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Annotation of 43BSDReno/sys/kern/vm_sw.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 is only permitted until one year after the first shipment
        !             6:  * of 4.4BSD by the Regents.  Otherwise, redistribution and use in source and
        !             7:  * binary forms are permitted provided that: (1) source distributions retain
        !             8:  * this entire copyright notice and comment, and (2) distributions including
        !             9:  * binaries display the following acknowledgement:  This product includes
        !            10:  * software developed by the University of California, Berkeley and its
        !            11:  * contributors'' in the documentation or other materials provided with the
        !            12:  * distribution and in all advertising materials mentioning features or use
        !            13:  * of this software.  Neither the name of the University nor the names of
        !            14:  * its contributors may be used to endorse or promote products derived from
        !            15:  * this software without specific prior written permission.
        !            16:  * THIS SOFTWARE IS PROVIDED AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
        !            17:  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
        !            18:  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
        !            19:  *
        !            20:  *     @(#)vm_sw.c     7.14 (Berkeley) 6/28/90
        !            21:  */
        !            22: 
        !            23: #include "param.h"
        !            24: #include "systm.h"
        !            25: #include "buf.h"
        !            26: #include "conf.h"
        !            27: #include "user.h"
        !            28: #include "vnode.h"
        !            29: #include "specdev.h"
        !            30: #include "map.h"
        !            31: #include "file.h"
        !            32: 
        !            33: /*
        !            34:  * Indirect driver for multi-controller paging.
        !            35:  */
        !            36: swstrategy(bp)
        !            37:        register struct buf *bp;
        !            38: {
        !            39:        int sz, off, seg, index;
        !            40:        register struct swdevt *sp;
        !            41:        struct vnode *vp;
        !            42: 
        !            43: #ifdef GENERIC
        !            44:        /*
        !            45:         * A mini-root gets copied into the front of the swap
        !            46:         * and we run over top of the swap area just long
        !            47:         * enough for us to do a mkfs and restor of the real
        !            48:         * root (sure beats rewriting standalone restor).
        !            49:         */
        !            50: #define        MINIROOTSIZE    4096
        !            51:        if (rootdev == dumpdev)
        !            52:                bp->b_blkno += MINIROOTSIZE;
        !            53: #endif
        !            54:        sz = howmany(bp->b_bcount, DEV_BSIZE);
        !            55:        if (bp->b_blkno+sz > nswap) {
        !            56:                bp->b_flags |= B_ERROR;
        !            57:                biodone(bp);
        !            58:                return;
        !            59:        }
        !            60:        if (nswdev > 1) {
        !            61:                off = bp->b_blkno % dmmax;
        !            62:                if (off+sz > dmmax) {
        !            63:                        bp->b_flags |= B_ERROR;
        !            64:                        biodone(bp);
        !            65:                        return;
        !            66:                }
        !            67:                seg = bp->b_blkno / dmmax;
        !            68:                index = seg % nswdev;
        !            69:                seg /= nswdev;
        !            70:                bp->b_blkno = seg*dmmax + off;
        !            71:        } else
        !            72:                index = 0;
        !            73:        sp = &swdevt[index];
        !            74:        if ((bp->b_dev = sp->sw_dev) == 0)
        !            75:                panic("swstrategy");
        !            76:        if (sp->sw_vp == NULL) {
        !            77:                bp->b_error |= B_ERROR;
        !            78:                biodone(bp);
        !            79:                return;
        !            80:        }
        !            81:        VHOLD(sp->sw_vp);
        !            82:        if ((bp->b_flags & B_READ) == 0) {
        !            83:                if (vp = bp->b_vp) {
        !            84:                        vp->v_numoutput--;
        !            85:                        if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) {
        !            86:                                vp->v_flag &= ~VBWAIT;
        !            87:                                wakeup((caddr_t)&vp->v_numoutput);
        !            88:                        }
        !            89:                }
        !            90:                sp->sw_vp->v_numoutput++;
        !            91:        }
        !            92:        if (bp->b_vp != NULL)
        !            93:                brelvp(bp);
        !            94:        bp->b_vp = sp->sw_vp;
        !            95:        VOP_STRATEGY(bp);
        !            96: }
        !            97: 
        !            98: /*
        !            99:  * System call swapon(name) enables swapping on device name,
        !           100:  * which must be in the swdevsw.  Return EBUSY
        !           101:  * if already swapping on this device.
        !           102:  */
        !           103: /* ARGSUSED */
        !           104: swapon(p, uap, retval)
        !           105:        struct proc *p;
        !           106:        struct args {
        !           107:                char    *name;
        !           108:        } *uap;
        !           109:        int *retval;
        !           110: {
        !           111:        register struct vnode *vp;
        !           112:        register struct swdevt *sp;
        !           113:        register struct nameidata *ndp = &u.u_nd;
        !           114:        dev_t dev;
        !           115:        int error;
        !           116: 
        !           117:        if (error = suser(u.u_cred, &u.u_acflag))
        !           118:                return (error);
        !           119:        ndp->ni_nameiop = LOOKUP | FOLLOW;
        !           120:        ndp->ni_segflg = UIO_USERSPACE;
        !           121:        ndp->ni_dirp = uap->name;
        !           122:        if (error = namei(ndp))
        !           123:                return (error);
        !           124:        vp = ndp->ni_vp;
        !           125:        if (vp->v_type != VBLK) {
        !           126:                vrele(vp);
        !           127:                return (ENOTBLK);
        !           128:        }
        !           129:        dev = (dev_t)vp->v_rdev;
        !           130:        if (major(dev) >= nblkdev) {
        !           131:                vrele(vp);
        !           132:                return (ENXIO);
        !           133:        }
        !           134:        for (sp = &swdevt[0]; sp->sw_dev; sp++)
        !           135:                if (sp->sw_dev == dev) {
        !           136:                        if (sp->sw_freed) {
        !           137:                                vrele(vp);
        !           138:                                return (EBUSY);
        !           139:                        }
        !           140:                        sp->sw_vp = vp;
        !           141:                        if (error = swfree(sp - swdevt)) {
        !           142:                                vrele(vp);
        !           143:                                return (error);
        !           144:                        }
        !           145:                        return (0);
        !           146:                }
        !           147:        vrele(vp);
        !           148:        return (EINVAL);
        !           149: }
        !           150: 
        !           151: /*
        !           152:  * Swfree(index) frees the index'th portion of the swap map.
        !           153:  * Each of the nswdev devices provides 1/nswdev'th of the swap
        !           154:  * space, which is laid out with blocks of dmmax pages circularly
        !           155:  * among the devices.
        !           156:  */
        !           157: swfree(index)
        !           158:        int index;
        !           159: {
        !           160:        register struct swdevt *sp;
        !           161:        register swblk_t vsbase;
        !           162:        register long blk;
        !           163:        struct vnode *vp;
        !           164:        register swblk_t dvbase;
        !           165:        register int nblks;
        !           166:        int error;
        !           167: 
        !           168:        sp = &swdevt[index];
        !           169:        vp = sp->sw_vp;
        !           170:        if (error = VOP_OPEN(vp, FREAD|FWRITE, u.u_cred))
        !           171:                return (error);
        !           172:        sp->sw_freed = 1;
        !           173:        nblks = sp->sw_nblks;
        !           174:        for (dvbase = 0; dvbase < nblks; dvbase += dmmax) {
        !           175:                blk = nblks - dvbase;
        !           176:                if ((vsbase = index*dmmax + dvbase*nswdev) >= nswap)
        !           177:                        panic("swfree");
        !           178:                if (blk > dmmax)
        !           179:                        blk = dmmax;
        !           180:                if (vsbase == 0) {
        !           181:                        /*
        !           182:                         * Can't free a block starting at 0 in the swapmap
        !           183:                         * but need some space for argmap so use 1/2 this
        !           184:                         * hunk which needs special treatment anyways.
        !           185:                         */
        !           186:                        argdev = sp->sw_dev;
        !           187:                        if (argdev_vp)
        !           188:                                vrele(argdev_vp);
        !           189:                        VREF(vp);
        !           190:                        argdev_vp = vp;
        !           191:                        rminit(argmap, (long)(blk/2-ctod(CLSIZE)),
        !           192:                            (long)ctod(CLSIZE), "argmap", ARGMAPSIZE);
        !           193:                        /*
        !           194:                         * First of all chunks... initialize the swapmap
        !           195:                         * the second half of the hunk.
        !           196:                         */
        !           197:                        rminit(swapmap, (long)(blk/2), (long)(blk/2),
        !           198:                            "swap", nswapmap);
        !           199:                } else if (dvbase == 0) {
        !           200:                        /*
        !           201:                         * Don't use the first cluster of the device
        !           202:                         * in case it starts with a label or boot block.
        !           203:                         */
        !           204:                        rmfree(swapmap, blk - ctod(CLSIZE),
        !           205:                            vsbase + ctod(CLSIZE));
        !           206:                } else
        !           207:                        rmfree(swapmap, blk, vsbase);
        !           208:        }
        !           209:        return (0);
        !           210: }

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