usr/src/sys/vm/vm_pager.h

/*
 * Copyright (c) 1990 University of Utah.
 * Copyright (c) 1991 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.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)vm_pager.h  7.2 (Berkeley) %G%
 */

/*
 * Pager routine interface definition.
 * For BSD we use a cleaner version of the internal pager interface.
 */

#ifndef _VM_PAGER_
#define _VM_PAGER_

struct  pager_struct {
        queue_head_t    pg_list;        /* links for list management */
        caddr_t         pg_handle;      /* external handle (vp, dev, fp) */
        int             pg_type;        /* type of pager */
        struct pagerops *pg_ops;        /* pager operations */
        caddr_t         pg_data;        /* private pager data */
};
typedef struct pager_struct *vm_pager_t;

/* pager types */
#define PG_DFLT         -1
#define PG_SWAP         0
#define PG_VNODE        1
#define PG_DEVICE       2

struct  pagerops {
        void            (*pgo_init)();          /* initialize pager */
        vm_pager_t      (*pgo_alloc)();         /* allocate pager */
        void            (*pgo_dealloc)();       /* disassociate */
        int             (*pgo_getpage)();       /* get (read) page */
        int             (*pgo_putpage)();       /* put (write) page */
        boolean_t       (*pgo_haspage)();       /* does pager have page? */
};

/*
 * get/put return values
 * OK   operation was successful
 * BAD  specified data was out of the accepted range
 * FAIL specified data was in range, but doesn't exist
 * PEND operations was initiated but not completed
 */
#define VM_PAGER_OK     0
#define VM_PAGER_BAD    1
#define VM_PAGER_FAIL   2
#define VM_PAGER_PEND   3

#define VM_PAGER_ALLOC(h, s, p)         (*(pg)->pg_ops->pgo_alloc)(h, s, p)
#define VM_PAGER_DEALLOC(pg)            (*(pg)->pg_ops->pgo_dealloc)(pg)
#define VM_PAGER_GET(pg, m, s)          (*(pg)->pg_ops->pgo_getpage)(pg, m, s)
#define VM_PAGER_PUT(pg, m, s)          (*(pg)->pg_ops->pgo_putpage)(pg, m, s)
#define VM_PAGER_HASPAGE(pg, o)         (*(pg)->pg_ops->pgo_haspage)(pg, o)

#ifdef KERNEL
vm_pager_t      vm_pager_allocate();
void            vm_pager_deallocate();
int             vm_pager_get();
int             vm_pager_put();
boolean_t       vm_pager_has_page();

vm_offset_t     vm_pager_map_page();
void            vm_pager_unmap_page();
vm_pager_t      vm_pager_lookup();
void            vm_pager_sync();

extern struct pagerops *dfltpagerops;
#endif

#endif  /* _VM_PAGER_ */