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

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * 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. 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
     * $FreeBSD$
     */
    
    /*
     * Pager routine interface definition.
     */
    
    #ifndef _VM_PAGER_
    #define _VM_PAGER_
    
    #include <sys/queue.h>
    
    TAILQ_HEAD(pagerlst, vm_object);
    
    typedef void pgo_init_t(void);
    typedef vm_object_t pgo_alloc_t(void *, vm_ooffset_t, vm_prot_t, vm_ooffset_t,
        struct ucred *);
    typedef void pgo_dealloc_t(vm_object_t);
    typedef int pgo_getpages_t(vm_object_t, vm_page_t *, int, int *, int *);
    typedef void pgo_getpages_iodone_t(void *, vm_page_t *, int, int);
    typedef int pgo_getpages_async_t(vm_object_t, vm_page_t *, int, int *, int *,
        pgo_getpages_iodone_t, void *);
    typedef void pgo_putpages_t(vm_object_t, vm_page_t *, int, int, int *);
    typedef boolean_t pgo_haspage_t(vm_object_t, vm_pindex_t, int *, int *);
    typedef int pgo_populate_t(vm_object_t, vm_pindex_t, int, vm_prot_t,
        vm_pindex_t *, vm_pindex_t *);
    typedef void pgo_pageunswapped_t(vm_page_t);
    typedef void pgo_writecount_t(vm_object_t, vm_offset_t, vm_offset_t);
    
    struct pagerops {
            pgo_init_t              *pgo_init;              /* Initialize pager. */
            pgo_alloc_t             *pgo_alloc;             /* Allocate pager. */
            pgo_dealloc_t           *pgo_dealloc;           /* Disassociate. */
            pgo_getpages_t          *pgo_getpages;          /* Get (read) page. */
            pgo_getpages_async_t    *pgo_getpages_async;    /* Get page asyncly. */
            pgo_putpages_t          *pgo_putpages;          /* Put (write) page. */
            pgo_haspage_t           *pgo_haspage;           /* Query page. */
            pgo_populate_t          *pgo_populate;          /* Bulk spec pagein. */
            pgo_pageunswapped_t     *pgo_pageunswapped;
            /* Operations for specialized writecount handling */
            pgo_writecount_t        *pgo_update_writecount;
            pgo_writecount_t        *pgo_release_writecount;
    };
    
    extern struct pagerops defaultpagerops;
    extern struct pagerops swappagerops;
    extern struct pagerops vnodepagerops;
    extern struct pagerops devicepagerops;
    extern struct pagerops physpagerops;
    extern struct pagerops sgpagerops;
    extern struct pagerops mgtdevicepagerops;
    
    /*
     * 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               0x0001
   #define VM_PAGER_PUT_INVAL              0x0002
   #define VM_PAGER_PUT_NOREUSE            0x0004
   #define VM_PAGER_CLUSTER_OK             0x0008
   
   #ifdef _KERNEL
   
   extern struct pagerops *pagertab[];
   extern struct mtx_padalign pbuf_mtx;
   
   /*
    * Number of pages that pbuf buffer can store in b_pages.
    * It is +1 to allow for unaligned data buffer of maxphys size.
    */
   #define PBUF_PAGES      (atop(maxphys) + 1)
   
   vm_object_t vm_pager_allocate(objtype_t, void *, vm_ooffset_t, vm_prot_t,
       vm_ooffset_t, struct ucred *);
   void vm_pager_bufferinit(void);
   void vm_pager_deallocate(vm_object_t);
   int vm_pager_get_pages(vm_object_t, vm_page_t *, int, int *, int *);
   int vm_pager_get_pages_async(vm_object_t, vm_page_t *, int, int *, int *,
       pgo_getpages_iodone_t, void *);
   void vm_pager_init(void);
   vm_object_t vm_pager_object_lookup(struct pagerlst *, void *);
   
   static __inline void
   vm_pager_put_pages(
           vm_object_t object,
           vm_page_t *m,
           int count,
           int flags,
           int *rtvals
   ) {
           VM_OBJECT_ASSERT_WLOCKED(object);
           (*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.
    *
    *      The object must be locked.
    */
   static __inline boolean_t
   vm_pager_has_page(
           vm_object_t object,
           vm_pindex_t offset, 
           int *before,
           int *after
   ) {
           boolean_t ret;
   
           VM_OBJECT_ASSERT_LOCKED(object);
           ret = (*pagertab[object->type]->pgo_haspage)
               (object, offset, before, after);
           return (ret);
   } 
   
   static __inline int
   vm_pager_populate(vm_object_t object, vm_pindex_t pidx, int fault_type,
       vm_prot_t max_prot, vm_pindex_t *first, vm_pindex_t *last)
   {
   
           MPASS((object->flags & OBJ_POPULATE) != 0);
           MPASS(pidx < object->size);
           MPASS(blockcount_read(&object->paging_in_progress) > 0);
           return ((*pagertab[object->type]->pgo_populate)(object, pidx,
               fault_type, max_prot, first, last));
   }
   
   /* 
    *      vm_pager_page_unswapped
    * 
    *      Destroy swap associated with the page.
    * 
    *      XXX: A much better name would be "vm_pager_page_dirtied()"
    *      XXX: It is not obvious if this could be profitably used by any
    *      XXX: pagers besides the swap_pager or if it should even be a
    *      XXX: generic pager_op in the first place.
    */
   static __inline void
   vm_pager_page_unswapped(vm_page_t m)
   {
   
           if (pagertab[m->object->type]->pgo_pageunswapped)
                   (*pagertab[m->object->type]->pgo_pageunswapped)(m);
   }
   
   static __inline void
   vm_pager_update_writecount(vm_object_t object, vm_offset_t start,
       vm_offset_t end)
   {
   
           if (pagertab[object->type]->pgo_update_writecount)
                   pagertab[object->type]->pgo_update_writecount(object, start,
                       end);
   }
   
   static __inline void
   vm_pager_release_writecount(vm_object_t object, vm_offset_t start,
       vm_offset_t end)
   {
   
           if (pagertab[object->type]->pgo_release_writecount)
                   pagertab[object->type]->pgo_release_writecount(object, start,
                       end);
   }
   
   struct cdev_pager_ops {
           int (*cdev_pg_fault)(vm_object_t vm_obj, vm_ooffset_t offset,
               int prot, vm_page_t *mres);
           int (*cdev_pg_populate)(vm_object_t vm_obj, vm_pindex_t pidx,
               int fault_type, vm_prot_t max_prot, vm_pindex_t *first,
               vm_pindex_t *last);
           int (*cdev_pg_ctor)(void *handle, vm_ooffset_t size, vm_prot_t prot,
               vm_ooffset_t foff, struct ucred *cred, u_short *color);
           void (*cdev_pg_dtor)(void *handle);
   };
   
   vm_object_t cdev_pager_allocate(void *handle, enum obj_type tp,
       struct cdev_pager_ops *ops, vm_ooffset_t size, vm_prot_t prot,
       vm_ooffset_t foff, struct ucred *cred);
   vm_object_t cdev_pager_lookup(void *handle);
   void cdev_pager_free_page(vm_object_t object, vm_page_t m);
   
   struct phys_pager_ops {
           int (*phys_pg_getpages)(vm_object_t vm_obj, vm_page_t *m, int count,
               int *rbehind, int *rahead);
           int (*phys_pg_populate)(vm_object_t vm_obj, vm_pindex_t pidx,
               int fault_type, vm_prot_t max_prot, vm_pindex_t *first,
               vm_pindex_t *last);
           boolean_t (*phys_pg_haspage)(vm_object_t obj,  vm_pindex_t pindex,
               int *before, int *after);
           void (*phys_pg_ctor)(vm_object_t vm_obj, vm_prot_t prot,
               vm_ooffset_t foff, struct ucred *cred);
           void (*phys_pg_dtor)(vm_object_t vm_obj);
   };
   extern struct phys_pager_ops default_phys_pg_ops;
   vm_object_t phys_pager_allocate(void *handle, struct phys_pager_ops *ops,
       void *data, vm_ooffset_t size, vm_prot_t prot, vm_ooffset_t foff,
       struct ucred *cred);
   
   #endif                          /* _KERNEL */
   #endif                          /* _VM_PAGER_ */

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