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, int); 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 6 /* 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_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 253 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 254 #define QUEUE_EMPTY 5 /* empty buffer headers */ 255 256 /* Queues for free buffers with various properties */ 257 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 258 259 /* Lock for the bufqueues */ 260 static struct mtx bqlock; 261 262 /* 263 * Single global constant for BUF_WMESG, to avoid getting multiple references. 264 * buf_wmesg is referred from macros. 265 */ 266 const char *buf_wmesg = BUF_WMESG; 267 268 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 269 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 270 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 271 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 272 273 #ifdef DIRECTIO 274 extern void ffs_rawread_setup(void); 275 #endif /* DIRECTIO */ 276 /* 277 * numdirtywakeup: 278 * 279 * If someone is blocked due to there being too many dirty buffers, 280 * and numdirtybuffers is now reasonable, wake them up. 281 */ 282 283 static __inline void 284 numdirtywakeup(int level) 285 { 286 287 if (numdirtybuffers <= level) { 288 mtx_lock(&nblock); 289 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 290 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 291 wakeup(&needsbuffer); 292 } 293 mtx_unlock(&nblock); 294 } 295 } 296 297 /* 298 * bufspacewakeup: 299 * 300 * Called when buffer space is potentially available for recovery. 301 * getnewbuf() will block on this flag when it is unable to free 302 * sufficient buffer space. Buffer space becomes recoverable when 303 * bp's get placed back in the queues. 304 */ 305 306 static __inline void 307 bufspacewakeup(void) 308 { 309 310 /* 311 * If someone is waiting for BUF space, wake them up. Even 312 * though we haven't freed the kva space yet, the waiting 313 * process will be able to now. 314 */ 315 mtx_lock(&nblock); 316 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 317 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 318 wakeup(&needsbuffer); 319 } 320 mtx_unlock(&nblock); 321 } 322 323 /* 324 * runningbufwakeup() - in-progress I/O accounting. 325 * 326 */ 327 void 328 runningbufwakeup(struct buf *bp) 329 { 330 331 if (bp->b_runningbufspace) { 332 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 333 bp->b_runningbufspace = 0; 334 mtx_lock(&rbreqlock); 335 if (runningbufreq && runningbufspace <= lorunningspace) { 336 runningbufreq = 0; 337 wakeup(&runningbufreq); 338 } 339 mtx_unlock(&rbreqlock); 340 } 341 } 342 343 /* 344 * bufcountwakeup: 345 * 346 * Called when a buffer has been added to one of the free queues to 347 * account for the buffer and to wakeup anyone waiting for free buffers. 348 * This typically occurs when large amounts of metadata are being handled 349 * by the buffer cache ( else buffer space runs out first, usually ). 350 */ 351 352 static __inline void 353 bufcountwakeup(void) 354 { 355 356 atomic_add_int(&numfreebuffers, 1); 357 mtx_lock(&nblock); 358 if (needsbuffer) { 359 needsbuffer &= ~VFS_BIO_NEED_ANY; 360 if (numfreebuffers >= hifreebuffers) 361 needsbuffer &= ~VFS_BIO_NEED_FREE; 362 wakeup(&needsbuffer); 363 } 364 mtx_unlock(&nblock); 365 } 366 367 /* 368 * waitrunningbufspace() 369 * 370 * runningbufspace is a measure of the amount of I/O currently 371 * running. This routine is used in async-write situations to 372 * prevent creating huge backups of pending writes to a device. 373 * Only asynchronous writes are governed by this function. 374 * 375 * Reads will adjust runningbufspace, but will not block based on it. 376 * The read load has a side effect of reducing the allowed write load. 377 * 378 * This does NOT turn an async write into a sync write. It waits 379 * for earlier writes to complete and generally returns before the 380 * caller's write has reached the device. 381 */ 382 void 383 waitrunningbufspace(void) 384 { 385 386 mtx_lock(&rbreqlock); 387 while (runningbufspace > hirunningspace) { 388 ++runningbufreq; 389 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 390 } 391 mtx_unlock(&rbreqlock); 392 } 393 394 395 /* 396 * vfs_buf_test_cache: 397 * 398 * Called when a buffer is extended. This function clears the B_CACHE 399 * bit if the newly extended portion of the buffer does not contain 400 * valid data. 401 */ 402 static __inline 403 void 404 vfs_buf_test_cache(struct buf *bp, 405 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 406 vm_page_t m) 407 { 408 409 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 410 if (bp->b_flags & B_CACHE) { 411 int base = (foff + off) & PAGE_MASK; 412 if (vm_page_is_valid(m, base, size) == 0) 413 bp->b_flags &= ~B_CACHE; 414 } 415 } 416 417 /* Wake up the buffer deamon if necessary */ 418 static __inline 419 void 420 bd_wakeup(int dirtybuflevel) 421 { 422 423 mtx_lock(&bdlock); 424 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 425 bd_request = 1; 426 wakeup(&bd_request); 427 } 428 mtx_unlock(&bdlock); 429 } 430 431 /* 432 * bd_speedup - speedup the buffer cache flushing code 433 */ 434 435 static __inline 436 void 437 bd_speedup(void) 438 { 439 440 bd_wakeup(1); 441 } 442 443 /* 444 * Calculating buffer cache scaling values and reserve space for buffer 445 * headers. This is called during low level kernel initialization and 446 * may be called more then once. We CANNOT write to the memory area 447 * being reserved at this time. 448 */ 449 caddr_t 450 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 451 { 452 453 /* 454 * physmem_est is in pages. Convert it to kilobytes (assumes 455 * PAGE_SIZE is >= 1K) 456 */ 457 physmem_est = physmem_est * (PAGE_SIZE / 1024); 458 459 /* 460 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 461 * For the first 64MB of ram nominally allocate sufficient buffers to 462 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 463 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 464 * the buffer cache we limit the eventual kva reservation to 465 * maxbcache bytes. 466 * 467 * factor represents the 1/4 x ram conversion. 468 */ 469 if (nbuf == 0) { 470 int factor = 4 * BKVASIZE / 1024; 471 472 nbuf = 50; 473 if (physmem_est > 4096) 474 nbuf += min((physmem_est - 4096) / factor, 475 65536 / factor); 476 if (physmem_est > 65536) 477 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 478 479 if (maxbcache && nbuf > maxbcache / BKVASIZE) 480 nbuf = maxbcache / BKVASIZE; 481 } 482 483 #if 0 484 /* 485 * Do not allow the buffer_map to be more then 1/2 the size of the 486 * kernel_map. 487 */ 488 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 489 (BKVASIZE * 2)) { 490 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 491 (BKVASIZE * 2); 492 printf("Warning: nbufs capped at %d\n", nbuf); 493 } 494 #endif 495 496 /* 497 * swbufs are used as temporary holders for I/O, such as paging I/O. 498 * We have no less then 16 and no more then 256. 499 */ 500 nswbuf = max(min(nbuf/4, 256), 16); 501 #ifdef NSWBUF_MIN 502 if (nswbuf < NSWBUF_MIN) 503 nswbuf = NSWBUF_MIN; 504 #endif 505 #ifdef DIRECTIO 506 ffs_rawread_setup(); 507 #endif 508 509 /* 510 * Reserve space for the buffer cache buffers 511 */ 512 swbuf = (void *)v; 513 v = (caddr_t)(swbuf + nswbuf); 514 buf = (void *)v; 515 v = (caddr_t)(buf + nbuf); 516 517 return(v); 518 } 519 520 /* Initialize the buffer subsystem. Called before use of any buffers. */ 521 void 522 bufinit(void) 523 { 524 struct buf *bp; 525 int i; 526 527 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 528 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 529 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 530 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 531 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 532 mtx_init(&bpinlock, "bpin lock", NULL, MTX_DEF); 533 534 /* next, make a null set of free lists */ 535 for (i = 0; i < BUFFER_QUEUES; i++) 536 TAILQ_INIT(&bufqueues[i]); 537 538 /* finally, initialize each buffer header and stick on empty q */ 539 for (i = 0; i < nbuf; i++) { 540 bp = &buf[i]; 541 bzero(bp, sizeof *bp); 542 bp->b_flags = B_INVAL; /* we're just an empty header */ 543 bp->b_rcred = NOCRED; 544 bp->b_wcred = NOCRED; 545 bp->b_qindex = QUEUE_EMPTY; 546 bp->b_vflags = 0; 547 bp->b_xflags = 0; 548 LIST_INIT(&bp->b_dep); 549 BUF_LOCKINIT(bp); 550 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 551 } 552 553 /* 554 * maxbufspace is the absolute maximum amount of buffer space we are 555 * allowed to reserve in KVM and in real terms. The absolute maximum 556 * is nominally used by buf_daemon. hibufspace is the nominal maximum 557 * used by most other processes. The differential is required to 558 * ensure that buf_daemon is able to run when other processes might 559 * be blocked waiting for buffer space. 560 * 561 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 562 * this may result in KVM fragmentation which is not handled optimally 563 * by the system. 564 */ 565 maxbufspace = nbuf * BKVASIZE; 566 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 567 lobufspace = hibufspace - MAXBSIZE; 568 569 lorunningspace = 512 * 1024; 570 hirunningspace = 1024 * 1024; 571 572 /* 573 * Limit the amount of malloc memory since it is wired permanently into 574 * the kernel space. Even though this is accounted for in the buffer 575 * allocation, we don't want the malloced region to grow uncontrolled. 576 * The malloc scheme improves memory utilization significantly on average 577 * (small) directories. 578 */ 579 maxbufmallocspace = hibufspace / 20; 580 581 /* 582 * Reduce the chance of a deadlock occuring by limiting the number 583 * of delayed-write dirty buffers we allow to stack up. 584 */ 585 hidirtybuffers = nbuf / 4 + 20; 586 dirtybufthresh = hidirtybuffers * 9 / 10; 587 numdirtybuffers = 0; 588 /* 589 * To support extreme low-memory systems, make sure hidirtybuffers cannot 590 * eat up all available buffer space. This occurs when our minimum cannot 591 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 592 * BKVASIZE'd (8K) buffers. 593 */ 594 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 595 hidirtybuffers >>= 1; 596 } 597 lodirtybuffers = hidirtybuffers / 2; 598 599 /* 600 * Try to keep the number of free buffers in the specified range, 601 * and give special processes (e.g. like buf_daemon) access to an 602 * emergency reserve. 603 */ 604 lofreebuffers = nbuf / 18 + 5; 605 hifreebuffers = 2 * lofreebuffers; 606 numfreebuffers = nbuf; 607 608 /* 609 * Maximum number of async ops initiated per buf_daemon loop. This is 610 * somewhat of a hack at the moment, we really need to limit ourselves 611 * based on the number of bytes of I/O in-transit that were initiated 612 * from buf_daemon. 613 */ 614 615 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 616 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 617 } 618 619 /* 620 * bfreekva() - free the kva allocation for a buffer. 621 * 622 * Since this call frees up buffer space, we call bufspacewakeup(). 623 */ 624 static void 625 bfreekva(struct buf *bp) 626 { 627 628 if (bp->b_kvasize) { 629 atomic_add_int(&buffreekvacnt, 1); 630 atomic_subtract_int(&bufspace, bp->b_kvasize); 631 vm_map_lock(buffer_map); 632 vm_map_delete(buffer_map, 633 (vm_offset_t) bp->b_kvabase, 634 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 635 ); 636 vm_map_unlock(buffer_map); 637 bp->b_kvasize = 0; 638 bufspacewakeup(); 639 } 640 } 641 642 /* 643 * bremfree: 644 * 645 * Mark the buffer for removal from the appropriate free list in brelse. 646 * 647 */ 648 void 649 bremfree(struct buf *bp) 650 { 651 652 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 653 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked.")); 654 KASSERT((bp->b_flags & B_REMFREE) == 0, 655 ("bremfree: buffer %p already marked for delayed removal.", bp)); 656 KASSERT(bp->b_qindex != QUEUE_NONE, 657 ("bremfree: buffer %p not on a queue.", bp)); 658 659 bp->b_flags |= B_REMFREE; 660 /* Fixup numfreebuffers count. */ 661 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 662 atomic_subtract_int(&numfreebuffers, 1); 663 } 664 665 /* 666 * bremfreef: 667 * 668 * Force an immediate removal from a free list. Used only in nfs when 669 * it abuses the b_freelist pointer. 670 */ 671 void 672 bremfreef(struct buf *bp) 673 { 674 mtx_lock(&bqlock); 675 bremfreel(bp); 676 mtx_unlock(&bqlock); 677 } 678 679 /* 680 * bremfreel: 681 * 682 * Removes a buffer from the free list, must be called with the 683 * bqlock held. 684 */ 685 static void 686 bremfreel(struct buf *bp) 687 { 688 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 689 bp, bp->b_vp, bp->b_flags); 690 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp)); 691 KASSERT(bp->b_qindex != QUEUE_NONE, 692 ("bremfreel: buffer %p not on a queue.", bp)); 693 mtx_assert(&bqlock, MA_OWNED); 694 695 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 696 bp->b_qindex = QUEUE_NONE; 697 /* 698 * If this was a delayed bremfree() we only need to remove the buffer 699 * from the queue and return the stats are already done. 700 */ 701 if (bp->b_flags & B_REMFREE) { 702 bp->b_flags &= ~B_REMFREE; 703 return; 704 } 705 /* 706 * Fixup numfreebuffers count. If the buffer is invalid or not 707 * delayed-write, the buffer was free and we must decrement 708 * numfreebuffers. 709 */ 710 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 711 atomic_subtract_int(&numfreebuffers, 1); 712 } 713 714 715 /* 716 * Get a buffer with the specified data. Look in the cache first. We 717 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 718 * is set, the buffer is valid and we do not have to do anything ( see 719 * getblk() ). This is really just a special case of breadn(). 720 */ 721 int 722 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 723 struct buf **bpp) 724 { 725 726 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 727 } 728 729 /* 730 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 731 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 732 * the buffer is valid and we do not have to do anything. 733 */ 734 void 735 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 736 int cnt, struct ucred * cred) 737 { 738 struct buf *rabp; 739 int i; 740 741 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 742 if (inmem(vp, *rablkno)) 743 continue; 744 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 745 746 if ((rabp->b_flags & B_CACHE) == 0) { 747 if (curthread != PCPU_GET(idlethread)) 748 curthread->td_proc->p_stats->p_ru.ru_inblock++; 749 rabp->b_flags |= B_ASYNC; 750 rabp->b_flags &= ~B_INVAL; 751 rabp->b_ioflags &= ~BIO_ERROR; 752 rabp->b_iocmd = BIO_READ; 753 if (rabp->b_rcred == NOCRED && cred != NOCRED) 754 rabp->b_rcred = crhold(cred); 755 vfs_busy_pages(rabp, 0); 756 BUF_KERNPROC(rabp); 757 rabp->b_iooffset = dbtob(rabp->b_blkno); 758 bstrategy(rabp); 759 } else { 760 brelse(rabp); 761 } 762 } 763 } 764 765 /* 766 * Operates like bread, but also starts asynchronous I/O on 767 * read-ahead blocks. 768 */ 769 int 770 breadn(struct vnode * vp, daddr_t blkno, int size, 771 daddr_t * rablkno, int *rabsize, 772 int cnt, struct ucred * cred, struct buf **bpp) 773 { 774 struct buf *bp; 775 int rv = 0, readwait = 0; 776 777 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 778 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 779 780 /* if not found in cache, do some I/O */ 781 if ((bp->b_flags & B_CACHE) == 0) { 782 if (curthread != PCPU_GET(idlethread)) 783 curthread->td_proc->p_stats->p_ru.ru_inblock++; 784 bp->b_iocmd = BIO_READ; 785 bp->b_flags &= ~B_INVAL; 786 bp->b_ioflags &= ~BIO_ERROR; 787 if (bp->b_rcred == NOCRED && cred != NOCRED) 788 bp->b_rcred = crhold(cred); 789 vfs_busy_pages(bp, 0); 790 bp->b_iooffset = dbtob(bp->b_blkno); 791 bstrategy(bp); 792 ++readwait; 793 } 794 795 breada(vp, rablkno, rabsize, cnt, cred); 796 797 if (readwait) { 798 rv = bufwait(bp); 799 } 800 return (rv); 801 } 802 803 /* 804 * Write, release buffer on completion. (Done by iodone 805 * if async). Do not bother writing anything if the buffer 806 * is invalid. 807 * 808 * Note that we set B_CACHE here, indicating that buffer is 809 * fully valid and thus cacheable. This is true even of NFS 810 * now so we set it generally. This could be set either here 811 * or in biodone() since the I/O is synchronous. We put it 812 * here. 813 */ 814 int 815 bufwrite(struct buf *bp) 816 { 817 int oldflags; 818 819 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 820 if (bp->b_flags & B_INVAL) { 821 brelse(bp); 822 return (0); 823 } 824 825 oldflags = bp->b_flags; 826 827 if (BUF_REFCNT(bp) == 0) 828 panic("bufwrite: buffer is not busy???"); 829 830 if (bp->b_pin_count > 0) 831 bunpin_wait(bp); 832 833 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 834 ("FFS background buffer should not get here %p", bp)); 835 836 /* Mark the buffer clean */ 837 bundirty(bp); 838 839 bp->b_flags &= ~B_DONE; 840 bp->b_ioflags &= ~BIO_ERROR; 841 bp->b_flags |= B_CACHE; 842 bp->b_iocmd = BIO_WRITE; 843 844 bufobj_wref(bp->b_bufobj); 845 vfs_busy_pages(bp, 1); 846 847 /* 848 * Normal bwrites pipeline writes 849 */ 850 bp->b_runningbufspace = bp->b_bufsize; 851 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 852 853 if (curthread != PCPU_GET(idlethread)) 854 curthread->td_proc->p_stats->p_ru.ru_oublock++; 855 if (oldflags & B_ASYNC) 856 BUF_KERNPROC(bp); 857 bp->b_iooffset = dbtob(bp->b_blkno); 858 bstrategy(bp); 859 860 if ((oldflags & B_ASYNC) == 0) { 861 int rtval = bufwait(bp); 862 brelse(bp); 863 return (rtval); 864 } else { 865 /* 866 * don't allow the async write to saturate the I/O 867 * system. We will not deadlock here because 868 * we are blocking waiting for I/O that is already in-progress 869 * to complete. We do not block here if it is the update 870 * or syncer daemon trying to clean up as that can lead 871 * to deadlock. 872 */ 873 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0) 874 waitrunningbufspace(); 875 } 876 877 return (0); 878 } 879 880 /* 881 * Delayed write. (Buffer is marked dirty). Do not bother writing 882 * anything if the buffer is marked invalid. 883 * 884 * Note that since the buffer must be completely valid, we can safely 885 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 886 * biodone() in order to prevent getblk from writing the buffer 887 * out synchronously. 888 */ 889 void 890 bdwrite(struct buf *bp) 891 { 892 struct thread *td = curthread; 893 struct vnode *vp; 894 struct buf *nbp; 895 struct bufobj *bo; 896 897 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 898 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 899 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy")); 900 901 if (bp->b_flags & B_INVAL) { 902 brelse(bp); 903 return; 904 } 905 906 /* 907 * If we have too many dirty buffers, don't create any more. 908 * If we are wildly over our limit, then force a complete 909 * cleanup. Otherwise, just keep the situation from getting 910 * out of control. Note that we have to avoid a recursive 911 * disaster and not try to clean up after our own cleanup! 912 */ 913 vp = bp->b_vp; 914 bo = bp->b_bufobj; 915 if ((td->td_pflags & TDP_COWINPROGRESS) == 0) { 916 BO_LOCK(bo); 917 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 918 BO_UNLOCK(bo); 919 (void) VOP_FSYNC(vp, MNT_NOWAIT, td); 920 altbufferflushes++; 921 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 922 /* 923 * Try to find a buffer to flush. 924 */ 925 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 926 if ((nbp->b_vflags & BV_BKGRDINPROG) || 927 BUF_LOCK(nbp, 928 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 929 continue; 930 if (bp == nbp) 931 panic("bdwrite: found ourselves"); 932 BO_UNLOCK(bo); 933 /* Don't countdeps with the bo lock held. */ 934 if (buf_countdeps(nbp, 0)) { 935 BO_LOCK(bo); 936 BUF_UNLOCK(nbp); 937 continue; 938 } 939 if (nbp->b_flags & B_CLUSTEROK) { 940 vfs_bio_awrite(nbp); 941 } else { 942 bremfree(nbp); 943 bawrite(nbp); 944 } 945 dirtybufferflushes++; 946 break; 947 } 948 if (nbp == NULL) 949 BO_UNLOCK(bo); 950 } else 951 BO_UNLOCK(bo); 952 } else 953 recursiveflushes++; 954 955 bdirty(bp); 956 /* 957 * Set B_CACHE, indicating that the buffer is fully valid. This is 958 * true even of NFS now. 959 */ 960 bp->b_flags |= B_CACHE; 961 962 /* 963 * This bmap keeps the system from needing to do the bmap later, 964 * perhaps when the system is attempting to do a sync. Since it 965 * is likely that the indirect block -- or whatever other datastructure 966 * that the filesystem needs is still in memory now, it is a good 967 * thing to do this. Note also, that if the pageout daemon is 968 * requesting a sync -- there might not be enough memory to do 969 * the bmap then... So, this is important to do. 970 */ 971 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 972 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 973 } 974 975 /* 976 * Set the *dirty* buffer range based upon the VM system dirty pages. 977 */ 978 vfs_setdirty(bp); 979 980 /* 981 * We need to do this here to satisfy the vnode_pager and the 982 * pageout daemon, so that it thinks that the pages have been 983 * "cleaned". Note that since the pages are in a delayed write 984 * buffer -- the VFS layer "will" see that the pages get written 985 * out on the next sync, or perhaps the cluster will be completed. 986 */ 987 vfs_clean_pages(bp); 988 bqrelse(bp); 989 990 /* 991 * Wakeup the buffer flushing daemon if we have a lot of dirty 992 * buffers (midpoint between our recovery point and our stall 993 * point). 994 */ 995 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 996 997 /* 998 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 999 * due to the softdep code. 1000 */ 1001 } 1002 1003 /* 1004 * bdirty: 1005 * 1006 * Turn buffer into delayed write request. We must clear BIO_READ and 1007 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1008 * itself to properly update it in the dirty/clean lists. We mark it 1009 * B_DONE to ensure that any asynchronization of the buffer properly 1010 * clears B_DONE ( else a panic will occur later ). 1011 * 1012 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1013 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1014 * should only be called if the buffer is known-good. 1015 * 1016 * Since the buffer is not on a queue, we do not update the numfreebuffers 1017 * count. 1018 * 1019 * The buffer must be on QUEUE_NONE. 1020 */ 1021 void 1022 bdirty(struct buf *bp) 1023 { 1024 1025 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1026 bp, bp->b_vp, bp->b_flags); 1027 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp)); 1028 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1029 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1030 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1031 bp->b_flags &= ~(B_RELBUF); 1032 bp->b_iocmd = BIO_WRITE; 1033 1034 if ((bp->b_flags & B_DELWRI) == 0) { 1035 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1036 reassignbuf(bp); 1037 atomic_add_int(&numdirtybuffers, 1); 1038 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1039 } 1040 } 1041 1042 /* 1043 * bundirty: 1044 * 1045 * Clear B_DELWRI for buffer. 1046 * 1047 * Since the buffer is not on a queue, we do not update the numfreebuffers 1048 * count. 1049 * 1050 * The buffer must be on QUEUE_NONE. 1051 */ 1052 1053 void 1054 bundirty(struct buf *bp) 1055 { 1056 1057 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1058 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1059 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1060 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1061 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp)); 1062 1063 if (bp->b_flags & B_DELWRI) { 1064 bp->b_flags &= ~B_DELWRI; 1065 reassignbuf(bp); 1066 atomic_subtract_int(&numdirtybuffers, 1); 1067 numdirtywakeup(lodirtybuffers); 1068 } 1069 /* 1070 * Since it is now being written, we can clear its deferred write flag. 1071 */ 1072 bp->b_flags &= ~B_DEFERRED; 1073 } 1074 1075 /* 1076 * bawrite: 1077 * 1078 * Asynchronous write. Start output on a buffer, but do not wait for 1079 * it to complete. The buffer is released when the output completes. 1080 * 1081 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1082 * B_INVAL buffers. Not us. 1083 */ 1084 void 1085 bawrite(struct buf *bp) 1086 { 1087 1088 bp->b_flags |= B_ASYNC; 1089 (void) bwrite(bp); 1090 } 1091 1092 /* 1093 * bwillwrite: 1094 * 1095 * Called prior to the locking of any vnodes when we are expecting to 1096 * write. We do not want to starve the buffer cache with too many 1097 * dirty buffers so we block here. By blocking prior to the locking 1098 * of any vnodes we attempt to avoid the situation where a locked vnode 1099 * prevents the various system daemons from flushing related buffers. 1100 */ 1101 1102 void 1103 bwillwrite(void) 1104 { 1105 1106 if (numdirtybuffers >= hidirtybuffers) { 1107 mtx_lock(&nblock); 1108 while (numdirtybuffers >= hidirtybuffers) { 1109 bd_wakeup(1); 1110 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1111 msleep(&needsbuffer, &nblock, 1112 (PRIBIO + 4), "flswai", 0); 1113 } 1114 mtx_unlock(&nblock); 1115 } 1116 } 1117 1118 /* 1119 * Return true if we have too many dirty buffers. 1120 */ 1121 int 1122 buf_dirty_count_severe(void) 1123 { 1124 1125 return(numdirtybuffers >= hidirtybuffers); 1126 } 1127 1128 /* 1129 * brelse: 1130 * 1131 * Release a busy buffer and, if requested, free its resources. The 1132 * buffer will be stashed in the appropriate bufqueue[] allowing it 1133 * to be accessed later as a cache entity or reused for other purposes. 1134 */ 1135 void 1136 brelse(struct buf *bp) 1137 { 1138 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1139 bp, bp->b_vp, bp->b_flags); 1140 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1141 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1142 1143 if (bp->b_flags & B_MANAGED) { 1144 bqrelse(bp); 1145 return; 1146 } 1147 1148 if (bp->b_iocmd == BIO_WRITE && 1149 (bp->b_ioflags & BIO_ERROR) && 1150 !(bp->b_flags & B_INVAL)) { 1151 /* 1152 * Failed write, redirty. Must clear BIO_ERROR to prevent 1153 * pages from being scrapped. If B_INVAL is set then 1154 * this case is not run and the next case is run to 1155 * destroy the buffer. B_INVAL can occur if the buffer 1156 * is outside the range supported by the underlying device. 1157 */ 1158 bp->b_ioflags &= ~BIO_ERROR; 1159 bdirty(bp); 1160 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1161 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1162 /* 1163 * Either a failed I/O or we were asked to free or not 1164 * cache the buffer. 1165 */ 1166 bp->b_flags |= B_INVAL; 1167 if (LIST_FIRST(&bp->b_dep) != NULL) 1168 buf_deallocate(bp); 1169 if (bp->b_flags & B_DELWRI) { 1170 atomic_subtract_int(&numdirtybuffers, 1); 1171 numdirtywakeup(lodirtybuffers); 1172 } 1173 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1174 if ((bp->b_flags & B_VMIO) == 0) { 1175 if (bp->b_bufsize) 1176 allocbuf(bp, 0); 1177 if (bp->b_vp) 1178 brelvp(bp); 1179 } 1180 } 1181 1182 /* 1183 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1184 * is called with B_DELWRI set, the underlying pages may wind up 1185 * getting freed causing a previous write (bdwrite()) to get 'lost' 1186 * because pages associated with a B_DELWRI bp are marked clean. 1187 * 1188 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1189 * if B_DELWRI is set. 1190 * 1191 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1192 * on pages to return pages to the VM page queues. 1193 */ 1194 if (bp->b_flags & B_DELWRI) 1195 bp->b_flags &= ~B_RELBUF; 1196 else if (vm_page_count_severe()) { 1197 /* 1198 * XXX This lock may not be necessary since BKGRDINPROG 1199 * cannot be set while we hold the buf lock, it can only be 1200 * cleared if it is already pending. 1201 */ 1202 if (bp->b_vp) { 1203 BO_LOCK(bp->b_bufobj); 1204 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1205 bp->b_flags |= B_RELBUF; 1206 BO_UNLOCK(bp->b_bufobj); 1207 } else 1208 bp->b_flags |= B_RELBUF; 1209 } 1210 1211 /* 1212 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1213 * constituted, not even NFS buffers now. Two flags effect this. If 1214 * B_INVAL, the struct buf is invalidated but the VM object is kept 1215 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1216 * 1217 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1218 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1219 * buffer is also B_INVAL because it hits the re-dirtying code above. 1220 * 1221 * Normally we can do this whether a buffer is B_DELWRI or not. If 1222 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1223 * the commit state and we cannot afford to lose the buffer. If the 1224 * buffer has a background write in progress, we need to keep it 1225 * around to prevent it from being reconstituted and starting a second 1226 * background write. 1227 */ 1228 if ((bp->b_flags & B_VMIO) 1229 && !(bp->b_vp->v_mount != NULL && 1230 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1231 !vn_isdisk(bp->b_vp, NULL) && 1232 (bp->b_flags & B_DELWRI)) 1233 ) { 1234 1235 int i, j, resid; 1236 vm_page_t m; 1237 off_t foff; 1238 vm_pindex_t poff; 1239 vm_object_t obj; 1240 1241 obj = bp->b_bufobj->bo_object; 1242 1243 /* 1244 * Get the base offset and length of the buffer. Note that 1245 * in the VMIO case if the buffer block size is not 1246 * page-aligned then b_data pointer may not be page-aligned. 1247 * But our b_pages[] array *IS* page aligned. 1248 * 1249 * block sizes less then DEV_BSIZE (usually 512) are not 1250 * supported due to the page granularity bits (m->valid, 1251 * m->dirty, etc...). 1252 * 1253 * See man buf(9) for more information 1254 */ 1255 resid = bp->b_bufsize; 1256 foff = bp->b_offset; 1257 VM_OBJECT_LOCK(obj); 1258 for (i = 0; i < bp->b_npages; i++) { 1259 int had_bogus = 0; 1260 1261 m = bp->b_pages[i]; 1262 1263 /* 1264 * If we hit a bogus page, fixup *all* the bogus pages 1265 * now. 1266 */ 1267 if (m == bogus_page) { 1268 poff = OFF_TO_IDX(bp->b_offset); 1269 had_bogus = 1; 1270 1271 for (j = i; j < bp->b_npages; j++) { 1272 vm_page_t mtmp; 1273 mtmp = bp->b_pages[j]; 1274 if (mtmp == bogus_page) { 1275 mtmp = vm_page_lookup(obj, poff + j); 1276 if (!mtmp) { 1277 panic("brelse: page missing\n"); 1278 } 1279 bp->b_pages[j] = mtmp; 1280 } 1281 } 1282 1283 if ((bp->b_flags & B_INVAL) == 0) { 1284 pmap_qenter( 1285 trunc_page((vm_offset_t)bp->b_data), 1286 bp->b_pages, bp->b_npages); 1287 } 1288 m = bp->b_pages[i]; 1289 } 1290 if ((bp->b_flags & B_NOCACHE) || 1291 (bp->b_ioflags & BIO_ERROR)) { 1292 int poffset = foff & PAGE_MASK; 1293 int presid = resid > (PAGE_SIZE - poffset) ? 1294 (PAGE_SIZE - poffset) : resid; 1295 1296 KASSERT(presid >= 0, ("brelse: extra page")); 1297 vm_page_lock_queues(); 1298 vm_page_set_invalid(m, poffset, presid); 1299 vm_page_unlock_queues(); 1300 if (had_bogus) 1301 printf("avoided corruption bug in bogus_page/brelse code\n"); 1302 } 1303 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1304 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1305 } 1306 VM_OBJECT_UNLOCK(obj); 1307 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1308 vfs_vmio_release(bp); 1309 1310 } else if (bp->b_flags & B_VMIO) { 1311 1312 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1313 vfs_vmio_release(bp); 1314 } 1315 1316 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1317 if (bp->b_bufsize != 0) 1318 allocbuf(bp, 0); 1319 if (bp->b_vp != NULL) 1320 brelvp(bp); 1321 } 1322 1323 if (BUF_REFCNT(bp) > 1) { 1324 /* do not release to free list */ 1325 BUF_UNLOCK(bp); 1326 return; 1327 } 1328 1329 /* enqueue */ 1330 mtx_lock(&bqlock); 1331 /* Handle delayed bremfree() processing. */ 1332 if (bp->b_flags & B_REMFREE) 1333 bremfreel(bp); 1334 if (bp->b_qindex != QUEUE_NONE) 1335 panic("brelse: free buffer onto another queue???"); 1336 1337 /* buffers with no memory */ 1338 if (bp->b_bufsize == 0) { 1339 bp->b_flags |= B_INVAL; 1340 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1341 if (bp->b_vflags & BV_BKGRDINPROG) 1342 panic("losing buffer 1"); 1343 if (bp->b_kvasize) { 1344 bp->b_qindex = QUEUE_EMPTYKVA; 1345 } else { 1346 bp->b_qindex = QUEUE_EMPTY; 1347 } 1348 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1349 /* buffers with junk contents */ 1350 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1351 (bp->b_ioflags & BIO_ERROR)) { 1352 bp->b_flags |= B_INVAL; 1353 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1354 if (bp->b_vflags & BV_BKGRDINPROG) 1355 panic("losing buffer 2"); 1356 bp->b_qindex = QUEUE_CLEAN; 1357 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1358 /* remaining buffers */ 1359 } else { 1360 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1361 (B_DELWRI|B_NEEDSGIANT)) 1362 bp->b_qindex = QUEUE_DIRTY_GIANT; 1363 if (bp->b_flags & B_DELWRI) 1364 bp->b_qindex = QUEUE_DIRTY; 1365 else 1366 bp->b_qindex = QUEUE_CLEAN; 1367 if (bp->b_flags & B_AGE) 1368 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1369 else 1370 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1371 } 1372 mtx_unlock(&bqlock); 1373 1374 /* 1375 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1376 * placed the buffer on the correct queue. We must also disassociate 1377 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1378 * find it. 1379 */ 1380 if (bp->b_flags & B_INVAL) { 1381 if (bp->b_flags & B_DELWRI) 1382 bundirty(bp); 1383 if (bp->b_vp) 1384 brelvp(bp); 1385 } 1386 1387 /* 1388 * Fixup numfreebuffers count. The bp is on an appropriate queue 1389 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1390 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1391 * if B_INVAL is set ). 1392 */ 1393 1394 if (!(bp->b_flags & B_DELWRI)) 1395 bufcountwakeup(); 1396 1397 /* 1398 * Something we can maybe free or reuse 1399 */ 1400 if (bp->b_bufsize || bp->b_kvasize) 1401 bufspacewakeup(); 1402 1403 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1404 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1405 panic("brelse: not dirty"); 1406 /* unlock */ 1407 BUF_UNLOCK(bp); 1408 } 1409 1410 /* 1411 * Release a buffer back to the appropriate queue but do not try to free 1412 * it. The buffer is expected to be used again soon. 1413 * 1414 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1415 * biodone() to requeue an async I/O on completion. It is also used when 1416 * known good buffers need to be requeued but we think we may need the data 1417 * again soon. 1418 * 1419 * XXX we should be able to leave the B_RELBUF hint set on completion. 1420 */ 1421 void 1422 bqrelse(struct buf *bp) 1423 { 1424 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1425 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1426 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1427 1428 if (BUF_REFCNT(bp) > 1) { 1429 /* do not release to free list */ 1430 BUF_UNLOCK(bp); 1431 return; 1432 } 1433 1434 if (bp->b_flags & B_MANAGED) { 1435 if (bp->b_flags & B_REMFREE) { 1436 mtx_lock(&bqlock); 1437 bremfreel(bp); 1438 mtx_unlock(&bqlock); 1439 } 1440 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1441 BUF_UNLOCK(bp); 1442 return; 1443 } 1444 1445 mtx_lock(&bqlock); 1446 /* Handle delayed bremfree() processing. */ 1447 if (bp->b_flags & B_REMFREE) 1448 bremfreel(bp); 1449 if (bp->b_qindex != QUEUE_NONE) 1450 panic("bqrelse: free buffer onto another queue???"); 1451 /* buffers with stale but valid contents */ 1452 if (bp->b_flags & B_DELWRI) { 1453 if (bp->b_flags & B_NEEDSGIANT) 1454 bp->b_qindex = QUEUE_DIRTY_GIANT; 1455 else 1456 bp->b_qindex = QUEUE_DIRTY; 1457 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1458 } else { 1459 /* 1460 * XXX This lock may not be necessary since BKGRDINPROG 1461 * cannot be set while we hold the buf lock, it can only be 1462 * cleared if it is already pending. 1463 */ 1464 BO_LOCK(bp->b_bufobj); 1465 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1466 BO_UNLOCK(bp->b_bufobj); 1467 bp->b_qindex = QUEUE_CLEAN; 1468 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1469 b_freelist); 1470 } else { 1471 /* 1472 * We are too low on memory, we have to try to free 1473 * the buffer (most importantly: the wired pages 1474 * making up its backing store) *now*. 1475 */ 1476 BO_UNLOCK(bp->b_bufobj); 1477 mtx_unlock(&bqlock); 1478 brelse(bp); 1479 return; 1480 } 1481 } 1482 mtx_unlock(&bqlock); 1483 1484 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1485 bufcountwakeup(); 1486 1487 /* 1488 * Something we can maybe free or reuse. 1489 */ 1490 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1491 bufspacewakeup(); 1492 1493 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1494 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1495 panic("bqrelse: not dirty"); 1496 /* unlock */ 1497 BUF_UNLOCK(bp); 1498 } 1499 1500 /* Give pages used by the bp back to the VM system (where possible) */ 1501 static void 1502 vfs_vmio_release(struct buf *bp) 1503 { 1504 int i; 1505 vm_page_t m; 1506 1507 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1508 vm_page_lock_queues(); 1509 for (i = 0; i < bp->b_npages; i++) { 1510 m = bp->b_pages[i]; 1511 bp->b_pages[i] = NULL; 1512 /* 1513 * In order to keep page LRU ordering consistent, put 1514 * everything on the inactive queue. 1515 */ 1516 vm_page_unwire(m, 0); 1517 /* 1518 * We don't mess with busy pages, it is 1519 * the responsibility of the process that 1520 * busied the pages to deal with them. 1521 */ 1522 if ((m->flags & PG_BUSY) || (m->busy != 0)) 1523 continue; 1524 1525 if (m->wire_count == 0) { 1526 /* 1527 * Might as well free the page if we can and it has 1528 * no valid data. We also free the page if the 1529 * buffer was used for direct I/O 1530 */ 1531 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1532 m->hold_count == 0) { 1533 vm_page_free(m); 1534 } else if (bp->b_flags & B_DIRECT) { 1535 vm_page_try_to_free(m); 1536 } else if (vm_page_count_severe()) { 1537 vm_page_try_to_cache(m); 1538 } 1539 } 1540 } 1541 vm_page_unlock_queues(); 1542 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1543 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1544 1545 if (bp->b_bufsize) { 1546 bufspacewakeup(); 1547 bp->b_bufsize = 0; 1548 } 1549 bp->b_npages = 0; 1550 bp->b_flags &= ~B_VMIO; 1551 if (bp->b_vp) 1552 brelvp(bp); 1553 } 1554 1555 /* 1556 * Check to see if a block at a particular lbn is available for a clustered 1557 * write. 1558 */ 1559 static int 1560 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1561 { 1562 struct buf *bpa; 1563 int match; 1564 1565 match = 0; 1566 1567 /* If the buf isn't in core skip it */ 1568 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1569 return (0); 1570 1571 /* If the buf is busy we don't want to wait for it */ 1572 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1573 return (0); 1574 1575 /* Only cluster with valid clusterable delayed write buffers */ 1576 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1577 (B_DELWRI | B_CLUSTEROK)) 1578 goto done; 1579 1580 if (bpa->b_bufsize != size) 1581 goto done; 1582 1583 /* 1584 * Check to see if it is in the expected place on disk and that the 1585 * block has been mapped. 1586 */ 1587 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1588 match = 1; 1589 done: 1590 BUF_UNLOCK(bpa); 1591 return (match); 1592 } 1593 1594 /* 1595 * vfs_bio_awrite: 1596 * 1597 * Implement clustered async writes for clearing out B_DELWRI buffers. 1598 * This is much better then the old way of writing only one buffer at 1599 * a time. Note that we may not be presented with the buffers in the 1600 * correct order, so we search for the cluster in both directions. 1601 */ 1602 int 1603 vfs_bio_awrite(struct buf *bp) 1604 { 1605 int i; 1606 int j; 1607 daddr_t lblkno = bp->b_lblkno; 1608 struct vnode *vp = bp->b_vp; 1609 int ncl; 1610 int nwritten; 1611 int size; 1612 int maxcl; 1613 1614 /* 1615 * right now we support clustered writing only to regular files. If 1616 * we find a clusterable block we could be in the middle of a cluster 1617 * rather then at the beginning. 1618 */ 1619 if ((vp->v_type == VREG) && 1620 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1621 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1622 1623 size = vp->v_mount->mnt_stat.f_iosize; 1624 maxcl = MAXPHYS / size; 1625 1626 VI_LOCK(vp); 1627 for (i = 1; i < maxcl; i++) 1628 if (vfs_bio_clcheck(vp, size, lblkno + i, 1629 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1630 break; 1631 1632 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1633 if (vfs_bio_clcheck(vp, size, lblkno - j, 1634 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1635 break; 1636 1637 VI_UNLOCK(vp); 1638 --j; 1639 ncl = i + j; 1640 /* 1641 * this is a possible cluster write 1642 */ 1643 if (ncl != 1) { 1644 BUF_UNLOCK(bp); 1645 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1646 return nwritten; 1647 } 1648 } 1649 bremfree(bp); 1650 bp->b_flags |= B_ASYNC; 1651 /* 1652 * default (old) behavior, writing out only one block 1653 * 1654 * XXX returns b_bufsize instead of b_bcount for nwritten? 1655 */ 1656 nwritten = bp->b_bufsize; 1657 (void) bwrite(bp); 1658 1659 return nwritten; 1660 } 1661 1662 /* 1663 * getnewbuf: 1664 * 1665 * Find and initialize a new buffer header, freeing up existing buffers 1666 * in the bufqueues as necessary. The new buffer is returned locked. 1667 * 1668 * Important: B_INVAL is not set. If the caller wishes to throw the 1669 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1670 * 1671 * We block if: 1672 * We have insufficient buffer headers 1673 * We have insufficient buffer space 1674 * buffer_map is too fragmented ( space reservation fails ) 1675 * If we have to flush dirty buffers ( but we try to avoid this ) 1676 * 1677 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1678 * Instead we ask the buf daemon to do it for us. We attempt to 1679 * avoid piecemeal wakeups of the pageout daemon. 1680 */ 1681 1682 static struct buf * 1683 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1684 { 1685 struct buf *bp; 1686 struct buf *nbp; 1687 int defrag = 0; 1688 int nqindex; 1689 static int flushingbufs; 1690 1691 /* 1692 * We can't afford to block since we might be holding a vnode lock, 1693 * which may prevent system daemons from running. We deal with 1694 * low-memory situations by proactively returning memory and running 1695 * async I/O rather then sync I/O. 1696 */ 1697 1698 atomic_add_int(&getnewbufcalls, 1); 1699 atomic_subtract_int(&getnewbufrestarts, 1); 1700 restart: 1701 atomic_add_int(&getnewbufrestarts, 1); 1702 1703 /* 1704 * Setup for scan. If we do not have enough free buffers, 1705 * we setup a degenerate case that immediately fails. Note 1706 * that if we are specially marked process, we are allowed to 1707 * dip into our reserves. 1708 * 1709 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1710 * 1711 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1712 * However, there are a number of cases (defragging, reusing, ...) 1713 * where we cannot backup. 1714 */ 1715 mtx_lock(&bqlock); 1716 nqindex = QUEUE_EMPTYKVA; 1717 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1718 1719 if (nbp == NULL) { 1720 /* 1721 * If no EMPTYKVA buffers and we are either 1722 * defragging or reusing, locate a CLEAN buffer 1723 * to free or reuse. If bufspace useage is low 1724 * skip this step so we can allocate a new buffer. 1725 */ 1726 if (defrag || bufspace >= lobufspace) { 1727 nqindex = QUEUE_CLEAN; 1728 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1729 } 1730 1731 /* 1732 * If we could not find or were not allowed to reuse a 1733 * CLEAN buffer, check to see if it is ok to use an EMPTY 1734 * buffer. We can only use an EMPTY buffer if allocating 1735 * its KVA would not otherwise run us out of buffer space. 1736 */ 1737 if (nbp == NULL && defrag == 0 && 1738 bufspace + maxsize < hibufspace) { 1739 nqindex = QUEUE_EMPTY; 1740 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1741 } 1742 } 1743 1744 /* 1745 * Run scan, possibly freeing data and/or kva mappings on the fly 1746 * depending. 1747 */ 1748 1749 while ((bp = nbp) != NULL) { 1750 int qindex = nqindex; 1751 1752 /* 1753 * Calculate next bp ( we can only use it if we do not block 1754 * or do other fancy things ). 1755 */ 1756 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1757 switch(qindex) { 1758 case QUEUE_EMPTY: 1759 nqindex = QUEUE_EMPTYKVA; 1760 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1761 break; 1762 /* FALLTHROUGH */ 1763 case QUEUE_EMPTYKVA: 1764 nqindex = QUEUE_CLEAN; 1765 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1766 break; 1767 /* FALLTHROUGH */ 1768 case QUEUE_CLEAN: 1769 /* 1770 * nbp is NULL. 1771 */ 1772 break; 1773 } 1774 } 1775 /* 1776 * If we are defragging then we need a buffer with 1777 * b_kvasize != 0. XXX this situation should no longer 1778 * occur, if defrag is non-zero the buffer's b_kvasize 1779 * should also be non-zero at this point. XXX 1780 */ 1781 if (defrag && bp->b_kvasize == 0) { 1782 printf("Warning: defrag empty buffer %p\n", bp); 1783 continue; 1784 } 1785 1786 /* 1787 * Start freeing the bp. This is somewhat involved. nbp 1788 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1789 */ 1790 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1791 continue; 1792 if (bp->b_vp) { 1793 BO_LOCK(bp->b_bufobj); 1794 if (bp->b_vflags & BV_BKGRDINPROG) { 1795 BO_UNLOCK(bp->b_bufobj); 1796 BUF_UNLOCK(bp); 1797 continue; 1798 } 1799 BO_UNLOCK(bp->b_bufobj); 1800 } 1801 CTR6(KTR_BUF, 1802 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1803 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1804 bp->b_kvasize, bp->b_bufsize, qindex); 1805 1806 /* 1807 * Sanity Checks 1808 */ 1809 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1810 1811 /* 1812 * Note: we no longer distinguish between VMIO and non-VMIO 1813 * buffers. 1814 */ 1815 1816 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1817 1818 bremfreel(bp); 1819 mtx_unlock(&bqlock); 1820 1821 if (qindex == QUEUE_CLEAN) { 1822 if (bp->b_flags & B_VMIO) { 1823 bp->b_flags &= ~B_ASYNC; 1824 vfs_vmio_release(bp); 1825 } 1826 if (bp->b_vp) 1827 brelvp(bp); 1828 } 1829 1830 /* 1831 * NOTE: nbp is now entirely invalid. We can only restart 1832 * the scan from this point on. 1833 * 1834 * Get the rest of the buffer freed up. b_kva* is still 1835 * valid after this operation. 1836 */ 1837 1838 if (bp->b_rcred != NOCRED) { 1839 crfree(bp->b_rcred); 1840 bp->b_rcred = NOCRED; 1841 } 1842 if (bp->b_wcred != NOCRED) { 1843 crfree(bp->b_wcred); 1844 bp->b_wcred = NOCRED; 1845 } 1846 if (LIST_FIRST(&bp->b_dep) != NULL) 1847 buf_deallocate(bp); 1848 if (bp->b_vflags & BV_BKGRDINPROG) 1849 panic("losing buffer 3"); 1850 KASSERT(bp->b_vp == NULL, 1851 ("bp: %p still has vnode %p. qindex: %d", 1852 bp, bp->b_vp, qindex)); 1853 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1854 ("bp: %p still on a buffer list. xflags %X", 1855 bp, bp->b_xflags)); 1856 1857 if (bp->b_bufsize) 1858 allocbuf(bp, 0); 1859 1860 bp->b_flags = 0; 1861 bp->b_ioflags = 0; 1862 bp->b_xflags = 0; 1863 bp->b_vflags = 0; 1864 bp->b_vp = NULL; 1865 bp->b_blkno = bp->b_lblkno = 0; 1866 bp->b_offset = NOOFFSET; 1867 bp->b_iodone = 0; 1868 bp->b_error = 0; 1869 bp->b_resid = 0; 1870 bp->b_bcount = 0; 1871 bp->b_npages = 0; 1872 bp->b_dirtyoff = bp->b_dirtyend = 0; 1873 bp->b_bufobj = NULL; 1874 bp->b_pin_count = 0; 1875 bp->b_fsprivate1 = NULL; 1876 bp->b_fsprivate2 = NULL; 1877 bp->b_fsprivate3 = NULL; 1878 1879 LIST_INIT(&bp->b_dep); 1880 1881 /* 1882 * If we are defragging then free the buffer. 1883 */ 1884 if (defrag) { 1885 bp->b_flags |= B_INVAL; 1886 bfreekva(bp); 1887 brelse(bp); 1888 defrag = 0; 1889 goto restart; 1890 } 1891 1892 /* 1893 * Notify any waiters for the buffer lock about 1894 * identity change by freeing the buffer. 1895 */ 1896 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) { 1897 bp->b_flags |= B_INVAL; 1898 bfreekva(bp); 1899 brelse(bp); 1900 goto restart; 1901 } 1902 1903 /* 1904 * If we are overcomitted then recover the buffer and its 1905 * KVM space. This occurs in rare situations when multiple 1906 * processes are blocked in getnewbuf() or allocbuf(). 1907 */ 1908 if (bufspace >= hibufspace) 1909 flushingbufs = 1; 1910 if (flushingbufs && bp->b_kvasize != 0) { 1911 bp->b_flags |= B_INVAL; 1912 bfreekva(bp); 1913 brelse(bp); 1914 goto restart; 1915 } 1916 if (bufspace < lobufspace) 1917 flushingbufs = 0; 1918 break; 1919 } 1920 1921 /* 1922 * If we exhausted our list, sleep as appropriate. We may have to 1923 * wakeup various daemons and write out some dirty buffers. 1924 * 1925 * Generally we are sleeping due to insufficient buffer space. 1926 */ 1927 1928 if (bp == NULL) { 1929 int flags; 1930 char *waitmsg; 1931 1932 if (defrag) { 1933 flags = VFS_BIO_NEED_BUFSPACE; 1934 waitmsg = "nbufkv"; 1935 } else if (bufspace >= hibufspace) { 1936 waitmsg = "nbufbs"; 1937 flags = VFS_BIO_NEED_BUFSPACE; 1938 } else { 1939 waitmsg = "newbuf"; 1940 flags = VFS_BIO_NEED_ANY; 1941 } 1942 mtx_lock(&nblock); 1943 needsbuffer |= flags; 1944 mtx_unlock(&nblock); 1945 mtx_unlock(&bqlock); 1946 1947 bd_speedup(); /* heeeelp */ 1948 1949 mtx_lock(&nblock); 1950 while (needsbuffer & flags) { 1951 if (msleep(&needsbuffer, &nblock, 1952 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1953 mtx_unlock(&nblock); 1954 return (NULL); 1955 } 1956 } 1957 mtx_unlock(&nblock); 1958 } else { 1959 /* 1960 * We finally have a valid bp. We aren't quite out of the 1961 * woods, we still have to reserve kva space. In order 1962 * to keep fragmentation sane we only allocate kva in 1963 * BKVASIZE chunks. 1964 */ 1965 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1966 1967 if (maxsize != bp->b_kvasize) { 1968 vm_offset_t addr = 0; 1969 1970 bfreekva(bp); 1971 1972 vm_map_lock(buffer_map); 1973 if (vm_map_findspace(buffer_map, 1974 vm_map_min(buffer_map), maxsize, &addr)) { 1975 /* 1976 * Uh oh. Buffer map is to fragmented. We 1977 * must defragment the map. 1978 */ 1979 atomic_add_int(&bufdefragcnt, 1); 1980 vm_map_unlock(buffer_map); 1981 defrag = 1; 1982 bp->b_flags |= B_INVAL; 1983 brelse(bp); 1984 goto restart; 1985 } 1986 if (addr) { 1987 vm_map_insert(buffer_map, NULL, 0, 1988 addr, addr + maxsize, 1989 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1990 1991 bp->b_kvabase = (caddr_t) addr; 1992 bp->b_kvasize = maxsize; 1993 atomic_add_int(&bufspace, bp->b_kvasize); 1994 atomic_add_int(&bufreusecnt, 1); 1995 } 1996 vm_map_unlock(buffer_map); 1997 } 1998 bp->b_saveaddr = bp->b_kvabase; 1999 bp->b_data = bp->b_saveaddr; 2000 } 2001 return(bp); 2002 } 2003 2004 /* 2005 * buf_daemon: 2006 * 2007 * buffer flushing daemon. Buffers are normally flushed by the 2008 * update daemon but if it cannot keep up this process starts to 2009 * take the load in an attempt to prevent getnewbuf() from blocking. 2010 */ 2011 2012 static struct kproc_desc buf_kp = { 2013 "bufdaemon", 2014 buf_daemon, 2015 &bufdaemonproc 2016 }; 2017 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2018 2019 static void 2020 buf_daemon() 2021 { 2022 2023 /* 2024 * This process needs to be suspended prior to shutdown sync. 2025 */ 2026 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2027 SHUTDOWN_PRI_LAST); 2028 2029 /* 2030 * This process is allowed to take the buffer cache to the limit 2031 */ 2032 curthread->td_pflags |= TDP_NORUNNINGBUF; 2033 mtx_lock(&bdlock); 2034 for (;;) { 2035 bd_request = 0; 2036 mtx_unlock(&bdlock); 2037 2038 kthread_suspend_check(bufdaemonproc); 2039 2040 /* 2041 * Do the flush. Limit the amount of in-transit I/O we 2042 * allow to build up, otherwise we would completely saturate 2043 * the I/O system. Wakeup any waiting processes before we 2044 * normally would so they can run in parallel with our drain. 2045 */ 2046 while (numdirtybuffers > lodirtybuffers) { 2047 int flushed; 2048 2049 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2050 /* The list empty check here is slightly racy */ 2051 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2052 mtx_lock(&Giant); 2053 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2054 mtx_unlock(&Giant); 2055 } 2056 if (flushed == 0) { 2057 /* 2058 * Could not find any buffers without rollback 2059 * dependencies, so just write the first one 2060 * in the hopes of eventually making progress. 2061 */ 2062 flushbufqueues(QUEUE_DIRTY, 1); 2063 if (!TAILQ_EMPTY( 2064 &bufqueues[QUEUE_DIRTY_GIANT])) { 2065 mtx_lock(&Giant); 2066 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2067 mtx_unlock(&Giant); 2068 } 2069 break; 2070 } 2071 uio_yield(); 2072 } 2073 2074 /* 2075 * Only clear bd_request if we have reached our low water 2076 * mark. The buf_daemon normally waits 1 second and 2077 * then incrementally flushes any dirty buffers that have 2078 * built up, within reason. 2079 * 2080 * If we were unable to hit our low water mark and couldn't 2081 * find any flushable buffers, we sleep half a second. 2082 * Otherwise we loop immediately. 2083 */ 2084 mtx_lock(&bdlock); 2085 if (numdirtybuffers <= lodirtybuffers) { 2086 /* 2087 * We reached our low water mark, reset the 2088 * request and sleep until we are needed again. 2089 * The sleep is just so the suspend code works. 2090 */ 2091 bd_request = 0; 2092 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2093 } else { 2094 /* 2095 * We couldn't find any flushable dirty buffers but 2096 * still have too many dirty buffers, we 2097 * have to sleep and try again. (rare) 2098 */ 2099 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2100 } 2101 } 2102 } 2103 2104 /* 2105 * flushbufqueues: 2106 * 2107 * Try to flush a buffer in the dirty queue. We must be careful to 2108 * free up B_INVAL buffers instead of write them, which NFS is 2109 * particularly sensitive to. 2110 */ 2111 static int flushwithdeps = 0; 2112 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2113 0, "Number of buffers flushed with dependecies that require rollbacks"); 2114 2115 static int 2116 flushbufqueues(int queue, int flushdeps) 2117 { 2118 struct thread *td = curthread; 2119 struct buf sentinel; 2120 struct vnode *vp; 2121 struct mount *mp; 2122 struct buf *bp; 2123 int hasdeps; 2124 int flushed; 2125 int target; 2126 2127 target = numdirtybuffers - lodirtybuffers; 2128 if (flushdeps && target > 2) 2129 target /= 2; 2130 flushed = 0; 2131 bp = NULL; 2132 mtx_lock(&bqlock); 2133 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2134 while (flushed != target) { 2135 bp = TAILQ_FIRST(&bufqueues[queue]); 2136 if (bp == &sentinel) 2137 break; 2138 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2139 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2140 2141 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2142 continue; 2143 if (bp->b_pin_count > 0) { 2144 BUF_UNLOCK(bp); 2145 continue; 2146 } 2147 BO_LOCK(bp->b_bufobj); 2148 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2149 (bp->b_flags & B_DELWRI) == 0) { 2150 BO_UNLOCK(bp->b_bufobj); 2151 BUF_UNLOCK(bp); 2152 continue; 2153 } 2154 BO_UNLOCK(bp->b_bufobj); 2155 if (bp->b_flags & B_INVAL) { 2156 bremfreel(bp); 2157 mtx_unlock(&bqlock); 2158 brelse(bp); 2159 flushed++; 2160 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2161 mtx_lock(&bqlock); 2162 continue; 2163 } 2164 2165 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2166 if (flushdeps == 0) { 2167 BUF_UNLOCK(bp); 2168 continue; 2169 } 2170 hasdeps = 1; 2171 } else 2172 hasdeps = 0; 2173 /* 2174 * We must hold the lock on a vnode before writing 2175 * one of its buffers. Otherwise we may confuse, or 2176 * in the case of a snapshot vnode, deadlock the 2177 * system. 2178 * 2179 * The lock order here is the reverse of the normal 2180 * of vnode followed by buf lock. This is ok because 2181 * the NOWAIT will prevent deadlock. 2182 */ 2183 vp = bp->b_vp; 2184 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2185 BUF_UNLOCK(bp); 2186 continue; 2187 } 2188 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2189 mtx_unlock(&bqlock); 2190 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2191 bp, bp->b_vp, bp->b_flags); 2192 vfs_bio_awrite(bp); 2193 vn_finished_write(mp); 2194 VOP_UNLOCK(vp, 0, td); 2195 flushwithdeps += hasdeps; 2196 flushed++; 2197 waitrunningbufspace(); 2198 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2199 mtx_lock(&bqlock); 2200 continue; 2201 } 2202 vn_finished_write(mp); 2203 BUF_UNLOCK(bp); 2204 } 2205 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2206 mtx_unlock(&bqlock); 2207 return (flushed); 2208 } 2209 2210 /* 2211 * Check to see if a block is currently memory resident. 2212 */ 2213 struct buf * 2214 incore(struct bufobj *bo, daddr_t blkno) 2215 { 2216 struct buf *bp; 2217 2218 BO_LOCK(bo); 2219 bp = gbincore(bo, blkno); 2220 BO_UNLOCK(bo); 2221 return (bp); 2222 } 2223 2224 /* 2225 * Returns true if no I/O is needed to access the 2226 * associated VM object. This is like incore except 2227 * it also hunts around in the VM system for the data. 2228 */ 2229 2230 static int 2231 inmem(struct vnode * vp, daddr_t blkno) 2232 { 2233 vm_object_t obj; 2234 vm_offset_t toff, tinc, size; 2235 vm_page_t m; 2236 vm_ooffset_t off; 2237 2238 ASSERT_VOP_LOCKED(vp, "inmem"); 2239 2240 if (incore(&vp->v_bufobj, blkno)) 2241 return 1; 2242 if (vp->v_mount == NULL) 2243 return 0; 2244 obj = vp->v_object; 2245 if (obj == NULL) 2246 return (0); 2247 2248 size = PAGE_SIZE; 2249 if (size > vp->v_mount->mnt_stat.f_iosize) 2250 size = vp->v_mount->mnt_stat.f_iosize; 2251 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2252 2253 VM_OBJECT_LOCK(obj); 2254 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2255 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2256 if (!m) 2257 goto notinmem; 2258 tinc = size; 2259 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2260 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2261 if (vm_page_is_valid(m, 2262 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2263 goto notinmem; 2264 } 2265 VM_OBJECT_UNLOCK(obj); 2266 return 1; 2267 2268 notinmem: 2269 VM_OBJECT_UNLOCK(obj); 2270 return (0); 2271 } 2272 2273 /* 2274 * vfs_setdirty: 2275 * 2276 * Sets the dirty range for a buffer based on the status of the dirty 2277 * bits in the pages comprising the buffer. 2278 * 2279 * The range is limited to the size of the buffer. 2280 * 2281 * This routine is primarily used by NFS, but is generalized for the 2282 * B_VMIO case. 2283 */ 2284 static void 2285 vfs_setdirty(struct buf *bp) 2286 { 2287 int i; 2288 vm_object_t object; 2289 2290 /* 2291 * Degenerate case - empty buffer 2292 */ 2293 2294 if (bp->b_bufsize == 0) 2295 return; 2296 2297 /* 2298 * We qualify the scan for modified pages on whether the 2299 * object has been flushed yet. 2300 */ 2301 2302 if ((bp->b_flags & B_VMIO) == 0) 2303 return; 2304 2305 object = bp->b_pages[0]->object; 2306 VM_OBJECT_LOCK(object); 2307 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2308 vm_offset_t boffset; 2309 vm_offset_t eoffset; 2310 2311 vm_page_lock_queues(); 2312 /* 2313 * test the pages to see if they have been modified directly 2314 * by users through the VM system. 2315 */ 2316 for (i = 0; i < bp->b_npages; i++) 2317 vm_page_test_dirty(bp->b_pages[i]); 2318 2319 /* 2320 * Calculate the encompassing dirty range, boffset and eoffset, 2321 * (eoffset - boffset) bytes. 2322 */ 2323 2324 for (i = 0; i < bp->b_npages; i++) { 2325 if (bp->b_pages[i]->dirty) 2326 break; 2327 } 2328 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2329 2330 for (i = bp->b_npages - 1; i >= 0; --i) { 2331 if (bp->b_pages[i]->dirty) { 2332 break; 2333 } 2334 } 2335 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2336 2337 vm_page_unlock_queues(); 2338 /* 2339 * Fit it to the buffer. 2340 */ 2341 2342 if (eoffset > bp->b_bcount) 2343 eoffset = bp->b_bcount; 2344 2345 /* 2346 * If we have a good dirty range, merge with the existing 2347 * dirty range. 2348 */ 2349 2350 if (boffset < eoffset) { 2351 if (bp->b_dirtyoff > boffset) 2352 bp->b_dirtyoff = boffset; 2353 if (bp->b_dirtyend < eoffset) 2354 bp->b_dirtyend = eoffset; 2355 } 2356 } 2357 VM_OBJECT_UNLOCK(object); 2358 } 2359 2360 /* 2361 * getblk: 2362 * 2363 * Get a block given a specified block and offset into a file/device. 2364 * The buffers B_DONE bit will be cleared on return, making it almost 2365 * ready for an I/O initiation. B_INVAL may or may not be set on 2366 * return. The caller should clear B_INVAL prior to initiating a 2367 * READ. 2368 * 2369 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2370 * an existing buffer. 2371 * 2372 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2373 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2374 * and then cleared based on the backing VM. If the previous buffer is 2375 * non-0-sized but invalid, B_CACHE will be cleared. 2376 * 2377 * If getblk() must create a new buffer, the new buffer is returned with 2378 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2379 * case it is returned with B_INVAL clear and B_CACHE set based on the 2380 * backing VM. 2381 * 2382 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2383 * B_CACHE bit is clear. 2384 * 2385 * What this means, basically, is that the caller should use B_CACHE to 2386 * determine whether the buffer is fully valid or not and should clear 2387 * B_INVAL prior to issuing a read. If the caller intends to validate 2388 * the buffer by loading its data area with something, the caller needs 2389 * to clear B_INVAL. If the caller does this without issuing an I/O, 2390 * the caller should set B_CACHE ( as an optimization ), else the caller 2391 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2392 * a write attempt or if it was a successfull read. If the caller 2393 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2394 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2395 */ 2396 struct buf * 2397 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2398 int flags) 2399 { 2400 struct buf *bp; 2401 struct bufobj *bo; 2402 int error; 2403 2404 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2405 ASSERT_VOP_LOCKED(vp, "getblk"); 2406 if (size > MAXBSIZE) 2407 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2408 2409 bo = &vp->v_bufobj; 2410 loop: 2411 /* 2412 * Block if we are low on buffers. Certain processes are allowed 2413 * to completely exhaust the buffer cache. 2414 * 2415 * If this check ever becomes a bottleneck it may be better to 2416 * move it into the else, when gbincore() fails. At the moment 2417 * it isn't a problem. 2418 * 2419 * XXX remove if 0 sections (clean this up after its proven) 2420 */ 2421 if (numfreebuffers == 0) { 2422 if (curthread == PCPU_GET(idlethread)) 2423 return NULL; 2424 mtx_lock(&nblock); 2425 needsbuffer |= VFS_BIO_NEED_ANY; 2426 mtx_unlock(&nblock); 2427 } 2428 2429 VI_LOCK(vp); 2430 bp = gbincore(bo, blkno); 2431 if (bp != NULL) { 2432 int lockflags; 2433 /* 2434 * Buffer is in-core. If the buffer is not busy, it must 2435 * be on a queue. 2436 */ 2437 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2438 2439 if (flags & GB_LOCK_NOWAIT) 2440 lockflags |= LK_NOWAIT; 2441 2442 error = BUF_TIMELOCK(bp, lockflags, 2443 VI_MTX(vp), "getblk", slpflag, slptimeo); 2444 2445 /* 2446 * If we slept and got the lock we have to restart in case 2447 * the buffer changed identities. 2448 */ 2449 if (error == ENOLCK) 2450 goto loop; 2451 /* We timed out or were interrupted. */ 2452 else if (error) 2453 return (NULL); 2454 2455 /* 2456 * The buffer is locked. B_CACHE is cleared if the buffer is 2457 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2458 * and for a VMIO buffer B_CACHE is adjusted according to the 2459 * backing VM cache. 2460 */ 2461 if (bp->b_flags & B_INVAL) 2462 bp->b_flags &= ~B_CACHE; 2463 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2464 bp->b_flags |= B_CACHE; 2465 bremfree(bp); 2466 2467 /* 2468 * check for size inconsistancies for non-VMIO case. 2469 */ 2470 2471 if (bp->b_bcount != size) { 2472 if ((bp->b_flags & B_VMIO) == 0 || 2473 (size > bp->b_kvasize)) { 2474 if (bp->b_flags & B_DELWRI) { 2475 /* 2476 * If buffer is pinned and caller does 2477 * not want sleep waiting for it to be 2478 * unpinned, bail out 2479 * */ 2480 if (bp->b_pin_count > 0) { 2481 if (flags & GB_LOCK_NOWAIT) { 2482 bqrelse(bp); 2483 return (NULL); 2484 } else { 2485 bunpin_wait(bp); 2486 } 2487 } 2488 bp->b_flags |= B_NOCACHE; 2489 bwrite(bp); 2490 } else { 2491 if (LIST_FIRST(&bp->b_dep) == NULL) { 2492 bp->b_flags |= B_RELBUF; 2493 brelse(bp); 2494 } else { 2495 bp->b_flags |= B_NOCACHE; 2496 bwrite(bp); 2497 } 2498 } 2499 goto loop; 2500 } 2501 } 2502 2503 /* 2504 * If the size is inconsistant in the VMIO case, we can resize 2505 * the buffer. This might lead to B_CACHE getting set or 2506 * cleared. If the size has not changed, B_CACHE remains 2507 * unchanged from its previous state. 2508 */ 2509 2510 if (bp->b_bcount != size) 2511 allocbuf(bp, size); 2512 2513 KASSERT(bp->b_offset != NOOFFSET, 2514 ("getblk: no buffer offset")); 2515 2516 /* 2517 * A buffer with B_DELWRI set and B_CACHE clear must 2518 * be committed before we can return the buffer in 2519 * order to prevent the caller from issuing a read 2520 * ( due to B_CACHE not being set ) and overwriting 2521 * it. 2522 * 2523 * Most callers, including NFS and FFS, need this to 2524 * operate properly either because they assume they 2525 * can issue a read if B_CACHE is not set, or because 2526 * ( for example ) an uncached B_DELWRI might loop due 2527 * to softupdates re-dirtying the buffer. In the latter 2528 * case, B_CACHE is set after the first write completes, 2529 * preventing further loops. 2530 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2531 * above while extending the buffer, we cannot allow the 2532 * buffer to remain with B_CACHE set after the write 2533 * completes or it will represent a corrupt state. To 2534 * deal with this we set B_NOCACHE to scrap the buffer 2535 * after the write. 2536 * 2537 * We might be able to do something fancy, like setting 2538 * B_CACHE in bwrite() except if B_DELWRI is already set, 2539 * so the below call doesn't set B_CACHE, but that gets real 2540 * confusing. This is much easier. 2541 */ 2542 2543 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2544 bp->b_flags |= B_NOCACHE; 2545 bwrite(bp); 2546 goto loop; 2547 } 2548 bp->b_flags &= ~B_DONE; 2549 } else { 2550 int bsize, maxsize, vmio; 2551 off_t offset; 2552 2553 /* 2554 * Buffer is not in-core, create new buffer. The buffer 2555 * returned by getnewbuf() is locked. Note that the returned 2556 * buffer is also considered valid (not marked B_INVAL). 2557 */ 2558 VI_UNLOCK(vp); 2559 /* 2560 * If the user does not want us to create the buffer, bail out 2561 * here. 2562 */ 2563 if (flags & GB_NOCREAT) 2564 return NULL; 2565 bsize = bo->bo_bsize; 2566 offset = blkno * bsize; 2567 vmio = vp->v_object != NULL; 2568 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2569 maxsize = imax(maxsize, bsize); 2570 2571 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2572 if (bp == NULL) { 2573 if (slpflag || slptimeo) 2574 return NULL; 2575 goto loop; 2576 } 2577 2578 /* 2579 * This code is used to make sure that a buffer is not 2580 * created while the getnewbuf routine is blocked. 2581 * This can be a problem whether the vnode is locked or not. 2582 * If the buffer is created out from under us, we have to 2583 * throw away the one we just created. 2584 * 2585 * Note: this must occur before we associate the buffer 2586 * with the vp especially considering limitations in 2587 * the splay tree implementation when dealing with duplicate 2588 * lblkno's. 2589 */ 2590 BO_LOCK(bo); 2591 if (gbincore(bo, blkno)) { 2592 BO_UNLOCK(bo); 2593 bp->b_flags |= B_INVAL; 2594 brelse(bp); 2595 goto loop; 2596 } 2597 2598 /* 2599 * Insert the buffer into the hash, so that it can 2600 * be found by incore. 2601 */ 2602 bp->b_blkno = bp->b_lblkno = blkno; 2603 bp->b_offset = offset; 2604 bgetvp(vp, bp); 2605 BO_UNLOCK(bo); 2606 2607 /* 2608 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2609 * buffer size starts out as 0, B_CACHE will be set by 2610 * allocbuf() for the VMIO case prior to it testing the 2611 * backing store for validity. 2612 */ 2613 2614 if (vmio) { 2615 bp->b_flags |= B_VMIO; 2616 #if defined(VFS_BIO_DEBUG) 2617 if (vn_canvmio(vp) != TRUE) 2618 printf("getblk: VMIO on vnode type %d\n", 2619 vp->v_type); 2620 #endif 2621 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2622 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2623 bp, vp->v_object, bp->b_bufobj->bo_object)); 2624 } else { 2625 bp->b_flags &= ~B_VMIO; 2626 KASSERT(bp->b_bufobj->bo_object == NULL, 2627 ("ARGH! has b_bufobj->bo_object %p %p\n", 2628 bp, bp->b_bufobj->bo_object)); 2629 } 2630 2631 allocbuf(bp, size); 2632 bp->b_flags &= ~B_DONE; 2633 } 2634 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2635 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2636 KASSERT(bp->b_bufobj == bo, 2637 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2638 return (bp); 2639 } 2640 2641 /* 2642 * Get an empty, disassociated buffer of given size. The buffer is initially 2643 * set to B_INVAL. 2644 */ 2645 struct buf * 2646 geteblk(int size) 2647 { 2648 struct buf *bp; 2649 int maxsize; 2650 2651 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2652 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2653 continue; 2654 allocbuf(bp, size); 2655 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2656 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2657 return (bp); 2658 } 2659 2660 2661 /* 2662 * This code constitutes the buffer memory from either anonymous system 2663 * memory (in the case of non-VMIO operations) or from an associated 2664 * VM object (in the case of VMIO operations). This code is able to 2665 * resize a buffer up or down. 2666 * 2667 * Note that this code is tricky, and has many complications to resolve 2668 * deadlock or inconsistant data situations. Tread lightly!!! 2669 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2670 * the caller. Calling this code willy nilly can result in the loss of data. 2671 * 2672 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2673 * B_CACHE for the non-VMIO case. 2674 */ 2675 2676 int 2677 allocbuf(struct buf *bp, int size) 2678 { 2679 int newbsize, mbsize; 2680 int i; 2681 2682 if (BUF_REFCNT(bp) == 0) 2683 panic("allocbuf: buffer not busy"); 2684 2685 if (bp->b_kvasize < size) 2686 panic("allocbuf: buffer too small"); 2687 2688 if ((bp->b_flags & B_VMIO) == 0) { 2689 caddr_t origbuf; 2690 int origbufsize; 2691 /* 2692 * Just get anonymous memory from the kernel. Don't 2693 * mess with B_CACHE. 2694 */ 2695 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2696 if (bp->b_flags & B_MALLOC) 2697 newbsize = mbsize; 2698 else 2699 newbsize = round_page(size); 2700 2701 if (newbsize < bp->b_bufsize) { 2702 /* 2703 * malloced buffers are not shrunk 2704 */ 2705 if (bp->b_flags & B_MALLOC) { 2706 if (newbsize) { 2707 bp->b_bcount = size; 2708 } else { 2709 free(bp->b_data, M_BIOBUF); 2710 if (bp->b_bufsize) { 2711 atomic_subtract_int( 2712 &bufmallocspace, 2713 bp->b_bufsize); 2714 bufspacewakeup(); 2715 bp->b_bufsize = 0; 2716 } 2717 bp->b_saveaddr = bp->b_kvabase; 2718 bp->b_data = bp->b_saveaddr; 2719 bp->b_bcount = 0; 2720 bp->b_flags &= ~B_MALLOC; 2721 } 2722 return 1; 2723 } 2724 vm_hold_free_pages( 2725 bp, 2726 (vm_offset_t) bp->b_data + newbsize, 2727 (vm_offset_t) bp->b_data + bp->b_bufsize); 2728 } else if (newbsize > bp->b_bufsize) { 2729 /* 2730 * We only use malloced memory on the first allocation. 2731 * and revert to page-allocated memory when the buffer 2732 * grows. 2733 */ 2734 /* 2735 * There is a potential smp race here that could lead 2736 * to bufmallocspace slightly passing the max. It 2737 * is probably extremely rare and not worth worrying 2738 * over. 2739 */ 2740 if ( (bufmallocspace < maxbufmallocspace) && 2741 (bp->b_bufsize == 0) && 2742 (mbsize <= PAGE_SIZE/2)) { 2743 2744 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2745 bp->b_bufsize = mbsize; 2746 bp->b_bcount = size; 2747 bp->b_flags |= B_MALLOC; 2748 atomic_add_int(&bufmallocspace, mbsize); 2749 return 1; 2750 } 2751 origbuf = NULL; 2752 origbufsize = 0; 2753 /* 2754 * If the buffer is growing on its other-than-first allocation, 2755 * then we revert to the page-allocation scheme. 2756 */ 2757 if (bp->b_flags & B_MALLOC) { 2758 origbuf = bp->b_data; 2759 origbufsize = bp->b_bufsize; 2760 bp->b_data = bp->b_kvabase; 2761 if (bp->b_bufsize) { 2762 atomic_subtract_int(&bufmallocspace, 2763 bp->b_bufsize); 2764 bufspacewakeup(); 2765 bp->b_bufsize = 0; 2766 } 2767 bp->b_flags &= ~B_MALLOC; 2768 newbsize = round_page(newbsize); 2769 } 2770 vm_hold_load_pages( 2771 bp, 2772 (vm_offset_t) bp->b_data + bp->b_bufsize, 2773 (vm_offset_t) bp->b_data + newbsize); 2774 if (origbuf) { 2775 bcopy(origbuf, bp->b_data, origbufsize); 2776 free(origbuf, M_BIOBUF); 2777 } 2778 } 2779 } else { 2780 int desiredpages; 2781 2782 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2783 desiredpages = (size == 0) ? 0 : 2784 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2785 2786 if (bp->b_flags & B_MALLOC) 2787 panic("allocbuf: VMIO buffer can't be malloced"); 2788 /* 2789 * Set B_CACHE initially if buffer is 0 length or will become 2790 * 0-length. 2791 */ 2792 if (size == 0 || bp->b_bufsize == 0) 2793 bp->b_flags |= B_CACHE; 2794 2795 if (newbsize < bp->b_bufsize) { 2796 /* 2797 * DEV_BSIZE aligned new buffer size is less then the 2798 * DEV_BSIZE aligned existing buffer size. Figure out 2799 * if we have to remove any pages. 2800 */ 2801 if (desiredpages < bp->b_npages) { 2802 vm_page_t m; 2803 2804 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2805 vm_page_lock_queues(); 2806 for (i = desiredpages; i < bp->b_npages; i++) { 2807 /* 2808 * the page is not freed here -- it 2809 * is the responsibility of 2810 * vnode_pager_setsize 2811 */ 2812 m = bp->b_pages[i]; 2813 KASSERT(m != bogus_page, 2814 ("allocbuf: bogus page found")); 2815 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2816 vm_page_lock_queues(); 2817 2818 bp->b_pages[i] = NULL; 2819 vm_page_unwire(m, 0); 2820 } 2821 vm_page_unlock_queues(); 2822 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2823 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2824 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2825 bp->b_npages = desiredpages; 2826 } 2827 } else if (size > bp->b_bcount) { 2828 /* 2829 * We are growing the buffer, possibly in a 2830 * byte-granular fashion. 2831 */ 2832 struct vnode *vp; 2833 vm_object_t obj; 2834 vm_offset_t toff; 2835 vm_offset_t tinc; 2836 2837 /* 2838 * Step 1, bring in the VM pages from the object, 2839 * allocating them if necessary. We must clear 2840 * B_CACHE if these pages are not valid for the 2841 * range covered by the buffer. 2842 */ 2843 2844 vp = bp->b_vp; 2845 obj = bp->b_bufobj->bo_object; 2846 2847 VM_OBJECT_LOCK(obj); 2848 while (bp->b_npages < desiredpages) { 2849 vm_page_t m; 2850 vm_pindex_t pi; 2851 2852 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2853 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2854 /* 2855 * note: must allocate system pages 2856 * since blocking here could intefere 2857 * with paging I/O, no matter which 2858 * process we are. 2859 */ 2860 m = vm_page_alloc(obj, pi, 2861 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2862 VM_ALLOC_WIRED); 2863 if (m == NULL) { 2864 atomic_add_int(&vm_pageout_deficit, 2865 desiredpages - bp->b_npages); 2866 VM_OBJECT_UNLOCK(obj); 2867 VM_WAIT; 2868 VM_OBJECT_LOCK(obj); 2869 } else { 2870 bp->b_flags &= ~B_CACHE; 2871 bp->b_pages[bp->b_npages] = m; 2872 ++bp->b_npages; 2873 } 2874 continue; 2875 } 2876 2877 /* 2878 * We found a page. If we have to sleep on it, 2879 * retry because it might have gotten freed out 2880 * from under us. 2881 * 2882 * We can only test PG_BUSY here. Blocking on 2883 * m->busy might lead to a deadlock: 2884 * 2885 * vm_fault->getpages->cluster_read->allocbuf 2886 * 2887 */ 2888 vm_page_lock_queues(); 2889 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2890 continue; 2891 2892 /* 2893 * We have a good page. Should we wakeup the 2894 * page daemon? 2895 */ 2896 if ((curproc != pageproc) && 2897 (VM_PAGE_INQUEUE1(m, PQ_CACHE)) && 2898 ((cnt.v_free_count + cnt.v_cache_count) < 2899 (cnt.v_free_min + cnt.v_cache_min))) { 2900 pagedaemon_wakeup(); 2901 } 2902 vm_page_wire(m); 2903 vm_page_unlock_queues(); 2904 bp->b_pages[bp->b_npages] = m; 2905 ++bp->b_npages; 2906 } 2907 2908 /* 2909 * Step 2. We've loaded the pages into the buffer, 2910 * we have to figure out if we can still have B_CACHE 2911 * set. Note that B_CACHE is set according to the 2912 * byte-granular range ( bcount and size ), new the 2913 * aligned range ( newbsize ). 2914 * 2915 * The VM test is against m->valid, which is DEV_BSIZE 2916 * aligned. Needless to say, the validity of the data 2917 * needs to also be DEV_BSIZE aligned. Note that this 2918 * fails with NFS if the server or some other client 2919 * extends the file's EOF. If our buffer is resized, 2920 * B_CACHE may remain set! XXX 2921 */ 2922 2923 toff = bp->b_bcount; 2924 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2925 2926 while ((bp->b_flags & B_CACHE) && toff < size) { 2927 vm_pindex_t pi; 2928 2929 if (tinc > (size - toff)) 2930 tinc = size - toff; 2931 2932 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2933 PAGE_SHIFT; 2934 2935 vfs_buf_test_cache( 2936 bp, 2937 bp->b_offset, 2938 toff, 2939 tinc, 2940 bp->b_pages[pi] 2941 ); 2942 toff += tinc; 2943 tinc = PAGE_SIZE; 2944 } 2945 VM_OBJECT_UNLOCK(obj); 2946 2947 /* 2948 * Step 3, fixup the KVM pmap. Remember that 2949 * bp->b_data is relative to bp->b_offset, but 2950 * bp->b_offset may be offset into the first page. 2951 */ 2952 2953 bp->b_data = (caddr_t) 2954 trunc_page((vm_offset_t)bp->b_data); 2955 pmap_qenter( 2956 (vm_offset_t)bp->b_data, 2957 bp->b_pages, 2958 bp->b_npages 2959 ); 2960 2961 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2962 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2963 } 2964 } 2965 if (newbsize < bp->b_bufsize) 2966 bufspacewakeup(); 2967 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2968 bp->b_bcount = size; /* requested buffer size */ 2969 return 1; 2970 } 2971 2972 void 2973 biodone(struct bio *bp) 2974 { 2975 void (*done)(struct bio *); 2976 2977 mtx_lock(&bdonelock); 2978 bp->bio_flags |= BIO_DONE; 2979 done = bp->bio_done; 2980 if (done == NULL) 2981 wakeup(bp); 2982 mtx_unlock(&bdonelock); 2983 if (done != NULL) 2984 done(bp); 2985 } 2986 2987 /* 2988 * Wait for a BIO to finish. 2989 * 2990 * XXX: resort to a timeout for now. The optimal locking (if any) for this 2991 * case is not yet clear. 2992 */ 2993 int 2994 biowait(struct bio *bp, const char *wchan) 2995 { 2996 2997 mtx_lock(&bdonelock); 2998 while ((bp->bio_flags & BIO_DONE) == 0) 2999 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3000 mtx_unlock(&bdonelock); 3001 if (bp->bio_error != 0) 3002 return (bp->bio_error); 3003 if (!(bp->bio_flags & BIO_ERROR)) 3004 return (0); 3005 return (EIO); 3006 } 3007 3008 void 3009 biofinish(struct bio *bp, struct devstat *stat, int error) 3010 { 3011 3012 if (error) { 3013 bp->bio_error = error; 3014 bp->bio_flags |= BIO_ERROR; 3015 } 3016 if (stat != NULL) 3017 devstat_end_transaction_bio(stat, bp); 3018 biodone(bp); 3019 } 3020 3021 /* 3022 * bufwait: 3023 * 3024 * Wait for buffer I/O completion, returning error status. The buffer 3025 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3026 * error and cleared. 3027 */ 3028 int 3029 bufwait(struct buf *bp) 3030 { 3031 if (bp->b_iocmd == BIO_READ) 3032 bwait(bp, PRIBIO, "biord"); 3033 else 3034 bwait(bp, PRIBIO, "biowr"); 3035 if (bp->b_flags & B_EINTR) { 3036 bp->b_flags &= ~B_EINTR; 3037 return (EINTR); 3038 } 3039 if (bp->b_ioflags & BIO_ERROR) { 3040 return (bp->b_error ? bp->b_error : EIO); 3041 } else { 3042 return (0); 3043 } 3044 } 3045 3046 /* 3047 * Call back function from struct bio back up to struct buf. 3048 */ 3049 static void 3050 bufdonebio(struct bio *bip) 3051 { 3052 struct buf *bp; 3053 3054 bp = bip->bio_caller2; 3055 bp->b_resid = bp->b_bcount - bip->bio_completed; 3056 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3057 bp->b_ioflags = bip->bio_flags; 3058 bp->b_error = bip->bio_error; 3059 if (bp->b_error) 3060 bp->b_ioflags |= BIO_ERROR; 3061 bufdone(bp); 3062 g_destroy_bio(bip); 3063 } 3064 3065 void 3066 dev_strategy(struct cdev *dev, struct buf *bp) 3067 { 3068 struct cdevsw *csw; 3069 struct bio *bip; 3070 3071 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3072 panic("b_iocmd botch"); 3073 for (;;) { 3074 bip = g_new_bio(); 3075 if (bip != NULL) 3076 break; 3077 /* Try again later */ 3078 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3079 } 3080 bip->bio_cmd = bp->b_iocmd; 3081 bip->bio_offset = bp->b_iooffset; 3082 bip->bio_length = bp->b_bcount; 3083 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3084 bip->bio_data = bp->b_data; 3085 bip->bio_done = bufdonebio; 3086 bip->bio_caller2 = bp; 3087 bip->bio_dev = dev; 3088 KASSERT(dev->si_refcount > 0, 3089 ("dev_strategy on un-referenced struct cdev *(%s)", 3090 devtoname(dev))); 3091 csw = dev_refthread(dev); 3092 if (csw == NULL) { 3093 g_destroy_bio(bip); 3094 bp->b_error = ENXIO; 3095 bp->b_ioflags = BIO_ERROR; 3096 bufdone(bp); 3097 return; 3098 } 3099 (*csw->d_strategy)(bip); 3100 dev_relthread(dev); 3101 } 3102 3103 /* 3104 * bufdone: 3105 * 3106 * Finish I/O on a buffer, optionally calling a completion function. 3107 * This is usually called from an interrupt so process blocking is 3108 * not allowed. 3109 * 3110 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3111 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3112 * assuming B_INVAL is clear. 3113 * 3114 * For the VMIO case, we set B_CACHE if the op was a read and no 3115 * read error occured, or if the op was a write. B_CACHE is never 3116 * set if the buffer is invalid or otherwise uncacheable. 3117 * 3118 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3119 * initiator to leave B_INVAL set to brelse the buffer out of existance 3120 * in the biodone routine. 3121 */ 3122 void 3123 bufdone(struct buf *bp) 3124 { 3125 struct bufobj *dropobj; 3126 void (*biodone)(struct buf *); 3127 3128 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3129 dropobj = NULL; 3130 3131 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3132 BUF_REFCNT(bp))); 3133 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3134 3135 runningbufwakeup(bp); 3136 if (bp->b_iocmd == BIO_WRITE) 3137 dropobj = bp->b_bufobj; 3138 /* call optional completion function if requested */ 3139 if (bp->b_iodone != NULL) { 3140 biodone = bp->b_iodone; 3141 bp->b_iodone = NULL; 3142 (*biodone) (bp); 3143 if (dropobj) 3144 bufobj_wdrop(dropobj); 3145 return; 3146 } 3147 3148 bufdone_finish(bp); 3149 3150 if (dropobj) 3151 bufobj_wdrop(dropobj); 3152 } 3153 3154 void 3155 bufdone_finish(struct buf *bp) 3156 { 3157 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3158 BUF_REFCNT(bp))); 3159 3160 if (LIST_FIRST(&bp->b_dep) != NULL) 3161 buf_complete(bp); 3162 3163 if (bp->b_flags & B_VMIO) { 3164 int i; 3165 vm_ooffset_t foff; 3166 vm_page_t m; 3167 vm_object_t obj; 3168 int iosize; 3169 struct vnode *vp = bp->b_vp; 3170 3171 obj = bp->b_bufobj->bo_object; 3172 3173 #if defined(VFS_BIO_DEBUG) 3174 mp_fixme("usecount and vflag accessed without locks."); 3175 if (vp->v_usecount == 0) { 3176 panic("biodone: zero vnode ref count"); 3177 } 3178 3179 KASSERT(vp->v_object != NULL, 3180 ("biodone: vnode %p has no vm_object", vp)); 3181 #endif 3182 3183 foff = bp->b_offset; 3184 KASSERT(bp->b_offset != NOOFFSET, 3185 ("biodone: no buffer offset")); 3186 3187 VM_OBJECT_LOCK(obj); 3188 #if defined(VFS_BIO_DEBUG) 3189 if (obj->paging_in_progress < bp->b_npages) { 3190 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3191 obj->paging_in_progress, bp->b_npages); 3192 } 3193 #endif 3194 3195 /* 3196 * Set B_CACHE if the op was a normal read and no error 3197 * occured. B_CACHE is set for writes in the b*write() 3198 * routines. 3199 */ 3200 iosize = bp->b_bcount - bp->b_resid; 3201 if (bp->b_iocmd == BIO_READ && 3202 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3203 !(bp->b_ioflags & BIO_ERROR)) { 3204 bp->b_flags |= B_CACHE; 3205 } 3206 vm_page_lock_queues(); 3207 for (i = 0; i < bp->b_npages; i++) { 3208 int bogusflag = 0; 3209 int resid; 3210 3211 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3212 if (resid > iosize) 3213 resid = iosize; 3214 3215 /* 3216 * cleanup bogus pages, restoring the originals 3217 */ 3218 m = bp->b_pages[i]; 3219 if (m == bogus_page) { 3220 bogusflag = 1; 3221 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3222 if (m == NULL) 3223 panic("biodone: page disappeared!"); 3224 bp->b_pages[i] = m; 3225 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3226 bp->b_pages, bp->b_npages); 3227 } 3228 #if defined(VFS_BIO_DEBUG) 3229 if (OFF_TO_IDX(foff) != m->pindex) { 3230 printf( 3231 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3232 (intmax_t)foff, (uintmax_t)m->pindex); 3233 } 3234 #endif 3235 3236 /* 3237 * In the write case, the valid and clean bits are 3238 * already changed correctly ( see bdwrite() ), so we 3239 * only need to do this here in the read case. 3240 */ 3241 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3242 vfs_page_set_valid(bp, foff, i, m); 3243 } 3244 3245 /* 3246 * when debugging new filesystems or buffer I/O methods, this 3247 * is the most common error that pops up. if you see this, you 3248 * have not set the page busy flag correctly!!! 3249 */ 3250 if (m->busy == 0) { 3251 printf("biodone: page busy < 0, " 3252 "pindex: %d, foff: 0x(%x,%x), " 3253 "resid: %d, index: %d\n", 3254 (int) m->pindex, (int)(foff >> 32), 3255 (int) foff & 0xffffffff, resid, i); 3256 if (!vn_isdisk(vp, NULL)) 3257 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3258 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3259 (intmax_t) bp->b_lblkno, 3260 bp->b_flags, bp->b_npages); 3261 else 3262 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3263 (intmax_t) bp->b_lblkno, 3264 bp->b_flags, bp->b_npages); 3265 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3266 (u_long)m->valid, (u_long)m->dirty, 3267 m->wire_count); 3268 panic("biodone: page busy < 0\n"); 3269 } 3270 vm_page_io_finish(m); 3271 vm_object_pip_subtract(obj, 1); 3272 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3273 iosize -= resid; 3274 } 3275 vm_page_unlock_queues(); 3276 vm_object_pip_wakeupn(obj, 0); 3277 VM_OBJECT_UNLOCK(obj); 3278 } 3279 3280 /* 3281 * For asynchronous completions, release the buffer now. The brelse 3282 * will do a wakeup there if necessary - so no need to do a wakeup 3283 * here in the async case. The sync case always needs to do a wakeup. 3284 */ 3285 3286 if (bp->b_flags & B_ASYNC) { 3287 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3288 brelse(bp); 3289 else 3290 bqrelse(bp); 3291 } else 3292 bdone(bp); 3293 } 3294 3295 /* 3296 * This routine is called in lieu of iodone in the case of 3297 * incomplete I/O. This keeps the busy status for pages 3298 * consistant. 3299 */ 3300 void 3301 vfs_unbusy_pages(struct buf *bp) 3302 { 3303 int i; 3304 vm_object_t obj; 3305 vm_page_t m; 3306 3307 runningbufwakeup(bp); 3308 if (!(bp->b_flags & B_VMIO)) 3309 return; 3310 3311 obj = bp->b_bufobj->bo_object; 3312 VM_OBJECT_LOCK(obj); 3313 for (i = 0; i < bp->b_npages; i++) { 3314 m = bp->b_pages[i]; 3315 if (m == bogus_page) { 3316 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3317 if (!m) 3318 panic("vfs_unbusy_pages: page missing\n"); 3319 bp->b_pages[i] = m; 3320 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3321 bp->b_pages, bp->b_npages); 3322 } 3323 vm_object_pip_subtract(obj, 1); 3324 vm_page_io_finish(m); 3325 } 3326 vm_object_pip_wakeupn(obj, 0); 3327 VM_OBJECT_UNLOCK(obj); 3328 } 3329 3330 /* 3331 * vfs_page_set_valid: 3332 * 3333 * Set the valid bits in a page based on the supplied offset. The 3334 * range is restricted to the buffer's size. 3335 * 3336 * This routine is typically called after a read completes. 3337 */ 3338 static void 3339 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3340 { 3341 vm_ooffset_t soff, eoff; 3342 3343 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3344 /* 3345 * Start and end offsets in buffer. eoff - soff may not cross a 3346 * page boundry or cross the end of the buffer. The end of the 3347 * buffer, in this case, is our file EOF, not the allocation size 3348 * of the buffer. 3349 */ 3350 soff = off; 3351 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3352 if (eoff > bp->b_offset + bp->b_bcount) 3353 eoff = bp->b_offset + bp->b_bcount; 3354 3355 /* 3356 * Set valid range. This is typically the entire buffer and thus the 3357 * entire page. 3358 */ 3359 if (eoff > soff) { 3360 vm_page_set_validclean( 3361 m, 3362 (vm_offset_t) (soff & PAGE_MASK), 3363 (vm_offset_t) (eoff - soff) 3364 ); 3365 } 3366 } 3367 3368 /* 3369 * This routine is called before a device strategy routine. 3370 * It is used to tell the VM system that paging I/O is in 3371 * progress, and treat the pages associated with the buffer 3372 * almost as being PG_BUSY. Also the object paging_in_progress 3373 * flag is handled to make sure that the object doesn't become 3374 * inconsistant. 3375 * 3376 * Since I/O has not been initiated yet, certain buffer flags 3377 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3378 * and should be ignored. 3379 */ 3380 void 3381 vfs_busy_pages(struct buf *bp, int clear_modify) 3382 { 3383 int i, bogus; 3384 vm_object_t obj; 3385 vm_ooffset_t foff; 3386 vm_page_t m; 3387 3388 if (!(bp->b_flags & B_VMIO)) 3389 return; 3390 3391 obj = bp->b_bufobj->bo_object; 3392 foff = bp->b_offset; 3393 KASSERT(bp->b_offset != NOOFFSET, 3394 ("vfs_busy_pages: no buffer offset")); 3395 vfs_setdirty(bp); 3396 VM_OBJECT_LOCK(obj); 3397 retry: 3398 for (i = 0; i < bp->b_npages; i++) { 3399 m = bp->b_pages[i]; 3400 3401 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3402 goto retry; 3403 } 3404 bogus = 0; 3405 vm_page_lock_queues(); 3406 for (i = 0; i < bp->b_npages; i++) { 3407 m = bp->b_pages[i]; 3408 3409 if ((bp->b_flags & B_CLUSTER) == 0) { 3410 vm_object_pip_add(obj, 1); 3411 vm_page_io_start(m); 3412 } 3413 /* 3414 * When readying a buffer for a read ( i.e 3415 * clear_modify == 0 ), it is important to do 3416 * bogus_page replacement for valid pages in 3417 * partially instantiated buffers. Partially 3418 * instantiated buffers can, in turn, occur when 3419 * reconstituting a buffer from its VM backing store 3420 * base. We only have to do this if B_CACHE is 3421 * clear ( which causes the I/O to occur in the 3422 * first place ). The replacement prevents the read 3423 * I/O from overwriting potentially dirty VM-backed 3424 * pages. XXX bogus page replacement is, uh, bogus. 3425 * It may not work properly with small-block devices. 3426 * We need to find a better way. 3427 */ 3428 pmap_remove_all(m); 3429 if (clear_modify) 3430 vfs_page_set_valid(bp, foff, i, m); 3431 else if (m->valid == VM_PAGE_BITS_ALL && 3432 (bp->b_flags & B_CACHE) == 0) { 3433 bp->b_pages[i] = bogus_page; 3434 bogus++; 3435 } 3436 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3437 } 3438 vm_page_unlock_queues(); 3439 VM_OBJECT_UNLOCK(obj); 3440 if (bogus) 3441 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3442 bp->b_pages, bp->b_npages); 3443 } 3444 3445 /* 3446 * Tell the VM system that the pages associated with this buffer 3447 * are clean. This is used for delayed writes where the data is 3448 * going to go to disk eventually without additional VM intevention. 3449 * 3450 * Note that while we only really need to clean through to b_bcount, we 3451 * just go ahead and clean through to b_bufsize. 3452 */ 3453 static void 3454 vfs_clean_pages(struct buf *bp) 3455 { 3456 int i; 3457 vm_ooffset_t foff, noff, eoff; 3458 vm_page_t m; 3459 3460 if (!(bp->b_flags & B_VMIO)) 3461 return; 3462 3463 foff = bp->b_offset; 3464 KASSERT(bp->b_offset != NOOFFSET, 3465 ("vfs_clean_pages: no buffer offset")); 3466 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3467 vm_page_lock_queues(); 3468 for (i = 0; i < bp->b_npages; i++) { 3469 m = bp->b_pages[i]; 3470 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3471 eoff = noff; 3472 3473 if (eoff > bp->b_offset + bp->b_bufsize) 3474 eoff = bp->b_offset + bp->b_bufsize; 3475 vfs_page_set_valid(bp, foff, i, m); 3476 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3477 foff = noff; 3478 } 3479 vm_page_unlock_queues(); 3480 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3481 } 3482 3483 /* 3484 * vfs_bio_set_validclean: 3485 * 3486 * Set the range within the buffer to valid and clean. The range is 3487 * relative to the beginning of the buffer, b_offset. Note that b_offset 3488 * itself may be offset from the beginning of the first page. 3489 * 3490 */ 3491 3492 void 3493 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3494 { 3495 int i, n; 3496 vm_page_t m; 3497 3498 if (!(bp->b_flags & B_VMIO)) 3499 return; 3500 /* 3501 * Fixup base to be relative to beginning of first page. 3502 * Set initial n to be the maximum number of bytes in the 3503 * first page that can be validated. 3504 */ 3505 3506 base += (bp->b_offset & PAGE_MASK); 3507 n = PAGE_SIZE - (base & PAGE_MASK); 3508 3509 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3510 vm_page_lock_queues(); 3511 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3512 m = bp->b_pages[i]; 3513 if (n > size) 3514 n = size; 3515 vm_page_set_validclean(m, base & PAGE_MASK, n); 3516 base += n; 3517 size -= n; 3518 n = PAGE_SIZE; 3519 } 3520 vm_page_unlock_queues(); 3521 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3522 } 3523 3524 /* 3525 * vfs_bio_clrbuf: 3526 * 3527 * clear a buffer. This routine essentially fakes an I/O, so we need 3528 * to clear BIO_ERROR and B_INVAL. 3529 * 3530 * Note that while we only theoretically need to clear through b_bcount, 3531 * we go ahead and clear through b_bufsize. 3532 */ 3533 3534 void 3535 vfs_bio_clrbuf(struct buf *bp) 3536 { 3537 int i, j, mask = 0; 3538 caddr_t sa, ea; 3539 3540 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3541 clrbuf(bp); 3542 return; 3543 } 3544 3545 bp->b_flags &= ~B_INVAL; 3546 bp->b_ioflags &= ~BIO_ERROR; 3547 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3548 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3549 (bp->b_offset & PAGE_MASK) == 0) { 3550 if (bp->b_pages[0] == bogus_page) 3551 goto unlock; 3552 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3553 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3554 if ((bp->b_pages[0]->valid & mask) == mask) 3555 goto unlock; 3556 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3557 ((bp->b_pages[0]->valid & mask) == 0)) { 3558 bzero(bp->b_data, bp->b_bufsize); 3559 bp->b_pages[0]->valid |= mask; 3560 goto unlock; 3561 } 3562 } 3563 ea = sa = bp->b_data; 3564 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3565 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3566 ea = (caddr_t)(vm_offset_t)ulmin( 3567 (u_long)(vm_offset_t)ea, 3568 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3569 if (bp->b_pages[i] == bogus_page) 3570 continue; 3571 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3572 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3573 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3574 if ((bp->b_pages[i]->valid & mask) == mask) 3575 continue; 3576 if ((bp->b_pages[i]->valid & mask) == 0) { 3577 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3578 bzero(sa, ea - sa); 3579 } else { 3580 for (; sa < ea; sa += DEV_BSIZE, j++) { 3581 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3582 (bp->b_pages[i]->valid & (1 << j)) == 0) 3583 bzero(sa, DEV_BSIZE); 3584 } 3585 } 3586 bp->b_pages[i]->valid |= mask; 3587 } 3588 unlock: 3589 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3590 bp->b_resid = 0; 3591 } 3592 3593 /* 3594 * vm_hold_load_pages and vm_hold_free_pages get pages into 3595 * a buffers address space. The pages are anonymous and are 3596 * not associated with a file object. 3597 */ 3598 static void 3599 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3600 { 3601 vm_offset_t pg; 3602 vm_page_t p; 3603 int index; 3604 3605 to = round_page(to); 3606 from = round_page(from); 3607 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3608 3609 VM_OBJECT_LOCK(kernel_object); 3610 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3611 tryagain: 3612 /* 3613 * note: must allocate system pages since blocking here 3614 * could intefere with paging I/O, no matter which 3615 * process we are. 3616 */ 3617 p = vm_page_alloc(kernel_object, 3618 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3619 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3620 if (!p) { 3621 atomic_add_int(&vm_pageout_deficit, 3622 (to - pg) >> PAGE_SHIFT); 3623 VM_OBJECT_UNLOCK(kernel_object); 3624 VM_WAIT; 3625 VM_OBJECT_LOCK(kernel_object); 3626 goto tryagain; 3627 } 3628 p->valid = VM_PAGE_BITS_ALL; 3629 pmap_qenter(pg, &p, 1); 3630 bp->b_pages[index] = p; 3631 } 3632 VM_OBJECT_UNLOCK(kernel_object); 3633 bp->b_npages = index; 3634 } 3635 3636 /* Return pages associated with this buf to the vm system */ 3637 static void 3638 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3639 { 3640 vm_offset_t pg; 3641 vm_page_t p; 3642 int index, newnpages; 3643 3644 from = round_page(from); 3645 to = round_page(to); 3646 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3647 3648 VM_OBJECT_LOCK(kernel_object); 3649 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3650 p = bp->b_pages[index]; 3651 if (p && (index < bp->b_npages)) { 3652 if (p->busy) { 3653 printf( 3654 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3655 (intmax_t)bp->b_blkno, 3656 (intmax_t)bp->b_lblkno); 3657 } 3658 bp->b_pages[index] = NULL; 3659 pmap_qremove(pg, 1); 3660 vm_page_lock_queues(); 3661 vm_page_unwire(p, 0); 3662 vm_page_free(p); 3663 vm_page_unlock_queues(); 3664 } 3665 } 3666 VM_OBJECT_UNLOCK(kernel_object); 3667 bp->b_npages = newnpages; 3668 } 3669 3670 /* 3671 * Map an IO request into kernel virtual address space. 3672 * 3673 * All requests are (re)mapped into kernel VA space. 3674 * Notice that we use b_bufsize for the size of the buffer 3675 * to be mapped. b_bcount might be modified by the driver. 3676 * 3677 * Note that even if the caller determines that the address space should 3678 * be valid, a race or a smaller-file mapped into a larger space may 3679 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3680 * check the return value. 3681 */ 3682 int 3683 vmapbuf(struct buf *bp) 3684 { 3685 caddr_t addr, kva; 3686 vm_prot_t prot; 3687 int pidx, i; 3688 struct vm_page *m; 3689 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3690 3691 if (bp->b_bufsize < 0) 3692 return (-1); 3693 prot = VM_PROT_READ; 3694 if (bp->b_iocmd == BIO_READ) 3695 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3696 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3697 addr < bp->b_data + bp->b_bufsize; 3698 addr += PAGE_SIZE, pidx++) { 3699 /* 3700 * Do the vm_fault if needed; do the copy-on-write thing 3701 * when reading stuff off device into memory. 3702 * 3703 * NOTE! Must use pmap_extract() because addr may be in 3704 * the userland address space, and kextract is only guarenteed 3705 * to work for the kernland address space (see: sparc64 port). 3706 */ 3707 retry: 3708 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3709 prot) < 0) { 3710 vm_page_lock_queues(); 3711 for (i = 0; i < pidx; ++i) { 3712 vm_page_unhold(bp->b_pages[i]); 3713 bp->b_pages[i] = NULL; 3714 } 3715 vm_page_unlock_queues(); 3716 return(-1); 3717 } 3718 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3719 if (m == NULL) 3720 goto retry; 3721 bp->b_pages[pidx] = m; 3722 } 3723 if (pidx > btoc(MAXPHYS)) 3724 panic("vmapbuf: mapped more than MAXPHYS"); 3725 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3726 3727 kva = bp->b_saveaddr; 3728 bp->b_npages = pidx; 3729 bp->b_saveaddr = bp->b_data; 3730 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3731 return(0); 3732 } 3733 3734 /* 3735 * Free the io map PTEs associated with this IO operation. 3736 * We also invalidate the TLB entries and restore the original b_addr. 3737 */ 3738 void 3739 vunmapbuf(struct buf *bp) 3740 { 3741 int pidx; 3742 int npages; 3743 3744 npages = bp->b_npages; 3745 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3746 vm_page_lock_queues(); 3747 for (pidx = 0; pidx < npages; pidx++) 3748 vm_page_unhold(bp->b_pages[pidx]); 3749 vm_page_unlock_queues(); 3750 3751 bp->b_data = bp->b_saveaddr; 3752 } 3753 3754 void 3755 bdone(struct buf *bp) 3756 { 3757 3758 mtx_lock(&bdonelock); 3759 bp->b_flags |= B_DONE; 3760 wakeup(bp); 3761 mtx_unlock(&bdonelock); 3762 } 3763 3764 void 3765 bwait(struct buf *bp, u_char pri, const char *wchan) 3766 { 3767 3768 mtx_lock(&bdonelock); 3769 while ((bp->b_flags & B_DONE) == 0) 3770 msleep(bp, &bdonelock, pri, wchan, 0); 3771 mtx_unlock(&bdonelock); 3772 } 3773 3774 int 3775 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3776 { 3777 3778 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3779 } 3780 3781 void 3782 bufstrategy(struct bufobj *bo, struct buf *bp) 3783 { 3784 int i = 0; 3785 struct vnode *vp; 3786 3787 vp = bp->b_vp; 3788 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3789 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3790 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3791 i = VOP_STRATEGY(vp, bp); 3792 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3793 } 3794 3795 void 3796 bufobj_wrefl(struct bufobj *bo) 3797 { 3798 3799 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3800 ASSERT_BO_LOCKED(bo); 3801 bo->bo_numoutput++; 3802 } 3803 3804 void 3805 bufobj_wref(struct bufobj *bo) 3806 { 3807 3808 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3809 BO_LOCK(bo); 3810 bo->bo_numoutput++; 3811 BO_UNLOCK(bo); 3812 } 3813 3814 void 3815 bufobj_wdrop(struct bufobj *bo) 3816 { 3817 3818 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3819 BO_LOCK(bo); 3820 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3821 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3822 bo->bo_flag &= ~BO_WWAIT; 3823 wakeup(&bo->bo_numoutput); 3824 } 3825 BO_UNLOCK(bo); 3826 } 3827 3828 int 3829 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3830 { 3831 int error; 3832 3833 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3834 ASSERT_BO_LOCKED(bo); 3835 error = 0; 3836 while (bo->bo_numoutput) { 3837 bo->bo_flag |= BO_WWAIT; 3838 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3839 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3840 if (error) 3841 break; 3842 } 3843 return (error); 3844 } 3845 3846 void 3847 bpin(struct buf *bp) 3848 { 3849 mtx_lock(&bpinlock); 3850 bp->b_pin_count++; 3851 mtx_unlock(&bpinlock); 3852 } 3853 3854 void 3855 bunpin(struct buf *bp) 3856 { 3857 mtx_lock(&bpinlock); 3858 if (--bp->b_pin_count == 0) 3859 wakeup(bp); 3860 mtx_unlock(&bpinlock); 3861 } 3862 3863 void 3864 bunpin_wait(struct buf *bp) 3865 { 3866 mtx_lock(&bpinlock); 3867 while (bp->b_pin_count > 0) 3868 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3869 mtx_unlock(&bpinlock); 3870 } 3871 3872 #include "opt_ddb.h" 3873 #ifdef DDB 3874 #include <ddb/ddb.h> 3875 3876 /* DDB command to show buffer data */ 3877 DB_SHOW_COMMAND(buffer, db_show_buffer) 3878 { 3879 /* get args */ 3880 struct buf *bp = (struct buf *)addr; 3881 3882 if (!have_addr) { 3883 db_printf("usage: show buffer <addr>\n"); 3884 return; 3885 } 3886 3887 db_printf("buf at %p\n", bp); 3888 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3889 db_printf( 3890 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3891 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3892 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3893 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3894 if (bp->b_npages) { 3895 int i; 3896 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3897 for (i = 0; i < bp->b_npages; i++) { 3898 vm_page_t m; 3899 m = bp->b_pages[i]; 3900 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3901 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3902 if ((i + 1) < bp->b_npages) 3903 db_printf(","); 3904 } 3905 db_printf("\n"); 3906 } 3907 lockmgr_printinfo(&bp->b_lock); 3908 } 3909 3910 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3911 { 3912 struct buf *bp; 3913 int i; 3914 3915 for (i = 0; i < nbuf; i++) { 3916 bp = &buf[i]; 3917 if (lockcount(&bp->b_lock)) { 3918 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3919 db_printf("\n"); 3920 } 3921 } 3922 } 3923 #endif /* DDB */ 3924