5e4bdb57cb
advantage of this restriction to avoid acquiring and releasing Giant when wiring pages within a system map. In collaboration with: tegge@
1342 lines
35 KiB
C
1342 lines
35 KiB
C
/*
|
|
* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
|
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* Copyright (c) 1994 John S. Dyson
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* All rights reserved.
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* Copyright (c) 1994 David Greenman
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* All rights reserved.
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*
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*
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* This code is derived from software contributed to Berkeley by
|
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* The Mach Operating System project at Carnegie-Mellon University.
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*
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* Redistribution and use in source and binary forms, with or without
|
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
|
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* documentation and/or other materials provided with the distribution.
|
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* 3. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
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* This product includes software developed by the University of
|
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
|
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
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*
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*
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* Copyright (c) 1987, 1990 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Authors: Avadis Tevanian, Jr., Michael Wayne Young
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
|
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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|
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
|
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* rights to redistribute these changes.
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*/
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|
|
|
/*
|
|
* Page fault handling module.
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|
*/
|
|
|
|
#include <sys/cdefs.h>
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|
__FBSDID("$FreeBSD$");
|
|
|
|
#include <sys/param.h>
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|
#include <sys/systm.h>
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|
#include <sys/kernel.h>
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|
#include <sys/lock.h>
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|
#include <sys/mutex.h>
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|
#include <sys/proc.h>
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|
#include <sys/resourcevar.h>
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|
#include <sys/sysctl.h>
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|
#include <sys/vmmeter.h>
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|
#include <sys/vnode.h>
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|
|
|
#include <vm/vm.h>
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|
#include <vm/vm_param.h>
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|
#include <vm/pmap.h>
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|
#include <vm/vm_map.h>
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|
#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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|
#include <vm/vm_pageout.h>
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|
#include <vm/vm_kern.h>
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|
#include <vm/vm_pager.h>
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|
#include <vm/vnode_pager.h>
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|
#include <vm/vm_extern.h>
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|
|
|
#define PFBAK 4
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|
#define PFFOR 4
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|
#define PAGEORDER_SIZE (PFBAK+PFFOR)
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|
|
|
static int prefault_pageorder[] = {
|
|
-1 * PAGE_SIZE, 1 * PAGE_SIZE,
|
|
-2 * PAGE_SIZE, 2 * PAGE_SIZE,
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-3 * PAGE_SIZE, 3 * PAGE_SIZE,
|
|
-4 * PAGE_SIZE, 4 * PAGE_SIZE
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|
};
|
|
|
|
static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *);
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|
static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t);
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|
|
|
#define VM_FAULT_READ_AHEAD 8
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|
#define VM_FAULT_READ_BEHIND 7
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|
#define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1)
|
|
|
|
struct faultstate {
|
|
vm_page_t m;
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|
vm_object_t object;
|
|
vm_pindex_t pindex;
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|
vm_page_t first_m;
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|
vm_object_t first_object;
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|
vm_pindex_t first_pindex;
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|
vm_map_t map;
|
|
vm_map_entry_t entry;
|
|
int lookup_still_valid;
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|
struct vnode *vp;
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|
};
|
|
|
|
static __inline void
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|
release_page(struct faultstate *fs)
|
|
{
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|
vm_page_lock_queues();
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|
vm_page_wakeup(fs->m);
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|
vm_page_deactivate(fs->m);
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|
vm_page_unlock_queues();
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|
fs->m = NULL;
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|
}
|
|
|
|
static __inline void
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|
unlock_map(struct faultstate *fs)
|
|
{
|
|
if (fs->lookup_still_valid) {
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|
vm_map_lookup_done(fs->map, fs->entry);
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|
fs->lookup_still_valid = FALSE;
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|
}
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|
}
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|
|
|
static void
|
|
_unlock_things(struct faultstate *fs, int dealloc)
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|
{
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|
|
|
vm_object_pip_wakeup(fs->object);
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|
VM_OBJECT_UNLOCK(fs->object);
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|
if (fs->object != fs->first_object) {
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|
VM_OBJECT_LOCK(fs->first_object);
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|
vm_page_lock_queues();
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vm_page_free(fs->first_m);
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vm_page_unlock_queues();
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vm_object_pip_wakeup(fs->first_object);
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|
VM_OBJECT_UNLOCK(fs->first_object);
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fs->first_m = NULL;
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|
}
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|
if (dealloc) {
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|
vm_object_deallocate(fs->first_object);
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|
}
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|
unlock_map(fs);
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if (fs->vp != NULL) {
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|
mtx_lock(&Giant);
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|
vput(fs->vp);
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|
mtx_unlock(&Giant);
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|
fs->vp = NULL;
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}
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if (dealloc && !fs->map->system_map)
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|
VM_UNLOCK_GIANT();
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|
}
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|
|
|
#define unlock_things(fs) _unlock_things(fs, 0)
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|
#define unlock_and_deallocate(fs) _unlock_things(fs, 1)
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|
|
|
/*
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|
* TRYPAGER - used by vm_fault to calculate whether the pager for the
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|
* current object *might* contain the page.
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|
*
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|
* default objects are zero-fill, there is no real pager.
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|
*/
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|
#define TRYPAGER (fs.object->type != OBJT_DEFAULT && \
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|
(((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired))
|
|
|
|
/*
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|
* vm_fault:
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|
*
|
|
* Handle a page fault occurring at the given address,
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|
* requiring the given permissions, in the map specified.
|
|
* If successful, the page is inserted into the
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|
* associated physical map.
|
|
*
|
|
* NOTE: the given address should be truncated to the
|
|
* proper page address.
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|
*
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|
* KERN_SUCCESS is returned if the page fault is handled; otherwise,
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|
* a standard error specifying why the fault is fatal is returned.
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|
*
|
|
*
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|
* The map in question must be referenced, and remains so.
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|
* Caller may hold no locks.
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|
*/
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|
int
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|
vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
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|
int fault_flags)
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|
{
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|
vm_prot_t prot;
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|
int is_first_object_locked, result;
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|
boolean_t growstack, wired;
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|
int map_generation;
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vm_object_t next_object;
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|
vm_page_t marray[VM_FAULT_READ];
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int hardfault;
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|
int faultcount;
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|
struct faultstate fs;
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|
hardfault = 0;
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|
growstack = TRUE;
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atomic_add_int(&cnt.v_vm_faults, 1);
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|
RetryFault:;
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/*
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* Find the backing store object and offset into it to begin the
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* search.
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*/
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fs.map = map;
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result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry,
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&fs.first_object, &fs.first_pindex, &prot, &wired);
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if (result != KERN_SUCCESS) {
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if (result != KERN_PROTECTION_FAILURE ||
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(fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) {
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if (growstack && result == KERN_INVALID_ADDRESS &&
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map != kernel_map && curproc != NULL) {
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result = vm_map_growstack(curproc, vaddr);
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if (result != KERN_SUCCESS)
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return (KERN_FAILURE);
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growstack = FALSE;
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goto RetryFault;
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}
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return (result);
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|
}
|
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|
|
/*
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|
* If we are user-wiring a r/w segment, and it is COW, then
|
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* we need to do the COW operation. Note that we don't COW
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|
* currently RO sections now, because it is NOT desirable
|
|
* to COW .text. We simply keep .text from ever being COW'ed
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|
* and take the heat that one cannot debug wired .text sections.
|
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*/
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result = vm_map_lookup(&fs.map, vaddr,
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VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE,
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&fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired);
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|
if (result != KERN_SUCCESS)
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|
return (result);
|
|
|
|
/*
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|
* If we don't COW now, on a user wire, the user will never
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|
* be able to write to the mapping. If we don't make this
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* restriction, the bookkeeping would be nearly impossible.
|
|
*
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* XXX The following assignment modifies the map without
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* holding a write lock on it.
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|
*/
|
|
if ((fs.entry->protection & VM_PROT_WRITE) == 0)
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fs.entry->max_protection &= ~VM_PROT_WRITE;
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}
|
|
|
|
map_generation = fs.map->timestamp;
|
|
|
|
if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
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panic("vm_fault: fault on nofault entry, addr: %lx",
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|
(u_long)vaddr);
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|
}
|
|
|
|
/*
|
|
* Make a reference to this object to prevent its disposal while we
|
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* are messing with it. Once we have the reference, the map is free
|
|
* to be diddled. Since objects reference their shadows (and copies),
|
|
* they will stay around as well.
|
|
*
|
|
* Bump the paging-in-progress count to prevent size changes (e.g.
|
|
* truncation operations) during I/O. This must be done after
|
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* obtaining the vnode lock in order to avoid possible deadlocks.
|
|
*
|
|
* XXX vnode_pager_lock() can block without releasing the map lock.
|
|
*/
|
|
if (!fs.map->system_map)
|
|
mtx_lock(&Giant);
|
|
VM_OBJECT_LOCK(fs.first_object);
|
|
vm_object_reference_locked(fs.first_object);
|
|
fs.vp = vnode_pager_lock(fs.first_object);
|
|
KASSERT(fs.vp == NULL || !fs.map->system_map,
|
|
("vm_fault: vnode-backed object mapped by system map"));
|
|
if (debug_mpsafevm && !fs.map->system_map)
|
|
mtx_unlock(&Giant);
|
|
vm_object_pip_add(fs.first_object, 1);
|
|
|
|
fs.lookup_still_valid = TRUE;
|
|
|
|
if (wired)
|
|
fault_type = prot;
|
|
|
|
fs.first_m = NULL;
|
|
|
|
/*
|
|
* Search for the page at object/offset.
|
|
*/
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
while (TRUE) {
|
|
/*
|
|
* If the object is dead, we stop here
|
|
*/
|
|
if (fs.object->flags & OBJ_DEAD) {
|
|
unlock_and_deallocate(&fs);
|
|
return (KERN_PROTECTION_FAILURE);
|
|
}
|
|
|
|
/*
|
|
* See if page is resident
|
|
*/
|
|
fs.m = vm_page_lookup(fs.object, fs.pindex);
|
|
if (fs.m != NULL) {
|
|
int queue;
|
|
|
|
/*
|
|
* check for page-based copy on write.
|
|
* We check fs.object == fs.first_object so
|
|
* as to ensure the legacy COW mechanism is
|
|
* used when the page in question is part of
|
|
* a shadow object. Otherwise, vm_page_cowfault()
|
|
* removes the page from the backing object,
|
|
* which is not what we want.
|
|
*/
|
|
vm_page_lock_queues();
|
|
if ((fs.m->cow) &&
|
|
(fault_type & VM_PROT_WRITE) &&
|
|
(fs.object == fs.first_object)) {
|
|
vm_page_cowfault(fs.m);
|
|
vm_page_unlock_queues();
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
|
|
/*
|
|
* Wait/Retry if the page is busy. We have to do this
|
|
* if the page is busy via either PG_BUSY or
|
|
* vm_page_t->busy because the vm_pager may be using
|
|
* vm_page_t->busy for pageouts ( and even pageins if
|
|
* it is the vnode pager ), and we could end up trying
|
|
* to pagein and pageout the same page simultaneously.
|
|
*
|
|
* We can theoretically allow the busy case on a read
|
|
* fault if the page is marked valid, but since such
|
|
* pages are typically already pmap'd, putting that
|
|
* special case in might be more effort then it is
|
|
* worth. We cannot under any circumstances mess
|
|
* around with a vm_page_t->busy page except, perhaps,
|
|
* to pmap it.
|
|
*/
|
|
if ((fs.m->flags & PG_BUSY) || fs.m->busy) {
|
|
vm_page_unlock_queues();
|
|
unlock_things(&fs);
|
|
vm_page_lock_queues();
|
|
if (!vm_page_sleep_if_busy(fs.m, TRUE, "vmpfw"))
|
|
vm_page_unlock_queues();
|
|
atomic_add_int(&cnt.v_intrans, 1);
|
|
if (!fs.map->system_map)
|
|
VM_UNLOCK_GIANT();
|
|
vm_object_deallocate(fs.first_object);
|
|
goto RetryFault;
|
|
}
|
|
queue = fs.m->queue;
|
|
|
|
vm_pageq_remove_nowakeup(fs.m);
|
|
|
|
if ((queue - fs.m->pc) == PQ_CACHE && vm_page_count_severe()) {
|
|
vm_page_activate(fs.m);
|
|
vm_page_unlock_queues();
|
|
unlock_and_deallocate(&fs);
|
|
VM_WAITPFAULT;
|
|
goto RetryFault;
|
|
}
|
|
|
|
/*
|
|
* Mark page busy for other processes, and the
|
|
* pagedaemon. If it still isn't completely valid
|
|
* (readable), jump to readrest, else break-out ( we
|
|
* found the page ).
|
|
*/
|
|
vm_page_busy(fs.m);
|
|
vm_page_unlock_queues();
|
|
if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) &&
|
|
fs.m->object != kernel_object && fs.m->object != kmem_object) {
|
|
goto readrest;
|
|
}
|
|
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Page is not resident, If this is the search termination
|
|
* or the pager might contain the page, allocate a new page.
|
|
*/
|
|
if (TRYPAGER || fs.object == fs.first_object) {
|
|
if (fs.pindex >= fs.object->size) {
|
|
unlock_and_deallocate(&fs);
|
|
return (KERN_PROTECTION_FAILURE);
|
|
}
|
|
|
|
/*
|
|
* Allocate a new page for this object/offset pair.
|
|
*/
|
|
fs.m = NULL;
|
|
if (!vm_page_count_severe()) {
|
|
fs.m = vm_page_alloc(fs.object, fs.pindex,
|
|
(fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO);
|
|
}
|
|
if (fs.m == NULL) {
|
|
unlock_and_deallocate(&fs);
|
|
VM_WAITPFAULT;
|
|
goto RetryFault;
|
|
}
|
|
}
|
|
|
|
readrest:
|
|
/*
|
|
* We have found a valid page or we have allocated a new page.
|
|
* The page thus may not be valid or may not be entirely
|
|
* valid.
|
|
*
|
|
* Attempt to fault-in the page if there is a chance that the
|
|
* pager has it, and potentially fault in additional pages
|
|
* at the same time.
|
|
*/
|
|
if (TRYPAGER) {
|
|
int rv;
|
|
int reqpage;
|
|
int ahead, behind;
|
|
u_char behavior = vm_map_entry_behavior(fs.entry);
|
|
|
|
if (behavior == MAP_ENTRY_BEHAV_RANDOM) {
|
|
ahead = 0;
|
|
behind = 0;
|
|
} else {
|
|
behind = (vaddr - fs.entry->start) >> PAGE_SHIFT;
|
|
if (behind > VM_FAULT_READ_BEHIND)
|
|
behind = VM_FAULT_READ_BEHIND;
|
|
|
|
ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1;
|
|
if (ahead > VM_FAULT_READ_AHEAD)
|
|
ahead = VM_FAULT_READ_AHEAD;
|
|
}
|
|
is_first_object_locked = FALSE;
|
|
if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL ||
|
|
(behavior != MAP_ENTRY_BEHAV_RANDOM &&
|
|
fs.pindex >= fs.entry->lastr &&
|
|
fs.pindex < fs.entry->lastr + VM_FAULT_READ)) &&
|
|
(fs.first_object == fs.object ||
|
|
(is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) &&
|
|
fs.first_object->type != OBJT_DEVICE) {
|
|
vm_pindex_t firstpindex, tmppindex;
|
|
|
|
if (fs.first_pindex < 2 * VM_FAULT_READ)
|
|
firstpindex = 0;
|
|
else
|
|
firstpindex = fs.first_pindex - 2 * VM_FAULT_READ;
|
|
|
|
vm_page_lock_queues();
|
|
/*
|
|
* note: partially valid pages cannot be
|
|
* included in the lookahead - NFS piecemeal
|
|
* writes will barf on it badly.
|
|
*/
|
|
for (tmppindex = fs.first_pindex - 1;
|
|
tmppindex >= firstpindex;
|
|
--tmppindex) {
|
|
vm_page_t mt;
|
|
|
|
mt = vm_page_lookup(fs.first_object, tmppindex);
|
|
if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL))
|
|
break;
|
|
if (mt->busy ||
|
|
(mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) ||
|
|
mt->hold_count ||
|
|
mt->wire_count)
|
|
continue;
|
|
pmap_remove_all(mt);
|
|
if (mt->dirty) {
|
|
vm_page_deactivate(mt);
|
|
} else {
|
|
vm_page_cache(mt);
|
|
}
|
|
}
|
|
vm_page_unlock_queues();
|
|
ahead += behind;
|
|
behind = 0;
|
|
}
|
|
if (is_first_object_locked)
|
|
VM_OBJECT_UNLOCK(fs.first_object);
|
|
/*
|
|
* now we find out if any other pages should be paged
|
|
* in at this time this routine checks to see if the
|
|
* pages surrounding this fault reside in the same
|
|
* object as the page for this fault. If they do,
|
|
* then they are faulted in also into the object. The
|
|
* array "marray" returned contains an array of
|
|
* vm_page_t structs where one of them is the
|
|
* vm_page_t passed to the routine. The reqpage
|
|
* return value is the index into the marray for the
|
|
* vm_page_t passed to the routine.
|
|
*
|
|
* fs.m plus the additional pages are PG_BUSY'd.
|
|
*
|
|
* XXX vm_fault_additional_pages() can block
|
|
* without releasing the map lock.
|
|
*/
|
|
faultcount = vm_fault_additional_pages(
|
|
fs.m, behind, ahead, marray, &reqpage);
|
|
|
|
/*
|
|
* update lastr imperfectly (we do not know how much
|
|
* getpages will actually read), but good enough.
|
|
*
|
|
* XXX The following assignment modifies the map
|
|
* without holding a write lock on it.
|
|
*/
|
|
fs.entry->lastr = fs.pindex + faultcount - behind;
|
|
|
|
/*
|
|
* Call the pager to retrieve the data, if any, after
|
|
* releasing the lock on the map. We hold a ref on
|
|
* fs.object and the pages are PG_BUSY'd.
|
|
*/
|
|
unlock_map(&fs);
|
|
|
|
rv = faultcount ?
|
|
vm_pager_get_pages(fs.object, marray, faultcount,
|
|
reqpage) : VM_PAGER_FAIL;
|
|
|
|
if (rv == VM_PAGER_OK) {
|
|
/*
|
|
* Found the page. Leave it busy while we play
|
|
* with it.
|
|
*/
|
|
|
|
/*
|
|
* Relookup in case pager changed page. Pager
|
|
* is responsible for disposition of old page
|
|
* if moved.
|
|
*/
|
|
fs.m = vm_page_lookup(fs.object, fs.pindex);
|
|
if (!fs.m) {
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
|
|
hardfault++;
|
|
break; /* break to PAGE HAS BEEN FOUND */
|
|
}
|
|
/*
|
|
* Remove the bogus page (which does not exist at this
|
|
* object/offset); before doing so, we must get back
|
|
* our object lock to preserve our invariant.
|
|
*
|
|
* Also wake up any other process that may want to bring
|
|
* in this page.
|
|
*
|
|
* If this is the top-level object, we must leave the
|
|
* busy page to prevent another process from rushing
|
|
* past us, and inserting the page in that object at
|
|
* the same time that we are.
|
|
*/
|
|
if (rv == VM_PAGER_ERROR)
|
|
printf("vm_fault: pager read error, pid %d (%s)\n",
|
|
curproc->p_pid, curproc->p_comm);
|
|
/*
|
|
* Data outside the range of the pager or an I/O error
|
|
*/
|
|
/*
|
|
* XXX - the check for kernel_map is a kludge to work
|
|
* around having the machine panic on a kernel space
|
|
* fault w/ I/O error.
|
|
*/
|
|
if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) ||
|
|
(rv == VM_PAGER_BAD)) {
|
|
vm_page_lock_queues();
|
|
vm_page_free(fs.m);
|
|
vm_page_unlock_queues();
|
|
fs.m = NULL;
|
|
unlock_and_deallocate(&fs);
|
|
return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE);
|
|
}
|
|
if (fs.object != fs.first_object) {
|
|
vm_page_lock_queues();
|
|
vm_page_free(fs.m);
|
|
vm_page_unlock_queues();
|
|
fs.m = NULL;
|
|
/*
|
|
* XXX - we cannot just fall out at this
|
|
* point, m has been freed and is invalid!
|
|
*/
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We get here if the object has default pager (or unwiring)
|
|
* or the pager doesn't have the page.
|
|
*/
|
|
if (fs.object == fs.first_object)
|
|
fs.first_m = fs.m;
|
|
|
|
/*
|
|
* Move on to the next object. Lock the next object before
|
|
* unlocking the current one.
|
|
*/
|
|
fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset);
|
|
next_object = fs.object->backing_object;
|
|
if (next_object == NULL) {
|
|
/*
|
|
* If there's no object left, fill the page in the top
|
|
* object with zeros.
|
|
*/
|
|
if (fs.object != fs.first_object) {
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_UNLOCK(fs.object);
|
|
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
fs.m = fs.first_m;
|
|
VM_OBJECT_LOCK(fs.object);
|
|
}
|
|
fs.first_m = NULL;
|
|
|
|
/*
|
|
* Zero the page if necessary and mark it valid.
|
|
*/
|
|
if ((fs.m->flags & PG_ZERO) == 0) {
|
|
pmap_zero_page(fs.m);
|
|
} else {
|
|
atomic_add_int(&cnt.v_ozfod, 1);
|
|
}
|
|
atomic_add_int(&cnt.v_zfod, 1);
|
|
fs.m->valid = VM_PAGE_BITS_ALL;
|
|
break; /* break to PAGE HAS BEEN FOUND */
|
|
} else {
|
|
KASSERT(fs.object != next_object,
|
|
("object loop %p", next_object));
|
|
VM_OBJECT_LOCK(next_object);
|
|
vm_object_pip_add(next_object, 1);
|
|
if (fs.object != fs.first_object)
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_UNLOCK(fs.object);
|
|
fs.object = next_object;
|
|
}
|
|
}
|
|
|
|
KASSERT((fs.m->flags & PG_BUSY) != 0,
|
|
("vm_fault: not busy after main loop"));
|
|
|
|
/*
|
|
* PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
|
|
* is held.]
|
|
*/
|
|
|
|
/*
|
|
* If the page is being written, but isn't already owned by the
|
|
* top-level object, we have to copy it into a new page owned by the
|
|
* top-level object.
|
|
*/
|
|
if (fs.object != fs.first_object) {
|
|
/*
|
|
* We only really need to copy if we want to write it.
|
|
*/
|
|
if (fault_type & VM_PROT_WRITE) {
|
|
/*
|
|
* This allows pages to be virtually copied from a
|
|
* backing_object into the first_object, where the
|
|
* backing object has no other refs to it, and cannot
|
|
* gain any more refs. Instead of a bcopy, we just
|
|
* move the page from the backing object to the
|
|
* first object. Note that we must mark the page
|
|
* dirty in the first object so that it will go out
|
|
* to swap when needed.
|
|
*/
|
|
is_first_object_locked = FALSE;
|
|
if (
|
|
/*
|
|
* Only one shadow object
|
|
*/
|
|
(fs.object->shadow_count == 1) &&
|
|
/*
|
|
* No COW refs, except us
|
|
*/
|
|
(fs.object->ref_count == 1) &&
|
|
/*
|
|
* No one else can look this object up
|
|
*/
|
|
(fs.object->handle == NULL) &&
|
|
/*
|
|
* No other ways to look the object up
|
|
*/
|
|
((fs.object->type == OBJT_DEFAULT) ||
|
|
(fs.object->type == OBJT_SWAP)) &&
|
|
(is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) &&
|
|
/*
|
|
* We don't chase down the shadow chain
|
|
*/
|
|
fs.object == fs.first_object->backing_object) {
|
|
vm_page_lock_queues();
|
|
/*
|
|
* get rid of the unnecessary page
|
|
*/
|
|
pmap_remove_all(fs.first_m);
|
|
vm_page_free(fs.first_m);
|
|
/*
|
|
* grab the page and put it into the
|
|
* process'es object. The page is
|
|
* automatically made dirty.
|
|
*/
|
|
vm_page_rename(fs.m, fs.first_object, fs.first_pindex);
|
|
vm_page_busy(fs.m);
|
|
vm_page_unlock_queues();
|
|
fs.first_m = fs.m;
|
|
fs.m = NULL;
|
|
atomic_add_int(&cnt.v_cow_optim, 1);
|
|
} else {
|
|
/*
|
|
* Oh, well, lets copy it.
|
|
*/
|
|
pmap_copy_page(fs.m, fs.first_m);
|
|
fs.first_m->valid = VM_PAGE_BITS_ALL;
|
|
}
|
|
if (fs.m) {
|
|
/*
|
|
* We no longer need the old page or object.
|
|
*/
|
|
release_page(&fs);
|
|
}
|
|
/*
|
|
* fs.object != fs.first_object due to above
|
|
* conditional
|
|
*/
|
|
vm_object_pip_wakeup(fs.object);
|
|
VM_OBJECT_UNLOCK(fs.object);
|
|
/*
|
|
* Only use the new page below...
|
|
*/
|
|
fs.object = fs.first_object;
|
|
fs.pindex = fs.first_pindex;
|
|
fs.m = fs.first_m;
|
|
if (!is_first_object_locked)
|
|
VM_OBJECT_LOCK(fs.object);
|
|
atomic_add_int(&cnt.v_cow_faults, 1);
|
|
} else {
|
|
prot &= ~VM_PROT_WRITE;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* We must verify that the maps have not changed since our last
|
|
* lookup.
|
|
*/
|
|
if (!fs.lookup_still_valid) {
|
|
vm_object_t retry_object;
|
|
vm_pindex_t retry_pindex;
|
|
vm_prot_t retry_prot;
|
|
|
|
if (!vm_map_trylock_read(fs.map)) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
fs.lookup_still_valid = TRUE;
|
|
if (fs.map->timestamp != map_generation) {
|
|
result = vm_map_lookup_locked(&fs.map, vaddr, fault_type,
|
|
&fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired);
|
|
|
|
/*
|
|
* If we don't need the page any longer, put it on the active
|
|
* list (the easiest thing to do here). If no one needs it,
|
|
* pageout will grab it eventually.
|
|
*/
|
|
if (result != KERN_SUCCESS) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
|
|
/*
|
|
* If retry of map lookup would have blocked then
|
|
* retry fault from start.
|
|
*/
|
|
if (result == KERN_FAILURE)
|
|
goto RetryFault;
|
|
return (result);
|
|
}
|
|
if ((retry_object != fs.first_object) ||
|
|
(retry_pindex != fs.first_pindex)) {
|
|
release_page(&fs);
|
|
unlock_and_deallocate(&fs);
|
|
goto RetryFault;
|
|
}
|
|
|
|
/*
|
|
* Check whether the protection has changed or the object has
|
|
* been copied while we left the map unlocked. Changing from
|
|
* read to write permission is OK - we leave the page
|
|
* write-protected, and catch the write fault. Changing from
|
|
* write to read permission means that we can't mark the page
|
|
* write-enabled after all.
|
|
*/
|
|
prot &= retry_prot;
|
|
}
|
|
}
|
|
if (prot & VM_PROT_WRITE) {
|
|
vm_page_lock_queues();
|
|
vm_page_flag_set(fs.m, PG_WRITEABLE);
|
|
vm_object_set_writeable_dirty(fs.m->object);
|
|
|
|
/*
|
|
* If the fault is a write, we know that this page is being
|
|
* written NOW so dirty it explicitly to save on
|
|
* pmap_is_modified() calls later.
|
|
*
|
|
* If this is a NOSYNC mmap we do not want to set PG_NOSYNC
|
|
* if the page is already dirty to prevent data written with
|
|
* the expectation of being synced from not being synced.
|
|
* Likewise if this entry does not request NOSYNC then make
|
|
* sure the page isn't marked NOSYNC. Applications sharing
|
|
* data should use the same flags to avoid ping ponging.
|
|
*
|
|
* Also tell the backing pager, if any, that it should remove
|
|
* any swap backing since the page is now dirty.
|
|
*/
|
|
if (fs.entry->eflags & MAP_ENTRY_NOSYNC) {
|
|
if (fs.m->dirty == 0)
|
|
vm_page_flag_set(fs.m, PG_NOSYNC);
|
|
} else {
|
|
vm_page_flag_clear(fs.m, PG_NOSYNC);
|
|
}
|
|
vm_page_unlock_queues();
|
|
if (fault_flags & VM_FAULT_DIRTY) {
|
|
vm_page_dirty(fs.m);
|
|
vm_pager_page_unswapped(fs.m);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Page had better still be busy
|
|
*/
|
|
KASSERT(fs.m->flags & PG_BUSY,
|
|
("vm_fault: page %p not busy!", fs.m));
|
|
/*
|
|
* Sanity check: page must be completely valid or it is not fit to
|
|
* map into user space. vm_pager_get_pages() ensures this.
|
|
*/
|
|
if (fs.m->valid != VM_PAGE_BITS_ALL) {
|
|
vm_page_zero_invalid(fs.m, TRUE);
|
|
printf("Warning: page %p partially invalid on fault\n", fs.m);
|
|
}
|
|
VM_OBJECT_UNLOCK(fs.object);
|
|
|
|
/*
|
|
* Put this page into the physical map. We had to do the unlock above
|
|
* because pmap_enter() may sleep. We don't put the page
|
|
* back on the active queue until later so that the pageout daemon
|
|
* won't find it (yet).
|
|
*/
|
|
pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired);
|
|
if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) {
|
|
vm_fault_prefault(fs.map->pmap, vaddr, fs.entry);
|
|
}
|
|
VM_OBJECT_LOCK(fs.object);
|
|
vm_page_lock_queues();
|
|
vm_page_flag_set(fs.m, PG_REFERENCED);
|
|
|
|
/*
|
|
* If the page is not wired down, then put it where the pageout daemon
|
|
* can find it.
|
|
*/
|
|
if (fault_flags & VM_FAULT_WIRE_MASK) {
|
|
if (wired)
|
|
vm_page_wire(fs.m);
|
|
else
|
|
vm_page_unwire(fs.m, 1);
|
|
} else {
|
|
vm_page_activate(fs.m);
|
|
}
|
|
vm_page_wakeup(fs.m);
|
|
vm_page_unlock_queues();
|
|
|
|
/*
|
|
* Unlock everything, and return
|
|
*/
|
|
unlock_and_deallocate(&fs);
|
|
PROC_LOCK(curproc);
|
|
if ((curproc->p_sflag & PS_INMEM) && curproc->p_stats) {
|
|
if (hardfault) {
|
|
curproc->p_stats->p_ru.ru_majflt++;
|
|
} else {
|
|
curproc->p_stats->p_ru.ru_minflt++;
|
|
}
|
|
}
|
|
PROC_UNLOCK(curproc);
|
|
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* vm_fault_prefault provides a quick way of clustering
|
|
* pagefaults into a processes address space. It is a "cousin"
|
|
* of vm_map_pmap_enter, except it runs at page fault time instead
|
|
* of mmap time.
|
|
*/
|
|
static void
|
|
vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry)
|
|
{
|
|
int i;
|
|
vm_offset_t addr, starta;
|
|
vm_pindex_t pindex;
|
|
vm_page_t m, mpte;
|
|
vm_object_t object;
|
|
|
|
if (!curthread || (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)))
|
|
return;
|
|
|
|
object = entry->object.vm_object;
|
|
|
|
starta = addra - PFBAK * PAGE_SIZE;
|
|
if (starta < entry->start) {
|
|
starta = entry->start;
|
|
} else if (starta > addra) {
|
|
starta = 0;
|
|
}
|
|
|
|
mpte = NULL;
|
|
for (i = 0; i < PAGEORDER_SIZE; i++) {
|
|
vm_object_t backing_object, lobject;
|
|
|
|
addr = addra + prefault_pageorder[i];
|
|
if (addr > addra + (PFFOR * PAGE_SIZE))
|
|
addr = 0;
|
|
|
|
if (addr < starta || addr >= entry->end)
|
|
continue;
|
|
|
|
if (!pmap_is_prefaultable(pmap, addr))
|
|
continue;
|
|
|
|
pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
|
|
lobject = object;
|
|
VM_OBJECT_LOCK(lobject);
|
|
while ((m = vm_page_lookup(lobject, pindex)) == NULL &&
|
|
lobject->type == OBJT_DEFAULT &&
|
|
(backing_object = lobject->backing_object) != NULL) {
|
|
if (lobject->backing_object_offset & PAGE_MASK)
|
|
break;
|
|
pindex += lobject->backing_object_offset >> PAGE_SHIFT;
|
|
VM_OBJECT_LOCK(backing_object);
|
|
VM_OBJECT_UNLOCK(lobject);
|
|
lobject = backing_object;
|
|
}
|
|
/*
|
|
* give-up when a page is not in memory
|
|
*/
|
|
if (m == NULL) {
|
|
VM_OBJECT_UNLOCK(lobject);
|
|
break;
|
|
}
|
|
vm_page_lock_queues();
|
|
if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
|
|
(m->busy == 0) &&
|
|
(m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) {
|
|
|
|
if ((m->queue - m->pc) == PQ_CACHE) {
|
|
vm_page_deactivate(m);
|
|
}
|
|
vm_page_busy(m);
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(lobject);
|
|
mpte = pmap_enter_quick(pmap, addr, m, mpte);
|
|
VM_OBJECT_LOCK(lobject);
|
|
vm_page_lock_queues();
|
|
vm_page_wakeup(m);
|
|
}
|
|
vm_page_unlock_queues();
|
|
VM_OBJECT_UNLOCK(lobject);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* vm_fault_quick:
|
|
*
|
|
* Ensure that the requested virtual address, which may be in userland,
|
|
* is valid. Fault-in the page if necessary. Return -1 on failure.
|
|
*/
|
|
int
|
|
vm_fault_quick(caddr_t v, int prot)
|
|
{
|
|
int r;
|
|
|
|
if (prot & VM_PROT_WRITE)
|
|
r = subyte(v, fubyte(v));
|
|
else
|
|
r = fubyte(v);
|
|
return(r);
|
|
}
|
|
|
|
/*
|
|
* vm_fault_wire:
|
|
*
|
|
* Wire down a range of virtual addresses in a map.
|
|
*/
|
|
int
|
|
vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
|
|
boolean_t user_wire, boolean_t fictitious)
|
|
{
|
|
vm_offset_t va;
|
|
int rv;
|
|
|
|
/*
|
|
* We simulate a fault to get the page and enter it in the physical
|
|
* map. For user wiring, we only ask for read access on currently
|
|
* read-only sections.
|
|
*/
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
rv = vm_fault(map, va,
|
|
user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE,
|
|
user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING);
|
|
if (rv) {
|
|
if (va != start)
|
|
vm_fault_unwire(map, start, va, fictitious);
|
|
return (rv);
|
|
}
|
|
}
|
|
return (KERN_SUCCESS);
|
|
}
|
|
|
|
/*
|
|
* vm_fault_unwire:
|
|
*
|
|
* Unwire a range of virtual addresses in a map.
|
|
*/
|
|
void
|
|
vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
|
|
boolean_t fictitious)
|
|
{
|
|
vm_paddr_t pa;
|
|
vm_offset_t va;
|
|
pmap_t pmap;
|
|
|
|
pmap = vm_map_pmap(map);
|
|
|
|
/*
|
|
* Since the pages are wired down, we must be able to get their
|
|
* mappings from the physical map system.
|
|
*/
|
|
for (va = start; va < end; va += PAGE_SIZE) {
|
|
pa = pmap_extract(pmap, va);
|
|
if (pa != 0) {
|
|
pmap_change_wiring(pmap, va, FALSE);
|
|
if (!fictitious) {
|
|
vm_page_lock_queues();
|
|
vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
|
|
vm_page_unlock_queues();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Routine:
|
|
* vm_fault_copy_entry
|
|
* Function:
|
|
* Copy all of the pages from a wired-down map entry to another.
|
|
*
|
|
* In/out conditions:
|
|
* The source and destination maps must be locked for write.
|
|
* The source map entry must be wired down (or be a sharing map
|
|
* entry corresponding to a main map entry that is wired down).
|
|
*/
|
|
void
|
|
vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry)
|
|
vm_map_t dst_map;
|
|
vm_map_t src_map;
|
|
vm_map_entry_t dst_entry;
|
|
vm_map_entry_t src_entry;
|
|
{
|
|
vm_object_t backing_object, dst_object, object;
|
|
vm_object_t src_object;
|
|
vm_ooffset_t dst_offset;
|
|
vm_ooffset_t src_offset;
|
|
vm_pindex_t pindex;
|
|
vm_prot_t prot;
|
|
vm_offset_t vaddr;
|
|
vm_page_t dst_m;
|
|
vm_page_t src_m;
|
|
|
|
#ifdef lint
|
|
src_map++;
|
|
#endif /* lint */
|
|
|
|
src_object = src_entry->object.vm_object;
|
|
src_offset = src_entry->offset;
|
|
|
|
/*
|
|
* Create the top-level object for the destination entry. (Doesn't
|
|
* actually shadow anything - we copy the pages directly.)
|
|
*/
|
|
dst_object = vm_object_allocate(OBJT_DEFAULT,
|
|
(vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start));
|
|
|
|
VM_OBJECT_LOCK(dst_object);
|
|
dst_entry->object.vm_object = dst_object;
|
|
dst_entry->offset = 0;
|
|
|
|
prot = dst_entry->max_protection;
|
|
|
|
/*
|
|
* Loop through all of the pages in the entry's range, copying each
|
|
* one from the source object (it should be there) to the destination
|
|
* object.
|
|
*/
|
|
for (vaddr = dst_entry->start, dst_offset = 0;
|
|
vaddr < dst_entry->end;
|
|
vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
|
|
|
|
/*
|
|
* Allocate a page in the destination object
|
|
*/
|
|
do {
|
|
dst_m = vm_page_alloc(dst_object,
|
|
OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL);
|
|
if (dst_m == NULL) {
|
|
VM_OBJECT_UNLOCK(dst_object);
|
|
VM_WAIT;
|
|
VM_OBJECT_LOCK(dst_object);
|
|
}
|
|
} while (dst_m == NULL);
|
|
|
|
/*
|
|
* Find the page in the source object, and copy it in.
|
|
* (Because the source is wired down, the page will be in
|
|
* memory.)
|
|
*/
|
|
VM_OBJECT_LOCK(src_object);
|
|
object = src_object;
|
|
pindex = 0;
|
|
while ((src_m = vm_page_lookup(object, pindex +
|
|
OFF_TO_IDX(dst_offset + src_offset))) == NULL &&
|
|
(src_entry->protection & VM_PROT_WRITE) == 0 &&
|
|
(backing_object = object->backing_object) != NULL) {
|
|
/*
|
|
* Allow fallback to backing objects if we are reading.
|
|
*/
|
|
VM_OBJECT_LOCK(backing_object);
|
|
pindex += OFF_TO_IDX(object->backing_object_offset);
|
|
VM_OBJECT_UNLOCK(object);
|
|
object = backing_object;
|
|
}
|
|
if (src_m == NULL)
|
|
panic("vm_fault_copy_wired: page missing");
|
|
pmap_copy_page(src_m, dst_m);
|
|
VM_OBJECT_UNLOCK(object);
|
|
dst_m->valid = VM_PAGE_BITS_ALL;
|
|
VM_OBJECT_UNLOCK(dst_object);
|
|
|
|
/*
|
|
* Enter it in the pmap...
|
|
*/
|
|
pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE);
|
|
VM_OBJECT_LOCK(dst_object);
|
|
vm_page_lock_queues();
|
|
if ((prot & VM_PROT_WRITE) != 0)
|
|
vm_page_flag_set(dst_m, PG_WRITEABLE);
|
|
|
|
/*
|
|
* Mark it no longer busy, and put it on the active list.
|
|
*/
|
|
vm_page_activate(dst_m);
|
|
vm_page_wakeup(dst_m);
|
|
vm_page_unlock_queues();
|
|
}
|
|
VM_OBJECT_UNLOCK(dst_object);
|
|
}
|
|
|
|
|
|
/*
|
|
* This routine checks around the requested page for other pages that
|
|
* might be able to be faulted in. This routine brackets the viable
|
|
* pages for the pages to be paged in.
|
|
*
|
|
* Inputs:
|
|
* m, rbehind, rahead
|
|
*
|
|
* Outputs:
|
|
* marray (array of vm_page_t), reqpage (index of requested page)
|
|
*
|
|
* Return value:
|
|
* number of pages in marray
|
|
*
|
|
* This routine can't block.
|
|
*/
|
|
static int
|
|
vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage)
|
|
vm_page_t m;
|
|
int rbehind;
|
|
int rahead;
|
|
vm_page_t *marray;
|
|
int *reqpage;
|
|
{
|
|
int i,j;
|
|
vm_object_t object;
|
|
vm_pindex_t pindex, startpindex, endpindex, tpindex;
|
|
vm_page_t rtm;
|
|
int cbehind, cahead;
|
|
|
|
VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED);
|
|
|
|
object = m->object;
|
|
pindex = m->pindex;
|
|
|
|
/*
|
|
* we don't fault-ahead for device pager
|
|
*/
|
|
if (object->type == OBJT_DEVICE) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* if the requested page is not available, then give up now
|
|
*/
|
|
if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
|
|
return 0;
|
|
}
|
|
|
|
if ((cbehind == 0) && (cahead == 0)) {
|
|
*reqpage = 0;
|
|
marray[0] = m;
|
|
return 1;
|
|
}
|
|
|
|
if (rahead > cahead) {
|
|
rahead = cahead;
|
|
}
|
|
|
|
if (rbehind > cbehind) {
|
|
rbehind = cbehind;
|
|
}
|
|
|
|
/*
|
|
* try to do any readahead that we might have free pages for.
|
|
*/
|
|
if ((rahead + rbehind) >
|
|
((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) {
|
|
pagedaemon_wakeup();
|
|
marray[0] = m;
|
|
*reqpage = 0;
|
|
return 1;
|
|
}
|
|
|
|
/*
|
|
* scan backward for the read behind pages -- in memory
|
|
*/
|
|
if (pindex > 0) {
|
|
if (rbehind > pindex) {
|
|
rbehind = pindex;
|
|
startpindex = 0;
|
|
} else {
|
|
startpindex = pindex - rbehind;
|
|
}
|
|
|
|
for (tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) {
|
|
if (vm_page_lookup(object, tpindex)) {
|
|
startpindex = tpindex + 1;
|
|
break;
|
|
}
|
|
if (tpindex == 0)
|
|
break;
|
|
}
|
|
|
|
for (i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) {
|
|
|
|
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
|
|
if (rtm == NULL) {
|
|
vm_page_lock_queues();
|
|
for (j = 0; j < i; j++) {
|
|
vm_page_free(marray[j]);
|
|
}
|
|
vm_page_unlock_queues();
|
|
marray[0] = m;
|
|
*reqpage = 0;
|
|
return 1;
|
|
}
|
|
|
|
marray[i] = rtm;
|
|
}
|
|
} else {
|
|
startpindex = 0;
|
|
i = 0;
|
|
}
|
|
|
|
marray[i] = m;
|
|
/* page offset of the required page */
|
|
*reqpage = i;
|
|
|
|
tpindex = pindex + 1;
|
|
i++;
|
|
|
|
/*
|
|
* scan forward for the read ahead pages
|
|
*/
|
|
endpindex = tpindex + rahead;
|
|
if (endpindex > object->size)
|
|
endpindex = object->size;
|
|
|
|
for (; tpindex < endpindex; i++, tpindex++) {
|
|
|
|
if (vm_page_lookup(object, tpindex)) {
|
|
break;
|
|
}
|
|
|
|
rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL);
|
|
if (rtm == NULL) {
|
|
break;
|
|
}
|
|
|
|
marray[i] = rtm;
|
|
}
|
|
|
|
/* return number of bytes of pages */
|
|
return i;
|
|
}
|