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