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freebsd/sys/vm/device_pager.c
Attilio Rao 89f6b8632c Switch the vm_object mutex to be a rwlock. This will enable in the
future further optimizations where the vm_object lock will be held
in read mode most of the time the page cache resident pool of pages
are accessed for reading purposes.

The change is mostly mechanical but few notes are reported:
* The KPI changes as follow:
  - VM_OBJECT_LOCK() -> VM_OBJECT_WLOCK()
  - VM_OBJECT_TRYLOCK() -> VM_OBJECT_TRYWLOCK()
  - VM_OBJECT_UNLOCK() -> VM_OBJECT_WUNLOCK()
  - VM_OBJECT_LOCK_ASSERT(MA_OWNED) -> VM_OBJECT_ASSERT_WLOCKED()
    (in order to avoid visibility of implementation details)
  - The read-mode operations are added:
    VM_OBJECT_RLOCK(), VM_OBJECT_TRYRLOCK(), VM_OBJECT_RUNLOCK(),
    VM_OBJECT_ASSERT_RLOCKED(), VM_OBJECT_ASSERT_LOCKED()
* The vm/vm_pager.h namespace pollution avoidance (forcing requiring
  sys/mutex.h in consumers directly to cater its inlining functions
  using VM_OBJECT_LOCK()) imposes that all the vm/vm_pager.h
  consumers now must include also sys/rwlock.h.
* zfs requires a quite convoluted fix to include FreeBSD rwlocks into
  the compat layer because the name clash between FreeBSD and solaris
  versions must be avoided.
  At this purpose zfs redefines the vm_object locking functions
  directly, isolating the FreeBSD components in specific compat stubs.

The KPI results heavilly broken by this commit.  Thirdy part ports must
be updated accordingly (I can think off-hand of VirtualBox, for example).

Sponsored by:	EMC / Isilon storage division
Reviewed by:	jeff
Reviewed by:	pjd (ZFS specific review)
Discussed with:	alc
Tested by:	pho
2013-03-09 02:32:23 +00:00

433 lines
11 KiB
C

/*-
* 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.
* 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.
*
* @(#)device_pager.c 8.1 (Berkeley) 6/11/93
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/mutex.h>
#include <sys/mman.h>
#include <sys/rwlock.h>
#include <sys/sx.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_phys.h>
#include <vm/uma.h>
static void dev_pager_init(void);
static vm_object_t dev_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
vm_ooffset_t, struct ucred *);
static void dev_pager_dealloc(vm_object_t);
static int dev_pager_getpages(vm_object_t, vm_page_t *, int, int);
static void dev_pager_putpages(vm_object_t, vm_page_t *, int,
boolean_t, int *);
static boolean_t dev_pager_haspage(vm_object_t, vm_pindex_t, int *,
int *);
static void dev_pager_free_page(vm_object_t object, vm_page_t m);
/* list of device pager objects */
static struct pagerlst dev_pager_object_list;
/* protect list manipulation */
static struct mtx dev_pager_mtx;
struct pagerops devicepagerops = {
.pgo_init = dev_pager_init,
.pgo_alloc = dev_pager_alloc,
.pgo_dealloc = dev_pager_dealloc,
.pgo_getpages = dev_pager_getpages,
.pgo_putpages = dev_pager_putpages,
.pgo_haspage = dev_pager_haspage,
};
struct pagerops mgtdevicepagerops = {
.pgo_alloc = dev_pager_alloc,
.pgo_dealloc = dev_pager_dealloc,
.pgo_getpages = dev_pager_getpages,
.pgo_putpages = dev_pager_putpages,
.pgo_haspage = dev_pager_haspage,
};
static int old_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred, u_short *color);
static void old_dev_pager_dtor(void *handle);
static int old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset,
int prot, vm_page_t *mres);
static struct cdev_pager_ops old_dev_pager_ops = {
.cdev_pg_ctor = old_dev_pager_ctor,
.cdev_pg_dtor = old_dev_pager_dtor,
.cdev_pg_fault = old_dev_pager_fault
};
static void
dev_pager_init()
{
TAILQ_INIT(&dev_pager_object_list);
mtx_init(&dev_pager_mtx, "dev_pager list", NULL, MTX_DEF);
}
vm_object_t
cdev_pager_lookup(void *handle)
{
vm_object_t object;
mtx_lock(&dev_pager_mtx);
object = vm_pager_object_lookup(&dev_pager_object_list, handle);
mtx_unlock(&dev_pager_mtx);
return (object);
}
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 object, object1;
vm_pindex_t pindex;
u_short color;
if (tp != OBJT_DEVICE && tp != OBJT_MGTDEVICE)
return (NULL);
/*
* Offset should be page aligned.
*/
if (foff & PAGE_MASK)
return (NULL);
size = round_page(size);
pindex = OFF_TO_IDX(foff + size);
if (ops->cdev_pg_ctor(handle, size, prot, foff, cred, &color) != 0)
return (NULL);
mtx_lock(&dev_pager_mtx);
/*
* Look up pager, creating as necessary.
*/
object1 = NULL;
object = vm_pager_object_lookup(&dev_pager_object_list, handle);
if (object == NULL) {
/*
* Allocate object and associate it with the pager. Initialize
* the object's pg_color based upon the physical address of the
* device's memory.
*/
mtx_unlock(&dev_pager_mtx);
object1 = vm_object_allocate(tp, pindex);
object1->flags |= OBJ_COLORED;
object1->pg_color = color;
object1->handle = handle;
object1->un_pager.devp.ops = ops;
object1->un_pager.devp.dev = handle;
TAILQ_INIT(&object1->un_pager.devp.devp_pglist);
mtx_lock(&dev_pager_mtx);
object = vm_pager_object_lookup(&dev_pager_object_list, handle);
if (object != NULL) {
/*
* We raced with other thread while allocating object.
*/
if (pindex > object->size)
object->size = pindex;
} else {
object = object1;
object1 = NULL;
object->handle = handle;
TAILQ_INSERT_TAIL(&dev_pager_object_list, object,
pager_object_list);
KASSERT(object->type == tp,
("Inconsistent device pager type %p %d", object, tp));
}
} else {
if (pindex > object->size)
object->size = pindex;
}
mtx_unlock(&dev_pager_mtx);
if (object1 != NULL) {
object1->handle = object1;
mtx_lock(&dev_pager_mtx);
TAILQ_INSERT_TAIL(&dev_pager_object_list, object1,
pager_object_list);
mtx_unlock(&dev_pager_mtx);
vm_object_deallocate(object1);
}
return (object);
}
static vm_object_t
dev_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred)
{
return (cdev_pager_allocate(handle, OBJT_DEVICE, &old_dev_pager_ops,
size, prot, foff, cred));
}
void
cdev_pager_free_page(vm_object_t object, vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(object);
if (object->type == OBJT_MGTDEVICE) {
KASSERT((m->oflags & VPO_UNMANAGED) == 0, ("unmanaged %p", m));
pmap_remove_all(m);
vm_page_lock(m);
vm_page_remove(m);
vm_page_unlock(m);
} else if (object->type == OBJT_DEVICE)
dev_pager_free_page(object, m);
}
static void
dev_pager_free_page(vm_object_t object, vm_page_t m)
{
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT((object->type == OBJT_DEVICE &&
(m->oflags & VPO_UNMANAGED) != 0),
("Managed device or page obj %p m %p", object, m));
TAILQ_REMOVE(&object->un_pager.devp.devp_pglist, m, pageq);
vm_page_putfake(m);
}
static void
dev_pager_dealloc(object)
vm_object_t object;
{
vm_page_t m;
VM_OBJECT_WUNLOCK(object);
object->un_pager.devp.ops->cdev_pg_dtor(object->un_pager.devp.dev);
mtx_lock(&dev_pager_mtx);
TAILQ_REMOVE(&dev_pager_object_list, object, pager_object_list);
mtx_unlock(&dev_pager_mtx);
VM_OBJECT_WLOCK(object);
if (object->type == OBJT_DEVICE) {
/*
* Free up our fake pages.
*/
while ((m = TAILQ_FIRST(&object->un_pager.devp.devp_pglist))
!= NULL)
dev_pager_free_page(object, m);
}
}
static int
dev_pager_getpages(vm_object_t object, vm_page_t *ma, int count, int reqpage)
{
int error, i;
VM_OBJECT_ASSERT_WLOCKED(object);
error = object->un_pager.devp.ops->cdev_pg_fault(object,
IDX_TO_OFF(ma[reqpage]->pindex), PROT_READ, &ma[reqpage]);
VM_OBJECT_ASSERT_WLOCKED(object);
for (i = 0; i < count; i++) {
if (i != reqpage) {
vm_page_lock(ma[i]);
vm_page_free(ma[i]);
vm_page_unlock(ma[i]);
}
}
if (error == VM_PAGER_OK) {
KASSERT((object->type == OBJT_DEVICE &&
(ma[reqpage]->oflags & VPO_UNMANAGED) != 0) ||
(object->type == OBJT_MGTDEVICE &&
(ma[reqpage]->oflags & VPO_UNMANAGED) == 0),
("Wrong page type %p %p", ma[reqpage], object));
if (object->type == OBJT_DEVICE) {
TAILQ_INSERT_TAIL(&object->un_pager.devp.devp_pglist,
ma[reqpage], pageq);
}
}
return (error);
}
static int
old_dev_pager_fault(vm_object_t object, vm_ooffset_t offset, int prot,
vm_page_t *mres)
{
vm_pindex_t pidx;
vm_paddr_t paddr;
vm_page_t m_paddr, page;
struct cdev *dev;
struct cdevsw *csw;
struct file *fpop;
struct thread *td;
vm_memattr_t memattr;
int ref, ret;
pidx = OFF_TO_IDX(offset);
memattr = object->memattr;
VM_OBJECT_WUNLOCK(object);
dev = object->handle;
csw = dev_refthread(dev, &ref);
if (csw == NULL) {
VM_OBJECT_WLOCK(object);
return (VM_PAGER_FAIL);
}
td = curthread;
fpop = td->td_fpop;
td->td_fpop = NULL;
ret = csw->d_mmap(dev, offset, &paddr, prot, &memattr);
td->td_fpop = fpop;
dev_relthread(dev, ref);
if (ret != 0) {
printf(
"WARNING: dev_pager_getpage: map function returns error %d", ret);
VM_OBJECT_WLOCK(object);
return (VM_PAGER_FAIL);
}
/* If "paddr" is a real page, perform a sanity check on "memattr". */
if ((m_paddr = vm_phys_paddr_to_vm_page(paddr)) != NULL &&
pmap_page_get_memattr(m_paddr) != memattr) {
memattr = pmap_page_get_memattr(m_paddr);
printf(
"WARNING: A device driver has set \"memattr\" inconsistently.\n");
}
if (((*mres)->flags & PG_FICTITIOUS) != 0) {
/*
* If the passed in result page is a fake page, update it with
* the new physical address.
*/
page = *mres;
VM_OBJECT_WLOCK(object);
vm_page_updatefake(page, paddr, memattr);
} else {
/*
* Replace the passed in reqpage page with our own fake page and
* free up the all of the original pages.
*/
page = vm_page_getfake(paddr, memattr);
VM_OBJECT_WLOCK(object);
vm_page_lock(*mres);
vm_page_free(*mres);
vm_page_unlock(*mres);
*mres = page;
vm_page_insert(page, object, pidx);
}
page->valid = VM_PAGE_BITS_ALL;
return (VM_PAGER_OK);
}
static void
dev_pager_putpages(object, m, count, sync, rtvals)
vm_object_t object;
vm_page_t *m;
int count;
boolean_t sync;
int *rtvals;
{
panic("dev_pager_putpage called");
}
static boolean_t
dev_pager_haspage(object, pindex, before, after)
vm_object_t object;
vm_pindex_t pindex;
int *before;
int *after;
{
if (before != NULL)
*before = 0;
if (after != NULL)
*after = 0;
return (TRUE);
}
static int
old_dev_pager_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t foff, struct ucred *cred, u_short *color)
{
struct cdev *dev;
struct cdevsw *csw;
vm_memattr_t dummy;
vm_ooffset_t off;
vm_paddr_t paddr;
unsigned int npages;
int ref;
/*
* Make sure this device can be mapped.
*/
dev = handle;
csw = dev_refthread(dev, &ref);
if (csw == NULL)
return (ENXIO);
/*
* Check that the specified range of the device allows the desired
* protection.
*
* XXX assumes VM_PROT_* == PROT_*
*/
npages = OFF_TO_IDX(size);
for (off = foff; npages--; off += PAGE_SIZE) {
if (csw->d_mmap(dev, off, &paddr, (int)prot, &dummy) != 0) {
dev_relthread(dev, ref);
return (EINVAL);
}
}
dev_ref(dev);
dev_relthread(dev, ref);
*color = atop(paddr) - OFF_TO_IDX(off - PAGE_SIZE);
return (0);
}
static void
old_dev_pager_dtor(void *handle)
{
dev_rel(handle);
}