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, "biobuf", "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 * Lock that protects against bwait()/bdone()/B_DONE races. 241 */ 242 static struct mtx bpinlock; 243 244 /* 245 * Definitions for the buffer free lists. 246 */ 247 #define BUFFER_QUEUES 5 /* number of free buffer queues */ 248 249 #define QUEUE_NONE 0 /* on no queue */ 250 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 251 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 252 #define QUEUE_EMPTYKVA 3 /* empty buffer headers w/KVA assignment */ 253 #define QUEUE_EMPTY 4 /* empty buffer headers */ 254 255 /* Queues for free buffers with various properties */ 256 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 257 258 /* Lock for the bufqueues */ 259 static struct mtx bqlock; 260 261 /* 262 * Single global constant for BUF_WMESG, to avoid getting multiple references. 263 * buf_wmesg is referred from macros. 264 */ 265 const char *buf_wmesg = BUF_WMESG; 266 267 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 268 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 269 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 270 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 271 272 #ifdef DIRECTIO 273 extern void ffs_rawread_setup(void); 274 #endif /* DIRECTIO */ 275 /* 276 * numdirtywakeup: 277 * 278 * If someone is blocked due to there being too many dirty buffers, 279 * and numdirtybuffers is now reasonable, wake them up. 280 */ 281 282 static __inline void 283 numdirtywakeup(int level) 284 { 285 286 if (numdirtybuffers <= level) { 287 mtx_lock(&nblock); 288 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 289 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 290 wakeup(&needsbuffer); 291 } 292 mtx_unlock(&nblock); 293 } 294 } 295 296 /* 297 * bufspacewakeup: 298 * 299 * Called when buffer space is potentially available for recovery. 300 * getnewbuf() will block on this flag when it is unable to free 301 * sufficient buffer space. Buffer space becomes recoverable when 302 * bp's get placed back in the queues. 303 */ 304 305 static __inline void 306 bufspacewakeup(void) 307 { 308 309 /* 310 * If someone is waiting for BUF space, wake them up. Even 311 * though we haven't freed the kva space yet, the waiting 312 * process will be able to now. 313 */ 314 mtx_lock(&nblock); 315 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 316 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 317 wakeup(&needsbuffer); 318 } 319 mtx_unlock(&nblock); 320 } 321 322 /* 323 * runningbufwakeup() - in-progress I/O accounting. 324 * 325 */ 326 void 327 runningbufwakeup(struct buf *bp) 328 { 329 330 if (bp->b_runningbufspace) { 331 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 332 bp->b_runningbufspace = 0; 333 mtx_lock(&rbreqlock); 334 if (runningbufreq && runningbufspace <= lorunningspace) { 335 runningbufreq = 0; 336 wakeup(&runningbufreq); 337 } 338 mtx_unlock(&rbreqlock); 339 } 340 } 341 342 /* 343 * bufcountwakeup: 344 * 345 * Called when a buffer has been added to one of the free queues to 346 * account for the buffer and to wakeup anyone waiting for free buffers. 347 * This typically occurs when large amounts of metadata are being handled 348 * by the buffer cache ( else buffer space runs out first, usually ). 349 */ 350 351 static __inline void 352 bufcountwakeup(void) 353 { 354 355 atomic_add_int(&numfreebuffers, 1); 356 mtx_lock(&nblock); 357 if (needsbuffer) { 358 needsbuffer &= ~VFS_BIO_NEED_ANY; 359 if (numfreebuffers >= hifreebuffers) 360 needsbuffer &= ~VFS_BIO_NEED_FREE; 361 wakeup(&needsbuffer); 362 } 363 mtx_unlock(&nblock); 364 } 365 366 /* 367 * waitrunningbufspace() 368 * 369 * runningbufspace is a measure of the amount of I/O currently 370 * running. This routine is used in async-write situations to 371 * prevent creating huge backups of pending writes to a device. 372 * Only asynchronous writes are governed by this function. 373 * 374 * Reads will adjust runningbufspace, but will not block based on it. 375 * The read load has a side effect of reducing the allowed write load. 376 * 377 * This does NOT turn an async write into a sync write. It waits 378 * for earlier writes to complete and generally returns before the 379 * caller's write has reached the device. 380 */ 381 void 382 waitrunningbufspace(void) 383 { 384 385 mtx_lock(&rbreqlock); 386 while (runningbufspace > hirunningspace) { 387 ++runningbufreq; 388 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 389 } 390 mtx_unlock(&rbreqlock); 391 } 392 393 394 /* 395 * vfs_buf_test_cache: 396 * 397 * Called when a buffer is extended. This function clears the B_CACHE 398 * bit if the newly extended portion of the buffer does not contain 399 * valid data. 400 */ 401 static __inline 402 void 403 vfs_buf_test_cache(struct buf *bp, 404 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 405 vm_page_t m) 406 { 407 408 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 409 if (bp->b_flags & B_CACHE) { 410 int base = (foff + off) & PAGE_MASK; 411 if (vm_page_is_valid(m, base, size) == 0) 412 bp->b_flags &= ~B_CACHE; 413 } 414 } 415 416 /* Wake up the buffer deamon if necessary */ 417 static __inline 418 void 419 bd_wakeup(int dirtybuflevel) 420 { 421 422 mtx_lock(&bdlock); 423 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 424 bd_request = 1; 425 wakeup(&bd_request); 426 } 427 mtx_unlock(&bdlock); 428 } 429 430 /* 431 * bd_speedup - speedup the buffer cache flushing code 432 */ 433 434 static __inline 435 void 436 bd_speedup(void) 437 { 438 439 bd_wakeup(1); 440 } 441 442 /* 443 * Calculating buffer cache scaling values and reserve space for buffer 444 * headers. This is called during low level kernel initialization and 445 * may be called more then once. We CANNOT write to the memory area 446 * being reserved at this time. 447 */ 448 caddr_t 449 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 450 { 451 452 /* 453 * physmem_est is in pages. Convert it to kilobytes (assumes 454 * PAGE_SIZE is >= 1K) 455 */ 456 physmem_est = physmem_est * (PAGE_SIZE / 1024); 457 458 /* 459 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 460 * For the first 64MB of ram nominally allocate sufficient buffers to 461 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 462 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 463 * the buffer cache we limit the eventual kva reservation to 464 * maxbcache bytes. 465 * 466 * factor represents the 1/4 x ram conversion. 467 */ 468 if (nbuf == 0) { 469 int factor = 4 * BKVASIZE / 1024; 470 471 nbuf = 50; 472 if (physmem_est > 4096) 473 nbuf += min((physmem_est - 4096) / factor, 474 65536 / factor); 475 if (physmem_est > 65536) 476 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 477 478 if (maxbcache && nbuf > maxbcache / BKVASIZE) 479 nbuf = maxbcache / BKVASIZE; 480 } 481 482 #if 0 483 /* 484 * Do not allow the buffer_map to be more then 1/2 the size of the 485 * kernel_map. 486 */ 487 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 488 (BKVASIZE * 2)) { 489 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 490 (BKVASIZE * 2); 491 printf("Warning: nbufs capped at %d\n", nbuf); 492 } 493 #endif 494 495 /* 496 * swbufs are used as temporary holders for I/O, such as paging I/O. 497 * We have no less then 16 and no more then 256. 498 */ 499 nswbuf = max(min(nbuf/4, 256), 16); 500 #ifdef NSWBUF_MIN 501 if (nswbuf < NSWBUF_MIN) 502 nswbuf = NSWBUF_MIN; 503 #endif 504 #ifdef DIRECTIO 505 ffs_rawread_setup(); 506 #endif 507 508 /* 509 * Reserve space for the buffer cache buffers 510 */ 511 swbuf = (void *)v; 512 v = (caddr_t)(swbuf + nswbuf); 513 buf = (void *)v; 514 v = (caddr_t)(buf + nbuf); 515 516 return(v); 517 } 518 519 /* Initialize the buffer subsystem. Called before use of any buffers. */ 520 void 521 bufinit(void) 522 { 523 struct buf *bp; 524 int i; 525 526 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 527 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 528 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 529 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 530 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 531 mtx_init(&bpinlock, "bpin lock", NULL, MTX_DEF); 532 533 /* next, make a null set of free lists */ 534 for (i = 0; i < BUFFER_QUEUES; i++) 535 TAILQ_INIT(&bufqueues[i]); 536 537 /* finally, initialize each buffer header and stick on empty q */ 538 for (i = 0; i < nbuf; i++) { 539 bp = &buf[i]; 540 bzero(bp, sizeof *bp); 541 bp->b_flags = B_INVAL; /* we're just an empty header */ 542 bp->b_rcred = NOCRED; 543 bp->b_wcred = NOCRED; 544 bp->b_qindex = QUEUE_EMPTY; 545 bp->b_vflags = 0; 546 bp->b_xflags = 0; 547 LIST_INIT(&bp->b_dep); 548 BUF_LOCKINIT(bp); 549 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 550 } 551 552 /* 553 * maxbufspace is the absolute maximum amount of buffer space we are 554 * allowed to reserve in KVM and in real terms. The absolute maximum 555 * is nominally used by buf_daemon. hibufspace is the nominal maximum 556 * used by most other processes. The differential is required to 557 * ensure that buf_daemon is able to run when other processes might 558 * be blocked waiting for buffer space. 559 * 560 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 561 * this may result in KVM fragmentation which is not handled optimally 562 * by the system. 563 */ 564 maxbufspace = nbuf * BKVASIZE; 565 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 566 lobufspace = hibufspace - MAXBSIZE; 567 568 lorunningspace = 512 * 1024; 569 hirunningspace = 1024 * 1024; 570 571 /* 572 * Limit the amount of malloc memory since it is wired permanently into 573 * the kernel space. Even though this is accounted for in the buffer 574 * allocation, we don't want the malloced region to grow uncontrolled. 575 * The malloc scheme improves memory utilization significantly on average 576 * (small) directories. 577 */ 578 maxbufmallocspace = hibufspace / 20; 579 580 /* 581 * Reduce the chance of a deadlock occuring by limiting the number 582 * of delayed-write dirty buffers we allow to stack up. 583 */ 584 hidirtybuffers = nbuf / 4 + 20; 585 dirtybufthresh = hidirtybuffers * 9 / 10; 586 numdirtybuffers = 0; 587 /* 588 * To support extreme low-memory systems, make sure hidirtybuffers cannot 589 * eat up all available buffer space. This occurs when our minimum cannot 590 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 591 * BKVASIZE'd (8K) buffers. 592 */ 593 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 594 hidirtybuffers >>= 1; 595 } 596 lodirtybuffers = hidirtybuffers / 2; 597 598 /* 599 * Try to keep the number of free buffers in the specified range, 600 * and give special processes (e.g. like buf_daemon) access to an 601 * emergency reserve. 602 */ 603 lofreebuffers = nbuf / 18 + 5; 604 hifreebuffers = 2 * lofreebuffers; 605 numfreebuffers = nbuf; 606 607 /* 608 * Maximum number of async ops initiated per buf_daemon loop. This is 609 * somewhat of a hack at the moment, we really need to limit ourselves 610 * based on the number of bytes of I/O in-transit that were initiated 611 * from buf_daemon. 612 */ 613 614 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 615 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 616 } 617 618 /* 619 * bfreekva() - free the kva allocation for a buffer. 620 * 621 * Since this call frees up buffer space, we call bufspacewakeup(). 622 */ 623 static void 624 bfreekva(struct buf *bp) 625 { 626 627 if (bp->b_kvasize) { 628 atomic_add_int(&buffreekvacnt, 1); 629 atomic_subtract_int(&bufspace, bp->b_kvasize); 630 vm_map_lock(buffer_map); 631 vm_map_delete(buffer_map, 632 (vm_offset_t) bp->b_kvabase, 633 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 634 ); 635 vm_map_unlock(buffer_map); 636 bp->b_kvasize = 0; 637 bufspacewakeup(); 638 } 639 } 640 641 /* 642 * bremfree: 643 * 644 * Mark the buffer for removal from the appropriate free list in brelse. 645 * 646 */ 647 void 648 bremfree(struct buf *bp) 649 { 650 651 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 652 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked.")); 653 KASSERT((bp->b_flags & B_REMFREE) == 0, 654 ("bremfree: buffer %p already marked for delayed removal.", bp)); 655 KASSERT(bp->b_qindex != QUEUE_NONE, 656 ("bremfree: buffer %p not on a queue.", bp)); 657 658 bp->b_flags |= B_REMFREE; 659 /* Fixup numfreebuffers count. */ 660 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 661 atomic_subtract_int(&numfreebuffers, 1); 662 } 663 664 /* 665 * bremfreef: 666 * 667 * Force an immediate removal from a free list. Used only in nfs when 668 * it abuses the b_freelist pointer. 669 */ 670 void 671 bremfreef(struct buf *bp) 672 { 673 mtx_lock(&bqlock); 674 bremfreel(bp); 675 mtx_unlock(&bqlock); 676 } 677 678 /* 679 * bremfreel: 680 * 681 * Removes a buffer from the free list, must be called with the 682 * bqlock held. 683 */ 684 static void 685 bremfreel(struct buf *bp) 686 { 687 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 688 bp, bp->b_vp, bp->b_flags); 689 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp)); 690 KASSERT(bp->b_qindex != QUEUE_NONE, 691 ("bremfreel: buffer %p not on a queue.", bp)); 692 mtx_assert(&bqlock, MA_OWNED); 693 694 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 695 bp->b_qindex = QUEUE_NONE; 696 /* 697 * If this was a delayed bremfree() we only need to remove the buffer 698 * from the queue and return the stats are already done. 699 */ 700 if (bp->b_flags & B_REMFREE) { 701 bp->b_flags &= ~B_REMFREE; 702 return; 703 } 704 /* 705 * Fixup numfreebuffers count. If the buffer is invalid or not 706 * delayed-write, the buffer was free and we must decrement 707 * numfreebuffers. 708 */ 709 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 710 atomic_subtract_int(&numfreebuffers, 1); 711 } 712 713 714 /* 715 * Get a buffer with the specified data. Look in the cache first. We 716 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 717 * is set, the buffer is valid and we do not have to do anything ( see 718 * getblk() ). This is really just a special case of breadn(). 719 */ 720 int 721 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 722 struct buf **bpp) 723 { 724 725 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 726 } 727 728 /* 729 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 730 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 731 * the buffer is valid and we do not have to do anything. 732 */ 733 void 734 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 735 int cnt, struct ucred * cred) 736 { 737 struct buf *rabp; 738 int i; 739 740 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 741 if (inmem(vp, *rablkno)) 742 continue; 743 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 744 745 if ((rabp->b_flags & B_CACHE) == 0) { 746 if (curthread != PCPU_GET(idlethread)) 747 curthread->td_proc->p_stats->p_ru.ru_inblock++; 748 rabp->b_flags |= B_ASYNC; 749 rabp->b_flags &= ~B_INVAL; 750 rabp->b_ioflags &= ~BIO_ERROR; 751 rabp->b_iocmd = BIO_READ; 752 if (rabp->b_rcred == NOCRED && cred != NOCRED) 753 rabp->b_rcred = crhold(cred); 754 vfs_busy_pages(rabp, 0); 755 BUF_KERNPROC(rabp); 756 rabp->b_iooffset = dbtob(rabp->b_blkno); 757 bstrategy(rabp); 758 } else { 759 brelse(rabp); 760 } 761 } 762 } 763 764 /* 765 * Operates like bread, but also starts asynchronous I/O on 766 * read-ahead blocks. 767 */ 768 int 769 breadn(struct vnode * vp, daddr_t blkno, int size, 770 daddr_t * rablkno, int *rabsize, 771 int cnt, struct ucred * cred, struct buf **bpp) 772 { 773 struct buf *bp; 774 int rv = 0, readwait = 0; 775 776 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 777 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 778 779 /* if not found in cache, do some I/O */ 780 if ((bp->b_flags & B_CACHE) == 0) { 781 if (curthread != PCPU_GET(idlethread)) 782 curthread->td_proc->p_stats->p_ru.ru_inblock++; 783 bp->b_iocmd = BIO_READ; 784 bp->b_flags &= ~B_INVAL; 785 bp->b_ioflags &= ~BIO_ERROR; 786 if (bp->b_rcred == NOCRED && cred != NOCRED) 787 bp->b_rcred = crhold(cred); 788 vfs_busy_pages(bp, 0); 789 bp->b_iooffset = dbtob(bp->b_blkno); 790 bstrategy(bp); 791 ++readwait; 792 } 793 794 breada(vp, rablkno, rabsize, cnt, cred); 795 796 if (readwait) { 797 rv = bufwait(bp); 798 } 799 return (rv); 800 } 801 802 /* 803 * Write, release buffer on completion. (Done by iodone 804 * if async). Do not bother writing anything if the buffer 805 * is invalid. 806 * 807 * Note that we set B_CACHE here, indicating that buffer is 808 * fully valid and thus cacheable. This is true even of NFS 809 * now so we set it generally. This could be set either here 810 * or in biodone() since the I/O is synchronous. We put it 811 * here. 812 */ 813 int 814 bufwrite(struct buf *bp) 815 { 816 int oldflags; 817 818 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 819 if (bp->b_flags & B_INVAL) { 820 brelse(bp); 821 return (0); 822 } 823 824 oldflags = bp->b_flags; 825 826 if (BUF_REFCNT(bp) == 0) 827 panic("bufwrite: buffer is not busy???"); 828 829 if (bp->b_pin_count > 0) 830 bunpin_wait(bp); 831 832 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 833 ("FFS background buffer should not get here %p", bp)); 834 835 /* Mark the buffer clean */ 836 bundirty(bp); 837 838 bp->b_flags &= ~B_DONE; 839 bp->b_ioflags &= ~BIO_ERROR; 840 bp->b_flags |= B_CACHE; 841 bp->b_iocmd = BIO_WRITE; 842 843 bufobj_wref(bp->b_bufobj); 844 vfs_busy_pages(bp, 1); 845 846 /* 847 * Normal bwrites pipeline writes 848 */ 849 bp->b_runningbufspace = bp->b_bufsize; 850 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 851 852 if (curthread != PCPU_GET(idlethread)) 853 curthread->td_proc->p_stats->p_ru.ru_oublock++; 854 if (oldflags & B_ASYNC) 855 BUF_KERNPROC(bp); 856 bp->b_iooffset = dbtob(bp->b_blkno); 857 bstrategy(bp); 858 859 if ((oldflags & B_ASYNC) == 0) { 860 int rtval = bufwait(bp); 861 brelse(bp); 862 return (rtval); 863 } else { 864 /* 865 * don't allow the async write to saturate the I/O 866 * system. We will not deadlock here because 867 * we are blocking waiting for I/O that is already in-progress 868 * to complete. We do not block here if it is the update 869 * or syncer daemon trying to clean up as that can lead 870 * to deadlock. 871 */ 872 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0) 873 waitrunningbufspace(); 874 } 875 876 return (0); 877 } 878 879 /* 880 * Delayed write. (Buffer is marked dirty). Do not bother writing 881 * anything if the buffer is marked invalid. 882 * 883 * Note that since the buffer must be completely valid, we can safely 884 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 885 * biodone() in order to prevent getblk from writing the buffer 886 * out synchronously. 887 */ 888 void 889 bdwrite(struct buf *bp) 890 { 891 struct thread *td = curthread; 892 struct vnode *vp; 893 struct buf *nbp; 894 struct bufobj *bo; 895 896 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 897 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 898 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy")); 899 900 if (bp->b_flags & B_INVAL) { 901 brelse(bp); 902 return; 903 } 904 905 /* 906 * If we have too many dirty buffers, don't create any more. 907 * If we are wildly over our limit, then force a complete 908 * cleanup. Otherwise, just keep the situation from getting 909 * out of control. Note that we have to avoid a recursive 910 * disaster and not try to clean up after our own cleanup! 911 */ 912 vp = bp->b_vp; 913 bo = bp->b_bufobj; 914 if ((td->td_pflags & TDP_COWINPROGRESS) == 0) { 915 BO_LOCK(bo); 916 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 917 BO_UNLOCK(bo); 918 (void) VOP_FSYNC(vp, MNT_NOWAIT, td); 919 altbufferflushes++; 920 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 921 /* 922 * Try to find a buffer to flush. 923 */ 924 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 925 if ((nbp->b_vflags & BV_BKGRDINPROG) || 926 BUF_LOCK(nbp, 927 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 928 continue; 929 if (bp == nbp) 930 panic("bdwrite: found ourselves"); 931 BO_UNLOCK(bo); 932 /* Don't countdeps with the bo lock held. */ 933 if (buf_countdeps(nbp, 0)) { 934 BO_LOCK(bo); 935 BUF_UNLOCK(nbp); 936 continue; 937 } 938 if (nbp->b_flags & B_CLUSTEROK) { 939 vfs_bio_awrite(nbp); 940 } else { 941 bremfree(nbp); 942 bawrite(nbp); 943 } 944 dirtybufferflushes++; 945 break; 946 } 947 if (nbp == NULL) 948 BO_UNLOCK(bo); 949 } else 950 BO_UNLOCK(bo); 951 } else 952 recursiveflushes++; 953 954 bdirty(bp); 955 /* 956 * Set B_CACHE, indicating that the buffer is fully valid. This is 957 * true even of NFS now. 958 */ 959 bp->b_flags |= B_CACHE; 960 961 /* 962 * This bmap keeps the system from needing to do the bmap later, 963 * perhaps when the system is attempting to do a sync. Since it 964 * is likely that the indirect block -- or whatever other datastructure 965 * that the filesystem needs is still in memory now, it is a good 966 * thing to do this. Note also, that if the pageout daemon is 967 * requesting a sync -- there might not be enough memory to do 968 * the bmap then... So, this is important to do. 969 */ 970 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 971 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 972 } 973 974 /* 975 * Set the *dirty* buffer range based upon the VM system dirty pages. 976 */ 977 vfs_setdirty(bp); 978 979 /* 980 * We need to do this here to satisfy the vnode_pager and the 981 * pageout daemon, so that it thinks that the pages have been 982 * "cleaned". Note that since the pages are in a delayed write 983 * buffer -- the VFS layer "will" see that the pages get written 984 * out on the next sync, or perhaps the cluster will be completed. 985 */ 986 vfs_clean_pages(bp); 987 bqrelse(bp); 988 989 /* 990 * Wakeup the buffer flushing daemon if we have a lot of dirty 991 * buffers (midpoint between our recovery point and our stall 992 * point). 993 */ 994 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 995 996 /* 997 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 998 * due to the softdep code. 999 */ 1000 } 1001 1002 /* 1003 * bdirty: 1004 * 1005 * Turn buffer into delayed write request. We must clear BIO_READ and 1006 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1007 * itself to properly update it in the dirty/clean lists. We mark it 1008 * B_DONE to ensure that any asynchronization of the buffer properly 1009 * clears B_DONE ( else a panic will occur later ). 1010 * 1011 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1012 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1013 * should only be called if the buffer is known-good. 1014 * 1015 * Since the buffer is not on a queue, we do not update the numfreebuffers 1016 * count. 1017 * 1018 * The buffer must be on QUEUE_NONE. 1019 */ 1020 void 1021 bdirty(struct buf *bp) 1022 { 1023 1024 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1025 bp, bp->b_vp, bp->b_flags); 1026 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp)); 1027 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1028 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1029 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1030 bp->b_flags &= ~(B_RELBUF); 1031 bp->b_iocmd = BIO_WRITE; 1032 1033 if ((bp->b_flags & B_DELWRI) == 0) { 1034 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1035 reassignbuf(bp); 1036 atomic_add_int(&numdirtybuffers, 1); 1037 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1038 } 1039 } 1040 1041 /* 1042 * bundirty: 1043 * 1044 * Clear B_DELWRI for buffer. 1045 * 1046 * Since the buffer is not on a queue, we do not update the numfreebuffers 1047 * count. 1048 * 1049 * The buffer must be on QUEUE_NONE. 1050 */ 1051 1052 void 1053 bundirty(struct buf *bp) 1054 { 1055 1056 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1057 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1058 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1059 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1060 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp)); 1061 1062 if (bp->b_flags & B_DELWRI) { 1063 bp->b_flags &= ~B_DELWRI; 1064 reassignbuf(bp); 1065 atomic_subtract_int(&numdirtybuffers, 1); 1066 numdirtywakeup(lodirtybuffers); 1067 } 1068 /* 1069 * Since it is now being written, we can clear its deferred write flag. 1070 */ 1071 bp->b_flags &= ~B_DEFERRED; 1072 } 1073 1074 /* 1075 * bawrite: 1076 * 1077 * Asynchronous write. Start output on a buffer, but do not wait for 1078 * it to complete. The buffer is released when the output completes. 1079 * 1080 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1081 * B_INVAL buffers. Not us. 1082 */ 1083 void 1084 bawrite(struct buf *bp) 1085 { 1086 1087 bp->b_flags |= B_ASYNC; 1088 (void) bwrite(bp); 1089 } 1090 1091 /* 1092 * bwillwrite: 1093 * 1094 * Called prior to the locking of any vnodes when we are expecting to 1095 * write. We do not want to starve the buffer cache with too many 1096 * dirty buffers so we block here. By blocking prior to the locking 1097 * of any vnodes we attempt to avoid the situation where a locked vnode 1098 * prevents the various system daemons from flushing related buffers. 1099 */ 1100 1101 void 1102 bwillwrite(void) 1103 { 1104 1105 if (numdirtybuffers >= hidirtybuffers) { 1106 mtx_lock(&nblock); 1107 while (numdirtybuffers >= hidirtybuffers) { 1108 bd_wakeup(1); 1109 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1110 msleep(&needsbuffer, &nblock, 1111 (PRIBIO + 4), "flswai", 0); 1112 } 1113 mtx_unlock(&nblock); 1114 } 1115 } 1116 1117 /* 1118 * Return true if we have too many dirty buffers. 1119 */ 1120 int 1121 buf_dirty_count_severe(void) 1122 { 1123 1124 return(numdirtybuffers >= hidirtybuffers); 1125 } 1126 1127 /* 1128 * brelse: 1129 * 1130 * Release a busy buffer and, if requested, free its resources. The 1131 * buffer will be stashed in the appropriate bufqueue[] allowing it 1132 * to be accessed later as a cache entity or reused for other purposes. 1133 */ 1134 void 1135 brelse(struct buf *bp) 1136 { 1137 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1138 bp, bp->b_vp, bp->b_flags); 1139 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1140 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1141 1142 if (bp->b_flags & B_MANAGED) { 1143 bqrelse(bp); 1144 return; 1145 } 1146 1147 if (bp->b_iocmd == BIO_WRITE && 1148 (bp->b_ioflags & BIO_ERROR) && 1149 !(bp->b_flags & B_INVAL)) { 1150 /* 1151 * Failed write, redirty. Must clear BIO_ERROR to prevent 1152 * pages from being scrapped. If B_INVAL is set then 1153 * this case is not run and the next case is run to 1154 * destroy the buffer. B_INVAL can occur if the buffer 1155 * is outside the range supported by the underlying device. 1156 */ 1157 bp->b_ioflags &= ~BIO_ERROR; 1158 bdirty(bp); 1159 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1160 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1161 /* 1162 * Either a failed I/O or we were asked to free or not 1163 * cache the buffer. 1164 */ 1165 bp->b_flags |= B_INVAL; 1166 if (LIST_FIRST(&bp->b_dep) != NULL) 1167 buf_deallocate(bp); 1168 if (bp->b_flags & B_DELWRI) { 1169 atomic_subtract_int(&numdirtybuffers, 1); 1170 numdirtywakeup(lodirtybuffers); 1171 } 1172 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1173 if ((bp->b_flags & B_VMIO) == 0) { 1174 if (bp->b_bufsize) 1175 allocbuf(bp, 0); 1176 if (bp->b_vp) 1177 brelvp(bp); 1178 } 1179 } 1180 1181 /* 1182 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1183 * is called with B_DELWRI set, the underlying pages may wind up 1184 * getting freed causing a previous write (bdwrite()) to get 'lost' 1185 * because pages associated with a B_DELWRI bp are marked clean. 1186 * 1187 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1188 * if B_DELWRI is set. 1189 * 1190 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1191 * on pages to return pages to the VM page queues. 1192 */ 1193 if (bp->b_flags & B_DELWRI) 1194 bp->b_flags &= ~B_RELBUF; 1195 else if (vm_page_count_severe()) { 1196 /* 1197 * XXX This lock may not be necessary since BKGRDINPROG 1198 * cannot be set while we hold the buf lock, it can only be 1199 * cleared if it is already pending. 1200 */ 1201 if (bp->b_vp) { 1202 BO_LOCK(bp->b_bufobj); 1203 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1204 bp->b_flags |= B_RELBUF; 1205 BO_UNLOCK(bp->b_bufobj); 1206 } else 1207 bp->b_flags |= B_RELBUF; 1208 } 1209 1210 /* 1211 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1212 * constituted, not even NFS buffers now. Two flags effect this. If 1213 * B_INVAL, the struct buf is invalidated but the VM object is kept 1214 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1215 * 1216 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1217 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1218 * buffer is also B_INVAL because it hits the re-dirtying code above. 1219 * 1220 * Normally we can do this whether a buffer is B_DELWRI or not. If 1221 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1222 * the commit state and we cannot afford to lose the buffer. If the 1223 * buffer has a background write in progress, we need to keep it 1224 * around to prevent it from being reconstituted and starting a second 1225 * background write. 1226 */ 1227 if ((bp->b_flags & B_VMIO) 1228 && !(bp->b_vp->v_mount != NULL && 1229 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1230 !vn_isdisk(bp->b_vp, NULL) && 1231 (bp->b_flags & B_DELWRI)) 1232 ) { 1233 1234 int i, j, resid; 1235 vm_page_t m; 1236 off_t foff; 1237 vm_pindex_t poff; 1238 vm_object_t obj; 1239 1240 obj = bp->b_bufobj->bo_object; 1241 1242 /* 1243 * Get the base offset and length of the buffer. Note that 1244 * in the VMIO case if the buffer block size is not 1245 * page-aligned then b_data pointer may not be page-aligned. 1246 * But our b_pages[] array *IS* page aligned. 1247 * 1248 * block sizes less then DEV_BSIZE (usually 512) are not 1249 * supported due to the page granularity bits (m->valid, 1250 * m->dirty, etc...). 1251 * 1252 * See man buf(9) for more information 1253 */ 1254 resid = bp->b_bufsize; 1255 foff = bp->b_offset; 1256 VM_OBJECT_LOCK(obj); 1257 for (i = 0; i < bp->b_npages; i++) { 1258 int had_bogus = 0; 1259 1260 m = bp->b_pages[i]; 1261 1262 /* 1263 * If we hit a bogus page, fixup *all* the bogus pages 1264 * now. 1265 */ 1266 if (m == bogus_page) { 1267 poff = OFF_TO_IDX(bp->b_offset); 1268 had_bogus = 1; 1269 1270 for (j = i; j < bp->b_npages; j++) { 1271 vm_page_t mtmp; 1272 mtmp = bp->b_pages[j]; 1273 if (mtmp == bogus_page) { 1274 mtmp = vm_page_lookup(obj, poff + j); 1275 if (!mtmp) { 1276 panic("brelse: page missing\n"); 1277 } 1278 bp->b_pages[j] = mtmp; 1279 } 1280 } 1281 1282 if ((bp->b_flags & B_INVAL) == 0) { 1283 pmap_qenter( 1284 trunc_page((vm_offset_t)bp->b_data), 1285 bp->b_pages, bp->b_npages); 1286 } 1287 m = bp->b_pages[i]; 1288 } 1289 if ((bp->b_flags & B_NOCACHE) || 1290 (bp->b_ioflags & BIO_ERROR)) { 1291 int poffset = foff & PAGE_MASK; 1292 int presid = resid > (PAGE_SIZE - poffset) ? 1293 (PAGE_SIZE - poffset) : resid; 1294 1295 KASSERT(presid >= 0, ("brelse: extra page")); 1296 vm_page_lock_queues(); 1297 vm_page_set_invalid(m, poffset, presid); 1298 vm_page_unlock_queues(); 1299 if (had_bogus) 1300 printf("avoided corruption bug in bogus_page/brelse code\n"); 1301 } 1302 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1303 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1304 } 1305 VM_OBJECT_UNLOCK(obj); 1306 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1307 vfs_vmio_release(bp); 1308 1309 } else if (bp->b_flags & B_VMIO) { 1310 1311 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1312 vfs_vmio_release(bp); 1313 } 1314 1315 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1316 if (bp->b_bufsize != 0) 1317 allocbuf(bp, 0); 1318 if (bp->b_vp != NULL) 1319 brelvp(bp); 1320 } 1321 1322 if (BUF_REFCNT(bp) > 1) { 1323 /* do not release to free list */ 1324 BUF_UNLOCK(bp); 1325 return; 1326 } 1327 1328 /* enqueue */ 1329 mtx_lock(&bqlock); 1330 /* Handle delayed bremfree() processing. */ 1331 if (bp->b_flags & B_REMFREE) 1332 bremfreel(bp); 1333 if (bp->b_qindex != QUEUE_NONE) 1334 panic("brelse: free buffer onto another queue???"); 1335 1336 /* buffers with no memory */ 1337 if (bp->b_bufsize == 0) { 1338 bp->b_flags |= B_INVAL; 1339 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1340 if (bp->b_vflags & BV_BKGRDINPROG) 1341 panic("losing buffer 1"); 1342 if (bp->b_kvasize) { 1343 bp->b_qindex = QUEUE_EMPTYKVA; 1344 } else { 1345 bp->b_qindex = QUEUE_EMPTY; 1346 } 1347 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1348 /* buffers with junk contents */ 1349 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1350 (bp->b_ioflags & BIO_ERROR)) { 1351 bp->b_flags |= B_INVAL; 1352 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1353 if (bp->b_vflags & BV_BKGRDINPROG) 1354 panic("losing buffer 2"); 1355 bp->b_qindex = QUEUE_CLEAN; 1356 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1357 /* remaining buffers */ 1358 } else { 1359 if (bp->b_flags & B_DELWRI) 1360 bp->b_qindex = QUEUE_DIRTY; 1361 else 1362 bp->b_qindex = QUEUE_CLEAN; 1363 if (bp->b_flags & B_AGE) 1364 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1365 else 1366 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1367 } 1368 mtx_unlock(&bqlock); 1369 1370 /* 1371 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1372 * placed the buffer on the correct queue. We must also disassociate 1373 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1374 * find it. 1375 */ 1376 if (bp->b_flags & B_INVAL) { 1377 if (bp->b_flags & B_DELWRI) 1378 bundirty(bp); 1379 if (bp->b_vp) 1380 brelvp(bp); 1381 } 1382 1383 /* 1384 * Fixup numfreebuffers count. The bp is on an appropriate queue 1385 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1386 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1387 * if B_INVAL is set ). 1388 */ 1389 1390 if (!(bp->b_flags & B_DELWRI)) 1391 bufcountwakeup(); 1392 1393 /* 1394 * Something we can maybe free or reuse 1395 */ 1396 if (bp->b_bufsize || bp->b_kvasize) 1397 bufspacewakeup(); 1398 1399 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1400 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1401 panic("brelse: not dirty"); 1402 /* unlock */ 1403 BUF_UNLOCK(bp); 1404 } 1405 1406 /* 1407 * Release a buffer back to the appropriate queue but do not try to free 1408 * it. The buffer is expected to be used again soon. 1409 * 1410 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1411 * biodone() to requeue an async I/O on completion. It is also used when 1412 * known good buffers need to be requeued but we think we may need the data 1413 * again soon. 1414 * 1415 * XXX we should be able to leave the B_RELBUF hint set on completion. 1416 */ 1417 void 1418 bqrelse(struct buf *bp) 1419 { 1420 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1421 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1422 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1423 1424 if (BUF_REFCNT(bp) > 1) { 1425 /* do not release to free list */ 1426 BUF_UNLOCK(bp); 1427 return; 1428 } 1429 1430 if (bp->b_flags & B_MANAGED) { 1431 if (bp->b_flags & B_REMFREE) { 1432 mtx_lock(&bqlock); 1433 bremfreel(bp); 1434 mtx_unlock(&bqlock); 1435 } 1436 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1437 BUF_UNLOCK(bp); 1438 return; 1439 } 1440 1441 mtx_lock(&bqlock); 1442 /* Handle delayed bremfree() processing. */ 1443 if (bp->b_flags & B_REMFREE) 1444 bremfreel(bp); 1445 if (bp->b_qindex != QUEUE_NONE) 1446 panic("bqrelse: free buffer onto another queue???"); 1447 /* buffers with stale but valid contents */ 1448 if (bp->b_flags & B_DELWRI) { 1449 bp->b_qindex = QUEUE_DIRTY; 1450 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 1451 } else { 1452 /* 1453 * XXX This lock may not be necessary since BKGRDINPROG 1454 * cannot be set while we hold the buf lock, it can only be 1455 * cleared if it is already pending. 1456 */ 1457 BO_LOCK(bp->b_bufobj); 1458 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1459 BO_UNLOCK(bp->b_bufobj); 1460 bp->b_qindex = QUEUE_CLEAN; 1461 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1462 b_freelist); 1463 } else { 1464 /* 1465 * We are too low on memory, we have to try to free 1466 * the buffer (most importantly: the wired pages 1467 * making up its backing store) *now*. 1468 */ 1469 BO_UNLOCK(bp->b_bufobj); 1470 mtx_unlock(&bqlock); 1471 brelse(bp); 1472 return; 1473 } 1474 } 1475 mtx_unlock(&bqlock); 1476 1477 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1478 bufcountwakeup(); 1479 1480 /* 1481 * Something we can maybe free or reuse. 1482 */ 1483 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1484 bufspacewakeup(); 1485 1486 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1487 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1488 panic("bqrelse: not dirty"); 1489 /* unlock */ 1490 BUF_UNLOCK(bp); 1491 } 1492 1493 /* Give pages used by the bp back to the VM system (where possible) */ 1494 static void 1495 vfs_vmio_release(struct buf *bp) 1496 { 1497 int i; 1498 vm_page_t m; 1499 1500 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1501 vm_page_lock_queues(); 1502 for (i = 0; i < bp->b_npages; i++) { 1503 m = bp->b_pages[i]; 1504 bp->b_pages[i] = NULL; 1505 /* 1506 * In order to keep page LRU ordering consistent, put 1507 * everything on the inactive queue. 1508 */ 1509 vm_page_unwire(m, 0); 1510 /* 1511 * We don't mess with busy pages, it is 1512 * the responsibility of the process that 1513 * busied the pages to deal with them. 1514 */ 1515 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1516 continue; 1517 1518 if (m->wire_count == 0) { 1519 /* 1520 * Might as well free the page if we can and it has 1521 * no valid data. We also free the page if the 1522 * buffer was used for direct I/O 1523 */ 1524 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1525 m->hold_count == 0) { 1526 vm_page_free(m); 1527 } else if (bp->b_flags & B_DIRECT) { 1528 vm_page_try_to_free(m); 1529 } else if (vm_page_count_severe()) { 1530 vm_page_try_to_cache(m); 1531 } 1532 } 1533 } 1534 vm_page_unlock_queues(); 1535 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1536 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1537 1538 if (bp->b_bufsize) { 1539 bufspacewakeup(); 1540 bp->b_bufsize = 0; 1541 } 1542 bp->b_npages = 0; 1543 bp->b_flags &= ~B_VMIO; 1544 if (bp->b_vp) 1545 brelvp(bp); 1546 } 1547 1548 /* 1549 * Check to see if a block at a particular lbn is available for a clustered 1550 * write. 1551 */ 1552 static int 1553 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1554 { 1555 struct buf *bpa; 1556 int match; 1557 1558 match = 0; 1559 1560 /* If the buf isn't in core skip it */ 1561 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1562 return (0); 1563 1564 /* If the buf is busy we don't want to wait for it */ 1565 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1566 return (0); 1567 1568 /* Only cluster with valid clusterable delayed write buffers */ 1569 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1570 (B_DELWRI | B_CLUSTEROK)) 1571 goto done; 1572 1573 if (bpa->b_bufsize != size) 1574 goto done; 1575 1576 /* 1577 * Check to see if it is in the expected place on disk and that the 1578 * block has been mapped. 1579 */ 1580 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1581 match = 1; 1582 done: 1583 BUF_UNLOCK(bpa); 1584 return (match); 1585 } 1586 1587 /* 1588 * vfs_bio_awrite: 1589 * 1590 * Implement clustered async writes for clearing out B_DELWRI buffers. 1591 * This is much better then the old way of writing only one buffer at 1592 * a time. Note that we may not be presented with the buffers in the 1593 * correct order, so we search for the cluster in both directions. 1594 */ 1595 int 1596 vfs_bio_awrite(struct buf *bp) 1597 { 1598 int i; 1599 int j; 1600 daddr_t lblkno = bp->b_lblkno; 1601 struct vnode *vp = bp->b_vp; 1602 int ncl; 1603 int nwritten; 1604 int size; 1605 int maxcl; 1606 1607 /* 1608 * right now we support clustered writing only to regular files. If 1609 * we find a clusterable block we could be in the middle of a cluster 1610 * rather then at the beginning. 1611 */ 1612 if ((vp->v_type == VREG) && 1613 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1614 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1615 1616 size = vp->v_mount->mnt_stat.f_iosize; 1617 maxcl = MAXPHYS / size; 1618 1619 VI_LOCK(vp); 1620 for (i = 1; i < maxcl; i++) 1621 if (vfs_bio_clcheck(vp, size, lblkno + i, 1622 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1623 break; 1624 1625 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1626 if (vfs_bio_clcheck(vp, size, lblkno - j, 1627 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1628 break; 1629 1630 VI_UNLOCK(vp); 1631 --j; 1632 ncl = i + j; 1633 /* 1634 * this is a possible cluster write 1635 */ 1636 if (ncl != 1) { 1637 BUF_UNLOCK(bp); 1638 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1639 return nwritten; 1640 } 1641 } 1642 bremfree(bp); 1643 bp->b_flags |= B_ASYNC; 1644 /* 1645 * default (old) behavior, writing out only one block 1646 * 1647 * XXX returns b_bufsize instead of b_bcount for nwritten? 1648 */ 1649 nwritten = bp->b_bufsize; 1650 (void) bwrite(bp); 1651 1652 return nwritten; 1653 } 1654 1655 /* 1656 * getnewbuf: 1657 * 1658 * Find and initialize a new buffer header, freeing up existing buffers 1659 * in the bufqueues as necessary. The new buffer is returned locked. 1660 * 1661 * Important: B_INVAL is not set. If the caller wishes to throw the 1662 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1663 * 1664 * We block if: 1665 * We have insufficient buffer headers 1666 * We have insufficient buffer space 1667 * buffer_map is too fragmented ( space reservation fails ) 1668 * If we have to flush dirty buffers ( but we try to avoid this ) 1669 * 1670 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1671 * Instead we ask the buf daemon to do it for us. We attempt to 1672 * avoid piecemeal wakeups of the pageout daemon. 1673 */ 1674 1675 static struct buf * 1676 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1677 { 1678 struct buf *bp; 1679 struct buf *nbp; 1680 int defrag = 0; 1681 int nqindex; 1682 static int flushingbufs; 1683 1684 /* 1685 * We can't afford to block since we might be holding a vnode lock, 1686 * which may prevent system daemons from running. We deal with 1687 * low-memory situations by proactively returning memory and running 1688 * async I/O rather then sync I/O. 1689 */ 1690 1691 atomic_add_int(&getnewbufcalls, 1); 1692 atomic_subtract_int(&getnewbufrestarts, 1); 1693 restart: 1694 atomic_add_int(&getnewbufrestarts, 1); 1695 1696 /* 1697 * Setup for scan. If we do not have enough free buffers, 1698 * we setup a degenerate case that immediately fails. Note 1699 * that if we are specially marked process, we are allowed to 1700 * dip into our reserves. 1701 * 1702 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1703 * 1704 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1705 * However, there are a number of cases (defragging, reusing, ...) 1706 * where we cannot backup. 1707 */ 1708 mtx_lock(&bqlock); 1709 nqindex = QUEUE_EMPTYKVA; 1710 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1711 1712 if (nbp == NULL) { 1713 /* 1714 * If no EMPTYKVA buffers and we are either 1715 * defragging or reusing, locate a CLEAN buffer 1716 * to free or reuse. If bufspace useage is low 1717 * skip this step so we can allocate a new buffer. 1718 */ 1719 if (defrag || bufspace >= lobufspace) { 1720 nqindex = QUEUE_CLEAN; 1721 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1722 } 1723 1724 /* 1725 * If we could not find or were not allowed to reuse a 1726 * CLEAN buffer, check to see if it is ok to use an EMPTY 1727 * buffer. We can only use an EMPTY buffer if allocating 1728 * its KVA would not otherwise run us out of buffer space. 1729 */ 1730 if (nbp == NULL && defrag == 0 && 1731 bufspace + maxsize < hibufspace) { 1732 nqindex = QUEUE_EMPTY; 1733 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1734 } 1735 } 1736 1737 /* 1738 * Run scan, possibly freeing data and/or kva mappings on the fly 1739 * depending. 1740 */ 1741 1742 while ((bp = nbp) != NULL) { 1743 int qindex = nqindex; 1744 1745 /* 1746 * Calculate next bp ( we can only use it if we do not block 1747 * or do other fancy things ). 1748 */ 1749 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1750 switch(qindex) { 1751 case QUEUE_EMPTY: 1752 nqindex = QUEUE_EMPTYKVA; 1753 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1754 break; 1755 /* FALLTHROUGH */ 1756 case QUEUE_EMPTYKVA: 1757 nqindex = QUEUE_CLEAN; 1758 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1759 break; 1760 /* FALLTHROUGH */ 1761 case QUEUE_CLEAN: 1762 /* 1763 * nbp is NULL. 1764 */ 1765 break; 1766 } 1767 } 1768 /* 1769 * If we are defragging then we need a buffer with 1770 * b_kvasize != 0. XXX this situation should no longer 1771 * occur, if defrag is non-zero the buffer's b_kvasize 1772 * should also be non-zero at this point. XXX 1773 */ 1774 if (defrag && bp->b_kvasize == 0) { 1775 printf("Warning: defrag empty buffer %p\n", bp); 1776 continue; 1777 } 1778 1779 /* 1780 * Start freeing the bp. This is somewhat involved. nbp 1781 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1782 */ 1783 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1784 continue; 1785 if (bp->b_vp) { 1786 BO_LOCK(bp->b_bufobj); 1787 if (bp->b_vflags & BV_BKGRDINPROG) { 1788 BO_UNLOCK(bp->b_bufobj); 1789 BUF_UNLOCK(bp); 1790 continue; 1791 } 1792 BO_UNLOCK(bp->b_bufobj); 1793 } 1794 CTR6(KTR_BUF, 1795 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1796 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1797 bp->b_kvasize, bp->b_bufsize, qindex); 1798 1799 /* 1800 * Sanity Checks 1801 */ 1802 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1803 1804 /* 1805 * Note: we no longer distinguish between VMIO and non-VMIO 1806 * buffers. 1807 */ 1808 1809 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1810 1811 bremfreel(bp); 1812 mtx_unlock(&bqlock); 1813 1814 if (qindex == QUEUE_CLEAN) { 1815 if (bp->b_flags & B_VMIO) { 1816 bp->b_flags &= ~B_ASYNC; 1817 vfs_vmio_release(bp); 1818 } 1819 if (bp->b_vp) 1820 brelvp(bp); 1821 } 1822 1823 /* 1824 * NOTE: nbp is now entirely invalid. We can only restart 1825 * the scan from this point on. 1826 * 1827 * Get the rest of the buffer freed up. b_kva* is still 1828 * valid after this operation. 1829 */ 1830 1831 if (bp->b_rcred != NOCRED) { 1832 crfree(bp->b_rcred); 1833 bp->b_rcred = NOCRED; 1834 } 1835 if (bp->b_wcred != NOCRED) { 1836 crfree(bp->b_wcred); 1837 bp->b_wcred = NOCRED; 1838 } 1839 if (LIST_FIRST(&bp->b_dep) != NULL) 1840 buf_deallocate(bp); 1841 if (bp->b_vflags & BV_BKGRDINPROG) 1842 panic("losing buffer 3"); 1843 KASSERT(bp->b_vp == NULL, 1844 ("bp: %p still has vnode %p. qindex: %d", 1845 bp, bp->b_vp, qindex)); 1846 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1847 ("bp: %p still on a buffer list. xflags %X", 1848 bp, bp->b_xflags)); 1849 1850 if (bp->b_bufsize) 1851 allocbuf(bp, 0); 1852 1853 bp->b_flags = 0; 1854 bp->b_ioflags = 0; 1855 bp->b_xflags = 0; 1856 bp->b_vflags = 0; 1857 bp->b_vp = NULL; 1858 bp->b_blkno = bp->b_lblkno = 0; 1859 bp->b_offset = NOOFFSET; 1860 bp->b_iodone = 0; 1861 bp->b_error = 0; 1862 bp->b_resid = 0; 1863 bp->b_bcount = 0; 1864 bp->b_npages = 0; 1865 bp->b_dirtyoff = bp->b_dirtyend = 0; 1866 bp->b_bufobj = NULL; 1867 bp->b_pin_count = 0; 1868 bp->b_fsprivate1 = NULL; 1869 bp->b_fsprivate2 = NULL; 1870 bp->b_fsprivate3 = NULL; 1871 1872 LIST_INIT(&bp->b_dep); 1873 1874 /* 1875 * If we are defragging then free the buffer. 1876 */ 1877 if (defrag) { 1878 bp->b_flags |= B_INVAL; 1879 bfreekva(bp); 1880 brelse(bp); 1881 defrag = 0; 1882 goto restart; 1883 } 1884 1885 /* 1886 * If we are overcomitted then recover the buffer and its 1887 * KVM space. This occurs in rare situations when multiple 1888 * processes are blocked in getnewbuf() or allocbuf(). 1889 */ 1890 if (bufspace >= hibufspace) 1891 flushingbufs = 1; 1892 if (flushingbufs && bp->b_kvasize != 0) { 1893 bp->b_flags |= B_INVAL; 1894 bfreekva(bp); 1895 brelse(bp); 1896 goto restart; 1897 } 1898 if (bufspace < lobufspace) 1899 flushingbufs = 0; 1900 break; 1901 } 1902 1903 /* 1904 * If we exhausted our list, sleep as appropriate. We may have to 1905 * wakeup various daemons and write out some dirty buffers. 1906 * 1907 * Generally we are sleeping due to insufficient buffer space. 1908 */ 1909 1910 if (bp == NULL) { 1911 int flags; 1912 char *waitmsg; 1913 1914 if (defrag) { 1915 flags = VFS_BIO_NEED_BUFSPACE; 1916 waitmsg = "nbufkv"; 1917 } else if (bufspace >= hibufspace) { 1918 waitmsg = "nbufbs"; 1919 flags = VFS_BIO_NEED_BUFSPACE; 1920 } else { 1921 waitmsg = "newbuf"; 1922 flags = VFS_BIO_NEED_ANY; 1923 } 1924 mtx_lock(&nblock); 1925 needsbuffer |= flags; 1926 mtx_unlock(&nblock); 1927 mtx_unlock(&bqlock); 1928 1929 bd_speedup(); /* heeeelp */ 1930 1931 mtx_lock(&nblock); 1932 while (needsbuffer & flags) { 1933 if (msleep(&needsbuffer, &nblock, 1934 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1935 mtx_unlock(&nblock); 1936 return (NULL); 1937 } 1938 } 1939 mtx_unlock(&nblock); 1940 } else { 1941 /* 1942 * We finally have a valid bp. We aren't quite out of the 1943 * woods, we still have to reserve kva space. In order 1944 * to keep fragmentation sane we only allocate kva in 1945 * BKVASIZE chunks. 1946 */ 1947 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1948 1949 if (maxsize != bp->b_kvasize) { 1950 vm_offset_t addr = 0; 1951 1952 bfreekva(bp); 1953 1954 vm_map_lock(buffer_map); 1955 if (vm_map_findspace(buffer_map, 1956 vm_map_min(buffer_map), maxsize, &addr)) { 1957 /* 1958 * Uh oh. Buffer map is to fragmented. We 1959 * must defragment the map. 1960 */ 1961 atomic_add_int(&bufdefragcnt, 1); 1962 vm_map_unlock(buffer_map); 1963 defrag = 1; 1964 bp->b_flags |= B_INVAL; 1965 brelse(bp); 1966 goto restart; 1967 } 1968 if (addr) { 1969 vm_map_insert(buffer_map, NULL, 0, 1970 addr, addr + maxsize, 1971 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1972 1973 bp->b_kvabase = (caddr_t) addr; 1974 bp->b_kvasize = maxsize; 1975 atomic_add_int(&bufspace, bp->b_kvasize); 1976 atomic_add_int(&bufreusecnt, 1); 1977 } 1978 vm_map_unlock(buffer_map); 1979 } 1980 bp->b_saveaddr = bp->b_kvabase; 1981 bp->b_data = bp->b_saveaddr; 1982 } 1983 return(bp); 1984 } 1985 1986 /* 1987 * buf_daemon: 1988 * 1989 * buffer flushing daemon. Buffers are normally flushed by the 1990 * update daemon but if it cannot keep up this process starts to 1991 * take the load in an attempt to prevent getnewbuf() from blocking. 1992 */ 1993 1994 static struct kproc_desc buf_kp = { 1995 "bufdaemon", 1996 buf_daemon, 1997 &bufdaemonproc 1998 }; 1999 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2000 2001 static void 2002 buf_daemon() 2003 { 2004 mtx_lock(&Giant); 2005 2006 /* 2007 * This process needs to be suspended prior to shutdown sync. 2008 */ 2009 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2010 SHUTDOWN_PRI_LAST); 2011 2012 /* 2013 * This process is allowed to take the buffer cache to the limit 2014 */ 2015 curthread->td_pflags |= TDP_NORUNNINGBUF; 2016 mtx_lock(&bdlock); 2017 for (;;) { 2018 bd_request = 0; 2019 mtx_unlock(&bdlock); 2020 2021 kthread_suspend_check(bufdaemonproc); 2022 2023 /* 2024 * Do the flush. Limit the amount of in-transit I/O we 2025 * allow to build up, otherwise we would completely saturate 2026 * the I/O system. Wakeup any waiting processes before we 2027 * normally would so they can run in parallel with our drain. 2028 */ 2029 while (numdirtybuffers > lodirtybuffers) { 2030 if (flushbufqueues(0) == 0) { 2031 /* 2032 * Could not find any buffers without rollback 2033 * dependencies, so just write the first one 2034 * in the hopes of eventually making progress. 2035 */ 2036 flushbufqueues(1); 2037 break; 2038 } 2039 uio_yield(); 2040 } 2041 2042 /* 2043 * Only clear bd_request if we have reached our low water 2044 * mark. The buf_daemon normally waits 1 second and 2045 * then incrementally flushes any dirty buffers that have 2046 * built up, within reason. 2047 * 2048 * If we were unable to hit our low water mark and couldn't 2049 * find any flushable buffers, we sleep half a second. 2050 * Otherwise we loop immediately. 2051 */ 2052 mtx_lock(&bdlock); 2053 if (numdirtybuffers <= lodirtybuffers) { 2054 /* 2055 * We reached our low water mark, reset the 2056 * request and sleep until we are needed again. 2057 * The sleep is just so the suspend code works. 2058 */ 2059 bd_request = 0; 2060 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2061 } else { 2062 /* 2063 * We couldn't find any flushable dirty buffers but 2064 * still have too many dirty buffers, we 2065 * have to sleep and try again. (rare) 2066 */ 2067 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2068 } 2069 } 2070 } 2071 2072 /* 2073 * flushbufqueues: 2074 * 2075 * Try to flush a buffer in the dirty queue. We must be careful to 2076 * free up B_INVAL buffers instead of write them, which NFS is 2077 * particularly sensitive to. 2078 */ 2079 static int flushwithdeps = 0; 2080 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2081 0, "Number of buffers flushed with dependecies that require rollbacks"); 2082 2083 static int 2084 flushbufqueues(int flushdeps) 2085 { 2086 struct thread *td = curthread; 2087 struct buf sentinel; 2088 struct vnode *vp; 2089 struct mount *mp; 2090 struct buf *bp; 2091 int hasdeps; 2092 int flushed; 2093 int target; 2094 2095 target = numdirtybuffers - lodirtybuffers; 2096 if (flushdeps && target > 2) 2097 target /= 2; 2098 flushed = 0; 2099 bp = NULL; 2100 mtx_lock(&bqlock); 2101 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist); 2102 while (flushed != target) { 2103 bp = TAILQ_FIRST(&bufqueues[QUEUE_DIRTY]); 2104 if (bp == &sentinel) 2105 break; 2106 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 2107 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_DIRTY], bp, b_freelist); 2108 2109 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2110 continue; 2111 if (bp->b_pin_count > 0) { 2112 BUF_UNLOCK(bp); 2113 continue; 2114 } 2115 BO_LOCK(bp->b_bufobj); 2116 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2117 (bp->b_flags & B_DELWRI) == 0) { 2118 BO_UNLOCK(bp->b_bufobj); 2119 BUF_UNLOCK(bp); 2120 continue; 2121 } 2122 BO_UNLOCK(bp->b_bufobj); 2123 if (bp->b_flags & B_INVAL) { 2124 bremfreel(bp); 2125 mtx_unlock(&bqlock); 2126 brelse(bp); 2127 flushed++; 2128 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2129 mtx_lock(&bqlock); 2130 continue; 2131 } 2132 2133 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2134 if (flushdeps == 0) { 2135 BUF_UNLOCK(bp); 2136 continue; 2137 } 2138 hasdeps = 1; 2139 } else 2140 hasdeps = 0; 2141 /* 2142 * We must hold the lock on a vnode before writing 2143 * one of its buffers. Otherwise we may confuse, or 2144 * in the case of a snapshot vnode, deadlock the 2145 * system. 2146 * 2147 * The lock order here is the reverse of the normal 2148 * of vnode followed by buf lock. This is ok because 2149 * the NOWAIT will prevent deadlock. 2150 */ 2151 vp = bp->b_vp; 2152 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2153 BUF_UNLOCK(bp); 2154 continue; 2155 } 2156 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2157 mtx_unlock(&bqlock); 2158 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2159 bp, bp->b_vp, bp->b_flags); 2160 vfs_bio_awrite(bp); 2161 vn_finished_write(mp); 2162 VOP_UNLOCK(vp, 0, td); 2163 flushwithdeps += hasdeps; 2164 flushed++; 2165 waitrunningbufspace(); 2166 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2167 mtx_lock(&bqlock); 2168 continue; 2169 } 2170 vn_finished_write(mp); 2171 BUF_UNLOCK(bp); 2172 } 2173 TAILQ_REMOVE(&bufqueues[QUEUE_DIRTY], &sentinel, b_freelist); 2174 mtx_unlock(&bqlock); 2175 return (flushed); 2176 } 2177 2178 /* 2179 * Check to see if a block is currently memory resident. 2180 */ 2181 struct buf * 2182 incore(struct bufobj *bo, daddr_t blkno) 2183 { 2184 struct buf *bp; 2185 2186 BO_LOCK(bo); 2187 bp = gbincore(bo, blkno); 2188 BO_UNLOCK(bo); 2189 return (bp); 2190 } 2191 2192 /* 2193 * Returns true if no I/O is needed to access the 2194 * associated VM object. This is like incore except 2195 * it also hunts around in the VM system for the data. 2196 */ 2197 2198 static int 2199 inmem(struct vnode * vp, daddr_t blkno) 2200 { 2201 vm_object_t obj; 2202 vm_offset_t toff, tinc, size; 2203 vm_page_t m; 2204 vm_ooffset_t off; 2205 2206 ASSERT_VOP_LOCKED(vp, "inmem"); 2207 2208 if (incore(&vp->v_bufobj, blkno)) 2209 return 1; 2210 if (vp->v_mount == NULL) 2211 return 0; 2212 obj = vp->v_object; 2213 if (obj == NULL) 2214 return (0); 2215 2216 size = PAGE_SIZE; 2217 if (size > vp->v_mount->mnt_stat.f_iosize) 2218 size = vp->v_mount->mnt_stat.f_iosize; 2219 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2220 2221 VM_OBJECT_LOCK(obj); 2222 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2223 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2224 if (!m) 2225 goto notinmem; 2226 tinc = size; 2227 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2228 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2229 if (vm_page_is_valid(m, 2230 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2231 goto notinmem; 2232 } 2233 VM_OBJECT_UNLOCK(obj); 2234 return 1; 2235 2236 notinmem: 2237 VM_OBJECT_UNLOCK(obj); 2238 return (0); 2239 } 2240 2241 /* 2242 * vfs_setdirty: 2243 * 2244 * Sets the dirty range for a buffer based on the status of the dirty 2245 * bits in the pages comprising the buffer. 2246 * 2247 * The range is limited to the size of the buffer. 2248 * 2249 * This routine is primarily used by NFS, but is generalized for the 2250 * B_VMIO case. 2251 */ 2252 static void 2253 vfs_setdirty(struct buf *bp) 2254 { 2255 int i; 2256 vm_object_t object; 2257 2258 /* 2259 * Degenerate case - empty buffer 2260 */ 2261 2262 if (bp->b_bufsize == 0) 2263 return; 2264 2265 /* 2266 * We qualify the scan for modified pages on whether the 2267 * object has been flushed yet. The OBJ_WRITEABLE flag 2268 * is not cleared simply by protecting pages off. 2269 */ 2270 2271 if ((bp->b_flags & B_VMIO) == 0) 2272 return; 2273 2274 object = bp->b_pages[0]->object; 2275 VM_OBJECT_LOCK(object); 2276 if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) 2277 printf("Warning: object %p writeable but not mightbedirty\n", object); 2278 if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) 2279 printf("Warning: object %p mightbedirty but not writeable\n", object); 2280 2281 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2282 vm_offset_t boffset; 2283 vm_offset_t eoffset; 2284 2285 vm_page_lock_queues(); 2286 /* 2287 * test the pages to see if they have been modified directly 2288 * by users through the VM system. 2289 */ 2290 for (i = 0; i < bp->b_npages; i++) 2291 vm_page_test_dirty(bp->b_pages[i]); 2292 2293 /* 2294 * Calculate the encompassing dirty range, boffset and eoffset, 2295 * (eoffset - boffset) bytes. 2296 */ 2297 2298 for (i = 0; i < bp->b_npages; i++) { 2299 if (bp->b_pages[i]->dirty) 2300 break; 2301 } 2302 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2303 2304 for (i = bp->b_npages - 1; i >= 0; --i) { 2305 if (bp->b_pages[i]->dirty) { 2306 break; 2307 } 2308 } 2309 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2310 2311 vm_page_unlock_queues(); 2312 /* 2313 * Fit it to the buffer. 2314 */ 2315 2316 if (eoffset > bp->b_bcount) 2317 eoffset = bp->b_bcount; 2318 2319 /* 2320 * If we have a good dirty range, merge with the existing 2321 * dirty range. 2322 */ 2323 2324 if (boffset < eoffset) { 2325 if (bp->b_dirtyoff > boffset) 2326 bp->b_dirtyoff = boffset; 2327 if (bp->b_dirtyend < eoffset) 2328 bp->b_dirtyend = eoffset; 2329 } 2330 } 2331 VM_OBJECT_UNLOCK(object); 2332 } 2333 2334 /* 2335 * getblk: 2336 * 2337 * Get a block given a specified block and offset into a file/device. 2338 * The buffers B_DONE bit will be cleared on return, making it almost 2339 * ready for an I/O initiation. B_INVAL may or may not be set on 2340 * return. The caller should clear B_INVAL prior to initiating a 2341 * READ. 2342 * 2343 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2344 * an existing buffer. 2345 * 2346 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2347 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2348 * and then cleared based on the backing VM. If the previous buffer is 2349 * non-0-sized but invalid, B_CACHE will be cleared. 2350 * 2351 * If getblk() must create a new buffer, the new buffer is returned with 2352 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2353 * case it is returned with B_INVAL clear and B_CACHE set based on the 2354 * backing VM. 2355 * 2356 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2357 * B_CACHE bit is clear. 2358 * 2359 * What this means, basically, is that the caller should use B_CACHE to 2360 * determine whether the buffer is fully valid or not and should clear 2361 * B_INVAL prior to issuing a read. If the caller intends to validate 2362 * the buffer by loading its data area with something, the caller needs 2363 * to clear B_INVAL. If the caller does this without issuing an I/O, 2364 * the caller should set B_CACHE ( as an optimization ), else the caller 2365 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2366 * a write attempt or if it was a successfull read. If the caller 2367 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2368 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2369 */ 2370 struct buf * 2371 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2372 int flags) 2373 { 2374 struct buf *bp; 2375 struct bufobj *bo; 2376 int error; 2377 2378 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2379 ASSERT_VOP_LOCKED(vp, "getblk"); 2380 if (size > MAXBSIZE) 2381 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2382 2383 bo = &vp->v_bufobj; 2384 loop: 2385 /* 2386 * Block if we are low on buffers. Certain processes are allowed 2387 * to completely exhaust the buffer cache. 2388 * 2389 * If this check ever becomes a bottleneck it may be better to 2390 * move it into the else, when gbincore() fails. At the moment 2391 * it isn't a problem. 2392 * 2393 * XXX remove if 0 sections (clean this up after its proven) 2394 */ 2395 if (numfreebuffers == 0) { 2396 if (curthread == PCPU_GET(idlethread)) 2397 return NULL; 2398 mtx_lock(&nblock); 2399 needsbuffer |= VFS_BIO_NEED_ANY; 2400 mtx_unlock(&nblock); 2401 } 2402 2403 VI_LOCK(vp); 2404 bp = gbincore(bo, blkno); 2405 if (bp != NULL) { 2406 int lockflags; 2407 /* 2408 * Buffer is in-core. If the buffer is not busy, it must 2409 * be on a queue. 2410 */ 2411 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2412 2413 if (flags & GB_LOCK_NOWAIT) 2414 lockflags |= LK_NOWAIT; 2415 2416 error = BUF_TIMELOCK(bp, lockflags, 2417 VI_MTX(vp), "getblk", slpflag, slptimeo); 2418 2419 /* 2420 * If we slept and got the lock we have to restart in case 2421 * the buffer changed identities. 2422 */ 2423 if (error == ENOLCK) 2424 goto loop; 2425 /* We timed out or were interrupted. */ 2426 else if (error) 2427 return (NULL); 2428 2429 /* 2430 * The buffer is locked. B_CACHE is cleared if the buffer is 2431 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2432 * and for a VMIO buffer B_CACHE is adjusted according to the 2433 * backing VM cache. 2434 */ 2435 if (bp->b_flags & B_INVAL) 2436 bp->b_flags &= ~B_CACHE; 2437 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2438 bp->b_flags |= B_CACHE; 2439 bremfree(bp); 2440 2441 /* 2442 * check for size inconsistancies for non-VMIO case. 2443 */ 2444 2445 if (bp->b_bcount != size) { 2446 if ((bp->b_flags & B_VMIO) == 0 || 2447 (size > bp->b_kvasize)) { 2448 if (bp->b_flags & B_DELWRI) { 2449 /* 2450 * If buffer is pinned and caller does 2451 * not want sleep waiting for it to be 2452 * unpinned, bail out 2453 * */ 2454 if (bp->b_pin_count > 0) { 2455 if (flags & GB_LOCK_NOWAIT) { 2456 bqrelse(bp); 2457 return (NULL); 2458 } else { 2459 bunpin_wait(bp); 2460 } 2461 } 2462 bp->b_flags |= B_NOCACHE; 2463 bwrite(bp); 2464 } else { 2465 if (LIST_FIRST(&bp->b_dep) == NULL) { 2466 bp->b_flags |= B_RELBUF; 2467 brelse(bp); 2468 } else { 2469 bp->b_flags |= B_NOCACHE; 2470 bwrite(bp); 2471 } 2472 } 2473 goto loop; 2474 } 2475 } 2476 2477 /* 2478 * If the size is inconsistant in the VMIO case, we can resize 2479 * the buffer. This might lead to B_CACHE getting set or 2480 * cleared. If the size has not changed, B_CACHE remains 2481 * unchanged from its previous state. 2482 */ 2483 2484 if (bp->b_bcount != size) 2485 allocbuf(bp, size); 2486 2487 KASSERT(bp->b_offset != NOOFFSET, 2488 ("getblk: no buffer offset")); 2489 2490 /* 2491 * A buffer with B_DELWRI set and B_CACHE clear must 2492 * be committed before we can return the buffer in 2493 * order to prevent the caller from issuing a read 2494 * ( due to B_CACHE not being set ) and overwriting 2495 * it. 2496 * 2497 * Most callers, including NFS and FFS, need this to 2498 * operate properly either because they assume they 2499 * can issue a read if B_CACHE is not set, or because 2500 * ( for example ) an uncached B_DELWRI might loop due 2501 * to softupdates re-dirtying the buffer. In the latter 2502 * case, B_CACHE is set after the first write completes, 2503 * preventing further loops. 2504 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2505 * above while extending the buffer, we cannot allow the 2506 * buffer to remain with B_CACHE set after the write 2507 * completes or it will represent a corrupt state. To 2508 * deal with this we set B_NOCACHE to scrap the buffer 2509 * after the write. 2510 * 2511 * We might be able to do something fancy, like setting 2512 * B_CACHE in bwrite() except if B_DELWRI is already set, 2513 * so the below call doesn't set B_CACHE, but that gets real 2514 * confusing. This is much easier. 2515 */ 2516 2517 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2518 bp->b_flags |= B_NOCACHE; 2519 bwrite(bp); 2520 goto loop; 2521 } 2522 bp->b_flags &= ~B_DONE; 2523 } else { 2524 int bsize, maxsize, vmio; 2525 off_t offset; 2526 2527 /* 2528 * Buffer is not in-core, create new buffer. The buffer 2529 * returned by getnewbuf() is locked. Note that the returned 2530 * buffer is also considered valid (not marked B_INVAL). 2531 */ 2532 VI_UNLOCK(vp); 2533 /* 2534 * If the user does not want us to create the buffer, bail out 2535 * here. 2536 */ 2537 if (flags & GB_NOCREAT) 2538 return NULL; 2539 bsize = bo->bo_bsize; 2540 offset = blkno * bsize; 2541 vmio = vp->v_object != NULL; 2542 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2543 maxsize = imax(maxsize, bsize); 2544 2545 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2546 if (bp == NULL) { 2547 if (slpflag || slptimeo) 2548 return NULL; 2549 goto loop; 2550 } 2551 2552 /* 2553 * This code is used to make sure that a buffer is not 2554 * created while the getnewbuf routine is blocked. 2555 * This can be a problem whether the vnode is locked or not. 2556 * If the buffer is created out from under us, we have to 2557 * throw away the one we just created. 2558 * 2559 * Note: this must occur before we associate the buffer 2560 * with the vp especially considering limitations in 2561 * the splay tree implementation when dealing with duplicate 2562 * lblkno's. 2563 */ 2564 BO_LOCK(bo); 2565 if (gbincore(bo, blkno)) { 2566 BO_UNLOCK(bo); 2567 bp->b_flags |= B_INVAL; 2568 brelse(bp); 2569 goto loop; 2570 } 2571 2572 /* 2573 * Insert the buffer into the hash, so that it can 2574 * be found by incore. 2575 */ 2576 bp->b_blkno = bp->b_lblkno = blkno; 2577 bp->b_offset = offset; 2578 2579 bgetvp(vp, bp); 2580 BO_UNLOCK(bo); 2581 2582 /* 2583 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2584 * buffer size starts out as 0, B_CACHE will be set by 2585 * allocbuf() for the VMIO case prior to it testing the 2586 * backing store for validity. 2587 */ 2588 2589 if (vmio) { 2590 bp->b_flags |= B_VMIO; 2591 #if defined(VFS_BIO_DEBUG) 2592 if (vn_canvmio(vp) != TRUE) 2593 printf("getblk: VMIO on vnode type %d\n", 2594 vp->v_type); 2595 #endif 2596 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2597 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2598 bp, vp->v_object, bp->b_bufobj->bo_object)); 2599 } else { 2600 bp->b_flags &= ~B_VMIO; 2601 KASSERT(bp->b_bufobj->bo_object == NULL, 2602 ("ARGH! has b_bufobj->bo_object %p %p\n", 2603 bp, bp->b_bufobj->bo_object)); 2604 } 2605 2606 allocbuf(bp, size); 2607 bp->b_flags &= ~B_DONE; 2608 } 2609 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2610 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2611 KASSERT(bp->b_bufobj == bo, 2612 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2613 return (bp); 2614 } 2615 2616 /* 2617 * Get an empty, disassociated buffer of given size. The buffer is initially 2618 * set to B_INVAL. 2619 */ 2620 struct buf * 2621 geteblk(int size) 2622 { 2623 struct buf *bp; 2624 int maxsize; 2625 2626 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2627 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2628 continue; 2629 allocbuf(bp, size); 2630 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2631 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2632 return (bp); 2633 } 2634 2635 2636 /* 2637 * This code constitutes the buffer memory from either anonymous system 2638 * memory (in the case of non-VMIO operations) or from an associated 2639 * VM object (in the case of VMIO operations). This code is able to 2640 * resize a buffer up or down. 2641 * 2642 * Note that this code is tricky, and has many complications to resolve 2643 * deadlock or inconsistant data situations. Tread lightly!!! 2644 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2645 * the caller. Calling this code willy nilly can result in the loss of data. 2646 * 2647 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2648 * B_CACHE for the non-VMIO case. 2649 */ 2650 2651 int 2652 allocbuf(struct buf *bp, int size) 2653 { 2654 int newbsize, mbsize; 2655 int i; 2656 2657 if (BUF_REFCNT(bp) == 0) 2658 panic("allocbuf: buffer not busy"); 2659 2660 if (bp->b_kvasize < size) 2661 panic("allocbuf: buffer too small"); 2662 2663 if ((bp->b_flags & B_VMIO) == 0) { 2664 caddr_t origbuf; 2665 int origbufsize; 2666 /* 2667 * Just get anonymous memory from the kernel. Don't 2668 * mess with B_CACHE. 2669 */ 2670 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2671 if (bp->b_flags & B_MALLOC) 2672 newbsize = mbsize; 2673 else 2674 newbsize = round_page(size); 2675 2676 if (newbsize < bp->b_bufsize) { 2677 /* 2678 * malloced buffers are not shrunk 2679 */ 2680 if (bp->b_flags & B_MALLOC) { 2681 if (newbsize) { 2682 bp->b_bcount = size; 2683 } else { 2684 free(bp->b_data, M_BIOBUF); 2685 if (bp->b_bufsize) { 2686 atomic_subtract_int( 2687 &bufmallocspace, 2688 bp->b_bufsize); 2689 bufspacewakeup(); 2690 bp->b_bufsize = 0; 2691 } 2692 bp->b_saveaddr = bp->b_kvabase; 2693 bp->b_data = bp->b_saveaddr; 2694 bp->b_bcount = 0; 2695 bp->b_flags &= ~B_MALLOC; 2696 } 2697 return 1; 2698 } 2699 vm_hold_free_pages( 2700 bp, 2701 (vm_offset_t) bp->b_data + newbsize, 2702 (vm_offset_t) bp->b_data + bp->b_bufsize); 2703 } else if (newbsize > bp->b_bufsize) { 2704 /* 2705 * We only use malloced memory on the first allocation. 2706 * and revert to page-allocated memory when the buffer 2707 * grows. 2708 */ 2709 /* 2710 * There is a potential smp race here that could lead 2711 * to bufmallocspace slightly passing the max. It 2712 * is probably extremely rare and not worth worrying 2713 * over. 2714 */ 2715 if ( (bufmallocspace < maxbufmallocspace) && 2716 (bp->b_bufsize == 0) && 2717 (mbsize <= PAGE_SIZE/2)) { 2718 2719 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2720 bp->b_bufsize = mbsize; 2721 bp->b_bcount = size; 2722 bp->b_flags |= B_MALLOC; 2723 atomic_add_int(&bufmallocspace, mbsize); 2724 return 1; 2725 } 2726 origbuf = NULL; 2727 origbufsize = 0; 2728 /* 2729 * If the buffer is growing on its other-than-first allocation, 2730 * then we revert to the page-allocation scheme. 2731 */ 2732 if (bp->b_flags & B_MALLOC) { 2733 origbuf = bp->b_data; 2734 origbufsize = bp->b_bufsize; 2735 bp->b_data = bp->b_kvabase; 2736 if (bp->b_bufsize) { 2737 atomic_subtract_int(&bufmallocspace, 2738 bp->b_bufsize); 2739 bufspacewakeup(); 2740 bp->b_bufsize = 0; 2741 } 2742 bp->b_flags &= ~B_MALLOC; 2743 newbsize = round_page(newbsize); 2744 } 2745 vm_hold_load_pages( 2746 bp, 2747 (vm_offset_t) bp->b_data + bp->b_bufsize, 2748 (vm_offset_t) bp->b_data + newbsize); 2749 if (origbuf) { 2750 bcopy(origbuf, bp->b_data, origbufsize); 2751 free(origbuf, M_BIOBUF); 2752 } 2753 } 2754 } else { 2755 int desiredpages; 2756 2757 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2758 desiredpages = (size == 0) ? 0 : 2759 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2760 2761 if (bp->b_flags & B_MALLOC) 2762 panic("allocbuf: VMIO buffer can't be malloced"); 2763 /* 2764 * Set B_CACHE initially if buffer is 0 length or will become 2765 * 0-length. 2766 */ 2767 if (size == 0 || bp->b_bufsize == 0) 2768 bp->b_flags |= B_CACHE; 2769 2770 if (newbsize < bp->b_bufsize) { 2771 /* 2772 * DEV_BSIZE aligned new buffer size is less then the 2773 * DEV_BSIZE aligned existing buffer size. Figure out 2774 * if we have to remove any pages. 2775 */ 2776 if (desiredpages < bp->b_npages) { 2777 vm_page_t m; 2778 2779 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2780 vm_page_lock_queues(); 2781 for (i = desiredpages; i < bp->b_npages; i++) { 2782 /* 2783 * the page is not freed here -- it 2784 * is the responsibility of 2785 * vnode_pager_setsize 2786 */ 2787 m = bp->b_pages[i]; 2788 KASSERT(m != bogus_page, 2789 ("allocbuf: bogus page found")); 2790 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2791 vm_page_lock_queues(); 2792 2793 bp->b_pages[i] = NULL; 2794 vm_page_unwire(m, 0); 2795 } 2796 vm_page_unlock_queues(); 2797 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2798 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2799 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2800 bp->b_npages = desiredpages; 2801 } 2802 } else if (size > bp->b_bcount) { 2803 /* 2804 * We are growing the buffer, possibly in a 2805 * byte-granular fashion. 2806 */ 2807 struct vnode *vp; 2808 vm_object_t obj; 2809 vm_offset_t toff; 2810 vm_offset_t tinc; 2811 2812 /* 2813 * Step 1, bring in the VM pages from the object, 2814 * allocating them if necessary. We must clear 2815 * B_CACHE if these pages are not valid for the 2816 * range covered by the buffer. 2817 */ 2818 2819 vp = bp->b_vp; 2820 obj = bp->b_bufobj->bo_object; 2821 2822 VM_OBJECT_LOCK(obj); 2823 while (bp->b_npages < desiredpages) { 2824 vm_page_t m; 2825 vm_pindex_t pi; 2826 2827 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2828 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2829 /* 2830 * note: must allocate system pages 2831 * since blocking here could intefere 2832 * with paging I/O, no matter which 2833 * process we are. 2834 */ 2835 m = vm_page_alloc(obj, pi, 2836 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2837 VM_ALLOC_WIRED); 2838 if (m == NULL) { 2839 atomic_add_int(&vm_pageout_deficit, 2840 desiredpages - bp->b_npages); 2841 VM_OBJECT_UNLOCK(obj); 2842 VM_WAIT; 2843 VM_OBJECT_LOCK(obj); 2844 } else { 2845 bp->b_flags &= ~B_CACHE; 2846 bp->b_pages[bp->b_npages] = m; 2847 ++bp->b_npages; 2848 } 2849 continue; 2850 } 2851 2852 /* 2853 * We found a page. If we have to sleep on it, 2854 * retry because it might have gotten freed out 2855 * from under us. 2856 * 2857 * We can only test PG_BUSY here. Blocking on 2858 * m->busy might lead to a deadlock: 2859 * 2860 * vm_fault->getpages->cluster_read->allocbuf 2861 * 2862 */ 2863 vm_page_lock_queues(); 2864 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2865 continue; 2866 2867 /* 2868 * We have a good page. Should we wakeup the 2869 * page daemon? 2870 */ 2871 if ((curproc != pageproc) && 2872 (VM_PAGE_INQUEUE1(m, PQ_CACHE)) && 2873 ((cnt.v_free_count + cnt.v_cache_count) < 2874 (cnt.v_free_min + cnt.v_cache_min))) { 2875 pagedaemon_wakeup(); 2876 } 2877 vm_page_wire(m); 2878 vm_page_unlock_queues(); 2879 bp->b_pages[bp->b_npages] = m; 2880 ++bp->b_npages; 2881 } 2882 2883 /* 2884 * Step 2. We've loaded the pages into the buffer, 2885 * we have to figure out if we can still have B_CACHE 2886 * set. Note that B_CACHE is set according to the 2887 * byte-granular range ( bcount and size ), new the 2888 * aligned range ( newbsize ). 2889 * 2890 * The VM test is against m->valid, which is DEV_BSIZE 2891 * aligned. Needless to say, the validity of the data 2892 * needs to also be DEV_BSIZE aligned. Note that this 2893 * fails with NFS if the server or some other client 2894 * extends the file's EOF. If our buffer is resized, 2895 * B_CACHE may remain set! XXX 2896 */ 2897 2898 toff = bp->b_bcount; 2899 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2900 2901 while ((bp->b_flags & B_CACHE) && toff < size) { 2902 vm_pindex_t pi; 2903 2904 if (tinc > (size - toff)) 2905 tinc = size - toff; 2906 2907 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2908 PAGE_SHIFT; 2909 2910 vfs_buf_test_cache( 2911 bp, 2912 bp->b_offset, 2913 toff, 2914 tinc, 2915 bp->b_pages[pi] 2916 ); 2917 toff += tinc; 2918 tinc = PAGE_SIZE; 2919 } 2920 VM_OBJECT_UNLOCK(obj); 2921 2922 /* 2923 * Step 3, fixup the KVM pmap. Remember that 2924 * bp->b_data is relative to bp->b_offset, but 2925 * bp->b_offset may be offset into the first page. 2926 */ 2927 2928 bp->b_data = (caddr_t) 2929 trunc_page((vm_offset_t)bp->b_data); 2930 pmap_qenter( 2931 (vm_offset_t)bp->b_data, 2932 bp->b_pages, 2933 bp->b_npages 2934 ); 2935 2936 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2937 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2938 } 2939 } 2940 if (newbsize < bp->b_bufsize) 2941 bufspacewakeup(); 2942 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2943 bp->b_bcount = size; /* requested buffer size */ 2944 return 1; 2945 } 2946 2947 void 2948 biodone(struct bio *bp) 2949 { 2950 void (*done)(struct bio *); 2951 2952 mtx_lock(&bdonelock); 2953 bp->bio_flags |= BIO_DONE; 2954 done = bp->bio_done; 2955 if (done == NULL) 2956 wakeup(bp); 2957 mtx_unlock(&bdonelock); 2958 if (done != NULL) 2959 done(bp); 2960 } 2961 2962 /* 2963 * Wait for a BIO to finish. 2964 * 2965 * XXX: resort to a timeout for now. The optimal locking (if any) for this 2966 * case is not yet clear. 2967 */ 2968 int 2969 biowait(struct bio *bp, const char *wchan) 2970 { 2971 2972 mtx_lock(&bdonelock); 2973 while ((bp->bio_flags & BIO_DONE) == 0) 2974 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 2975 mtx_unlock(&bdonelock); 2976 if (bp->bio_error != 0) 2977 return (bp->bio_error); 2978 if (!(bp->bio_flags & BIO_ERROR)) 2979 return (0); 2980 return (EIO); 2981 } 2982 2983 void 2984 biofinish(struct bio *bp, struct devstat *stat, int error) 2985 { 2986 2987 if (error) { 2988 bp->bio_error = error; 2989 bp->bio_flags |= BIO_ERROR; 2990 } 2991 if (stat != NULL) 2992 devstat_end_transaction_bio(stat, bp); 2993 biodone(bp); 2994 } 2995 2996 /* 2997 * bufwait: 2998 * 2999 * Wait for buffer I/O completion, returning error status. The buffer 3000 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3001 * error and cleared. 3002 */ 3003 int 3004 bufwait(struct buf *bp) 3005 { 3006 if (bp->b_iocmd == BIO_READ) 3007 bwait(bp, PRIBIO, "biord"); 3008 else 3009 bwait(bp, PRIBIO, "biowr"); 3010 if (bp->b_flags & B_EINTR) { 3011 bp->b_flags &= ~B_EINTR; 3012 return (EINTR); 3013 } 3014 if (bp->b_ioflags & BIO_ERROR) { 3015 return (bp->b_error ? bp->b_error : EIO); 3016 } else { 3017 return (0); 3018 } 3019 } 3020 3021 /* 3022 * Call back function from struct bio back up to struct buf. 3023 */ 3024 static void 3025 bufdonebio(struct bio *bip) 3026 { 3027 struct buf *bp; 3028 3029 bp = bip->bio_caller2; 3030 bp->b_resid = bp->b_bcount - bip->bio_completed; 3031 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3032 bp->b_ioflags = bip->bio_flags; 3033 bp->b_error = bip->bio_error; 3034 if (bp->b_error) 3035 bp->b_ioflags |= BIO_ERROR; 3036 bufdone(bp); 3037 g_destroy_bio(bip); 3038 } 3039 3040 void 3041 dev_strategy(struct cdev *dev, struct buf *bp) 3042 { 3043 struct cdevsw *csw; 3044 struct bio *bip; 3045 3046 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3047 panic("b_iocmd botch"); 3048 for (;;) { 3049 bip = g_new_bio(); 3050 if (bip != NULL) 3051 break; 3052 /* Try again later */ 3053 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3054 } 3055 bip->bio_cmd = bp->b_iocmd; 3056 bip->bio_offset = bp->b_iooffset; 3057 bip->bio_length = bp->b_bcount; 3058 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3059 bip->bio_data = bp->b_data; 3060 bip->bio_done = bufdonebio; 3061 bip->bio_caller2 = bp; 3062 bip->bio_dev = dev; 3063 KASSERT(dev->si_refcount > 0, 3064 ("dev_strategy on un-referenced struct cdev *(%s)", 3065 devtoname(dev))); 3066 csw = dev_refthread(dev); 3067 if (csw == NULL) { 3068 bp->b_error = ENXIO; 3069 bp->b_ioflags = BIO_ERROR; 3070 bufdone(bp); 3071 return; 3072 } 3073 (*csw->d_strategy)(bip); 3074 dev_relthread(dev); 3075 } 3076 3077 /* 3078 * bufdone: 3079 * 3080 * Finish I/O on a buffer, optionally calling a completion function. 3081 * This is usually called from an interrupt so process blocking is 3082 * not allowed. 3083 * 3084 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3085 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3086 * assuming B_INVAL is clear. 3087 * 3088 * For the VMIO case, we set B_CACHE if the op was a read and no 3089 * read error occured, or if the op was a write. B_CACHE is never 3090 * set if the buffer is invalid or otherwise uncacheable. 3091 * 3092 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3093 * initiator to leave B_INVAL set to brelse the buffer out of existance 3094 * in the biodone routine. 3095 */ 3096 void 3097 bufdone(struct buf *bp) 3098 { 3099 struct bufobj *dropobj; 3100 void (*biodone)(struct buf *); 3101 3102 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3103 dropobj = NULL; 3104 3105 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3106 BUF_REFCNT(bp))); 3107 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3108 3109 runningbufwakeup(bp); 3110 if (bp->b_iocmd == BIO_WRITE) 3111 dropobj = bp->b_bufobj; 3112 /* call optional completion function if requested */ 3113 if (bp->b_iodone != NULL) { 3114 biodone = bp->b_iodone; 3115 bp->b_iodone = NULL; 3116 (*biodone) (bp); 3117 if (dropobj) 3118 bufobj_wdrop(dropobj); 3119 return; 3120 } 3121 3122 bufdone_finish(bp); 3123 3124 if (dropobj) 3125 bufobj_wdrop(dropobj); 3126 } 3127 3128 void 3129 bufdone_finish(struct buf *bp) 3130 { 3131 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3132 BUF_REFCNT(bp))); 3133 3134 if (LIST_FIRST(&bp->b_dep) != NULL) 3135 buf_complete(bp); 3136 3137 if (bp->b_flags & B_VMIO) { 3138 int i; 3139 vm_ooffset_t foff; 3140 vm_page_t m; 3141 vm_object_t obj; 3142 int iosize; 3143 struct vnode *vp = bp->b_vp; 3144 3145 obj = bp->b_bufobj->bo_object; 3146 3147 #if defined(VFS_BIO_DEBUG) 3148 mp_fixme("usecount and vflag accessed without locks."); 3149 if (vp->v_usecount == 0) { 3150 panic("biodone: zero vnode ref count"); 3151 } 3152 3153 KASSERT(vp->v_object != NULL, 3154 ("biodone: vnode %p has no vm_object", vp)); 3155 #endif 3156 3157 foff = bp->b_offset; 3158 KASSERT(bp->b_offset != NOOFFSET, 3159 ("biodone: no buffer offset")); 3160 3161 VM_OBJECT_LOCK(obj); 3162 #if defined(VFS_BIO_DEBUG) 3163 if (obj->paging_in_progress < bp->b_npages) { 3164 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3165 obj->paging_in_progress, bp->b_npages); 3166 } 3167 #endif 3168 3169 /* 3170 * Set B_CACHE if the op was a normal read and no error 3171 * occured. B_CACHE is set for writes in the b*write() 3172 * routines. 3173 */ 3174 iosize = bp->b_bcount - bp->b_resid; 3175 if (bp->b_iocmd == BIO_READ && 3176 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3177 !(bp->b_ioflags & BIO_ERROR)) { 3178 bp->b_flags |= B_CACHE; 3179 } 3180 vm_page_lock_queues(); 3181 for (i = 0; i < bp->b_npages; i++) { 3182 int bogusflag = 0; 3183 int resid; 3184 3185 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3186 if (resid > iosize) 3187 resid = iosize; 3188 3189 /* 3190 * cleanup bogus pages, restoring the originals 3191 */ 3192 m = bp->b_pages[i]; 3193 if (m == bogus_page) { 3194 bogusflag = 1; 3195 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3196 if (m == NULL) 3197 panic("biodone: page disappeared!"); 3198 bp->b_pages[i] = m; 3199 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3200 bp->b_pages, bp->b_npages); 3201 } 3202 #if defined(VFS_BIO_DEBUG) 3203 if (OFF_TO_IDX(foff) != m->pindex) { 3204 printf( 3205 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3206 (intmax_t)foff, (uintmax_t)m->pindex); 3207 } 3208 #endif 3209 3210 /* 3211 * In the write case, the valid and clean bits are 3212 * already changed correctly ( see bdwrite() ), so we 3213 * only need to do this here in the read case. 3214 */ 3215 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3216 vfs_page_set_valid(bp, foff, i, m); 3217 } 3218 3219 /* 3220 * when debugging new filesystems or buffer I/O methods, this 3221 * is the most common error that pops up. if you see this, you 3222 * have not set the page busy flag correctly!!! 3223 */ 3224 if (m->busy == 0) { 3225 printf("biodone: page busy < 0, " 3226 "pindex: %d, foff: 0x(%x,%x), " 3227 "resid: %d, index: %d\n", 3228 (int) m->pindex, (int)(foff >> 32), 3229 (int) foff & 0xffffffff, resid, i); 3230 if (!vn_isdisk(vp, NULL)) 3231 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3232 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3233 (intmax_t) bp->b_lblkno, 3234 bp->b_flags, bp->b_npages); 3235 else 3236 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3237 (intmax_t) bp->b_lblkno, 3238 bp->b_flags, bp->b_npages); 3239 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3240 (u_long)m->valid, (u_long)m->dirty, 3241 m->wire_count); 3242 panic("biodone: page busy < 0\n"); 3243 } 3244 vm_page_io_finish(m); 3245 vm_object_pip_subtract(obj, 1); 3246 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3247 iosize -= resid; 3248 } 3249 vm_page_unlock_queues(); 3250 vm_object_pip_wakeupn(obj, 0); 3251 VM_OBJECT_UNLOCK(obj); 3252 } 3253 3254 /* 3255 * For asynchronous completions, release the buffer now. The brelse 3256 * will do a wakeup there if necessary - so no need to do a wakeup 3257 * here in the async case. The sync case always needs to do a wakeup. 3258 */ 3259 3260 if (bp->b_flags & B_ASYNC) { 3261 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3262 brelse(bp); 3263 else 3264 bqrelse(bp); 3265 } else 3266 bdone(bp); 3267 } 3268 3269 /* 3270 * This routine is called in lieu of iodone in the case of 3271 * incomplete I/O. This keeps the busy status for pages 3272 * consistant. 3273 */ 3274 void 3275 vfs_unbusy_pages(struct buf *bp) 3276 { 3277 int i; 3278 vm_object_t obj; 3279 vm_page_t m; 3280 3281 runningbufwakeup(bp); 3282 if (!(bp->b_flags & B_VMIO)) 3283 return; 3284 3285 obj = bp->b_bufobj->bo_object; 3286 VM_OBJECT_LOCK(obj); 3287 vm_page_lock_queues(); 3288 for (i = 0; i < bp->b_npages; i++) { 3289 m = bp->b_pages[i]; 3290 if (m == bogus_page) { 3291 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3292 if (!m) 3293 panic("vfs_unbusy_pages: page missing\n"); 3294 bp->b_pages[i] = m; 3295 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3296 bp->b_pages, bp->b_npages); 3297 } 3298 vm_object_pip_subtract(obj, 1); 3299 vm_page_io_finish(m); 3300 } 3301 vm_page_unlock_queues(); 3302 vm_object_pip_wakeupn(obj, 0); 3303 VM_OBJECT_UNLOCK(obj); 3304 } 3305 3306 /* 3307 * vfs_page_set_valid: 3308 * 3309 * Set the valid bits in a page based on the supplied offset. The 3310 * range is restricted to the buffer's size. 3311 * 3312 * This routine is typically called after a read completes. 3313 */ 3314 static void 3315 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3316 { 3317 vm_ooffset_t soff, eoff; 3318 3319 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3320 /* 3321 * Start and end offsets in buffer. eoff - soff may not cross a 3322 * page boundry or cross the end of the buffer. The end of the 3323 * buffer, in this case, is our file EOF, not the allocation size 3324 * of the buffer. 3325 */ 3326 soff = off; 3327 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3328 if (eoff > bp->b_offset + bp->b_bcount) 3329 eoff = bp->b_offset + bp->b_bcount; 3330 3331 /* 3332 * Set valid range. This is typically the entire buffer and thus the 3333 * entire page. 3334 */ 3335 if (eoff > soff) { 3336 vm_page_set_validclean( 3337 m, 3338 (vm_offset_t) (soff & PAGE_MASK), 3339 (vm_offset_t) (eoff - soff) 3340 ); 3341 } 3342 } 3343 3344 /* 3345 * This routine is called before a device strategy routine. 3346 * It is used to tell the VM system that paging I/O is in 3347 * progress, and treat the pages associated with the buffer 3348 * almost as being PG_BUSY. Also the object paging_in_progress 3349 * flag is handled to make sure that the object doesn't become 3350 * inconsistant. 3351 * 3352 * Since I/O has not been initiated yet, certain buffer flags 3353 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3354 * and should be ignored. 3355 */ 3356 void 3357 vfs_busy_pages(struct buf *bp, int clear_modify) 3358 { 3359 int i, bogus; 3360 vm_object_t obj; 3361 vm_ooffset_t foff; 3362 vm_page_t m; 3363 3364 if (!(bp->b_flags & B_VMIO)) 3365 return; 3366 3367 obj = bp->b_bufobj->bo_object; 3368 foff = bp->b_offset; 3369 KASSERT(bp->b_offset != NOOFFSET, 3370 ("vfs_busy_pages: no buffer offset")); 3371 vfs_setdirty(bp); 3372 VM_OBJECT_LOCK(obj); 3373 retry: 3374 vm_page_lock_queues(); 3375 for (i = 0; i < bp->b_npages; i++) { 3376 m = bp->b_pages[i]; 3377 3378 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3379 goto retry; 3380 } 3381 bogus = 0; 3382 for (i = 0; i < bp->b_npages; i++) { 3383 m = bp->b_pages[i]; 3384 3385 if ((bp->b_flags & B_CLUSTER) == 0) { 3386 vm_object_pip_add(obj, 1); 3387 vm_page_io_start(m); 3388 } 3389 /* 3390 * When readying a buffer for a read ( i.e 3391 * clear_modify == 0 ), it is important to do 3392 * bogus_page replacement for valid pages in 3393 * partially instantiated buffers. Partially 3394 * instantiated buffers can, in turn, occur when 3395 * reconstituting a buffer from its VM backing store 3396 * base. We only have to do this if B_CACHE is 3397 * clear ( which causes the I/O to occur in the 3398 * first place ). The replacement prevents the read 3399 * I/O from overwriting potentially dirty VM-backed 3400 * pages. XXX bogus page replacement is, uh, bogus. 3401 * It may not work properly with small-block devices. 3402 * We need to find a better way. 3403 */ 3404 pmap_remove_all(m); 3405 if (clear_modify) 3406 vfs_page_set_valid(bp, foff, i, m); 3407 else if (m->valid == VM_PAGE_BITS_ALL && 3408 (bp->b_flags & B_CACHE) == 0) { 3409 bp->b_pages[i] = bogus_page; 3410 bogus++; 3411 } 3412 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3413 } 3414 vm_page_unlock_queues(); 3415 VM_OBJECT_UNLOCK(obj); 3416 if (bogus) 3417 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3418 bp->b_pages, bp->b_npages); 3419 } 3420 3421 /* 3422 * Tell the VM system that the pages associated with this buffer 3423 * are clean. This is used for delayed writes where the data is 3424 * going to go to disk eventually without additional VM intevention. 3425 * 3426 * Note that while we only really need to clean through to b_bcount, we 3427 * just go ahead and clean through to b_bufsize. 3428 */ 3429 static void 3430 vfs_clean_pages(struct buf *bp) 3431 { 3432 int i; 3433 vm_ooffset_t foff, noff, eoff; 3434 vm_page_t m; 3435 3436 if (!(bp->b_flags & B_VMIO)) 3437 return; 3438 3439 foff = bp->b_offset; 3440 KASSERT(bp->b_offset != NOOFFSET, 3441 ("vfs_clean_pages: no buffer offset")); 3442 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3443 vm_page_lock_queues(); 3444 for (i = 0; i < bp->b_npages; i++) { 3445 m = bp->b_pages[i]; 3446 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3447 eoff = noff; 3448 3449 if (eoff > bp->b_offset + bp->b_bufsize) 3450 eoff = bp->b_offset + bp->b_bufsize; 3451 vfs_page_set_valid(bp, foff, i, m); 3452 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3453 foff = noff; 3454 } 3455 vm_page_unlock_queues(); 3456 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3457 } 3458 3459 /* 3460 * vfs_bio_set_validclean: 3461 * 3462 * Set the range within the buffer to valid and clean. The range is 3463 * relative to the beginning of the buffer, b_offset. Note that b_offset 3464 * itself may be offset from the beginning of the first page. 3465 * 3466 */ 3467 3468 void 3469 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3470 { 3471 int i, n; 3472 vm_page_t m; 3473 3474 if (!(bp->b_flags & B_VMIO)) 3475 return; 3476 /* 3477 * Fixup base to be relative to beginning of first page. 3478 * Set initial n to be the maximum number of bytes in the 3479 * first page that can be validated. 3480 */ 3481 3482 base += (bp->b_offset & PAGE_MASK); 3483 n = PAGE_SIZE - (base & PAGE_MASK); 3484 3485 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3486 vm_page_lock_queues(); 3487 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3488 m = bp->b_pages[i]; 3489 if (n > size) 3490 n = size; 3491 vm_page_set_validclean(m, base & PAGE_MASK, n); 3492 base += n; 3493 size -= n; 3494 n = PAGE_SIZE; 3495 } 3496 vm_page_unlock_queues(); 3497 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3498 } 3499 3500 /* 3501 * vfs_bio_clrbuf: 3502 * 3503 * clear a buffer. This routine essentially fakes an I/O, so we need 3504 * to clear BIO_ERROR and B_INVAL. 3505 * 3506 * Note that while we only theoretically need to clear through b_bcount, 3507 * we go ahead and clear through b_bufsize. 3508 */ 3509 3510 void 3511 vfs_bio_clrbuf(struct buf *bp) 3512 { 3513 int i, j, mask = 0; 3514 caddr_t sa, ea; 3515 3516 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3517 clrbuf(bp); 3518 return; 3519 } 3520 3521 bp->b_flags &= ~B_INVAL; 3522 bp->b_ioflags &= ~BIO_ERROR; 3523 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3524 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3525 (bp->b_offset & PAGE_MASK) == 0) { 3526 if (bp->b_pages[0] == bogus_page) 3527 goto unlock; 3528 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3529 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3530 if ((bp->b_pages[0]->valid & mask) == mask) 3531 goto unlock; 3532 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3533 ((bp->b_pages[0]->valid & mask) == 0)) { 3534 bzero(bp->b_data, bp->b_bufsize); 3535 bp->b_pages[0]->valid |= mask; 3536 goto unlock; 3537 } 3538 } 3539 ea = sa = bp->b_data; 3540 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3541 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3542 ea = (caddr_t)(vm_offset_t)ulmin( 3543 (u_long)(vm_offset_t)ea, 3544 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3545 if (bp->b_pages[i] == bogus_page) 3546 continue; 3547 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3548 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3549 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3550 if ((bp->b_pages[i]->valid & mask) == mask) 3551 continue; 3552 if ((bp->b_pages[i]->valid & mask) == 0) { 3553 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3554 bzero(sa, ea - sa); 3555 } else { 3556 for (; sa < ea; sa += DEV_BSIZE, j++) { 3557 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3558 (bp->b_pages[i]->valid & (1 << j)) == 0) 3559 bzero(sa, DEV_BSIZE); 3560 } 3561 } 3562 bp->b_pages[i]->valid |= mask; 3563 } 3564 unlock: 3565 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3566 bp->b_resid = 0; 3567 } 3568 3569 /* 3570 * vm_hold_load_pages and vm_hold_free_pages get pages into 3571 * a buffers address space. The pages are anonymous and are 3572 * not associated with a file object. 3573 */ 3574 static void 3575 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3576 { 3577 vm_offset_t pg; 3578 vm_page_t p; 3579 int index; 3580 3581 to = round_page(to); 3582 from = round_page(from); 3583 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3584 3585 VM_OBJECT_LOCK(kernel_object); 3586 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3587 tryagain: 3588 /* 3589 * note: must allocate system pages since blocking here 3590 * could intefere with paging I/O, no matter which 3591 * process we are. 3592 */ 3593 p = vm_page_alloc(kernel_object, 3594 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3595 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3596 if (!p) { 3597 atomic_add_int(&vm_pageout_deficit, 3598 (to - pg) >> PAGE_SHIFT); 3599 VM_OBJECT_UNLOCK(kernel_object); 3600 VM_WAIT; 3601 VM_OBJECT_LOCK(kernel_object); 3602 goto tryagain; 3603 } 3604 p->valid = VM_PAGE_BITS_ALL; 3605 pmap_qenter(pg, &p, 1); 3606 bp->b_pages[index] = p; 3607 } 3608 VM_OBJECT_UNLOCK(kernel_object); 3609 bp->b_npages = index; 3610 } 3611 3612 /* Return pages associated with this buf to the vm system */ 3613 static void 3614 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3615 { 3616 vm_offset_t pg; 3617 vm_page_t p; 3618 int index, newnpages; 3619 3620 from = round_page(from); 3621 to = round_page(to); 3622 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3623 3624 VM_OBJECT_LOCK(kernel_object); 3625 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3626 p = bp->b_pages[index]; 3627 if (p && (index < bp->b_npages)) { 3628 if (p->busy) { 3629 printf( 3630 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3631 (intmax_t)bp->b_blkno, 3632 (intmax_t)bp->b_lblkno); 3633 } 3634 bp->b_pages[index] = NULL; 3635 pmap_qremove(pg, 1); 3636 vm_page_lock_queues(); 3637 vm_page_unwire(p, 0); 3638 vm_page_free(p); 3639 vm_page_unlock_queues(); 3640 } 3641 } 3642 VM_OBJECT_UNLOCK(kernel_object); 3643 bp->b_npages = newnpages; 3644 } 3645 3646 /* 3647 * Map an IO request into kernel virtual address space. 3648 * 3649 * All requests are (re)mapped into kernel VA space. 3650 * Notice that we use b_bufsize for the size of the buffer 3651 * to be mapped. b_bcount might be modified by the driver. 3652 * 3653 * Note that even if the caller determines that the address space should 3654 * be valid, a race or a smaller-file mapped into a larger space may 3655 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3656 * check the return value. 3657 */ 3658 int 3659 vmapbuf(struct buf *bp) 3660 { 3661 caddr_t addr, kva; 3662 vm_prot_t prot; 3663 int pidx, i; 3664 struct vm_page *m; 3665 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3666 3667 if (bp->b_bufsize < 0) 3668 return (-1); 3669 prot = VM_PROT_READ; 3670 if (bp->b_iocmd == BIO_READ) 3671 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3672 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3673 addr < bp->b_data + bp->b_bufsize; 3674 addr += PAGE_SIZE, pidx++) { 3675 /* 3676 * Do the vm_fault if needed; do the copy-on-write thing 3677 * when reading stuff off device into memory. 3678 * 3679 * NOTE! Must use pmap_extract() because addr may be in 3680 * the userland address space, and kextract is only guarenteed 3681 * to work for the kernland address space (see: sparc64 port). 3682 */ 3683 retry: 3684 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3685 prot) < 0) { 3686 vm_page_lock_queues(); 3687 for (i = 0; i < pidx; ++i) { 3688 vm_page_unhold(bp->b_pages[i]); 3689 bp->b_pages[i] = NULL; 3690 } 3691 vm_page_unlock_queues(); 3692 return(-1); 3693 } 3694 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3695 if (m == NULL) 3696 goto retry; 3697 bp->b_pages[pidx] = m; 3698 } 3699 if (pidx > btoc(MAXPHYS)) 3700 panic("vmapbuf: mapped more than MAXPHYS"); 3701 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3702 3703 kva = bp->b_saveaddr; 3704 bp->b_npages = pidx; 3705 bp->b_saveaddr = bp->b_data; 3706 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3707 return(0); 3708 } 3709 3710 /* 3711 * Free the io map PTEs associated with this IO operation. 3712 * We also invalidate the TLB entries and restore the original b_addr. 3713 */ 3714 void 3715 vunmapbuf(struct buf *bp) 3716 { 3717 int pidx; 3718 int npages; 3719 3720 npages = bp->b_npages; 3721 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3722 vm_page_lock_queues(); 3723 for (pidx = 0; pidx < npages; pidx++) 3724 vm_page_unhold(bp->b_pages[pidx]); 3725 vm_page_unlock_queues(); 3726 3727 bp->b_data = bp->b_saveaddr; 3728 } 3729 3730 void 3731 bdone(struct buf *bp) 3732 { 3733 3734 mtx_lock(&bdonelock); 3735 bp->b_flags |= B_DONE; 3736 wakeup(bp); 3737 mtx_unlock(&bdonelock); 3738 } 3739 3740 void 3741 bwait(struct buf *bp, u_char pri, const char *wchan) 3742 { 3743 3744 mtx_lock(&bdonelock); 3745 while ((bp->b_flags & B_DONE) == 0) 3746 msleep(bp, &bdonelock, pri, wchan, 0); 3747 mtx_unlock(&bdonelock); 3748 } 3749 3750 int 3751 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3752 { 3753 3754 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3755 } 3756 3757 void 3758 bufstrategy(struct bufobj *bo, struct buf *bp) 3759 { 3760 int i = 0; 3761 struct vnode *vp; 3762 3763 vp = bp->b_vp; 3764 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3765 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3766 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3767 i = VOP_STRATEGY(vp, bp); 3768 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3769 } 3770 3771 void 3772 bufobj_wrefl(struct bufobj *bo) 3773 { 3774 3775 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3776 ASSERT_BO_LOCKED(bo); 3777 bo->bo_numoutput++; 3778 } 3779 3780 void 3781 bufobj_wref(struct bufobj *bo) 3782 { 3783 3784 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3785 BO_LOCK(bo); 3786 bo->bo_numoutput++; 3787 BO_UNLOCK(bo); 3788 } 3789 3790 void 3791 bufobj_wdrop(struct bufobj *bo) 3792 { 3793 3794 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3795 BO_LOCK(bo); 3796 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3797 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3798 bo->bo_flag &= ~BO_WWAIT; 3799 wakeup(&bo->bo_numoutput); 3800 } 3801 BO_UNLOCK(bo); 3802 } 3803 3804 int 3805 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3806 { 3807 int error; 3808 3809 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3810 ASSERT_BO_LOCKED(bo); 3811 error = 0; 3812 while (bo->bo_numoutput) { 3813 bo->bo_flag |= BO_WWAIT; 3814 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3815 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3816 if (error) 3817 break; 3818 } 3819 return (error); 3820 } 3821 3822 void 3823 bpin(struct buf *bp) 3824 { 3825 mtx_lock(&bpinlock); 3826 bp->b_pin_count++; 3827 mtx_unlock(&bpinlock); 3828 } 3829 3830 void 3831 bunpin(struct buf *bp) 3832 { 3833 mtx_lock(&bpinlock); 3834 if (--bp->b_pin_count == 0) 3835 wakeup(bp); 3836 mtx_unlock(&bpinlock); 3837 } 3838 3839 void 3840 bunpin_wait(struct buf *bp) 3841 { 3842 mtx_lock(&bpinlock); 3843 while (bp->b_pin_count > 0) 3844 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3845 mtx_unlock(&bpinlock); 3846 } 3847 3848 #include "opt_ddb.h" 3849 #ifdef DDB 3850 #include <ddb/ddb.h> 3851 3852 /* DDB command to show buffer data */ 3853 DB_SHOW_COMMAND(buffer, db_show_buffer) 3854 { 3855 /* get args */ 3856 struct buf *bp = (struct buf *)addr; 3857 3858 if (!have_addr) { 3859 db_printf("usage: show buffer <addr>\n"); 3860 return; 3861 } 3862 3863 db_printf("buf at %p\n", bp); 3864 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3865 db_printf( 3866 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3867 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3868 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3869 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3870 if (bp->b_npages) { 3871 int i; 3872 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3873 for (i = 0; i < bp->b_npages; i++) { 3874 vm_page_t m; 3875 m = bp->b_pages[i]; 3876 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3877 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3878 if ((i + 1) < bp->b_npages) 3879 db_printf(","); 3880 } 3881 db_printf("\n"); 3882 } 3883 lockmgr_printinfo(&bp->b_lock); 3884 } 3885 3886 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3887 { 3888 struct buf *bp; 3889 int i; 3890 3891 for (i = 0; i < nbuf; i++) { 3892 bp = &buf[i]; 3893 if (lockcount(&bp->b_lock)) { 3894 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3895 db_printf("\n"); 3896 } 3897 } 3898 } 3899 #endif /* DDB */ 3900