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