8af2296bcb
with davidg about it, I hereby kill two undocumented misfeatures: The code to skip a miniroot in the swapdev is not particular useful, and if we need it we need it to be done properly, ie size the fs and skip all of it not some hardcoded size, and subtract what we skip from the length in the first place. The SEQSWAP dies too. It's not the way to do it, it doesn't work, and nobody have expressed any great desire for it to work. The way to implement it correctly would be a second argument to swapon(2) to give a priority/policy information. Low priority swapdevs can be made so by adding them at a far offset (0x80000000 kind of thing), with almost no modification to the strategy routine (in particular a offset per swapdev). But until the need is obvious, it will not be done.
300 lines
7.6 KiB
C
300 lines
7.6 KiB
C
/*
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* Copyright (c) 1982, 1986, 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)vm_swap.c 8.5 (Berkeley) 2/17/94
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* $Id: vm_swap.c,v 1.15 1995/03/16 18:17:33 bde Exp $
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/buf.h>
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#include <sys/conf.h>
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#include <sys/proc.h>
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#include <sys/namei.h>
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#include <sys/dmap.h> /* XXX */
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#include <sys/vnode.h>
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#include <sys/file.h>
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#include <sys/rlist.h>
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#include <vm/vm.h>
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#include <miscfs/specfs/specdev.h>
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/*
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* Indirect driver for multi-controller paging.
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*/
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int nswap, nswdev;
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int vm_swap_size;
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int bswneeded;
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vm_offset_t swapbkva; /* swap buffers kva */
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/*
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* Set up swap devices.
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* Initialize linked list of free swap
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* headers. These do not actually point
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* to buffers, but rather to pages that
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* are being swapped in and out.
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*/
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void
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swapinit()
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{
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register struct proc *p = &proc0; /* XXX */
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struct swdevt *swp;
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int error;
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/*
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* Count swap devices, and adjust total swap space available. Some of
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* the space will not be countable until later (dynamically
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* configurable devices) and some of the counted space will not be
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* available until a swapon() system call is issued, both usually
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* happen when the system goes multi-user.
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*
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* If using NFS for swap, swdevt[0] will already be bdevvp'd. XXX
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*/
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nswdev = 0;
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nswap = 0;
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for (swp = swdevt; swp->sw_dev != NODEV || swp->sw_vp != NULL; swp++) {
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nswdev++;
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if (swp->sw_nblks > nswap)
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nswap = swp->sw_nblks;
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}
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if (nswdev == 0)
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panic("swapinit");
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if (nswdev > 1)
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nswap = ((nswap + dmmax - 1) / dmmax) * dmmax;
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nswap *= nswdev;
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if (swdevt[0].sw_vp == NULL &&
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bdevvp(swdevt[0].sw_dev, &swdevt[0].sw_vp))
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panic("swapvp");
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/*
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* If there is no swap configured, tell the user. We don't
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* automatically activate any swapspaces in the kernel; the user must
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* explicitly use swapon to enable swaping on a device.
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*/
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if (nswap == 0)
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printf("WARNING: no swap space found\n");
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for (swp = swdevt;; swp++) {
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if (swp->sw_dev == NODEV) {
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if (swp->sw_vp == NULL)
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break;
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/* We DO enable NFS swapspaces */
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error = swfree(p, swp - swdevt);
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if (error) {
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printf(
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"Couldn't enable swapspace %d, error = %d",
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swp - swdevt, error);
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}
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}
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}
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}
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void
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swstrategy(bp)
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register struct buf *bp;
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{
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int sz, off, seg, index;
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register struct swdevt *sp;
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struct vnode *vp;
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sz = howmany(bp->b_bcount, DEV_BSIZE);
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if (bp->b_blkno + sz > nswap) {
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bp->b_error = EINVAL;
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bp->b_flags |= B_ERROR;
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biodone(bp);
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return;
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}
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if (nswdev > 1) {
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off = bp->b_blkno % dmmax;
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if (off + sz > dmmax) {
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bp->b_error = EINVAL;
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bp->b_flags |= B_ERROR;
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biodone(bp);
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return;
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}
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seg = bp->b_blkno / dmmax;
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index = seg % nswdev;
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seg /= nswdev;
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bp->b_blkno = seg * dmmax + off;
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} else
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index = 0;
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sp = &swdevt[index];
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if ((bp->b_dev = sp->sw_dev) == NODEV)
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panic("swstrategy");
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if (sp->sw_vp == NULL) {
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bp->b_error = ENODEV;
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bp->b_flags |= B_ERROR;
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biodone(bp);
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return;
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}
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VHOLD(sp->sw_vp);
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if ((bp->b_flags & B_READ) == 0) {
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vp = bp->b_vp;
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if (vp) {
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vp->v_numoutput--;
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if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
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vp->v_flag &= ~VBWAIT;
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wakeup((caddr_t) &vp->v_numoutput);
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}
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}
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sp->sw_vp->v_numoutput++;
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}
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if (bp->b_vp != NULL)
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pbrelvp(bp);
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bp->b_vp = sp->sw_vp;
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VOP_STRATEGY(bp);
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}
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/*
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* System call swapon(name) enables swapping on device name,
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* which must be in the swdevsw. Return EBUSY
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* if already swapping on this device.
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*/
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struct swapon_args {
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char *name;
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};
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/* ARGSUSED */
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int
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swapon(p, uap, retval)
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struct proc *p;
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struct swapon_args *uap;
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int *retval;
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{
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register struct vnode *vp;
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register struct swdevt *sp;
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dev_t dev;
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int error;
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struct nameidata nd;
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error = suser(p->p_ucred, &p->p_acflag);
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if (error)
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return (error);
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NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, p);
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error = namei(&nd);
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if (error)
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return (error);
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vp = nd.ni_vp;
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if (vp->v_type != VBLK) {
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vrele(vp);
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return (ENOTBLK);
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}
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dev = (dev_t) vp->v_rdev;
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if (major(dev) >= nblkdev) {
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vrele(vp);
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return (ENXIO);
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}
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for (sp = &swdevt[0]; sp->sw_dev != NODEV; sp++) {
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if (sp->sw_dev == dev) {
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if (sp->sw_flags & SW_FREED) {
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vrele(vp);
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return (EBUSY);
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}
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sp->sw_vp = vp;
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error = swfree(p, sp - swdevt);
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if (error) {
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vrele(vp);
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return (error);
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}
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return (0);
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}
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}
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vrele(vp);
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return (EINVAL);
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}
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/*
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* Swfree(index) frees the index'th portion of the swap map.
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* Each of the nswdev devices provides 1/nswdev'th of the swap
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* space, which is laid out with blocks of dmmax pages circularly
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* among the devices.
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*/
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int
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swfree(p, index)
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struct proc *p;
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int index;
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{
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register struct swdevt *sp;
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register swblk_t vsbase;
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register long blk;
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struct vnode *vp;
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register swblk_t dvbase;
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register int nblks;
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int error;
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sp = &swdevt[index];
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vp = sp->sw_vp;
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error = VOP_OPEN(vp, FREAD | FWRITE, p->p_ucred, p);
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if (error)
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return (error);
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sp->sw_flags |= SW_FREED;
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nblks = sp->sw_nblks;
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/*
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* Some devices may not exist til after boot time. If so, their nblk
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* count will be 0.
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*/
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if (nblks <= 0) {
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int perdev;
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dev_t dev = sp->sw_dev;
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if (bdevsw[major(dev)].d_psize == 0 ||
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(nblks = (*bdevsw[major(dev)].d_psize) (dev)) == -1) {
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(void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
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sp->sw_flags &= ~SW_FREED;
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return (ENXIO);
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}
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perdev = nswap / nswdev;
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if (nblks > perdev)
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nblks = perdev;
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sp->sw_nblks = nblks;
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}
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if (nblks == 0) {
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(void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p);
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sp->sw_flags &= ~SW_FREED;
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return (0); /* XXX error? */
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}
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for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
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blk = nblks - dvbase;
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if ((vsbase = index * dmmax + dvbase * nswdev) >= nswap)
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panic("swfree");
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if (blk > dmmax)
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blk = dmmax;
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/* XXX -- we need to exclude the first cluster as above */
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/* but for now, this will work fine... */
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rlist_free(&swaplist, vsbase, vsbase + blk - 1);
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vm_swap_size += blk;
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}
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return (0);
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}
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