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/sysctl.h> 62 #include <sys/vmmeter.h> 63 #include <sys/vnode.h> 64 #include <geom/geom.h> 65 #include <vm/vm.h> 66 #include <vm/vm_param.h> 67 #include <vm/vm_kern.h> 68 #include <vm/vm_pageout.h> 69 #include <vm/vm_page.h> 70 #include <vm/vm_object.h> 71 #include <vm/vm_extern.h> 72 #include <vm/vm_map.h> 73 #include "opt_compat.h" 74 #include "opt_directio.h" 75 #include "opt_swap.h" 76 77 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 78 79 struct bio_ops bioops; /* I/O operation notification */ 80 81 struct buf_ops buf_ops_bio = { 82 .bop_name = "buf_ops_bio", 83 .bop_write = bufwrite, 84 .bop_strategy = bufstrategy, 85 .bop_sync = bufsync, 86 .bop_bdflush = bufbdflush, 87 }; 88 89 /* 90 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 91 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 92 */ 93 struct buf *buf; /* buffer header pool */ 94 95 static struct proc *bufdaemonproc; 96 97 static int inmem(struct vnode *vp, daddr_t blkno); 98 static void vm_hold_free_pages(struct buf *bp, int newbsize); 99 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 100 vm_offset_t to); 101 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 102 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 103 vm_page_t m); 104 static void vfs_drain_busy_pages(struct buf *bp); 105 static void vfs_clean_pages_dirty_buf(struct buf *bp); 106 static void vfs_setdirty_locked_object(struct buf *bp); 107 static void vfs_vmio_release(struct buf *bp); 108 static int vfs_bio_clcheck(struct vnode *vp, int size, 109 daddr_t lblkno, daddr_t blkno); 110 static int buf_do_flush(struct vnode *vp); 111 static int flushbufqueues(struct vnode *, int, int); 112 static void buf_daemon(void); 113 static void bremfreel(struct buf *bp); 114 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 115 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 116 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 117 #endif 118 119 int vmiodirenable = TRUE; 120 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 121 "Use the VM system for directory writes"); 122 long runningbufspace; 123 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 124 "Amount of presently outstanding async buffer io"); 125 static long bufspace; 126 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 127 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 128 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 129 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 130 #else 131 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 132 "Virtual memory used for buffers"); 133 #endif 134 static long maxbufspace; 135 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 136 "Maximum allowed value of bufspace (including buf_daemon)"); 137 static long bufmallocspace; 138 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 139 "Amount of malloced memory for buffers"); 140 static long maxbufmallocspace; 141 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 142 "Maximum amount of malloced memory for buffers"); 143 static long lobufspace; 144 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 145 "Minimum amount of buffers we want to have"); 146 long hibufspace; 147 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 148 "Maximum allowed value of bufspace (excluding buf_daemon)"); 149 static int bufreusecnt; 150 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 151 "Number of times we have reused a buffer"); 152 static int buffreekvacnt; 153 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 154 "Number of times we have freed the KVA space from some buffer"); 155 static int bufdefragcnt; 156 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 157 "Number of times we have had to repeat buffer allocation to defragment"); 158 static long lorunningspace; 159 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 160 "Minimum preferred space used for in-progress I/O"); 161 static long hirunningspace; 162 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 163 "Maximum amount of space to use for in-progress I/O"); 164 int dirtybufferflushes; 165 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 166 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 167 int bdwriteskip; 168 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 169 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 170 int altbufferflushes; 171 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 172 0, "Number of fsync flushes to limit dirty buffers"); 173 static int recursiveflushes; 174 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 175 0, "Number of flushes skipped due to being recursive"); 176 static int numdirtybuffers; 177 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 178 "Number of buffers that are dirty (has unwritten changes) at the moment"); 179 static int lodirtybuffers; 180 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 181 "How many buffers we want to have free before bufdaemon can sleep"); 182 static int hidirtybuffers; 183 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 184 "When the number of dirty buffers is considered severe"); 185 int dirtybufthresh; 186 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 187 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 188 static int numfreebuffers; 189 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 190 "Number of free buffers"); 191 static int lofreebuffers; 192 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 193 "XXX Unused"); 194 static int hifreebuffers; 195 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 196 "XXX Complicatedly unused"); 197 static int getnewbufcalls; 198 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 199 "Number of calls to getnewbuf"); 200 static int getnewbufrestarts; 201 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 202 "Number of times getnewbuf has had to restart a buffer aquisition"); 203 static int flushbufqtarget = 100; 204 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 205 "Amount of work to do in flushbufqueues when helping bufdaemon"); 206 static long notbufdflashes; 207 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, 208 "Number of dirty buffer flushes done by the bufdaemon helpers"); 209 static long barrierwrites; 210 SYSCTL_LONG(_vfs, OID_AUTO, barrierwrites, CTLFLAG_RW, &barrierwrites, 0, 211 "Number of barrier writes"); 212 213 /* 214 * Wakeup point for bufdaemon, as well as indicator of whether it is already 215 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 216 * is idling. 217 */ 218 static int bd_request; 219 220 /* 221 * Request for the buf daemon to write more buffers than is indicated by 222 * lodirtybuf. This may be necessary to push out excess dependencies or 223 * defragment the address space where a simple count of the number of dirty 224 * buffers is insufficient to characterize the demand for flushing them. 225 */ 226 static int bd_speedupreq; 227 228 /* 229 * This lock synchronizes access to bd_request. 230 */ 231 static struct mtx bdlock; 232 233 /* 234 * bogus page -- for I/O to/from partially complete buffers 235 * this is a temporary solution to the problem, but it is not 236 * really that bad. it would be better to split the buffer 237 * for input in the case of buffers partially already in memory, 238 * but the code is intricate enough already. 239 */ 240 vm_page_t bogus_page; 241 242 /* 243 * Synchronization (sleep/wakeup) variable for active buffer space requests. 244 * Set when wait starts, cleared prior to wakeup(). 245 * Used in runningbufwakeup() and waitrunningbufspace(). 246 */ 247 static int runningbufreq; 248 249 /* 250 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 251 * waitrunningbufspace(). 252 */ 253 static struct mtx rbreqlock; 254 255 /* 256 * Synchronization (sleep/wakeup) variable for buffer requests. 257 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 258 * by and/or. 259 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 260 * getnewbuf(), and getblk(). 261 */ 262 static int needsbuffer; 263 264 /* 265 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 266 */ 267 static struct mtx nblock; 268 269 /* 270 * Definitions for the buffer free lists. 271 */ 272 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 273 274 #define QUEUE_NONE 0 /* on no queue */ 275 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 276 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 277 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 278 #define QUEUE_EMPTY 4 /* empty buffer headers */ 279 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 280 281 /* Queues for free buffers with various properties */ 282 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 283 284 /* Lock for the bufqueues */ 285 static struct mtx bqlock; 286 287 /* 288 * Single global constant for BUF_WMESG, to avoid getting multiple references. 289 * buf_wmesg is referred from macros. 290 */ 291 const char *buf_wmesg = BUF_WMESG; 292 293 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 294 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 295 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 296 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 297 298 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 299 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 300 static int 301 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 302 { 303 long lvalue; 304 int ivalue; 305 306 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 307 return (sysctl_handle_long(oidp, arg1, arg2, req)); 308 lvalue = *(long *)arg1; 309 if (lvalue > INT_MAX) 310 /* On overflow, still write out a long to trigger ENOMEM. */ 311 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 312 ivalue = lvalue; 313 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 314 } 315 #endif 316 317 #ifdef DIRECTIO 318 extern void ffs_rawread_setup(void); 319 #endif /* DIRECTIO */ 320 /* 321 * numdirtywakeup: 322 * 323 * If someone is blocked due to there being too many dirty buffers, 324 * and numdirtybuffers is now reasonable, wake them up. 325 */ 326 327 static __inline void 328 numdirtywakeup(int level) 329 { 330 331 if (numdirtybuffers <= level) { 332 mtx_lock(&nblock); 333 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 334 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 335 wakeup(&needsbuffer); 336 } 337 mtx_unlock(&nblock); 338 } 339 } 340 341 /* 342 * bufspacewakeup: 343 * 344 * Called when buffer space is potentially available for recovery. 345 * getnewbuf() will block on this flag when it is unable to free 346 * sufficient buffer space. Buffer space becomes recoverable when 347 * bp's get placed back in the queues. 348 */ 349 350 static __inline void 351 bufspacewakeup(void) 352 { 353 354 /* 355 * If someone is waiting for BUF space, wake them up. Even 356 * though we haven't freed the kva space yet, the waiting 357 * process will be able to now. 358 */ 359 mtx_lock(&nblock); 360 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 361 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 362 wakeup(&needsbuffer); 363 } 364 mtx_unlock(&nblock); 365 } 366 367 /* 368 * runningbufwakeup() - in-progress I/O accounting. 369 * 370 */ 371 void 372 runningbufwakeup(struct buf *bp) 373 { 374 375 if (bp->b_runningbufspace) { 376 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 377 bp->b_runningbufspace = 0; 378 mtx_lock(&rbreqlock); 379 if (runningbufreq && runningbufspace <= lorunningspace) { 380 runningbufreq = 0; 381 wakeup(&runningbufreq); 382 } 383 mtx_unlock(&rbreqlock); 384 } 385 } 386 387 /* 388 * bufcountwakeup: 389 * 390 * Called when a buffer has been added to one of the free queues to 391 * account for the buffer and to wakeup anyone waiting for free buffers. 392 * This typically occurs when large amounts of metadata are being handled 393 * by the buffer cache ( else buffer space runs out first, usually ). 394 */ 395 396 static __inline void 397 bufcountwakeup(struct buf *bp) 398 { 399 int old; 400 401 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 402 ("buf %p already counted as free", bp)); 403 if (bp->b_bufobj != NULL) 404 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 405 bp->b_vflags |= BV_INFREECNT; 406 old = atomic_fetchadd_int(&numfreebuffers, 1); 407 KASSERT(old >= 0 && old < nbuf, 408 ("numfreebuffers climbed to %d", old + 1)); 409 mtx_lock(&nblock); 410 if (needsbuffer) { 411 needsbuffer &= ~VFS_BIO_NEED_ANY; 412 if (numfreebuffers >= hifreebuffers) 413 needsbuffer &= ~VFS_BIO_NEED_FREE; 414 wakeup(&needsbuffer); 415 } 416 mtx_unlock(&nblock); 417 } 418 419 /* 420 * waitrunningbufspace() 421 * 422 * runningbufspace is a measure of the amount of I/O currently 423 * running. This routine is used in async-write situations to 424 * prevent creating huge backups of pending writes to a device. 425 * Only asynchronous writes are governed by this function. 426 * 427 * Reads will adjust runningbufspace, but will not block based on it. 428 * The read load has a side effect of reducing the allowed write load. 429 * 430 * This does NOT turn an async write into a sync write. It waits 431 * for earlier writes to complete and generally returns before the 432 * caller's write has reached the device. 433 */ 434 void 435 waitrunningbufspace(void) 436 { 437 438 mtx_lock(&rbreqlock); 439 while (runningbufspace > hirunningspace) { 440 ++runningbufreq; 441 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 442 } 443 mtx_unlock(&rbreqlock); 444 } 445 446 447 /* 448 * vfs_buf_test_cache: 449 * 450 * Called when a buffer is extended. This function clears the B_CACHE 451 * bit if the newly extended portion of the buffer does not contain 452 * valid data. 453 */ 454 static __inline 455 void 456 vfs_buf_test_cache(struct buf *bp, 457 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 458 vm_page_t m) 459 { 460 461 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 462 if (bp->b_flags & B_CACHE) { 463 int base = (foff + off) & PAGE_MASK; 464 if (vm_page_is_valid(m, base, size) == 0) 465 bp->b_flags &= ~B_CACHE; 466 } 467 } 468 469 /* Wake up the buffer daemon if necessary */ 470 static __inline 471 void 472 bd_wakeup(int dirtybuflevel) 473 { 474 475 mtx_lock(&bdlock); 476 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 477 bd_request = 1; 478 wakeup(&bd_request); 479 } 480 mtx_unlock(&bdlock); 481 } 482 483 /* 484 * bd_speedup - speedup the buffer cache flushing code 485 */ 486 487 void 488 bd_speedup(void) 489 { 490 int needwake; 491 492 mtx_lock(&bdlock); 493 needwake = 0; 494 if (bd_speedupreq == 0 || bd_request == 0) 495 needwake = 1; 496 bd_speedupreq = 1; 497 bd_request = 1; 498 if (needwake) 499 wakeup(&bd_request); 500 mtx_unlock(&bdlock); 501 } 502 503 /* 504 * Calculating buffer cache scaling values and reserve space for buffer 505 * headers. This is called during low level kernel initialization and 506 * may be called more then once. We CANNOT write to the memory area 507 * being reserved at this time. 508 */ 509 caddr_t 510 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 511 { 512 int tuned_nbuf; 513 long maxbuf; 514 515 /* 516 * physmem_est is in pages. Convert it to kilobytes (assumes 517 * PAGE_SIZE is >= 1K) 518 */ 519 physmem_est = physmem_est * (PAGE_SIZE / 1024); 520 521 /* 522 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 523 * For the first 64MB of ram nominally allocate sufficient buffers to 524 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 525 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 526 * the buffer cache we limit the eventual kva reservation to 527 * maxbcache bytes. 528 * 529 * factor represents the 1/4 x ram conversion. 530 */ 531 if (nbuf == 0) { 532 int factor = 4 * BKVASIZE / 1024; 533 534 nbuf = 50; 535 if (physmem_est > 4096) 536 nbuf += min((physmem_est - 4096) / factor, 537 65536 / factor); 538 if (physmem_est > 65536) 539 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 540 541 if (maxbcache && nbuf > maxbcache / BKVASIZE) 542 nbuf = maxbcache / BKVASIZE; 543 tuned_nbuf = 1; 544 } else 545 tuned_nbuf = 0; 546 547 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 548 maxbuf = (LONG_MAX / 3) / BKVASIZE; 549 if (nbuf > maxbuf) { 550 if (!tuned_nbuf) 551 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 552 maxbuf); 553 nbuf = maxbuf; 554 } 555 556 /* 557 * swbufs are used as temporary holders for I/O, such as paging I/O. 558 * We have no less then 16 and no more then 256. 559 */ 560 nswbuf = max(min(nbuf/4, 256), 16); 561 #ifdef NSWBUF_MIN 562 if (nswbuf < NSWBUF_MIN) 563 nswbuf = NSWBUF_MIN; 564 #endif 565 #ifdef DIRECTIO 566 ffs_rawread_setup(); 567 #endif 568 569 /* 570 * Reserve space for the buffer cache buffers 571 */ 572 swbuf = (void *)v; 573 v = (caddr_t)(swbuf + nswbuf); 574 buf = (void *)v; 575 v = (caddr_t)(buf + nbuf); 576 577 return(v); 578 } 579 580 /* Initialize the buffer subsystem. Called before use of any buffers. */ 581 void 582 bufinit(void) 583 { 584 struct buf *bp; 585 int i; 586 587 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 588 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 589 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 590 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 591 592 /* next, make a null set of free lists */ 593 for (i = 0; i < BUFFER_QUEUES; i++) 594 TAILQ_INIT(&bufqueues[i]); 595 596 /* finally, initialize each buffer header and stick on empty q */ 597 for (i = 0; i < nbuf; i++) { 598 bp = &buf[i]; 599 bzero(bp, sizeof *bp); 600 bp->b_flags = B_INVAL; /* we're just an empty header */ 601 bp->b_rcred = NOCRED; 602 bp->b_wcred = NOCRED; 603 bp->b_qindex = QUEUE_EMPTY; 604 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */ 605 bp->b_xflags = 0; 606 LIST_INIT(&bp->b_dep); 607 BUF_LOCKINIT(bp); 608 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 609 } 610 611 /* 612 * maxbufspace is the absolute maximum amount of buffer space we are 613 * allowed to reserve in KVM and in real terms. The absolute maximum 614 * is nominally used by buf_daemon. hibufspace is the nominal maximum 615 * used by most other processes. The differential is required to 616 * ensure that buf_daemon is able to run when other processes might 617 * be blocked waiting for buffer space. 618 * 619 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 620 * this may result in KVM fragmentation which is not handled optimally 621 * by the system. 622 */ 623 maxbufspace = (long)nbuf * BKVASIZE; 624 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 625 lobufspace = hibufspace - MAXBSIZE; 626 627 /* 628 * Note: The 16 MiB upper limit for hirunningspace was chosen 629 * arbitrarily and may need further tuning. It corresponds to 630 * 128 outstanding write IO requests (if IO size is 128 KiB), 631 * which fits with many RAID controllers' tagged queuing limits. 632 * The lower 1 MiB limit is the historical upper limit for 633 * hirunningspace. 634 */ 635 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 636 16 * 1024 * 1024), 1024 * 1024); 637 lorunningspace = roundup((hirunningspace * 2) / 3, MAXBSIZE); 638 639 /* 640 * Limit the amount of malloc memory since it is wired permanently into 641 * the kernel space. Even though this is accounted for in the buffer 642 * allocation, we don't want the malloced region to grow uncontrolled. 643 * The malloc scheme improves memory utilization significantly on average 644 * (small) directories. 645 */ 646 maxbufmallocspace = hibufspace / 20; 647 648 /* 649 * Reduce the chance of a deadlock occuring by limiting the number 650 * of delayed-write dirty buffers we allow to stack up. 651 */ 652 hidirtybuffers = nbuf / 4 + 20; 653 dirtybufthresh = hidirtybuffers * 9 / 10; 654 numdirtybuffers = 0; 655 /* 656 * To support extreme low-memory systems, make sure hidirtybuffers cannot 657 * eat up all available buffer space. This occurs when our minimum cannot 658 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 659 * BKVASIZE'd buffers. 660 */ 661 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 662 hidirtybuffers >>= 1; 663 } 664 lodirtybuffers = hidirtybuffers / 2; 665 666 /* 667 * Try to keep the number of free buffers in the specified range, 668 * and give special processes (e.g. like buf_daemon) access to an 669 * emergency reserve. 670 */ 671 lofreebuffers = nbuf / 18 + 5; 672 hifreebuffers = 2 * lofreebuffers; 673 numfreebuffers = nbuf; 674 675 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 676 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 677 } 678 679 /* 680 * bfreekva() - free the kva allocation for a buffer. 681 * 682 * Since this call frees up buffer space, we call bufspacewakeup(). 683 */ 684 static void 685 bfreekva(struct buf *bp) 686 { 687 688 if (bp->b_kvasize) { 689 atomic_add_int(&buffreekvacnt, 1); 690 atomic_subtract_long(&bufspace, bp->b_kvasize); 691 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 692 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 693 bp->b_kvasize = 0; 694 bufspacewakeup(); 695 } 696 } 697 698 /* 699 * bremfree: 700 * 701 * Mark the buffer for removal from the appropriate free list in brelse. 702 * 703 */ 704 void 705 bremfree(struct buf *bp) 706 { 707 int old; 708 709 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 710 KASSERT((bp->b_flags & B_REMFREE) == 0, 711 ("bremfree: buffer %p already marked for delayed removal.", bp)); 712 KASSERT(bp->b_qindex != QUEUE_NONE, 713 ("bremfree: buffer %p not on a queue.", bp)); 714 BUF_ASSERT_HELD(bp); 715 716 bp->b_flags |= B_REMFREE; 717 /* Fixup numfreebuffers count. */ 718 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 719 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 720 ("buf %p not counted in numfreebuffers", bp)); 721 if (bp->b_bufobj != NULL) 722 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 723 bp->b_vflags &= ~BV_INFREECNT; 724 old = atomic_fetchadd_int(&numfreebuffers, -1); 725 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 726 } 727 } 728 729 /* 730 * bremfreef: 731 * 732 * Force an immediate removal from a free list. Used only in nfs when 733 * it abuses the b_freelist pointer. 734 */ 735 void 736 bremfreef(struct buf *bp) 737 { 738 mtx_lock(&bqlock); 739 bremfreel(bp); 740 mtx_unlock(&bqlock); 741 } 742 743 /* 744 * bremfreel: 745 * 746 * Removes a buffer from the free list, must be called with the 747 * bqlock held. 748 */ 749 static void 750 bremfreel(struct buf *bp) 751 { 752 int old; 753 754 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 755 bp, bp->b_vp, bp->b_flags); 756 KASSERT(bp->b_qindex != QUEUE_NONE, 757 ("bremfreel: buffer %p not on a queue.", bp)); 758 BUF_ASSERT_HELD(bp); 759 mtx_assert(&bqlock, MA_OWNED); 760 761 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 762 bp->b_qindex = QUEUE_NONE; 763 /* 764 * If this was a delayed bremfree() we only need to remove the buffer 765 * from the queue and return the stats are already done. 766 */ 767 if (bp->b_flags & B_REMFREE) { 768 bp->b_flags &= ~B_REMFREE; 769 return; 770 } 771 /* 772 * Fixup numfreebuffers count. If the buffer is invalid or not 773 * delayed-write, the buffer was free and we must decrement 774 * numfreebuffers. 775 */ 776 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 777 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 778 ("buf %p not counted in numfreebuffers", bp)); 779 if (bp->b_bufobj != NULL) 780 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 781 bp->b_vflags &= ~BV_INFREECNT; 782 old = atomic_fetchadd_int(&numfreebuffers, -1); 783 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 784 } 785 } 786 787 /* 788 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 789 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 790 * the buffer is valid and we do not have to do anything. 791 */ 792 void 793 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 794 int cnt, struct ucred * cred) 795 { 796 struct buf *rabp; 797 int i; 798 799 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 800 if (inmem(vp, *rablkno)) 801 continue; 802 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 803 804 if ((rabp->b_flags & B_CACHE) == 0) { 805 if (!TD_IS_IDLETHREAD(curthread)) 806 curthread->td_ru.ru_inblock++; 807 rabp->b_flags |= B_ASYNC; 808 rabp->b_flags &= ~B_INVAL; 809 rabp->b_ioflags &= ~BIO_ERROR; 810 rabp->b_iocmd = BIO_READ; 811 if (rabp->b_rcred == NOCRED && cred != NOCRED) 812 rabp->b_rcred = crhold(cred); 813 vfs_busy_pages(rabp, 0); 814 BUF_KERNPROC(rabp); 815 rabp->b_iooffset = dbtob(rabp->b_blkno); 816 bstrategy(rabp); 817 } else { 818 brelse(rabp); 819 } 820 } 821 } 822 823 /* 824 * Entry point for bread() and breadn() via #defines in sys/buf.h. 825 * 826 * Get a buffer with the specified data. Look in the cache first. We 827 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 828 * is set, the buffer is valid and we do not have to do anything, see 829 * getblk(). Also starts asynchronous I/O on read-ahead blocks. 830 */ 831 int 832 breadn_flags(struct vnode * vp, daddr_t blkno, int size, 833 daddr_t * rablkno, int *rabsize, int cnt, 834 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_LOCK(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_UNLOCK(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_LOCK(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_UNLOCK(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 return nwritten; 1798 } 1799 } 1800 bremfree(bp); 1801 bp->b_flags |= B_ASYNC; 1802 /* 1803 * default (old) behavior, writing out only one block 1804 * 1805 * XXX returns b_bufsize instead of b_bcount for nwritten? 1806 */ 1807 nwritten = bp->b_bufsize; 1808 (void) bwrite(bp); 1809 1810 return nwritten; 1811 } 1812 1813 /* 1814 * getnewbuf: 1815 * 1816 * Find and initialize a new buffer header, freeing up existing buffers 1817 * in the bufqueues as necessary. The new buffer is returned locked. 1818 * 1819 * Important: B_INVAL is not set. If the caller wishes to throw the 1820 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1821 * 1822 * We block if: 1823 * We have insufficient buffer headers 1824 * We have insufficient buffer space 1825 * buffer_map is too fragmented ( space reservation fails ) 1826 * If we have to flush dirty buffers ( but we try to avoid this ) 1827 * 1828 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1829 * Instead we ask the buf daemon to do it for us. We attempt to 1830 * avoid piecemeal wakeups of the pageout daemon. 1831 */ 1832 1833 static struct buf * 1834 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1835 int gbflags) 1836 { 1837 struct thread *td; 1838 struct buf *bp; 1839 struct buf *nbp; 1840 int defrag = 0; 1841 int nqindex; 1842 static int flushingbufs; 1843 1844 td = curthread; 1845 /* 1846 * We can't afford to block since we might be holding a vnode lock, 1847 * which may prevent system daemons from running. We deal with 1848 * low-memory situations by proactively returning memory and running 1849 * async I/O rather then sync I/O. 1850 */ 1851 atomic_add_int(&getnewbufcalls, 1); 1852 atomic_subtract_int(&getnewbufrestarts, 1); 1853 restart: 1854 atomic_add_int(&getnewbufrestarts, 1); 1855 1856 /* 1857 * Setup for scan. If we do not have enough free buffers, 1858 * we setup a degenerate case that immediately fails. Note 1859 * that if we are specially marked process, we are allowed to 1860 * dip into our reserves. 1861 * 1862 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1863 * 1864 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1865 * However, there are a number of cases (defragging, reusing, ...) 1866 * where we cannot backup. 1867 */ 1868 mtx_lock(&bqlock); 1869 nqindex = QUEUE_EMPTYKVA; 1870 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1871 1872 if (nbp == NULL) { 1873 /* 1874 * If no EMPTYKVA buffers and we are either 1875 * defragging or reusing, locate a CLEAN buffer 1876 * to free or reuse. If bufspace useage is low 1877 * skip this step so we can allocate a new buffer. 1878 */ 1879 if (defrag || bufspace >= lobufspace) { 1880 nqindex = QUEUE_CLEAN; 1881 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1882 } 1883 1884 /* 1885 * If we could not find or were not allowed to reuse a 1886 * CLEAN buffer, check to see if it is ok to use an EMPTY 1887 * buffer. We can only use an EMPTY buffer if allocating 1888 * its KVA would not otherwise run us out of buffer space. 1889 */ 1890 if (nbp == NULL && defrag == 0 && 1891 bufspace + maxsize < hibufspace) { 1892 nqindex = QUEUE_EMPTY; 1893 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1894 } 1895 } 1896 1897 /* 1898 * Run scan, possibly freeing data and/or kva mappings on the fly 1899 * depending. 1900 */ 1901 1902 while ((bp = nbp) != NULL) { 1903 int qindex = nqindex; 1904 1905 /* 1906 * Calculate next bp ( we can only use it if we do not block 1907 * or do other fancy things ). 1908 */ 1909 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1910 switch(qindex) { 1911 case QUEUE_EMPTY: 1912 nqindex = QUEUE_EMPTYKVA; 1913 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1914 break; 1915 /* FALLTHROUGH */ 1916 case QUEUE_EMPTYKVA: 1917 nqindex = QUEUE_CLEAN; 1918 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1919 break; 1920 /* FALLTHROUGH */ 1921 case QUEUE_CLEAN: 1922 /* 1923 * nbp is NULL. 1924 */ 1925 break; 1926 } 1927 } 1928 /* 1929 * If we are defragging then we need a buffer with 1930 * b_kvasize != 0. XXX this situation should no longer 1931 * occur, if defrag is non-zero the buffer's b_kvasize 1932 * should also be non-zero at this point. XXX 1933 */ 1934 if (defrag && bp->b_kvasize == 0) { 1935 printf("Warning: defrag empty buffer %p\n", bp); 1936 continue; 1937 } 1938 1939 /* 1940 * Start freeing the bp. This is somewhat involved. nbp 1941 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1942 */ 1943 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1944 continue; 1945 if (bp->b_vp) { 1946 BO_LOCK(bp->b_bufobj); 1947 if (bp->b_vflags & BV_BKGRDINPROG) { 1948 BO_UNLOCK(bp->b_bufobj); 1949 BUF_UNLOCK(bp); 1950 continue; 1951 } 1952 BO_UNLOCK(bp->b_bufobj); 1953 } 1954 CTR6(KTR_BUF, 1955 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1956 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1957 bp->b_kvasize, bp->b_bufsize, qindex); 1958 1959 /* 1960 * Sanity Checks 1961 */ 1962 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1963 1964 /* 1965 * Note: we no longer distinguish between VMIO and non-VMIO 1966 * buffers. 1967 */ 1968 1969 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1970 1971 if (bp->b_bufobj != NULL) 1972 BO_LOCK(bp->b_bufobj); 1973 bremfreel(bp); 1974 if (bp->b_bufobj != NULL) 1975 BO_UNLOCK(bp->b_bufobj); 1976 mtx_unlock(&bqlock); 1977 1978 if (qindex == QUEUE_CLEAN) { 1979 if (bp->b_flags & B_VMIO) { 1980 bp->b_flags &= ~B_ASYNC; 1981 vfs_vmio_release(bp); 1982 } 1983 if (bp->b_vp) 1984 brelvp(bp); 1985 } 1986 1987 /* 1988 * NOTE: nbp is now entirely invalid. We can only restart 1989 * the scan from this point on. 1990 * 1991 * Get the rest of the buffer freed up. b_kva* is still 1992 * valid after this operation. 1993 */ 1994 1995 if (bp->b_rcred != NOCRED) { 1996 crfree(bp->b_rcred); 1997 bp->b_rcred = NOCRED; 1998 } 1999 if (bp->b_wcred != NOCRED) { 2000 crfree(bp->b_wcred); 2001 bp->b_wcred = NOCRED; 2002 } 2003 if (!LIST_EMPTY(&bp->b_dep)) 2004 buf_deallocate(bp); 2005 if (bp->b_vflags & BV_BKGRDINPROG) 2006 panic("losing buffer 3"); 2007 KASSERT(bp->b_vp == NULL, 2008 ("bp: %p still has vnode %p. qindex: %d", 2009 bp, bp->b_vp, qindex)); 2010 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2011 ("bp: %p still on a buffer list. xflags %X", 2012 bp, bp->b_xflags)); 2013 2014 if (bp->b_bufsize) 2015 allocbuf(bp, 0); 2016 2017 bp->b_flags = 0; 2018 bp->b_ioflags = 0; 2019 bp->b_xflags = 0; 2020 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 2021 ("buf %p still counted as free?", bp)); 2022 bp->b_vflags = 0; 2023 bp->b_vp = NULL; 2024 bp->b_blkno = bp->b_lblkno = 0; 2025 bp->b_offset = NOOFFSET; 2026 bp->b_iodone = 0; 2027 bp->b_error = 0; 2028 bp->b_resid = 0; 2029 bp->b_bcount = 0; 2030 bp->b_npages = 0; 2031 bp->b_dirtyoff = bp->b_dirtyend = 0; 2032 bp->b_bufobj = NULL; 2033 bp->b_pin_count = 0; 2034 bp->b_fsprivate1 = NULL; 2035 bp->b_fsprivate2 = NULL; 2036 bp->b_fsprivate3 = NULL; 2037 2038 LIST_INIT(&bp->b_dep); 2039 2040 /* 2041 * If we are defragging then free the buffer. 2042 */ 2043 if (defrag) { 2044 bp->b_flags |= B_INVAL; 2045 bfreekva(bp); 2046 brelse(bp); 2047 defrag = 0; 2048 goto restart; 2049 } 2050 2051 /* 2052 * Notify any waiters for the buffer lock about 2053 * identity change by freeing the buffer. 2054 */ 2055 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2056 bp->b_flags |= B_INVAL; 2057 bfreekva(bp); 2058 brelse(bp); 2059 goto restart; 2060 } 2061 2062 /* 2063 * If we are overcomitted then recover the buffer and its 2064 * KVM space. This occurs in rare situations when multiple 2065 * processes are blocked in getnewbuf() or allocbuf(). 2066 */ 2067 if (bufspace >= hibufspace) 2068 flushingbufs = 1; 2069 if (flushingbufs && bp->b_kvasize != 0) { 2070 bp->b_flags |= B_INVAL; 2071 bfreekva(bp); 2072 brelse(bp); 2073 goto restart; 2074 } 2075 if (bufspace < lobufspace) 2076 flushingbufs = 0; 2077 break; 2078 } 2079 2080 /* 2081 * If we exhausted our list, sleep as appropriate. We may have to 2082 * wakeup various daemons and write out some dirty buffers. 2083 * 2084 * Generally we are sleeping due to insufficient buffer space. 2085 */ 2086 2087 if (bp == NULL) { 2088 int flags, norunbuf; 2089 char *waitmsg; 2090 int fl; 2091 2092 if (defrag) { 2093 flags = VFS_BIO_NEED_BUFSPACE; 2094 waitmsg = "nbufkv"; 2095 } else if (bufspace >= hibufspace) { 2096 waitmsg = "nbufbs"; 2097 flags = VFS_BIO_NEED_BUFSPACE; 2098 } else { 2099 waitmsg = "newbuf"; 2100 flags = VFS_BIO_NEED_ANY; 2101 } 2102 mtx_lock(&nblock); 2103 needsbuffer |= flags; 2104 mtx_unlock(&nblock); 2105 mtx_unlock(&bqlock); 2106 2107 bd_speedup(); /* heeeelp */ 2108 if (gbflags & GB_NOWAIT_BD) 2109 return (NULL); 2110 2111 mtx_lock(&nblock); 2112 while (needsbuffer & flags) { 2113 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2114 mtx_unlock(&nblock); 2115 /* 2116 * getblk() is called with a vnode 2117 * locked, and some majority of the 2118 * dirty buffers may as well belong to 2119 * the vnode. Flushing the buffers 2120 * there would make a progress that 2121 * cannot be achieved by the 2122 * buf_daemon, that cannot lock the 2123 * vnode. 2124 */ 2125 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2126 (td->td_pflags & TDP_NORUNNINGBUF); 2127 /* play bufdaemon */ 2128 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2129 fl = buf_do_flush(vp); 2130 td->td_pflags &= norunbuf; 2131 mtx_lock(&nblock); 2132 if (fl != 0) 2133 continue; 2134 if ((needsbuffer & flags) == 0) 2135 break; 2136 } 2137 if (msleep(&needsbuffer, &nblock, 2138 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2139 mtx_unlock(&nblock); 2140 return (NULL); 2141 } 2142 } 2143 mtx_unlock(&nblock); 2144 } else { 2145 /* 2146 * We finally have a valid bp. We aren't quite out of the 2147 * woods, we still have to reserve kva space. In order 2148 * to keep fragmentation sane we only allocate kva in 2149 * BKVASIZE chunks. 2150 */ 2151 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2152 2153 if (maxsize != bp->b_kvasize) { 2154 vm_offset_t addr = 0; 2155 int rv; 2156 2157 bfreekva(bp); 2158 2159 vm_map_lock(buffer_map); 2160 if (vm_map_findspace(buffer_map, 2161 vm_map_min(buffer_map), maxsize, &addr)) { 2162 /* 2163 * Buffer map is too fragmented. 2164 * We must defragment the map. 2165 */ 2166 atomic_add_int(&bufdefragcnt, 1); 2167 vm_map_unlock(buffer_map); 2168 defrag = 1; 2169 bp->b_flags |= B_INVAL; 2170 brelse(bp); 2171 goto restart; 2172 } 2173 rv = vm_map_insert(buffer_map, NULL, 0, addr, 2174 addr + maxsize, VM_PROT_ALL, VM_PROT_ALL, 2175 MAP_NOFAULT); 2176 KASSERT(rv == KERN_SUCCESS, 2177 ("vm_map_insert(buffer_map) rv %d", rv)); 2178 vm_map_unlock(buffer_map); 2179 bp->b_kvabase = (caddr_t)addr; 2180 bp->b_kvasize = maxsize; 2181 atomic_add_long(&bufspace, bp->b_kvasize); 2182 atomic_add_int(&bufreusecnt, 1); 2183 } 2184 bp->b_saveaddr = bp->b_kvabase; 2185 bp->b_data = bp->b_saveaddr; 2186 } 2187 return (bp); 2188 } 2189 2190 /* 2191 * buf_daemon: 2192 * 2193 * buffer flushing daemon. Buffers are normally flushed by the 2194 * update daemon but if it cannot keep up this process starts to 2195 * take the load in an attempt to prevent getnewbuf() from blocking. 2196 */ 2197 2198 static struct kproc_desc buf_kp = { 2199 "bufdaemon", 2200 buf_daemon, 2201 &bufdaemonproc 2202 }; 2203 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2204 2205 static int 2206 buf_do_flush(struct vnode *vp) 2207 { 2208 int flushed; 2209 2210 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2211 if (flushed == 0) { 2212 /* 2213 * Could not find any buffers without rollback 2214 * dependencies, so just write the first one 2215 * in the hopes of eventually making progress. 2216 */ 2217 flushbufqueues(vp, QUEUE_DIRTY, 1); 2218 } 2219 return (flushed); 2220 } 2221 2222 static void 2223 buf_daemon() 2224 { 2225 int lodirtysave; 2226 2227 /* 2228 * This process needs to be suspended prior to shutdown sync. 2229 */ 2230 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2231 SHUTDOWN_PRI_LAST); 2232 2233 /* 2234 * This process is allowed to take the buffer cache to the limit 2235 */ 2236 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2237 mtx_lock(&bdlock); 2238 for (;;) { 2239 bd_request = 0; 2240 mtx_unlock(&bdlock); 2241 2242 kproc_suspend_check(bufdaemonproc); 2243 lodirtysave = lodirtybuffers; 2244 if (bd_speedupreq) { 2245 lodirtybuffers = numdirtybuffers / 2; 2246 bd_speedupreq = 0; 2247 } 2248 /* 2249 * Do the flush. Limit the amount of in-transit I/O we 2250 * allow to build up, otherwise we would completely saturate 2251 * the I/O system. Wakeup any waiting processes before we 2252 * normally would so they can run in parallel with our drain. 2253 */ 2254 while (numdirtybuffers > lodirtybuffers) { 2255 if (buf_do_flush(NULL) == 0) 2256 break; 2257 kern_yield(PRI_USER); 2258 } 2259 lodirtybuffers = lodirtysave; 2260 2261 /* 2262 * Only clear bd_request if we have reached our low water 2263 * mark. The buf_daemon normally waits 1 second and 2264 * then incrementally flushes any dirty buffers that have 2265 * built up, within reason. 2266 * 2267 * If we were unable to hit our low water mark and couldn't 2268 * find any flushable buffers, we sleep half a second. 2269 * Otherwise we loop immediately. 2270 */ 2271 mtx_lock(&bdlock); 2272 if (numdirtybuffers <= lodirtybuffers) { 2273 /* 2274 * We reached our low water mark, reset the 2275 * request and sleep until we are needed again. 2276 * The sleep is just so the suspend code works. 2277 */ 2278 bd_request = 0; 2279 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2280 } else { 2281 /* 2282 * We couldn't find any flushable dirty buffers but 2283 * still have too many dirty buffers, we 2284 * have to sleep and try again. (rare) 2285 */ 2286 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2287 } 2288 } 2289 } 2290 2291 /* 2292 * flushbufqueues: 2293 * 2294 * Try to flush a buffer in the dirty queue. We must be careful to 2295 * free up B_INVAL buffers instead of write them, which NFS is 2296 * particularly sensitive to. 2297 */ 2298 static int flushwithdeps = 0; 2299 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2300 0, "Number of buffers flushed with dependecies that require rollbacks"); 2301 2302 static int 2303 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2304 { 2305 struct buf *sentinel; 2306 struct vnode *vp; 2307 struct mount *mp; 2308 struct buf *bp; 2309 int hasdeps; 2310 int flushed; 2311 int target; 2312 2313 if (lvp == NULL) { 2314 target = numdirtybuffers - lodirtybuffers; 2315 if (flushdeps && target > 2) 2316 target /= 2; 2317 } else 2318 target = flushbufqtarget; 2319 flushed = 0; 2320 bp = NULL; 2321 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2322 sentinel->b_qindex = QUEUE_SENTINEL; 2323 mtx_lock(&bqlock); 2324 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2325 while (flushed != target) { 2326 bp = TAILQ_NEXT(sentinel, b_freelist); 2327 if (bp != NULL) { 2328 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2329 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2330 b_freelist); 2331 } else 2332 break; 2333 /* 2334 * Skip sentinels inserted by other invocations of the 2335 * flushbufqueues(), taking care to not reorder them. 2336 */ 2337 if (bp->b_qindex == QUEUE_SENTINEL) 2338 continue; 2339 /* 2340 * Only flush the buffers that belong to the 2341 * vnode locked by the curthread. 2342 */ 2343 if (lvp != NULL && bp->b_vp != lvp) 2344 continue; 2345 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2346 continue; 2347 if (bp->b_pin_count > 0) { 2348 BUF_UNLOCK(bp); 2349 continue; 2350 } 2351 BO_LOCK(bp->b_bufobj); 2352 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2353 (bp->b_flags & B_DELWRI) == 0) { 2354 BO_UNLOCK(bp->b_bufobj); 2355 BUF_UNLOCK(bp); 2356 continue; 2357 } 2358 BO_UNLOCK(bp->b_bufobj); 2359 if (bp->b_flags & B_INVAL) { 2360 bremfreel(bp); 2361 mtx_unlock(&bqlock); 2362 brelse(bp); 2363 flushed++; 2364 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2365 mtx_lock(&bqlock); 2366 continue; 2367 } 2368 2369 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2370 if (flushdeps == 0) { 2371 BUF_UNLOCK(bp); 2372 continue; 2373 } 2374 hasdeps = 1; 2375 } else 2376 hasdeps = 0; 2377 /* 2378 * We must hold the lock on a vnode before writing 2379 * one of its buffers. Otherwise we may confuse, or 2380 * in the case of a snapshot vnode, deadlock the 2381 * system. 2382 * 2383 * The lock order here is the reverse of the normal 2384 * of vnode followed by buf lock. This is ok because 2385 * the NOWAIT will prevent deadlock. 2386 */ 2387 vp = bp->b_vp; 2388 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2389 BUF_UNLOCK(bp); 2390 continue; 2391 } 2392 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2393 mtx_unlock(&bqlock); 2394 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2395 bp, bp->b_vp, bp->b_flags); 2396 if (curproc == bufdaemonproc) 2397 vfs_bio_awrite(bp); 2398 else { 2399 bremfree(bp); 2400 bwrite(bp); 2401 notbufdflashes++; 2402 } 2403 vn_finished_write(mp); 2404 VOP_UNLOCK(vp, 0); 2405 flushwithdeps += hasdeps; 2406 flushed++; 2407 2408 /* 2409 * Sleeping on runningbufspace while holding 2410 * vnode lock leads to deadlock. 2411 */ 2412 if (curproc == bufdaemonproc) 2413 waitrunningbufspace(); 2414 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2415 mtx_lock(&bqlock); 2416 continue; 2417 } 2418 vn_finished_write(mp); 2419 BUF_UNLOCK(bp); 2420 } 2421 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2422 mtx_unlock(&bqlock); 2423 free(sentinel, M_TEMP); 2424 return (flushed); 2425 } 2426 2427 /* 2428 * Check to see if a block is currently memory resident. 2429 */ 2430 struct buf * 2431 incore(struct bufobj *bo, daddr_t blkno) 2432 { 2433 struct buf *bp; 2434 2435 BO_LOCK(bo); 2436 bp = gbincore(bo, blkno); 2437 BO_UNLOCK(bo); 2438 return (bp); 2439 } 2440 2441 /* 2442 * Returns true if no I/O is needed to access the 2443 * associated VM object. This is like incore except 2444 * it also hunts around in the VM system for the data. 2445 */ 2446 2447 static int 2448 inmem(struct vnode * vp, daddr_t blkno) 2449 { 2450 vm_object_t obj; 2451 vm_offset_t toff, tinc, size; 2452 vm_page_t m; 2453 vm_ooffset_t off; 2454 2455 ASSERT_VOP_LOCKED(vp, "inmem"); 2456 2457 if (incore(&vp->v_bufobj, blkno)) 2458 return 1; 2459 if (vp->v_mount == NULL) 2460 return 0; 2461 obj = vp->v_object; 2462 if (obj == NULL) 2463 return (0); 2464 2465 size = PAGE_SIZE; 2466 if (size > vp->v_mount->mnt_stat.f_iosize) 2467 size = vp->v_mount->mnt_stat.f_iosize; 2468 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2469 2470 VM_OBJECT_LOCK(obj); 2471 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2472 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2473 if (!m) 2474 goto notinmem; 2475 tinc = size; 2476 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2477 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2478 if (vm_page_is_valid(m, 2479 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2480 goto notinmem; 2481 } 2482 VM_OBJECT_UNLOCK(obj); 2483 return 1; 2484 2485 notinmem: 2486 VM_OBJECT_UNLOCK(obj); 2487 return (0); 2488 } 2489 2490 /* 2491 * Set the dirty range for a buffer based on the status of the dirty 2492 * bits in the pages comprising the buffer. The range is limited 2493 * to the size of the buffer. 2494 * 2495 * Tell the VM system that the pages associated with this buffer 2496 * are clean. This is used for delayed writes where the data is 2497 * going to go to disk eventually without additional VM intevention. 2498 * 2499 * Note that while we only really need to clean through to b_bcount, we 2500 * just go ahead and clean through to b_bufsize. 2501 */ 2502 static void 2503 vfs_clean_pages_dirty_buf(struct buf *bp) 2504 { 2505 vm_ooffset_t foff, noff, eoff; 2506 vm_page_t m; 2507 int i; 2508 2509 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2510 return; 2511 2512 foff = bp->b_offset; 2513 KASSERT(bp->b_offset != NOOFFSET, 2514 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2515 2516 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2517 vfs_drain_busy_pages(bp); 2518 vfs_setdirty_locked_object(bp); 2519 for (i = 0; i < bp->b_npages; i++) { 2520 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2521 eoff = noff; 2522 if (eoff > bp->b_offset + bp->b_bufsize) 2523 eoff = bp->b_offset + bp->b_bufsize; 2524 m = bp->b_pages[i]; 2525 vfs_page_set_validclean(bp, foff, m); 2526 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2527 foff = noff; 2528 } 2529 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2530 } 2531 2532 static void 2533 vfs_setdirty_locked_object(struct buf *bp) 2534 { 2535 vm_object_t object; 2536 int i; 2537 2538 object = bp->b_bufobj->bo_object; 2539 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2540 2541 /* 2542 * We qualify the scan for modified pages on whether the 2543 * object has been flushed yet. 2544 */ 2545 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2546 vm_offset_t boffset; 2547 vm_offset_t eoffset; 2548 2549 /* 2550 * test the pages to see if they have been modified directly 2551 * by users through the VM system. 2552 */ 2553 for (i = 0; i < bp->b_npages; i++) 2554 vm_page_test_dirty(bp->b_pages[i]); 2555 2556 /* 2557 * Calculate the encompassing dirty range, boffset and eoffset, 2558 * (eoffset - boffset) bytes. 2559 */ 2560 2561 for (i = 0; i < bp->b_npages; i++) { 2562 if (bp->b_pages[i]->dirty) 2563 break; 2564 } 2565 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2566 2567 for (i = bp->b_npages - 1; i >= 0; --i) { 2568 if (bp->b_pages[i]->dirty) { 2569 break; 2570 } 2571 } 2572 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2573 2574 /* 2575 * Fit it to the buffer. 2576 */ 2577 2578 if (eoffset > bp->b_bcount) 2579 eoffset = bp->b_bcount; 2580 2581 /* 2582 * If we have a good dirty range, merge with the existing 2583 * dirty range. 2584 */ 2585 2586 if (boffset < eoffset) { 2587 if (bp->b_dirtyoff > boffset) 2588 bp->b_dirtyoff = boffset; 2589 if (bp->b_dirtyend < eoffset) 2590 bp->b_dirtyend = eoffset; 2591 } 2592 } 2593 } 2594 2595 /* 2596 * getblk: 2597 * 2598 * Get a block given a specified block and offset into a file/device. 2599 * The buffers B_DONE bit will be cleared on return, making it almost 2600 * ready for an I/O initiation. B_INVAL may or may not be set on 2601 * return. The caller should clear B_INVAL prior to initiating a 2602 * READ. 2603 * 2604 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2605 * an existing buffer. 2606 * 2607 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2608 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2609 * and then cleared based on the backing VM. If the previous buffer is 2610 * non-0-sized but invalid, B_CACHE will be cleared. 2611 * 2612 * If getblk() must create a new buffer, the new buffer is returned with 2613 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2614 * case it is returned with B_INVAL clear and B_CACHE set based on the 2615 * backing VM. 2616 * 2617 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2618 * B_CACHE bit is clear. 2619 * 2620 * What this means, basically, is that the caller should use B_CACHE to 2621 * determine whether the buffer is fully valid or not and should clear 2622 * B_INVAL prior to issuing a read. If the caller intends to validate 2623 * the buffer by loading its data area with something, the caller needs 2624 * to clear B_INVAL. If the caller does this without issuing an I/O, 2625 * the caller should set B_CACHE ( as an optimization ), else the caller 2626 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2627 * a write attempt or if it was a successfull read. If the caller 2628 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2629 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2630 */ 2631 struct buf * 2632 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2633 int flags) 2634 { 2635 struct buf *bp; 2636 struct bufobj *bo; 2637 int error; 2638 2639 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2640 ASSERT_VOP_LOCKED(vp, "getblk"); 2641 if (size > MAXBSIZE) 2642 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2643 2644 bo = &vp->v_bufobj; 2645 loop: 2646 /* 2647 * Block if we are low on buffers. Certain processes are allowed 2648 * to completely exhaust the buffer cache. 2649 * 2650 * If this check ever becomes a bottleneck it may be better to 2651 * move it into the else, when gbincore() fails. At the moment 2652 * it isn't a problem. 2653 */ 2654 if (numfreebuffers == 0) { 2655 if (TD_IS_IDLETHREAD(curthread)) 2656 return NULL; 2657 mtx_lock(&nblock); 2658 needsbuffer |= VFS_BIO_NEED_ANY; 2659 mtx_unlock(&nblock); 2660 } 2661 2662 BO_LOCK(bo); 2663 bp = gbincore(bo, blkno); 2664 if (bp != NULL) { 2665 int lockflags; 2666 /* 2667 * Buffer is in-core. If the buffer is not busy nor managed, 2668 * it must be on a queue. 2669 */ 2670 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2671 2672 if (flags & GB_LOCK_NOWAIT) 2673 lockflags |= LK_NOWAIT; 2674 2675 error = BUF_TIMELOCK(bp, lockflags, 2676 BO_MTX(bo), "getblk", slpflag, slptimeo); 2677 2678 /* 2679 * If we slept and got the lock we have to restart in case 2680 * the buffer changed identities. 2681 */ 2682 if (error == ENOLCK) 2683 goto loop; 2684 /* We timed out or were interrupted. */ 2685 else if (error) 2686 return (NULL); 2687 /* If recursed, assume caller knows the rules. */ 2688 else if (BUF_LOCKRECURSED(bp)) 2689 goto end; 2690 2691 /* 2692 * The buffer is locked. B_CACHE is cleared if the buffer is 2693 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2694 * and for a VMIO buffer B_CACHE is adjusted according to the 2695 * backing VM cache. 2696 */ 2697 if (bp->b_flags & B_INVAL) 2698 bp->b_flags &= ~B_CACHE; 2699 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2700 bp->b_flags |= B_CACHE; 2701 if (bp->b_flags & B_MANAGED) 2702 MPASS(bp->b_qindex == QUEUE_NONE); 2703 else { 2704 BO_LOCK(bo); 2705 bremfree(bp); 2706 BO_UNLOCK(bo); 2707 } 2708 2709 /* 2710 * check for size inconsistancies for non-VMIO case. 2711 */ 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_LOCK(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_UNLOCK(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_LOCK(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_UNLOCK(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_LOCK(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_UNLOCK(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_LOCK(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_UNLOCK(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_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED); 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_LOCK(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_UNLOCK(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_LOCK(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_UNLOCK(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; 3715 caddr_t sa, ea; 3716 3717 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3718 clrbuf(bp); 3719 return; 3720 } 3721 bp->b_flags &= ~B_INVAL; 3722 bp->b_ioflags &= ~BIO_ERROR; 3723 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3724 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3725 (bp->b_offset & PAGE_MASK) == 0) { 3726 if (bp->b_pages[0] == bogus_page) 3727 goto unlock; 3728 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3729 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3730 if ((bp->b_pages[0]->valid & mask) == mask) 3731 goto unlock; 3732 if ((bp->b_pages[0]->valid & mask) == 0) { 3733 bzero(bp->b_data, bp->b_bufsize); 3734 bp->b_pages[0]->valid |= mask; 3735 goto unlock; 3736 } 3737 } 3738 ea = sa = bp->b_data; 3739 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3740 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3741 ea = (caddr_t)(vm_offset_t)ulmin( 3742 (u_long)(vm_offset_t)ea, 3743 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3744 if (bp->b_pages[i] == bogus_page) 3745 continue; 3746 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3747 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3748 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3749 if ((bp->b_pages[i]->valid & mask) == mask) 3750 continue; 3751 if ((bp->b_pages[i]->valid & mask) == 0) 3752 bzero(sa, ea - sa); 3753 else { 3754 for (; sa < ea; sa += DEV_BSIZE, j++) { 3755 if ((bp->b_pages[i]->valid & (1 << j)) == 0) 3756 bzero(sa, DEV_BSIZE); 3757 } 3758 } 3759 bp->b_pages[i]->valid |= mask; 3760 } 3761 unlock: 3762 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3763 bp->b_resid = 0; 3764 } 3765 3766 /* 3767 * vm_hold_load_pages and vm_hold_free_pages get pages into 3768 * a buffers address space. The pages are anonymous and are 3769 * not associated with a file object. 3770 */ 3771 static void 3772 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3773 { 3774 vm_offset_t pg; 3775 vm_page_t p; 3776 int index; 3777 3778 to = round_page(to); 3779 from = round_page(from); 3780 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3781 3782 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3783 tryagain: 3784 /* 3785 * note: must allocate system pages since blocking here 3786 * could interfere with paging I/O, no matter which 3787 * process we are. 3788 */ 3789 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 3790 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 3791 if (p == NULL) { 3792 VM_WAIT; 3793 goto tryagain; 3794 } 3795 pmap_qenter(pg, &p, 1); 3796 bp->b_pages[index] = p; 3797 } 3798 bp->b_npages = index; 3799 } 3800 3801 /* Return pages associated with this buf to the vm system */ 3802 static void 3803 vm_hold_free_pages(struct buf *bp, int newbsize) 3804 { 3805 vm_offset_t from; 3806 vm_page_t p; 3807 int index, newnpages; 3808 3809 from = round_page((vm_offset_t)bp->b_data + newbsize); 3810 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3811 if (bp->b_npages > newnpages) 3812 pmap_qremove(from, bp->b_npages - newnpages); 3813 for (index = newnpages; index < bp->b_npages; index++) { 3814 p = bp->b_pages[index]; 3815 bp->b_pages[index] = NULL; 3816 if (p->busy != 0) 3817 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3818 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 3819 p->wire_count--; 3820 vm_page_free(p); 3821 atomic_subtract_int(&cnt.v_wire_count, 1); 3822 } 3823 bp->b_npages = newnpages; 3824 } 3825 3826 /* 3827 * Map an IO request into kernel virtual address space. 3828 * 3829 * All requests are (re)mapped into kernel VA space. 3830 * Notice that we use b_bufsize for the size of the buffer 3831 * to be mapped. b_bcount might be modified by the driver. 3832 * 3833 * Note that even if the caller determines that the address space should 3834 * be valid, a race or a smaller-file mapped into a larger space may 3835 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3836 * check the return value. 3837 */ 3838 int 3839 vmapbuf(struct buf *bp) 3840 { 3841 caddr_t kva; 3842 vm_prot_t prot; 3843 int pidx; 3844 3845 if (bp->b_bufsize < 0) 3846 return (-1); 3847 prot = VM_PROT_READ; 3848 if (bp->b_iocmd == BIO_READ) 3849 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3850 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 3851 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 3852 btoc(MAXPHYS))) < 0) 3853 return (-1); 3854 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3855 3856 kva = bp->b_saveaddr; 3857 bp->b_npages = pidx; 3858 bp->b_saveaddr = bp->b_data; 3859 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3860 return(0); 3861 } 3862 3863 /* 3864 * Free the io map PTEs associated with this IO operation. 3865 * We also invalidate the TLB entries and restore the original b_addr. 3866 */ 3867 void 3868 vunmapbuf(struct buf *bp) 3869 { 3870 int npages; 3871 3872 npages = bp->b_npages; 3873 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3874 vm_page_unhold_pages(bp->b_pages, npages); 3875 3876 bp->b_data = bp->b_saveaddr; 3877 } 3878 3879 void 3880 bdone(struct buf *bp) 3881 { 3882 struct mtx *mtxp; 3883 3884 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3885 mtx_lock(mtxp); 3886 bp->b_flags |= B_DONE; 3887 wakeup(bp); 3888 mtx_unlock(mtxp); 3889 } 3890 3891 void 3892 bwait(struct buf *bp, u_char pri, const char *wchan) 3893 { 3894 struct mtx *mtxp; 3895 3896 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3897 mtx_lock(mtxp); 3898 while ((bp->b_flags & B_DONE) == 0) 3899 msleep(bp, mtxp, pri, wchan, 0); 3900 mtx_unlock(mtxp); 3901 } 3902 3903 int 3904 bufsync(struct bufobj *bo, int waitfor) 3905 { 3906 3907 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3908 } 3909 3910 void 3911 bufstrategy(struct bufobj *bo, struct buf *bp) 3912 { 3913 int i = 0; 3914 struct vnode *vp; 3915 3916 vp = bp->b_vp; 3917 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3918 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3919 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3920 i = VOP_STRATEGY(vp, bp); 3921 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3922 } 3923 3924 void 3925 bufobj_wrefl(struct bufobj *bo) 3926 { 3927 3928 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3929 ASSERT_BO_LOCKED(bo); 3930 bo->bo_numoutput++; 3931 } 3932 3933 void 3934 bufobj_wref(struct bufobj *bo) 3935 { 3936 3937 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3938 BO_LOCK(bo); 3939 bo->bo_numoutput++; 3940 BO_UNLOCK(bo); 3941 } 3942 3943 void 3944 bufobj_wdrop(struct bufobj *bo) 3945 { 3946 3947 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3948 BO_LOCK(bo); 3949 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3950 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3951 bo->bo_flag &= ~BO_WWAIT; 3952 wakeup(&bo->bo_numoutput); 3953 } 3954 BO_UNLOCK(bo); 3955 } 3956 3957 int 3958 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3959 { 3960 int error; 3961 3962 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3963 ASSERT_BO_LOCKED(bo); 3964 error = 0; 3965 while (bo->bo_numoutput) { 3966 bo->bo_flag |= BO_WWAIT; 3967 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3968 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3969 if (error) 3970 break; 3971 } 3972 return (error); 3973 } 3974 3975 void 3976 bpin(struct buf *bp) 3977 { 3978 struct mtx *mtxp; 3979 3980 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3981 mtx_lock(mtxp); 3982 bp->b_pin_count++; 3983 mtx_unlock(mtxp); 3984 } 3985 3986 void 3987 bunpin(struct buf *bp) 3988 { 3989 struct mtx *mtxp; 3990 3991 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3992 mtx_lock(mtxp); 3993 if (--bp->b_pin_count == 0) 3994 wakeup(bp); 3995 mtx_unlock(mtxp); 3996 } 3997 3998 void 3999 bunpin_wait(struct buf *bp) 4000 { 4001 struct mtx *mtxp; 4002 4003 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4004 mtx_lock(mtxp); 4005 while (bp->b_pin_count > 0) 4006 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4007 mtx_unlock(mtxp); 4008 } 4009 4010 #include "opt_ddb.h" 4011 #ifdef DDB 4012 #include <ddb/ddb.h> 4013 4014 /* DDB command to show buffer data */ 4015 DB_SHOW_COMMAND(buffer, db_show_buffer) 4016 { 4017 /* get args */ 4018 struct buf *bp = (struct buf *)addr; 4019 4020 if (!have_addr) { 4021 db_printf("usage: show buffer <addr>\n"); 4022 return; 4023 } 4024 4025 db_printf("buf at %p\n", bp); 4026 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4027 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4028 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4029 db_printf( 4030 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4031 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4032 "b_dep = %p\n", 4033 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4034 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4035 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4036 if (bp->b_npages) { 4037 int i; 4038 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4039 for (i = 0; i < bp->b_npages; i++) { 4040 vm_page_t m; 4041 m = bp->b_pages[i]; 4042 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4043 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4044 if ((i + 1) < bp->b_npages) 4045 db_printf(","); 4046 } 4047 db_printf("\n"); 4048 } 4049 db_printf(" "); 4050 BUF_LOCKPRINTINFO(bp); 4051 } 4052 4053 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4054 { 4055 struct buf *bp; 4056 int i; 4057 4058 for (i = 0; i < nbuf; i++) { 4059 bp = &buf[i]; 4060 if (BUF_ISLOCKED(bp)) { 4061 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4062 db_printf("\n"); 4063 } 4064 } 4065 } 4066 4067 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4068 { 4069 struct vnode *vp; 4070 struct buf *bp; 4071 4072 if (!have_addr) { 4073 db_printf("usage: show vnodebufs <addr>\n"); 4074 return; 4075 } 4076 vp = (struct vnode *)addr; 4077 db_printf("Clean buffers:\n"); 4078 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4079 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4080 db_printf("\n"); 4081 } 4082 db_printf("Dirty buffers:\n"); 4083 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4084 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4085 db_printf("\n"); 4086 } 4087 } 4088 4089 DB_COMMAND(countfreebufs, db_coundfreebufs) 4090 { 4091 struct buf *bp; 4092 int i, used = 0, nfree = 0; 4093 4094 if (have_addr) { 4095 db_printf("usage: countfreebufs\n"); 4096 return; 4097 } 4098 4099 for (i = 0; i < nbuf; i++) { 4100 bp = &buf[i]; 4101 if ((bp->b_vflags & BV_INFREECNT) != 0) 4102 nfree++; 4103 else 4104 used++; 4105 } 4106 4107 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4108 nfree + used); 4109 db_printf("numfreebuffers is %d\n", numfreebuffers); 4110 } 4111 #endif /* DDB */ 4112