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