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