freebsd-dev/sys/vm/vm_swap.c
Robert Watson edfa785a8e Introduce per-swap area accounting in the VM system, and export
this information via the vm.nswapdev sysctl (number of swap areas)
and vm.swapdevX nodes (where X is the device), which contain the MIBs
dev, blocks, used, and flags.  These changes are required to allow
top and other userland swap-monitoring utilities to run without
setgid kmem.

Submitted by:	Thomas Moestl <tmoestl@gmx.net>
Reviewed by:	freebsd-audit
2001-02-23 18:46:21 +00:00

363 lines
9.5 KiB
C

/*
* Copyright (c) 1982, 1986, 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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.
*
* @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
* $FreeBSD$
*/
#include "opt_swap.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/proc.h>
#include <sys/namei.h>
#include <sys/dmap.h> /* XXX */
#include <sys/vnode.h>
#include <sys/fcntl.h>
#include <sys/blist.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/conf.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_zone.h>
#include <vm/swap_pager.h>
/*
* Indirect driver for multi-controller paging.
*/
#ifndef NSWAPDEV
#define NSWAPDEV 4
#endif
static struct swdevt should_be_malloced[NSWAPDEV];
struct swdevt *swdevt = should_be_malloced;
static int nswap; /* first block after the interleaved devs */
int nswdev = NSWAPDEV;
int vm_swap_size;
static int ncswdev = 0; /* # of configured swap devs */
SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD,
&ncswdev, 0, "Number of swap devices");
static int swapdev_strategy __P((struct vop_strategy_args *ap));
struct vnode *swapdev_vp;
/*
* swapdev_strategy:
*
* VOP_STRATEGY() for swapdev_vp.
* Perform swap strategy interleave device selection.
*
* The bp is expected to be locked and *not* B_DONE on call.
*/
static int
swapdev_strategy(ap)
struct vop_strategy_args /* {
struct vnode *a_vp;
struct buf *a_bp;
} */ *ap;
{
int s, sz, off, seg, index;
register struct swdevt *sp;
struct vnode *vp;
struct buf *bp;
bp = ap->a_bp;
sz = howmany(bp->b_bcount, PAGE_SIZE);
/*
* Convert interleaved swap into per-device swap. Note that
* the block size is left in PAGE_SIZE'd chunks (for the newswap)
* here.
*/
if (nswdev > 1) {
off = bp->b_blkno % dmmax;
if (off + sz > dmmax) {
bp->b_error = EINVAL;
bp->b_ioflags |= BIO_ERROR;
bufdone(bp);
return 0;
}
seg = bp->b_blkno / dmmax;
index = seg % nswdev;
seg /= nswdev;
bp->b_blkno = seg * dmmax + off;
} else {
index = 0;
}
sp = &swdevt[index];
if (bp->b_blkno + sz > sp->sw_nblks) {
bp->b_error = EINVAL;
bp->b_ioflags |= BIO_ERROR;
bufdone(bp);
return 0;
}
bp->b_dev = sp->sw_device;
if (sp->sw_vp == NULL) {
bp->b_error = ENODEV;
bp->b_ioflags |= BIO_ERROR;
bufdone(bp);
return 0;
}
/*
* Convert from PAGE_SIZE'd to DEV_BSIZE'd chunks for the actual I/O
*/
bp->b_blkno = ctodb(bp->b_blkno);
vhold(sp->sw_vp);
s = splvm();
if (bp->b_iocmd == BIO_WRITE) {
vp = bp->b_vp;
if (vp) {
vp->v_numoutput--;
if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
vp->v_flag &= ~VBWAIT;
wakeup(&vp->v_numoutput);
}
}
sp->sw_vp->v_numoutput++;
}
pbreassignbuf(bp, sp->sw_vp);
splx(s);
BUF_STRATEGY(bp);
return 0;
}
/*
* Create a special vnode op vector for swapdev_vp - we only use
* VOP_STRATEGY(), everything else returns an error.
*/
vop_t **swapdev_vnodeop_p;
static struct vnodeopv_entry_desc swapdev_vnodeop_entries[] = {
{ &vop_default_desc, (vop_t *) vop_defaultop },
{ &vop_strategy_desc, (vop_t *) swapdev_strategy },
{ NULL, NULL }
};
static struct vnodeopv_desc swapdev_vnodeop_opv_desc =
{ &swapdev_vnodeop_p, swapdev_vnodeop_entries };
VNODEOP_SET(swapdev_vnodeop_opv_desc);
/*
* System call swapon(name) enables swapping on device name,
* which must be in the swdevsw. Return EBUSY
* if already swapping on this device.
*/
#ifndef _SYS_SYSPROTO_H_
struct swapon_args {
char *name;
};
#endif
/* ARGSUSED */
int
swapon(p, uap)
struct proc *p;
struct swapon_args *uap;
{
register struct vnode *vp;
struct nameidata nd;
int error;
error = suser(p);
if (error)
return (error);
/*
* Swap metadata may not fit in the KVM if we have physical
* memory of >1GB.
*/
if (swap_zone == NULL)
return (ENOMEM);
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, p);
error = namei(&nd);
if (error)
return (error);
NDFREE(&nd, NDF_ONLY_PNBUF);
vp = nd.ni_vp;
vn_isdisk(vp, &error);
if (!error)
error = swaponvp(p, vp, vp->v_rdev, 0);
if (error)
vrele(vp);
return (error);
}
/*
* Swfree(index) frees the index'th portion of the swap map.
* Each of the nswdev devices provides 1/nswdev'th of the swap
* space, which is laid out with blocks of dmmax pages circularly
* among the devices.
*
* The new swap code uses page-sized blocks. The old swap code used
* DEV_BSIZE'd chunks.
*
* XXX locking when multiple swapon's run in parallel
*/
int
swaponvp(p, vp, dev, nblks)
struct proc *p;
struct vnode *vp;
dev_t dev;
u_long nblks;
{
int index;
register struct swdevt *sp;
register swblk_t vsbase;
register long blk;
swblk_t dvbase;
int error;
u_long aligned_nblks;
struct sysctl_oid *oid;
char name[11];
if (!swapdev_vp) {
error = getnewvnode(VT_NON, NULL, swapdev_vnodeop_p,
&swapdev_vp);
if (error)
panic("Cannot get vnode for swapdev");
swapdev_vp->v_type = VNON; /* Untyped */
}
ASSERT_VOP_UNLOCKED(vp, "swaponvp");
for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
if (sp->sw_vp == vp)
return EBUSY;
if (!sp->sw_vp)
goto found;
}
return EINVAL;
found:
(void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
error = VOP_OPEN(vp, FREAD | FWRITE, p->p_ucred, p);
(void) VOP_UNLOCK(vp, 0, p);
if (error)
return (error);
if (nblks == 0 && dev != NODEV && (devsw(dev)->d_psize == 0 ||
(nblks = (*devsw(dev)->d_psize) (dev)) == -1)) {
(void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
return (ENXIO);
}
if (nblks == 0) {
(void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
return (ENXIO);
}
/*
* If we go beyond this, we get overflows in the radix
* tree bitmap code.
*/
if (nblks > 0x40000000 / BLIST_META_RADIX / nswdev) {
printf("exceeded maximum of %d blocks per swap unit\n",
0x40000000 / BLIST_META_RADIX / nswdev);
(void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
return (ENXIO);
}
/*
* nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
* First chop nblks off to page-align it, then convert.
*
* sw->sw_nblks is in page-sized chunks now too.
*/
nblks &= ~(ctodb(1) - 1);
nblks = dbtoc(nblks);
sp->sw_vp = vp;
sp->sw_dev = dev2udev(dev);
sp->sw_device = dev;
sp->sw_flags |= SW_FREED;
sp->sw_nblks = nblks;
sp->sw_used = 0;
/*
* nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not
* DEV_BSIZE'd. aligned_nblks is used to calculate the
* size of the swap bitmap, taking into account the stripe size.
*/
aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
if (aligned_nblks * nswdev > nswap)
nswap = aligned_nblks * nswdev;
if (swapblist == NULL)
swapblist = blist_create(nswap);
else
blist_resize(&swapblist, nswap, 0);
for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
blk = min(nblks - dvbase, dmmax);
vsbase = index * dmmax + dvbase * nswdev;
blist_free(swapblist, vsbase, blk);
vm_swap_size += blk;
}
/*
* Add sysctl entries for new swap area. XXX: if some day swap devices
* can be removed, add an oid member to swdevt.
*/
if (snprintf(name, sizeof(name), "swapdev%d", ncswdev) < sizeof(name)) {
oid = SYSCTL_ADD_NODE(NULL, SYSCTL_STATIC_CHILDREN(_vm),
OID_AUTO, name, CTLFLAG_RD, NULL, "Swap device stats");
if (oid != NULL) {
SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"flags", CTLFLAG_RD, &sp->sw_flags, 0, "Flags");
SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"nblks", CTLFLAG_RD, &sp->sw_nblks, 0,
"Number of blocks");
SYSCTL_ADD_INT(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"used", CTLFLAG_RD, &sp->sw_used, 0,
"Number of blocks in use");
SYSCTL_ADD_OPAQUE(NULL, SYSCTL_CHILDREN(oid), OID_AUTO,
"dev", CTLFLAG_RD, &sp->sw_dev, sizeof(sp->sw_dev),
"T,dev_t", "Device");
}
} else
printf("XXX: swaponvp() name buffer too small!\n");
ncswdev++;
return (0);
}