1 /* $NetBSD: kern_physio.c,v 1.91 2009/05/26 14:59:31 hannken Exp $ */ 2 3 /*- 4 * Copyright (c) 1982, 1986, 1990, 1993 5 * The Regents of the University of California. All rights reserved. 6 * (c) UNIX System Laboratories, Inc. 7 * All or some portions of this file are derived from material licensed 8 * to the University of California by American Telephone and Telegraph 9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 10 * the permission of UNIX System Laboratories, Inc. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)kern_physio.c 8.1 (Berkeley) 6/10/93 37 */ 38 39 /*- 40 * Copyright (c) 1994 Christopher G. Demetriou 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. All advertising materials mentioning features or use of this software 51 * must display the following acknowledgement: 52 * This product includes software developed by the University of 53 * California, Berkeley and its contributors. 54 * 4. Neither the name of the University nor the names of its contributors 55 * may be used to endorse or promote products derived from this software 56 * without specific prior written permission. 57 * 58 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 59 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 61 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 62 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 63 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 68 * SUCH DAMAGE. 69 * 70 * @(#)kern_physio.c 8.1 (Berkeley) 6/10/93 71 */ 72 73 #include <sys/cdefs.h> 74 __KERNEL_RCSID(0, "$NetBSD: kern_physio.c,v 1.91 2009/05/26 14:59:31 hannken Exp $"); 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/buf.h> 79 #include <sys/proc.h> 80 #include <sys/once.h> 81 #include <sys/workqueue.h> 82 #include <sys/kmem.h> 83 84 #include <uvm/uvm_extern.h> 85 86 ONCE_DECL(physio_initialized); 87 struct workqueue *physio_workqueue; 88 89 int physio_concurrency = 16; 90 91 /* #define PHYSIO_DEBUG */ 92 #if defined(PHYSIO_DEBUG) 93 #define DPRINTF(a) printf a 94 #else /* defined(PHYSIO_DEBUG) */ 95 #define DPRINTF(a) /* nothing */ 96 #endif /* defined(PHYSIO_DEBUG) */ 97 98 struct physio_stat { 99 int ps_running; 100 int ps_error; 101 int ps_failed; 102 off_t ps_endoffset; 103 buf_t *ps_orig_bp; 104 kmutex_t ps_lock; 105 kcondvar_t ps_cv; 106 }; 107 108 static void 109 physio_done(struct work *wk, void *dummy) 110 { 111 struct buf *bp = (void *)wk; 112 size_t todo = bp->b_bufsize; 113 size_t done = bp->b_bcount - bp->b_resid; 114 struct physio_stat *ps = bp->b_private; 115 bool is_iobuf; 116 117 KASSERT(&bp->b_work == wk); 118 KASSERT(bp->b_bcount <= todo); 119 KASSERT(bp->b_resid <= bp->b_bcount); 120 KASSERT((bp->b_flags & B_PHYS) != 0); 121 KASSERT(dummy == NULL); 122 123 vunmapbuf(bp, todo); 124 uvm_vsunlock(bp->b_proc->p_vmspace, bp->b_data, todo); 125 126 mutex_enter(&ps->ps_lock); 127 is_iobuf = (bp != ps->ps_orig_bp); 128 if (__predict_false(done != todo)) { 129 off_t endoffset = dbtob(bp->b_blkno) + done; 130 131 /* 132 * we got an error or hit EOM. 133 * 134 * we only care about the first one. 135 * ie. the one at the lowest offset. 136 */ 137 138 KASSERT(ps->ps_endoffset != endoffset); 139 DPRINTF(("%s: error=%d at %" PRIu64 " - %" PRIu64 140 ", blkno=%" PRIu64 ", bcount=%d, flags=0x%x\n", 141 __func__, bp->b_error, dbtob(bp->b_blkno), endoffset, 142 bp->b_blkno, bp->b_bcount, bp->b_flags)); 143 144 if (ps->ps_endoffset == -1 || endoffset < ps->ps_endoffset) { 145 DPRINTF(("%s: ps=%p, error %d -> %d, endoff %" PRIu64 146 " -> %" PRIu64 "\n", 147 __func__, ps, 148 ps->ps_error, bp->b_error, 149 ps->ps_endoffset, endoffset)); 150 151 ps->ps_endoffset = endoffset; 152 ps->ps_error = bp->b_error; 153 } 154 ps->ps_failed++; 155 } else { 156 KASSERT(bp->b_error == 0); 157 } 158 159 ps->ps_running--; 160 cv_signal(&ps->ps_cv); 161 mutex_exit(&ps->ps_lock); 162 163 if (is_iobuf) 164 putiobuf(bp); 165 } 166 167 static void 168 physio_biodone(struct buf *bp) 169 { 170 #if defined(DIAGNOSTIC) 171 struct physio_stat *ps = bp->b_private; 172 size_t todo = bp->b_bufsize; 173 size_t done = bp->b_bcount - bp->b_resid; 174 175 KASSERT(ps->ps_running > 0); 176 KASSERT(bp->b_bcount <= todo); 177 KASSERT(bp->b_resid <= bp->b_bcount); 178 if (done == todo) 179 KASSERT(bp->b_error == 0); 180 #endif /* defined(DIAGNOSTIC) */ 181 182 workqueue_enqueue(physio_workqueue, &bp->b_work, NULL); 183 } 184 185 static void 186 physio_wait(struct physio_stat *ps, int n) 187 { 188 189 KASSERT(mutex_owned(&ps->ps_lock)); 190 191 while (ps->ps_running > n) 192 cv_wait(&ps->ps_cv, &ps->ps_lock); 193 } 194 195 static int 196 physio_init(void) 197 { 198 int error; 199 200 KASSERT(physio_workqueue == NULL); 201 202 error = workqueue_create(&physio_workqueue, "physiod", 203 physio_done, NULL, PRI_BIO, IPL_BIO, WQ_MPSAFE); 204 205 return error; 206 } 207 208 /* 209 * Do "physical I/O" on behalf of a user. "Physical I/O" is I/O directly 210 * from the raw device to user buffers, and bypasses the buffer cache. 211 */ 212 int 213 physio(void (*strategy)(struct buf *), struct buf *obp, dev_t dev, int flags, 214 void (*min_phys)(struct buf *), struct uio *uio) 215 { 216 struct iovec *iovp; 217 struct lwp *l = curlwp; 218 struct proc *p = l->l_proc; 219 int i, error; 220 struct buf *bp = NULL; 221 struct physio_stat *ps; 222 int concurrency = physio_concurrency - 1; 223 224 error = RUN_ONCE(&physio_initialized, physio_init); 225 if (__predict_false(error != 0)) { 226 return error; 227 } 228 229 DPRINTF(("%s: called: off=%" PRIu64 ", resid=%zu\n", 230 __func__, uio->uio_offset, uio->uio_resid)); 231 232 flags &= B_READ | B_WRITE; 233 234 if ((ps = kmem_zalloc(sizeof(*ps), KM_SLEEP)) == NULL) 235 return ENOMEM; 236 /* ps->ps_running = 0; */ 237 /* ps->ps_error = 0; */ 238 /* ps->ps_failed = 0; */ 239 ps->ps_orig_bp = obp; 240 ps->ps_endoffset = -1; 241 mutex_init(&ps->ps_lock, MUTEX_DEFAULT, IPL_NONE); 242 cv_init(&ps->ps_cv, "physio"); 243 244 /* Make sure we have a buffer, creating one if necessary. */ 245 if (obp != NULL) { 246 mutex_enter(&bufcache_lock); 247 /* Mark it busy, so nobody else will use it. */ 248 while (bbusy(obp, false, 0, NULL) == EPASSTHROUGH) 249 ; 250 mutex_exit(&bufcache_lock); 251 concurrency = 0; /* see "XXXkludge" comment below */ 252 } 253 254 for (i = 0; i < uio->uio_iovcnt; i++) { 255 bool sync = true; 256 257 iovp = &uio->uio_iov[i]; 258 while (iovp->iov_len > 0) { 259 size_t todo; 260 vaddr_t endp; 261 262 mutex_enter(&ps->ps_lock); 263 if (ps->ps_failed != 0) { 264 goto done_locked; 265 } 266 physio_wait(ps, sync ? 0 : concurrency); 267 mutex_exit(&ps->ps_lock); 268 if (obp != NULL) { 269 /* 270 * XXXkludge 271 * some drivers use "obp" as an identifier. 272 */ 273 bp = obp; 274 } else { 275 bp = getiobuf(NULL, true); 276 bp->b_cflags = BC_BUSY; 277 } 278 bp->b_dev = dev; 279 bp->b_proc = p; 280 bp->b_private = ps; 281 282 /* 283 * Mrk the buffer busy for physical I/O. Also set 284 * B_PHYS because it's an I/O to user memory, and 285 * B_RAW because B_RAW is to be "set by physio for 286 * raw transfers". 287 */ 288 bp->b_oflags = 0; 289 bp->b_cflags = BC_BUSY; 290 bp->b_flags = flags | B_PHYS | B_RAW; 291 bp->b_iodone = physio_biodone; 292 293 /* Set up the buffer for a maximum-sized transfer. */ 294 bp->b_blkno = btodb(uio->uio_offset); 295 if (dbtob(bp->b_blkno) != uio->uio_offset) { 296 error = EINVAL; 297 goto done; 298 } 299 bp->b_bcount = MIN(MAXPHYS, iovp->iov_len); 300 bp->b_data = iovp->iov_base; 301 302 /* 303 * Call minphys to bound the transfer size, 304 * and remember the amount of data to transfer, 305 * for later comparison. 306 */ 307 (*min_phys)(bp); 308 todo = bp->b_bufsize = bp->b_bcount; 309 #if defined(DIAGNOSTIC) 310 if (todo > MAXPHYS) 311 panic("todo(%zu) > MAXPHYS; minphys broken", 312 todo); 313 #endif /* defined(DIAGNOSTIC) */ 314 315 sync = false; 316 endp = (vaddr_t)bp->b_data + todo; 317 if (trunc_page(endp) != endp) { 318 /* 319 * Following requests can overlap. 320 * note that uvm_vslock does round_page. 321 */ 322 sync = true; 323 } 324 325 /* 326 * Lock the part of the user address space involved 327 * in the transfer. Beware vmapbuf(); it clobbers 328 * b_data and saves it in b_saveaddr. However, 329 * vunmapbuf() restores it. 330 */ 331 error = uvm_vslock(p->p_vmspace, bp->b_data, todo, 332 (flags & B_READ) ? VM_PROT_WRITE : VM_PROT_READ); 333 if (error) { 334 goto done; 335 } 336 vmapbuf(bp, todo); 337 338 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 339 340 mutex_enter(&ps->ps_lock); 341 ps->ps_running++; 342 mutex_exit(&ps->ps_lock); 343 344 /* Call strategy to start the transfer. */ 345 (*strategy)(bp); 346 bp = NULL; 347 348 iovp->iov_len -= todo; 349 iovp->iov_base = (char *)iovp->iov_base + todo; 350 uio->uio_offset += todo; 351 uio->uio_resid -= todo; 352 } 353 } 354 355 done: 356 mutex_enter(&ps->ps_lock); 357 done_locked: 358 physio_wait(ps, 0); 359 mutex_exit(&ps->ps_lock); 360 361 if (ps->ps_failed != 0) { 362 off_t delta; 363 364 delta = uio->uio_offset - ps->ps_endoffset; 365 KASSERT(delta > 0); 366 uio->uio_resid += delta; 367 /* uio->uio_offset = ps->ps_endoffset; */ 368 } else { 369 KASSERT(ps->ps_endoffset == -1); 370 } 371 if (bp != NULL && bp != obp) { 372 putiobuf(bp); 373 } 374 if (error == 0) { 375 error = ps->ps_error; 376 } 377 mutex_destroy(&ps->ps_lock); 378 cv_destroy(&ps->ps_cv); 379 kmem_free(ps, sizeof(*ps)); 380 381 /* 382 * Clean up the state of the buffer. Remember if somebody wants 383 * it, so we can wake them up below. Also, if we had to steal it, 384 * give it back. 385 */ 386 if (obp != NULL) { 387 KASSERT((obp->b_cflags & BC_BUSY) != 0); 388 389 /* 390 * If another process is waiting for the raw I/O buffer, 391 * wake up processes waiting to do physical I/O; 392 */ 393 mutex_enter(&bufcache_lock); 394 obp->b_cflags &= ~(BC_BUSY | BC_WANTED); 395 obp->b_flags &= ~(B_PHYS | B_RAW); 396 obp->b_iodone = NULL; 397 cv_broadcast(&obp->b_busy); 398 mutex_exit(&bufcache_lock); 399 } 400 401 DPRINTF(("%s: done: off=%" PRIu64 ", resid=%zu\n", 402 __func__, uio->uio_offset, uio->uio_resid)); 403 404 return error; 405 } 406 407 /* 408 * A minphys() routine is called by physio() to adjust the size of each 409 * I/O transfer before the latter is passed to the strategy routine. 410 * 411 * This minphys() is a default that must be called to enforce limits 412 * that are applicable to all devices, because of limitations in the 413 * kernel or the hardware platform. 414 */ 415 void 416 minphys(struct buf *bp) 417 { 418 419 if (bp->b_bcount > MAXPHYS) 420 bp->b_bcount = MAXPHYS; 421 } 422