FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_object.c

     /*      $NetBSD: uvm_object.c,v 1.6 2008/04/28 20:24:12 martin Exp $    */
     
     /*
      * Copyright (c) 2006 The NetBSD Foundation, Inc.
      * All rights reserved.
      *
      * This code is derived from software contributed to The NetBSD Foundation
      * by Mindaugas Rasiukevicius.
      *
     * 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.
     *
     * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
     */
    
    /*
     * uvm_object.c: operate with memory objects
     *
     * TODO:
     *  1. Support PG_RELEASED-using objects
     *
     */
    
    #include <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: uvm_object.c,v 1.6 2008/04/28 20:24:12 martin Exp $");
    
    #include "opt_uvmhist.h"
    
    #include <sys/param.h>
    
    #include <uvm/uvm.h>
    
    /* We will fetch this page count per step */
    #define FETCH_PAGECOUNT 16
    
    /*
     * uobj_wirepages: wire the pages of entire uobj
     *
     * => NOTE: this function should only be used for types of objects
     *  where PG_RELEASED flag is never set (aobj objects)
     * => caller must pass page-aligned start and end values
     */
    
    int
    uobj_wirepages(struct uvm_object *uobj, off_t start, off_t end)
    {
            int i, npages, error;
            struct vm_page *pgs[FETCH_PAGECOUNT], *pg = NULL;
            off_t offset = start, left;
    
            left = (end - start) >> PAGE_SHIFT;
    
            mutex_enter(&uobj->vmobjlock);
            while (left) {
    
                    npages = MIN(FETCH_PAGECOUNT, left);
    
                    /* Get the pages */
                    memset(pgs, 0, sizeof(pgs));
                    error = (*uobj->pgops->pgo_get)(uobj, offset, pgs, &npages, 0,
                            VM_PROT_READ | VM_PROT_WRITE, UVM_ADV_SEQUENTIAL,
                            PGO_ALLPAGES | PGO_SYNCIO);
    
                    if (error)
                            goto error;
    
                    mutex_enter(&uobj->vmobjlock);
                    for (i = 0; i < npages; i++) {
    
                            KASSERT(pgs[i] != NULL);
                            KASSERT(!(pgs[i]->flags & PG_RELEASED));
    
                            /*
                             * Loan break
                             */
                            if (pgs[i]->loan_count) {
                                    while (pgs[i]->loan_count) {
                                            pg = uvm_loanbreak(pgs[i]);
                                            if (!pg) {
                                                    mutex_exit(&uobj->vmobjlock);
                                                    uvm_wait("uobjwirepg");
                                                    mutex_enter(&uobj->vmobjlock);
                                                    continue;
                                           }
                                   }
                                   pgs[i] = pg;
                           }
   
                           if (pgs[i]->pqflags & PQ_AOBJ) {
                                   pgs[i]->flags &= ~(PG_CLEAN);
                                   uao_dropswap(uobj, i);
                           }
                   }
   
                   /* Wire the pages */
                   mutex_enter(&uvm_pageqlock);
                   for (i = 0; i < npages; i++) {
                           uvm_pagewire(pgs[i]);
                   }
                   mutex_exit(&uvm_pageqlock);
   
                   /* Unbusy the pages */
                   uvm_page_unbusy(pgs, npages);
   
                   left -= npages;
                   offset += npages << PAGE_SHIFT;
           }
           mutex_exit(&uobj->vmobjlock);
   
           return 0;
   
   error:
           /* Unwire the pages which has been wired */
           uobj_unwirepages(uobj, start, offset);
   
           return error;
   }
   
   /*
    * uobj_unwirepages: unwire the pages of entire uobj
    *
    * => NOTE: this function should only be used for types of objects
    *  where PG_RELEASED flag is never set
    * => caller must pass page-aligned start and end values
    */
   
   void
   uobj_unwirepages(struct uvm_object *uobj, off_t start, off_t end)
   {
           struct vm_page *pg;
           off_t offset;
   
           mutex_enter(&uobj->vmobjlock);
           mutex_enter(&uvm_pageqlock);
           for (offset = start; offset < end; offset += PAGE_SIZE) {
                   pg = uvm_pagelookup(uobj, offset);
   
                   KASSERT(pg != NULL);
                   KASSERT(!(pg->flags & PG_RELEASED));
   
                   uvm_pageunwire(pg);
           }
           mutex_exit(&uvm_pageqlock);
           mutex_exit(&uobj->vmobjlock);
   }

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