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, vm_offset_t from, 99 vm_offset_t to); 100 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 101 vm_offset_t to); 102 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m); 103 static void vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, 104 vm_page_t m); 105 static void vfs_drain_busy_pages(struct buf *bp); 106 static void vfs_clean_pages_dirty_buf(struct buf *bp); 107 static void vfs_setdirty_locked_object(struct buf *bp); 108 static void vfs_vmio_release(struct buf *bp); 109 static int vfs_bio_clcheck(struct vnode *vp, int size, 110 daddr_t lblkno, daddr_t blkno); 111 static int buf_do_flush(struct vnode *vp); 112 static int flushbufqueues(struct vnode *, int, int); 113 static void buf_daemon(void); 114 static void bremfreel(struct buf *bp); 115 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 116 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 117 static int sysctl_bufspace(SYSCTL_HANDLER_ARGS); 118 #endif 119 120 int vmiodirenable = TRUE; 121 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 122 "Use the VM system for directory writes"); 123 long runningbufspace; 124 SYSCTL_LONG(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 125 "Amount of presently outstanding async buffer io"); 126 static long bufspace; 127 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 128 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 129 SYSCTL_PROC(_vfs, OID_AUTO, bufspace, CTLTYPE_LONG|CTLFLAG_MPSAFE|CTLFLAG_RD, 130 &bufspace, 0, sysctl_bufspace, "L", "Virtual memory used for buffers"); 131 #else 132 SYSCTL_LONG(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 133 "Virtual memory used for buffers"); 134 #endif 135 static long maxbufspace; 136 SYSCTL_LONG(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 137 "Maximum allowed value of bufspace (including buf_daemon)"); 138 static long bufmallocspace; 139 SYSCTL_LONG(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 140 "Amount of malloced memory for buffers"); 141 static long maxbufmallocspace; 142 SYSCTL_LONG(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 143 "Maximum amount of malloced memory for buffers"); 144 static long lobufspace; 145 SYSCTL_LONG(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 146 "Minimum amount of buffers we want to have"); 147 long hibufspace; 148 SYSCTL_LONG(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 149 "Maximum allowed value of bufspace (excluding buf_daemon)"); 150 static int bufreusecnt; 151 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 152 "Number of times we have reused a buffer"); 153 static int buffreekvacnt; 154 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 155 "Number of times we have freed the KVA space from some buffer"); 156 static int bufdefragcnt; 157 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 158 "Number of times we have had to repeat buffer allocation to defragment"); 159 static long lorunningspace; 160 SYSCTL_LONG(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 161 "Minimum preferred space used for in-progress I/O"); 162 static long hirunningspace; 163 SYSCTL_LONG(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 164 "Maximum amount of space to use for in-progress I/O"); 165 int dirtybufferflushes; 166 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 167 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 168 int bdwriteskip; 169 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 170 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 171 int altbufferflushes; 172 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 173 0, "Number of fsync flushes to limit dirty buffers"); 174 static int recursiveflushes; 175 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 176 0, "Number of flushes skipped due to being recursive"); 177 static int numdirtybuffers; 178 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 179 "Number of buffers that are dirty (has unwritten changes) at the moment"); 180 static int lodirtybuffers; 181 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 182 "How many buffers we want to have free before bufdaemon can sleep"); 183 static int hidirtybuffers; 184 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 185 "When the number of dirty buffers is considered severe"); 186 int dirtybufthresh; 187 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 188 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 189 static int numfreebuffers; 190 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 191 "Number of free buffers"); 192 static int lofreebuffers; 193 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 194 "XXX Unused"); 195 static int hifreebuffers; 196 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 197 "XXX Complicatedly unused"); 198 static int getnewbufcalls; 199 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 200 "Number of calls to getnewbuf"); 201 static int getnewbufrestarts; 202 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 203 "Number of times getnewbuf has had to restart a buffer aquisition"); 204 static int flushbufqtarget = 100; 205 SYSCTL_INT(_vfs, OID_AUTO, flushbufqtarget, CTLFLAG_RW, &flushbufqtarget, 0, 206 "Amount of work to do in flushbufqueues when helping bufdaemon"); 207 static long notbufdflashes; 208 SYSCTL_LONG(_vfs, OID_AUTO, notbufdflashes, CTLFLAG_RD, ¬bufdflashes, 0, 209 "Number of dirty buffer flushes done by the bufdaemon helpers"); 210 211 /* 212 * Wakeup point for bufdaemon, as well as indicator of whether it is already 213 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 214 * is idling. 215 */ 216 static int bd_request; 217 218 /* 219 * Request for the buf daemon to write more buffers than is indicated by 220 * lodirtybuf. This may be necessary to push out excess dependencies or 221 * defragment the address space where a simple count of the number of dirty 222 * buffers is insufficient to characterize the demand for flushing them. 223 */ 224 static int bd_speedupreq; 225 226 /* 227 * This lock synchronizes access to bd_request. 228 */ 229 static struct mtx bdlock; 230 231 /* 232 * bogus page -- for I/O to/from partially complete buffers 233 * this is a temporary solution to the problem, but it is not 234 * really that bad. it would be better to split the buffer 235 * for input in the case of buffers partially already in memory, 236 * but the code is intricate enough already. 237 */ 238 vm_page_t bogus_page; 239 240 /* 241 * Synchronization (sleep/wakeup) variable for active buffer space requests. 242 * Set when wait starts, cleared prior to wakeup(). 243 * Used in runningbufwakeup() and waitrunningbufspace(). 244 */ 245 static int runningbufreq; 246 247 /* 248 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 249 * waitrunningbufspace(). 250 */ 251 static struct mtx rbreqlock; 252 253 /* 254 * Synchronization (sleep/wakeup) variable for buffer requests. 255 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 256 * by and/or. 257 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 258 * getnewbuf(), and getblk(). 259 */ 260 static int needsbuffer; 261 262 /* 263 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 264 */ 265 static struct mtx nblock; 266 267 /* 268 * Definitions for the buffer free lists. 269 */ 270 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 271 272 #define QUEUE_NONE 0 /* on no queue */ 273 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 274 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 275 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 276 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 277 #define QUEUE_EMPTY 5 /* empty buffer headers */ 278 #define QUEUE_SENTINEL 1024 /* not an queue index, but mark for sentinel */ 279 280 /* Queues for free buffers with various properties */ 281 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 282 283 /* Lock for the bufqueues */ 284 static struct mtx bqlock; 285 286 /* 287 * Single global constant for BUF_WMESG, to avoid getting multiple references. 288 * buf_wmesg is referred from macros. 289 */ 290 const char *buf_wmesg = BUF_WMESG; 291 292 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 293 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 294 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 295 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 296 297 #if defined(COMPAT_FREEBSD4) || defined(COMPAT_FREEBSD5) || \ 298 defined(COMPAT_FREEBSD6) || defined(COMPAT_FREEBSD7) 299 static int 300 sysctl_bufspace(SYSCTL_HANDLER_ARGS) 301 { 302 long lvalue; 303 int ivalue; 304 305 if (sizeof(int) == sizeof(long) || req->oldlen >= sizeof(long)) 306 return (sysctl_handle_long(oidp, arg1, arg2, req)); 307 lvalue = *(long *)arg1; 308 if (lvalue > INT_MAX) 309 /* On overflow, still write out a long to trigger ENOMEM. */ 310 return (sysctl_handle_long(oidp, &lvalue, 0, req)); 311 ivalue = lvalue; 312 return (sysctl_handle_int(oidp, &ivalue, 0, req)); 313 } 314 #endif 315 316 #ifdef DIRECTIO 317 extern void ffs_rawread_setup(void); 318 #endif /* DIRECTIO */ 319 /* 320 * numdirtywakeup: 321 * 322 * If someone is blocked due to there being too many dirty buffers, 323 * and numdirtybuffers is now reasonable, wake them up. 324 */ 325 326 static __inline void 327 numdirtywakeup(int level) 328 { 329 330 if (numdirtybuffers <= level) { 331 mtx_lock(&nblock); 332 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 333 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 334 wakeup(&needsbuffer); 335 } 336 mtx_unlock(&nblock); 337 } 338 } 339 340 /* 341 * bufspacewakeup: 342 * 343 * Called when buffer space is potentially available for recovery. 344 * getnewbuf() will block on this flag when it is unable to free 345 * sufficient buffer space. Buffer space becomes recoverable when 346 * bp's get placed back in the queues. 347 */ 348 349 static __inline void 350 bufspacewakeup(void) 351 { 352 353 /* 354 * If someone is waiting for BUF space, wake them up. Even 355 * though we haven't freed the kva space yet, the waiting 356 * process will be able to now. 357 */ 358 mtx_lock(&nblock); 359 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 360 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 361 wakeup(&needsbuffer); 362 } 363 mtx_unlock(&nblock); 364 } 365 366 /* 367 * runningbufwakeup() - in-progress I/O accounting. 368 * 369 */ 370 void 371 runningbufwakeup(struct buf *bp) 372 { 373 374 if (bp->b_runningbufspace) { 375 atomic_subtract_long(&runningbufspace, bp->b_runningbufspace); 376 bp->b_runningbufspace = 0; 377 mtx_lock(&rbreqlock); 378 if (runningbufreq && runningbufspace <= lorunningspace) { 379 runningbufreq = 0; 380 wakeup(&runningbufreq); 381 } 382 mtx_unlock(&rbreqlock); 383 } 384 } 385 386 /* 387 * bufcountwakeup: 388 * 389 * Called when a buffer has been added to one of the free queues to 390 * account for the buffer and to wakeup anyone waiting for free buffers. 391 * This typically occurs when large amounts of metadata are being handled 392 * by the buffer cache ( else buffer space runs out first, usually ). 393 */ 394 395 static __inline void 396 bufcountwakeup(void) 397 { 398 399 atomic_add_int(&numfreebuffers, 1); 400 mtx_lock(&nblock); 401 if (needsbuffer) { 402 needsbuffer &= ~VFS_BIO_NEED_ANY; 403 if (numfreebuffers >= hifreebuffers) 404 needsbuffer &= ~VFS_BIO_NEED_FREE; 405 wakeup(&needsbuffer); 406 } 407 mtx_unlock(&nblock); 408 } 409 410 /* 411 * waitrunningbufspace() 412 * 413 * runningbufspace is a measure of the amount of I/O currently 414 * running. This routine is used in async-write situations to 415 * prevent creating huge backups of pending writes to a device. 416 * Only asynchronous writes are governed by this function. 417 * 418 * Reads will adjust runningbufspace, but will not block based on it. 419 * The read load has a side effect of reducing the allowed write load. 420 * 421 * This does NOT turn an async write into a sync write. It waits 422 * for earlier writes to complete and generally returns before the 423 * caller's write has reached the device. 424 */ 425 void 426 waitrunningbufspace(void) 427 { 428 429 mtx_lock(&rbreqlock); 430 while (runningbufspace > hirunningspace) { 431 ++runningbufreq; 432 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 433 } 434 mtx_unlock(&rbreqlock); 435 } 436 437 438 /* 439 * vfs_buf_test_cache: 440 * 441 * Called when a buffer is extended. This function clears the B_CACHE 442 * bit if the newly extended portion of the buffer does not contain 443 * valid data. 444 */ 445 static __inline 446 void 447 vfs_buf_test_cache(struct buf *bp, 448 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 449 vm_page_t m) 450 { 451 452 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 453 if (bp->b_flags & B_CACHE) { 454 int base = (foff + off) & PAGE_MASK; 455 if (vm_page_is_valid(m, base, size) == 0) 456 bp->b_flags &= ~B_CACHE; 457 } 458 } 459 460 /* Wake up the buffer daemon if necessary */ 461 static __inline 462 void 463 bd_wakeup(int dirtybuflevel) 464 { 465 466 mtx_lock(&bdlock); 467 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 468 bd_request = 1; 469 wakeup(&bd_request); 470 } 471 mtx_unlock(&bdlock); 472 } 473 474 /* 475 * bd_speedup - speedup the buffer cache flushing code 476 */ 477 478 void 479 bd_speedup(void) 480 { 481 int needwake; 482 483 mtx_lock(&bdlock); 484 needwake = 0; 485 if (bd_speedupreq == 0 || bd_request == 0) 486 needwake = 1; 487 bd_speedupreq = 1; 488 bd_request = 1; 489 if (needwake) 490 wakeup(&bd_request); 491 mtx_unlock(&bdlock); 492 } 493 494 /* 495 * Calculating buffer cache scaling values and reserve space for buffer 496 * headers. This is called during low level kernel initialization and 497 * may be called more then once. We CANNOT write to the memory area 498 * being reserved at this time. 499 */ 500 caddr_t 501 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 502 { 503 int tuned_nbuf; 504 long maxbuf; 505 506 /* 507 * physmem_est is in pages. Convert it to kilobytes (assumes 508 * PAGE_SIZE is >= 1K) 509 */ 510 physmem_est = physmem_est * (PAGE_SIZE / 1024); 511 512 /* 513 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 514 * For the first 64MB of ram nominally allocate sufficient buffers to 515 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 516 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 517 * the buffer cache we limit the eventual kva reservation to 518 * maxbcache bytes. 519 * 520 * factor represents the 1/4 x ram conversion. 521 */ 522 if (nbuf == 0) { 523 int factor = 4 * BKVASIZE / 1024; 524 525 nbuf = 50; 526 if (physmem_est > 4096) 527 nbuf += min((physmem_est - 4096) / factor, 528 65536 / factor); 529 if (physmem_est > 65536) 530 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 531 532 if (maxbcache && nbuf > maxbcache / BKVASIZE) 533 nbuf = maxbcache / BKVASIZE; 534 tuned_nbuf = 1; 535 } else 536 tuned_nbuf = 0; 537 538 /* XXX Avoid unsigned long overflows later on with maxbufspace. */ 539 maxbuf = (LONG_MAX / 3) / BKVASIZE; 540 if (nbuf > maxbuf) { 541 if (!tuned_nbuf) 542 printf("Warning: nbufs lowered from %d to %ld\n", nbuf, 543 maxbuf); 544 nbuf = maxbuf; 545 } 546 547 /* 548 * swbufs are used as temporary holders for I/O, such as paging I/O. 549 * We have no less then 16 and no more then 256. 550 */ 551 nswbuf = max(min(nbuf/4, 256), 16); 552 #ifdef NSWBUF_MIN 553 if (nswbuf < NSWBUF_MIN) 554 nswbuf = NSWBUF_MIN; 555 #endif 556 #ifdef DIRECTIO 557 ffs_rawread_setup(); 558 #endif 559 560 /* 561 * Reserve space for the buffer cache buffers 562 */ 563 swbuf = (void *)v; 564 v = (caddr_t)(swbuf + nswbuf); 565 buf = (void *)v; 566 v = (caddr_t)(buf + nbuf); 567 568 return(v); 569 } 570 571 /* Initialize the buffer subsystem. Called before use of any buffers. */ 572 void 573 bufinit(void) 574 { 575 struct buf *bp; 576 int i; 577 578 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 579 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 580 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 581 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 582 583 /* next, make a null set of free lists */ 584 for (i = 0; i < BUFFER_QUEUES; i++) 585 TAILQ_INIT(&bufqueues[i]); 586 587 /* finally, initialize each buffer header and stick on empty q */ 588 for (i = 0; i < nbuf; i++) { 589 bp = &buf[i]; 590 bzero(bp, sizeof *bp); 591 bp->b_flags = B_INVAL; /* we're just an empty header */ 592 bp->b_rcred = NOCRED; 593 bp->b_wcred = NOCRED; 594 bp->b_qindex = QUEUE_EMPTY; 595 bp->b_vflags = 0; 596 bp->b_xflags = 0; 597 LIST_INIT(&bp->b_dep); 598 BUF_LOCKINIT(bp); 599 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 600 } 601 602 /* 603 * maxbufspace is the absolute maximum amount of buffer space we are 604 * allowed to reserve in KVM and in real terms. The absolute maximum 605 * is nominally used by buf_daemon. hibufspace is the nominal maximum 606 * used by most other processes. The differential is required to 607 * ensure that buf_daemon is able to run when other processes might 608 * be blocked waiting for buffer space. 609 * 610 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 611 * this may result in KVM fragmentation which is not handled optimally 612 * by the system. 613 */ 614 maxbufspace = (long)nbuf * BKVASIZE; 615 hibufspace = lmax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 616 lobufspace = hibufspace - MAXBSIZE; 617 618 lorunningspace = 512 * 1024; 619 hirunningspace = 1024 * 1024; 620 621 /* 622 * Limit the amount of malloc memory since it is wired permanently into 623 * the kernel space. Even though this is accounted for in the buffer 624 * allocation, we don't want the malloced region to grow uncontrolled. 625 * The malloc scheme improves memory utilization significantly on average 626 * (small) directories. 627 */ 628 maxbufmallocspace = hibufspace / 20; 629 630 /* 631 * Reduce the chance of a deadlock occuring by limiting the number 632 * of delayed-write dirty buffers we allow to stack up. 633 */ 634 hidirtybuffers = nbuf / 4 + 20; 635 dirtybufthresh = hidirtybuffers * 9 / 10; 636 numdirtybuffers = 0; 637 /* 638 * To support extreme low-memory systems, make sure hidirtybuffers cannot 639 * eat up all available buffer space. This occurs when our minimum cannot 640 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 641 * BKVASIZE'd (8K) buffers. 642 */ 643 while ((long)hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 644 hidirtybuffers >>= 1; 645 } 646 lodirtybuffers = hidirtybuffers / 2; 647 648 /* 649 * Try to keep the number of free buffers in the specified range, 650 * and give special processes (e.g. like buf_daemon) access to an 651 * emergency reserve. 652 */ 653 lofreebuffers = nbuf / 18 + 5; 654 hifreebuffers = 2 * lofreebuffers; 655 numfreebuffers = nbuf; 656 657 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 658 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 659 } 660 661 /* 662 * bfreekva() - free the kva allocation for a buffer. 663 * 664 * Since this call frees up buffer space, we call bufspacewakeup(). 665 */ 666 static void 667 bfreekva(struct buf *bp) 668 { 669 670 if (bp->b_kvasize) { 671 atomic_add_int(&buffreekvacnt, 1); 672 atomic_subtract_long(&bufspace, bp->b_kvasize); 673 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 674 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 675 bp->b_kvasize = 0; 676 bufspacewakeup(); 677 } 678 } 679 680 /* 681 * bremfree: 682 * 683 * Mark the buffer for removal from the appropriate free list in brelse. 684 * 685 */ 686 void 687 bremfree(struct buf *bp) 688 { 689 690 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 691 KASSERT((bp->b_flags & B_REMFREE) == 0, 692 ("bremfree: buffer %p already marked for delayed removal.", bp)); 693 KASSERT(bp->b_qindex != QUEUE_NONE, 694 ("bremfree: buffer %p not on a queue.", bp)); 695 BUF_ASSERT_HELD(bp); 696 697 bp->b_flags |= B_REMFREE; 698 /* Fixup numfreebuffers count. */ 699 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 700 atomic_subtract_int(&numfreebuffers, 1); 701 } 702 703 /* 704 * bremfreef: 705 * 706 * Force an immediate removal from a free list. Used only in nfs when 707 * it abuses the b_freelist pointer. 708 */ 709 void 710 bremfreef(struct buf *bp) 711 { 712 mtx_lock(&bqlock); 713 bremfreel(bp); 714 mtx_unlock(&bqlock); 715 } 716 717 /* 718 * bremfreel: 719 * 720 * Removes a buffer from the free list, must be called with the 721 * bqlock held. 722 */ 723 static void 724 bremfreel(struct buf *bp) 725 { 726 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 727 bp, bp->b_vp, bp->b_flags); 728 KASSERT(bp->b_qindex != QUEUE_NONE, 729 ("bremfreel: buffer %p not on a queue.", bp)); 730 BUF_ASSERT_HELD(bp); 731 mtx_assert(&bqlock, MA_OWNED); 732 733 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 734 bp->b_qindex = QUEUE_NONE; 735 /* 736 * If this was a delayed bremfree() we only need to remove the buffer 737 * from the queue and return the stats are already done. 738 */ 739 if (bp->b_flags & B_REMFREE) { 740 bp->b_flags &= ~B_REMFREE; 741 return; 742 } 743 /* 744 * Fixup numfreebuffers count. If the buffer is invalid or not 745 * delayed-write, the buffer was free and we must decrement 746 * numfreebuffers. 747 */ 748 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 749 atomic_subtract_int(&numfreebuffers, 1); 750 } 751 752 753 /* 754 * Get a buffer with the specified data. Look in the cache first. We 755 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 756 * is set, the buffer is valid and we do not have to do anything ( see 757 * getblk() ). This is really just a special case of breadn(). 758 */ 759 int 760 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 761 struct buf **bpp) 762 { 763 764 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 765 } 766 767 /* 768 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 769 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 770 * the buffer is valid and we do not have to do anything. 771 */ 772 void 773 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 774 int cnt, struct ucred * cred) 775 { 776 struct buf *rabp; 777 int i; 778 779 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 780 if (inmem(vp, *rablkno)) 781 continue; 782 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 783 784 if ((rabp->b_flags & B_CACHE) == 0) { 785 if (!TD_IS_IDLETHREAD(curthread)) 786 curthread->td_ru.ru_inblock++; 787 rabp->b_flags |= B_ASYNC; 788 rabp->b_flags &= ~B_INVAL; 789 rabp->b_ioflags &= ~BIO_ERROR; 790 rabp->b_iocmd = BIO_READ; 791 if (rabp->b_rcred == NOCRED && cred != NOCRED) 792 rabp->b_rcred = crhold(cred); 793 vfs_busy_pages(rabp, 0); 794 BUF_KERNPROC(rabp); 795 rabp->b_iooffset = dbtob(rabp->b_blkno); 796 bstrategy(rabp); 797 } else { 798 brelse(rabp); 799 } 800 } 801 } 802 803 /* 804 * Operates like bread, but also starts asynchronous I/O on 805 * read-ahead blocks. 806 */ 807 int 808 breadn(struct vnode * vp, daddr_t blkno, int size, 809 daddr_t * rablkno, int *rabsize, 810 int cnt, struct ucred * cred, struct buf **bpp) 811 { 812 struct buf *bp; 813 int rv = 0, readwait = 0; 814 815 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 816 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 817 818 /* if not found in cache, do some I/O */ 819 if ((bp->b_flags & B_CACHE) == 0) { 820 if (!TD_IS_IDLETHREAD(curthread)) 821 curthread->td_ru.ru_inblock++; 822 bp->b_iocmd = BIO_READ; 823 bp->b_flags &= ~B_INVAL; 824 bp->b_ioflags &= ~BIO_ERROR; 825 if (bp->b_rcred == NOCRED && cred != NOCRED) 826 bp->b_rcred = crhold(cred); 827 vfs_busy_pages(bp, 0); 828 bp->b_iooffset = dbtob(bp->b_blkno); 829 bstrategy(bp); 830 ++readwait; 831 } 832 833 breada(vp, rablkno, rabsize, cnt, cred); 834 835 if (readwait) { 836 rv = bufwait(bp); 837 } 838 return (rv); 839 } 840 841 /* 842 * Write, release buffer on completion. (Done by iodone 843 * if async). Do not bother writing anything if the buffer 844 * is invalid. 845 * 846 * Note that we set B_CACHE here, indicating that buffer is 847 * fully valid and thus cacheable. This is true even of NFS 848 * now so we set it generally. This could be set either here 849 * or in biodone() since the I/O is synchronous. We put it 850 * here. 851 */ 852 int 853 bufwrite(struct buf *bp) 854 { 855 int oldflags; 856 struct vnode *vp; 857 int vp_md; 858 859 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 860 if (bp->b_flags & B_INVAL) { 861 brelse(bp); 862 return (0); 863 } 864 865 oldflags = bp->b_flags; 866 867 BUF_ASSERT_HELD(bp); 868 869 if (bp->b_pin_count > 0) 870 bunpin_wait(bp); 871 872 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 873 ("FFS background buffer should not get here %p", bp)); 874 875 vp = bp->b_vp; 876 if (vp) 877 vp_md = vp->v_vflag & VV_MD; 878 else 879 vp_md = 0; 880 881 /* Mark the buffer clean */ 882 bundirty(bp); 883 884 bp->b_flags &= ~B_DONE; 885 bp->b_ioflags &= ~BIO_ERROR; 886 bp->b_flags |= B_CACHE; 887 bp->b_iocmd = BIO_WRITE; 888 889 bufobj_wref(bp->b_bufobj); 890 vfs_busy_pages(bp, 1); 891 892 /* 893 * Normal bwrites pipeline writes 894 */ 895 bp->b_runningbufspace = bp->b_bufsize; 896 atomic_add_long(&runningbufspace, bp->b_runningbufspace); 897 898 if (!TD_IS_IDLETHREAD(curthread)) 899 curthread->td_ru.ru_oublock++; 900 if (oldflags & B_ASYNC) 901 BUF_KERNPROC(bp); 902 bp->b_iooffset = dbtob(bp->b_blkno); 903 bstrategy(bp); 904 905 if ((oldflags & B_ASYNC) == 0) { 906 int rtval = bufwait(bp); 907 brelse(bp); 908 return (rtval); 909 } else { 910 /* 911 * don't allow the async write to saturate the I/O 912 * system. We will not deadlock here because 913 * we are blocking waiting for I/O that is already in-progress 914 * to complete. We do not block here if it is the update 915 * or syncer daemon trying to clean up as that can lead 916 * to deadlock. 917 */ 918 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 919 waitrunningbufspace(); 920 } 921 922 return (0); 923 } 924 925 void 926 bufbdflush(struct bufobj *bo, struct buf *bp) 927 { 928 struct buf *nbp; 929 930 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 931 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 932 altbufferflushes++; 933 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 934 BO_LOCK(bo); 935 /* 936 * Try to find a buffer to flush. 937 */ 938 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 939 if ((nbp->b_vflags & BV_BKGRDINPROG) || 940 BUF_LOCK(nbp, 941 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 942 continue; 943 if (bp == nbp) 944 panic("bdwrite: found ourselves"); 945 BO_UNLOCK(bo); 946 /* Don't countdeps with the bo lock held. */ 947 if (buf_countdeps(nbp, 0)) { 948 BO_LOCK(bo); 949 BUF_UNLOCK(nbp); 950 continue; 951 } 952 if (nbp->b_flags & B_CLUSTEROK) { 953 vfs_bio_awrite(nbp); 954 } else { 955 bremfree(nbp); 956 bawrite(nbp); 957 } 958 dirtybufferflushes++; 959 break; 960 } 961 if (nbp == NULL) 962 BO_UNLOCK(bo); 963 } 964 } 965 966 /* 967 * Delayed write. (Buffer is marked dirty). Do not bother writing 968 * anything if the buffer is marked invalid. 969 * 970 * Note that since the buffer must be completely valid, we can safely 971 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 972 * biodone() in order to prevent getblk from writing the buffer 973 * out synchronously. 974 */ 975 void 976 bdwrite(struct buf *bp) 977 { 978 struct thread *td = curthread; 979 struct vnode *vp; 980 struct bufobj *bo; 981 982 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 983 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 984 BUF_ASSERT_HELD(bp); 985 986 if (bp->b_flags & B_INVAL) { 987 brelse(bp); 988 return; 989 } 990 991 /* 992 * If we have too many dirty buffers, don't create any more. 993 * If we are wildly over our limit, then force a complete 994 * cleanup. Otherwise, just keep the situation from getting 995 * out of control. Note that we have to avoid a recursive 996 * disaster and not try to clean up after our own cleanup! 997 */ 998 vp = bp->b_vp; 999 bo = bp->b_bufobj; 1000 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 1001 td->td_pflags |= TDP_INBDFLUSH; 1002 BO_BDFLUSH(bo, bp); 1003 td->td_pflags &= ~TDP_INBDFLUSH; 1004 } else 1005 recursiveflushes++; 1006 1007 bdirty(bp); 1008 /* 1009 * Set B_CACHE, indicating that the buffer is fully valid. This is 1010 * true even of NFS now. 1011 */ 1012 bp->b_flags |= B_CACHE; 1013 1014 /* 1015 * This bmap keeps the system from needing to do the bmap later, 1016 * perhaps when the system is attempting to do a sync. Since it 1017 * is likely that the indirect block -- or whatever other datastructure 1018 * that the filesystem needs is still in memory now, it is a good 1019 * thing to do this. Note also, that if the pageout daemon is 1020 * requesting a sync -- there might not be enough memory to do 1021 * the bmap then... So, this is important to do. 1022 */ 1023 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 1024 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 1025 } 1026 1027 /* 1028 * Set the *dirty* buffer range based upon the VM system dirty 1029 * pages. 1030 * 1031 * Mark the buffer pages as clean. We need to do this here to 1032 * satisfy the vnode_pager and the pageout daemon, so that it 1033 * thinks that the pages have been "cleaned". Note that since 1034 * the pages are in a delayed write buffer -- the VFS layer 1035 * "will" see that the pages get written out on the next sync, 1036 * or perhaps the cluster will be completed. 1037 */ 1038 vfs_clean_pages_dirty_buf(bp); 1039 bqrelse(bp); 1040 1041 /* 1042 * Wakeup the buffer flushing daemon if we have a lot of dirty 1043 * buffers (midpoint between our recovery point and our stall 1044 * point). 1045 */ 1046 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1047 1048 /* 1049 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1050 * due to the softdep code. 1051 */ 1052 } 1053 1054 /* 1055 * bdirty: 1056 * 1057 * Turn buffer into delayed write request. We must clear BIO_READ and 1058 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1059 * itself to properly update it in the dirty/clean lists. We mark it 1060 * B_DONE to ensure that any asynchronization of the buffer properly 1061 * clears B_DONE ( else a panic will occur later ). 1062 * 1063 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1064 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1065 * should only be called if the buffer is known-good. 1066 * 1067 * Since the buffer is not on a queue, we do not update the numfreebuffers 1068 * count. 1069 * 1070 * The buffer must be on QUEUE_NONE. 1071 */ 1072 void 1073 bdirty(struct buf *bp) 1074 { 1075 1076 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1077 bp, bp->b_vp, bp->b_flags); 1078 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1079 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1080 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1081 BUF_ASSERT_HELD(bp); 1082 bp->b_flags &= ~(B_RELBUF); 1083 bp->b_iocmd = BIO_WRITE; 1084 1085 if ((bp->b_flags & B_DELWRI) == 0) { 1086 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1087 reassignbuf(bp); 1088 atomic_add_int(&numdirtybuffers, 1); 1089 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1090 } 1091 } 1092 1093 /* 1094 * bundirty: 1095 * 1096 * Clear B_DELWRI for buffer. 1097 * 1098 * Since the buffer is not on a queue, we do not update the numfreebuffers 1099 * count. 1100 * 1101 * The buffer must be on QUEUE_NONE. 1102 */ 1103 1104 void 1105 bundirty(struct buf *bp) 1106 { 1107 1108 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1109 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1110 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1111 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1112 BUF_ASSERT_HELD(bp); 1113 1114 if (bp->b_flags & B_DELWRI) { 1115 bp->b_flags &= ~B_DELWRI; 1116 reassignbuf(bp); 1117 atomic_subtract_int(&numdirtybuffers, 1); 1118 numdirtywakeup(lodirtybuffers); 1119 } 1120 /* 1121 * Since it is now being written, we can clear its deferred write flag. 1122 */ 1123 bp->b_flags &= ~B_DEFERRED; 1124 } 1125 1126 /* 1127 * bawrite: 1128 * 1129 * Asynchronous write. Start output on a buffer, but do not wait for 1130 * it to complete. The buffer is released when the output completes. 1131 * 1132 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1133 * B_INVAL buffers. Not us. 1134 */ 1135 void 1136 bawrite(struct buf *bp) 1137 { 1138 1139 bp->b_flags |= B_ASYNC; 1140 (void) bwrite(bp); 1141 } 1142 1143 /* 1144 * bwillwrite: 1145 * 1146 * Called prior to the locking of any vnodes when we are expecting to 1147 * write. We do not want to starve the buffer cache with too many 1148 * dirty buffers so we block here. By blocking prior to the locking 1149 * of any vnodes we attempt to avoid the situation where a locked vnode 1150 * prevents the various system daemons from flushing related buffers. 1151 */ 1152 1153 void 1154 bwillwrite(void) 1155 { 1156 1157 if (numdirtybuffers >= hidirtybuffers) { 1158 mtx_lock(&nblock); 1159 while (numdirtybuffers >= hidirtybuffers) { 1160 bd_wakeup(1); 1161 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1162 msleep(&needsbuffer, &nblock, 1163 (PRIBIO + 4), "flswai", 0); 1164 } 1165 mtx_unlock(&nblock); 1166 } 1167 } 1168 1169 /* 1170 * Return true if we have too many dirty buffers. 1171 */ 1172 int 1173 buf_dirty_count_severe(void) 1174 { 1175 1176 return(numdirtybuffers >= hidirtybuffers); 1177 } 1178 1179 static __noinline int 1180 buf_vm_page_count_severe(void) 1181 { 1182 1183 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1184 1185 return vm_page_count_severe(); 1186 } 1187 1188 /* 1189 * brelse: 1190 * 1191 * Release a busy buffer and, if requested, free its resources. The 1192 * buffer will be stashed in the appropriate bufqueue[] allowing it 1193 * to be accessed later as a cache entity or reused for other purposes. 1194 */ 1195 void 1196 brelse(struct buf *bp) 1197 { 1198 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1199 bp, bp->b_vp, bp->b_flags); 1200 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1201 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1202 1203 if (bp->b_flags & B_MANAGED) { 1204 bqrelse(bp); 1205 return; 1206 } 1207 1208 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1209 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1210 /* 1211 * Failed write, redirty. Must clear BIO_ERROR to prevent 1212 * pages from being scrapped. If the error is anything 1213 * other than an I/O error (EIO), assume that retrying 1214 * is futile. 1215 */ 1216 bp->b_ioflags &= ~BIO_ERROR; 1217 bdirty(bp); 1218 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1219 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1220 /* 1221 * Either a failed I/O or we were asked to free or not 1222 * cache the buffer. 1223 */ 1224 bp->b_flags |= B_INVAL; 1225 if (!LIST_EMPTY(&bp->b_dep)) 1226 buf_deallocate(bp); 1227 if (bp->b_flags & B_DELWRI) { 1228 atomic_subtract_int(&numdirtybuffers, 1); 1229 numdirtywakeup(lodirtybuffers); 1230 } 1231 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1232 if ((bp->b_flags & B_VMIO) == 0) { 1233 if (bp->b_bufsize) 1234 allocbuf(bp, 0); 1235 if (bp->b_vp) 1236 brelvp(bp); 1237 } 1238 } 1239 1240 /* 1241 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1242 * is called with B_DELWRI set, the underlying pages may wind up 1243 * getting freed causing a previous write (bdwrite()) to get 'lost' 1244 * because pages associated with a B_DELWRI bp are marked clean. 1245 * 1246 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1247 * if B_DELWRI is set. 1248 * 1249 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1250 * on pages to return pages to the VM page queues. 1251 */ 1252 if (bp->b_flags & B_DELWRI) 1253 bp->b_flags &= ~B_RELBUF; 1254 else if (buf_vm_page_count_severe()) { 1255 /* 1256 * The locking of the BO_LOCK is not necessary since 1257 * BKGRDINPROG cannot be set while we hold the buf 1258 * lock, it can only be cleared if it is already 1259 * pending. 1260 */ 1261 if (bp->b_vp) { 1262 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1263 bp->b_flags |= B_RELBUF; 1264 } else 1265 bp->b_flags |= B_RELBUF; 1266 } 1267 1268 /* 1269 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1270 * constituted, not even NFS buffers now. Two flags effect this. If 1271 * B_INVAL, the struct buf is invalidated but the VM object is kept 1272 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1273 * 1274 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1275 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1276 * buffer is also B_INVAL because it hits the re-dirtying code above. 1277 * 1278 * Normally we can do this whether a buffer is B_DELWRI or not. If 1279 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1280 * the commit state and we cannot afford to lose the buffer. If the 1281 * buffer has a background write in progress, we need to keep it 1282 * around to prevent it from being reconstituted and starting a second 1283 * background write. 1284 */ 1285 if ((bp->b_flags & B_VMIO) 1286 && !(bp->b_vp->v_mount != NULL && 1287 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1288 !vn_isdisk(bp->b_vp, NULL) && 1289 (bp->b_flags & B_DELWRI)) 1290 ) { 1291 1292 int i, j, resid; 1293 vm_page_t m; 1294 off_t foff; 1295 vm_pindex_t poff; 1296 vm_object_t obj; 1297 1298 obj = bp->b_bufobj->bo_object; 1299 1300 /* 1301 * Get the base offset and length of the buffer. Note that 1302 * in the VMIO case if the buffer block size is not 1303 * page-aligned then b_data pointer may not be page-aligned. 1304 * But our b_pages[] array *IS* page aligned. 1305 * 1306 * block sizes less then DEV_BSIZE (usually 512) are not 1307 * supported due to the page granularity bits (m->valid, 1308 * m->dirty, etc...). 1309 * 1310 * See man buf(9) for more information 1311 */ 1312 resid = bp->b_bufsize; 1313 foff = bp->b_offset; 1314 VM_OBJECT_LOCK(obj); 1315 for (i = 0; i < bp->b_npages; i++) { 1316 int had_bogus = 0; 1317 1318 m = bp->b_pages[i]; 1319 1320 /* 1321 * If we hit a bogus page, fixup *all* the bogus pages 1322 * now. 1323 */ 1324 if (m == bogus_page) { 1325 poff = OFF_TO_IDX(bp->b_offset); 1326 had_bogus = 1; 1327 1328 for (j = i; j < bp->b_npages; j++) { 1329 vm_page_t mtmp; 1330 mtmp = bp->b_pages[j]; 1331 if (mtmp == bogus_page) { 1332 mtmp = vm_page_lookup(obj, poff + j); 1333 if (!mtmp) { 1334 panic("brelse: page missing\n"); 1335 } 1336 bp->b_pages[j] = mtmp; 1337 } 1338 } 1339 1340 if ((bp->b_flags & B_INVAL) == 0) { 1341 pmap_qenter( 1342 trunc_page((vm_offset_t)bp->b_data), 1343 bp->b_pages, bp->b_npages); 1344 } 1345 m = bp->b_pages[i]; 1346 } 1347 if ((bp->b_flags & B_NOCACHE) || 1348 (bp->b_ioflags & BIO_ERROR && 1349 bp->b_iocmd == BIO_READ)) { 1350 int poffset = foff & PAGE_MASK; 1351 int presid = resid > (PAGE_SIZE - poffset) ? 1352 (PAGE_SIZE - poffset) : resid; 1353 1354 KASSERT(presid >= 0, ("brelse: extra page")); 1355 vm_page_set_invalid(m, poffset, presid); 1356 if (had_bogus) 1357 printf("avoided corruption bug in bogus_page/brelse code\n"); 1358 } 1359 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1360 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1361 } 1362 VM_OBJECT_UNLOCK(obj); 1363 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1364 vfs_vmio_release(bp); 1365 1366 } else if (bp->b_flags & B_VMIO) { 1367 1368 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1369 vfs_vmio_release(bp); 1370 } 1371 1372 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1373 if (bp->b_bufsize != 0) 1374 allocbuf(bp, 0); 1375 if (bp->b_vp != NULL) 1376 brelvp(bp); 1377 } 1378 1379 if (BUF_LOCKRECURSED(bp)) { 1380 /* do not release to free list */ 1381 BUF_UNLOCK(bp); 1382 return; 1383 } 1384 1385 /* enqueue */ 1386 mtx_lock(&bqlock); 1387 /* Handle delayed bremfree() processing. */ 1388 if (bp->b_flags & B_REMFREE) 1389 bremfreel(bp); 1390 if (bp->b_qindex != QUEUE_NONE) 1391 panic("brelse: free buffer onto another queue???"); 1392 1393 /* 1394 * If the buffer has junk contents signal it and eventually 1395 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1396 * doesn't find it. 1397 */ 1398 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1399 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1400 bp->b_flags |= B_INVAL; 1401 if (bp->b_flags & B_INVAL) { 1402 if (bp->b_flags & B_DELWRI) 1403 bundirty(bp); 1404 if (bp->b_vp) 1405 brelvp(bp); 1406 } 1407 1408 /* buffers with no memory */ 1409 if (bp->b_bufsize == 0) { 1410 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1411 if (bp->b_vflags & BV_BKGRDINPROG) 1412 panic("losing buffer 1"); 1413 if (bp->b_kvasize) { 1414 bp->b_qindex = QUEUE_EMPTYKVA; 1415 } else { 1416 bp->b_qindex = QUEUE_EMPTY; 1417 } 1418 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1419 /* buffers with junk contents */ 1420 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1421 (bp->b_ioflags & BIO_ERROR)) { 1422 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1423 if (bp->b_vflags & BV_BKGRDINPROG) 1424 panic("losing buffer 2"); 1425 bp->b_qindex = QUEUE_CLEAN; 1426 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1427 /* remaining buffers */ 1428 } else { 1429 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1430 (B_DELWRI|B_NEEDSGIANT)) 1431 bp->b_qindex = QUEUE_DIRTY_GIANT; 1432 else if (bp->b_flags & B_DELWRI) 1433 bp->b_qindex = QUEUE_DIRTY; 1434 else 1435 bp->b_qindex = QUEUE_CLEAN; 1436 if (bp->b_flags & B_AGE) 1437 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1438 else 1439 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1440 } 1441 mtx_unlock(&bqlock); 1442 1443 /* 1444 * Fixup numfreebuffers count. The bp is on an appropriate queue 1445 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1446 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1447 * if B_INVAL is set ). 1448 */ 1449 1450 if (!(bp->b_flags & B_DELWRI)) 1451 bufcountwakeup(); 1452 1453 /* 1454 * Something we can maybe free or reuse 1455 */ 1456 if (bp->b_bufsize || bp->b_kvasize) 1457 bufspacewakeup(); 1458 1459 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1460 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1461 panic("brelse: not dirty"); 1462 /* unlock */ 1463 BUF_UNLOCK(bp); 1464 } 1465 1466 /* 1467 * Release a buffer back to the appropriate queue but do not try to free 1468 * it. The buffer is expected to be used again soon. 1469 * 1470 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1471 * biodone() to requeue an async I/O on completion. It is also used when 1472 * known good buffers need to be requeued but we think we may need the data 1473 * again soon. 1474 * 1475 * XXX we should be able to leave the B_RELBUF hint set on completion. 1476 */ 1477 void 1478 bqrelse(struct buf *bp) 1479 { 1480 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1481 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1482 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1483 1484 if (BUF_LOCKRECURSED(bp)) { 1485 /* do not release to free list */ 1486 BUF_UNLOCK(bp); 1487 return; 1488 } 1489 1490 if (bp->b_flags & B_MANAGED) { 1491 if (bp->b_flags & B_REMFREE) { 1492 mtx_lock(&bqlock); 1493 bremfreel(bp); 1494 mtx_unlock(&bqlock); 1495 } 1496 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1497 BUF_UNLOCK(bp); 1498 return; 1499 } 1500 1501 mtx_lock(&bqlock); 1502 /* Handle delayed bremfree() processing. */ 1503 if (bp->b_flags & B_REMFREE) 1504 bremfreel(bp); 1505 if (bp->b_qindex != QUEUE_NONE) 1506 panic("bqrelse: free buffer onto another queue???"); 1507 /* buffers with stale but valid contents */ 1508 if (bp->b_flags & B_DELWRI) { 1509 if (bp->b_flags & B_NEEDSGIANT) 1510 bp->b_qindex = QUEUE_DIRTY_GIANT; 1511 else 1512 bp->b_qindex = QUEUE_DIRTY; 1513 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1514 } else { 1515 /* 1516 * The locking of the BO_LOCK for checking of the 1517 * BV_BKGRDINPROG is not necessary since the 1518 * BV_BKGRDINPROG cannot be set while we hold the buf 1519 * lock, it can only be cleared if it is already 1520 * pending. 1521 */ 1522 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1523 bp->b_qindex = QUEUE_CLEAN; 1524 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1525 b_freelist); 1526 } else { 1527 /* 1528 * We are too low on memory, we have to try to free 1529 * the buffer (most importantly: the wired pages 1530 * making up its backing store) *now*. 1531 */ 1532 mtx_unlock(&bqlock); 1533 brelse(bp); 1534 return; 1535 } 1536 } 1537 mtx_unlock(&bqlock); 1538 1539 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1540 bufcountwakeup(); 1541 1542 /* 1543 * Something we can maybe free or reuse. 1544 */ 1545 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1546 bufspacewakeup(); 1547 1548 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1549 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1550 panic("bqrelse: not dirty"); 1551 /* unlock */ 1552 BUF_UNLOCK(bp); 1553 } 1554 1555 /* Give pages used by the bp back to the VM system (where possible) */ 1556 static void 1557 vfs_vmio_release(struct buf *bp) 1558 { 1559 int i; 1560 vm_page_t m; 1561 1562 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1563 for (i = 0; i < bp->b_npages; i++) { 1564 m = bp->b_pages[i]; 1565 bp->b_pages[i] = NULL; 1566 /* 1567 * In order to keep page LRU ordering consistent, put 1568 * everything on the inactive queue. 1569 */ 1570 vm_page_lock(m); 1571 vm_page_unwire(m, 0); 1572 /* 1573 * We don't mess with busy pages, it is 1574 * the responsibility of the process that 1575 * busied the pages to deal with them. 1576 */ 1577 if ((m->oflags & VPO_BUSY) == 0 && m->busy == 0 && 1578 m->wire_count == 0) { 1579 /* 1580 * Might as well free the page if we can and it has 1581 * no valid data. We also free the page if the 1582 * buffer was used for direct I/O 1583 */ 1584 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1585 m->hold_count == 0) { 1586 vm_page_free(m); 1587 } else if (bp->b_flags & B_DIRECT) { 1588 vm_page_try_to_free(m); 1589 } else if (buf_vm_page_count_severe()) { 1590 vm_page_try_to_cache(m); 1591 } 1592 } 1593 vm_page_unlock(m); 1594 } 1595 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1596 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1597 1598 if (bp->b_bufsize) { 1599 bufspacewakeup(); 1600 bp->b_bufsize = 0; 1601 } 1602 bp->b_npages = 0; 1603 bp->b_flags &= ~B_VMIO; 1604 if (bp->b_vp) 1605 brelvp(bp); 1606 } 1607 1608 /* 1609 * Check to see if a block at a particular lbn is available for a clustered 1610 * write. 1611 */ 1612 static int 1613 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1614 { 1615 struct buf *bpa; 1616 int match; 1617 1618 match = 0; 1619 1620 /* If the buf isn't in core skip it */ 1621 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1622 return (0); 1623 1624 /* If the buf is busy we don't want to wait for it */ 1625 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1626 return (0); 1627 1628 /* Only cluster with valid clusterable delayed write buffers */ 1629 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1630 (B_DELWRI | B_CLUSTEROK)) 1631 goto done; 1632 1633 if (bpa->b_bufsize != size) 1634 goto done; 1635 1636 /* 1637 * Check to see if it is in the expected place on disk and that the 1638 * block has been mapped. 1639 */ 1640 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1641 match = 1; 1642 done: 1643 BUF_UNLOCK(bpa); 1644 return (match); 1645 } 1646 1647 /* 1648 * vfs_bio_awrite: 1649 * 1650 * Implement clustered async writes for clearing out B_DELWRI buffers. 1651 * This is much better then the old way of writing only one buffer at 1652 * a time. Note that we may not be presented with the buffers in the 1653 * correct order, so we search for the cluster in both directions. 1654 */ 1655 int 1656 vfs_bio_awrite(struct buf *bp) 1657 { 1658 struct bufobj *bo; 1659 int i; 1660 int j; 1661 daddr_t lblkno = bp->b_lblkno; 1662 struct vnode *vp = bp->b_vp; 1663 int ncl; 1664 int nwritten; 1665 int size; 1666 int maxcl; 1667 1668 bo = &vp->v_bufobj; 1669 /* 1670 * right now we support clustered writing only to regular files. If 1671 * we find a clusterable block we could be in the middle of a cluster 1672 * rather then at the beginning. 1673 */ 1674 if ((vp->v_type == VREG) && 1675 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1676 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1677 1678 size = vp->v_mount->mnt_stat.f_iosize; 1679 maxcl = MAXPHYS / size; 1680 1681 BO_LOCK(bo); 1682 for (i = 1; i < maxcl; i++) 1683 if (vfs_bio_clcheck(vp, size, lblkno + i, 1684 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1685 break; 1686 1687 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1688 if (vfs_bio_clcheck(vp, size, lblkno - j, 1689 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1690 break; 1691 BO_UNLOCK(bo); 1692 --j; 1693 ncl = i + j; 1694 /* 1695 * this is a possible cluster write 1696 */ 1697 if (ncl != 1) { 1698 BUF_UNLOCK(bp); 1699 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1700 return nwritten; 1701 } 1702 } 1703 bremfree(bp); 1704 bp->b_flags |= B_ASYNC; 1705 /* 1706 * default (old) behavior, writing out only one block 1707 * 1708 * XXX returns b_bufsize instead of b_bcount for nwritten? 1709 */ 1710 nwritten = bp->b_bufsize; 1711 (void) bwrite(bp); 1712 1713 return nwritten; 1714 } 1715 1716 /* 1717 * getnewbuf: 1718 * 1719 * Find and initialize a new buffer header, freeing up existing buffers 1720 * in the bufqueues as necessary. The new buffer is returned locked. 1721 * 1722 * Important: B_INVAL is not set. If the caller wishes to throw the 1723 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1724 * 1725 * We block if: 1726 * We have insufficient buffer headers 1727 * We have insufficient buffer space 1728 * buffer_map is too fragmented ( space reservation fails ) 1729 * If we have to flush dirty buffers ( but we try to avoid this ) 1730 * 1731 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1732 * Instead we ask the buf daemon to do it for us. We attempt to 1733 * avoid piecemeal wakeups of the pageout daemon. 1734 */ 1735 1736 static struct buf * 1737 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1738 int gbflags) 1739 { 1740 struct thread *td; 1741 struct buf *bp; 1742 struct buf *nbp; 1743 int defrag = 0; 1744 int nqindex; 1745 static int flushingbufs; 1746 1747 td = curthread; 1748 /* 1749 * We can't afford to block since we might be holding a vnode lock, 1750 * which may prevent system daemons from running. We deal with 1751 * low-memory situations by proactively returning memory and running 1752 * async I/O rather then sync I/O. 1753 */ 1754 atomic_add_int(&getnewbufcalls, 1); 1755 atomic_subtract_int(&getnewbufrestarts, 1); 1756 restart: 1757 atomic_add_int(&getnewbufrestarts, 1); 1758 1759 /* 1760 * Setup for scan. If we do not have enough free buffers, 1761 * we setup a degenerate case that immediately fails. Note 1762 * that if we are specially marked process, we are allowed to 1763 * dip into our reserves. 1764 * 1765 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1766 * 1767 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1768 * However, there are a number of cases (defragging, reusing, ...) 1769 * where we cannot backup. 1770 */ 1771 mtx_lock(&bqlock); 1772 nqindex = QUEUE_EMPTYKVA; 1773 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1774 1775 if (nbp == NULL) { 1776 /* 1777 * If no EMPTYKVA buffers and we are either 1778 * defragging or reusing, locate a CLEAN buffer 1779 * to free or reuse. If bufspace useage is low 1780 * skip this step so we can allocate a new buffer. 1781 */ 1782 if (defrag || bufspace >= lobufspace) { 1783 nqindex = QUEUE_CLEAN; 1784 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1785 } 1786 1787 /* 1788 * If we could not find or were not allowed to reuse a 1789 * CLEAN buffer, check to see if it is ok to use an EMPTY 1790 * buffer. We can only use an EMPTY buffer if allocating 1791 * its KVA would not otherwise run us out of buffer space. 1792 */ 1793 if (nbp == NULL && defrag == 0 && 1794 bufspace + maxsize < hibufspace) { 1795 nqindex = QUEUE_EMPTY; 1796 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1797 } 1798 } 1799 1800 /* 1801 * Run scan, possibly freeing data and/or kva mappings on the fly 1802 * depending. 1803 */ 1804 1805 while ((bp = nbp) != NULL) { 1806 int qindex = nqindex; 1807 1808 /* 1809 * Calculate next bp ( we can only use it if we do not block 1810 * or do other fancy things ). 1811 */ 1812 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1813 switch(qindex) { 1814 case QUEUE_EMPTY: 1815 nqindex = QUEUE_EMPTYKVA; 1816 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1817 break; 1818 /* FALLTHROUGH */ 1819 case QUEUE_EMPTYKVA: 1820 nqindex = QUEUE_CLEAN; 1821 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1822 break; 1823 /* FALLTHROUGH */ 1824 case QUEUE_CLEAN: 1825 /* 1826 * nbp is NULL. 1827 */ 1828 break; 1829 } 1830 } 1831 /* 1832 * If we are defragging then we need a buffer with 1833 * b_kvasize != 0. XXX this situation should no longer 1834 * occur, if defrag is non-zero the buffer's b_kvasize 1835 * should also be non-zero at this point. XXX 1836 */ 1837 if (defrag && bp->b_kvasize == 0) { 1838 printf("Warning: defrag empty buffer %p\n", bp); 1839 continue; 1840 } 1841 1842 /* 1843 * Start freeing the bp. This is somewhat involved. nbp 1844 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1845 */ 1846 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1847 continue; 1848 if (bp->b_vp) { 1849 BO_LOCK(bp->b_bufobj); 1850 if (bp->b_vflags & BV_BKGRDINPROG) { 1851 BO_UNLOCK(bp->b_bufobj); 1852 BUF_UNLOCK(bp); 1853 continue; 1854 } 1855 BO_UNLOCK(bp->b_bufobj); 1856 } 1857 CTR6(KTR_BUF, 1858 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1859 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1860 bp->b_kvasize, bp->b_bufsize, qindex); 1861 1862 /* 1863 * Sanity Checks 1864 */ 1865 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1866 1867 /* 1868 * Note: we no longer distinguish between VMIO and non-VMIO 1869 * buffers. 1870 */ 1871 1872 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1873 1874 bremfreel(bp); 1875 mtx_unlock(&bqlock); 1876 1877 if (qindex == QUEUE_CLEAN) { 1878 if (bp->b_flags & B_VMIO) { 1879 bp->b_flags &= ~B_ASYNC; 1880 vfs_vmio_release(bp); 1881 } 1882 if (bp->b_vp) 1883 brelvp(bp); 1884 } 1885 1886 /* 1887 * NOTE: nbp is now entirely invalid. We can only restart 1888 * the scan from this point on. 1889 * 1890 * Get the rest of the buffer freed up. b_kva* is still 1891 * valid after this operation. 1892 */ 1893 1894 if (bp->b_rcred != NOCRED) { 1895 crfree(bp->b_rcred); 1896 bp->b_rcred = NOCRED; 1897 } 1898 if (bp->b_wcred != NOCRED) { 1899 crfree(bp->b_wcred); 1900 bp->b_wcred = NOCRED; 1901 } 1902 if (!LIST_EMPTY(&bp->b_dep)) 1903 buf_deallocate(bp); 1904 if (bp->b_vflags & BV_BKGRDINPROG) 1905 panic("losing buffer 3"); 1906 KASSERT(bp->b_vp == NULL, 1907 ("bp: %p still has vnode %p. qindex: %d", 1908 bp, bp->b_vp, qindex)); 1909 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1910 ("bp: %p still on a buffer list. xflags %X", 1911 bp, bp->b_xflags)); 1912 1913 if (bp->b_bufsize) 1914 allocbuf(bp, 0); 1915 1916 bp->b_flags = 0; 1917 bp->b_ioflags = 0; 1918 bp->b_xflags = 0; 1919 bp->b_vflags = 0; 1920 bp->b_vp = NULL; 1921 bp->b_blkno = bp->b_lblkno = 0; 1922 bp->b_offset = NOOFFSET; 1923 bp->b_iodone = 0; 1924 bp->b_error = 0; 1925 bp->b_resid = 0; 1926 bp->b_bcount = 0; 1927 bp->b_npages = 0; 1928 bp->b_dirtyoff = bp->b_dirtyend = 0; 1929 bp->b_bufobj = NULL; 1930 bp->b_pin_count = 0; 1931 bp->b_fsprivate1 = NULL; 1932 bp->b_fsprivate2 = NULL; 1933 bp->b_fsprivate3 = NULL; 1934 1935 LIST_INIT(&bp->b_dep); 1936 1937 /* 1938 * If we are defragging then free the buffer. 1939 */ 1940 if (defrag) { 1941 bp->b_flags |= B_INVAL; 1942 bfreekva(bp); 1943 brelse(bp); 1944 defrag = 0; 1945 goto restart; 1946 } 1947 1948 /* 1949 * Notify any waiters for the buffer lock about 1950 * identity change by freeing the buffer. 1951 */ 1952 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 1953 bp->b_flags |= B_INVAL; 1954 bfreekva(bp); 1955 brelse(bp); 1956 goto restart; 1957 } 1958 1959 /* 1960 * If we are overcomitted then recover the buffer and its 1961 * KVM space. This occurs in rare situations when multiple 1962 * processes are blocked in getnewbuf() or allocbuf(). 1963 */ 1964 if (bufspace >= hibufspace) 1965 flushingbufs = 1; 1966 if (flushingbufs && bp->b_kvasize != 0) { 1967 bp->b_flags |= B_INVAL; 1968 bfreekva(bp); 1969 brelse(bp); 1970 goto restart; 1971 } 1972 if (bufspace < lobufspace) 1973 flushingbufs = 0; 1974 break; 1975 } 1976 1977 /* 1978 * If we exhausted our list, sleep as appropriate. We may have to 1979 * wakeup various daemons and write out some dirty buffers. 1980 * 1981 * Generally we are sleeping due to insufficient buffer space. 1982 */ 1983 1984 if (bp == NULL) { 1985 int flags, norunbuf; 1986 char *waitmsg; 1987 int fl; 1988 1989 if (defrag) { 1990 flags = VFS_BIO_NEED_BUFSPACE; 1991 waitmsg = "nbufkv"; 1992 } else if (bufspace >= hibufspace) { 1993 waitmsg = "nbufbs"; 1994 flags = VFS_BIO_NEED_BUFSPACE; 1995 } else { 1996 waitmsg = "newbuf"; 1997 flags = VFS_BIO_NEED_ANY; 1998 } 1999 mtx_lock(&nblock); 2000 needsbuffer |= flags; 2001 mtx_unlock(&nblock); 2002 mtx_unlock(&bqlock); 2003 2004 bd_speedup(); /* heeeelp */ 2005 if (gbflags & GB_NOWAIT_BD) 2006 return (NULL); 2007 2008 mtx_lock(&nblock); 2009 while (needsbuffer & flags) { 2010 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2011 mtx_unlock(&nblock); 2012 /* 2013 * getblk() is called with a vnode 2014 * locked, and some majority of the 2015 * dirty buffers may as well belong to 2016 * the vnode. Flushing the buffers 2017 * there would make a progress that 2018 * cannot be achieved by the 2019 * buf_daemon, that cannot lock the 2020 * vnode. 2021 */ 2022 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2023 (td->td_pflags & TDP_NORUNNINGBUF); 2024 /* play bufdaemon */ 2025 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2026 fl = buf_do_flush(vp); 2027 td->td_pflags &= norunbuf; 2028 mtx_lock(&nblock); 2029 if (fl != 0) 2030 continue; 2031 if ((needsbuffer & flags) == 0) 2032 break; 2033 } 2034 if (msleep(&needsbuffer, &nblock, 2035 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2036 mtx_unlock(&nblock); 2037 return (NULL); 2038 } 2039 } 2040 mtx_unlock(&nblock); 2041 } else { 2042 /* 2043 * We finally have a valid bp. We aren't quite out of the 2044 * woods, we still have to reserve kva space. In order 2045 * to keep fragmentation sane we only allocate kva in 2046 * BKVASIZE chunks. 2047 */ 2048 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2049 2050 if (maxsize != bp->b_kvasize) { 2051 vm_offset_t addr = 0; 2052 2053 bfreekva(bp); 2054 2055 vm_map_lock(buffer_map); 2056 if (vm_map_findspace(buffer_map, 2057 vm_map_min(buffer_map), maxsize, &addr)) { 2058 /* 2059 * Uh oh. Buffer map is to fragmented. We 2060 * must defragment the map. 2061 */ 2062 atomic_add_int(&bufdefragcnt, 1); 2063 vm_map_unlock(buffer_map); 2064 defrag = 1; 2065 bp->b_flags |= B_INVAL; 2066 brelse(bp); 2067 goto restart; 2068 } 2069 if (addr) { 2070 vm_map_insert(buffer_map, NULL, 0, 2071 addr, addr + maxsize, 2072 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2073 2074 bp->b_kvabase = (caddr_t) addr; 2075 bp->b_kvasize = maxsize; 2076 atomic_add_long(&bufspace, bp->b_kvasize); 2077 atomic_add_int(&bufreusecnt, 1); 2078 } 2079 vm_map_unlock(buffer_map); 2080 } 2081 bp->b_saveaddr = bp->b_kvabase; 2082 bp->b_data = bp->b_saveaddr; 2083 } 2084 return(bp); 2085 } 2086 2087 /* 2088 * buf_daemon: 2089 * 2090 * buffer flushing daemon. Buffers are normally flushed by the 2091 * update daemon but if it cannot keep up this process starts to 2092 * take the load in an attempt to prevent getnewbuf() from blocking. 2093 */ 2094 2095 static struct kproc_desc buf_kp = { 2096 "bufdaemon", 2097 buf_daemon, 2098 &bufdaemonproc 2099 }; 2100 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2101 2102 static int 2103 buf_do_flush(struct vnode *vp) 2104 { 2105 int flushed; 2106 2107 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2108 /* The list empty check here is slightly racy */ 2109 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2110 mtx_lock(&Giant); 2111 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0); 2112 mtx_unlock(&Giant); 2113 } 2114 if (flushed == 0) { 2115 /* 2116 * Could not find any buffers without rollback 2117 * dependencies, so just write the first one 2118 * in the hopes of eventually making progress. 2119 */ 2120 flushbufqueues(vp, QUEUE_DIRTY, 1); 2121 if (!TAILQ_EMPTY( 2122 &bufqueues[QUEUE_DIRTY_GIANT])) { 2123 mtx_lock(&Giant); 2124 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1); 2125 mtx_unlock(&Giant); 2126 } 2127 } 2128 return (flushed); 2129 } 2130 2131 static void 2132 buf_daemon() 2133 { 2134 int lodirtysave; 2135 2136 /* 2137 * This process needs to be suspended prior to shutdown sync. 2138 */ 2139 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2140 SHUTDOWN_PRI_LAST); 2141 2142 /* 2143 * This process is allowed to take the buffer cache to the limit 2144 */ 2145 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2146 mtx_lock(&bdlock); 2147 for (;;) { 2148 bd_request = 0; 2149 mtx_unlock(&bdlock); 2150 2151 kproc_suspend_check(bufdaemonproc); 2152 lodirtysave = lodirtybuffers; 2153 if (bd_speedupreq) { 2154 lodirtybuffers = numdirtybuffers / 2; 2155 bd_speedupreq = 0; 2156 } 2157 /* 2158 * Do the flush. Limit the amount of in-transit I/O we 2159 * allow to build up, otherwise we would completely saturate 2160 * the I/O system. Wakeup any waiting processes before we 2161 * normally would so they can run in parallel with our drain. 2162 */ 2163 while (numdirtybuffers > lodirtybuffers) { 2164 if (buf_do_flush(NULL) == 0) 2165 break; 2166 uio_yield(); 2167 } 2168 lodirtybuffers = lodirtysave; 2169 2170 /* 2171 * Only clear bd_request if we have reached our low water 2172 * mark. The buf_daemon normally waits 1 second and 2173 * then incrementally flushes any dirty buffers that have 2174 * built up, within reason. 2175 * 2176 * If we were unable to hit our low water mark and couldn't 2177 * find any flushable buffers, we sleep half a second. 2178 * Otherwise we loop immediately. 2179 */ 2180 mtx_lock(&bdlock); 2181 if (numdirtybuffers <= lodirtybuffers) { 2182 /* 2183 * We reached our low water mark, reset the 2184 * request and sleep until we are needed again. 2185 * The sleep is just so the suspend code works. 2186 */ 2187 bd_request = 0; 2188 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2189 } else { 2190 /* 2191 * We couldn't find any flushable dirty buffers but 2192 * still have too many dirty buffers, we 2193 * have to sleep and try again. (rare) 2194 */ 2195 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2196 } 2197 } 2198 } 2199 2200 /* 2201 * flushbufqueues: 2202 * 2203 * Try to flush a buffer in the dirty queue. We must be careful to 2204 * free up B_INVAL buffers instead of write them, which NFS is 2205 * particularly sensitive to. 2206 */ 2207 static int flushwithdeps = 0; 2208 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2209 0, "Number of buffers flushed with dependecies that require rollbacks"); 2210 2211 static int 2212 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2213 { 2214 struct buf *sentinel; 2215 struct vnode *vp; 2216 struct mount *mp; 2217 struct buf *bp; 2218 int hasdeps; 2219 int flushed; 2220 int target; 2221 2222 if (lvp == NULL) { 2223 target = numdirtybuffers - lodirtybuffers; 2224 if (flushdeps && target > 2) 2225 target /= 2; 2226 } else 2227 target = flushbufqtarget; 2228 flushed = 0; 2229 bp = NULL; 2230 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2231 sentinel->b_qindex = QUEUE_SENTINEL; 2232 mtx_lock(&bqlock); 2233 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2234 while (flushed != target) { 2235 bp = TAILQ_NEXT(sentinel, b_freelist); 2236 if (bp != NULL) { 2237 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2238 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2239 b_freelist); 2240 } else 2241 break; 2242 /* 2243 * Skip sentinels inserted by other invocations of the 2244 * flushbufqueues(), taking care to not reorder them. 2245 */ 2246 if (bp->b_qindex == QUEUE_SENTINEL) 2247 continue; 2248 /* 2249 * Only flush the buffers that belong to the 2250 * vnode locked by the curthread. 2251 */ 2252 if (lvp != NULL && bp->b_vp != lvp) 2253 continue; 2254 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2255 continue; 2256 if (bp->b_pin_count > 0) { 2257 BUF_UNLOCK(bp); 2258 continue; 2259 } 2260 BO_LOCK(bp->b_bufobj); 2261 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2262 (bp->b_flags & B_DELWRI) == 0) { 2263 BO_UNLOCK(bp->b_bufobj); 2264 BUF_UNLOCK(bp); 2265 continue; 2266 } 2267 BO_UNLOCK(bp->b_bufobj); 2268 if (bp->b_flags & B_INVAL) { 2269 bremfreel(bp); 2270 mtx_unlock(&bqlock); 2271 brelse(bp); 2272 flushed++; 2273 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2274 mtx_lock(&bqlock); 2275 continue; 2276 } 2277 2278 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2279 if (flushdeps == 0) { 2280 BUF_UNLOCK(bp); 2281 continue; 2282 } 2283 hasdeps = 1; 2284 } else 2285 hasdeps = 0; 2286 /* 2287 * We must hold the lock on a vnode before writing 2288 * one of its buffers. Otherwise we may confuse, or 2289 * in the case of a snapshot vnode, deadlock the 2290 * system. 2291 * 2292 * The lock order here is the reverse of the normal 2293 * of vnode followed by buf lock. This is ok because 2294 * the NOWAIT will prevent deadlock. 2295 */ 2296 vp = bp->b_vp; 2297 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2298 BUF_UNLOCK(bp); 2299 continue; 2300 } 2301 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2302 mtx_unlock(&bqlock); 2303 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2304 bp, bp->b_vp, bp->b_flags); 2305 if (curproc == bufdaemonproc) 2306 vfs_bio_awrite(bp); 2307 else { 2308 bremfree(bp); 2309 bwrite(bp); 2310 notbufdflashes++; 2311 } 2312 vn_finished_write(mp); 2313 VOP_UNLOCK(vp, 0); 2314 flushwithdeps += hasdeps; 2315 flushed++; 2316 2317 /* 2318 * Sleeping on runningbufspace while holding 2319 * vnode lock leads to deadlock. 2320 */ 2321 if (curproc == bufdaemonproc) 2322 waitrunningbufspace(); 2323 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2324 mtx_lock(&bqlock); 2325 continue; 2326 } 2327 vn_finished_write(mp); 2328 BUF_UNLOCK(bp); 2329 } 2330 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2331 mtx_unlock(&bqlock); 2332 free(sentinel, M_TEMP); 2333 return (flushed); 2334 } 2335 2336 /* 2337 * Check to see if a block is currently memory resident. 2338 */ 2339 struct buf * 2340 incore(struct bufobj *bo, daddr_t blkno) 2341 { 2342 struct buf *bp; 2343 2344 BO_LOCK(bo); 2345 bp = gbincore(bo, blkno); 2346 BO_UNLOCK(bo); 2347 return (bp); 2348 } 2349 2350 /* 2351 * Returns true if no I/O is needed to access the 2352 * associated VM object. This is like incore except 2353 * it also hunts around in the VM system for the data. 2354 */ 2355 2356 static int 2357 inmem(struct vnode * vp, daddr_t blkno) 2358 { 2359 vm_object_t obj; 2360 vm_offset_t toff, tinc, size; 2361 vm_page_t m; 2362 vm_ooffset_t off; 2363 2364 ASSERT_VOP_LOCKED(vp, "inmem"); 2365 2366 if (incore(&vp->v_bufobj, blkno)) 2367 return 1; 2368 if (vp->v_mount == NULL) 2369 return 0; 2370 obj = vp->v_object; 2371 if (obj == NULL) 2372 return (0); 2373 2374 size = PAGE_SIZE; 2375 if (size > vp->v_mount->mnt_stat.f_iosize) 2376 size = vp->v_mount->mnt_stat.f_iosize; 2377 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2378 2379 VM_OBJECT_LOCK(obj); 2380 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2381 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2382 if (!m) 2383 goto notinmem; 2384 tinc = size; 2385 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2386 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2387 if (vm_page_is_valid(m, 2388 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2389 goto notinmem; 2390 } 2391 VM_OBJECT_UNLOCK(obj); 2392 return 1; 2393 2394 notinmem: 2395 VM_OBJECT_UNLOCK(obj); 2396 return (0); 2397 } 2398 2399 /* 2400 * Set the dirty range for a buffer based on the status of the dirty 2401 * bits in the pages comprising the buffer. The range is limited 2402 * to the size of the buffer. 2403 * 2404 * Tell the VM system that the pages associated with this buffer 2405 * are clean. This is used for delayed writes where the data is 2406 * going to go to disk eventually without additional VM intevention. 2407 * 2408 * Note that while we only really need to clean through to b_bcount, we 2409 * just go ahead and clean through to b_bufsize. 2410 */ 2411 static void 2412 vfs_clean_pages_dirty_buf(struct buf *bp) 2413 { 2414 vm_ooffset_t foff, noff, eoff; 2415 vm_page_t m; 2416 int i; 2417 2418 if ((bp->b_flags & B_VMIO) == 0 || bp->b_bufsize == 0) 2419 return; 2420 2421 foff = bp->b_offset; 2422 KASSERT(bp->b_offset != NOOFFSET, 2423 ("vfs_clean_pages_dirty_buf: no buffer offset")); 2424 2425 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2426 vfs_drain_busy_pages(bp); 2427 vfs_setdirty_locked_object(bp); 2428 for (i = 0; i < bp->b_npages; i++) { 2429 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 2430 eoff = noff; 2431 if (eoff > bp->b_offset + bp->b_bufsize) 2432 eoff = bp->b_offset + bp->b_bufsize; 2433 m = bp->b_pages[i]; 2434 vfs_page_set_validclean(bp, foff, m); 2435 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 2436 foff = noff; 2437 } 2438 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2439 } 2440 2441 static void 2442 vfs_setdirty_locked_object(struct buf *bp) 2443 { 2444 vm_object_t object; 2445 int i; 2446 2447 object = bp->b_bufobj->bo_object; 2448 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2449 2450 /* 2451 * We qualify the scan for modified pages on whether the 2452 * object has been flushed yet. 2453 */ 2454 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2455 vm_offset_t boffset; 2456 vm_offset_t eoffset; 2457 2458 /* 2459 * test the pages to see if they have been modified directly 2460 * by users through the VM system. 2461 */ 2462 for (i = 0; i < bp->b_npages; i++) 2463 vm_page_test_dirty(bp->b_pages[i]); 2464 2465 /* 2466 * Calculate the encompassing dirty range, boffset and eoffset, 2467 * (eoffset - boffset) bytes. 2468 */ 2469 2470 for (i = 0; i < bp->b_npages; i++) { 2471 if (bp->b_pages[i]->dirty) 2472 break; 2473 } 2474 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2475 2476 for (i = bp->b_npages - 1; i >= 0; --i) { 2477 if (bp->b_pages[i]->dirty) { 2478 break; 2479 } 2480 } 2481 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2482 2483 /* 2484 * Fit it to the buffer. 2485 */ 2486 2487 if (eoffset > bp->b_bcount) 2488 eoffset = bp->b_bcount; 2489 2490 /* 2491 * If we have a good dirty range, merge with the existing 2492 * dirty range. 2493 */ 2494 2495 if (boffset < eoffset) { 2496 if (bp->b_dirtyoff > boffset) 2497 bp->b_dirtyoff = boffset; 2498 if (bp->b_dirtyend < eoffset) 2499 bp->b_dirtyend = eoffset; 2500 } 2501 } 2502 } 2503 2504 /* 2505 * getblk: 2506 * 2507 * Get a block given a specified block and offset into a file/device. 2508 * The buffers B_DONE bit will be cleared on return, making it almost 2509 * ready for an I/O initiation. B_INVAL may or may not be set on 2510 * return. The caller should clear B_INVAL prior to initiating a 2511 * READ. 2512 * 2513 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2514 * an existing buffer. 2515 * 2516 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2517 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2518 * and then cleared based on the backing VM. If the previous buffer is 2519 * non-0-sized but invalid, B_CACHE will be cleared. 2520 * 2521 * If getblk() must create a new buffer, the new buffer is returned with 2522 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2523 * case it is returned with B_INVAL clear and B_CACHE set based on the 2524 * backing VM. 2525 * 2526 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2527 * B_CACHE bit is clear. 2528 * 2529 * What this means, basically, is that the caller should use B_CACHE to 2530 * determine whether the buffer is fully valid or not and should clear 2531 * B_INVAL prior to issuing a read. If the caller intends to validate 2532 * the buffer by loading its data area with something, the caller needs 2533 * to clear B_INVAL. If the caller does this without issuing an I/O, 2534 * the caller should set B_CACHE ( as an optimization ), else the caller 2535 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2536 * a write attempt or if it was a successfull read. If the caller 2537 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2538 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2539 */ 2540 struct buf * 2541 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2542 int flags) 2543 { 2544 struct buf *bp; 2545 struct bufobj *bo; 2546 int error; 2547 2548 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2549 ASSERT_VOP_LOCKED(vp, "getblk"); 2550 if (size > MAXBSIZE) 2551 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2552 2553 bo = &vp->v_bufobj; 2554 loop: 2555 /* 2556 * Block if we are low on buffers. Certain processes are allowed 2557 * to completely exhaust the buffer cache. 2558 * 2559 * If this check ever becomes a bottleneck it may be better to 2560 * move it into the else, when gbincore() fails. At the moment 2561 * it isn't a problem. 2562 * 2563 * XXX remove if 0 sections (clean this up after its proven) 2564 */ 2565 if (numfreebuffers == 0) { 2566 if (TD_IS_IDLETHREAD(curthread)) 2567 return NULL; 2568 mtx_lock(&nblock); 2569 needsbuffer |= VFS_BIO_NEED_ANY; 2570 mtx_unlock(&nblock); 2571 } 2572 2573 BO_LOCK(bo); 2574 bp = gbincore(bo, blkno); 2575 if (bp != NULL) { 2576 int lockflags; 2577 /* 2578 * Buffer is in-core. If the buffer is not busy, it must 2579 * be on a queue. 2580 */ 2581 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2582 2583 if (flags & GB_LOCK_NOWAIT) 2584 lockflags |= LK_NOWAIT; 2585 2586 error = BUF_TIMELOCK(bp, lockflags, 2587 BO_MTX(bo), "getblk", slpflag, slptimeo); 2588 2589 /* 2590 * If we slept and got the lock we have to restart in case 2591 * the buffer changed identities. 2592 */ 2593 if (error == ENOLCK) 2594 goto loop; 2595 /* We timed out or were interrupted. */ 2596 else if (error) 2597 return (NULL); 2598 2599 /* 2600 * The buffer is locked. B_CACHE is cleared if the buffer is 2601 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2602 * and for a VMIO buffer B_CACHE is adjusted according to the 2603 * backing VM cache. 2604 */ 2605 if (bp->b_flags & B_INVAL) 2606 bp->b_flags &= ~B_CACHE; 2607 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2608 bp->b_flags |= B_CACHE; 2609 bremfree(bp); 2610 2611 /* 2612 * check for size inconsistancies for non-VMIO case. 2613 */ 2614 2615 if (bp->b_bcount != size) { 2616 if ((bp->b_flags & B_VMIO) == 0 || 2617 (size > bp->b_kvasize)) { 2618 if (bp->b_flags & B_DELWRI) { 2619 /* 2620 * If buffer is pinned and caller does 2621 * not want sleep waiting for it to be 2622 * unpinned, bail out 2623 * */ 2624 if (bp->b_pin_count > 0) { 2625 if (flags & GB_LOCK_NOWAIT) { 2626 bqrelse(bp); 2627 return (NULL); 2628 } else { 2629 bunpin_wait(bp); 2630 } 2631 } 2632 bp->b_flags |= B_NOCACHE; 2633 bwrite(bp); 2634 } else { 2635 if (LIST_EMPTY(&bp->b_dep)) { 2636 bp->b_flags |= B_RELBUF; 2637 brelse(bp); 2638 } else { 2639 bp->b_flags |= B_NOCACHE; 2640 bwrite(bp); 2641 } 2642 } 2643 goto loop; 2644 } 2645 } 2646 2647 /* 2648 * If the size is inconsistant in the VMIO case, we can resize 2649 * the buffer. This might lead to B_CACHE getting set or 2650 * cleared. If the size has not changed, B_CACHE remains 2651 * unchanged from its previous state. 2652 */ 2653 2654 if (bp->b_bcount != size) 2655 allocbuf(bp, size); 2656 2657 KASSERT(bp->b_offset != NOOFFSET, 2658 ("getblk: no buffer offset")); 2659 2660 /* 2661 * A buffer with B_DELWRI set and B_CACHE clear must 2662 * be committed before we can return the buffer in 2663 * order to prevent the caller from issuing a read 2664 * ( due to B_CACHE not being set ) and overwriting 2665 * it. 2666 * 2667 * Most callers, including NFS and FFS, need this to 2668 * operate properly either because they assume they 2669 * can issue a read if B_CACHE is not set, or because 2670 * ( for example ) an uncached B_DELWRI might loop due 2671 * to softupdates re-dirtying the buffer. In the latter 2672 * case, B_CACHE is set after the first write completes, 2673 * preventing further loops. 2674 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2675 * above while extending the buffer, we cannot allow the 2676 * buffer to remain with B_CACHE set after the write 2677 * completes or it will represent a corrupt state. To 2678 * deal with this we set B_NOCACHE to scrap the buffer 2679 * after the write. 2680 * 2681 * We might be able to do something fancy, like setting 2682 * B_CACHE in bwrite() except if B_DELWRI is already set, 2683 * so the below call doesn't set B_CACHE, but that gets real 2684 * confusing. This is much easier. 2685 */ 2686 2687 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2688 bp->b_flags |= B_NOCACHE; 2689 bwrite(bp); 2690 goto loop; 2691 } 2692 bp->b_flags &= ~B_DONE; 2693 } else { 2694 int bsize, maxsize, vmio; 2695 off_t offset; 2696 2697 /* 2698 * Buffer is not in-core, create new buffer. The buffer 2699 * returned by getnewbuf() is locked. Note that the returned 2700 * buffer is also considered valid (not marked B_INVAL). 2701 */ 2702 BO_UNLOCK(bo); 2703 /* 2704 * If the user does not want us to create the buffer, bail out 2705 * here. 2706 */ 2707 if (flags & GB_NOCREAT) 2708 return NULL; 2709 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 2710 offset = blkno * bsize; 2711 vmio = vp->v_object != NULL; 2712 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2713 maxsize = imax(maxsize, bsize); 2714 2715 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2716 if (bp == NULL) { 2717 if (slpflag || slptimeo) 2718 return NULL; 2719 goto loop; 2720 } 2721 2722 /* 2723 * This code is used to make sure that a buffer is not 2724 * created while the getnewbuf routine is blocked. 2725 * This can be a problem whether the vnode is locked or not. 2726 * If the buffer is created out from under us, we have to 2727 * throw away the one we just created. 2728 * 2729 * Note: this must occur before we associate the buffer 2730 * with the vp especially considering limitations in 2731 * the splay tree implementation when dealing with duplicate 2732 * lblkno's. 2733 */ 2734 BO_LOCK(bo); 2735 if (gbincore(bo, blkno)) { 2736 BO_UNLOCK(bo); 2737 bp->b_flags |= B_INVAL; 2738 brelse(bp); 2739 goto loop; 2740 } 2741 2742 /* 2743 * Insert the buffer into the hash, so that it can 2744 * be found by incore. 2745 */ 2746 bp->b_blkno = bp->b_lblkno = blkno; 2747 bp->b_offset = offset; 2748 bgetvp(vp, bp); 2749 BO_UNLOCK(bo); 2750 2751 /* 2752 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2753 * buffer size starts out as 0, B_CACHE will be set by 2754 * allocbuf() for the VMIO case prior to it testing the 2755 * backing store for validity. 2756 */ 2757 2758 if (vmio) { 2759 bp->b_flags |= B_VMIO; 2760 #if defined(VFS_BIO_DEBUG) 2761 if (vn_canvmio(vp) != TRUE) 2762 printf("getblk: VMIO on vnode type %d\n", 2763 vp->v_type); 2764 #endif 2765 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2766 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2767 bp, vp->v_object, bp->b_bufobj->bo_object)); 2768 } else { 2769 bp->b_flags &= ~B_VMIO; 2770 KASSERT(bp->b_bufobj->bo_object == NULL, 2771 ("ARGH! has b_bufobj->bo_object %p %p\n", 2772 bp, bp->b_bufobj->bo_object)); 2773 } 2774 2775 allocbuf(bp, size); 2776 bp->b_flags &= ~B_DONE; 2777 } 2778 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2779 BUF_ASSERT_HELD(bp); 2780 KASSERT(bp->b_bufobj == bo, 2781 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2782 return (bp); 2783 } 2784 2785 /* 2786 * Get an empty, disassociated buffer of given size. The buffer is initially 2787 * set to B_INVAL. 2788 */ 2789 struct buf * 2790 geteblk(int size, int flags) 2791 { 2792 struct buf *bp; 2793 int maxsize; 2794 2795 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2796 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2797 if ((flags & GB_NOWAIT_BD) && 2798 (curthread->td_pflags & TDP_BUFNEED) != 0) 2799 return (NULL); 2800 } 2801 allocbuf(bp, size); 2802 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2803 BUF_ASSERT_HELD(bp); 2804 return (bp); 2805 } 2806 2807 2808 /* 2809 * This code constitutes the buffer memory from either anonymous system 2810 * memory (in the case of non-VMIO operations) or from an associated 2811 * VM object (in the case of VMIO operations). This code is able to 2812 * resize a buffer up or down. 2813 * 2814 * Note that this code is tricky, and has many complications to resolve 2815 * deadlock or inconsistant data situations. Tread lightly!!! 2816 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2817 * the caller. Calling this code willy nilly can result in the loss of data. 2818 * 2819 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2820 * B_CACHE for the non-VMIO case. 2821 */ 2822 2823 int 2824 allocbuf(struct buf *bp, int size) 2825 { 2826 int newbsize, mbsize; 2827 int i; 2828 2829 BUF_ASSERT_HELD(bp); 2830 2831 if (bp->b_kvasize < size) 2832 panic("allocbuf: buffer too small"); 2833 2834 if ((bp->b_flags & B_VMIO) == 0) { 2835 caddr_t origbuf; 2836 int origbufsize; 2837 /* 2838 * Just get anonymous memory from the kernel. Don't 2839 * mess with B_CACHE. 2840 */ 2841 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2842 if (bp->b_flags & B_MALLOC) 2843 newbsize = mbsize; 2844 else 2845 newbsize = round_page(size); 2846 2847 if (newbsize < bp->b_bufsize) { 2848 /* 2849 * malloced buffers are not shrunk 2850 */ 2851 if (bp->b_flags & B_MALLOC) { 2852 if (newbsize) { 2853 bp->b_bcount = size; 2854 } else { 2855 free(bp->b_data, M_BIOBUF); 2856 if (bp->b_bufsize) { 2857 atomic_subtract_long( 2858 &bufmallocspace, 2859 bp->b_bufsize); 2860 bufspacewakeup(); 2861 bp->b_bufsize = 0; 2862 } 2863 bp->b_saveaddr = bp->b_kvabase; 2864 bp->b_data = bp->b_saveaddr; 2865 bp->b_bcount = 0; 2866 bp->b_flags &= ~B_MALLOC; 2867 } 2868 return 1; 2869 } 2870 vm_hold_free_pages( 2871 bp, 2872 (vm_offset_t) bp->b_data + newbsize, 2873 (vm_offset_t) bp->b_data + bp->b_bufsize); 2874 } else if (newbsize > bp->b_bufsize) { 2875 /* 2876 * We only use malloced memory on the first allocation. 2877 * and revert to page-allocated memory when the buffer 2878 * grows. 2879 */ 2880 /* 2881 * There is a potential smp race here that could lead 2882 * to bufmallocspace slightly passing the max. It 2883 * is probably extremely rare and not worth worrying 2884 * over. 2885 */ 2886 if ( (bufmallocspace < maxbufmallocspace) && 2887 (bp->b_bufsize == 0) && 2888 (mbsize <= PAGE_SIZE/2)) { 2889 2890 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2891 bp->b_bufsize = mbsize; 2892 bp->b_bcount = size; 2893 bp->b_flags |= B_MALLOC; 2894 atomic_add_long(&bufmallocspace, mbsize); 2895 return 1; 2896 } 2897 origbuf = NULL; 2898 origbufsize = 0; 2899 /* 2900 * If the buffer is growing on its other-than-first allocation, 2901 * then we revert to the page-allocation scheme. 2902 */ 2903 if (bp->b_flags & B_MALLOC) { 2904 origbuf = bp->b_data; 2905 origbufsize = bp->b_bufsize; 2906 bp->b_data = bp->b_kvabase; 2907 if (bp->b_bufsize) { 2908 atomic_subtract_long(&bufmallocspace, 2909 bp->b_bufsize); 2910 bufspacewakeup(); 2911 bp->b_bufsize = 0; 2912 } 2913 bp->b_flags &= ~B_MALLOC; 2914 newbsize = round_page(newbsize); 2915 } 2916 vm_hold_load_pages( 2917 bp, 2918 (vm_offset_t) bp->b_data + bp->b_bufsize, 2919 (vm_offset_t) bp->b_data + newbsize); 2920 if (origbuf) { 2921 bcopy(origbuf, bp->b_data, origbufsize); 2922 free(origbuf, M_BIOBUF); 2923 } 2924 } 2925 } else { 2926 int desiredpages; 2927 2928 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2929 desiredpages = (size == 0) ? 0 : 2930 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2931 2932 if (bp->b_flags & B_MALLOC) 2933 panic("allocbuf: VMIO buffer can't be malloced"); 2934 /* 2935 * Set B_CACHE initially if buffer is 0 length or will become 2936 * 0-length. 2937 */ 2938 if (size == 0 || bp->b_bufsize == 0) 2939 bp->b_flags |= B_CACHE; 2940 2941 if (newbsize < bp->b_bufsize) { 2942 /* 2943 * DEV_BSIZE aligned new buffer size is less then the 2944 * DEV_BSIZE aligned existing buffer size. Figure out 2945 * if we have to remove any pages. 2946 */ 2947 if (desiredpages < bp->b_npages) { 2948 vm_page_t m; 2949 2950 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2951 for (i = desiredpages; i < bp->b_npages; i++) { 2952 /* 2953 * the page is not freed here -- it 2954 * is the responsibility of 2955 * vnode_pager_setsize 2956 */ 2957 m = bp->b_pages[i]; 2958 KASSERT(m != bogus_page, 2959 ("allocbuf: bogus page found")); 2960 while (vm_page_sleep_if_busy(m, TRUE, 2961 "biodep")) 2962 continue; 2963 2964 bp->b_pages[i] = NULL; 2965 vm_page_lock(m); 2966 vm_page_unwire(m, 0); 2967 vm_page_unlock(m); 2968 } 2969 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2970 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2971 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2972 bp->b_npages = desiredpages; 2973 } 2974 } else if (size > bp->b_bcount) { 2975 /* 2976 * We are growing the buffer, possibly in a 2977 * byte-granular fashion. 2978 */ 2979 vm_object_t obj; 2980 vm_offset_t toff; 2981 vm_offset_t tinc; 2982 2983 /* 2984 * Step 1, bring in the VM pages from the object, 2985 * allocating them if necessary. We must clear 2986 * B_CACHE if these pages are not valid for the 2987 * range covered by the buffer. 2988 */ 2989 2990 obj = bp->b_bufobj->bo_object; 2991 2992 VM_OBJECT_LOCK(obj); 2993 while (bp->b_npages < desiredpages) { 2994 vm_page_t m; 2995 vm_pindex_t pi; 2996 2997 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2998 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2999 /* 3000 * note: must allocate system pages 3001 * since blocking here could intefere 3002 * with paging I/O, no matter which 3003 * process we are. 3004 */ 3005 m = vm_page_alloc(obj, pi, 3006 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 3007 VM_ALLOC_WIRED); 3008 if (m == NULL) { 3009 atomic_add_int(&vm_pageout_deficit, 3010 desiredpages - bp->b_npages); 3011 VM_OBJECT_UNLOCK(obj); 3012 VM_WAIT; 3013 VM_OBJECT_LOCK(obj); 3014 } else { 3015 if (m->valid == 0) 3016 bp->b_flags &= ~B_CACHE; 3017 bp->b_pages[bp->b_npages] = m; 3018 ++bp->b_npages; 3019 } 3020 continue; 3021 } 3022 3023 /* 3024 * We found a page. If we have to sleep on it, 3025 * retry because it might have gotten freed out 3026 * from under us. 3027 * 3028 * We can only test VPO_BUSY here. Blocking on 3029 * m->busy might lead to a deadlock: 3030 * 3031 * vm_fault->getpages->cluster_read->allocbuf 3032 * 3033 */ 3034 if ((m->oflags & VPO_BUSY) != 0) { 3035 /* 3036 * Reference the page before unlocking 3037 * and sleeping so that the page daemon 3038 * is less likely to reclaim it. 3039 */ 3040 vm_page_lock_queues(); 3041 vm_page_flag_set(m, PG_REFERENCED); 3042 vm_page_sleep(m, "pgtblk"); 3043 continue; 3044 } 3045 3046 /* 3047 * We have a good page. 3048 */ 3049 vm_page_lock(m); 3050 vm_page_wire(m); 3051 vm_page_unlock(m); 3052 bp->b_pages[bp->b_npages] = m; 3053 ++bp->b_npages; 3054 } 3055 3056 /* 3057 * Step 2. We've loaded the pages into the buffer, 3058 * we have to figure out if we can still have B_CACHE 3059 * set. Note that B_CACHE is set according to the 3060 * byte-granular range ( bcount and size ), new the 3061 * aligned range ( newbsize ). 3062 * 3063 * The VM test is against m->valid, which is DEV_BSIZE 3064 * aligned. Needless to say, the validity of the data 3065 * needs to also be DEV_BSIZE aligned. Note that this 3066 * fails with NFS if the server or some other client 3067 * extends the file's EOF. If our buffer is resized, 3068 * B_CACHE may remain set! XXX 3069 */ 3070 3071 toff = bp->b_bcount; 3072 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3073 3074 while ((bp->b_flags & B_CACHE) && toff < size) { 3075 vm_pindex_t pi; 3076 3077 if (tinc > (size - toff)) 3078 tinc = size - toff; 3079 3080 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3081 PAGE_SHIFT; 3082 3083 vfs_buf_test_cache( 3084 bp, 3085 bp->b_offset, 3086 toff, 3087 tinc, 3088 bp->b_pages[pi] 3089 ); 3090 toff += tinc; 3091 tinc = PAGE_SIZE; 3092 } 3093 VM_OBJECT_UNLOCK(obj); 3094 3095 /* 3096 * Step 3, fixup the KVM pmap. Remember that 3097 * bp->b_data is relative to bp->b_offset, but 3098 * bp->b_offset may be offset into the first page. 3099 */ 3100 3101 bp->b_data = (caddr_t) 3102 trunc_page((vm_offset_t)bp->b_data); 3103 pmap_qenter( 3104 (vm_offset_t)bp->b_data, 3105 bp->b_pages, 3106 bp->b_npages 3107 ); 3108 3109 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3110 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3111 } 3112 } 3113 if (newbsize < bp->b_bufsize) 3114 bufspacewakeup(); 3115 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3116 bp->b_bcount = size; /* requested buffer size */ 3117 return 1; 3118 } 3119 3120 void 3121 biodone(struct bio *bp) 3122 { 3123 struct mtx *mtxp; 3124 void (*done)(struct bio *); 3125 3126 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3127 mtx_lock(mtxp); 3128 bp->bio_flags |= BIO_DONE; 3129 done = bp->bio_done; 3130 if (done == NULL) 3131 wakeup(bp); 3132 mtx_unlock(mtxp); 3133 if (done != NULL) 3134 done(bp); 3135 } 3136 3137 /* 3138 * Wait for a BIO to finish. 3139 * 3140 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3141 * case is not yet clear. 3142 */ 3143 int 3144 biowait(struct bio *bp, const char *wchan) 3145 { 3146 struct mtx *mtxp; 3147 3148 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3149 mtx_lock(mtxp); 3150 while ((bp->bio_flags & BIO_DONE) == 0) 3151 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3152 mtx_unlock(mtxp); 3153 if (bp->bio_error != 0) 3154 return (bp->bio_error); 3155 if (!(bp->bio_flags & BIO_ERROR)) 3156 return (0); 3157 return (EIO); 3158 } 3159 3160 void 3161 biofinish(struct bio *bp, struct devstat *stat, int error) 3162 { 3163 3164 if (error) { 3165 bp->bio_error = error; 3166 bp->bio_flags |= BIO_ERROR; 3167 } 3168 if (stat != NULL) 3169 devstat_end_transaction_bio(stat, bp); 3170 biodone(bp); 3171 } 3172 3173 /* 3174 * bufwait: 3175 * 3176 * Wait for buffer I/O completion, returning error status. The buffer 3177 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3178 * error and cleared. 3179 */ 3180 int 3181 bufwait(struct buf *bp) 3182 { 3183 if (bp->b_iocmd == BIO_READ) 3184 bwait(bp, PRIBIO, "biord"); 3185 else 3186 bwait(bp, PRIBIO, "biowr"); 3187 if (bp->b_flags & B_EINTR) { 3188 bp->b_flags &= ~B_EINTR; 3189 return (EINTR); 3190 } 3191 if (bp->b_ioflags & BIO_ERROR) { 3192 return (bp->b_error ? bp->b_error : EIO); 3193 } else { 3194 return (0); 3195 } 3196 } 3197 3198 /* 3199 * Call back function from struct bio back up to struct buf. 3200 */ 3201 static void 3202 bufdonebio(struct bio *bip) 3203 { 3204 struct buf *bp; 3205 3206 bp = bip->bio_caller2; 3207 bp->b_resid = bp->b_bcount - bip->bio_completed; 3208 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3209 bp->b_ioflags = bip->bio_flags; 3210 bp->b_error = bip->bio_error; 3211 if (bp->b_error) 3212 bp->b_ioflags |= BIO_ERROR; 3213 bufdone(bp); 3214 g_destroy_bio(bip); 3215 } 3216 3217 void 3218 dev_strategy(struct cdev *dev, struct buf *bp) 3219 { 3220 struct cdevsw *csw; 3221 struct bio *bip; 3222 3223 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3224 panic("b_iocmd botch"); 3225 for (;;) { 3226 bip = g_new_bio(); 3227 if (bip != NULL) 3228 break; 3229 /* Try again later */ 3230 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3231 } 3232 bip->bio_cmd = bp->b_iocmd; 3233 bip->bio_offset = bp->b_iooffset; 3234 bip->bio_length = bp->b_bcount; 3235 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3236 bip->bio_data = bp->b_data; 3237 bip->bio_done = bufdonebio; 3238 bip->bio_caller2 = bp; 3239 bip->bio_dev = dev; 3240 KASSERT(dev->si_refcount > 0, 3241 ("dev_strategy on un-referenced struct cdev *(%s)", 3242 devtoname(dev))); 3243 csw = dev_refthread(dev); 3244 if (csw == NULL) { 3245 g_destroy_bio(bip); 3246 bp->b_error = ENXIO; 3247 bp->b_ioflags = BIO_ERROR; 3248 bufdone(bp); 3249 return; 3250 } 3251 (*csw->d_strategy)(bip); 3252 dev_relthread(dev); 3253 } 3254 3255 /* 3256 * bufdone: 3257 * 3258 * Finish I/O on a buffer, optionally calling a completion function. 3259 * This is usually called from an interrupt so process blocking is 3260 * not allowed. 3261 * 3262 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3263 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3264 * assuming B_INVAL is clear. 3265 * 3266 * For the VMIO case, we set B_CACHE if the op was a read and no 3267 * read error occured, or if the op was a write. B_CACHE is never 3268 * set if the buffer is invalid or otherwise uncacheable. 3269 * 3270 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3271 * initiator to leave B_INVAL set to brelse the buffer out of existance 3272 * in the biodone routine. 3273 */ 3274 void 3275 bufdone(struct buf *bp) 3276 { 3277 struct bufobj *dropobj; 3278 void (*biodone)(struct buf *); 3279 3280 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3281 dropobj = NULL; 3282 3283 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3284 BUF_ASSERT_HELD(bp); 3285 3286 runningbufwakeup(bp); 3287 if (bp->b_iocmd == BIO_WRITE) 3288 dropobj = bp->b_bufobj; 3289 /* call optional completion function if requested */ 3290 if (bp->b_iodone != NULL) { 3291 biodone = bp->b_iodone; 3292 bp->b_iodone = NULL; 3293 (*biodone) (bp); 3294 if (dropobj) 3295 bufobj_wdrop(dropobj); 3296 return; 3297 } 3298 3299 bufdone_finish(bp); 3300 3301 if (dropobj) 3302 bufobj_wdrop(dropobj); 3303 } 3304 3305 void 3306 bufdone_finish(struct buf *bp) 3307 { 3308 BUF_ASSERT_HELD(bp); 3309 3310 if (!LIST_EMPTY(&bp->b_dep)) 3311 buf_complete(bp); 3312 3313 if (bp->b_flags & B_VMIO) { 3314 int i; 3315 vm_ooffset_t foff; 3316 vm_page_t m; 3317 vm_object_t obj; 3318 int iosize; 3319 struct vnode *vp = bp->b_vp; 3320 3321 obj = bp->b_bufobj->bo_object; 3322 3323 #if defined(VFS_BIO_DEBUG) 3324 mp_fixme("usecount and vflag accessed without locks."); 3325 if (vp->v_usecount == 0) { 3326 panic("biodone: zero vnode ref count"); 3327 } 3328 3329 KASSERT(vp->v_object != NULL, 3330 ("biodone: vnode %p has no vm_object", vp)); 3331 #endif 3332 3333 foff = bp->b_offset; 3334 KASSERT(bp->b_offset != NOOFFSET, 3335 ("biodone: no buffer offset")); 3336 3337 VM_OBJECT_LOCK(obj); 3338 #if defined(VFS_BIO_DEBUG) 3339 if (obj->paging_in_progress < bp->b_npages) { 3340 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3341 obj->paging_in_progress, bp->b_npages); 3342 } 3343 #endif 3344 3345 /* 3346 * Set B_CACHE if the op was a normal read and no error 3347 * occured. B_CACHE is set for writes in the b*write() 3348 * routines. 3349 */ 3350 iosize = bp->b_bcount - bp->b_resid; 3351 if (bp->b_iocmd == BIO_READ && 3352 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3353 !(bp->b_ioflags & BIO_ERROR)) { 3354 bp->b_flags |= B_CACHE; 3355 } 3356 for (i = 0; i < bp->b_npages; i++) { 3357 int bogusflag = 0; 3358 int resid; 3359 3360 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3361 if (resid > iosize) 3362 resid = iosize; 3363 3364 /* 3365 * cleanup bogus pages, restoring the originals 3366 */ 3367 m = bp->b_pages[i]; 3368 if (m == bogus_page) { 3369 bogusflag = 1; 3370 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3371 if (m == NULL) 3372 panic("biodone: page disappeared!"); 3373 bp->b_pages[i] = m; 3374 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3375 bp->b_pages, bp->b_npages); 3376 } 3377 #if defined(VFS_BIO_DEBUG) 3378 if (OFF_TO_IDX(foff) != m->pindex) { 3379 printf( 3380 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3381 (intmax_t)foff, (uintmax_t)m->pindex); 3382 } 3383 #endif 3384 3385 /* 3386 * In the write case, the valid and clean bits are 3387 * already changed correctly ( see bdwrite() ), so we 3388 * only need to do this here in the read case. 3389 */ 3390 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3391 KASSERT((m->dirty & vm_page_bits(foff & 3392 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3393 " page %p has unexpected dirty bits", m)); 3394 vfs_page_set_valid(bp, foff, m); 3395 } 3396 3397 /* 3398 * when debugging new filesystems or buffer I/O methods, this 3399 * is the most common error that pops up. if you see this, you 3400 * have not set the page busy flag correctly!!! 3401 */ 3402 if (m->busy == 0) { 3403 printf("biodone: page busy < 0, " 3404 "pindex: %d, foff: 0x(%x,%x), " 3405 "resid: %d, index: %d\n", 3406 (int) m->pindex, (int)(foff >> 32), 3407 (int) foff & 0xffffffff, resid, i); 3408 if (!vn_isdisk(vp, NULL)) 3409 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3410 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3411 (intmax_t) bp->b_lblkno, 3412 bp->b_flags, bp->b_npages); 3413 else 3414 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3415 (intmax_t) bp->b_lblkno, 3416 bp->b_flags, bp->b_npages); 3417 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3418 (u_long)m->valid, (u_long)m->dirty, 3419 m->wire_count); 3420 panic("biodone: page busy < 0\n"); 3421 } 3422 vm_page_io_finish(m); 3423 vm_object_pip_subtract(obj, 1); 3424 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3425 iosize -= resid; 3426 } 3427 vm_object_pip_wakeupn(obj, 0); 3428 VM_OBJECT_UNLOCK(obj); 3429 } 3430 3431 /* 3432 * For asynchronous completions, release the buffer now. The brelse 3433 * will do a wakeup there if necessary - so no need to do a wakeup 3434 * here in the async case. The sync case always needs to do a wakeup. 3435 */ 3436 3437 if (bp->b_flags & B_ASYNC) { 3438 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3439 brelse(bp); 3440 else 3441 bqrelse(bp); 3442 } else 3443 bdone(bp); 3444 } 3445 3446 /* 3447 * This routine is called in lieu of iodone in the case of 3448 * incomplete I/O. This keeps the busy status for pages 3449 * consistant. 3450 */ 3451 void 3452 vfs_unbusy_pages(struct buf *bp) 3453 { 3454 int i; 3455 vm_object_t obj; 3456 vm_page_t m; 3457 3458 runningbufwakeup(bp); 3459 if (!(bp->b_flags & B_VMIO)) 3460 return; 3461 3462 obj = bp->b_bufobj->bo_object; 3463 VM_OBJECT_LOCK(obj); 3464 for (i = 0; i < bp->b_npages; i++) { 3465 m = bp->b_pages[i]; 3466 if (m == bogus_page) { 3467 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3468 if (!m) 3469 panic("vfs_unbusy_pages: page missing\n"); 3470 bp->b_pages[i] = m; 3471 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3472 bp->b_pages, bp->b_npages); 3473 } 3474 vm_object_pip_subtract(obj, 1); 3475 vm_page_io_finish(m); 3476 } 3477 vm_object_pip_wakeupn(obj, 0); 3478 VM_OBJECT_UNLOCK(obj); 3479 } 3480 3481 /* 3482 * vfs_page_set_valid: 3483 * 3484 * Set the valid bits in a page based on the supplied offset. The 3485 * range is restricted to the buffer's size. 3486 * 3487 * This routine is typically called after a read completes. 3488 */ 3489 static void 3490 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3491 { 3492 vm_ooffset_t eoff; 3493 3494 /* 3495 * Compute the end offset, eoff, such that [off, eoff) does not span a 3496 * page boundary and eoff is not greater than the end of the buffer. 3497 * The end of the buffer, in this case, is our file EOF, not the 3498 * allocation size of the buffer. 3499 */ 3500 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3501 if (eoff > bp->b_offset + bp->b_bcount) 3502 eoff = bp->b_offset + bp->b_bcount; 3503 3504 /* 3505 * Set valid range. This is typically the entire buffer and thus the 3506 * entire page. 3507 */ 3508 if (eoff > off) 3509 vm_page_set_valid(m, off & PAGE_MASK, eoff - off); 3510 } 3511 3512 /* 3513 * vfs_page_set_validclean: 3514 * 3515 * Set the valid bits and clear the dirty bits in a page based on the 3516 * supplied offset. The range is restricted to the buffer's size. 3517 */ 3518 static void 3519 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3520 { 3521 vm_ooffset_t soff, eoff; 3522 3523 /* 3524 * Start and end offsets in buffer. eoff - soff may not cross a 3525 * page boundry or cross the end of the buffer. The end of the 3526 * buffer, in this case, is our file EOF, not the allocation size 3527 * of the buffer. 3528 */ 3529 soff = off; 3530 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3531 if (eoff > bp->b_offset + bp->b_bcount) 3532 eoff = bp->b_offset + bp->b_bcount; 3533 3534 /* 3535 * Set valid range. This is typically the entire buffer and thus the 3536 * entire page. 3537 */ 3538 if (eoff > soff) { 3539 vm_page_set_validclean( 3540 m, 3541 (vm_offset_t) (soff & PAGE_MASK), 3542 (vm_offset_t) (eoff - soff) 3543 ); 3544 } 3545 } 3546 3547 /* 3548 * Ensure that all buffer pages are not busied by VPO_BUSY flag. If 3549 * any page is busy, drain the flag. 3550 */ 3551 static void 3552 vfs_drain_busy_pages(struct buf *bp) 3553 { 3554 vm_page_t m; 3555 int i, last_busied; 3556 3557 VM_OBJECT_LOCK_ASSERT(bp->b_bufobj->bo_object, MA_OWNED); 3558 last_busied = 0; 3559 for (i = 0; i < bp->b_npages; i++) { 3560 m = bp->b_pages[i]; 3561 if ((m->oflags & VPO_BUSY) != 0) { 3562 for (; last_busied < i; last_busied++) 3563 vm_page_busy(bp->b_pages[last_busied]); 3564 while ((m->oflags & VPO_BUSY) != 0) 3565 vm_page_sleep(m, "vbpage"); 3566 } 3567 } 3568 for (i = 0; i < last_busied; i++) 3569 vm_page_wakeup(bp->b_pages[i]); 3570 } 3571 3572 /* 3573 * This routine is called before a device strategy routine. 3574 * It is used to tell the VM system that paging I/O is in 3575 * progress, and treat the pages associated with the buffer 3576 * almost as being VPO_BUSY. Also the object paging_in_progress 3577 * flag is handled to make sure that the object doesn't become 3578 * inconsistant. 3579 * 3580 * Since I/O has not been initiated yet, certain buffer flags 3581 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3582 * and should be ignored. 3583 */ 3584 void 3585 vfs_busy_pages(struct buf *bp, int clear_modify) 3586 { 3587 int i, bogus; 3588 vm_object_t obj; 3589 vm_ooffset_t foff; 3590 vm_page_t m; 3591 3592 if (!(bp->b_flags & B_VMIO)) 3593 return; 3594 3595 obj = bp->b_bufobj->bo_object; 3596 foff = bp->b_offset; 3597 KASSERT(bp->b_offset != NOOFFSET, 3598 ("vfs_busy_pages: no buffer offset")); 3599 VM_OBJECT_LOCK(obj); 3600 vfs_drain_busy_pages(bp); 3601 if (bp->b_bufsize != 0) 3602 vfs_setdirty_locked_object(bp); 3603 bogus = 0; 3604 for (i = 0; i < bp->b_npages; i++) { 3605 m = bp->b_pages[i]; 3606 3607 if ((bp->b_flags & B_CLUSTER) == 0) { 3608 vm_object_pip_add(obj, 1); 3609 vm_page_io_start(m); 3610 } 3611 /* 3612 * When readying a buffer for a read ( i.e 3613 * clear_modify == 0 ), it is important to do 3614 * bogus_page replacement for valid pages in 3615 * partially instantiated buffers. Partially 3616 * instantiated buffers can, in turn, occur when 3617 * reconstituting a buffer from its VM backing store 3618 * base. We only have to do this if B_CACHE is 3619 * clear ( which causes the I/O to occur in the 3620 * first place ). The replacement prevents the read 3621 * I/O from overwriting potentially dirty VM-backed 3622 * pages. XXX bogus page replacement is, uh, bogus. 3623 * It may not work properly with small-block devices. 3624 * We need to find a better way. 3625 */ 3626 if (clear_modify) { 3627 pmap_remove_write(m); 3628 vfs_page_set_validclean(bp, foff, m); 3629 } else if (m->valid == VM_PAGE_BITS_ALL && 3630 (bp->b_flags & B_CACHE) == 0) { 3631 bp->b_pages[i] = bogus_page; 3632 bogus++; 3633 } 3634 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3635 } 3636 VM_OBJECT_UNLOCK(obj); 3637 if (bogus) 3638 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3639 bp->b_pages, bp->b_npages); 3640 } 3641 3642 /* 3643 * vfs_bio_set_valid: 3644 * 3645 * Set the range within the buffer to valid. The range is 3646 * relative to the beginning of the buffer, b_offset. Note that 3647 * b_offset itself may be offset from the beginning of the first 3648 * page. 3649 */ 3650 void 3651 vfs_bio_set_valid(struct buf *bp, int base, int size) 3652 { 3653 int i, n; 3654 vm_page_t m; 3655 3656 if (!(bp->b_flags & B_VMIO)) 3657 return; 3658 3659 /* 3660 * Fixup base to be relative to beginning of first page. 3661 * Set initial n to be the maximum number of bytes in the 3662 * first page that can be validated. 3663 */ 3664 base += (bp->b_offset & PAGE_MASK); 3665 n = PAGE_SIZE - (base & PAGE_MASK); 3666 3667 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3668 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3669 m = bp->b_pages[i]; 3670 if (n > size) 3671 n = size; 3672 vm_page_set_valid(m, base & PAGE_MASK, n); 3673 base += n; 3674 size -= n; 3675 n = PAGE_SIZE; 3676 } 3677 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3678 } 3679 3680 /* 3681 * vfs_bio_clrbuf: 3682 * 3683 * If the specified buffer is a non-VMIO buffer, clear the entire 3684 * buffer. If the specified buffer is a VMIO buffer, clear and 3685 * validate only the previously invalid portions of the buffer. 3686 * This routine essentially fakes an I/O, so we need to clear 3687 * BIO_ERROR and B_INVAL. 3688 * 3689 * Note that while we only theoretically need to clear through b_bcount, 3690 * we go ahead and clear through b_bufsize. 3691 */ 3692 void 3693 vfs_bio_clrbuf(struct buf *bp) 3694 { 3695 int i, j, mask; 3696 caddr_t sa, ea; 3697 3698 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3699 clrbuf(bp); 3700 return; 3701 } 3702 bp->b_flags &= ~B_INVAL; 3703 bp->b_ioflags &= ~BIO_ERROR; 3704 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3705 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3706 (bp->b_offset & PAGE_MASK) == 0) { 3707 if (bp->b_pages[0] == bogus_page) 3708 goto unlock; 3709 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3710 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3711 if ((bp->b_pages[0]->valid & mask) == mask) 3712 goto unlock; 3713 if ((bp->b_pages[0]->valid & mask) == 0) { 3714 bzero(bp->b_data, bp->b_bufsize); 3715 bp->b_pages[0]->valid |= mask; 3716 goto unlock; 3717 } 3718 } 3719 ea = sa = bp->b_data; 3720 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3721 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3722 ea = (caddr_t)(vm_offset_t)ulmin( 3723 (u_long)(vm_offset_t)ea, 3724 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3725 if (bp->b_pages[i] == bogus_page) 3726 continue; 3727 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3728 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3729 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3730 if ((bp->b_pages[i]->valid & mask) == mask) 3731 continue; 3732 if ((bp->b_pages[i]->valid & mask) == 0) 3733 bzero(sa, ea - sa); 3734 else { 3735 for (; sa < ea; sa += DEV_BSIZE, j++) { 3736 if ((bp->b_pages[i]->valid & (1 << j)) == 0) 3737 bzero(sa, DEV_BSIZE); 3738 } 3739 } 3740 bp->b_pages[i]->valid |= mask; 3741 } 3742 unlock: 3743 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3744 bp->b_resid = 0; 3745 } 3746 3747 /* 3748 * vm_hold_load_pages and vm_hold_free_pages get pages into 3749 * a buffers address space. The pages are anonymous and are 3750 * not associated with a file object. 3751 */ 3752 static void 3753 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3754 { 3755 vm_offset_t pg; 3756 vm_page_t p; 3757 int index; 3758 3759 to = round_page(to); 3760 from = round_page(from); 3761 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3762 3763 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3764 tryagain: 3765 /* 3766 * note: must allocate system pages since blocking here 3767 * could interfere with paging I/O, no matter which 3768 * process we are. 3769 */ 3770 p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ | 3771 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3772 if (!p) { 3773 atomic_add_int(&vm_pageout_deficit, 3774 (to - pg) >> PAGE_SHIFT); 3775 VM_WAIT; 3776 goto tryagain; 3777 } 3778 pmap_qenter(pg, &p, 1); 3779 bp->b_pages[index] = p; 3780 } 3781 bp->b_npages = index; 3782 } 3783 3784 /* Return pages associated with this buf to the vm system */ 3785 static void 3786 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3787 { 3788 vm_offset_t pg; 3789 vm_page_t p; 3790 int index, newnpages; 3791 3792 from = round_page(from); 3793 to = round_page(to); 3794 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3795 3796 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3797 p = bp->b_pages[index]; 3798 if (p && (index < bp->b_npages)) { 3799 if (p->busy) { 3800 printf( 3801 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3802 (intmax_t)bp->b_blkno, 3803 (intmax_t)bp->b_lblkno); 3804 } 3805 bp->b_pages[index] = NULL; 3806 pmap_qremove(pg, 1); 3807 p->wire_count--; 3808 vm_page_free(p); 3809 atomic_subtract_int(&cnt.v_wire_count, 1); 3810 } 3811 } 3812 bp->b_npages = newnpages; 3813 } 3814 3815 /* 3816 * Map an IO request into kernel virtual address space. 3817 * 3818 * All requests are (re)mapped into kernel VA space. 3819 * Notice that we use b_bufsize for the size of the buffer 3820 * to be mapped. b_bcount might be modified by the driver. 3821 * 3822 * Note that even if the caller determines that the address space should 3823 * be valid, a race or a smaller-file mapped into a larger space may 3824 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3825 * check the return value. 3826 */ 3827 int 3828 vmapbuf(struct buf *bp) 3829 { 3830 caddr_t addr, kva; 3831 vm_prot_t prot; 3832 int pidx, i; 3833 struct vm_page *m; 3834 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3835 3836 if (bp->b_bufsize < 0) 3837 return (-1); 3838 prot = VM_PROT_READ; 3839 if (bp->b_iocmd == BIO_READ) 3840 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3841 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3842 addr < bp->b_data + bp->b_bufsize; 3843 addr += PAGE_SIZE, pidx++) { 3844 /* 3845 * Do the vm_fault if needed; do the copy-on-write thing 3846 * when reading stuff off device into memory. 3847 * 3848 * NOTE! Must use pmap_extract() because addr may be in 3849 * the userland address space, and kextract is only guarenteed 3850 * to work for the kernland address space (see: sparc64 port). 3851 */ 3852 retry: 3853 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3854 prot) < 0) { 3855 for (i = 0; i < pidx; ++i) { 3856 vm_page_lock(bp->b_pages[i]); 3857 vm_page_unhold(bp->b_pages[i]); 3858 vm_page_unlock(bp->b_pages[i]); 3859 bp->b_pages[i] = NULL; 3860 } 3861 return(-1); 3862 } 3863 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3864 if (m == NULL) 3865 goto retry; 3866 bp->b_pages[pidx] = m; 3867 } 3868 if (pidx > btoc(MAXPHYS)) 3869 panic("vmapbuf: mapped more than MAXPHYS"); 3870 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3871 3872 kva = bp->b_saveaddr; 3873 bp->b_npages = pidx; 3874 bp->b_saveaddr = bp->b_data; 3875 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3876 return(0); 3877 } 3878 3879 /* 3880 * Free the io map PTEs associated with this IO operation. 3881 * We also invalidate the TLB entries and restore the original b_addr. 3882 */ 3883 void 3884 vunmapbuf(struct buf *bp) 3885 { 3886 int pidx; 3887 int npages; 3888 3889 npages = bp->b_npages; 3890 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3891 for (pidx = 0; pidx < npages; pidx++) { 3892 vm_page_lock(bp->b_pages[pidx]); 3893 vm_page_unhold(bp->b_pages[pidx]); 3894 vm_page_unlock(bp->b_pages[pidx]); 3895 } 3896 3897 bp->b_data = bp->b_saveaddr; 3898 } 3899 3900 void 3901 bdone(struct buf *bp) 3902 { 3903 struct mtx *mtxp; 3904 3905 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3906 mtx_lock(mtxp); 3907 bp->b_flags |= B_DONE; 3908 wakeup(bp); 3909 mtx_unlock(mtxp); 3910 } 3911 3912 void 3913 bwait(struct buf *bp, u_char pri, const char *wchan) 3914 { 3915 struct mtx *mtxp; 3916 3917 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3918 mtx_lock(mtxp); 3919 while ((bp->b_flags & B_DONE) == 0) 3920 msleep(bp, mtxp, pri, wchan, 0); 3921 mtx_unlock(mtxp); 3922 } 3923 3924 int 3925 bufsync(struct bufobj *bo, int waitfor) 3926 { 3927 3928 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3929 } 3930 3931 void 3932 bufstrategy(struct bufobj *bo, struct buf *bp) 3933 { 3934 int i = 0; 3935 struct vnode *vp; 3936 3937 vp = bp->b_vp; 3938 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3939 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3940 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3941 i = VOP_STRATEGY(vp, bp); 3942 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3943 } 3944 3945 void 3946 bufobj_wrefl(struct bufobj *bo) 3947 { 3948 3949 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3950 ASSERT_BO_LOCKED(bo); 3951 bo->bo_numoutput++; 3952 } 3953 3954 void 3955 bufobj_wref(struct bufobj *bo) 3956 { 3957 3958 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3959 BO_LOCK(bo); 3960 bo->bo_numoutput++; 3961 BO_UNLOCK(bo); 3962 } 3963 3964 void 3965 bufobj_wdrop(struct bufobj *bo) 3966 { 3967 3968 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3969 BO_LOCK(bo); 3970 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3971 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3972 bo->bo_flag &= ~BO_WWAIT; 3973 wakeup(&bo->bo_numoutput); 3974 } 3975 BO_UNLOCK(bo); 3976 } 3977 3978 int 3979 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3980 { 3981 int error; 3982 3983 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3984 ASSERT_BO_LOCKED(bo); 3985 error = 0; 3986 while (bo->bo_numoutput) { 3987 bo->bo_flag |= BO_WWAIT; 3988 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3989 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3990 if (error) 3991 break; 3992 } 3993 return (error); 3994 } 3995 3996 void 3997 bpin(struct buf *bp) 3998 { 3999 struct mtx *mtxp; 4000 4001 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4002 mtx_lock(mtxp); 4003 bp->b_pin_count++; 4004 mtx_unlock(mtxp); 4005 } 4006 4007 void 4008 bunpin(struct buf *bp) 4009 { 4010 struct mtx *mtxp; 4011 4012 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4013 mtx_lock(mtxp); 4014 if (--bp->b_pin_count == 0) 4015 wakeup(bp); 4016 mtx_unlock(mtxp); 4017 } 4018 4019 void 4020 bunpin_wait(struct buf *bp) 4021 { 4022 struct mtx *mtxp; 4023 4024 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4025 mtx_lock(mtxp); 4026 while (bp->b_pin_count > 0) 4027 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4028 mtx_unlock(mtxp); 4029 } 4030 4031 #include "opt_ddb.h" 4032 #ifdef DDB 4033 #include <ddb/ddb.h> 4034 4035 /* DDB command to show buffer data */ 4036 DB_SHOW_COMMAND(buffer, db_show_buffer) 4037 { 4038 /* get args */ 4039 struct buf *bp = (struct buf *)addr; 4040 4041 if (!have_addr) { 4042 db_printf("usage: show buffer <addr>\n"); 4043 return; 4044 } 4045 4046 db_printf("buf at %p\n", bp); 4047 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4048 db_printf( 4049 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4050 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n", 4051 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4052 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4053 bp->b_dep.lh_first); 4054 if (bp->b_npages) { 4055 int i; 4056 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4057 for (i = 0; i < bp->b_npages; i++) { 4058 vm_page_t m; 4059 m = bp->b_pages[i]; 4060 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4061 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4062 if ((i + 1) < bp->b_npages) 4063 db_printf(","); 4064 } 4065 db_printf("\n"); 4066 } 4067 db_printf(" "); 4068 lockmgr_printinfo(&bp->b_lock); 4069 } 4070 4071 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4072 { 4073 struct buf *bp; 4074 int i; 4075 4076 for (i = 0; i < nbuf; i++) { 4077 bp = &buf[i]; 4078 if (BUF_ISLOCKED(bp)) { 4079 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4080 db_printf("\n"); 4081 } 4082 } 4083 } 4084 4085 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4086 { 4087 struct vnode *vp; 4088 struct buf *bp; 4089 4090 if (!have_addr) { 4091 db_printf("usage: show vnodebufs <addr>\n"); 4092 return; 4093 } 4094 vp = (struct vnode *)addr; 4095 db_printf("Clean buffers:\n"); 4096 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4097 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4098 db_printf("\n"); 4099 } 4100 db_printf("Dirty buffers:\n"); 4101 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4102 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4103 db_printf("\n"); 4104 } 4105 } 4106 #endif /* DDB */ 4107