FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_pager.h

     /*
      * 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.
     *
     *      @(#)vm_pager.h  8.4 (Berkeley) 1/12/94
     * $FreeBSD: releng/5.0/sys/vm/vm_pager.h 99196 2002-07-01 02:38:05Z alc $
     */
    
    /*
     * Pager routine interface definition.
     */
    
    #ifndef _VM_PAGER_
    #define _VM_PAGER_
    
    #include <sys/queue.h>
    
    TAILQ_HEAD(pagerlst, vm_object);
    
    struct bio;
    
    struct pagerops {
            void (*pgo_init)(void);         /* Initialize pager. */
            vm_object_t (*pgo_alloc)(void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t);        /* Allocate pager. */
            void (*pgo_dealloc)(vm_object_t);       /* Disassociate. */
            int (*pgo_getpages)(vm_object_t, vm_page_t *, int, int);        /* Get (read) page. */
            void (*pgo_putpages)(vm_object_t, vm_page_t *, int, int, int *); /* Put (write) page. */
            boolean_t (*pgo_haspage)(vm_object_t, vm_pindex_t, int *, int *); /* Does pager have page? */
            void (*pgo_pageunswapped)(vm_page_t);
            void (*pgo_strategy)(vm_object_t, struct bio *);
    };
    
    /*
     * 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
     * ERROR error while accessing data that is in range and exists
     * AGAIN temporary resource shortage prevented operation from happening
     */
    #define VM_PAGER_OK     0
    #define VM_PAGER_BAD    1
    #define VM_PAGER_FAIL   2
    #define VM_PAGER_PEND   3
    #define VM_PAGER_ERROR  4
    #define VM_PAGER_AGAIN  5
    
    #define VM_PAGER_PUT_SYNC       0x1
    #define VM_PAGER_PUT_INVAL      0x2
    
    #ifdef _KERNEL
    #ifdef MALLOC_DECLARE
    MALLOC_DECLARE(M_VMPGDATA);
    #endif
    
    extern vm_map_t pager_map;
    extern int pager_map_size;
    extern struct pagerops *pagertab[];
    extern struct mtx pbuf_mtx;
    
    vm_object_t vm_pager_allocate(objtype_t, void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t);
    void vm_pager_bufferinit(void);
    void vm_pager_deallocate(vm_object_t);
    static __inline int vm_pager_get_pages(vm_object_t, vm_page_t *, int, int);
    static __inline boolean_t vm_pager_has_page(vm_object_t, vm_pindex_t, int *, int *);
   void vm_pager_init(void);
   vm_object_t vm_pager_object_lookup(struct pagerlst *, void *);
   vm_offset_t vm_pager_map_page(vm_page_t);
   void vm_pager_unmap_page(vm_offset_t);
   void vm_pager_strategy(vm_object_t object, struct bio *bp);
   
   /*
    *      vm_page_get_pages:
    *
    *      Retrieve pages from the VM system in order to map them into an object
    *      ( or into VM space somewhere ).  If the pagein was successful, we
    *      must fully validate it.
    */
   static __inline int
   vm_pager_get_pages(
           vm_object_t object,
           vm_page_t *m,
           int count,
           int reqpage
   ) {
           int r;
   
           GIANT_REQUIRED;
   
           r = (*pagertab[object->type]->pgo_getpages)(object, m, count, reqpage);
           if (r == VM_PAGER_OK && m[reqpage]->valid != VM_PAGE_BITS_ALL) {
                   vm_page_zero_invalid(m[reqpage], TRUE);
           }
           return (r);
   }
   
   static __inline void
   vm_pager_put_pages(
           vm_object_t object,
           vm_page_t *m,
           int count,
           int flags,
           int *rtvals
   ) {
           GIANT_REQUIRED;
           (*pagertab[object->type]->pgo_putpages)
               (object, m, count, flags, rtvals);
   }
   
   /*
    *      vm_pager_haspage
    *
    *      Check to see if an object's pager has the requested page.  The
    *      object's pager will also set before and after to give the caller
    *      some idea of the number of pages before and after the requested
    *      page can be I/O'd efficiently.
    *
    *      This routine does not have to be called at any particular spl.
    */
   static __inline boolean_t
   vm_pager_has_page(
           vm_object_t object,
           vm_pindex_t offset, 
           int *before,
           int *after
   ) {
           boolean_t ret;
   
           GIANT_REQUIRED;
           ret = (*pagertab[object->type]->pgo_haspage)
               (object, offset, before, after);
           return (ret);
   } 
   
   /* 
    *      vm_pager_page_unswapped
    * 
    *      called at splvm() to destroy swap associated with the page.
    * 
    *      This function may not block.
    */
   static __inline void
   vm_pager_page_unswapped(vm_page_t m)
   {
           GIANT_REQUIRED;
           if (pagertab[m->object->type]->pgo_pageunswapped)
                   (*pagertab[m->object->type]->pgo_pageunswapped)(m);
   }
   
   #endif                          /* _KERNEL */
   #endif                          /* _VM_PAGER_ */

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