1 /* $NetBSD: kern_physio.c,v 1.93 2015/04/21 10:54:52 pooka 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 1.93 2015/04/21 10:54:52 pooka 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 ps = kmem_zalloc(sizeof(*ps), KM_SLEEP); 235 /* ps->ps_running = 0; */ 236 /* ps->ps_error = 0; */ 237 /* ps->ps_failed = 0; */ 238 ps->ps_orig_bp = obp; 239 ps->ps_endoffset = -1; 240 mutex_init(&ps->ps_lock, MUTEX_DEFAULT, IPL_NONE); 241 cv_init(&ps->ps_cv, "physio"); 242 243 /* Make sure we have a buffer, creating one if necessary. */ 244 if (obp != NULL) { 245 mutex_enter(&bufcache_lock); 246 /* Mark it busy, so nobody else will use it. */ 247 while (bbusy(obp, false, 0, NULL) == EPASSTHROUGH) 248 ; 249 mutex_exit(&bufcache_lock); 250 concurrency = 0; /* see "XXXkludge" comment below */ 251 } 252 253 for (i = 0; i < uio->uio_iovcnt; i++) { 254 bool sync = true; 255 256 iovp = &uio->uio_iov[i]; 257 while (iovp->iov_len > 0) { 258 size_t todo; 259 vaddr_t endp; 260 261 mutex_enter(&ps->ps_lock); 262 if (ps->ps_failed != 0) { 263 goto done_locked; 264 } 265 physio_wait(ps, sync ? 0 : concurrency); 266 mutex_exit(&ps->ps_lock); 267 if (obp != NULL) { 268 /* 269 * XXXkludge 270 * some drivers use "obp" as an identifier. 271 */ 272 bp = obp; 273 } else { 274 bp = getiobuf(NULL, true); 275 bp->b_cflags = BC_BUSY; 276 } 277 bp->b_dev = dev; 278 bp->b_proc = p; 279 bp->b_private = ps; 280 281 /* 282 * Mrk the buffer busy for physical I/O. Also set 283 * B_PHYS because it's an I/O to user memory, and 284 * B_RAW because B_RAW is to be "set by physio for 285 * raw transfers". 286 */ 287 bp->b_oflags = 0; 288 bp->b_cflags = BC_BUSY; 289 bp->b_flags = flags | B_PHYS | B_RAW; 290 bp->b_iodone = physio_biodone; 291 292 /* Set up the buffer for a maximum-sized transfer. */ 293 bp->b_blkno = btodb(uio->uio_offset); 294 if (dbtob(bp->b_blkno) != uio->uio_offset) { 295 error = EINVAL; 296 goto done; 297 } 298 bp->b_bcount = MIN(MAXPHYS, iovp->iov_len); 299 bp->b_data = iovp->iov_base; 300 301 /* 302 * Call minphys to bound the transfer size, 303 * and remember the amount of data to transfer, 304 * for later comparison. 305 */ 306 (*min_phys)(bp); 307 todo = bp->b_bufsize = bp->b_bcount; 308 #if defined(DIAGNOSTIC) 309 if (todo > MAXPHYS) 310 panic("todo(%zu) > MAXPHYS; minphys broken", 311 todo); 312 #endif /* defined(DIAGNOSTIC) */ 313 314 sync = false; 315 endp = (vaddr_t)bp->b_data + todo; 316 if (trunc_page(endp) != endp) { 317 /* 318 * Following requests can overlap. 319 * note that uvm_vslock does round_page. 320 */ 321 sync = true; 322 } 323 324 /* 325 * Lock the part of the user address space involved 326 * in the transfer. 327 */ 328 error = uvm_vslock(p->p_vmspace, bp->b_data, todo, 329 (flags & B_READ) ? VM_PROT_WRITE : VM_PROT_READ); 330 if (error) { 331 goto done; 332 } 333 334 /* 335 * Beware vmapbuf(); if succesful it clobbers 336 * b_data and saves it in b_saveaddr. 337 * However, vunmapbuf() restores b_data. 338 */ 339 if ((error = vmapbuf(bp, todo)) != 0) { 340 uvm_vsunlock(p->p_vmspace, bp->b_data, todo); 341 goto done; 342 } 343 344 BIO_SETPRIO(bp, BPRIO_TIMECRITICAL); 345 346 mutex_enter(&ps->ps_lock); 347 ps->ps_running++; 348 mutex_exit(&ps->ps_lock); 349 350 /* Call strategy to start the transfer. */ 351 (*strategy)(bp); 352 bp = NULL; 353 354 iovp->iov_len -= todo; 355 iovp->iov_base = (char *)iovp->iov_base + todo; 356 uio->uio_offset += todo; 357 uio->uio_resid -= todo; 358 } 359 } 360 361 done: 362 mutex_enter(&ps->ps_lock); 363 done_locked: 364 physio_wait(ps, 0); 365 mutex_exit(&ps->ps_lock); 366 367 if (ps->ps_failed != 0) { 368 off_t delta; 369 370 delta = uio->uio_offset - ps->ps_endoffset; 371 KASSERT(delta > 0); 372 uio->uio_resid += delta; 373 /* uio->uio_offset = ps->ps_endoffset; */ 374 } else { 375 KASSERT(ps->ps_endoffset == -1); 376 } 377 if (bp != NULL && bp != obp) { 378 putiobuf(bp); 379 } 380 if (error == 0) { 381 error = ps->ps_error; 382 } 383 mutex_destroy(&ps->ps_lock); 384 cv_destroy(&ps->ps_cv); 385 kmem_free(ps, sizeof(*ps)); 386 387 /* 388 * Clean up the state of the buffer. Remember if somebody wants 389 * it, so we can wake them up below. Also, if we had to steal it, 390 * give it back. 391 */ 392 if (obp != NULL) { 393 KASSERT((obp->b_cflags & BC_BUSY) != 0); 394 395 /* 396 * If another process is waiting for the raw I/O buffer, 397 * wake up processes waiting to do physical I/O; 398 */ 399 mutex_enter(&bufcache_lock); 400 obp->b_cflags &= ~(BC_BUSY | BC_WANTED); 401 obp->b_flags &= ~(B_PHYS | B_RAW); 402 obp->b_iodone = NULL; 403 cv_broadcast(&obp->b_busy); 404 mutex_exit(&bufcache_lock); 405 } 406 407 DPRINTF(("%s: done: off=%" PRIu64 ", resid=%zu\n", 408 __func__, uio->uio_offset, uio->uio_resid)); 409 410 return error; 411 } 412 413 /* 414 * A minphys() routine is called by physio() to adjust the size of each 415 * I/O transfer before the latter is passed to the strategy routine. 416 * 417 * This minphys() is a default that must be called to enforce limits 418 * that are applicable to all devices, because of limitations in the 419 * kernel or the hardware platform. 420 */ 421 void 422 minphys(struct buf *bp) 423 { 424 425 if (bp->b_bcount > MAXPHYS) 426 bp->b_bcount = MAXPHYS; 427 } 428