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 * nblks = blist_fill(blist, blkno, count)
13 * (void) blist_resize(&blist, count, freeextra)
14 *
15 *
16 * Notes:
17 * on creation, the entire list is marked reserved. You should
18 * first blist_free() the sections you want to make available
19 * for allocation before doing general blist_alloc()/free()
20 * ops.
21 *
22 * SWAPBLK_NONE is returned on failure. This module is typically
23 * capable of managing up to (2^31) blocks per blist, though
24 * the memory utilization would be insane if you actually did
25 * that. Managing something like 512MB worth of 4K blocks
26 * eats around 32 KBytes of memory.
27 *
28 * $FreeBSD: releng/5.1/sys/sys/blist.h 109086 2003-01-11 01:09:51Z dillon $
29 */
30
31 #ifndef _SYS_BLIST_H_
32 #define _SYS_BLIST_H_
33
34 typedef u_int32_t u_daddr_t; /* unsigned disk address */
35
36 /*
37 * blmeta and bl_bitmap_t MUST be a power of 2 in size.
38 */
39
40 typedef struct blmeta {
41 union {
42 daddr_t bmu_avail; /* space available under us */
43 u_daddr_t bmu_bitmap; /* bitmap if we are a leaf */
44 } u;
45 daddr_t bm_bighint; /* biggest contiguous block hint*/
46 } blmeta_t;
47
48 typedef struct blist {
49 daddr_t bl_blocks; /* area of coverage */
50 daddr_t bl_radix; /* coverage radix */
51 daddr_t bl_skip; /* starting skip */
52 daddr_t bl_free; /* number of free blocks */
53 blmeta_t *bl_root; /* root of radix tree */
54 daddr_t bl_rootblks; /* daddr_t blks allocated for tree */
55 } *blist_t;
56
57 #define BLIST_META_RADIX 16
58 #define BLIST_BMAP_RADIX (sizeof(u_daddr_t)*8)
59
60 #define BLIST_MAX_ALLOC BLIST_BMAP_RADIX
61
62 extern blist_t blist_create(daddr_t blocks);
63 extern void blist_destroy(blist_t blist);
64 extern daddr_t blist_alloc(blist_t blist, daddr_t count);
65 extern void blist_free(blist_t blist, daddr_t blkno, daddr_t count);
66 extern int blist_fill(blist_t bl, daddr_t blkno, daddr_t count);
67 extern void blist_print(blist_t blist);
68 extern void blist_resize(blist_t *pblist, daddr_t count, int freenew);
69
70 #endif /* _SYS_BLIST_H_ */
71
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