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freebsd/sys/vm/vm_swap.c
Robert Watson 1b2c2ab29a Provide a mac_check_system_swapoff() entry point, which permits MAC
modules to authorize disabling of swap against a particular vnode.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories
2003-03-05 23:50:15 +00:00

543 lines
13 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_mac.h"
#include "opt_swap.h"
#include "opt_vm.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/vnode.h>
#include <sys/fcntl.h>
#include <sys/blist.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/conf.h>
#include <sys/disk.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/mac.h>
#include <sys/mount.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_param.h>
#include <vm/vm_pageout.h>
#include <vm/swap_pager.h>
#include <vm/uma.h>
/*
* Indirect driver for multi-controller paging.
*/
typedef int32_t swblk_t; /* swap offset */
#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 swdev_syscall_active = 0; /* serialize swap(on|off) */
static int swapdev_strategy(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;
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) {
VI_LOCK(vp);
vp->v_numoutput--;
if ((vp->v_iflag & VI_BWAIT) && vp->v_numoutput <= 0) {
vp->v_iflag &= ~VI_BWAIT;
wakeup(&vp->v_numoutput);
}
VI_UNLOCK(vp);
}
VI_LOCK(sp->sw_vp);
sp->sw_vp->v_numoutput++;
VI_UNLOCK(sp->sw_vp);
}
bp->b_vp = sp->sw_vp;
splx(s);
if (bp->b_vp->v_type == VCHR)
VOP_SPECSTRATEGY(bp->b_vp, bp);
else
VOP_STRATEGY(bp->b_vp, bp);
return 0;
}
/*
* Create a special vnode op vector for swapdev_vp - we only use
* VOP_STRATEGY() and reclaim; 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_reclaim_desc, (vop_t *) vop_null },
{ &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
/*
* MPSAFE
*/
/* ARGSUSED */
int
swapon(td, uap)
struct thread *td;
struct swapon_args *uap;
{
struct vattr attr;
struct vnode *vp;
struct nameidata nd;
int error;
mtx_lock(&Giant);
error = suser(td);
if (error)
goto done2;
while (swdev_syscall_active)
tsleep(&swdev_syscall_active, PUSER - 1, "swpon", 0);
swdev_syscall_active = 1;
/*
* Swap metadata may not fit in the KVM if we have physical
* memory of >1GB.
*/
if (swap_zone == NULL) {
error = ENOMEM;
goto done;
}
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td);
error = namei(&nd);
if (error)
goto done;
NDFREE(&nd, NDF_ONLY_PNBUF);
vp = nd.ni_vp;
if (vn_isdisk(vp, &error))
error = swaponvp(td, vp, vp->v_rdev, 0);
else if (vp->v_type == VREG &&
(vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 &&
(error = VOP_GETATTR(vp, &attr, td->td_ucred, td)) == 0) {
/*
* Allow direct swapping to NFS regular files in the same
* way that nfs_mountroot() sets up diskless swapping.
*/
error = swaponvp(td, vp, NODEV, attr.va_size / DEV_BSIZE);
}
if (error)
vrele(vp);
done:
swdev_syscall_active = 0;
wakeup_one(&swdev_syscall_active);
done2:
mtx_unlock(&Giant);
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.
*/
int
swaponvp(td, vp, dev, nblks)
struct thread *td;
struct vnode *vp;
dev_t dev;
u_long nblks;
{
int index;
struct swdevt *sp;
swblk_t vsbase;
long blk;
swblk_t dvbase;
int error;
u_long aligned_nblks;
off_t mediasize;
if (!swapdev_vp) {
error = getnewvnode("none", 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, td);
#ifdef MAC
error = mac_check_system_swapon(td->td_ucred, vp);
if (error == 0)
#endif
error = VOP_OPEN(vp, FREAD | FWRITE, td->td_ucred, td);
(void) VOP_UNLOCK(vp, 0, td);
if (error)
return (error);
error = VOP_IOCTL(vp, DIOCGMEDIASIZE, (caddr_t)&mediasize,
FREAD, td->td_ucred, td);
if (error == 0)
nblks = mediasize / DEV_BSIZE;
else
nblks = 0;
/*
* XXX: We should also check that the sectorsize makes sense
* XXX: it should be a power of two, no larger than the page size.
*/
if (nblks == 0) {
(void) VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td);
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, td->td_ucred, td);
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;
}
swap_pager_full = 0;
return (0);
}
/*
* SYSCALL: swapoff(devname)
*
* Disable swapping on the given device.
*/
#ifndef _SYS_SYSPROTO_H_
struct swapoff_args {
char *name;
};
#endif
/*
* MPSAFE
*/
/* ARGSUSED */
int
swapoff(td, uap)
struct thread *td;
struct swapoff_args *uap;
{
struct vnode *vp;
struct nameidata nd;
struct swdevt *sp;
swblk_t dvbase, vsbase;
u_long nblks, aligned_nblks, blk;
int error, index;
mtx_lock(&Giant);
error = suser(td);
if (error)
goto done2;
while (swdev_syscall_active)
tsleep(&swdev_syscall_active, PUSER - 1, "swpoff", 0);
swdev_syscall_active = 1;
NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, td);
error = namei(&nd);
if (error)
goto done;
NDFREE(&nd, NDF_ONLY_PNBUF);
vp = nd.ni_vp;
for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
if (sp->sw_vp == vp)
goto found;
}
error = EINVAL;
goto done;
found:
#ifdef MAC
(void) vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
error = mac_check_system_swapoff(td->td_ucred, vp);
(void) VOP_UNLOCK(vp, 0, td);
if (error != 0)
goto done;
#endif
nblks = sp->sw_nblks;
/*
* We can turn off this swap device safely only if the
* available virtual memory in the system will fit the amount
* of data we will have to page back in, plus an epsilon so
* the system doesn't become critically low on swap space.
*/
if (cnt.v_free_count + cnt.v_cache_count + vm_swap_size <
nblks + nswap_lowat) {
error = ENOMEM;
goto done;
}
/*
* Prevent further allocations on this device.
*/
sp->sw_flags |= SW_CLOSING;
for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
blk = min(nblks - dvbase, dmmax);
vsbase = index * dmmax + dvbase * nswdev;
vm_swap_size -= blist_fill(swapblist, vsbase, blk);
}
/*
* Page in the contents of the device and close it.
*/
#ifndef NO_SWAPPING
vm_proc_swapin_all(index);
#endif /* !NO_SWAPPING */
swap_pager_swapoff(index, &sp->sw_used);
VOP_CLOSE(vp, FREAD | FWRITE, td->td_ucred, td);
vrele(vp);
sp->sw_vp = NULL;
/*
* Resize the bitmap based on the new largest swap device,
* or free the bitmap if there are no more devices.
*/
for (sp = swdevt, nblks = 0; sp < swdevt + nswdev; sp++) {
if (sp->sw_vp == NULL)
continue;
nblks = max(nblks, sp->sw_nblks);
}
aligned_nblks = (nblks + (dmmax -1)) & ~(u_long)(dmmax -1);
nswap = aligned_nblks * nswdev;
if (nswap == 0) {
blist_destroy(swapblist);
swapblist = NULL;
vrele(swapdev_vp);
swapdev_vp = NULL;
} else
blist_resize(&swapblist, nswap, 0);
done:
swdev_syscall_active = 0;
wakeup_one(&swdev_syscall_active);
done2:
mtx_unlock(&Giant);
return (error);
}
static int
sysctl_vm_swap_info(SYSCTL_HANDLER_ARGS)
{
int *name = (int *)arg1;
int error, i, n;
struct xswdev xs;
struct swdevt *sp;
if (arg2 != 1) /* name length */
return (EINVAL);
for (sp = swdevt, i = 0, n = 0 ; i < nswdev; i++, sp++) {
if (sp->sw_vp) {
if (n == *name) {
xs.xsw_version = XSWDEV_VERSION;
xs.xsw_dev = sp->sw_dev;
xs.xsw_flags = sp->sw_flags;
xs.xsw_nblks = sp->sw_nblks;
xs.xsw_used = sp->sw_used;
error = SYSCTL_OUT(req, &xs, sizeof(xs));
return (error);
}
n++;
}
}
return (ENOENT);
}
SYSCTL_INT(_vm, OID_AUTO, nswapdev, CTLFLAG_RD, &nswdev, 0,
"Number of swap devices");
SYSCTL_NODE(_vm, OID_AUTO, swap_info, CTLFLAG_RD, sysctl_vm_swap_info,
"Swap statistics by device");