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/limits.h> 52 #include <sys/lock.h> 53 #include <sys/malloc.h> 54 #include <sys/mount.h> 55 #include <sys/mutex.h> 56 #include <sys/kernel.h> 57 #include <sys/kthread.h> 58 #include <sys/proc.h> 59 #include <sys/resourcevar.h> 60 #include <sys/sysctl.h> 61 #include <sys/vmmeter.h> 62 #include <sys/vnode.h> 63 #include <geom/geom.h> 64 #include <vm/vm.h> 65 #include <vm/vm_param.h> 66 #include <vm/vm_kern.h> 67 #include <vm/vm_pageout.h> 68 #include <vm/vm_page.h> 69 #include <vm/vm_object.h> 70 #include <vm/vm_extern.h> 71 #include <vm/vm_map.h> 72 #include "opt_directio.h" 73 #include "opt_swap.h" 74 75 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 76 77 struct bio_ops bioops; /* I/O operation notification */ 78 79 struct buf_ops buf_ops_bio = { 80 .bop_name = "buf_ops_bio", 81 .bop_write = bufwrite, 82 .bop_strategy = bufstrategy, 83 .bop_sync = bufsync, 84 .bop_bdflush = bufbdflush, 85 }; 86 87 /* 88 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 89 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 90 */ 91 struct buf *buf; /* buffer header pool */ 92 93 static struct proc *bufdaemonproc; 94 95 static int inmem(struct vnode *vp, daddr_t blkno); 96 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 97 vm_offset_t to); 98 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 99 vm_offset_t to); 100 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 101 vm_page_t m); 102 static void vfs_clean_pages(struct buf *bp); 103 static void vfs_setdirty(struct buf *bp); 104 static void vfs_setdirty_locked_object(struct buf *bp); 105 static void vfs_vmio_release(struct buf *bp); 106 static int vfs_bio_clcheck(struct vnode *vp, int size, 107 daddr_t lblkno, daddr_t blkno); 108 static int flushbufqueues(int, int); 109 static void buf_daemon(void); 110 static void bremfreel(struct buf *bp); 111 112 int vmiodirenable = TRUE; 113 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 114 "Use the VM system for directory writes"); 115 int runningbufspace; 116 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 117 "Amount of presently outstanding async buffer io"); 118 static int bufspace; 119 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 120 "KVA memory used for bufs"); 121 static int maxbufspace; 122 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 123 "Maximum allowed value of bufspace (including buf_daemon)"); 124 static int bufmallocspace; 125 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 126 "Amount of malloced memory for buffers"); 127 static int maxbufmallocspace; 128 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 129 "Maximum amount of malloced memory for buffers"); 130 static int lobufspace; 131 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 132 "Minimum amount of buffers we want to have"); 133 int hibufspace; 134 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 135 "Maximum allowed value of bufspace (excluding buf_daemon)"); 136 static int bufreusecnt; 137 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 138 "Number of times we have reused a buffer"); 139 static int buffreekvacnt; 140 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 141 "Number of times we have freed the KVA space from some buffer"); 142 static int bufdefragcnt; 143 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 144 "Number of times we have had to repeat buffer allocation to defragment"); 145 static int lorunningspace; 146 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 147 "Minimum preferred space used for in-progress I/O"); 148 static int hirunningspace; 149 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 150 "Maximum amount of space to use for in-progress I/O"); 151 int dirtybufferflushes; 152 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 153 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 154 int bdwriteskip; 155 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 156 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 157 int altbufferflushes; 158 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 159 0, "Number of fsync flushes to limit dirty buffers"); 160 static int recursiveflushes; 161 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 162 0, "Number of flushes skipped due to being recursive"); 163 static int numdirtybuffers; 164 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 165 "Number of buffers that are dirty (has unwritten changes) at the moment"); 166 static int lodirtybuffers; 167 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 168 "How many buffers we want to have free before bufdaemon can sleep"); 169 static int hidirtybuffers; 170 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 171 "When the number of dirty buffers is considered severe"); 172 int dirtybufthresh; 173 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 174 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 175 static int numfreebuffers; 176 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 177 "Number of free buffers"); 178 static int lofreebuffers; 179 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 180 "XXX Unused"); 181 static int hifreebuffers; 182 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 183 "XXX Complicatedly unused"); 184 static int getnewbufcalls; 185 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 186 "Number of calls to getnewbuf"); 187 static int getnewbufrestarts; 188 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 189 "Number of times getnewbuf has had to restart a buffer aquisition"); 190 191 /* 192 * Wakeup point for bufdaemon, as well as indicator of whether it is already 193 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 194 * is idling. 195 */ 196 static int bd_request; 197 198 /* 199 * This lock synchronizes access to bd_request. 200 */ 201 static struct mtx bdlock; 202 203 /* 204 * bogus page -- for I/O to/from partially complete buffers 205 * this is a temporary solution to the problem, but it is not 206 * really that bad. it would be better to split the buffer 207 * for input in the case of buffers partially already in memory, 208 * but the code is intricate enough already. 209 */ 210 vm_page_t bogus_page; 211 212 /* 213 * Synchronization (sleep/wakeup) variable for active buffer space requests. 214 * Set when wait starts, cleared prior to wakeup(). 215 * Used in runningbufwakeup() and waitrunningbufspace(). 216 */ 217 static int runningbufreq; 218 219 /* 220 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 221 * waitrunningbufspace(). 222 */ 223 static struct mtx rbreqlock; 224 225 /* 226 * Synchronization (sleep/wakeup) variable for buffer requests. 227 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 228 * by and/or. 229 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 230 * getnewbuf(), and getblk(). 231 */ 232 static int needsbuffer; 233 234 /* 235 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 236 */ 237 static struct mtx nblock; 238 239 /* 240 * Definitions for the buffer free lists. 241 */ 242 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 243 244 #define QUEUE_NONE 0 /* on no queue */ 245 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 246 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 247 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 248 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 249 #define QUEUE_EMPTY 5 /* empty buffer headers */ 250 251 /* Queues for free buffers with various properties */ 252 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 253 254 /* Lock for the bufqueues */ 255 static struct mtx bqlock; 256 257 /* 258 * Single global constant for BUF_WMESG, to avoid getting multiple references. 259 * buf_wmesg is referred from macros. 260 */ 261 const char *buf_wmesg = BUF_WMESG; 262 263 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 264 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 265 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 266 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 267 268 #ifdef DIRECTIO 269 extern void ffs_rawread_setup(void); 270 #endif /* DIRECTIO */ 271 /* 272 * numdirtywakeup: 273 * 274 * If someone is blocked due to there being too many dirty buffers, 275 * and numdirtybuffers is now reasonable, wake them up. 276 */ 277 278 static __inline void 279 numdirtywakeup(int level) 280 { 281 282 if (numdirtybuffers <= level) { 283 mtx_lock(&nblock); 284 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 285 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 286 wakeup(&needsbuffer); 287 } 288 mtx_unlock(&nblock); 289 } 290 } 291 292 /* 293 * bufspacewakeup: 294 * 295 * Called when buffer space is potentially available for recovery. 296 * getnewbuf() will block on this flag when it is unable to free 297 * sufficient buffer space. Buffer space becomes recoverable when 298 * bp's get placed back in the queues. 299 */ 300 301 static __inline void 302 bufspacewakeup(void) 303 { 304 305 /* 306 * If someone is waiting for BUF space, wake them up. Even 307 * though we haven't freed the kva space yet, the waiting 308 * process will be able to now. 309 */ 310 mtx_lock(&nblock); 311 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 312 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 313 wakeup(&needsbuffer); 314 } 315 mtx_unlock(&nblock); 316 } 317 318 /* 319 * runningbufwakeup() - in-progress I/O accounting. 320 * 321 */ 322 void 323 runningbufwakeup(struct buf *bp) 324 { 325 326 if (bp->b_runningbufspace) { 327 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 328 bp->b_runningbufspace = 0; 329 mtx_lock(&rbreqlock); 330 if (runningbufreq && runningbufspace <= lorunningspace) { 331 runningbufreq = 0; 332 wakeup(&runningbufreq); 333 } 334 mtx_unlock(&rbreqlock); 335 } 336 } 337 338 /* 339 * bufcountwakeup: 340 * 341 * Called when a buffer has been added to one of the free queues to 342 * account for the buffer and to wakeup anyone waiting for free buffers. 343 * This typically occurs when large amounts of metadata are being handled 344 * by the buffer cache ( else buffer space runs out first, usually ). 345 */ 346 347 static __inline void 348 bufcountwakeup(void) 349 { 350 351 atomic_add_int(&numfreebuffers, 1); 352 mtx_lock(&nblock); 353 if (needsbuffer) { 354 needsbuffer &= ~VFS_BIO_NEED_ANY; 355 if (numfreebuffers >= hifreebuffers) 356 needsbuffer &= ~VFS_BIO_NEED_FREE; 357 wakeup(&needsbuffer); 358 } 359 mtx_unlock(&nblock); 360 } 361 362 /* 363 * waitrunningbufspace() 364 * 365 * runningbufspace is a measure of the amount of I/O currently 366 * running. This routine is used in async-write situations to 367 * prevent creating huge backups of pending writes to a device. 368 * Only asynchronous writes are governed by this function. 369 * 370 * Reads will adjust runningbufspace, but will not block based on it. 371 * The read load has a side effect of reducing the allowed write load. 372 * 373 * This does NOT turn an async write into a sync write. It waits 374 * for earlier writes to complete and generally returns before the 375 * caller's write has reached the device. 376 */ 377 void 378 waitrunningbufspace(void) 379 { 380 381 mtx_lock(&rbreqlock); 382 while (runningbufspace > hirunningspace) { 383 ++runningbufreq; 384 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 385 } 386 mtx_unlock(&rbreqlock); 387 } 388 389 390 /* 391 * vfs_buf_test_cache: 392 * 393 * Called when a buffer is extended. This function clears the B_CACHE 394 * bit if the newly extended portion of the buffer does not contain 395 * valid data. 396 */ 397 static __inline 398 void 399 vfs_buf_test_cache(struct buf *bp, 400 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 401 vm_page_t m) 402 { 403 404 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 405 if (bp->b_flags & B_CACHE) { 406 int base = (foff + off) & PAGE_MASK; 407 if (vm_page_is_valid(m, base, size) == 0) 408 bp->b_flags &= ~B_CACHE; 409 } 410 } 411 412 /* Wake up the buffer daemon if necessary */ 413 static __inline 414 void 415 bd_wakeup(int dirtybuflevel) 416 { 417 418 mtx_lock(&bdlock); 419 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 420 bd_request = 1; 421 wakeup(&bd_request); 422 } 423 mtx_unlock(&bdlock); 424 } 425 426 /* 427 * bd_speedup - speedup the buffer cache flushing code 428 */ 429 430 static __inline 431 void 432 bd_speedup(void) 433 { 434 435 bd_wakeup(1); 436 } 437 438 /* 439 * Calculating buffer cache scaling values and reserve space for buffer 440 * headers. This is called during low level kernel initialization and 441 * may be called more then once. We CANNOT write to the memory area 442 * being reserved at this time. 443 */ 444 caddr_t 445 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 446 { 447 int maxbuf; 448 449 /* 450 * physmem_est is in pages. Convert it to kilobytes (assumes 451 * PAGE_SIZE is >= 1K) 452 */ 453 physmem_est = physmem_est * (PAGE_SIZE / 1024); 454 455 /* 456 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 457 * For the first 64MB of ram nominally allocate sufficient buffers to 458 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 459 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 460 * the buffer cache we limit the eventual kva reservation to 461 * maxbcache bytes. 462 * 463 * factor represents the 1/4 x ram conversion. 464 */ 465 if (nbuf == 0) { 466 int factor = 4 * BKVASIZE / 1024; 467 468 nbuf = 50; 469 if (physmem_est > 4096) 470 nbuf += min((physmem_est - 4096) / factor, 471 65536 / factor); 472 if (physmem_est > 65536) 473 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 474 475 if (maxbcache && nbuf > maxbcache / BKVASIZE) 476 nbuf = maxbcache / BKVASIZE; 477 478 /* XXX Avoid integer overflows later on with maxbufspace. */ 479 maxbuf = (INT_MAX / 3) / BKVASIZE; 480 if (nbuf > maxbuf) 481 nbuf = maxbuf; 482 } 483 484 #if 0 485 /* 486 * Do not allow the buffer_map to be more then 1/2 the size of the 487 * kernel_map. 488 */ 489 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 490 (BKVASIZE * 2)) { 491 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 492 (BKVASIZE * 2); 493 printf("Warning: nbufs capped at %d\n", nbuf); 494 } 495 #endif 496 497 /* 498 * swbufs are used as temporary holders for I/O, such as paging I/O. 499 * We have no less then 16 and no more then 256. 500 */ 501 nswbuf = max(min(nbuf/4, 256), 16); 502 #ifdef NSWBUF_MIN 503 if (nswbuf < NSWBUF_MIN) 504 nswbuf = NSWBUF_MIN; 505 #endif 506 #ifdef DIRECTIO 507 ffs_rawread_setup(); 508 #endif 509 510 /* 511 * Reserve space for the buffer cache buffers 512 */ 513 swbuf = (void *)v; 514 v = (caddr_t)(swbuf + nswbuf); 515 buf = (void *)v; 516 v = (caddr_t)(buf + nbuf); 517 518 return(v); 519 } 520 521 /* Initialize the buffer subsystem. Called before use of any buffers. */ 522 void 523 bufinit(void) 524 { 525 struct buf *bp; 526 int i; 527 528 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 529 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 530 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 531 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 532 533 /* next, make a null set of free lists */ 534 for (i = 0; i < BUFFER_QUEUES; i++) 535 TAILQ_INIT(&bufqueues[i]); 536 537 /* finally, initialize each buffer header and stick on empty q */ 538 for (i = 0; i < nbuf; i++) { 539 bp = &buf[i]; 540 bzero(bp, sizeof *bp); 541 bp->b_flags = B_INVAL; /* we're just an empty header */ 542 bp->b_rcred = NOCRED; 543 bp->b_wcred = NOCRED; 544 bp->b_qindex = QUEUE_EMPTY; 545 bp->b_vflags = 0; 546 bp->b_xflags = 0; 547 LIST_INIT(&bp->b_dep); 548 BUF_LOCKINIT(bp); 549 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 550 } 551 552 /* 553 * maxbufspace is the absolute maximum amount of buffer space we are 554 * allowed to reserve in KVM and in real terms. The absolute maximum 555 * is nominally used by buf_daemon. hibufspace is the nominal maximum 556 * used by most other processes. The differential is required to 557 * ensure that buf_daemon is able to run when other processes might 558 * be blocked waiting for buffer space. 559 * 560 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 561 * this may result in KVM fragmentation which is not handled optimally 562 * by the system. 563 */ 564 maxbufspace = nbuf * BKVASIZE; 565 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 566 lobufspace = hibufspace - MAXBSIZE; 567 568 lorunningspace = 512 * 1024; 569 hirunningspace = 1024 * 1024; 570 571 /* 572 * Limit the amount of malloc memory since it is wired permanently into 573 * the kernel space. Even though this is accounted for in the buffer 574 * allocation, we don't want the malloced region to grow uncontrolled. 575 * The malloc scheme improves memory utilization significantly on average 576 * (small) directories. 577 */ 578 maxbufmallocspace = hibufspace / 20; 579 580 /* 581 * Reduce the chance of a deadlock occuring by limiting the number 582 * of delayed-write dirty buffers we allow to stack up. 583 */ 584 hidirtybuffers = nbuf / 4 + 20; 585 dirtybufthresh = hidirtybuffers * 9 / 10; 586 numdirtybuffers = 0; 587 /* 588 * To support extreme low-memory systems, make sure hidirtybuffers cannot 589 * eat up all available buffer space. This occurs when our minimum cannot 590 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 591 * BKVASIZE'd (8K) buffers. 592 */ 593 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 594 hidirtybuffers >>= 1; 595 } 596 lodirtybuffers = hidirtybuffers / 2; 597 598 /* 599 * Try to keep the number of free buffers in the specified range, 600 * and give special processes (e.g. like buf_daemon) access to an 601 * emergency reserve. 602 */ 603 lofreebuffers = nbuf / 18 + 5; 604 hifreebuffers = 2 * lofreebuffers; 605 numfreebuffers = nbuf; 606 607 /* 608 * Maximum number of async ops initiated per buf_daemon loop. This is 609 * somewhat of a hack at the moment, we really need to limit ourselves 610 * based on the number of bytes of I/O in-transit that were initiated 611 * from buf_daemon. 612 */ 613 614 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 615 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 616 } 617 618 /* 619 * bfreekva() - free the kva allocation for a buffer. 620 * 621 * Since this call frees up buffer space, we call bufspacewakeup(). 622 */ 623 static void 624 bfreekva(struct buf *bp) 625 { 626 627 if (bp->b_kvasize) { 628 atomic_add_int(&buffreekvacnt, 1); 629 atomic_subtract_int(&bufspace, bp->b_kvasize); 630 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 631 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 632 bp->b_kvasize = 0; 633 bufspacewakeup(); 634 } 635 } 636 637 /* 638 * bremfree: 639 * 640 * Mark the buffer for removal from the appropriate free list in brelse. 641 * 642 */ 643 void 644 bremfree(struct buf *bp) 645 { 646 647 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 648 KASSERT((bp->b_flags & B_REMFREE) == 0, 649 ("bremfree: buffer %p already marked for delayed removal.", bp)); 650 KASSERT(bp->b_qindex != QUEUE_NONE, 651 ("bremfree: buffer %p not on a queue.", bp)); 652 BUF_ASSERT_HELD(bp); 653 654 bp->b_flags |= B_REMFREE; 655 /* Fixup numfreebuffers count. */ 656 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 657 atomic_subtract_int(&numfreebuffers, 1); 658 } 659 660 /* 661 * bremfreef: 662 * 663 * Force an immediate removal from a free list. Used only in nfs when 664 * it abuses the b_freelist pointer. 665 */ 666 void 667 bremfreef(struct buf *bp) 668 { 669 mtx_lock(&bqlock); 670 bremfreel(bp); 671 mtx_unlock(&bqlock); 672 } 673 674 /* 675 * bremfreel: 676 * 677 * Removes a buffer from the free list, must be called with the 678 * bqlock held. 679 */ 680 static void 681 bremfreel(struct buf *bp) 682 { 683 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 684 bp, bp->b_vp, bp->b_flags); 685 KASSERT(bp->b_qindex != QUEUE_NONE, 686 ("bremfreel: buffer %p not on a queue.", bp)); 687 BUF_ASSERT_HELD(bp); 688 mtx_assert(&bqlock, MA_OWNED); 689 690 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 691 bp->b_qindex = QUEUE_NONE; 692 /* 693 * If this was a delayed bremfree() we only need to remove the buffer 694 * from the queue and return the stats are already done. 695 */ 696 if (bp->b_flags & B_REMFREE) { 697 bp->b_flags &= ~B_REMFREE; 698 return; 699 } 700 /* 701 * Fixup numfreebuffers count. If the buffer is invalid or not 702 * delayed-write, the buffer was free and we must decrement 703 * numfreebuffers. 704 */ 705 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 706 atomic_subtract_int(&numfreebuffers, 1); 707 } 708 709 710 /* 711 * Get a buffer with the specified data. Look in the cache first. We 712 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 713 * is set, the buffer is valid and we do not have to do anything ( see 714 * getblk() ). This is really just a special case of breadn(). 715 */ 716 int 717 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 718 struct buf **bpp) 719 { 720 721 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 722 } 723 724 /* 725 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 726 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 727 * the buffer is valid and we do not have to do anything. 728 */ 729 void 730 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 731 int cnt, struct ucred * cred) 732 { 733 struct buf *rabp; 734 int i; 735 736 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 737 if (inmem(vp, *rablkno)) 738 continue; 739 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 740 741 if ((rabp->b_flags & B_CACHE) == 0) { 742 if (!TD_IS_IDLETHREAD(curthread)) 743 curthread->td_ru.ru_inblock++; 744 rabp->b_flags |= B_ASYNC; 745 rabp->b_flags &= ~B_INVAL; 746 rabp->b_ioflags &= ~BIO_ERROR; 747 rabp->b_iocmd = BIO_READ; 748 if (rabp->b_rcred == NOCRED && cred != NOCRED) 749 rabp->b_rcred = crhold(cred); 750 vfs_busy_pages(rabp, 0); 751 BUF_KERNPROC(rabp); 752 rabp->b_iooffset = dbtob(rabp->b_blkno); 753 bstrategy(rabp); 754 } else { 755 brelse(rabp); 756 } 757 } 758 } 759 760 /* 761 * Operates like bread, but also starts asynchronous I/O on 762 * read-ahead blocks. 763 */ 764 int 765 breadn(struct vnode * vp, daddr_t blkno, int size, 766 daddr_t * rablkno, int *rabsize, 767 int cnt, struct ucred * cred, struct buf **bpp) 768 { 769 struct buf *bp; 770 int rv = 0, readwait = 0; 771 772 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 773 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 774 775 /* if not found in cache, do some I/O */ 776 if ((bp->b_flags & B_CACHE) == 0) { 777 if (!TD_IS_IDLETHREAD(curthread)) 778 curthread->td_ru.ru_inblock++; 779 bp->b_iocmd = BIO_READ; 780 bp->b_flags &= ~B_INVAL; 781 bp->b_ioflags &= ~BIO_ERROR; 782 if (bp->b_rcred == NOCRED && cred != NOCRED) 783 bp->b_rcred = crhold(cred); 784 vfs_busy_pages(bp, 0); 785 bp->b_iooffset = dbtob(bp->b_blkno); 786 bstrategy(bp); 787 ++readwait; 788 } 789 790 breada(vp, rablkno, rabsize, cnt, cred); 791 792 if (readwait) { 793 rv = bufwait(bp); 794 } 795 return (rv); 796 } 797 798 /* 799 * Write, release buffer on completion. (Done by iodone 800 * if async). Do not bother writing anything if the buffer 801 * is invalid. 802 * 803 * Note that we set B_CACHE here, indicating that buffer is 804 * fully valid and thus cacheable. This is true even of NFS 805 * now so we set it generally. This could be set either here 806 * or in biodone() since the I/O is synchronous. We put it 807 * here. 808 */ 809 int 810 bufwrite(struct buf *bp) 811 { 812 int oldflags; 813 struct vnode *vp; 814 int vp_md; 815 816 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 817 if (bp->b_flags & B_INVAL) { 818 brelse(bp); 819 return (0); 820 } 821 822 oldflags = bp->b_flags; 823 824 BUF_ASSERT_HELD(bp); 825 826 if (bp->b_pin_count > 0) 827 bunpin_wait(bp); 828 829 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 830 ("FFS background buffer should not get here %p", bp)); 831 832 vp = bp->b_vp; 833 if (vp) 834 vp_md = vp->v_vflag & VV_MD; 835 else 836 vp_md = 0; 837 838 /* Mark the buffer clean */ 839 bundirty(bp); 840 841 bp->b_flags &= ~B_DONE; 842 bp->b_ioflags &= ~BIO_ERROR; 843 bp->b_flags |= B_CACHE; 844 bp->b_iocmd = BIO_WRITE; 845 846 bufobj_wref(bp->b_bufobj); 847 vfs_busy_pages(bp, 1); 848 849 /* 850 * Normal bwrites pipeline writes 851 */ 852 bp->b_runningbufspace = bp->b_bufsize; 853 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 854 855 if (!TD_IS_IDLETHREAD(curthread)) 856 curthread->td_ru.ru_oublock++; 857 if (oldflags & B_ASYNC) 858 BUF_KERNPROC(bp); 859 bp->b_iooffset = dbtob(bp->b_blkno); 860 bstrategy(bp); 861 862 if ((oldflags & B_ASYNC) == 0) { 863 int rtval = bufwait(bp); 864 brelse(bp); 865 return (rtval); 866 } else { 867 /* 868 * don't allow the async write to saturate the I/O 869 * system. We will not deadlock here because 870 * we are blocking waiting for I/O that is already in-progress 871 * to complete. We do not block here if it is the update 872 * or syncer daemon trying to clean up as that can lead 873 * to deadlock. 874 */ 875 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 876 waitrunningbufspace(); 877 } 878 879 return (0); 880 } 881 882 void 883 bufbdflush(struct bufobj *bo, struct buf *bp) 884 { 885 struct buf *nbp; 886 887 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 888 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 889 altbufferflushes++; 890 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 891 BO_LOCK(bo); 892 /* 893 * Try to find a buffer to flush. 894 */ 895 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 896 if ((nbp->b_vflags & BV_BKGRDINPROG) || 897 BUF_LOCK(nbp, 898 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 899 continue; 900 if (bp == nbp) 901 panic("bdwrite: found ourselves"); 902 BO_UNLOCK(bo); 903 /* Don't countdeps with the bo lock held. */ 904 if (buf_countdeps(nbp, 0)) { 905 BO_LOCK(bo); 906 BUF_UNLOCK(nbp); 907 continue; 908 } 909 if (nbp->b_flags & B_CLUSTEROK) { 910 vfs_bio_awrite(nbp); 911 } else { 912 bremfree(nbp); 913 bawrite(nbp); 914 } 915 dirtybufferflushes++; 916 break; 917 } 918 if (nbp == NULL) 919 BO_UNLOCK(bo); 920 } 921 } 922 923 /* 924 * Delayed write. (Buffer is marked dirty). Do not bother writing 925 * anything if the buffer is marked invalid. 926 * 927 * Note that since the buffer must be completely valid, we can safely 928 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 929 * biodone() in order to prevent getblk from writing the buffer 930 * out synchronously. 931 */ 932 void 933 bdwrite(struct buf *bp) 934 { 935 struct thread *td = curthread; 936 struct vnode *vp; 937 struct bufobj *bo; 938 939 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 940 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 941 BUF_ASSERT_HELD(bp); 942 943 if (bp->b_flags & B_INVAL) { 944 brelse(bp); 945 return; 946 } 947 948 /* 949 * If we have too many dirty buffers, don't create any more. 950 * If we are wildly over our limit, then force a complete 951 * cleanup. Otherwise, just keep the situation from getting 952 * out of control. Note that we have to avoid a recursive 953 * disaster and not try to clean up after our own cleanup! 954 */ 955 vp = bp->b_vp; 956 bo = bp->b_bufobj; 957 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 958 td->td_pflags |= TDP_INBDFLUSH; 959 BO_BDFLUSH(bo, bp); 960 td->td_pflags &= ~TDP_INBDFLUSH; 961 } else 962 recursiveflushes++; 963 964 bdirty(bp); 965 /* 966 * Set B_CACHE, indicating that the buffer is fully valid. This is 967 * true even of NFS now. 968 */ 969 bp->b_flags |= B_CACHE; 970 971 /* 972 * This bmap keeps the system from needing to do the bmap later, 973 * perhaps when the system is attempting to do a sync. Since it 974 * is likely that the indirect block -- or whatever other datastructure 975 * that the filesystem needs is still in memory now, it is a good 976 * thing to do this. Note also, that if the pageout daemon is 977 * requesting a sync -- there might not be enough memory to do 978 * the bmap then... So, this is important to do. 979 */ 980 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 981 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 982 } 983 984 /* 985 * Set the *dirty* buffer range based upon the VM system dirty pages. 986 */ 987 vfs_setdirty(bp); 988 989 /* 990 * We need to do this here to satisfy the vnode_pager and the 991 * pageout daemon, so that it thinks that the pages have been 992 * "cleaned". Note that since the pages are in a delayed write 993 * buffer -- the VFS layer "will" see that the pages get written 994 * out on the next sync, or perhaps the cluster will be completed. 995 */ 996 vfs_clean_pages(bp); 997 bqrelse(bp); 998 999 /* 1000 * Wakeup the buffer flushing daemon if we have a lot of dirty 1001 * buffers (midpoint between our recovery point and our stall 1002 * point). 1003 */ 1004 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1005 1006 /* 1007 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1008 * due to the softdep code. 1009 */ 1010 } 1011 1012 /* 1013 * bdirty: 1014 * 1015 * Turn buffer into delayed write request. We must clear BIO_READ and 1016 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1017 * itself to properly update it in the dirty/clean lists. We mark it 1018 * B_DONE to ensure that any asynchronization of the buffer properly 1019 * clears B_DONE ( else a panic will occur later ). 1020 * 1021 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1022 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1023 * should only be called if the buffer is known-good. 1024 * 1025 * Since the buffer is not on a queue, we do not update the numfreebuffers 1026 * count. 1027 * 1028 * The buffer must be on QUEUE_NONE. 1029 */ 1030 void 1031 bdirty(struct buf *bp) 1032 { 1033 1034 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1035 bp, bp->b_vp, bp->b_flags); 1036 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1037 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1038 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1039 BUF_ASSERT_HELD(bp); 1040 bp->b_flags &= ~(B_RELBUF); 1041 bp->b_iocmd = BIO_WRITE; 1042 1043 if ((bp->b_flags & B_DELWRI) == 0) { 1044 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1045 reassignbuf(bp); 1046 atomic_add_int(&numdirtybuffers, 1); 1047 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1048 } 1049 } 1050 1051 /* 1052 * bundirty: 1053 * 1054 * Clear B_DELWRI for buffer. 1055 * 1056 * Since the buffer is not on a queue, we do not update the numfreebuffers 1057 * count. 1058 * 1059 * The buffer must be on QUEUE_NONE. 1060 */ 1061 1062 void 1063 bundirty(struct buf *bp) 1064 { 1065 1066 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1067 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1068 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1069 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1070 BUF_ASSERT_HELD(bp); 1071 1072 if (bp->b_flags & B_DELWRI) { 1073 bp->b_flags &= ~B_DELWRI; 1074 reassignbuf(bp); 1075 atomic_subtract_int(&numdirtybuffers, 1); 1076 numdirtywakeup(lodirtybuffers); 1077 } 1078 /* 1079 * Since it is now being written, we can clear its deferred write flag. 1080 */ 1081 bp->b_flags &= ~B_DEFERRED; 1082 } 1083 1084 /* 1085 * bawrite: 1086 * 1087 * Asynchronous write. Start output on a buffer, but do not wait for 1088 * it to complete. The buffer is released when the output completes. 1089 * 1090 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1091 * B_INVAL buffers. Not us. 1092 */ 1093 void 1094 bawrite(struct buf *bp) 1095 { 1096 1097 bp->b_flags |= B_ASYNC; 1098 (void) bwrite(bp); 1099 } 1100 1101 /* 1102 * bwillwrite: 1103 * 1104 * Called prior to the locking of any vnodes when we are expecting to 1105 * write. We do not want to starve the buffer cache with too many 1106 * dirty buffers so we block here. By blocking prior to the locking 1107 * of any vnodes we attempt to avoid the situation where a locked vnode 1108 * prevents the various system daemons from flushing related buffers. 1109 */ 1110 1111 void 1112 bwillwrite(void) 1113 { 1114 1115 if (numdirtybuffers >= hidirtybuffers) { 1116 mtx_lock(&nblock); 1117 while (numdirtybuffers >= hidirtybuffers) { 1118 bd_wakeup(1); 1119 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1120 msleep(&needsbuffer, &nblock, 1121 (PRIBIO + 4), "flswai", 0); 1122 } 1123 mtx_unlock(&nblock); 1124 } 1125 } 1126 1127 /* 1128 * Return true if we have too many dirty buffers. 1129 */ 1130 int 1131 buf_dirty_count_severe(void) 1132 { 1133 1134 return(numdirtybuffers >= hidirtybuffers); 1135 } 1136 1137 /* 1138 * brelse: 1139 * 1140 * Release a busy buffer and, if requested, free its resources. The 1141 * buffer will be stashed in the appropriate bufqueue[] allowing it 1142 * to be accessed later as a cache entity or reused for other purposes. 1143 */ 1144 void 1145 brelse(struct buf *bp) 1146 { 1147 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1148 bp, bp->b_vp, bp->b_flags); 1149 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1150 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1151 1152 if (bp->b_flags & B_MANAGED) { 1153 bqrelse(bp); 1154 return; 1155 } 1156 1157 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1158 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1159 /* 1160 * Failed write, redirty. Must clear BIO_ERROR to prevent 1161 * pages from being scrapped. If the error is anything 1162 * other than an I/O error (EIO), assume that retryingi 1163 * is futile. 1164 */ 1165 bp->b_ioflags &= ~BIO_ERROR; 1166 bdirty(bp); 1167 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1168 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1169 /* 1170 * Either a failed I/O or we were asked to free or not 1171 * cache the buffer. 1172 */ 1173 bp->b_flags |= B_INVAL; 1174 if (!LIST_EMPTY(&bp->b_dep)) 1175 buf_deallocate(bp); 1176 if (bp->b_flags & B_DELWRI) { 1177 atomic_subtract_int(&numdirtybuffers, 1); 1178 numdirtywakeup(lodirtybuffers); 1179 } 1180 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1181 if ((bp->b_flags & B_VMIO) == 0) { 1182 if (bp->b_bufsize) 1183 allocbuf(bp, 0); 1184 if (bp->b_vp) 1185 brelvp(bp); 1186 } 1187 } 1188 1189 /* 1190 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1191 * is called with B_DELWRI set, the underlying pages may wind up 1192 * getting freed causing a previous write (bdwrite()) to get 'lost' 1193 * because pages associated with a B_DELWRI bp are marked clean. 1194 * 1195 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1196 * if B_DELWRI is set. 1197 * 1198 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1199 * on pages to return pages to the VM page queues. 1200 */ 1201 if (bp->b_flags & B_DELWRI) 1202 bp->b_flags &= ~B_RELBUF; 1203 else if (vm_page_count_severe()) { 1204 /* 1205 * The locking of the BO_LOCK is not necessary since 1206 * BKGRDINPROG cannot be set while we hold the buf 1207 * lock, it can only be cleared if it is already 1208 * pending. 1209 */ 1210 if (bp->b_vp) { 1211 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1212 bp->b_flags |= B_RELBUF; 1213 } else 1214 bp->b_flags |= B_RELBUF; 1215 } 1216 1217 /* 1218 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1219 * constituted, not even NFS buffers now. Two flags effect this. If 1220 * B_INVAL, the struct buf is invalidated but the VM object is kept 1221 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1222 * 1223 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1224 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1225 * buffer is also B_INVAL because it hits the re-dirtying code above. 1226 * 1227 * Normally we can do this whether a buffer is B_DELWRI or not. If 1228 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1229 * the commit state and we cannot afford to lose the buffer. If the 1230 * buffer has a background write in progress, we need to keep it 1231 * around to prevent it from being reconstituted and starting a second 1232 * background write. 1233 */ 1234 if ((bp->b_flags & B_VMIO) 1235 && !(bp->b_vp->v_mount != NULL && 1236 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1237 !vn_isdisk(bp->b_vp, NULL) && 1238 (bp->b_flags & B_DELWRI)) 1239 ) { 1240 1241 int i, j, resid; 1242 vm_page_t m; 1243 off_t foff; 1244 vm_pindex_t poff; 1245 vm_object_t obj; 1246 1247 obj = bp->b_bufobj->bo_object; 1248 1249 /* 1250 * Get the base offset and length of the buffer. Note that 1251 * in the VMIO case if the buffer block size is not 1252 * page-aligned then b_data pointer may not be page-aligned. 1253 * But our b_pages[] array *IS* page aligned. 1254 * 1255 * block sizes less then DEV_BSIZE (usually 512) are not 1256 * supported due to the page granularity bits (m->valid, 1257 * m->dirty, etc...). 1258 * 1259 * See man buf(9) for more information 1260 */ 1261 resid = bp->b_bufsize; 1262 foff = bp->b_offset; 1263 VM_OBJECT_LOCK(obj); 1264 for (i = 0; i < bp->b_npages; i++) { 1265 int had_bogus = 0; 1266 1267 m = bp->b_pages[i]; 1268 1269 /* 1270 * If we hit a bogus page, fixup *all* the bogus pages 1271 * now. 1272 */ 1273 if (m == bogus_page) { 1274 poff = OFF_TO_IDX(bp->b_offset); 1275 had_bogus = 1; 1276 1277 for (j = i; j < bp->b_npages; j++) { 1278 vm_page_t mtmp; 1279 mtmp = bp->b_pages[j]; 1280 if (mtmp == bogus_page) { 1281 mtmp = vm_page_lookup(obj, poff + j); 1282 if (!mtmp) { 1283 panic("brelse: page missing\n"); 1284 } 1285 bp->b_pages[j] = mtmp; 1286 } 1287 } 1288 1289 if ((bp->b_flags & B_INVAL) == 0) { 1290 pmap_qenter( 1291 trunc_page((vm_offset_t)bp->b_data), 1292 bp->b_pages, bp->b_npages); 1293 } 1294 m = bp->b_pages[i]; 1295 } 1296 if ((bp->b_flags & B_NOCACHE) || 1297 (bp->b_ioflags & BIO_ERROR)) { 1298 int poffset = foff & PAGE_MASK; 1299 int presid = resid > (PAGE_SIZE - poffset) ? 1300 (PAGE_SIZE - poffset) : resid; 1301 1302 KASSERT(presid >= 0, ("brelse: extra page")); 1303 vm_page_lock_queues(); 1304 vm_page_set_invalid(m, poffset, presid); 1305 vm_page_unlock_queues(); 1306 if (had_bogus) 1307 printf("avoided corruption bug in bogus_page/brelse code\n"); 1308 } 1309 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1310 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1311 } 1312 VM_OBJECT_UNLOCK(obj); 1313 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1314 vfs_vmio_release(bp); 1315 1316 } else if (bp->b_flags & B_VMIO) { 1317 1318 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1319 vfs_vmio_release(bp); 1320 } 1321 1322 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1323 if (bp->b_bufsize != 0) 1324 allocbuf(bp, 0); 1325 if (bp->b_vp != NULL) 1326 brelvp(bp); 1327 } 1328 1329 if (BUF_LOCKRECURSED(bp)) { 1330 /* do not release to free list */ 1331 BUF_UNLOCK(bp); 1332 return; 1333 } 1334 1335 /* enqueue */ 1336 mtx_lock(&bqlock); 1337 /* Handle delayed bremfree() processing. */ 1338 if (bp->b_flags & B_REMFREE) 1339 bremfreel(bp); 1340 if (bp->b_qindex != QUEUE_NONE) 1341 panic("brelse: free buffer onto another queue???"); 1342 1343 /* buffers with no memory */ 1344 if (bp->b_bufsize == 0) { 1345 bp->b_flags |= B_INVAL; 1346 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1347 if (bp->b_vflags & BV_BKGRDINPROG) 1348 panic("losing buffer 1"); 1349 if (bp->b_kvasize) { 1350 bp->b_qindex = QUEUE_EMPTYKVA; 1351 } else { 1352 bp->b_qindex = QUEUE_EMPTY; 1353 } 1354 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1355 /* buffers with junk contents */ 1356 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1357 (bp->b_ioflags & BIO_ERROR)) { 1358 bp->b_flags |= B_INVAL; 1359 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1360 if (bp->b_vflags & BV_BKGRDINPROG) 1361 panic("losing buffer 2"); 1362 bp->b_qindex = QUEUE_CLEAN; 1363 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1364 /* remaining buffers */ 1365 } else { 1366 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1367 (B_DELWRI|B_NEEDSGIANT)) 1368 bp->b_qindex = QUEUE_DIRTY_GIANT; 1369 if (bp->b_flags & B_DELWRI) 1370 bp->b_qindex = QUEUE_DIRTY; 1371 else 1372 bp->b_qindex = QUEUE_CLEAN; 1373 if (bp->b_flags & B_AGE) 1374 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1375 else 1376 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1377 } 1378 mtx_unlock(&bqlock); 1379 1380 /* 1381 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1382 * placed the buffer on the correct queue. We must also disassociate 1383 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1384 * find it. 1385 */ 1386 if (bp->b_flags & B_INVAL) { 1387 if (bp->b_flags & B_DELWRI) 1388 bundirty(bp); 1389 if (bp->b_vp) 1390 brelvp(bp); 1391 } 1392 1393 /* 1394 * Fixup numfreebuffers count. The bp is on an appropriate queue 1395 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1396 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1397 * if B_INVAL is set ). 1398 */ 1399 1400 if (!(bp->b_flags & B_DELWRI)) 1401 bufcountwakeup(); 1402 1403 /* 1404 * Something we can maybe free or reuse 1405 */ 1406 if (bp->b_bufsize || bp->b_kvasize) 1407 bufspacewakeup(); 1408 1409 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1410 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1411 panic("brelse: not dirty"); 1412 /* unlock */ 1413 BUF_UNLOCK(bp); 1414 } 1415 1416 /* 1417 * Release a buffer back to the appropriate queue but do not try to free 1418 * it. The buffer is expected to be used again soon. 1419 * 1420 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1421 * biodone() to requeue an async I/O on completion. It is also used when 1422 * known good buffers need to be requeued but we think we may need the data 1423 * again soon. 1424 * 1425 * XXX we should be able to leave the B_RELBUF hint set on completion. 1426 */ 1427 void 1428 bqrelse(struct buf *bp) 1429 { 1430 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1431 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1432 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1433 1434 if (BUF_LOCKRECURSED(bp)) { 1435 /* do not release to free list */ 1436 BUF_UNLOCK(bp); 1437 return; 1438 } 1439 1440 if (bp->b_flags & B_MANAGED) { 1441 if (bp->b_flags & B_REMFREE) { 1442 mtx_lock(&bqlock); 1443 bremfreel(bp); 1444 mtx_unlock(&bqlock); 1445 } 1446 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1447 BUF_UNLOCK(bp); 1448 return; 1449 } 1450 1451 mtx_lock(&bqlock); 1452 /* Handle delayed bremfree() processing. */ 1453 if (bp->b_flags & B_REMFREE) 1454 bremfreel(bp); 1455 if (bp->b_qindex != QUEUE_NONE) 1456 panic("bqrelse: free buffer onto another queue???"); 1457 /* buffers with stale but valid contents */ 1458 if (bp->b_flags & B_DELWRI) { 1459 if (bp->b_flags & B_NEEDSGIANT) 1460 bp->b_qindex = QUEUE_DIRTY_GIANT; 1461 else 1462 bp->b_qindex = QUEUE_DIRTY; 1463 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1464 } else { 1465 /* 1466 * The locking of the BO_LOCK for checking of the 1467 * BV_BKGRDINPROG is not necessary since the 1468 * BV_BKGRDINPROG cannot be set while we hold the buf 1469 * lock, it can only be cleared if it is already 1470 * pending. 1471 */ 1472 if (!vm_page_count_severe() || (bp->b_vflags & BV_BKGRDINPROG)) { 1473 bp->b_qindex = QUEUE_CLEAN; 1474 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1475 b_freelist); 1476 } else { 1477 /* 1478 * We are too low on memory, we have to try to free 1479 * the buffer (most importantly: the wired pages 1480 * making up its backing store) *now*. 1481 */ 1482 mtx_unlock(&bqlock); 1483 brelse(bp); 1484 return; 1485 } 1486 } 1487 mtx_unlock(&bqlock); 1488 1489 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1490 bufcountwakeup(); 1491 1492 /* 1493 * Something we can maybe free or reuse. 1494 */ 1495 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1496 bufspacewakeup(); 1497 1498 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1499 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1500 panic("bqrelse: not dirty"); 1501 /* unlock */ 1502 BUF_UNLOCK(bp); 1503 } 1504 1505 /* Give pages used by the bp back to the VM system (where possible) */ 1506 static void 1507 vfs_vmio_release(struct buf *bp) 1508 { 1509 int i; 1510 vm_page_t m; 1511 1512 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1513 vm_page_lock_queues(); 1514 for (i = 0; i < bp->b_npages; i++) { 1515 m = bp->b_pages[i]; 1516 bp->b_pages[i] = NULL; 1517 /* 1518 * In order to keep page LRU ordering consistent, put 1519 * everything on the inactive queue. 1520 */ 1521 vm_page_unwire(m, 0); 1522 /* 1523 * We don't mess with busy pages, it is 1524 * the responsibility of the process that 1525 * busied the pages to deal with them. 1526 */ 1527 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1528 continue; 1529 1530 if (m->wire_count == 0) { 1531 /* 1532 * Might as well free the page if we can and it has 1533 * no valid data. We also free the page if the 1534 * buffer was used for direct I/O 1535 */ 1536 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1537 m->hold_count == 0) { 1538 vm_page_free(m); 1539 } else if (bp->b_flags & B_DIRECT) { 1540 vm_page_try_to_free(m); 1541 } else if (vm_page_count_severe()) { 1542 vm_page_try_to_cache(m); 1543 } 1544 } 1545 } 1546 vm_page_unlock_queues(); 1547 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1548 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1549 1550 if (bp->b_bufsize) { 1551 bufspacewakeup(); 1552 bp->b_bufsize = 0; 1553 } 1554 bp->b_npages = 0; 1555 bp->b_flags &= ~B_VMIO; 1556 if (bp->b_vp) 1557 brelvp(bp); 1558 } 1559 1560 /* 1561 * Check to see if a block at a particular lbn is available for a clustered 1562 * write. 1563 */ 1564 static int 1565 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1566 { 1567 struct buf *bpa; 1568 int match; 1569 1570 match = 0; 1571 1572 /* If the buf isn't in core skip it */ 1573 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1574 return (0); 1575 1576 /* If the buf is busy we don't want to wait for it */ 1577 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1578 return (0); 1579 1580 /* Only cluster with valid clusterable delayed write buffers */ 1581 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1582 (B_DELWRI | B_CLUSTEROK)) 1583 goto done; 1584 1585 if (bpa->b_bufsize != size) 1586 goto done; 1587 1588 /* 1589 * Check to see if it is in the expected place on disk and that the 1590 * block has been mapped. 1591 */ 1592 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1593 match = 1; 1594 done: 1595 BUF_UNLOCK(bpa); 1596 return (match); 1597 } 1598 1599 /* 1600 * vfs_bio_awrite: 1601 * 1602 * Implement clustered async writes for clearing out B_DELWRI buffers. 1603 * This is much better then the old way of writing only one buffer at 1604 * a time. Note that we may not be presented with the buffers in the 1605 * correct order, so we search for the cluster in both directions. 1606 */ 1607 int 1608 vfs_bio_awrite(struct buf *bp) 1609 { 1610 struct bufobj *bo; 1611 int i; 1612 int j; 1613 daddr_t lblkno = bp->b_lblkno; 1614 struct vnode *vp = bp->b_vp; 1615 int ncl; 1616 int nwritten; 1617 int size; 1618 int maxcl; 1619 1620 bo = &vp->v_bufobj; 1621 /* 1622 * right now we support clustered writing only to regular files. If 1623 * we find a clusterable block we could be in the middle of a cluster 1624 * rather then at the beginning. 1625 */ 1626 if ((vp->v_type == VREG) && 1627 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1628 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1629 1630 size = vp->v_mount->mnt_stat.f_iosize; 1631 maxcl = MAXPHYS / size; 1632 1633 BO_LOCK(bo); 1634 for (i = 1; i < maxcl; i++) 1635 if (vfs_bio_clcheck(vp, size, lblkno + i, 1636 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1637 break; 1638 1639 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1640 if (vfs_bio_clcheck(vp, size, lblkno - j, 1641 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1642 break; 1643 BO_UNLOCK(bo); 1644 --j; 1645 ncl = i + j; 1646 /* 1647 * this is a possible cluster write 1648 */ 1649 if (ncl != 1) { 1650 BUF_UNLOCK(bp); 1651 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1652 return nwritten; 1653 } 1654 } 1655 bremfree(bp); 1656 bp->b_flags |= B_ASYNC; 1657 /* 1658 * default (old) behavior, writing out only one block 1659 * 1660 * XXX returns b_bufsize instead of b_bcount for nwritten? 1661 */ 1662 nwritten = bp->b_bufsize; 1663 (void) bwrite(bp); 1664 1665 return nwritten; 1666 } 1667 1668 /* 1669 * getnewbuf: 1670 * 1671 * Find and initialize a new buffer header, freeing up existing buffers 1672 * in the bufqueues as necessary. The new buffer is returned locked. 1673 * 1674 * Important: B_INVAL is not set. If the caller wishes to throw the 1675 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1676 * 1677 * We block if: 1678 * We have insufficient buffer headers 1679 * We have insufficient buffer space 1680 * buffer_map is too fragmented ( space reservation fails ) 1681 * If we have to flush dirty buffers ( but we try to avoid this ) 1682 * 1683 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1684 * Instead we ask the buf daemon to do it for us. We attempt to 1685 * avoid piecemeal wakeups of the pageout daemon. 1686 */ 1687 1688 static struct buf * 1689 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1690 { 1691 struct buf *bp; 1692 struct buf *nbp; 1693 int defrag = 0; 1694 int nqindex; 1695 static int flushingbufs; 1696 1697 /* 1698 * We can't afford to block since we might be holding a vnode lock, 1699 * which may prevent system daemons from running. We deal with 1700 * low-memory situations by proactively returning memory and running 1701 * async I/O rather then sync I/O. 1702 */ 1703 1704 atomic_add_int(&getnewbufcalls, 1); 1705 atomic_subtract_int(&getnewbufrestarts, 1); 1706 restart: 1707 atomic_add_int(&getnewbufrestarts, 1); 1708 1709 /* 1710 * Setup for scan. If we do not have enough free buffers, 1711 * we setup a degenerate case that immediately fails. Note 1712 * that if we are specially marked process, we are allowed to 1713 * dip into our reserves. 1714 * 1715 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1716 * 1717 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1718 * However, there are a number of cases (defragging, reusing, ...) 1719 * where we cannot backup. 1720 */ 1721 mtx_lock(&bqlock); 1722 nqindex = QUEUE_EMPTYKVA; 1723 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1724 1725 if (nbp == NULL) { 1726 /* 1727 * If no EMPTYKVA buffers and we are either 1728 * defragging or reusing, locate a CLEAN buffer 1729 * to free or reuse. If bufspace useage is low 1730 * skip this step so we can allocate a new buffer. 1731 */ 1732 if (defrag || bufspace >= lobufspace) { 1733 nqindex = QUEUE_CLEAN; 1734 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1735 } 1736 1737 /* 1738 * If we could not find or were not allowed to reuse a 1739 * CLEAN buffer, check to see if it is ok to use an EMPTY 1740 * buffer. We can only use an EMPTY buffer if allocating 1741 * its KVA would not otherwise run us out of buffer space. 1742 */ 1743 if (nbp == NULL && defrag == 0 && 1744 bufspace + maxsize < hibufspace) { 1745 nqindex = QUEUE_EMPTY; 1746 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1747 } 1748 } 1749 1750 /* 1751 * Run scan, possibly freeing data and/or kva mappings on the fly 1752 * depending. 1753 */ 1754 1755 while ((bp = nbp) != NULL) { 1756 int qindex = nqindex; 1757 1758 /* 1759 * Calculate next bp ( we can only use it if we do not block 1760 * or do other fancy things ). 1761 */ 1762 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1763 switch(qindex) { 1764 case QUEUE_EMPTY: 1765 nqindex = QUEUE_EMPTYKVA; 1766 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1767 break; 1768 /* FALLTHROUGH */ 1769 case QUEUE_EMPTYKVA: 1770 nqindex = QUEUE_CLEAN; 1771 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1772 break; 1773 /* FALLTHROUGH */ 1774 case QUEUE_CLEAN: 1775 /* 1776 * nbp is NULL. 1777 */ 1778 break; 1779 } 1780 } 1781 /* 1782 * If we are defragging then we need a buffer with 1783 * b_kvasize != 0. XXX this situation should no longer 1784 * occur, if defrag is non-zero the buffer's b_kvasize 1785 * should also be non-zero at this point. XXX 1786 */ 1787 if (defrag && bp->b_kvasize == 0) { 1788 printf("Warning: defrag empty buffer %p\n", bp); 1789 continue; 1790 } 1791 1792 /* 1793 * Start freeing the bp. This is somewhat involved. nbp 1794 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1795 */ 1796 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1797 continue; 1798 if (bp->b_vp) { 1799 BO_LOCK(bp->b_bufobj); 1800 if (bp->b_vflags & BV_BKGRDINPROG) { 1801 BO_UNLOCK(bp->b_bufobj); 1802 BUF_UNLOCK(bp); 1803 continue; 1804 } 1805 BO_UNLOCK(bp->b_bufobj); 1806 } 1807 CTR6(KTR_BUF, 1808 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1809 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1810 bp->b_kvasize, bp->b_bufsize, qindex); 1811 1812 /* 1813 * Sanity Checks 1814 */ 1815 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1816 1817 /* 1818 * Note: we no longer distinguish between VMIO and non-VMIO 1819 * buffers. 1820 */ 1821 1822 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1823 1824 bremfreel(bp); 1825 mtx_unlock(&bqlock); 1826 1827 if (qindex == QUEUE_CLEAN) { 1828 if (bp->b_flags & B_VMIO) { 1829 bp->b_flags &= ~B_ASYNC; 1830 vfs_vmio_release(bp); 1831 } 1832 if (bp->b_vp) 1833 brelvp(bp); 1834 } 1835 1836 /* 1837 * NOTE: nbp is now entirely invalid. We can only restart 1838 * the scan from this point on. 1839 * 1840 * Get the rest of the buffer freed up. b_kva* is still 1841 * valid after this operation. 1842 */ 1843 1844 if (bp->b_rcred != NOCRED) { 1845 crfree(bp->b_rcred); 1846 bp->b_rcred = NOCRED; 1847 } 1848 if (bp->b_wcred != NOCRED) { 1849 crfree(bp->b_wcred); 1850 bp->b_wcred = NOCRED; 1851 } 1852 if (!LIST_EMPTY(&bp->b_dep)) 1853 buf_deallocate(bp); 1854 if (bp->b_vflags & BV_BKGRDINPROG) 1855 panic("losing buffer 3"); 1856 KASSERT(bp->b_vp == NULL, 1857 ("bp: %p still has vnode %p. qindex: %d", 1858 bp, bp->b_vp, qindex)); 1859 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1860 ("bp: %p still on a buffer list. xflags %X", 1861 bp, bp->b_xflags)); 1862 1863 if (bp->b_bufsize) 1864 allocbuf(bp, 0); 1865 1866 bp->b_flags = 0; 1867 bp->b_ioflags = 0; 1868 bp->b_xflags = 0; 1869 bp->b_vflags = 0; 1870 bp->b_vp = NULL; 1871 bp->b_blkno = bp->b_lblkno = 0; 1872 bp->b_offset = NOOFFSET; 1873 bp->b_iodone = 0; 1874 bp->b_error = 0; 1875 bp->b_resid = 0; 1876 bp->b_bcount = 0; 1877 bp->b_npages = 0; 1878 bp->b_dirtyoff = bp->b_dirtyend = 0; 1879 bp->b_bufobj = NULL; 1880 bp->b_pin_count = 0; 1881 bp->b_fsprivate1 = NULL; 1882 bp->b_fsprivate2 = NULL; 1883 bp->b_fsprivate3 = NULL; 1884 1885 LIST_INIT(&bp->b_dep); 1886 1887 /* 1888 * If we are defragging then free the buffer. 1889 */ 1890 if (defrag) { 1891 bp->b_flags |= B_INVAL; 1892 bfreekva(bp); 1893 brelse(bp); 1894 defrag = 0; 1895 goto restart; 1896 } 1897 1898 /* 1899 * Notify any waiters for the buffer lock about 1900 * identity change by freeing the buffer. 1901 */ 1902 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp)) { 1903 bp->b_flags |= B_INVAL; 1904 bfreekva(bp); 1905 brelse(bp); 1906 goto restart; 1907 } 1908 1909 /* 1910 * If we are overcomitted then recover the buffer and its 1911 * KVM space. This occurs in rare situations when multiple 1912 * processes are blocked in getnewbuf() or allocbuf(). 1913 */ 1914 if (bufspace >= hibufspace) 1915 flushingbufs = 1; 1916 if (flushingbufs && bp->b_kvasize != 0) { 1917 bp->b_flags |= B_INVAL; 1918 bfreekva(bp); 1919 brelse(bp); 1920 goto restart; 1921 } 1922 if (bufspace < lobufspace) 1923 flushingbufs = 0; 1924 break; 1925 } 1926 1927 /* 1928 * If we exhausted our list, sleep as appropriate. We may have to 1929 * wakeup various daemons and write out some dirty buffers. 1930 * 1931 * Generally we are sleeping due to insufficient buffer space. 1932 */ 1933 1934 if (bp == NULL) { 1935 int flags; 1936 char *waitmsg; 1937 1938 if (defrag) { 1939 flags = VFS_BIO_NEED_BUFSPACE; 1940 waitmsg = "nbufkv"; 1941 } else if (bufspace >= hibufspace) { 1942 waitmsg = "nbufbs"; 1943 flags = VFS_BIO_NEED_BUFSPACE; 1944 } else { 1945 waitmsg = "newbuf"; 1946 flags = VFS_BIO_NEED_ANY; 1947 } 1948 mtx_lock(&nblock); 1949 needsbuffer |= flags; 1950 mtx_unlock(&nblock); 1951 mtx_unlock(&bqlock); 1952 1953 bd_speedup(); /* heeeelp */ 1954 1955 mtx_lock(&nblock); 1956 while (needsbuffer & flags) { 1957 if (msleep(&needsbuffer, &nblock, 1958 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1959 mtx_unlock(&nblock); 1960 return (NULL); 1961 } 1962 } 1963 mtx_unlock(&nblock); 1964 } else { 1965 /* 1966 * We finally have a valid bp. We aren't quite out of the 1967 * woods, we still have to reserve kva space. In order 1968 * to keep fragmentation sane we only allocate kva in 1969 * BKVASIZE chunks. 1970 */ 1971 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1972 1973 if (maxsize != bp->b_kvasize) { 1974 vm_offset_t addr = 0; 1975 1976 bfreekva(bp); 1977 1978 vm_map_lock(buffer_map); 1979 if (vm_map_findspace(buffer_map, 1980 vm_map_min(buffer_map), maxsize, &addr)) { 1981 /* 1982 * Uh oh. Buffer map is to fragmented. We 1983 * must defragment the map. 1984 */ 1985 atomic_add_int(&bufdefragcnt, 1); 1986 vm_map_unlock(buffer_map); 1987 defrag = 1; 1988 bp->b_flags |= B_INVAL; 1989 brelse(bp); 1990 goto restart; 1991 } 1992 if (addr) { 1993 vm_map_insert(buffer_map, NULL, 0, 1994 addr, addr + maxsize, 1995 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1996 1997 bp->b_kvabase = (caddr_t) addr; 1998 bp->b_kvasize = maxsize; 1999 atomic_add_int(&bufspace, bp->b_kvasize); 2000 atomic_add_int(&bufreusecnt, 1); 2001 } 2002 vm_map_unlock(buffer_map); 2003 } 2004 bp->b_saveaddr = bp->b_kvabase; 2005 bp->b_data = bp->b_saveaddr; 2006 } 2007 return(bp); 2008 } 2009 2010 /* 2011 * buf_daemon: 2012 * 2013 * buffer flushing daemon. Buffers are normally flushed by the 2014 * update daemon but if it cannot keep up this process starts to 2015 * take the load in an attempt to prevent getnewbuf() from blocking. 2016 */ 2017 2018 static struct kproc_desc buf_kp = { 2019 "bufdaemon", 2020 buf_daemon, 2021 &bufdaemonproc 2022 }; 2023 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp); 2024 2025 static void 2026 buf_daemon() 2027 { 2028 2029 /* 2030 * This process needs to be suspended prior to shutdown sync. 2031 */ 2032 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2033 SHUTDOWN_PRI_LAST); 2034 2035 /* 2036 * This process is allowed to take the buffer cache to the limit 2037 */ 2038 curthread->td_pflags |= TDP_NORUNNINGBUF; 2039 mtx_lock(&bdlock); 2040 for (;;) { 2041 bd_request = 0; 2042 mtx_unlock(&bdlock); 2043 2044 kproc_suspend_check(bufdaemonproc); 2045 2046 /* 2047 * Do the flush. Limit the amount of in-transit I/O we 2048 * allow to build up, otherwise we would completely saturate 2049 * the I/O system. Wakeup any waiting processes before we 2050 * normally would so they can run in parallel with our drain. 2051 */ 2052 while (numdirtybuffers > lodirtybuffers) { 2053 int flushed; 2054 2055 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2056 /* The list empty check here is slightly racy */ 2057 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2058 mtx_lock(&Giant); 2059 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2060 mtx_unlock(&Giant); 2061 } 2062 if (flushed == 0) { 2063 /* 2064 * Could not find any buffers without rollback 2065 * dependencies, so just write the first one 2066 * in the hopes of eventually making progress. 2067 */ 2068 flushbufqueues(QUEUE_DIRTY, 1); 2069 if (!TAILQ_EMPTY( 2070 &bufqueues[QUEUE_DIRTY_GIANT])) { 2071 mtx_lock(&Giant); 2072 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2073 mtx_unlock(&Giant); 2074 } 2075 break; 2076 } 2077 uio_yield(); 2078 } 2079 2080 /* 2081 * Only clear bd_request if we have reached our low water 2082 * mark. The buf_daemon normally waits 1 second and 2083 * then incrementally flushes any dirty buffers that have 2084 * built up, within reason. 2085 * 2086 * If we were unable to hit our low water mark and couldn't 2087 * find any flushable buffers, we sleep half a second. 2088 * Otherwise we loop immediately. 2089 */ 2090 mtx_lock(&bdlock); 2091 if (numdirtybuffers <= lodirtybuffers) { 2092 /* 2093 * We reached our low water mark, reset the 2094 * request and sleep until we are needed again. 2095 * The sleep is just so the suspend code works. 2096 */ 2097 bd_request = 0; 2098 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2099 } else { 2100 /* 2101 * We couldn't find any flushable dirty buffers but 2102 * still have too many dirty buffers, we 2103 * have to sleep and try again. (rare) 2104 */ 2105 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2106 } 2107 } 2108 } 2109 2110 /* 2111 * flushbufqueues: 2112 * 2113 * Try to flush a buffer in the dirty queue. We must be careful to 2114 * free up B_INVAL buffers instead of write them, which NFS is 2115 * particularly sensitive to. 2116 */ 2117 static int flushwithdeps = 0; 2118 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2119 0, "Number of buffers flushed with dependecies that require rollbacks"); 2120 2121 static int 2122 flushbufqueues(int queue, int flushdeps) 2123 { 2124 struct buf sentinel; 2125 struct vnode *vp; 2126 struct mount *mp; 2127 struct buf *bp; 2128 int hasdeps; 2129 int flushed; 2130 int target; 2131 2132 target = numdirtybuffers - lodirtybuffers; 2133 if (flushdeps && target > 2) 2134 target /= 2; 2135 flushed = 0; 2136 bp = NULL; 2137 mtx_lock(&bqlock); 2138 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2139 while (flushed != target) { 2140 bp = TAILQ_FIRST(&bufqueues[queue]); 2141 if (bp == &sentinel) 2142 break; 2143 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2144 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2145 2146 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2147 continue; 2148 if (bp->b_pin_count > 0) { 2149 BUF_UNLOCK(bp); 2150 continue; 2151 } 2152 BO_LOCK(bp->b_bufobj); 2153 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2154 (bp->b_flags & B_DELWRI) == 0) { 2155 BO_UNLOCK(bp->b_bufobj); 2156 BUF_UNLOCK(bp); 2157 continue; 2158 } 2159 BO_UNLOCK(bp->b_bufobj); 2160 if (bp->b_flags & B_INVAL) { 2161 bremfreel(bp); 2162 mtx_unlock(&bqlock); 2163 brelse(bp); 2164 flushed++; 2165 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2166 mtx_lock(&bqlock); 2167 continue; 2168 } 2169 2170 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2171 if (flushdeps == 0) { 2172 BUF_UNLOCK(bp); 2173 continue; 2174 } 2175 hasdeps = 1; 2176 } else 2177 hasdeps = 0; 2178 /* 2179 * We must hold the lock on a vnode before writing 2180 * one of its buffers. Otherwise we may confuse, or 2181 * in the case of a snapshot vnode, deadlock the 2182 * system. 2183 * 2184 * The lock order here is the reverse of the normal 2185 * of vnode followed by buf lock. This is ok because 2186 * the NOWAIT will prevent deadlock. 2187 */ 2188 vp = bp->b_vp; 2189 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2190 BUF_UNLOCK(bp); 2191 continue; 2192 } 2193 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 2194 mtx_unlock(&bqlock); 2195 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2196 bp, bp->b_vp, bp->b_flags); 2197 vfs_bio_awrite(bp); 2198 vn_finished_write(mp); 2199 VOP_UNLOCK(vp, 0); 2200 flushwithdeps += hasdeps; 2201 flushed++; 2202 waitrunningbufspace(); 2203 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2204 mtx_lock(&bqlock); 2205 continue; 2206 } 2207 vn_finished_write(mp); 2208 BUF_UNLOCK(bp); 2209 } 2210 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2211 mtx_unlock(&bqlock); 2212 return (flushed); 2213 } 2214 2215 /* 2216 * Check to see if a block is currently memory resident. 2217 */ 2218 struct buf * 2219 incore(struct bufobj *bo, daddr_t blkno) 2220 { 2221 struct buf *bp; 2222 2223 BO_LOCK(bo); 2224 bp = gbincore(bo, blkno); 2225 BO_UNLOCK(bo); 2226 return (bp); 2227 } 2228 2229 /* 2230 * Returns true if no I/O is needed to access the 2231 * associated VM object. This is like incore except 2232 * it also hunts around in the VM system for the data. 2233 */ 2234 2235 static int 2236 inmem(struct vnode * vp, daddr_t blkno) 2237 { 2238 vm_object_t obj; 2239 vm_offset_t toff, tinc, size; 2240 vm_page_t m; 2241 vm_ooffset_t off; 2242 2243 ASSERT_VOP_LOCKED(vp, "inmem"); 2244 2245 if (incore(&vp->v_bufobj, blkno)) 2246 return 1; 2247 if (vp->v_mount == NULL) 2248 return 0; 2249 obj = vp->v_object; 2250 if (obj == NULL) 2251 return (0); 2252 2253 size = PAGE_SIZE; 2254 if (size > vp->v_mount->mnt_stat.f_iosize) 2255 size = vp->v_mount->mnt_stat.f_iosize; 2256 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2257 2258 VM_OBJECT_LOCK(obj); 2259 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2260 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2261 if (!m) 2262 goto notinmem; 2263 tinc = size; 2264 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2265 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2266 if (vm_page_is_valid(m, 2267 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2268 goto notinmem; 2269 } 2270 VM_OBJECT_UNLOCK(obj); 2271 return 1; 2272 2273 notinmem: 2274 VM_OBJECT_UNLOCK(obj); 2275 return (0); 2276 } 2277 2278 /* 2279 * vfs_setdirty: 2280 * 2281 * Sets the dirty range for a buffer based on the status of the dirty 2282 * bits in the pages comprising the buffer. 2283 * 2284 * The range is limited to the size of the buffer. 2285 * 2286 * This routine is primarily used by NFS, but is generalized for the 2287 * B_VMIO case. 2288 */ 2289 static void 2290 vfs_setdirty(struct buf *bp) 2291 { 2292 2293 /* 2294 * Degenerate case - empty buffer 2295 */ 2296 2297 if (bp->b_bufsize == 0) 2298 return; 2299 2300 /* 2301 * We qualify the scan for modified pages on whether the 2302 * object has been flushed yet. 2303 */ 2304 2305 if ((bp->b_flags & B_VMIO) == 0) 2306 return; 2307 2308 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2309 vfs_setdirty_locked_object(bp); 2310 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2311 } 2312 2313 static void 2314 vfs_setdirty_locked_object(struct buf *bp) 2315 { 2316 vm_object_t object; 2317 int i; 2318 2319 object = bp->b_bufobj->bo_object; 2320 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2321 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2322 vm_offset_t boffset; 2323 vm_offset_t eoffset; 2324 2325 vm_page_lock_queues(); 2326 /* 2327 * test the pages to see if they have been modified directly 2328 * by users through the VM system. 2329 */ 2330 for (i = 0; i < bp->b_npages; i++) 2331 vm_page_test_dirty(bp->b_pages[i]); 2332 2333 /* 2334 * Calculate the encompassing dirty range, boffset and eoffset, 2335 * (eoffset - boffset) bytes. 2336 */ 2337 2338 for (i = 0; i < bp->b_npages; i++) { 2339 if (bp->b_pages[i]->dirty) 2340 break; 2341 } 2342 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2343 2344 for (i = bp->b_npages - 1; i >= 0; --i) { 2345 if (bp->b_pages[i]->dirty) { 2346 break; 2347 } 2348 } 2349 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2350 2351 vm_page_unlock_queues(); 2352 /* 2353 * Fit it to the buffer. 2354 */ 2355 2356 if (eoffset > bp->b_bcount) 2357 eoffset = bp->b_bcount; 2358 2359 /* 2360 * If we have a good dirty range, merge with the existing 2361 * dirty range. 2362 */ 2363 2364 if (boffset < eoffset) { 2365 if (bp->b_dirtyoff > boffset) 2366 bp->b_dirtyoff = boffset; 2367 if (bp->b_dirtyend < eoffset) 2368 bp->b_dirtyend = eoffset; 2369 } 2370 } 2371 } 2372 2373 /* 2374 * getblk: 2375 * 2376 * Get a block given a specified block and offset into a file/device. 2377 * The buffers B_DONE bit will be cleared on return, making it almost 2378 * ready for an I/O initiation. B_INVAL may or may not be set on 2379 * return. The caller should clear B_INVAL prior to initiating a 2380 * READ. 2381 * 2382 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2383 * an existing buffer. 2384 * 2385 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2386 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2387 * and then cleared based on the backing VM. If the previous buffer is 2388 * non-0-sized but invalid, B_CACHE will be cleared. 2389 * 2390 * If getblk() must create a new buffer, the new buffer is returned with 2391 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2392 * case it is returned with B_INVAL clear and B_CACHE set based on the 2393 * backing VM. 2394 * 2395 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2396 * B_CACHE bit is clear. 2397 * 2398 * What this means, basically, is that the caller should use B_CACHE to 2399 * determine whether the buffer is fully valid or not and should clear 2400 * B_INVAL prior to issuing a read. If the caller intends to validate 2401 * the buffer by loading its data area with something, the caller needs 2402 * to clear B_INVAL. If the caller does this without issuing an I/O, 2403 * the caller should set B_CACHE ( as an optimization ), else the caller 2404 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2405 * a write attempt or if it was a successfull read. If the caller 2406 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2407 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2408 */ 2409 struct buf * 2410 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2411 int flags) 2412 { 2413 struct buf *bp; 2414 struct bufobj *bo; 2415 int error; 2416 2417 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2418 ASSERT_VOP_LOCKED(vp, "getblk"); 2419 if (size > MAXBSIZE) 2420 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2421 2422 bo = &vp->v_bufobj; 2423 loop: 2424 /* 2425 * Block if we are low on buffers. Certain processes are allowed 2426 * to completely exhaust the buffer cache. 2427 * 2428 * If this check ever becomes a bottleneck it may be better to 2429 * move it into the else, when gbincore() fails. At the moment 2430 * it isn't a problem. 2431 * 2432 * XXX remove if 0 sections (clean this up after its proven) 2433 */ 2434 if (numfreebuffers == 0) { 2435 if (TD_IS_IDLETHREAD(curthread)) 2436 return NULL; 2437 mtx_lock(&nblock); 2438 needsbuffer |= VFS_BIO_NEED_ANY; 2439 mtx_unlock(&nblock); 2440 } 2441 2442 BO_LOCK(bo); 2443 bp = gbincore(bo, blkno); 2444 if (bp != NULL) { 2445 int lockflags; 2446 /* 2447 * Buffer is in-core. If the buffer is not busy, it must 2448 * be on a queue. 2449 */ 2450 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2451 2452 if (flags & GB_LOCK_NOWAIT) 2453 lockflags |= LK_NOWAIT; 2454 2455 error = BUF_TIMELOCK(bp, lockflags, 2456 BO_MTX(bo), "getblk", slpflag, slptimeo); 2457 2458 /* 2459 * If we slept and got the lock we have to restart in case 2460 * the buffer changed identities. 2461 */ 2462 if (error == ENOLCK) 2463 goto loop; 2464 /* We timed out or were interrupted. */ 2465 else if (error) 2466 return (NULL); 2467 2468 /* 2469 * The buffer is locked. B_CACHE is cleared if the buffer is 2470 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2471 * and for a VMIO buffer B_CACHE is adjusted according to the 2472 * backing VM cache. 2473 */ 2474 if (bp->b_flags & B_INVAL) 2475 bp->b_flags &= ~B_CACHE; 2476 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2477 bp->b_flags |= B_CACHE; 2478 bremfree(bp); 2479 2480 /* 2481 * check for size inconsistancies for non-VMIO case. 2482 */ 2483 2484 if (bp->b_bcount != size) { 2485 if ((bp->b_flags & B_VMIO) == 0 || 2486 (size > bp->b_kvasize)) { 2487 if (bp->b_flags & B_DELWRI) { 2488 /* 2489 * If buffer is pinned and caller does 2490 * not want sleep waiting for it to be 2491 * unpinned, bail out 2492 * */ 2493 if (bp->b_pin_count > 0) { 2494 if (flags & GB_LOCK_NOWAIT) { 2495 bqrelse(bp); 2496 return (NULL); 2497 } else { 2498 bunpin_wait(bp); 2499 } 2500 } 2501 bp->b_flags |= B_NOCACHE; 2502 bwrite(bp); 2503 } else { 2504 if (LIST_EMPTY(&bp->b_dep)) { 2505 bp->b_flags |= B_RELBUF; 2506 brelse(bp); 2507 } else { 2508 bp->b_flags |= B_NOCACHE; 2509 bwrite(bp); 2510 } 2511 } 2512 goto loop; 2513 } 2514 } 2515 2516 /* 2517 * If the size is inconsistant in the VMIO case, we can resize 2518 * the buffer. This might lead to B_CACHE getting set or 2519 * cleared. If the size has not changed, B_CACHE remains 2520 * unchanged from its previous state. 2521 */ 2522 2523 if (bp->b_bcount != size) 2524 allocbuf(bp, size); 2525 2526 KASSERT(bp->b_offset != NOOFFSET, 2527 ("getblk: no buffer offset")); 2528 2529 /* 2530 * A buffer with B_DELWRI set and B_CACHE clear must 2531 * be committed before we can return the buffer in 2532 * order to prevent the caller from issuing a read 2533 * ( due to B_CACHE not being set ) and overwriting 2534 * it. 2535 * 2536 * Most callers, including NFS and FFS, need this to 2537 * operate properly either because they assume they 2538 * can issue a read if B_CACHE is not set, or because 2539 * ( for example ) an uncached B_DELWRI might loop due 2540 * to softupdates re-dirtying the buffer. In the latter 2541 * case, B_CACHE is set after the first write completes, 2542 * preventing further loops. 2543 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2544 * above while extending the buffer, we cannot allow the 2545 * buffer to remain with B_CACHE set after the write 2546 * completes or it will represent a corrupt state. To 2547 * deal with this we set B_NOCACHE to scrap the buffer 2548 * after the write. 2549 * 2550 * We might be able to do something fancy, like setting 2551 * B_CACHE in bwrite() except if B_DELWRI is already set, 2552 * so the below call doesn't set B_CACHE, but that gets real 2553 * confusing. This is much easier. 2554 */ 2555 2556 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2557 bp->b_flags |= B_NOCACHE; 2558 bwrite(bp); 2559 goto loop; 2560 } 2561 bp->b_flags &= ~B_DONE; 2562 } else { 2563 int bsize, maxsize, vmio; 2564 off_t offset; 2565 2566 /* 2567 * Buffer is not in-core, create new buffer. The buffer 2568 * returned by getnewbuf() is locked. Note that the returned 2569 * buffer is also considered valid (not marked B_INVAL). 2570 */ 2571 BO_UNLOCK(bo); 2572 /* 2573 * If the user does not want us to create the buffer, bail out 2574 * here. 2575 */ 2576 if (flags & GB_NOCREAT) 2577 return NULL; 2578 bsize = bo->bo_bsize; 2579 offset = blkno * bsize; 2580 vmio = vp->v_object != NULL; 2581 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2582 maxsize = imax(maxsize, bsize); 2583 2584 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2585 if (bp == NULL) { 2586 if (slpflag || slptimeo) 2587 return NULL; 2588 goto loop; 2589 } 2590 2591 /* 2592 * This code is used to make sure that a buffer is not 2593 * created while the getnewbuf routine is blocked. 2594 * This can be a problem whether the vnode is locked or not. 2595 * If the buffer is created out from under us, we have to 2596 * throw away the one we just created. 2597 * 2598 * Note: this must occur before we associate the buffer 2599 * with the vp especially considering limitations in 2600 * the splay tree implementation when dealing with duplicate 2601 * lblkno's. 2602 */ 2603 BO_LOCK(bo); 2604 if (gbincore(bo, blkno)) { 2605 BO_UNLOCK(bo); 2606 bp->b_flags |= B_INVAL; 2607 brelse(bp); 2608 goto loop; 2609 } 2610 2611 /* 2612 * Insert the buffer into the hash, so that it can 2613 * be found by incore. 2614 */ 2615 bp->b_blkno = bp->b_lblkno = blkno; 2616 bp->b_offset = offset; 2617 bgetvp(vp, bp); 2618 BO_UNLOCK(bo); 2619 2620 /* 2621 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2622 * buffer size starts out as 0, B_CACHE will be set by 2623 * allocbuf() for the VMIO case prior to it testing the 2624 * backing store for validity. 2625 */ 2626 2627 if (vmio) { 2628 bp->b_flags |= B_VMIO; 2629 #if defined(VFS_BIO_DEBUG) 2630 if (vn_canvmio(vp) != TRUE) 2631 printf("getblk: VMIO on vnode type %d\n", 2632 vp->v_type); 2633 #endif 2634 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2635 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2636 bp, vp->v_object, bp->b_bufobj->bo_object)); 2637 } else { 2638 bp->b_flags &= ~B_VMIO; 2639 KASSERT(bp->b_bufobj->bo_object == NULL, 2640 ("ARGH! has b_bufobj->bo_object %p %p\n", 2641 bp, bp->b_bufobj->bo_object)); 2642 } 2643 2644 allocbuf(bp, size); 2645 bp->b_flags &= ~B_DONE; 2646 } 2647 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2648 BUF_ASSERT_HELD(bp); 2649 KASSERT(bp->b_bufobj == bo, 2650 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2651 return (bp); 2652 } 2653 2654 /* 2655 * Get an empty, disassociated buffer of given size. The buffer is initially 2656 * set to B_INVAL. 2657 */ 2658 struct buf * 2659 geteblk(int size) 2660 { 2661 struct buf *bp; 2662 int maxsize; 2663 2664 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2665 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2666 continue; 2667 allocbuf(bp, size); 2668 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2669 BUF_ASSERT_HELD(bp); 2670 return (bp); 2671 } 2672 2673 2674 /* 2675 * This code constitutes the buffer memory from either anonymous system 2676 * memory (in the case of non-VMIO operations) or from an associated 2677 * VM object (in the case of VMIO operations). This code is able to 2678 * resize a buffer up or down. 2679 * 2680 * Note that this code is tricky, and has many complications to resolve 2681 * deadlock or inconsistant data situations. Tread lightly!!! 2682 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2683 * the caller. Calling this code willy nilly can result in the loss of data. 2684 * 2685 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2686 * B_CACHE for the non-VMIO case. 2687 */ 2688 2689 int 2690 allocbuf(struct buf *bp, int size) 2691 { 2692 int newbsize, mbsize; 2693 int i; 2694 2695 BUF_ASSERT_HELD(bp); 2696 2697 if (bp->b_kvasize < size) 2698 panic("allocbuf: buffer too small"); 2699 2700 if ((bp->b_flags & B_VMIO) == 0) { 2701 caddr_t origbuf; 2702 int origbufsize; 2703 /* 2704 * Just get anonymous memory from the kernel. Don't 2705 * mess with B_CACHE. 2706 */ 2707 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2708 if (bp->b_flags & B_MALLOC) 2709 newbsize = mbsize; 2710 else 2711 newbsize = round_page(size); 2712 2713 if (newbsize < bp->b_bufsize) { 2714 /* 2715 * malloced buffers are not shrunk 2716 */ 2717 if (bp->b_flags & B_MALLOC) { 2718 if (newbsize) { 2719 bp->b_bcount = size; 2720 } else { 2721 free(bp->b_data, M_BIOBUF); 2722 if (bp->b_bufsize) { 2723 atomic_subtract_int( 2724 &bufmallocspace, 2725 bp->b_bufsize); 2726 bufspacewakeup(); 2727 bp->b_bufsize = 0; 2728 } 2729 bp->b_saveaddr = bp->b_kvabase; 2730 bp->b_data = bp->b_saveaddr; 2731 bp->b_bcount = 0; 2732 bp->b_flags &= ~B_MALLOC; 2733 } 2734 return 1; 2735 } 2736 vm_hold_free_pages( 2737 bp, 2738 (vm_offset_t) bp->b_data + newbsize, 2739 (vm_offset_t) bp->b_data + bp->b_bufsize); 2740 } else if (newbsize > bp->b_bufsize) { 2741 /* 2742 * We only use malloced memory on the first allocation. 2743 * and revert to page-allocated memory when the buffer 2744 * grows. 2745 */ 2746 /* 2747 * There is a potential smp race here that could lead 2748 * to bufmallocspace slightly passing the max. It 2749 * is probably extremely rare and not worth worrying 2750 * over. 2751 */ 2752 if ( (bufmallocspace < maxbufmallocspace) && 2753 (bp->b_bufsize == 0) && 2754 (mbsize <= PAGE_SIZE/2)) { 2755 2756 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2757 bp->b_bufsize = mbsize; 2758 bp->b_bcount = size; 2759 bp->b_flags |= B_MALLOC; 2760 atomic_add_int(&bufmallocspace, mbsize); 2761 return 1; 2762 } 2763 origbuf = NULL; 2764 origbufsize = 0; 2765 /* 2766 * If the buffer is growing on its other-than-first allocation, 2767 * then we revert to the page-allocation scheme. 2768 */ 2769 if (bp->b_flags & B_MALLOC) { 2770 origbuf = bp->b_data; 2771 origbufsize = bp->b_bufsize; 2772 bp->b_data = bp->b_kvabase; 2773 if (bp->b_bufsize) { 2774 atomic_subtract_int(&bufmallocspace, 2775 bp->b_bufsize); 2776 bufspacewakeup(); 2777 bp->b_bufsize = 0; 2778 } 2779 bp->b_flags &= ~B_MALLOC; 2780 newbsize = round_page(newbsize); 2781 } 2782 vm_hold_load_pages( 2783 bp, 2784 (vm_offset_t) bp->b_data + bp->b_bufsize, 2785 (vm_offset_t) bp->b_data + newbsize); 2786 if (origbuf) { 2787 bcopy(origbuf, bp->b_data, origbufsize); 2788 free(origbuf, M_BIOBUF); 2789 } 2790 } 2791 } else { 2792 int desiredpages; 2793 2794 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2795 desiredpages = (size == 0) ? 0 : 2796 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2797 2798 if (bp->b_flags & B_MALLOC) 2799 panic("allocbuf: VMIO buffer can't be malloced"); 2800 /* 2801 * Set B_CACHE initially if buffer is 0 length or will become 2802 * 0-length. 2803 */ 2804 if (size == 0 || bp->b_bufsize == 0) 2805 bp->b_flags |= B_CACHE; 2806 2807 if (newbsize < bp->b_bufsize) { 2808 /* 2809 * DEV_BSIZE aligned new buffer size is less then the 2810 * DEV_BSIZE aligned existing buffer size. Figure out 2811 * if we have to remove any pages. 2812 */ 2813 if (desiredpages < bp->b_npages) { 2814 vm_page_t m; 2815 2816 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2817 vm_page_lock_queues(); 2818 for (i = desiredpages; i < bp->b_npages; i++) { 2819 /* 2820 * the page is not freed here -- it 2821 * is the responsibility of 2822 * vnode_pager_setsize 2823 */ 2824 m = bp->b_pages[i]; 2825 KASSERT(m != bogus_page, 2826 ("allocbuf: bogus page found")); 2827 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2828 vm_page_lock_queues(); 2829 2830 bp->b_pages[i] = NULL; 2831 vm_page_unwire(m, 0); 2832 } 2833 vm_page_unlock_queues(); 2834 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2835 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2836 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2837 bp->b_npages = desiredpages; 2838 } 2839 } else if (size > bp->b_bcount) { 2840 /* 2841 * We are growing the buffer, possibly in a 2842 * byte-granular fashion. 2843 */ 2844 struct vnode *vp; 2845 vm_object_t obj; 2846 vm_offset_t toff; 2847 vm_offset_t tinc; 2848 2849 /* 2850 * Step 1, bring in the VM pages from the object, 2851 * allocating them if necessary. We must clear 2852 * B_CACHE if these pages are not valid for the 2853 * range covered by the buffer. 2854 */ 2855 2856 vp = bp->b_vp; 2857 obj = bp->b_bufobj->bo_object; 2858 2859 VM_OBJECT_LOCK(obj); 2860 while (bp->b_npages < desiredpages) { 2861 vm_page_t m; 2862 vm_pindex_t pi; 2863 2864 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2865 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2866 /* 2867 * note: must allocate system pages 2868 * since blocking here could intefere 2869 * with paging I/O, no matter which 2870 * process we are. 2871 */ 2872 m = vm_page_alloc(obj, pi, 2873 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2874 VM_ALLOC_WIRED); 2875 if (m == NULL) { 2876 atomic_add_int(&vm_pageout_deficit, 2877 desiredpages - bp->b_npages); 2878 VM_OBJECT_UNLOCK(obj); 2879 VM_WAIT; 2880 VM_OBJECT_LOCK(obj); 2881 } else { 2882 if (m->valid == 0) 2883 bp->b_flags &= ~B_CACHE; 2884 bp->b_pages[bp->b_npages] = m; 2885 ++bp->b_npages; 2886 } 2887 continue; 2888 } 2889 2890 /* 2891 * We found a page. If we have to sleep on it, 2892 * retry because it might have gotten freed out 2893 * from under us. 2894 * 2895 * We can only test VPO_BUSY here. Blocking on 2896 * m->busy might lead to a deadlock: 2897 * 2898 * vm_fault->getpages->cluster_read->allocbuf 2899 * 2900 */ 2901 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2902 continue; 2903 2904 /* 2905 * We have a good page. 2906 */ 2907 vm_page_lock_queues(); 2908 vm_page_wire(m); 2909 vm_page_unlock_queues(); 2910 bp->b_pages[bp->b_npages] = m; 2911 ++bp->b_npages; 2912 } 2913 2914 /* 2915 * Step 2. We've loaded the pages into the buffer, 2916 * we have to figure out if we can still have B_CACHE 2917 * set. Note that B_CACHE is set according to the 2918 * byte-granular range ( bcount and size ), new the 2919 * aligned range ( newbsize ). 2920 * 2921 * The VM test is against m->valid, which is DEV_BSIZE 2922 * aligned. Needless to say, the validity of the data 2923 * needs to also be DEV_BSIZE aligned. Note that this 2924 * fails with NFS if the server or some other client 2925 * extends the file's EOF. If our buffer is resized, 2926 * B_CACHE may remain set! XXX 2927 */ 2928 2929 toff = bp->b_bcount; 2930 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2931 2932 while ((bp->b_flags & B_CACHE) && toff < size) { 2933 vm_pindex_t pi; 2934 2935 if (tinc > (size - toff)) 2936 tinc = size - toff; 2937 2938 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2939 PAGE_SHIFT; 2940 2941 vfs_buf_test_cache( 2942 bp, 2943 bp->b_offset, 2944 toff, 2945 tinc, 2946 bp->b_pages[pi] 2947 ); 2948 toff += tinc; 2949 tinc = PAGE_SIZE; 2950 } 2951 VM_OBJECT_UNLOCK(obj); 2952 2953 /* 2954 * Step 3, fixup the KVM pmap. Remember that 2955 * bp->b_data is relative to bp->b_offset, but 2956 * bp->b_offset may be offset into the first page. 2957 */ 2958 2959 bp->b_data = (caddr_t) 2960 trunc_page((vm_offset_t)bp->b_data); 2961 pmap_qenter( 2962 (vm_offset_t)bp->b_data, 2963 bp->b_pages, 2964 bp->b_npages 2965 ); 2966 2967 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2968 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2969 } 2970 } 2971 if (newbsize < bp->b_bufsize) 2972 bufspacewakeup(); 2973 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2974 bp->b_bcount = size; /* requested buffer size */ 2975 return 1; 2976 } 2977 2978 void 2979 biodone(struct bio *bp) 2980 { 2981 struct mtx *mtxp; 2982 void (*done)(struct bio *); 2983 2984 mtxp = mtx_pool_find(mtxpool_sleep, bp); 2985 mtx_lock(mtxp); 2986 bp->bio_flags |= BIO_DONE; 2987 done = bp->bio_done; 2988 if (done == NULL) 2989 wakeup(bp); 2990 mtx_unlock(mtxp); 2991 if (done != NULL) 2992 done(bp); 2993 } 2994 2995 /* 2996 * Wait for a BIO to finish. 2997 * 2998 * XXX: resort to a timeout for now. The optimal locking (if any) for this 2999 * case is not yet clear. 3000 */ 3001 int 3002 biowait(struct bio *bp, const char *wchan) 3003 { 3004 struct mtx *mtxp; 3005 3006 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3007 mtx_lock(mtxp); 3008 while ((bp->bio_flags & BIO_DONE) == 0) 3009 msleep(bp, mtxp, PRIBIO, wchan, hz / 10); 3010 mtx_unlock(mtxp); 3011 if (bp->bio_error != 0) 3012 return (bp->bio_error); 3013 if (!(bp->bio_flags & BIO_ERROR)) 3014 return (0); 3015 return (EIO); 3016 } 3017 3018 void 3019 biofinish(struct bio *bp, struct devstat *stat, int error) 3020 { 3021 3022 if (error) { 3023 bp->bio_error = error; 3024 bp->bio_flags |= BIO_ERROR; 3025 } 3026 if (stat != NULL) 3027 devstat_end_transaction_bio(stat, bp); 3028 biodone(bp); 3029 } 3030 3031 /* 3032 * bufwait: 3033 * 3034 * Wait for buffer I/O completion, returning error status. The buffer 3035 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3036 * error and cleared. 3037 */ 3038 int 3039 bufwait(struct buf *bp) 3040 { 3041 if (bp->b_iocmd == BIO_READ) 3042 bwait(bp, PRIBIO, "biord"); 3043 else 3044 bwait(bp, PRIBIO, "biowr"); 3045 if (bp->b_flags & B_EINTR) { 3046 bp->b_flags &= ~B_EINTR; 3047 return (EINTR); 3048 } 3049 if (bp->b_ioflags & BIO_ERROR) { 3050 return (bp->b_error ? bp->b_error : EIO); 3051 } else { 3052 return (0); 3053 } 3054 } 3055 3056 /* 3057 * Call back function from struct bio back up to struct buf. 3058 */ 3059 static void 3060 bufdonebio(struct bio *bip) 3061 { 3062 struct buf *bp; 3063 3064 bp = bip->bio_caller2; 3065 bp->b_resid = bp->b_bcount - bip->bio_completed; 3066 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3067 bp->b_ioflags = bip->bio_flags; 3068 bp->b_error = bip->bio_error; 3069 if (bp->b_error) 3070 bp->b_ioflags |= BIO_ERROR; 3071 bufdone(bp); 3072 g_destroy_bio(bip); 3073 } 3074 3075 void 3076 dev_strategy(struct cdev *dev, struct buf *bp) 3077 { 3078 struct cdevsw *csw; 3079 struct bio *bip; 3080 3081 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3082 panic("b_iocmd botch"); 3083 for (;;) { 3084 bip = g_new_bio(); 3085 if (bip != NULL) 3086 break; 3087 /* Try again later */ 3088 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3089 } 3090 bip->bio_cmd = bp->b_iocmd; 3091 bip->bio_offset = bp->b_iooffset; 3092 bip->bio_length = bp->b_bcount; 3093 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3094 bip->bio_data = bp->b_data; 3095 bip->bio_done = bufdonebio; 3096 bip->bio_caller2 = bp; 3097 bip->bio_dev = dev; 3098 KASSERT(dev->si_refcount > 0, 3099 ("dev_strategy on un-referenced struct cdev *(%s)", 3100 devtoname(dev))); 3101 csw = dev_refthread(dev); 3102 if (csw == NULL) { 3103 g_destroy_bio(bip); 3104 bp->b_error = ENXIO; 3105 bp->b_ioflags = BIO_ERROR; 3106 bufdone(bp); 3107 return; 3108 } 3109 (*csw->d_strategy)(bip); 3110 dev_relthread(dev); 3111 } 3112 3113 /* 3114 * bufdone: 3115 * 3116 * Finish I/O on a buffer, optionally calling a completion function. 3117 * This is usually called from an interrupt so process blocking is 3118 * not allowed. 3119 * 3120 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3121 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3122 * assuming B_INVAL is clear. 3123 * 3124 * For the VMIO case, we set B_CACHE if the op was a read and no 3125 * read error occured, or if the op was a write. B_CACHE is never 3126 * set if the buffer is invalid or otherwise uncacheable. 3127 * 3128 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3129 * initiator to leave B_INVAL set to brelse the buffer out of existance 3130 * in the biodone routine. 3131 */ 3132 void 3133 bufdone(struct buf *bp) 3134 { 3135 struct bufobj *dropobj; 3136 void (*biodone)(struct buf *); 3137 3138 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3139 dropobj = NULL; 3140 3141 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3142 BUF_ASSERT_HELD(bp); 3143 3144 runningbufwakeup(bp); 3145 if (bp->b_iocmd == BIO_WRITE) 3146 dropobj = bp->b_bufobj; 3147 /* call optional completion function if requested */ 3148 if (bp->b_iodone != NULL) { 3149 biodone = bp->b_iodone; 3150 bp->b_iodone = NULL; 3151 (*biodone) (bp); 3152 if (dropobj) 3153 bufobj_wdrop(dropobj); 3154 return; 3155 } 3156 3157 bufdone_finish(bp); 3158 3159 if (dropobj) 3160 bufobj_wdrop(dropobj); 3161 } 3162 3163 void 3164 bufdone_finish(struct buf *bp) 3165 { 3166 BUF_ASSERT_HELD(bp); 3167 3168 if (!LIST_EMPTY(&bp->b_dep)) 3169 buf_complete(bp); 3170 3171 if (bp->b_flags & B_VMIO) { 3172 int i; 3173 vm_ooffset_t foff; 3174 vm_page_t m; 3175 vm_object_t obj; 3176 int iosize; 3177 struct vnode *vp = bp->b_vp; 3178 boolean_t are_queues_locked; 3179 3180 obj = bp->b_bufobj->bo_object; 3181 3182 #if defined(VFS_BIO_DEBUG) 3183 mp_fixme("usecount and vflag accessed without locks."); 3184 if (vp->v_usecount == 0) { 3185 panic("biodone: zero vnode ref count"); 3186 } 3187 3188 KASSERT(vp->v_object != NULL, 3189 ("biodone: vnode %p has no vm_object", vp)); 3190 #endif 3191 3192 foff = bp->b_offset; 3193 KASSERT(bp->b_offset != NOOFFSET, 3194 ("biodone: no buffer offset")); 3195 3196 VM_OBJECT_LOCK(obj); 3197 #if defined(VFS_BIO_DEBUG) 3198 if (obj->paging_in_progress < bp->b_npages) { 3199 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3200 obj->paging_in_progress, bp->b_npages); 3201 } 3202 #endif 3203 3204 /* 3205 * Set B_CACHE if the op was a normal read and no error 3206 * occured. B_CACHE is set for writes in the b*write() 3207 * routines. 3208 */ 3209 iosize = bp->b_bcount - bp->b_resid; 3210 if (bp->b_iocmd == BIO_READ && 3211 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3212 !(bp->b_ioflags & BIO_ERROR)) { 3213 bp->b_flags |= B_CACHE; 3214 } 3215 if (bp->b_iocmd == BIO_READ) { 3216 vm_page_lock_queues(); 3217 are_queues_locked = TRUE; 3218 } else 3219 are_queues_locked = FALSE; 3220 for (i = 0; i < bp->b_npages; i++) { 3221 int bogusflag = 0; 3222 int resid; 3223 3224 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3225 if (resid > iosize) 3226 resid = iosize; 3227 3228 /* 3229 * cleanup bogus pages, restoring the originals 3230 */ 3231 m = bp->b_pages[i]; 3232 if (m == bogus_page) { 3233 bogusflag = 1; 3234 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3235 if (m == NULL) 3236 panic("biodone: page disappeared!"); 3237 bp->b_pages[i] = m; 3238 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3239 bp->b_pages, bp->b_npages); 3240 } 3241 #if defined(VFS_BIO_DEBUG) 3242 if (OFF_TO_IDX(foff) != m->pindex) { 3243 printf( 3244 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3245 (intmax_t)foff, (uintmax_t)m->pindex); 3246 } 3247 #endif 3248 3249 /* 3250 * In the write case, the valid and clean bits are 3251 * already changed correctly ( see bdwrite() ), so we 3252 * only need to do this here in the read case. 3253 */ 3254 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3255 vfs_page_set_valid(bp, foff, m); 3256 } 3257 3258 /* 3259 * when debugging new filesystems or buffer I/O methods, this 3260 * is the most common error that pops up. if you see this, you 3261 * have not set the page busy flag correctly!!! 3262 */ 3263 if (m->busy == 0) { 3264 printf("biodone: page busy < 0, " 3265 "pindex: %d, foff: 0x(%x,%x), " 3266 "resid: %d, index: %d\n", 3267 (int) m->pindex, (int)(foff >> 32), 3268 (int) foff & 0xffffffff, resid, i); 3269 if (!vn_isdisk(vp, NULL)) 3270 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3271 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3272 (intmax_t) bp->b_lblkno, 3273 bp->b_flags, bp->b_npages); 3274 else 3275 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3276 (intmax_t) bp->b_lblkno, 3277 bp->b_flags, bp->b_npages); 3278 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3279 (u_long)m->valid, (u_long)m->dirty, 3280 m->wire_count); 3281 panic("biodone: page busy < 0\n"); 3282 } 3283 vm_page_io_finish(m); 3284 vm_object_pip_subtract(obj, 1); 3285 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3286 iosize -= resid; 3287 } 3288 if (are_queues_locked) 3289 vm_page_unlock_queues(); 3290 vm_object_pip_wakeupn(obj, 0); 3291 VM_OBJECT_UNLOCK(obj); 3292 } 3293 3294 /* 3295 * For asynchronous completions, release the buffer now. The brelse 3296 * will do a wakeup there if necessary - so no need to do a wakeup 3297 * here in the async case. The sync case always needs to do a wakeup. 3298 */ 3299 3300 if (bp->b_flags & B_ASYNC) { 3301 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3302 brelse(bp); 3303 else 3304 bqrelse(bp); 3305 } else 3306 bdone(bp); 3307 } 3308 3309 /* 3310 * This routine is called in lieu of iodone in the case of 3311 * incomplete I/O. This keeps the busy status for pages 3312 * consistant. 3313 */ 3314 void 3315 vfs_unbusy_pages(struct buf *bp) 3316 { 3317 int i; 3318 vm_object_t obj; 3319 vm_page_t m; 3320 3321 runningbufwakeup(bp); 3322 if (!(bp->b_flags & B_VMIO)) 3323 return; 3324 3325 obj = bp->b_bufobj->bo_object; 3326 VM_OBJECT_LOCK(obj); 3327 for (i = 0; i < bp->b_npages; i++) { 3328 m = bp->b_pages[i]; 3329 if (m == bogus_page) { 3330 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3331 if (!m) 3332 panic("vfs_unbusy_pages: page missing\n"); 3333 bp->b_pages[i] = m; 3334 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3335 bp->b_pages, bp->b_npages); 3336 } 3337 vm_object_pip_subtract(obj, 1); 3338 vm_page_io_finish(m); 3339 } 3340 vm_object_pip_wakeupn(obj, 0); 3341 VM_OBJECT_UNLOCK(obj); 3342 } 3343 3344 /* 3345 * vfs_page_set_valid: 3346 * 3347 * Set the valid bits in a page based on the supplied offset. The 3348 * range is restricted to the buffer's size. 3349 * 3350 * This routine is typically called after a read completes. 3351 */ 3352 static void 3353 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3354 { 3355 vm_ooffset_t soff, eoff; 3356 3357 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3358 /* 3359 * Start and end offsets in buffer. eoff - soff may not cross a 3360 * page boundry or cross the end of the buffer. The end of the 3361 * buffer, in this case, is our file EOF, not the allocation size 3362 * of the buffer. 3363 */ 3364 soff = off; 3365 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3366 if (eoff > bp->b_offset + bp->b_bcount) 3367 eoff = bp->b_offset + bp->b_bcount; 3368 3369 /* 3370 * Set valid range. This is typically the entire buffer and thus the 3371 * entire page. 3372 */ 3373 if (eoff > soff) { 3374 vm_page_set_validclean( 3375 m, 3376 (vm_offset_t) (soff & PAGE_MASK), 3377 (vm_offset_t) (eoff - soff) 3378 ); 3379 } 3380 } 3381 3382 /* 3383 * This routine is called before a device strategy routine. 3384 * It is used to tell the VM system that paging I/O is in 3385 * progress, and treat the pages associated with the buffer 3386 * almost as being VPO_BUSY. Also the object paging_in_progress 3387 * flag is handled to make sure that the object doesn't become 3388 * inconsistant. 3389 * 3390 * Since I/O has not been initiated yet, certain buffer flags 3391 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3392 * and should be ignored. 3393 */ 3394 void 3395 vfs_busy_pages(struct buf *bp, int clear_modify) 3396 { 3397 int i, bogus; 3398 vm_object_t obj; 3399 vm_ooffset_t foff; 3400 vm_page_t m; 3401 3402 if (!(bp->b_flags & B_VMIO)) 3403 return; 3404 3405 obj = bp->b_bufobj->bo_object; 3406 foff = bp->b_offset; 3407 KASSERT(bp->b_offset != NOOFFSET, 3408 ("vfs_busy_pages: no buffer offset")); 3409 VM_OBJECT_LOCK(obj); 3410 if (bp->b_bufsize != 0) 3411 vfs_setdirty_locked_object(bp); 3412 retry: 3413 for (i = 0; i < bp->b_npages; i++) { 3414 m = bp->b_pages[i]; 3415 3416 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3417 goto retry; 3418 } 3419 bogus = 0; 3420 vm_page_lock_queues(); 3421 for (i = 0; i < bp->b_npages; i++) { 3422 m = bp->b_pages[i]; 3423 3424 if ((bp->b_flags & B_CLUSTER) == 0) { 3425 vm_object_pip_add(obj, 1); 3426 vm_page_io_start(m); 3427 } 3428 /* 3429 * When readying a buffer for a read ( i.e 3430 * clear_modify == 0 ), it is important to do 3431 * bogus_page replacement for valid pages in 3432 * partially instantiated buffers. Partially 3433 * instantiated buffers can, in turn, occur when 3434 * reconstituting a buffer from its VM backing store 3435 * base. We only have to do this if B_CACHE is 3436 * clear ( which causes the I/O to occur in the 3437 * first place ). The replacement prevents the read 3438 * I/O from overwriting potentially dirty VM-backed 3439 * pages. XXX bogus page replacement is, uh, bogus. 3440 * It may not work properly with small-block devices. 3441 * We need to find a better way. 3442 */ 3443 pmap_remove_all(m); 3444 if (clear_modify) 3445 vfs_page_set_valid(bp, foff, m); 3446 else if (m->valid == VM_PAGE_BITS_ALL && 3447 (bp->b_flags & B_CACHE) == 0) { 3448 bp->b_pages[i] = bogus_page; 3449 bogus++; 3450 } 3451 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3452 } 3453 vm_page_unlock_queues(); 3454 VM_OBJECT_UNLOCK(obj); 3455 if (bogus) 3456 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3457 bp->b_pages, bp->b_npages); 3458 } 3459 3460 /* 3461 * Tell the VM system that the pages associated with this buffer 3462 * are clean. This is used for delayed writes where the data is 3463 * going to go to disk eventually without additional VM intevention. 3464 * 3465 * Note that while we only really need to clean through to b_bcount, we 3466 * just go ahead and clean through to b_bufsize. 3467 */ 3468 static void 3469 vfs_clean_pages(struct buf *bp) 3470 { 3471 int i; 3472 vm_ooffset_t foff, noff, eoff; 3473 vm_page_t m; 3474 3475 if (!(bp->b_flags & B_VMIO)) 3476 return; 3477 3478 foff = bp->b_offset; 3479 KASSERT(bp->b_offset != NOOFFSET, 3480 ("vfs_clean_pages: no buffer offset")); 3481 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3482 vm_page_lock_queues(); 3483 for (i = 0; i < bp->b_npages; i++) { 3484 m = bp->b_pages[i]; 3485 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3486 eoff = noff; 3487 3488 if (eoff > bp->b_offset + bp->b_bufsize) 3489 eoff = bp->b_offset + bp->b_bufsize; 3490 vfs_page_set_valid(bp, foff, m); 3491 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3492 foff = noff; 3493 } 3494 vm_page_unlock_queues(); 3495 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3496 } 3497 3498 /* 3499 * vfs_bio_set_validclean: 3500 * 3501 * Set the range within the buffer to valid and clean. The range is 3502 * relative to the beginning of the buffer, b_offset. Note that b_offset 3503 * itself may be offset from the beginning of the first page. 3504 * 3505 */ 3506 3507 void 3508 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3509 { 3510 int i, n; 3511 vm_page_t m; 3512 3513 if (!(bp->b_flags & B_VMIO)) 3514 return; 3515 /* 3516 * Fixup base to be relative to beginning of first page. 3517 * Set initial n to be the maximum number of bytes in the 3518 * first page that can be validated. 3519 */ 3520 3521 base += (bp->b_offset & PAGE_MASK); 3522 n = PAGE_SIZE - (base & PAGE_MASK); 3523 3524 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3525 vm_page_lock_queues(); 3526 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3527 m = bp->b_pages[i]; 3528 if (n > size) 3529 n = size; 3530 vm_page_set_validclean(m, base & PAGE_MASK, n); 3531 base += n; 3532 size -= n; 3533 n = PAGE_SIZE; 3534 } 3535 vm_page_unlock_queues(); 3536 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3537 } 3538 3539 /* 3540 * vfs_bio_clrbuf: 3541 * 3542 * clear a buffer. This routine essentially fakes an I/O, so we need 3543 * to clear BIO_ERROR and B_INVAL. 3544 * 3545 * Note that while we only theoretically need to clear through b_bcount, 3546 * we go ahead and clear through b_bufsize. 3547 */ 3548 3549 void 3550 vfs_bio_clrbuf(struct buf *bp) 3551 { 3552 int i, j, mask = 0; 3553 caddr_t sa, ea; 3554 3555 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3556 clrbuf(bp); 3557 return; 3558 } 3559 3560 bp->b_flags &= ~B_INVAL; 3561 bp->b_ioflags &= ~BIO_ERROR; 3562 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3563 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3564 (bp->b_offset & PAGE_MASK) == 0) { 3565 if (bp->b_pages[0] == bogus_page) 3566 goto unlock; 3567 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3568 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3569 if ((bp->b_pages[0]->valid & mask) == mask) 3570 goto unlock; 3571 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3572 ((bp->b_pages[0]->valid & mask) == 0)) { 3573 bzero(bp->b_data, bp->b_bufsize); 3574 bp->b_pages[0]->valid |= mask; 3575 goto unlock; 3576 } 3577 } 3578 ea = sa = bp->b_data; 3579 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3580 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3581 ea = (caddr_t)(vm_offset_t)ulmin( 3582 (u_long)(vm_offset_t)ea, 3583 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3584 if (bp->b_pages[i] == bogus_page) 3585 continue; 3586 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3587 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3588 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3589 if ((bp->b_pages[i]->valid & mask) == mask) 3590 continue; 3591 if ((bp->b_pages[i]->valid & mask) == 0) { 3592 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3593 bzero(sa, ea - sa); 3594 } else { 3595 for (; sa < ea; sa += DEV_BSIZE, j++) { 3596 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3597 (bp->b_pages[i]->valid & (1 << j)) == 0) 3598 bzero(sa, DEV_BSIZE); 3599 } 3600 } 3601 bp->b_pages[i]->valid |= mask; 3602 } 3603 unlock: 3604 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3605 bp->b_resid = 0; 3606 } 3607 3608 /* 3609 * vm_hold_load_pages and vm_hold_free_pages get pages into 3610 * a buffers address space. The pages are anonymous and are 3611 * not associated with a file object. 3612 */ 3613 static void 3614 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3615 { 3616 vm_offset_t pg; 3617 vm_page_t p; 3618 int index; 3619 3620 to = round_page(to); 3621 from = round_page(from); 3622 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3623 3624 VM_OBJECT_LOCK(kernel_object); 3625 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3626 tryagain: 3627 /* 3628 * note: must allocate system pages since blocking here 3629 * could intefere with paging I/O, no matter which 3630 * process we are. 3631 */ 3632 p = vm_page_alloc(kernel_object, 3633 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3634 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3635 if (!p) { 3636 atomic_add_int(&vm_pageout_deficit, 3637 (to - pg) >> PAGE_SHIFT); 3638 VM_OBJECT_UNLOCK(kernel_object); 3639 VM_WAIT; 3640 VM_OBJECT_LOCK(kernel_object); 3641 goto tryagain; 3642 } 3643 p->valid = VM_PAGE_BITS_ALL; 3644 pmap_qenter(pg, &p, 1); 3645 bp->b_pages[index] = p; 3646 } 3647 VM_OBJECT_UNLOCK(kernel_object); 3648 bp->b_npages = index; 3649 } 3650 3651 /* Return pages associated with this buf to the vm system */ 3652 static void 3653 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3654 { 3655 vm_offset_t pg; 3656 vm_page_t p; 3657 int index, newnpages; 3658 3659 from = round_page(from); 3660 to = round_page(to); 3661 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3662 3663 VM_OBJECT_LOCK(kernel_object); 3664 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3665 p = bp->b_pages[index]; 3666 if (p && (index < bp->b_npages)) { 3667 if (p->busy) { 3668 printf( 3669 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3670 (intmax_t)bp->b_blkno, 3671 (intmax_t)bp->b_lblkno); 3672 } 3673 bp->b_pages[index] = NULL; 3674 pmap_qremove(pg, 1); 3675 vm_page_lock_queues(); 3676 vm_page_unwire(p, 0); 3677 vm_page_free(p); 3678 vm_page_unlock_queues(); 3679 } 3680 } 3681 VM_OBJECT_UNLOCK(kernel_object); 3682 bp->b_npages = newnpages; 3683 } 3684 3685 /* 3686 * Map an IO request into kernel virtual address space. 3687 * 3688 * All requests are (re)mapped into kernel VA space. 3689 * Notice that we use b_bufsize for the size of the buffer 3690 * to be mapped. b_bcount might be modified by the driver. 3691 * 3692 * Note that even if the caller determines that the address space should 3693 * be valid, a race or a smaller-file mapped into a larger space may 3694 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3695 * check the return value. 3696 */ 3697 int 3698 vmapbuf(struct buf *bp) 3699 { 3700 caddr_t addr, kva; 3701 vm_prot_t prot; 3702 int pidx, i; 3703 struct vm_page *m; 3704 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3705 3706 if (bp->b_bufsize < 0) 3707 return (-1); 3708 prot = VM_PROT_READ; 3709 if (bp->b_iocmd == BIO_READ) 3710 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3711 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3712 addr < bp->b_data + bp->b_bufsize; 3713 addr += PAGE_SIZE, pidx++) { 3714 /* 3715 * Do the vm_fault if needed; do the copy-on-write thing 3716 * when reading stuff off device into memory. 3717 * 3718 * NOTE! Must use pmap_extract() because addr may be in 3719 * the userland address space, and kextract is only guarenteed 3720 * to work for the kernland address space (see: sparc64 port). 3721 */ 3722 retry: 3723 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3724 prot) < 0) { 3725 vm_page_lock_queues(); 3726 for (i = 0; i < pidx; ++i) { 3727 vm_page_unhold(bp->b_pages[i]); 3728 bp->b_pages[i] = NULL; 3729 } 3730 vm_page_unlock_queues(); 3731 return(-1); 3732 } 3733 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3734 if (m == NULL) 3735 goto retry; 3736 bp->b_pages[pidx] = m; 3737 } 3738 if (pidx > btoc(MAXPHYS)) 3739 panic("vmapbuf: mapped more than MAXPHYS"); 3740 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3741 3742 kva = bp->b_saveaddr; 3743 bp->b_npages = pidx; 3744 bp->b_saveaddr = bp->b_data; 3745 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3746 return(0); 3747 } 3748 3749 /* 3750 * Free the io map PTEs associated with this IO operation. 3751 * We also invalidate the TLB entries and restore the original b_addr. 3752 */ 3753 void 3754 vunmapbuf(struct buf *bp) 3755 { 3756 int pidx; 3757 int npages; 3758 3759 npages = bp->b_npages; 3760 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3761 vm_page_lock_queues(); 3762 for (pidx = 0; pidx < npages; pidx++) 3763 vm_page_unhold(bp->b_pages[pidx]); 3764 vm_page_unlock_queues(); 3765 3766 bp->b_data = bp->b_saveaddr; 3767 } 3768 3769 void 3770 bdone(struct buf *bp) 3771 { 3772 struct mtx *mtxp; 3773 3774 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3775 mtx_lock(mtxp); 3776 bp->b_flags |= B_DONE; 3777 wakeup(bp); 3778 mtx_unlock(mtxp); 3779 } 3780 3781 void 3782 bwait(struct buf *bp, u_char pri, const char *wchan) 3783 { 3784 struct mtx *mtxp; 3785 3786 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3787 mtx_lock(mtxp); 3788 while ((bp->b_flags & B_DONE) == 0) 3789 msleep(bp, mtxp, pri, wchan, 0); 3790 mtx_unlock(mtxp); 3791 } 3792 3793 int 3794 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3795 { 3796 3797 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3798 } 3799 3800 void 3801 bufstrategy(struct bufobj *bo, struct buf *bp) 3802 { 3803 int i = 0; 3804 struct vnode *vp; 3805 3806 vp = bp->b_vp; 3807 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3808 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3809 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3810 i = VOP_STRATEGY(vp, bp); 3811 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3812 } 3813 3814 void 3815 bufobj_wrefl(struct bufobj *bo) 3816 { 3817 3818 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3819 ASSERT_BO_LOCKED(bo); 3820 bo->bo_numoutput++; 3821 } 3822 3823 void 3824 bufobj_wref(struct bufobj *bo) 3825 { 3826 3827 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3828 BO_LOCK(bo); 3829 bo->bo_numoutput++; 3830 BO_UNLOCK(bo); 3831 } 3832 3833 void 3834 bufobj_wdrop(struct bufobj *bo) 3835 { 3836 3837 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3838 BO_LOCK(bo); 3839 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3840 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3841 bo->bo_flag &= ~BO_WWAIT; 3842 wakeup(&bo->bo_numoutput); 3843 } 3844 BO_UNLOCK(bo); 3845 } 3846 3847 int 3848 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3849 { 3850 int error; 3851 3852 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3853 ASSERT_BO_LOCKED(bo); 3854 error = 0; 3855 while (bo->bo_numoutput) { 3856 bo->bo_flag |= BO_WWAIT; 3857 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3858 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3859 if (error) 3860 break; 3861 } 3862 return (error); 3863 } 3864 3865 void 3866 bpin(struct buf *bp) 3867 { 3868 struct mtx *mtxp; 3869 3870 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3871 mtx_lock(mtxp); 3872 bp->b_pin_count++; 3873 mtx_unlock(mtxp); 3874 } 3875 3876 void 3877 bunpin(struct buf *bp) 3878 { 3879 struct mtx *mtxp; 3880 3881 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3882 mtx_lock(mtxp); 3883 if (--bp->b_pin_count == 0) 3884 wakeup(bp); 3885 mtx_unlock(mtxp); 3886 } 3887 3888 void 3889 bunpin_wait(struct buf *bp) 3890 { 3891 struct mtx *mtxp; 3892 3893 mtxp = mtx_pool_find(mtxpool_sleep, bp); 3894 mtx_lock(mtxp); 3895 while (bp->b_pin_count > 0) 3896 msleep(bp, mtxp, PRIBIO, "bwunpin", 0); 3897 mtx_unlock(mtxp); 3898 } 3899 3900 #include "opt_ddb.h" 3901 #ifdef DDB 3902 #include <ddb/ddb.h> 3903 3904 /* DDB command to show buffer data */ 3905 DB_SHOW_COMMAND(buffer, db_show_buffer) 3906 { 3907 /* get args */ 3908 struct buf *bp = (struct buf *)addr; 3909 3910 if (!have_addr) { 3911 db_printf("usage: show buffer <addr>\n"); 3912 return; 3913 } 3914 3915 db_printf("buf at %p\n", bp); 3916 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3917 db_printf( 3918 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3919 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3920 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3921 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3922 if (bp->b_npages) { 3923 int i; 3924 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3925 for (i = 0; i < bp->b_npages; i++) { 3926 vm_page_t m; 3927 m = bp->b_pages[i]; 3928 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3929 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3930 if ((i + 1) < bp->b_npages) 3931 db_printf(","); 3932 } 3933 db_printf("\n"); 3934 } 3935 lockmgr_printinfo(&bp->b_lock); 3936 } 3937 3938 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3939 { 3940 struct buf *bp; 3941 int i; 3942 3943 for (i = 0; i < nbuf; i++) { 3944 bp = &buf[i]; 3945 if (BUF_ISLOCKED(bp)) { 3946 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3947 db_printf("\n"); 3948 } 3949 } 3950 } 3951 #endif /* DDB */ 3952