BSD 4.4 Lite Kernel Sources

1 files changed, 90 insertions, 0 deletions

diff --git a/sys/vm/swap_pager.h b/sys/vm/swap_pager.h
new file mode 100644
index 0000000..497d92a
--- /dev/null
+++ b/sys/vm/swap_pager.h
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 1990 University of Utah.
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * the Systems Programming Group of the University of Utah Computer
+ * Science Department.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)swap_pager.h	8.1 (Berkeley) 6/11/93
+ */
+
+#ifndef	_SWAP_PAGER_
+#define	_SWAP_PAGER_	1
+
+/*
+ * In the swap pager, the backing store for an object is organized as an
+ * array of some number of "swap blocks".  A swap block consists of a bitmask
+ * and some number of contiguous DEV_BSIZE disk blocks.  The minimum size
+ * of a swap block is:
+ *
+ *	max(PAGE_SIZE, dmmin*DEV_BSIZE)			[ 32k currently ]
+ *
+ * bytes (since the pager interface is page oriented), the maximum size is:
+ *
+ *	min(#bits(swb_mask)*PAGE_SIZE, dmmax*DEV_BSIZE)	[ 128k currently ]
+ *
+ * where dmmin and dmmax are left over from the old VM interface.  The bitmask
+ * (swb_mask) is used by swap_pager_haspage() to determine if a particular
+ * page has actually been written; i.e. the pager copy of the page is valid.
+ * All swap blocks in the backing store of an object will be the same size.
+ *
+ * The reason for variable sized swap blocks is to reduce fragmentation of
+ * swap resources.  Whenever possible we allocate smaller swap blocks to
+ * smaller objects.  The swap block size is determined from a table of
+ * object-size vs. swap-block-size computed at boot time.
+ */
+typedef	int	sw_bm_t;	/* pager bitmask */
+
+struct	swblock {
+	sw_bm_t	 swb_mask;	/* bitmask of valid pages in this block */
+	daddr_t	 swb_block;	/* starting disk block for this block */
+};
+typedef struct swblock	*sw_blk_t;
+
+/*
+ * Swap pager private data.
+ */
+struct swpager {
+	vm_size_t    sw_osize;	/* size of object we are backing (bytes) */
+	int	     sw_bsize;	/* size of swap blocks (DEV_BSIZE units) */
+	int	     sw_nblocks;/* number of blocks in list (sw_blk_t units) */
+	sw_blk_t     sw_blocks;	/* pointer to list of swap blocks */
+	short	     sw_flags;	/* flags */
+	short	     sw_poip;	/* pageouts in progress */
+};
+typedef struct swpager	*sw_pager_t;
+
+#define	SW_WANTED	0x01
+#define SW_NAMED	0x02
+
+#endif	/* _SWAP_PAGER_ */