Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_swap.c
Version:
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1 /* 2 * Copyright (c) 1982, 1986, 1989, 1993 3 * The Regents of the University of California. 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 8.5 (Berkeley) 2/17/94 34 * $FreeBSD: src/sys/vm/vm_swap.c,v 1.40.2.2 1999/09/05 08:24:41 peter Exp $ 35 */ 36 37 #include <sys/param.h> 38 #include <sys/systm.h> 39 #include <sys/sysproto.h> 40 #include <sys/buf.h> 41 #include <sys/conf.h> 42 #ifdef DEVFS 43 #include <sys/devfsext.h> 44 #endif 45 #include <sys/proc.h> 46 #include <sys/namei.h> 47 #include <sys/dmap.h> /* XXX */ 48 #include <sys/vnode.h> 49 #include <sys/file.h> 50 #include <sys/rlist.h> 51 #include <sys/kernel.h> 52 #include <vm/vm.h> 53 #include <vm/vm_param.h> 54 #include <vm/vm_extern.h> 55 #include <vm/swap_pager.h> 56 57 #include <miscfs/specfs/specdev.h> 58 59 static void swstrategy __P((struct buf *)); 60 61 #define CDEV_MAJOR 4 62 #define BDEV_MAJOR 26 63 extern struct cdevsw sw_cdevsw ; 64 65 static struct bdevsw sw_bdevsw = 66 { noopen, noclose, swstrategy, noioc, /*1*/ 67 nodump, nopsize, 0, "sw", &sw_cdevsw, -1 }; 68 69 static struct cdevsw sw_cdevsw = 70 { nullopen, nullclose, rawread, rawwrite, /*4*/ 71 noioc, nostop, noreset, nodevtotty,/* swap */ 72 noselect, nommap, swstrategy, "sw", 73 &sw_bdevsw, -1 }; 74 75 76 /* 77 * Swapdev is a fake device implemented 78 * in sw.c used only internally to get to swstrategy. 79 * It cannot be provided to the users, because the 80 * swstrategy routine munches the b_dev and b_blkno entries 81 * before calling the appropriate driver. This would horribly 82 * confuse, e.g. the hashing routines. Instead, /dev/drum is 83 * provided as a character (raw) device. 84 */ 85 dev_t swapdev = makedev(BDEV_MAJOR, 0); 86 87 /* 88 * Indirect driver for multi-controller paging. 89 */ 90 91 #ifndef NSWAPDEV 92 #define NSWAPDEV 4 93 #endif 94 static struct swdevt should_be_malloced[NSWAPDEV]; 95 static struct swdevt *swdevt = should_be_malloced; 96 struct vnode *swapdev_vp; 97 /* XXX swapinfo(8) needs this one I belive */ 98 int nswap; /* first block after the interleaved devs */ 99 static int nswdev = NSWAPDEV; 100 int vm_swap_size; 101 102 static void 103 swstrategy(bp) 104 register struct buf *bp; 105 { 106 int sz, off, seg, index; 107 register struct swdevt *sp; 108 struct vnode *vp; 109 110 sz = howmany(bp->b_bcount, DEV_BSIZE); 111 if (nswdev > 1) { 112 off = bp->b_blkno % dmmax; 113 if (off + sz > dmmax) { 114 bp->b_error = EINVAL; 115 bp->b_flags |= B_ERROR; 116 biodone(bp); 117 return; 118 } 119 seg = bp->b_blkno / dmmax; 120 index = seg % nswdev; 121 seg /= nswdev; 122 bp->b_blkno = seg * dmmax + off; 123 } else 124 index = 0; 125 sp = &swdevt[index]; 126 if (bp->b_blkno + sz > sp->sw_nblks) { 127 bp->b_error = EINVAL; 128 bp->b_flags |= B_ERROR; 129 biodone(bp); 130 return; 131 } 132 bp->b_dev = sp->sw_dev; 133 if (sp->sw_vp == NULL) { 134 bp->b_error = ENODEV; 135 bp->b_flags |= B_ERROR; 136 biodone(bp); 137 return; 138 } 139 VHOLD(sp->sw_vp); 140 if ((bp->b_flags & B_READ) == 0) { 141 vp = bp->b_vp; 142 if (vp) { 143 vp->v_numoutput--; 144 if ((vp->v_flag & VBWAIT) && vp->v_numoutput <= 0) { 145 vp->v_flag &= ~VBWAIT; 146 wakeup(&vp->v_numoutput); 147 } 148 } 149 sp->sw_vp->v_numoutput++; 150 } 151 if (bp->b_vp != NULL) 152 pbrelvp(bp); 153 bp->b_vp = sp->sw_vp; 154 VOP_STRATEGY(bp); 155 } 156 157 /* 158 * System call swapon(name) enables swapping on device name, 159 * which must be in the swdevsw. Return EBUSY 160 * if already swapping on this device. 161 */ 162 #ifndef _SYS_SYSPROTO_H_ 163 struct swapon_args { 164 char *name; 165 }; 166 #endif 167 168 /* ARGSUSED */ 169 int 170 swapon(p, uap, retval) 171 struct proc *p; 172 struct swapon_args *uap; 173 int *retval; 174 { 175 register struct vnode *vp; 176 dev_t dev; 177 struct nameidata nd; 178 int error; 179 180 error = suser(p->p_ucred, &p->p_acflag); 181 if (error) 182 return (error); 183 184 NDINIT(&nd, LOOKUP, FOLLOW, UIO_USERSPACE, uap->name, p); 185 error = namei(&nd); 186 if (error) 187 return (error); 188 189 vp = nd.ni_vp; 190 191 switch (vp->v_type) { 192 case VBLK: 193 dev = (dev_t) vp->v_rdev; 194 if (major(dev) >= nblkdev) { 195 error = ENXIO; 196 break; 197 } 198 error = swaponvp(p, vp, dev, 0); 199 break; 200 case VCHR: 201 /* 202 * For now, we disallow swapping to regular files. 203 * It requires logical->physcal block translation 204 * support in the swap pager before it will work. 205 */ 206 error = ENOTBLK; 207 break; 208 #if 0 209 error = VOP_GETATTR(vp, &attr, p->p_ucred, p); 210 if (!error) 211 error = swaponvp(p, vp, NODEV, attr.va_size / DEV_BSIZE); 212 break; 213 #endif 214 default: 215 error = EINVAL; 216 break; 217 } 218 219 if (error) 220 vrele(vp); 221 222 return (error); 223 } 224 225 /* 226 * Swfree(index) frees the index'th portion of the swap map. 227 * Each of the nswdev devices provides 1/nswdev'th of the swap 228 * space, which is laid out with blocks of dmmax pages circularly 229 * among the devices. 230 */ 231 int 232 swaponvp(p, vp, dev, nblks) 233 struct proc *p; 234 struct vnode *vp; 235 dev_t dev; 236 u_long nblks; 237 { 238 int index; 239 register struct swdevt *sp; 240 register swblk_t vsbase; 241 register long blk; 242 swblk_t dvbase; 243 int error; 244 245 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) { 246 if (sp->sw_vp == vp) 247 return EBUSY; 248 if (!sp->sw_vp) 249 goto found; 250 251 } 252 return EINVAL; 253 found: 254 if (dev != NODEV && (major(dev) >= nblkdev)) 255 return (ENXIO); 256 257 error = VOP_OPEN(vp, FREAD | FWRITE, p->p_ucred, p); 258 if (error) 259 return (error); 260 261 if (nblks == 0 && (bdevsw[major(dev)]->d_psize == 0 || 262 (nblks = (*bdevsw[major(dev)]->d_psize) (dev)) == -1)) { 263 (void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p); 264 return (ENXIO); 265 } 266 if (nblks == 0) { 267 (void) VOP_CLOSE(vp, FREAD | FWRITE, p->p_ucred, p); 268 return (ENXIO); 269 } 270 sp->sw_vp = vp; 271 sp->sw_dev = dev; 272 sp->sw_flags |= SW_FREED; 273 sp->sw_nblks = nblks; 274 275 if (nblks * nswdev > nswap) 276 nswap = (nblks+1) * nswdev; 277 278 for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) { 279 blk = min(nblks - dvbase,dmmax); 280 vsbase = index * dmmax + dvbase * nswdev; 281 rlist_free(&swaplist, vsbase, vsbase + blk - 1); 282 vm_swap_size += blk; 283 } 284 285 if (!swapdev_vp) { 286 struct vnode *vp; 287 struct vnode *nvp; 288 289 error = getnewvnode(VT_NON, (struct mount *) 0, 290 spec_vnodeop_p, &nvp); 291 if (error) 292 panic("Cannot get vnode for swapdev"); 293 vp = nvp; 294 vp->v_type = VBLK; 295 if ((nvp = checkalias(vp, swapdev, 296 (struct mount *) 0))) { 297 vput(vp); 298 vp = nvp; 299 } 300 swapdev_vp = vp; 301 } 302 return (0); 303 } 304 305 static sw_devsw_installed = 0; 306 #ifdef DEVFS 307 static void *drum_devfs_token; 308 #endif 309 310 static void sw_drvinit(void *unused) 311 { 312 dev_t dev; 313 314 if( ! sw_devsw_installed ) { 315 dev = makedev(CDEV_MAJOR,0); 316 cdevsw_add(&dev,&sw_cdevsw,NULL); 317 dev = makedev(BDEV_MAJOR,0); 318 bdevsw_add(&dev,&sw_bdevsw,NULL); 319 sw_devsw_installed = 1; 320 #ifdef DEVFS 321 drum_devfs_token = devfs_add_devswf(&sw_cdevsw, 0, DV_CHR, 322 UID_ROOT, GID_KMEM, 0640, 323 "drum"); 324 #endif 325 } 326 } 327 328 SYSINIT(swdev,SI_SUB_DRIVERS,SI_ORDER_MIDDLE+CDEV_MAJOR,sw_drvinit,NULL) 329
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