The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/sys/blist.h

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    1 /* $OpenBSD: blist.h,v 1.2 2022/08/06 13:44:04 semarie Exp $ */
    2 /* DragonFlyBSD:7b80531f545c7d3c51c1660130c71d01f6bccbe0:/sys/sys/blist.h */
    3 /*
    4  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
    5  * 
    6  * This code is derived from software contributed to The DragonFly Project
    7  * by Matthew Dillon <dillon@backplane.com>
    8  * 
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 
   13  * 1. Redistributions of source code must retain the above copyright
   14  *    notice, this list of conditions and the following disclaimer.
   15  * 2. Redistributions in binary form must reproduce the above copyright
   16  *    notice, this list of conditions and the following disclaimer in
   17  *    the documentation and/or other materials provided with the
   18  *    distribution.
   19  * 3. Neither the name of The DragonFly Project nor the names of its
   20  *    contributors may be used to endorse or promote products derived
   21  *    from this software without specific, prior written permission.
   22  * 
   23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   24  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   25  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   26  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
   27  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   28  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
   29  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   30  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   31  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   32  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   33  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   34  * SUCH DAMAGE.
   35  * 
   36  * Implements bitmap resource lists.
   37  *
   38  *      Usage:
   39  *              blist = blist_create(blocks)
   40  *              (void)  blist_destroy(blist)
   41  *              blkno = blist_alloc(blist, count)
   42  *              (void)  blist_free(blist, blkno, count)
   43  *              nblks = blist_fill(blist, blkno, count)
   44  *              (void)  blist_resize(&blist, count, freeextra)
   45  *
   46  *
   47  *      Notes:
   48  *              on creation, the entire list is marked reserved.  You should
   49  *              first blist_free() the sections you want to make available
   50  *              for allocation before doing general blist_alloc()/free()
   51  *              ops.
   52  *
   53  *              SWAPBLK_NONE is returned on failure.  This module is typically
   54  *              capable of managing up to (2^31) blocks per blist, though
   55  *              the memory utilization would be insane if you actually did
   56  *              that.  Managing something like 512MB worth of 4K blocks
   57  *              eats around 32 KBytes of memory.
   58  *
   59  * $FreeBSD: src/sys/sys/blist.h,v 1.2.2.1 2003/01/12 09:23:12 dillon Exp $
   60  */
   61 
   62 #ifndef _SYS_BLIST_H_
   63 #define _SYS_BLIST_H_
   64 
   65 #ifndef _SYS_TYPES_H_
   66 #include <sys/types.h>
   67 #endif
   68 
   69 typedef u_long          swblk_t;
   70 typedef u_int64_t       u_swblk_t;
   71 
   72 /*
   73  * note: currently use SWAPBLK_NONE as an absolute value rather then
   74  * a flag bit.
   75  */
   76 #define SWAPBLK_NONE    ((swblk_t)-1)
   77 
   78 /*
   79  * blmeta and bl_bitmap_t MUST be a power of 2 in size.
   80  */
   81 
   82 typedef struct blmeta {
   83         union {
   84             swblk_t     bmu_avail;      /* space available under us     */
   85             u_swblk_t   bmu_bitmap;     /* bitmap if we are a leaf      */
   86         } u;
   87         swblk_t         bm_bighint;     /* biggest contiguous block hint*/
   88 } blmeta_t;
   89 
   90 typedef struct blist {
   91         swblk_t         bl_blocks;      /* area of coverage             */
   92         /* XXX int64_t bl_radix */
   93         swblk_t         bl_radix;       /* coverage radix               */
   94         swblk_t         bl_skip;        /* starting skip                */
   95         swblk_t         bl_free;        /* number of free blocks        */
   96         blmeta_t        *bl_root;       /* root of radix tree           */
   97         swblk_t         bl_rootblks;    /* swblk_t blks allocated for tree */
   98 } *blist_t;
   99 
  100 #define BLIST_META_RADIX        (sizeof(u_swblk_t)*8/2) /* 2 bits per */
  101 #define BLIST_BMAP_RADIX        (sizeof(u_swblk_t)*8)   /* 1 bit per */
  102 
  103 /*
  104  * The radix may exceed the size of a 64 bit signed (or unsigned) int
  105  * when the maximal number of blocks is allocated.  With a 32-bit swblk_t
  106  * this corresponds to ~1G x PAGE_SIZE = 4096GB.  The swap code usually
  107  * divides this by 4, leaving us with a capability of up to four 1TB swap
  108  * devices.
  109  *
  110  * With a 64-bit swblk_t the limitation is some insane number.
  111  *
  112  * NOTE: For now I don't trust that we overflow-detect properly so we divide
  113  *       out to ensure that no overflow occurs.
  114  */
  115 
  116 #if defined(_LP64)
  117 /* swblk_t 64bits */
  118 #define BLIST_MAXBLKS           (0x4000000000000000LL /         \
  119                                  (BLIST_BMAP_RADIX / BLIST_META_RADIX))
  120 #else
  121 #define BLIST_MAXBLKS           (0x40000000 /           \
  122                                  (BLIST_BMAP_RADIX / BLIST_META_RADIX))
  123 #endif
  124 
  125 #define BLIST_MAX_ALLOC         BLIST_BMAP_RADIX
  126 
  127 blist_t blist_create(swblk_t);
  128 void blist_destroy(blist_t);
  129 swblk_t blist_alloc(blist_t, swblk_t);
  130 swblk_t blist_allocat(blist_t, swblk_t, swblk_t);
  131 void blist_free(blist_t, swblk_t, swblk_t);
  132 swblk_t blist_fill(blist_t, swblk_t, swblk_t);
  133 void blist_print(blist_t);
  134 void blist_resize(blist_t *, swblk_t, int);
  135 void blist_gapfind(blist_t, swblk_t *, swblk_t *);
  136 
  137 #endif  /* _SYS_BLIST_H_ */

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