freebsd-dev/sys/vm/vm_pager.c
Mark Johnston b0acc3f11b vm_pager: Optimize an assertion
Obtained from:	jeff (object_concurrency patches)
Reviewed by:	kib
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D32946
2021-11-15 13:01:30 -05:00

618 lines
15 KiB
C

/*-
* SPDX-License-Identifier: (BSD-3-Clause AND MIT-CMU)
*
* 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. 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.
*/
/*
* Paging space routine stubs. Emulates a matchmaker-like interface
* for builtin pagers.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_param.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/ucred.h>
#include <sys/malloc.h>
#include <sys/rwlock.h>
#include <sys/user.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_pager.h>
#include <vm/vm_extern.h>
#include <vm/uma.h>
uma_zone_t pbuf_zone;
static int pbuf_init(void *, int, int);
static int pbuf_ctor(void *, int, void *, int);
static void pbuf_dtor(void *, int, void *);
static int dead_pager_getpages(vm_object_t, vm_page_t *, int, int *, int *);
static vm_object_t dead_pager_alloc(void *, vm_ooffset_t, vm_prot_t,
vm_ooffset_t, struct ucred *);
static void dead_pager_putpages(vm_object_t, vm_page_t *, int, int, int *);
static boolean_t dead_pager_haspage(vm_object_t, vm_pindex_t, int *, int *);
static void dead_pager_dealloc(vm_object_t);
static void dead_pager_getvp(vm_object_t, struct vnode **, bool *);
static int
dead_pager_getpages(vm_object_t obj, vm_page_t *ma, int count, int *rbehind,
int *rahead)
{
return (VM_PAGER_FAIL);
}
static vm_object_t
dead_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
vm_ooffset_t off, struct ucred *cred)
{
return (NULL);
}
static void
dead_pager_putpages(vm_object_t object, vm_page_t *m, int count,
int flags, int *rtvals)
{
int i;
for (i = 0; i < count; i++)
rtvals[i] = VM_PAGER_AGAIN;
}
static int
dead_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *prev, int *next)
{
if (prev != NULL)
*prev = 0;
if (next != NULL)
*next = 0;
return (FALSE);
}
static void
dead_pager_dealloc(vm_object_t object)
{
}
static void
dead_pager_getvp(vm_object_t object, struct vnode **vpp, bool *vp_heldp)
{
/*
* For OBJT_DEAD objects, v_writecount was handled in
* vnode_pager_dealloc().
*/
}
static const struct pagerops deadpagerops = {
.pgo_kvme_type = KVME_TYPE_DEAD,
.pgo_alloc = dead_pager_alloc,
.pgo_dealloc = dead_pager_dealloc,
.pgo_getpages = dead_pager_getpages,
.pgo_putpages = dead_pager_putpages,
.pgo_haspage = dead_pager_haspage,
.pgo_getvp = dead_pager_getvp,
};
const struct pagerops *pagertab[16] __read_mostly = {
[OBJT_DEFAULT] = &defaultpagerops,
[OBJT_SWAP] = &swappagerops,
[OBJT_VNODE] = &vnodepagerops,
[OBJT_DEVICE] = &devicepagerops,
[OBJT_PHYS] = &physpagerops,
[OBJT_DEAD] = &deadpagerops,
[OBJT_SG] = &sgpagerops,
[OBJT_MGTDEVICE] = &mgtdevicepagerops,
};
static struct mtx pagertab_lock;
void
vm_pager_init(void)
{
const struct pagerops **pgops;
int i;
mtx_init(&pagertab_lock, "dynpag", NULL, MTX_DEF);
/*
* Initialize known pagers
*/
for (i = 0; i < OBJT_FIRST_DYN; i++) {
pgops = &pagertab[i];
if ((*pgops)->pgo_init != NULL)
(*(*pgops)->pgo_init)();
}
}
static int nswbuf_max;
void
vm_pager_bufferinit(void)
{
/* Main zone for paging bufs. */
pbuf_zone = uma_zcreate("pbuf",
sizeof(struct buf) + PBUF_PAGES * sizeof(vm_page_t),
pbuf_ctor, pbuf_dtor, pbuf_init, NULL, UMA_ALIGN_CACHE,
UMA_ZONE_NOFREE);
/* Few systems may still use this zone directly, so it needs a limit. */
nswbuf_max += uma_zone_set_max(pbuf_zone, NSWBUF_MIN);
}
uma_zone_t
pbuf_zsecond_create(const char *name, int max)
{
uma_zone_t zone;
zone = uma_zsecond_create(name, pbuf_ctor, pbuf_dtor, NULL, NULL,
pbuf_zone);
#ifdef KMSAN
/*
* Shrink the size of the pbuf pools if KMSAN is enabled, otherwise the
* shadows of the large KVA allocations eat up too much memory.
*/
max /= 3;
#endif
/*
* uma_prealloc() rounds up to items per slab. If we would prealloc
* immediately on every pbuf_zsecond_create(), we may accumulate too
* much of difference between hard limit and prealloced items, which
* means wasted memory.
*/
if (nswbuf_max > 0)
nswbuf_max += uma_zone_set_max(zone, max);
else
uma_prealloc(pbuf_zone, uma_zone_set_max(zone, max));
return (zone);
}
static void
pbuf_prealloc(void *arg __unused)
{
uma_prealloc(pbuf_zone, nswbuf_max);
nswbuf_max = -1;
}
SYSINIT(pbuf, SI_SUB_KTHREAD_BUF, SI_ORDER_ANY, pbuf_prealloc, NULL);
/*
* 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(objtype_t type, void *handle, vm_ooffset_t size,
vm_prot_t prot, vm_ooffset_t off, struct ucred *cred)
{
MPASS(type < nitems(pagertab));
return ((*pagertab[type]->pgo_alloc)(handle, size, prot, off, cred));
}
/*
* The object must be locked.
*/
void
vm_pager_deallocate(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
MPASS(object->type < nitems(pagertab));
(*pagertab[object->type]->pgo_dealloc) (object);
}
static void
vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count)
{
#ifdef INVARIANTS
/*
* All pages must be consecutive, busied, not mapped, not fully valid,
* not dirty and belong to the proper object. Some pages may be the
* bogus page, but the first and last pages must be a real ones.
*/
VM_OBJECT_ASSERT_UNLOCKED(object);
VM_OBJECT_ASSERT_PAGING(object);
KASSERT(count > 0, ("%s: 0 count", __func__));
for (int i = 0 ; i < count; i++) {
if (m[i] == bogus_page) {
KASSERT(i != 0 && i != count - 1,
("%s: page %d is the bogus page", __func__, i));
continue;
}
vm_page_assert_xbusied(m[i]);
KASSERT(!pmap_page_is_mapped(m[i]),
("%s: page %p is mapped", __func__, m[i]));
KASSERT(m[i]->valid != VM_PAGE_BITS_ALL,
("%s: request for a valid page %p", __func__, m[i]));
KASSERT(m[i]->dirty == 0,
("%s: page %p is dirty", __func__, m[i]));
KASSERT(m[i]->object == object,
("%s: wrong object %p/%p", __func__, object, m[i]->object));
KASSERT(m[i]->pindex == m[0]->pindex + i,
("%s: page %p isn't consecutive", __func__, m[i]));
}
#endif
}
/*
* Page in the pages for the object using its associated pager.
* The requested page must be fully valid on successful return.
*/
int
vm_pager_get_pages(vm_object_t object, vm_page_t *m, int count, int *rbehind,
int *rahead)
{
#ifdef INVARIANTS
vm_pindex_t pindex = m[0]->pindex;
#endif
int r;
MPASS(object->type < nitems(pagertab));
vm_pager_assert_in(object, m, count);
r = (*pagertab[object->type]->pgo_getpages)(object, m, count, rbehind,
rahead);
if (r != VM_PAGER_OK)
return (r);
for (int i = 0; i < count; i++) {
/*
* If pager has replaced a page, assert that it had
* updated the array.
*/
#ifdef INVARIANTS
KASSERT(m[i] == vm_page_relookup(object, pindex++),
("%s: mismatch page %p pindex %ju", __func__,
m[i], (uintmax_t )pindex - 1));
#endif
/*
* Zero out partially filled data.
*/
if (m[i]->valid != VM_PAGE_BITS_ALL)
vm_page_zero_invalid(m[i], TRUE);
}
return (VM_PAGER_OK);
}
int
vm_pager_get_pages_async(vm_object_t object, vm_page_t *m, int count,
int *rbehind, int *rahead, pgo_getpages_iodone_t iodone, void *arg)
{
MPASS(object->type < nitems(pagertab));
vm_pager_assert_in(object, m, count);
return ((*pagertab[object->type]->pgo_getpages_async)(object, m,
count, rbehind, rahead, iodone, arg));
}
/*
* vm_pager_put_pages() - inline, see vm/vm_pager.h
* vm_pager_has_page() - inline, see vm/vm_pager.h
*/
/*
* Search the specified pager object list for an object with the
* specified handle. If an object with the specified handle is found,
* increase its reference count and return it. Otherwise, return NULL.
*
* The pager object list must be locked.
*/
vm_object_t
vm_pager_object_lookup(struct pagerlst *pg_list, void *handle)
{
vm_object_t object;
TAILQ_FOREACH(object, pg_list, pager_object_list) {
if (object->handle == handle) {
VM_OBJECT_WLOCK(object);
if ((object->flags & OBJ_DEAD) == 0) {
vm_object_reference_locked(object);
VM_OBJECT_WUNLOCK(object);
break;
}
VM_OBJECT_WUNLOCK(object);
}
}
return (object);
}
int
vm_pager_alloc_dyn_type(struct pagerops *ops, int base_type)
{
int res;
mtx_lock(&pagertab_lock);
MPASS(base_type == -1 ||
(base_type >= OBJT_DEFAULT && base_type < nitems(pagertab)));
for (res = OBJT_FIRST_DYN; res < nitems(pagertab); res++) {
if (pagertab[res] == NULL)
break;
}
if (res == nitems(pagertab)) {
mtx_unlock(&pagertab_lock);
return (-1);
}
if (base_type != -1) {
MPASS(pagertab[base_type] != NULL);
#define FIX(n) \
if (ops->pgo_##n == NULL) \
ops->pgo_##n = pagertab[base_type]->pgo_##n
FIX(init);
FIX(alloc);
FIX(dealloc);
FIX(getpages);
FIX(getpages_async);
FIX(putpages);
FIX(haspage);
FIX(populate);
FIX(pageunswapped);
FIX(update_writecount);
FIX(release_writecount);
FIX(set_writeable_dirty);
FIX(mightbedirty);
FIX(getvp);
FIX(freespace);
#undef FIX
}
pagertab[res] = ops; /* XXXKIB should be rel, but acq is too much */
mtx_unlock(&pagertab_lock);
return (res);
}
void
vm_pager_free_dyn_type(objtype_t type)
{
MPASS(type >= OBJT_FIRST_DYN && type < nitems(pagertab));
mtx_lock(&pagertab_lock);
MPASS(pagertab[type] != NULL);
pagertab[type] = NULL;
mtx_unlock(&pagertab_lock);
}
static int
pbuf_ctor(void *mem, int size, void *arg, int flags)
{
struct buf *bp = mem;
bp->b_vp = NULL;
bp->b_bufobj = NULL;
/* copied from initpbuf() */
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
bp->b_data = bp->b_kvabase;
bp->b_xflags = 0;
bp->b_flags = B_MAXPHYS;
bp->b_ioflags = 0;
bp->b_iodone = NULL;
bp->b_error = 0;
BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
return (0);
}
static void
pbuf_dtor(void *mem, int size, void *arg)
{
struct buf *bp = mem;
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;
}
BUF_UNLOCK(bp);
}
static int
pbuf_init(void *mem, int size, int flags)
{
struct buf *bp = mem;
bp->b_kvabase = (void *)kva_alloc(ptoa(PBUF_PAGES));
if (bp->b_kvabase == NULL)
return (ENOMEM);
bp->b_kvasize = ptoa(PBUF_PAGES);
BUF_LOCKINIT(bp);
LIST_INIT(&bp->b_dep);
bp->b_rcred = bp->b_wcred = NOCRED;
bp->b_xflags = 0;
return (0);
}
/*
* Associate a p-buffer with a vnode.
*
* Also sets B_PAGING flag to indicate that vnode is not fully associated
* with the buffer. i.e. the bp has not been linked into the vnode or
* ref-counted.
*/
void
pbgetvp(struct vnode *vp, struct buf *bp)
{
KASSERT(bp->b_vp == NULL, ("pbgetvp: not free"));
KASSERT(bp->b_bufobj == NULL, ("pbgetvp: not free (bufobj)"));
bp->b_vp = vp;
bp->b_flags |= B_PAGING;
bp->b_bufobj = &vp->v_bufobj;
}
/*
* Associate a p-buffer with a vnode.
*
* Also sets B_PAGING flag to indicate that vnode is not fully associated
* with the buffer. i.e. the bp has not been linked into the vnode or
* ref-counted.
*/
void
pbgetbo(struct bufobj *bo, struct buf *bp)
{
KASSERT(bp->b_vp == NULL, ("pbgetbo: not free (vnode)"));
KASSERT(bp->b_bufobj == NULL, ("pbgetbo: not free (bufobj)"));
bp->b_flags |= B_PAGING;
bp->b_bufobj = bo;
}
/*
* Disassociate a p-buffer from a vnode.
*/
void
pbrelvp(struct buf *bp)
{
KASSERT(bp->b_vp != NULL, ("pbrelvp: NULL"));
KASSERT(bp->b_bufobj != NULL, ("pbrelvp: NULL bufobj"));
KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
("pbrelvp: pager buf on vnode list."));
bp->b_vp = NULL;
bp->b_bufobj = NULL;
bp->b_flags &= ~B_PAGING;
}
/*
* Disassociate a p-buffer from a bufobj.
*/
void
pbrelbo(struct buf *bp)
{
KASSERT(bp->b_vp == NULL, ("pbrelbo: vnode"));
KASSERT(bp->b_bufobj != NULL, ("pbrelbo: NULL bufobj"));
KASSERT((bp->b_xflags & (BX_VNDIRTY | BX_VNCLEAN)) == 0,
("pbrelbo: pager buf on vnode list."));
bp->b_bufobj = NULL;
bp->b_flags &= ~B_PAGING;
}
void
vm_object_set_writeable_dirty(vm_object_t object)
{
pgo_set_writeable_dirty_t *method;
MPASS(object->type < nitems(pagertab));
method = pagertab[object->type]->pgo_set_writeable_dirty;
if (method != NULL)
method(object);
}
bool
vm_object_mightbedirty(vm_object_t object)
{
pgo_mightbedirty_t *method;
MPASS(object->type < nitems(pagertab));
method = pagertab[object->type]->pgo_mightbedirty;
if (method == NULL)
return (false);
return (method(object));
}
/*
* Return the kvme type of the given object.
* If vpp is not NULL, set it to the object's vm_object_vnode() or NULL.
*/
int
vm_object_kvme_type(vm_object_t object, struct vnode **vpp)
{
VM_OBJECT_ASSERT_LOCKED(object);
MPASS(object->type < nitems(pagertab));
if (vpp != NULL)
*vpp = vm_object_vnode(object);
return (pagertab[object->type]->pgo_kvme_type);
}