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

     /*
      * 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 Mach Operating System project at Carnegie-Mellon University.
      *
      * 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.
     *
     *      from: @(#)vm_pager.c    8.6 (Berkeley) 1/12/94
     *
     *
     * Copyright (c) 1987, 1990 Carnegie-Mellon University.
     * All rights reserved.
     *
     * Authors: Avadis Tevanian, Jr., Michael Wayne Young
     *
     * Permission to use, copy, modify and distribute this software and
     * its documentation is hereby granted, provided that both the copyright
     * notice and this permission notice appear in all copies of the
     * software, derivative works or modified versions, and any portions
     * thereof, and that both notices appear in supporting documentation.
     *
     * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     *
     * Carnegie Mellon requests users of this software to return to
     *
     *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
     *  School of Computer Science
     *  Carnegie Mellon University
     *  Pittsburgh PA 15213-3890
     *
     * any improvements or extensions that they make and grant Carnegie the
     * rights to redistribute these changes.
     *
     * $FreeBSD: src/sys/vm/vm_pager.c,v 1.24.2.2 1999/09/05 08:24:38 peter Exp $
     */
    
    /*
     *      Paging space routine stubs.  Emulates a matchmaker-like interface
     *      for builtin pagers.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/malloc.h>
    #include <sys/buf.h>
    #include <sys/ucred.h>
    
    #include <vm/vm.h>
    #include <vm/vm_param.h>
    #include <vm/vm_prot.h>
    #include <vm/vm_object.h>
    #include <vm/vm_page.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_pager.h>
    #include <vm/vm_extern.h>
    
    extern struct pagerops defaultpagerops;
    extern struct pagerops swappagerops;
    extern struct pagerops vnodepagerops;
    extern struct pagerops devicepagerops;
    
    static struct pagerops *pagertab[] = {
            &defaultpagerops,       /* OBJT_DEFAULT */
            &swappagerops,          /* OBJT_SWAP */
            &vnodepagerops,         /* OBJT_VNODE */
            &devicepagerops,        /* OBJT_DEVICE */
    };
    static int npagers = sizeof(pagertab) / sizeof(pagertab[0]);
   
   /*
    * Kernel address space for mapping pages.
    * Used by pagers where KVAs are needed for IO.
    *
    * XXX needs to be large enough to support the number of pending async
    * cleaning requests (NPENDINGIO == 64) * the maximum swap cluster size
    * (MAXPHYS == 64k) if you want to get the most efficiency.
    */
   #define PAGER_MAP_SIZE  (8 * 1024 * 1024)
   
   int pager_map_size = PAGER_MAP_SIZE;
   vm_map_t pager_map;
   static int bswneeded;
   static vm_offset_t swapbkva;            /* swap buffers kva */
   
   void
   vm_pager_init()
   {
           struct pagerops **pgops;
   
           /*
            * Initialize known pagers
            */
           for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
                   if (pgops && ((*pgops)->pgo_init != NULL))
                           (*(*pgops)->pgo_init) ();
   }
   
   void
   vm_pager_bufferinit()
   {
           struct buf *bp;
           int i;
   
           bp = swbuf;
           /*
            * Now set up swap and physical I/O buffer headers.
            */
           for (i = 0; i < nswbuf - 1; i++, bp++) {
                   TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
                   bp->b_rcred = bp->b_wcred = NOCRED;
                   bp->b_vnbufs.le_next = NOLIST;
           }
           bp->b_rcred = bp->b_wcred = NOCRED;
           bp->b_vnbufs.le_next = NOLIST;
   
           swapbkva = kmem_alloc_pageable(pager_map, nswbuf * MAXPHYS);
           if (!swapbkva)
                   panic("Not enough pager_map VM space for physical buffers");
   }
   
   /*
    * Allocate an instance of a pager of the given type.
    * Size, protection and offset parameters are passed in for pagers that
    * need to perform page-level validation (e.g. the device pager).
    */
   vm_object_t
   vm_pager_allocate(type, handle, size, prot, off)
           objtype_t type;
           void *handle;
           vm_size_t size;
           vm_prot_t prot;
           vm_ooffset_t off;
   {
           struct pagerops *ops;
   
           ops = pagertab[type];
           if (ops)
                   return ((*ops->pgo_alloc) (handle, size, prot, off));
           return (NULL);
   }
   
   void
   vm_pager_deallocate(object)
           vm_object_t object;
   {
           (*pagertab[object->type]->pgo_dealloc) (object);
   }
   
   
   int
   vm_pager_get_pages(object, m, count, reqpage)
           vm_object_t object;
           vm_page_t *m;
           int count;
           int reqpage;
   {
           return ((*pagertab[object->type]->pgo_getpages)(object, m, count, reqpage));
   }
   
   int
   vm_pager_put_pages(object, m, count, sync, rtvals)
           vm_object_t object;
           vm_page_t *m;
           int count;
           boolean_t sync;
           int *rtvals;
   {
           return ((*pagertab[object->type]->pgo_putpages)(object, m, count, sync, rtvals));
   }
   
   boolean_t
   vm_pager_has_page(object, offset, before, after)
           vm_object_t object;
           vm_pindex_t offset;
           int *before;
           int *after;
   {
           return ((*pagertab[object->type]->pgo_haspage) (object, offset, before, after));
   }
   
   /*
    * Called by pageout daemon before going back to sleep.
    * Gives pagers a chance to clean up any completed async pageing operations.
    */
   void
   vm_pager_sync()
   {
           struct pagerops **pgops;
   
           for (pgops = pagertab; pgops < &pagertab[npagers]; pgops++)
                   if (pgops && ((*pgops)->pgo_sync != NULL))
                           (*(*pgops)->pgo_sync) ();
   }
   
   vm_offset_t
   vm_pager_map_page(m)
           vm_page_t m;
   {
           vm_offset_t kva;
   
           kva = kmem_alloc_wait(pager_map, PAGE_SIZE);
           pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
           return (kva);
   }
   
   void
   vm_pager_unmap_page(kva)
           vm_offset_t kva;
   {
           pmap_kremove(kva);
           kmem_free_wakeup(pager_map, kva, PAGE_SIZE);
   }
   
   vm_object_t
   vm_pager_object_lookup(pg_list, handle)
           register struct pagerlst *pg_list;
           void *handle;
   {
           register vm_object_t object;
   
           for (object = TAILQ_FIRST(pg_list); object != NULL; object = TAILQ_NEXT(object,pager_object_list))
                   if (object->handle == handle)
                           return (object);
           return (NULL);
   }
   
   /*
    * This routine loses a reference to the object -
    * thus a reference must be gained before calling.
    */
   int
   pager_cache(object, should_cache)
           vm_object_t object;
           boolean_t should_cache;
   {
           if (object == NULL)
                   return (KERN_INVALID_ARGUMENT);
   
           if (should_cache)
                   object->flags |= OBJ_CANPERSIST;
           else
                   object->flags &= ~OBJ_CANPERSIST;
   
           vm_object_deallocate(object);
   
           return (KERN_SUCCESS);
   }
   
   /*
    * initialize a physical buffer
    */
   
   static void
   initpbuf(struct buf *bp) {
           bzero(bp, sizeof *bp);
           bp->b_rcred = NOCRED;
           bp->b_wcred = NOCRED;
           bp->b_qindex = QUEUE_NONE;
           bp->b_data = (caddr_t) (MAXPHYS * (bp - swbuf)) + swapbkva;
           bp->b_kvabase = bp->b_data;
           bp->b_kvasize = MAXPHYS;
           bp->b_vnbufs.le_next = NOLIST;
   }
   
   /*
    * allocate a physical buffer
    */
   struct buf *
   getpbuf()
   {
           int s;
           struct buf *bp;
   
           s = splbio();
           /* get a bp from the swap buffer header pool */
           while ((bp = TAILQ_FIRST(&bswlist)) == NULL) {
                   bswneeded = 1;
                   tsleep(&bswneeded, PVM, "wswbuf", 0);
           }
           TAILQ_REMOVE(&bswlist, bp, b_freelist);
           splx(s);
   
           initpbuf(bp);
           return bp;
   }
   
   /*
    * allocate a physical buffer, if one is available
    */
   struct buf *
   trypbuf()
   {
           int s;
           struct buf *bp;
   
           s = splbio();
           if ((bp = TAILQ_FIRST(&bswlist)) == NULL) {
                   splx(s);
                   return NULL;
           }
           TAILQ_REMOVE(&bswlist, bp, b_freelist);
           splx(s);
   
           initpbuf(bp);
   
           return bp;
   }
   
   /*
    * release a physical buffer
    */
   void
   relpbuf(bp)
           struct buf *bp;
   {
           int s;
   
           s = splbio();
   
           if (bp->b_rcred != NOCRED) {
                   crfree(bp->b_rcred);
                   bp->b_rcred = NOCRED;
           }
           if (bp->b_wcred != NOCRED) {
                   crfree(bp->b_wcred);
                   bp->b_wcred = NOCRED;
           }
           if (bp->b_vp)
                   pbrelvp(bp);
   
           if (bp->b_flags & B_WANTED)
                   wakeup(bp);
   
           TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
   
           if (bswneeded) {
                   bswneeded = 0;
                   wakeup(&bswneeded);
           }
           splx(s);
   }

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