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1.1 root 1: /*
2: * Copyright (c) 1990 University of Utah.
3: * Copyright (c) 1991 The Regents of the University of California.
4: * All rights reserved.
5: *
6: * This code is derived from software contributed to Berkeley by
7: * the Systems Programming Group of the University of Utah Computer
8: * Science Department.
9: *
10: * Redistribution and use in source and binary forms, with or without
11: * modification, are permitted provided that the following conditions
12: * are met:
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 the
17: * documentation and/or other materials provided with the distribution.
18: * 3. All advertising materials mentioning features or use of this software
19: * must display the following acknowledgement:
20: * This product includes software developed by the University of
21: * California, Berkeley and its contributors.
22: * 4. Neither the name of the University nor the names of its contributors
23: * may be used to endorse or promote products derived from this software
24: * without specific prior written permission.
25: *
26: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36: * SUCH DAMAGE.
37: *
38: * @(#)swap_pager.h 7.1 (Berkeley) 12/5/90
39: */
40:
41: #ifndef _SWAP_PAGER_
42: #define _SWAP_PAGER_ 1
43:
44: /*
45: * In the swap pager, the backing store for an object is organized as an
46: * array of some number of "swap blocks". A swap block consists of a bitmask
47: * and some number of contiguous DEV_BSIZE disk blocks. The minimum size
48: * of a swap block is:
49: *
50: * max(PAGE_SIZE, dmmin*DEV_BSIZE) [ 32k currently ]
51: *
52: * bytes (since the pager interface is page oriented), the maximum size is:
53: *
54: * min(#bits(swb_mask)*PAGE_SIZE, dmmax*DEV_BSIZE) [ 128k currently ]
55: *
56: * where dmmin and dmmax are left over from the old VM interface. The bitmask
57: * (swb_mask) is used by swap_pager_haspage() to determine if a particular
58: * page has actually been written; i.e. the pager copy of the page is valid.
59: * All swap blocks in the backing store of an object will be the same size.
60: *
61: * The reason for variable sized swap blocks is to reduce fragmentation of
62: * swap resources. Whenever possible we allocate smaller swap blocks to
63: * smaller objects. The swap block size is determined from a table of
64: * object-size vs. swap-block-size computed at boot time.
65: */
66: typedef int sw_bm_t; /* pager bitmask */
67:
68: struct swblock {
69: sw_bm_t swb_mask; /* bitmask of valid pages in this block */
70: daddr_t swb_block; /* starting disk block for this block */
71: };
72: typedef struct swblock *sw_blk_t;
73:
74: /*
75: * Swap pager private data.
76: */
77: struct swpager {
78: vm_size_t sw_osize; /* size of object we are backing (bytes) */
79: int sw_bsize; /* size of swap blocks (DEV_BSIZE units) */
80: int sw_nblocks;/* number of blocks in list (sw_blk_t units) */
81: sw_blk_t sw_blocks; /* pointer to list of swap blocks */
82: short sw_flags; /* flags */
83: short sw_poip; /* pageouts in progress */
84: };
85: typedef struct swpager *sw_pager_t;
86:
87: #define SW_WANTED 0x01
88: #define SW_NAMED 0x02
89:
90: #ifdef KERNEL
91:
92: void swap_pager_init();
93: vm_pager_t swap_pager_alloc();
94: void swap_pager_dealloc();
95: boolean_t swap_pager_getpage(), swap_pager_putpage();
96: boolean_t swap_pager_haspage();
97:
98: struct pagerops swappagerops = {
99: swap_pager_init,
100: swap_pager_alloc,
101: swap_pager_dealloc,
102: swap_pager_getpage,
103: swap_pager_putpage,
104: swap_pager_haspage
105: };
106:
107: int swap_pager_iodone();
108: boolean_t swap_pager_clean();
109:
110: #endif
111:
112: #endif /* _SWAP_PAGER_ */
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