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/priv.h> 46 #include <sys/nlookup.h> 47 #include <sys/dmap.h> /* XXX */ 48 #include <sys/vnode.h> 49 #include <sys/fcntl.h> 50 #include <sys/blist.h> 51 #include <sys/kernel.h> 52 #include <sys/lock.h> 53 #include <sys/conf.h> 54 #include <sys/stat.h> 55 #include <sys/thread2.h> 56 #include <vm/vm.h> 57 #include <vm/vm_extern.h> 58 #include <vm/swap_pager.h> 59 #include <vm/vm_zone.h> 60 61 /* 62 * Indirect driver for multi-controller paging. 63 */ 64 65 #ifndef NSWAPDEV 66 #define NSWAPDEV 4 67 #endif 68 static struct swdevt should_be_malloced[NSWAPDEV]; 69 struct swdevt *swdevt = should_be_malloced; /* exported to pstat/systat */ 70 static int nswap; /* first block after the interleaved devs */ 71 int nswdev = NSWAPDEV; /* exported to pstat/systat */ 72 int vm_swap_size; 73 74 static int swapdev_strategy (struct vop_strategy_args *ap); 75 struct vnode *swapdev_vp; 76 77 /* 78 * swapdev_strategy: 79 * 80 * vn_strategy() for swapdev_vp. 81 * Perform swap strategy interleave device selection. 82 * 83 * The bp is expected to be locked and on call. 84 * 85 * (struct vnode *a_vp, struct bio *b_bio) 86 */ 87 88 static int 89 swapdev_strategy(struct vop_strategy_args *ap) 90 { 91 struct bio *bio = ap->a_bio; 92 struct bio *nbio; 93 struct buf *bp = bio->bio_buf; 94 int sz, off, seg, index, blkno, nblkno; 95 struct swdevt *sp; 96 struct vnode *vp; 97 98 vp = ap->a_vp; 99 sz = howmany(bp->b_bcount, PAGE_SIZE); 100 blkno = (int)(bio->bio_offset >> PAGE_SHIFT); 101 102 /* 103 * Convert interleaved swap into per-device swap. Note that 104 * the block size is left in PAGE_SIZE'd chunks (for the newswap) 105 * here. 106 */ 107 nbio = push_bio(bio); 108 if (nswdev > 1) { 109 off = blkno % dmmax; 110 if (off + sz > dmmax) { 111 bp->b_error = EINVAL; 112 bp->b_flags |= B_ERROR; 113 biodone(bio); 114 return 0; 115 } 116 seg = blkno / dmmax; 117 index = seg % nswdev; 118 seg /= nswdev; 119 nbio->bio_offset = (off_t)(seg * dmmax + off) << PAGE_SHIFT; 120 } else { 121 index = 0; 122 nbio->bio_offset = bio->bio_offset; 123 } 124 nblkno = (int)(nbio->bio_offset >> PAGE_SHIFT); 125 sp = &swdevt[index]; 126 if (nblkno + sz > sp->sw_nblks) { 127 bp->b_error = EINVAL; 128 bp->b_flags |= B_ERROR; 129 /* I/O was never started on nbio, must biodone(bio) */ 130 biodone(bio); 131 return 0; 132 } 133 if (sp->sw_vp == NULL) { 134 bp->b_error = ENODEV; 135 bp->b_flags |= B_ERROR; 136 /* I/O was never started on nbio, must biodone(bio) */ 137 biodone(bio); 138 return 0; 139 } 140 141 /* 142 * Issue a strategy call on the appropriate swap vnode. Note that 143 * bp->b_vp is not modified. Strategy code is always supposed to 144 * use the passed vp. 145 * 146 * We have to use vn_strategy() here even if we know we have a 147 * device in order to properly break up requests which exceed the 148 * device's DMA limits. 149 */ 150 vn_strategy(sp->sw_vp, nbio); 151 return 0; 152 } 153 154 /* 155 * Create a special vnode op vector for swapdev_vp - we only use 156 * vn_strategy(), everything else returns an error. 157 */ 158 static struct vop_ops swapdev_vnode_vops = { 159 .vop_default = vop_defaultop, 160 .vop_strategy = swapdev_strategy 161 }; 162 static struct vop_ops *swapdev_vnode_vops_p = &swapdev_vnode_vops; 163 164 VNODEOP_SET(swapdev_vnode_vops); 165 166 /* 167 * swapon_args(char *name) 168 * 169 * System call swapon(name) enables swapping on device name, 170 * which must be in the swdevsw. Return EBUSY 171 * if already swapping on this device. 172 */ 173 /* ARGSUSED */ 174 int 175 sys_swapon(struct swapon_args *uap) 176 { 177 struct thread *td = curthread; 178 struct vattr attr; 179 struct vnode *vp; 180 struct nlookupdata nd; 181 int error; 182 struct ucred *cred; 183 184 KKASSERT(td->td_proc); 185 cred = td->td_proc->p_ucred; 186 187 error = priv_check(td, PRIV_ROOT); 188 if (error) 189 return (error); 190 191 vp = NULL; 192 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW); 193 if (error == 0) 194 error = nlookup(&nd); 195 if (error == 0) 196 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp); 197 nlookup_done(&nd); 198 if (error) 199 return (error); 200 201 if (vn_isdisk(vp, &error)) 202 error = swaponvp(td, vp, 0); 203 else if (vp->v_type == VREG && vp->v_tag == VT_NFS && 204 (error = VOP_GETATTR(vp, &attr)) == 0) { 205 /* 206 * Allow direct swapping to NFS regular files in the same 207 * way that nfs_mountroot() sets up diskless swapping. 208 */ 209 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 210 } 211 212 if (error) 213 vrele(vp); 214 215 return (error); 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 * The new swap code uses page-sized blocks. The old swap code used 225 * DEV_BSIZE'd chunks. 226 * 227 * XXX locking when multiple swapon's run in parallel 228 */ 229 int 230 swaponvp(struct thread *td, struct vnode *vp, u_long nblks) 231 { 232 u_long aligned_nblks; 233 int64_t dpsize; 234 struct ucred *cred; 235 struct swdevt *sp; 236 swblk_t vsbase; 237 swblk_t dvbase; 238 cdev_t dev; 239 int index; 240 int error; 241 long blk; 242 243 KKASSERT(td->td_proc); 244 cred = td->td_proc->p_ucred; 245 246 if (!swapdev_vp) { 247 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p, 248 &swapdev_vp, 0, 0); 249 if (error) 250 panic("Cannot get vnode for swapdev"); 251 swapdev_vp->v_type = VNON; /* Untyped */ 252 vx_unlock(swapdev_vp); 253 } 254 255 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) { 256 if (sp->sw_vp == vp) 257 return EBUSY; 258 if (!sp->sw_vp) 259 goto found; 260 261 } 262 return EINVAL; 263 found: 264 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 265 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL); 266 vn_unlock(vp); 267 if (error) 268 return (error); 269 270 /* 271 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize() 272 * must be supported if a character device has been specified. 273 */ 274 if (vp->v_type == VCHR) 275 dev = vp->v_rdev; 276 else 277 dev = NULL; 278 279 if (nblks == 0 && dev != NULL) { 280 dpsize = dev_dpsize(dev); 281 if (dpsize == -1) { 282 VOP_CLOSE(vp, FREAD | FWRITE); 283 return (ENXIO); 284 } 285 if ((u_int64_t)dpsize < 0x100000000ULL) 286 nblks = (u_long)dpsize; 287 else 288 nblks = 0xffffffffU; 289 } 290 if (nblks == 0) { 291 VOP_CLOSE(vp, FREAD | FWRITE); 292 return (ENXIO); 293 } 294 295 /* 296 * If we go beyond this, we get overflows in the radix 297 * tree bitmap code. 298 */ 299 if (nblks > 0x40000000 / BLIST_META_RADIX / nswdev) { 300 kprintf("exceeded maximum of %d blocks per swap unit\n", 301 0x40000000 / BLIST_META_RADIX / nswdev); 302 VOP_CLOSE(vp, FREAD | FWRITE); 303 return (ENXIO); 304 } 305 /* 306 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 307 * First chop nblks off to page-align it, then convert. 308 * 309 * sw->sw_nblks is in page-sized chunks now too. 310 */ 311 nblks &= ~(ctodb(1) - 1); 312 nblks = dbtoc(nblks); 313 314 sp->sw_vp = vp; 315 sp->sw_dev = dev2udev(dev); 316 sp->sw_device = dev; 317 sp->sw_flags |= SW_FREED; 318 sp->sw_nblks = nblks; 319 320 /* 321 * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not 322 * DEV_BSIZE'd. aligned_nblks is used to calculate the 323 * size of the swap bitmap, taking into account the stripe size. 324 */ 325 aligned_nblks = (nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1); 326 327 if (aligned_nblks * nswdev > nswap) 328 nswap = aligned_nblks * nswdev; 329 330 if (swapblist == NULL) 331 swapblist = blist_create(nswap); 332 else 333 blist_resize(&swapblist, nswap, 0); 334 335 for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) { 336 blk = min(nblks - dvbase, dmmax); 337 vsbase = index * dmmax + dvbase * nswdev; 338 blist_free(swapblist, vsbase, blk); 339 vm_swap_size += blk; 340 } 341 swap_pager_newswap(); 342 343 return (0); 344 } 345