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