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f-stack/freebsd/vm/vm_pager.c

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/*-
* 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.
* 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.
*
* 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(object, m, count, flags, rtvals)
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(object, pindex, prev, next)
vm_object_t object;
vm_pindex_t pindex;
int *prev;
int *next;
{
if (prev)
*prev = 0;
if (next)
*next = 0;
return FALSE;
}
static void
dead_pager_dealloc(object)
vm_object_t object;
{
return;
}
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()
{
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()
{
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(object)
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++) {
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);
}
/*
* 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) {
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_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;
}
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