1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * this file contains a new buffer I/O scheme implementing a coherent 30 * VM object and buffer cache scheme. Pains have been taken to make 31 * sure that the performance degradation associated with schemes such 32 * as this is not realized. 33 * 34 * Author: John S. Dyson 35 * Significant help during the development and debugging phases 36 * had been provided by David Greenman, also of the FreeBSD core team. 37 * 38 * see man buf(9) for more info. 39 */ 40 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/bio.h> 47 #include <sys/conf.h> 48 #include <sys/buf.h> 49 #include <sys/devicestat.h> 50 #include <sys/eventhandler.h> 51 #include <sys/fail.h> 52 #include <sys/limits.h> 53 #include <sys/lock.h> 54 #include <sys/malloc.h> 55 #include <sys/mount.h> 56 #include <sys/mutex.h> 57 #include <sys/kernel.h> 58 #include <sys/kthread.h> 59 #include <sys/proc.h> 60 #include <sys/resourcevar.h> 61 #include <sys/rwlock.h> 62 #include <sys/sysctl.h> 63 #include <sys/vmmeter.h> 64 #include <sys/vnode.h> 65 #include <geom/geom.h> 66 #include <vm/vm.h> 67 #include <vm/vm_param.h> 68 #include <vm/vm_kern.h> 69 #include <vm/vm_pageout.h> 70 #include <vm/vm_page.h> 71 #include <vm/vm_object.h> 72 #include <vm/vm_extern.h> 73 #include <vm/vm_map.h> 74 #include "opt_compat.h" 75 #include "opt_directio.h" 76 #include "opt_swap.h" 77 78 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 79 80 struct bio_ops bioops; /* I/O operation notification */ 81 82 struct buf_ops buf_ops_bio = { 83 .bop_name = "buf_ops_bio", 84 .bop_write = bufwrite, 85 .bop_strategy = bufstrategy, 86 .bop_sync = bufsync, 87 .bop_bdflush = bufbdflush, 88 }; 89 90 /* 91 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 92 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 93 */ 94 struct buf *buf; /* buffer header pool */ 95 96 static struct proc *bufdaemonproc; 97 98 static int inmem(struct vnode *vp, daddr_t blkno); 99 static void vm_hold_free_pages(struct buf *bp, int newbsize); 100 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 101 vm_offset_t to); 102 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 103 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 104 vm_page_t m); 105 static void vfs_drain_busy_pages(struct buf *bp); 106 static void vfs_clean_pages_dirty_buf(struct buf *bp); 107 static void vfs_setdirty_locked_object(struct buf *bp); 108 static void vfs_vmio_release(struct buf *bp); 109 static int vfs_bio_clcheck(struct vnode *vp, int size, 110 daddr_t lblkno, daddr_t blkno); 111 static int buf_do_flush(struct vnode *vp); 112 static int flushbufqueues(struct vnode *, int, int); 113 static void buf_daemon(void); 114 static void bremfreel(struct buf *bp); 115 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 116 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 117 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 118 #endif 119 120 int vmiodirenable = TRUE; 121 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 122 "Use the VM system for directory writes"); 123 long runningbufspace; 124 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 125 "Amount of presently outstanding async buffer io"); 126 static long bufspace; 127 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 128 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 129 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 130 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 131 #else 132 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 133 "Virtual memory used for buffers"); 134 #endif 135 static long maxbufspace; 136 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 137 "Maximum allowed value of bufspace (including buf_daemon)"); 138 static long bufmallocspace; 139 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 140 "Amount of malloced memory for buffers"); 141 static long maxbufmallocspace; 142 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 143 "Maximum amount of malloced memory for buffers"); 144 static long lobufspace; 145 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 146 "Minimum amount of buffers we want to have"); 147 long hibufspace; 148 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 149 "Maximum allowed value of bufspace (excluding buf_daemon)"); 150 static int bufreusecnt; 151 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 152 "Number of times we have reused a buffer"); 153 static int buffreekvacnt; 154 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 155 "Number of times we have freed the KVA space from some buffer"); 156 static int bufdefragcnt; 157 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 158 "Number of times we have had to repeat buffer allocation to defragment"); 159 static long lorunningspace; 160 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 161 "Minimum preferred space used for in-progress I/O"); 162 static long hirunningspace; 163 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 164 "Maximum amount of space to use for in-progress I/O"); 165 int dirtybufferflushes; 166 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 167 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 168 int bdwriteskip; 169 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 170 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 171 int altbufferflushes; 172 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 173 0, "Number of fsync flushes to limit dirty buffers"); 174 static int recursiveflushes; 175 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 176 0, "Number of flushes skipped due to being recursive"); 177 static int numdirtybuffers; 178 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 179 "Number of buffers that are dirty (has unwritten changes) at the moment"); 180 static int lodirtybuffers; 181 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 182 "How many buffers we want to have free before bufdaemon can sleep"); 183 static int hidirtybuffers; 184 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 185 "When the number of dirty buffers is considered severe"); 186 int dirtybufthresh; 187 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 188 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 189 static int numfreebuffers; 190 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 191 "Number of free buffers"); 192 static int lofreebuffers; 193 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 194 "XXX Unused"); 195 static int hifreebuffers; 196 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 197 "XXX Complicatedly unused"); 198 static int getnewbufcalls; 199 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 200 "Number of calls to getnewbuf"); 201 static int getnewbufrestarts; 202 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 203 "Number of times getnewbuf has had to restart a buffer aquisition"); 204 static int flushbufqtarget = 100; 205 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 206 "Amount of work to do in flushbufqueues when helping bufdaemon"); 207 static long notbufdflashes; 208 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, 209 "Number of dirty buffer flushes done by the bufdaemon helpers"); 210 static long barrierwrites; 211 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 212 "Number of barrier writes"); 213 214 /* 215 * Wakeup point for bufdaemon, as well as indicator of whether it is already 216 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 217 * is idling. 218 */ 219 static int bd_request; 220 221 /* 222 * Request for the buf daemon to write more buffers than is indicated by 223 * lodirtybuf. This may be necessary to push out excess dependencies or 224 * defragment the address space where a simple count of the number of dirty 225 * buffers is insufficient to characterize the demand for flushing them. 226 */ 227 static int bd_speedupreq; 228 229 /* 230 * This lock synchronizes access to bd_request. 231 */ 232 static struct mtx bdlock; 233 234 /* 235 * bogus page -- for I/O to/from partially complete buffers 236 * this is a temporary solution to the problem, but it is not 237 * really that bad. it would be better to split the buffer 238 * for input in the case of buffers partially already in memory, 239 * but the code is intricate enough already. 240 */ 241 vm_page_t bogus_page; 242 243 /* 244 * Synchronization (sleep/wakeup) variable for active buffer space requests. 245 * Set when wait starts, cleared prior to wakeup(). 246 * Used in runningbufwakeup() and waitrunningbufspace(). 247 */ 248 static int runningbufreq; 249 250 /* 251 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 252 * waitrunningbufspace(). 253 */ 254 static struct mtx rbreqlock; 255 256 /* 257 * Synchronization (sleep/wakeup) variable for buffer requests. 258 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 259 * by and/or. 260 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 261 * getnewbuf(), and getblk(). 262 */ 263 static int needsbuffer; 264 265 /* 266 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 267 */ 268 static struct mtx nblock; 269 270 /* 271 * Definitions for the buffer free lists. 272 */ 273 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 274 275 #define QUEUE_NONE 0 /* on no queue */ 276 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 277 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 278 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 279 #define QUEUE_EMPTY 4 /* empty buffer headers */ 280 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 281 282 /* Queues for free buffers with various properties */ 283 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 284 285 /* Lock for the bufqueues */ 286 static struct mtx bqlock; 287 288 /* 289 * Single global constant for BUF_WMESG, to avoid getting multiple references. 290 * buf_wmesg is referred from macros. 291 */ 292 const char *buf_wmesg = BUF_WMESG; 293 294 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 295 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 296 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 297 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 298 299 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 300 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 301 static int 302 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 303 { 304 long lvalue; 305 int ivalue; 306 307 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 308 return (sysctl_handle_long(oidp, arg1, arg2, req)); 309 lvalue = *(long *)arg1; 310 if (lvalue > INT_MAX) 311 /* On overflow, still write out a long to trigger ENOMEM. */ 312 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 313 ivalue = lvalue; 314 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 315 } 316 #endif 317 318 #ifdef DIRECTIO 319 extern void ffs_rawread_setup(void); 320 #endif /* DIRECTIO */ 321 /* 322 * numdirtywakeup: 323 * 324 * If someone is blocked due to there being too many dirty buffers, 325 * and numdirtybuffers is now reasonable, wake them up. 326 */ 327 328 static __inline void 329 numdirtywakeup(int level) 330 { 331 332 if (numdirtybuffers <= level) { 333 mtx_lock(&nblock); 334 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 335 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 336 wakeup(&needsbuffer); 337 } 338 mtx_unlock(&nblock); 339 } 340 } 341 342 /* 343 * bufspacewakeup: 344 * 345 * Called when buffer space is potentially available for recovery. 346 * getnewbuf() will block on this flag when it is unable to free 347 * sufficient buffer space. Buffer space becomes recoverable when 348 * bp's get placed back in the queues. 349 */ 350 351 static __inline void 352 bufspacewakeup(void) 353 { 354 355 /* 356 * If someone is waiting for BUF space, wake them up. Even 357 * though we haven't freed the kva space yet, the waiting 358 * process will be able to now. 359 */ 360 mtx_lock(&nblock); 361 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 362 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 363 wakeup(&needsbuffer); 364 } 365 mtx_unlock(&nblock); 366 } 367 368 /* 369 * runningbufwakeup() - in-progress I/O accounting. 370 * 371 */ 372 void 373 runningbufwakeup(struct buf *bp) 374 { 375 376 if (bp->b_runningbufspace) { 377 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 378 bp->b_runningbufspace = 0; 379 mtx_lock(&rbreqlock); 380 if (runningbufreq && runningbufspace <= lorunningspace) { 381 runningbufreq = 0; 382 wakeup(&runningbufreq); 383 } 384 mtx_unlock(&rbreqlock); 385 } 386 } 387 388 /* 389 * bufcountwakeup: 390 * 391 * Called when a buffer has been added to one of the free queues to 392 * account for the buffer and to wakeup anyone waiting for free buffers. 393 * This typically occurs when large amounts of metadata are being handled 394 * by the buffer cache ( else buffer space runs out first, usually ). 395 */ 396 397 static __inline void 398 bufcountwakeup(struct buf *bp) 399 { 400 int old; 401 402 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 403 ("buf %p already counted as free", bp)); 404 if (bp->b_bufobj != NULL) 405 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 406 bp->b_vflags |= BV_INFREECNT; 407 old = atomic_fetchadd_int(&numfreebuffers, 1); 408 KASSERT(old >= 0 && old < nbuf, 409 ("numfreebuffers climbed to %d", old + 1)); 410 mtx_lock(&nblock); 411 if (needsbuffer) { 412 needsbuffer &= ~VFS_BIO_NEED_ANY; 413 if (numfreebuffers >= hifreebuffers) 414 needsbuffer &= ~VFS_BIO_NEED_FREE; 415 wakeup(&needsbuffer); 416 } 417 mtx_unlock(&nblock); 418 } 419 420 /* 421 * waitrunningbufspace() 422 * 423 * runningbufspace is a measure of the amount of I/O currently 424 * running. This routine is used in async-write situations to 425 * prevent creating huge backups of pending writes to a device. 426 * Only asynchronous writes are governed by this function. 427 * 428 * Reads will adjust runningbufspace, but will not block based on it. 429 * The read load has a side effect of reducing the allowed write load. 430 * 431 * This does NOT turn an async write into a sync write. It waits 432 * for earlier writes to complete and generally returns before the 433 * caller's write has reached the device. 434 */ 435 void 436 waitrunningbufspace(void) 437 { 438 439 mtx_lock(&rbreqlock); 440 while (runningbufspace > hirunningspace) { 441 ++runningbufreq; 442 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 443 } 444 mtx_unlock(&rbreqlock); 445 } 446 447 448 /* 449 * vfs_buf_test_cache: 450 * 451 * Called when a buffer is extended. This function clears the B_CACHE 452 * bit if the newly extended portion of the buffer does not contain 453 * valid data. 454 */ 455 static __inline 456 void 457 vfs_buf_test_cache(struct buf *bp, 458 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 459 vm_page_t m) 460 { 461 462 VM_OBJECT_ASSERT_WLOCKED(m->object); 463 if (bp->b_flags & B_CACHE) { 464 int base = (foff + off) & PAGE_MASK; 465 if (vm_page_is_valid(m, base, size) == 0) 466 bp->b_flags &= ~B_CACHE; 467 } 468 } 469 470 /* Wake up the buffer daemon if necessary */ 471 static __inline 472 void 473 bd_wakeup(int dirtybuflevel) 474 { 475 476 mtx_lock(&bdlock); 477 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 478 bd_request = 1; 479 wakeup(&bd_request); 480 } 481 mtx_unlock(&bdlock); 482 } 483 484 /* 485 * bd_speedup - speedup the buffer cache flushing code 486 */ 487 488 void 489 bd_speedup(void) 490 { 491 int needwake; 492 493 mtx_lock(&bdlock); 494 needwake = 0; 495 if (bd_speedupreq == 0 || bd_request == 0) 496 needwake = 1; 497 bd_speedupreq = 1; 498 bd_request = 1; 499 if (needwake) 500 wakeup(&bd_request); 501 mtx_unlock(&bdlock); 502 } 503 504 /* 505 * Calculating buffer cache scaling values and reserve space for buffer 506 * headers. This is called during low level kernel initialization and 507 * may be called more then once. We CANNOT write to the memory area 508 * being reserved at this time. 509 */ 510 caddr_t 511 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 512 { 513 int tuned_nbuf; 514 long maxbuf; 515 516 /* 517 * physmem_est is in pages. Convert it to kilobytes (assumes 518 * PAGE_SIZE is >= 1K) 519 */ 520 physmem_est = physmem_est * (PAGE_SIZE / 1024); 521 522 /* 523 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 524 * For the first 64MB of ram nominally allocate sufficient buffers to 525 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 526 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 527 * the buffer cache we limit the eventual kva reservation to 528 * maxbcache bytes. 529 * 530 * factor represents the 1/4 x ram conversion. 531 */ 532 if (nbuf == 0) { 533 int factor = 4 * BKVASIZE / 1024; 534 535 nbuf = 50; 536 if (physmem_est > 4096) 537 nbuf += min((physmem_est - 4096) / factor, 538 65536 / factor); 539 if (physmem_est > 65536) 540 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 541 542 if (maxbcache && nbuf > maxbcache / BKVASIZE) 543 nbuf = maxbcache / BKVASIZE; 544 tuned_nbuf = 1; 545 } else 546 tuned_nbuf = 0; 547 548 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 549 maxbuf = (LONG_MAX / 3) / BKVASIZE; 550 if (nbuf > maxbuf) { 551 if (!tuned_nbuf) 552 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 553 maxbuf); 554 nbuf = maxbuf; 555 } 556 557 /* 558 * swbufs are used as temporary holders for I/O, such as paging I/O. 559 * We have no less then 16 and no more then 256. 560 */ 561 nswbuf = max(min(nbuf/4, 256), 16); 562 #ifdef NSWBUF_MIN 563 if (nswbuf < NSWBUF_MIN) 564 nswbuf = NSWBUF_MIN; 565 #endif 566 #ifdef DIRECTIO 567 ffs_rawread_setup(); 568 #endif 569 570 /* 571 * Reserve space for the buffer cache buffers 572 */ 573 swbuf = (void *)v; 574 v = (caddr_t)(swbuf + nswbuf); 575 buf = (void *)v; 576 v = (caddr_t)(buf + nbuf); 577 578 return(v); 579 } 580 581 /* Initialize the buffer subsystem. Called before use of any buffers. */ 582 void 583 bufinit(void) 584 { 585 struct buf *bp; 586 int i; 587 588 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 589 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 590 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 591 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 592 593 /* next, make a null set of free lists */ 594 for (i = 0; i < BUFFER_QUEUES; i++) 595 TAILQ_INIT(&bufqueues[i]); 596 597 /* finally, initialize each buffer header and stick on empty q */ 598 for (i = 0; i < nbuf; i++) { 599 bp = &buf[i]; 600 bzero(bp, sizeof *bp); 601 bp->b_flags = B_INVAL; /* we're just an empty header */ 602 bp->b_rcred = NOCRED; 603 bp->b_wcred = NOCRED; 604 bp->b_qindex = QUEUE_EMPTY; 605 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */ 606 bp->b_xflags = 0; 607 LIST_INIT(&bp->b_dep); 608 BUF_LOCKINIT(bp); 609 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 610 } 611 612 /* 613 * maxbufspace is the absolute maximum amount of buffer space we are 614 * allowed to reserve in KVM and in real terms. The absolute maximum 615 * is nominally used by buf_daemon. hibufspace is the nominal maximum 616 * used by most other processes. The differential is required to 617 * ensure that buf_daemon is able to run when other processes might 618 * be blocked waiting for buffer space. 619 * 620 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 621 * this may result in KVM fragmentation which is not handled optimally 622 * by the system. 623 */ 624 maxbufspace = (long)nbuf * BKVASIZE; 625 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 626 lobufspace = hibufspace - MAXBSIZE; 627 628 /* 629 * Note: The 16 MiB upper limit for hirunningspace was chosen 630 * arbitrarily and may need further tuning. It corresponds to 631 * 128 outstanding write IO requests (if IO size is 128 KiB), 632 * which fits with many RAID controllers' tagged queuing limits. 633 * The lower 1 MiB limit is the historical upper limit for 634 * hirunningspace. 635 */ 636 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 637 16 * 1024 * 1024), 1024 * 1024); 638 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 639 640 /* 641 * Limit the amount of malloc memory since it is wired permanently into 642 * the kernel space. Even though this is accounted for in the buffer 643 * allocation, we don't want the malloced region to grow uncontrolled. 644 * The malloc scheme improves memory utilization significantly on average 645 * (small) directories. 646 */ 647 maxbufmallocspace = hibufspace / 20; 648 649 /* 650 * Reduce the chance of a deadlock occuring by limiting the number 651 * of delayed-write dirty buffers we allow to stack up. 652 */ 653 hidirtybuffers = nbuf / 4 + 20; 654 dirtybufthresh = hidirtybuffers * 9 / 10; 655 numdirtybuffers = 0; 656 /* 657 * To support extreme low-memory systems, make sure hidirtybuffers cannot 658 * eat up all available buffer space. This occurs when our minimum cannot 659 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 660 * BKVASIZE'd buffers. 661 */ 662 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 663 hidirtybuffers >>= 1; 664 } 665 lodirtybuffers = hidirtybuffers / 2; 666 667 /* 668 * Try to keep the number of free buffers in the specified range, 669 * and give special processes (e.g. like buf_daemon) access to an 670 * emergency reserve. 671 */ 672 lofreebuffers = nbuf / 18 + 5; 673 hifreebuffers = 2 * lofreebuffers; 674 numfreebuffers = nbuf; 675 676 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 677 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 678 } 679 680 /* 681 * bfreekva() - free the kva allocation for a buffer. 682 * 683 * Since this call frees up buffer space, we call bufspacewakeup(). 684 */ 685 static void 686 bfreekva(struct buf *bp) 687 { 688 689 if (bp->b_kvasize) { 690 atomic_add_int(&buffreekvacnt, 1); 691 atomic_subtract_long(&bufspace, bp->b_kvasize); 692 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 693 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 694 bp->b_kvasize = 0; 695 bufspacewakeup(); 696 } 697 } 698 699 /* 700 * bremfree: 701 * 702 * Mark the buffer for removal from the appropriate free list in brelse. 703 * 704 */ 705 void 706 bremfree(struct buf *bp) 707 { 708 int old; 709 710 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 711 KASSERT((bp->b_flags & B_REMFREE) == 0, 712 ("bremfree: buffer %p already marked for delayed removal.", bp)); 713 KASSERT(bp->b_qindex != QUEUE_NONE, 714 ("bremfree: buffer %p not on a queue.", bp)); 715 BUF_ASSERT_HELD(bp); 716 717 bp->b_flags |= B_REMFREE; 718 /* Fixup numfreebuffers count. */ 719 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 720 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 721 ("buf %p not counted in numfreebuffers", bp)); 722 if (bp->b_bufobj != NULL) 723 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 724 bp->b_vflags &= ~BV_INFREECNT; 725 old = atomic_fetchadd_int(&numfreebuffers, -1); 726 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 727 } 728 } 729 730 /* 731 * bremfreef: 732 * 733 * Force an immediate removal from a free list. Used only in nfs when 734 * it abuses the b_freelist pointer. 735 */ 736 void 737 bremfreef(struct buf *bp) 738 { 739 mtx_lock(&bqlock); 740 bremfreel(bp); 741 mtx_unlock(&bqlock); 742 } 743 744 /* 745 * bremfreel: 746 * 747 * Removes a buffer from the free list, must be called with the 748 * bqlock held. 749 */ 750 static void 751 bremfreel(struct buf *bp) 752 { 753 int old; 754 755 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 756 bp, bp->b_vp, bp->b_flags); 757 KASSERT(bp->b_qindex != QUEUE_NONE, 758 ("bremfreel: buffer %p not on a queue.", bp)); 759 BUF_ASSERT_HELD(bp); 760 mtx_assert(&bqlock, MA_OWNED); 761 762 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 763 bp->b_qindex = QUEUE_NONE; 764 /* 765 * If this was a delayed bremfree() we only need to remove the buffer 766 * from the queue and return the stats are already done. 767 */ 768 if (bp->b_flags & B_REMFREE) { 769 bp->b_flags &= ~B_REMFREE; 770 return; 771 } 772 /* 773 * Fixup numfreebuffers count. If the buffer is invalid or not 774 * delayed-write, the buffer was free and we must decrement 775 * numfreebuffers. 776 */ 777 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 778 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 779 ("buf %p not counted in numfreebuffers", bp)); 780 if (bp->b_bufobj != NULL) 781 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 782 bp->b_vflags &= ~BV_INFREECNT; 783 old = atomic_fetchadd_int(&numfreebuffers, -1); 784 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 785 } 786 } 787 788 /* 789 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 790 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 791 * the buffer is valid and we do not have to do anything. 792 */ 793 void 794 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 795 int cnt, struct ucred * cred) 796 { 797 struct buf *rabp; 798 int i; 799 800 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 801 if (inmem(vp, *rablkno)) 802 continue; 803 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 804 805 if ((rabp->b_flags & B_CACHE) == 0) { 806 if (!TD_IS_IDLETHREAD(curthread)) 807 curthread->td_ru.ru_inblock++; 808 rabp->b_flags |= B_ASYNC; 809 rabp->b_flags &= ~B_INVAL; 810 rabp->b_ioflags &= ~BIO_ERROR; 811 rabp->b_iocmd = BIO_READ; 812 if (rabp->b_rcred == NOCRED && cred != NOCRED) 813 rabp->b_rcred = crhold(cred); 814 vfs_busy_pages(rabp, 0); 815 BUF_KERNPROC(rabp); 816 rabp->b_iooffset = dbtob(rabp->b_blkno); 817 bstrategy(rabp); 818 } else { 819 brelse(rabp); 820 } 821 } 822 } 823 824 /* 825 * Entry point for bread() and breadn() via #defines in sys/buf.h. 826 * 827 * Get a buffer with the specified data. Look in the cache first. We 828 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 829 * is set, the buffer is valid and we do not have to do anything, see 830 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 831 */ 832 int 833 breadn_flags(struct vnode *vp, daddr_t blkno, int size, daddr_t *rablkno, 834 int *rabsize, int cnt, struct ucred *cred, int flags, struct buf **bpp) 835 { 836 struct buf *bp; 837 int rv = 0, readwait = 0; 838 839 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 840 /* 841 * Can only return NULL if GB_LOCK_NOWAIT flag is specified. 842 */ 843 *bpp = bp = getblk(vp, blkno, size, 0, 0, flags); 844 if (bp == NULL) 845 return (EBUSY); 846 847 /* if not found in cache, do some I/O */ 848 if ((bp->b_flags & B_CACHE) == 0) { 849 if (!TD_IS_IDLETHREAD(curthread)) 850 curthread->td_ru.ru_inblock++; 851 bp->b_iocmd = BIO_READ; 852 bp->b_flags &= ~B_INVAL; 853 bp->b_ioflags &= ~BIO_ERROR; 854 if (bp->b_rcred == NOCRED && cred != NOCRED) 855 bp->b_rcred = crhold(cred); 856 vfs_busy_pages(bp, 0); 857 bp->b_iooffset = dbtob(bp->b_blkno); 858 bstrategy(bp); 859 ++readwait; 860 } 861 862 breada(vp, rablkno, rabsize, cnt, cred); 863 864 if (readwait) { 865 rv = bufwait(bp); 866 } 867 return (rv); 868 } 869 870 /* 871 * Write, release buffer on completion. (Done by iodone 872 * if async). Do not bother writing anything if the buffer 873 * is invalid. 874 * 875 * Note that we set B_CACHE here, indicating that buffer is 876 * fully valid and thus cacheable. This is true even of NFS 877 * now so we set it generally. This could be set either here 878 * or in biodone() since the I/O is synchronous. We put it 879 * here. 880 */ 881 int 882 bufwrite(struct buf *bp) 883 { 884 int oldflags; 885 struct vnode *vp; 886 int vp_md; 887 888 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 889 if (bp->b_flags & B_INVAL) { 890 brelse(bp); 891 return (0); 892 } 893 894 if (bp->b_flags & B_BARRIER) 895 barrierwrites++; 896 897 oldflags = bp->b_flags; 898 899 BUF_ASSERT_HELD(bp); 900 901 if (bp->b_pin_count > 0) 902 bunpin_wait(bp); 903 904 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 905 ("FFS background buffer should not get here %p", bp)); 906 907 vp = bp->b_vp; 908 if (vp) 909 vp_md = vp->v_vflag & VV_MD; 910 else 911 vp_md = 0; 912 913 /* Mark the buffer clean */ 914 bundirty(bp); 915 916 bp->b_flags &= ~B_DONE; 917 bp->b_ioflags &= ~BIO_ERROR; 918 bp->b_flags |= B_CACHE; 919 bp->b_iocmd = BIO_WRITE; 920 921 bufobj_wref(bp->b_bufobj); 922 vfs_busy_pages(bp, 1); 923 924 /* 925 * Normal bwrites pipeline writes 926 */ 927 bp->b_runningbufspace = bp->b_bufsize; 928 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 929 930 if (!TD_IS_IDLETHREAD(curthread)) 931 curthread->td_ru.ru_oublock++; 932 if (oldflags & B_ASYNC) 933 BUF_KERNPROC(bp); 934 bp->b_iooffset = dbtob(bp->b_blkno); 935 bstrategy(bp); 936 937 if ((oldflags & B_ASYNC) == 0) { 938 int rtval = bufwait(bp); 939 brelse(bp); 940 return (rtval); 941 } else { 942 /* 943 * don't allow the async write to saturate the I/O 944 * system. We will not deadlock here because 945 * we are blocking waiting for I/O that is already in-progress 946 * to complete. We do not block here if it is the update 947 * or syncer daemon trying to clean up as that can lead 948 * to deadlock. 949 */ 950 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 951 waitrunningbufspace(); 952 } 953 954 return (0); 955 } 956 957 void 958 bufbdflush(struct bufobj *bo, struct buf *bp) 959 { 960 struct buf *nbp; 961 962 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 963 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 964 altbufferflushes++; 965 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 966 BO_LOCK(bo); 967 /* 968 * Try to find a buffer to flush. 969 */ 970 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 971 if ((nbp->b_vflags & BV_BKGRDINPROG) || 972 BUF_LOCK(nbp, 973 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 974 continue; 975 if (bp == nbp) 976 panic("bdwrite: found ourselves"); 977 BO_UNLOCK(bo); 978 /* Don't countdeps with the bo lock held. */ 979 if (buf_countdeps(nbp, 0)) { 980 BO_LOCK(bo); 981 BUF_UNLOCK(nbp); 982 continue; 983 } 984 if (nbp->b_flags & B_CLUSTEROK) { 985 vfs_bio_awrite(nbp); 986 } else { 987 bremfree(nbp); 988 bawrite(nbp); 989 } 990 dirtybufferflushes++; 991 break; 992 } 993 if (nbp == NULL) 994 BO_UNLOCK(bo); 995 } 996 } 997 998 /* 999 * Delayed write. (Buffer is marked dirty). Do not bother writing 1000 * anything if the buffer is marked invalid. 1001 * 1002 * Note that since the buffer must be completely valid, we can safely 1003 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1004 * biodone() in order to prevent getblk from writing the buffer 1005 * out synchronously. 1006 */ 1007 void 1008 bdwrite(struct buf *bp) 1009 { 1010 struct thread *td = curthread; 1011 struct vnode *vp; 1012 struct bufobj *bo; 1013 1014 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1015 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1016 KASSERT((bp->b_flags & B_BARRIER) == 0, 1017 ("Barrier request in delayed write %p", bp)); 1018 BUF_ASSERT_HELD(bp); 1019 1020 if (bp->b_flags & B_INVAL) { 1021 brelse(bp); 1022 return; 1023 } 1024 1025 /* 1026 * If we have too many dirty buffers, don't create any more. 1027 * If we are wildly over our limit, then force a complete 1028 * cleanup. Otherwise, just keep the situation from getting 1029 * out of control. Note that we have to avoid a recursive 1030 * disaster and not try to clean up after our own cleanup! 1031 */ 1032 vp = bp->b_vp; 1033 bo = bp->b_bufobj; 1034 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1035 td->td_pflags |= TDP_INBDFLUSH; 1036 BO_BDFLUSH(bo, bp); 1037 td->td_pflags &= ~TDP_INBDFLUSH; 1038 } else 1039 recursiveflushes++; 1040 1041 bdirty(bp); 1042 /* 1043 * Set B_CACHE, indicating that the buffer is fully valid. This is 1044 * true even of NFS now. 1045 */ 1046 bp->b_flags |= B_CACHE; 1047 1048 /* 1049 * This bmap keeps the system from needing to do the bmap later, 1050 * perhaps when the system is attempting to do a sync. Since it 1051 * is likely that the indirect block -- or whatever other datastructure 1052 * that the filesystem needs is still in memory now, it is a good 1053 * thing to do this. Note also, that if the pageout daemon is 1054 * requesting a sync -- there might not be enough memory to do 1055 * the bmap then... So, this is important to do. 1056 */ 1057 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1058 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1059 } 1060 1061 /* 1062 * Set the *dirty* buffer range based upon the VM system dirty 1063 * pages. 1064 * 1065 * Mark the buffer pages as clean. We need to do this here to 1066 * satisfy the vnode_pager and the pageout daemon, so that it 1067 * thinks that the pages have been "cleaned". Note that since 1068 * the pages are in a delayed write buffer -- the VFS layer 1069 * "will" see that the pages get written out on the next sync, 1070 * or perhaps the cluster will be completed. 1071 */ 1072 vfs_clean_pages_dirty_buf(bp); 1073 bqrelse(bp); 1074 1075 /* 1076 * Wakeup the buffer flushing daemon if we have a lot of dirty 1077 * buffers (midpoint between our recovery point and our stall 1078 * point). 1079 */ 1080 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1081 1082 /* 1083 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1084 * due to the softdep code. 1085 */ 1086 } 1087 1088 /* 1089 * bdirty: 1090 * 1091 * Turn buffer into delayed write request. We must clear BIO_READ and 1092 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1093 * itself to properly update it in the dirty/clean lists. We mark it 1094 * B_DONE to ensure that any asynchronization of the buffer properly 1095 * clears B_DONE ( else a panic will occur later ). 1096 * 1097 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1098 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1099 * should only be called if the buffer is known-good. 1100 * 1101 * Since the buffer is not on a queue, we do not update the numfreebuffers 1102 * count. 1103 * 1104 * The buffer must be on QUEUE_NONE. 1105 */ 1106 void 1107 bdirty(struct buf *bp) 1108 { 1109 1110 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1111 bp, bp->b_vp, bp->b_flags); 1112 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1113 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1114 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1115 BUF_ASSERT_HELD(bp); 1116 bp->b_flags &= ~(B_RELBUF); 1117 bp->b_iocmd = BIO_WRITE; 1118 1119 if ((bp->b_flags & B_DELWRI) == 0) { 1120 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1121 reassignbuf(bp); 1122 atomic_add_int(&numdirtybuffers, 1); 1123 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1124 } 1125 } 1126 1127 /* 1128 * bundirty: 1129 * 1130 * Clear B_DELWRI for buffer. 1131 * 1132 * Since the buffer is not on a queue, we do not update the numfreebuffers 1133 * count. 1134 * 1135 * The buffer must be on QUEUE_NONE. 1136 */ 1137 1138 void 1139 bundirty(struct buf *bp) 1140 { 1141 1142 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1143 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1144 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1145 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1146 BUF_ASSERT_HELD(bp); 1147 1148 if (bp->b_flags & B_DELWRI) { 1149 bp->b_flags &= ~B_DELWRI; 1150 reassignbuf(bp); 1151 atomic_subtract_int(&numdirtybuffers, 1); 1152 numdirtywakeup(lodirtybuffers); 1153 } 1154 /* 1155 * Since it is now being written, we can clear its deferred write flag. 1156 */ 1157 bp->b_flags &= ~B_DEFERRED; 1158 } 1159 1160 /* 1161 * bawrite: 1162 * 1163 * Asynchronous write. Start output on a buffer, but do not wait for 1164 * it to complete. The buffer is released when the output completes. 1165 * 1166 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1167 * B_INVAL buffers. Not us. 1168 */ 1169 void 1170 bawrite(struct buf *bp) 1171 { 1172 1173 bp->b_flags |= B_ASYNC; 1174 (void) bwrite(bp); 1175 } 1176 1177 /* 1178 * babarrierwrite: 1179 * 1180 * Asynchronous barrier write. Start output on a buffer, but do not 1181 * wait for it to complete. Place a write barrier after this write so 1182 * that this buffer and all buffers written before it are committed to 1183 * the disk before any buffers written after this write are committed 1184 * to the disk. The buffer is released when the output completes. 1185 */ 1186 void 1187 babarrierwrite(struct buf *bp) 1188 { 1189 1190 bp->b_flags |= B_ASYNC | B_BARRIER; 1191 (void) bwrite(bp); 1192 } 1193 1194 /* 1195 * bbarrierwrite: 1196 * 1197 * Synchronous barrier write. Start output on a buffer and wait for 1198 * it to complete. Place a write barrier after this write so that 1199 * this buffer and all buffers written before it are committed to 1200 * the disk before any buffers written after this write are committed 1201 * to the disk. The buffer is released when the output completes. 1202 */ 1203 int 1204 bbarrierwrite(struct buf *bp) 1205 { 1206 1207 bp->b_flags |= B_BARRIER; 1208 return (bwrite(bp)); 1209 } 1210 1211 /* 1212 * bwillwrite: 1213 * 1214 * Called prior to the locking of any vnodes when we are expecting to 1215 * write. We do not want to starve the buffer cache with too many 1216 * dirty buffers so we block here. By blocking prior to the locking 1217 * of any vnodes we attempt to avoid the situation where a locked vnode 1218 * prevents the various system daemons from flushing related buffers. 1219 */ 1220 1221 void 1222 bwillwrite(void) 1223 { 1224 1225 if (numdirtybuffers >= hidirtybuffers) { 1226 mtx_lock(&nblock); 1227 while (numdirtybuffers >= hidirtybuffers) { 1228 bd_wakeup(1); 1229 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1230 msleep(&needsbuffer, &nblock, 1231 (PRIBIO + 4), "flswai", 0); 1232 } 1233 mtx_unlock(&nblock); 1234 } 1235 } 1236 1237 /* 1238 * Return true if we have too many dirty buffers. 1239 */ 1240 int 1241 buf_dirty_count_severe(void) 1242 { 1243 1244 return(numdirtybuffers >= hidirtybuffers); 1245 } 1246 1247 static __noinline int 1248 buf_vm_page_count_severe(void) 1249 { 1250 1251 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1252 1253 return vm_page_count_severe(); 1254 } 1255 1256 /* 1257 * brelse: 1258 * 1259 * Release a busy buffer and, if requested, free its resources. The 1260 * buffer will be stashed in the appropriate bufqueue[] allowing it 1261 * to be accessed later as a cache entity or reused for other purposes. 1262 */ 1263 void 1264 brelse(struct buf *bp) 1265 { 1266 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1267 bp, bp->b_vp, bp->b_flags); 1268 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1269 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1270 1271 if (BUF_LOCKRECURSED(bp)) { 1272 /* 1273 * Do not process, in particular, do not handle the 1274 * B_INVAL/B_RELBUF and do not release to free list. 1275 */ 1276 BUF_UNLOCK(bp); 1277 return; 1278 } 1279 1280 if (bp->b_flags & B_MANAGED) { 1281 bqrelse(bp); 1282 return; 1283 } 1284 1285 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1286 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1287 /* 1288 * Failed write, redirty. Must clear BIO_ERROR to prevent 1289 * pages from being scrapped. If the error is anything 1290 * other than an I/O error (EIO), assume that retrying 1291 * is futile. 1292 */ 1293 bp->b_ioflags &= ~BIO_ERROR; 1294 bdirty(bp); 1295 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1296 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1297 /* 1298 * Either a failed I/O or we were asked to free or not 1299 * cache the buffer. 1300 */ 1301 bp->b_flags |= B_INVAL; 1302 if (!LIST_EMPTY(&bp->b_dep)) 1303 buf_deallocate(bp); 1304 if (bp->b_flags & B_DELWRI) { 1305 atomic_subtract_int(&numdirtybuffers, 1); 1306 numdirtywakeup(lodirtybuffers); 1307 } 1308 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1309 if ((bp->b_flags & B_VMIO) == 0) { 1310 if (bp->b_bufsize) 1311 allocbuf(bp, 0); 1312 if (bp->b_vp) 1313 brelvp(bp); 1314 } 1315 } 1316 1317 /* 1318 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1319 * is called with B_DELWRI set, the underlying pages may wind up 1320 * getting freed causing a previous write (bdwrite()) to get 'lost' 1321 * because pages associated with a B_DELWRI bp are marked clean. 1322 * 1323 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1324 * if B_DELWRI is set. 1325 * 1326 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1327 * on pages to return pages to the VM page queues. 1328 */ 1329 if (bp->b_flags & B_DELWRI) 1330 bp->b_flags &= ~B_RELBUF; 1331 else if (buf_vm_page_count_severe()) { 1332 /* 1333 * The locking of the BO_LOCK is not necessary since 1334 * BKGRDINPROG cannot be set while we hold the buf 1335 * lock, it can only be cleared if it is already 1336 * pending. 1337 */ 1338 if (bp->b_vp) { 1339 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1340 bp->b_flags |= B_RELBUF; 1341 } else 1342 bp->b_flags |= B_RELBUF; 1343 } 1344 1345 /* 1346 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1347 * constituted, not even NFS buffers now. Two flags effect this. If 1348 * B_INVAL, the struct buf is invalidated but the VM object is kept 1349 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1350 * 1351 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1352 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1353 * buffer is also B_INVAL because it hits the re-dirtying code above. 1354 * 1355 * Normally we can do this whether a buffer is B_DELWRI or not. If 1356 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1357 * the commit state and we cannot afford to lose the buffer. If the 1358 * buffer has a background write in progress, we need to keep it 1359 * around to prevent it from being reconstituted and starting a second 1360 * background write. 1361 */ 1362 if ((bp->b_flags & B_VMIO) 1363 && !(bp->b_vp->v_mount != NULL && 1364 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1365 !vn_isdisk(bp->b_vp, NULL) && 1366 (bp->b_flags & B_DELWRI)) 1367 ) { 1368 1369 int i, j, resid; 1370 vm_page_t m; 1371 off_t foff; 1372 vm_pindex_t poff; 1373 vm_object_t obj; 1374 1375 obj = bp->b_bufobj->bo_object; 1376 1377 /* 1378 * Get the base offset and length of the buffer. Note that 1379 * in the VMIO case if the buffer block size is not 1380 * page-aligned then b_data pointer may not be page-aligned. 1381 * But our b_pages[] array *IS* page aligned. 1382 * 1383 * block sizes less then DEV_BSIZE (usually 512) are not 1384 * supported due to the page granularity bits (m->valid, 1385 * m->dirty, etc...). 1386 * 1387 * See man buf(9) for more information 1388 */ 1389 resid = bp->b_bufsize; 1390 foff = bp->b_offset; 1391 VM_OBJECT_WLOCK(obj); 1392 for (i = 0; i < bp->b_npages; i++) { 1393 int had_bogus = 0; 1394 1395 m = bp->b_pages[i]; 1396 1397 /* 1398 * If we hit a bogus page, fixup *all* the bogus pages 1399 * now. 1400 */ 1401 if (m == bogus_page) { 1402 poff = OFF_TO_IDX(bp->b_offset); 1403 had_bogus = 1; 1404 1405 for (j = i; j < bp->b_npages; j++) { 1406 vm_page_t mtmp; 1407 mtmp = bp->b_pages[j]; 1408 if (mtmp == bogus_page) { 1409 mtmp = vm_page_lookup(obj, poff + j); 1410 if (!mtmp) { 1411 panic("brelse: page missing\n"); 1412 } 1413 bp->b_pages[j] = mtmp; 1414 } 1415 } 1416 1417 if ((bp->b_flags & B_INVAL) == 0) { 1418 pmap_qenter( 1419 trunc_page((vm_offset_t)bp->b_data), 1420 bp->b_pages, bp->b_npages); 1421 } 1422 m = bp->b_pages[i]; 1423 } 1424 if ((bp->b_flags & B_NOCACHE) || 1425 (bp->b_ioflags & BIO_ERROR && 1426 bp->b_iocmd == BIO_READ)) { 1427 int poffset = foff & PAGE_MASK; 1428 int presid = resid > (PAGE_SIZE - poffset) ? 1429 (PAGE_SIZE - poffset) : resid; 1430 1431 KASSERT(presid >= 0, ("brelse: extra page")); 1432 vm_page_set_invalid(m, poffset, presid); 1433 if (had_bogus) 1434 printf("avoided corruption bug in bogus_page/brelse code\n"); 1435 } 1436 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1437 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1438 } 1439 VM_OBJECT_WUNLOCK(obj); 1440 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1441 vfs_vmio_release(bp); 1442 1443 } else if (bp->b_flags & B_VMIO) { 1444 1445 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1446 vfs_vmio_release(bp); 1447 } 1448 1449 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1450 if (bp->b_bufsize != 0) 1451 allocbuf(bp, 0); 1452 if (bp->b_vp != NULL) 1453 brelvp(bp); 1454 } 1455 1456 /* enqueue */ 1457 mtx_lock(&bqlock); 1458 /* Handle delayed bremfree() processing. */ 1459 if (bp->b_flags & B_REMFREE) { 1460 struct bufobj *bo; 1461 1462 bo = bp->b_bufobj; 1463 if (bo != NULL) 1464 BO_LOCK(bo); 1465 bremfreel(bp); 1466 if (bo != NULL) 1467 BO_UNLOCK(bo); 1468 } 1469 if (bp->b_qindex != QUEUE_NONE) 1470 panic("brelse: free buffer onto another queue???"); 1471 1472 /* 1473 * If the buffer has junk contents signal it and eventually 1474 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1475 * doesn't find it. 1476 */ 1477 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1478 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1479 bp->b_flags |= B_INVAL; 1480 if (bp->b_flags & B_INVAL) { 1481 if (bp->b_flags & B_DELWRI) 1482 bundirty(bp); 1483 if (bp->b_vp) 1484 brelvp(bp); 1485 } 1486 1487 /* buffers with no memory */ 1488 if (bp->b_bufsize == 0) { 1489 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1490 if (bp->b_vflags & BV_BKGRDINPROG) 1491 panic("losing buffer 1"); 1492 if (bp->b_kvasize) { 1493 bp->b_qindex = QUEUE_EMPTYKVA; 1494 } else { 1495 bp->b_qindex = QUEUE_EMPTY; 1496 } 1497 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1498 /* buffers with junk contents */ 1499 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1500 (bp->b_ioflags & BIO_ERROR)) { 1501 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1502 if (bp->b_vflags & BV_BKGRDINPROG) 1503 panic("losing buffer 2"); 1504 bp->b_qindex = QUEUE_CLEAN; 1505 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1506 /* remaining buffers */ 1507 } else { 1508 if (bp->b_flags & B_DELWRI) 1509 bp->b_qindex = QUEUE_DIRTY; 1510 else 1511 bp->b_qindex = QUEUE_CLEAN; 1512 if (bp->b_flags & B_AGE) 1513 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1514 else 1515 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1516 } 1517 mtx_unlock(&bqlock); 1518 1519 /* 1520 * Fixup numfreebuffers count. The bp is on an appropriate queue 1521 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1522 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1523 * if B_INVAL is set ). 1524 */ 1525 1526 if (!(bp->b_flags & B_DELWRI)) { 1527 struct bufobj *bo; 1528 1529 bo = bp->b_bufobj; 1530 if (bo != NULL) 1531 BO_LOCK(bo); 1532 bufcountwakeup(bp); 1533 if (bo != NULL) 1534 BO_UNLOCK(bo); 1535 } 1536 1537 /* 1538 * Something we can maybe free or reuse 1539 */ 1540 if (bp->b_bufsize || bp->b_kvasize) 1541 bufspacewakeup(); 1542 1543 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1544 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1545 panic("brelse: not dirty"); 1546 /* unlock */ 1547 BUF_UNLOCK(bp); 1548 } 1549 1550 /* 1551 * Release a buffer back to the appropriate queue but do not try to free 1552 * it. The buffer is expected to be used again soon. 1553 * 1554 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1555 * biodone() to requeue an async I/O on completion. It is also used when 1556 * known good buffers need to be requeued but we think we may need the data 1557 * again soon. 1558 * 1559 * XXX we should be able to leave the B_RELBUF hint set on completion. 1560 */ 1561 void 1562 bqrelse(struct buf *bp) 1563 { 1564 struct bufobj *bo; 1565 1566 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1567 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1568 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1569 1570 if (BUF_LOCKRECURSED(bp)) { 1571 /* do not release to free list */ 1572 BUF_UNLOCK(bp); 1573 return; 1574 } 1575 1576 bo = bp->b_bufobj; 1577 if (bp->b_flags & B_MANAGED) { 1578 if (bp->b_flags & B_REMFREE) { 1579 mtx_lock(&bqlock); 1580 if (bo != NULL) 1581 BO_LOCK(bo); 1582 bremfreel(bp); 1583 if (bo != NULL) 1584 BO_UNLOCK(bo); 1585 mtx_unlock(&bqlock); 1586 } 1587 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1588 BUF_UNLOCK(bp); 1589 return; 1590 } 1591 1592 mtx_lock(&bqlock); 1593 /* Handle delayed bremfree() processing. */ 1594 if (bp->b_flags & B_REMFREE) { 1595 if (bo != NULL) 1596 BO_LOCK(bo); 1597 bremfreel(bp); 1598 if (bo != NULL) 1599 BO_UNLOCK(bo); 1600 } 1601 if (bp->b_qindex != QUEUE_NONE) 1602 panic("bqrelse: free buffer onto another queue???"); 1603 /* buffers with stale but valid contents */ 1604 if (bp->b_flags & B_DELWRI) { 1605 bp->b_qindex = QUEUE_DIRTY; 1606 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1607 } else { 1608 /* 1609 * The locking of the BO_LOCK for checking of the 1610 * BV_BKGRDINPROG is not necessary since the 1611 * BV_BKGRDINPROG cannot be set while we hold the buf 1612 * lock, it can only be cleared if it is already 1613 * pending. 1614 */ 1615 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1616 bp->b_qindex = QUEUE_CLEAN; 1617 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1618 b_freelist); 1619 } else { 1620 /* 1621 * We are too low on memory, we have to try to free 1622 * the buffer (most importantly: the wired pages 1623 * making up its backing store) *now*. 1624 */ 1625 mtx_unlock(&bqlock); 1626 brelse(bp); 1627 return; 1628 } 1629 } 1630 mtx_unlock(&bqlock); 1631 1632 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) { 1633 if (bo != NULL) 1634 BO_LOCK(bo); 1635 bufcountwakeup(bp); 1636 if (bo != NULL) 1637 BO_UNLOCK(bo); 1638 } 1639 1640 /* 1641 * Something we can maybe free or reuse. 1642 */ 1643 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1644 bufspacewakeup(); 1645 1646 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1647 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1648 panic("bqrelse: not dirty"); 1649 /* unlock */ 1650 BUF_UNLOCK(bp); 1651 } 1652 1653 /* Give pages used by the bp back to the VM system (where possible) */ 1654 static void 1655 vfs_vmio_release(struct buf *bp) 1656 { 1657 int i; 1658 vm_page_t m; 1659 1660 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1661 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 1662 for (i = 0; i < bp->b_npages; i++) { 1663 m = bp->b_pages[i]; 1664 bp->b_pages[i] = NULL; 1665 /* 1666 * In order to keep page LRU ordering consistent, put 1667 * everything on the inactive queue. 1668 */ 1669 vm_page_lock(m); 1670 vm_page_unwire(m, 0); 1671 /* 1672 * We don't mess with busy pages, it is 1673 * the responsibility of the process that 1674 * busied the pages to deal with them. 1675 */ 1676 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1677 m->wire_count == 0) { 1678 /* 1679 * Might as well free the page if we can and it has 1680 * no valid data. We also free the page if the 1681 * buffer was used for direct I/O 1682 */ 1683 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1684 vm_page_free(m); 1685 } else if (bp->b_flags & B_DIRECT) { 1686 vm_page_try_to_free(m); 1687 } else if (buf_vm_page_count_severe()) { 1688 vm_page_try_to_cache(m); 1689 } 1690 } 1691 vm_page_unlock(m); 1692 } 1693 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 1694 1695 if (bp->b_bufsize) { 1696 bufspacewakeup(); 1697 bp->b_bufsize = 0; 1698 } 1699 bp->b_npages = 0; 1700 bp->b_flags &= ~B_VMIO; 1701 if (bp->b_vp) 1702 brelvp(bp); 1703 } 1704 1705 /* 1706 * Check to see if a block at a particular lbn is available for a clustered 1707 * write. 1708 */ 1709 static int 1710 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1711 { 1712 struct buf *bpa; 1713 int match; 1714 1715 match = 0; 1716 1717 /* If the buf isn't in core skip it */ 1718 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1719 return (0); 1720 1721 /* If the buf is busy we don't want to wait for it */ 1722 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1723 return (0); 1724 1725 /* Only cluster with valid clusterable delayed write buffers */ 1726 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1727 (B_DELWRI | B_CLUSTEROK)) 1728 goto done; 1729 1730 if (bpa->b_bufsize != size) 1731 goto done; 1732 1733 /* 1734 * Check to see if it is in the expected place on disk and that the 1735 * block has been mapped. 1736 */ 1737 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1738 match = 1; 1739 done: 1740 BUF_UNLOCK(bpa); 1741 return (match); 1742 } 1743 1744 /* 1745 * vfs_bio_awrite: 1746 * 1747 * Implement clustered async writes for clearing out B_DELWRI buffers. 1748 * This is much better then the old way of writing only one buffer at 1749 * a time. Note that we may not be presented with the buffers in the 1750 * correct order, so we search for the cluster in both directions. 1751 */ 1752 int 1753 vfs_bio_awrite(struct buf *bp) 1754 { 1755 struct bufobj *bo; 1756 int i; 1757 int j; 1758 daddr_t lblkno = bp->b_lblkno; 1759 struct vnode *vp = bp->b_vp; 1760 int ncl; 1761 int nwritten; 1762 int size; 1763 int maxcl; 1764 1765 bo = &vp->v_bufobj; 1766 /* 1767 * right now we support clustered writing only to regular files. If 1768 * we find a clusterable block we could be in the middle of a cluster 1769 * rather then at the beginning. 1770 */ 1771 if ((vp->v_type == VREG) && 1772 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1773 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1774 1775 size = vp->v_mount->mnt_stat.f_iosize; 1776 maxcl = MAXPHYS / size; 1777 1778 BO_LOCK(bo); 1779 for (i = 1; i < maxcl; i++) 1780 if (vfs_bio_clcheck(vp, size, lblkno + i, 1781 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1782 break; 1783 1784 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1785 if (vfs_bio_clcheck(vp, size, lblkno - j, 1786 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1787 break; 1788 BO_UNLOCK(bo); 1789 --j; 1790 ncl = i + j; 1791 /* 1792 * this is a possible cluster write 1793 */ 1794 if (ncl != 1) { 1795 BUF_UNLOCK(bp); 1796 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl, 1797 0); 1798 return (nwritten); 1799 } 1800 } 1801 bremfree(bp); 1802 bp->b_flags |= B_ASYNC; 1803 /* 1804 * default (old) behavior, writing out only one block 1805 * 1806 * XXX returns b_bufsize instead of b_bcount for nwritten? 1807 */ 1808 nwritten = bp->b_bufsize; 1809 (void) bwrite(bp); 1810 1811 return (nwritten); 1812 } 1813 1814 /* 1815 * getnewbuf: 1816 * 1817 * Find and initialize a new buffer header, freeing up existing buffers 1818 * in the bufqueues as necessary. The new buffer is returned locked. 1819 * 1820 * Important: B_INVAL is not set. If the caller wishes to throw the 1821 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1822 * 1823 * We block if: 1824 * We have insufficient buffer headers 1825 * We have insufficient buffer space 1826 * buffer_map is too fragmented ( space reservation fails ) 1827 * If we have to flush dirty buffers ( but we try to avoid this ) 1828 * 1829 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1830 * Instead we ask the buf daemon to do it for us. We attempt to 1831 * avoid piecemeal wakeups of the pageout daemon. 1832 */ 1833 1834 static struct buf * 1835 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1836 int gbflags) 1837 { 1838 struct thread *td; 1839 struct buf *bp; 1840 struct buf *nbp; 1841 int defrag = 0; 1842 int nqindex; 1843 static int flushingbufs; 1844 1845 td = curthread; 1846 /* 1847 * We can't afford to block since we might be holding a vnode lock, 1848 * which may prevent system daemons from running. We deal with 1849 * low-memory situations by proactively returning memory and running 1850 * async I/O rather then sync I/O. 1851 */ 1852 atomic_add_int(&getnewbufcalls, 1); 1853 atomic_subtract_int(&getnewbufrestarts, 1); 1854 restart: 1855 atomic_add_int(&getnewbufrestarts, 1); 1856 1857 /* 1858 * Setup for scan. If we do not have enough free buffers, 1859 * we setup a degenerate case that immediately fails. Note 1860 * that if we are specially marked process, we are allowed to 1861 * dip into our reserves. 1862 * 1863 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1864 * 1865 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1866 * However, there are a number of cases (defragging, reusing, ...) 1867 * where we cannot backup. 1868 */ 1869 mtx_lock(&bqlock); 1870 nqindex = QUEUE_EMPTYKVA; 1871 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1872 1873 if (nbp == NULL) { 1874 /* 1875 * If no EMPTYKVA buffers and we are either 1876 * defragging or reusing, locate a CLEAN buffer 1877 * to free or reuse. If bufspace useage is low 1878 * skip this step so we can allocate a new buffer. 1879 */ 1880 if (defrag || bufspace >= lobufspace) { 1881 nqindex = QUEUE_CLEAN; 1882 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1883 } 1884 1885 /* 1886 * If we could not find or were not allowed to reuse a 1887 * CLEAN buffer, check to see if it is ok to use an EMPTY 1888 * buffer. We can only use an EMPTY buffer if allocating 1889 * its KVA would not otherwise run us out of buffer space. 1890 */ 1891 if (nbp == NULL && defrag == 0 && 1892 bufspace + maxsize < hibufspace) { 1893 nqindex = QUEUE_EMPTY; 1894 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1895 } 1896 } 1897 1898 /* 1899 * Run scan, possibly freeing data and/or kva mappings on the fly 1900 * depending. 1901 */ 1902 1903 while ((bp = nbp) != NULL) { 1904 int qindex = nqindex; 1905 1906 /* 1907 * Calculate next bp ( we can only use it if we do not block 1908 * or do other fancy things ). 1909 */ 1910 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1911 switch(qindex) { 1912 case QUEUE_EMPTY: 1913 nqindex = QUEUE_EMPTYKVA; 1914 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1915 break; 1916 /* FALLTHROUGH */ 1917 case QUEUE_EMPTYKVA: 1918 nqindex = QUEUE_CLEAN; 1919 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1920 break; 1921 /* FALLTHROUGH */ 1922 case QUEUE_CLEAN: 1923 /* 1924 * nbp is NULL. 1925 */ 1926 break; 1927 } 1928 } 1929 /* 1930 * If we are defragging then we need a buffer with 1931 * b_kvasize != 0. XXX this situation should no longer 1932 * occur, if defrag is non-zero the buffer's b_kvasize 1933 * should also be non-zero at this point. XXX 1934 */ 1935 if (defrag && bp->b_kvasize == 0) { 1936 printf("Warning: defrag empty buffer %p\n", bp); 1937 continue; 1938 } 1939 1940 /* 1941 * Start freeing the bp. This is somewhat involved. nbp 1942 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1943 */ 1944 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1945 continue; 1946 if (bp->b_vp) { 1947 BO_LOCK(bp->b_bufobj); 1948 if (bp->b_vflags & BV_BKGRDINPROG) { 1949 BO_UNLOCK(bp->b_bufobj); 1950 BUF_UNLOCK(bp); 1951 continue; 1952 } 1953 BO_UNLOCK(bp->b_bufobj); 1954 } 1955 CTR6(KTR_BUF, 1956 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1957 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1958 bp->b_kvasize, bp->b_bufsize, qindex); 1959 1960 /* 1961 * Sanity Checks 1962 */ 1963 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1964 1965 /* 1966 * Note: we no longer distinguish between VMIO and non-VMIO 1967 * buffers. 1968 */ 1969 1970 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1971 1972 if (bp->b_bufobj != NULL) 1973 BO_LOCK(bp->b_bufobj); 1974 bremfreel(bp); 1975 if (bp->b_bufobj != NULL) 1976 BO_UNLOCK(bp->b_bufobj); 1977 mtx_unlock(&bqlock); 1978 1979 if (qindex == QUEUE_CLEAN) { 1980 if (bp->b_flags & B_VMIO) { 1981 bp->b_flags &= ~B_ASYNC; 1982 vfs_vmio_release(bp); 1983 } 1984 if (bp->b_vp) 1985 brelvp(bp); 1986 } 1987 1988 /* 1989 * NOTE: nbp is now entirely invalid. We can only restart 1990 * the scan from this point on. 1991 * 1992 * Get the rest of the buffer freed up. b_kva* is still 1993 * valid after this operation. 1994 */ 1995 1996 if (bp->b_rcred != NOCRED) { 1997 crfree(bp->b_rcred); 1998 bp->b_rcred = NOCRED; 1999 } 2000 if (bp->b_wcred != NOCRED) { 2001 crfree(bp->b_wcred); 2002 bp->b_wcred = NOCRED; 2003 } 2004 if (!LIST_EMPTY(&bp->b_dep)) 2005 buf_deallocate(bp); 2006 if (bp->b_vflags & BV_BKGRDINPROG) 2007 panic("losing buffer 3"); 2008 KASSERT(bp->b_vp == NULL, 2009 ("bp: %p still has vnode %p. qindex: %d", 2010 bp, bp->b_vp, qindex)); 2011 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2012 ("bp: %p still on a buffer list. xflags %X", 2013 bp, bp->b_xflags)); 2014 2015 if (bp->b_bufsize) 2016 allocbuf(bp, 0); 2017 2018 bp->b_flags = 0; 2019 bp->b_ioflags = 0; 2020 bp->b_xflags = 0; 2021 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 2022 ("buf %p still counted as free?", bp)); 2023 bp->b_vflags = 0; 2024 bp->b_vp = NULL; 2025 bp->b_blkno = bp->b_lblkno = 0; 2026 bp->b_offset = NOOFFSET; 2027 bp->b_iodone = 0; 2028 bp->b_error = 0; 2029 bp->b_resid = 0; 2030 bp->b_bcount = 0; 2031 bp->b_npages = 0; 2032 bp->b_dirtyoff = bp->b_dirtyend = 0; 2033 bp->b_bufobj = NULL; 2034 bp->b_pin_count = 0; 2035 bp->b_fsprivate1 = NULL; 2036 bp->b_fsprivate2 = NULL; 2037 bp->b_fsprivate3 = NULL; 2038 2039 LIST_INIT(&bp->b_dep); 2040 2041 /* 2042 * If we are defragging then free the buffer. 2043 */ 2044 if (defrag) { 2045 bp->b_flags |= B_INVAL; 2046 bfreekva(bp); 2047 brelse(bp); 2048 defrag = 0; 2049 goto restart; 2050 } 2051 2052 /* 2053 * Notify any waiters for the buffer lock about 2054 * identity change by freeing the buffer. 2055 */ 2056 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2057 bp->b_flags |= B_INVAL; 2058 bfreekva(bp); 2059 brelse(bp); 2060 goto restart; 2061 } 2062 2063 /* 2064 * If we are overcomitted then recover the buffer and its 2065 * KVM space. This occurs in rare situations when multiple 2066 * processes are blocked in getnewbuf() or allocbuf(). 2067 */ 2068 if (bufspace >= hibufspace) 2069 flushingbufs = 1; 2070 if (flushingbufs && bp->b_kvasize != 0) { 2071 bp->b_flags |= B_INVAL; 2072 bfreekva(bp); 2073 brelse(bp); 2074 goto restart; 2075 } 2076 if (bufspace < lobufspace) 2077 flushingbufs = 0; 2078 break; 2079 } 2080 2081 /* 2082 * If we exhausted our list, sleep as appropriate. We may have to 2083 * wakeup various daemons and write out some dirty buffers. 2084 * 2085 * Generally we are sleeping due to insufficient buffer space. 2086 */ 2087 2088 if (bp == NULL) { 2089 int flags, norunbuf; 2090 char *waitmsg; 2091 int fl; 2092 2093 if (defrag) { 2094 flags = VFS_BIO_NEED_BUFSPACE; 2095 waitmsg = "nbufkv"; 2096 } else if (bufspace >= hibufspace) { 2097 waitmsg = "nbufbs"; 2098 flags = VFS_BIO_NEED_BUFSPACE; 2099 } else { 2100 waitmsg = "newbuf"; 2101 flags = VFS_BIO_NEED_ANY; 2102 } 2103 mtx_lock(&nblock); 2104 needsbuffer |= flags; 2105 mtx_unlock(&nblock); 2106 mtx_unlock(&bqlock); 2107 2108 bd_speedup(); /* heeeelp */ 2109 if (gbflags & GB_NOWAIT_BD) 2110 return (NULL); 2111 2112 mtx_lock(&nblock); 2113 while (needsbuffer & flags) { 2114 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2115 mtx_unlock(&nblock); 2116 /* 2117 * getblk() is called with a vnode 2118 * locked, and some majority of the 2119 * dirty buffers may as well belong to 2120 * the vnode. Flushing the buffers 2121 * there would make a progress that 2122 * cannot be achieved by the 2123 * buf_daemon, that cannot lock the 2124 * vnode. 2125 */ 2126 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2127 (td->td_pflags & TDP_NORUNNINGBUF); 2128 /* play bufdaemon */ 2129 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2130 fl = buf_do_flush(vp); 2131 td->td_pflags &= norunbuf; 2132 mtx_lock(&nblock); 2133 if (fl != 0) 2134 continue; 2135 if ((needsbuffer & flags) == 0) 2136 break; 2137 } 2138 if (msleep(&needsbuffer, &nblock, 2139 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2140 mtx_unlock(&nblock); 2141 return (NULL); 2142 } 2143 } 2144 mtx_unlock(&nblock); 2145 } else { 2146 /* 2147 * We finally have a valid bp. We aren't quite out of the 2148 * woods, we still have to reserve kva space. In order 2149 * to keep fragmentation sane we only allocate kva in 2150 * BKVASIZE chunks. 2151 */ 2152 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2153 2154 if (maxsize != bp->b_kvasize) { 2155 vm_offset_t addr = 0; 2156 int rv; 2157 2158 bfreekva(bp); 2159 2160 vm_map_lock(buffer_map); 2161 if (vm_map_findspace(buffer_map, 2162 vm_map_min(buffer_map), maxsize, &addr)) { 2163 /* 2164 * Buffer map is too fragmented. 2165 * We must defragment the map. 2166 */ 2167 atomic_add_int(&bufdefragcnt, 1); 2168 vm_map_unlock(buffer_map); 2169 defrag = 1; 2170 bp->b_flags |= B_INVAL; 2171 brelse(bp); 2172 goto restart; 2173 } 2174 rv = vm_map_insert(buffer_map, NULL, 0, addr, 2175 addr + maxsize, VM_PROT_ALL, VM_PROT_ALL, 2176 MAP_NOFAULT); 2177 KASSERT(rv == KERN_SUCCESS, 2178 ("vm_map_insert(buffer_map) rv %d", rv)); 2179 vm_map_unlock(buffer_map); 2180 bp->b_kvabase = (caddr_t)addr; 2181 bp->b_kvasize = maxsize; 2182 atomic_add_long(&bufspace, bp->b_kvasize); 2183 atomic_add_int(&bufreusecnt, 1); 2184 } 2185 bp->b_saveaddr = bp->b_kvabase; 2186 bp->b_data = bp->b_saveaddr; 2187 } 2188 return (bp); 2189 } 2190 2191 /* 2192 * buf_daemon: 2193 * 2194 * buffer flushing daemon. Buffers are normally flushed by the 2195 * update daemon but if it cannot keep up this process starts to 2196 * take the load in an attempt to prevent getnewbuf() from blocking. 2197 */ 2198 2199 static struct kproc_desc buf_kp = { 2200 "bufdaemon", 2201 buf_daemon, 2202 &bufdaemonproc 2203 }; 2204 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2205 2206 static int 2207 buf_do_flush(struct vnode *vp) 2208 { 2209 int flushed; 2210 2211 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2212 if (flushed == 0) { 2213 /* 2214 * Could not find any buffers without rollback 2215 * dependencies, so just write the first one 2216 * in the hopes of eventually making progress. 2217 */ 2218 flushbufqueues(vp, QUEUE_DIRTY, 1); 2219 } 2220 return (flushed); 2221 } 2222 2223 static void 2224 buf_daemon() 2225 { 2226 int lodirtysave; 2227 2228 /* 2229 * This process needs to be suspended prior to shutdown sync. 2230 */ 2231 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2232 SHUTDOWN_PRI_LAST); 2233 2234 /* 2235 * This process is allowed to take the buffer cache to the limit 2236 */ 2237 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2238 mtx_lock(&bdlock); 2239 for (;;) { 2240 bd_request = 0; 2241 mtx_unlock(&bdlock); 2242 2243 kproc_suspend_check(bufdaemonproc); 2244 lodirtysave = lodirtybuffers; 2245 if (bd_speedupreq) { 2246 lodirtybuffers = numdirtybuffers / 2; 2247 bd_speedupreq = 0; 2248 } 2249 /* 2250 * Do the flush. Limit the amount of in-transit I/O we 2251 * allow to build up, otherwise we would completely saturate 2252 * the I/O system. Wakeup any waiting processes before we 2253 * normally would so they can run in parallel with our drain. 2254 */ 2255 while (numdirtybuffers > lodirtybuffers) { 2256 if (buf_do_flush(NULL) == 0) 2257 break; 2258 kern_yield(PRI_USER); 2259 } 2260 lodirtybuffers = lodirtysave; 2261 2262 /* 2263 * Only clear bd_request if we have reached our low water 2264 * mark. The buf_daemon normally waits 1 second and 2265 * then incrementally flushes any dirty buffers that have 2266 * built up, within reason. 2267 * 2268 * If we were unable to hit our low water mark and couldn't 2269 * find any flushable buffers, we sleep half a second. 2270 * Otherwise we loop immediately. 2271 */ 2272 mtx_lock(&bdlock); 2273 if (numdirtybuffers <= lodirtybuffers) { 2274 /* 2275 * We reached our low water mark, reset the 2276 * request and sleep until we are needed again. 2277 * The sleep is just so the suspend code works. 2278 */ 2279 bd_request = 0; 2280 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2281 } else { 2282 /* 2283 * We couldn't find any flushable dirty buffers but 2284 * still have too many dirty buffers, we 2285 * have to sleep and try again. (rare) 2286 */ 2287 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2288 } 2289 } 2290 } 2291 2292 /* 2293 * flushbufqueues: 2294 * 2295 * Try to flush a buffer in the dirty queue. We must be careful to 2296 * free up B_INVAL buffers instead of write them, which NFS is 2297 * particularly sensitive to. 2298 */ 2299 static int flushwithdeps = 0; 2300 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2301 0, "Number of buffers flushed with dependecies that require rollbacks"); 2302 2303 static int 2304 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2305 { 2306 struct buf *sentinel; 2307 struct vnode *vp; 2308 struct mount *mp; 2309 struct buf *bp; 2310 int hasdeps; 2311 int flushed; 2312 int target; 2313 2314 if (lvp == NULL) { 2315 target = numdirtybuffers - lodirtybuffers; 2316 if (flushdeps && target > 2) 2317 target /= 2; 2318 } else 2319 target = flushbufqtarget; 2320 flushed = 0; 2321 bp = NULL; 2322 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2323 sentinel->b_qindex = QUEUE_SENTINEL; 2324 mtx_lock(&bqlock); 2325 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2326 while (flushed != target) { 2327 bp = TAILQ_NEXT(sentinel, b_freelist); 2328 if (bp != NULL) { 2329 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2330 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2331 b_freelist); 2332 } else 2333 break; 2334 /* 2335 * Skip sentinels inserted by other invocations of the 2336 * flushbufqueues(), taking care to not reorder them. 2337 */ 2338 if (bp->b_qindex == QUEUE_SENTINEL) 2339 continue; 2340 /* 2341 * Only flush the buffers that belong to the 2342 * vnode locked by the curthread. 2343 */ 2344 if (lvp != NULL && bp->b_vp != lvp) 2345 continue; 2346 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2347 continue; 2348 if (bp->b_pin_count > 0) { 2349 BUF_UNLOCK(bp); 2350 continue; 2351 } 2352 BO_LOCK(bp->b_bufobj); 2353 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2354 (bp->b_flags & B_DELWRI) == 0) { 2355 BO_UNLOCK(bp->b_bufobj); 2356 BUF_UNLOCK(bp); 2357 continue; 2358 } 2359 BO_UNLOCK(bp->b_bufobj); 2360 if (bp->b_flags & B_INVAL) { 2361 bremfreel(bp); 2362 mtx_unlock(&bqlock); 2363 brelse(bp); 2364 flushed++; 2365 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2366 mtx_lock(&bqlock); 2367 continue; 2368 } 2369 2370 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2371 if (flushdeps == 0) { 2372 BUF_UNLOCK(bp); 2373 continue; 2374 } 2375 hasdeps = 1; 2376 } else 2377 hasdeps = 0; 2378 /* 2379 * We must hold the lock on a vnode before writing 2380 * one of its buffers. Otherwise we may confuse, or 2381 * in the case of a snapshot vnode, deadlock the 2382 * system. 2383 * 2384 * The lock order here is the reverse of the normal 2385 * of vnode followed by buf lock. This is ok because 2386 * the NOWAIT will prevent deadlock. 2387 */ 2388 vp = bp->b_vp; 2389 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2390 BUF_UNLOCK(bp); 2391 continue; 2392 } 2393 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2394 mtx_unlock(&bqlock); 2395 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2396 bp, bp->b_vp, bp->b_flags); 2397 if (curproc == bufdaemonproc) 2398 vfs_bio_awrite(bp); 2399 else { 2400 bremfree(bp); 2401 bwrite(bp); 2402 notbufdflashes++; 2403 } 2404 vn_finished_write(mp); 2405 VOP_UNLOCK(vp, 0); 2406 flushwithdeps += hasdeps; 2407 flushed++; 2408 2409 /* 2410 * Sleeping on runningbufspace while holding 2411 * vnode lock leads to deadlock. 2412 */ 2413 if (curproc == bufdaemonproc) 2414 waitrunningbufspace(); 2415 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2416 mtx_lock(&bqlock); 2417 continue; 2418 } 2419 vn_finished_write(mp); 2420 BUF_UNLOCK(bp); 2421 } 2422 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2423 mtx_unlock(&bqlock); 2424 free(sentinel, M_TEMP); 2425 return (flushed); 2426 } 2427 2428 /* 2429 * Check to see if a block is currently memory resident. 2430 */ 2431 struct buf * 2432 incore(struct bufobj *bo, daddr_t blkno) 2433 { 2434 struct buf *bp; 2435 2436 BO_LOCK(bo); 2437 bp = gbincore(bo, blkno); 2438 BO_UNLOCK(bo); 2439 return (bp); 2440 } 2441 2442 /* 2443 * Returns true if no I/O is needed to access the 2444 * associated VM object. This is like incore except 2445 * it also hunts around in the VM system for the data. 2446 */ 2447 2448 static int 2449 inmem(struct vnode * vp, daddr_t blkno) 2450 { 2451 vm_object_t obj; 2452 vm_offset_t toff, tinc, size; 2453 vm_page_t m; 2454 vm_ooffset_t off; 2455 2456 ASSERT_VOP_LOCKED(vp, "inmem"); 2457 2458 if (incore(&vp->v_bufobj, blkno)) 2459 return 1; 2460 if (vp->v_mount == NULL) 2461 return 0; 2462 obj = vp->v_object; 2463 if (obj == NULL) 2464 return (0); 2465 2466 size = PAGE_SIZE; 2467 if (size > vp->v_mount->mnt_stat.f_iosize) 2468 size = vp->v_mount->mnt_stat.f_iosize; 2469 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2470 2471 VM_OBJECT_WLOCK(obj); 2472 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2473 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2474 if (!m) 2475 goto notinmem; 2476 tinc = size; 2477 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2478 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2479 if (vm_page_is_valid(m, 2480 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2481 goto notinmem; 2482 } 2483 VM_OBJECT_WUNLOCK(obj); 2484 return 1; 2485 2486 notinmem: 2487 VM_OBJECT_WUNLOCK(obj); 2488 return (0); 2489 } 2490 2491 /* 2492 * Set the dirty range for a buffer based on the status of the dirty 2493 * bits in the pages comprising the buffer. The range is limited 2494 * to the size of the buffer. 2495 * 2496 * Tell the VM system that the pages associated with this buffer 2497 * are clean. This is used for delayed writes where the data is 2498 * going to go to disk eventually without additional VM intevention. 2499 * 2500 * Note that while we only really need to clean through to b_bcount, we 2501 * just go ahead and clean through to b_bufsize. 2502 */ 2503 static void 2504 vfs_clean_pages_dirty_buf(struct buf *bp) 2505 { 2506 vm_ooffset_t foff, noff, eoff; 2507 vm_page_t m; 2508 int i; 2509 2510 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2511 return; 2512 2513 foff = bp->b_offset; 2514 KASSERT(bp->b_offset != NOOFFSET, 2515 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2516 2517 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 2518 vfs_drain_busy_pages(bp); 2519 vfs_setdirty_locked_object(bp); 2520 for (i = 0; i < bp->b_npages; i++) { 2521 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2522 eoff = noff; 2523 if (eoff > bp->b_offset + bp->b_bufsize) 2524 eoff = bp->b_offset + bp->b_bufsize; 2525 m = bp->b_pages[i]; 2526 vfs_page_set_validclean(bp, foff, m); 2527 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2528 foff = noff; 2529 } 2530 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 2531 } 2532 2533 static void 2534 vfs_setdirty_locked_object(struct buf *bp) 2535 { 2536 vm_object_t object; 2537 int i; 2538 2539 object = bp->b_bufobj->bo_object; 2540 VM_OBJECT_ASSERT_WLOCKED(object); 2541 2542 /* 2543 * We qualify the scan for modified pages on whether the 2544 * object has been flushed yet. 2545 */ 2546 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2547 vm_offset_t boffset; 2548 vm_offset_t eoffset; 2549 2550 /* 2551 * test the pages to see if they have been modified directly 2552 * by users through the VM system. 2553 */ 2554 for (i = 0; i < bp->b_npages; i++) 2555 vm_page_test_dirty(bp->b_pages[i]); 2556 2557 /* 2558 * Calculate the encompassing dirty range, boffset and eoffset, 2559 * (eoffset - boffset) bytes. 2560 */ 2561 2562 for (i = 0; i < bp->b_npages; i++) { 2563 if (bp->b_pages[i]->dirty) 2564 break; 2565 } 2566 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2567 2568 for (i = bp->b_npages - 1; i >= 0; --i) { 2569 if (bp->b_pages[i]->dirty) { 2570 break; 2571 } 2572 } 2573 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2574 2575 /* 2576 * Fit it to the buffer. 2577 */ 2578 2579 if (eoffset > bp->b_bcount) 2580 eoffset = bp->b_bcount; 2581 2582 /* 2583 * If we have a good dirty range, merge with the existing 2584 * dirty range. 2585 */ 2586 2587 if (boffset < eoffset) { 2588 if (bp->b_dirtyoff > boffset) 2589 bp->b_dirtyoff = boffset; 2590 if (bp->b_dirtyend < eoffset) 2591 bp->b_dirtyend = eoffset; 2592 } 2593 } 2594 } 2595 2596 /* 2597 * getblk: 2598 * 2599 * Get a block given a specified block and offset into a file/device. 2600 * The buffers B_DONE bit will be cleared on return, making it almost 2601 * ready for an I/O initiation. B_INVAL may or may not be set on 2602 * return. The caller should clear B_INVAL prior to initiating a 2603 * READ. 2604 * 2605 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2606 * an existing buffer. 2607 * 2608 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2609 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2610 * and then cleared based on the backing VM. If the previous buffer is 2611 * non-0-sized but invalid, B_CACHE will be cleared. 2612 * 2613 * If getblk() must create a new buffer, the new buffer is returned with 2614 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2615 * case it is returned with B_INVAL clear and B_CACHE set based on the 2616 * backing VM. 2617 * 2618 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2619 * B_CACHE bit is clear. 2620 * 2621 * What this means, basically, is that the caller should use B_CACHE to 2622 * determine whether the buffer is fully valid or not and should clear 2623 * B_INVAL prior to issuing a read. If the caller intends to validate 2624 * the buffer by loading its data area with something, the caller needs 2625 * to clear B_INVAL. If the caller does this without issuing an I/O, 2626 * the caller should set B_CACHE ( as an optimization ), else the caller 2627 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2628 * a write attempt or if it was a successfull read. If the caller 2629 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2630 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2631 */ 2632 struct buf * 2633 getblk(struct vnode *vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2634 int flags) 2635 { 2636 struct buf *bp; 2637 struct bufobj *bo; 2638 int error; 2639 2640 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2641 ASSERT_VOP_LOCKED(vp, "getblk"); 2642 if (size > MAXBSIZE) 2643 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2644 2645 bo = &vp->v_bufobj; 2646 loop: 2647 /* 2648 * Block if we are low on buffers. Certain processes are allowed 2649 * to completely exhaust the buffer cache. 2650 * 2651 * If this check ever becomes a bottleneck it may be better to 2652 * move it into the else, when gbincore() fails. At the moment 2653 * it isn't a problem. 2654 */ 2655 if (numfreebuffers == 0) { 2656 if (TD_IS_IDLETHREAD(curthread)) 2657 return NULL; 2658 mtx_lock(&nblock); 2659 needsbuffer |= VFS_BIO_NEED_ANY; 2660 mtx_unlock(&nblock); 2661 } 2662 2663 BO_LOCK(bo); 2664 bp = gbincore(bo, blkno); 2665 if (bp != NULL) { 2666 int lockflags; 2667 /* 2668 * Buffer is in-core. If the buffer is not busy nor managed, 2669 * it must be on a queue. 2670 */ 2671 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2672 2673 if (flags & GB_LOCK_NOWAIT) 2674 lockflags |= LK_NOWAIT; 2675 2676 error = BUF_TIMELOCK(bp, lockflags, 2677 BO_MTX(bo), "getblk", slpflag, slptimeo); 2678 2679 /* 2680 * If we slept and got the lock we have to restart in case 2681 * the buffer changed identities. 2682 */ 2683 if (error == ENOLCK) 2684 goto loop; 2685 /* We timed out or were interrupted. */ 2686 else if (error) 2687 return (NULL); 2688 /* If recursed, assume caller knows the rules. */ 2689 else if (BUF_LOCKRECURSED(bp)) 2690 goto end; 2691 2692 /* 2693 * The buffer is locked. B_CACHE is cleared if the buffer is 2694 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2695 * and for a VMIO buffer B_CACHE is adjusted according to the 2696 * backing VM cache. 2697 */ 2698 if (bp->b_flags & B_INVAL) 2699 bp->b_flags &= ~B_CACHE; 2700 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2701 bp->b_flags |= B_CACHE; 2702 if (bp->b_flags & B_MANAGED) 2703 MPASS(bp->b_qindex == QUEUE_NONE); 2704 else { 2705 BO_LOCK(bo); 2706 bremfree(bp); 2707 BO_UNLOCK(bo); 2708 } 2709 2710 /* 2711 * check for size inconsistencies for non-VMIO case. 2712 */ 2713 if (bp->b_bcount != size) { 2714 if ((bp->b_flags & B_VMIO) == 0 || 2715 (size > bp->b_kvasize)) { 2716 if (bp->b_flags & B_DELWRI) { 2717 /* 2718 * If buffer is pinned and caller does 2719 * not want sleep waiting for it to be 2720 * unpinned, bail out 2721 * */ 2722 if (bp->b_pin_count > 0) { 2723 if (flags & GB_LOCK_NOWAIT) { 2724 bqrelse(bp); 2725 return (NULL); 2726 } else { 2727 bunpin_wait(bp); 2728 } 2729 } 2730 bp->b_flags |= B_NOCACHE; 2731 bwrite(bp); 2732 } else { 2733 if (LIST_EMPTY(&bp->b_dep)) { 2734 bp->b_flags |= B_RELBUF; 2735 brelse(bp); 2736 } else { 2737 bp->b_flags |= B_NOCACHE; 2738 bwrite(bp); 2739 } 2740 } 2741 goto loop; 2742 } 2743 } 2744 2745 /* 2746 * If the size is inconsistant in the VMIO case, we can resize 2747 * the buffer. This might lead to B_CACHE getting set or 2748 * cleared. If the size has not changed, B_CACHE remains 2749 * unchanged from its previous state. 2750 */ 2751 2752 if (bp->b_bcount != size) 2753 allocbuf(bp, size); 2754 2755 KASSERT(bp->b_offset != NOOFFSET, 2756 ("getblk: no buffer offset")); 2757 2758 /* 2759 * A buffer with B_DELWRI set and B_CACHE clear must 2760 * be committed before we can return the buffer in 2761 * order to prevent the caller from issuing a read 2762 * ( due to B_CACHE not being set ) and overwriting 2763 * it. 2764 * 2765 * Most callers, including NFS and FFS, need this to 2766 * operate properly either because they assume they 2767 * can issue a read if B_CACHE is not set, or because 2768 * ( for example ) an uncached B_DELWRI might loop due 2769 * to softupdates re-dirtying the buffer. In the latter 2770 * case, B_CACHE is set after the first write completes, 2771 * preventing further loops. 2772 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2773 * above while extending the buffer, we cannot allow the 2774 * buffer to remain with B_CACHE set after the write 2775 * completes or it will represent a corrupt state. To 2776 * deal with this we set B_NOCACHE to scrap the buffer 2777 * after the write. 2778 * 2779 * We might be able to do something fancy, like setting 2780 * B_CACHE in bwrite() except if B_DELWRI is already set, 2781 * so the below call doesn't set B_CACHE, but that gets real 2782 * confusing. This is much easier. 2783 */ 2784 2785 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2786 bp->b_flags |= B_NOCACHE; 2787 bwrite(bp); 2788 goto loop; 2789 } 2790 bp->b_flags &= ~B_DONE; 2791 } else { 2792 int bsize, maxsize, vmio; 2793 off_t offset; 2794 2795 /* 2796 * Buffer is not in-core, create new buffer. The buffer 2797 * returned by getnewbuf() is locked. Note that the returned 2798 * buffer is also considered valid (not marked B_INVAL). 2799 */ 2800 BO_UNLOCK(bo); 2801 /* 2802 * If the user does not want us to create the buffer, bail out 2803 * here. 2804 */ 2805 if (flags & GB_NOCREAT) 2806 return NULL; 2807 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 2808 offset = blkno * bsize; 2809 vmio = vp->v_object != NULL; 2810 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2811 maxsize = imax(maxsize, bsize); 2812 2813 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2814 if (bp == NULL) { 2815 if (slpflag || slptimeo) 2816 return NULL; 2817 goto loop; 2818 } 2819 2820 /* 2821 * This code is used to make sure that a buffer is not 2822 * created while the getnewbuf routine is blocked. 2823 * This can be a problem whether the vnode is locked or not. 2824 * If the buffer is created out from under us, we have to 2825 * throw away the one we just created. 2826 * 2827 * Note: this must occur before we associate the buffer 2828 * with the vp especially considering limitations in 2829 * the splay tree implementation when dealing with duplicate 2830 * lblkno's. 2831 */ 2832 BO_LOCK(bo); 2833 if (gbincore(bo, blkno)) { 2834 BO_UNLOCK(bo); 2835 bp->b_flags |= B_INVAL; 2836 brelse(bp); 2837 goto loop; 2838 } 2839 2840 /* 2841 * Insert the buffer into the hash, so that it can 2842 * be found by incore. 2843 */ 2844 bp->b_blkno = bp->b_lblkno = blkno; 2845 bp->b_offset = offset; 2846 bgetvp(vp, bp); 2847 BO_UNLOCK(bo); 2848 2849 /* 2850 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2851 * buffer size starts out as 0, B_CACHE will be set by 2852 * allocbuf() for the VMIO case prior to it testing the 2853 * backing store for validity. 2854 */ 2855 2856 if (vmio) { 2857 bp->b_flags |= B_VMIO; 2858 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2859 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2860 bp, vp->v_object, bp->b_bufobj->bo_object)); 2861 } else { 2862 bp->b_flags &= ~B_VMIO; 2863 KASSERT(bp->b_bufobj->bo_object == NULL, 2864 ("ARGH! has b_bufobj->bo_object %p %p\n", 2865 bp, bp->b_bufobj->bo_object)); 2866 } 2867 2868 allocbuf(bp, size); 2869 bp->b_flags &= ~B_DONE; 2870 } 2871 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2872 BUF_ASSERT_HELD(bp); 2873 end: 2874 KASSERT(bp->b_bufobj == bo, 2875 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2876 return (bp); 2877 } 2878 2879 /* 2880 * Get an empty, disassociated buffer of given size. The buffer is initially 2881 * set to B_INVAL. 2882 */ 2883 struct buf * 2884 geteblk(int size, int flags) 2885 { 2886 struct buf *bp; 2887 int maxsize; 2888 2889 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2890 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2891 if ((flags & GB_NOWAIT_BD) && 2892 (curthread->td_pflags & TDP_BUFNEED) != 0) 2893 return (NULL); 2894 } 2895 allocbuf(bp, size); 2896 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2897 BUF_ASSERT_HELD(bp); 2898 return (bp); 2899 } 2900 2901 2902 /* 2903 * This code constitutes the buffer memory from either anonymous system 2904 * memory (in the case of non-VMIO operations) or from an associated 2905 * VM object (in the case of VMIO operations). This code is able to 2906 * resize a buffer up or down. 2907 * 2908 * Note that this code is tricky, and has many complications to resolve 2909 * deadlock or inconsistant data situations. Tread lightly!!! 2910 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2911 * the caller. Calling this code willy nilly can result in the loss of data. 2912 * 2913 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2914 * B_CACHE for the non-VMIO case. 2915 */ 2916 2917 int 2918 allocbuf(struct buf *bp, int size) 2919 { 2920 int newbsize, mbsize; 2921 int i; 2922 2923 BUF_ASSERT_HELD(bp); 2924 2925 if (bp->b_kvasize < size) 2926 panic("allocbuf: buffer too small"); 2927 2928 if ((bp->b_flags & B_VMIO) == 0) { 2929 caddr_t origbuf; 2930 int origbufsize; 2931 /* 2932 * Just get anonymous memory from the kernel. Don't 2933 * mess with B_CACHE. 2934 */ 2935 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2936 if (bp->b_flags & B_MALLOC) 2937 newbsize = mbsize; 2938 else 2939 newbsize = round_page(size); 2940 2941 if (newbsize < bp->b_bufsize) { 2942 /* 2943 * malloced buffers are not shrunk 2944 */ 2945 if (bp->b_flags & B_MALLOC) { 2946 if (newbsize) { 2947 bp->b_bcount = size; 2948 } else { 2949 free(bp->b_data, M_BIOBUF); 2950 if (bp->b_bufsize) { 2951 atomic_subtract_long( 2952 &bufmallocspace, 2953 bp->b_bufsize); 2954 bufspacewakeup(); 2955 bp->b_bufsize = 0; 2956 } 2957 bp->b_saveaddr = bp->b_kvabase; 2958 bp->b_data = bp->b_saveaddr; 2959 bp->b_bcount = 0; 2960 bp->b_flags &= ~B_MALLOC; 2961 } 2962 return 1; 2963 } 2964 vm_hold_free_pages(bp, newbsize); 2965 } else if (newbsize > bp->b_bufsize) { 2966 /* 2967 * We only use malloced memory on the first allocation. 2968 * and revert to page-allocated memory when the buffer 2969 * grows. 2970 */ 2971 /* 2972 * There is a potential smp race here that could lead 2973 * to bufmallocspace slightly passing the max. It 2974 * is probably extremely rare and not worth worrying 2975 * over. 2976 */ 2977 if ( (bufmallocspace < maxbufmallocspace) && 2978 (bp->b_bufsize == 0) && 2979 (mbsize <= PAGE_SIZE/2)) { 2980 2981 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2982 bp->b_bufsize = mbsize; 2983 bp->b_bcount = size; 2984 bp->b_flags |= B_MALLOC; 2985 atomic_add_long(&bufmallocspace, mbsize); 2986 return 1; 2987 } 2988 origbuf = NULL; 2989 origbufsize = 0; 2990 /* 2991 * If the buffer is growing on its other-than-first allocation, 2992 * then we revert to the page-allocation scheme. 2993 */ 2994 if (bp->b_flags & B_MALLOC) { 2995 origbuf = bp->b_data; 2996 origbufsize = bp->b_bufsize; 2997 bp->b_data = bp->b_kvabase; 2998 if (bp->b_bufsize) { 2999 atomic_subtract_long(&bufmallocspace, 3000 bp->b_bufsize); 3001 bufspacewakeup(); 3002 bp->b_bufsize = 0; 3003 } 3004 bp->b_flags &= ~B_MALLOC; 3005 newbsize = round_page(newbsize); 3006 } 3007 vm_hold_load_pages( 3008 bp, 3009 (vm_offset_t) bp->b_data + bp->b_bufsize, 3010 (vm_offset_t) bp->b_data + newbsize); 3011 if (origbuf) { 3012 bcopy(origbuf, bp->b_data, origbufsize); 3013 free(origbuf, M_BIOBUF); 3014 } 3015 } 3016 } else { 3017 int desiredpages; 3018 3019 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3020 desiredpages = (size == 0) ? 0 : 3021 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3022 3023 if (bp->b_flags & B_MALLOC) 3024 panic("allocbuf: VMIO buffer can't be malloced"); 3025 /* 3026 * Set B_CACHE initially if buffer is 0 length or will become 3027 * 0-length. 3028 */ 3029 if (size == 0 || bp->b_bufsize == 0) 3030 bp->b_flags |= B_CACHE; 3031 3032 if (newbsize < bp->b_bufsize) { 3033 /* 3034 * DEV_BSIZE aligned new buffer size is less then the 3035 * DEV_BSIZE aligned existing buffer size. Figure out 3036 * if we have to remove any pages. 3037 */ 3038 if (desiredpages < bp->b_npages) { 3039 vm_page_t m; 3040 3041 pmap_qremove((vm_offset_t)trunc_page( 3042 (vm_offset_t)bp->b_data) + 3043 (desiredpages << PAGE_SHIFT), 3044 (bp->b_npages - desiredpages)); 3045 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3046 for (i = desiredpages; i < bp->b_npages; i++) { 3047 /* 3048 * the page is not freed here -- it 3049 * is the responsibility of 3050 * vnode_pager_setsize 3051 */ 3052 m = bp->b_pages[i]; 3053 KASSERT(m != bogus_page, 3054 ("allocbuf: bogus page found")); 3055 while (vm_page_sleep_if_busy(m, TRUE, 3056 "biodep")) 3057 continue; 3058 3059 bp->b_pages[i] = NULL; 3060 vm_page_lock(m); 3061 vm_page_unwire(m, 0); 3062 vm_page_unlock(m); 3063 } 3064 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3065 bp->b_npages = desiredpages; 3066 } 3067 } else if (size > bp->b_bcount) { 3068 /* 3069 * We are growing the buffer, possibly in a 3070 * byte-granular fashion. 3071 */ 3072 vm_object_t obj; 3073 vm_offset_t toff; 3074 vm_offset_t tinc; 3075 3076 /* 3077 * Step 1, bring in the VM pages from the object, 3078 * allocating them if necessary. We must clear 3079 * B_CACHE if these pages are not valid for the 3080 * range covered by the buffer. 3081 */ 3082 3083 obj = bp->b_bufobj->bo_object; 3084 3085 VM_OBJECT_WLOCK(obj); 3086 while (bp->b_npages < desiredpages) { 3087 vm_page_t m; 3088 3089 /* 3090 * We must allocate system pages since blocking 3091 * here could interfere with paging I/O, no 3092 * matter which process we are. 3093 * 3094 * We can only test VPO_BUSY here. Blocking on 3095 * m->busy might lead to a deadlock: 3096 * vm_fault->getpages->cluster_read->allocbuf 3097 * Thus, we specify VM_ALLOC_IGN_SBUSY. 3098 */ 3099 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3100 bp->b_npages, VM_ALLOC_NOBUSY | 3101 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3102 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | 3103 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3104 if (m->valid == 0) 3105 bp->b_flags &= ~B_CACHE; 3106 bp->b_pages[bp->b_npages] = m; 3107 ++bp->b_npages; 3108 } 3109 3110 /* 3111 * Step 2. We've loaded the pages into the buffer, 3112 * we have to figure out if we can still have B_CACHE 3113 * set. Note that B_CACHE is set according to the 3114 * byte-granular range ( bcount and size ), new the 3115 * aligned range ( newbsize ). 3116 * 3117 * The VM test is against m->valid, which is DEV_BSIZE 3118 * aligned. Needless to say, the validity of the data 3119 * needs to also be DEV_BSIZE aligned. Note that this 3120 * fails with NFS if the server or some other client 3121 * extends the file's EOF. If our buffer is resized, 3122 * B_CACHE may remain set! XXX 3123 */ 3124 3125 toff = bp->b_bcount; 3126 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3127 3128 while ((bp->b_flags & B_CACHE) && toff < size) { 3129 vm_pindex_t pi; 3130 3131 if (tinc > (size - toff)) 3132 tinc = size - toff; 3133 3134 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3135 PAGE_SHIFT; 3136 3137 vfs_buf_test_cache( 3138 bp, 3139 bp->b_offset, 3140 toff, 3141 tinc, 3142 bp->b_pages[pi] 3143 ); 3144 toff += tinc; 3145 tinc = PAGE_SIZE; 3146 } 3147 VM_OBJECT_WUNLOCK(obj); 3148 3149 /* 3150 * Step 3, fixup the KVM pmap. Remember that 3151 * bp->b_data is relative to bp->b_offset, but 3152 * bp->b_offset may be offset into the first page. 3153 */ 3154 3155 bp->b_data = (caddr_t) 3156 trunc_page((vm_offset_t)bp->b_data); 3157 pmap_qenter( 3158 (vm_offset_t)bp->b_data, 3159 bp->b_pages, 3160 bp->b_npages 3161 ); 3162 3163 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3164 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3165 } 3166 } 3167 if (newbsize < bp->b_bufsize) 3168 bufspacewakeup(); 3169 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3170 bp->b_bcount = size; /* requested buffer size */ 3171 return 1; 3172 } 3173 3174 void 3175 biodone(struct bio *bp) 3176 { 3177 struct mtx *mtxp; 3178 void (*done)(struct bio *); 3179 3180 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3181 mtx_lock(mtxp); 3182 bp->bio_flags |= BIO_DONE; 3183 done = bp->bio_done; 3184 if (done == NULL) 3185 wakeup(bp); 3186 mtx_unlock(mtxp); 3187 if (done != NULL) 3188 done(bp); 3189 } 3190 3191 /* 3192 * Wait for a BIO to finish. 3193 * 3194 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3195 * case is not yet clear. 3196 */ 3197 int 3198 biowait(struct bio *bp, const char *wchan) 3199 { 3200 struct mtx *mtxp; 3201 3202 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3203 mtx_lock(mtxp); 3204 while ((bp->bio_flags & BIO_DONE) == 0) 3205 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3206 mtx_unlock(mtxp); 3207 if (bp->bio_error != 0) 3208 return (bp->bio_error); 3209 if (!(bp->bio_flags & BIO_ERROR)) 3210 return (0); 3211 return (EIO); 3212 } 3213 3214 void 3215 biofinish(struct bio *bp, struct devstat *stat, int error) 3216 { 3217 3218 if (error) { 3219 bp->bio_error = error; 3220 bp->bio_flags |= BIO_ERROR; 3221 } 3222 if (stat != NULL) 3223 devstat_end_transaction_bio(stat, bp); 3224 biodone(bp); 3225 } 3226 3227 /* 3228 * bufwait: 3229 * 3230 * Wait for buffer I/O completion, returning error status. The buffer 3231 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3232 * error and cleared. 3233 */ 3234 int 3235 bufwait(struct buf *bp) 3236 { 3237 if (bp->b_iocmd == BIO_READ) 3238 bwait(bp, PRIBIO, "biord"); 3239 else 3240 bwait(bp, PRIBIO, "biowr"); 3241 if (bp->b_flags & B_EINTR) { 3242 bp->b_flags &= ~B_EINTR; 3243 return (EINTR); 3244 } 3245 if (bp->b_ioflags & BIO_ERROR) { 3246 return (bp->b_error ? bp->b_error : EIO); 3247 } else { 3248 return (0); 3249 } 3250 } 3251 3252 /* 3253 * Call back function from struct bio back up to struct buf. 3254 */ 3255 static void 3256 bufdonebio(struct bio *bip) 3257 { 3258 struct buf *bp; 3259 3260 bp = bip->bio_caller2; 3261 bp->b_resid = bp->b_bcount - bip->bio_completed; 3262 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3263 bp->b_ioflags = bip->bio_flags; 3264 bp->b_error = bip->bio_error; 3265 if (bp->b_error) 3266 bp->b_ioflags |= BIO_ERROR; 3267 bufdone(bp); 3268 g_destroy_bio(bip); 3269 } 3270 3271 void 3272 dev_strategy(struct cdev *dev, struct buf *bp) 3273 { 3274 struct cdevsw *csw; 3275 struct bio *bip; 3276 int ref; 3277 3278 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3279 panic("b_iocmd botch"); 3280 for (;;) { 3281 bip = g_new_bio(); 3282 if (bip != NULL) 3283 break; 3284 /* Try again later */ 3285 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3286 } 3287 bip->bio_cmd = bp->b_iocmd; 3288 bip->bio_offset = bp->b_iooffset; 3289 bip->bio_length = bp->b_bcount; 3290 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3291 bip->bio_data = bp->b_data; 3292 bip->bio_done = bufdonebio; 3293 bip->bio_caller2 = bp; 3294 bip->bio_dev = dev; 3295 KASSERT(dev->si_refcount > 0, 3296 ("dev_strategy on un-referenced struct cdev *(%s)", 3297 devtoname(dev))); 3298 csw = dev_refthread(dev, &ref); 3299 if (csw == NULL) { 3300 g_destroy_bio(bip); 3301 bp->b_error = ENXIO; 3302 bp->b_ioflags = BIO_ERROR; 3303 bufdone(bp); 3304 return; 3305 } 3306 (*csw->d_strategy)(bip); 3307 dev_relthread(dev, ref); 3308 } 3309 3310 /* 3311 * bufdone: 3312 * 3313 * Finish I/O on a buffer, optionally calling a completion function. 3314 * This is usually called from an interrupt so process blocking is 3315 * not allowed. 3316 * 3317 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3318 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3319 * assuming B_INVAL is clear. 3320 * 3321 * For the VMIO case, we set B_CACHE if the op was a read and no 3322 * read error occured, or if the op was a write. B_CACHE is never 3323 * set if the buffer is invalid or otherwise uncacheable. 3324 * 3325 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3326 * initiator to leave B_INVAL set to brelse the buffer out of existance 3327 * in the biodone routine. 3328 */ 3329 void 3330 bufdone(struct buf *bp) 3331 { 3332 struct bufobj *dropobj; 3333 void (*biodone)(struct buf *); 3334 3335 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3336 dropobj = NULL; 3337 3338 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3339 BUF_ASSERT_HELD(bp); 3340 3341 runningbufwakeup(bp); 3342 if (bp->b_iocmd == BIO_WRITE) 3343 dropobj = bp->b_bufobj; 3344 /* call optional completion function if requested */ 3345 if (bp->b_iodone != NULL) { 3346 biodone = bp->b_iodone; 3347 bp->b_iodone = NULL; 3348 (*biodone) (bp); 3349 if (dropobj) 3350 bufobj_wdrop(dropobj); 3351 return; 3352 } 3353 3354 bufdone_finish(bp); 3355 3356 if (dropobj) 3357 bufobj_wdrop(dropobj); 3358 } 3359 3360 void 3361 bufdone_finish(struct buf *bp) 3362 { 3363 BUF_ASSERT_HELD(bp); 3364 3365 if (!LIST_EMPTY(&bp->b_dep)) 3366 buf_complete(bp); 3367 3368 if (bp->b_flags & B_VMIO) { 3369 vm_ooffset_t foff; 3370 vm_page_t m; 3371 vm_object_t obj; 3372 struct vnode *vp; 3373 int bogus, i, iosize; 3374 3375 obj = bp->b_bufobj->bo_object; 3376 KASSERT(obj->paging_in_progress >= bp->b_npages, 3377 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3378 obj->paging_in_progress, bp->b_npages)); 3379 3380 vp = bp->b_vp; 3381 KASSERT(vp->v_holdcnt > 0, 3382 ("biodone_finish: vnode %p has zero hold count", vp)); 3383 KASSERT(vp->v_object != NULL, 3384 ("biodone_finish: vnode %p has no vm_object", vp)); 3385 3386 foff = bp->b_offset; 3387 KASSERT(bp->b_offset != NOOFFSET, 3388 ("biodone_finish: bp %p has no buffer offset", bp)); 3389 3390 /* 3391 * Set B_CACHE if the op was a normal read and no error 3392 * occured. B_CACHE is set for writes in the b*write() 3393 * routines. 3394 */ 3395 iosize = bp->b_bcount - bp->b_resid; 3396 if (bp->b_iocmd == BIO_READ && 3397 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3398 !(bp->b_ioflags & BIO_ERROR)) { 3399 bp->b_flags |= B_CACHE; 3400 } 3401 bogus = 0; 3402 VM_OBJECT_WLOCK(obj); 3403 for (i = 0; i < bp->b_npages; i++) { 3404 int bogusflag = 0; 3405 int resid; 3406 3407 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3408 if (resid > iosize) 3409 resid = iosize; 3410 3411 /* 3412 * cleanup bogus pages, restoring the originals 3413 */ 3414 m = bp->b_pages[i]; 3415 if (m == bogus_page) { 3416 bogus = bogusflag = 1; 3417 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3418 if (m == NULL) 3419 panic("biodone: page disappeared!"); 3420 bp->b_pages[i] = m; 3421 } 3422 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3423 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3424 (intmax_t)foff, (uintmax_t)m->pindex)); 3425 3426 /* 3427 * In the write case, the valid and clean bits are 3428 * already changed correctly ( see bdwrite() ), so we 3429 * only need to do this here in the read case. 3430 */ 3431 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3432 KASSERT((m->dirty & vm_page_bits(foff & 3433 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3434 " page %p has unexpected dirty bits", m)); 3435 vfs_page_set_valid(bp, foff, m); 3436 } 3437 3438 vm_page_io_finish(m); 3439 vm_object_pip_subtract(obj, 1); 3440 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3441 iosize -= resid; 3442 } 3443 vm_object_pip_wakeupn(obj, 0); 3444 VM_OBJECT_WUNLOCK(obj); 3445 if (bogus) 3446 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3447 bp->b_pages, bp->b_npages); 3448 } 3449 3450 /* 3451 * For asynchronous completions, release the buffer now. The brelse 3452 * will do a wakeup there if necessary - so no need to do a wakeup 3453 * here in the async case. The sync case always needs to do a wakeup. 3454 */ 3455 3456 if (bp->b_flags & B_ASYNC) { 3457 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3458 brelse(bp); 3459 else 3460 bqrelse(bp); 3461 } else 3462 bdone(bp); 3463 } 3464 3465 /* 3466 * This routine is called in lieu of iodone in the case of 3467 * incomplete I/O. This keeps the busy status for pages 3468 * consistant. 3469 */ 3470 void 3471 vfs_unbusy_pages(struct buf *bp) 3472 { 3473 int i; 3474 vm_object_t obj; 3475 vm_page_t m; 3476 3477 runningbufwakeup(bp); 3478 if (!(bp->b_flags & B_VMIO)) 3479 return; 3480 3481 obj = bp->b_bufobj->bo_object; 3482 VM_OBJECT_WLOCK(obj); 3483 for (i = 0; i < bp->b_npages; i++) { 3484 m = bp->b_pages[i]; 3485 if (m == bogus_page) { 3486 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3487 if (!m) 3488 panic("vfs_unbusy_pages: page missing\n"); 3489 bp->b_pages[i] = m; 3490 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3491 bp->b_pages, bp->b_npages); 3492 } 3493 vm_object_pip_subtract(obj, 1); 3494 vm_page_io_finish(m); 3495 } 3496 vm_object_pip_wakeupn(obj, 0); 3497 VM_OBJECT_WUNLOCK(obj); 3498 } 3499 3500 /* 3501 * vfs_page_set_valid: 3502 * 3503 * Set the valid bits in a page based on the supplied offset. The 3504 * range is restricted to the buffer's size. 3505 * 3506 * This routine is typically called after a read completes. 3507 */ 3508 static void 3509 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3510 { 3511 vm_ooffset_t eoff; 3512 3513 /* 3514 * Compute the end offset, eoff, such that [off, eoff) does not span a 3515 * page boundary and eoff is not greater than the end of the buffer. 3516 * The end of the buffer, in this case, is our file EOF, not the 3517 * allocation size of the buffer. 3518 */ 3519 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3520 if (eoff > bp->b_offset + bp->b_bcount) 3521 eoff = bp->b_offset + bp->b_bcount; 3522 3523 /* 3524 * Set valid range. This is typically the entire buffer and thus the 3525 * entire page. 3526 */ 3527 if (eoff > off) 3528 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3529 } 3530 3531 /* 3532 * vfs_page_set_validclean: 3533 * 3534 * Set the valid bits and clear the dirty bits in a page based on the 3535 * supplied offset. The range is restricted to the buffer's size. 3536 */ 3537 static void 3538 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3539 { 3540 vm_ooffset_t soff, eoff; 3541 3542 /* 3543 * Start and end offsets in buffer. eoff - soff may not cross a 3544 * page boundry or cross the end of the buffer. The end of the 3545 * buffer, in this case, is our file EOF, not the allocation size 3546 * of the buffer. 3547 */ 3548 soff = off; 3549 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3550 if (eoff > bp->b_offset + bp->b_bcount) 3551 eoff = bp->b_offset + bp->b_bcount; 3552 3553 /* 3554 * Set valid range. This is typically the entire buffer and thus the 3555 * entire page. 3556 */ 3557 if (eoff > soff) { 3558 vm_page_set_validclean( 3559 m, 3560 (vm_offset_t) (soff & PAGE_MASK), 3561 (vm_offset_t) (eoff - soff) 3562 ); 3563 } 3564 } 3565 3566 /* 3567 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3568 * any page is busy, drain the flag. 3569 */ 3570 static void 3571 vfs_drain_busy_pages(struct buf *bp) 3572 { 3573 vm_page_t m; 3574 int i, last_busied; 3575 3576 VM_OBJECT_ASSERT_WLOCKED(bp->b_bufobj->bo_object); 3577 last_busied = 0; 3578 for (i = 0; i < bp->b_npages; i++) { 3579 m = bp->b_pages[i]; 3580 if ((m->oflags & VPO_BUSY) != 0) { 3581 for (; last_busied < i; last_busied++) 3582 vm_page_busy(bp->b_pages[last_busied]); 3583 while ((m->oflags & VPO_BUSY) != 0) 3584 vm_page_sleep(m, "vbpage"); 3585 } 3586 } 3587 for (i = 0; i < last_busied; i++) 3588 vm_page_wakeup(bp->b_pages[i]); 3589 } 3590 3591 /* 3592 * This routine is called before a device strategy routine. 3593 * It is used to tell the VM system that paging I/O is in 3594 * progress, and treat the pages associated with the buffer 3595 * almost as being VPO_BUSY. Also the object paging_in_progress 3596 * flag is handled to make sure that the object doesn't become 3597 * inconsistant. 3598 * 3599 * Since I/O has not been initiated yet, certain buffer flags 3600 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3601 * and should be ignored. 3602 */ 3603 void 3604 vfs_busy_pages(struct buf *bp, int clear_modify) 3605 { 3606 int i, bogus; 3607 vm_object_t obj; 3608 vm_ooffset_t foff; 3609 vm_page_t m; 3610 3611 if (!(bp->b_flags & B_VMIO)) 3612 return; 3613 3614 obj = bp->b_bufobj->bo_object; 3615 foff = bp->b_offset; 3616 KASSERT(bp->b_offset != NOOFFSET, 3617 ("vfs_busy_pages: no buffer offset")); 3618 VM_OBJECT_WLOCK(obj); 3619 vfs_drain_busy_pages(bp); 3620 if (bp->b_bufsize != 0) 3621 vfs_setdirty_locked_object(bp); 3622 bogus = 0; 3623 for (i = 0; i < bp->b_npages; i++) { 3624 m = bp->b_pages[i]; 3625 3626 if ((bp->b_flags & B_CLUSTER) == 0) { 3627 vm_object_pip_add(obj, 1); 3628 vm_page_io_start(m); 3629 } 3630 /* 3631 * When readying a buffer for a read ( i.e 3632 * clear_modify == 0 ), it is important to do 3633 * bogus_page replacement for valid pages in 3634 * partially instantiated buffers. Partially 3635 * instantiated buffers can, in turn, occur when 3636 * reconstituting a buffer from its VM backing store 3637 * base. We only have to do this if B_CACHE is 3638 * clear ( which causes the I/O to occur in the 3639 * first place ). The replacement prevents the read 3640 * I/O from overwriting potentially dirty VM-backed 3641 * pages. XXX bogus page replacement is, uh, bogus. 3642 * It may not work properly with small-block devices. 3643 * We need to find a better way. 3644 */ 3645 if (clear_modify) { 3646 pmap_remove_write(m); 3647 vfs_page_set_validclean(bp, foff, m); 3648 } else if (m->valid == VM_PAGE_BITS_ALL && 3649 (bp->b_flags & B_CACHE) == 0) { 3650 bp->b_pages[i] = bogus_page; 3651 bogus++; 3652 } 3653 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3654 } 3655 VM_OBJECT_WUNLOCK(obj); 3656 if (bogus) 3657 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3658 bp->b_pages, bp->b_npages); 3659 } 3660 3661 /* 3662 * vfs_bio_set_valid: 3663 * 3664 * Set the range within the buffer to valid. The range is 3665 * relative to the beginning of the buffer, b_offset. Note that 3666 * b_offset itself may be offset from the beginning of the first 3667 * page. 3668 */ 3669 void 3670 vfs_bio_set_valid(struct buf *bp, int base, int size) 3671 { 3672 int i, n; 3673 vm_page_t m; 3674 3675 if (!(bp->b_flags & B_VMIO)) 3676 return; 3677 3678 /* 3679 * Fixup base to be relative to beginning of first page. 3680 * Set initial n to be the maximum number of bytes in the 3681 * first page that can be validated. 3682 */ 3683 base += (bp->b_offset & PAGE_MASK); 3684 n = PAGE_SIZE - (base & PAGE_MASK); 3685 3686 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3687 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3688 m = bp->b_pages[i]; 3689 if (n > size) 3690 n = size; 3691 vm_page_set_valid_range(m, base & PAGE_MASK, n); 3692 base += n; 3693 size -= n; 3694 n = PAGE_SIZE; 3695 } 3696 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3697 } 3698 3699 /* 3700 * vfs_bio_clrbuf: 3701 * 3702 * If the specified buffer is a non-VMIO buffer, clear the entire 3703 * buffer. If the specified buffer is a VMIO buffer, clear and 3704 * validate only the previously invalid portions of the buffer. 3705 * This routine essentially fakes an I/O, so we need to clear 3706 * BIO_ERROR and B_INVAL. 3707 * 3708 * Note that while we only theoretically need to clear through b_bcount, 3709 * we go ahead and clear through b_bufsize. 3710 */ 3711 void 3712 vfs_bio_clrbuf(struct buf *bp) 3713 { 3714 int i, j, mask, sa, ea, slide; 3715 3716 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3717 clrbuf(bp); 3718 return; 3719 } 3720 bp->b_flags &= ~B_INVAL; 3721 bp->b_ioflags &= ~BIO_ERROR; 3722 VM_OBJECT_WLOCK(bp->b_bufobj->bo_object); 3723 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3724 (bp->b_offset & PAGE_MASK) == 0) { 3725 if (bp->b_pages[0] == bogus_page) 3726 goto unlock; 3727 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3728 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[0]->object); 3729 if ((bp->b_pages[0]->valid & mask) == mask) 3730 goto unlock; 3731 if ((bp->b_pages[0]->valid & mask) == 0) { 3732 pmap_zero_page_area(bp->b_pages[0], 0, bp->b_bufsize); 3733 bp->b_pages[0]->valid |= mask; 3734 goto unlock; 3735 } 3736 } 3737 sa = bp->b_offset & PAGE_MASK; 3738 slide = 0; 3739 for (i = 0; i < bp->b_npages; i++, sa = 0) { 3740 slide = imin(slide + PAGE_SIZE, bp->b_offset + bp->b_bufsize); 3741 ea = slide & PAGE_MASK; 3742 if (ea == 0) 3743 ea = PAGE_SIZE; 3744 if (bp->b_pages[i] == bogus_page) 3745 continue; 3746 j = sa / DEV_BSIZE; 3747 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3748 VM_OBJECT_ASSERT_WLOCKED(bp->b_pages[i]->object); 3749 if ((bp->b_pages[i]->valid & mask) == mask) 3750 continue; 3751 if ((bp->b_pages[i]->valid & mask) == 0) 3752 pmap_zero_page_area(bp->b_pages[i], sa, ea - sa); 3753 else { 3754 for (; sa < ea; sa += DEV_BSIZE, j++) { 3755 if ((bp->b_pages[i]->valid & (1 << j)) == 0) { 3756 pmap_zero_page_area(bp->b_pages[i], 3757 sa, DEV_BSIZE); 3758 } 3759 } 3760 } 3761 bp->b_pages[i]->valid |= mask; 3762 } 3763 unlock: 3764 VM_OBJECT_WUNLOCK(bp->b_bufobj->bo_object); 3765 bp->b_resid = 0; 3766 } 3767 3768 /* 3769 * vm_hold_load_pages and vm_hold_free_pages get pages into 3770 * a buffers address space. The pages are anonymous and are 3771 * not associated with a file object. 3772 */ 3773 static void 3774 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3775 { 3776 vm_offset_t pg; 3777 vm_page_t p; 3778 int index; 3779 3780 to = round_page(to); 3781 from = round_page(from); 3782 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3783 3784 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3785 tryagain: 3786 /* 3787 * note: must allocate system pages since blocking here 3788 * could interfere with paging I/O, no matter which 3789 * process we are. 3790 */ 3791 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 3792 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 3793 if (p == NULL) { 3794 VM_WAIT; 3795 goto tryagain; 3796 } 3797 pmap_qenter(pg, &p, 1); 3798 bp->b_pages[index] = p; 3799 } 3800 bp->b_npages = index; 3801 } 3802 3803 /* Return pages associated with this buf to the vm system */ 3804 static void 3805 vm_hold_free_pages(struct buf *bp, int newbsize) 3806 { 3807 vm_offset_t from; 3808 vm_page_t p; 3809 int index, newnpages; 3810 3811 from = round_page((vm_offset_t)bp->b_data + newbsize); 3812 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3813 if (bp->b_npages > newnpages) 3814 pmap_qremove(from, bp->b_npages - newnpages); 3815 for (index = newnpages; index < bp->b_npages; index++) { 3816 p = bp->b_pages[index]; 3817 bp->b_pages[index] = NULL; 3818 if (p->busy != 0) 3819 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3820 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 3821 p->wire_count--; 3822 vm_page_free(p); 3823 atomic_subtract_int(&cnt.v_wire_count, 1); 3824 } 3825 bp->b_npages = newnpages; 3826 } 3827 3828 /* 3829 * Map an IO request into kernel virtual address space. 3830 * 3831 * All requests are (re)mapped into kernel VA space. 3832 * Notice that we use b_bufsize for the size of the buffer 3833 * to be mapped. b_bcount might be modified by the driver. 3834 * 3835 * Note that even if the caller determines that the address space should 3836 * be valid, a race or a smaller-file mapped into a larger space may 3837 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3838 * check the return value. 3839 */ 3840 int 3841 vmapbuf(struct buf *bp) 3842 { 3843 caddr_t kva; 3844 vm_prot_t prot; 3845 int pidx; 3846 3847 if (bp->b_bufsize < 0) 3848 return (-1); 3849 prot = VM_PROT_READ; 3850 if (bp->b_iocmd == BIO_READ) 3851 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3852 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 3853 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 3854 btoc(MAXPHYS))) < 0) 3855 return (-1); 3856 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3857 3858 kva = bp->b_saveaddr; 3859 bp->b_npages = pidx; 3860 bp->b_saveaddr = bp->b_data; 3861 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3862 return(0); 3863 } 3864 3865 /* 3866 * Free the io map PTEs associated with this IO operation. 3867 * We also invalidate the TLB entries and restore the original b_addr. 3868 */ 3869 void 3870 vunmapbuf(struct buf *bp) 3871 { 3872 int npages; 3873 3874 npages = bp->b_npages; 3875 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3876 vm_page_unhold_pages(bp->b_pages, npages); 3877 3878 bp->b_data = bp->b_saveaddr; 3879 } 3880 3881 void 3882 bdone(struct buf *bp) 3883 { 3884 struct mtx *mtxp; 3885 3886 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3887 mtx_lock(mtxp); 3888 bp->b_flags |= B_DONE; 3889 wakeup(bp); 3890 mtx_unlock(mtxp); 3891 } 3892 3893 void 3894 bwait(struct buf *bp, u_char pri, const char *wchan) 3895 { 3896 struct mtx *mtxp; 3897 3898 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3899 mtx_lock(mtxp); 3900 while ((bp->b_flags & B_DONE) == 0) 3901 msleep(bp, mtxp, pri, wchan, 0); 3902 mtx_unlock(mtxp); 3903 } 3904 3905 int 3906 bufsync(struct bufobj *bo, int waitfor) 3907 { 3908 3909 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3910 } 3911 3912 void 3913 bufstrategy(struct bufobj *bo, struct buf *bp) 3914 { 3915 int i = 0; 3916 struct vnode *vp; 3917 3918 vp = bp->b_vp; 3919 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3920 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3921 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3922 i = VOP_STRATEGY(vp, bp); 3923 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3924 } 3925 3926 void 3927 bufobj_wrefl(struct bufobj *bo) 3928 { 3929 3930 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3931 ASSERT_BO_LOCKED(bo); 3932 bo->bo_numoutput++; 3933 } 3934 3935 void 3936 bufobj_wref(struct bufobj *bo) 3937 { 3938 3939 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3940 BO_LOCK(bo); 3941 bo->bo_numoutput++; 3942 BO_UNLOCK(bo); 3943 } 3944 3945 void 3946 bufobj_wdrop(struct bufobj *bo) 3947 { 3948 3949 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3950 BO_LOCK(bo); 3951 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3952 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3953 bo->bo_flag &= ~BO_WWAIT; 3954 wakeup(&bo->bo_numoutput); 3955 } 3956 BO_UNLOCK(bo); 3957 } 3958 3959 int 3960 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3961 { 3962 int error; 3963 3964 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3965 ASSERT_BO_LOCKED(bo); 3966 error = 0; 3967 while (bo->bo_numoutput) { 3968 bo->bo_flag |= BO_WWAIT; 3969 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3970 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3971 if (error) 3972 break; 3973 } 3974 return (error); 3975 } 3976 3977 void 3978 bpin(struct buf *bp) 3979 { 3980 struct mtx *mtxp; 3981 3982 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3983 mtx_lock(mtxp); 3984 bp->b_pin_count++; 3985 mtx_unlock(mtxp); 3986 } 3987 3988 void 3989 bunpin(struct buf *bp) 3990 { 3991 struct mtx *mtxp; 3992 3993 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3994 mtx_lock(mtxp); 3995 if (--bp->b_pin_count == 0) 3996 wakeup(bp); 3997 mtx_unlock(mtxp); 3998 } 3999 4000 void 4001 bunpin_wait(struct buf *bp) 4002 { 4003 struct mtx *mtxp; 4004 4005 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4006 mtx_lock(mtxp); 4007 while (bp->b_pin_count > 0) 4008 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4009 mtx_unlock(mtxp); 4010 } 4011 4012 #include "opt_ddb.h" 4013 #ifdef DDB 4014 #include <ddb/ddb.h> 4015 4016 /* DDB command to show buffer data */ 4017 DB_SHOW_COMMAND(buffer, db_show_buffer) 4018 { 4019 /* get args */ 4020 struct buf *bp = (struct buf *)addr; 4021 4022 if (!have_addr) { 4023 db_printf("usage: show buffer <addr>\n"); 4024 return; 4025 } 4026 4027 db_printf("buf at %p\n", bp); 4028 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4029 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4030 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4031 db_printf( 4032 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4033 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4034 "b_dep = %p\n", 4035 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4036 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4037 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4038 if (bp->b_npages) { 4039 int i; 4040 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4041 for (i = 0; i < bp->b_npages; i++) { 4042 vm_page_t m; 4043 m = bp->b_pages[i]; 4044 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4045 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4046 if ((i + 1) < bp->b_npages) 4047 db_printf(","); 4048 } 4049 db_printf("\n"); 4050 } 4051 db_printf(" "); 4052 BUF_LOCKPRINTINFO(bp); 4053 } 4054 4055 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4056 { 4057 struct buf *bp; 4058 int i; 4059 4060 for (i = 0; i < nbuf; i++) { 4061 bp = &buf[i]; 4062 if (BUF_ISLOCKED(bp)) { 4063 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4064 db_printf("\n"); 4065 } 4066 } 4067 } 4068 4069 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4070 { 4071 struct vnode *vp; 4072 struct buf *bp; 4073 4074 if (!have_addr) { 4075 db_printf("usage: show vnodebufs <addr>\n"); 4076 return; 4077 } 4078 vp = (struct vnode *)addr; 4079 db_printf("Clean buffers:\n"); 4080 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4081 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4082 db_printf("\n"); 4083 } 4084 db_printf("Dirty buffers:\n"); 4085 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4086 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4087 db_printf("\n"); 4088 } 4089 } 4090 4091 DB_COMMAND(countfreebufs, db_coundfreebufs) 4092 { 4093 struct buf *bp; 4094 int i, used = 0, nfree = 0; 4095 4096 if (have_addr) { 4097 db_printf("usage: countfreebufs\n"); 4098 return; 4099 } 4100 4101 for (i = 0; i < nbuf; i++) { 4102 bp = &buf[i]; 4103 if ((bp->b_vflags & BV_INFREECNT) != 0) 4104 nfree++; 4105 else 4106 used++; 4107 } 4108 4109 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4110 nfree + used); 4111 db_printf("numfreebuffers is %d\n", numfreebuffers); 4112 } 4113 #endif /* DDB */ 4114