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 (bp->b_flags & B_MANAGED) { 1272 bqrelse(bp); 1273 return; 1274 } 1275 1276 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1277 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1278 /* 1279 * Failed write, redirty. Must clear BIO_ERROR to prevent 1280 * pages from being scrapped. If the error is anything 1281 * other than an I/O error (EIO), assume that retrying 1282 * is futile. 1283 */ 1284 bp->b_ioflags &= ~BIO_ERROR; 1285 bdirty(bp); 1286 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1287 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1288 /* 1289 * Either a failed I/O or we were asked to free or not 1290 * cache the buffer. 1291 */ 1292 bp->b_flags |= B_INVAL; 1293 if (!LIST_EMPTY(&bp->b_dep)) 1294 buf_deallocate(bp); 1295 if (bp->b_flags & B_DELWRI) { 1296 atomic_subtract_int(&numdirtybuffers, 1); 1297 numdirtywakeup(lodirtybuffers); 1298 } 1299 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1300 if ((bp->b_flags & B_VMIO) == 0) { 1301 if (bp->b_bufsize) 1302 allocbuf(bp, 0); 1303 if (bp->b_vp) 1304 brelvp(bp); 1305 } 1306 } 1307 1308 /* 1309 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1310 * is called with B_DELWRI set, the underlying pages may wind up 1311 * getting freed causing a previous write (bdwrite()) to get 'lost' 1312 * because pages associated with a B_DELWRI bp are marked clean. 1313 * 1314 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1315 * if B_DELWRI is set. 1316 * 1317 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1318 * on pages to return pages to the VM page queues. 1319 */ 1320 if (bp->b_flags & B_DELWRI) 1321 bp->b_flags &= ~B_RELBUF; 1322 else if (buf_vm_page_count_severe()) { 1323 /* 1324 * The locking of the BO_LOCK is not necessary since 1325 * BKGRDINPROG cannot be set while we hold the buf 1326 * lock, it can only be cleared if it is already 1327 * pending. 1328 */ 1329 if (bp->b_vp) { 1330 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1331 bp->b_flags |= B_RELBUF; 1332 } else 1333 bp->b_flags |= B_RELBUF; 1334 } 1335 1336 /* 1337 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1338 * constituted, not even NFS buffers now. Two flags effect this. If 1339 * B_INVAL, the struct buf is invalidated but the VM object is kept 1340 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1341 * 1342 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1343 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1344 * buffer is also B_INVAL because it hits the re-dirtying code above. 1345 * 1346 * Normally we can do this whether a buffer is B_DELWRI or not. If 1347 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1348 * the commit state and we cannot afford to lose the buffer. If the 1349 * buffer has a background write in progress, we need to keep it 1350 * around to prevent it from being reconstituted and starting a second 1351 * background write. 1352 */ 1353 if ((bp->b_flags & B_VMIO) 1354 && !(bp->b_vp->v_mount != NULL && 1355 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1356 !vn_isdisk(bp->b_vp, NULL) && 1357 (bp->b_flags & B_DELWRI)) 1358 ) { 1359 1360 int i, j, resid; 1361 vm_page_t m; 1362 off_t foff; 1363 vm_pindex_t poff; 1364 vm_object_t obj; 1365 1366 obj = bp->b_bufobj->bo_object; 1367 1368 /* 1369 * Get the base offset and length of the buffer. Note that 1370 * in the VMIO case if the buffer block size is not 1371 * page-aligned then b_data pointer may not be page-aligned. 1372 * But our b_pages[] array *IS* page aligned. 1373 * 1374 * block sizes less then DEV_BSIZE (usually 512) are not 1375 * supported due to the page granularity bits (m->valid, 1376 * m->dirty, etc...). 1377 * 1378 * See man buf(9) for more information 1379 */ 1380 resid = bp->b_bufsize; 1381 foff = bp->b_offset; 1382 VM_OBJECT_LOCK(obj); 1383 for (i = 0; i < bp->b_npages; i++) { 1384 int had_bogus = 0; 1385 1386 m = bp->b_pages[i]; 1387 1388 /* 1389 * If we hit a bogus page, fixup *all* the bogus pages 1390 * now. 1391 */ 1392 if (m == bogus_page) { 1393 poff = OFF_TO_IDX(bp->b_offset); 1394 had_bogus = 1; 1395 1396 for (j = i; j < bp->b_npages; j++) { 1397 vm_page_t mtmp; 1398 mtmp = bp->b_pages[j]; 1399 if (mtmp == bogus_page) { 1400 mtmp = vm_page_lookup(obj, poff + j); 1401 if (!mtmp) { 1402 panic("brelse: page missing\n"); 1403 } 1404 bp->b_pages[j] = mtmp; 1405 } 1406 } 1407 1408 if ((bp->b_flags & B_INVAL) == 0) { 1409 pmap_qenter( 1410 trunc_page((vm_offset_t)bp->b_data), 1411 bp->b_pages, bp->b_npages); 1412 } 1413 m = bp->b_pages[i]; 1414 } 1415 if ((bp->b_flags & B_NOCACHE) || 1416 (bp->b_ioflags & BIO_ERROR && 1417 bp->b_iocmd == BIO_READ)) { 1418 int poffset = foff & PAGE_MASK; 1419 int presid = resid > (PAGE_SIZE - poffset) ? 1420 (PAGE_SIZE - poffset) : resid; 1421 1422 KASSERT(presid >= 0, ("brelse: extra page")); 1423 vm_page_set_invalid(m, poffset, presid); 1424 if (had_bogus) 1425 printf("avoided corruption bug in bogus_page/brelse code\n"); 1426 } 1427 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1428 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1429 } 1430 VM_OBJECT_UNLOCK(obj); 1431 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1432 vfs_vmio_release(bp); 1433 1434 } else if (bp->b_flags & B_VMIO) { 1435 1436 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1437 vfs_vmio_release(bp); 1438 } 1439 1440 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1441 if (bp->b_bufsize != 0) 1442 allocbuf(bp, 0); 1443 if (bp->b_vp != NULL) 1444 brelvp(bp); 1445 } 1446 1447 if (BUF_LOCKRECURSED(bp)) { 1448 /* do not release to free list */ 1449 BUF_UNLOCK(bp); 1450 return; 1451 } 1452 1453 /* enqueue */ 1454 mtx_lock(&bqlock); 1455 /* Handle delayed bremfree() processing. */ 1456 if (bp->b_flags & B_REMFREE) { 1457 struct bufobj *bo; 1458 1459 bo = bp->b_bufobj; 1460 if (bo != NULL) 1461 BO_LOCK(bo); 1462 bremfreel(bp); 1463 if (bo != NULL) 1464 BO_UNLOCK(bo); 1465 } 1466 if (bp->b_qindex != QUEUE_NONE) 1467 panic("brelse: free buffer onto another queue???"); 1468 1469 /* 1470 * If the buffer has junk contents signal it and eventually 1471 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1472 * doesn't find it. 1473 */ 1474 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1475 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1476 bp->b_flags |= B_INVAL; 1477 if (bp->b_flags & B_INVAL) { 1478 if (bp->b_flags & B_DELWRI) 1479 bundirty(bp); 1480 if (bp->b_vp) 1481 brelvp(bp); 1482 } 1483 1484 /* buffers with no memory */ 1485 if (bp->b_bufsize == 0) { 1486 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1487 if (bp->b_vflags & BV_BKGRDINPROG) 1488 panic("losing buffer 1"); 1489 if (bp->b_kvasize) { 1490 bp->b_qindex = QUEUE_EMPTYKVA; 1491 } else { 1492 bp->b_qindex = QUEUE_EMPTY; 1493 } 1494 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1495 /* buffers with junk contents */ 1496 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1497 (bp->b_ioflags & BIO_ERROR)) { 1498 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1499 if (bp->b_vflags & BV_BKGRDINPROG) 1500 panic("losing buffer 2"); 1501 bp->b_qindex = QUEUE_CLEAN; 1502 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1503 /* remaining buffers */ 1504 } else { 1505 if (bp->b_flags & B_DELWRI) 1506 bp->b_qindex = QUEUE_DIRTY; 1507 else 1508 bp->b_qindex = QUEUE_CLEAN; 1509 if (bp->b_flags & B_AGE) 1510 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1511 else 1512 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1513 } 1514 mtx_unlock(&bqlock); 1515 1516 /* 1517 * Fixup numfreebuffers count. The bp is on an appropriate queue 1518 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1519 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1520 * if B_INVAL is set ). 1521 */ 1522 1523 if (!(bp->b_flags & B_DELWRI)) { 1524 struct bufobj *bo; 1525 1526 bo = bp->b_bufobj; 1527 if (bo != NULL) 1528 BO_LOCK(bo); 1529 bufcountwakeup(bp); 1530 if (bo != NULL) 1531 BO_UNLOCK(bo); 1532 } 1533 1534 /* 1535 * Something we can maybe free or reuse 1536 */ 1537 if (bp->b_bufsize || bp->b_kvasize) 1538 bufspacewakeup(); 1539 1540 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1541 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1542 panic("brelse: not dirty"); 1543 /* unlock */ 1544 BUF_UNLOCK(bp); 1545 } 1546 1547 /* 1548 * Release a buffer back to the appropriate queue but do not try to free 1549 * it. The buffer is expected to be used again soon. 1550 * 1551 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1552 * biodone() to requeue an async I/O on completion. It is also used when 1553 * known good buffers need to be requeued but we think we may need the data 1554 * again soon. 1555 * 1556 * XXX we should be able to leave the B_RELBUF hint set on completion. 1557 */ 1558 void 1559 bqrelse(struct buf *bp) 1560 { 1561 struct bufobj *bo; 1562 1563 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1564 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1565 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1566 1567 if (BUF_LOCKRECURSED(bp)) { 1568 /* do not release to free list */ 1569 BUF_UNLOCK(bp); 1570 return; 1571 } 1572 1573 bo = bp->b_bufobj; 1574 if (bp->b_flags & B_MANAGED) { 1575 if (bp->b_flags & B_REMFREE) { 1576 mtx_lock(&bqlock); 1577 if (bo != NULL) 1578 BO_LOCK(bo); 1579 bremfreel(bp); 1580 if (bo != NULL) 1581 BO_UNLOCK(bo); 1582 mtx_unlock(&bqlock); 1583 } 1584 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1585 BUF_UNLOCK(bp); 1586 return; 1587 } 1588 1589 mtx_lock(&bqlock); 1590 /* Handle delayed bremfree() processing. */ 1591 if (bp->b_flags & B_REMFREE) { 1592 if (bo != NULL) 1593 BO_LOCK(bo); 1594 bremfreel(bp); 1595 if (bo != NULL) 1596 BO_UNLOCK(bo); 1597 } 1598 if (bp->b_qindex != QUEUE_NONE) 1599 panic("bqrelse: free buffer onto another queue???"); 1600 /* buffers with stale but valid contents */ 1601 if (bp->b_flags & B_DELWRI) { 1602 bp->b_qindex = QUEUE_DIRTY; 1603 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1604 } else { 1605 /* 1606 * The locking of the BO_LOCK for checking of the 1607 * BV_BKGRDINPROG is not necessary since the 1608 * BV_BKGRDINPROG cannot be set while we hold the buf 1609 * lock, it can only be cleared if it is already 1610 * pending. 1611 */ 1612 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1613 bp->b_qindex = QUEUE_CLEAN; 1614 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1615 b_freelist); 1616 } else { 1617 /* 1618 * We are too low on memory, we have to try to free 1619 * the buffer (most importantly: the wired pages 1620 * making up its backing store) *now*. 1621 */ 1622 mtx_unlock(&bqlock); 1623 brelse(bp); 1624 return; 1625 } 1626 } 1627 mtx_unlock(&bqlock); 1628 1629 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) { 1630 if (bo != NULL) 1631 BO_LOCK(bo); 1632 bufcountwakeup(bp); 1633 if (bo != NULL) 1634 BO_UNLOCK(bo); 1635 } 1636 1637 /* 1638 * Something we can maybe free or reuse. 1639 */ 1640 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1641 bufspacewakeup(); 1642 1643 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1644 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1645 panic("bqrelse: not dirty"); 1646 /* unlock */ 1647 BUF_UNLOCK(bp); 1648 } 1649 1650 /* Give pages used by the bp back to the VM system (where possible) */ 1651 static void 1652 vfs_vmio_release(struct buf *bp) 1653 { 1654 int i; 1655 vm_page_t m; 1656 1657 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), bp->b_npages); 1658 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1659 for (i = 0; i < bp->b_npages; i++) { 1660 m = bp->b_pages[i]; 1661 bp->b_pages[i] = NULL; 1662 /* 1663 * In order to keep page LRU ordering consistent, put 1664 * everything on the inactive queue. 1665 */ 1666 vm_page_lock(m); 1667 vm_page_unwire(m, 0); 1668 /* 1669 * We don't mess with busy pages, it is 1670 * the responsibility of the process that 1671 * busied the pages to deal with them. 1672 */ 1673 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1674 m->wire_count == 0) { 1675 /* 1676 * Might as well free the page if we can and it has 1677 * no valid data. We also free the page if the 1678 * buffer was used for direct I/O 1679 */ 1680 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid) { 1681 vm_page_free(m); 1682 } else if (bp->b_flags & B_DIRECT) { 1683 vm_page_try_to_free(m); 1684 } else if (buf_vm_page_count_severe()) { 1685 vm_page_try_to_cache(m); 1686 } 1687 } 1688 vm_page_unlock(m); 1689 } 1690 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1691 1692 if (bp->b_bufsize) { 1693 bufspacewakeup(); 1694 bp->b_bufsize = 0; 1695 } 1696 bp->b_npages = 0; 1697 bp->b_flags &= ~B_VMIO; 1698 if (bp->b_vp) 1699 brelvp(bp); 1700 } 1701 1702 /* 1703 * Check to see if a block at a particular lbn is available for a clustered 1704 * write. 1705 */ 1706 static int 1707 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1708 { 1709 struct buf *bpa; 1710 int match; 1711 1712 match = 0; 1713 1714 /* If the buf isn't in core skip it */ 1715 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1716 return (0); 1717 1718 /* If the buf is busy we don't want to wait for it */ 1719 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1720 return (0); 1721 1722 /* Only cluster with valid clusterable delayed write buffers */ 1723 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1724 (B_DELWRI | B_CLUSTEROK)) 1725 goto done; 1726 1727 if (bpa->b_bufsize != size) 1728 goto done; 1729 1730 /* 1731 * Check to see if it is in the expected place on disk and that the 1732 * block has been mapped. 1733 */ 1734 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1735 match = 1; 1736 done: 1737 BUF_UNLOCK(bpa); 1738 return (match); 1739 } 1740 1741 /* 1742 * vfs_bio_awrite: 1743 * 1744 * Implement clustered async writes for clearing out B_DELWRI buffers. 1745 * This is much better then the old way of writing only one buffer at 1746 * a time. Note that we may not be presented with the buffers in the 1747 * correct order, so we search for the cluster in both directions. 1748 */ 1749 int 1750 vfs_bio_awrite(struct buf *bp) 1751 { 1752 struct bufobj *bo; 1753 int i; 1754 int j; 1755 daddr_t lblkno = bp->b_lblkno; 1756 struct vnode *vp = bp->b_vp; 1757 int ncl; 1758 int nwritten; 1759 int size; 1760 int maxcl; 1761 1762 bo = &vp->v_bufobj; 1763 /* 1764 * right now we support clustered writing only to regular files. If 1765 * we find a clusterable block we could be in the middle of a cluster 1766 * rather then at the beginning. 1767 */ 1768 if ((vp->v_type == VREG) && 1769 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1770 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1771 1772 size = vp->v_mount->mnt_stat.f_iosize; 1773 maxcl = MAXPHYS / size; 1774 1775 BO_LOCK(bo); 1776 for (i = 1; i < maxcl; i++) 1777 if (vfs_bio_clcheck(vp, size, lblkno + i, 1778 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1779 break; 1780 1781 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1782 if (vfs_bio_clcheck(vp, size, lblkno - j, 1783 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1784 break; 1785 BO_UNLOCK(bo); 1786 --j; 1787 ncl = i + j; 1788 /* 1789 * this is a possible cluster write 1790 */ 1791 if (ncl != 1) { 1792 BUF_UNLOCK(bp); 1793 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1794 return nwritten; 1795 } 1796 } 1797 bremfree(bp); 1798 bp->b_flags |= B_ASYNC; 1799 /* 1800 * default (old) behavior, writing out only one block 1801 * 1802 * XXX returns b_bufsize instead of b_bcount for nwritten? 1803 */ 1804 nwritten = bp->b_bufsize; 1805 (void) bwrite(bp); 1806 1807 return nwritten; 1808 } 1809 1810 /* 1811 * getnewbuf: 1812 * 1813 * Find and initialize a new buffer header, freeing up existing buffers 1814 * in the bufqueues as necessary. The new buffer is returned locked. 1815 * 1816 * Important: B_INVAL is not set. If the caller wishes to throw the 1817 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1818 * 1819 * We block if: 1820 * We have insufficient buffer headers 1821 * We have insufficient buffer space 1822 * buffer_map is too fragmented ( space reservation fails ) 1823 * If we have to flush dirty buffers ( but we try to avoid this ) 1824 * 1825 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1826 * Instead we ask the buf daemon to do it for us. We attempt to 1827 * avoid piecemeal wakeups of the pageout daemon. 1828 */ 1829 1830 static struct buf * 1831 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1832 int gbflags) 1833 { 1834 struct thread *td; 1835 struct buf *bp; 1836 struct buf *nbp; 1837 int defrag = 0; 1838 int nqindex; 1839 static int flushingbufs; 1840 1841 td = curthread; 1842 /* 1843 * We can't afford to block since we might be holding a vnode lock, 1844 * which may prevent system daemons from running. We deal with 1845 * low-memory situations by proactively returning memory and running 1846 * async I/O rather then sync I/O. 1847 */ 1848 atomic_add_int(&getnewbufcalls, 1); 1849 atomic_subtract_int(&getnewbufrestarts, 1); 1850 restart: 1851 atomic_add_int(&getnewbufrestarts, 1); 1852 1853 /* 1854 * Setup for scan. If we do not have enough free buffers, 1855 * we setup a degenerate case that immediately fails. Note 1856 * that if we are specially marked process, we are allowed to 1857 * dip into our reserves. 1858 * 1859 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1860 * 1861 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1862 * However, there are a number of cases (defragging, reusing, ...) 1863 * where we cannot backup. 1864 */ 1865 mtx_lock(&bqlock); 1866 nqindex = QUEUE_EMPTYKVA; 1867 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1868 1869 if (nbp == NULL) { 1870 /* 1871 * If no EMPTYKVA buffers and we are either 1872 * defragging or reusing, locate a CLEAN buffer 1873 * to free or reuse. If bufspace useage is low 1874 * skip this step so we can allocate a new buffer. 1875 */ 1876 if (defrag || bufspace >= lobufspace) { 1877 nqindex = QUEUE_CLEAN; 1878 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1879 } 1880 1881 /* 1882 * If we could not find or were not allowed to reuse a 1883 * CLEAN buffer, check to see if it is ok to use an EMPTY 1884 * buffer. We can only use an EMPTY buffer if allocating 1885 * its KVA would not otherwise run us out of buffer space. 1886 */ 1887 if (nbp == NULL && defrag == 0 && 1888 bufspace + maxsize < hibufspace) { 1889 nqindex = QUEUE_EMPTY; 1890 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1891 } 1892 } 1893 1894 /* 1895 * Run scan, possibly freeing data and/or kva mappings on the fly 1896 * depending. 1897 */ 1898 1899 while ((bp = nbp) != NULL) { 1900 int qindex = nqindex; 1901 1902 /* 1903 * Calculate next bp ( we can only use it if we do not block 1904 * or do other fancy things ). 1905 */ 1906 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1907 switch(qindex) { 1908 case QUEUE_EMPTY: 1909 nqindex = QUEUE_EMPTYKVA; 1910 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1911 break; 1912 /* FALLTHROUGH */ 1913 case QUEUE_EMPTYKVA: 1914 nqindex = QUEUE_CLEAN; 1915 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1916 break; 1917 /* FALLTHROUGH */ 1918 case QUEUE_CLEAN: 1919 /* 1920 * nbp is NULL. 1921 */ 1922 break; 1923 } 1924 } 1925 /* 1926 * If we are defragging then we need a buffer with 1927 * b_kvasize != 0. XXX this situation should no longer 1928 * occur, if defrag is non-zero the buffer's b_kvasize 1929 * should also be non-zero at this point. XXX 1930 */ 1931 if (defrag && bp->b_kvasize == 0) { 1932 printf("Warning: defrag empty buffer %p\n", bp); 1933 continue; 1934 } 1935 1936 /* 1937 * Start freeing the bp. This is somewhat involved. nbp 1938 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1939 */ 1940 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1941 continue; 1942 if (bp->b_vp) { 1943 BO_LOCK(bp->b_bufobj); 1944 if (bp->b_vflags & BV_BKGRDINPROG) { 1945 BO_UNLOCK(bp->b_bufobj); 1946 BUF_UNLOCK(bp); 1947 continue; 1948 } 1949 BO_UNLOCK(bp->b_bufobj); 1950 } 1951 CTR6(KTR_BUF, 1952 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1953 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1954 bp->b_kvasize, bp->b_bufsize, qindex); 1955 1956 /* 1957 * Sanity Checks 1958 */ 1959 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1960 1961 /* 1962 * Note: we no longer distinguish between VMIO and non-VMIO 1963 * buffers. 1964 */ 1965 1966 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1967 1968 if (bp->b_bufobj != NULL) 1969 BO_LOCK(bp->b_bufobj); 1970 bremfreel(bp); 1971 if (bp->b_bufobj != NULL) 1972 BO_UNLOCK(bp->b_bufobj); 1973 mtx_unlock(&bqlock); 1974 1975 if (qindex == QUEUE_CLEAN) { 1976 if (bp->b_flags & B_VMIO) { 1977 bp->b_flags &= ~B_ASYNC; 1978 vfs_vmio_release(bp); 1979 } 1980 if (bp->b_vp) 1981 brelvp(bp); 1982 } 1983 1984 /* 1985 * NOTE: nbp is now entirely invalid. We can only restart 1986 * the scan from this point on. 1987 * 1988 * Get the rest of the buffer freed up. b_kva* is still 1989 * valid after this operation. 1990 */ 1991 1992 if (bp->b_rcred != NOCRED) { 1993 crfree(bp->b_rcred); 1994 bp->b_rcred = NOCRED; 1995 } 1996 if (bp->b_wcred != NOCRED) { 1997 crfree(bp->b_wcred); 1998 bp->b_wcred = NOCRED; 1999 } 2000 if (!LIST_EMPTY(&bp->b_dep)) 2001 buf_deallocate(bp); 2002 if (bp->b_vflags & BV_BKGRDINPROG) 2003 panic("losing buffer 3"); 2004 KASSERT(bp->b_vp == NULL, 2005 ("bp: %p still has vnode %p. qindex: %d", 2006 bp, bp->b_vp, qindex)); 2007 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 2008 ("bp: %p still on a buffer list. xflags %X", 2009 bp, bp->b_xflags)); 2010 2011 if (bp->b_bufsize) 2012 allocbuf(bp, 0); 2013 2014 bp->b_flags = 0; 2015 bp->b_ioflags = 0; 2016 bp->b_xflags = 0; 2017 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 2018 ("buf %p still counted as free?", bp)); 2019 bp->b_vflags = 0; 2020 bp->b_vp = NULL; 2021 bp->b_blkno = bp->b_lblkno = 0; 2022 bp->b_offset = NOOFFSET; 2023 bp->b_iodone = 0; 2024 bp->b_error = 0; 2025 bp->b_resid = 0; 2026 bp->b_bcount = 0; 2027 bp->b_npages = 0; 2028 bp->b_dirtyoff = bp->b_dirtyend = 0; 2029 bp->b_bufobj = NULL; 2030 bp->b_pin_count = 0; 2031 bp->b_fsprivate1 = NULL; 2032 bp->b_fsprivate2 = NULL; 2033 bp->b_fsprivate3 = NULL; 2034 2035 LIST_INIT(&bp->b_dep); 2036 2037 /* 2038 * If we are defragging then free the buffer. 2039 */ 2040 if (defrag) { 2041 bp->b_flags |= B_INVAL; 2042 bfreekva(bp); 2043 brelse(bp); 2044 defrag = 0; 2045 goto restart; 2046 } 2047 2048 /* 2049 * Notify any waiters for the buffer lock about 2050 * identity change by freeing the buffer. 2051 */ 2052 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2053 bp->b_flags |= B_INVAL; 2054 bfreekva(bp); 2055 brelse(bp); 2056 goto restart; 2057 } 2058 2059 /* 2060 * If we are overcomitted then recover the buffer and its 2061 * KVM space. This occurs in rare situations when multiple 2062 * processes are blocked in getnewbuf() or allocbuf(). 2063 */ 2064 if (bufspace >= hibufspace) 2065 flushingbufs = 1; 2066 if (flushingbufs && bp->b_kvasize != 0) { 2067 bp->b_flags |= B_INVAL; 2068 bfreekva(bp); 2069 brelse(bp); 2070 goto restart; 2071 } 2072 if (bufspace < lobufspace) 2073 flushingbufs = 0; 2074 break; 2075 } 2076 2077 /* 2078 * If we exhausted our list, sleep as appropriate. We may have to 2079 * wakeup various daemons and write out some dirty buffers. 2080 * 2081 * Generally we are sleeping due to insufficient buffer space. 2082 */ 2083 2084 if (bp == NULL) { 2085 int flags, norunbuf; 2086 char *waitmsg; 2087 int fl; 2088 2089 if (defrag) { 2090 flags = VFS_BIO_NEED_BUFSPACE; 2091 waitmsg = "nbufkv"; 2092 } else if (bufspace >= hibufspace) { 2093 waitmsg = "nbufbs"; 2094 flags = VFS_BIO_NEED_BUFSPACE; 2095 } else { 2096 waitmsg = "newbuf"; 2097 flags = VFS_BIO_NEED_ANY; 2098 } 2099 mtx_lock(&nblock); 2100 needsbuffer |= flags; 2101 mtx_unlock(&nblock); 2102 mtx_unlock(&bqlock); 2103 2104 bd_speedup(); /* heeeelp */ 2105 if (gbflags & GB_NOWAIT_BD) 2106 return (NULL); 2107 2108 mtx_lock(&nblock); 2109 while (needsbuffer & flags) { 2110 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2111 mtx_unlock(&nblock); 2112 /* 2113 * getblk() is called with a vnode 2114 * locked, and some majority of the 2115 * dirty buffers may as well belong to 2116 * the vnode. Flushing the buffers 2117 * there would make a progress that 2118 * cannot be achieved by the 2119 * buf_daemon, that cannot lock the 2120 * vnode. 2121 */ 2122 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2123 (td->td_pflags & TDP_NORUNNINGBUF); 2124 /* play bufdaemon */ 2125 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2126 fl = buf_do_flush(vp); 2127 td->td_pflags &= norunbuf; 2128 mtx_lock(&nblock); 2129 if (fl != 0) 2130 continue; 2131 if ((needsbuffer & flags) == 0) 2132 break; 2133 } 2134 if (msleep(&needsbuffer, &nblock, 2135 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2136 mtx_unlock(&nblock); 2137 return (NULL); 2138 } 2139 } 2140 mtx_unlock(&nblock); 2141 } else { 2142 /* 2143 * We finally have a valid bp. We aren't quite out of the 2144 * woods, we still have to reserve kva space. In order 2145 * to keep fragmentation sane we only allocate kva in 2146 * BKVASIZE chunks. 2147 */ 2148 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2149 2150 if (maxsize != bp->b_kvasize) { 2151 vm_offset_t addr = 0; 2152 int rv; 2153 2154 bfreekva(bp); 2155 2156 vm_map_lock(buffer_map); 2157 if (vm_map_findspace(buffer_map, 2158 vm_map_min(buffer_map), maxsize, &addr)) { 2159 /* 2160 * Buffer map is too fragmented. 2161 * We must defragment the map. 2162 */ 2163 atomic_add_int(&bufdefragcnt, 1); 2164 vm_map_unlock(buffer_map); 2165 defrag = 1; 2166 bp->b_flags |= B_INVAL; 2167 brelse(bp); 2168 goto restart; 2169 } 2170 rv = vm_map_insert(buffer_map, NULL, 0, addr, 2171 addr + maxsize, VM_PROT_ALL, VM_PROT_ALL, 2172 MAP_NOFAULT); 2173 KASSERT(rv == KERN_SUCCESS, 2174 ("vm_map_insert(buffer_map) rv %d", rv)); 2175 vm_map_unlock(buffer_map); 2176 bp->b_kvabase = (caddr_t)addr; 2177 bp->b_kvasize = maxsize; 2178 atomic_add_long(&bufspace, bp->b_kvasize); 2179 atomic_add_int(&bufreusecnt, 1); 2180 } 2181 bp->b_saveaddr = bp->b_kvabase; 2182 bp->b_data = bp->b_saveaddr; 2183 } 2184 return (bp); 2185 } 2186 2187 /* 2188 * buf_daemon: 2189 * 2190 * buffer flushing daemon. Buffers are normally flushed by the 2191 * update daemon but if it cannot keep up this process starts to 2192 * take the load in an attempt to prevent getnewbuf() from blocking. 2193 */ 2194 2195 static struct kproc_desc buf_kp = { 2196 "bufdaemon", 2197 buf_daemon, 2198 &bufdaemonproc 2199 }; 2200 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2201 2202 static int 2203 buf_do_flush(struct vnode *vp) 2204 { 2205 int flushed; 2206 2207 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2208 if (flushed == 0) { 2209 /* 2210 * Could not find any buffers without rollback 2211 * dependencies, so just write the first one 2212 * in the hopes of eventually making progress. 2213 */ 2214 flushbufqueues(vp, QUEUE_DIRTY, 1); 2215 } 2216 return (flushed); 2217 } 2218 2219 static void 2220 buf_daemon() 2221 { 2222 int lodirtysave; 2223 2224 /* 2225 * This process needs to be suspended prior to shutdown sync. 2226 */ 2227 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2228 SHUTDOWN_PRI_LAST); 2229 2230 /* 2231 * This process is allowed to take the buffer cache to the limit 2232 */ 2233 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2234 mtx_lock(&bdlock); 2235 for (;;) { 2236 bd_request = 0; 2237 mtx_unlock(&bdlock); 2238 2239 kproc_suspend_check(bufdaemonproc); 2240 lodirtysave = lodirtybuffers; 2241 if (bd_speedupreq) { 2242 lodirtybuffers = numdirtybuffers / 2; 2243 bd_speedupreq = 0; 2244 } 2245 /* 2246 * Do the flush. Limit the amount of in-transit I/O we 2247 * allow to build up, otherwise we would completely saturate 2248 * the I/O system. Wakeup any waiting processes before we 2249 * normally would so they can run in parallel with our drain. 2250 */ 2251 while (numdirtybuffers > lodirtybuffers) { 2252 if (buf_do_flush(NULL) == 0) 2253 break; 2254 kern_yield(PRI_USER); 2255 } 2256 lodirtybuffers = lodirtysave; 2257 2258 /* 2259 * Only clear bd_request if we have reached our low water 2260 * mark. The buf_daemon normally waits 1 second and 2261 * then incrementally flushes any dirty buffers that have 2262 * built up, within reason. 2263 * 2264 * If we were unable to hit our low water mark and couldn't 2265 * find any flushable buffers, we sleep half a second. 2266 * Otherwise we loop immediately. 2267 */ 2268 mtx_lock(&bdlock); 2269 if (numdirtybuffers <= lodirtybuffers) { 2270 /* 2271 * We reached our low water mark, reset the 2272 * request and sleep until we are needed again. 2273 * The sleep is just so the suspend code works. 2274 */ 2275 bd_request = 0; 2276 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2277 } else { 2278 /* 2279 * We couldn't find any flushable dirty buffers but 2280 * still have too many dirty buffers, we 2281 * have to sleep and try again. (rare) 2282 */ 2283 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2284 } 2285 } 2286 } 2287 2288 /* 2289 * flushbufqueues: 2290 * 2291 * Try to flush a buffer in the dirty queue. We must be careful to 2292 * free up B_INVAL buffers instead of write them, which NFS is 2293 * particularly sensitive to. 2294 */ 2295 static int flushwithdeps = 0; 2296 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2297 0, "Number of buffers flushed with dependecies that require rollbacks"); 2298 2299 static int 2300 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2301 { 2302 struct buf *sentinel; 2303 struct vnode *vp; 2304 struct mount *mp; 2305 struct buf *bp; 2306 int hasdeps; 2307 int flushed; 2308 int target; 2309 2310 if (lvp == NULL) { 2311 target = numdirtybuffers - lodirtybuffers; 2312 if (flushdeps && target > 2) 2313 target /= 2; 2314 } else 2315 target = flushbufqtarget; 2316 flushed = 0; 2317 bp = NULL; 2318 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2319 sentinel->b_qindex = QUEUE_SENTINEL; 2320 mtx_lock(&bqlock); 2321 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2322 while (flushed != target) { 2323 bp = TAILQ_NEXT(sentinel, b_freelist); 2324 if (bp != NULL) { 2325 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2326 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2327 b_freelist); 2328 } else 2329 break; 2330 /* 2331 * Skip sentinels inserted by other invocations of the 2332 * flushbufqueues(), taking care to not reorder them. 2333 */ 2334 if (bp->b_qindex == QUEUE_SENTINEL) 2335 continue; 2336 /* 2337 * Only flush the buffers that belong to the 2338 * vnode locked by the curthread. 2339 */ 2340 if (lvp != NULL && bp->b_vp != lvp) 2341 continue; 2342 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2343 continue; 2344 if (bp->b_pin_count > 0) { 2345 BUF_UNLOCK(bp); 2346 continue; 2347 } 2348 BO_LOCK(bp->b_bufobj); 2349 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2350 (bp->b_flags & B_DELWRI) == 0) { 2351 BO_UNLOCK(bp->b_bufobj); 2352 BUF_UNLOCK(bp); 2353 continue; 2354 } 2355 BO_UNLOCK(bp->b_bufobj); 2356 if (bp->b_flags & B_INVAL) { 2357 bremfreel(bp); 2358 mtx_unlock(&bqlock); 2359 brelse(bp); 2360 flushed++; 2361 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2362 mtx_lock(&bqlock); 2363 continue; 2364 } 2365 2366 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2367 if (flushdeps == 0) { 2368 BUF_UNLOCK(bp); 2369 continue; 2370 } 2371 hasdeps = 1; 2372 } else 2373 hasdeps = 0; 2374 /* 2375 * We must hold the lock on a vnode before writing 2376 * one of its buffers. Otherwise we may confuse, or 2377 * in the case of a snapshot vnode, deadlock the 2378 * system. 2379 * 2380 * The lock order here is the reverse of the normal 2381 * of vnode followed by buf lock. This is ok because 2382 * the NOWAIT will prevent deadlock. 2383 */ 2384 vp = bp->b_vp; 2385 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2386 BUF_UNLOCK(bp); 2387 continue; 2388 } 2389 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2390 mtx_unlock(&bqlock); 2391 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2392 bp, bp->b_vp, bp->b_flags); 2393 if (curproc == bufdaemonproc) 2394 vfs_bio_awrite(bp); 2395 else { 2396 bremfree(bp); 2397 bwrite(bp); 2398 notbufdflashes++; 2399 } 2400 vn_finished_write(mp); 2401 VOP_UNLOCK(vp, 0); 2402 flushwithdeps += hasdeps; 2403 flushed++; 2404 2405 /* 2406 * Sleeping on runningbufspace while holding 2407 * vnode lock leads to deadlock. 2408 */ 2409 if (curproc == bufdaemonproc) 2410 waitrunningbufspace(); 2411 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2412 mtx_lock(&bqlock); 2413 continue; 2414 } 2415 vn_finished_write(mp); 2416 BUF_UNLOCK(bp); 2417 } 2418 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2419 mtx_unlock(&bqlock); 2420 free(sentinel, M_TEMP); 2421 return (flushed); 2422 } 2423 2424 /* 2425 * Check to see if a block is currently memory resident. 2426 */ 2427 struct buf * 2428 incore(struct bufobj *bo, daddr_t blkno) 2429 { 2430 struct buf *bp; 2431 2432 BO_LOCK(bo); 2433 bp = gbincore(bo, blkno); 2434 BO_UNLOCK(bo); 2435 return (bp); 2436 } 2437 2438 /* 2439 * Returns true if no I/O is needed to access the 2440 * associated VM object. This is like incore except 2441 * it also hunts around in the VM system for the data. 2442 */ 2443 2444 static int 2445 inmem(struct vnode * vp, daddr_t blkno) 2446 { 2447 vm_object_t obj; 2448 vm_offset_t toff, tinc, size; 2449 vm_page_t m; 2450 vm_ooffset_t off; 2451 2452 ASSERT_VOP_LOCKED(vp, "inmem"); 2453 2454 if (incore(&vp->v_bufobj, blkno)) 2455 return 1; 2456 if (vp->v_mount == NULL) 2457 return 0; 2458 obj = vp->v_object; 2459 if (obj == NULL) 2460 return (0); 2461 2462 size = PAGE_SIZE; 2463 if (size > vp->v_mount->mnt_stat.f_iosize) 2464 size = vp->v_mount->mnt_stat.f_iosize; 2465 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2466 2467 VM_OBJECT_LOCK(obj); 2468 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2469 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2470 if (!m) 2471 goto notinmem; 2472 tinc = size; 2473 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2474 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2475 if (vm_page_is_valid(m, 2476 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2477 goto notinmem; 2478 } 2479 VM_OBJECT_UNLOCK(obj); 2480 return 1; 2481 2482 notinmem: 2483 VM_OBJECT_UNLOCK(obj); 2484 return (0); 2485 } 2486 2487 /* 2488 * Set the dirty range for a buffer based on the status of the dirty 2489 * bits in the pages comprising the buffer. The range is limited 2490 * to the size of the buffer. 2491 * 2492 * Tell the VM system that the pages associated with this buffer 2493 * are clean. This is used for delayed writes where the data is 2494 * going to go to disk eventually without additional VM intevention. 2495 * 2496 * Note that while we only really need to clean through to b_bcount, we 2497 * just go ahead and clean through to b_bufsize. 2498 */ 2499 static void 2500 vfs_clean_pages_dirty_buf(struct buf *bp) 2501 { 2502 vm_ooffset_t foff, noff, eoff; 2503 vm_page_t m; 2504 int i; 2505 2506 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2507 return; 2508 2509 foff = bp->b_offset; 2510 KASSERT(bp->b_offset != NOOFFSET, 2511 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2512 2513 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2514 vfs_drain_busy_pages(bp); 2515 vfs_setdirty_locked_object(bp); 2516 for (i = 0; i < bp->b_npages; i++) { 2517 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2518 eoff = noff; 2519 if (eoff > bp->b_offset + bp->b_bufsize) 2520 eoff = bp->b_offset + bp->b_bufsize; 2521 m = bp->b_pages[i]; 2522 vfs_page_set_validclean(bp, foff, m); 2523 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2524 foff = noff; 2525 } 2526 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2527 } 2528 2529 static void 2530 vfs_setdirty_locked_object(struct buf *bp) 2531 { 2532 vm_object_t object; 2533 int i; 2534 2535 object = bp->b_bufobj->bo_object; 2536 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2537 2538 /* 2539 * We qualify the scan for modified pages on whether the 2540 * object has been flushed yet. 2541 */ 2542 if ((object->flags & OBJ_MIGHTBEDIRTY) != 0) { 2543 vm_offset_t boffset; 2544 vm_offset_t eoffset; 2545 2546 /* 2547 * test the pages to see if they have been modified directly 2548 * by users through the VM system. 2549 */ 2550 for (i = 0; i < bp->b_npages; i++) 2551 vm_page_test_dirty(bp->b_pages[i]); 2552 2553 /* 2554 * Calculate the encompassing dirty range, boffset and eoffset, 2555 * (eoffset - boffset) bytes. 2556 */ 2557 2558 for (i = 0; i < bp->b_npages; i++) { 2559 if (bp->b_pages[i]->dirty) 2560 break; 2561 } 2562 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2563 2564 for (i = bp->b_npages - 1; i >= 0; --i) { 2565 if (bp->b_pages[i]->dirty) { 2566 break; 2567 } 2568 } 2569 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2570 2571 /* 2572 * Fit it to the buffer. 2573 */ 2574 2575 if (eoffset > bp->b_bcount) 2576 eoffset = bp->b_bcount; 2577 2578 /* 2579 * If we have a good dirty range, merge with the existing 2580 * dirty range. 2581 */ 2582 2583 if (boffset < eoffset) { 2584 if (bp->b_dirtyoff > boffset) 2585 bp->b_dirtyoff = boffset; 2586 if (bp->b_dirtyend < eoffset) 2587 bp->b_dirtyend = eoffset; 2588 } 2589 } 2590 } 2591 2592 /* 2593 * getblk: 2594 * 2595 * Get a block given a specified block and offset into a file/device. 2596 * The buffers B_DONE bit will be cleared on return, making it almost 2597 * ready for an I/O initiation. B_INVAL may or may not be set on 2598 * return. The caller should clear B_INVAL prior to initiating a 2599 * READ. 2600 * 2601 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2602 * an existing buffer. 2603 * 2604 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2605 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2606 * and then cleared based on the backing VM. If the previous buffer is 2607 * non-0-sized but invalid, B_CACHE will be cleared. 2608 * 2609 * If getblk() must create a new buffer, the new buffer is returned with 2610 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2611 * case it is returned with B_INVAL clear and B_CACHE set based on the 2612 * backing VM. 2613 * 2614 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2615 * B_CACHE bit is clear. 2616 * 2617 * What this means, basically, is that the caller should use B_CACHE to 2618 * determine whether the buffer is fully valid or not and should clear 2619 * B_INVAL prior to issuing a read. If the caller intends to validate 2620 * the buffer by loading its data area with something, the caller needs 2621 * to clear B_INVAL. If the caller does this without issuing an I/O, 2622 * the caller should set B_CACHE ( as an optimization ), else the caller 2623 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2624 * a write attempt or if it was a successfull read. If the caller 2625 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2626 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2627 */ 2628 struct buf * 2629 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2630 int flags) 2631 { 2632 struct buf *bp; 2633 struct bufobj *bo; 2634 int error; 2635 2636 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2637 ASSERT_VOP_LOCKED(vp, "getblk"); 2638 if (size > MAXBSIZE) 2639 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2640 2641 bo = &vp->v_bufobj; 2642 loop: 2643 /* 2644 * Block if we are low on buffers. Certain processes are allowed 2645 * to completely exhaust the buffer cache. 2646 * 2647 * If this check ever becomes a bottleneck it may be better to 2648 * move it into the else, when gbincore() fails. At the moment 2649 * it isn't a problem. 2650 */ 2651 if (numfreebuffers == 0) { 2652 if (TD_IS_IDLETHREAD(curthread)) 2653 return NULL; 2654 mtx_lock(&nblock); 2655 needsbuffer |= VFS_BIO_NEED_ANY; 2656 mtx_unlock(&nblock); 2657 } 2658 2659 BO_LOCK(bo); 2660 bp = gbincore(bo, blkno); 2661 if (bp != NULL) { 2662 int lockflags; 2663 /* 2664 * Buffer is in-core. If the buffer is not busy nor managed, 2665 * it must be on a queue. 2666 */ 2667 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2668 2669 if (flags & GB_LOCK_NOWAIT) 2670 lockflags |= LK_NOWAIT; 2671 2672 error = BUF_TIMELOCK(bp, lockflags, 2673 BO_MTX(bo), "getblk", slpflag, slptimeo); 2674 2675 /* 2676 * If we slept and got the lock we have to restart in case 2677 * the buffer changed identities. 2678 */ 2679 if (error == ENOLCK) 2680 goto loop; 2681 /* We timed out or were interrupted. */ 2682 else if (error) 2683 return (NULL); 2684 2685 /* 2686 * The buffer is locked. B_CACHE is cleared if the buffer is 2687 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2688 * and for a VMIO buffer B_CACHE is adjusted according to the 2689 * backing VM cache. 2690 */ 2691 if (bp->b_flags & B_INVAL) 2692 bp->b_flags &= ~B_CACHE; 2693 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2694 bp->b_flags |= B_CACHE; 2695 if (bp->b_flags & B_MANAGED) 2696 MPASS(bp->b_qindex == QUEUE_NONE); 2697 else { 2698 BO_LOCK(bo); 2699 bremfree(bp); 2700 BO_UNLOCK(bo); 2701 } 2702 2703 /* 2704 * check for size inconsistancies for non-VMIO case. 2705 */ 2706 2707 if (bp->b_bcount != size) { 2708 if ((bp->b_flags & B_VMIO) == 0 || 2709 (size > bp->b_kvasize)) { 2710 if (bp->b_flags & B_DELWRI) { 2711 /* 2712 * If buffer is pinned and caller does 2713 * not want sleep waiting for it to be 2714 * unpinned, bail out 2715 * */ 2716 if (bp->b_pin_count > 0) { 2717 if (flags & GB_LOCK_NOWAIT) { 2718 bqrelse(bp); 2719 return (NULL); 2720 } else { 2721 bunpin_wait(bp); 2722 } 2723 } 2724 bp->b_flags |= B_NOCACHE; 2725 bwrite(bp); 2726 } else { 2727 if (LIST_EMPTY(&bp->b_dep)) { 2728 bp->b_flags |= B_RELBUF; 2729 brelse(bp); 2730 } else { 2731 bp->b_flags |= B_NOCACHE; 2732 bwrite(bp); 2733 } 2734 } 2735 goto loop; 2736 } 2737 } 2738 2739 /* 2740 * If the size is inconsistant in the VMIO case, we can resize 2741 * the buffer. This might lead to B_CACHE getting set or 2742 * cleared. If the size has not changed, B_CACHE remains 2743 * unchanged from its previous state. 2744 */ 2745 2746 if (bp->b_bcount != size) 2747 allocbuf(bp, size); 2748 2749 KASSERT(bp->b_offset != NOOFFSET, 2750 ("getblk: no buffer offset")); 2751 2752 /* 2753 * A buffer with B_DELWRI set and B_CACHE clear must 2754 * be committed before we can return the buffer in 2755 * order to prevent the caller from issuing a read 2756 * ( due to B_CACHE not being set ) and overwriting 2757 * it. 2758 * 2759 * Most callers, including NFS and FFS, need this to 2760 * operate properly either because they assume they 2761 * can issue a read if B_CACHE is not set, or because 2762 * ( for example ) an uncached B_DELWRI might loop due 2763 * to softupdates re-dirtying the buffer. In the latter 2764 * case, B_CACHE is set after the first write completes, 2765 * preventing further loops. 2766 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2767 * above while extending the buffer, we cannot allow the 2768 * buffer to remain with B_CACHE set after the write 2769 * completes or it will represent a corrupt state. To 2770 * deal with this we set B_NOCACHE to scrap the buffer 2771 * after the write. 2772 * 2773 * We might be able to do something fancy, like setting 2774 * B_CACHE in bwrite() except if B_DELWRI is already set, 2775 * so the below call doesn't set B_CACHE, but that gets real 2776 * confusing. This is much easier. 2777 */ 2778 2779 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2780 bp->b_flags |= B_NOCACHE; 2781 bwrite(bp); 2782 goto loop; 2783 } 2784 bp->b_flags &= ~B_DONE; 2785 } else { 2786 int bsize, maxsize, vmio; 2787 off_t offset; 2788 2789 /* 2790 * Buffer is not in-core, create new buffer. The buffer 2791 * returned by getnewbuf() is locked. Note that the returned 2792 * buffer is also considered valid (not marked B_INVAL). 2793 */ 2794 BO_UNLOCK(bo); 2795 /* 2796 * If the user does not want us to create the buffer, bail out 2797 * here. 2798 */ 2799 if (flags & GB_NOCREAT) 2800 return NULL; 2801 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 2802 offset = blkno * bsize; 2803 vmio = vp->v_object != NULL; 2804 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2805 maxsize = imax(maxsize, bsize); 2806 2807 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2808 if (bp == NULL) { 2809 if (slpflag || slptimeo) 2810 return NULL; 2811 goto loop; 2812 } 2813 2814 /* 2815 * This code is used to make sure that a buffer is not 2816 * created while the getnewbuf routine is blocked. 2817 * This can be a problem whether the vnode is locked or not. 2818 * If the buffer is created out from under us, we have to 2819 * throw away the one we just created. 2820 * 2821 * Note: this must occur before we associate the buffer 2822 * with the vp especially considering limitations in 2823 * the splay tree implementation when dealing with duplicate 2824 * lblkno's. 2825 */ 2826 BO_LOCK(bo); 2827 if (gbincore(bo, blkno)) { 2828 BO_UNLOCK(bo); 2829 bp->b_flags |= B_INVAL; 2830 brelse(bp); 2831 goto loop; 2832 } 2833 2834 /* 2835 * Insert the buffer into the hash, so that it can 2836 * be found by incore. 2837 */ 2838 bp->b_blkno = bp->b_lblkno = blkno; 2839 bp->b_offset = offset; 2840 bgetvp(vp, bp); 2841 BO_UNLOCK(bo); 2842 2843 /* 2844 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2845 * buffer size starts out as 0, B_CACHE will be set by 2846 * allocbuf() for the VMIO case prior to it testing the 2847 * backing store for validity. 2848 */ 2849 2850 if (vmio) { 2851 bp->b_flags |= B_VMIO; 2852 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2853 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2854 bp, vp->v_object, bp->b_bufobj->bo_object)); 2855 } else { 2856 bp->b_flags &= ~B_VMIO; 2857 KASSERT(bp->b_bufobj->bo_object == NULL, 2858 ("ARGH! has b_bufobj->bo_object %p %p\n", 2859 bp, bp->b_bufobj->bo_object)); 2860 } 2861 2862 allocbuf(bp, size); 2863 bp->b_flags &= ~B_DONE; 2864 } 2865 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2866 BUF_ASSERT_HELD(bp); 2867 KASSERT(bp->b_bufobj == bo, 2868 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2869 return (bp); 2870 } 2871 2872 /* 2873 * Get an empty, disassociated buffer of given size. The buffer is initially 2874 * set to B_INVAL. 2875 */ 2876 struct buf * 2877 geteblk(int size, int flags) 2878 { 2879 struct buf *bp; 2880 int maxsize; 2881 2882 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2883 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2884 if ((flags & GB_NOWAIT_BD) && 2885 (curthread->td_pflags & TDP_BUFNEED) != 0) 2886 return (NULL); 2887 } 2888 allocbuf(bp, size); 2889 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2890 BUF_ASSERT_HELD(bp); 2891 return (bp); 2892 } 2893 2894 2895 /* 2896 * This code constitutes the buffer memory from either anonymous system 2897 * memory (in the case of non-VMIO operations) or from an associated 2898 * VM object (in the case of VMIO operations). This code is able to 2899 * resize a buffer up or down. 2900 * 2901 * Note that this code is tricky, and has many complications to resolve 2902 * deadlock or inconsistant data situations. Tread lightly!!! 2903 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2904 * the caller. Calling this code willy nilly can result in the loss of data. 2905 * 2906 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2907 * B_CACHE for the non-VMIO case. 2908 */ 2909 2910 int 2911 allocbuf(struct buf *bp, int size) 2912 { 2913 int newbsize, mbsize; 2914 int i; 2915 2916 BUF_ASSERT_HELD(bp); 2917 2918 if (bp->b_kvasize < size) 2919 panic("allocbuf: buffer too small"); 2920 2921 if ((bp->b_flags & B_VMIO) == 0) { 2922 caddr_t origbuf; 2923 int origbufsize; 2924 /* 2925 * Just get anonymous memory from the kernel. Don't 2926 * mess with B_CACHE. 2927 */ 2928 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2929 if (bp->b_flags & B_MALLOC) 2930 newbsize = mbsize; 2931 else 2932 newbsize = round_page(size); 2933 2934 if (newbsize < bp->b_bufsize) { 2935 /* 2936 * malloced buffers are not shrunk 2937 */ 2938 if (bp->b_flags & B_MALLOC) { 2939 if (newbsize) { 2940 bp->b_bcount = size; 2941 } else { 2942 free(bp->b_data, M_BIOBUF); 2943 if (bp->b_bufsize) { 2944 atomic_subtract_long( 2945 &bufmallocspace, 2946 bp->b_bufsize); 2947 bufspacewakeup(); 2948 bp->b_bufsize = 0; 2949 } 2950 bp->b_saveaddr = bp->b_kvabase; 2951 bp->b_data = bp->b_saveaddr; 2952 bp->b_bcount = 0; 2953 bp->b_flags &= ~B_MALLOC; 2954 } 2955 return 1; 2956 } 2957 vm_hold_free_pages(bp, newbsize); 2958 } else if (newbsize > bp->b_bufsize) { 2959 /* 2960 * We only use malloced memory on the first allocation. 2961 * and revert to page-allocated memory when the buffer 2962 * grows. 2963 */ 2964 /* 2965 * There is a potential smp race here that could lead 2966 * to bufmallocspace slightly passing the max. It 2967 * is probably extremely rare and not worth worrying 2968 * over. 2969 */ 2970 if ( (bufmallocspace < maxbufmallocspace) && 2971 (bp->b_bufsize == 0) && 2972 (mbsize <= PAGE_SIZE/2)) { 2973 2974 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2975 bp->b_bufsize = mbsize; 2976 bp->b_bcount = size; 2977 bp->b_flags |= B_MALLOC; 2978 atomic_add_long(&bufmallocspace, mbsize); 2979 return 1; 2980 } 2981 origbuf = NULL; 2982 origbufsize = 0; 2983 /* 2984 * If the buffer is growing on its other-than-first allocation, 2985 * then we revert to the page-allocation scheme. 2986 */ 2987 if (bp->b_flags & B_MALLOC) { 2988 origbuf = bp->b_data; 2989 origbufsize = bp->b_bufsize; 2990 bp->b_data = bp->b_kvabase; 2991 if (bp->b_bufsize) { 2992 atomic_subtract_long(&bufmallocspace, 2993 bp->b_bufsize); 2994 bufspacewakeup(); 2995 bp->b_bufsize = 0; 2996 } 2997 bp->b_flags &= ~B_MALLOC; 2998 newbsize = round_page(newbsize); 2999 } 3000 vm_hold_load_pages( 3001 bp, 3002 (vm_offset_t) bp->b_data + bp->b_bufsize, 3003 (vm_offset_t) bp->b_data + newbsize); 3004 if (origbuf) { 3005 bcopy(origbuf, bp->b_data, origbufsize); 3006 free(origbuf, M_BIOBUF); 3007 } 3008 } 3009 } else { 3010 int desiredpages; 3011 3012 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3013 desiredpages = (size == 0) ? 0 : 3014 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3015 3016 if (bp->b_flags & B_MALLOC) 3017 panic("allocbuf: VMIO buffer can't be malloced"); 3018 /* 3019 * Set B_CACHE initially if buffer is 0 length or will become 3020 * 0-length. 3021 */ 3022 if (size == 0 || bp->b_bufsize == 0) 3023 bp->b_flags |= B_CACHE; 3024 3025 if (newbsize < bp->b_bufsize) { 3026 /* 3027 * DEV_BSIZE aligned new buffer size is less then the 3028 * DEV_BSIZE aligned existing buffer size. Figure out 3029 * if we have to remove any pages. 3030 */ 3031 if (desiredpages < bp->b_npages) { 3032 vm_page_t m; 3033 3034 pmap_qremove((vm_offset_t)trunc_page( 3035 (vm_offset_t)bp->b_data) + 3036 (desiredpages << PAGE_SHIFT), 3037 (bp->b_npages - desiredpages)); 3038 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3039 for (i = desiredpages; i < bp->b_npages; i++) { 3040 /* 3041 * the page is not freed here -- it 3042 * is the responsibility of 3043 * vnode_pager_setsize 3044 */ 3045 m = bp->b_pages[i]; 3046 KASSERT(m != bogus_page, 3047 ("allocbuf: bogus page found")); 3048 while (vm_page_sleep_if_busy(m, TRUE, 3049 "biodep")) 3050 continue; 3051 3052 bp->b_pages[i] = NULL; 3053 vm_page_lock(m); 3054 vm_page_unwire(m, 0); 3055 vm_page_unlock(m); 3056 } 3057 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3058 bp->b_npages = desiredpages; 3059 } 3060 } else if (size > bp->b_bcount) { 3061 /* 3062 * We are growing the buffer, possibly in a 3063 * byte-granular fashion. 3064 */ 3065 vm_object_t obj; 3066 vm_offset_t toff; 3067 vm_offset_t tinc; 3068 3069 /* 3070 * Step 1, bring in the VM pages from the object, 3071 * allocating them if necessary. We must clear 3072 * B_CACHE if these pages are not valid for the 3073 * range covered by the buffer. 3074 */ 3075 3076 obj = bp->b_bufobj->bo_object; 3077 3078 VM_OBJECT_LOCK(obj); 3079 while (bp->b_npages < desiredpages) { 3080 vm_page_t m; 3081 3082 /* 3083 * We must allocate system pages since blocking 3084 * here could interfere with paging I/O, no 3085 * matter which process we are. 3086 * 3087 * We can only test VPO_BUSY here. Blocking on 3088 * m->busy might lead to a deadlock: 3089 * vm_fault->getpages->cluster_read->allocbuf 3090 * Thus, we specify VM_ALLOC_IGN_SBUSY. 3091 */ 3092 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3093 bp->b_npages, VM_ALLOC_NOBUSY | 3094 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3095 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | 3096 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3097 if (m->valid == 0) 3098 bp->b_flags &= ~B_CACHE; 3099 bp->b_pages[bp->b_npages] = m; 3100 ++bp->b_npages; 3101 } 3102 3103 /* 3104 * Step 2. We've loaded the pages into the buffer, 3105 * we have to figure out if we can still have B_CACHE 3106 * set. Note that B_CACHE is set according to the 3107 * byte-granular range ( bcount and size ), new the 3108 * aligned range ( newbsize ). 3109 * 3110 * The VM test is against m->valid, which is DEV_BSIZE 3111 * aligned. Needless to say, the validity of the data 3112 * needs to also be DEV_BSIZE aligned. Note that this 3113 * fails with NFS if the server or some other client 3114 * extends the file's EOF. If our buffer is resized, 3115 * B_CACHE may remain set! XXX 3116 */ 3117 3118 toff = bp->b_bcount; 3119 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3120 3121 while ((bp->b_flags & B_CACHE) && toff < size) { 3122 vm_pindex_t pi; 3123 3124 if (tinc > (size - toff)) 3125 tinc = size - toff; 3126 3127 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3128 PAGE_SHIFT; 3129 3130 vfs_buf_test_cache( 3131 bp, 3132 bp->b_offset, 3133 toff, 3134 tinc, 3135 bp->b_pages[pi] 3136 ); 3137 toff += tinc; 3138 tinc = PAGE_SIZE; 3139 } 3140 VM_OBJECT_UNLOCK(obj); 3141 3142 /* 3143 * Step 3, fixup the KVM pmap. Remember that 3144 * bp->b_data is relative to bp->b_offset, but 3145 * bp->b_offset may be offset into the first page. 3146 */ 3147 3148 bp->b_data = (caddr_t) 3149 trunc_page((vm_offset_t)bp->b_data); 3150 pmap_qenter( 3151 (vm_offset_t)bp->b_data, 3152 bp->b_pages, 3153 bp->b_npages 3154 ); 3155 3156 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3157 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3158 } 3159 } 3160 if (newbsize < bp->b_bufsize) 3161 bufspacewakeup(); 3162 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3163 bp->b_bcount = size; /* requested buffer size */ 3164 return 1; 3165 } 3166 3167 void 3168 biodone(struct bio *bp) 3169 { 3170 struct mtx *mtxp; 3171 void (*done)(struct bio *); 3172 3173 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3174 mtx_lock(mtxp); 3175 bp->bio_flags |= BIO_DONE; 3176 done = bp->bio_done; 3177 if (done == NULL) 3178 wakeup(bp); 3179 mtx_unlock(mtxp); 3180 if (done != NULL) 3181 done(bp); 3182 } 3183 3184 /* 3185 * Wait for a BIO to finish. 3186 * 3187 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3188 * case is not yet clear. 3189 */ 3190 int 3191 biowait(struct bio *bp, const char *wchan) 3192 { 3193 struct mtx *mtxp; 3194 3195 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3196 mtx_lock(mtxp); 3197 while ((bp->bio_flags & BIO_DONE) == 0) 3198 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3199 mtx_unlock(mtxp); 3200 if (bp->bio_error != 0) 3201 return (bp->bio_error); 3202 if (!(bp->bio_flags & BIO_ERROR)) 3203 return (0); 3204 return (EIO); 3205 } 3206 3207 void 3208 biofinish(struct bio *bp, struct devstat *stat, int error) 3209 { 3210 3211 if (error) { 3212 bp->bio_error = error; 3213 bp->bio_flags |= BIO_ERROR; 3214 } 3215 if (stat != NULL) 3216 devstat_end_transaction_bio(stat, bp); 3217 biodone(bp); 3218 } 3219 3220 /* 3221 * bufwait: 3222 * 3223 * Wait for buffer I/O completion, returning error status. The buffer 3224 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3225 * error and cleared. 3226 */ 3227 int 3228 bufwait(struct buf *bp) 3229 { 3230 if (bp->b_iocmd == BIO_READ) 3231 bwait(bp, PRIBIO, "biord"); 3232 else 3233 bwait(bp, PRIBIO, "biowr"); 3234 if (bp->b_flags & B_EINTR) { 3235 bp->b_flags &= ~B_EINTR; 3236 return (EINTR); 3237 } 3238 if (bp->b_ioflags & BIO_ERROR) { 3239 return (bp->b_error ? bp->b_error : EIO); 3240 } else { 3241 return (0); 3242 } 3243 } 3244 3245 /* 3246 * Call back function from struct bio back up to struct buf. 3247 */ 3248 static void 3249 bufdonebio(struct bio *bip) 3250 { 3251 struct buf *bp; 3252 3253 bp = bip->bio_caller2; 3254 bp->b_resid = bp->b_bcount - bip->bio_completed; 3255 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3256 bp->b_ioflags = bip->bio_flags; 3257 bp->b_error = bip->bio_error; 3258 if (bp->b_error) 3259 bp->b_ioflags |= BIO_ERROR; 3260 bufdone(bp); 3261 g_destroy_bio(bip); 3262 } 3263 3264 void 3265 dev_strategy(struct cdev *dev, struct buf *bp) 3266 { 3267 struct cdevsw *csw; 3268 struct bio *bip; 3269 int ref; 3270 3271 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3272 panic("b_iocmd botch"); 3273 for (;;) { 3274 bip = g_new_bio(); 3275 if (bip != NULL) 3276 break; 3277 /* Try again later */ 3278 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3279 } 3280 bip->bio_cmd = bp->b_iocmd; 3281 bip->bio_offset = bp->b_iooffset; 3282 bip->bio_length = bp->b_bcount; 3283 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3284 bip->bio_data = bp->b_data; 3285 bip->bio_done = bufdonebio; 3286 bip->bio_caller2 = bp; 3287 bip->bio_dev = dev; 3288 KASSERT(dev->si_refcount > 0, 3289 ("dev_strategy on un-referenced struct cdev *(%s)", 3290 devtoname(dev))); 3291 csw = dev_refthread(dev, &ref); 3292 if (csw == NULL) { 3293 g_destroy_bio(bip); 3294 bp->b_error = ENXIO; 3295 bp->b_ioflags = BIO_ERROR; 3296 bufdone(bp); 3297 return; 3298 } 3299 (*csw->d_strategy)(bip); 3300 dev_relthread(dev, ref); 3301 } 3302 3303 /* 3304 * bufdone: 3305 * 3306 * Finish I/O on a buffer, optionally calling a completion function. 3307 * This is usually called from an interrupt so process blocking is 3308 * not allowed. 3309 * 3310 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3311 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3312 * assuming B_INVAL is clear. 3313 * 3314 * For the VMIO case, we set B_CACHE if the op was a read and no 3315 * read error occured, or if the op was a write. B_CACHE is never 3316 * set if the buffer is invalid or otherwise uncacheable. 3317 * 3318 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3319 * initiator to leave B_INVAL set to brelse the buffer out of existance 3320 * in the biodone routine. 3321 */ 3322 void 3323 bufdone(struct buf *bp) 3324 { 3325 struct bufobj *dropobj; 3326 void (*biodone)(struct buf *); 3327 3328 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3329 dropobj = NULL; 3330 3331 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3332 BUF_ASSERT_HELD(bp); 3333 3334 runningbufwakeup(bp); 3335 if (bp->b_iocmd == BIO_WRITE) 3336 dropobj = bp->b_bufobj; 3337 /* call optional completion function if requested */ 3338 if (bp->b_iodone != NULL) { 3339 biodone = bp->b_iodone; 3340 bp->b_iodone = NULL; 3341 (*biodone) (bp); 3342 if (dropobj) 3343 bufobj_wdrop(dropobj); 3344 return; 3345 } 3346 3347 bufdone_finish(bp); 3348 3349 if (dropobj) 3350 bufobj_wdrop(dropobj); 3351 } 3352 3353 void 3354 bufdone_finish(struct buf *bp) 3355 { 3356 BUF_ASSERT_HELD(bp); 3357 3358 if (!LIST_EMPTY(&bp->b_dep)) 3359 buf_complete(bp); 3360 3361 if (bp->b_flags & B_VMIO) { 3362 vm_ooffset_t foff; 3363 vm_page_t m; 3364 vm_object_t obj; 3365 struct vnode *vp; 3366 int bogus, i, iosize; 3367 3368 obj = bp->b_bufobj->bo_object; 3369 KASSERT(obj->paging_in_progress >= bp->b_npages, 3370 ("biodone_finish: paging in progress(%d) < b_npages(%d)", 3371 obj->paging_in_progress, bp->b_npages)); 3372 3373 vp = bp->b_vp; 3374 KASSERT(vp->v_holdcnt > 0, 3375 ("biodone_finish: vnode %p has zero hold count", vp)); 3376 KASSERT(vp->v_object != NULL, 3377 ("biodone_finish: vnode %p has no vm_object", vp)); 3378 3379 foff = bp->b_offset; 3380 KASSERT(bp->b_offset != NOOFFSET, 3381 ("biodone_finish: bp %p has no buffer offset", bp)); 3382 3383 /* 3384 * Set B_CACHE if the op was a normal read and no error 3385 * occured. B_CACHE is set for writes in the b*write() 3386 * routines. 3387 */ 3388 iosize = bp->b_bcount - bp->b_resid; 3389 if (bp->b_iocmd == BIO_READ && 3390 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3391 !(bp->b_ioflags & BIO_ERROR)) { 3392 bp->b_flags |= B_CACHE; 3393 } 3394 bogus = 0; 3395 VM_OBJECT_LOCK(obj); 3396 for (i = 0; i < bp->b_npages; i++) { 3397 int bogusflag = 0; 3398 int resid; 3399 3400 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3401 if (resid > iosize) 3402 resid = iosize; 3403 3404 /* 3405 * cleanup bogus pages, restoring the originals 3406 */ 3407 m = bp->b_pages[i]; 3408 if (m == bogus_page) { 3409 bogus = bogusflag = 1; 3410 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3411 if (m == NULL) 3412 panic("biodone: page disappeared!"); 3413 bp->b_pages[i] = m; 3414 } 3415 KASSERT(OFF_TO_IDX(foff) == m->pindex, 3416 ("biodone_finish: foff(%jd)/pindex(%ju) mismatch", 3417 (intmax_t)foff, (uintmax_t)m->pindex)); 3418 3419 /* 3420 * In the write case, the valid and clean bits are 3421 * already changed correctly ( see bdwrite() ), so we 3422 * only need to do this here in the read case. 3423 */ 3424 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3425 KASSERT((m->dirty & vm_page_bits(foff & 3426 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3427 " page %p has unexpected dirty bits", m)); 3428 vfs_page_set_valid(bp, foff, m); 3429 } 3430 3431 vm_page_io_finish(m); 3432 vm_object_pip_subtract(obj, 1); 3433 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3434 iosize -= resid; 3435 } 3436 vm_object_pip_wakeupn(obj, 0); 3437 VM_OBJECT_UNLOCK(obj); 3438 if (bogus) 3439 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3440 bp->b_pages, bp->b_npages); 3441 } 3442 3443 /* 3444 * For asynchronous completions, release the buffer now. The brelse 3445 * will do a wakeup there if necessary - so no need to do a wakeup 3446 * here in the async case. The sync case always needs to do a wakeup. 3447 */ 3448 3449 if (bp->b_flags & B_ASYNC) { 3450 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3451 brelse(bp); 3452 else 3453 bqrelse(bp); 3454 } else 3455 bdone(bp); 3456 } 3457 3458 /* 3459 * This routine is called in lieu of iodone in the case of 3460 * incomplete I/O. This keeps the busy status for pages 3461 * consistant. 3462 */ 3463 void 3464 vfs_unbusy_pages(struct buf *bp) 3465 { 3466 int i; 3467 vm_object_t obj; 3468 vm_page_t m; 3469 3470 runningbufwakeup(bp); 3471 if (!(bp->b_flags & B_VMIO)) 3472 return; 3473 3474 obj = bp->b_bufobj->bo_object; 3475 VM_OBJECT_LOCK(obj); 3476 for (i = 0; i < bp->b_npages; i++) { 3477 m = bp->b_pages[i]; 3478 if (m == bogus_page) { 3479 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3480 if (!m) 3481 panic("vfs_unbusy_pages: page missing\n"); 3482 bp->b_pages[i] = m; 3483 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3484 bp->b_pages, bp->b_npages); 3485 } 3486 vm_object_pip_subtract(obj, 1); 3487 vm_page_io_finish(m); 3488 } 3489 vm_object_pip_wakeupn(obj, 0); 3490 VM_OBJECT_UNLOCK(obj); 3491 } 3492 3493 /* 3494 * vfs_page_set_valid: 3495 * 3496 * Set the valid bits in a page based on the supplied offset. The 3497 * range is restricted to the buffer's size. 3498 * 3499 * This routine is typically called after a read completes. 3500 */ 3501 static void 3502 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3503 { 3504 vm_ooffset_t eoff; 3505 3506 /* 3507 * Compute the end offset, eoff, such that [off, eoff) does not span a 3508 * page boundary and eoff is not greater than the end of the buffer. 3509 * The end of the buffer, in this case, is our file EOF, not the 3510 * allocation size of the buffer. 3511 */ 3512 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3513 if (eoff > bp->b_offset + bp->b_bcount) 3514 eoff = bp->b_offset + bp->b_bcount; 3515 3516 /* 3517 * Set valid range. This is typically the entire buffer and thus the 3518 * entire page. 3519 */ 3520 if (eoff > off) 3521 vm_page_set_valid_range(m, off & PAGE_MASK, eoff - off); 3522 } 3523 3524 /* 3525 * vfs_page_set_validclean: 3526 * 3527 * Set the valid bits and clear the dirty bits in a page based on the 3528 * supplied offset. The range is restricted to the buffer's size. 3529 */ 3530 static void 3531 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3532 { 3533 vm_ooffset_t soff, eoff; 3534 3535 /* 3536 * Start and end offsets in buffer. eoff - soff may not cross a 3537 * page boundry or cross the end of the buffer. The end of the 3538 * buffer, in this case, is our file EOF, not the allocation size 3539 * of the buffer. 3540 */ 3541 soff = off; 3542 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3543 if (eoff > bp->b_offset + bp->b_bcount) 3544 eoff = bp->b_offset + bp->b_bcount; 3545 3546 /* 3547 * Set valid range. This is typically the entire buffer and thus the 3548 * entire page. 3549 */ 3550 if (eoff > soff) { 3551 vm_page_set_validclean( 3552 m, 3553 (vm_offset_t) (soff & PAGE_MASK), 3554 (vm_offset_t) (eoff - soff) 3555 ); 3556 } 3557 } 3558 3559 /* 3560 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3561 * any page is busy, drain the flag. 3562 */ 3563 static void 3564 vfs_drain_busy_pages(struct buf *bp) 3565 { 3566 vm_page_t m; 3567 int i, last_busied; 3568 3569 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED); 3570 last_busied = 0; 3571 for (i = 0; i < bp->b_npages; i++) { 3572 m = bp->b_pages[i]; 3573 if ((m->oflags & VPO_BUSY) != 0) { 3574 for (; last_busied < i; last_busied++) 3575 vm_page_busy(bp->b_pages[last_busied]); 3576 while ((m->oflags & VPO_BUSY) != 0) 3577 vm_page_sleep(m, "vbpage"); 3578 } 3579 } 3580 for (i = 0; i < last_busied; i++) 3581 vm_page_wakeup(bp->b_pages[i]); 3582 } 3583 3584 /* 3585 * This routine is called before a device strategy routine. 3586 * It is used to tell the VM system that paging I/O is in 3587 * progress, and treat the pages associated with the buffer 3588 * almost as being VPO_BUSY. Also the object paging_in_progress 3589 * flag is handled to make sure that the object doesn't become 3590 * inconsistant. 3591 * 3592 * Since I/O has not been initiated yet, certain buffer flags 3593 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3594 * and should be ignored. 3595 */ 3596 void 3597 vfs_busy_pages(struct buf *bp, int clear_modify) 3598 { 3599 int i, bogus; 3600 vm_object_t obj; 3601 vm_ooffset_t foff; 3602 vm_page_t m; 3603 3604 if (!(bp->b_flags & B_VMIO)) 3605 return; 3606 3607 obj = bp->b_bufobj->bo_object; 3608 foff = bp->b_offset; 3609 KASSERT(bp->b_offset != NOOFFSET, 3610 ("vfs_busy_pages: no buffer offset")); 3611 VM_OBJECT_LOCK(obj); 3612 vfs_drain_busy_pages(bp); 3613 if (bp->b_bufsize != 0) 3614 vfs_setdirty_locked_object(bp); 3615 bogus = 0; 3616 for (i = 0; i < bp->b_npages; i++) { 3617 m = bp->b_pages[i]; 3618 3619 if ((bp->b_flags & B_CLUSTER) == 0) { 3620 vm_object_pip_add(obj, 1); 3621 vm_page_io_start(m); 3622 } 3623 /* 3624 * When readying a buffer for a read ( i.e 3625 * clear_modify == 0 ), it is important to do 3626 * bogus_page replacement for valid pages in 3627 * partially instantiated buffers. Partially 3628 * instantiated buffers can, in turn, occur when 3629 * reconstituting a buffer from its VM backing store 3630 * base. We only have to do this if B_CACHE is 3631 * clear ( which causes the I/O to occur in the 3632 * first place ). The replacement prevents the read 3633 * I/O from overwriting potentially dirty VM-backed 3634 * pages. XXX bogus page replacement is, uh, bogus. 3635 * It may not work properly with small-block devices. 3636 * We need to find a better way. 3637 */ 3638 if (clear_modify) { 3639 pmap_remove_write(m); 3640 vfs_page_set_validclean(bp, foff, m); 3641 } else if (m->valid == VM_PAGE_BITS_ALL && 3642 (bp->b_flags & B_CACHE) == 0) { 3643 bp->b_pages[i] = bogus_page; 3644 bogus++; 3645 } 3646 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3647 } 3648 VM_OBJECT_UNLOCK(obj); 3649 if (bogus) 3650 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3651 bp->b_pages, bp->b_npages); 3652 } 3653 3654 /* 3655 * vfs_bio_set_valid: 3656 * 3657 * Set the range within the buffer to valid. The range is 3658 * relative to the beginning of the buffer, b_offset. Note that 3659 * b_offset itself may be offset from the beginning of the first 3660 * page. 3661 */ 3662 void 3663 vfs_bio_set_valid(struct buf *bp, int base, int size) 3664 { 3665 int i, n; 3666 vm_page_t m; 3667 3668 if (!(bp->b_flags & B_VMIO)) 3669 return; 3670 3671 /* 3672 * Fixup base to be relative to beginning of first page. 3673 * Set initial n to be the maximum number of bytes in the 3674 * first page that can be validated. 3675 */ 3676 base += (bp->b_offset & PAGE_MASK); 3677 n = PAGE_SIZE - (base & PAGE_MASK); 3678 3679 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3680 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3681 m = bp->b_pages[i]; 3682 if (n > size) 3683 n = size; 3684 vm_page_set_valid_range(m, base & PAGE_MASK, n); 3685 base += n; 3686 size -= n; 3687 n = PAGE_SIZE; 3688 } 3689 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3690 } 3691 3692 /* 3693 * vfs_bio_clrbuf: 3694 * 3695 * If the specified buffer is a non-VMIO buffer, clear the entire 3696 * buffer. If the specified buffer is a VMIO buffer, clear and 3697 * validate only the previously invalid portions of the buffer. 3698 * This routine essentially fakes an I/O, so we need to clear 3699 * BIO_ERROR and B_INVAL. 3700 * 3701 * Note that while we only theoretically need to clear through b_bcount, 3702 * we go ahead and clear through b_bufsize. 3703 */ 3704 void 3705 vfs_bio_clrbuf(struct buf *bp) 3706 { 3707 int i, j, mask; 3708 caddr_t sa, ea; 3709 3710 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3711 clrbuf(bp); 3712 return; 3713 } 3714 bp->b_flags &= ~B_INVAL; 3715 bp->b_ioflags &= ~BIO_ERROR; 3716 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3717 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3718 (bp->b_offset & PAGE_MASK) == 0) { 3719 if (bp->b_pages[0] == bogus_page) 3720 goto unlock; 3721 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3722 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3723 if ((bp->b_pages[0]->valid & mask) == mask) 3724 goto unlock; 3725 if ((bp->b_pages[0]->valid & mask) == 0) { 3726 bzero(bp->b_data, bp->b_bufsize); 3727 bp->b_pages[0]->valid |= mask; 3728 goto unlock; 3729 } 3730 } 3731 ea = sa = bp->b_data; 3732 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3733 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3734 ea = (caddr_t)(vm_offset_t)ulmin( 3735 (u_long)(vm_offset_t)ea, 3736 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3737 if (bp->b_pages[i] == bogus_page) 3738 continue; 3739 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3740 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3741 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3742 if ((bp->b_pages[i]->valid & mask) == mask) 3743 continue; 3744 if ((bp->b_pages[i]->valid & mask) == 0) 3745 bzero(sa, ea - sa); 3746 else { 3747 for (; sa < ea; sa += DEV_BSIZE, j++) { 3748 if ((bp->b_pages[i]->valid & (1 << j)) == 0) 3749 bzero(sa, DEV_BSIZE); 3750 } 3751 } 3752 bp->b_pages[i]->valid |= mask; 3753 } 3754 unlock: 3755 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3756 bp->b_resid = 0; 3757 } 3758 3759 /* 3760 * vm_hold_load_pages and vm_hold_free_pages get pages into 3761 * a buffers address space. The pages are anonymous and are 3762 * not associated with a file object. 3763 */ 3764 static void 3765 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3766 { 3767 vm_offset_t pg; 3768 vm_page_t p; 3769 int index; 3770 3771 to = round_page(to); 3772 from = round_page(from); 3773 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3774 3775 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3776 tryagain: 3777 /* 3778 * note: must allocate system pages since blocking here 3779 * could interfere with paging I/O, no matter which 3780 * process we are. 3781 */ 3782 p = vm_page_alloc(NULL, 0, VM_ALLOC_SYSTEM | VM_ALLOC_NOOBJ | 3783 VM_ALLOC_WIRED | VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 3784 if (p == NULL) { 3785 VM_WAIT; 3786 goto tryagain; 3787 } 3788 pmap_qenter(pg, &p, 1); 3789 bp->b_pages[index] = p; 3790 } 3791 bp->b_npages = index; 3792 } 3793 3794 /* Return pages associated with this buf to the vm system */ 3795 static void 3796 vm_hold_free_pages(struct buf *bp, int newbsize) 3797 { 3798 vm_offset_t from; 3799 vm_page_t p; 3800 int index, newnpages; 3801 3802 from = round_page((vm_offset_t)bp->b_data + newbsize); 3803 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3804 if (bp->b_npages > newnpages) 3805 pmap_qremove(from, bp->b_npages - newnpages); 3806 for (index = newnpages; index < bp->b_npages; index++) { 3807 p = bp->b_pages[index]; 3808 bp->b_pages[index] = NULL; 3809 if (p->busy != 0) 3810 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3811 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 3812 p->wire_count--; 3813 vm_page_free(p); 3814 atomic_subtract_int(&cnt.v_wire_count, 1); 3815 } 3816 bp->b_npages = newnpages; 3817 } 3818 3819 /* 3820 * Map an IO request into kernel virtual address space. 3821 * 3822 * All requests are (re)mapped into kernel VA space. 3823 * Notice that we use b_bufsize for the size of the buffer 3824 * to be mapped. b_bcount might be modified by the driver. 3825 * 3826 * Note that even if the caller determines that the address space should 3827 * be valid, a race or a smaller-file mapped into a larger space may 3828 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3829 * check the return value. 3830 */ 3831 int 3832 vmapbuf(struct buf *bp) 3833 { 3834 caddr_t kva; 3835 vm_prot_t prot; 3836 int pidx; 3837 3838 if (bp->b_bufsize < 0) 3839 return (-1); 3840 prot = VM_PROT_READ; 3841 if (bp->b_iocmd == BIO_READ) 3842 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3843 if ((pidx = vm_fault_quick_hold_pages(&curproc->p_vmspace->vm_map, 3844 (vm_offset_t)bp->b_data, bp->b_bufsize, prot, bp->b_pages, 3845 btoc(MAXPHYS))) < 0) 3846 return (-1); 3847 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3848 3849 kva = bp->b_saveaddr; 3850 bp->b_npages = pidx; 3851 bp->b_saveaddr = bp->b_data; 3852 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3853 return(0); 3854 } 3855 3856 /* 3857 * Free the io map PTEs associated with this IO operation. 3858 * We also invalidate the TLB entries and restore the original b_addr. 3859 */ 3860 void 3861 vunmapbuf(struct buf *bp) 3862 { 3863 int npages; 3864 3865 npages = bp->b_npages; 3866 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3867 vm_page_unhold_pages(bp->b_pages, npages); 3868 3869 bp->b_data = bp->b_saveaddr; 3870 } 3871 3872 void 3873 bdone(struct buf *bp) 3874 { 3875 struct mtx *mtxp; 3876 3877 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3878 mtx_lock(mtxp); 3879 bp->b_flags |= B_DONE; 3880 wakeup(bp); 3881 mtx_unlock(mtxp); 3882 } 3883 3884 void 3885 bwait(struct buf *bp, u_char pri, const char *wchan) 3886 { 3887 struct mtx *mtxp; 3888 3889 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3890 mtx_lock(mtxp); 3891 while ((bp->b_flags & B_DONE) == 0) 3892 msleep(bp, mtxp, pri, wchan, 0); 3893 mtx_unlock(mtxp); 3894 } 3895 3896 int 3897 bufsync(struct bufobj *bo, int waitfor) 3898 { 3899 3900 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3901 } 3902 3903 void 3904 bufstrategy(struct bufobj *bo, struct buf *bp) 3905 { 3906 int i = 0; 3907 struct vnode *vp; 3908 3909 vp = bp->b_vp; 3910 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3911 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3912 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3913 i = VOP_STRATEGY(vp, bp); 3914 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3915 } 3916 3917 void 3918 bufobj_wrefl(struct bufobj *bo) 3919 { 3920 3921 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3922 ASSERT_BO_LOCKED(bo); 3923 bo->bo_numoutput++; 3924 } 3925 3926 void 3927 bufobj_wref(struct bufobj *bo) 3928 { 3929 3930 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3931 BO_LOCK(bo); 3932 bo->bo_numoutput++; 3933 BO_UNLOCK(bo); 3934 } 3935 3936 void 3937 bufobj_wdrop(struct bufobj *bo) 3938 { 3939 3940 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3941 BO_LOCK(bo); 3942 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3943 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3944 bo->bo_flag &= ~BO_WWAIT; 3945 wakeup(&bo->bo_numoutput); 3946 } 3947 BO_UNLOCK(bo); 3948 } 3949 3950 int 3951 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3952 { 3953 int error; 3954 3955 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3956 ASSERT_BO_LOCKED(bo); 3957 error = 0; 3958 while (bo->bo_numoutput) { 3959 bo->bo_flag |= BO_WWAIT; 3960 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3961 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3962 if (error) 3963 break; 3964 } 3965 return (error); 3966 } 3967 3968 void 3969 bpin(struct buf *bp) 3970 { 3971 struct mtx *mtxp; 3972 3973 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3974 mtx_lock(mtxp); 3975 bp->b_pin_count++; 3976 mtx_unlock(mtxp); 3977 } 3978 3979 void 3980 bunpin(struct buf *bp) 3981 { 3982 struct mtx *mtxp; 3983 3984 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3985 mtx_lock(mtxp); 3986 if (--bp->b_pin_count == 0) 3987 wakeup(bp); 3988 mtx_unlock(mtxp); 3989 } 3990 3991 void 3992 bunpin_wait(struct buf *bp) 3993 { 3994 struct mtx *mtxp; 3995 3996 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3997 mtx_lock(mtxp); 3998 while (bp->b_pin_count > 0) 3999 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4000 mtx_unlock(mtxp); 4001 } 4002 4003 #include "opt_ddb.h" 4004 #ifdef DDB 4005 #include <ddb/ddb.h> 4006 4007 /* DDB command to show buffer data */ 4008 DB_SHOW_COMMAND(buffer, db_show_buffer) 4009 { 4010 /* get args */ 4011 struct buf *bp = (struct buf *)addr; 4012 4013 if (!have_addr) { 4014 db_printf("usage: show buffer <addr>\n"); 4015 return; 4016 } 4017 4018 db_printf("buf at %p\n", bp); 4019 db_printf("b_flags = 0x%b, b_xflags=0x%b, b_vflags=0x%b\n", 4020 (u_int)bp->b_flags, PRINT_BUF_FLAGS, (u_int)bp->b_xflags, 4021 PRINT_BUF_XFLAGS, (u_int)bp->b_vflags, PRINT_BUF_VFLAGS); 4022 db_printf( 4023 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4024 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_lblkno = %jd, " 4025 "b_dep = %p\n", 4026 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4027 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4028 (intmax_t)bp->b_lblkno, bp->b_dep.lh_first); 4029 if (bp->b_npages) { 4030 int i; 4031 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4032 for (i = 0; i < bp->b_npages; i++) { 4033 vm_page_t m; 4034 m = bp->b_pages[i]; 4035 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4036 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4037 if ((i + 1) < bp->b_npages) 4038 db_printf(","); 4039 } 4040 db_printf("\n"); 4041 } 4042 db_printf(" "); 4043 BUF_LOCKPRINTINFO(bp); 4044 } 4045 4046 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4047 { 4048 struct buf *bp; 4049 int i; 4050 4051 for (i = 0; i < nbuf; i++) { 4052 bp = &buf[i]; 4053 if (BUF_ISLOCKED(bp)) { 4054 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4055 db_printf("\n"); 4056 } 4057 } 4058 } 4059 4060 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4061 { 4062 struct vnode *vp; 4063 struct buf *bp; 4064 4065 if (!have_addr) { 4066 db_printf("usage: show vnodebufs <addr>\n"); 4067 return; 4068 } 4069 vp = (struct vnode *)addr; 4070 db_printf("Clean buffers:\n"); 4071 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4072 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4073 db_printf("\n"); 4074 } 4075 db_printf("Dirty buffers:\n"); 4076 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4077 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4078 db_printf("\n"); 4079 } 4080 } 4081 4082 DB_COMMAND(countfreebufs, db_coundfreebufs) 4083 { 4084 struct buf *bp; 4085 int i, used = 0, nfree = 0; 4086 4087 if (have_addr) { 4088 db_printf("usage: countfreebufs\n"); 4089 return; 4090 } 4091 4092 for (i = 0; i < nbuf; i++) { 4093 bp = &buf[i]; 4094 if ((bp->b_vflags & BV_INFREECNT) != 0) 4095 nfree++; 4096 else 4097 used++; 4098 } 4099 4100 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4101 nfree + used); 4102 db_printf("numfreebuffers is %d\n", numfreebuffers); 4103 } 4104 #endif /* DDB */ 4105