                         blst_leaf_free(bl->bl_root, blkno, count);
  244                 else
  245                         blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix, bl->bl_skip, 0);
  246                 bl->bl_free += count;
  247         }
  248 }
  249 
  250 /*
  251  * blist_fill() -       mark a region in the block bitmap as off-limits
  252  *                      to the allocator (i.e. allocate it), ignoring any
  253  *                      existing allocations.  Return the number of blocks
  254  *                      actually filled that were free before the call.
  255  */
  256 
  257 int
  258 blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
  259 {
  260         int filled;
  261 
  262         if (bl) {
  263                 if (bl->bl_radix == BLIST_BMAP_RADIX)
  264                         filled = blst_leaf_fill(bl->bl_root, blkno, count);
  265                 else
  266                         filled = blst_meta_fill(bl->bl_root, blkno, count,
  267                             bl->bl_radix, bl->bl_skip, 0);
  268                 bl->bl_free -= filled;
  269                 return filled;
  270         } else
  271                 return 0;
  272 }
  273 
  274 /*
  275  * blist_resize() -     resize an existing radix tree to handle the
  276  *                      specified number of blocks.  This will reallocate
  277  *                      the tree and transfer the previous bitmap to the new
  278  *                      one.  When extending the tree you can specify whether
  279  *                      the new blocks are to left allocated or freed.
  280  */
  281 
  282 void
  283 blist_resize(blist_t *pbl, daddr_t count, int freenew)
  284 {
  285     blist_t newbl = blist_create(count);
  286     blist_t save = *pbl;
  287 
  288     *pbl = newbl;
  289     if (count > save->bl_blocks)
  290             count = save->bl_blocks;
  291     blst_copy(save->bl_root, 0, save->bl_radix, save->bl_skip, newbl, count);
  292 
  293     /*
  294      * If resizing upwards, should we free the new space or not?
  295      */
  296     if (freenew && count < newbl->bl_blocks) {
  297             blist_free(newbl, count, newbl->bl_blocks - count);
  298     }
  299     blist_destroy(save);
  300 }
  301 
  302 #ifdef BLIST_DEBUG
  303 
  304 /*
  305  * blist_print()    - dump radix tree
  306  */
  307 
  308 void
  309 blist_print(blist_t bl)
  310 {
  311         printf("BLIST {\n");
  312         blst_radix_print(bl->bl_root, 0, bl->bl_radix, bl->bl_skip, 4);
  313         printf("}\n");
  314 }
  315 
  316 #endif
  317 
  318 /************************************************************************
  319  *                        ALLOCATION SUPPORT FUNCTIONS                  *
  320  ************************************************************************
  321  *
  322  *      These support functions do all the actual work.  They may seem 
  323  *      rather longish, but that's because I've commented them up.  The
  324  *      actual code is straight forward.
  325  *
  326  */
  327 
  328 /*
  329  * blist_leaf_alloc() - allocate at a leaf in the radix tree (a bitmap).
  330  *
  331  *      This is the core of the allocator and is optimized for the 1 block
  332  *      and the BLIST_BMAP_RADIX block allocation cases.  Other cases are
  333  *      somewhat slower.  The 1 block allocation case is log2 and extremely
  334  *      quick.
  335  */
  336 
  337 static daddr_t
  338 blst_leaf_alloc(
  339         blmeta_t *scan,
  340         daddr_t blk,
  341         int count
  342 ) {
  343         u_daddr_t orig = scan->u.bmu_bitmap;
  344 
  345         if (orig == 0) {
  346                 /*
  347                  * Optimize bitmap all-allocated case.  Also, count = 1
  348                  * case assumes at least 1 bit is free in the bitmap, so
  349                  * we have to take care of this case here.
  350                  */
  351                 scan->bm_bighint = 0;
  352                 return(SWAPBLK_NONE);
  353         }
  354         if (count == 1) {
  355                 /*
  356                  * Optimized code to allocate one bit out of the bitmap
  357                  */
  358                 u_daddr_t mask;
  359                 int j = BLIST_BMAP_RADIX/2;
  360                 int r = 0;
  361 
  362                 mask = (u_daddr_t)-1 >> (BLIST_BMAP_RADIX/2);
  363 
  364                 while (j) {
  365                         if ((orig & mask) == 0) {
  366                             r += j;
  367                             orig >>= j;
  368                         }
  369                         j >>= 1;
  370                         mask >>= j;
  371                 }
  372                 scan->u.bmu_bitmap &= ~(1 << r);
  373                 return(blk + r);
  374         }
  375         if (count <= BLIST_BMAP_RADIX) {
  376                 /*
  377                  * non-optimized code to allocate N bits out of the bitmap.
  378                  * The more bits, the faster the code runs.  It will run
  379                  * the slowest allocating 2 bits, but since there aren't any
  380                  * memory ops in the core loop (or shouldn't be, anyway),
  381                  * you probably won't notice the difference.
  382                  */
  383                 int j;
  384                 int n = BLIST_BMAP_RADIX - count;
  385                 u_daddr_t mask;
  386 
  387                 mask = (u_daddr_t)-1 >> n;
  388 
  389                 for (j = 0; j <= n; ++j) {
  390                         if ((orig & mask) == mask) {
  391                                 scan->u.bmu_bitmap &= ~mask;
  392                                 return(blk + j);
  393                         }
  394                         mask = (mask << 1);
  395                 }
  396         }
  397         /*
  398          * We couldn't allocate count in this subtree, update bighint.
  399          */
  400         scan->bm_bighint = count - 1;
  401         return(SWAPBLK_NONE);
  402 }
  403 
  404 /*
  405  * blist_meta_alloc() - allocate at a meta in the radix tree.
  406  *
  407  *      Attempt to allocate at a meta node.  If we can't, we update
  408  *      bighint and return a failure.  Updating bighint optimize future
  409  *      calls that hit this node.  We have to check for our collapse cases
  410  *      and we have a few optimizations strewn in as well.
  411  */
  412 
  413 static daddr_t
  414 blst_meta_alloc(
  415         blmeta_t *scan, 
  416         daddr_t blk,
  417         daddr_t count,
  418         daddr_t radix, 
  419         int skip
  420 ) {
  421         int i;
  422         int next_skip = ((u_int)skip / BLIST_META_RADIX);
  423 
  424         if (scan->u.bmu_avail == 0)  {
  425                 /*
  426                  * ALL-ALLOCATED special case
  427                  */
  428                 scan->bm_bighint = count;
  429                 return(SWAPBLK_NONE);
  430         }
  431 
  432         if (scan->u.bmu_avail == radix) {
  433                 radix /= BLIST_META_RADIX;
  434 
  435                 /*
  436                  * ALL-FREE special case, initialize uninitialize
  437                  * sublevel.
  438                  */
  439                 for (i = 1; i <= skip; i += next_skip) {
  440                         if (scan[i].bm_bighint == (daddr_t)-1)
  441                                 break;
  442                         if (next_skip == 1) {
  443                                 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
  444                                 scan[i].bm_bighint = BLIST_BMAP_RADIX;
  445                         } else {
  446                                 scan[i].bm_bighint = radix;
  447                                 scan[i].u.bmu_avail = radix;
  448                         }
  449                 }
  450         } else {
  451                 radix /= BLIST_META_RADIX;
  452         }
  453 
  454         for (i = 1; i <= skip; i += next_skip) {
  455                 if (count <= scan[i].bm_bighint) {
  456                         /*
  457                          * count fits in object
  458                          */
  459                         daddr_t r;
  460                         if (next_skip == 1) {
  461                                 r = blst_leaf_alloc(&scan[i], blk, count);
  462                         } else {
  463                                 r = blst_meta_alloc(&scan[i], blk, count, radix, next_skip - 1);
  464                         }
  465                         if (r != SWAPBLK_NONE) {
  466                                 scan->u.bmu_avail -= count;
  467                                 if (scan->bm_bighint > scan->u.bmu_avail)
  468                                         scan->bm_bighint = scan->u.bmu_avail;
  469                                 return(r);
  470                         }
  471                 } else if (scan[i].bm_bighint == (daddr_t)-1) {
  472                         /*
  473                          * Terminator
  474                          */
  475                         break;
  476                 } else if (count > radix) {
  477                         /*
  478                          * count does not fit in object even if it were
  479                          * complete free.
  480                          */
  481                         panic("blist_meta_alloc: allocation too large");
  482                 }
  483                 blk += radix;
  484         }
  485 
  486         /*
  487          * We couldn't allocate count in this subtree, update bighint.
  488          */
  489         if (scan->bm_bighint >= count)
  490                 scan->bm_bighint = count - 1;
  491         return(SWAPBLK_NONE);
  492 }
  493 
  494 /*
  495  * BLST_LEAF_FREE() -   free allocated block from leaf bitmap
  496  *
  497  */
  498 
  499 static void
  500 blst_leaf_free(
  501         blmeta_t *scan,
  502         daddr_t blk,
  503         int count
  504 ) {
  505         /*
  506          * free some data in this bitmap
  507          *
  508          * e.g.
  509          *      0000111111111110000
  510          *          \_________/\__/
  511          *              v        n
  512          */
  513         int n = blk & (BLIST_BMAP_RADIX - 1);
  514         u_daddr_t mask;
  515 
  516         mask = ((u_daddr_t)-1 << n) &
  517             ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
  518 
  519         if (scan->u.bmu_bitmap & mask)
  520                 panic("blst_radix_free: freeing free block");
  521         scan->u.bmu_bitmap |= mask;
  522 
  523         /*
  524          * We could probably do a better job here.  We are required to make
  525          * bighint at least as large as the biggest contiguous block of 
  526          * data.  If we just shoehorn it, a little extra overhead will
  527          * be incured on the next allocation (but only that one typically).
  528          */
  529         scan->bm_bighint = BLIST_BMAP_RADIX;
  530 }
  531 
  532 /*
  533  * BLST_META_FREE() - free allocated blocks from radix tree meta info
  534  *
  535  *      This support routine frees a range of blocks from the bitmap.
  536  *      The range must be entirely enclosed by this radix node.  If a
  537  *      meta node, we break the range down recursively to free blocks
  538  *      in subnodes (which means that this code can free an arbitrary
  539  *      range whereas the allocation code cannot allocate an arbitrary
  540  *      range).
  541  */
  542 
  543 static void 
  544 blst_meta_free(
  545         blmeta_t *scan, 
  546         daddr_t freeBlk,
  547         daddr_t count,
  548         daddr_t radix, 
  549         int skip,
  550         daddr_t blk
  551 ) {
  552         int i;
  553         int next_skip = ((u_int)skip / BLIST_META_RADIX);
  554 
  555 #if 0
  556         printf("FREE (%llx,%lld) FROM (%llx,%lld)\n",
  557             (long long)freeBlk, (long long)count,
  558             (long long)blk, (long long)radix
  559         );
  560 #endif
  561 
  562         if (scan->u.bmu_avail == 0) {
  563                 /*
  564                  * ALL-ALLOCATED special case, with possible
  565                  * shortcut to ALL-FREE special case.
  566                  */
  567                 scan->u.bmu_avail = count;
  568                 scan->bm_bighint = count;
  569 
  570                 if (count != radix)  {
  571                         for (i = 1; i <= skip; i += next_skip) {
  572                                 if (scan[i].bm_bighint == (daddr_t)-1)
  573                                         break;
  574                                 scan[i].bm_bighint = 0;
  575                                 if (next_skip == 1) {
  576                                         scan[i].u.bmu_bitmap = 0;
  577                                 } else {
  578                                         scan[i].u.bmu_avail = 0;
  579                                 }
  580                         }
  581                         /* fall through */
  582                 }
  583         } else {
  584                 scan->u.bmu_avail += count;
  585                 /* scan->bm_bighint = radix; */
  586         }
  587 
  588         /*
  589          * ALL-FREE special case.
  590          */
  591 
  592         if (scan->u.bmu_avail == radix)
  593                 return;
  594         if (scan->u.bmu_avail > radix)
  595                 panic("blst_meta_free: freeing already free blocks (%lld) %lld/%lld",
  596                     (long long)count, (long long)scan->u.bmu_avail,
  597                     (long long)radix);
  598 
  599         /*
  600          * Break the free down into its components
  601          */
  602 
  603         radix /= BLIST_META_RADIX;
  604 
  605         i = (freeBlk - blk) / radix;
  606         blk += i * radix;
  607         i = i * next_skip + 1;
  608 
  609         while (i <= skip && blk < freeBlk + count) {
  610                 daddr_t v;
  611 
  612                 v = blk + radix - freeBlk;
  613                 if (v > count)
  614                         v = count;
  615 
  616                 if (scan->bm_bighint == (daddr_t)-1)
  617                         panic("blst_meta_free: freeing unexpected range");
  618 
  619                 if (next_skip == 1) {
  620                         blst_leaf_free(&scan[i], freeBlk, v);
  621                 } else {
  622                         blst_meta_free(&scan[i], freeBlk, v, radix, next_skip - 1, blk);
  623                 }
  624                 if (scan->bm_bighint < scan[i].bm_bighint)
  625                     scan->bm_bighint = scan[i].bm_bighint;
  626                 count -= v;
  627                 freeBlk += v;
  628                 blk += radix;
  629                 i += next_skip;
  630         }
  631 }
  632 
  633 /*
  634  * BLIST_RADIX_COPY() - copy one radix tree to another
  635  *
  636  *      Locates free space in the source tree and frees it in the destination
  637  *      tree.  The space may not already be free in the destination.
  638  */
  639 
  640 static void blst_copy(
  641         blmeta_t *scan, 
  642         daddr_t blk,
  643         daddr_t radix, 
  644         daddr_t skip, 
  645         blist_t dest,
  646         daddr_t count
  647 ) {
  648         int next_skip;
  649         int i;
  650 
  651         /*
  652          * Leaf node
  653          */
  654 
  655         if (radix == BLIST_BMAP_RADIX) {
  656                 u_daddr_t v = scan->u.bmu_bitmap;
  657 
  658                 if (v == (u_daddr_t)-1) {
  659                         blist_free(dest, blk, count);
  660                 } else if (v != 0) {
  661                         int i;
  662 
  663                         for (i = 0; i < BLIST_BMAP_RADIX && i < count; ++i) {
  664                                 if (v & (1 << i))
  665                                         blist_free(dest, blk + i, 1);
  666                         }
  667                 }
  668                 return;
  669         }
  670 
  671         /*
  672          * Meta node
  673          */
  674 
  675         if (scan->u.bmu_avail == 0) {
  676                 /*
  677                  * Source all allocated, leave dest allocated
  678                  */
  679                 return;
  680         } 
  681         if (scan->u.bmu_avail == radix) {
  682                 /*
  683                  * Source all free, free entire dest
  684                  */
  685                 if (count < radix)
  686                         blist_free(dest, blk, count);
  687                 else
  688                         blist_free(dest, blk, radix);
  689                 return;
  690         }
  691 
  692 
  693         radix /= BLIST_META_RADIX;
  694         next_skip = ((u_int)skip / BLIST_META_RADIX);
  695 
  696         for (i = 1; count && i <= skip; i += next_skip) {
  697                 if (scan[i].bm_bighint == (daddr_t)-1)
  698                         break;
  699 
  700                 if (count >= radix) {
  701                         blst_copy(
  702                             &scan[i],
  703                             blk,
  704                             radix,
  705                             next_skip - 1,
  706                             dest,
  707                             radix
  708                         );
  709                         count -= radix;
  710                 } else {
  711                         if (count) {
  712                                 blst_copy(
  713                                     &scan[i],
  714                                     blk,
  715                                     radix,
  716                                     next_skip - 1,
  717                                     dest,
  718                                     count
  719                                 );
  720                         }
  721                         count = 0;
  722                 }
  723                 blk += radix;
  724         }
  725 }
  726 
  727 /*
  728  * BLST_LEAF_FILL() -   allocate specific blocks in leaf bitmap
  729  *
  730  *      This routine allocates all blocks in the specified range
  731  *      regardless of any existing allocations in that range.  Returns
  732  *      the number of blocks allocated by the call.
  733  */
  734 
  735 static int
  736 blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)
  737 {
  738         int n = blk & (BLIST_BMAP_RADIX - 1);
  739         int nblks;
  740         u_daddr_t mask, bitmap;
  741 
  742         mask = ((u_daddr_t)-1 << n) &
  743             ((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - count - n));
  744 
  745         /* Count the number of blocks we're about to allocate */
  746         bitmap = scan->u.bmu_bitmap & mask;
  747         for (nblks = 0; bitmap != 0; nblks++)
  748                 bitmap &= bitmap - 1;
  749 
  750         scan->u.bmu_bitmap &= ~mask;
  751         return nblks;
  752 }
  753 
  754 /*
  755  * BLIST_META_FILL() -  allocate specific blocks at a meta node
  756  *
  757  *      This routine allocates the specified range of blocks,
  758  *      regardless of any existing allocations in the range.  The
  759  *      range must be within the extent of this node.  Returns the
  760  *      number of blocks allocated by the call.
  761  */
  762 static int
  763 blst_meta_fill(
  764         blmeta_t *scan,
  765         daddr_t allocBlk,
  766         daddr_t count,
  767         daddr_t radix, 
  768         int skip,
  769         daddr_t blk
  770 ) {
  771         int i;
  772         int next_skip = ((u_int)skip / BLIST_META_RADIX);
  773         int nblks = 0;
  774 
  775         if (count == radix || scan->u.bmu_avail == 0)  {
  776                 /*
  777                  * ALL-ALLOCATED special case
  778                  */
  779                 nblks = scan->u.bmu_avail;
  780                 scan->u.bmu_avail = 0;
  781                 scan->bm_bighint = count;
  782                 return nblks;
  783         }
  784 
  785         if (scan->u.bmu_avail == radix) {
  786                 radix /= BLIST_META_RADIX;
  787 
  788                 /*
  789                  * ALL-FREE special case, initialize sublevel
  790                  */
  791                 for (i = 1; i <= skip; i += next_skip) {
  792                         if (scan[i].bm_bighint == (daddr_t)-1)
  793                                 break;
  794                         if (next_skip == 1) {
  795                                 scan[i].u.bmu_bitmap = (u_daddr_t)-1;
  796                                 scan[i].bm_bighint = BLIST_BMAP_RADIX;
  797                         } else {
  798                                 scan[i].bm_bighint = radix;
  799                                 scan[i].u.bmu_avail = radix;
  800                         }
  801                 }
  802         } else {
  803                 radix /= BLIST_META_RADIX;
  804         }
  805 
  806         if (count > radix)
  807                 panic("blist_meta_fill: allocation too large");
  808 
  809         i = (allocBlk - blk) / radix;
  810         blk += i * radix;
  811         i = i * next_skip + 1;
  812 
  813         while (i <= skip && blk < allocBlk + count) {
  814                 daddr_t v;
  815 
  816                 v = blk + radix - allocBlk;
  817                 if (v > count)
  818                         v = count;
  819 
  820                 if (scan->bm_bighint == (daddr_t)-1)
  821                         panic("blst_meta_fill: filling unexpected range");
  822 
  823                 if (next_skip == 1) {
  824                         nblks += blst_leaf_fill(&scan[i], allocBlk, v);
  825                 } else {
  826                         nblks += blst_meta_fill(&scan[i], allocBlk, v,
  827                             radix, next_skip - 1, blk);
  828                 }
  829                 count -= v;
  830                 allocBlk += v;
  831                 blk += radix;
  832                 i += next_skip;
  833         }
  834         scan->u.bmu_avail -= nblks;
  835         return nblks;
  836 }
  837 
  838 /*
  839  * BLST_RADIX_INIT() - initialize radix tree
  840  *
  841  *      Initialize our meta structures and bitmaps and calculate the exact
  842  *      amount of space required to manage 'count' blocks - this space may
  843  *      be considerably less then the calculated radix due to the large
  844  *      RADIX values we use.
  845  */
  846 
  847 static daddr_t  
  848 blst_radix_init(blmeta_t *scan, daddr_t radix, int skip, daddr_t count)
  849 {
  850         int i;
  851         int next_skip;
  852         daddr_t memindex = 0;
  853 
  854         /*
  855          * Leaf node
  856          */
  857 
  858         if (radix == BLIST_BMAP_RADIX) {
  859                 if (scan) {
  860                         scan->bm_bighint = 0;
  861                         scan->u.bmu_bitmap = 0;
  862                 }
  863                 return(memindex);
  864         }
  865 
  866         /*
  867          * Meta node.  If allocating the entire object we can special
  868          * case it.  However, we need to figure out how much memory
  869          * is required to manage 'count' blocks, so we continue on anyway.
  870          */
  871 
  872         if (scan) {
  873                 scan->bm_bighint = 0;
  874                 scan->u.bmu_avail = 0;
  875         }
  876 
  877         radix /= BLIST_META_RADIX;
  878         next_skip = ((u_int)skip / BLIST_META_RADIX);
  879 
  880         for (i = 1; i <= skip; i += next_skip) {
  881                 if (count >= radix) {
  882                         /*
  883                          * Allocate the entire object
  884                          */
  885                         memindex = i + blst_radix_init(
  886                             ((scan) ? &scan[i] : NULL),
  887                             radix,
  888                             next_skip - 1,
  889                             radix
  890                         );
  891                         count -= radix;
  892                 } else if (count > 0) {
  893                         /*
  894                          * Allocate a partial object
  895                          */
  896                         memindex = i + blst_radix_init(
  897                             ((scan) ? &scan[i] : NULL),
  898                             radix,
  899                             next_skip - 1,
  900                             count
  901                         );
  902                         count = 0;
  903                 } else {
  904                         /*
  905                          * Add terminator and break out
  906                          */
  907                         if (scan)
  908                                 scan[i].bm_bighint = (daddr_t)-1;
  909                         break;
  910                 }
  911         }
  912         if (memindex < i)
  913                 memindex = i;
  914         return(memindex);
  915 }
  916 
  917 #ifdef BLIST_DEBUG
  918 
  919 static void     
  920 blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int skip, int tab)
  921 {
  922         int i;
  923         int next_skip;
  924         int lastState = 0;
  925 
  926         if (radix == BLIST_BMAP_RADIX) {
  927                 printf(
  928                     "%*.*s(%08llx,%lld): bitmap %08llx big=%lld\n", 
  929                     tab, tab, "",
  930                     (long long)blk, (long long)radix,
  931                     (long long)scan->u.bmu_bitmap,
  932                     (long long)scan->bm_bighint
  933                 );
  934                 return;
  935         }
  936 
  937         if (scan->u.bmu_avail == 0) {
  938                 printf(
  939                     "%*.*s(%08llx,%lld) ALL ALLOCATED\n",
  940                     tab, tab, "",
  941                     (long long)blk,
  942                     (long long)radix
  943                 );
  944                 return;
  945         }
  946         if (scan->u.bmu_avail == radix) {
  947                 printf(
  948                     "%*.*s(%08llx,%lld) ALL FREE\n",
  949                     tab, tab, "",
  950                     (long long)blk,
  951                     (long long)radix
  952                 );
  953                 return;
  954         }
  955 
  956         printf(
  957             "%*.*s(%08llx,%lld): subtree (%lld/%lld) big=%lld {\n",
  958             tab, tab, "",
  959             (long long)blk, (long long)radix,
  960             (long long)scan->u.bmu_avail,
  961             (long long)radix,
  962             (long long)scan->bm_bighint
  963         );
  964 
  965         radix /= BLIST_META_RADIX;
  966         next_skip = ((u_int)skip / BLIST_META_RADIX);
  967         tab += 4;
  968 
  969         for (i = 1; i <= skip; i += next_skip) {
  970                 if (scan[i].bm_bighint == (daddr_t)-1) {
  971                         printf(
  972                             "%*.*s(%08llx,%lld): Terminator\n",
  973                             tab, tab, "",
  974                             (long long)blk, (long long)radix
  975                         );
  976                         lastState = 0;
  977                         break;
  978                 }
  979                 blst_radix_print(
  980                     &scan[i],
  981                     blk,
  982                     radix,
  983                     next_skip - 1,
  984                     tab
  985                 );
  986                 blk += radix;
  987         }
  988         tab -= 4;
  989 
  990         printf(
  991             "%*.*s}\n",
  992             tab, tab, ""
  993         );
  994 }
  995 
  996 #endif
  997 
  998 #ifdef BLIST_DEBUG
  999 
 1000 int
 1001 main(int ac, char **av)
 1002 {
 1003         int size = 1024;
 1004         int i;
 1005         blist_t bl;
 1006 
 1007         for (i = 1; i < ac; ++i) {
 1008                 const char *ptr = av[i];
 1009                 if (*ptr != '-') {
 1010                         size = strtol(ptr, NULL, 0);
 1011                         continue;
 1012                 }
 1013                 ptr += 2;
 1014                 fprintf(stderr, "Bad option: %s\n", ptr - 2);
 1015                 exit(1);
 1016         }
 1017         bl = blist_create(size);
 1018         blist_free(bl, 0, size);
 1019 
 1020         for (;;) {
 1021                 char buf[1024];
 1022                 daddr_t da = 0;
 1023                 daddr_t count = 0;
 1024 
 1025 
 1026                 printf("%lld/%lld/%lld> ", (long long)bl->bl_free,
 1027                     (long long)size, (long long)bl->bl_radix);
 1028                 fflush(stdout);
 1029                 if (fgets(buf, sizeof(buf), stdin) == NULL)
 1030                         break;
 1031                 switch(buf[0]) {
 1032                 case 'r':
 1033                         if (sscanf(buf + 1, "%lld", &count) == 1) {
 1034                                 blist_resize(&bl, count, 1);
 1035                         } else {
 1036                                 printf("?\n");
 1037                         }
 1038                 case 'p':
 1039                         blist_print(bl);
 1040                         break;
 1041                 case 'a':
 1042                         if (sscanf(buf + 1, "%lld", &count) == 1) {
 1043                                 daddr_t blk = blist_alloc(bl, count);
 1044                                 printf("    R=%08llx\n", (long long)blk);
 1045                         } else {
 1046                                 printf("?\n");
 1047                         }
 1048                         break;
 1049                 case 'f':
 1050                         if (sscanf(buf + 1, "%llx %lld",
 1051                             (long long *)&da, (long long *)&count) == 2) {
 1052                                 blist_free(bl, da, count);
 1053                         } else {
 1054                                 printf("?\n");
 1055                         }
 1056                         break;
 1057                 case 'l':
 1058                         if (sscanf(buf + 1, "%llx %lld",
 1059                             (long long *)&da, (long long *)&count) == 2) {
 1060                                 printf("    n=%d\n",
 1061                                     blist_fill(bl, da, count));
 1062                         } else {
 1063                                 printf("?\n");
 1064                         }
 1065                         break;
 1066                 case '?':
 1067                 case 'h':
 1068                         puts(
 1069                             "p          -print\n"
 1070                             "a %d       -allocate\n"
 1071                             "f %x %d    -free\n"
 1072                             "l %x %d    -fill\n"
 1073                             "r %d       -resize\n"
 1074                             "h/?        -help"
 1075                         );
 1076                         break;
 1077                 default:
 1078                         printf("?\n");
 1079                         break;
 1080                 }
 1081         }
 1082         return(0);
 1083 }
 1084 
 1085 void
 1086 panic(const char *ctl, ...)
 1087 {
 1088         va_list va;
 1089 
 1090         va_start(va, ctl);
 1091         vfprintf(stderr, ctl, va);
 1092         fprintf(stderr, "\n");
 1093         va_end(va);
 1094         exit(1);
 1095 }
 1096 
 1097 #endif
 1098 

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