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_clean_pages(struct buf *bp); 106 static void vfs_setdirty(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 pages. 1029 */ 1030 vfs_setdirty(bp); 1031 1032 /* 1033 * We need to do this here to satisfy the vnode_pager and the 1034 * pageout daemon, so that it thinks that the pages have been 1035 * "cleaned". Note that since the pages are in a delayed write 1036 * buffer -- the VFS layer "will" see that the pages get written 1037 * out on the next sync, or perhaps the cluster will be completed. 1038 */ 1039 vfs_clean_pages(bp); 1040 bqrelse(bp); 1041 1042 /* 1043 * Wakeup the buffer flushing daemon if we have a lot of dirty 1044 * buffers (midpoint between our recovery point and our stall 1045 * point). 1046 */ 1047 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1048 1049 /* 1050 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1051 * due to the softdep code. 1052 */ 1053 } 1054 1055 /* 1056 * bdirty: 1057 * 1058 * Turn buffer into delayed write request. We must clear BIO_READ and 1059 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1060 * itself to properly update it in the dirty/clean lists. We mark it 1061 * B_DONE to ensure that any asynchronization of the buffer properly 1062 * clears B_DONE ( else a panic will occur later ). 1063 * 1064 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1065 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1066 * should only be called if the buffer is known-good. 1067 * 1068 * Since the buffer is not on a queue, we do not update the numfreebuffers 1069 * count. 1070 * 1071 * The buffer must be on QUEUE_NONE. 1072 */ 1073 void 1074 bdirty(struct buf *bp) 1075 { 1076 1077 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1078 bp, bp->b_vp, bp->b_flags); 1079 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1080 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1081 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1082 BUF_ASSERT_HELD(bp); 1083 bp->b_flags &= ~(B_RELBUF); 1084 bp->b_iocmd = BIO_WRITE; 1085 1086 if ((bp->b_flags & B_DELWRI) == 0) { 1087 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1088 reassignbuf(bp); 1089 atomic_add_int(&numdirtybuffers, 1); 1090 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1091 } 1092 } 1093 1094 /* 1095 * bundirty: 1096 * 1097 * Clear B_DELWRI for buffer. 1098 * 1099 * Since the buffer is not on a queue, we do not update the numfreebuffers 1100 * count. 1101 * 1102 * The buffer must be on QUEUE_NONE. 1103 */ 1104 1105 void 1106 bundirty(struct buf *bp) 1107 { 1108 1109 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1110 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1111 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1112 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1113 BUF_ASSERT_HELD(bp); 1114 1115 if (bp->b_flags & B_DELWRI) { 1116 bp->b_flags &= ~B_DELWRI; 1117 reassignbuf(bp); 1118 atomic_subtract_int(&numdirtybuffers, 1); 1119 numdirtywakeup(lodirtybuffers); 1120 } 1121 /* 1122 * Since it is now being written, we can clear its deferred write flag. 1123 */ 1124 bp->b_flags &= ~B_DEFERRED; 1125 } 1126 1127 /* 1128 * bawrite: 1129 * 1130 * Asynchronous write. Start output on a buffer, but do not wait for 1131 * it to complete. The buffer is released when the output completes. 1132 * 1133 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1134 * B_INVAL buffers. Not us. 1135 */ 1136 void 1137 bawrite(struct buf *bp) 1138 { 1139 1140 bp->b_flags |= B_ASYNC; 1141 (void) bwrite(bp); 1142 } 1143 1144 /* 1145 * bwillwrite: 1146 * 1147 * Called prior to the locking of any vnodes when we are expecting to 1148 * write. We do not want to starve the buffer cache with too many 1149 * dirty buffers so we block here. By blocking prior to the locking 1150 * of any vnodes we attempt to avoid the situation where a locked vnode 1151 * prevents the various system daemons from flushing related buffers. 1152 */ 1153 1154 void 1155 bwillwrite(void) 1156 { 1157 1158 if (numdirtybuffers >= hidirtybuffers) { 1159 mtx_lock(&nblock); 1160 while (numdirtybuffers >= hidirtybuffers) { 1161 bd_wakeup(1); 1162 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1163 msleep(&needsbuffer, &nblock, 1164 (PRIBIO + 4), "flswai", 0); 1165 } 1166 mtx_unlock(&nblock); 1167 } 1168 } 1169 1170 /* 1171 * Return true if we have too many dirty buffers. 1172 */ 1173 int 1174 buf_dirty_count_severe(void) 1175 { 1176 1177 return(numdirtybuffers >= hidirtybuffers); 1178 } 1179 1180 static __noinline int 1181 buf_vm_page_count_severe(void) 1182 { 1183 1184 KFAIL_POINT_CODE(DEBUG_FP, buf_pressure, return 1); 1185 1186 return vm_page_count_severe(); 1187 } 1188 1189 /* 1190 * brelse: 1191 * 1192 * Release a busy buffer and, if requested, free its resources. The 1193 * buffer will be stashed in the appropriate bufqueue[] allowing it 1194 * to be accessed later as a cache entity or reused for other purposes. 1195 */ 1196 void 1197 brelse(struct buf *bp) 1198 { 1199 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1200 bp, bp->b_vp, bp->b_flags); 1201 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1202 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1203 1204 if (bp->b_flags & B_MANAGED) { 1205 bqrelse(bp); 1206 return; 1207 } 1208 1209 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1210 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1211 /* 1212 * Failed write, redirty. Must clear BIO_ERROR to prevent 1213 * pages from being scrapped. If the error is anything 1214 * other than an I/O error (EIO), assume that retrying 1215 * is futile. 1216 */ 1217 bp->b_ioflags &= ~BIO_ERROR; 1218 bdirty(bp); 1219 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1220 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1221 /* 1222 * Either a failed I/O or we were asked to free or not 1223 * cache the buffer. 1224 */ 1225 bp->b_flags |= B_INVAL; 1226 if (!LIST_EMPTY(&bp->b_dep)) 1227 buf_deallocate(bp); 1228 if (bp->b_flags & B_DELWRI) { 1229 atomic_subtract_int(&numdirtybuffers, 1); 1230 numdirtywakeup(lodirtybuffers); 1231 } 1232 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1233 if ((bp->b_flags & B_VMIO) == 0) { 1234 if (bp->b_bufsize) 1235 allocbuf(bp, 0); 1236 if (bp->b_vp) 1237 brelvp(bp); 1238 } 1239 } 1240 1241 /* 1242 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1243 * is called with B_DELWRI set, the underlying pages may wind up 1244 * getting freed causing a previous write (bdwrite()) to get 'lost' 1245 * because pages associated with a B_DELWRI bp are marked clean. 1246 * 1247 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1248 * if B_DELWRI is set. 1249 * 1250 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1251 * on pages to return pages to the VM page queues. 1252 */ 1253 if (bp->b_flags & B_DELWRI) 1254 bp->b_flags &= ~B_RELBUF; 1255 else if (buf_vm_page_count_severe()) { 1256 /* 1257 * The locking of the BO_LOCK is not necessary since 1258 * BKGRDINPROG cannot be set while we hold the buf 1259 * lock, it can only be cleared if it is already 1260 * pending. 1261 */ 1262 if (bp->b_vp) { 1263 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1264 bp->b_flags |= B_RELBUF; 1265 } else 1266 bp->b_flags |= B_RELBUF; 1267 } 1268 1269 /* 1270 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1271 * constituted, not even NFS buffers now. Two flags effect this. If 1272 * B_INVAL, the struct buf is invalidated but the VM object is kept 1273 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1274 * 1275 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1276 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1277 * buffer is also B_INVAL because it hits the re-dirtying code above. 1278 * 1279 * Normally we can do this whether a buffer is B_DELWRI or not. If 1280 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1281 * the commit state and we cannot afford to lose the buffer. If the 1282 * buffer has a background write in progress, we need to keep it 1283 * around to prevent it from being reconstituted and starting a second 1284 * background write. 1285 */ 1286 if ((bp->b_flags & B_VMIO) 1287 && !(bp->b_vp->v_mount != NULL && 1288 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1289 !vn_isdisk(bp->b_vp, NULL) && 1290 (bp->b_flags & B_DELWRI)) 1291 ) { 1292 1293 int i, j, resid; 1294 vm_page_t m; 1295 off_t foff; 1296 vm_pindex_t poff; 1297 vm_object_t obj; 1298 1299 obj = bp->b_bufobj->bo_object; 1300 1301 /* 1302 * Get the base offset and length of the buffer. Note that 1303 * in the VMIO case if the buffer block size is not 1304 * page-aligned then b_data pointer may not be page-aligned. 1305 * But our b_pages[] array *IS* page aligned. 1306 * 1307 * block sizes less then DEV_BSIZE (usually 512) are not 1308 * supported due to the page granularity bits (m->valid, 1309 * m->dirty, etc...). 1310 * 1311 * See man buf(9) for more information 1312 */ 1313 resid = bp->b_bufsize; 1314 foff = bp->b_offset; 1315 VM_OBJECT_LOCK(obj); 1316 for (i = 0; i < bp->b_npages; i++) { 1317 int had_bogus = 0; 1318 1319 m = bp->b_pages[i]; 1320 1321 /* 1322 * If we hit a bogus page, fixup *all* the bogus pages 1323 * now. 1324 */ 1325 if (m == bogus_page) { 1326 poff = OFF_TO_IDX(bp->b_offset); 1327 had_bogus = 1; 1328 1329 for (j = i; j < bp->b_npages; j++) { 1330 vm_page_t mtmp; 1331 mtmp = bp->b_pages[j]; 1332 if (mtmp == bogus_page) { 1333 mtmp = vm_page_lookup(obj, poff + j); 1334 if (!mtmp) { 1335 panic("brelse: page missing\n"); 1336 } 1337 bp->b_pages[j] = mtmp; 1338 } 1339 } 1340 1341 if ((bp->b_flags & B_INVAL) == 0) { 1342 pmap_qenter( 1343 trunc_page((vm_offset_t)bp->b_data), 1344 bp->b_pages, bp->b_npages); 1345 } 1346 m = bp->b_pages[i]; 1347 } 1348 if ((bp->b_flags & B_NOCACHE) || 1349 (bp->b_ioflags & BIO_ERROR && 1350 bp->b_iocmd == BIO_READ)) { 1351 int poffset = foff & PAGE_MASK; 1352 int presid = resid > (PAGE_SIZE - poffset) ? 1353 (PAGE_SIZE - poffset) : resid; 1354 1355 KASSERT(presid >= 0, ("brelse: extra page")); 1356 vm_page_lock_queues(); 1357 vm_page_set_invalid(m, poffset, presid); 1358 vm_page_unlock_queues(); 1359 if (had_bogus) 1360 printf("avoided corruption bug in bogus_page/brelse code\n"); 1361 } 1362 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1363 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1364 } 1365 VM_OBJECT_UNLOCK(obj); 1366 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1367 vfs_vmio_release(bp); 1368 1369 } else if (bp->b_flags & B_VMIO) { 1370 1371 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1372 vfs_vmio_release(bp); 1373 } 1374 1375 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1376 if (bp->b_bufsize != 0) 1377 allocbuf(bp, 0); 1378 if (bp->b_vp != NULL) 1379 brelvp(bp); 1380 } 1381 1382 if (BUF_LOCKRECURSED(bp)) { 1383 /* do not release to free list */ 1384 BUF_UNLOCK(bp); 1385 return; 1386 } 1387 1388 /* enqueue */ 1389 mtx_lock(&bqlock); 1390 /* Handle delayed bremfree() processing. */ 1391 if (bp->b_flags & B_REMFREE) 1392 bremfreel(bp); 1393 if (bp->b_qindex != QUEUE_NONE) 1394 panic("brelse: free buffer onto another queue???"); 1395 1396 /* 1397 * If the buffer has junk contents signal it and eventually 1398 * clean up B_DELWRI and diassociate the vnode so that gbincore() 1399 * doesn't find it. 1400 */ 1401 if (bp->b_bufsize == 0 || (bp->b_ioflags & BIO_ERROR) != 0 || 1402 (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF)) != 0) 1403 bp->b_flags |= B_INVAL; 1404 if (bp->b_flags & B_INVAL) { 1405 if (bp->b_flags & B_DELWRI) 1406 bundirty(bp); 1407 if (bp->b_vp) 1408 brelvp(bp); 1409 } 1410 1411 /* buffers with no memory */ 1412 if (bp->b_bufsize == 0) { 1413 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1414 if (bp->b_vflags & BV_BKGRDINPROG) 1415 panic("losing buffer 1"); 1416 if (bp->b_kvasize) { 1417 bp->b_qindex = QUEUE_EMPTYKVA; 1418 } else { 1419 bp->b_qindex = QUEUE_EMPTY; 1420 } 1421 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1422 /* buffers with junk contents */ 1423 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1424 (bp->b_ioflags & BIO_ERROR)) { 1425 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1426 if (bp->b_vflags & BV_BKGRDINPROG) 1427 panic("losing buffer 2"); 1428 bp->b_qindex = QUEUE_CLEAN; 1429 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1430 /* remaining buffers */ 1431 } else { 1432 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1433 (B_DELWRI|B_NEEDSGIANT)) 1434 bp->b_qindex = QUEUE_DIRTY_GIANT; 1435 else if (bp->b_flags & B_DELWRI) 1436 bp->b_qindex = QUEUE_DIRTY; 1437 else 1438 bp->b_qindex = QUEUE_CLEAN; 1439 if (bp->b_flags & B_AGE) 1440 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1441 else 1442 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1443 } 1444 mtx_unlock(&bqlock); 1445 1446 /* 1447 * Fixup numfreebuffers count. The bp is on an appropriate queue 1448 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1449 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1450 * if B_INVAL is set ). 1451 */ 1452 1453 if (!(bp->b_flags & B_DELWRI)) 1454 bufcountwakeup(); 1455 1456 /* 1457 * Something we can maybe free or reuse 1458 */ 1459 if (bp->b_bufsize || bp->b_kvasize) 1460 bufspacewakeup(); 1461 1462 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1463 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1464 panic("brelse: not dirty"); 1465 /* unlock */ 1466 BUF_UNLOCK(bp); 1467 } 1468 1469 /* 1470 * Release a buffer back to the appropriate queue but do not try to free 1471 * it. The buffer is expected to be used again soon. 1472 * 1473 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1474 * biodone() to requeue an async I/O on completion. It is also used when 1475 * known good buffers need to be requeued but we think we may need the data 1476 * again soon. 1477 * 1478 * XXX we should be able to leave the B_RELBUF hint set on completion. 1479 */ 1480 void 1481 bqrelse(struct buf *bp) 1482 { 1483 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1484 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1485 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1486 1487 if (BUF_LOCKRECURSED(bp)) { 1488 /* do not release to free list */ 1489 BUF_UNLOCK(bp); 1490 return; 1491 } 1492 1493 if (bp->b_flags & B_MANAGED) { 1494 if (bp->b_flags & B_REMFREE) { 1495 mtx_lock(&bqlock); 1496 bremfreel(bp); 1497 mtx_unlock(&bqlock); 1498 } 1499 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1500 BUF_UNLOCK(bp); 1501 return; 1502 } 1503 1504 mtx_lock(&bqlock); 1505 /* Handle delayed bremfree() processing. */ 1506 if (bp->b_flags & B_REMFREE) 1507 bremfreel(bp); 1508 if (bp->b_qindex != QUEUE_NONE) 1509 panic("bqrelse: free buffer onto another queue???"); 1510 /* buffers with stale but valid contents */ 1511 if (bp->b_flags & B_DELWRI) { 1512 if (bp->b_flags & B_NEEDSGIANT) 1513 bp->b_qindex = QUEUE_DIRTY_GIANT; 1514 else 1515 bp->b_qindex = QUEUE_DIRTY; 1516 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1517 } else { 1518 /* 1519 * The locking of the BO_LOCK for checking of the 1520 * BV_BKGRDINPROG is not necessary since the 1521 * BV_BKGRDINPROG cannot be set while we hold the buf 1522 * lock, it can only be cleared if it is already 1523 * pending. 1524 */ 1525 if (!buf_vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1526 bp->b_qindex = QUEUE_CLEAN; 1527 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1528 b_freelist); 1529 } else { 1530 /* 1531 * We are too low on memory, we have to try to free 1532 * the buffer (most importantly: the wired pages 1533 * making up its backing store) *now*. 1534 */ 1535 mtx_unlock(&bqlock); 1536 brelse(bp); 1537 return; 1538 } 1539 } 1540 mtx_unlock(&bqlock); 1541 1542 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1543 bufcountwakeup(); 1544 1545 /* 1546 * Something we can maybe free or reuse. 1547 */ 1548 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1549 bufspacewakeup(); 1550 1551 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1552 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1553 panic("bqrelse: not dirty"); 1554 /* unlock */ 1555 BUF_UNLOCK(bp); 1556 } 1557 1558 /* Give pages used by the bp back to the VM system (where possible) */ 1559 static void 1560 vfs_vmio_release(struct buf *bp) 1561 { 1562 int i; 1563 vm_page_t m; 1564 1565 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1566 vm_page_lock_queues(); 1567 for (i = 0; i < bp->b_npages; i++) { 1568 m = bp->b_pages[i]; 1569 bp->b_pages[i] = NULL; 1570 /* 1571 * In order to keep page LRU ordering consistent, put 1572 * everything on the inactive queue. 1573 */ 1574 vm_page_unwire(m, 0); 1575 /* 1576 * We don't mess with busy pages, it is 1577 * the responsibility of the process that 1578 * busied the pages to deal with them. 1579 */ 1580 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1581 continue; 1582 1583 if (m->wire_count == 0) { 1584 /* 1585 * Might as well free the page if we can and it has 1586 * no valid data. We also free the page if the 1587 * buffer was used for direct I/O 1588 */ 1589 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1590 m->hold_count == 0) { 1591 vm_page_free(m); 1592 } else if (bp->b_flags & B_DIRECT) { 1593 vm_page_try_to_free(m); 1594 } else if (buf_vm_page_count_severe()) { 1595 vm_page_try_to_cache(m); 1596 } 1597 } 1598 } 1599 vm_page_unlock_queues(); 1600 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1601 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1602 1603 if (bp->b_bufsize) { 1604 bufspacewakeup(); 1605 bp->b_bufsize = 0; 1606 } 1607 bp->b_npages = 0; 1608 bp->b_flags &= ~B_VMIO; 1609 if (bp->b_vp) 1610 brelvp(bp); 1611 } 1612 1613 /* 1614 * Check to see if a block at a particular lbn is available for a clustered 1615 * write. 1616 */ 1617 static int 1618 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1619 { 1620 struct buf *bpa; 1621 int match; 1622 1623 match = 0; 1624 1625 /* If the buf isn't in core skip it */ 1626 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1627 return (0); 1628 1629 /* If the buf is busy we don't want to wait for it */ 1630 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1631 return (0); 1632 1633 /* Only cluster with valid clusterable delayed write buffers */ 1634 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1635 (B_DELWRI | B_CLUSTEROK)) 1636 goto done; 1637 1638 if (bpa->b_bufsize != size) 1639 goto done; 1640 1641 /* 1642 * Check to see if it is in the expected place on disk and that the 1643 * block has been mapped. 1644 */ 1645 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1646 match = 1; 1647 done: 1648 BUF_UNLOCK(bpa); 1649 return (match); 1650 } 1651 1652 /* 1653 * vfs_bio_awrite: 1654 * 1655 * Implement clustered async writes for clearing out B_DELWRI buffers. 1656 * This is much better then the old way of writing only one buffer at 1657 * a time. Note that we may not be presented with the buffers in the 1658 * correct order, so we search for the cluster in both directions. 1659 */ 1660 int 1661 vfs_bio_awrite(struct buf *bp) 1662 { 1663 struct bufobj *bo; 1664 int i; 1665 int j; 1666 daddr_t lblkno = bp->b_lblkno; 1667 struct vnode *vp = bp->b_vp; 1668 int ncl; 1669 int nwritten; 1670 int size; 1671 int maxcl; 1672 1673 bo = &vp->v_bufobj; 1674 /* 1675 * right now we support clustered writing only to regular files. If 1676 * we find a clusterable block we could be in the middle of a cluster 1677 * rather then at the beginning. 1678 */ 1679 if ((vp->v_type == VREG) && 1680 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1681 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1682 1683 size = vp->v_mount->mnt_stat.f_iosize; 1684 maxcl = MAXPHYS / size; 1685 1686 BO_LOCK(bo); 1687 for (i = 1; i < maxcl; i++) 1688 if (vfs_bio_clcheck(vp, size, lblkno + i, 1689 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1690 break; 1691 1692 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1693 if (vfs_bio_clcheck(vp, size, lblkno - j, 1694 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1695 break; 1696 BO_UNLOCK(bo); 1697 --j; 1698 ncl = i + j; 1699 /* 1700 * this is a possible cluster write 1701 */ 1702 if (ncl != 1) { 1703 BUF_UNLOCK(bp); 1704 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1705 return nwritten; 1706 } 1707 } 1708 bremfree(bp); 1709 bp->b_flags |= B_ASYNC; 1710 /* 1711 * default (old) behavior, writing out only one block 1712 * 1713 * XXX returns b_bufsize instead of b_bcount for nwritten? 1714 */ 1715 nwritten = bp->b_bufsize; 1716 (void) bwrite(bp); 1717 1718 return nwritten; 1719 } 1720 1721 /* 1722 * getnewbuf: 1723 * 1724 * Find and initialize a new buffer header, freeing up existing buffers 1725 * in the bufqueues as necessary. The new buffer is returned locked. 1726 * 1727 * Important: B_INVAL is not set. If the caller wishes to throw the 1728 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1729 * 1730 * We block if: 1731 * We have insufficient buffer headers 1732 * We have insufficient buffer space 1733 * buffer_map is too fragmented ( space reservation fails ) 1734 * If we have to flush dirty buffers ( but we try to avoid this ) 1735 * 1736 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1737 * Instead we ask the buf daemon to do it for us. We attempt to 1738 * avoid piecemeal wakeups of the pageout daemon. 1739 */ 1740 1741 static struct buf * 1742 getnewbuf(struct vnode *vp, int slpflag, int slptimeo, int size, int maxsize, 1743 int gbflags) 1744 { 1745 struct thread *td; 1746 struct buf *bp; 1747 struct buf *nbp; 1748 int defrag = 0; 1749 int nqindex; 1750 static int flushingbufs; 1751 1752 td = curthread; 1753 /* 1754 * We can't afford to block since we might be holding a vnode lock, 1755 * which may prevent system daemons from running. We deal with 1756 * low-memory situations by proactively returning memory and running 1757 * async I/O rather then sync I/O. 1758 */ 1759 atomic_add_int(&getnewbufcalls, 1); 1760 atomic_subtract_int(&getnewbufrestarts, 1); 1761 restart: 1762 atomic_add_int(&getnewbufrestarts, 1); 1763 1764 /* 1765 * Setup for scan. If we do not have enough free buffers, 1766 * we setup a degenerate case that immediately fails. Note 1767 * that if we are specially marked process, we are allowed to 1768 * dip into our reserves. 1769 * 1770 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1771 * 1772 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1773 * However, there are a number of cases (defragging, reusing, ...) 1774 * where we cannot backup. 1775 */ 1776 mtx_lock(&bqlock); 1777 nqindex = QUEUE_EMPTYKVA; 1778 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1779 1780 if (nbp == NULL) { 1781 /* 1782 * If no EMPTYKVA buffers and we are either 1783 * defragging or reusing, locate a CLEAN buffer 1784 * to free or reuse. If bufspace useage is low 1785 * skip this step so we can allocate a new buffer. 1786 */ 1787 if (defrag || bufspace >= lobufspace) { 1788 nqindex = QUEUE_CLEAN; 1789 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1790 } 1791 1792 /* 1793 * If we could not find or were not allowed to reuse a 1794 * CLEAN buffer, check to see if it is ok to use an EMPTY 1795 * buffer. We can only use an EMPTY buffer if allocating 1796 * its KVA would not otherwise run us out of buffer space. 1797 */ 1798 if (nbp == NULL && defrag == 0 && 1799 bufspace + maxsize < hibufspace) { 1800 nqindex = QUEUE_EMPTY; 1801 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1802 } 1803 } 1804 1805 /* 1806 * Run scan, possibly freeing data and/or kva mappings on the fly 1807 * depending. 1808 */ 1809 1810 while ((bp = nbp) != NULL) { 1811 int qindex = nqindex; 1812 1813 /* 1814 * Calculate next bp ( we can only use it if we do not block 1815 * or do other fancy things ). 1816 */ 1817 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1818 switch(qindex) { 1819 case QUEUE_EMPTY: 1820 nqindex = QUEUE_EMPTYKVA; 1821 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1822 break; 1823 /* FALLTHROUGH */ 1824 case QUEUE_EMPTYKVA: 1825 nqindex = QUEUE_CLEAN; 1826 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1827 break; 1828 /* FALLTHROUGH */ 1829 case QUEUE_CLEAN: 1830 /* 1831 * nbp is NULL. 1832 */ 1833 break; 1834 } 1835 } 1836 /* 1837 * If we are defragging then we need a buffer with 1838 * b_kvasize != 0. XXX this situation should no longer 1839 * occur, if defrag is non-zero the buffer's b_kvasize 1840 * should also be non-zero at this point. XXX 1841 */ 1842 if (defrag && bp->b_kvasize == 0) { 1843 printf("Warning: defrag empty buffer %p\n", bp); 1844 continue; 1845 } 1846 1847 /* 1848 * Start freeing the bp. This is somewhat involved. nbp 1849 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1850 */ 1851 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1852 continue; 1853 if (bp->b_vp) { 1854 BO_LOCK(bp->b_bufobj); 1855 if (bp->b_vflags & BV_BKGRDINPROG) { 1856 BO_UNLOCK(bp->b_bufobj); 1857 BUF_UNLOCK(bp); 1858 continue; 1859 } 1860 BO_UNLOCK(bp->b_bufobj); 1861 } 1862 CTR6(KTR_BUF, 1863 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1864 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1865 bp->b_kvasize, bp->b_bufsize, qindex); 1866 1867 /* 1868 * Sanity Checks 1869 */ 1870 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1871 1872 /* 1873 * Note: we no longer distinguish between VMIO and non-VMIO 1874 * buffers. 1875 */ 1876 1877 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1878 1879 bremfreel(bp); 1880 mtx_unlock(&bqlock); 1881 1882 if (qindex == QUEUE_CLEAN) { 1883 if (bp->b_flags & B_VMIO) { 1884 bp->b_flags &= ~B_ASYNC; 1885 vfs_vmio_release(bp); 1886 } 1887 if (bp->b_vp) 1888 brelvp(bp); 1889 } 1890 1891 /* 1892 * NOTE: nbp is now entirely invalid. We can only restart 1893 * the scan from this point on. 1894 * 1895 * Get the rest of the buffer freed up. b_kva* is still 1896 * valid after this operation. 1897 */ 1898 1899 if (bp->b_rcred != NOCRED) { 1900 crfree(bp->b_rcred); 1901 bp->b_rcred = NOCRED; 1902 } 1903 if (bp->b_wcred != NOCRED) { 1904 crfree(bp->b_wcred); 1905 bp->b_wcred = NOCRED; 1906 } 1907 if (!LIST_EMPTY(&bp->b_dep)) 1908 buf_deallocate(bp); 1909 if (bp->b_vflags & BV_BKGRDINPROG) 1910 panic("losing buffer 3"); 1911 KASSERT(bp->b_vp == NULL, 1912 ("bp: %p still has vnode %p. qindex: %d", 1913 bp, bp->b_vp, qindex)); 1914 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1915 ("bp: %p still on a buffer list. xflags %X", 1916 bp, bp->b_xflags)); 1917 1918 if (bp->b_bufsize) 1919 allocbuf(bp, 0); 1920 1921 bp->b_flags = 0; 1922 bp->b_ioflags = 0; 1923 bp->b_xflags = 0; 1924 bp->b_vflags = 0; 1925 bp->b_vp = NULL; 1926 bp->b_blkno = bp->b_lblkno = 0; 1927 bp->b_offset = NOOFFSET; 1928 bp->b_iodone = 0; 1929 bp->b_error = 0; 1930 bp->b_resid = 0; 1931 bp->b_bcount = 0; 1932 bp->b_npages = 0; 1933 bp->b_dirtyoff = bp->b_dirtyend = 0; 1934 bp->b_bufobj = NULL; 1935 bp->b_pin_count = 0; 1936 bp->b_fsprivate1 = NULL; 1937 bp->b_fsprivate2 = NULL; 1938 bp->b_fsprivate3 = NULL; 1939 1940 LIST_INIT(&bp->b_dep); 1941 1942 /* 1943 * If we are defragging then free the buffer. 1944 */ 1945 if (defrag) { 1946 bp->b_flags |= B_INVAL; 1947 bfreekva(bp); 1948 brelse(bp); 1949 defrag = 0; 1950 goto restart; 1951 } 1952 1953 /* 1954 * Notify any waiters for the buffer lock about 1955 * identity change by freeing the buffer. 1956 */ 1957 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 1958 bp->b_flags |= B_INVAL; 1959 bfreekva(bp); 1960 brelse(bp); 1961 goto restart; 1962 } 1963 1964 /* 1965 * If we are overcomitted then recover the buffer and its 1966 * KVM space. This occurs in rare situations when multiple 1967 * processes are blocked in getnewbuf() or allocbuf(). 1968 */ 1969 if (bufspace >= hibufspace) 1970 flushingbufs = 1; 1971 if (flushingbufs && bp->b_kvasize != 0) { 1972 bp->b_flags |= B_INVAL; 1973 bfreekva(bp); 1974 brelse(bp); 1975 goto restart; 1976 } 1977 if (bufspace < lobufspace) 1978 flushingbufs = 0; 1979 break; 1980 } 1981 1982 /* 1983 * If we exhausted our list, sleep as appropriate. We may have to 1984 * wakeup various daemons and write out some dirty buffers. 1985 * 1986 * Generally we are sleeping due to insufficient buffer space. 1987 */ 1988 1989 if (bp == NULL) { 1990 int flags, norunbuf; 1991 char *waitmsg; 1992 int fl; 1993 1994 if (defrag) { 1995 flags = VFS_BIO_NEED_BUFSPACE; 1996 waitmsg = "nbufkv"; 1997 } else if (bufspace >= hibufspace) { 1998 waitmsg = "nbufbs"; 1999 flags = VFS_BIO_NEED_BUFSPACE; 2000 } else { 2001 waitmsg = "newbuf"; 2002 flags = VFS_BIO_NEED_ANY; 2003 } 2004 mtx_lock(&nblock); 2005 needsbuffer |= flags; 2006 mtx_unlock(&nblock); 2007 mtx_unlock(&bqlock); 2008 2009 bd_speedup(); /* heeeelp */ 2010 if (gbflags & GB_NOWAIT_BD) 2011 return (NULL); 2012 2013 mtx_lock(&nblock); 2014 while (needsbuffer & flags) { 2015 if (vp != NULL && (td->td_pflags & TDP_BUFNEED) == 0) { 2016 mtx_unlock(&nblock); 2017 /* 2018 * getblk() is called with a vnode 2019 * locked, and some majority of the 2020 * dirty buffers may as well belong to 2021 * the vnode. Flushing the buffers 2022 * there would make a progress that 2023 * cannot be achieved by the 2024 * buf_daemon, that cannot lock the 2025 * vnode. 2026 */ 2027 norunbuf = ~(TDP_BUFNEED | TDP_NORUNNINGBUF) | 2028 (td->td_pflags & TDP_NORUNNINGBUF); 2029 /* play bufdaemon */ 2030 td->td_pflags |= TDP_BUFNEED | TDP_NORUNNINGBUF; 2031 fl = buf_do_flush(vp); 2032 td->td_pflags &= norunbuf; 2033 mtx_lock(&nblock); 2034 if (fl != 0) 2035 continue; 2036 if ((needsbuffer & flags) == 0) 2037 break; 2038 } 2039 if (msleep(&needsbuffer, &nblock, 2040 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 2041 mtx_unlock(&nblock); 2042 return (NULL); 2043 } 2044 } 2045 mtx_unlock(&nblock); 2046 } else { 2047 /* 2048 * We finally have a valid bp. We aren't quite out of the 2049 * woods, we still have to reserve kva space. In order 2050 * to keep fragmentation sane we only allocate kva in 2051 * BKVASIZE chunks. 2052 */ 2053 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 2054 2055 if (maxsize != bp->b_kvasize) { 2056 vm_offset_t addr = 0; 2057 2058 bfreekva(bp); 2059 2060 vm_map_lock(buffer_map); 2061 if (vm_map_findspace(buffer_map, 2062 vm_map_min(buffer_map), maxsize, &addr)) { 2063 /* 2064 * Uh oh. Buffer map is to fragmented. We 2065 * must defragment the map. 2066 */ 2067 atomic_add_int(&bufdefragcnt, 1); 2068 vm_map_unlock(buffer_map); 2069 defrag = 1; 2070 bp->b_flags |= B_INVAL; 2071 brelse(bp); 2072 goto restart; 2073 } 2074 if (addr) { 2075 vm_map_insert(buffer_map, NULL, 0, 2076 addr, addr + maxsize, 2077 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2078 2079 bp->b_kvabase = (caddr_t) addr; 2080 bp->b_kvasize = maxsize; 2081 atomic_add_long(&bufspace, bp->b_kvasize); 2082 atomic_add_int(&bufreusecnt, 1); 2083 } 2084 vm_map_unlock(buffer_map); 2085 } 2086 bp->b_saveaddr = bp->b_kvabase; 2087 bp->b_data = bp->b_saveaddr; 2088 } 2089 return(bp); 2090 } 2091 2092 /* 2093 * buf_daemon: 2094 * 2095 * buffer flushing daemon. Buffers are normally flushed by the 2096 * update daemon but if it cannot keep up this process starts to 2097 * take the load in an attempt to prevent getnewbuf() from blocking. 2098 */ 2099 2100 static struct kproc_desc buf_kp = { 2101 "bufdaemon", 2102 buf_daemon, 2103 &bufdaemonproc 2104 }; 2105 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2106 2107 static int 2108 buf_do_flush(struct vnode *vp) 2109 { 2110 int flushed; 2111 2112 flushed = flushbufqueues(vp, QUEUE_DIRTY, 0); 2113 /* The list empty check here is slightly racy */ 2114 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2115 mtx_lock(&Giant); 2116 flushed += flushbufqueues(vp, QUEUE_DIRTY_GIANT, 0); 2117 mtx_unlock(&Giant); 2118 } 2119 if (flushed == 0) { 2120 /* 2121 * Could not find any buffers without rollback 2122 * dependencies, so just write the first one 2123 * in the hopes of eventually making progress. 2124 */ 2125 flushbufqueues(vp, QUEUE_DIRTY, 1); 2126 if (!TAILQ_EMPTY( 2127 &bufqueues[QUEUE_DIRTY_GIANT])) { 2128 mtx_lock(&Giant); 2129 flushbufqueues(vp, QUEUE_DIRTY_GIANT, 1); 2130 mtx_unlock(&Giant); 2131 } 2132 } 2133 return (flushed); 2134 } 2135 2136 static void 2137 buf_daemon() 2138 { 2139 int lodirtysave; 2140 2141 /* 2142 * This process needs to be suspended prior to shutdown sync. 2143 */ 2144 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2145 SHUTDOWN_PRI_LAST); 2146 2147 /* 2148 * This process is allowed to take the buffer cache to the limit 2149 */ 2150 curthread->td_pflags |= TDP_NORUNNINGBUF | TDP_BUFNEED; 2151 mtx_lock(&bdlock); 2152 for (;;) { 2153 bd_request = 0; 2154 mtx_unlock(&bdlock); 2155 2156 kproc_suspend_check(bufdaemonproc); 2157 lodirtysave = lodirtybuffers; 2158 if (bd_speedupreq) { 2159 lodirtybuffers = numdirtybuffers / 2; 2160 bd_speedupreq = 0; 2161 } 2162 /* 2163 * Do the flush. Limit the amount of in-transit I/O we 2164 * allow to build up, otherwise we would completely saturate 2165 * the I/O system. Wakeup any waiting processes before we 2166 * normally would so they can run in parallel with our drain. 2167 */ 2168 while (numdirtybuffers > lodirtybuffers) { 2169 if (buf_do_flush(NULL) == 0) 2170 break; 2171 uio_yield(); 2172 } 2173 lodirtybuffers = lodirtysave; 2174 2175 /* 2176 * Only clear bd_request if we have reached our low water 2177 * mark. The buf_daemon normally waits 1 second and 2178 * then incrementally flushes any dirty buffers that have 2179 * built up, within reason. 2180 * 2181 * If we were unable to hit our low water mark and couldn't 2182 * find any flushable buffers, we sleep half a second. 2183 * Otherwise we loop immediately. 2184 */ 2185 mtx_lock(&bdlock); 2186 if (numdirtybuffers <= lodirtybuffers) { 2187 /* 2188 * We reached our low water mark, reset the 2189 * request and sleep until we are needed again. 2190 * The sleep is just so the suspend code works. 2191 */ 2192 bd_request = 0; 2193 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2194 } else { 2195 /* 2196 * We couldn't find any flushable dirty buffers but 2197 * still have too many dirty buffers, we 2198 * have to sleep and try again. (rare) 2199 */ 2200 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2201 } 2202 } 2203 } 2204 2205 /* 2206 * flushbufqueues: 2207 * 2208 * Try to flush a buffer in the dirty queue. We must be careful to 2209 * free up B_INVAL buffers instead of write them, which NFS is 2210 * particularly sensitive to. 2211 */ 2212 static int flushwithdeps = 0; 2213 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2214 0, "Number of buffers flushed with dependecies that require rollbacks"); 2215 2216 static int 2217 flushbufqueues(struct vnode *lvp, int queue, int flushdeps) 2218 { 2219 struct buf *sentinel; 2220 struct vnode *vp; 2221 struct mount *mp; 2222 struct buf *bp; 2223 int hasdeps; 2224 int flushed; 2225 int target; 2226 2227 if (lvp == NULL) { 2228 target = numdirtybuffers - lodirtybuffers; 2229 if (flushdeps && target > 2) 2230 target /= 2; 2231 } else 2232 target = flushbufqtarget; 2233 flushed = 0; 2234 bp = NULL; 2235 sentinel = malloc(sizeof(struct buf), M_TEMP, M_WAITOK | M_ZERO); 2236 sentinel->b_qindex = QUEUE_SENTINEL; 2237 mtx_lock(&bqlock); 2238 TAILQ_INSERT_HEAD(&bufqueues[queue], sentinel, b_freelist); 2239 while (flushed != target) { 2240 bp = TAILQ_NEXT(sentinel, b_freelist); 2241 if (bp != NULL) { 2242 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2243 TAILQ_INSERT_AFTER(&bufqueues[queue], bp, sentinel, 2244 b_freelist); 2245 } else 2246 break; 2247 /* 2248 * Skip sentinels inserted by other invocations of the 2249 * flushbufqueues(), taking care to not reorder them. 2250 */ 2251 if (bp->b_qindex == QUEUE_SENTINEL) 2252 continue; 2253 /* 2254 * Only flush the buffers that belong to the 2255 * vnode locked by the curthread. 2256 */ 2257 if (lvp != NULL && bp->b_vp != lvp) 2258 continue; 2259 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2260 continue; 2261 if (bp->b_pin_count > 0) { 2262 BUF_UNLOCK(bp); 2263 continue; 2264 } 2265 BO_LOCK(bp->b_bufobj); 2266 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2267 (bp->b_flags & B_DELWRI) == 0) { 2268 BO_UNLOCK(bp->b_bufobj); 2269 BUF_UNLOCK(bp); 2270 continue; 2271 } 2272 BO_UNLOCK(bp->b_bufobj); 2273 if (bp->b_flags & B_INVAL) { 2274 bremfreel(bp); 2275 mtx_unlock(&bqlock); 2276 brelse(bp); 2277 flushed++; 2278 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2279 mtx_lock(&bqlock); 2280 continue; 2281 } 2282 2283 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2284 if (flushdeps == 0) { 2285 BUF_UNLOCK(bp); 2286 continue; 2287 } 2288 hasdeps = 1; 2289 } else 2290 hasdeps = 0; 2291 /* 2292 * We must hold the lock on a vnode before writing 2293 * one of its buffers. Otherwise we may confuse, or 2294 * in the case of a snapshot vnode, deadlock the 2295 * system. 2296 * 2297 * The lock order here is the reverse of the normal 2298 * of vnode followed by buf lock. This is ok because 2299 * the NOWAIT will prevent deadlock. 2300 */ 2301 vp = bp->b_vp; 2302 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2303 BUF_UNLOCK(bp); 2304 continue; 2305 } 2306 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT | LK_CANRECURSE) == 0) { 2307 mtx_unlock(&bqlock); 2308 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2309 bp, bp->b_vp, bp->b_flags); 2310 if (curproc == bufdaemonproc) 2311 vfs_bio_awrite(bp); 2312 else { 2313 bremfree(bp); 2314 bwrite(bp); 2315 notbufdflashes++; 2316 } 2317 vn_finished_write(mp); 2318 VOP_UNLOCK(vp, 0); 2319 flushwithdeps += hasdeps; 2320 flushed++; 2321 2322 /* 2323 * Sleeping on runningbufspace while holding 2324 * vnode lock leads to deadlock. 2325 */ 2326 if (curproc == bufdaemonproc) 2327 waitrunningbufspace(); 2328 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2329 mtx_lock(&bqlock); 2330 continue; 2331 } 2332 vn_finished_write(mp); 2333 BUF_UNLOCK(bp); 2334 } 2335 TAILQ_REMOVE(&bufqueues[queue], sentinel, b_freelist); 2336 mtx_unlock(&bqlock); 2337 free(sentinel, M_TEMP); 2338 return (flushed); 2339 } 2340 2341 /* 2342 * Check to see if a block is currently memory resident. 2343 */ 2344 struct buf * 2345 incore(struct bufobj *bo, daddr_t blkno) 2346 { 2347 struct buf *bp; 2348 2349 BO_LOCK(bo); 2350 bp = gbincore(bo, blkno); 2351 BO_UNLOCK(bo); 2352 return (bp); 2353 } 2354 2355 /* 2356 * Returns true if no I/O is needed to access the 2357 * associated VM object. This is like incore except 2358 * it also hunts around in the VM system for the data. 2359 */ 2360 2361 static int 2362 inmem(struct vnode * vp, daddr_t blkno) 2363 { 2364 vm_object_t obj; 2365 vm_offset_t toff, tinc, size; 2366 vm_page_t m; 2367 vm_ooffset_t off; 2368 2369 ASSERT_VOP_LOCKED(vp, "inmem"); 2370 2371 if (incore(&vp->v_bufobj, blkno)) 2372 return 1; 2373 if (vp->v_mount == NULL) 2374 return 0; 2375 obj = vp->v_object; 2376 if (obj == NULL) 2377 return (0); 2378 2379 size = PAGE_SIZE; 2380 if (size > vp->v_mount->mnt_stat.f_iosize) 2381 size = vp->v_mount->mnt_stat.f_iosize; 2382 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2383 2384 VM_OBJECT_LOCK(obj); 2385 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2386 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2387 if (!m) 2388 goto notinmem; 2389 tinc = size; 2390 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2391 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2392 if (vm_page_is_valid(m, 2393 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2394 goto notinmem; 2395 } 2396 VM_OBJECT_UNLOCK(obj); 2397 return 1; 2398 2399 notinmem: 2400 VM_OBJECT_UNLOCK(obj); 2401 return (0); 2402 } 2403 2404 /* 2405 * vfs_setdirty: 2406 * 2407 * Sets the dirty range for a buffer based on the status of the dirty 2408 * bits in the pages comprising the buffer. 2409 * 2410 * The range is limited to the size of the buffer. 2411 * 2412 * This routine is primarily used by NFS, but is generalized for the 2413 * B_VMIO case. 2414 */ 2415 static void 2416 vfs_setdirty(struct buf *bp) 2417 { 2418 2419 /* 2420 * Degenerate case - empty buffer 2421 */ 2422 if (bp->b_bufsize == 0) 2423 return; 2424 2425 if ((bp->b_flags & B_VMIO) == 0) 2426 return; 2427 2428 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2429 vfs_setdirty_locked_object(bp); 2430 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2431 } 2432 2433 static void 2434 vfs_setdirty_locked_object(struct buf *bp) 2435 { 2436 vm_object_t object; 2437 int i; 2438 2439 object = bp->b_bufobj->bo_object; 2440 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2441 2442 /* 2443 * We qualify the scan for modified pages on whether the 2444 * object has been flushed yet. 2445 */ 2446 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2447 vm_offset_t boffset; 2448 vm_offset_t eoffset; 2449 2450 vm_page_lock_queues(); 2451 /* 2452 * test the pages to see if they have been modified directly 2453 * by users through the VM system. 2454 */ 2455 for (i = 0; i < bp->b_npages; i++) 2456 vm_page_test_dirty(bp->b_pages[i]); 2457 2458 /* 2459 * Calculate the encompassing dirty range, boffset and eoffset, 2460 * (eoffset - boffset) bytes. 2461 */ 2462 2463 for (i = 0; i < bp->b_npages; i++) { 2464 if (bp->b_pages[i]->dirty) 2465 break; 2466 } 2467 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2468 2469 for (i = bp->b_npages - 1; i >= 0; --i) { 2470 if (bp->b_pages[i]->dirty) { 2471 break; 2472 } 2473 } 2474 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2475 2476 vm_page_unlock_queues(); 2477 /* 2478 * Fit it to the buffer. 2479 */ 2480 2481 if (eoffset > bp->b_bcount) 2482 eoffset = bp->b_bcount; 2483 2484 /* 2485 * If we have a good dirty range, merge with the existing 2486 * dirty range. 2487 */ 2488 2489 if (boffset < eoffset) { 2490 if (bp->b_dirtyoff > boffset) 2491 bp->b_dirtyoff = boffset; 2492 if (bp->b_dirtyend < eoffset) 2493 bp->b_dirtyend = eoffset; 2494 } 2495 } 2496 } 2497 2498 /* 2499 * getblk: 2500 * 2501 * Get a block given a specified block and offset into a file/device. 2502 * The buffers B_DONE bit will be cleared on return, making it almost 2503 * ready for an I/O initiation. B_INVAL may or may not be set on 2504 * return. The caller should clear B_INVAL prior to initiating a 2505 * READ. 2506 * 2507 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2508 * an existing buffer. 2509 * 2510 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2511 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2512 * and then cleared based on the backing VM. If the previous buffer is 2513 * non-0-sized but invalid, B_CACHE will be cleared. 2514 * 2515 * If getblk() must create a new buffer, the new buffer is returned with 2516 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2517 * case it is returned with B_INVAL clear and B_CACHE set based on the 2518 * backing VM. 2519 * 2520 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2521 * B_CACHE bit is clear. 2522 * 2523 * What this means, basically, is that the caller should use B_CACHE to 2524 * determine whether the buffer is fully valid or not and should clear 2525 * B_INVAL prior to issuing a read. If the caller intends to validate 2526 * the buffer by loading its data area with something, the caller needs 2527 * to clear B_INVAL. If the caller does this without issuing an I/O, 2528 * the caller should set B_CACHE ( as an optimization ), else the caller 2529 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2530 * a write attempt or if it was a successfull read. If the caller 2531 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2532 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2533 */ 2534 struct buf * 2535 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2536 int flags) 2537 { 2538 struct buf *bp; 2539 struct bufobj *bo; 2540 int error; 2541 2542 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2543 ASSERT_VOP_LOCKED(vp, "getblk"); 2544 if (size > MAXBSIZE) 2545 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2546 2547 bo = &vp->v_bufobj; 2548 loop: 2549 /* 2550 * Block if we are low on buffers. Certain processes are allowed 2551 * to completely exhaust the buffer cache. 2552 * 2553 * If this check ever becomes a bottleneck it may be better to 2554 * move it into the else, when gbincore() fails. At the moment 2555 * it isn't a problem. 2556 * 2557 * XXX remove if 0 sections (clean this up after its proven) 2558 */ 2559 if (numfreebuffers == 0) { 2560 if (TD_IS_IDLETHREAD(curthread)) 2561 return NULL; 2562 mtx_lock(&nblock); 2563 needsbuffer |= VFS_BIO_NEED_ANY; 2564 mtx_unlock(&nblock); 2565 } 2566 2567 BO_LOCK(bo); 2568 bp = gbincore(bo, blkno); 2569 if (bp != NULL) { 2570 int lockflags; 2571 /* 2572 * Buffer is in-core. If the buffer is not busy, it must 2573 * be on a queue. 2574 */ 2575 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2576 2577 if (flags & GB_LOCK_NOWAIT) 2578 lockflags |= LK_NOWAIT; 2579 2580 error = BUF_TIMELOCK(bp, lockflags, 2581 BO_MTX(bo), "getblk", slpflag, slptimeo); 2582 2583 /* 2584 * If we slept and got the lock we have to restart in case 2585 * the buffer changed identities. 2586 */ 2587 if (error == ENOLCK) 2588 goto loop; 2589 /* We timed out or were interrupted. */ 2590 else if (error) 2591 return (NULL); 2592 2593 /* 2594 * The buffer is locked. B_CACHE is cleared if the buffer is 2595 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2596 * and for a VMIO buffer B_CACHE is adjusted according to the 2597 * backing VM cache. 2598 */ 2599 if (bp->b_flags & B_INVAL) 2600 bp->b_flags &= ~B_CACHE; 2601 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2602 bp->b_flags |= B_CACHE; 2603 bremfree(bp); 2604 2605 /* 2606 * check for size inconsistancies for non-VMIO case. 2607 */ 2608 2609 if (bp->b_bcount != size) { 2610 if ((bp->b_flags & B_VMIO) == 0 || 2611 (size > bp->b_kvasize)) { 2612 if (bp->b_flags & B_DELWRI) { 2613 /* 2614 * If buffer is pinned and caller does 2615 * not want sleep waiting for it to be 2616 * unpinned, bail out 2617 * */ 2618 if (bp->b_pin_count > 0) { 2619 if (flags & GB_LOCK_NOWAIT) { 2620 bqrelse(bp); 2621 return (NULL); 2622 } else { 2623 bunpin_wait(bp); 2624 } 2625 } 2626 bp->b_flags |= B_NOCACHE; 2627 bwrite(bp); 2628 } else { 2629 if (LIST_EMPTY(&bp->b_dep)) { 2630 bp->b_flags |= B_RELBUF; 2631 brelse(bp); 2632 } else { 2633 bp->b_flags |= B_NOCACHE; 2634 bwrite(bp); 2635 } 2636 } 2637 goto loop; 2638 } 2639 } 2640 2641 /* 2642 * If the size is inconsistant in the VMIO case, we can resize 2643 * the buffer. This might lead to B_CACHE getting set or 2644 * cleared. If the size has not changed, B_CACHE remains 2645 * unchanged from its previous state. 2646 */ 2647 2648 if (bp->b_bcount != size) 2649 allocbuf(bp, size); 2650 2651 KASSERT(bp->b_offset != NOOFFSET, 2652 ("getblk: no buffer offset")); 2653 2654 /* 2655 * A buffer with B_DELWRI set and B_CACHE clear must 2656 * be committed before we can return the buffer in 2657 * order to prevent the caller from issuing a read 2658 * ( due to B_CACHE not being set ) and overwriting 2659 * it. 2660 * 2661 * Most callers, including NFS and FFS, need this to 2662 * operate properly either because they assume they 2663 * can issue a read if B_CACHE is not set, or because 2664 * ( for example ) an uncached B_DELWRI might loop due 2665 * to softupdates re-dirtying the buffer. In the latter 2666 * case, B_CACHE is set after the first write completes, 2667 * preventing further loops. 2668 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2669 * above while extending the buffer, we cannot allow the 2670 * buffer to remain with B_CACHE set after the write 2671 * completes or it will represent a corrupt state. To 2672 * deal with this we set B_NOCACHE to scrap the buffer 2673 * after the write. 2674 * 2675 * We might be able to do something fancy, like setting 2676 * B_CACHE in bwrite() except if B_DELWRI is already set, 2677 * so the below call doesn't set B_CACHE, but that gets real 2678 * confusing. This is much easier. 2679 */ 2680 2681 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2682 bp->b_flags |= B_NOCACHE; 2683 bwrite(bp); 2684 goto loop; 2685 } 2686 bp->b_flags &= ~B_DONE; 2687 } else { 2688 int bsize, maxsize, vmio; 2689 off_t offset; 2690 2691 /* 2692 * Buffer is not in-core, create new buffer. The buffer 2693 * returned by getnewbuf() is locked. Note that the returned 2694 * buffer is also considered valid (not marked B_INVAL). 2695 */ 2696 BO_UNLOCK(bo); 2697 /* 2698 * If the user does not want us to create the buffer, bail out 2699 * here. 2700 */ 2701 if (flags & GB_NOCREAT) 2702 return NULL; 2703 bsize = vn_isdisk(vp, NULL) ? DEV_BSIZE : bo->bo_bsize; 2704 offset = blkno * bsize; 2705 vmio = vp->v_object != NULL; 2706 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2707 maxsize = imax(maxsize, bsize); 2708 2709 bp = getnewbuf(vp, slpflag, slptimeo, size, maxsize, flags); 2710 if (bp == NULL) { 2711 if (slpflag || slptimeo) 2712 return NULL; 2713 goto loop; 2714 } 2715 2716 /* 2717 * This code is used to make sure that a buffer is not 2718 * created while the getnewbuf routine is blocked. 2719 * This can be a problem whether the vnode is locked or not. 2720 * If the buffer is created out from under us, we have to 2721 * throw away the one we just created. 2722 * 2723 * Note: this must occur before we associate the buffer 2724 * with the vp especially considering limitations in 2725 * the splay tree implementation when dealing with duplicate 2726 * lblkno's. 2727 */ 2728 BO_LOCK(bo); 2729 if (gbincore(bo, blkno)) { 2730 BO_UNLOCK(bo); 2731 bp->b_flags |= B_INVAL; 2732 brelse(bp); 2733 goto loop; 2734 } 2735 2736 /* 2737 * Insert the buffer into the hash, so that it can 2738 * be found by incore. 2739 */ 2740 bp->b_blkno = bp->b_lblkno = blkno; 2741 bp->b_offset = offset; 2742 bgetvp(vp, bp); 2743 BO_UNLOCK(bo); 2744 2745 /* 2746 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2747 * buffer size starts out as 0, B_CACHE will be set by 2748 * allocbuf() for the VMIO case prior to it testing the 2749 * backing store for validity. 2750 */ 2751 2752 if (vmio) { 2753 bp->b_flags |= B_VMIO; 2754 #if defined(VFS_BIO_DEBUG) 2755 if (vn_canvmio(vp) != TRUE) 2756 printf("getblk: VMIO on vnode type %d\n", 2757 vp->v_type); 2758 #endif 2759 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2760 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2761 bp, vp->v_object, bp->b_bufobj->bo_object)); 2762 } else { 2763 bp->b_flags &= ~B_VMIO; 2764 KASSERT(bp->b_bufobj->bo_object == NULL, 2765 ("ARGH! has b_bufobj->bo_object %p %p\n", 2766 bp, bp->b_bufobj->bo_object)); 2767 } 2768 2769 allocbuf(bp, size); 2770 bp->b_flags &= ~B_DONE; 2771 } 2772 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2773 BUF_ASSERT_HELD(bp); 2774 KASSERT(bp->b_bufobj == bo, 2775 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2776 return (bp); 2777 } 2778 2779 /* 2780 * Get an empty, disassociated buffer of given size. The buffer is initially 2781 * set to B_INVAL. 2782 */ 2783 struct buf * 2784 geteblk(int size, int flags) 2785 { 2786 struct buf *bp; 2787 int maxsize; 2788 2789 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2790 while ((bp = getnewbuf(NULL, 0, 0, size, maxsize, flags)) == NULL) { 2791 if ((flags & GB_NOWAIT_BD) && 2792 (curthread->td_pflags & TDP_BUFNEED) != 0) 2793 return (NULL); 2794 } 2795 allocbuf(bp, size); 2796 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2797 BUF_ASSERT_HELD(bp); 2798 return (bp); 2799 } 2800 2801 2802 /* 2803 * This code constitutes the buffer memory from either anonymous system 2804 * memory (in the case of non-VMIO operations) or from an associated 2805 * VM object (in the case of VMIO operations). This code is able to 2806 * resize a buffer up or down. 2807 * 2808 * Note that this code is tricky, and has many complications to resolve 2809 * deadlock or inconsistant data situations. Tread lightly!!! 2810 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2811 * the caller. Calling this code willy nilly can result in the loss of data. 2812 * 2813 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2814 * B_CACHE for the non-VMIO case. 2815 */ 2816 2817 int 2818 allocbuf(struct buf *bp, int size) 2819 { 2820 int newbsize, mbsize; 2821 int i; 2822 2823 BUF_ASSERT_HELD(bp); 2824 2825 if (bp->b_kvasize < size) 2826 panic("allocbuf: buffer too small"); 2827 2828 if ((bp->b_flags & B_VMIO) == 0) { 2829 caddr_t origbuf; 2830 int origbufsize; 2831 /* 2832 * Just get anonymous memory from the kernel. Don't 2833 * mess with B_CACHE. 2834 */ 2835 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2836 if (bp->b_flags & B_MALLOC) 2837 newbsize = mbsize; 2838 else 2839 newbsize = round_page(size); 2840 2841 if (newbsize < bp->b_bufsize) { 2842 /* 2843 * malloced buffers are not shrunk 2844 */ 2845 if (bp->b_flags & B_MALLOC) { 2846 if (newbsize) { 2847 bp->b_bcount = size; 2848 } else { 2849 free(bp->b_data, M_BIOBUF); 2850 if (bp->b_bufsize) { 2851 atomic_subtract_long( 2852 &bufmallocspace, 2853 bp->b_bufsize); 2854 bufspacewakeup(); 2855 bp->b_bufsize = 0; 2856 } 2857 bp->b_saveaddr = bp->b_kvabase; 2858 bp->b_data = bp->b_saveaddr; 2859 bp->b_bcount = 0; 2860 bp->b_flags &= ~B_MALLOC; 2861 } 2862 return 1; 2863 } 2864 vm_hold_free_pages( 2865 bp, 2866 (vm_offset_t) bp->b_data + newbsize, 2867 (vm_offset_t) bp->b_data + bp->b_bufsize); 2868 } else if (newbsize > bp->b_bufsize) { 2869 /* 2870 * We only use malloced memory on the first allocation. 2871 * and revert to page-allocated memory when the buffer 2872 * grows. 2873 */ 2874 /* 2875 * There is a potential smp race here that could lead 2876 * to bufmallocspace slightly passing the max. It 2877 * is probably extremely rare and not worth worrying 2878 * over. 2879 */ 2880 if ( (bufmallocspace < maxbufmallocspace) && 2881 (bp->b_bufsize == 0) && 2882 (mbsize <= PAGE_SIZE/2)) { 2883 2884 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2885 bp->b_bufsize = mbsize; 2886 bp->b_bcount = size; 2887 bp->b_flags |= B_MALLOC; 2888 atomic_add_long(&bufmallocspace, mbsize); 2889 return 1; 2890 } 2891 origbuf = NULL; 2892 origbufsize = 0; 2893 /* 2894 * If the buffer is growing on its other-than-first allocation, 2895 * then we revert to the page-allocation scheme. 2896 */ 2897 if (bp->b_flags & B_MALLOC) { 2898 origbuf = bp->b_data; 2899 origbufsize = bp->b_bufsize; 2900 bp->b_data = bp->b_kvabase; 2901 if (bp->b_bufsize) { 2902 atomic_subtract_long(&bufmallocspace, 2903 bp->b_bufsize); 2904 bufspacewakeup(); 2905 bp->b_bufsize = 0; 2906 } 2907 bp->b_flags &= ~B_MALLOC; 2908 newbsize = round_page(newbsize); 2909 } 2910 vm_hold_load_pages( 2911 bp, 2912 (vm_offset_t) bp->b_data + bp->b_bufsize, 2913 (vm_offset_t) bp->b_data + newbsize); 2914 if (origbuf) { 2915 bcopy(origbuf, bp->b_data, origbufsize); 2916 free(origbuf, M_BIOBUF); 2917 } 2918 } 2919 } else { 2920 int desiredpages; 2921 2922 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2923 desiredpages = (size == 0) ? 0 : 2924 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2925 2926 if (bp->b_flags & B_MALLOC) 2927 panic("allocbuf: VMIO buffer can't be malloced"); 2928 /* 2929 * Set B_CACHE initially if buffer is 0 length or will become 2930 * 0-length. 2931 */ 2932 if (size == 0 || bp->b_bufsize == 0) 2933 bp->b_flags |= B_CACHE; 2934 2935 if (newbsize < bp->b_bufsize) { 2936 /* 2937 * DEV_BSIZE aligned new buffer size is less then the 2938 * DEV_BSIZE aligned existing buffer size. Figure out 2939 * if we have to remove any pages. 2940 */ 2941 if (desiredpages < bp->b_npages) { 2942 vm_page_t m; 2943 2944 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2945 vm_page_lock_queues(); 2946 for (i = desiredpages; i < bp->b_npages; i++) { 2947 /* 2948 * the page is not freed here -- it 2949 * is the responsibility of 2950 * vnode_pager_setsize 2951 */ 2952 m = bp->b_pages[i]; 2953 KASSERT(m != bogus_page, 2954 ("allocbuf: bogus page found")); 2955 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2956 vm_page_lock_queues(); 2957 2958 bp->b_pages[i] = NULL; 2959 vm_page_unwire(m, 0); 2960 } 2961 vm_page_unlock_queues(); 2962 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2963 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2964 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2965 bp->b_npages = desiredpages; 2966 } 2967 } else if (size > bp->b_bcount) { 2968 /* 2969 * We are growing the buffer, possibly in a 2970 * byte-granular fashion. 2971 */ 2972 vm_object_t obj; 2973 vm_offset_t toff; 2974 vm_offset_t tinc; 2975 2976 /* 2977 * Step 1, bring in the VM pages from the object, 2978 * allocating them if necessary. We must clear 2979 * B_CACHE if these pages are not valid for the 2980 * range covered by the buffer. 2981 */ 2982 2983 obj = bp->b_bufobj->bo_object; 2984 2985 VM_OBJECT_LOCK(obj); 2986 while (bp->b_npages < desiredpages) { 2987 vm_page_t m; 2988 vm_pindex_t pi; 2989 2990 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2991 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2992 /* 2993 * note: must allocate system pages 2994 * since blocking here could intefere 2995 * with paging I/O, no matter which 2996 * process we are. 2997 */ 2998 m = vm_page_alloc(obj, pi, 2999 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 3000 VM_ALLOC_WIRED); 3001 if (m == NULL) { 3002 atomic_add_int(&vm_pageout_deficit, 3003 desiredpages - bp->b_npages); 3004 VM_OBJECT_UNLOCK(obj); 3005 VM_WAIT; 3006 VM_OBJECT_LOCK(obj); 3007 } else { 3008 if (m->valid == 0) 3009 bp->b_flags &= ~B_CACHE; 3010 bp->b_pages[bp->b_npages] = m; 3011 ++bp->b_npages; 3012 } 3013 continue; 3014 } 3015 3016 /* 3017 * We found a page. If we have to sleep on it, 3018 * retry because it might have gotten freed out 3019 * from under us. 3020 * 3021 * We can only test VPO_BUSY here. Blocking on 3022 * m->busy might lead to a deadlock: 3023 * 3024 * vm_fault->getpages->cluster_read->allocbuf 3025 * 3026 */ 3027 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 3028 continue; 3029 3030 /* 3031 * We have a good page. 3032 */ 3033 vm_page_lock_queues(); 3034 vm_page_wire(m); 3035 vm_page_unlock_queues(); 3036 bp->b_pages[bp->b_npages] = m; 3037 ++bp->b_npages; 3038 } 3039 3040 /* 3041 * Step 2. We've loaded the pages into the buffer, 3042 * we have to figure out if we can still have B_CACHE 3043 * set. Note that B_CACHE is set according to the 3044 * byte-granular range ( bcount and size ), new the 3045 * aligned range ( newbsize ). 3046 * 3047 * The VM test is against m->valid, which is DEV_BSIZE 3048 * aligned. Needless to say, the validity of the data 3049 * needs to also be DEV_BSIZE aligned. Note that this 3050 * fails with NFS if the server or some other client 3051 * extends the file's EOF. If our buffer is resized, 3052 * B_CACHE may remain set! XXX 3053 */ 3054 3055 toff = bp->b_bcount; 3056 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 3057 3058 while ((bp->b_flags & B_CACHE) && toff < size) { 3059 vm_pindex_t pi; 3060 3061 if (tinc > (size - toff)) 3062 tinc = size - toff; 3063 3064 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 3065 PAGE_SHIFT; 3066 3067 vfs_buf_test_cache( 3068 bp, 3069 bp->b_offset, 3070 toff, 3071 tinc, 3072 bp->b_pages[pi] 3073 ); 3074 toff += tinc; 3075 tinc = PAGE_SIZE; 3076 } 3077 VM_OBJECT_UNLOCK(obj); 3078 3079 /* 3080 * Step 3, fixup the KVM pmap. Remember that 3081 * bp->b_data is relative to bp->b_offset, but 3082 * bp->b_offset may be offset into the first page. 3083 */ 3084 3085 bp->b_data = (caddr_t) 3086 trunc_page((vm_offset_t)bp->b_data); 3087 pmap_qenter( 3088 (vm_offset_t)bp->b_data, 3089 bp->b_pages, 3090 bp->b_npages 3091 ); 3092 3093 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 3094 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 3095 } 3096 } 3097 if (newbsize < bp->b_bufsize) 3098 bufspacewakeup(); 3099 bp->b_bufsize = newbsize; /* actual buffer allocation */ 3100 bp->b_bcount = size; /* requested buffer size */ 3101 return 1; 3102 } 3103 3104 void 3105 biodone(struct bio *bp) 3106 { 3107 struct mtx *mtxp; 3108 void (*done)(struct bio *); 3109 3110 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3111 mtx_lock(mtxp); 3112 bp->bio_flags |= BIO_DONE; 3113 done = bp->bio_done; 3114 if (done == NULL) 3115 wakeup(bp); 3116 mtx_unlock(mtxp); 3117 if (done != NULL) 3118 done(bp); 3119 } 3120 3121 /* 3122 * Wait for a BIO to finish. 3123 * 3124 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3125 * case is not yet clear. 3126 */ 3127 int 3128 biowait(struct bio *bp, const char *wchan) 3129 { 3130 struct mtx *mtxp; 3131 3132 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3133 mtx_lock(mtxp); 3134 while ((bp->bio_flags & BIO_DONE) == 0) 3135 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3136 mtx_unlock(mtxp); 3137 if (bp->bio_error != 0) 3138 return (bp->bio_error); 3139 if (!(bp->bio_flags & BIO_ERROR)) 3140 return (0); 3141 return (EIO); 3142 } 3143 3144 void 3145 biofinish(struct bio *bp, struct devstat *stat, int error) 3146 { 3147 3148 if (error) { 3149 bp->bio_error = error; 3150 bp->bio_flags |= BIO_ERROR; 3151 } 3152 if (stat != NULL) 3153 devstat_end_transaction_bio(stat, bp); 3154 biodone(bp); 3155 } 3156 3157 /* 3158 * bufwait: 3159 * 3160 * Wait for buffer I/O completion, returning error status. The buffer 3161 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3162 * error and cleared. 3163 */ 3164 int 3165 bufwait(struct buf *bp) 3166 { 3167 if (bp->b_iocmd == BIO_READ) 3168 bwait(bp, PRIBIO, "biord"); 3169 else 3170 bwait(bp, PRIBIO, "biowr"); 3171 if (bp->b_flags & B_EINTR) { 3172 bp->b_flags &= ~B_EINTR; 3173 return (EINTR); 3174 } 3175 if (bp->b_ioflags & BIO_ERROR) { 3176 return (bp->b_error ? bp->b_error : EIO); 3177 } else { 3178 return (0); 3179 } 3180 } 3181 3182 /* 3183 * Call back function from struct bio back up to struct buf. 3184 */ 3185 static void 3186 bufdonebio(struct bio *bip) 3187 { 3188 struct buf *bp; 3189 3190 bp = bip->bio_caller2; 3191 bp->b_resid = bp->b_bcount - bip->bio_completed; 3192 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3193 bp->b_ioflags = bip->bio_flags; 3194 bp->b_error = bip->bio_error; 3195 if (bp->b_error) 3196 bp->b_ioflags |= BIO_ERROR; 3197 bufdone(bp); 3198 g_destroy_bio(bip); 3199 } 3200 3201 void 3202 dev_strategy(struct cdev *dev, struct buf *bp) 3203 { 3204 struct cdevsw *csw; 3205 struct bio *bip; 3206 3207 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3208 panic("b_iocmd botch"); 3209 for (;;) { 3210 bip = g_new_bio(); 3211 if (bip != NULL) 3212 break; 3213 /* Try again later */ 3214 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3215 } 3216 bip->bio_cmd = bp->b_iocmd; 3217 bip->bio_offset = bp->b_iooffset; 3218 bip->bio_length = bp->b_bcount; 3219 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3220 bip->bio_data = bp->b_data; 3221 bip->bio_done = bufdonebio; 3222 bip->bio_caller2 = bp; 3223 bip->bio_dev = dev; 3224 KASSERT(dev->si_refcount > 0, 3225 ("dev_strategy on un-referenced struct cdev *(%s)", 3226 devtoname(dev))); 3227 csw = dev_refthread(dev); 3228 if (csw == NULL) { 3229 g_destroy_bio(bip); 3230 bp->b_error = ENXIO; 3231 bp->b_ioflags = BIO_ERROR; 3232 bufdone(bp); 3233 return; 3234 } 3235 (*csw->d_strategy)(bip); 3236 dev_relthread(dev); 3237 } 3238 3239 /* 3240 * bufdone: 3241 * 3242 * Finish I/O on a buffer, optionally calling a completion function. 3243 * This is usually called from an interrupt so process blocking is 3244 * not allowed. 3245 * 3246 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3247 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3248 * assuming B_INVAL is clear. 3249 * 3250 * For the VMIO case, we set B_CACHE if the op was a read and no 3251 * read error occured, or if the op was a write. B_CACHE is never 3252 * set if the buffer is invalid or otherwise uncacheable. 3253 * 3254 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3255 * initiator to leave B_INVAL set to brelse the buffer out of existance 3256 * in the biodone routine. 3257 */ 3258 void 3259 bufdone(struct buf *bp) 3260 { 3261 struct bufobj *dropobj; 3262 void (*biodone)(struct buf *); 3263 3264 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3265 dropobj = NULL; 3266 3267 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3268 BUF_ASSERT_HELD(bp); 3269 3270 runningbufwakeup(bp); 3271 if (bp->b_iocmd == BIO_WRITE) 3272 dropobj = bp->b_bufobj; 3273 /* call optional completion function if requested */ 3274 if (bp->b_iodone != NULL) { 3275 biodone = bp->b_iodone; 3276 bp->b_iodone = NULL; 3277 (*biodone) (bp); 3278 if (dropobj) 3279 bufobj_wdrop(dropobj); 3280 return; 3281 } 3282 3283 bufdone_finish(bp); 3284 3285 if (dropobj) 3286 bufobj_wdrop(dropobj); 3287 } 3288 3289 void 3290 bufdone_finish(struct buf *bp) 3291 { 3292 BUF_ASSERT_HELD(bp); 3293 3294 if (!LIST_EMPTY(&bp->b_dep)) 3295 buf_complete(bp); 3296 3297 if (bp->b_flags & B_VMIO) { 3298 int i; 3299 vm_ooffset_t foff; 3300 vm_page_t m; 3301 vm_object_t obj; 3302 int iosize; 3303 struct vnode *vp = bp->b_vp; 3304 3305 obj = bp->b_bufobj->bo_object; 3306 3307 #if defined(VFS_BIO_DEBUG) 3308 mp_fixme("usecount and vflag accessed without locks."); 3309 if (vp->v_usecount == 0) { 3310 panic("biodone: zero vnode ref count"); 3311 } 3312 3313 KASSERT(vp->v_object != NULL, 3314 ("biodone: vnode %p has no vm_object", vp)); 3315 #endif 3316 3317 foff = bp->b_offset; 3318 KASSERT(bp->b_offset != NOOFFSET, 3319 ("biodone: no buffer offset")); 3320 3321 VM_OBJECT_LOCK(obj); 3322 #if defined(VFS_BIO_DEBUG) 3323 if (obj->paging_in_progress < bp->b_npages) { 3324 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3325 obj->paging_in_progress, bp->b_npages); 3326 } 3327 #endif 3328 3329 /* 3330 * Set B_CACHE if the op was a normal read and no error 3331 * occured. B_CACHE is set for writes in the b*write() 3332 * routines. 3333 */ 3334 iosize = bp->b_bcount - bp->b_resid; 3335 if (bp->b_iocmd == BIO_READ && 3336 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3337 !(bp->b_ioflags & BIO_ERROR)) { 3338 bp->b_flags |= B_CACHE; 3339 } 3340 for (i = 0; i < bp->b_npages; i++) { 3341 int bogusflag = 0; 3342 int resid; 3343 3344 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3345 if (resid > iosize) 3346 resid = iosize; 3347 3348 /* 3349 * cleanup bogus pages, restoring the originals 3350 */ 3351 m = bp->b_pages[i]; 3352 if (m == bogus_page) { 3353 bogusflag = 1; 3354 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3355 if (m == NULL) 3356 panic("biodone: page disappeared!"); 3357 bp->b_pages[i] = m; 3358 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3359 bp->b_pages, bp->b_npages); 3360 } 3361 #if defined(VFS_BIO_DEBUG) 3362 if (OFF_TO_IDX(foff) != m->pindex) { 3363 printf( 3364 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3365 (intmax_t)foff, (uintmax_t)m->pindex); 3366 } 3367 #endif 3368 3369 /* 3370 * In the write case, the valid and clean bits are 3371 * already changed correctly ( see bdwrite() ), so we 3372 * only need to do this here in the read case. 3373 */ 3374 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3375 KASSERT((m->dirty & vm_page_bits(foff & 3376 PAGE_MASK, resid)) == 0, ("bufdone_finish:" 3377 " page %p has unexpected dirty bits", m)); 3378 vfs_page_set_valid(bp, foff, m); 3379 } 3380 3381 /* 3382 * when debugging new filesystems or buffer I/O methods, this 3383 * is the most common error that pops up. if you see this, you 3384 * have not set the page busy flag correctly!!! 3385 */ 3386 if (m->busy == 0) { 3387 printf("biodone: page busy < 0, " 3388 "pindex: %d, foff: 0x(%x,%x), " 3389 "resid: %d, index: %d\n", 3390 (int) m->pindex, (int)(foff >> 32), 3391 (int) foff & 0xffffffff, resid, i); 3392 if (!vn_isdisk(vp, NULL)) 3393 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3394 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3395 (intmax_t) bp->b_lblkno, 3396 bp->b_flags, bp->b_npages); 3397 else 3398 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3399 (intmax_t) bp->b_lblkno, 3400 bp->b_flags, bp->b_npages); 3401 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3402 (u_long)m->valid, (u_long)m->dirty, 3403 m->wire_count); 3404 panic("biodone: page busy < 0\n"); 3405 } 3406 vm_page_io_finish(m); 3407 vm_object_pip_subtract(obj, 1); 3408 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3409 iosize -= resid; 3410 } 3411 vm_object_pip_wakeupn(obj, 0); 3412 VM_OBJECT_UNLOCK(obj); 3413 } 3414 3415 /* 3416 * For asynchronous completions, release the buffer now. The brelse 3417 * will do a wakeup there if necessary - so no need to do a wakeup 3418 * here in the async case. The sync case always needs to do a wakeup. 3419 */ 3420 3421 if (bp->b_flags & B_ASYNC) { 3422 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3423 brelse(bp); 3424 else 3425 bqrelse(bp); 3426 } else 3427 bdone(bp); 3428 } 3429 3430 /* 3431 * This routine is called in lieu of iodone in the case of 3432 * incomplete I/O. This keeps the busy status for pages 3433 * consistant. 3434 */ 3435 void 3436 vfs_unbusy_pages(struct buf *bp) 3437 { 3438 int i; 3439 vm_object_t obj; 3440 vm_page_t m; 3441 3442 runningbufwakeup(bp); 3443 if (!(bp->b_flags & B_VMIO)) 3444 return; 3445 3446 obj = bp->b_bufobj->bo_object; 3447 VM_OBJECT_LOCK(obj); 3448 for (i = 0; i < bp->b_npages; i++) { 3449 m = bp->b_pages[i]; 3450 if (m == bogus_page) { 3451 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3452 if (!m) 3453 panic("vfs_unbusy_pages: page missing\n"); 3454 bp->b_pages[i] = m; 3455 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3456 bp->b_pages, bp->b_npages); 3457 } 3458 vm_object_pip_subtract(obj, 1); 3459 vm_page_io_finish(m); 3460 } 3461 vm_object_pip_wakeupn(obj, 0); 3462 VM_OBJECT_UNLOCK(obj); 3463 } 3464 3465 /* 3466 * vfs_page_set_valid: 3467 * 3468 * Set the valid bits in a page based on the supplied offset. The 3469 * range is restricted to the buffer's size. 3470 * 3471 * This routine is typically called after a read completes. 3472 */ 3473 static void 3474 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3475 { 3476 vm_ooffset_t eoff; 3477 3478 /* 3479 * Compute the end offset, eoff, such that [off, eoff) does not span a 3480 * page boundary and eoff is not greater than the end of the buffer. 3481 * The end of the buffer, in this case, is our file EOF, not the 3482 * allocation size of the buffer. 3483 */ 3484 eoff = (off + PAGE_SIZE) & ~(vm_ooffset_t)PAGE_MASK; 3485 if (eoff > bp->b_offset + bp->b_bcount) 3486 eoff = bp->b_offset + bp->b_bcount; 3487 3488 /* 3489 * Set valid range. This is typically the entire buffer and thus the 3490 * entire page. 3491 */ 3492 if (eoff > off) 3493 vm_page_set_valid(m, off & PAGE_MASK, eoff - off); 3494 } 3495 3496 /* 3497 * vfs_page_set_validclean: 3498 * 3499 * Set the valid bits and clear the dirty bits in a page based on the 3500 * supplied offset. The range is restricted to the buffer's size. 3501 */ 3502 static void 3503 vfs_page_set_validclean(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3504 { 3505 vm_ooffset_t soff, eoff; 3506 3507 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3508 /* 3509 * Start and end offsets in buffer. eoff - soff may not cross a 3510 * page boundry or cross the end of the buffer. The end of the 3511 * buffer, in this case, is our file EOF, not the allocation size 3512 * of the buffer. 3513 */ 3514 soff = off; 3515 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3516 if (eoff > bp->b_offset + bp->b_bcount) 3517 eoff = bp->b_offset + bp->b_bcount; 3518 3519 /* 3520 * Set valid range. This is typically the entire buffer and thus the 3521 * entire page. 3522 */ 3523 if (eoff > soff) { 3524 vm_page_set_validclean( 3525 m, 3526 (vm_offset_t) (soff & PAGE_MASK), 3527 (vm_offset_t) (eoff - soff) 3528 ); 3529 } 3530 } 3531 3532 /* 3533 * This routine is called before a device strategy routine. 3534 * It is used to tell the VM system that paging I/O is in 3535 * progress, and treat the pages associated with the buffer 3536 * almost as being VPO_BUSY. Also the object paging_in_progress 3537 * flag is handled to make sure that the object doesn't become 3538 * inconsistant. 3539 * 3540 * Since I/O has not been initiated yet, certain buffer flags 3541 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3542 * and should be ignored. 3543 */ 3544 void 3545 vfs_busy_pages(struct buf *bp, int clear_modify) 3546 { 3547 int i, bogus; 3548 vm_object_t obj; 3549 vm_ooffset_t foff; 3550 vm_page_t m; 3551 3552 if (!(bp->b_flags & B_VMIO)) 3553 return; 3554 3555 obj = bp->b_bufobj->bo_object; 3556 foff = bp->b_offset; 3557 KASSERT(bp->b_offset != NOOFFSET, 3558 ("vfs_busy_pages: no buffer offset")); 3559 VM_OBJECT_LOCK(obj); 3560 if (bp->b_bufsize != 0) 3561 vfs_setdirty_locked_object(bp); 3562 retry: 3563 for (i = 0; i < bp->b_npages; i++) { 3564 m = bp->b_pages[i]; 3565 3566 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3567 goto retry; 3568 } 3569 bogus = 0; 3570 if (clear_modify) 3571 vm_page_lock_queues(); 3572 for (i = 0; i < bp->b_npages; i++) { 3573 m = bp->b_pages[i]; 3574 3575 if ((bp->b_flags & B_CLUSTER) == 0) { 3576 vm_object_pip_add(obj, 1); 3577 vm_page_io_start(m); 3578 } 3579 /* 3580 * When readying a buffer for a read ( i.e 3581 * clear_modify == 0 ), it is important to do 3582 * bogus_page replacement for valid pages in 3583 * partially instantiated buffers. Partially 3584 * instantiated buffers can, in turn, occur when 3585 * reconstituting a buffer from its VM backing store 3586 * base. We only have to do this if B_CACHE is 3587 * clear ( which causes the I/O to occur in the 3588 * first place ). The replacement prevents the read 3589 * I/O from overwriting potentially dirty VM-backed 3590 * pages. XXX bogus page replacement is, uh, bogus. 3591 * It may not work properly with small-block devices. 3592 * We need to find a better way. 3593 */ 3594 if (clear_modify) { 3595 pmap_remove_write(m); 3596 vfs_page_set_validclean(bp, foff, m); 3597 } else if (m->valid == VM_PAGE_BITS_ALL && 3598 (bp->b_flags & B_CACHE) == 0) { 3599 bp->b_pages[i] = bogus_page; 3600 bogus++; 3601 } 3602 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3603 } 3604 if (clear_modify) 3605 vm_page_unlock_queues(); 3606 VM_OBJECT_UNLOCK(obj); 3607 if (bogus) 3608 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3609 bp->b_pages, bp->b_npages); 3610 } 3611 3612 /* 3613 * Tell the VM system that the pages associated with this buffer 3614 * are clean. This is used for delayed writes where the data is 3615 * going to go to disk eventually without additional VM intevention. 3616 * 3617 * Note that while we only really need to clean through to b_bcount, we 3618 * just go ahead and clean through to b_bufsize. 3619 */ 3620 static void 3621 vfs_clean_pages(struct buf *bp) 3622 { 3623 int i; 3624 vm_ooffset_t foff, noff, eoff; 3625 vm_page_t m; 3626 3627 if (!(bp->b_flags & B_VMIO)) 3628 return; 3629 3630 foff = bp->b_offset; 3631 KASSERT(bp->b_offset != NOOFFSET, 3632 ("vfs_clean_pages: no buffer offset")); 3633 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3634 vm_page_lock_queues(); 3635 for (i = 0; i < bp->b_npages; i++) { 3636 m = bp->b_pages[i]; 3637 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3638 eoff = noff; 3639 3640 if (eoff > bp->b_offset + bp->b_bufsize) 3641 eoff = bp->b_offset + bp->b_bufsize; 3642 vfs_page_set_validclean(bp, foff, m); 3643 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3644 foff = noff; 3645 } 3646 vm_page_unlock_queues(); 3647 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3648 } 3649 3650 /* 3651 * vfs_bio_set_valid: 3652 * 3653 * Set the range within the buffer to valid. The range is 3654 * relative to the beginning of the buffer, b_offset. Note that 3655 * b_offset itself may be offset from the beginning of the first 3656 * page. 3657 */ 3658 void 3659 vfs_bio_set_valid(struct buf *bp, int base, int size) 3660 { 3661 int i, n; 3662 vm_page_t m; 3663 3664 if (!(bp->b_flags & B_VMIO)) 3665 return; 3666 3667 /* 3668 * Fixup base to be relative to beginning of first page. 3669 * Set initial n to be the maximum number of bytes in the 3670 * first page that can be validated. 3671 */ 3672 base += (bp->b_offset & PAGE_MASK); 3673 n = PAGE_SIZE - (base & PAGE_MASK); 3674 3675 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3676 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3677 m = bp->b_pages[i]; 3678 if (n > size) 3679 n = size; 3680 vm_page_set_valid(m, base & PAGE_MASK, n); 3681 base += n; 3682 size -= n; 3683 n = PAGE_SIZE; 3684 } 3685 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3686 } 3687 3688 /* 3689 * vfs_bio_clrbuf: 3690 * 3691 * If the specified buffer is a non-VMIO buffer, clear the entire 3692 * buffer. If the specified buffer is a VMIO buffer, clear and 3693 * validate only the previously invalid portions of the buffer. 3694 * This routine essentially fakes an I/O, so we need to clear 3695 * BIO_ERROR and B_INVAL. 3696 * 3697 * Note that while we only theoretically need to clear through b_bcount, 3698 * we go ahead and clear through b_bufsize. 3699 */ 3700 void 3701 vfs_bio_clrbuf(struct buf *bp) 3702 { 3703 int i, j, mask; 3704 caddr_t sa, ea; 3705 3706 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3707 clrbuf(bp); 3708 return; 3709 } 3710 bp->b_flags &= ~B_INVAL; 3711 bp->b_ioflags &= ~BIO_ERROR; 3712 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3713 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3714 (bp->b_offset & PAGE_MASK) == 0) { 3715 if (bp->b_pages[0] == bogus_page) 3716 goto unlock; 3717 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3718 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3719 if ((bp->b_pages[0]->valid & mask) == mask) 3720 goto unlock; 3721 if ((bp->b_pages[0]->valid & mask) == 0) { 3722 bzero(bp->b_data, bp->b_bufsize); 3723 bp->b_pages[0]->valid |= mask; 3724 goto unlock; 3725 } 3726 } 3727 ea = sa = bp->b_data; 3728 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3729 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3730 ea = (caddr_t)(vm_offset_t)ulmin( 3731 (u_long)(vm_offset_t)ea, 3732 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3733 if (bp->b_pages[i] == bogus_page) 3734 continue; 3735 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3736 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3737 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3738 if ((bp->b_pages[i]->valid & mask) == mask) 3739 continue; 3740 if ((bp->b_pages[i]->valid & mask) == 0) 3741 bzero(sa, ea - sa); 3742 else { 3743 for (; sa < ea; sa += DEV_BSIZE, j++) { 3744 if ((bp->b_pages[i]->valid & (1 << j)) == 0) 3745 bzero(sa, DEV_BSIZE); 3746 } 3747 } 3748 bp->b_pages[i]->valid |= mask; 3749 } 3750 unlock: 3751 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3752 bp->b_resid = 0; 3753 } 3754 3755 /* 3756 * vm_hold_load_pages and vm_hold_free_pages get pages into 3757 * a buffers address space. The pages are anonymous and are 3758 * not associated with a file object. 3759 */ 3760 static void 3761 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3762 { 3763 vm_offset_t pg; 3764 vm_page_t p; 3765 int index; 3766 3767 to = round_page(to); 3768 from = round_page(from); 3769 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3770 3771 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3772 tryagain: 3773 /* 3774 * note: must allocate system pages since blocking here 3775 * could interfere with paging I/O, no matter which 3776 * process we are. 3777 */ 3778 p = vm_page_alloc(NULL, pg >> PAGE_SHIFT, VM_ALLOC_NOOBJ | 3779 VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3780 if (!p) { 3781 atomic_add_int(&vm_pageout_deficit, 3782 (to - pg) >> PAGE_SHIFT); 3783 VM_WAIT; 3784 goto tryagain; 3785 } 3786 pmap_qenter(pg, &p, 1); 3787 bp->b_pages[index] = p; 3788 } 3789 bp->b_npages = index; 3790 } 3791 3792 /* Return pages associated with this buf to the vm system */ 3793 static void 3794 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3795 { 3796 vm_offset_t pg; 3797 vm_page_t p; 3798 int index, newnpages; 3799 3800 from = round_page(from); 3801 to = round_page(to); 3802 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3803 3804 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3805 p = bp->b_pages[index]; 3806 if (p && (index < bp->b_npages)) { 3807 if (p->busy) { 3808 printf( 3809 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3810 (intmax_t)bp->b_blkno, 3811 (intmax_t)bp->b_lblkno); 3812 } 3813 bp->b_pages[index] = NULL; 3814 pmap_qremove(pg, 1); 3815 p->wire_count--; 3816 vm_page_free(p); 3817 atomic_subtract_int(&cnt.v_wire_count, 1); 3818 } 3819 } 3820 bp->b_npages = newnpages; 3821 } 3822 3823 /* 3824 * Map an IO request into kernel virtual address space. 3825 * 3826 * All requests are (re)mapped into kernel VA space. 3827 * Notice that we use b_bufsize for the size of the buffer 3828 * to be mapped. b_bcount might be modified by the driver. 3829 * 3830 * Note that even if the caller determines that the address space should 3831 * be valid, a race or a smaller-file mapped into a larger space may 3832 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3833 * check the return value. 3834 */ 3835 int 3836 vmapbuf(struct buf *bp) 3837 { 3838 caddr_t addr, kva; 3839 vm_prot_t prot; 3840 int pidx, i; 3841 struct vm_page *m; 3842 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3843 3844 if (bp->b_bufsize < 0) 3845 return (-1); 3846 prot = VM_PROT_READ; 3847 if (bp->b_iocmd == BIO_READ) 3848 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3849 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3850 addr < bp->b_data + bp->b_bufsize; 3851 addr += PAGE_SIZE, pidx++) { 3852 /* 3853 * Do the vm_fault if needed; do the copy-on-write thing 3854 * when reading stuff off device into memory. 3855 * 3856 * NOTE! Must use pmap_extract() because addr may be in 3857 * the userland address space, and kextract is only guarenteed 3858 * to work for the kernland address space (see: sparc64 port). 3859 */ 3860 retry: 3861 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3862 prot) < 0) { 3863 vm_page_lock_queues(); 3864 for (i = 0; i < pidx; ++i) { 3865 vm_page_unhold(bp->b_pages[i]); 3866 bp->b_pages[i] = NULL; 3867 } 3868 vm_page_unlock_queues(); 3869 return(-1); 3870 } 3871 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3872 if (m == NULL) 3873 goto retry; 3874 bp->b_pages[pidx] = m; 3875 } 3876 if (pidx > btoc(MAXPHYS)) 3877 panic("vmapbuf: mapped more than MAXPHYS"); 3878 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3879 3880 kva = bp->b_saveaddr; 3881 bp->b_npages = pidx; 3882 bp->b_saveaddr = bp->b_data; 3883 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3884 return(0); 3885 } 3886 3887 /* 3888 * Free the io map PTEs associated with this IO operation. 3889 * We also invalidate the TLB entries and restore the original b_addr. 3890 */ 3891 void 3892 vunmapbuf(struct buf *bp) 3893 { 3894 int pidx; 3895 int npages; 3896 3897 npages = bp->b_npages; 3898 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3899 vm_page_lock_queues(); 3900 for (pidx = 0; pidx < npages; pidx++) 3901 vm_page_unhold(bp->b_pages[pidx]); 3902 vm_page_unlock_queues(); 3903 3904 bp->b_data = bp->b_saveaddr; 3905 } 3906 3907 void 3908 bdone(struct buf *bp) 3909 { 3910 struct mtx *mtxp; 3911 3912 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3913 mtx_lock(mtxp); 3914 bp->b_flags |= B_DONE; 3915 wakeup(bp); 3916 mtx_unlock(mtxp); 3917 } 3918 3919 void 3920 bwait(struct buf *bp, u_char pri, const char *wchan) 3921 { 3922 struct mtx *mtxp; 3923 3924 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3925 mtx_lock(mtxp); 3926 while ((bp->b_flags & B_DONE) == 0) 3927 msleep(bp, mtxp, pri, wchan, 0); 3928 mtx_unlock(mtxp); 3929 } 3930 3931 int 3932 bufsync(struct bufobj *bo, int waitfor) 3933 { 3934 3935 return (VOP_FSYNC(bo->__bo_vnode, waitfor, curthread)); 3936 } 3937 3938 void 3939 bufstrategy(struct bufobj *bo, struct buf *bp) 3940 { 3941 int i = 0; 3942 struct vnode *vp; 3943 3944 vp = bp->b_vp; 3945 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3946 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3947 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3948 i = VOP_STRATEGY(vp, bp); 3949 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3950 } 3951 3952 void 3953 bufobj_wrefl(struct bufobj *bo) 3954 { 3955 3956 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3957 ASSERT_BO_LOCKED(bo); 3958 bo->bo_numoutput++; 3959 } 3960 3961 void 3962 bufobj_wref(struct bufobj *bo) 3963 { 3964 3965 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3966 BO_LOCK(bo); 3967 bo->bo_numoutput++; 3968 BO_UNLOCK(bo); 3969 } 3970 3971 void 3972 bufobj_wdrop(struct bufobj *bo) 3973 { 3974 3975 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3976 BO_LOCK(bo); 3977 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3978 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3979 bo->bo_flag &= ~BO_WWAIT; 3980 wakeup(&bo->bo_numoutput); 3981 } 3982 BO_UNLOCK(bo); 3983 } 3984 3985 int 3986 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3987 { 3988 int error; 3989 3990 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3991 ASSERT_BO_LOCKED(bo); 3992 error = 0; 3993 while (bo->bo_numoutput) { 3994 bo->bo_flag |= BO_WWAIT; 3995 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3996 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3997 if (error) 3998 break; 3999 } 4000 return (error); 4001 } 4002 4003 void 4004 bpin(struct buf *bp) 4005 { 4006 struct mtx *mtxp; 4007 4008 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4009 mtx_lock(mtxp); 4010 bp->b_pin_count++; 4011 mtx_unlock(mtxp); 4012 } 4013 4014 void 4015 bunpin(struct buf *bp) 4016 { 4017 struct mtx *mtxp; 4018 4019 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4020 mtx_lock(mtxp); 4021 if (--bp->b_pin_count == 0) 4022 wakeup(bp); 4023 mtx_unlock(mtxp); 4024 } 4025 4026 void 4027 bunpin_wait(struct buf *bp) 4028 { 4029 struct mtx *mtxp; 4030 4031 mtxp = mtx_pool_find(mtxpool_sleep, bp); 4032 mtx_lock(mtxp); 4033 while (bp->b_pin_count > 0) 4034 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 4035 mtx_unlock(mtxp); 4036 } 4037 4038 #include "opt_ddb.h" 4039 #ifdef DDB 4040 #include <ddb/ddb.h> 4041 4042 /* DDB command to show buffer data */ 4043 DB_SHOW_COMMAND(buffer, db_show_buffer) 4044 { 4045 /* get args */ 4046 struct buf *bp = (struct buf *)addr; 4047 4048 if (!have_addr) { 4049 db_printf("usage: show buffer <addr>\n"); 4050 return; 4051 } 4052 4053 db_printf("buf at %p\n", bp); 4054 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 4055 db_printf( 4056 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 4057 "b_bufobj = (%p), b_data = %p, b_blkno = %jd, b_dep = %p\n", 4058 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 4059 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno, 4060 bp->b_dep.lh_first); 4061 if (bp->b_npages) { 4062 int i; 4063 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 4064 for (i = 0; i < bp->b_npages; i++) { 4065 vm_page_t m; 4066 m = bp->b_pages[i]; 4067 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 4068 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 4069 if ((i + 1) < bp->b_npages) 4070 db_printf(","); 4071 } 4072 db_printf("\n"); 4073 } 4074 db_printf(" "); 4075 lockmgr_printinfo(&bp->b_lock); 4076 } 4077 4078 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 4079 { 4080 struct buf *bp; 4081 int i; 4082 4083 for (i = 0; i < nbuf; i++) { 4084 bp = &buf[i]; 4085 if (BUF_ISLOCKED(bp)) { 4086 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4087 db_printf("\n"); 4088 } 4089 } 4090 } 4091 4092 DB_SHOW_COMMAND(vnodebufs, db_show_vnodebufs) 4093 { 4094 struct vnode *vp; 4095 struct buf *bp; 4096 4097 if (!have_addr) { 4098 db_printf("usage: show vnodebufs <addr>\n"); 4099 return; 4100 } 4101 vp = (struct vnode *)addr; 4102 db_printf("Clean buffers:\n"); 4103 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_clean.bv_hd, b_bobufs) { 4104 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4105 db_printf("\n"); 4106 } 4107 db_printf("Dirty buffers:\n"); 4108 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) { 4109 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 4110 db_printf("\n"); 4111 } 4112 } 4113 #endif /* DDB */ 4114