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
69typedef u_long swblk_t;
70typedef 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
82typedef 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
90typedef 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
127blist_t blist_create(swblk_t);
128void blist_destroy(blist_t);
129swblk_t blist_alloc(blist_t, swblk_t);
130swblk_t blist_allocat(blist_t, swblk_t, swblk_t);
131void blist_free(blist_t, swblk_t, swblk_t);
132swblk_t blist_fill(blist_t, swblk_t, swblk_t);
133void blist_print(blist_t);
134void blist_resize(blist_t *, swblk_t, int);
135void blist_gapfind(blist_t, swblk_t *, swblk_t *);
136
137#endif /* _SYS_BLIST_H_ */