| 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 | |