bsd/vm/vnode_pager.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * Mach Operating System
  24  * Copyright (c) 1987 Carnegie-Mellon University
  25  * All rights reserved.  The CMU software License Agreement specifies
  26  * the terms and conditions for use and redistribution.
  27  */
  28
  29 #ifndef _VNODE_PAGER_
  30 #define _VNODE_PAGER_   1
  31
  32 #include <mach/kern_return.h>
  33 #include <sys/types.h>
  34 #include <kern/queue.h>
  35
  36 #ifdef  KERNEL
  37
  38 #include <mach/boolean.h>
  39 #include <vm/vm_pager.h>
  40
  41 vm_pager_t      vnode_pager_setup();
  42 boolean_t       vnode_has_page();
  43 boolean_t       vnode_pager_active();
  44
  45 /*
  46  *  Vstructs are the internal (to us) description of a unit of backing store.
  47  *  The are the link between memory objects and the backing store they represent.
  48  *  For the vnode pager, backing store comes in two flavors: normal files and
  49  *  swap files.
  50  *
  51  *  For objects that page to and from normal files (e.g. objects that represent
  52  *  program text segments), we maintain some simple parameters that allow us to
  53  *  access the file's contents directly through the vnode interface.
  54  *
  55  *  Data for objects without associated vnodes is maintained in the swap files.
  56  *  Each object that uses one of these as backing store has a vstruct indicating
  57  *  the swap file of preference (vs_pf) and a mapping between contiguous object
  58  *  offsets and swap file offsets (vs_pmap).  Each entry in this mapping specifies
  59  *  the pager file to use, and the offset of the page in that pager file.  These
  60  *  mapping entries are of type pfMapEntry.
  61  */
  62
  63 /*
  64  * Pager file structure.  One per swap file.
  65  */
  66 typedef struct pager_file {
  67         queue_chain_t   pf_chain;       /* link to other paging files */
  68         struct  vnode   *pf_vp;         /* vnode of paging file */
  69         u_int           pf_count;       /* Number of vstruct using this file */
  70         u_char          *pf_bmap;       /* Map of used blocks */
  71         long            pf_npgs;        /* Size of file in pages */
  72         long            pf_pfree;       /* Number of unused pages */
  73         long            pf_lowat;       /* Low water page */
  74         long            pf_hipage;      /* Highest page allocated */
  75         long            pf_hint;        /* Lowest page unallocated */
  76         char            *pf_name;       /* Filename of this file */
  77         boolean_t       pf_prefer;
  78         int             pf_index;       /* index into the pager_file array */
  79         void *          pf_lock;        /* Lock for alloc and dealloc */
  80 } *pager_file_t;
  81
  82 #define PAGER_FILE_NULL (pager_file_t) 0
  83
  84 #define MAXPAGERFILES 16
  85
  86 #define MAX_BACKING_STORE 100
  87
  88 struct bs_map {
  89         struct vnode    *vp;
  90         void            *bs;
  91 };
  92
  93
  94
  95 /*
  96  * Pager file data structures.
  97  */
  98 #define INDEX_NULL      0
  99 typedef struct {
 100         unsigned int index:8;   /* paging file this block is in */
 101         unsigned int offset:24; /* page number where block resides */
 102 } pf_entry;
 103
 104 typedef enum {
 105                 IS_INODE,       /* Local disk */
 106                 IS_RNODE        /* NFS */
 107         } vpager_fstype;
 108
 109 /*
 110  *  Basic vnode pager structure.  One per object, backing-store pair.
 111  */
 112 typedef struct vstruct {
 113         boolean_t       is_device;      /* Must be first - see vm_pager.h */
 114         pager_file_t    vs_pf;          /* Pager file this uses */
 115         pf_entry        **vs_pmap;      /* Map of pages into paging file */
 116         unsigned int
 117         /* boolean_t */ vs_swapfile:1;  /* vnode is a swapfile */
 118         short           vs_count;       /* use count */
 119         int             vs_size;        /* size of this chunk in pages*/
 120         struct vnode    *vs_vp;         /* vnode to page to */
 121 } *vnode_pager_t;
 122
 123 #define VNODE_PAGER_NULL        ((vnode_pager_t) 0)
 124
 125
 126
 127 pager_return_t  pager_vnode_pagein();
 128 pager_return_t  pager_vnode_pageout();
 129 pager_return_t  vnode_pagein();
 130 pager_return_t  vnode_pageout();
 131
 132 #endif  /* KERNEL */
 133
 134 #endif  /* _VNODE_PAGER_ */