1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * this file contains a new buffer I/O scheme implementing a coherent 30 * VM object and buffer cache scheme. Pains have been taken to make 31 * sure that the performance degradation associated with schemes such 32 * as this is not realized. 33 * 34 * Author: John S. Dyson 35 * Significant help during the development and debugging phases 36 * had been provided by David Greenman, also of the FreeBSD core team. 37 * 38 * see man buf(9) for more info. 39 */ 40 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/bio.h> 47 #include <sys/conf.h> 48 #include <sys/buf.h> 49 #include <sys/devicestat.h> 50 #include <sys/eventhandler.h> 51 #include <sys/fail.h> 52 #include <sys/limits.h> 53 #include <sys/lock.h> 54 #include <sys/malloc.h> 55 #include <sys/mount.h> 56 #include <sys/mutex.h> 57 #include <sys/kernel.h> 58 #include <sys/kthread.h> 59 #include <sys/proc.h> 60 #include <sys/resourcevar.h> 61 #include <sys/sysctl.h> 62 #include <sys/vmmeter.h> 63 #include <sys/vnode.h> 64 #include <geom/geom.h> 65 #include <vm/vm.h> 66 #include <vm/vm_param.h> 67 #include <vm/vm_kern.h> 68 #include <vm/vm_pageout.h> 69 #include <vm/vm_page.h> 70 #include <vm/vm_object.h> 71 #include <vm/vm_extern.h> 72 #include <vm/vm_map.h> 73 #include "opt_compat.h" 74 #include "opt_directio.h" 75 #include "opt_swap.h" 76 77 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 78 79 struct bio_ops bioops; /* I/O operation notification */ 80 81 struct buf_ops buf_ops_bio = { 82 .bop_name = "buf_ops_bio", 83 .bop_write = bufwrite, 84 .bop_strategy = bufstrategy, 85 .bop_sync = bufsync, 86 .bop_bdflush = bufbdflush, 87 }; 88 89 /* 90 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 91 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 92 */ 93 struct buf *buf; /* buffer header pool */ 94 95 static struct proc *bufdaemonproc; 96 97 static int inmem(struct vnode *vp, daddr_t blkno); 98 static void vm_hold_free_pages(struct buf *bp, int newbsize); 99 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 100 vm_offset_t to); 101 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 102 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 103 vm_page_t m); 104 static void vfs_drain_busy_pages(struct buf *bp); 105 static void vfs_clean_pages_dirty_buf(struct buf *bp); 106 static void vfs_setdirty_locked_object(struct buf *bp); 107 static void vfs_vmio_release(struct buf *bp); 108 static int vfs_bio_clcheck(struct vnode *vp, int size, 109 daddr_t lblkno, daddr_t blkno); 110 static int buf_do_flush(struct vnode *vp); 111 static int flushbufqueues(struct vnode *, int, int); 112 static void buf_daemon(void); 113 static void bremfreel(struct buf *bp); 114 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 115 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 116 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 117 #endif 118 119 int vmiodirenable = TRUE; 120 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 121 "Use the VM system for directory writes"); 122 long runningbufspace; 123 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 124 "Amount of presently outstanding async buffer io"); 125 static long bufspace; 126 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 127 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 128 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 129 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 130 #else 131 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 132 "Virtual memory used for buffers"); 133 #endif 134 static long maxbufspace; 135 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 136 "Maximum allowed value of bufspace (including buf_daemon)"); 137 static long bufmallocspace; 138 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 139 "Amount of malloced memory for buffers"); 140 static long maxbufmallocspace; 141 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 142 "Maximum amount of malloced memory for buffers"); 143 static long lobufspace; 144 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 145 "Minimum amount of buffers we want to have"); 146 long hibufspace; 147 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 148 "Maximum allowed value of bufspace (excluding buf_daemon)"); 149 static int bufreusecnt; 150 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 151 "Number of times we have reused a buffer"); 152 static int buffreekvacnt; 153 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 154 "Number of times we have freed the KVA space from some buffer"); 155 static int bufdefragcnt; 156 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 157 "Number of times we have had to repeat buffer allocation to defragment"); 158 static long lorunningspace; 159 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 160 "Minimum preferred space used for in-progress I/O"); 161 static long hirunningspace; 162 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 163 "Maximum amount of space to use for in-progress I/O"); 164 int dirtybufferflushes; 165 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 166 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 167 int bdwriteskip; 168 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 169 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 170 int altbufferflushes; 171 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 172 0, "Number of fsync flushes to limit dirty buffers"); 173 static int recursiveflushes; 174 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 175 0, "Number of flushes skipped due to being recursive"); 176 static int numdirtybuffers; 177 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 178 "Number of buffers that are dirty (has unwritten changes) at the moment"); 179 static int lodirtybuffers; 180 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 181 "How many buffers we want to have free before bufdaemon can sleep"); 182 static int hidirtybuffers; 183 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 184 "When the number of dirty buffers is considered severe"); 185 int dirtybufthresh; 186 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 187 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 188 static int numfreebuffers; 189 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 190 "Number of free buffers"); 191 static int lofreebuffers; 192 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 193 "XXX Unused"); 194 static int hifreebuffers; 195 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 196 "XXX Complicatedly unused"); 197 static int getnewbufcalls; 198 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 199 "Number of calls to getnewbuf"); 200 static int getnewbufrestarts; 201 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 202 "Number of times getnewbuf has had to restart a buffer aquisition"); 203 static int flushbufqtarget = 100; 204 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 205 "Amount of work to do in flushbufqueues when helping bufdaemon"); 206 static long notbufdflashes; 207 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, 208 "Number of dirty buffer flushes done by the bufdaemon helpers"); 209 210 /* 211 * Wakeup point for bufdaemon, as well as indicator of whether it is already 212 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 213 * is idling. 214 */ 215 static int bd_request; 216 217 /* 218 * Request for the buf daemon to write more buffers than is indicated by 219 * lodirtybuf. This may be necessary to push out excess dependencies or 220 * defragment the address space where a simple count of the number of dirty 221 * buffers is insufficient to characterize the demand for flushing them. 222 */ 223 static int bd_speedupreq; 224 225 /* 226 * This lock synchronizes access to bd_request. 227 */ 228 static struct mtx bdlock; 229 230 /* 231 * bogus page -- for I/O to/from partially complete buffers 232 * this is a temporary solution to the problem, but it is not 233 * really that bad. it would be better to split the buffer 234 * for input in the case of buffers partially already in memory, 235 * but the code is intricate enough already. 236 */ 237 vm_page_t bogus_page; 238 239 /* 240 * Synchronization (sleep/wakeup) variable for active buffer space requests. 241 * Set when wait starts, cleared prior to wakeup(). 242 * Used in runningbufwakeup() and waitrunningbufspace(). 243 */ 244 static int runningbufreq; 245 246 /* 247 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 248 * waitrunningbufspace(). 249 */ 250 static struct mtx rbreqlock; 251 252 /* 253 * Synchronization (sleep/wakeup) variable for buffer requests. 254 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 255 * by and/or. 256 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 257 * getnewbuf(), and getblk(). 258 */ 259 static int needsbuffer; 260 261 /* 262 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 263 */ 264 static struct mtx nblock; 265 266 /* 267 * Definitions for the buffer free lists. 268 */ 269 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 270 271 #define QUEUE_NONE 0 /* on no queue */ 272 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 273 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 274 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 275 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 276 #define QUEUE_EMPTY 5 /* empty buffer headers */ 277 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 278 279 /* Queues for free buffers with various properties */ 280 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 281 282 /* Lock for the bufqueues */ 283 static struct mtx bqlock; 284 285 /* 286 * Single global constant for BUF_WMESG, to avoid getting multiple references. 287 * buf_wmesg is referred from macros. 288 */ 289 const char *buf_wmesg = BUF_WMESG; 290 291 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 292 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 293 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 294 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 295 296 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 297 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 298 static int 299 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 300 { 301 long lvalue; 302 int ivalue; 303 304 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 305 return (sysctl_handle_long(oidp, arg1, arg2, req)); 306 lvalue = *(long *)arg1; 307 if (lvalue > INT_MAX) 308 /* On overflow, still write out a long to trigger ENOMEM. */ 309 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 310 ivalue = lvalue; 311 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 312 } 313 #endif 314 315 #ifdef DIRECTIO 316 extern void ffs_rawread_setup(void); 317 #endif /* DIRECTIO */ 318 /* 319 * numdirtywakeup: 320 * 321 * If someone is blocked due to there being too many dirty buffers, 322 * and numdirtybuffers is now reasonable, wake them up. 323 */ 324 325 static __inline void 326 numdirtywakeup(int level) 327 { 328 329 if (numdirtybuffers <= level) { 330 mtx_lock(&nblock); 331 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 332 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 333 wakeup(&needsbuffer); 334 } 335 mtx_unlock(&nblock); 336 } 337 } 338 339 /* 340 * bufspacewakeup: 341 * 342 * Called when buffer space is potentially available for recovery. 343 * getnewbuf() will block on this flag when it is unable to free 344 * sufficient buffer space. Buffer space becomes recoverable when 345 * bp's get placed back in the queues. 346 */ 347 348 static __inline void 349 bufspacewakeup(void) 350 { 351 352 /* 353 * If someone is waiting for BUF space, wake them up. Even 354 * though we haven't freed the kva space yet, the waiting 355 * process will be able to now. 356 */ 357 mtx_lock(&nblock); 358 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 359 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 360 wakeup(&needsbuffer); 361 } 362 mtx_unlock(&nblock); 363 } 364 365 /* 366 * runningbufwakeup() - in-progress I/O accounting. 367 * 368 */ 369 void 370 runningbufwakeup(struct buf *bp) 371 { 372 373 if (bp->b_runningbufspace) { 374 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 375 bp->b_runningbufspace = 0; 376 mtx_lock(&rbreqlock); 377 if (runningbufreq && runningbufspace <= lorunningspace) { 378 runningbufreq = 0; 379 wakeup(&runningbufreq); 380 } 381 mtx_unlock(&rbreqlock); 382 } 383 } 384 385 /* 386 * bufcountwakeup: 387 * 388 * Called when a buffer has been added to one of the free queues to 389 * account for the buffer and to wakeup anyone waiting for free buffers. 390 * This typically occurs when large amounts of metadata are being handled 391 * by the buffer cache ( else buffer space runs out first, usually ). 392 */ 393 394 static __inline void 395 bufcountwakeup(struct buf *bp) 396 { 397 int old; 398 399 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 400 ("buf %p already counted as free", bp)); 401 bp->b_vflags |= BV_INFREECNT; 402 old = atomic_fetchadd_int(&numfreebuffers, 1); 403 KASSERT(old >= 0 && old < nbuf, 404 ("numfreebuffers climbed to %d", old + 1)); 405 mtx_lock(&nblock); 406 if (needsbuffer) { 407 needsbuffer &= ~VFS_BIO_NEED_ANY; 408 if (numfreebuffers >= hifreebuffers) 409 needsbuffer &= ~VFS_BIO_NEED_FREE; 410 wakeup(&needsbuffer); 411 } 412 mtx_unlock(&nblock); 413 } 414 415 /* 416 * waitrunningbufspace() 417 * 418 * runningbufspace is a measure of the amount of I/O currently 419 * running. This routine is used in async-write situations to 420 * prevent creating huge backups of pending writes to a device. 421 * Only asynchronous writes are governed by this function. 422 * 423 * Reads will adjust runningbufspace, but will not block based on it. 424 * The read load has a side effect of reducing the allowed write load. 425 * 426 * This does NOT turn an async write into a sync write. It waits 427 * for earlier writes to complete and generally returns before the 428 * caller's write has reached the device. 429 */ 430 void 431 waitrunningbufspace(void) 432 { 433 434 mtx_lock(&rbreqlock); 435 while (runningbufspace > hirunningspace) { 436 ++runningbufreq; 437 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 438 } 439 mtx_unlock(&rbreqlock); 440 } 441 442 443 /* 444 * vfs_buf_test_cache: 445 * 446 * Called when a buffer is extended. This function clears the B_CACHE 447 * bit if the newly extended portion of the buffer does not contain 448 * valid data. 449 */ 450 static __inline 451 void 452 vfs_buf_test_cache(struct buf *bp, 453 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 454 vm_page_t m) 455 { 456 457 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 458 if (bp->b_flags & B_CACHE) { 459 int base = (foff + off) & PAGE_MASK; 460 if (vm_page_is_valid(m, base, size) == 0) 461 bp->b_flags &= ~B_CACHE; 462 } 463 } 464 465 /* Wake up the buffer daemon if necessary */ 466 static __inline 467 void 468 bd_wakeup(int dirtybuflevel) 469 { 470 471 mtx_lock(&bdlock); 472 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 473 bd_request = 1; 474 wakeup(&bd_request); 475 } 476 mtx_unlock(&bdlock); 477 } 478 479 /* 480 * bd_speedup - speedup the buffer cache flushing code 481 */ 482 483 void 484 bd_speedup(void) 485 { 486 int needwake; 487 488 mtx_lock(&bdlock); 489 needwake = 0; 490 if (bd_speedupreq == 0 || bd_request == 0) 491 needwake = 1; 492 bd_speedupreq = 1; 493 bd_request = 1; 494 if (needwake) 495 wakeup(&bd_request); 496 mtx_unlock(&bdlock); 497 } 498 499 /* 500 * Calculating buffer cache scaling values and reserve space for buffer 501 * headers. This is called during low level kernel initialization and 502 * may be called more then once. We CANNOT write to the memory area 503 * being reserved at this time. 504 */ 505 caddr_t 506 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 507 { 508 int tuned_nbuf; 509 long maxbuf; 510 511 /* 512 * physmem_est is in pages. Convert it to kilobytes (assumes 513 * PAGE_SIZE is >= 1K) 514 */ 515 physmem_est = physmem_est * (PAGE_SIZE / 1024); 516 517 /* 518 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 519 * For the first 64MB of ram nominally allocate sufficient buffers to 520 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 521 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 522 * the buffer cache we limit the eventual kva reservation to 523 * maxbcache bytes. 524 * 525 * factor represents the 1/4 x ram conversion. 526 */ 527 if (nbuf == 0) { 528 int factor = 4 * BKVASIZE / 1024; 529 530 nbuf = 50; 531 if (physmem_est > 4096) 532 nbuf += min((physmem_est - 4096) / factor, 533 65536 / factor); 534 if (physmem_est > 65536) 535 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 536 537 if (maxbcache && nbuf > maxbcache / BKVASIZE) 538 nbuf = maxbcache / BKVASIZE; 539 tuned_nbuf = 1; 540 } else 541 tuned_nbuf = 0; 542 543 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 544 maxbuf = (LONG_MAX / 3) / BKVASIZE; 545 if (nbuf > maxbuf) { 546 if (!tuned_nbuf) 547 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 548 maxbuf); 549 nbuf = maxbuf; 550 } 551 552 /* 553 * swbufs are used as temporary holders for I/O, such as paging I/O. 554 * We have no less then 16 and no more then 256. 555 */ 556 nswbuf = max(min(nbuf/4, 256), 16); 557 #ifdef NSWBUF_MIN 558 if (nswbuf < NSWBUF_MIN) 559 nswbuf = NSWBUF_MIN; 560 #endif 561 #ifdef DIRECTIO 562 ffs_rawread_setup(); 563 #endif 564 565 /* 566 * Reserve space for the buffer cache buffers 567 */ 568 swbuf = (void *)v; 569 v = (caddr_t)(swbuf + nswbuf); 570 buf = (void *)v; 571 v = (caddr_t)(buf + nbuf); 572 573 return(v); 574 } 575 576 /* Initialize the buffer subsystem. Called before use of any buffers. */ 577 void 578 bufinit(void) 579 { 580 struct buf *bp; 581 int i; 582 583 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 584 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 585 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 586 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 587 588 /* next, make a null set of free lists */ 589 for (i = 0; i < BUFFER_QUEUES; i++) 590 TAILQ_INIT(&bufqueues[i]); 591 592 /* finally, initialize each buffer header and stick on empty q */ 593 for (i = 0; i < nbuf; i++) { 594 bp = &buf[i]; 595 bzero(bp, sizeof *bp); 596 bp->b_flags = B_INVAL; /* we're just an empty header */ 597 bp->b_rcred = NOCRED; 598 bp->b_wcred = NOCRED; 599 bp->b_qindex = QUEUE_EMPTY; 600 bp->b_vflags = BV_INFREECNT; /* buf is counted as free */ 601 bp->b_xflags = 0; 602 LIST_INIT(&bp->b_dep); 603 BUF_LOCKINIT(bp); 604 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 605 } 606 607 /* 608 * maxbufspace is the absolute maximum amount of buffer space we are 609 * allowed to reserve in KVM and in real terms. The absolute maximum 610 * is nominally used by buf_daemon. hibufspace is the nominal maximum 611 * used by most other processes. The differential is required to 612 * ensure that buf_daemon is able to run when other processes might 613 * be blocked waiting for buffer space. 614 * 615 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 616 * this may result in KVM fragmentation which is not handled optimally 617 * by the system. 618 */ 619 maxbufspace = (long)nbuf * BKVASIZE; 620 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 621 lobufspace = hibufspace - MAXBSIZE; 622 623 lorunningspace = 512 * 1024; 624 hirunningspace = 1024 * 1024; 625 626 /* 627 * Limit the amount of malloc memory since it is wired permanently into 628 * the kernel space. Even though this is accounted for in the buffer 629 * allocation, we don't want the malloced region to grow uncontrolled. 630 * The malloc scheme improves memory utilization significantly on average 631 * (small) directories. 632 */ 633 maxbufmallocspace = hibufspace / 20; 634 635 /* 636 * Reduce the chance of a deadlock occuring by limiting the number 637 * of delayed-write dirty buffers we allow to stack up. 638 */ 639 hidirtybuffers = nbuf / 4 + 20; 640 dirtybufthresh = hidirtybuffers * 9 / 10; 641 numdirtybuffers = 0; 642 /* 643 * To support extreme low-memory systems, make sure hidirtybuffers cannot 644 * eat up all available buffer space. This occurs when our minimum cannot 645 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 646 * BKVASIZE'd (8K) buffers. 647 */ 648 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 649 hidirtybuffers >>= 1; 650 } 651 lodirtybuffers = hidirtybuffers / 2; 652 653 /* 654 * Try to keep the number of free buffers in the specified range, 655 * and give special processes (e.g. like buf_daemon) access to an 656 * emergency reserve. 657 */ 658 lofreebuffers = nbuf / 18 + 5; 659 hifreebuffers = 2 * lofreebuffers; 660 numfreebuffers = nbuf; 661 662 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 663 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 664 } 665 666 /* 667 * bfreekva() - free the kva allocation for a buffer. 668 * 669 * Since this call frees up buffer space, we call bufspacewakeup(). 670 */ 671 static void 672 bfreekva(struct buf *bp) 673 { 674 675 if (bp->b_kvasize) { 676 atomic_add_int(&buffreekvacnt, 1); 677 atomic_subtract_long(&bufspace, bp->b_kvasize); 678 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 679 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 680 bp->b_kvasize = 0; 681 bufspacewakeup(); 682 } 683 } 684 685 /* 686 * bremfree: 687 * 688 * Mark the buffer for removal from the appropriate free list in brelse. 689 * 690 */ 691 void 692 bremfree(struct buf *bp) 693 { 694 int old; 695 696 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 697 KASSERT((bp->b_flags & B_REMFREE) == 0, 698 ("bremfree: buffer %p already marked for delayed removal.", bp)); 699 KASSERT(bp->b_qindex != QUEUE_NONE, 700 ("bremfree: buffer %p not on a queue.", bp)); 701 BUF_ASSERT_HELD(bp); 702 703 bp->b_flags |= B_REMFREE; 704 /* Fixup numfreebuffers count. */ 705 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 706 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 707 ("buf %p not counted in numfreebuffers", bp)); 708 bp->b_vflags &= ~BV_INFREECNT; 709 old = atomic_fetchadd_int(&numfreebuffers, -1); 710 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 711 } 712 } 713 714 /* 715 * bremfreef: 716 * 717 * Force an immediate removal from a free list. Used only in nfs when 718 * it abuses the b_freelist pointer. 719 */ 720 void 721 bremfreef(struct buf *bp) 722 { 723 mtx_lock(&bqlock); 724 bremfreel(bp); 725 mtx_unlock(&bqlock); 726 } 727 728 /* 729 * bremfreel: 730 * 731 * Removes a buffer from the free list, must be called with the 732 * bqlock held. 733 */ 734 static void 735 bremfreel(struct buf *bp) 736 { 737 int old; 738 739 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 740 bp, bp->b_vp, bp->b_flags); 741 KASSERT(bp->b_qindex != QUEUE_NONE, 742 ("bremfreel: buffer %p not on a queue.", bp)); 743 BUF_ASSERT_HELD(bp); 744 mtx_assert(&bqlock, MA_OWNED); 745 746 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 747 bp->b_qindex = QUEUE_NONE; 748 /* 749 * If this was a delayed bremfree() we only need to remove the buffer 750 * from the queue and return the stats are already done. 751 */ 752 if (bp->b_flags & B_REMFREE) { 753 bp->b_flags &= ~B_REMFREE; 754 return; 755 } 756 /* 757 * Fixup numfreebuffers count. If the buffer is invalid or not 758 * delayed-write, the buffer was free and we must decrement 759 * numfreebuffers. 760 */ 761 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { 762 KASSERT((bp->b_vflags & BV_INFREECNT) != 0, 763 ("buf %p not counted in numfreebuffers", bp)); 764 bp->b_vflags &= ~BV_INFREECNT; 765 old = atomic_fetchadd_int(&numfreebuffers, -1); 766 KASSERT(old > 0, ("numfreebuffers dropped to %d", old - 1)); 767 } 768 } 769 770 771 /* 772 * Get a buffer with the specified data. Look in the cache first. We 773 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 774 * is set, the buffer is valid and we do not have to do anything ( see 775 * getblk() ). This is really just a special case of breadn(). 776 */ 777 int 778 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 779 struct buf **bpp) 780 { 781 782 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 783 } 784 785 /* 786 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 787 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 788 * the buffer is valid and we do not have to do anything. 789 */ 790 void 791 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 792 int cnt, struct ucred * cred) 793 { 794 struct buf *rabp; 795 int i; 796 797 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 798 if (inmem(vp, *rablkno)) 799 continue; 800 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 801 802 if ((rabp->b_flags & B_CACHE) == 0) { 803 if (!TD_IS_IDLETHREAD(curthread)) 804 curthread->td_ru.ru_inblock++; 805 rabp->b_flags |= B_ASYNC; 806 rabp->b_flags &= ~B_INVAL; 807 rabp->b_ioflags &= ~BIO_ERROR; 808 rabp->b_iocmd = BIO_READ; 809 if (rabp->b_rcred == NOCRED && cred != NOCRED) 810 rabp->b_rcred = crhold(cred); 811 vfs_busy_pages(rabp, 0); 812 BUF_KERNPROC(rabp); 813 rabp->b_iooffset = dbtob(rabp->b_blkno); 814 bstrategy(rabp); 815 } else { 816 brelse(rabp); 817 } 818 } 819 } 820 821 /* 822 * Operates like bread, but also starts asynchronous I/O on 823 * read-ahead blocks. 824 */ 825 int 826 breadn(struct vnode * vp, daddr_t blkno, int size, 827 daddr_t * rablkno, int *rabsize, 828 int cnt, struct ucred * cred, struct buf **bpp) 829 { 830 struct buf *bp; 831 int rv = 0, readwait = 0; 832 833 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 834 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 835 836 /* if not found in cache, do some I/O */ 837 if ((bp->b_flags & B_CACHE) == 0) { 838 if (!TD_IS_IDLETHREAD(curthread)) 839 curthread->td_ru.ru_inblock++; 840 bp->b_iocmd = BIO_READ; 841 bp->b_flags &= ~B_INVAL; 842 bp->b_ioflags &= ~BIO_ERROR; 843 if (bp->b_rcred == NOCRED && cred != NOCRED) 844 bp->b_rcred = crhold(cred); 845 vfs_busy_pages(bp, 0); 846 bp->b_iooffset = dbtob(bp->b_blkno); 847 bstrategy(bp); 848 ++readwait; 849 } 850 851 breada(vp, rablkno, rabsize, cnt, cred); 852 853 if (readwait) { 854 rv = bufwait(bp); 855 } 856 return (rv); 857 } 858 859 /* 860 * Write, release buffer on completion. (Done by iodone 861 * if async). Do not bother writing anything if the buffer 862 * is invalid. 863 * 864 * Note that we set B_CACHE here, indicating that buffer is 865 * fully valid and thus cacheable. This is true even of NFS 866 * now so we set it generally. This could be set either here 867 * or in biodone() since the I/O is synchronous. We put it 868 * here. 869 */ 870 int 871 bufwrite(struct buf *bp) 872 { 873 int oldflags; 874 struct vnode *vp; 875 int vp_md; 876 877 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 878 if (bp->b_flags & B_INVAL) { 879 brelse(bp); 880 return (0); 881 } 882 883 oldflags = bp->b_flags; 884 885 BUF_ASSERT_HELD(bp); 886 887 if (bp->b_pin_count > 0) 888 bunpin_wait(bp); 889 890 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 891 ("FFS background buffer should not get here %p", bp)); 892 893 vp = bp->b_vp; 894 if (vp) 895 vp_md = vp->v_vflag & VV_MD; 896 else 897 vp_md = 0; 898 899 /* Mark the buffer clean */ 900 bundirty(bp); 901 902 bp->b_flags &= ~B_DONE; 903 bp->b_ioflags &= ~BIO_ERROR; 904 bp->b_flags |= B_CACHE; 905 bp->b_iocmd = BIO_WRITE; 906 907 bufobj_wref(bp->b_bufobj); 908 vfs_busy_pages(bp, 1); 909 910 /* 911 * Normal bwrites pipeline writes 912 */ 913 bp->b_runningbufspace = bp->b_bufsize; 914 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 915 916 if (!TD_IS_IDLETHREAD(curthread)) 917 curthread->td_ru.ru_oublock++; 918 if (oldflags & B_ASYNC) 919 BUF_KERNPROC(bp); 920 bp->b_iooffset = dbtob(bp->b_blkno); 921 bstrategy(bp); 922 923 if ((oldflags & B_ASYNC) == 0) { 924 int rtval = bufwait(bp); 925 brelse(bp); 926 return (rtval); 927 } else { 928 /* 929 * don't allow the async write to saturate the I/O 930 * system. We will not deadlock here because 931 * we are blocking waiting for I/O that is already in-progress 932 * to complete. We do not block here if it is the update 933 * or syncer daemon trying to clean up as that can lead 934 * to deadlock. 935 */ 936 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 937 waitrunningbufspace(); 938 } 939 940 return (0); 941 } 942 943 void 944 bufbdflush(struct bufobj *bo, struct buf *bp) 945 { 946 struct buf *nbp; 947 948 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 949 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 950 altbufferflushes++; 951 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 952 BO_LOCK(bo); 953 /* 954 * Try to find a buffer to flush. 955 */ 956 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 957 if ((nbp->b_vflags & BV_BKGRDINPROG) || 958 BUF_LOCK(nbp, 959 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 960 continue; 961 if (bp == nbp) 962 panic("bdwrite: found ourselves"); 963 BO_UNLOCK(bo); 964 /* Don't countdeps with the bo lock held. */ 965 if (buf_countdeps(nbp, 0)) { 966 BO_LOCK(bo); 967 BUF_UNLOCK(nbp); 968 continue; 969 } 970 if (nbp->b_flags & B_CLUSTEROK) { 971 vfs_bio_awrite(nbp); 972 } else { 973 bremfree(nbp); 974 bawrite(nbp); 975 } 976 dirtybufferflushes++; 977 break; 978 } 979 if (nbp == NULL) 980 BO_UNLOCK(bo); 981 } 982 } 983 984 /* 985 * Delayed write. (Buffer is marked dirty). Do not bother writing 986 * anything if the buffer is marked invalid. 987 * 988 * Note that since the buffer must be completely valid, we can safely 989 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 990 * biodone() in order to prevent getblk from writing the buffer 991 * out synchronously. 992 */ 993 void 994 bdwrite(struct buf *bp) 995 { 996 struct thread *td = curthread; 997 struct vnode *vp; 998 struct bufobj *bo; 999 1000 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1001 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1002 BUF_ASSERT_HELD(bp); 1003 1004 if (bp->b_flags & B_INVAL) { 1005 brelse(bp); 1006 return; 1007 } 1008 1009 /* 1010 * If we have too many dirty buffers, don't create any more. 1011 * If we are wildly over our limit, then force a complete 1012 * cleanup. Otherwise, just keep the situation from getting 1013 * out of control. Note that we have to avoid a recursive 1014 * disaster and not try to clean up after our own cleanup! 1015 */ 1016 vp = bp->b_vp; 1017 bo = bp->b_bufobj; 1018 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1019 td->td_pflags |= TDP_INBDFLUSH; 1020 BO_BDFLUSH(bo, bp); 1021 td->td_pflags &= ~TDP_INBDFLUSH; 1022 } else 1023 recursiveflushes++; 1024 1025 bdirty(bp); 1026 /* 1027 * Set B_CACHE, indicating that the buffer is fully valid. This is 1028 * true even of NFS now. 1029 */ 1030 bp->b_flags |= B_CACHE; 1031 1032 /* 1033 * This bmap keeps the system from needing to do the bmap later, 1034 * perhaps when the system is attempting to do a sync. Since it 1035 * is likely that the indirect block -- or whatever other datastructure 1036 * that the filesystem needs is still in memory now, it is a good 1037 * thing to do this. Note also, that if the pageout daemon is 1038 * requesting a sync -- there might not be enough memory to do 1039 * the bmap then... So, this is important to do. 1040 */ 1041 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1042 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1043 } 1044 1045 /* 1046 * Set the *dirty* buffer range based upon the VM system dirty 1047 * pages. 1048 * 1049 * Mark the buffer pages as clean. We need to do this here to 1050 * satisfy the vnode_pager and the pageout daemon, so that it 1051 * thinks that the pages have been "cleaned". Note that since 1052 * the pages are in a delayed write buffer -- the VFS layer 1053 * "will" see that the pages get written out on the next sync, 1054 * or perhaps the cluster will be completed. 1055 */ 1056 vfs_clean_pages_dirty_buf(bp); 1057 bqrelse(bp); 1058 1059 /* 1060 * Wakeup the buffer flushing daemon if we have a lot of dirty 1061 * buffers (midpoint between our recovery point and our stall 1062 * point). 1063 */ 1064 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1065 1066 /* 1067 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1068 * due to the softdep code. 1069 */ 1070 } 1071 1072 /* 1073 * bdirty: 1074 * 1075 * Turn buffer into delayed write request. We must clear BIO_READ and 1076 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1077 * itself to properly update it in the dirty/clean lists. We mark it 1078 * B_DONE to ensure that any asynchronization of the buffer properly 1079 * clears B_DONE ( else a panic will occur later ). 1080 * 1081 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1082 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1083 * should only be called if the buffer is known-good. 1084 * 1085 * Since the buffer is not on a queue, we do not update the numfreebuffers 1086 * count. 1087 * 1088 * The buffer must be on QUEUE_NONE. 1089 */ 1090 void 1091 bdirty(struct buf *bp) 1092 { 1093 1094 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1095 bp, bp->b_vp, bp->b_flags); 1096 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1097 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1098 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1099 BUF_ASSERT_HELD(bp); 1100 bp->b_flags &= ~(B_RELBUF); 1101 bp->b_iocmd = BIO_WRITE; 1102 1103 if ((bp->b_flags & B_DELWRI) == 0) { 1104 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1105 reassignbuf(bp); 1106 atomic_add_int(&numdirtybuffers, 1); 1107 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1108 } 1109 } 1110 1111 /* 1112 * bundirty: 1113 * 1114 * Clear B_DELWRI for buffer. 1115 * 1116 * Since the buffer is not on a queue, we do not update the numfreebuffers 1117 * count. 1118 * 1119 * The buffer must be on QUEUE_NONE. 1120 */ 1121 1122 void 1123 bundirty(struct buf *bp) 1124 { 1125 1126 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1127 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1128 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1129 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1130 BUF_ASSERT_HELD(bp); 1131 1132 if (bp->b_flags & B_DELWRI) { 1133 bp->b_flags &= ~B_DELWRI; 1134 reassignbuf(bp); 1135 atomic_subtract_int(&numdirtybuffers, 1); 1136 numdirtywakeup(lodirtybuffers); 1137 } 1138 /* 1139 * Since it is now being written, we can clear its deferred write flag. 1140 */ 1141 bp->b_flags &= ~B_DEFERRED; 1142 } 1143 1144 /* 1145 * bawrite: 1146 * 1147 * Asynchronous write. Start output on a buffer, but do not wait for 1148 * it to complete. The buffer is released when the output completes. 1149 * 1150 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1151 * B_INVAL buffers. Not us. 1152 */ 1153 void 1154 bawrite(struct buf *bp) 1155 { 1156 1157 bp->b_flags |= B_ASYNC; 1158 (void) bwrite(bp); 1159 } 1160 1161 /* 1162 * bwillwrite: 1163 * 1164 * Called prior to the locking of any vnodes when we are expecting to 1165 * write. We do not want to starve the buffer cache with too many 1166 * dirty buffers so we block here. By blocking prior to the locking 1167 * of any vnodes we attempt to avoid the situation where a locked vnode 1168 * prevents the various system daemons from flushing related buffers. 1169 */ 1170 1171 void 1172 bwillwrite(void) 1173 { 1174 1175 if (numdirtybuffers >= hidirtybuffers) { 1176 mtx_lock(&nblock); 1177 while (numdirtybuffers >= hidirtybuffers) { 1178 bd_wakeup(1); 1179 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1180 msleep(&needsbuffer, &nblock, 1181 (PRIBIO + 4), "flswai", 0); 1182 } 1183 mtx_unlock(&nblock); 1184 } 1185 } 1186 1187 /* 1188 * Return true if we have too many dirty buffers. 1189 */ 1190 int 1191 buf_dirty_count_severe(void) 1192 { 1193 1194 return(numdirtybuffers >= hidirtybuffers); 1195 } 1196 1197 static __noinline int 1198 buf_vm_page_count_severe(void) 1199 { 1200 1201 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1202 1203 return vm_page_count_severe(); 1204 } 1205 1206 /* 1207 * brelse: 1208 * 1209 * Release a busy buffer and, if requested, free its resources. The 1210 * buffer will be stashed in the appropriate bufqueue[] allowing it 1211 * to be accessed later as a cache entity or reused for other purposes. 1212 */ 1213 void 1214 brelse(struct buf *bp) 1215 { 1216 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1217 bp, bp->b_vp, bp->b_flags); 1218 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1219 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1220 1221 if (bp->b_flags & B_MANAGED) { 1222 bqrelse(bp); 1223 return; 1224 } 1225 1226 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1227 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1228 /* 1229 * Failed write, redirty. Must clear BIO_ERROR to prevent 1230 * pages from being scrapped. If the error is anything 1231 * other than an I/O error (EIO), assume that retrying 1232 * is futile. 1233 */ 1234 bp->b_ioflags &= ~BIO_ERROR; 1235 bdirty(bp); 1236 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1237 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1238 /* 1239 * Either a failed I/O or we were asked to free or not 1240 * cache the buffer. 1241 */ 1242 bp->b_flags |= B_INVAL; 1243 if (!LIST_EMPTY(&bp->b_dep)) 1244 buf_deallocate(bp); 1245 if (bp->b_flags & B_DELWRI) { 1246 atomic_subtract_int(&numdirtybuffers, 1); 1247 numdirtywakeup(lodirtybuffers); 1248 } 1249 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1250 if ((bp->b_flags & B_VMIO) == 0) { 1251 if (bp->b_bufsize) 1252 allocbuf(bp, 0); 1253 if (bp->b_vp) 1254 brelvp(bp); 1255 } 1256 } 1257 1258 /* 1259 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1260 * is called with B_DELWRI set, the underlying pages may wind up 1261 * getting freed causing a previous write (bdwrite()) to get 'lost' 1262 * because pages associated with a B_DELWRI bp are marked clean. 1263 * 1264 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1265 * if B_DELWRI is set. 1266 * 1267 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1268 * on pages to return pages to the VM page queues. 1269 */ 1270 if (bp->b_flags & B_DELWRI) 1271 bp->b_flags &= ~B_RELBUF; 1272 else if (buf_vm_page_count_severe()) { 1273 /* 1274 * The locking of the BO_LOCK is not necessary since 1275 * BKGRDINPROG cannot be set while we hold the buf 1276 * lock, it can only be cleared if it is already 1277 * pending. 1278 */ 1279 if (bp->b_vp) { 1280 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1281 bp->b_flags |= B_RELBUF; 1282 } else 1283 bp->b_flags |= B_RELBUF; 1284 } 1285 1286 /* 1287 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1288 * constituted, not even NFS buffers now. Two flags effect this. If 1289 * B_INVAL, the struct buf is invalidated but the VM object is kept 1290 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1291 * 1292 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1293 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1294 * buffer is also B_INVAL because it hits the re-dirtying code above. 1295 * 1296 * Normally we can do this whether a buffer is B_DELWRI or not. If 1297 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1298 * the commit state and we cannot afford to lose the buffer. If the 1299 * buffer has a background write in progress, we need to keep it 1300 * around to prevent it from being reconstituted and starting a second 1301 * background write. 1302 */ 1303 if ((bp->b_flags & B_VMIO) 1304 && !(bp->b_vp->v_mount != NULL && 1305 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1306 !vn_isdisk(bp->b_vp, NULL) && 1307 (bp->b_flags & B_DELWRI)) 1308 ) { 1309 1310 int i, j, resid; 1311 vm_page_t m; 1312 off_t foff; 1313 vm_pindex_t poff; 1314 vm_object_t obj; 1315 1316 obj = bp->b_bufobj->bo_object; 1317 1318 /* 1319 * Get the base offset and length of the buffer. Note that 1320 * in the VMIO case if the buffer block size is not 1321 * page-aligned then b_data pointer may not be page-aligned. 1322 * But our b_pages[] array *IS* page aligned. 1323 * 1324 * block sizes less then DEV_BSIZE (usually 512) are not 1325 * supported due to the page granularity bits (m->valid, 1326 * m->dirty, etc...). 1327 * 1328 * See man buf(9) for more information 1329 */ 1330 resid = bp->b_bufsize; 1331 foff = bp->b_offset; 1332 VM_OBJECT_LOCK(obj); 1333 for (i = 0; i < bp->b_npages; i++) { 1334 int had_bogus = 0; 1335 1336 m = bp->b_pages[i]; 1337 1338 /* 1339 * If we hit a bogus page, fixup *all* the bogus pages 1340 * now. 1341 */ 1342 if (m == bogus_page) { 1343 poff = OFF_TO_IDX(bp->b_offset); 1344 had_bogus = 1; 1345 1346 for (j = i; j < bp->b_npages; j++) { 1347 vm_page_t mtmp; 1348 mtmp = bp->b_pages[j]; 1349 if (mtmp == bogus_page) { 1350 mtmp = vm_page_lookup(obj, poff + j); 1351 if (!mtmp) { 1352 panic("brelse: page missing\n"); 1353 } 1354 bp->b_pages[j] = mtmp; 1355 } 1356 } 1357 1358 if ((bp->b_flags & B_INVAL) == 0) { 1359 pmap_qenter( 1360 trunc_page((vm_offset_t)bp->b_data), 1361 bp->b_pages, bp->b_npages); 1362 } 1363 m = bp->b_pages[i]; 1364 } 1365 if ((bp->b_flags & B_NOCACHE) || 1366 (bp->b_ioflags & BIO_ERROR && 1367 bp->b_iocmd == BIO_READ)) { 1368 int poffset = foff & PAGE_MASK; 1369 int presid = resid > (PAGE_SIZE - poffset) ? 1370 (PAGE_SIZE - poffset) : resid; 1371 1372 KASSERT(presid >= 0, ("brelse: extra page")); 1373 vm_page_set_invalid(m, poffset, presid); 1374 if (had_bogus) 1375 printf("avoided corruption bug in bogus_page/brelse code\n"); 1376 } 1377 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1378 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1379 } 1380 VM_OBJECT_UNLOCK(obj); 1381 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1382 vfs_vmio_release(bp); 1383 1384 } else if (bp->b_flags & B_VMIO) { 1385 1386 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1387 vfs_vmio_release(bp); 1388 } 1389 1390 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1391 if (bp->b_bufsize != 0) 1392 allocbuf(bp, 0); 1393 if (bp->b_vp != NULL) 1394 brelvp(bp); 1395 } 1396 1397 if (BUF_LOCKRECURSED(bp)) { 1398 /* do not release to free list */ 1399 BUF_UNLOCK(bp); 1400 return; 1401 } 1402 1403 /* enqueue */ 1404 mtx_lock(&bqlock); 1405 /* Handle delayed bremfree() processing. */ 1406 if (bp->b_flags & B_REMFREE) 1407 bremfreel(bp); 1408 if (bp->b_qindex != QUEUE_NONE) 1409 panic("brelse: free buffer onto another queue???"); 1410 1411 /* 1412 * If the buffer has junk contents signal it and eventually 1413 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1414 * doesn't find it. 1415 */ 1416 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1417 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1418 bp->b_flags |= B_INVAL; 1419 if (bp->b_flags & B_INVAL) { 1420 if (bp->b_flags & B_DELWRI) 1421 bundirty(bp); 1422 if (bp->b_vp) 1423 brelvp(bp); 1424 } 1425 1426 /* buffers with no memory */ 1427 if (bp->b_bufsize == 0) { 1428 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1429 if (bp->b_vflags & BV_BKGRDINPROG) 1430 panic("losing buffer 1"); 1431 if (bp->b_kvasize) { 1432 bp->b_qindex = QUEUE_EMPTYKVA; 1433 } else { 1434 bp->b_qindex = QUEUE_EMPTY; 1435 } 1436 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1437 /* buffers with junk contents */ 1438 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1439 (bp->b_ioflags & BIO_ERROR)) { 1440 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1441 if (bp->b_vflags & BV_BKGRDINPROG) 1442 panic("losing buffer 2"); 1443 bp->b_qindex = QUEUE_CLEAN; 1444 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1445 /* remaining buffers */ 1446 } else { 1447 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1448 (B_DELWRI|B_NEEDSGIANT)) 1449 bp->b_qindex = QUEUE_DIRTY_GIANT; 1450 else if (bp->b_flags & B_DELWRI) 1451 bp->b_qindex = QUEUE_DIRTY; 1452 else 1453 bp->b_qindex = QUEUE_CLEAN; 1454 if (bp->b_flags & B_AGE) 1455 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1456 else 1457 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1458 } 1459 mtx_unlock(&bqlock); 1460 1461 /* 1462 * Fixup numfreebuffers count. The bp is on an appropriate queue 1463 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1464 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1465 * if B_INVAL is set ). 1466 */ 1467 1468 if (!(bp->b_flags & B_DELWRI)) 1469 bufcountwakeup(bp); 1470 1471 /* 1472 * Something we can maybe free or reuse 1473 */ 1474 if (bp->b_bufsize || bp->b_kvasize) 1475 bufspacewakeup(); 1476 1477 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1478 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1479 panic("brelse: not dirty"); 1480 /* unlock */ 1481 BUF_UNLOCK(bp); 1482 } 1483 1484 /* 1485 * Release a buffer back to the appropriate queue but do not try to free 1486 * it. The buffer is expected to be used again soon. 1487 * 1488 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1489 * biodone() to requeue an async I/O on completion. It is also used when 1490 * known good buffers need to be requeued but we think we may need the data 1491 * again soon. 1492 * 1493 * XXX we should be able to leave the B_RELBUF hint set on completion. 1494 */ 1495 void 1496 bqrelse(struct buf *bp) 1497 { 1498 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1499 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1500 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1501 1502 if (BUF_LOCKRECURSED(bp)) { 1503 /* do not release to free list */ 1504 BUF_UNLOCK(bp); 1505 return; 1506 } 1507 1508 if (bp->b_flags & B_MANAGED) { 1509 if (bp->b_flags & B_REMFREE) { 1510 mtx_lock(&bqlock); 1511 bremfreel(bp); 1512 mtx_unlock(&bqlock); 1513 } 1514 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1515 BUF_UNLOCK(bp); 1516 return; 1517 } 1518 1519 mtx_lock(&bqlock); 1520 /* Handle delayed bremfree() processing. */ 1521 if (bp->b_flags & B_REMFREE) 1522 bremfreel(bp); 1523 if (bp->b_qindex != QUEUE_NONE) 1524 panic("bqrelse: free buffer onto another queue???"); 1525 /* buffers with stale but valid contents */ 1526 if (bp->b_flags & B_DELWRI) { 1527 if (bp->b_flags & B_NEEDSGIANT) 1528 bp->b_qindex = QUEUE_DIRTY_GIANT; 1529 else 1530 bp->b_qindex = QUEUE_DIRTY; 1531 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1532 } else { 1533 /* 1534 * The locking of the BO_LOCK for checking of the 1535 * BV_BKGRDINPROG is not necessary since the 1536 * BV_BKGRDINPROG cannot be set while we hold the buf 1537 * lock, it can only be cleared if it is already 1538 * pending. 1539 */ 1540 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1541 bp->b_qindex = QUEUE_CLEAN; 1542 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1543 b_freelist); 1544 } else { 1545 /* 1546 * We are too low on memory, we have to try to free 1547 * the buffer (most importantly: the wired pages 1548 * making up its backing store) *now*. 1549 */ 1550 mtx_unlock(&bqlock); 1551 brelse(bp); 1552 return; 1553 } 1554 } 1555 mtx_unlock(&bqlock); 1556 1557 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1558 bufcountwakeup(bp); 1559 1560 /* 1561 * Something we can maybe free or reuse. 1562 */ 1563 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1564 bufspacewakeup(); 1565 1566 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1567 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1568 panic("bqrelse: not dirty"); 1569 /* unlock */ 1570 BUF_UNLOCK(bp); 1571 } 1572 1573 /* Give pages used by the bp back to the VM system (where possible) */ 1574 static void 1575 vfs_vmio_release(struct buf *bp) 1576 { 1577 int i; 1578 vm_page_t m; 1579 1580 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1581 for (i = 0; i < bp->b_npages; i++) { 1582 m = bp->b_pages[i]; 1583 bp->b_pages[i] = NULL; 1584 /* 1585 * In order to keep page LRU ordering consistent, put 1586 * everything on the inactive queue. 1587 */ 1588 vm_page_lock(m); 1589 vm_page_unwire(m, 0); 1590 /* 1591 * We don't mess with busy pages, it is 1592 * the responsibility of the process that 1593 * busied the pages to deal with them. 1594 */ 1595 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1596 m->wire_count == 0) { 1597 /* 1598 * Might as well free the page if we can and it has 1599 * no valid data. We also free the page if the 1600 * buffer was used for direct I/O 1601 */ 1602 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1603 m->hold_count == 0) { 1604 vm_page_free(m); 1605 } else if (bp->b_flags & B_DIRECT) { 1606 vm_page_try_to_free(m); 1607 } else if (buf_vm_page_count_severe()) { 1608 vm_page_try_to_cache(m); 1609 } 1610 } 1611 vm_page_unlock(m); 1612 } 1613 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1614 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1615 1616 if (bp->b_bufsize) { 1617 bufspacewakeup(); 1618 bp->b_bufsize = 0; 1619 } 1620 bp->b_npages = 0; 1621 bp->b_flags &= ~B_VMIO; 1622 if (bp->b_vp) 1623 brelvp(bp); 1624 } 1625 1626 /* 1627 * Check to see if a block at a particular lbn is available for a clustered 1628 * write. 1629 */ 1630 static int 1631 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1632 { 1633 struct buf *bpa; 1634 int match; 1635 1636 match = 0; 1637 1638 /* If the buf isn't in core skip it */ 1639 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1640 return (0); 1641 1642 /* If the buf is busy we don't want to wait for it */ 1643 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1644 return (0); 1645 1646 /* Only cluster with valid clusterable delayed write buffers */ 1647 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1648 (B_DELWRI | B_CLUSTEROK)) 1649 goto done; 1650 1651 if (bpa->b_bufsize != size) 1652 goto done; 1653 1654 /* 1655 * Check to see if it is in the expected place on disk and that the 1656 * block has been mapped. 1657 */ 1658 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1659 match = 1; 1660 done: 1661 BUF_UNLOCK(bpa); 1662 return (match); 1663 } 1664 1665 /* 1666 * vfs_bio_awrite: 1667 * 1668 * Implement clustered async writes for clearing out B_DELWRI buffers. 1669 * This is much better then the old way of writing only one buffer at 1670 * a time. Note that we may not be presented with the buffers in the 1671 * correct order, so we search for the cluster in both directions. 1672 */ 1673 int 1674 vfs_bio_awrite(struct buf *bp) 1675 { 1676 struct bufobj *bo; 1677 int i; 1678 int j; 1679 daddr_t lblkno = bp->b_lblkno; 1680 struct vnode *vp = bp->b_vp; 1681 int ncl; 1682 int nwritten; 1683 int size; 1684 int maxcl; 1685 1686 bo = &vp->v_bufobj; 1687 /* 1688 * right now we support clustered writing only to regular files. If 1689 * we find a clusterable block we could be in the middle of a cluster 1690 * rather then at the beginning. 1691 */ 1692 if ((vp->v_type == VREG) && 1693 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1694 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1695 1696 size = vp->v_mount->mnt_stat.f_iosize; 1697 maxcl = MAXPHYS / size; 1698 1699 BO_LOCK(bo); 1700 for (i = 1; i < maxcl; i++) 1701 if (vfs_bio_clcheck(vp, size, lblkno + i, 1702 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1703 break; 1704 1705 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1706 if (vfs_bio_clcheck(vp, size, lblkno - j, 1707 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1708 break; 1709 BO_UNLOCK(bo); 1710 --j; 1711 ncl = i + j; 1712 /* 1713 * this is a possible cluster write 1714 */ 1715 if (ncl != 1) { 1716 BUF_UNLOCK(bp); 1717 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1718 return nwritten; 1719 } 1720 } 1721 bremfree(bp); 1722 bp->b_flags |= B_ASYNC; 1723 /* 1724 * default (old) behavior, writing out only one block 1725 * 1726 * XXX returns b_bufsize instead of b_bcount for nwritten? 1727 */ 1728 nwritten = bp->b_bufsize; 1729 (void) bwrite(bp); 1730 1731 return nwritten; 1732 } 1733 1734 /* 1735 * getnewbuf: 1736 * 1737 * Find and initialize a new buffer header, freeing up existing buffers 1738 * in the bufqueues as necessary. The new buffer is returned locked. 1739 * 1740 * Important: B_INVAL is not set. If the caller wishes to throw the 1741 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1742 * 1743 * We block if: 1744 * We have insufficient buffer headers 1745 * We have insufficient buffer space 1746 * buffer_map is too fragmented ( space reservation fails ) 1747 * If we have to flush dirty buffers ( but we try to avoid this ) 1748 * 1749 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1750 * Instead we ask the buf daemon to do it for us. We attempt to 1751 * avoid piecemeal wakeups of the pageout daemon. 1752 */ 1753 1754 static struct buf * 1755 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1756 int gbflags) 1757 { 1758 struct thread *td; 1759 struct buf *bp; 1760 struct buf *nbp; 1761 int defrag = 0; 1762 int nqindex; 1763 static int flushingbufs; 1764 1765 td = curthread; 1766 /* 1767 * We can't afford to block since we might be holding a vnode lock, 1768 * which may prevent system daemons from running. We deal with 1769 * low-memory situations by proactively returning memory and running 1770 * async I/O rather then sync I/O. 1771 */ 1772 atomic_add_int(&getnewbufcalls, 1); 1773 atomic_subtract_int(&getnewbufrestarts, 1); 1774 restart: 1775 atomic_add_int(&getnewbufrestarts, 1); 1776 1777 /* 1778 * Setup for scan. If we do not have enough free buffers, 1779 * we setup a degenerate case that immediately fails. Note 1780 * that if we are specially marked process, we are allowed to 1781 * dip into our reserves. 1782 * 1783 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1784 * 1785 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1786 * However, there are a number of cases (defragging, reusing, ...) 1787 * where we cannot backup. 1788 */ 1789 mtx_lock(&bqlock); 1790 nqindex = QUEUE_EMPTYKVA; 1791 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1792 1793 if (nbp == NULL) { 1794 /* 1795 * If no EMPTYKVA buffers and we are either 1796 * defragging or reusing, locate a CLEAN buffer 1797 * to free or reuse. If bufspace useage is low 1798 * skip this step so we can allocate a new buffer. 1799 */ 1800 if (defrag || bufspace >= lobufspace) { 1801 nqindex = QUEUE_CLEAN; 1802 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1803 } 1804 1805 /* 1806 * If we could not find or were not allowed to reuse a 1807 * CLEAN buffer, check to see if it is ok to use an EMPTY 1808 * buffer. We can only use an EMPTY buffer if allocating 1809 * its KVA would not otherwise run us out of buffer space. 1810 */ 1811 if (nbp == NULL && defrag == 0 && 1812 bufspace + maxsize < hibufspace) { 1813 nqindex = QUEUE_EMPTY; 1814 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1815 } 1816 } 1817 1818 /* 1819 * Run scan, possibly freeing data and/or kva mappings on the fly 1820 * depending. 1821 */ 1822 1823 while ((bp = nbp) != NULL) { 1824 int qindex = nqindex; 1825 1826 /* 1827 * Calculate next bp ( we can only use it if we do not block 1828 * or do other fancy things ). 1829 */ 1830 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1831 switch(qindex) { 1832 case QUEUE_EMPTY: 1833 nqindex = QUEUE_EMPTYKVA; 1834 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1835 break; 1836 /* FALLTHROUGH */ 1837 case QUEUE_EMPTYKVA: 1838 nqindex = QUEUE_CLEAN; 1839 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1840 break; 1841 /* FALLTHROUGH */ 1842 case QUEUE_CLEAN: 1843 /* 1844 * nbp is NULL. 1845 */ 1846 break; 1847 } 1848 } 1849 /* 1850 * If we are defragging then we need a buffer with 1851 * b_kvasize != 0. XXX this situation should no longer 1852 * occur, if defrag is non-zero the buffer's b_kvasize 1853 * should also be non-zero at this point. XXX 1854 */ 1855 if (defrag && bp->b_kvasize == 0) { 1856 printf("Warning: defrag empty buffer %p\n", bp); 1857 continue; 1858 } 1859 1860 /* 1861 * Start freeing the bp. This is somewhat involved. nbp 1862 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1863 */ 1864 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1865 continue; 1866 if (bp->b_vp) { 1867 BO_LOCK(bp->b_bufobj); 1868 if (bp->b_vflags & BV_BKGRDINPROG) { 1869 BO_UNLOCK(bp->b_bufobj); 1870 BUF_UNLOCK(bp); 1871 continue; 1872 } 1873 BO_UNLOCK(bp->b_bufobj); 1874 } 1875 CTR6(KTR_BUF, 1876 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1877 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1878 bp->b_kvasize, bp->b_bufsize, qindex); 1879 1880 /* 1881 * Sanity Checks 1882 */ 1883 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1884 1885 /* 1886 * Note: we no longer distinguish between VMIO and non-VMIO 1887 * buffers. 1888 */ 1889 1890 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1891 1892 bremfreel(bp); 1893 mtx_unlock(&bqlock); 1894 1895 if (qindex == QUEUE_CLEAN) { 1896 if (bp->b_flags & B_VMIO) { 1897 bp->b_flags &= ~B_ASYNC; 1898 vfs_vmio_release(bp); 1899 } 1900 if (bp->b_vp) 1901 brelvp(bp); 1902 } 1903 1904 /* 1905 * NOTE: nbp is now entirely invalid. We can only restart 1906 * the scan from this point on. 1907 * 1908 * Get the rest of the buffer freed up. b_kva* is still 1909 * valid after this operation. 1910 */ 1911 1912 if (bp->b_rcred != NOCRED) { 1913 crfree(bp->b_rcred); 1914 bp->b_rcred = NOCRED; 1915 } 1916 if (bp->b_wcred != NOCRED) { 1917 crfree(bp->b_wcred); 1918 bp->b_wcred = NOCRED; 1919 } 1920 if (!LIST_EMPTY(&bp->b_dep)) 1921 buf_deallocate(bp); 1922 if (bp->b_vflags & BV_BKGRDINPROG) 1923 panic("losing buffer 3"); 1924 KASSERT(bp->b_vp == NULL, 1925 ("bp: %p still has vnode %p. qindex: %d", 1926 bp, bp->b_vp, qindex)); 1927 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1928 ("bp: %p still on a buffer list. xflags %X", 1929 bp, bp->b_xflags)); 1930 1931 if (bp->b_bufsize) 1932 allocbuf(bp, 0); 1933 1934 bp->b_flags = 0; 1935 bp->b_ioflags = 0; 1936 bp->b_xflags = 0; 1937 KASSERT((bp->b_vflags & BV_INFREECNT) == 0, 1938 ("buf %p still counted as free?", bp)); 1939 bp->b_vflags = 0; 1940 bp->b_vp = NULL; 1941 bp->b_blkno = bp->b_lblkno = 0; 1942 bp->b_offset = NOOFFSET; 1943 bp->b_iodone = 0; 1944 bp->b_error = 0; 1945 bp->b_resid = 0; 1946 bp->b_bcount = 0; 1947 bp->b_npages = 0; 1948 bp->b_dirtyoff = bp->b_dirtyend = 0; 1949 bp->b_bufobj = NULL; 1950 bp->b_pin_count = 0; 1951 bp->b_fsprivate1 = NULL; 1952 bp->b_fsprivate2 = NULL; 1953 bp->b_fsprivate3 = NULL; 1954 1955 LIST_INIT(&bp->b_dep); 1956 1957 /* 1958 * If we are defragging then free the buffer. 1959 */ 1960 if (defrag) { 1961 bp->b_flags |= B_INVAL; 1962 bfreekva(bp); 1963 brelse(bp); 1964 defrag = 0; 1965 goto restart; 1966 } 1967 1968 /* 1969 * Notify any waiters for the buffer lock about 1970 * identity change by freeing the buffer. 1971 */ 1972 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 1973 bp->b_flags |= B_INVAL; 1974 bfreekva(bp); 1975 brelse(bp); 1976 goto restart; 1977 } 1978 1979 /* 1980 * If we are overcomitted then recover the buffer and its 1981 * KVM space. This occurs in rare situations when multiple 1982 * processes are blocked in getnewbuf() or allocbuf(). 1983 */ 1984 if (bufspace >= hibufspace) 1985 flushingbufs = 1; 1986 if (flushingbufs && bp->b_kvasize != 0) { 1987 bp->b_flags |= B_INVAL; 1988 bfreekva(bp); 1989 brelse(bp); 1990 goto restart; 1991 } 1992 if (bufspace < lobufspace) 1993 flushingbufs = 0; 1994 break; 1995 } 1996 1997 /* 1998 * If we exhausted our list, sleep as appropriate. We may have to 1999 * wakeup various daemons and write out some dirty buffers. 2000 * 2001 * Generally we are sleeping due to insufficient buffer space. 2002 */ 2003 2004 if (bp == NULL) { 2005 int flags, norunbuf; 2006 char *waitmsg; 2007 int fl; 2008 2009 if (defrag) { 2010 flags = VFS_BIO_NEED_BUFSPACE; 2011 waitmsg = "nbufkv"; 2012 } else if (bufspace >= hibufspace) { 2013 waitmsg = "nbufbs"; 2014 flags = VFS_BIO_NEED_BUFSPACE; 2015 } else { 2016 waitmsg = "newbuf"; 2017 flags = VFS_BIO_NEED_ANY; 2018 } 2019 mtx_lock(&nblock); 2020 needsbuffer |= flags; 2021 mtx_unlock(&nblock); 2022 mtx_unlock(&bqlock); 2023 2024 bd_speedup(); /* heeeelp */ 2025 if (gbflags & GB_NOWAIT_BD) 2026 return (NULL); 2027 2028 mtx_lock(&nblock); 2029 while (needsbuffer & flags) { 2030 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2031 mtx_unlock(&nblock); 2032 /* 2033 * getblk() is called with a vnode 2034 * locked, and some majority of the 2035 * dirty buffers may as well belong to 2036 * the vnode. Flushing the buffers 2037 * there would make a progress that 2038 * cannot be achieved by the 2039 * buf_daemon, that cannot lock the 2040 * vnode. 2041 */ 2042 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2043 (td->td_pflags & TDP_NORUNNINGBUF); 2044 /* play bufdaemon */ 2045 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2046 fl = buf_do_flush(vp); 2047 td->td_pflags &= norunbuf; 2048 mtx_lock(&nblock); 2049 if (fl != 0) 2050 continue; 2051 if ((needsbuffer & flags) == 0) 2052 break; 2053 } 2054 if (msleep(&needsbuffer, &nblock, 2055 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2056 mtx_unlock(&nblock); 2057 return (NULL); 2058 } 2059 } 2060 mtx_unlock(&nblock); 2061 } else { 2062 /* 2063 * We finally have a valid bp. We aren't quite out of the 2064 * woods, we still have to reserve kva space. In order 2065 * to keep fragmentation sane we only allocate kva in 2066 * BKVASIZE chunks. 2067 */ 2068 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2069 2070 if (maxsize != bp->b_kvasize) { 2071 vm_offset_t addr = 0; 2072 2073 bfreekva(bp); 2074 2075 vm_map_lock(buffer_map); 2076 if (vm_map_findspace(buffer_map, 2077 vm_map_min(buffer_map), maxsize, &addr)) { 2078 /* 2079 * Uh oh. Buffer map is to fragmented. We 2080 * must defragment the map. 2081 */ 2082 atomic_add_int(&bufdefragcnt, 1); 2083 vm_map_unlock(buffer_map); 2084 defrag = 1; 2085 bp->b_flags |= B_INVAL; 2086 brelse(bp); 2087 goto restart; 2088 } 2089 if (addr) { 2090 vm_map_insert(buffer_map, NULL, 0, 2091 addr, addr + maxsize, 2092 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2093 2094 bp->b_kvabase = (caddr_t) addr; 2095 bp->b_kvasize = maxsize; 2096 atomic_add_long(&bufspace, bp->b_kvasize); 2097 atomic_add_int(&bufreusecnt, 1); 2098 } 2099 vm_map_unlock(buffer_map); 2100 } 2101 bp->b_saveaddr = bp->b_kvabase; 2102 bp->b_data = bp->b_saveaddr; 2103 } 2104 return(bp); 2105 } 2106 2107 /* 2108 * buf_daemon: 2109 * 2110 * buffer flushing daemon. Buffers are normally flushed by the 2111 * update daemon but if it cannot keep up this process starts to 2112 * take the load in an attempt to prevent getnewbuf() from blocking. 2113 */ 2114 2115 static struct kproc_desc buf_kp = { 2116 "bufdaemon", 2117 buf_daemon, 2118 &bufdaemonproc 2119 }; 2120 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2121 2122 static int 2123 buf_do_flush(struct vnode *vp) 2124 { 2125 int flushed; 2126 2127 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2128 /* The list empty check here is slightly racy */ 2129 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2130 mtx_lock(&Giant); 2131 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0); 2132 mtx_unlock(&Giant); 2133 } 2134 if (flushed == 0) { 2135 /* 2136 * Could not find any buffers without rollback 2137 * dependencies, so just write the first one 2138 * in the hopes of eventually making progress. 2139 */ 2140 flushbufqueues(vp, QUEUE_DIRTY, 1); 2141 if (!TAILQ_EMPTY( 2142 &bufqueues[QUEUE_DIRTY_GIANT])) { 2143 mtx_lock(&Giant); 2144 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1); 2145 mtx_unlock(&Giant); 2146 } 2147 } 2148 return (flushed); 2149 } 2150 2151 static void 2152 buf_daemon() 2153 { 2154 int lodirtysave; 2155 2156 /* 2157 * This process needs to be suspended prior to shutdown sync. 2158 */ 2159 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2160 SHUTDOWN_PRI_LAST); 2161 2162 /* 2163 * This process is allowed to take the buffer cache to the limit 2164 */ 2165 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2166 mtx_lock(&bdlock); 2167 for (;;) { 2168 bd_request = 0; 2169 mtx_unlock(&bdlock); 2170 2171 kproc_suspend_check(bufdaemonproc); 2172 lodirtysave = lodirtybuffers; 2173 if (bd_speedupreq) { 2174 lodirtybuffers = numdirtybuffers / 2; 2175 bd_speedupreq = 0; 2176 } 2177 /* 2178 * Do the flush. Limit the amount of in-transit I/O we 2179 * allow to build up, otherwise we would completely saturate 2180 * the I/O system. Wakeup any waiting processes before we 2181 * normally would so they can run in parallel with our drain. 2182 */ 2183 while (numdirtybuffers > lodirtybuffers) { 2184 if (buf_do_flush(NULL) == 0) 2185 break; 2186 uio_yield(); 2187 } 2188 lodirtybuffers = lodirtysave; 2189 2190 /* 2191 * Only clear bd_request if we have reached our low water 2192 * mark. The buf_daemon normally waits 1 second and 2193 * then incrementally flushes any dirty buffers that have 2194 * built up, within reason. 2195 * 2196 * If we were unable to hit our low water mark and couldn't 2197 * find any flushable buffers, we sleep half a second. 2198 * Otherwise we loop immediately. 2199 */ 2200 mtx_lock(&bdlock); 2201 if (numdirtybuffers <= lodirtybuffers) { 2202 /* 2203 * We reached our low water mark, reset the 2204 * request and sleep until we are needed again. 2205 * The sleep is just so the suspend code works. 2206 */ 2207 bd_request = 0; 2208 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2209 } else { 2210 /* 2211 * We couldn't find any flushable dirty buffers but 2212 * still have too many dirty buffers, we 2213 * have to sleep and try again. (rare) 2214 */ 2215 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2216 } 2217 } 2218 } 2219 2220 /* 2221 * flushbufqueues: 2222 * 2223 * Try to flush a buffer in the dirty queue. We must be careful to 2224 * free up B_INVAL buffers instead of write them, which NFS is 2225 * particularly sensitive to. 2226 */ 2227 static int flushwithdeps = 0; 2228 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2229 0, "Number of buffers flushed with dependecies that require rollbacks"); 2230 2231 static int 2232 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2233 { 2234 struct buf *sentinel; 2235 struct vnode *vp; 2236 struct mount *mp; 2237 struct buf *bp; 2238 int hasdeps; 2239 int flushed; 2240 int target; 2241 2242 if (lvp == NULL) { 2243 target = numdirtybuffers - lodirtybuffers; 2244 if (flushdeps && target > 2) 2245 target /= 2; 2246 } else 2247 target = flushbufqtarget; 2248 flushed = 0; 2249 bp = NULL; 2250 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2251 sentinel->b_qindex = QUEUE_SENTINEL; 2252 mtx_lock(&bqlock); 2253 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2254 while (flushed != target) { 2255 bp = TAILQ_NEXT(sentinel, b_freelist); 2256 if (bp != NULL) { 2257 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2258 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2259 b_freelist); 2260 } else 2261 break; 2262 /* 2263 * Skip sentinels inserted by other invocations of the 2264 * flushbufqueues(), taking care to not reorder them. 2265 */ 2266 if (bp->b_qindex == QUEUE_SENTINEL) 2267 continue; 2268 /* 2269 * Only flush the buffers that belong to the 2270 * vnode locked by the curthread. 2271 */ 2272 if (lvp != NULL && bp->b_vp != lvp) 2273 continue; 2274 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2275 continue; 2276 if (bp->b_pin_count > 0) { 2277 BUF_UNLOCK(bp); 2278 continue; 2279 } 2280 BO_LOCK(bp->b_bufobj); 2281 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2282 (bp->b_flags & B_DELWRI) == 0) { 2283 BO_UNLOCK(bp->b_bufobj); 2284 BUF_UNLOCK(bp); 2285 continue; 2286 } 2287 BO_UNLOCK(bp->b_bufobj); 2288 if (bp->b_flags & B_INVAL) { 2289 bremfreel(bp); 2290 mtx_unlock(&bqlock); 2291 brelse(bp); 2292 flushed++; 2293 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2294 mtx_lock(&bqlock); 2295 continue; 2296 } 2297 2298 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2299 if (flushdeps == 0) { 2300 BUF_UNLOCK(bp); 2301 continue; 2302 } 2303 hasdeps = 1; 2304 } else 2305 hasdeps = 0; 2306 /* 2307 * We must hold the lock on a vnode before writing 2308 * one of its buffers. Otherwise we may confuse, or 2309 * in the case of a snapshot vnode, deadlock the 2310 * system. 2311 * 2312 * The lock order here is the reverse of the normal 2313 * of vnode followed by buf lock. This is ok because 2314 * the NOWAIT will prevent deadlock. 2315 */ 2316 vp = bp->b_vp; 2317 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2318 BUF_UNLOCK(bp); 2319 continue; 2320 } 2321 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2322 mtx_unlock(&bqlock); 2323 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2324 bp, bp->b_vp, bp->b_flags); 2325 if (curproc == bufdaemonproc) 2326 vfs_bio_awrite(bp); 2327 else { 2328 bremfree(bp); 2329 bwrite(bp); 2330 notbufdflashes++; 2331 } 2332 vn_finished_write(mp); 2333 VOP_UNLOCK(vp, 0); 2334 flushwithdeps += hasdeps; 2335 flushed++; 2336 2337 /* 2338 * Sleeping on runningbufspace while holding 2339 * vnode lock leads to deadlock. 2340 */ 2341 if (curproc == bufdaemonproc) 2342 waitrunningbufspace(); 2343 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2344 mtx_lock(&bqlock); 2345 continue; 2346 } 2347 vn_finished_write(mp); 2348 BUF_UNLOCK(bp); 2349 } 2350 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2351 mtx_unlock(&bqlock); 2352 free(sentinel, M_TEMP); 2353 return (flushed); 2354 } 2355 2356 /* 2357 * Check to see if a block is currently memory resident. 2358 */ 2359 struct buf * 2360 incore(struct bufobj *bo, daddr_t blkno) 2361 { 2362 struct buf *bp; 2363 2364 BO_LOCK(bo); 2365 bp = gbincore(bo, blkno); 2366 BO_UNLOCK(bo); 2367 return (bp); 2368 } 2369 2370 /* 2371 * Returns true if no I/O is needed to access the 2372 * associated VM object. This is like incore except 2373 * it also hunts around in the VM system for the data. 2374 */ 2375 2376 static int 2377 inmem(struct vnode * vp, daddr_t blkno) 2378 { 2379 vm_object_t obj; 2380 vm_offset_t toff, tinc, size; 2381 vm_page_t m; 2382 vm_ooffset_t off; 2383 2384 ASSERT_VOP_LOCKED(vp, "inmem"); 2385 2386 if (incore(&vp->v_bufobj, blkno)) 2387 return 1; 2388 if (vp->v_mount == NULL) 2389 return 0; 2390 obj = vp->v_object; 2391 if (obj == NULL) 2392 return (0); 2393 2394 size = PAGE_SIZE; 2395 if (size > vp->v_mount->mnt_stat.f_iosize) 2396 size = vp->v_mount->mnt_stat.f_iosize; 2397 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2398 2399 VM_OBJECT_LOCK(obj); 2400 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2401 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2402 if (!m) 2403 goto notinmem; 2404 tinc = size; 2405 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2406 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2407 if (vm_page_is_valid(m, 2408 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2409 goto notinmem; 2410 } 2411 VM_OBJECT_UNLOCK(obj); 2412 return 1; 2413 2414 notinmem: 2415 VM_OBJECT_UNLOCK(obj); 2416 return (0); 2417 } 2418 2419 /* 2420 * Set the dirty range for a buffer based on the status of the dirty 2421 * bits in the pages comprising the buffer. The range is limited 2422 * to the size of the buffer. 2423 * 2424 * Tell the VM system that the pages associated with this buffer 2425 * are clean. This is used for delayed writes where the data is 2426 * going to go to disk eventually without additional VM intevention. 2427 * 2428 * Note that while we only really need to clean through to b_bcount, we 2429 * just go ahead and clean through to b_bufsize. 2430 */ 2431 static void 2432 vfs_clean_pages_dirty_buf(struct buf *bp) 2433 { 2434 vm_ooffset_t foff, noff, eoff; 2435 vm_page_t m; 2436 int i; 2437 2438 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2439 return; 2440 2441 foff = bp->b_offset; 2442 KASSERT(bp->b_offset != NOOFFSET, 2443 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2444 2445 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2446 vfs_drain_busy_pages(bp); 2447 vfs_setdirty_locked_object(bp); 2448 for (i = 0; i < bp->b_npages; i++) { 2449 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2450 eoff = noff; 2451 if (eoff > bp->b_offset + bp->b_bufsize) 2452 eoff = bp->b_offset + bp->b_bufsize; 2453 m = bp->b_pages[i]; 2454 vfs_page_set_validclean(bp, foff, m); 2455 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2456 foff = noff; 2457 } 2458 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2459 } 2460 2461 static void 2462 vfs_setdirty_locked_object(struct buf *bp) 2463 { 2464 vm_object_t object; 2465 int i; 2466 2467 object = bp->b_bufobj->bo_object; 2468 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2469 2470 /* 2471 * We qualify the scan for modified pages on whether the 2472 * object has been flushed yet. 2473 */ 2474 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2475 vm_offset_t boffset; 2476 vm_offset_t eoffset; 2477 2478 /* 2479 * test the pages to see if they have been modified directly 2480 * by users through the VM system. 2481 */ 2482 for (i = 0; i < bp->b_npages; i++) 2483 vm_page_test_dirty(bp->b_pages[i]); 2484 2485 /* 2486 * Calculate the encompassing dirty range, boffset and eoffset, 2487 * (eoffset - boffset) bytes. 2488 */ 2489 2490 for (i = 0; i < bp->b_npages; i++) { 2491 if (bp->b_pages[i]->dirty) 2492 break; 2493 } 2494 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2495 2496 for (i = bp->b_npages - 1; i >= 0; --i) { 2497 if (bp->b_pages[i]->dirty) { 2498 break; 2499 } 2500 } 2501 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2502 2503 /* 2504 * Fit it to the buffer. 2505 */ 2506 2507 if (eoffset > bp->b_bcount) 2508 eoffset = bp->b_bcount; 2509 2510 /* 2511 * If we have a good dirty range, merge with the existing 2512 * dirty range. 2513 */ 2514 2515 if (boffset < eoffset) { 2516 if (bp->b_dirtyoff > boffset) 2517 bp->b_dirtyoff = boffset; 2518 if (bp->b_dirtyend < eoffset) 2519 bp->b_dirtyend = eoffset; 2520 } 2521 } 2522 } 2523 2524 /* 2525 * getblk: 2526 * 2527 * Get a block given a specified block and offset into a file/device. 2528 * The buffers B_DONE bit will be cleared on return, making it almost 2529 * ready for an I/O initiation. B_INVAL may or may not be set on 2530 * return. The caller should clear B_INVAL prior to initiating a 2531 * READ. 2532 * 2533 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2534 * an existing buffer. 2535 * 2536 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2537 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2538 * and then cleared based on the backing VM. If the previous buffer is 2539 * non-0-sized but invalid, B_CACHE will be cleared. 2540 * 2541 * If getblk() must create a new buffer, the new buffer is returned with 2542 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2543 * case it is returned with B_INVAL clear and B_CACHE set based on the 2544 * backing VM. 2545 * 2546 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2547 * B_CACHE bit is clear. 2548 * 2549 * What this means, basically, is that the caller should use B_CACHE to 2550 * determine whether the buffer is fully valid or not and should clear 2551 * B_INVAL prior to issuing a read. If the caller intends to validate 2552 * the buffer by loading its data area with something, the caller needs 2553 * to clear B_INVAL. If the caller does this without issuing an I/O, 2554 * the caller should set B_CACHE ( as an optimization ), else the caller 2555 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2556 * a write attempt or if it was a successfull read. If the caller 2557 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2558 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2559 */ 2560 struct buf * 2561 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2562 int flags) 2563 { 2564 struct buf *bp; 2565 struct bufobj *bo; 2566 int error; 2567 2568 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2569 ASSERT_VOP_LOCKED(vp, "getblk"); 2570 if (size > MAXBSIZE) 2571 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2572 2573 bo = &vp->v_bufobj; 2574 loop: 2575 /* 2576 * Block if we are low on buffers. Certain processes are allowed 2577 * to completely exhaust the buffer cache. 2578 * 2579 * If this check ever becomes a bottleneck it may be better to 2580 * move it into the else, when gbincore() fails. At the moment 2581 * it isn't a problem. 2582 * 2583 * XXX remove if 0 sections (clean this up after its proven) 2584 */ 2585 if (numfreebuffers == 0) { 2586 if (TD_IS_IDLETHREAD(curthread)) 2587 return NULL; 2588 mtx_lock(&nblock); 2589 needsbuffer |= VFS_BIO_NEED_ANY; 2590 mtx_unlock(&nblock); 2591 } 2592 2593 BO_LOCK(bo); 2594 bp = gbincore(bo, blkno); 2595 if (bp != NULL) { 2596 int lockflags; 2597 /* 2598 * Buffer is in-core. If the buffer is not busy, it must 2599 * be on a queue. 2600 */ 2601 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2602 2603 if (flags & GB_LOCK_NOWAIT) 2604 lockflags |= LK_NOWAIT; 2605 2606 error = BUF_TIMELOCK(bp, lockflags, 2607 BO_MTX(bo), "getblk", slpflag, slptimeo); 2608 2609 /* 2610 * If we slept and got the lock we have to restart in case 2611 * the buffer changed identities. 2612 */ 2613 if (error == ENOLCK) 2614 goto loop; 2615 /* We timed out or were interrupted. */ 2616 else if (error) 2617 return (NULL); 2618 2619 /* 2620 * The buffer is locked. B_CACHE is cleared if the buffer is 2621 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2622 * and for a VMIO buffer B_CACHE is adjusted according to the 2623 * backing VM cache. 2624 */ 2625 if (bp->b_flags & B_INVAL) 2626 bp->b_flags &= ~B_CACHE; 2627 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2628 bp->b_flags |= B_CACHE; 2629 bremfree(bp); 2630 2631 /* 2632 * check for size inconsistancies for non-VMIO case. 2633 */ 2634 2635 if (bp->b_bcount != size) { 2636 if ((bp->b_flags & B_VMIO) == 0 || 2637 (size > bp->b_kvasize)) { 2638 if (bp->b_flags & B_DELWRI) { 2639 /* 2640 * If buffer is pinned and caller does 2641 * not want sleep waiting for it to be 2642 * unpinned, bail out 2643 * */ 2644 if (bp->b_pin_count > 0) { 2645 if (flags & GB_LOCK_NOWAIT) { 2646 bqrelse(bp); 2647 return (NULL); 2648 } else { 2649 bunpin_wait(bp); 2650 } 2651 } 2652 bp->b_flags |= B_NOCACHE; 2653 bwrite(bp); 2654 } else { 2655 if (LIST_EMPTY(&bp->b_dep)) { 2656 bp->b_flags |= B_RELBUF; 2657 brelse(bp); 2658 } else { 2659 bp->b_flags |= B_NOCACHE; 2660 bwrite(bp); 2661 } 2662 } 2663 goto loop; 2664 } 2665 } 2666 2667 /* 2668 * If the size is inconsistant in the VMIO case, we can resize 2669 * the buffer. This might lead to B_CACHE getting set or 2670 * cleared. If the size has not changed, B_CACHE remains 2671 * unchanged from its previous state. 2672 */ 2673 2674 if (bp->b_bcount != size) 2675 allocbuf(bp, size); 2676 2677 KASSERT(bp->b_offset != NOOFFSET, 2678 ("getblk: no buffer offset")); 2679 2680 /* 2681 * A buffer with B_DELWRI set and B_CACHE clear must 2682 * be committed before we can return the buffer in 2683 * order to prevent the caller from issuing a read 2684 * ( due to B_CACHE not being set ) and overwriting 2685 * it. 2686 * 2687 * Most callers, including NFS and FFS, need this to 2688 * operate properly either because they assume they 2689 * can issue a read if B_CACHE is not set, or because 2690 * ( for example ) an uncached B_DELWRI might loop due 2691 * to softupdates re-dirtying the buffer. In the latter 2692 * case, B_CACHE is set after the first write completes, 2693 * preventing further loops. 2694 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2695 * above while extending the buffer, we cannot allow the 2696 * buffer to remain with B_CACHE set after the write 2697 * completes or it will represent a corrupt state. To 2698 * deal with this we set B_NOCACHE to scrap the buffer 2699 * after the write. 2700 * 2701 * We might be able to do something fancy, like setting 2702 * B_CACHE in bwrite() except if B_DELWRI is already set, 2703 * so the below call doesn't set B_CACHE, but that gets real 2704 * confusing. This is much easier. 2705 */ 2706 2707 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2708 bp->b_flags |= B_NOCACHE; 2709 bwrite(bp); 2710 goto loop; 2711 } 2712 bp->b_flags &= ~B_DONE; 2713 } else { 2714 int bsize, maxsize, vmio; 2715 off_t offset; 2716 2717 /* 2718 * Buffer is not in-core, create new buffer. The buffer 2719 * returned by getnewbuf() is locked. Note that the returned 2720 * buffer is also considered valid (not marked B_INVAL). 2721 */ 2722 BO_UNLOCK(bo); 2723 /* 2724 * If the user does not want us to create the buffer, bail out 2725 * here. 2726 */ 2727 if (flags & GB_NOCREAT) 2728 return NULL; 2729 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 2730 offset = blkno * bsize; 2731 vmio = vp->v_object != NULL; 2732 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2733 maxsize = imax(maxsize, bsize); 2734 2735 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2736 if (bp == NULL) { 2737 if (slpflag || slptimeo) 2738 return NULL; 2739 goto loop; 2740 } 2741 2742 /* 2743 * This code is used to make sure that a buffer is not 2744 * created while the getnewbuf routine is blocked. 2745 * This can be a problem whether the vnode is locked or not. 2746 * If the buffer is created out from under us, we have to 2747 * throw away the one we just created. 2748 * 2749 * Note: this must occur before we associate the buffer 2750 * with the vp especially considering limitations in 2751 * the splay tree implementation when dealing with duplicate 2752 * lblkno's. 2753 */ 2754 BO_LOCK(bo); 2755 if (gbincore(bo, blkno)) { 2756 BO_UNLOCK(bo); 2757 bp->b_flags |= B_INVAL; 2758 brelse(bp); 2759 goto loop; 2760 } 2761 2762 /* 2763 * Insert the buffer into the hash, so that it can 2764 * be found by incore. 2765 */ 2766 bp->b_blkno = bp->b_lblkno = blkno; 2767 bp->b_offset = offset; 2768 bgetvp(vp, bp); 2769 BO_UNLOCK(bo); 2770 2771 /* 2772 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2773 * buffer size starts out as 0, B_CACHE will be set by 2774 * allocbuf() for the VMIO case prior to it testing the 2775 * backing store for validity. 2776 */ 2777 2778 if (vmio) { 2779 bp->b_flags |= B_VMIO; 2780 #if defined(VFS_BIO_DEBUG) 2781 if (vn_canvmio(vp) != TRUE) 2782 printf("getblk: VMIO on vnode type %d\n", 2783 vp->v_type); 2784 #endif 2785 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2786 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2787 bp, vp->v_object, bp->b_bufobj->bo_object)); 2788 } else { 2789 bp->b_flags &= ~B_VMIO; 2790 KASSERT(bp->b_bufobj->bo_object == NULL, 2791 ("ARGH! has b_bufobj->bo_object %p %p\n", 2792 bp, bp->b_bufobj->bo_object)); 2793 } 2794 2795 allocbuf(bp, size); 2796 bp->b_flags &= ~B_DONE; 2797 } 2798 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2799 BUF_ASSERT_HELD(bp); 2800 KASSERT(bp->b_bufobj == bo, 2801 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2802 return (bp); 2803 } 2804 2805 /* 2806 * Get an empty, disassociated buffer of given size. The buffer is initially 2807 * set to B_INVAL. 2808 */ 2809 struct buf * 2810 geteblk(int size, int flags) 2811 { 2812 struct buf *bp; 2813 int maxsize; 2814 2815 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2816 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2817 if ((flags & GB_NOWAIT_BD) && 2818 (curthread->td_pflags & TDP_BUFNEED) != 0) 2819 return (NULL); 2820 } 2821 allocbuf(bp, size); 2822 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2823 BUF_ASSERT_HELD(bp); 2824 return (bp); 2825 } 2826 2827 2828 /* 2829 * This code constitutes the buffer memory from either anonymous system 2830 * memory (in the case of non-VMIO operations) or from an associated 2831 * VM object (in the case of VMIO operations). This code is able to 2832 * resize a buffer up or down. 2833 * 2834 * Note that this code is tricky, and has many complications to resolve 2835 * deadlock or inconsistant data situations. Tread lightly!!! 2836 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2837 * the caller. Calling this code willy nilly can result in the loss of data. 2838 * 2839 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2840 * B_CACHE for the non-VMIO case. 2841 */ 2842 2843 int 2844 allocbuf(struct buf *bp, int size) 2845 { 2846 int newbsize, mbsize; 2847 int i; 2848 2849 BUF_ASSERT_HELD(bp); 2850 2851 if (bp->b_kvasize < size) 2852 panic("allocbuf: buffer too small"); 2853 2854 if ((bp->b_flags & B_VMIO) == 0) { 2855 caddr_t origbuf; 2856 int origbufsize; 2857 /* 2858 * Just get anonymous memory from the kernel. Don't 2859 * mess with B_CACHE. 2860 */ 2861 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2862 if (bp->b_flags & B_MALLOC) 2863 newbsize = mbsize; 2864 else 2865 newbsize = round_page(size); 2866 2867 if (newbsize < bp->b_bufsize) { 2868 /* 2869 * malloced buffers are not shrunk 2870 */ 2871 if (bp->b_flags & B_MALLOC) { 2872 if (newbsize) { 2873 bp->b_bcount = size; 2874 } else { 2875 free(bp->b_data, M_BIOBUF); 2876 if (bp->b_bufsize) { 2877 atomic_subtract_long( 2878 &bufmallocspace, 2879 bp->b_bufsize); 2880 bufspacewakeup(); 2881 bp->b_bufsize = 0; 2882 } 2883 bp->b_saveaddr = bp->b_kvabase; 2884 bp->b_data = bp->b_saveaddr; 2885 bp->b_bcount = 0; 2886 bp->b_flags &= ~B_MALLOC; 2887 } 2888 return 1; 2889 } 2890 vm_hold_free_pages(bp, newbsize); 2891 } else if (newbsize > bp->b_bufsize) { 2892 /* 2893 * We only use malloced memory on the first allocation. 2894 * and revert to page-allocated memory when the buffer 2895 * grows. 2896 */ 2897 /* 2898 * There is a potential smp race here that could lead 2899 * to bufmallocspace slightly passing the max. It 2900 * is probably extremely rare and not worth worrying 2901 * over. 2902 */ 2903 if ( (bufmallocspace < maxbufmallocspace) && 2904 (bp->b_bufsize == 0) && 2905 (mbsize <= PAGE_SIZE/2)) { 2906 2907 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2908 bp->b_bufsize = mbsize; 2909 bp->b_bcount = size; 2910 bp->b_flags |= B_MALLOC; 2911 atomic_add_long(&bufmallocspace, mbsize); 2912 return 1; 2913 } 2914 origbuf = NULL; 2915 origbufsize = 0; 2916 /* 2917 * If the buffer is growing on its other-than-first allocation, 2918 * then we revert to the page-allocation scheme. 2919 */ 2920 if (bp->b_flags & B_MALLOC) { 2921 origbuf = bp->b_data; 2922 origbufsize = bp->b_bufsize; 2923 bp->b_data = bp->b_kvabase; 2924 if (bp->b_bufsize) { 2925 atomic_subtract_long(&bufmallocspace, 2926 bp->b_bufsize); 2927 bufspacewakeup(); 2928 bp->b_bufsize = 0; 2929 } 2930 bp->b_flags &= ~B_MALLOC; 2931 newbsize = round_page(newbsize); 2932 } 2933 vm_hold_load_pages( 2934 bp, 2935 (vm_offset_t) bp->b_data + bp->b_bufsize, 2936 (vm_offset_t) bp->b_data + newbsize); 2937 if (origbuf) { 2938 bcopy(origbuf, bp->b_data, origbufsize); 2939 free(origbuf, M_BIOBUF); 2940 } 2941 } 2942 } else { 2943 int desiredpages; 2944 2945 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2946 desiredpages = (size == 0) ? 0 : 2947 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2948 2949 if (bp->b_flags & B_MALLOC) 2950 panic("allocbuf: VMIO buffer can't be malloced"); 2951 /* 2952 * Set B_CACHE initially if buffer is 0 length or will become 2953 * 0-length. 2954 */ 2955 if (size == 0 || bp->b_bufsize == 0) 2956 bp->b_flags |= B_CACHE; 2957 2958 if (newbsize < bp->b_bufsize) { 2959 /* 2960 * DEV_BSIZE aligned new buffer size is less then the 2961 * DEV_BSIZE aligned existing buffer size. Figure out 2962 * if we have to remove any pages. 2963 */ 2964 if (desiredpages < bp->b_npages) { 2965 vm_page_t m; 2966 2967 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2968 for (i = desiredpages; i < bp->b_npages; i++) { 2969 /* 2970 * the page is not freed here -- it 2971 * is the responsibility of 2972 * vnode_pager_setsize 2973 */ 2974 m = bp->b_pages[i]; 2975 KASSERT(m != bogus_page, 2976 ("allocbuf: bogus page found")); 2977 while (vm_page_sleep_if_busy(m, TRUE, 2978 "biodep")) 2979 continue; 2980 2981 bp->b_pages[i] = NULL; 2982 vm_page_lock(m); 2983 vm_page_unwire(m, 0); 2984 vm_page_unlock(m); 2985 } 2986 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2987 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2988 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2989 bp->b_npages = desiredpages; 2990 } 2991 } else if (size > bp->b_bcount) { 2992 /* 2993 * We are growing the buffer, possibly in a 2994 * byte-granular fashion. 2995 */ 2996 vm_object_t obj; 2997 vm_offset_t toff; 2998 vm_offset_t tinc; 2999 3000 /* 3001 * Step 1, bring in the VM pages from the object, 3002 * allocating them if necessary. We must clear 3003 * B_CACHE if these pages are not valid for the 3004 * range covered by the buffer. 3005 */ 3006 3007 obj = bp->b_bufobj->bo_object; 3008 3009 VM_OBJECT_LOCK(obj); 3010 while (bp->b_npages < desiredpages) { 3011 vm_page_t m; 3012 3013 /* 3014 * We must allocate system pages since blocking 3015 * here could intefere with paging I/O, no 3016 * matter which process we are. 3017 * 3018 * We can only test VPO_BUSY here. Blocking on 3019 * m->busy might lead to a deadlock: 3020 * vm_fault->getpages->cluster_read->allocbuf 3021 * Thus, we specify VM_ALLOC_IGN_SBUSY. 3022 */ 3023 m = vm_page_grab(obj, OFF_TO_IDX(bp->b_offset) + 3024 bp->b_npages, VM_ALLOC_NOBUSY | 3025 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3026 VM_ALLOC_RETRY | VM_ALLOC_IGN_SBUSY | 3027 VM_ALLOC_COUNT(desiredpages - bp->b_npages)); 3028 if (m->valid == 0) 3029 bp->b_flags &= ~B_CACHE; 3030 bp->b_pages[bp->b_npages] = m; 3031 ++bp->b_npages; 3032 } 3033 3034 /* 3035 * Step 2. We've loaded the pages into the buffer, 3036 * we have to figure out if we can still have B_CACHE 3037 * set. Note that B_CACHE is set according to the 3038 * byte-granular range ( bcount and size ), new the 3039 * aligned range ( newbsize ). 3040 * 3041 * The VM test is against m->valid, which is DEV_BSIZE 3042 * aligned. Needless to say, the validity of the data 3043 * needs to also be DEV_BSIZE aligned. Note that this 3044 * fails with NFS if the server or some other client 3045 * extends the file's EOF. If our buffer is resized, 3046 * B_CACHE may remain set! XXX 3047 */ 3048 3049 toff = bp->b_bcount; 3050 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3051 3052 while ((bp->b_flags & B_CACHE) && toff < size) { 3053 vm_pindex_t pi; 3054 3055 if (tinc > (size - toff)) 3056 tinc = size - toff; 3057 3058 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3059 PAGE_SHIFT; 3060 3061 vfs_buf_test_cache( 3062 bp, 3063 bp->b_offset, 3064 toff, 3065 tinc, 3066 bp->b_pages[pi] 3067 ); 3068 toff += tinc; 3069 tinc = PAGE_SIZE; 3070 } 3071 VM_OBJECT_UNLOCK(obj); 3072 3073 /* 3074 * Step 3, fixup the KVM pmap. Remember that 3075 * bp->b_data is relative to bp->b_offset, but 3076 * bp->b_offset may be offset into the first page. 3077 */ 3078 3079 bp->b_data = (caddr_t) 3080 trunc_page((vm_offset_t)bp->b_data); 3081 pmap_qenter( 3082 (vm_offset_t)bp->b_data, 3083 bp->b_pages, 3084 bp->b_npages 3085 ); 3086 3087 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3088 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3089 } 3090 } 3091 if (newbsize < bp->b_bufsize) 3092 bufspacewakeup(); 3093 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3094 bp->b_bcount = size; /* requested buffer size */ 3095 return 1; 3096 } 3097 3098 void 3099 biodone(struct bio *bp) 3100 { 3101 struct mtx *mtxp; 3102 void (*done)(struct bio *); 3103 3104 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3105 mtx_lock(mtxp); 3106 bp->bio_flags |= BIO_DONE; 3107 done = bp->bio_done; 3108 if (done == NULL) 3109 wakeup(bp); 3110 mtx_unlock(mtxp); 3111 if (done != NULL) 3112 done(bp); 3113 } 3114 3115 /* 3116 * Wait for a BIO to finish. 3117 * 3118 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3119 * case is not yet clear. 3120 */ 3121 int 3122 biowait(struct bio *bp, const char *wchan) 3123 { 3124 struct mtx *mtxp; 3125 3126 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3127 mtx_lock(mtxp); 3128 while ((bp->bio_flags & BIO_DONE) == 0) 3129 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3130 mtx_unlock(mtxp); 3131 if (bp->bio_error != 0) 3132 return (bp->bio_error); 3133 if (!(bp->bio_flags & BIO_ERROR)) 3134 return (0); 3135 return (EIO); 3136 } 3137 3138 void 3139 biofinish(struct bio *bp, struct devstat *stat, int error) 3140 { 3141 3142 if (error) { 3143 bp->bio_error = error; 3144 bp->bio_flags |= BIO_ERROR; 3145 } 3146 if (stat != NULL) 3147 devstat_end_transaction_bio(stat, bp); 3148 biodone(bp); 3149 } 3150 3151 /* 3152 * bufwait: 3153 * 3154 * Wait for buffer I/O completion, returning error status. The buffer 3155 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3156 * error and cleared. 3157 */ 3158 int 3159 bufwait(struct buf *bp) 3160 { 3161 if (bp->b_iocmd == BIO_READ) 3162 bwait(bp, PRIBIO, "biord"); 3163 else 3164 bwait(bp, PRIBIO, "biowr"); 3165 if (bp->b_flags & B_EINTR) { 3166 bp->b_flags &= ~B_EINTR; 3167 return (EINTR); 3168 } 3169 if (bp->b_ioflags & BIO_ERROR) { 3170 return (bp->b_error ? bp->b_error : EIO); 3171 } else { 3172 return (0); 3173 } 3174 } 3175 3176 /* 3177 * Call back function from struct bio back up to struct buf. 3178 */ 3179 static void 3180 bufdonebio(struct bio *bip) 3181 { 3182 struct buf *bp; 3183 3184 bp = bip->bio_caller2; 3185 bp->b_resid = bp->b_bcount - bip->bio_completed; 3186 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3187 bp->b_ioflags = bip->bio_flags; 3188 bp->b_error = bip->bio_error; 3189 if (bp->b_error) 3190 bp->b_ioflags |= BIO_ERROR; 3191 bufdone(bp); 3192 g_destroy_bio(bip); 3193 } 3194 3195 void 3196 dev_strategy(struct cdev *dev, struct buf *bp) 3197 { 3198 struct cdevsw *csw; 3199 struct bio *bip; 3200 3201 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3202 panic("b_iocmd botch"); 3203 for (;;) { 3204 bip = g_new_bio(); 3205 if (bip != NULL) 3206 break; 3207 /* Try again later */ 3208 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3209 } 3210 bip->bio_cmd = bp->b_iocmd; 3211 bip->bio_offset = bp->b_iooffset; 3212 bip->bio_length = bp->b_bcount; 3213 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3214 bip->bio_data = bp->b_data; 3215 bip->bio_done = bufdonebio; 3216 bip->bio_caller2 = bp; 3217 bip->bio_dev = dev; 3218 KASSERT(dev->si_refcount > 0, 3219 ("dev_strategy on un-referenced struct cdev *(%s)", 3220 devtoname(dev))); 3221 csw = dev_refthread(dev); 3222 if (csw == NULL) { 3223 g_destroy_bio(bip); 3224 bp->b_error = ENXIO; 3225 bp->b_ioflags = BIO_ERROR; 3226 bufdone(bp); 3227 return; 3228 } 3229 (*csw->d_strategy)(bip); 3230 dev_relthread(dev); 3231 } 3232 3233 /* 3234 * bufdone: 3235 * 3236 * Finish I/O on a buffer, optionally calling a completion function. 3237 * This is usually called from an interrupt so process blocking is 3238 * not allowed. 3239 * 3240 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3241 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3242 * assuming B_INVAL is clear. 3243 * 3244 * For the VMIO case, we set B_CACHE if the op was a read and no 3245 * read error occured, or if the op was a write. B_CACHE is never 3246 * set if the buffer is invalid or otherwise uncacheable. 3247 * 3248 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3249 * initiator to leave B_INVAL set to brelse the buffer out of existance 3250 * in the biodone routine. 3251 */ 3252 void 3253 bufdone(struct buf *bp) 3254 { 3255 struct bufobj *dropobj; 3256 void (*biodone)(struct buf *); 3257 3258 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3259 dropobj = NULL; 3260 3261 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3262 BUF_ASSERT_HELD(bp); 3263 3264 runningbufwakeup(bp); 3265 if (bp->b_iocmd == BIO_WRITE) 3266 dropobj = bp->b_bufobj; 3267 /* call optional completion function if requested */ 3268 if (bp->b_iodone != NULL) { 3269 biodone = bp->b_iodone; 3270 bp->b_iodone = NULL; 3271 (*biodone) (bp); 3272 if (dropobj) 3273 bufobj_wdrop(dropobj); 3274 return; 3275 } 3276 3277 bufdone_finish(bp); 3278 3279 if (dropobj) 3280 bufobj_wdrop(dropobj); 3281 } 3282 3283 void 3284 bufdone_finish(struct buf *bp) 3285 { 3286 BUF_ASSERT_HELD(bp); 3287 3288 if (!LIST_EMPTY(&bp->b_dep)) 3289 buf_complete(bp); 3290 3291 if (bp->b_flags & B_VMIO) { 3292 int i; 3293 vm_ooffset_t foff; 3294 vm_page_t m; 3295 vm_object_t obj; 3296 int bogus, iosize; 3297 struct vnode *vp = bp->b_vp; 3298 3299 obj = bp->b_bufobj->bo_object; 3300 3301 #if defined(VFS_BIO_DEBUG) 3302 mp_fixme("usecount and vflag accessed without locks."); 3303 if (vp->v_usecount == 0) { 3304 panic("biodone: zero vnode ref count"); 3305 } 3306 3307 KASSERT(vp->v_object != NULL, 3308 ("biodone: vnode %p has no vm_object", vp)); 3309 #endif 3310 3311 foff = bp->b_offset; 3312 KASSERT(bp->b_offset != NOOFFSET, 3313 ("biodone: no buffer offset")); 3314 3315 VM_OBJECT_LOCK(obj); 3316 #if defined(VFS_BIO_DEBUG) 3317 if (obj->paging_in_progress < bp->b_npages) { 3318 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3319 obj->paging_in_progress, bp->b_npages); 3320 } 3321 #endif 3322 3323 /* 3324 * Set B_CACHE if the op was a normal read and no error 3325 * occured. B_CACHE is set for writes in the b*write() 3326 * routines. 3327 */ 3328 iosize = bp->b_bcount - bp->b_resid; 3329 if (bp->b_iocmd == BIO_READ && 3330 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3331 !(bp->b_ioflags & BIO_ERROR)) { 3332 bp->b_flags |= B_CACHE; 3333 } 3334 bogus = 0; 3335 for (i = 0; i < bp->b_npages; i++) { 3336 int bogusflag = 0; 3337 int resid; 3338 3339 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3340 if (resid > iosize) 3341 resid = iosize; 3342 3343 /* 3344 * cleanup bogus pages, restoring the originals 3345 */ 3346 m = bp->b_pages[i]; 3347 if (m == bogus_page) { 3348 bogus = bogusflag = 1; 3349 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3350 if (m == NULL) 3351 panic("biodone: page disappeared!"); 3352 bp->b_pages[i] = m; 3353 } 3354 #if defined(VFS_BIO_DEBUG) 3355 if (OFF_TO_IDX(foff) != m->pindex) { 3356 printf( 3357 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3358 (intmax_t)foff, (uintmax_t)m->pindex); 3359 } 3360 #endif 3361 3362 /* 3363 * In the write case, the valid and clean bits are 3364 * already changed correctly ( see bdwrite() ), so we 3365 * only need to do this here in the read case. 3366 */ 3367 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3368 KASSERT((m->dirty & vm_page_bits(foff & 3369 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3370 " page %p has unexpected dirty bits", m)); 3371 vfs_page_set_valid(bp, foff, m); 3372 } 3373 3374 /* 3375 * when debugging new filesystems or buffer I/O methods, this 3376 * is the most common error that pops up. if you see this, you 3377 * have not set the page busy flag correctly!!! 3378 */ 3379 if (m->busy == 0) { 3380 printf("biodone: page busy < 0, " 3381 "pindex: %d, foff: 0x(%x,%x), " 3382 "resid: %d, index: %d\n", 3383 (int) m->pindex, (int)(foff >> 32), 3384 (int) foff & 0xffffffff, resid, i); 3385 if (!vn_isdisk(vp, NULL)) 3386 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3387 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3388 (intmax_t) bp->b_lblkno, 3389 bp->b_flags, bp->b_npages); 3390 else 3391 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3392 (intmax_t) bp->b_lblkno, 3393 bp->b_flags, bp->b_npages); 3394 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3395 (u_long)m->valid, (u_long)m->dirty, 3396 m->wire_count); 3397 panic("biodone: page busy < 0\n"); 3398 } 3399 vm_page_io_finish(m); 3400 vm_object_pip_subtract(obj, 1); 3401 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3402 iosize -= resid; 3403 } 3404 vm_object_pip_wakeupn(obj, 0); 3405 VM_OBJECT_UNLOCK(obj); 3406 if (bogus) 3407 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3408 bp->b_pages, bp->b_npages); 3409 } 3410 3411 /* 3412 * For asynchronous completions, release the buffer now. The brelse 3413 * will do a wakeup there if necessary - so no need to do a wakeup 3414 * here in the async case. The sync case always needs to do a wakeup. 3415 */ 3416 3417 if (bp->b_flags & B_ASYNC) { 3418 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3419 brelse(bp); 3420 else 3421 bqrelse(bp); 3422 } else 3423 bdone(bp); 3424 } 3425 3426 /* 3427 * This routine is called in lieu of iodone in the case of 3428 * incomplete I/O. This keeps the busy status for pages 3429 * consistant. 3430 */ 3431 void 3432 vfs_unbusy_pages(struct buf *bp) 3433 { 3434 int i; 3435 vm_object_t obj; 3436 vm_page_t m; 3437 3438 runningbufwakeup(bp); 3439 if (!(bp->b_flags & B_VMIO)) 3440 return; 3441 3442 obj = bp->b_bufobj->bo_object; 3443 VM_OBJECT_LOCK(obj); 3444 for (i = 0; i < bp->b_npages; i++) { 3445 m = bp->b_pages[i]; 3446 if (m == bogus_page) { 3447 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3448 if (!m) 3449 panic("vfs_unbusy_pages: page missing\n"); 3450 bp->b_pages[i] = m; 3451 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3452 bp->b_pages, bp->b_npages); 3453 } 3454 vm_object_pip_subtract(obj, 1); 3455 vm_page_io_finish(m); 3456 } 3457 vm_object_pip_wakeupn(obj, 0); 3458 VM_OBJECT_UNLOCK(obj); 3459 } 3460 3461 /* 3462 * vfs_page_set_valid: 3463 * 3464 * Set the valid bits in a page based on the supplied offset. The 3465 * range is restricted to the buffer's size. 3466 * 3467 * This routine is typically called after a read completes. 3468 */ 3469 static void 3470 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3471 { 3472 vm_ooffset_t eoff; 3473 3474 /* 3475 * Compute the end offset, eoff, such that [off, eoff) does not span a 3476 * page boundary and eoff is not greater than the end of the buffer. 3477 * The end of the buffer, in this case, is our file EOF, not the 3478 * allocation size of the buffer. 3479 */ 3480 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3481 if (eoff > bp->b_offset + bp->b_bcount) 3482 eoff = bp->b_offset + bp->b_bcount; 3483 3484 /* 3485 * Set valid range. This is typically the entire buffer and thus the 3486 * entire page. 3487 */ 3488 if (eoff > off) 3489 vm_page_set_valid(m, off & PAGE_MASK, eoff - off); 3490 } 3491 3492 /* 3493 * vfs_page_set_validclean: 3494 * 3495 * Set the valid bits and clear the dirty bits in a page based on the 3496 * supplied offset. The range is restricted to the buffer's size. 3497 */ 3498 static void 3499 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3500 { 3501 vm_ooffset_t soff, eoff; 3502 3503 /* 3504 * Start and end offsets in buffer. eoff - soff may not cross a 3505 * page boundry or cross the end of the buffer. The end of the 3506 * buffer, in this case, is our file EOF, not the allocation size 3507 * of the buffer. 3508 */ 3509 soff = off; 3510 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3511 if (eoff > bp->b_offset + bp->b_bcount) 3512 eoff = bp->b_offset + bp->b_bcount; 3513 3514 /* 3515 * Set valid range. This is typically the entire buffer and thus the 3516 * entire page. 3517 */ 3518 if (eoff > soff) { 3519 vm_page_set_validclean( 3520 m, 3521 (vm_offset_t) (soff & PAGE_MASK), 3522 (vm_offset_t) (eoff - soff) 3523 ); 3524 } 3525 } 3526 3527 /* 3528 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3529 * any page is busy, drain the flag. 3530 */ 3531 static void 3532 vfs_drain_busy_pages(struct buf *bp) 3533 { 3534 vm_page_t m; 3535 int i, last_busied; 3536 3537 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED); 3538 last_busied = 0; 3539 for (i = 0; i < bp->b_npages; i++) { 3540 m = bp->b_pages[i]; 3541 if ((m->oflags & VPO_BUSY) != 0) { 3542 for (; last_busied < i; last_busied++) 3543 vm_page_busy(bp->b_pages[last_busied]); 3544 while ((m->oflags & VPO_BUSY) != 0) 3545 vm_page_sleep(m, "vbpage"); 3546 } 3547 } 3548 for (i = 0; i < last_busied; i++) 3549 vm_page_wakeup(bp->b_pages[i]); 3550 } 3551 3552 /* 3553 * This routine is called before a device strategy routine. 3554 * It is used to tell the VM system that paging I/O is in 3555 * progress, and treat the pages associated with the buffer 3556 * almost as being VPO_BUSY. Also the object paging_in_progress 3557 * flag is handled to make sure that the object doesn't become 3558 * inconsistant. 3559 * 3560 * Since I/O has not been initiated yet, certain buffer flags 3561 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3562 * and should be ignored. 3563 */ 3564 void 3565 vfs_busy_pages(struct buf *bp, int clear_modify) 3566 { 3567 int i, bogus; 3568 vm_object_t obj; 3569 vm_ooffset_t foff; 3570 vm_page_t m; 3571 3572 if (!(bp->b_flags & B_VMIO)) 3573 return; 3574 3575 obj = bp->b_bufobj->bo_object; 3576 foff = bp->b_offset; 3577 KASSERT(bp->b_offset != NOOFFSET, 3578 ("vfs_busy_pages: no buffer offset")); 3579 VM_OBJECT_LOCK(obj); 3580 vfs_drain_busy_pages(bp); 3581 if (bp->b_bufsize != 0) 3582 vfs_setdirty_locked_object(bp); 3583 bogus = 0; 3584 for (i = 0; i < bp->b_npages; i++) { 3585 m = bp->b_pages[i]; 3586 3587 if ((bp->b_flags & B_CLUSTER) == 0) { 3588 vm_object_pip_add(obj, 1); 3589 vm_page_io_start(m); 3590 } 3591 /* 3592 * When readying a buffer for a read ( i.e 3593 * clear_modify == 0 ), it is important to do 3594 * bogus_page replacement for valid pages in 3595 * partially instantiated buffers. Partially 3596 * instantiated buffers can, in turn, occur when 3597 * reconstituting a buffer from its VM backing store 3598 * base. We only have to do this if B_CACHE is 3599 * clear ( which causes the I/O to occur in the 3600 * first place ). The replacement prevents the read 3601 * I/O from overwriting potentially dirty VM-backed 3602 * pages. XXX bogus page replacement is, uh, bogus. 3603 * It may not work properly with small-block devices. 3604 * We need to find a better way. 3605 */ 3606 if (clear_modify) { 3607 pmap_remove_write(m); 3608 vfs_page_set_validclean(bp, foff, m); 3609 } else if (m->valid == VM_PAGE_BITS_ALL && 3610 (bp->b_flags & B_CACHE) == 0) { 3611 bp->b_pages[i] = bogus_page; 3612 bogus++; 3613 } 3614 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3615 } 3616 VM_OBJECT_UNLOCK(obj); 3617 if (bogus) 3618 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3619 bp->b_pages, bp->b_npages); 3620 } 3621 3622 /* 3623 * vfs_bio_set_valid: 3624 * 3625 * Set the range within the buffer to valid. The range is 3626 * relative to the beginning of the buffer, b_offset. Note that 3627 * b_offset itself may be offset from the beginning of the first 3628 * page. 3629 */ 3630 void 3631 vfs_bio_set_valid(struct buf *bp, int base, int size) 3632 { 3633 int i, n; 3634 vm_page_t m; 3635 3636 if (!(bp->b_flags & B_VMIO)) 3637 return; 3638 3639 /* 3640 * Fixup base to be relative to beginning of first page. 3641 * Set initial n to be the maximum number of bytes in the 3642 * first page that can be validated. 3643 */ 3644 base += (bp->b_offset & PAGE_MASK); 3645 n = PAGE_SIZE - (base & PAGE_MASK); 3646 3647 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3648 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3649 m = bp->b_pages[i]; 3650 if (n > size) 3651 n = size; 3652 vm_page_set_valid(m, base & PAGE_MASK, n); 3653 base += n; 3654 size -= n; 3655 n = PAGE_SIZE; 3656 } 3657 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3658 } 3659 3660 /* 3661 * vfs_bio_clrbuf: 3662 * 3663 * If the specified buffer is a non-VMIO buffer, clear the entire 3664 * buffer. If the specified buffer is a VMIO buffer, clear and 3665 * validate only the previously invalid portions of the buffer. 3666 * This routine essentially fakes an I/O, so we need to clear 3667 * BIO_ERROR and B_INVAL. 3668 * 3669 * Note that while we only theoretically need to clear through b_bcount, 3670 * we go ahead and clear through b_bufsize. 3671 */ 3672 void 3673 vfs_bio_clrbuf(struct buf *bp) 3674 { 3675 int i, j, mask; 3676 caddr_t sa, ea; 3677 3678 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3679 clrbuf(bp); 3680 return; 3681 } 3682 bp->b_flags &= ~B_INVAL; 3683 bp->b_ioflags &= ~BIO_ERROR; 3684 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3685 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3686 (bp->b_offset & PAGE_MASK) == 0) { 3687 if (bp->b_pages[0] == bogus_page) 3688 goto unlock; 3689 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3690 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3691 if ((bp->b_pages[0]->valid & mask) == mask) 3692 goto unlock; 3693 if ((bp->b_pages[0]->valid & mask) == 0) { 3694 bzero(bp->b_data, bp->b_bufsize); 3695 bp->b_pages[0]->valid |= mask; 3696 goto unlock; 3697 } 3698 } 3699 ea = sa = bp->b_data; 3700 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3701 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3702 ea = (caddr_t)(vm_offset_t)ulmin( 3703 (u_long)(vm_offset_t)ea, 3704 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3705 if (bp->b_pages[i] == bogus_page) 3706 continue; 3707 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3708 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3709 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3710 if ((bp->b_pages[i]->valid & mask) == mask) 3711 continue; 3712 if ((bp->b_pages[i]->valid & mask) == 0) 3713 bzero(sa, ea - sa); 3714 else { 3715 for (; sa < ea; sa += DEV_BSIZE, j++) { 3716 if ((bp->b_pages[i]->valid & (1 << j)) == 0) 3717 bzero(sa, DEV_BSIZE); 3718 } 3719 } 3720 bp->b_pages[i]->valid |= mask; 3721 } 3722 unlock: 3723 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3724 bp->b_resid = 0; 3725 } 3726 3727 /* 3728 * vm_hold_load_pages and vm_hold_free_pages get pages into 3729 * a buffers address space. The pages are anonymous and are 3730 * not associated with a file object. 3731 */ 3732 static void 3733 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3734 { 3735 vm_offset_t pg; 3736 vm_page_t p; 3737 int index; 3738 3739 to = round_page(to); 3740 from = round_page(from); 3741 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3742 3743 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3744 tryagain: 3745 /* 3746 * note: must allocate system pages since blocking here 3747 * could interfere with paging I/O, no matter which 3748 * process we are. 3749 */ 3750 p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ | 3751 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED | 3752 VM_ALLOC_COUNT((to - pg) >> PAGE_SHIFT)); 3753 if (!p) { 3754 VM_WAIT; 3755 goto tryagain; 3756 } 3757 pmap_qenter(pg, &p, 1); 3758 bp->b_pages[index] = p; 3759 } 3760 bp->b_npages = index; 3761 } 3762 3763 /* Return pages associated with this buf to the vm system */ 3764 static void 3765 vm_hold_free_pages(struct buf *bp, int newbsize) 3766 { 3767 vm_offset_t from; 3768 vm_page_t p; 3769 int index, newnpages; 3770 3771 from = round_page((vm_offset_t)bp->b_data + newbsize); 3772 newnpages = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3773 if (bp->b_npages > newnpages) 3774 pmap_qremove(from, bp->b_npages - newnpages); 3775 for (index = newnpages; index < bp->b_npages; index++) { 3776 p = bp->b_pages[index]; 3777 bp->b_pages[index] = NULL; 3778 if (p->busy != 0) 3779 printf("vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3780 (intmax_t)bp->b_blkno, (intmax_t)bp->b_lblkno); 3781 p->wire_count--; 3782 vm_page_free(p); 3783 atomic_subtract_int(&cnt.v_wire_count, 1); 3784 } 3785 bp->b_npages = newnpages; 3786 } 3787 3788 /* 3789 * Map an IO request into kernel virtual address space. 3790 * 3791 * All requests are (re)mapped into kernel VA space. 3792 * Notice that we use b_bufsize for the size of the buffer 3793 * to be mapped. b_bcount might be modified by the driver. 3794 * 3795 * Note that even if the caller determines that the address space should 3796 * be valid, a race or a smaller-file mapped into a larger space may 3797 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3798 * check the return value. 3799 */ 3800 int 3801 vmapbuf(struct buf *bp) 3802 { 3803 caddr_t addr, kva; 3804 vm_prot_t prot; 3805 int pidx, i; 3806 struct vm_page *m; 3807 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3808 3809 if (bp->b_bufsize < 0) 3810 return (-1); 3811 prot = VM_PROT_READ; 3812 if (bp->b_iocmd == BIO_READ) 3813 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3814 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3815 addr < bp->b_data + bp->b_bufsize; 3816 addr += PAGE_SIZE, pidx++) { 3817 /* 3818 * Do the vm_fault if needed; do the copy-on-write thing 3819 * when reading stuff off device into memory. 3820 * 3821 * NOTE! Must use pmap_extract() because addr may be in 3822 * the userland address space, and kextract is only guarenteed 3823 * to work for the kernland address space (see: sparc64 port). 3824 */ 3825 retry: 3826 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3827 prot) < 0) { 3828 for (i = 0; i < pidx; ++i) { 3829 vm_page_lock(bp->b_pages[i]); 3830 vm_page_unhold(bp->b_pages[i]); 3831 vm_page_unlock(bp->b_pages[i]); 3832 bp->b_pages[i] = NULL; 3833 } 3834 return(-1); 3835 } 3836 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3837 if (m == NULL) 3838 goto retry; 3839 bp->b_pages[pidx] = m; 3840 } 3841 if (pidx > btoc(MAXPHYS)) 3842 panic("vmapbuf: mapped more than MAXPHYS"); 3843 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3844 3845 kva = bp->b_saveaddr; 3846 bp->b_npages = pidx; 3847 bp->b_saveaddr = bp->b_data; 3848 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3849 return(0); 3850 } 3851 3852 /* 3853 * Free the io map PTEs associated with this IO operation. 3854 * We also invalidate the TLB entries and restore the original b_addr. 3855 */ 3856 void 3857 vunmapbuf(struct buf *bp) 3858 { 3859 int pidx; 3860 int npages; 3861 3862 npages = bp->b_npages; 3863 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3864 for (pidx = 0; pidx < npages; pidx++) { 3865 vm_page_lock(bp->b_pages[pidx]); 3866 vm_page_unhold(bp->b_pages[pidx]); 3867 vm_page_unlock(bp->b_pages[pidx]); 3868 } 3869 3870 bp->b_data = bp->b_saveaddr; 3871 } 3872 3873 void 3874 bdone(struct buf *bp) 3875 { 3876 struct mtx *mtxp; 3877 3878 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3879 mtx_lock(mtxp); 3880 bp->b_flags |= B_DONE; 3881 wakeup(bp); 3882 mtx_unlock(mtxp); 3883 } 3884 3885 void 3886 bwait(struct buf *bp, u_char pri, const char *wchan) 3887 { 3888 struct mtx *mtxp; 3889 3890 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3891 mtx_lock(mtxp); 3892 while ((bp->b_flags & B_DONE) == 0) 3893 msleep(bp, mtxp, pri, wchan, 0); 3894 mtx_unlock(mtxp); 3895 } 3896 3897 int 3898 bufsync(struct bufobj *bo, int waitfor) 3899 { 3900 3901 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3902 } 3903 3904 void 3905 bufstrategy(struct bufobj *bo, struct buf *bp) 3906 { 3907 int i = 0; 3908 struct vnode *vp; 3909 3910 vp = bp->b_vp; 3911 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3912 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3913 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3914 i = VOP_STRATEGY(vp, bp); 3915 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3916 } 3917 3918 void 3919 bufobj_wrefl(struct bufobj *bo) 3920 { 3921 3922 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3923 ASSERT_BO_LOCKED(bo); 3924 bo->bo_numoutput++; 3925 } 3926 3927 void 3928 bufobj_wref(struct bufobj *bo) 3929 { 3930 3931 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3932 BO_LOCK(bo); 3933 bo->bo_numoutput++; 3934 BO_UNLOCK(bo); 3935 } 3936 3937 void 3938 bufobj_wdrop(struct bufobj *bo) 3939 { 3940 3941 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3942 BO_LOCK(bo); 3943 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3944 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3945 bo->bo_flag &= ~BO_WWAIT; 3946 wakeup(&bo->bo_numoutput); 3947 } 3948 BO_UNLOCK(bo); 3949 } 3950 3951 int 3952 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3953 { 3954 int error; 3955 3956 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3957 ASSERT_BO_LOCKED(bo); 3958 error = 0; 3959 while (bo->bo_numoutput) { 3960 bo->bo_flag |= BO_WWAIT; 3961 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3962 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3963 if (error) 3964 break; 3965 } 3966 return (error); 3967 } 3968 3969 void 3970 bpin(struct buf *bp) 3971 { 3972 struct mtx *mtxp; 3973 3974 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3975 mtx_lock(mtxp); 3976 bp->b_pin_count++; 3977 mtx_unlock(mtxp); 3978 } 3979 3980 void 3981 bunpin(struct buf *bp) 3982 { 3983 struct mtx *mtxp; 3984 3985 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3986 mtx_lock(mtxp); 3987 if (--bp->b_pin_count == 0) 3988 wakeup(bp); 3989 mtx_unlock(mtxp); 3990 } 3991 3992 void 3993 bunpin_wait(struct buf *bp) 3994 { 3995 struct mtx *mtxp; 3996 3997 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3998 mtx_lock(mtxp); 3999 while (bp->b_pin_count > 0) 4000 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4001 mtx_unlock(mtxp); 4002 } 4003 4004 #include "opt_ddb.h" 4005 #ifdef DDB 4006 #include <ddb/ddb.h> 4007 4008 /* DDB command to show buffer data */ 4009 DB_SHOW_COMMAND(buffer, db_show_buffer) 4010 { 4011 /* get args */ 4012 struct buf *bp = (struct buf *)addr; 4013 4014 if (!have_addr) { 4015 db_printf("usage: show buffer <addr>\n"); 4016 return; 4017 } 4018 4019 db_printf("buf at %p\n", bp); 4020 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4021 db_printf( 4022 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4023 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n", 4024 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4025 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4026 bp->b_dep.lh_first); 4027 if (bp->b_npages) { 4028 int i; 4029 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4030 for (i = 0; i < bp->b_npages; i++) { 4031 vm_page_t m; 4032 m = bp->b_pages[i]; 4033 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4034 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4035 if ((i + 1) < bp->b_npages) 4036 db_printf(","); 4037 } 4038 db_printf("\n"); 4039 } 4040 db_printf(" "); 4041 lockmgr_printinfo(&bp->b_lock); 4042 } 4043 4044 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4045 { 4046 struct buf *bp; 4047 int i; 4048 4049 for (i = 0; i < nbuf; i++) { 4050 bp = &buf[i]; 4051 if (BUF_ISLOCKED(bp)) { 4052 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4053 db_printf("\n"); 4054 } 4055 } 4056 } 4057 4058 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4059 { 4060 struct vnode *vp; 4061 struct buf *bp; 4062 4063 if (!have_addr) { 4064 db_printf("usage: show vnodebufs <addr>\n"); 4065 return; 4066 } 4067 vp = (struct vnode *)addr; 4068 db_printf("Clean buffers:\n"); 4069 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4070 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4071 db_printf("\n"); 4072 } 4073 db_printf("Dirty buffers:\n"); 4074 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4075 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4076 db_printf("\n"); 4077 } 4078 } 4079 4080 DB_COMMAND(countfreebufs, db_coundfreebufs) 4081 { 4082 struct buf *bp; 4083 int i, used = 0, nfree = 0; 4084 4085 if (have_addr) { 4086 db_printf("usage: countfreebufs\n"); 4087 return; 4088 } 4089 4090 for (i = 0; i < nbuf; i++) { 4091 bp = &buf[i]; 4092 if ((bp->b_vflags & BV_INFREECNT) != 0) 4093 nfree++; 4094 else 4095 used++; 4096 } 4097 4098 db_printf("Counted %d free, %d used (%d tot)\n", nfree, used, 4099 nfree + used); 4100 db_printf("numfreebuffers is %d\n", numfreebuffers); 4101 } 4102 #endif /* DDB */ 4103