freebsd-skq/sys/vm/vm_pager.c
imp 7e6cabd06e Renumber copyright clause 4
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by:	Jan Schaumann <jschauma@stevens.edu>
Pull Request:	https://github.com/freebsd/freebsd/pull/96
2017-02-28 23:42:47 +00:00

551 lines
14 KiB
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. 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 <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 <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>
int cluster_pbuf_freecnt = -1; /* unlimited to begin with */
struct buf *swbuf;
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 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 struct pagerops deadpagerops = {
.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,
};
struct pagerops *pagertab[] = {
&defaultpagerops, /* OBJT_DEFAULT */
&swappagerops, /* OBJT_SWAP */
&vnodepagerops, /* OBJT_VNODE */
&devicepagerops, /* OBJT_DEVICE */
&physpagerops, /* OBJT_PHYS */
&deadpagerops, /* OBJT_DEAD */
&sgpagerops, /* OBJT_SG */
&mgtdevicepagerops, /* OBJT_MGTDEVICE */
};
/*
* 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.
*/
struct mtx_padalign pbuf_mtx;
static TAILQ_HEAD(swqueue, buf) bswlist;
static int bswneeded;
vm_offset_t swapbkva; /* swap buffers kva */
void
vm_pager_init(void)
{
struct pagerops **pgops;
TAILQ_INIT(&bswlist);
/*
* Initialize known pagers
*/
for (pgops = pagertab; pgops < &pagertab[nitems(pagertab)]; pgops++)
if ((*pgops)->pgo_init != NULL)
(*(*pgops)->pgo_init)();
}
void
vm_pager_bufferinit(void)
{
struct buf *bp;
int i;
mtx_init(&pbuf_mtx, "pbuf mutex", NULL, MTX_DEF);
bp = swbuf;
/*
* Now set up swap and physical I/O buffer headers.
*/
for (i = 0; i < nswbuf; i++, bp++) {
TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
BUF_LOCKINIT(bp);
LIST_INIT(&bp->b_dep);
bp->b_rcred = bp->b_wcred = NOCRED;
bp->b_xflags = 0;
}
cluster_pbuf_freecnt = nswbuf / 2;
vnode_pbuf_freecnt = nswbuf / 2 + 1;
vnode_async_pbuf_freecnt = nswbuf / 2;
}
/*
* 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)
{
vm_object_t ret;
struct pagerops *ops;
ops = pagertab[type];
if (ops)
ret = (*ops->pgo_alloc)(handle, size, prot, off, cred);
else
ret = NULL;
return (ret);
}
/*
* The object must be locked.
*/
void
vm_pager_deallocate(vm_object_t object)
{
VM_OBJECT_ASSERT_WLOCKED(object);
(*pagertab[object->type]->pgo_dealloc) (object);
}
static void
vm_pager_assert_in(vm_object_t object, vm_page_t *m, int count)
{
#ifdef INVARIANTS
VM_OBJECT_ASSERT_WLOCKED(object);
KASSERT(count > 0, ("%s: 0 count", __func__));
/*
* All pages must be busied, not mapped, not fully valid,
* not dirty and belong to the proper object.
*/
for (int i = 0 ; i < count; i++) {
if (m[i] == bogus_page)
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));
}
#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;
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.
*/
KASSERT(m[i] == vm_page_lookup(object, pindex++),
("%s: mismatch page %p pindex %ju", __func__,
m[i], (uintmax_t )pindex - 1));
/*
* 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)
{
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);
}
/*
* initialize a physical buffer
*/
/*
* XXX This probably belongs in vfs_bio.c
*/
static void
initpbuf(struct buf *bp)
{
KASSERT(bp->b_bufobj == NULL, ("initpbuf with bufobj"));
KASSERT(bp->b_vp == NULL, ("initpbuf with vp"));
bp->b_rcred = NOCRED;
bp->b_wcred = NOCRED;
bp->b_qindex = 0; /* On no queue (QUEUE_NONE) */
bp->b_kvabase = (caddr_t)(MAXPHYS * (bp - swbuf)) + swapbkva;
bp->b_data = bp->b_kvabase;
bp->b_kvasize = MAXPHYS;
bp->b_flags = 0;
bp->b_xflags = 0;
bp->b_ioflags = 0;
bp->b_iodone = NULL;
bp->b_error = 0;
BUF_LOCK(bp, LK_EXCLUSIVE, NULL);
buf_track(bp, __func__);
}
/*
* allocate a physical buffer
*
* There are a limited number (nswbuf) of physical buffers. We need
* to make sure that no single subsystem is able to hog all of them,
* so each subsystem implements a counter which is typically initialized
* to 1/2 nswbuf. getpbuf() decrements this counter in allocation and
* increments it on release, and blocks if the counter hits zero. A
* subsystem may initialize the counter to -1 to disable the feature,
* but it must still be sure to match up all uses of getpbuf() with
* relpbuf() using the same variable.
*
* NOTE: pfreecnt can be NULL, but this 'feature' will be removed
* relatively soon when the rest of the subsystems get smart about it. XXX
*/
struct buf *
getpbuf(int *pfreecnt)
{
struct buf *bp;
mtx_lock(&pbuf_mtx);
for (;;) {
if (pfreecnt != NULL) {
while (*pfreecnt == 0) {
msleep(pfreecnt, &pbuf_mtx, PVM, "wswbuf0", 0);
}
}
/* get a bp from the swap buffer header pool */
if ((bp = TAILQ_FIRST(&bswlist)) != NULL)
break;
bswneeded = 1;
msleep(&bswneeded, &pbuf_mtx, PVM, "wswbuf1", 0);
/* loop in case someone else grabbed one */
}
TAILQ_REMOVE(&bswlist, bp, b_freelist);
if (pfreecnt)
--*pfreecnt;
mtx_unlock(&pbuf_mtx);
initpbuf(bp);
return (bp);
}
/*
* allocate a physical buffer, if one is available.
*
* Note that there is no NULL hack here - all subsystems using this
* call understand how to use pfreecnt.
*/
struct buf *
trypbuf(int *pfreecnt)
{
struct buf *bp;
mtx_lock(&pbuf_mtx);
if (*pfreecnt == 0 || (bp = TAILQ_FIRST(&bswlist)) == NULL) {
mtx_unlock(&pbuf_mtx);
return NULL;
}
TAILQ_REMOVE(&bswlist, bp, b_freelist);
--*pfreecnt;
mtx_unlock(&pbuf_mtx);
initpbuf(bp);
return (bp);
}
/*
* release a physical buffer
*
* NOTE: pfreecnt can be NULL, but this 'feature' will be removed
* relatively soon when the rest of the subsystems get smart about it. XXX
*/
void
relpbuf(struct buf *bp, int *pfreecnt)
{
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;
}
KASSERT(bp->b_vp == NULL, ("relpbuf with vp"));
KASSERT(bp->b_bufobj == NULL, ("relpbuf with bufobj"));
buf_track(bp, __func__);
BUF_UNLOCK(bp);
mtx_lock(&pbuf_mtx);
TAILQ_INSERT_HEAD(&bswlist, bp, b_freelist);
if (bswneeded) {
bswneeded = 0;
wakeup(&bswneeded);
}
if (pfreecnt) {
if (++*pfreecnt == 1)
wakeup(pfreecnt);
}
mtx_unlock(&pbuf_mtx);
}
/*
* 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;
}