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 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 #include <sys/thread2.h> 62 #include <sys/mplock2.h> 63 64 /* 65 * Indirect driver for multi-controller paging. 66 */ 67 68 #ifndef NSWAPDEV 69 #define NSWAPDEV 4 70 #endif 71 static struct swdevt should_be_malloced[NSWAPDEV]; 72 struct swdevt *swdevt = should_be_malloced; /* exported to pstat/systat */ 73 static swblk_t nswap; /* first block after the interleaved devs */ 74 int nswdev = NSWAPDEV; /* exported to pstat/systat */ 75 int vm_swap_size; 76 int vm_swap_max; 77 78 static int swapdev_strategy (struct vop_strategy_args *ap); 79 struct vnode *swapdev_vp; 80 81 /* 82 * swapdev_strategy: 83 * 84 * vn_strategy() for swapdev_vp. 85 * Perform swap strategy interleave device selection. 86 * 87 * The bp is expected to be locked and on call. 88 * 89 * (struct vnode *a_vp, struct bio *b_bio) 90 */ 91 92 static int 93 swapdev_strategy(struct vop_strategy_args *ap) 94 { 95 struct bio *bio = ap->a_bio; 96 struct bio *nbio; 97 struct buf *bp = bio->bio_buf; 98 int sz, off, seg, index, blkno, nblkno; 99 struct swdevt *sp; 100 struct vnode *vp; 101 102 vp = ap->a_vp; 103 sz = howmany(bp->b_bcount, PAGE_SIZE); 104 blkno = (int)(bio->bio_offset >> PAGE_SHIFT); 105 106 /* 107 * Convert interleaved swap into per-device swap. Note that 108 * the block size is left in PAGE_SIZE'd chunks (for the newswap) 109 * here. 110 */ 111 nbio = push_bio(bio); 112 if (nswdev > 1) { 113 off = blkno % dmmax; 114 if (off + sz > dmmax) { 115 bp->b_error = EINVAL; 116 bp->b_flags |= B_ERROR; 117 biodone(bio); 118 return 0; 119 } 120 seg = blkno / dmmax; 121 index = seg % nswdev; 122 seg /= nswdev; 123 nbio->bio_offset = (off_t)(seg * dmmax + off) << PAGE_SHIFT; 124 } else { 125 index = 0; 126 nbio->bio_offset = bio->bio_offset; 127 } 128 nblkno = (int)(nbio->bio_offset >> PAGE_SHIFT); 129 sp = &swdevt[index]; 130 if (nblkno + sz > sp->sw_nblks) { 131 bp->b_error = EINVAL; 132 bp->b_flags |= B_ERROR; 133 /* I/O was never started on nbio, must biodone(bio) */ 134 biodone(bio); 135 return 0; 136 } 137 if (sp->sw_vp == NULL) { 138 bp->b_error = ENODEV; 139 bp->b_flags |= B_ERROR; 140 /* I/O was never started on nbio, must biodone(bio) */ 141 biodone(bio); 142 return 0; 143 } 144 145 /* 146 * Issue a strategy call on the appropriate swap vnode. Note that 147 * bp->b_vp is not modified. Strategy code is always supposed to 148 * use the passed vp. 149 * 150 * We have to use vn_strategy() here even if we know we have a 151 * device in order to properly break up requests which exceed the 152 * device's DMA limits. 153 */ 154 vn_strategy(sp->sw_vp, nbio); 155 return 0; 156 } 157 158 /* 159 * Create a special vnode op vector for swapdev_vp - we only use 160 * vn_strategy(), everything else returns an error. 161 */ 162 static struct vop_ops swapdev_vnode_vops = { 163 .vop_default = vop_defaultop, 164 .vop_strategy = swapdev_strategy 165 }; 166 static struct vop_ops *swapdev_vnode_vops_p = &swapdev_vnode_vops; 167 168 VNODEOP_SET(swapdev_vnode_vops); 169 170 /* 171 * swapon_args(char *name) 172 * 173 * System call swapon(name) enables swapping on device name, 174 * which must be in the swdevsw. Return EBUSY 175 * if already swapping on this device. 176 * 177 * MPALMOSTSAFE 178 */ 179 int 180 sys_swapon(struct swapon_args *uap) 181 { 182 struct thread *td = curthread; 183 struct vattr attr; 184 struct vnode *vp; 185 struct nlookupdata nd; 186 int error; 187 struct ucred *cred; 188 189 cred = td->td_ucred; 190 191 error = priv_check(td, PRIV_ROOT); 192 if (error) 193 return (error); 194 195 get_mplock(); 196 vp = NULL; 197 error = nlookup_init(&nd, uap->name, UIO_USERSPACE, NLC_FOLLOW); 198 if (error == 0) 199 error = nlookup(&nd); 200 if (error == 0) 201 error = cache_vref(&nd.nl_nch, nd.nl_cred, &vp); 202 nlookup_done(&nd); 203 if (error) { 204 rel_mplock(); 205 return (error); 206 } 207 208 if (vn_isdisk(vp, &error)) { 209 error = swaponvp(td, vp, 0); 210 } else if (vp->v_type == VREG && vp->v_tag == VT_NFS && 211 (error = VOP_GETATTR(vp, &attr)) == 0) { 212 /* 213 * Allow direct swapping to NFS regular files in the same 214 * way that nfs_mountroot() sets up diskless swapping. 215 */ 216 error = swaponvp(td, vp, attr.va_size / DEV_BSIZE); 217 } 218 if (error) 219 vrele(vp); 220 rel_mplock(); 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 * The new swap code uses page-sized blocks. The old swap code used 232 * DEV_BSIZE'd chunks. 233 * 234 * XXX locking when multiple swapon's run in parallel 235 */ 236 int 237 swaponvp(struct thread *td, struct vnode *vp, u_quad_t nblks) 238 { 239 swblk_t aligned_nblks; 240 int64_t dpsize; 241 struct ucred *cred; 242 struct swdevt *sp; 243 swblk_t vsbase; 244 swblk_t dvbase; 245 cdev_t dev; 246 int index; 247 int error; 248 long blk; 249 250 cred = td->td_ucred; 251 252 if (!swapdev_vp) { 253 error = getspecialvnode(VT_NON, NULL, &swapdev_vnode_vops_p, 254 &swapdev_vp, 0, 0); 255 if (error) 256 panic("Cannot get vnode for swapdev"); 257 swapdev_vp->v_type = VNON; /* Untyped */ 258 vx_unlock(swapdev_vp); 259 } 260 261 for (sp = swdevt, index = 0 ; index < nswdev; index++, sp++) { 262 if (sp->sw_vp == vp) 263 return EBUSY; 264 if (!sp->sw_vp) 265 goto found; 266 267 } 268 return EINVAL; 269 found: 270 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 271 error = VOP_OPEN(vp, FREAD | FWRITE, cred, NULL); 272 vn_unlock(vp); 273 if (error) 274 return (error); 275 276 /* 277 * v_rdev is not valid until after the VOP_OPEN() call. dev_psize() 278 * must be supported if a character device has been specified. 279 */ 280 if (vp->v_type == VCHR) 281 dev = vp->v_rdev; 282 else 283 dev = NULL; 284 285 if (nblks == 0 && dev != NULL) { 286 dpsize = dev_dpsize(dev); 287 if (dpsize == -1) { 288 VOP_CLOSE(vp, FREAD | FWRITE); 289 return (ENXIO); 290 } 291 nblks = (u_quad_t)dpsize; 292 } 293 if (nblks == 0) { 294 VOP_CLOSE(vp, FREAD | FWRITE); 295 return (ENXIO); 296 } 297 298 /* 299 * nblks is in DEV_BSIZE'd chunks, convert to PAGE_SIZE'd chunks. 300 * First chop nblks off to page-align it, then convert. 301 * 302 * sw->sw_nblks is in page-sized chunks now too. 303 */ 304 nblks &= ~(u_quad_t)(ctodb(1) - 1); 305 nblks = dbtoc(nblks); 306 307 /* 308 * Post-conversion nblks must not be >= BLIST_MAXBLKS, and 309 * we impose a 4-swap-device limit so we have to divide it out 310 * further. Going beyond this will result in overflows in the 311 * blist code. 312 * 313 * Post-conversion nblks must fit within a (swblk_t), which 314 * this test also ensures. 315 */ 316 if (nblks > BLIST_MAXBLKS / nswdev) { 317 kprintf("exceeded maximum of %d blocks per swap unit\n", 318 (int)BLIST_MAXBLKS / nswdev); 319 VOP_CLOSE(vp, FREAD | FWRITE); 320 return (ENXIO); 321 } 322 323 sp->sw_vp = vp; 324 sp->sw_dev = dev2udev(dev); 325 sp->sw_device = dev; 326 sp->sw_flags |= SW_FREED; 327 sp->sw_nblks = (swblk_t)nblks; 328 329 /* 330 * nblks, nswap, and dmmax are PAGE_SIZE'd parameters now, not 331 * DEV_BSIZE'd. aligned_nblks is used to calculate the 332 * size of the swap bitmap, taking into account the stripe size. 333 */ 334 aligned_nblks = (swblk_t)((nblks + (dmmax - 1)) & ~(u_long)(dmmax - 1)); 335 336 if (aligned_nblks * nswdev > nswap) 337 nswap = aligned_nblks * nswdev; 338 339 if (swapblist == NULL) 340 swapblist = blist_create(nswap); 341 else 342 blist_resize(&swapblist, nswap, 0); 343 344 for (dvbase = dmmax; dvbase < nblks; dvbase += dmmax) { 345 blk = min(nblks - dvbase, dmmax); 346 vsbase = index * dmmax + dvbase * nswdev; 347 blist_free(swapblist, vsbase, blk); 348 vm_swap_size += blk; 349 vm_swap_max += blk; 350 } 351 swap_pager_newswap(); 352 353 return (0); 354 } 355