1 /* 2 * Copyright (c) 1982, 1986, 1989 Regents of the University of California. 3 * All rights reserved. 4 * 5 * %sccs.include.redist.c% 6 * 7 * @(#)vm_swap.c 7.25 (Berkeley) 07/12/92 8 */ 9 10 #include <sys/param.h> 11 #include <sys/systm.h> 12 #include <sys/buf.h> 13 #include <sys/conf.h> 14 #include <sys/proc.h> 15 #include <sys/namei.h> 16 #include <sys/dmap.h> /* XXX */ 17 #include <sys/vnode.h> 18 #include <sys/map.h> 19 #include <sys/file.h> 20 21 #include <miscfs/specfs/specdev.h> 22 23 /* 24 * Indirect driver for multi-controller paging. 25 */ 26 27 int nswap, nswdev; 28 29 /* 30 * Set up swap devices. 31 * Initialize linked list of free swap 32 * headers. These do not actually point 33 * to buffers, but rather to pages that 34 * are being swapped in and out. 35 */ 36 void 37 swapinit() 38 { 39 register int i; 40 register struct buf *sp = swbuf; 41 register struct proc *p = &proc0; /* XXX */ 42 struct swdevt *swp; 43 int error; 44 45 /* 46 * Count swap devices, and adjust total swap space available. 47 * Some of this space will not be available until a swapon() 48 * system is issued, usually when the system goes multi-user. 49 */ 50 nswdev = 0; 51 nswap = 0; 52 for (swp = swdevt; swp->sw_dev; swp++) { 53 nswdev++; 54 if (swp->sw_nblks > nswap) 55 nswap = swp->sw_nblks; 56 } 57 if (nswdev == 0) 58 panic("swapinit"); 59 if (nswdev > 1) 60 nswap = ((nswap + dmmax - 1) / dmmax) * dmmax; 61 nswap *= nswdev; 62 if (bdevvp(swdevt[0].sw_dev, &swdevt[0].sw_vp)) 63 panic("swapvp"); 64 if (error = swfree(p, 0)) { 65 printf("swfree errno %d\n", error); /* XXX */ 66 panic("swapinit swfree 0"); 67 } 68 69 /* 70 * Now set up swap buffer headers. 71 */ 72 bswlist.av_forw = sp; 73 for (i = 0; i < nswbuf - 1; i++, sp++) { 74 sp->av_forw = sp + 1; 75 sp->b_rcred = sp->b_wcred = p->p_ucred; 76 } 77 sp->b_rcred = sp->b_wcred = p->p_ucred; 78 sp->av_forw = NULL; 79 } 80 81 void 82 swstrategy(bp) 83 register struct buf *bp; 84 { 85 int sz, off, seg, index; 86 register struct swdevt *sp; 87 struct vnode *vp; 88 89 #ifdef GENERIC 90 /* 91 * A mini-root gets copied into the front of the swap 92 * and we run over top of the swap area just long 93 * enough for us to do a mkfs and restor of the real 94 * root (sure beats rewriting standalone restor). 95 */ 96 #define MINIROOTSIZE 4096 97 if (rootdev == dumpdev) 98 bp->b_blkno += MINIROOTSIZE; 99 #endif 100 sz = howmany(bp->b_bcount, DEV_BSIZE); 101 if (bp->b_blkno + sz > nswap) { 102 bp->b_flags |= B_ERROR; 103 biodone(bp); 104 return; 105 } 106 if (nswdev > 1) { 107 off = bp->b_blkno % dmmax; 108 if (off+sz > dmmax) { 109 bp->b_flags |= B_ERROR; 110 biodone(bp); 111 return; 112 } 113 seg = bp->b_blkno / dmmax; 114 index = seg % nswdev; 115 seg /= nswdev; 116 bp->b_blkno = seg*dmmax + off; 117 } else 118 index = 0; 119 sp = &swdevt[index]; 120 if ((bp->b_dev = sp->sw_dev) == 0) 121 panic("swstrategy"); 122 if (sp->sw_vp == NULL) { 123 bp->b_error |= B_ERROR; 124 biodone(bp); 125 return; 126 } 127 VHOLD(sp->sw_vp); 128 if ((bp->b_flags & B_READ) == 0) { 129 if (vp = bp->b_vp) { 130 vp->v_numoutput--; 131 if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) { 132 vp->v_flag &= ~VBWAIT; 133 wakeup((caddr_t)&vp->v_numoutput); 134 } 135 } 136 sp->sw_vp->v_numoutput++; 137 } 138 if (bp->b_vp != NULL) 139 brelvp(bp); 140 bp->b_vp = sp->sw_vp; 141 VOP_STRATEGY(bp); 142 } 143 144 /* 145 * System call swapon(name) enables swapping on device name, 146 * which must be in the swdevsw. Return EBUSY 147 * if already swapping on this device. 148 */ 149 struct swapon_args { 150 char *name; 151 }; 152 /* ARGSUSED */ 153 int 154 swapon(p, uap, retval) 155 struct proc *p; 156 struct swapon_args *uap; 157 int *retval; 158 { 159 register struct vnode *vp; 160 register struct swdevt *sp; 161 dev_t dev; 162 int error; 163 struct nameidata nd; 164 165 if (error = suser(p->p_ucred, &p->p_acflag)) 166 return (error); 167 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, p); 168 if (error = namei(&nd)) 169 return (error); 170 vp = nd.ni_vp; 171 if (vp->v_type != VBLK) { 172 vrele(vp); 173 return (ENOTBLK); 174 } 175 dev = (dev_t)vp->v_rdev; 176 if (major(dev) >= nblkdev) { 177 vrele(vp); 178 return (ENXIO); 179 } 180 for (sp = &swdevt[0]; sp->sw_dev; sp++) 181 if (sp->sw_dev == dev) { 182 if (sp->sw_freed) { 183 vrele(vp); 184 return (EBUSY); 185 } 186 sp->sw_vp = vp; 187 if (error = swfree(p, sp - swdevt)) { 188 vrele(vp); 189 return (error); 190 } 191 return (0); 192 } 193 vrele(vp); 194 return (EINVAL); 195 } 196 197 /* 198 * Swfree(index) frees the index'th portion of the swap map. 199 * Each of the nswdev devices provides 1/nswdev'th of the swap 200 * space, which is laid out with blocks of dmmax pages circularly 201 * among the devices. 202 */ 203 int 204 swfree(p, index) 205 struct proc *p; 206 int index; 207 { 208 register struct swdevt *sp; 209 register swblk_t vsbase; 210 register long blk; 211 struct vnode *vp; 212 register swblk_t dvbase; 213 register int nblks; 214 int error; 215 216 sp = &swdevt[index]; 217 vp = sp->sw_vp; 218 if (error = VOP_OPEN(vp, FREAD|FWRITE, p->p_ucred, p)) 219 return (error); 220 sp->sw_freed = 1; 221 nblks = sp->sw_nblks; 222 for (dvbase = 0; dvbase < nblks; dvbase += dmmax) { 223 blk = nblks - dvbase; 224 if ((vsbase = index*dmmax + dvbase*nswdev) >= nswap) 225 panic("swfree"); 226 if (blk > dmmax) 227 blk = dmmax; 228 if (vsbase == 0) { 229 /* 230 * First of all chunks... initialize the swapmap 231 * the second half of the hunk. 232 */ 233 rminit(swapmap, (long)(blk/2), (long)(blk/2), 234 "swap", nswapmap); 235 } else if (dvbase == 0) { 236 /* 237 * Don't use the first cluster of the device 238 * in case it starts with a label or boot block. 239 */ 240 rmfree(swapmap, blk - ctod(CLSIZE), 241 vsbase + ctod(CLSIZE)); 242 } else 243 rmfree(swapmap, blk, vsbase); 244 } 245 return (0); 246 } 247