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Annotation of Net2/vm/vm_swap.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1982, 1986, 1989 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms, with or without
        !             6:  * modification, are permitted provided that the following conditions
        !             7:  * are met:
        !             8:  * 1. Redistributions of source code must retain the above copyright
        !             9:  *    notice, this list of conditions and the following disclaimer.
        !            10:  * 2. Redistributions in binary form must reproduce the above copyright
        !            11:  *    notice, this list of conditions and the following disclaimer in the
        !            12:  *    documentation and/or other materials provided with the distribution.
        !            13:  * 3. All advertising materials mentioning features or use of this software
        !            14:  *    must display the following acknowledgement:
        !            15:  *     This product includes software developed by the University of
        !            16:  *     California, Berkeley and its contributors.
        !            17:  * 4. Neither the name of the University nor the names of its contributors
        !            18:  *    may be used to endorse or promote products derived from this software
        !            19:  *    without specific prior written permission.
        !            20:  *
        !            21:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
        !            22:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
        !            23:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
        !            24:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
        !            25:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
        !            26:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
        !            27:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
        !            28:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
        !            29:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
        !            30:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
        !            31:  * SUCH DAMAGE.
        !            32:  *
        !            33:  *     @(#)vm_swap.c   7.18 (Berkeley) 5/6/91
        !            34:  */
        !            35: 
        !            36: #include "param.h"
        !            37: #include "systm.h"
        !            38: #include "buf.h"
        !            39: #include "conf.h"
        !            40: #include "proc.h"
        !            41: #include "namei.h"
        !            42: #include "dmap.h"              /* XXX */
        !            43: #include "vnode.h"
        !            44: #include "specdev.h"
        !            45: #include "map.h"
        !            46: #include "file.h"
        !            47: 
        !            48: /*
        !            49:  * Indirect driver for multi-controller paging.
        !            50:  */
        !            51: 
        !            52: int    nswap, nswdev;
        !            53: 
        !            54: /*
        !            55:  * Set up swap devices.
        !            56:  * Initialize linked list of free swap
        !            57:  * headers. These do not actually point
        !            58:  * to buffers, but rather to pages that
        !            59:  * are being swapped in and out.
        !            60:  */
        !            61: swapinit()
        !            62: {
        !            63:        register int i;
        !            64:        register struct buf *sp = swbuf;
        !            65:        struct swdevt *swp;
        !            66:        int error;
        !            67: 
        !            68:        /*
        !            69:         * Count swap devices, and adjust total swap space available.
        !            70:         * Some of this space will not be available until a swapon()
        !            71:         * system is issued, usually when the system goes multi-user.
        !            72:         */
        !            73:        nswdev = 0;
        !            74:        nswap = 0;
        !            75:        for (swp = swdevt; swp->sw_dev; swp++) {
        !            76:                nswdev++;
        !            77:                if (swp->sw_nblks > nswap)
        !            78:                        nswap = swp->sw_nblks;
        !            79:        }
        !            80:        if (nswdev == 0)
        !            81:                panic("swapinit");
        !            82:        if (nswdev > 1)
        !            83:                nswap = ((nswap + dmmax - 1) / dmmax) * dmmax;
        !            84:        nswap *= nswdev;
        !            85:        if (bdevvp(swdevt[0].sw_dev, &swdevt[0].sw_vp))
        !            86:                panic("swapvp");
        !            87:        if (error = swfree(&proc0, 0)) {
        !            88:                printf("swfree errno %d\n", error);     /* XXX */
        !            89:                panic("swapinit swfree 0");
        !            90:        }
        !            91: 
        !            92:        /*
        !            93:         * Now set up swap buffer headers.
        !            94:         */
        !            95:        bswlist.av_forw = sp;
        !            96:        for (i = 0; i < nswbuf - 1; i++, sp++)
        !            97:                sp->av_forw = sp + 1;
        !            98:        sp->av_forw = NULL;
        !            99: }
        !           100: 
        !           101: swstrategy(bp)
        !           102:        register struct buf *bp;
        !           103: {
        !           104:        int sz, off, seg, index;
        !           105:        register struct swdevt *sp;
        !           106:        struct vnode *vp;
        !           107: 
        !           108: #ifdef GENERIC
        !           109:        /*
        !           110:         * A mini-root gets copied into the front of the swap
        !           111:         * and we run over top of the swap area just long
        !           112:         * enough for us to do a mkfs and restor of the real
        !           113:         * root (sure beats rewriting standalone restor).
        !           114:         */
        !           115: #define        MINIROOTSIZE    4096
        !           116:        if (rootdev == dumpdev)
        !           117:                bp->b_blkno += MINIROOTSIZE;
        !           118: #endif
        !           119:        sz = howmany(bp->b_bcount, DEV_BSIZE);
        !           120:        if (bp->b_blkno + sz > nswap) {
        !           121:                bp->b_flags |= B_ERROR;
        !           122:                biodone(bp);
        !           123:                return;
        !           124:        }
        !           125:        if (nswdev > 1) {
        !           126:                off = bp->b_blkno % dmmax;
        !           127:                if (off+sz > dmmax) {
        !           128:                        bp->b_flags |= B_ERROR;
        !           129:                        biodone(bp);
        !           130:                        return;
        !           131:                }
        !           132:                seg = bp->b_blkno / dmmax;
        !           133:                index = seg % nswdev;
        !           134:                seg /= nswdev;
        !           135:                bp->b_blkno = seg*dmmax + off;
        !           136:        } else
        !           137:                index = 0;
        !           138:        sp = &swdevt[index];
        !           139:        if ((bp->b_dev = sp->sw_dev) == 0)
        !           140:                panic("swstrategy");
        !           141:        if (sp->sw_vp == NULL) {
        !           142:                bp->b_error |= B_ERROR;
        !           143:                biodone(bp);
        !           144:                return;
        !           145:        }
        !           146:        VHOLD(sp->sw_vp);
        !           147:        if ((bp->b_flags & B_READ) == 0) {
        !           148:                if (vp = bp->b_vp) {
        !           149:                        vp->v_numoutput--;
        !           150:                        if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
        !           151:                                vp->v_flag &= ~VBWAIT;
        !           152:                                wakeup((caddr_t)&vp->v_numoutput);
        !           153:                        }
        !           154:                }
        !           155:                sp->sw_vp->v_numoutput++;
        !           156:        }
        !           157:        if (bp->b_vp != NULL)
        !           158:                brelvp(bp);
        !           159:        bp->b_vp = sp->sw_vp;
        !           160:        VOP_STRATEGY(bp);
        !           161: }
        !           162: 
        !           163: /*
        !           164:  * System call swapon(name) enables swapping on device name,
        !           165:  * which must be in the swdevsw.  Return EBUSY
        !           166:  * if already swapping on this device.
        !           167:  */
        !           168: /* ARGSUSED */
        !           169: swapon(p, uap, retval)
        !           170:        struct proc *p;
        !           171:        struct args {
        !           172:                char    *name;
        !           173:        } *uap;
        !           174:        int *retval;
        !           175: {
        !           176:        register struct vnode *vp;
        !           177:        register struct swdevt *sp;
        !           178:        register struct nameidata *ndp;
        !           179:        dev_t dev;
        !           180:        int error;
        !           181:        struct nameidata nd;
        !           182: 
        !           183:        if (error = suser(p->p_ucred, &p->p_acflag))
        !           184:                return (error);
        !           185:        ndp = &nd;
        !           186:        ndp->ni_nameiop = LOOKUP | FOLLOW;
        !           187:        ndp->ni_segflg = UIO_USERSPACE;
        !           188:        ndp->ni_dirp = uap->name;
        !           189:        if (error = namei(ndp, p))
        !           190:                return (error);
        !           191:        vp = ndp->ni_vp;
        !           192:        if (vp->v_type != VBLK) {
        !           193:                vrele(vp);
        !           194:                return (ENOTBLK);
        !           195:        }
        !           196:        dev = (dev_t)vp->v_rdev;
        !           197:        if (major(dev) >= nblkdev) {
        !           198:                vrele(vp);
        !           199:                return (ENXIO);
        !           200:        }
        !           201:        for (sp = &swdevt[0]; sp->sw_dev; sp++)
        !           202:                if (sp->sw_dev == dev) {
        !           203:                        if (sp->sw_freed) {
        !           204:                                vrele(vp);
        !           205:                                return (EBUSY);
        !           206:                        }
        !           207:                        sp->sw_vp = vp;
        !           208:                        if (error = swfree(p, sp - swdevt)) {
        !           209:                                vrele(vp);
        !           210:                                return (error);
        !           211:                        }
        !           212:                        return (0);
        !           213:                }
        !           214:        vrele(vp);
        !           215:        return (EINVAL);
        !           216: }
        !           217: 
        !           218: /*
        !           219:  * Swfree(index) frees the index'th portion of the swap map.
        !           220:  * Each of the nswdev devices provides 1/nswdev'th of the swap
        !           221:  * space, which is laid out with blocks of dmmax pages circularly
        !           222:  * among the devices.
        !           223:  */
        !           224: swfree(p, index)
        !           225:        struct proc *p;
        !           226:        int index;
        !           227: {
        !           228:        register struct swdevt *sp;
        !           229:        register swblk_t vsbase;
        !           230:        register long blk;
        !           231:        struct vnode *vp;
        !           232:        register swblk_t dvbase;
        !           233:        register int nblks;
        !           234:        int error;
        !           235: 
        !           236:        sp = &swdevt[index];
        !           237:        vp = sp->sw_vp;
        !           238:        if (error = VOP_OPEN(vp, FREAD|FWRITE, p->p_ucred, p))
        !           239:                return (error);
        !           240:        sp->sw_freed = 1;
        !           241:        nblks = sp->sw_nblks;
        !           242:        for (dvbase = 0; dvbase < nblks; dvbase += dmmax) {
        !           243:                blk = nblks - dvbase;
        !           244:                if ((vsbase = index*dmmax + dvbase*nswdev) >= nswap)
        !           245:                        panic("swfree");
        !           246:                if (blk > dmmax)
        !           247:                        blk = dmmax;
        !           248:                if (vsbase == 0) {
        !           249:                        /*
        !           250:                         * First of all chunks... initialize the swapmap
        !           251:                         * the second half of the hunk.
        !           252:                         */
        !           253:                        rminit(swapmap, (long)(blk/2), (long)(blk/2),
        !           254:                            "swap", nswapmap);
        !           255:                } else if (dvbase == 0) {
        !           256:                        /*
        !           257:                         * Don't use the first cluster of the device
        !           258:                         * in case it starts with a label or boot block.
        !           259:                         */
        !           260:                        rmfree(swapmap, blk - ctod(CLSIZE),
        !           261:                            vsbase + ctod(CLSIZE));
        !           262:                } else
        !           263:                        rmfree(swapmap, blk, vsbase);
        !           264:        }
        !           265:        return (0);
        !           266: }

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