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"); 209 210 /* 211 * Wakeup point for bufdaemon, as well as indicator of whether it is already 212 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 213 * is idling. 214 */ 215 static int bd_request; 216 217 /* 218 * Request for the buf daemon to write more buffers than is indicated by 219 * lodirtybuf. This may be necessary to push out excess dependencies or 220 * defragment the address space where a simple count of the number of dirty 221 * buffers is insufficient to characterize the demand for flushing them. 222 */ 223 static int bd_speedupreq; 224 225 /* 226 * This lock synchronizes access to bd_request. 227 */ 228 static struct mtx bdlock; 229 230 /* 231 * bogus page -- for I/O to/from partially complete buffers 232 * this is a temporary solution to the problem, but it is not 233 * really that bad. it would be better to split the buffer 234 * for input in the case of buffers partially already in memory, 235 * but the code is intricate enough already. 236 */ 237 vm_page_t bogus_page; 238 239 /* 240 * Synchronization (sleep/wakeup) variable for active buffer space requests. 241 * Set when wait starts, cleared prior to wakeup(). 242 * Used in runningbufwakeup() and waitrunningbufspace(). 243 */ 244 static int runningbufreq; 245 246 /* 247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 248 * waitrunningbufspace(). 249 */ 250 static struct mtx rbreqlock; 251 252 /* 253 * Synchronization (sleep/wakeup) variable for buffer requests. 254 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 255 * by and/or. 256 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 257 * getnewbuf(), and getblk(). 258 */ 259 static int needsbuffer; 260 261 /* 262 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 263 */ 264 static struct mtx nblock; 265 266 /* 267 * Definitions for the buffer free lists. 268 */ 269 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 270 271 #define QUEUE_NONE 0 /* on no queue */ 272 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 273 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 274 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 275 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 276 #define QUEUE_EMPTY 5 /* empty buffer headers */ 277 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 278 279 /* Queues for free buffers with various properties */ 280 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 281 282 /* Lock for the bufqueues */ 283 static struct mtx bqlock; 284 285 /* 286 * Single global constant for BUF_WMESG, to avoid getting multiple references. 287 * buf_wmesg is referred from macros. 288 */ 289 const char *buf_wmesg = BUF_WMESG; 290 291 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 292 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 293 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 294 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 295 296 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 297 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 298 static int 299 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 300 { 301 long lvalue; 302 int ivalue; 303 304 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 305 return (sysctl_handle_long(oidp, arg1, arg2, req)); 306 lvalue = *(long *)arg1; 307 if (lvalue > INT_MAX) 308 /* On overflow, still write out a long to trigger ENOMEM. */ 309 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 310 ivalue = lvalue; 311 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 312 } 313 #endif 314 315 #ifdef DIRECTIO 316 extern void ffs_rawread_setup(void); 317 #endif /* DIRECTIO */ 318 /* 319 * numdirtywakeup: 320 * 321 * If someone is blocked due to there being too many dirty buffers, 322 * and numdirtybuffers is now reasonable, wake them up. 323 */ 324 325 static __inline void 326 numdirtywakeup(int level) 327 { 328 329 if (numdirtybuffers <= level) { 330 mtx_lock(&nblock); 331 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 332 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 333 wakeup(&needsbuffer); 334 } 335 mtx_unlock(&nblock); 336 } 337 } 338 339 /* 340 * bufspacewakeup: 341 * 342 * Called when buffer space is potentially available for recovery. 343 * getnewbuf() will block on this flag when it is unable to free 344 * sufficient buffer space. Buffer space becomes recoverable when 345 * bp's get placed back in the queues. 346 */ 347 348 static __inline void 349 bufspacewakeup(void) 350 { 351 352 /* 353 * If someone is waiting for BUF space, wake them up. Even 354 * though we haven't freed the kva space yet, the waiting 355 * process will be able to now. 356 */ 357 mtx_lock(&nblock); 358 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 359 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 360 wakeup(&needsbuffer); 361 } 362 mtx_unlock(&nblock); 363 } 364 365 /* 366 * runningbufwakeup() - in-progress I/O accounting. 367 * 368 */ 369 void 370 runningbufwakeup(struct buf *bp) 371 { 372 373 if (bp->b_runningbufspace) { 374 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 375 bp->b_runningbufspace = 0; 376 mtx_lock(&rbreqlock); 377 if (runningbufreq && runningbufspace <= lorunningspace) { 378 runningbufreq = 0; 379 wakeup(&runningbufreq); 380 } 381 mtx_unlock(&rbreqlock); 382 } 383 } 384 385 /* 386 * bufcountwakeup: 387 * 388 * Called when a buffer has been added to one of the free queues to 389 * account for the buffer and to wakeup anyone waiting for free buffers. 390 * This typically occurs when large amounts of metadata are being handled 391 * by the buffer cache ( else buffer space runs out first, usually ). 392 */ 393 394 static __inline void 395 bufcountwakeup(struct buf *bp) 396 { 397 int old; 398 399 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 400 ("buf %p already counted as free", bp)); 401 if (bp->b_bufobj != NULL) 402 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 403 bp->b_vflags |= BV_INFREECNT; 404 old = atomic_fetchadd_int(&numfreebuffers, 1); 405 KASSERT(old >= 0 && old < nbuf, 406 ("numfreebuffers climbed to %d", old + 1)); 407 mtx_lock(&nblock); 408 if (needsbuffer) { 409 needsbuffer &= ~VFS_BIO_NEED_ANY; 410 if (numfreebuffers >= hifreebuffers) 411 needsbuffer &= ~VFS_BIO_NEED_FREE; 412 wakeup(&needsbuffer); 413 } 414 mtx_unlock(&nblock); 415 } 416 417 /* 418 * waitrunningbufspace() 419 * 420 * runningbufspace is a measure of the amount of I/O currently 421 * running. This routine is used in async-write situations to 422 * prevent creating huge backups of pending writes to a device. 423 * Only asynchronous writes are governed by this function. 424 * 425 * Reads will adjust runningbufspace, but will not block based on it. 426 * The read load has a side effect of reducing the allowed write load. 427 * 428 * This does NOT turn an async write into a sync write. It waits 429 * for earlier writes to complete and generally returns before the 430 * caller's write has reached the device. 431 */ 432 void 433 waitrunningbufspace(void) 434 { 435 436 mtx_lock(&rbreqlock); 437 while (runningbufspace > hirunningspace) { 438 ++runningbufreq; 439 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 440 } 441 mtx_unlock(&rbreqlock); 442 } 443 444 445 /* 446 * vfs_buf_test_cache: 447 * 448 * Called when a buffer is extended. This function clears the B_CACHE 449 * bit if the newly extended portion of the buffer does not contain 450 * valid data. 451 */ 452 static __inline 453 void 454 vfs_buf_test_cache(struct buf *bp, 455 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 456 vm_page_t m) 457 { 458 459 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 460 if (bp->b_flags & B_CACHE) { 461 int base = (foff + off) & PAGE_MASK; 462 if (vm_page_is_valid(m, base, size) == 0) 463 bp->b_flags &= ~B_CACHE; 464 } 465 } 466 467 /* Wake up the buffer daemon if necessary */ 468 static __inline 469 void 470 bd_wakeup(int dirtybuflevel) 471 { 472 473 mtx_lock(&bdlock); 474 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 475 bd_request = 1; 476 wakeup(&bd_request); 477 } 478 mtx_unlock(&bdlock); 479 } 480 481 /* 482 * bd_speedup - speedup the buffer cache flushing code 483 */ 484 485 void 486 bd_speedup(void) 487 { 488 int needwake; 489 490 mtx_lock(&bdlock); 491 needwake = 0; 492 if (bd_speedupreq == 0 || bd_request == 0) 493 needwake = 1; 494 bd_speedupreq = 1; 495 bd_request = 1; 496 if (needwake) 497 wakeup(&bd_request); 498 mtx_unlock(&bdlock); 499 } 500 501 /* 502 * Calculating buffer cache scaling values and reserve space for buffer 503 * headers. This is called during low level kernel initialization and 504 * may be called more then once. We CANNOT write to the memory area 505 * being reserved at this time. 506 */ 507 caddr_t 508 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 509 { 510 int tuned_nbuf; 511 long maxbuf; 512 513 /* 514 * physmem_est is in pages. Convert it to kilobytes (assumes 515 * PAGE_SIZE is >= 1K) 516 */ 517 physmem_est = physmem_est * (PAGE_SIZE / 1024); 518 519 /* 520 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 521 * For the first 64MB of ram nominally allocate sufficient buffers to 522 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 523 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 524 * the buffer cache we limit the eventual kva reservation to 525 * maxbcache bytes. 526 * 527 * factor represents the 1/4 x ram conversion. 528 */ 529 if (nbuf == 0) { 530 int factor = 4 * BKVASIZE / 1024; 531 532 nbuf = 50; 533 if (physmem_est > 4096) 534 nbuf += min((physmem_est - 4096) / factor, 535 65536 / factor); 536 if (physmem_est > 65536) 537 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 538 539 if (maxbcache && nbuf > maxbcache / BKVASIZE) 540 nbuf = maxbcache / BKVASIZE; 541 tuned_nbuf = 1; 542 } else 543 tuned_nbuf = 0; 544 545 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 546 maxbuf = (LONG_MAX / 3) / BKVASIZE; 547 if (nbuf > maxbuf) { 548 if (!tuned_nbuf) 549 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 550 maxbuf); 551 nbuf = maxbuf; 552 } 553 554 /* 555 * swbufs are used as temporary holders for I/O, such as paging I/O. 556 * We have no less then 16 and no more then 256. 557 */ 558 nswbuf = max(min(nbuf/4, 256), 16); 559 #ifdef NSWBUF_MIN 560 if (nswbuf < NSWBUF_MIN) 561 nswbuf = NSWBUF_MIN; 562 #endif 563 #ifdef DIRECTIO 564 ffs_rawread_setup(); 565 #endif 566 567 /* 568 * Reserve space for the buffer cache buffers 569 */ 570 swbuf = (void *)v; 571 v = (caddr_t)(swbuf + nswbuf); 572 buf = (void *)v; 573 v = (caddr_t)(buf + nbuf); 574 575 return(v); 576 } 577 578 /* Initialize the buffer subsystem. Called before use of any buffers. */ 579 void 580 bufinit(void) 581 { 582 struct buf *bp; 583 int i; 584 585 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 586 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 587 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 588 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 589 590 /* next, make a null set of free lists */ 591 for (i = 0; i < BUFFER_QUEUES; i++) 592 TAILQ_INIT(&bufqueues[i]); 593 594 /* finally, initialize each buffer header and stick on empty q */ 595 for (i = 0; i < nbuf; i++) { 596 bp = &buf[i]; 597 bzero(bp, sizeof *bp); 598 bp->b_flags = B_INVAL; /* we're just an empty header */ 599 bp->b_rcred = NOCRED; 600 bp->b_wcred = NOCRED; 601 bp->b_qindex = QUEUE_EMPTY; 602 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */ 603 bp->b_xflags = 0; 604 LIST_INIT(&bp->b_dep); 605 BUF_LOCKINIT(bp); 606 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 607 } 608 609 /* 610 * maxbufspace is the absolute maximum amount of buffer space we are 611 * allowed to reserve in KVM and in real terms. The absolute maximum 612 * is nominally used by buf_daemon. hibufspace is the nominal maximum 613 * used by most other processes. The differential is required to 614 * ensure that buf_daemon is able to run when other processes might 615 * be blocked waiting for buffer space. 616 * 617 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 618 * this may result in KVM fragmentation which is not handled optimally 619 * by the system. 620 */ 621 maxbufspace = (long)nbuf * BKVASIZE; 622 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 623 lobufspace = hibufspace - MAXBSIZE; 624 625 /* 626 * Note: The 16 MB upper limit for hirunningspace was chosen 627 * arbitrarily and may need further tuning. It corresponds to 628 * 128 outstanding write IO requests (if IO size is 128 KiB), 629 * which fits with many RAID controllers' tagged queuing limits. 630 * The lower 1 MB limit is the historical upper limit for 631 * hirunningspace. 632 */ 633 hirunningspace = lmax(lmin(roundup(hibufspace / 64, MAXBSIZE), 634 16 * 1024 * 1024), 1024 * 1024); 635 lorunningspace = roundup(hirunningspace / 2, MAXBSIZE); 636 637 /* 638 * Limit the amount of malloc memory since it is wired permanently into 639 * the kernel space. Even though this is accounted for in the buffer 640 * allocation, we don't want the malloced region to grow uncontrolled. 641 * The malloc scheme improves memory utilization significantly on average 642 * (small) directories. 643 */ 644 maxbufmallocspace = hibufspace / 20; 645 646 /* 647 * Reduce the chance of a deadlock occuring by limiting the number 648 * of delayed-write dirty buffers we allow to stack up. 649 */ 650 hidirtybuffers = nbuf / 4 + 20; 651 dirtybufthresh = hidirtybuffers * 9 / 10; 652 numdirtybuffers = 0; 653 /* 654 * To support extreme low-memory systems, make sure hidirtybuffers cannot 655 * eat up all available buffer space. This occurs when our minimum cannot 656 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 657 * BKVASIZE'd (8K) buffers. 658 */ 659 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 660 hidirtybuffers >>= 1; 661 } 662 lodirtybuffers = hidirtybuffers / 2; 663 664 /* 665 * Try to keep the number of free buffers in the specified range, 666 * and give special processes (e.g. like buf_daemon) access to an 667 * emergency reserve. 668 */ 669 lofreebuffers = nbuf / 18 + 5; 670 hifreebuffers = 2 * lofreebuffers; 671 numfreebuffers = nbuf; 672 673 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 674 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 675 } 676 677 /* 678 * bfreekva() - free the kva allocation for a buffer. 679 * 680 * Since this call frees up buffer space, we call bufspacewakeup(). 681 */ 682 static void 683 bfreekva(struct buf *bp) 684 { 685 686 if (bp->b_kvasize) { 687 atomic_add_int(&buffreekvacnt, 1); 688 atomic_subtract_long(&bufspace, bp->b_kvasize); 689 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 690 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 691 bp->b_kvasize = 0; 692 bufspacewakeup(); 693 } 694 } 695 696 /* 697 * bremfree: 698 * 699 * Mark the buffer for removal from the appropriate free list in brelse. 700 * 701 */ 702 void 703 bremfree(struct buf *bp) 704 { 705 int old; 706 707 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 708 KASSERT((bp->b_flags & B_REMFREE) == 0, 709 ("bremfree: buffer %p already marked for delayed removal.", bp)); 710 KASSERT(bp->b_qindex != QUEUE_NONE, 711 ("bremfree: buffer %p not on a queue.", bp)); 712 BUF_ASSERT_HELD(bp); 713 714 bp->b_flags |= B_REMFREE; 715 /* Fixup numfreebuffers count. */ 716 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 717 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 718 ("buf %p not counted in numfreebuffers", bp)); 719 if (bp->b_bufobj != NULL) 720 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 721 bp->b_vflags &= ~BV_INFREECNT; 722 old = atomic_fetchadd_int(&numfreebuffers, -1); 723 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 724 } 725 } 726 727 /* 728 * bremfreef: 729 * 730 * Force an immediate removal from a free list. Used only in nfs when 731 * it abuses the b_freelist pointer. 732 */ 733 void 734 bremfreef(struct buf *bp) 735 { 736 mtx_lock(&bqlock); 737 bremfreel(bp); 738 mtx_unlock(&bqlock); 739 } 740 741 /* 742 * bremfreel: 743 * 744 * Removes a buffer from the free list, must be called with the 745 * bqlock held. 746 */ 747 static void 748 bremfreel(struct buf *bp) 749 { 750 int old; 751 752 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 753 bp, bp->b_vp, bp->b_flags); 754 KASSERT(bp->b_qindex != QUEUE_NONE, 755 ("bremfreel: buffer %p not on a queue.", bp)); 756 BUF_ASSERT_HELD(bp); 757 mtx_assert(&bqlock, MA_OWNED); 758 759 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 760 bp->b_qindex = QUEUE_NONE; 761 /* 762 * If this was a delayed bremfree() we only need to remove the buffer 763 * from the queue and return the stats are already done. 764 */ 765 if (bp->b_flags & B_REMFREE) { 766 bp->b_flags &= ~B_REMFREE; 767 return; 768 } 769 /* 770 * Fixup numfreebuffers count. If the buffer is invalid or not 771 * delayed-write, the buffer was free and we must decrement 772 * numfreebuffers. 773 */ 774 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 775 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 776 ("buf %p not counted in numfreebuffers", bp)); 777 if (bp->b_bufobj != NULL) 778 mtx_assert(BO_MTX(bp->b_bufobj), MA_OWNED); 779 bp->b_vflags &= ~BV_INFREECNT; 780 old = atomic_fetchadd_int(&numfreebuffers, -1); 781 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 782 } 783 } 784 785 786 /* 787 * Get a buffer with the specified data. Look in the cache first. We 788 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 789 * is set, the buffer is valid and we do not have to do anything ( see 790 * getblk() ). This is really just a special case of breadn(). 791 */ 792 int 793 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 794 struct buf **bpp) 795 { 796 797 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 798 } 799 800 /* 801 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 802 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 803 * the buffer is valid and we do not have to do anything. 804 */ 805 void 806 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 807 int cnt, struct ucred * cred) 808 { 809 struct buf *rabp; 810 int i; 811 812 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 813 if (inmem(vp, *rablkno)) 814 continue; 815 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 816 817 if ((rabp->b_flags & B_CACHE) == 0) { 818 if (!TD_IS_IDLETHREAD(curthread)) 819 curthread->td_ru.ru_inblock++; 820 rabp->b_flags |= B_ASYNC; 821 rabp->b_flags &= ~B_INVAL; 822 rabp->b_ioflags &= ~BIO_ERROR; 823 rabp->b_iocmd = BIO_READ; 824 if (rabp->b_rcred == NOCRED && cred != NOCRED) 825 rabp->b_rcred = crhold(cred); 826 vfs_busy_pages(rabp, 0); 827 BUF_KERNPROC(rabp); 828 rabp->b_iooffset = dbtob(rabp->b_blkno); 829 bstrategy(rabp); 830 } else { 831 brelse(rabp); 832 } 833 } 834 } 835 836 /* 837 * Operates like bread, but also starts asynchronous I/O on 838 * read-ahead blocks. 839 */ 840 int 841 breadn(struct vnode * vp, daddr_t blkno, int size, 842 daddr_t * rablkno, int *rabsize, 843 int cnt, struct ucred * cred, struct buf **bpp) 844 { 845 struct buf *bp; 846 int rv = 0, readwait = 0; 847 848 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 849 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 850 851 /* if not found in cache, do some I/O */ 852 if ((bp->b_flags & B_CACHE) == 0) { 853 if (!TD_IS_IDLETHREAD(curthread)) 854 curthread->td_ru.ru_inblock++; 855 bp->b_iocmd = BIO_READ; 856 bp->b_flags &= ~B_INVAL; 857 bp->b_ioflags &= ~BIO_ERROR; 858 if (bp->b_rcred == NOCRED && cred != NOCRED) 859 bp->b_rcred = crhold(cred); 860 vfs_busy_pages(bp, 0); 861 bp->b_iooffset = dbtob(bp->b_blkno); 862 bstrategy(bp); 863 ++readwait; 864 } 865 866 breada(vp, rablkno, rabsize, cnt, cred); 867 868 if (readwait) { 869 rv = bufwait(bp); 870 } 871 return (rv); 872 } 873 874 /* 875 * Write, release buffer on completion. (Done by iodone 876 * if async). Do not bother writing anything if the buffer 877 * is invalid. 878 * 879 * Note that we set B_CACHE here, indicating that buffer is 880 * fully valid and thus cacheable. This is true even of NFS 881 * now so we set it generally. This could be set either here 882 * or in biodone() since the I/O is synchronous. We put it 883 * here. 884 */ 885 int 886 bufwrite(struct buf *bp) 887 { 888 int oldflags; 889 struct vnode *vp; 890 int vp_md; 891 892 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 893 if (bp->b_flags & B_INVAL) { 894 brelse(bp); 895 return (0); 896 } 897 898 oldflags = bp->b_flags; 899 900 BUF_ASSERT_HELD(bp); 901 902 if (bp->b_pin_count > 0) 903 bunpin_wait(bp); 904 905 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 906 ("FFS background buffer should not get here %p", bp)); 907 908 vp = bp->b_vp; 909 if (vp) 910 vp_md = vp->v_vflag & VV_MD; 911 else 912 vp_md = 0; 913 914 /* Mark the buffer clean */ 915 bundirty(bp); 916 917 bp->b_flags &= ~B_DONE; 918 bp->b_ioflags &= ~BIO_ERROR; 919 bp->b_flags |= B_CACHE; 920 bp->b_iocmd = BIO_WRITE; 921 922 bufobj_wref(bp->b_bufobj); 923 vfs_busy_pages(bp, 1); 924 925 /* 926 * Normal bwrites pipeline writes 927 */ 928 bp->b_runningbufspace = bp->b_bufsize; 929 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 930 931 if (!TD_IS_IDLETHREAD(curthread)) 932 curthread->td_ru.ru_oublock++; 933 if (oldflags & B_ASYNC) 934 BUF_KERNPROC(bp); 935 bp->b_iooffset = dbtob(bp->b_blkno); 936 bstrategy(bp); 937 938 if ((oldflags & B_ASYNC) == 0) { 939 int rtval = bufwait(bp); 940 brelse(bp); 941 return (rtval); 942 } else { 943 /* 944 * don't allow the async write to saturate the I/O 945 * system. We will not deadlock here because 946 * we are blocking waiting for I/O that is already in-progress 947 * to complete. We do not block here if it is the update 948 * or syncer daemon trying to clean up as that can lead 949 * to deadlock. 950 */ 951 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 952 waitrunningbufspace(); 953 } 954 955 return (0); 956 } 957 958 void 959 bufbdflush(struct bufobj *bo, struct buf *bp) 960 { 961 struct buf *nbp; 962 963 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 964 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 965 altbufferflushes++; 966 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 967 BO_LOCK(bo); 968 /* 969 * Try to find a buffer to flush. 970 */ 971 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 972 if ((nbp->b_vflags & BV_BKGRDINPROG) || 973 BUF_LOCK(nbp, 974 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 975 continue; 976 if (bp == nbp) 977 panic("bdwrite: found ourselves"); 978 BO_UNLOCK(bo); 979 /* Don't countdeps with the bo lock held. */ 980 if (buf_countdeps(nbp, 0)) { 981 BO_LOCK(bo); 982 BUF_UNLOCK(nbp); 983 continue; 984 } 985 if (nbp->b_flags & B_CLUSTEROK) { 986 vfs_bio_awrite(nbp); 987 } else { 988 bremfree(nbp); 989 bawrite(nbp); 990 } 991 dirtybufferflushes++; 992 break; 993 } 994 if (nbp == NULL) 995 BO_UNLOCK(bo); 996 } 997 } 998 999 /* 1000 * Delayed write. (Buffer is marked dirty). Do not bother writing 1001 * anything if the buffer is marked invalid. 1002 * 1003 * Note that since the buffer must be completely valid, we can safely 1004 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 1005 * biodone() in order to prevent getblk from writing the buffer 1006 * out synchronously. 1007 */ 1008 void 1009 bdwrite(struct buf *bp) 1010 { 1011 struct thread *td = curthread; 1012 struct vnode *vp; 1013 struct bufobj *bo; 1014 1015 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1016 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1017 BUF_ASSERT_HELD(bp); 1018 1019 if (bp->b_flags & B_INVAL) { 1020 brelse(bp); 1021 return; 1022 } 1023 1024 /* 1025 * If we have too many dirty buffers, don't create any more. 1026 * If we are wildly over our limit, then force a complete 1027 * cleanup. Otherwise, just keep the situation from getting 1028 * out of control. Note that we have to avoid a recursive 1029 * disaster and not try to clean up after our own cleanup! 1030 */ 1031 vp = bp->b_vp; 1032 bo = bp->b_bufobj; 1033 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1034 td->td_pflags |= TDP_INBDFLUSH; 1035 BO_BDFLUSH(bo, bp); 1036 td->td_pflags &= ~TDP_INBDFLUSH; 1037 } else 1038 recursiveflushes++; 1039 1040 bdirty(bp); 1041 /* 1042 * Set B_CACHE, indicating that the buffer is fully valid. This is 1043 * true even of NFS now. 1044 */ 1045 bp->b_flags |= B_CACHE; 1046 1047 /* 1048 * This bmap keeps the system from needing to do the bmap later, 1049 * perhaps when the system is attempting to do a sync. Since it 1050 * is likely that the indirect block -- or whatever other datastructure 1051 * that the filesystem needs is still in memory now, it is a good 1052 * thing to do this. Note also, that if the pageout daemon is 1053 * requesting a sync -- there might not be enough memory to do 1054 * the bmap then... So, this is important to do. 1055 */ 1056 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1057 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1058 } 1059 1060 /* 1061 * Set the *dirty* buffer range based upon the VM system dirty 1062 * pages. 1063 * 1064 * Mark the buffer pages as clean. We need to do this here to 1065 * satisfy the vnode_pager and the pageout daemon, so that it 1066 * thinks that the pages have been "cleaned". Note that since 1067 * the pages are in a delayed write buffer -- the VFS layer 1068 * "will" see that the pages get written out on the next sync, 1069 * or perhaps the cluster will be completed. 1070 */ 1071 vfs_clean_pages_dirty_buf(bp); 1072 bqrelse(bp); 1073 1074 /* 1075 * Wakeup the buffer flushing daemon if we have a lot of dirty 1076 * buffers (midpoint between our recovery point and our stall 1077 * point). 1078 */ 1079 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1080 1081 /* 1082 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1083 * due to the softdep code. 1084 */ 1085 } 1086 1087 /* 1088 * bdirty: 1089 * 1090 * Turn buffer into delayed write request. We must clear BIO_READ and 1091 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1092 * itself to properly update it in the dirty/clean lists. We mark it 1093 * B_DONE to ensure that any asynchronization of the buffer properly 1094 * clears B_DONE ( else a panic will occur later ). 1095 * 1096 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1097 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1098 * should only be called if the buffer is known-good. 1099 * 1100 * Since the buffer is not on a queue, we do not update the numfreebuffers 1101 * count. 1102 * 1103 * The buffer must be on QUEUE_NONE. 1104 */ 1105 void 1106 bdirty(struct buf *bp) 1107 { 1108 1109 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1110 bp, bp->b_vp, bp->b_flags); 1111 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1112 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1113 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1114 BUF_ASSERT_HELD(bp); 1115 bp->b_flags &= ~(B_RELBUF); 1116 bp->b_iocmd = BIO_WRITE; 1117 1118 if ((bp->b_flags & B_DELWRI) == 0) { 1119 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1120 reassignbuf(bp); 1121 atomic_add_int(&numdirtybuffers, 1); 1122 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1123 } 1124 } 1125 1126 /* 1127 * bundirty: 1128 * 1129 * Clear B_DELWRI for buffer. 1130 * 1131 * Since the buffer is not on a queue, we do not update the numfreebuffers 1132 * count. 1133 * 1134 * The buffer must be on QUEUE_NONE. 1135 */ 1136 1137 void 1138 bundirty(struct buf *bp) 1139 { 1140 1141 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1142 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1143 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1144 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1145 BUF_ASSERT_HELD(bp); 1146 1147 if (bp->b_flags & B_DELWRI) { 1148 bp->b_flags &= ~B_DELWRI; 1149 reassignbuf(bp); 1150 atomic_subtract_int(&numdirtybuffers, 1); 1151 numdirtywakeup(lodirtybuffers); 1152 } 1153 /* 1154 * Since it is now being written, we can clear its deferred write flag. 1155 */ 1156 bp->b_flags &= ~B_DEFERRED; 1157 } 1158 1159 /* 1160 * bawrite: 1161 * 1162 * Asynchronous write. Start output on a buffer, but do not wait for 1163 * it to complete. The buffer is released when the output completes. 1164 * 1165 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1166 * B_INVAL buffers. Not us. 1167 */ 1168 void 1169 bawrite(struct buf *bp) 1170 { 1171 1172 bp->b_flags |= B_ASYNC; 1173 (void) bwrite(bp); 1174 } 1175 1176 /* 1177 * bwillwrite: 1178 * 1179 * Called prior to the locking of any vnodes when we are expecting to 1180 * write. We do not want to starve the buffer cache with too many 1181 * dirty buffers so we block here. By blocking prior to the locking 1182 * of any vnodes we attempt to avoid the situation where a locked vnode 1183 * prevents the various system daemons from flushing related buffers. 1184 */ 1185 1186 void 1187 bwillwrite(void) 1188 { 1189 1190 if (numdirtybuffers >= hidirtybuffers) { 1191 mtx_lock(&nblock); 1192 while (numdirtybuffers >= hidirtybuffers) { 1193 bd_wakeup(1); 1194 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1195 msleep(&needsbuffer, &nblock, 1196 (PRIBIO + 4), "flswai", 0); 1197 } 1198 mtx_unlock(&nblock); 1199 } 1200 } 1201 1202 /* 1203 * Return true if we have too many dirty buffers. 1204 */ 1205 int 1206 buf_dirty_count_severe(void) 1207 { 1208 1209 return(numdirtybuffers >= hidirtybuffers); 1210 } 1211 1212 static __noinline int 1213 buf_vm_page_count_severe(void) 1214 { 1215 1216 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1217 1218 return vm_page_count_severe(); 1219 } 1220 1221 /* 1222 * brelse: 1223 * 1224 * Release a busy buffer and, if requested, free its resources. The 1225 * buffer will be stashed in the appropriate bufqueue[] allowing it 1226 * to be accessed later as a cache entity or reused for other purposes. 1227 */ 1228 void 1229 brelse(struct buf *bp) 1230 { 1231 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1232 bp, bp->b_vp, bp->b_flags); 1233 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1234 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1235 1236 if (bp->b_flags & B_MANAGED) { 1237 bqrelse(bp); 1238 return; 1239 } 1240 1241 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1242 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1243 /* 1244 * Failed write, redirty. Must clear BIO_ERROR to prevent 1245 * pages from being scrapped. If the error is anything 1246 * other than an I/O error (EIO), assume that retrying 1247 * is futile. 1248 */ 1249 bp->b_ioflags &= ~BIO_ERROR; 1250 bdirty(bp); 1251 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1252 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1253 /* 1254 * Either a failed I/O or we were asked to free or not 1255 * cache the buffer. 1256 */ 1257 bp->b_flags |= B_INVAL; 1258 if (!LIST_EMPTY(&bp->b_dep)) 1259 buf_deallocate(bp); 1260 if (bp->b_flags & B_DELWRI) { 1261 atomic_subtract_int(&numdirtybuffers, 1); 1262 numdirtywakeup(lodirtybuffers); 1263 } 1264 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1265 if ((bp->b_flags & B_VMIO) == 0) { 1266 if (bp->b_bufsize) 1267 allocbuf(bp, 0); 1268 if (bp->b_vp) 1269 brelvp(bp); 1270 } 1271 } 1272 1273 /* 1274 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1275 * is called with B_DELWRI set, the underlying pages may wind up 1276 * getting freed causing a previous write (bdwrite()) to get 'lost' 1277 * because pages associated with a B_DELWRI bp are marked clean. 1278 * 1279 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1280 * if B_DELWRI is set. 1281 * 1282 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1283 * on pages to return pages to the VM page queues. 1284 */ 1285 if (bp->b_flags & B_DELWRI) 1286 bp->b_flags &= ~B_RELBUF; 1287 else if (buf_vm_page_count_severe()) { 1288 /* 1289 * The locking of the BO_LOCK is not necessary since 1290 * BKGRDINPROG cannot be set while we hold the buf 1291 * lock, it can only be cleared if it is already 1292 * pending. 1293 */ 1294 if (bp->b_vp) { 1295 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1296 bp->b_flags |= B_RELBUF; 1297 } else 1298 bp->b_flags |= B_RELBUF; 1299 } 1300 1301 /* 1302 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1303 * constituted, not even NFS buffers now. Two flags effect this. If 1304 * B_INVAL, the struct buf is invalidated but the VM object is kept 1305 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1306 * 1307 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1308 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1309 * buffer is also B_INVAL because it hits the re-dirtying code above. 1310 * 1311 * Normally we can do this whether a buffer is B_DELWRI or not. If 1312 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1313 * the commit state and we cannot afford to lose the buffer. If the 1314 * buffer has a background write in progress, we need to keep it 1315 * around to prevent it from being reconstituted and starting a second 1316 * background write. 1317 */ 1318 if ((bp->b_flags & B_VMIO) 1319 && !(bp->b_vp->v_mount != NULL && 1320 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1321 !vn_isdisk(bp->b_vp, NULL) && 1322 (bp->b_flags & B_DELWRI)) 1323 ) { 1324 1325 int i, j, resid; 1326 vm_page_t m; 1327 off_t foff; 1328 vm_pindex_t poff; 1329 vm_object_t obj; 1330 1331 obj = bp->b_bufobj->bo_object; 1332 1333 /* 1334 * Get the base offset and length of the buffer. Note that 1335 * in the VMIO case if the buffer block size is not 1336 * page-aligned then b_data pointer may not be page-aligned. 1337 * But our b_pages[] array *IS* page aligned. 1338 * 1339 * block sizes less then DEV_BSIZE (usually 512) are not 1340 * supported due to the page granularity bits (m->valid, 1341 * m->dirty, etc...). 1342 * 1343 * See man buf(9) for more information 1344 */ 1345 resid = bp->b_bufsize; 1346 foff = bp->b_offset; 1347 VM_OBJECT_LOCK(obj); 1348 for (i = 0; i < bp->b_npages; i++) { 1349 int had_bogus = 0; 1350 1351 m = bp->b_pages[i]; 1352 1353 /* 1354 * If we hit a bogus page, fixup *all* the bogus pages 1355 * now. 1356 */ 1357 if (m == bogus_page) { 1358 poff = OFF_TO_IDX(bp->b_offset); 1359 had_bogus = 1; 1360 1361 for (j = i; j < bp->b_npages; j++) { 1362 vm_page_t mtmp; 1363 mtmp = bp->b_pages[j]; 1364 if (mtmp == bogus_page) { 1365 mtmp = vm_page_lookup(obj, poff + j); 1366 if (!mtmp) { 1367 panic("brelse: page missing\n"); 1368 } 1369 bp->b_pages[j] = mtmp; 1370 } 1371 } 1372 1373 if ((bp->b_flags & B_INVAL) == 0) { 1374 pmap_qenter( 1375 trunc_page((vm_offset_t)bp->b_data), 1376 bp->b_pages, bp->b_npages); 1377 } 1378 m = bp->b_pages[i]; 1379 } 1380 if ((bp->b_flags & B_NOCACHE) || 1381 (bp->b_ioflags & BIO_ERROR && 1382 bp->b_iocmd == BIO_READ)) { 1383 int poffset = foff & PAGE_MASK; 1384 int presid = resid > (PAGE_SIZE - poffset) ? 1385 (PAGE_SIZE - poffset) : resid; 1386 1387 KASSERT(presid >= 0, ("brelse: extra page")); 1388 vm_page_set_invalid(m, poffset, presid); 1389 if (had_bogus) 1390 printf("avoided corruption bug in bogus_page/brelse code\n"); 1391 } 1392 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1393 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1394 } 1395 VM_OBJECT_UNLOCK(obj); 1396 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1397 vfs_vmio_release(bp); 1398 1399 } else if (bp->b_flags & B_VMIO) { 1400 1401 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1402 vfs_vmio_release(bp); 1403 } 1404 1405 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1406 if (bp->b_bufsize != 0) 1407 allocbuf(bp, 0); 1408 if (bp->b_vp != NULL) 1409 brelvp(bp); 1410 } 1411 1412 if (BUF_LOCKRECURSED(bp)) { 1413 /* do not release to free list */ 1414 BUF_UNLOCK(bp); 1415 return; 1416 } 1417 1418 /* enqueue */ 1419 mtx_lock(&bqlock); 1420 /* Handle delayed bremfree() processing. */ 1421 if (bp->b_flags & B_REMFREE) { 1422 struct bufobj *bo; 1423 1424 bo = bp->b_bufobj; 1425 if (bo != NULL) 1426 BO_LOCK(bo); 1427 bremfreel(bp); 1428 if (bo != NULL) 1429 BO_UNLOCK(bo); 1430 } 1431 if (bp->b_qindex != QUEUE_NONE) 1432 panic("brelse: free buffer onto another queue???"); 1433 1434 /* 1435 * If the buffer has junk contents signal it and eventually 1436 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1437 * doesn't find it. 1438 */ 1439 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1440 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1441 bp->b_flags |= B_INVAL; 1442 if (bp->b_flags & B_INVAL) { 1443 if (bp->b_flags & B_DELWRI) 1444 bundirty(bp); 1445 if (bp->b_vp) 1446 brelvp(bp); 1447 } 1448 1449 /* buffers with no memory */ 1450 if (bp->b_bufsize == 0) { 1451 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1452 if (bp->b_vflags & BV_BKGRDINPROG) 1453 panic("losing buffer 1"); 1454 if (bp->b_kvasize) { 1455 bp->b_qindex = QUEUE_EMPTYKVA; 1456 } else { 1457 bp->b_qindex = QUEUE_EMPTY; 1458 } 1459 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1460 /* buffers with junk contents */ 1461 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1462 (bp->b_ioflags & BIO_ERROR)) { 1463 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1464 if (bp->b_vflags & BV_BKGRDINPROG) 1465 panic("losing buffer 2"); 1466 bp->b_qindex = QUEUE_CLEAN; 1467 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1468 /* remaining buffers */ 1469 } else { 1470 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1471 (B_DELWRI|B_NEEDSGIANT)) 1472 bp->b_qindex = QUEUE_DIRTY_GIANT; 1473 else if (bp->b_flags & B_DELWRI) 1474 bp->b_qindex = QUEUE_DIRTY; 1475 else 1476 bp->b_qindex = QUEUE_CLEAN; 1477 if (bp->b_flags & B_AGE) 1478 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1479 else 1480 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1481 } 1482 mtx_unlock(&bqlock); 1483 1484 /* 1485 * Fixup numfreebuffers count. The bp is on an appropriate queue 1486 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1487 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1488 * if B_INVAL is set ). 1489 */ 1490 1491 if (!(bp->b_flags & B_DELWRI)) { 1492 struct bufobj *bo; 1493 1494 bo = bp->b_bufobj; 1495 if (bo != NULL) 1496 BO_LOCK(bo); 1497 bufcountwakeup(bp); 1498 if (bo != NULL) 1499 BO_UNLOCK(bo); 1500 } 1501 1502 /* 1503 * Something we can maybe free or reuse 1504 */ 1505 if (bp->b_bufsize || bp->b_kvasize) 1506 bufspacewakeup(); 1507 1508 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1509 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1510 panic("brelse: not dirty"); 1511 /* unlock */ 1512 BUF_UNLOCK(bp); 1513 } 1514 1515 /* 1516 * Release a buffer back to the appropriate queue but do not try to free 1517 * it. The buffer is expected to be used again soon. 1518 * 1519 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1520 * biodone() to requeue an async I/O on completion. It is also used when 1521 * known good buffers need to be requeued but we think we may need the data 1522 * again soon. 1523 * 1524 * XXX we should be able to leave the B_RELBUF hint set on completion. 1525 */ 1526 void 1527 bqrelse(struct buf *bp) 1528 { 1529 struct bufobj *bo; 1530 1531 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1532 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1533 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1534 1535 if (BUF_LOCKRECURSED(bp)) { 1536 /* do not release to free list */ 1537 BUF_UNLOCK(bp); 1538 return; 1539 } 1540 1541 bo = bp->b_bufobj; 1542 if (bp->b_flags & B_MANAGED) { 1543 if (bp->b_flags & B_REMFREE) { 1544 mtx_lock(&bqlock); 1545 if (bo != NULL) 1546 BO_LOCK(bo); 1547 bremfreel(bp); 1548 if (bo != NULL) 1549 BO_UNLOCK(bo); 1550 mtx_unlock(&bqlock); 1551 } 1552 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1553 BUF_UNLOCK(bp); 1554 return; 1555 } 1556 1557 mtx_lock(&bqlock); 1558 /* Handle delayed bremfree() processing. */ 1559 if (bp->b_flags & B_REMFREE) { 1560 if (bo != NULL) 1561 BO_LOCK(bo); 1562 bremfreel(bp); 1563 if (bo != NULL) 1564 BO_UNLOCK(bo); 1565 } 1566 if (bp->b_qindex != QUEUE_NONE) 1567 panic("bqrelse: free buffer onto another queue???"); 1568 /* buffers with stale but valid contents */ 1569 if (bp->b_flags & B_DELWRI) { 1570 if (bp->b_flags & B_NEEDSGIANT) 1571 bp->b_qindex = QUEUE_DIRTY_GIANT; 1572 else 1573 bp->b_qindex = QUEUE_DIRTY; 1574 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1575 } else { 1576 /* 1577 * The locking of the BO_LOCK for checking of the 1578 * BV_BKGRDINPROG is not necessary since the 1579 * BV_BKGRDINPROG cannot be set while we hold the buf 1580 * lock, it can only be cleared if it is already 1581 * pending. 1582 */ 1583 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1584 bp->b_qindex = QUEUE_CLEAN; 1585 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1586 b_freelist); 1587 } else { 1588 /* 1589 * We are too low on memory, we have to try to free 1590 * the buffer (most importantly: the wired pages 1591 * making up its backing store) *now*. 1592 */ 1593 mtx_unlock(&bqlock); 1594 brelse(bp); 1595 return; 1596 } 1597 } 1598 mtx_unlock(&bqlock); 1599 1600 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) { 1601 if (bo != NULL) 1602 BO_LOCK(bo); 1603 bufcountwakeup(bp); 1604 if (bo != NULL) 1605 BO_UNLOCK(bo); 1606 } 1607 1608 /* 1609 * Something we can maybe free or reuse. 1610 */ 1611 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1612 bufspacewakeup(); 1613 1614 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1615 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1616 panic("bqrelse: not dirty"); 1617 /* unlock */ 1618 BUF_UNLOCK(bp); 1619 } 1620 1621 /* Give pages used by the bp back to the VM system (where possible) */ 1622 static void 1623 vfs_vmio_release(struct buf *bp) 1624 { 1625 int i; 1626 vm_page_t m; 1627 1628 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1629 for (i = 0; i < bp->b_npages; i++) { 1630 m = bp->b_pages[i]; 1631 bp->b_pages[i] = NULL; 1632 /* 1633 * In order to keep page LRU ordering consistent, put 1634 * everything on the inactive queue. 1635 */ 1636 vm_page_lock(m); 1637 vm_page_unwire(m, 0); 1638 /* 1639 * We don't mess with busy pages, it is 1640 * the responsibility of the process that 1641 * busied the pages to deal with them. 1642 */ 1643 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1644 m->wire_count == 0) { 1645 /* 1646 * Might as well free the page if we can and it has 1647 * no valid data. We also free the page if the 1648 * buffer was used for direct I/O 1649 */ 1650 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1651 m->hold_count == 0) { 1652 vm_page_free(m); 1653 } else if (bp->b_flags & B_DIRECT) { 1654 vm_page_try_to_free(m); 1655 } else if (buf_vm_page_count_severe()) { 1656 vm_page_try_to_cache(m); 1657 } 1658 } 1659 vm_page_unlock(m); 1660 } 1661 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1662 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1663 1664 if (bp->b_bufsize) { 1665 bufspacewakeup(); 1666 bp->b_bufsize = 0; 1667 } 1668 bp->b_npages = 0; 1669 bp->b_flags &= ~B_VMIO; 1670 if (bp->b_vp) 1671 brelvp(bp); 1672 } 1673 1674 /* 1675 * Check to see if a block at a particular lbn is available for a clustered 1676 * write. 1677 */ 1678 static int 1679 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1680 { 1681 struct buf *bpa; 1682 int match; 1683 1684 match = 0; 1685 1686 /* If the buf isn't in core skip it */ 1687 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1688 return (0); 1689 1690 /* If the buf is busy we don't want to wait for it */ 1691 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1692 return (0); 1693 1694 /* Only cluster with valid clusterable delayed write buffers */ 1695 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1696 (B_DELWRI | B_CLUSTEROK)) 1697 goto done; 1698 1699 if (bpa->b_bufsize != size) 1700 goto done; 1701 1702 /* 1703 * Check to see if it is in the expected place on disk and that the 1704 * block has been mapped. 1705 */ 1706 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1707 match = 1; 1708 done: 1709 BUF_UNLOCK(bpa); 1710 return (match); 1711 } 1712 1713 /* 1714 * vfs_bio_awrite: 1715 * 1716 * Implement clustered async writes for clearing out B_DELWRI buffers. 1717 * This is much better then the old way of writing only one buffer at 1718 * a time. Note that we may not be presented with the buffers in the 1719 * correct order, so we search for the cluster in both directions. 1720 */ 1721 int 1722 vfs_bio_awrite(struct buf *bp) 1723 { 1724 struct bufobj *bo; 1725 int i; 1726 int j; 1727 daddr_t lblkno = bp->b_lblkno; 1728 struct vnode *vp = bp->b_vp; 1729 int ncl; 1730 int nwritten; 1731 int size; 1732 int maxcl; 1733 1734 bo = &vp->v_bufobj; 1735 /* 1736 * right now we support clustered writing only to regular files. If 1737 * we find a clusterable block we could be in the middle of a cluster 1738 * rather then at the beginning. 1739 */ 1740 if ((vp->v_type == VREG) && 1741 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1742 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1743 1744 size = vp->v_mount->mnt_stat.f_iosize; 1745 maxcl = MAXPHYS / size; 1746 1747 BO_LOCK(bo); 1748 for (i = 1; i < maxcl; i++) 1749 if (vfs_bio_clcheck(vp, size, lblkno + i, 1750 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1751 break; 1752 1753 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1754 if (vfs_bio_clcheck(vp, size, lblkno - j, 1755 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1756 break; 1757 BO_UNLOCK(bo); 1758 --j; 1759 ncl = i + j; 1760 /* 1761 * this is a possible cluster write 1762 */ 1763 if (ncl != 1) { 1764 BUF_UNLOCK(bp); 1765 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1766 return nwritten; 1767 } 1768 } 1769 bremfree(bp); 1770 bp->b_flags |= B_ASYNC; 1771 /* 1772 * default (old) behavior, writing out only one block 1773 * 1774 * XXX returns b_bufsize instead of b_bcount for nwritten? 1775 */ 1776 nwritten = bp->b_bufsize; 1777 (void) bwrite(bp); 1778 1779 return nwritten; 1780 } 1781 1782 /* 1783 * getnewbuf: 1784 * 1785 * Find and initialize a new buffer header, freeing up existing buffers 1786 * in the bufqueues as necessary. The new buffer is returned locked. 1787 * 1788 * Important: B_INVAL is not set. If the caller wishes to throw the 1789 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1790 * 1791 * We block if: 1792 * We have insufficient buffer headers 1793 * We have insufficient buffer space 1794 * buffer_map is too fragmented ( space reservation fails ) 1795 * If we have to flush dirty buffers ( but we try to avoid this ) 1796 * 1797 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1798 * Instead we ask the buf daemon to do it for us. We attempt to 1799 * avoid piecemeal wakeups of the pageout daemon. 1800 */ 1801 1802 static struct buf * 1803 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1804 int gbflags) 1805 { 1806 struct thread *td; 1807 struct buf *bp; 1808 struct buf *nbp; 1809 int defrag = 0; 1810 int nqindex; 1811 static int flushingbufs; 1812 1813 td = curthread; 1814 /* 1815 * We can't afford to block since we might be holding a vnode lock, 1816 * which may prevent system daemons from running. We deal with 1817 * low-memory situations by proactively returning memory and running 1818 * async I/O rather then sync I/O. 1819 */ 1820 atomic_add_int(&getnewbufcalls, 1); 1821 atomic_subtract_int(&getnewbufrestarts, 1); 1822 restart: 1823 atomic_add_int(&getnewbufrestarts, 1); 1824 1825 /* 1826 * Setup for scan. If we do not have enough free buffers, 1827 * we setup a degenerate case that immediately fails. Note 1828 * that if we are specially marked process, we are allowed to 1829 * dip into our reserves. 1830 * 1831 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1832 * 1833 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1834 * However, there are a number of cases (defragging, reusing, ...) 1835 * where we cannot backup. 1836 */ 1837 mtx_lock(&bqlock); 1838 nqindex = QUEUE_EMPTYKVA; 1839 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1840 1841 if (nbp == NULL) { 1842 /* 1843 * If no EMPTYKVA buffers and we are either 1844 * defragging or reusing, locate a CLEAN buffer 1845 * to free or reuse. If bufspace useage is low 1846 * skip this step so we can allocate a new buffer. 1847 */ 1848 if (defrag || bufspace >= lobufspace) { 1849 nqindex = QUEUE_CLEAN; 1850 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1851 } 1852 1853 /* 1854 * If we could not find or were not allowed to reuse a 1855 * CLEAN buffer, check to see if it is ok to use an EMPTY 1856 * buffer. We can only use an EMPTY buffer if allocating 1857 * its KVA would not otherwise run us out of buffer space. 1858 */ 1859 if (nbp == NULL && defrag == 0 && 1860 bufspace + maxsize < hibufspace) { 1861 nqindex = QUEUE_EMPTY; 1862 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1863 } 1864 } 1865 1866 /* 1867 * Run scan, possibly freeing data and/or kva mappings on the fly 1868 * depending. 1869 */ 1870 1871 while ((bp = nbp) != NULL) { 1872 int qindex = nqindex; 1873 1874 /* 1875 * Calculate next bp ( we can only use it if we do not block 1876 * or do other fancy things ). 1877 */ 1878 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1879 switch(qindex) { 1880 case QUEUE_EMPTY: 1881 nqindex = QUEUE_EMPTYKVA; 1882 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1883 break; 1884 /* FALLTHROUGH */ 1885 case QUEUE_EMPTYKVA: 1886 nqindex = QUEUE_CLEAN; 1887 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1888 break; 1889 /* FALLTHROUGH */ 1890 case QUEUE_CLEAN: 1891 /* 1892 * nbp is NULL. 1893 */ 1894 break; 1895 } 1896 } 1897 /* 1898 * If we are defragging then we need a buffer with 1899 * b_kvasize != 0. XXX this situation should no longer 1900 * occur, if defrag is non-zero the buffer's b_kvasize 1901 * should also be non-zero at this point. XXX 1902 */ 1903 if (defrag && bp->b_kvasize == 0) { 1904 printf("Warning: defrag empty buffer %p\n", bp); 1905 continue; 1906 } 1907 1908 /* 1909 * Start freeing the bp. This is somewhat involved. nbp 1910 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1911 */ 1912 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1913 continue; 1914 if (bp->b_vp) { 1915 BO_LOCK(bp->b_bufobj); 1916 if (bp->b_vflags & BV_BKGRDINPROG) { 1917 BO_UNLOCK(bp->b_bufobj); 1918 BUF_UNLOCK(bp); 1919 continue; 1920 } 1921 BO_UNLOCK(bp->b_bufobj); 1922 } 1923 CTR6(KTR_BUF, 1924 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1925 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1926 bp->b_kvasize, bp->b_bufsize, qindex); 1927 1928 /* 1929 * Sanity Checks 1930 */ 1931 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1932 1933 /* 1934 * Note: we no longer distinguish between VMIO and non-VMIO 1935 * buffers. 1936 */ 1937 1938 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1939 1940 if (bp->b_bufobj != NULL) 1941 BO_LOCK(bp->b_bufobj); 1942 bremfreel(bp); 1943 if (bp->b_bufobj != NULL) 1944 BO_UNLOCK(bp->b_bufobj); 1945 mtx_unlock(&bqlock); 1946 1947 if (qindex == QUEUE_CLEAN) { 1948 if (bp->b_flags & B_VMIO) { 1949 bp->b_flags &= ~B_ASYNC; 1950 vfs_vmio_release(bp); 1951 } 1952 if (bp->b_vp) 1953 brelvp(bp); 1954 } 1955 1956 /* 1957 * NOTE: nbp is now entirely invalid. We can only restart 1958 * the scan from this point on. 1959 * 1960 * Get the rest of the buffer freed up. b_kva* is still 1961 * valid after this operation. 1962 */ 1963 1964 if (bp->b_rcred != NOCRED) { 1965 crfree(bp->b_rcred); 1966 bp->b_rcred = NOCRED; 1967 } 1968 if (bp->b_wcred != NOCRED) { 1969 crfree(bp->b_wcred); 1970 bp->b_wcred = NOCRED; 1971 } 1972 if (!LIST_EMPTY(&bp->b_dep)) 1973 buf_deallocate(bp); 1974 if (bp->b_vflags & BV_BKGRDINPROG) 1975 panic("losing buffer 3"); 1976 KASSERT(bp->b_vp == NULL, 1977 ("bp: %p still has vnode %p. qindex: %d", 1978 bp, bp->b_vp, qindex)); 1979 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1980 ("bp: %p still on a buffer list. xflags %X", 1981 bp, bp->b_xflags)); 1982 1983 if (bp->b_bufsize) 1984 allocbuf(bp, 0); 1985 1986 bp->b_flags = 0; 1987 bp->b_ioflags = 0; 1988 bp->b_xflags = 0; 1989 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 1990 ("buf %p still counted as free?", bp)); 1991 bp->b_vflags = 0; 1992 bp->b_vp = NULL; 1993 bp->b_blkno = bp->b_lblkno = 0; 1994 bp->b_offset = NOOFFSET; 1995 bp->b_iodone = 0; 1996 bp->b_error = 0; 1997 bp->b_resid = 0; 1998 bp->b_bcount = 0; 1999 bp->b_npages = 0; 2000 bp->b_dirtyoff = bp->b_dirtyend = 0; 2001 bp->b_bufobj = NULL; 2002 bp->b_pin_count = 0; 2003 bp->b_fsprivate1 = NULL; 2004 bp->b_fsprivate2 = NULL; 2005 bp->b_fsprivate3 = NULL; 2006 2007 LIST_INIT(&bp->b_dep); 2008 2009 /* 2010 * If we are defragging then free the buffer. 2011 */ 2012 if (defrag) { 2013 bp->b_flags |= B_INVAL; 2014 bfreekva(bp); 2015 brelse(bp); 2016 defrag = 0; 2017 goto restart; 2018 } 2019 2020 /* 2021 * Notify any waiters for the buffer lock about 2022 * identity change by freeing the buffer. 2023 */ 2024 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 2025 bp->b_flags |= B_INVAL; 2026 bfreekva(bp); 2027 brelse(bp); 2028 goto restart; 2029 } 2030 2031 /* 2032 * If we are overcomitted then recover the buffer and its 2033 * KVM space. This occurs in rare situations when multiple 2034 * processes are blocked in getnewbuf() or allocbuf(). 2035 */ 2036 if (bufspace >= hibufspace) 2037 flushingbufs = 1; 2038 if (flushingbufs && bp->b_kvasize != 0) { 2039 bp->b_flags |= B_INVAL; 2040 bfreekva(bp); 2041 brelse(bp); 2042 goto restart; 2043 } 2044 if (bufspace < lobufspace) 2045 flushingbufs = 0; 2046 break; 2047 } 2048 2049 /* 2050 * If we exhausted our list, sleep as appropriate. We may have to 2051 * wakeup various daemons and write out some dirty buffers. 2052 * 2053 * Generally we are sleeping due to insufficient buffer space. 2054 */ 2055 2056 if (bp == NULL) { 2057 int flags, norunbuf; 2058 char *waitmsg; 2059 int fl; 2060 2061 if (defrag) { 2062 flags = VFS_BIO_NEED_BUFSPACE; 2063 waitmsg = "nbufkv"; 2064 } else if (bufspace >= hibufspace) { 2065 waitmsg = "nbufbs"; 2066 flags = VFS_BIO_NEED_BUFSPACE; 2067 } else { 2068 waitmsg = "newbuf"; 2069 flags = VFS_BIO_NEED_ANY; 2070 } 2071 mtx_lock(&nblock); 2072 needsbuffer |= flags; 2073 mtx_unlock(&nblock); 2074 mtx_unlock(&bqlock); 2075 2076 bd_speedup(); /* heeeelp */ 2077 if (gbflags & GB_NOWAIT_BD) 2078 return (NULL); 2079 2080 mtx_lock(&nblock); 2081 while (needsbuffer & flags) { 2082 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2083 mtx_unlock(&nblock); 2084 /* 2085 * getblk() is called with a vnode 2086 * locked, and some majority of the 2087 * dirty buffers may as well belong to 2088 * the vnode. Flushing the buffers 2089 * there would make a progress that 2090 * cannot be achieved by the 2091 * buf_daemon, that cannot lock the 2092 * vnode. 2093 */ 2094 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2095 (td->td_pflags & TDP_NORUNNINGBUF); 2096 /* play bufdaemon */ 2097 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2098 fl = buf_do_flush(vp); 2099 td->td_pflags &= norunbuf; 2100 mtx_lock(&nblock); 2101 if (fl != 0) 2102 continue; 2103 if ((needsbuffer & flags) == 0) 2104 break; 2105 } 2106 if (msleep(&needsbuffer, &nblock, 2107 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2108 mtx_unlock(&nblock); 2109 return (NULL); 2110 } 2111 } 2112 mtx_unlock(&nblock); 2113 } else { 2114 /* 2115 * We finally have a valid bp. We aren't quite out of the 2116 * woods, we still have to reserve kva space. In order 2117 * to keep fragmentation sane we only allocate kva in 2118 * BKVASIZE chunks. 2119 */ 2120 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2121 2122 if (maxsize != bp->b_kvasize) { 2123 vm_offset_t addr = 0; 2124 2125 bfreekva(bp); 2126 2127 vm_map_lock(buffer_map); 2128 if (vm_map_findspace(buffer_map, 2129 vm_map_min(buffer_map), maxsize, &addr)) { 2130 /* 2131 * Uh oh. Buffer map is to fragmented. We 2132 * must defragment the map. 2133 */ 2134 atomic_add_int(&bufdefragcnt, 1); 2135 vm_map_unlock(buffer_map); 2136 defrag = 1; 2137 bp->b_flags |= B_INVAL; 2138 brelse(bp); 2139 goto restart; 2140 } 2141 if (addr) { 2142 vm_map_insert(buffer_map, NULL, 0, 2143 addr, addr + maxsize, 2144 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2145 2146 bp->b_kvabase = (caddr_t) addr; 2147 bp->b_kvasize = maxsize; 2148 atomic_add_long(&bufspace, bp->b_kvasize); 2149 atomic_add_int(&bufreusecnt, 1); 2150 } 2151 vm_map_unlock(buffer_map); 2152 } 2153 bp->b_saveaddr = bp->b_kvabase; 2154 bp->b_data = bp->b_saveaddr; 2155 } 2156 return(bp); 2157 } 2158 2159 /* 2160 * buf_daemon: 2161 * 2162 * buffer flushing daemon. Buffers are normally flushed by the 2163 * update daemon but if it cannot keep up this process starts to 2164 * take the load in an attempt to prevent getnewbuf() from blocking. 2165 */ 2166 2167 static struct kproc_desc buf_kp = { 2168 "bufdaemon", 2169 buf_daemon, 2170 &bufdaemonproc 2171 }; 2172 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2173 2174 static int 2175 buf_do_flush(struct vnode *vp) 2176 { 2177 int flushed; 2178 2179 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2180 /* The list empty check here is slightly racy */ 2181 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2182 mtx_lock(&Giant); 2183 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0); 2184 mtx_unlock(&Giant); 2185 } 2186 if (flushed == 0) { 2187 /* 2188 * Could not find any buffers without rollback 2189 * dependencies, so just write the first one 2190 * in the hopes of eventually making progress. 2191 */ 2192 flushbufqueues(vp, QUEUE_DIRTY, 1); 2193 if (!TAILQ_EMPTY( 2194 &bufqueues[QUEUE_DIRTY_GIANT])) { 2195 mtx_lock(&Giant); 2196 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1); 2197 mtx_unlock(&Giant); 2198 } 2199 } 2200 return (flushed); 2201 } 2202 2203 static void 2204 buf_daemon() 2205 { 2206 int lodirtysave; 2207 2208 /* 2209 * This process needs to be suspended prior to shutdown sync. 2210 */ 2211 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2212 SHUTDOWN_PRI_LAST); 2213 2214 /* 2215 * This process is allowed to take the buffer cache to the limit 2216 */ 2217 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2218 mtx_lock(&bdlock); 2219 for (;;) { 2220 bd_request = 0; 2221 mtx_unlock(&bdlock); 2222 2223 kproc_suspend_check(bufdaemonproc); 2224 lodirtysave = lodirtybuffers; 2225 if (bd_speedupreq) { 2226 lodirtybuffers = numdirtybuffers / 2; 2227 bd_speedupreq = 0; 2228 } 2229 /* 2230 * Do the flush. Limit the amount of in-transit I/O we 2231 * allow to build up, otherwise we would completely saturate 2232 * the I/O system. Wakeup any waiting processes before we 2233 * normally would so they can run in parallel with our drain. 2234 */ 2235 while (numdirtybuffers > lodirtybuffers) { 2236 if (buf_do_flush(NULL) == 0) 2237 break; 2238 uio_yield(); 2239 } 2240 lodirtybuffers = lodirtysave; 2241 2242 /* 2243 * Only clear bd_request if we have reached our low water 2244 * mark. The buf_daemon normally waits 1 second and 2245 * then incrementally flushes any dirty buffers that have 2246 * built up, within reason. 2247 * 2248 * If we were unable to hit our low water mark and couldn't 2249 * find any flushable buffers, we sleep half a second. 2250 * Otherwise we loop immediately. 2251 */ 2252 mtx_lock(&bdlock); 2253 if (numdirtybuffers <= lodirtybuffers) { 2254 /* 2255 * We reached our low water mark, reset the 2256 * request and sleep until we are needed again. 2257 * The sleep is just so the suspend code works. 2258 */ 2259 bd_request = 0; 2260 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2261 } else { 2262 /* 2263 * We couldn't find any flushable dirty buffers but 2264 * still have too many dirty buffers, we 2265 * have to sleep and try again. (rare) 2266 */ 2267 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2268 } 2269 } 2270 } 2271 2272 /* 2273 * flushbufqueues: 2274 * 2275 * Try to flush a buffer in the dirty queue. We must be careful to 2276 * free up B_INVAL buffers instead of write them, which NFS is 2277 * particularly sensitive to. 2278 */ 2279 static int flushwithdeps = 0; 2280 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2281 0, "Number of buffers flushed with dependecies that require rollbacks"); 2282 2283 static int 2284 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2285 { 2286 struct buf *sentinel; 2287 struct vnode *vp; 2288 struct mount *mp; 2289 struct buf *bp; 2290 int hasdeps; 2291 int flushed; 2292 int target; 2293 2294 if (lvp == NULL) { 2295 target = numdirtybuffers - lodirtybuffers; 2296 if (flushdeps && target > 2) 2297 target /= 2; 2298 } else 2299 target = flushbufqtarget; 2300 flushed = 0; 2301 bp = NULL; 2302 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2303 sentinel->b_qindex = QUEUE_SENTINEL; 2304 mtx_lock(&bqlock); 2305 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2306 while (flushed != target) { 2307 bp = TAILQ_NEXT(sentinel, b_freelist); 2308 if (bp != NULL) { 2309 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2310 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2311 b_freelist); 2312 } else 2313 break; 2314 /* 2315 * Skip sentinels inserted by other invocations of the 2316 * flushbufqueues(), taking care to not reorder them. 2317 */ 2318 if (bp->b_qindex == QUEUE_SENTINEL) 2319 continue; 2320 /* 2321 * Only flush the buffers that belong to the 2322 * vnode locked by the curthread. 2323 */ 2324 if (lvp != NULL && bp->b_vp != lvp) 2325 continue; 2326 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2327 continue; 2328 if (bp->b_pin_count > 0) { 2329 BUF_UNLOCK(bp); 2330 continue; 2331 } 2332 BO_LOCK(bp->b_bufobj); 2333 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2334 (bp->b_flags & B_DELWRI) == 0) { 2335 BO_UNLOCK(bp->b_bufobj); 2336 BUF_UNLOCK(bp); 2337 continue; 2338 } 2339 BO_UNLOCK(bp->b_bufobj); 2340 if (bp->b_flags & B_INVAL) { 2341 bremfreel(bp); 2342 mtx_unlock(&bqlock); 2343 brelse(bp); 2344 flushed++; 2345 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2346 mtx_lock(&bqlock); 2347 continue; 2348 } 2349 2350 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2351 if (flushdeps == 0) { 2352 BUF_UNLOCK(bp); 2353 continue; 2354 } 2355 hasdeps = 1; 2356 } else 2357 hasdeps = 0; 2358 /* 2359 * We must hold the lock on a vnode before writing 2360 * one of its buffers. Otherwise we may confuse, or 2361 * in the case of a snapshot vnode, deadlock the 2362 * system. 2363 * 2364 * The lock order here is the reverse of the normal 2365 * of vnode followed by buf lock. This is ok because 2366 * the NOWAIT will prevent deadlock. 2367 */ 2368 vp = bp->b_vp; 2369 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2370 BUF_UNLOCK(bp); 2371 continue; 2372 } 2373 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2374 mtx_unlock(&bqlock); 2375 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2376 bp, bp->b_vp, bp->b_flags); 2377 if (curproc == bufdaemonproc) 2378 vfs_bio_awrite(bp); 2379 else { 2380 bremfree(bp); 2381 bwrite(bp); 2382 notbufdflashes++; 2383 } 2384 vn_finished_write(mp); 2385 VOP_UNLOCK(vp, 0); 2386 flushwithdeps += hasdeps; 2387 flushed++; 2388 2389 /* 2390 * Sleeping on runningbufspace while holding 2391 * vnode lock leads to deadlock. 2392 */ 2393 if (curproc == bufdaemonproc) 2394 waitrunningbufspace(); 2395 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2396 mtx_lock(&bqlock); 2397 continue; 2398 } 2399 vn_finished_write(mp); 2400 BUF_UNLOCK(bp); 2401 } 2402 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2403 mtx_unlock(&bqlock); 2404 free(sentinel, M_TEMP); 2405 return (flushed); 2406 } 2407 2408 /* 2409 * Check to see if a block is currently memory resident. 2410 */ 2411 struct buf * 2412 incore(struct bufobj *bo, daddr_t blkno) 2413 { 2414 struct buf *bp; 2415 2416 BO_LOCK(bo); 2417 bp = gbincore(bo, blkno); 2418 BO_UNLOCK(bo); 2419 return (bp); 2420 } 2421 2422 /* 2423 * Returns true if no I/O is needed to access the 2424 * associated VM object. This is like incore except 2425 * it also hunts around in the VM system for the data. 2426 */ 2427 2428 static int 2429 inmem(struct vnode * vp, daddr_t blkno) 2430 { 2431 vm_object_t obj; 2432 vm_offset_t toff, tinc, size; 2433 vm_page_t m; 2434 vm_ooffset_t off; 2435 2436 ASSERT_VOP_LOCKED(vp, "inmem"); 2437 2438 if (incore(&vp->v_bufobj, blkno)) 2439 return 1; 2440 if (vp->v_mount == NULL) 2441 return 0; 2442 obj = vp->v_object; 2443 if (obj == NULL) 2444 return (0); 2445 2446 size = PAGE_SIZE; 2447 if (size > vp->v_mount->mnt_stat.f_iosize) 2448 size = vp->v_mount->mnt_stat.f_iosize; 2449 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2450 2451 VM_OBJECT_LOCK(obj); 2452 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2453 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2454 if (!m) 2455 goto notinmem; 2456 tinc = size; 2457 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2458 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2459 if (vm_page_is_valid(m, 2460 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2461 goto notinmem; 2462 } 2463 VM_OBJECT_UNLOCK(obj); 2464 return 1; 2465 2466 notinmem: 2467 VM_OBJECT_UNLOCK(obj); 2468 return (0); 2469 } 2470 2471 /* 2472 * Set the dirty range for a buffer based on the status of the dirty 2473 * bits in the pages comprising the buffer. The range is limited 2474 * to the size of the buffer. 2475 * 2476 * Tell the VM system that the pages associated with this buffer 2477 * are clean. This is used for delayed writes where the data is 2478 * going to go to disk eventually without additional VM intevention. 2479 * 2480 * Note that while we only really need to clean through to b_bcount, we 2481 * just go ahead and clean through to b_bufsize. 2482 */ 2483 static void 2484 vfs_clean_pages_dirty_buf(struct buf *bp) 2485 { 2486 vm_ooffset_t foff, noff, eoff; 2487 vm_page_t m; 2488 int i; 2489 2490 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2491 return; 2492 2493 foff = bp->b_offset; 2494 KASSERT(bp->b_offset != NOOFFSET, 2495 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2496 2497 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2498 vfs_drain_busy_pages(bp); 2499 vfs_setdirty_locked_object(bp); 2500 for (i = 0; i < bp->b_npages; i++) { 2501 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2502 eoff = noff; 2503 if (eoff > bp->b_offset + bp->b_bufsize) 2504 eoff = bp->b_offset + bp->b_bufsize; 2505 m = bp->b_pages[i]; 2506 vfs_page_set_validclean(bp, foff, m); 2507 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2508 foff = noff; 2509 } 2510 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2511 } 2512 2513 static void 2514 vfs_setdirty_locked_object(struct buf *bp) 2515 { 2516 vm_object_t object; 2517 int i; 2518 2519 object = bp->b_bufobj->bo_object; 2520 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2521 2522 /* 2523 * We qualify the scan for modified pages on whether the 2524 * object has been flushed yet. 2525 */ 2526 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2527 vm_offset_t boffset; 2528 vm_offset_t eoffset; 2529 2530 /* 2531 * test the pages to see if they have been modified directly 2532 * by users through the VM system. 2533 */ 2534 for (i = 0; i < bp->b_npages; i++) 2535 vm_page_test_dirty(bp->b_pages[i]); 2536 2537 /* 2538 * Calculate the encompassing dirty range, boffset and eoffset, 2539 * (eoffset - boffset) bytes. 2540 */ 2541 2542 for (i = 0; i < bp->b_npages; i++) { 2543 if (bp->b_pages[i]->dirty) 2544 break; 2545 } 2546 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2547 2548 for (i = bp->b_npages - 1; i >= 0; --i) { 2549 if (bp->b_pages[i]->dirty) { 2550 break; 2551 } 2552 } 2553 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2554 2555 /* 2556 * Fit it to the buffer. 2557 */ 2558 2559 if (eoffset > bp->b_bcount) 2560 eoffset = bp->b_bcount; 2561 2562 /* 2563 * If we have a good dirty range, merge with the existing 2564 * dirty range. 2565 */ 2566 2567 if (boffset < eoffset) { 2568 if (bp->b_dirtyoff > boffset) 2569 bp->b_dirtyoff = boffset; 2570 if (bp->b_dirtyend < eoffset) 2571 bp->b_dirtyend = eoffset; 2572 } 2573 } 2574 } 2575 2576 /* 2577 * getblk: 2578 * 2579 * Get a block given a specified block and offset into a file/device. 2580 * The buffers B_DONE bit will be cleared on return, making it almost 2581 * ready for an I/O initiation. B_INVAL may or may not be set on 2582 * return. The caller should clear B_INVAL prior to initiating a 2583 * READ. 2584 * 2585 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2586 * an existing buffer. 2587 * 2588 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2589 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2590 * and then cleared based on the backing VM. If the previous buffer is 2591 * non-0-sized but invalid, B_CACHE will be cleared. 2592 * 2593 * If getblk() must create a new buffer, the new buffer is returned with 2594 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2595 * case it is returned with B_INVAL clear and B_CACHE set based on the 2596 * backing VM. 2597 * 2598 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2599 * B_CACHE bit is clear. 2600 * 2601 * What this means, basically, is that the caller should use B_CACHE to 2602 * determine whether the buffer is fully valid or not and should clear 2603 * B_INVAL prior to issuing a read. If the caller intends to validate 2604 * the buffer by loading its data area with something, the caller needs 2605 * to clear B_INVAL. If the caller does this without issuing an I/O, 2606 * the caller should set B_CACHE ( as an optimization ), else the caller 2607 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2608 * a write attempt or if it was a successfull read. If the caller 2609 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2610 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2611 */ 2612 struct buf * 2613 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2614 int flags) 2615 { 2616 struct buf *bp; 2617 struct bufobj *bo; 2618 int error; 2619 2620 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2621 ASSERT_VOP_LOCKED(vp, "getblk"); 2622 if (size > MAXBSIZE) 2623 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2624 2625 bo = &vp->v_bufobj; 2626 loop: 2627 /* 2628 * Block if we are low on buffers. Certain processes are allowed 2629 * to completely exhaust the buffer cache. 2630 * 2631 * If this check ever becomes a bottleneck it may be better to 2632 * move it into the else, when gbincore() fails. At the moment 2633 * it isn't a problem. 2634 * 2635 * XXX remove if 0 sections (clean this up after its proven) 2636 */ 2637 if (numfreebuffers == 0) { 2638 if (TD_IS_IDLETHREAD(curthread)) 2639 return NULL; 2640 mtx_lock(&nblock); 2641 needsbuffer |= VFS_BIO_NEED_ANY; 2642 mtx_unlock(&nblock); 2643 } 2644 2645 BO_LOCK(bo); 2646 bp = gbincore(bo, blkno); 2647 if (bp != NULL) { 2648 int lockflags; 2649 /* 2650 * Buffer is in-core. If the buffer is not busy, it must 2651 * be on a queue. 2652 */ 2653 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2654 2655 if (flags & GB_LOCK_NOWAIT) 2656 lockflags |= LK_NOWAIT; 2657 2658 error = BUF_TIMELOCK(bp, lockflags, 2659 BO_MTX(bo), "getblk", slpflag, slptimeo); 2660 2661 /* 2662 * If we slept and got the lock we have to restart in case 2663 * the buffer changed identities. 2664 */ 2665 if (error == ENOLCK) 2666 goto loop; 2667 /* We timed out or were interrupted. */ 2668 else if (error) 2669 return (NULL); 2670 2671 /* 2672 * The buffer is locked. B_CACHE is cleared if the buffer is 2673 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2674 * and for a VMIO buffer B_CACHE is adjusted according to the 2675 * backing VM cache. 2676 */ 2677 if (bp->b_flags & B_INVAL) 2678 bp->b_flags &= ~B_CACHE; 2679 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2680 bp->b_flags |= B_CACHE; 2681 BO_LOCK(bo); 2682 bremfree(bp); 2683 BO_UNLOCK(bo); 2684 2685 /* 2686 * check for size inconsistancies for non-VMIO case. 2687 */ 2688 2689 if (bp->b_bcount != size) { 2690 if ((bp->b_flags & B_VMIO) == 0 || 2691 (size > bp->b_kvasize)) { 2692 if (bp->b_flags & B_DELWRI) { 2693 /* 2694 * If buffer is pinned and caller does 2695 * not want sleep waiting for it to be 2696 * unpinned, bail out 2697 * */ 2698 if (bp->b_pin_count > 0) { 2699 if (flags & GB_LOCK_NOWAIT) { 2700 bqrelse(bp); 2701 return (NULL); 2702 } else { 2703 bunpin_wait(bp); 2704 } 2705 } 2706 bp->b_flags |= B_NOCACHE; 2707 bwrite(bp); 2708 } else { 2709 if (LIST_EMPTY(&bp->b_dep)) { 2710 bp->b_flags |= B_RELBUF; 2711 brelse(bp); 2712 } else { 2713 bp->b_flags |= B_NOCACHE; 2714 bwrite(bp); 2715 } 2716 } 2717 goto loop; 2718 } 2719 } 2720 2721 /* 2722 * If the size is inconsistant in the VMIO case, we can resize 2723 * the buffer. This might lead to B_CACHE getting set or 2724 * cleared. If the size has not changed, B_CACHE remains 2725 * unchanged from its previous state. 2726 */ 2727 2728 if (bp->b_bcount != size) 2729 allocbuf(bp, size); 2730 2731 KASSERT(bp->b_offset != NOOFFSET, 2732 ("getblk: no buffer offset")); 2733 2734 /* 2735 * A buffer with B_DELWRI set and B_CACHE clear must 2736 * be committed before we can return the buffer in 2737 * order to prevent the caller from issuing a read 2738 * ( due to B_CACHE not being set ) and overwriting 2739 * it. 2740 * 2741 * Most callers, including NFS and FFS, need this to 2742 * operate properly either because they assume they 2743 * can issue a read if B_CACHE is not set, or because 2744 * ( for example ) an uncached B_DELWRI might loop due 2745 * to softupdates re-dirtying the buffer. In the latter 2746 * case, B_CACHE is set after the first write completes, 2747 * preventing further loops. 2748 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2749 * above while extending the buffer, we cannot allow the 2750 * buffer to remain with B_CACHE set after the write 2751 * completes or it will represent a corrupt state. To 2752 * deal with this we set B_NOCACHE to scrap the buffer 2753 * after the write. 2754 * 2755 * We might be able to do something fancy, like setting 2756 * B_CACHE in bwrite() except if B_DELWRI is already set, 2757 * so the below call doesn't set B_CACHE, but that gets real 2758 * confusing. This is much easier. 2759 */ 2760 2761 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2762 bp->b_flags |= B_NOCACHE; 2763 bwrite(bp); 2764 goto loop; 2765 } 2766 bp->b_flags &= ~B_DONE; 2767 } else { 2768 int bsize, maxsize, vmio; 2769 off_t offset; 2770 2771 /* 2772 * Buffer is not in-core, create new buffer. The buffer 2773 * returned by getnewbuf() is locked. Note that the returned 2774 * buffer is also considered valid (not marked B_INVAL). 2775 */ 2776 BO_UNLOCK(bo); 2777 /* 2778 * If the user does not want us to create the buffer, bail out 2779 * here. 2780 */ 2781 if (flags & GB_NOCREAT) 2782 return NULL; 2783 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 2784 offset = blkno * bsize; 2785 vmio = vp->v_object != NULL; 2786 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2787 maxsize = imax(maxsize, bsize); 2788 2789 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2790 if (bp == NULL) { 2791 if (slpflag || slptimeo) 2792 return NULL; 2793 goto loop; 2794 } 2795 2796 /* 2797 * This code is used to make sure that a buffer is not 2798 * created while the getnewbuf routine is blocked. 2799 * This can be a problem whether the vnode is locked or not. 2800 * If the buffer is created out from under us, we have to 2801 * throw away the one we just created. 2802 * 2803 * Note: this must occur before we associate the buffer 2804 * with the vp especially considering limitations in 2805 * the splay tree implementation when dealing with duplicate 2806 * lblkno's. 2807 */ 2808 BO_LOCK(bo); 2809 if (gbincore(bo, blkno)) { 2810 BO_UNLOCK(bo); 2811 bp->b_flags |= B_INVAL; 2812 brelse(bp); 2813 goto loop; 2814 } 2815 2816 /* 2817 * Insert the buffer into the hash, so that it can 2818 * be found by incore. 2819 */ 2820 bp->b_blkno = bp->b_lblkno = blkno; 2821 bp->b_offset = offset; 2822 bgetvp(vp, bp); 2823 BO_UNLOCK(bo); 2824 2825 /* 2826 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2827 * buffer size starts out as 0, B_CACHE will be set by 2828 * allocbuf() for the VMIO case prior to it testing the 2829 * backing store for validity. 2830 */ 2831 2832 if (vmio) { 2833 bp->b_flags |= B_VMIO; 2834 #if defined(VFS_BIO_DEBUG) 2835 if (vn_canvmio(vp) != TRUE) 2836 printf("getblk: VMIO on vnode type %d\n", 2837 vp->v_type); 2838 #endif 2839 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2840 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2841 bp, vp->v_object, bp->b_bufobj->bo_object)); 2842 } else { 2843 bp->b_flags &= ~B_VMIO; 2844 KASSERT(bp->b_bufobj->bo_object == NULL, 2845 ("ARGH! has b_bufobj->bo_object %p %p\n", 2846 bp, bp->b_bufobj->bo_object)); 2847 } 2848 2849 allocbuf(bp, size); 2850 bp->b_flags &= ~B_DONE; 2851 } 2852 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2853 BUF_ASSERT_HELD(bp); 2854 KASSERT(bp->b_bufobj == bo, 2855 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2856 return (bp); 2857 } 2858 2859 /* 2860 * Get an empty, disassociated buffer of given size. The buffer is initially 2861 * set to B_INVAL. 2862 */ 2863 struct buf * 2864 geteblk(int size, int flags) 2865 { 2866 struct buf *bp; 2867 int maxsize; 2868 2869 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2870 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2871 if ((flags & GB_NOWAIT_BD) && 2872 (curthread->td_pflags & TDP_BUFNEED) != 0) 2873 return (NULL); 2874 } 2875 allocbuf(bp, size); 2876 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2877 BUF_ASSERT_HELD(bp); 2878 return (bp); 2879 } 2880 2881 2882 /* 2883 * This code constitutes the buffer memory from either anonymous system 2884 * memory (in the case of non-VMIO operations) or from an associated 2885 * VM object (in the case of VMIO operations). This code is able to 2886 * resize a buffer up or down. 2887 * 2888 * Note that this code is tricky, and has many complications to resolve 2889 * deadlock or inconsistant data situations. Tread lightly!!! 2890 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2891 * the caller. Calling this code willy nilly can result in the loss of data. 2892 * 2893 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2894 * B_CACHE for the non-VMIO case. 2895 */ 2896 2897 int 2898 allocbuf(struct buf *bp, int size) 2899 { 2900 int newbsize, mbsize; 2901 int i; 2902 2903 BUF_ASSERT_HELD(bp); 2904 2905 if (bp->b_kvasize < size) 2906 panic("allocbuf: buffer too small"); 2907 2908 if ((bp->b_flags & B_VMIO) == 0) { 2909 caddr_t origbuf; 2910 int origbufsize; 2911 /* 2912 * Just get anonymous memory from the kernel. Don't 2913 * mess with B_CACHE. 2914 */ 2915 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2916 if (bp->b_flags & B_MALLOC) 2917 newbsize = mbsize; 2918 else 2919 newbsize = round_page(size); 2920 2921 if (newbsize < bp->b_bufsize) { 2922 /* 2923 * malloced buffers are not shrunk 2924 */ 2925 if (bp->b_flags & B_MALLOC) { 2926 if (newbsize) { 2927 bp->b_bcount = size; 2928 } else { 2929 free(bp->b_data, M_BIOBUF); 2930 if (bp->b_bufsize) { 2931 atomic_subtract_long( 2932 &bufmallocspace, 2933 bp->b_bufsize); 2934 bufspacewakeup(); 2935 bp->b_bufsize = 0; 2936 } 2937 bp->b_saveaddr = bp->b_kvabase; 2938 bp->b_data = bp->b_saveaddr; 2939 bp->b_bcount = 0; 2940 bp->b_flags &= ~B_MALLOC; 2941 } 2942 return 1; 2943 } 2944 vm_hold_free_pages(bp, newbsize); 2945 } else if (newbsize > bp->b_bufsize) { 2946 /* 2947 * We only use malloced memory on the first allocation. 2948 * and revert to page-allocated memory when the buffer 2949 * grows. 2950 */ 2951 /* 2952 * There is a potential smp race here that could lead 2953 * to bufmallocspace slightly passing the max. It 2954 * is probably extremely rare and not worth worrying 2955 * over. 2956 */ 2957 if ( (bufmallocspace < maxbufmallocspace) && 2958 (bp->b_bufsize == 0) && 2959 (mbsize <= PAGE_SIZE/2)) { 2960 2961 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2962 bp->b_bufsize = mbsize; 2963 bp->b_bcount = size; 2964 bp->b_flags |= B_MALLOC; 2965 atomic_add_long(&bufmallocspace, mbsize); 2966 return 1; 2967 } 2968 origbuf = NULL; 2969 origbufsize = 0; 2970 /* 2971 * If the buffer is growing on its other-than-first allocation, 2972 * then we revert to the page-allocation scheme. 2973 */ 2974 if (bp->b_flags & B_MALLOC) { 2975 origbuf = bp->b_data; 2976 origbufsize = bp->b_bufsize; 2977 bp->b_data = bp->b_kvabase; 2978 if (bp->b_bufsize) { 2979 atomic_subtract_long(&bufmallocspace, 2980 bp->b_bufsize); 2981 bufspacewakeup(); 2982 bp->b_bufsize = 0; 2983 } 2984 bp->b_flags &= ~B_MALLOC; 2985 newbsize = round_page(newbsize); 2986 } 2987 vm_hold_load_pages( 2988 bp, 2989 (vm_offset_t) bp->b_data + bp->b_bufsize, 2990 (vm_offset_t) bp->b_data + newbsize); 2991 if (origbuf) { 2992 bcopy(origbuf, bp->b_data, origbufsize); 2993 free(origbuf, M_BIOBUF); 2994 } 2995 } 2996 } else { 2997 int desiredpages; 2998 2999 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 3000 desiredpages = (size == 0) ? 0 : 3001 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 3002 3003 if (bp->b_flags & B_MALLOC) 3004 panic("allocbuf: VMIO buffer can't be malloced"); 3005 /* 3006 * Set B_CACHE initially if buffer is 0 length or will become 3007 * 0-length. 3008 */ 3009 if (size == 0 || bp->b_bufsize == 0) 3010 bp->b_flags |= B_CACHE; 3011 3012 if (newbsize < bp->b_bufsize) { 3013 /* 3014 * DEV_BSIZE aligned new buffer size is less then the 3015 * DEV_BSIZE aligned existing buffer size. Figure out 3016 * if we have to remove any pages. 3017 */ 3018 if (desiredpages < bp->b_npages) { 3019 vm_page_t m; 3020 3021 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3022 for (i = desiredpages; i < bp->b_npages; i++) { 3023 /* 3024 * the page is not freed here -- it 3025 * is the responsibility of 3026 * vnode_pager_setsize 3027 */ 3028 m = bp->b_pages[i]; 3029 KASSERT(m != bogus_page, 3030 ("allocbuf: bogus page found")); 3031 while (vm_page_sleep_if_busy(m, TRUE, 3032 "biodep")) 3033 continue; 3034 3035 bp->b_pages[i] = NULL; 3036 vm_page_lock(m); 3037 vm_page_unwire(m, 0); 3038 vm_page_unlock(m); 3039 } 3040 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3041 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 3042 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 3043 bp->b_npages = desiredpages; 3044 } 3045 } else if (size > bp->b_bcount) { 3046 /* 3047 * We are growing the buffer, possibly in a 3048 * byte-granular fashion. 3049 */ 3050 vm_object_t obj; 3051 vm_offset_t toff; 3052 vm_offset_t tinc; 3053 3054 /* 3055 * Step 1, bring in the VM pages from the object, 3056 * allocating them if necessary. We must clear 3057 * B_CACHE if these pages are not valid for the 3058 * range covered by the buffer. 3059 */ 3060 3061 obj = bp->b_bufobj->bo_object; 3062 3063 VM_OBJECT_LOCK(obj); 3064 while (bp->b_npages < desiredpages) { 3065 vm_page_t m; 3066 3067 /* 3068 * We must allocate system pages since blocking 3069 * here could intefere with paging I/O, no 3070 * matter which process we are. 3071 * 3072 * We can only test VPO_BUSY here. Blocking on 3073 * m->busy might lead to a deadlock: 3074 * vm_fault->getpages->cluster_read->allocbuf 3075 * Thus, we specify VM_ALLOC_IGN_SBUSY. 3076 */ 3077 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3078 bp->b_npages, VM_ALLOC_NOBUSY | 3079 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3080 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | 3081 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3082 if (m->valid == 0) 3083 bp->b_flags &= ~B_CACHE; 3084 bp->b_pages[bp->b_npages] = m; 3085 ++bp->b_npages; 3086 } 3087 3088 /* 3089 * Step 2. We've loaded the pages into the buffer, 3090 * we have to figure out if we can still have B_CACHE 3091 * set. Note that B_CACHE is set according to the 3092 * byte-granular range ( bcount and size ), new the 3093 * aligned range ( newbsize ). 3094 * 3095 * The VM test is against m->valid, which is DEV_BSIZE 3096 * aligned. Needless to say, the validity of the data 3097 * needs to also be DEV_BSIZE aligned. Note that this 3098 * fails with NFS if the server or some other client 3099 * extends the file's EOF. If our buffer is resized, 3100 * B_CACHE may remain set! XXX 3101 */ 3102 3103 toff = bp->b_bcount; 3104 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3105 3106 while ((bp->b_flags & B_CACHE) && toff < size) { 3107 vm_pindex_t pi; 3108 3109 if (tinc > (size - toff)) 3110 tinc = size - toff; 3111 3112 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3113 PAGE_SHIFT; 3114 3115 vfs_buf_test_cache( 3116 bp, 3117 bp->b_offset, 3118 toff, 3119 tinc, 3120 bp->b_pages[pi] 3121 ); 3122 toff += tinc; 3123 tinc = PAGE_SIZE; 3124 } 3125 VM_OBJECT_UNLOCK(obj); 3126 3127 /* 3128 * Step 3, fixup the KVM pmap. Remember that 3129 * bp->b_data is relative to bp->b_offset, but 3130 * bp->b_offset may be offset into the first page. 3131 */ 3132 3133 bp->b_data = (caddr_t) 3134 trunc_page((vm_offset_t)bp->b_data); 3135 pmap_qenter( 3136 (vm_offset_t)bp->b_data, 3137 bp->b_pages, 3138 bp->b_npages 3139 ); 3140 3141 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3142 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3143 } 3144 } 3145 if (newbsize < bp->b_bufsize) 3146 bufspacewakeup(); 3147 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3148 bp->b_bcount = size; /* requested buffer size */ 3149 return 1; 3150 } 3151 3152 void 3153 biodone(struct bio *bp) 3154 { 3155 struct mtx *mtxp; 3156 void (*done)(struct bio *); 3157 3158 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3159 mtx_lock(mtxp); 3160 bp->bio_flags |= BIO_DONE; 3161 done = bp->bio_done; 3162 if (done == NULL) 3163 wakeup(bp); 3164 mtx_unlock(mtxp); 3165 if (done != NULL) 3166 done(bp); 3167 } 3168 3169 /* 3170 * Wait for a BIO to finish. 3171 * 3172 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3173 * case is not yet clear. 3174 */ 3175 int 3176 biowait(struct bio *bp, const char *wchan) 3177 { 3178 struct mtx *mtxp; 3179 3180 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3181 mtx_lock(mtxp); 3182 while ((bp->bio_flags & BIO_DONE) == 0) 3183 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3184 mtx_unlock(mtxp); 3185 if (bp->bio_error != 0) 3186 return (bp->bio_error); 3187 if (!(bp->bio_flags & BIO_ERROR)) 3188 return (0); 3189 return (EIO); 3190 } 3191 3192 void 3193 biofinish(struct bio *bp, struct devstat *stat, int error) 3194 { 3195 3196 if (error) { 3197 bp->bio_error = error; 3198 bp->bio_flags |= BIO_ERROR; 3199 } 3200 if (stat != NULL) 3201 devstat_end_transaction_bio(stat, bp); 3202 biodone(bp); 3203 } 3204 3205 /* 3206 * bufwait: 3207 * 3208 * Wait for buffer I/O completion, returning error status. The buffer 3209 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3210 * error and cleared. 3211 */ 3212 int 3213 bufwait(struct buf *bp) 3214 { 3215 if (bp->b_iocmd == BIO_READ) 3216 bwait(bp, PRIBIO, "biord"); 3217 else 3218 bwait(bp, PRIBIO, "biowr"); 3219 if (bp->b_flags & B_EINTR) { 3220 bp->b_flags &= ~B_EINTR; 3221 return (EINTR); 3222 } 3223 if (bp->b_ioflags & BIO_ERROR) { 3224 return (bp->b_error ? bp->b_error : EIO); 3225 } else { 3226 return (0); 3227 } 3228 } 3229 3230 /* 3231 * Call back function from struct bio back up to struct buf. 3232 */ 3233 static void 3234 bufdonebio(struct bio *bip) 3235 { 3236 struct buf *bp; 3237 3238 bp = bip->bio_caller2; 3239 bp->b_resid = bp->b_bcount - bip->bio_completed; 3240 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3241 bp->b_ioflags = bip->bio_flags; 3242 bp->b_error = bip->bio_error; 3243 if (bp->b_error) 3244 bp->b_ioflags |= BIO_ERROR; 3245 bufdone(bp); 3246 g_destroy_bio(bip); 3247 } 3248 3249 void 3250 dev_strategy(struct cdev *dev, struct buf *bp) 3251 { 3252 struct cdevsw *csw; 3253 struct bio *bip; 3254 int ref; 3255 3256 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3257 panic("b_iocmd botch"); 3258 for (;;) { 3259 bip = g_new_bio(); 3260 if (bip != NULL) 3261 break; 3262 /* Try again later */ 3263 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3264 } 3265 bip->bio_cmd = bp->b_iocmd; 3266 bip->bio_offset = bp->b_iooffset; 3267 bip->bio_length = bp->b_bcount; 3268 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3269 bip->bio_data = bp->b_data; 3270 bip->bio_done = bufdonebio; 3271 bip->bio_caller2 = bp; 3272 bip->bio_dev = dev; 3273 KASSERT(dev->si_refcount > 0, 3274 ("dev_strategy on un-referenced struct cdev *(%s)", 3275 devtoname(dev))); 3276 csw = dev_refthread(dev, &ref); 3277 if (csw == NULL) { 3278 g_destroy_bio(bip); 3279 bp->b_error = ENXIO; 3280 bp->b_ioflags = BIO_ERROR; 3281 bufdone(bp); 3282 return; 3283 } 3284 (*csw->d_strategy)(bip); 3285 dev_relthread(dev, ref); 3286 } 3287 3288 /* 3289 * bufdone: 3290 * 3291 * Finish I/O on a buffer, optionally calling a completion function. 3292 * This is usually called from an interrupt so process blocking is 3293 * not allowed. 3294 * 3295 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3296 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3297 * assuming B_INVAL is clear. 3298 * 3299 * For the VMIO case, we set B_CACHE if the op was a read and no 3300 * read error occured, or if the op was a write. B_CACHE is never 3301 * set if the buffer is invalid or otherwise uncacheable. 3302 * 3303 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3304 * initiator to leave B_INVAL set to brelse the buffer out of existance 3305 * in the biodone routine. 3306 */ 3307 void 3308 bufdone(struct buf *bp) 3309 { 3310 struct bufobj *dropobj; 3311 void (*biodone)(struct buf *); 3312 3313 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3314 dropobj = NULL; 3315 3316 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3317 BUF_ASSERT_HELD(bp); 3318 3319 runningbufwakeup(bp); 3320 if (bp->b_iocmd == BIO_WRITE) 3321 dropobj = bp->b_bufobj; 3322 /* call optional completion function if requested */ 3323 if (bp->b_iodone != NULL) { 3324 biodone = bp->b_iodone; 3325 bp->b_iodone = NULL; 3326 (*biodone) (bp); 3327 if (dropobj) 3328 bufobj_wdrop(dropobj); 3329 return; 3330 } 3331 3332 bufdone_finish(bp); 3333 3334 if (dropobj) 3335 bufobj_wdrop(dropobj); 3336 } 3337 3338 void 3339 bufdone_finish(struct buf *bp) 3340 { 3341 BUF_ASSERT_HELD(bp); 3342 3343 if (!LIST_EMPTY(&bp->b_dep)) 3344 buf_complete(bp); 3345 3346 if (bp->b_flags & B_VMIO) { 3347 int i; 3348 vm_ooffset_t foff; 3349 vm_page_t m; 3350 vm_object_t obj; 3351 int bogus, iosize; 3352 struct vnode *vp = bp->b_vp; 3353 3354 obj = bp->b_bufobj->bo_object; 3355 3356 #if defined(VFS_BIO_DEBUG) 3357 mp_fixme("usecount and vflag accessed without locks."); 3358 if (vp->v_usecount == 0) { 3359 panic("biodone: zero vnode ref count"); 3360 } 3361 3362 KASSERT(vp->v_object != NULL, 3363 ("biodone: vnode %p has no vm_object", vp)); 3364 #endif 3365 3366 foff = bp->b_offset; 3367 KASSERT(bp->b_offset != NOOFFSET, 3368 ("biodone: no buffer offset")); 3369 3370 VM_OBJECT_LOCK(obj); 3371 #if defined(VFS_BIO_DEBUG) 3372 if (obj->paging_in_progress < bp->b_npages) { 3373 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3374 obj->paging_in_progress, bp->b_npages); 3375 } 3376 #endif 3377 3378 /* 3379 * Set B_CACHE if the op was a normal read and no error 3380 * occured. B_CACHE is set for writes in the b*write() 3381 * routines. 3382 */ 3383 iosize = bp->b_bcount - bp->b_resid; 3384 if (bp->b_iocmd == BIO_READ && 3385 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3386 !(bp->b_ioflags & BIO_ERROR)) { 3387 bp->b_flags |= B_CACHE; 3388 } 3389 bogus = 0; 3390 for (i = 0; i < bp->b_npages; i++) { 3391 int bogusflag = 0; 3392 int resid; 3393 3394 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3395 if (resid > iosize) 3396 resid = iosize; 3397 3398 /* 3399 * cleanup bogus pages, restoring the originals 3400 */ 3401 m = bp->b_pages[i]; 3402 if (m == bogus_page) { 3403 bogus = bogusflag = 1; 3404 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3405 if (m == NULL) 3406 panic("biodone: page disappeared!"); 3407 bp->b_pages[i] = m; 3408 } 3409 #if defined(VFS_BIO_DEBUG) 3410 if (OFF_TO_IDX(foff) != m->pindex) { 3411 printf( 3412 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3413 (intmax_t)foff, (uintmax_t)m->pindex); 3414 } 3415 #endif 3416 3417 /* 3418 * In the write case, the valid and clean bits are 3419 * already changed correctly ( see bdwrite() ), so we 3420 * only need to do this here in the read case. 3421 */ 3422 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3423 KASSERT((m->dirty & vm_page_bits(foff & 3424 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3425 " page %p has unexpected dirty bits", m)); 3426 vfs_page_set_valid(bp, foff, m); 3427 } 3428 3429 /* 3430 * when debugging new filesystems or buffer I/O methods, this 3431 * is the most common error that pops up. if you see this, you 3432 * have not set the page busy flag correctly!!! 3433 */ 3434 if (m->busy == 0) { 3435 printf("biodone: page busy < 0, " 3436 "pindex: %d, foff: 0x(%x,%x), " 3437 "resid: %d, index: %d\n", 3438 (int) m->pindex, (int)(foff >> 32), 3439 (int) foff & 0xffffffff, resid, i); 3440 if (!vn_isdisk(vp, NULL)) 3441 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3442 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3443 (intmax_t) bp->b_lblkno, 3444 bp->b_flags, bp->b_npages); 3445 else 3446 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3447 (intmax_t) bp->b_lblkno, 3448 bp->b_flags, bp->b_npages); 3449 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3450 (u_long)m->valid, (u_long)m->dirty, 3451 m->wire_count); 3452 panic("biodone: page busy < 0\n"); 3453 } 3454 vm_page_io_finish(m); 3455 vm_object_pip_subtract(obj, 1); 3456 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3457 iosize -= resid; 3458 } 3459 vm_object_pip_wakeupn(obj, 0); 3460 VM_OBJECT_UNLOCK(obj); 3461 if (bogus) 3462 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3463 bp->b_pages, bp->b_npages); 3464 } 3465 3466 /* 3467 * For asynchronous completions, release the buffer now. The brelse 3468 * will do a wakeup there if necessary - so no need to do a wakeup 3469 * here in the async case. The sync case always needs to do a wakeup. 3470 */ 3471 3472 if (bp->b_flags & B_ASYNC) { 3473 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3474 brelse(bp); 3475 else 3476 bqrelse(bp); 3477 } else 3478 bdone(bp); 3479 } 3480 3481 /* 3482 * This routine is called in lieu of iodone in the case of 3483 * incomplete I/O. This keeps the busy status for pages 3484 * consistant. 3485 */ 3486 void 3487 vfs_unbusy_pages(struct buf *bp) 3488 { 3489 int i; 3490 vm_object_t obj; 3491 vm_page_t m; 3492 3493 runningbufwakeup(bp); 3494 if (!(bp->b_flags & B_VMIO)) 3495 return; 3496 3497 obj = bp->b_bufobj->bo_object; 3498 VM_OBJECT_LOCK(obj); 3499 for (i = 0; i < bp->b_npages; i++) { 3500 m = bp->b_pages[i]; 3501 if (m == bogus_page) { 3502 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3503 if (!m) 3504 panic("vfs_unbusy_pages: page missing\n"); 3505 bp->b_pages[i] = m; 3506 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3507 bp->b_pages, bp->b_npages); 3508 } 3509 vm_object_pip_subtract(obj, 1); 3510 vm_page_io_finish(m); 3511 } 3512 vm_object_pip_wakeupn(obj, 0); 3513 VM_OBJECT_UNLOCK(obj); 3514 } 3515 3516 /* 3517 * vfs_page_set_valid: 3518 * 3519 * Set the valid bits in a page based on the supplied offset. The 3520 * range is restricted to the buffer's size. 3521 * 3522 * This routine is typically called after a read completes. 3523 */ 3524 static void 3525 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3526 { 3527 vm_ooffset_t eoff; 3528 3529 /* 3530 * Compute the end offset, eoff, such that [off, eoff) does not span a 3531 * page boundary and eoff is not greater than the end of the buffer. 3532 * The end of the buffer, in this case, is our file EOF, not the 3533 * allocation size of the buffer. 3534 */ 3535 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3536 if (eoff > bp->b_offset + bp->b_bcount) 3537 eoff = bp->b_offset + bp->b_bcount; 3538 3539 /* 3540 * Set valid range. This is typically the entire buffer and thus the 3541 * entire page. 3542 */ 3543 if (eoff > off) 3544 vm_page_set_valid(m, off & PAGE_MASK, eoff - off); 3545 } 3546 3547 /* 3548 * vfs_page_set_validclean: 3549 * 3550 * Set the valid bits and clear the dirty bits in a page based on the 3551 * supplied offset. The range is restricted to the buffer's size. 3552 */ 3553 static void 3554 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3555 { 3556 vm_ooffset_t soff, eoff; 3557 3558 /* 3559 * Start and end offsets in buffer. eoff - soff may not cross a 3560 * page boundry or cross the end of the buffer. The end of the 3561 * buffer, in this case, is our file EOF, not the allocation size 3562 * of the buffer. 3563 */ 3564 soff = off; 3565 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3566 if (eoff > bp->b_offset + bp->b_bcount) 3567 eoff = bp->b_offset + bp->b_bcount; 3568 3569 /* 3570 * Set valid range. This is typically the entire buffer and thus the 3571 * entire page. 3572 */ 3573 if (eoff > soff) { 3574 vm_page_set_validclean( 3575 m, 3576 (vm_offset_t) (soff & PAGE_MASK), 3577 (vm_offset_t) (eoff - soff) 3578 ); 3579 } 3580 } 3581 3582 /* 3583 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3584 * any page is busy, drain the flag. 3585 */ 3586 static void 3587 vfs_drain_busy_pages(struct buf *bp) 3588 { 3589 vm_page_t m; 3590 int i, last_busied; 3591 3592 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED); 3593 last_busied = 0; 3594 for (i = 0; i < bp->b_npages; i++) { 3595 m = bp->b_pages[i]; 3596 if ((m->oflags & VPO_BUSY) != 0) { 3597 for (; last_busied < i; last_busied++) 3598 vm_page_busy(bp->b_pages[last_busied]); 3599 while ((m->oflags & VPO_BUSY) != 0) 3600 vm_page_sleep(m, "vbpage"); 3601 } 3602 } 3603 for (i = 0; i < last_busied; i++) 3604 vm_page_wakeup(bp->b_pages[i]); 3605 } 3606 3607 /* 3608 * This routine is called before a device strategy routine. 3609 * It is used to tell the VM system that paging I/O is in 3610 * progress, and treat the pages associated with the buffer 3611 * almost as being VPO_BUSY. Also the object paging_in_progress 3612 * flag is handled to make sure that the object doesn't become 3613 * inconsistant. 3614 * 3615 * Since I/O has not been initiated yet, certain buffer flags 3616 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3617 * and should be ignored. 3618 */ 3619 void 3620 vfs_busy_pages(struct buf *bp, int clear_modify) 3621 { 3622 int i, bogus; 3623 vm_object_t obj; 3624 vm_ooffset_t foff; 3625 vm_page_t m; 3626 3627 if (!(bp->b_flags & B_VMIO)) 3628 return; 3629 3630 obj = bp->b_bufobj->bo_object; 3631 foff = bp->b_offset; 3632 KASSERT(bp->b_offset != NOOFFSET, 3633 ("vfs_busy_pages: no buffer offset")); 3634 VM_OBJECT_LOCK(obj); 3635 vfs_drain_busy_pages(bp); 3636 if (bp->b_bufsize != 0) 3637 vfs_setdirty_locked_object(bp); 3638 bogus = 0; 3639 for (i = 0; i < bp->b_npages; i++) { 3640 m = bp->b_pages[i]; 3641 3642 if ((bp->b_flags & B_CLUSTER) == 0) { 3643 vm_object_pip_add(obj, 1); 3644 vm_page_io_start(m); 3645 } 3646 /* 3647 * When readying a buffer for a read ( i.e 3648 * clear_modify == 0 ), it is important to do 3649 * bogus_page replacement for valid pages in 3650 * partially instantiated buffers. Partially 3651 * instantiated buffers can, in turn, occur when 3652 * reconstituting a buffer from its VM backing store 3653 * base. We only have to do this if B_CACHE is 3654 * clear ( which causes the I/O to occur in the 3655 * first place ). The replacement prevents the read 3656 * I/O from overwriting potentially dirty VM-backed 3657 * pages. XXX bogus page replacement is, uh, bogus. 3658 * It may not work properly with small-block devices. 3659 * We need to find a better way. 3660 */ 3661 if (clear_modify) { 3662 pmap_remove_write(m); 3663 vfs_page_set_validclean(bp, foff, m); 3664 } else if (m->valid == VM_PAGE_BITS_ALL && 3665 (bp->b_flags & B_CACHE) == 0) { 3666 bp->b_pages[i] = bogus_page; 3667 bogus++; 3668 } 3669 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3670 } 3671 VM_OBJECT_UNLOCK(obj); 3672 if (bogus) 3673 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3674 bp->b_pages, bp->b_npages); 3675 } 3676 3677 /* 3678 * vfs_bio_set_valid: 3679 * 3680 * Set the range within the buffer to valid. The range is 3681 * relative to the beginning of the buffer, b_offset. Note that 3682 * b_offset itself may be offset from the beginning of the first 3683 * page. 3684 */ 3685 void 3686 vfs_bio_set_valid(struct buf *bp, int base, int size) 3687 { 3688 int i, n; 3689 vm_page_t m; 3690 3691 if (!(bp->b_flags & B_VMIO)) 3692 return; 3693 3694 /* 3695 * Fixup base to be relative to beginning of first page. 3696 * Set initial n to be the maximum number of bytes in the 3697 * first page that can be validated. 3698 */ 3699 base += (bp->b_offset & PAGE_MASK); 3700 n = PAGE_SIZE - (base & PAGE_MASK); 3701 3702 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3703 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3704 m = bp->b_pages[i]; 3705 if (n > size) 3706 n = size; 3707 vm_page_set_valid(m, base & PAGE_MASK, n); 3708 base += n; 3709 size -= n; 3710 n = PAGE_SIZE; 3711 } 3712 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3713 } 3714 3715 /* 3716 * vfs_bio_clrbuf: 3717 * 3718 * If the specified buffer is a non-VMIO buffer, clear the entire 3719 * buffer. If the specified buffer is a VMIO buffer, clear and 3720 * validate only the previously invalid portions of the buffer. 3721 * This routine essentially fakes an I/O, so we need to clear 3722 * BIO_ERROR and B_INVAL. 3723 * 3724 * Note that while we only theoretically need to clear through b_bcount, 3725 * we go ahead and clear through b_bufsize. 3726 */ 3727 void 3728 vfs_bio_clrbuf(struct buf *bp) 3729 { 3730 int i, j, mask; 3731 caddr_t sa, ea; 3732 3733 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3734 clrbuf(bp); 3735 return; 3736 } 3737 bp->b_flags &= ~B_INVAL; 3738 bp->b_ioflags &= ~BIO_ERROR; 3739 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3740 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3741 (bp->b_offset & PAGE_MASK) == 0) { 3742 if (bp->b_pages[0] == bogus_page) 3743 goto unlock; 3744 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3745 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3746 if ((bp->b_pages[0]->valid & mask) == mask) 3747 goto unlock; 3748 if ((bp->b_pages[0]->valid & mask) == 0) { 3749 bzero(bp->b_data, bp->b_bufsize); 3750 bp->b_pages[0]->valid |= mask; 3751 goto unlock; 3752 } 3753 } 3754 ea = sa = bp->b_data; 3755 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3756 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3757 ea = (caddr_t)(vm_offset_t)ulmin( 3758 (u_long)(vm_offset_t)ea, 3759 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3760 if (bp->b_pages[i] == bogus_page) 3761 continue; 3762 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3763 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3764 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3765 if ((bp->b_pages[i]->valid & mask) == mask) 3766 continue; 3767 if ((bp->b_pages[i]->valid & mask) == 0) 3768 bzero(sa, ea - sa); 3769 else { 3770 for (; sa < ea; sa += DEV_BSIZE, j++) { 3771 if ((bp->b_pages[i]->valid & (1 << j)) == 0) 3772 bzero(sa, DEV_BSIZE); 3773 } 3774 } 3775 bp->b_pages[i]->valid |= mask; 3776 } 3777 unlock: 3778 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3779 bp->b_resid = 0; 3780 } 3781 3782 /* 3783 * vm_hold_load_pages and vm_hold_free_pages get pages into 3784 * a buffers address space. The pages are anonymous and are 3785 * not associated with a file object. 3786 */ 3787 static void 3788 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3789 { 3790 vm_offset_t pg; 3791 vm_page_t p; 3792 int index; 3793 3794 to = round_page(to); 3795 from = round_page(from); 3796 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3797 3798 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3799 tryagain: 3800 /* 3801 * note: must allocate system pages since blocking here 3802 * could interfere with paging I/O, no matter which 3803 * process we are. 3804 */ 3805 p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ | 3806 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3807 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 3808 if (!p) { 3809 VM_WAIT; 3810 goto tryagain; 3811 } 3812 pmap_qenter(pg, &p, 1); 3813 bp->b_pages[index] = p; 3814 } 3815 bp->b_npages = index; 3816 } 3817 3818 /* Return pages associated with this buf to the vm system */ 3819 static void 3820 vm_hold_free_pages(struct buf *bp, int newbsize) 3821 { 3822 vm_offset_t from; 3823 vm_page_t p; 3824 int index, newnpages; 3825 3826 from = round_page((vm_offset_t)bp->b_data + newbsize); 3827 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3828 if (bp->b_npages > newnpages) 3829 pmap_qremove(from, bp->b_npages - newnpages); 3830 for (index = newnpages; index < bp->b_npages; index++) { 3831 p = bp->b_pages[index]; 3832 bp->b_pages[index] = NULL; 3833 if (p->busy != 0) 3834 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3835 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 3836 p->wire_count--; 3837 vm_page_free(p); 3838 atomic_subtract_int(&cnt.v_wire_count, 1); 3839 } 3840 bp->b_npages = newnpages; 3841 } 3842 3843 /* 3844 * Map an IO request into kernel virtual address space. 3845 * 3846 * All requests are (re)mapped into kernel VA space. 3847 * Notice that we use b_bufsize for the size of the buffer 3848 * to be mapped. b_bcount might be modified by the driver. 3849 * 3850 * Note that even if the caller determines that the address space should 3851 * be valid, a race or a smaller-file mapped into a larger space may 3852 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3853 * check the return value. 3854 */ 3855 int 3856 vmapbuf(struct buf *bp) 3857 { 3858 caddr_t addr, kva; 3859 vm_prot_t prot; 3860 int pidx, i; 3861 struct vm_page *m; 3862 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3863 3864 if (bp->b_bufsize < 0) 3865 return (-1); 3866 prot = VM_PROT_READ; 3867 if (bp->b_iocmd == BIO_READ) 3868 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3869 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3870 addr < bp->b_data + bp->b_bufsize; 3871 addr += PAGE_SIZE, pidx++) { 3872 /* 3873 * Do the vm_fault if needed; do the copy-on-write thing 3874 * when reading stuff off device into memory. 3875 * 3876 * NOTE! Must use pmap_extract() because addr may be in 3877 * the userland address space, and kextract is only guarenteed 3878 * to work for the kernland address space (see: sparc64 port). 3879 */ 3880 retry: 3881 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3882 prot) < 0) { 3883 for (i = 0; i < pidx; ++i) { 3884 vm_page_lock(bp->b_pages[i]); 3885 vm_page_unhold(bp->b_pages[i]); 3886 vm_page_unlock(bp->b_pages[i]); 3887 bp->b_pages[i] = NULL; 3888 } 3889 return(-1); 3890 } 3891 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3892 if (m == NULL) 3893 goto retry; 3894 bp->b_pages[pidx] = m; 3895 } 3896 if (pidx > btoc(MAXPHYS)) 3897 panic("vmapbuf: mapped more than MAXPHYS"); 3898 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3899 3900 kva = bp->b_saveaddr; 3901 bp->b_npages = pidx; 3902 bp->b_saveaddr = bp->b_data; 3903 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3904 return(0); 3905 } 3906 3907 /* 3908 * Free the io map PTEs associated with this IO operation. 3909 * We also invalidate the TLB entries and restore the original b_addr. 3910 */ 3911 void 3912 vunmapbuf(struct buf *bp) 3913 { 3914 int pidx; 3915 int npages; 3916 3917 npages = bp->b_npages; 3918 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3919 for (pidx = 0; pidx < npages; pidx++) { 3920 vm_page_lock(bp->b_pages[pidx]); 3921 vm_page_unhold(bp->b_pages[pidx]); 3922 vm_page_unlock(bp->b_pages[pidx]); 3923 } 3924 3925 bp->b_data = bp->b_saveaddr; 3926 } 3927 3928 void 3929 bdone(struct buf *bp) 3930 { 3931 struct mtx *mtxp; 3932 3933 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3934 mtx_lock(mtxp); 3935 bp->b_flags |= B_DONE; 3936 wakeup(bp); 3937 mtx_unlock(mtxp); 3938 } 3939 3940 void 3941 bwait(struct buf *bp, u_char pri, const char *wchan) 3942 { 3943 struct mtx *mtxp; 3944 3945 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3946 mtx_lock(mtxp); 3947 while ((bp->b_flags & B_DONE) == 0) 3948 msleep(bp, mtxp, pri, wchan, 0); 3949 mtx_unlock(mtxp); 3950 } 3951 3952 int 3953 bufsync(struct bufobj *bo, int waitfor) 3954 { 3955 3956 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3957 } 3958 3959 void 3960 bufstrategy(struct bufobj *bo, struct buf *bp) 3961 { 3962 int i = 0; 3963 struct vnode *vp; 3964 3965 vp = bp->b_vp; 3966 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3967 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3968 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3969 i = VOP_STRATEGY(vp, bp); 3970 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3971 } 3972 3973 void 3974 bufobj_wrefl(struct bufobj *bo) 3975 { 3976 3977 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3978 ASSERT_BO_LOCKED(bo); 3979 bo->bo_numoutput++; 3980 } 3981 3982 void 3983 bufobj_wref(struct bufobj *bo) 3984 { 3985 3986 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3987 BO_LOCK(bo); 3988 bo->bo_numoutput++; 3989 BO_UNLOCK(bo); 3990 } 3991 3992 void 3993 bufobj_wdrop(struct bufobj *bo) 3994 { 3995 3996 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3997 BO_LOCK(bo); 3998 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3999 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 4000 bo->bo_flag &= ~BO_WWAIT; 4001 wakeup(&bo->bo_numoutput); 4002 } 4003 BO_UNLOCK(bo); 4004 } 4005 4006 int 4007 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 4008 { 4009 int error; 4010 4011 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 4012 ASSERT_BO_LOCKED(bo); 4013 error = 0; 4014 while (bo->bo_numoutput) { 4015 bo->bo_flag |= BO_WWAIT; 4016 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 4017 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 4018 if (error) 4019 break; 4020 } 4021 return (error); 4022 } 4023 4024 void 4025 bpin(struct buf *bp) 4026 { 4027 struct mtx *mtxp; 4028 4029 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4030 mtx_lock(mtxp); 4031 bp->b_pin_count++; 4032 mtx_unlock(mtxp); 4033 } 4034 4035 void 4036 bunpin(struct buf *bp) 4037 { 4038 struct mtx *mtxp; 4039 4040 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4041 mtx_lock(mtxp); 4042 if (--bp->b_pin_count == 0) 4043 wakeup(bp); 4044 mtx_unlock(mtxp); 4045 } 4046 4047 void 4048 bunpin_wait(struct buf *bp) 4049 { 4050 struct mtx *mtxp; 4051 4052 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4053 mtx_lock(mtxp); 4054 while (bp->b_pin_count > 0) 4055 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4056 mtx_unlock(mtxp); 4057 } 4058 4059 #include "opt_ddb.h" 4060 #ifdef DDB 4061 #include <ddb/ddb.h> 4062 4063 /* DDB command to show buffer data */ 4064 DB_SHOW_COMMAND(buffer, db_show_buffer) 4065 { 4066 /* get args */ 4067 struct buf *bp = (struct buf *)addr; 4068 4069 if (!have_addr) { 4070 db_printf("usage: show buffer <addr>\n"); 4071 return; 4072 } 4073 4074 db_printf("buf at %p\n", bp); 4075 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4076 db_printf( 4077 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4078 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n", 4079 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4080 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4081 bp->b_dep.lh_first); 4082 if (bp->b_npages) { 4083 int i; 4084 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4085 for (i = 0; i < bp->b_npages; i++) { 4086 vm_page_t m; 4087 m = bp->b_pages[i]; 4088 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4089 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4090 if ((i + 1) < bp->b_npages) 4091 db_printf(","); 4092 } 4093 db_printf("\n"); 4094 } 4095 db_printf(" "); 4096 lockmgr_printinfo(&bp->b_lock); 4097 } 4098 4099 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4100 { 4101 struct buf *bp; 4102 int i; 4103 4104 for (i = 0; i < nbuf; i++) { 4105 bp = &buf[i]; 4106 if (BUF_ISLOCKED(bp)) { 4107 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4108 db_printf("\n"); 4109 } 4110 } 4111 } 4112 4113 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4114 { 4115 struct vnode *vp; 4116 struct buf *bp; 4117 4118 if (!have_addr) { 4119 db_printf("usage: show vnodebufs <addr>\n"); 4120 return; 4121 } 4122 vp = (struct vnode *)addr; 4123 db_printf("Clean buffers:\n"); 4124 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4125 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4126 db_printf("\n"); 4127 } 4128 db_printf("Dirty buffers:\n"); 4129 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4130 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4131 db_printf("\n"); 4132 } 4133 } 4134 4135 DB_COMMAND(countfreebufs, db_coundfreebufs) 4136 { 4137 struct buf *bp; 4138 int i, used = 0, nfree = 0; 4139 4140 if (have_addr) { 4141 db_printf("usage: countfreebufs\n"); 4142 return; 4143 } 4144 4145 for (i = 0; i < nbuf; i++) { 4146 bp = &buf[i]; 4147 if ((bp->b_vflags & BV_INFREECNT) != 0) 4148 nfree++; 4149 else 4150 used++; 4151 } 4152 4153 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4154 nfree + used); 4155 db_printf("numfreebuffers is %d\n", numfreebuffers); 4156 } 4157 #endif /* DDB */ 4158