sys/vm/vm_swap.c

   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 1.96.2.2 2001/10/14 18:46:47 iedowse Exp $
  35  * $DragonFly: src/sys/vm/vm_swap.c,v 1.36 2007/07/20 17:21:54 dillon Exp $
  36  */
  37
  38 #include "opt_swap.h"
  39
  40 #include <sys/param.h>
  41 #include <sys/systm.h>
  42 #include <sys/sysproto.h>
  43 #include <sys/buf.h>
  44 #include <sys/proc.h>
  45 #include <sys/nlookup.h>
  46 #include <sys/dmap.h>           /* XXX */
  47 #include <sys/vnode.h>
  48 #include <sys/fcntl.h>
  49 #include <sys/blist.h>
  50 #include <sys/kernel.h>
  51 #include <sys/lock.h>
  52 #include <sys/conf.h>
  53 #include <sys/stat.h>
  54 #include <sys/thread2.h>
  55 #include <vm/vm.h>
  56 #include <vm/vm_extern.h>
  57 #include <vm/swap_pager.h>
  58 #include <vm/vm_zone.h>
  59
  60 /*
  61  * Indirect driver for multi-controller paging.
  62  */
  63
  64 #ifndef NSWAPDEV
  65 #define NSWAPDEV        4
  66 #endif
  67 static struct swdevt should_be_malloced[NSWAPDEV];
  68 struct swdevt *swdevt = should_be_malloced;     /* exported to pstat/systat */
  69 static int nswap;               /* first block after the interleaved devs */
  70 int nswdev = NSWAPDEV;                          /* exported to pstat/systat */
  71 int vm_swap_size;
  72
  73 static int swapdev_strategy (struct vop_strategy_args *ap);
  74 struct vnode *swapdev_vp;
  75
  76 /*
  77  *      swapdev_strategy:
  78  *
  79  *      vn_strategy() for swapdev_vp.
  80  *      Perform swap strategy interleave device selection.
  81  *
  82  *      The bp is expected to be locked and on call.
  83  *
  84  *      (struct vnode *a_vp, struct bio *b_bio)
  85  */
  86
  87 static int
  88 swapdev_strategy(struct vop_strategy_args *ap)
  89 {
  90         struct bio *bio = ap->a_bio;
  91         struct bio *nbio;
  92         struct buf *bp = bio->bio_buf;
  93         int sz, off, seg, index, blkno, nblkno;
  94         struct swdevt *sp;
  95         struct vnode *vp;
  96
  97         vp = ap->a_vp;
  98         sz = howmany(bp->b_bcount, PAGE_SIZE);
  99         blkno = (int)(bio->bio_offset >> PAGE_SHIFT);
 100
 101         /*
 102          * Convert interleaved swap into per-device swap.  Note that
 103          * the block size is left in PAGE_SIZE'd chunks (for the newswap)
 104          * here.
 105          */
 106         nbio = push_bio(bio);
 107         if (nswdev > 1) {
 108                 off = blkno % dmmax;
 109                 if (off + sz > dmmax) {
 110                         bp->b_error = EINVAL;
 111                         bp->b_flags |= B_ERROR;
 112                         biodone(bio);
 113                         return 0;
 114                 }
 115                 seg = blkno / dmmax;
 116                 index = seg % nswdev;
 117                 seg /= nswdev;
 118                 nbio->bio_offset = (off_t)(seg * dmmax + off) << PAGE_SHIFT;
 119         } else {
 120                 index = 0;
 121                 nbio->bio_offset = bio->bio_offset;
 122         }
 123         nblkno = (int)(nbio->bio_offset >> PAGE_SHIFT);
 124         sp = &swdevt[index];
 125         if (nblkno + sz > sp->sw_nblks) {
 126                 bp->b_error = EINVAL;
 127                 bp->b_flags |= B_ERROR;
 128                 /* I/O was never started on nbio, must biodone(bio) */
 129                 biodone(bio);
 130                 return 0;
 131         }
 132         if (sp->sw_vp == NULL) {
 133                 bp->b_error = ENODEV;
 134                 bp->b_flags |= B_ERROR;
 135                 /* I/O was never started on nbio, must biodone(bio) */
 136                 biodone(bio);
 137                 return 0;
 138         }
 139
 140         /*
 141          * Issue a strategy call on the appropriate swap vnode.  Note that
 142          * bp->b_vp is not modified.  Strategy code is always supposed to
 143          * use the passed vp.
 144          *
 145          * We have to use vn_strategy() here even if we know we have a
 146          * device in order to properly break up requests which exceed the
 147          * device's DMA limits.
 148          */
 149         vn_strategy(sp->sw_vp, nbio);
 150         return 0;
 151 }
 152
 153 /*
 154  * Create a special vnode op vector for swapdev_vp - we only use
 155  * vn_strategy(), everything else returns an error.
 156  */
 157 static struct vop_ops swapdev_vnode_vops = {
 158         .vop_default =          vop_defaultop,
 159         .vop_strategy =         swapdev_strategy
 160 };
 161 static struct vop_ops *swapdev_vnode_vops_p = &swapdev_vnode_vops;
 162
 163 VNODEOP_SET(swapdev_vnode_vops);
 164
 165 /*
 166  * swapon_args(char *name)
 167  *
 168  * System call swapon(name) enables swapping on device name,
 169  * which must be in the swdevsw.  Return EBUSY
 170  * if already swapping on this device.
 171  */
 172 /* ARGSUSED */
 173 int
 174 sys_swapon(struct swapon_args *uap)
 175 {
 176         struct thread *td = curthread;
 177         struct vattr attr;
 178         struct vnode *vp;
 179         struct nlookupdata nd;
 180         int error;
 181         struct ucred *cred;
 182
 183         KKASSERT(td->td_proc);
 184         cred = td->td_proc->p_ucred;
 185
 186         error = suser(td);
 187         if (error)
 188                 return (error);
 189
 190         vp = NULL;
 191         error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW);
 192         if (error == 0)
 193                 error = nlookup(&nd);
 194         if (error == 0)
 195                 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp);
 196         nlookup_done(&nd);
 197         if (error)
 198                 return (error);
 199
 200         if (vn_isdisk(vp, &error))
 201                 error = swaponvp(td, vp, 0);
 202         else if (vp->v_type == VREG && vp->v_tag == VT_NFS &&
 203             (error = VOP_GETATTR(vp, &attr)) == 0) {
 204                 /*
 205                  * Allow direct swapping to NFS regular files in the same
 206                  * way that nfs_mountroot() sets up diskless swapping.
 207                  */
 208                 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE);
 209         }
 210
 211         if (error)
 212                 vrele(vp);
 213
 214         return (error);
 215 }
 216
 217 /*
 218  * Swfree(index) frees the index'th portion of the swap map.
 219  * Each of the nswdev devices provides 1/nswdev'th of the swap
 220  * space, which is laid out with blocks of dmmax pages circularly
 221  * among the devices.
 222  *
 223  * The new swap code uses page-sized blocks.  The old swap code used
 224  * DEV_BSIZE'd chunks.
 225  *
 226  * XXX locking when multiple swapon's run in parallel
 227  */
 228 int
 229 swaponvp(struct thread *td, struct vnode *vp, u_long nblks)
 230 {
 231         u_long aligned_nblks;
 232         int64_t dpsize;
 233         struct ucred *cred;
 234         struct swdevt *sp;
 235         swblk_t vsbase;
 236         swblk_t dvbase;
 237         cdev_t dev;
 238         int index;
 239         int error;
 240         long blk;
 241
 242         KKASSERT(td->td_proc);
 243         cred = td->td_proc->p_ucred;
 244
 245         if (!swapdev_vp) {
 246                 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p,
 247                                     &swapdev_vp, 0, 0);
 248                 if (error)
 249                         panic("Cannot get vnode for swapdev");
 250                 swapdev_vp->v_type = VNON;      /* Untyped */
 251                 vx_unlock(swapdev_vp);
 252         }
 253
 254         for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) {
 255                 if (sp->sw_vp == vp)
 256                         return EBUSY;
 257                 if (!sp->sw_vp)
 258                         goto found;
 259
 260         }
 261         return EINVAL;
 262     found:
 263         vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
 264         error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL);
 265         vn_unlock(vp);
 266         if (error)
 267                 return (error);
 268
 269         /*
 270          * v_rdev is not valid until after the VOP_OPEN() call.  dev_psize()
 271          * must be supported if a character device has been specified.
 272          */
 273         if (vp->v_type == VCHR)
 274                 dev = vp->v_rdev;
 275         else
 276                 dev = NULL;
 277
 278         if (nblks == 0 && dev != NULL) {
 279                 dpsize = dev_dpsize(dev);
 280                 if (dpsize == -1) {
 281                         VOP_CLOSE(vp, FREAD | FWRITE);
 282                         return (ENXIO);
 283                 }
 284                 if ((u_int64_t)dpsize < 0x100000000ULL)
 285                         nblks = (u_long)dpsize;
 286                 else
 287                         nblks = 0xffffffffU;
 288         }
 289         if (nblks == 0) {
 290                 VOP_CLOSE(vp, FREAD | FWRITE);
 291                 return (ENXIO);
 292         }
 293
 294         /*
 295          * If we go beyond this, we get overflows in the radix
 296          * tree bitmap code.
 297          */
 298         if (nblks > 0x40000000 / BLIST_META_RADIX / nswdev) {
 299                 kprintf("exceeded maximum of %d blocks per swap unit\n",
 300                         0x40000000 / BLIST_META_RADIX / nswdev);
 301                 VOP_CLOSE(vp, FREAD | FWRITE);
 302                 return (ENXIO);
 303         }
 304         /*
 305          * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks.
 306          * First chop nblks off to page-align it, then convert.
 307          *
 308          * sw->sw_nblks is in page-sized chunks now too.
 309          */
 310         nblks &= ~(ctodb(1) - 1);
 311         nblks = dbtoc(nblks);
 312
 313         sp->sw_vp = vp;
 314         sp->sw_dev = dev2udev(dev);
 315         sp->sw_device = dev;
 316         sp->sw_flags |= SW_FREED;
 317         sp->sw_nblks = nblks;
 318
 319         /*
 320          * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not
 321          * DEV_BSIZE'd.   aligned_nblks is used to calculate the
 322          * size of the swap bitmap, taking into account the stripe size.
 323          */
 324         aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1);
 325
 326         if (aligned_nblks * nswdev > nswap)
 327                 nswap = aligned_nblks * nswdev;
 328
 329         if (swapblist == NULL)
 330                 swapblist = blist_create(nswap);
 331         else
 332                 blist_resize(&swapblist, nswap, 0);
 333
 334         for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) {
 335                 blk = min(nblks - dvbase, dmmax);
 336                 vsbase = index * dmmax + dvbase * nswdev;
 337                 blist_free(swapblist, vsbase, blk);
 338                 vm_swap_size += blk;
 339         }
 340
 341         return (0);
 342 }