blist.h

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    1 /*
    2  * Copyright (c) 1998 Matthew Dillon.  Terms of use and redistribution in all
    3  * forms are covered by the BSD copyright in the file "/usr/src/COPYRIGHT".
    4  *
    5  * Implements bitmap resource lists.
    6  *
    7  *      Usage:
    8  *              blist = blist_create(blocks)
    9  *              (void)  blist_destroy(blist)
   10  *              blkno = blist_alloc(blist, count)
   11  *              (void)  blist_free(blist, blkno, count)
   12  *              (void)  blist_resize(&blist, count, freeextra)
   13  *              
   14  *
   15  *      Notes:
   16  *              on creation, the entire list is marked reserved.  You should
   17  *              first blist_free() the sections you want to make available
   18  *              for allocation before doing general blist_alloc()/free()
   19  *              ops.
   20  *
   21  *              SWAPBLK_NONE is returned on failure.  This module is typically
   22  *              capable of managing up to (2^31) blocks per blist, though
   23  *              the memory utilization would be insane if you actually did
   24  *              that.  Managing something like 512MB worth of 4K blocks 
   25  *              eats around 32 KBytes of memory. 
   26  *
   27  * $FreeBSD: releng/5.0/sys/sys/blist.h 96849 2002-05-18 09:38:20Z phk $
   28  */
   29 
   30 #ifndef _SYS_BLIST_H_
   31 #define _SYS_BLIST_H_
   32 
   33 typedef u_int32_t       u_daddr_t;      /* unsigned disk address */
   34 
   35 static __inline int
   36 LOG2(u_daddr_t v)
   37 {
   38         int i = -1;
   39 
   40         if (!v)
   41                 return(0);
   42         while (v) {
   43                 i++;
   44                 v >>= 1;
   45         }
   46         return (i);
   47 }
   48 
   49 /*
   50  * blmeta and bl_bitmap_t MUST be a power of 2 in size.
   51  */
   52 
   53 typedef struct blmeta {
   54         union {
   55             daddr_t     bmu_avail;      /* space available under us     */
   56             u_daddr_t   bmu_bitmap;     /* bitmap if we are a leaf      */
   57         } u;
   58         daddr_t         bm_bighint;     /* biggest contiguous block hint*/
   59 } blmeta_t;
   60 
   61 typedef struct blist {
   62         daddr_t         bl_blocks;      /* area of coverage             */
   63         daddr_t         bl_radix;       /* coverage radix               */
   64         daddr_t         bl_skip;        /* starting skip                */
   65         daddr_t         bl_free;        /* number of free blocks        */
   66         blmeta_t        *bl_root;       /* root of radix tree           */
   67         daddr_t         bl_rootblks;    /* daddr_t blks allocated for tree */
   68 } *blist_t;
   69 
   70 #define BLIST_META_RADIX        16
   71 #define BLIST_META_RADIX_SHIFT  LOG2(BLIST_META_RADIX)
   72 #define BLIST_BMAP_RADIX        (sizeof(u_daddr_t)*8)
   73 #define BLIST_BMAP_RADIX_SHIFT  LOG2(BLIST_BMAP_RADIX)
   74 
   75 #define BLIST_MAX_ALLOC         BLIST_BMAP_RADIX
   76 
   77 extern blist_t blist_create(daddr_t blocks);
   78 extern void blist_destroy(blist_t blist);
   79 extern daddr_t blist_alloc(blist_t blist, daddr_t count);
   80 extern void blist_free(blist_t blist, daddr_t blkno, daddr_t count);
   81 extern void blist_print(blist_t blist);
   82 extern void blist_resize(blist_t *pblist, daddr_t count, int freenew);
   83 
   84 #endif  /* _SYS_BLIST_H_ */
   85

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

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sys/sys/blist.h