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 * $FreeBSD$
28 */
29
30 #ifndef _SYS_BLIST_H_
31 #define _SYS_BLIST_H_
32
33 /*
34 * blmeta and bl_bitmap_t MUST be a power of 2 in size.
35 */
36
37 typedef struct blmeta {
38 union {
39 daddr_t bmu_avail; /* space available under us */
40 u_daddr_t bmu_bitmap; /* bitmap if we are a leaf */
41 } u;
42 daddr_t bm_bighint; /* biggest contiguous block hint*/
43 } blmeta_t;
44
45 typedef struct blist {
46 daddr_t bl_blocks; /* area of coverage */
47 daddr_t bl_radix; /* coverage radix */
48 daddr_t bl_skip; /* starting skip */
49 daddr_t bl_free; /* number of free blocks */
50 blmeta_t *bl_root; /* root of radix tree */
51 daddr_t bl_rootblks; /* daddr_t blks allocated for tree */
52 } *blist_t;
53
54 #define BLIST_META_RADIX 16
55 #define BLIST_BMAP_RADIX (sizeof(u_daddr_t)*8)
56
57 #define BLIST_MAX_ALLOC BLIST_BMAP_RADIX
58
59 extern blist_t blist_create(daddr_t blocks);
60 extern void blist_destroy(blist_t blist);
61 extern daddr_t blist_alloc(blist_t blist, daddr_t count);
62 extern void blist_free(blist_t blist, daddr_t blkno, daddr_t count);
63 extern void blist_print(blist_t blist);
64 extern void blist_resize(blist_t *pblist, daddr_t count, int freenew);
65
66 #endif /* _SYS_BLIST_H_ */
67
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