1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * this file contains a new buffer I/O scheme implementing a coherent 30 * VM object and buffer cache scheme. Pains have been taken to make 31 * sure that the performance degradation associated with schemes such 32 * as this is not realized. 33 * 34 * Author: John S. Dyson 35 * Significant help during the development and debugging phases 36 * had been provided by David Greenman, also of the FreeBSD core team. 37 * 38 * see man buf(9) for more info. 39 */ 40 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/bio.h> 47 #include <sys/conf.h> 48 #include <sys/buf.h> 49 #include <sys/devicestat.h> 50 #include <sys/eventhandler.h> 51 #include <sys/lock.h> 52 #include <sys/malloc.h> 53 #include <sys/mount.h> 54 #include <sys/mutex.h> 55 #include <sys/kernel.h> 56 #include <sys/kthread.h> 57 #include <sys/proc.h> 58 #include <sys/resourcevar.h> 59 #include <sys/sysctl.h> 60 #include <sys/vmmeter.h> 61 #include <sys/vnode.h> 62 #include <geom/geom.h> 63 #include <vm/vm.h> 64 #include <vm/vm_param.h> 65 #include <vm/vm_kern.h> 66 #include <vm/vm_pageout.h> 67 #include <vm/vm_page.h> 68 #include <vm/vm_object.h> 69 #include <vm/vm_extern.h> 70 #include <vm/vm_map.h> 71 #include "opt_directio.h" 72 #include "opt_swap.h" 73 74 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 75 76 struct bio_ops bioops; /* I/O operation notification */ 77 78 struct buf_ops buf_ops_bio = { 79 .bop_name = "buf_ops_bio", 80 .bop_write = bufwrite, 81 .bop_strategy = bufstrategy, 82 .bop_sync = bufsync, 83 }; 84 85 /* 86 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 87 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 88 */ 89 struct buf *buf; /* buffer header pool */ 90 91 static struct proc *bufdaemonproc; 92 93 static int inmem(struct vnode *vp, daddr_t blkno); 94 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 95 vm_offset_t to); 96 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 97 vm_offset_t to); 98 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 99 int pageno, vm_page_t m); 100 static void vfs_clean_pages(struct buf *bp); 101 static void vfs_setdirty(struct buf *bp); 102 static void vfs_setdirty_locked_object(struct buf *bp); 103 static void vfs_vmio_release(struct buf *bp); 104 static int vfs_bio_clcheck(struct vnode *vp, int size, 105 daddr_t lblkno, daddr_t blkno); 106 static int flushbufqueues(int, int); 107 static void buf_daemon(void); 108 static void bremfreel(struct buf *bp); 109 110 int vmiodirenable = TRUE; 111 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 112 "Use the VM system for directory writes"); 113 int runningbufspace; 114 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 115 "Amount of presently outstanding async buffer io"); 116 static int bufspace; 117 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 118 "KVA memory used for bufs"); 119 static int maxbufspace; 120 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 121 "Maximum allowed value of bufspace (including buf_daemon)"); 122 static int bufmallocspace; 123 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 124 "Amount of malloced memory for buffers"); 125 static int maxbufmallocspace; 126 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 127 "Maximum amount of malloced memory for buffers"); 128 static int lobufspace; 129 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 130 "Minimum amount of buffers we want to have"); 131 int hibufspace; 132 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 133 "Maximum allowed value of bufspace (excluding buf_daemon)"); 134 static int bufreusecnt; 135 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 136 "Number of times we have reused a buffer"); 137 static int buffreekvacnt; 138 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 139 "Number of times we have freed the KVA space from some buffer"); 140 static int bufdefragcnt; 141 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 142 "Number of times we have had to repeat buffer allocation to defragment"); 143 static int lorunningspace; 144 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 145 "Minimum preferred space used for in-progress I/O"); 146 static int hirunningspace; 147 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 148 "Maximum amount of space to use for in-progress I/O"); 149 static int dirtybufferflushes; 150 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 151 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 152 static int altbufferflushes; 153 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 154 0, "Number of fsync flushes to limit dirty buffers"); 155 static int recursiveflushes; 156 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 157 0, "Number of flushes skipped due to being recursive"); 158 static int numdirtybuffers; 159 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 160 "Number of buffers that are dirty (has unwritten changes) at the moment"); 161 static int lodirtybuffers; 162 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 163 "How many buffers we want to have free before bufdaemon can sleep"); 164 static int hidirtybuffers; 165 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 166 "When the number of dirty buffers is considered severe"); 167 static int dirtybufthresh; 168 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 169 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 170 static int numfreebuffers; 171 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 172 "Number of free buffers"); 173 static int lofreebuffers; 174 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 175 "XXX Unused"); 176 static int hifreebuffers; 177 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 178 "XXX Complicatedly unused"); 179 static int getnewbufcalls; 180 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 181 "Number of calls to getnewbuf"); 182 static int getnewbufrestarts; 183 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 184 "Number of times getnewbuf has had to restart a buffer aquisition"); 185 186 /* 187 * Wakeup point for bufdaemon, as well as indicator of whether it is already 188 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 189 * is idling. 190 */ 191 static int bd_request; 192 193 /* 194 * This lock synchronizes access to bd_request. 195 */ 196 static struct mtx bdlock; 197 198 /* 199 * bogus page -- for I/O to/from partially complete buffers 200 * this is a temporary solution to the problem, but it is not 201 * really that bad. it would be better to split the buffer 202 * for input in the case of buffers partially already in memory, 203 * but the code is intricate enough already. 204 */ 205 vm_page_t bogus_page; 206 207 /* 208 * Synchronization (sleep/wakeup) variable for active buffer space requests. 209 * Set when wait starts, cleared prior to wakeup(). 210 * Used in runningbufwakeup() and waitrunningbufspace(). 211 */ 212 static int runningbufreq; 213 214 /* 215 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 216 * waitrunningbufspace(). 217 */ 218 static struct mtx rbreqlock; 219 220 /* 221 * Synchronization (sleep/wakeup) variable for buffer requests. 222 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 223 * by and/or. 224 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 225 * getnewbuf(), and getblk(). 226 */ 227 static int needsbuffer; 228 229 /* 230 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 231 */ 232 static struct mtx nblock; 233 234 /* 235 * Lock that protects against bwait()/bdone()/B_DONE races. 236 */ 237 238 static struct mtx bdonelock; 239 240 /* 241 * Lock that protects against bwait()/bdone()/B_DONE races. 242 */ 243 static struct mtx bpinlock; 244 245 /* 246 * Definitions for the buffer free lists. 247 */ 248 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 249 250 #define QUEUE_NONE 0 /* on no queue */ 251 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 252 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 253 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 254 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 255 #define QUEUE_EMPTY 5 /* empty buffer headers */ 256 257 /* Queues for free buffers with various properties */ 258 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 259 260 /* Lock for the bufqueues */ 261 static struct mtx bqlock; 262 263 /* 264 * Single global constant for BUF_WMESG, to avoid getting multiple references. 265 * buf_wmesg is referred from macros. 266 */ 267 const char *buf_wmesg = BUF_WMESG; 268 269 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 270 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 271 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 272 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 273 274 #ifdef DIRECTIO 275 extern void ffs_rawread_setup(void); 276 #endif /* DIRECTIO */ 277 /* 278 * numdirtywakeup: 279 * 280 * If someone is blocked due to there being too many dirty buffers, 281 * and numdirtybuffers is now reasonable, wake them up. 282 */ 283 284 static __inline void 285 numdirtywakeup(int level) 286 { 287 288 if (numdirtybuffers <= level) { 289 mtx_lock(&nblock); 290 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 291 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 292 wakeup(&needsbuffer); 293 } 294 mtx_unlock(&nblock); 295 } 296 } 297 298 /* 299 * bufspacewakeup: 300 * 301 * Called when buffer space is potentially available for recovery. 302 * getnewbuf() will block on this flag when it is unable to free 303 * sufficient buffer space. Buffer space becomes recoverable when 304 * bp's get placed back in the queues. 305 */ 306 307 static __inline void 308 bufspacewakeup(void) 309 { 310 311 /* 312 * If someone is waiting for BUF space, wake them up. Even 313 * though we haven't freed the kva space yet, the waiting 314 * process will be able to now. 315 */ 316 mtx_lock(&nblock); 317 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 318 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 319 wakeup(&needsbuffer); 320 } 321 mtx_unlock(&nblock); 322 } 323 324 /* 325 * runningbufwakeup() - in-progress I/O accounting. 326 * 327 */ 328 void 329 runningbufwakeup(struct buf *bp) 330 { 331 332 if (bp->b_runningbufspace) { 333 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 334 bp->b_runningbufspace = 0; 335 mtx_lock(&rbreqlock); 336 if (runningbufreq && runningbufspace <= lorunningspace) { 337 runningbufreq = 0; 338 wakeup(&runningbufreq); 339 } 340 mtx_unlock(&rbreqlock); 341 } 342 } 343 344 /* 345 * bufcountwakeup: 346 * 347 * Called when a buffer has been added to one of the free queues to 348 * account for the buffer and to wakeup anyone waiting for free buffers. 349 * This typically occurs when large amounts of metadata are being handled 350 * by the buffer cache ( else buffer space runs out first, usually ). 351 */ 352 353 static __inline void 354 bufcountwakeup(void) 355 { 356 357 atomic_add_int(&numfreebuffers, 1); 358 mtx_lock(&nblock); 359 if (needsbuffer) { 360 needsbuffer &= ~VFS_BIO_NEED_ANY; 361 if (numfreebuffers >= hifreebuffers) 362 needsbuffer &= ~VFS_BIO_NEED_FREE; 363 wakeup(&needsbuffer); 364 } 365 mtx_unlock(&nblock); 366 } 367 368 /* 369 * waitrunningbufspace() 370 * 371 * runningbufspace is a measure of the amount of I/O currently 372 * running. This routine is used in async-write situations to 373 * prevent creating huge backups of pending writes to a device. 374 * Only asynchronous writes are governed by this function. 375 * 376 * Reads will adjust runningbufspace, but will not block based on it. 377 * The read load has a side effect of reducing the allowed write load. 378 * 379 * This does NOT turn an async write into a sync write. It waits 380 * for earlier writes to complete and generally returns before the 381 * caller's write has reached the device. 382 */ 383 void 384 waitrunningbufspace(void) 385 { 386 387 mtx_lock(&rbreqlock); 388 while (runningbufspace > hirunningspace) { 389 ++runningbufreq; 390 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 391 } 392 mtx_unlock(&rbreqlock); 393 } 394 395 396 /* 397 * vfs_buf_test_cache: 398 * 399 * Called when a buffer is extended. This function clears the B_CACHE 400 * bit if the newly extended portion of the buffer does not contain 401 * valid data. 402 */ 403 static __inline 404 void 405 vfs_buf_test_cache(struct buf *bp, 406 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 407 vm_page_t m) 408 { 409 410 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 411 if (bp->b_flags & B_CACHE) { 412 int base = (foff + off) & PAGE_MASK; 413 if (vm_page_is_valid(m, base, size) == 0) 414 bp->b_flags &= ~B_CACHE; 415 } 416 } 417 418 /* Wake up the buffer deamon if necessary */ 419 static __inline 420 void 421 bd_wakeup(int dirtybuflevel) 422 { 423 424 mtx_lock(&bdlock); 425 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 426 bd_request = 1; 427 wakeup(&bd_request); 428 } 429 mtx_unlock(&bdlock); 430 } 431 432 /* 433 * bd_speedup - speedup the buffer cache flushing code 434 */ 435 436 static __inline 437 void 438 bd_speedup(void) 439 { 440 441 bd_wakeup(1); 442 } 443 444 /* 445 * Calculating buffer cache scaling values and reserve space for buffer 446 * headers. This is called during low level kernel initialization and 447 * may be called more then once. We CANNOT write to the memory area 448 * being reserved at this time. 449 */ 450 caddr_t 451 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 452 { 453 454 /* 455 * physmem_est is in pages. Convert it to kilobytes (assumes 456 * PAGE_SIZE is >= 1K) 457 */ 458 physmem_est = physmem_est * (PAGE_SIZE / 1024); 459 460 /* 461 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 462 * For the first 64MB of ram nominally allocate sufficient buffers to 463 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 464 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 465 * the buffer cache we limit the eventual kva reservation to 466 * maxbcache bytes. 467 * 468 * factor represents the 1/4 x ram conversion. 469 */ 470 if (nbuf == 0) { 471 int factor = 4 * BKVASIZE / 1024; 472 473 nbuf = 50; 474 if (physmem_est > 4096) 475 nbuf += min((physmem_est - 4096) / factor, 476 65536 / factor); 477 if (physmem_est > 65536) 478 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 479 480 if (maxbcache && nbuf > maxbcache / BKVASIZE) 481 nbuf = maxbcache / BKVASIZE; 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 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 533 mtx_init(&bpinlock, "bpin lock", NULL, MTX_DEF); 534 535 /* next, make a null set of free lists */ 536 for (i = 0; i < BUFFER_QUEUES; i++) 537 TAILQ_INIT(&bufqueues[i]); 538 539 /* finally, initialize each buffer header and stick on empty q */ 540 for (i = 0; i < nbuf; i++) { 541 bp = &buf[i]; 542 bzero(bp, sizeof *bp); 543 bp->b_flags = B_INVAL; /* we're just an empty header */ 544 bp->b_rcred = NOCRED; 545 bp->b_wcred = NOCRED; 546 bp->b_qindex = QUEUE_EMPTY; 547 bp->b_vflags = 0; 548 bp->b_xflags = 0; 549 LIST_INIT(&bp->b_dep); 550 BUF_LOCKINIT(bp); 551 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 552 } 553 554 /* 555 * maxbufspace is the absolute maximum amount of buffer space we are 556 * allowed to reserve in KVM and in real terms. The absolute maximum 557 * is nominally used by buf_daemon. hibufspace is the nominal maximum 558 * used by most other processes. The differential is required to 559 * ensure that buf_daemon is able to run when other processes might 560 * be blocked waiting for buffer space. 561 * 562 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 563 * this may result in KVM fragmentation which is not handled optimally 564 * by the system. 565 */ 566 maxbufspace = nbuf * BKVASIZE; 567 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 568 lobufspace = hibufspace - MAXBSIZE; 569 570 lorunningspace = 512 * 1024; 571 hirunningspace = 1024 * 1024; 572 573 /* 574 * Limit the amount of malloc memory since it is wired permanently into 575 * the kernel space. Even though this is accounted for in the buffer 576 * allocation, we don't want the malloced region to grow uncontrolled. 577 * The malloc scheme improves memory utilization significantly on average 578 * (small) directories. 579 */ 580 maxbufmallocspace = hibufspace / 20; 581 582 /* 583 * Reduce the chance of a deadlock occuring by limiting the number 584 * of delayed-write dirty buffers we allow to stack up. 585 */ 586 hidirtybuffers = nbuf / 4 + 20; 587 dirtybufthresh = hidirtybuffers * 9 / 10; 588 numdirtybuffers = 0; 589 /* 590 * To support extreme low-memory systems, make sure hidirtybuffers cannot 591 * eat up all available buffer space. This occurs when our minimum cannot 592 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 593 * BKVASIZE'd (8K) buffers. 594 */ 595 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 596 hidirtybuffers >>= 1; 597 } 598 lodirtybuffers = hidirtybuffers / 2; 599 600 /* 601 * Try to keep the number of free buffers in the specified range, 602 * and give special processes (e.g. like buf_daemon) access to an 603 * emergency reserve. 604 */ 605 lofreebuffers = nbuf / 18 + 5; 606 hifreebuffers = 2 * lofreebuffers; 607 numfreebuffers = nbuf; 608 609 /* 610 * Maximum number of async ops initiated per buf_daemon loop. This is 611 * somewhat of a hack at the moment, we really need to limit ourselves 612 * based on the number of bytes of I/O in-transit that were initiated 613 * from buf_daemon. 614 */ 615 616 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 617 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 618 } 619 620 /* 621 * bfreekva() - free the kva allocation for a buffer. 622 * 623 * Since this call frees up buffer space, we call bufspacewakeup(). 624 */ 625 static void 626 bfreekva(struct buf *bp) 627 { 628 629 if (bp->b_kvasize) { 630 atomic_add_int(&buffreekvacnt, 1); 631 atomic_subtract_int(&bufspace, bp->b_kvasize); 632 vm_map_lock(buffer_map); 633 vm_map_delete(buffer_map, 634 (vm_offset_t) bp->b_kvabase, 635 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 636 ); 637 vm_map_unlock(buffer_map); 638 bp->b_kvasize = 0; 639 bufspacewakeup(); 640 } 641 } 642 643 /* 644 * bremfree: 645 * 646 * Mark the buffer for removal from the appropriate free list in brelse. 647 * 648 */ 649 void 650 bremfree(struct buf *bp) 651 { 652 653 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 654 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked.")); 655 KASSERT((bp->b_flags & B_REMFREE) == 0, 656 ("bremfree: buffer %p already marked for delayed removal.", bp)); 657 KASSERT(bp->b_qindex != QUEUE_NONE, 658 ("bremfree: buffer %p not on a queue.", bp)); 659 660 bp->b_flags |= B_REMFREE; 661 /* Fixup numfreebuffers count. */ 662 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 663 atomic_subtract_int(&numfreebuffers, 1); 664 } 665 666 /* 667 * bremfreef: 668 * 669 * Force an immediate removal from a free list. Used only in nfs when 670 * it abuses the b_freelist pointer. 671 */ 672 void 673 bremfreef(struct buf *bp) 674 { 675 mtx_lock(&bqlock); 676 bremfreel(bp); 677 mtx_unlock(&bqlock); 678 } 679 680 /* 681 * bremfreel: 682 * 683 * Removes a buffer from the free list, must be called with the 684 * bqlock held. 685 */ 686 static void 687 bremfreel(struct buf *bp) 688 { 689 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 690 bp, bp->b_vp, bp->b_flags); 691 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp)); 692 KASSERT(bp->b_qindex != QUEUE_NONE, 693 ("bremfreel: buffer %p not on a queue.", bp)); 694 mtx_assert(&bqlock, MA_OWNED); 695 696 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 697 bp->b_qindex = QUEUE_NONE; 698 /* 699 * If this was a delayed bremfree() we only need to remove the buffer 700 * from the queue and return the stats are already done. 701 */ 702 if (bp->b_flags & B_REMFREE) { 703 bp->b_flags &= ~B_REMFREE; 704 return; 705 } 706 /* 707 * Fixup numfreebuffers count. If the buffer is invalid or not 708 * delayed-write, the buffer was free and we must decrement 709 * numfreebuffers. 710 */ 711 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 712 atomic_subtract_int(&numfreebuffers, 1); 713 } 714 715 716 /* 717 * Get a buffer with the specified data. Look in the cache first. We 718 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 719 * is set, the buffer is valid and we do not have to do anything ( see 720 * getblk() ). This is really just a special case of breadn(). 721 */ 722 int 723 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 724 struct buf **bpp) 725 { 726 727 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 728 } 729 730 /* 731 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 732 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 733 * the buffer is valid and we do not have to do anything. 734 */ 735 void 736 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 737 int cnt, struct ucred * cred) 738 { 739 struct buf *rabp; 740 int i; 741 742 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 743 if (inmem(vp, *rablkno)) 744 continue; 745 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 746 747 if ((rabp->b_flags & B_CACHE) == 0) { 748 if (curthread != PCPU_GET(idlethread)) 749 curthread->td_proc->p_stats->p_ru.ru_inblock++; 750 rabp->b_flags |= B_ASYNC; 751 rabp->b_flags &= ~B_INVAL; 752 rabp->b_ioflags &= ~BIO_ERROR; 753 rabp->b_iocmd = BIO_READ; 754 if (rabp->b_rcred == NOCRED && cred != NOCRED) 755 rabp->b_rcred = crhold(cred); 756 vfs_busy_pages(rabp, 0); 757 BUF_KERNPROC(rabp); 758 rabp->b_iooffset = dbtob(rabp->b_blkno); 759 bstrategy(rabp); 760 } else { 761 brelse(rabp); 762 } 763 } 764 } 765 766 /* 767 * Operates like bread, but also starts asynchronous I/O on 768 * read-ahead blocks. 769 */ 770 int 771 breadn(struct vnode * vp, daddr_t blkno, int size, 772 daddr_t * rablkno, int *rabsize, 773 int cnt, struct ucred * cred, struct buf **bpp) 774 { 775 struct buf *bp; 776 int rv = 0, readwait = 0; 777 778 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 779 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 780 781 /* if not found in cache, do some I/O */ 782 if ((bp->b_flags & B_CACHE) == 0) { 783 if (curthread != PCPU_GET(idlethread)) 784 curthread->td_proc->p_stats->p_ru.ru_inblock++; 785 bp->b_iocmd = BIO_READ; 786 bp->b_flags &= ~B_INVAL; 787 bp->b_ioflags &= ~BIO_ERROR; 788 if (bp->b_rcred == NOCRED && cred != NOCRED) 789 bp->b_rcred = crhold(cred); 790 vfs_busy_pages(bp, 0); 791 bp->b_iooffset = dbtob(bp->b_blkno); 792 bstrategy(bp); 793 ++readwait; 794 } 795 796 breada(vp, rablkno, rabsize, cnt, cred); 797 798 if (readwait) { 799 rv = bufwait(bp); 800 } 801 return (rv); 802 } 803 804 /* 805 * Write, release buffer on completion. (Done by iodone 806 * if async). Do not bother writing anything if the buffer 807 * is invalid. 808 * 809 * Note that we set B_CACHE here, indicating that buffer is 810 * fully valid and thus cacheable. This is true even of NFS 811 * now so we set it generally. This could be set either here 812 * or in biodone() since the I/O is synchronous. We put it 813 * here. 814 */ 815 int 816 bufwrite(struct buf *bp) 817 { 818 int oldflags; 819 struct vnode *vp; 820 int vp_md; 821 822 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 823 if (bp->b_flags & B_INVAL) { 824 brelse(bp); 825 return (0); 826 } 827 828 oldflags = bp->b_flags; 829 830 if (BUF_REFCNT(bp) == 0) 831 panic("bufwrite: buffer is not busy???"); 832 833 if (bp->b_pin_count > 0) 834 bunpin_wait(bp); 835 836 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 837 ("FFS background buffer should not get here %p", bp)); 838 839 vp = bp->b_vp; 840 if (vp) 841 vp_md = vp->v_vflag & VV_MD; 842 else 843 vp_md = 0; 844 845 /* Mark the buffer clean */ 846 bundirty(bp); 847 848 bp->b_flags &= ~B_DONE; 849 bp->b_ioflags &= ~BIO_ERROR; 850 bp->b_flags |= B_CACHE; 851 bp->b_iocmd = BIO_WRITE; 852 853 bufobj_wref(bp->b_bufobj); 854 vfs_busy_pages(bp, 1); 855 856 /* 857 * Normal bwrites pipeline writes 858 */ 859 bp->b_runningbufspace = bp->b_bufsize; 860 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 861 862 if (curthread != PCPU_GET(idlethread)) 863 curthread->td_proc->p_stats->p_ru.ru_oublock++; 864 if (oldflags & B_ASYNC) 865 BUF_KERNPROC(bp); 866 bp->b_iooffset = dbtob(bp->b_blkno); 867 bstrategy(bp); 868 869 if ((oldflags & B_ASYNC) == 0) { 870 int rtval = bufwait(bp); 871 brelse(bp); 872 return (rtval); 873 } else { 874 /* 875 * don't allow the async write to saturate the I/O 876 * system. We will not deadlock here because 877 * we are blocking waiting for I/O that is already in-progress 878 * to complete. We do not block here if it is the update 879 * or syncer daemon trying to clean up as that can lead 880 * to deadlock. 881 */ 882 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 883 waitrunningbufspace(); 884 } 885 886 return (0); 887 } 888 889 /* 890 * Delayed write. (Buffer is marked dirty). Do not bother writing 891 * anything if the buffer is marked invalid. 892 * 893 * Note that since the buffer must be completely valid, we can safely 894 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 895 * biodone() in order to prevent getblk from writing the buffer 896 * out synchronously. 897 */ 898 void 899 bdwrite(struct buf *bp) 900 { 901 struct thread *td = curthread; 902 struct vnode *vp; 903 struct buf *nbp; 904 struct bufobj *bo; 905 906 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 907 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 908 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy")); 909 910 if (bp->b_flags & B_INVAL) { 911 brelse(bp); 912 return; 913 } 914 915 /* 916 * If we have too many dirty buffers, don't create any more. 917 * If we are wildly over our limit, then force a complete 918 * cleanup. Otherwise, just keep the situation from getting 919 * out of control. Note that we have to avoid a recursive 920 * disaster and not try to clean up after our own cleanup! 921 */ 922 vp = bp->b_vp; 923 bo = bp->b_bufobj; 924 if ((td->td_pflags & TDP_COWINPROGRESS) == 0) { 925 BO_LOCK(bo); 926 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 927 BO_UNLOCK(bo); 928 (void) VOP_FSYNC(vp, MNT_NOWAIT, td); 929 altbufferflushes++; 930 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 931 /* 932 * Try to find a buffer to flush. 933 */ 934 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 935 if ((nbp->b_vflags & BV_BKGRDINPROG) || 936 BUF_LOCK(nbp, 937 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 938 continue; 939 if (bp == nbp) 940 panic("bdwrite: found ourselves"); 941 BO_UNLOCK(bo); 942 /* Don't countdeps with the bo lock held. */ 943 if (buf_countdeps(nbp, 0)) { 944 BO_LOCK(bo); 945 BUF_UNLOCK(nbp); 946 continue; 947 } 948 if (nbp->b_flags & B_CLUSTEROK) { 949 vfs_bio_awrite(nbp); 950 } else { 951 bremfree(nbp); 952 bawrite(nbp); 953 } 954 dirtybufferflushes++; 955 break; 956 } 957 if (nbp == NULL) 958 BO_UNLOCK(bo); 959 } else 960 BO_UNLOCK(bo); 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(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp)); 1037 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1038 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1039 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 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 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",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 && 1158 (bp->b_ioflags & BIO_ERROR) && 1159 !(bp->b_flags & B_INVAL)) { 1160 /* 1161 * Failed write, redirty. Must clear BIO_ERROR to prevent 1162 * pages from being scrapped. If B_INVAL is set then 1163 * this case is not run and the next case is run to 1164 * destroy the buffer. B_INVAL can occur if the buffer 1165 * is outside the range supported by the underlying device. 1166 */ 1167 bp->b_ioflags &= ~BIO_ERROR; 1168 bdirty(bp); 1169 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1170 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1171 /* 1172 * Either a failed I/O or we were asked to free or not 1173 * cache the buffer. 1174 */ 1175 bp->b_flags |= B_INVAL; 1176 if (LIST_FIRST(&bp->b_dep) != NULL) 1177 buf_deallocate(bp); 1178 if (bp->b_flags & B_DELWRI) { 1179 atomic_subtract_int(&numdirtybuffers, 1); 1180 numdirtywakeup(lodirtybuffers); 1181 } 1182 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1183 if ((bp->b_flags & B_VMIO) == 0) { 1184 if (bp->b_bufsize) 1185 allocbuf(bp, 0); 1186 if (bp->b_vp) 1187 brelvp(bp); 1188 } 1189 } 1190 1191 /* 1192 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1193 * is called with B_DELWRI set, the underlying pages may wind up 1194 * getting freed causing a previous write (bdwrite()) to get 'lost' 1195 * because pages associated with a B_DELWRI bp are marked clean. 1196 * 1197 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1198 * if B_DELWRI is set. 1199 * 1200 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1201 * on pages to return pages to the VM page queues. 1202 */ 1203 if (bp->b_flags & B_DELWRI) 1204 bp->b_flags &= ~B_RELBUF; 1205 else if (vm_page_count_severe()) { 1206 /* 1207 * XXX This lock may not be necessary since BKGRDINPROG 1208 * cannot be set while we hold the buf lock, it can only be 1209 * cleared if it is already pending. 1210 */ 1211 if (bp->b_vp) { 1212 BO_LOCK(bp->b_bufobj); 1213 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1214 bp->b_flags |= B_RELBUF; 1215 BO_UNLOCK(bp->b_bufobj); 1216 } else 1217 bp->b_flags |= B_RELBUF; 1218 } 1219 1220 /* 1221 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1222 * constituted, not even NFS buffers now. Two flags effect this. If 1223 * B_INVAL, the struct buf is invalidated but the VM object is kept 1224 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1225 * 1226 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1227 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1228 * buffer is also B_INVAL because it hits the re-dirtying code above. 1229 * 1230 * Normally we can do this whether a buffer is B_DELWRI or not. If 1231 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1232 * the commit state and we cannot afford to lose the buffer. If the 1233 * buffer has a background write in progress, we need to keep it 1234 * around to prevent it from being reconstituted and starting a second 1235 * background write. 1236 */ 1237 if ((bp->b_flags & B_VMIO) 1238 && !(bp->b_vp->v_mount != NULL && 1239 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1240 !vn_isdisk(bp->b_vp, NULL) && 1241 (bp->b_flags & B_DELWRI)) 1242 ) { 1243 1244 int i, j, resid; 1245 vm_page_t m; 1246 off_t foff; 1247 vm_pindex_t poff; 1248 vm_object_t obj; 1249 1250 obj = bp->b_bufobj->bo_object; 1251 1252 /* 1253 * Get the base offset and length of the buffer. Note that 1254 * in the VMIO case if the buffer block size is not 1255 * page-aligned then b_data pointer may not be page-aligned. 1256 * But our b_pages[] array *IS* page aligned. 1257 * 1258 * block sizes less then DEV_BSIZE (usually 512) are not 1259 * supported due to the page granularity bits (m->valid, 1260 * m->dirty, etc...). 1261 * 1262 * See man buf(9) for more information 1263 */ 1264 resid = bp->b_bufsize; 1265 foff = bp->b_offset; 1266 VM_OBJECT_LOCK(obj); 1267 for (i = 0; i < bp->b_npages; i++) { 1268 int had_bogus = 0; 1269 1270 m = bp->b_pages[i]; 1271 1272 /* 1273 * If we hit a bogus page, fixup *all* the bogus pages 1274 * now. 1275 */ 1276 if (m == bogus_page) { 1277 poff = OFF_TO_IDX(bp->b_offset); 1278 had_bogus = 1; 1279 1280 for (j = i; j < bp->b_npages; j++) { 1281 vm_page_t mtmp; 1282 mtmp = bp->b_pages[j]; 1283 if (mtmp == bogus_page) { 1284 mtmp = vm_page_lookup(obj, poff + j); 1285 if (!mtmp) { 1286 panic("brelse: page missing\n"); 1287 } 1288 bp->b_pages[j] = mtmp; 1289 } 1290 } 1291 1292 if ((bp->b_flags & B_INVAL) == 0) { 1293 pmap_qenter( 1294 trunc_page((vm_offset_t)bp->b_data), 1295 bp->b_pages, bp->b_npages); 1296 } 1297 m = bp->b_pages[i]; 1298 } 1299 if ((bp->b_flags & B_NOCACHE) || 1300 (bp->b_ioflags & BIO_ERROR)) { 1301 int poffset = foff & PAGE_MASK; 1302 int presid = resid > (PAGE_SIZE - poffset) ? 1303 (PAGE_SIZE - poffset) : resid; 1304 1305 KASSERT(presid >= 0, ("brelse: extra page")); 1306 vm_page_lock_queues(); 1307 vm_page_set_invalid(m, poffset, presid); 1308 vm_page_unlock_queues(); 1309 if (had_bogus) 1310 printf("avoided corruption bug in bogus_page/brelse code\n"); 1311 } 1312 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1313 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1314 } 1315 VM_OBJECT_UNLOCK(obj); 1316 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1317 vfs_vmio_release(bp); 1318 1319 } else if (bp->b_flags & B_VMIO) { 1320 1321 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1322 vfs_vmio_release(bp); 1323 } 1324 1325 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1326 if (bp->b_bufsize != 0) 1327 allocbuf(bp, 0); 1328 if (bp->b_vp != NULL) 1329 brelvp(bp); 1330 } 1331 1332 if (BUF_REFCNT(bp) > 1) { 1333 /* do not release to free list */ 1334 BUF_UNLOCK(bp); 1335 return; 1336 } 1337 1338 /* enqueue */ 1339 mtx_lock(&bqlock); 1340 /* Handle delayed bremfree() processing. */ 1341 if (bp->b_flags & B_REMFREE) 1342 bremfreel(bp); 1343 if (bp->b_qindex != QUEUE_NONE) 1344 panic("brelse: free buffer onto another queue???"); 1345 1346 /* buffers with no memory */ 1347 if (bp->b_bufsize == 0) { 1348 bp->b_flags |= B_INVAL; 1349 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1350 if (bp->b_vflags & BV_BKGRDINPROG) 1351 panic("losing buffer 1"); 1352 if (bp->b_kvasize) { 1353 bp->b_qindex = QUEUE_EMPTYKVA; 1354 } else { 1355 bp->b_qindex = QUEUE_EMPTY; 1356 } 1357 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1358 /* buffers with junk contents */ 1359 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1360 (bp->b_ioflags & BIO_ERROR)) { 1361 bp->b_flags |= B_INVAL; 1362 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1363 if (bp->b_vflags & BV_BKGRDINPROG) 1364 panic("losing buffer 2"); 1365 bp->b_qindex = QUEUE_CLEAN; 1366 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1367 /* remaining buffers */ 1368 } else { 1369 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1370 (B_DELWRI|B_NEEDSGIANT)) 1371 bp->b_qindex = QUEUE_DIRTY_GIANT; 1372 if (bp->b_flags & B_DELWRI) 1373 bp->b_qindex = QUEUE_DIRTY; 1374 else 1375 bp->b_qindex = QUEUE_CLEAN; 1376 if (bp->b_flags & B_AGE) 1377 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1378 else 1379 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1380 } 1381 mtx_unlock(&bqlock); 1382 1383 /* 1384 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1385 * placed the buffer on the correct queue. We must also disassociate 1386 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1387 * find it. 1388 */ 1389 if (bp->b_flags & B_INVAL) { 1390 if (bp->b_flags & B_DELWRI) 1391 bundirty(bp); 1392 if (bp->b_vp) 1393 brelvp(bp); 1394 } 1395 1396 /* 1397 * Fixup numfreebuffers count. The bp is on an appropriate queue 1398 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1399 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1400 * if B_INVAL is set ). 1401 */ 1402 1403 if (!(bp->b_flags & B_DELWRI)) 1404 bufcountwakeup(); 1405 1406 /* 1407 * Something we can maybe free or reuse 1408 */ 1409 if (bp->b_bufsize || bp->b_kvasize) 1410 bufspacewakeup(); 1411 1412 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1413 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1414 panic("brelse: not dirty"); 1415 /* unlock */ 1416 BUF_UNLOCK(bp); 1417 } 1418 1419 /* 1420 * Release a buffer back to the appropriate queue but do not try to free 1421 * it. The buffer is expected to be used again soon. 1422 * 1423 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1424 * biodone() to requeue an async I/O on completion. It is also used when 1425 * known good buffers need to be requeued but we think we may need the data 1426 * again soon. 1427 * 1428 * XXX we should be able to leave the B_RELBUF hint set on completion. 1429 */ 1430 void 1431 bqrelse(struct buf *bp) 1432 { 1433 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1434 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1435 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1436 1437 if (BUF_REFCNT(bp) > 1) { 1438 /* do not release to free list */ 1439 BUF_UNLOCK(bp); 1440 return; 1441 } 1442 1443 if (bp->b_flags & B_MANAGED) { 1444 if (bp->b_flags & B_REMFREE) { 1445 mtx_lock(&bqlock); 1446 bremfreel(bp); 1447 mtx_unlock(&bqlock); 1448 } 1449 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1450 BUF_UNLOCK(bp); 1451 return; 1452 } 1453 1454 mtx_lock(&bqlock); 1455 /* Handle delayed bremfree() processing. */ 1456 if (bp->b_flags & B_REMFREE) 1457 bremfreel(bp); 1458 if (bp->b_qindex != QUEUE_NONE) 1459 panic("bqrelse: free buffer onto another queue???"); 1460 /* buffers with stale but valid contents */ 1461 if (bp->b_flags & B_DELWRI) { 1462 if (bp->b_flags & B_NEEDSGIANT) 1463 bp->b_qindex = QUEUE_DIRTY_GIANT; 1464 else 1465 bp->b_qindex = QUEUE_DIRTY; 1466 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1467 } else { 1468 /* 1469 * XXX This lock may not be necessary since BKGRDINPROG 1470 * cannot be set while we hold the buf lock, it can only be 1471 * cleared if it is already pending. 1472 */ 1473 BO_LOCK(bp->b_bufobj); 1474 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1475 BO_UNLOCK(bp->b_bufobj); 1476 bp->b_qindex = QUEUE_CLEAN; 1477 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1478 b_freelist); 1479 } else { 1480 /* 1481 * We are too low on memory, we have to try to free 1482 * the buffer (most importantly: the wired pages 1483 * making up its backing store) *now*. 1484 */ 1485 BO_UNLOCK(bp->b_bufobj); 1486 mtx_unlock(&bqlock); 1487 brelse(bp); 1488 return; 1489 } 1490 } 1491 mtx_unlock(&bqlock); 1492 1493 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1494 bufcountwakeup(); 1495 1496 /* 1497 * Something we can maybe free or reuse. 1498 */ 1499 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1500 bufspacewakeup(); 1501 1502 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1503 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1504 panic("bqrelse: not dirty"); 1505 /* unlock */ 1506 BUF_UNLOCK(bp); 1507 } 1508 1509 /* Give pages used by the bp back to the VM system (where possible) */ 1510 static void 1511 vfs_vmio_release(struct buf *bp) 1512 { 1513 int i; 1514 vm_page_t m; 1515 1516 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1517 vm_page_lock_queues(); 1518 for (i = 0; i < bp->b_npages; i++) { 1519 m = bp->b_pages[i]; 1520 bp->b_pages[i] = NULL; 1521 /* 1522 * In order to keep page LRU ordering consistent, put 1523 * everything on the inactive queue. 1524 */ 1525 vm_page_unwire(m, 0); 1526 /* 1527 * We don't mess with busy pages, it is 1528 * the responsibility of the process that 1529 * busied the pages to deal with them. 1530 */ 1531 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1532 continue; 1533 1534 if (m->wire_count == 0) { 1535 /* 1536 * Might as well free the page if we can and it has 1537 * no valid data. We also free the page if the 1538 * buffer was used for direct I/O 1539 */ 1540 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1541 m->hold_count == 0) { 1542 vm_page_free(m); 1543 } else if (bp->b_flags & B_DIRECT) { 1544 vm_page_try_to_free(m); 1545 } else if (vm_page_count_severe()) { 1546 vm_page_try_to_cache(m); 1547 } 1548 } 1549 } 1550 vm_page_unlock_queues(); 1551 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1552 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1553 1554 if (bp->b_bufsize) { 1555 bufspacewakeup(); 1556 bp->b_bufsize = 0; 1557 } 1558 bp->b_npages = 0; 1559 bp->b_flags &= ~B_VMIO; 1560 if (bp->b_vp) 1561 brelvp(bp); 1562 } 1563 1564 /* 1565 * Check to see if a block at a particular lbn is available for a clustered 1566 * write. 1567 */ 1568 static int 1569 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1570 { 1571 struct buf *bpa; 1572 int match; 1573 1574 match = 0; 1575 1576 /* If the buf isn't in core skip it */ 1577 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1578 return (0); 1579 1580 /* If the buf is busy we don't want to wait for it */ 1581 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1582 return (0); 1583 1584 /* Only cluster with valid clusterable delayed write buffers */ 1585 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1586 (B_DELWRI | B_CLUSTEROK)) 1587 goto done; 1588 1589 if (bpa->b_bufsize != size) 1590 goto done; 1591 1592 /* 1593 * Check to see if it is in the expected place on disk and that the 1594 * block has been mapped. 1595 */ 1596 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1597 match = 1; 1598 done: 1599 BUF_UNLOCK(bpa); 1600 return (match); 1601 } 1602 1603 /* 1604 * vfs_bio_awrite: 1605 * 1606 * Implement clustered async writes for clearing out B_DELWRI buffers. 1607 * This is much better then the old way of writing only one buffer at 1608 * a time. Note that we may not be presented with the buffers in the 1609 * correct order, so we search for the cluster in both directions. 1610 */ 1611 int 1612 vfs_bio_awrite(struct buf *bp) 1613 { 1614 int i; 1615 int j; 1616 daddr_t lblkno = bp->b_lblkno; 1617 struct vnode *vp = bp->b_vp; 1618 int ncl; 1619 int nwritten; 1620 int size; 1621 int maxcl; 1622 1623 /* 1624 * right now we support clustered writing only to regular files. If 1625 * we find a clusterable block we could be in the middle of a cluster 1626 * rather then at the beginning. 1627 */ 1628 if ((vp->v_type == VREG) && 1629 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1630 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1631 1632 size = vp->v_mount->mnt_stat.f_iosize; 1633 maxcl = MAXPHYS / size; 1634 1635 VI_LOCK(vp); 1636 for (i = 1; i < maxcl; i++) 1637 if (vfs_bio_clcheck(vp, size, lblkno + i, 1638 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1639 break; 1640 1641 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1642 if (vfs_bio_clcheck(vp, size, lblkno - j, 1643 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1644 break; 1645 1646 VI_UNLOCK(vp); 1647 --j; 1648 ncl = i + j; 1649 /* 1650 * this is a possible cluster write 1651 */ 1652 if (ncl != 1) { 1653 BUF_UNLOCK(bp); 1654 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1655 return nwritten; 1656 } 1657 } 1658 bremfree(bp); 1659 bp->b_flags |= B_ASYNC; 1660 /* 1661 * default (old) behavior, writing out only one block 1662 * 1663 * XXX returns b_bufsize instead of b_bcount for nwritten? 1664 */ 1665 nwritten = bp->b_bufsize; 1666 (void) bwrite(bp); 1667 1668 return nwritten; 1669 } 1670 1671 /* 1672 * getnewbuf: 1673 * 1674 * Find and initialize a new buffer header, freeing up existing buffers 1675 * in the bufqueues as necessary. The new buffer is returned locked. 1676 * 1677 * Important: B_INVAL is not set. If the caller wishes to throw the 1678 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1679 * 1680 * We block if: 1681 * We have insufficient buffer headers 1682 * We have insufficient buffer space 1683 * buffer_map is too fragmented ( space reservation fails ) 1684 * If we have to flush dirty buffers ( but we try to avoid this ) 1685 * 1686 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1687 * Instead we ask the buf daemon to do it for us. We attempt to 1688 * avoid piecemeal wakeups of the pageout daemon. 1689 */ 1690 1691 static struct buf * 1692 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1693 { 1694 struct buf *bp; 1695 struct buf *nbp; 1696 int defrag = 0; 1697 int nqindex; 1698 static int flushingbufs; 1699 1700 /* 1701 * We can't afford to block since we might be holding a vnode lock, 1702 * which may prevent system daemons from running. We deal with 1703 * low-memory situations by proactively returning memory and running 1704 * async I/O rather then sync I/O. 1705 */ 1706 1707 atomic_add_int(&getnewbufcalls, 1); 1708 atomic_subtract_int(&getnewbufrestarts, 1); 1709 restart: 1710 atomic_add_int(&getnewbufrestarts, 1); 1711 1712 /* 1713 * Setup for scan. If we do not have enough free buffers, 1714 * we setup a degenerate case that immediately fails. Note 1715 * that if we are specially marked process, we are allowed to 1716 * dip into our reserves. 1717 * 1718 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1719 * 1720 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1721 * However, there are a number of cases (defragging, reusing, ...) 1722 * where we cannot backup. 1723 */ 1724 mtx_lock(&bqlock); 1725 nqindex = QUEUE_EMPTYKVA; 1726 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1727 1728 if (nbp == NULL) { 1729 /* 1730 * If no EMPTYKVA buffers and we are either 1731 * defragging or reusing, locate a CLEAN buffer 1732 * to free or reuse. If bufspace useage is low 1733 * skip this step so we can allocate a new buffer. 1734 */ 1735 if (defrag || bufspace >= lobufspace) { 1736 nqindex = QUEUE_CLEAN; 1737 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1738 } 1739 1740 /* 1741 * If we could not find or were not allowed to reuse a 1742 * CLEAN buffer, check to see if it is ok to use an EMPTY 1743 * buffer. We can only use an EMPTY buffer if allocating 1744 * its KVA would not otherwise run us out of buffer space. 1745 */ 1746 if (nbp == NULL && defrag == 0 && 1747 bufspace + maxsize < hibufspace) { 1748 nqindex = QUEUE_EMPTY; 1749 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1750 } 1751 } 1752 1753 /* 1754 * Run scan, possibly freeing data and/or kva mappings on the fly 1755 * depending. 1756 */ 1757 1758 while ((bp = nbp) != NULL) { 1759 int qindex = nqindex; 1760 1761 /* 1762 * Calculate next bp ( we can only use it if we do not block 1763 * or do other fancy things ). 1764 */ 1765 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1766 switch(qindex) { 1767 case QUEUE_EMPTY: 1768 nqindex = QUEUE_EMPTYKVA; 1769 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1770 break; 1771 /* FALLTHROUGH */ 1772 case QUEUE_EMPTYKVA: 1773 nqindex = QUEUE_CLEAN; 1774 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1775 break; 1776 /* FALLTHROUGH */ 1777 case QUEUE_CLEAN: 1778 /* 1779 * nbp is NULL. 1780 */ 1781 break; 1782 } 1783 } 1784 /* 1785 * If we are defragging then we need a buffer with 1786 * b_kvasize != 0. XXX this situation should no longer 1787 * occur, if defrag is non-zero the buffer's b_kvasize 1788 * should also be non-zero at this point. XXX 1789 */ 1790 if (defrag && bp->b_kvasize == 0) { 1791 printf("Warning: defrag empty buffer %p\n", bp); 1792 continue; 1793 } 1794 1795 /* 1796 * Start freeing the bp. This is somewhat involved. nbp 1797 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1798 */ 1799 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1800 continue; 1801 if (bp->b_vp) { 1802 BO_LOCK(bp->b_bufobj); 1803 if (bp->b_vflags & BV_BKGRDINPROG) { 1804 BO_UNLOCK(bp->b_bufobj); 1805 BUF_UNLOCK(bp); 1806 continue; 1807 } 1808 BO_UNLOCK(bp->b_bufobj); 1809 } 1810 CTR6(KTR_BUF, 1811 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1812 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1813 bp->b_kvasize, bp->b_bufsize, qindex); 1814 1815 /* 1816 * Sanity Checks 1817 */ 1818 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1819 1820 /* 1821 * Note: we no longer distinguish between VMIO and non-VMIO 1822 * buffers. 1823 */ 1824 1825 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1826 1827 bremfreel(bp); 1828 mtx_unlock(&bqlock); 1829 1830 if (qindex == QUEUE_CLEAN) { 1831 if (bp->b_flags & B_VMIO) { 1832 bp->b_flags &= ~B_ASYNC; 1833 vfs_vmio_release(bp); 1834 } 1835 if (bp->b_vp) 1836 brelvp(bp); 1837 } 1838 1839 /* 1840 * NOTE: nbp is now entirely invalid. We can only restart 1841 * the scan from this point on. 1842 * 1843 * Get the rest of the buffer freed up. b_kva* is still 1844 * valid after this operation. 1845 */ 1846 1847 if (bp->b_rcred != NOCRED) { 1848 crfree(bp->b_rcred); 1849 bp->b_rcred = NOCRED; 1850 } 1851 if (bp->b_wcred != NOCRED) { 1852 crfree(bp->b_wcred); 1853 bp->b_wcred = NOCRED; 1854 } 1855 if (LIST_FIRST(&bp->b_dep) != NULL) 1856 buf_deallocate(bp); 1857 if (bp->b_vflags & BV_BKGRDINPROG) 1858 panic("losing buffer 3"); 1859 KASSERT(bp->b_vp == NULL, 1860 ("bp: %p still has vnode %p. qindex: %d", 1861 bp, bp->b_vp, qindex)); 1862 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1863 ("bp: %p still on a buffer list. xflags %X", 1864 bp, bp->b_xflags)); 1865 1866 if (bp->b_bufsize) 1867 allocbuf(bp, 0); 1868 1869 bp->b_flags = 0; 1870 bp->b_ioflags = 0; 1871 bp->b_xflags = 0; 1872 bp->b_vflags = 0; 1873 bp->b_vp = NULL; 1874 bp->b_blkno = bp->b_lblkno = 0; 1875 bp->b_offset = NOOFFSET; 1876 bp->b_iodone = 0; 1877 bp->b_error = 0; 1878 bp->b_resid = 0; 1879 bp->b_bcount = 0; 1880 bp->b_npages = 0; 1881 bp->b_dirtyoff = bp->b_dirtyend = 0; 1882 bp->b_bufobj = NULL; 1883 bp->b_pin_count = 0; 1884 bp->b_fsprivate1 = NULL; 1885 bp->b_fsprivate2 = NULL; 1886 bp->b_fsprivate3 = NULL; 1887 1888 LIST_INIT(&bp->b_dep); 1889 1890 /* 1891 * If we are defragging then free the buffer. 1892 */ 1893 if (defrag) { 1894 bp->b_flags |= B_INVAL; 1895 bfreekva(bp); 1896 brelse(bp); 1897 defrag = 0; 1898 goto restart; 1899 } 1900 1901 /* 1902 * Notify any waiters for the buffer lock about 1903 * identity change by freeing the buffer. 1904 */ 1905 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) { 1906 bp->b_flags |= B_INVAL; 1907 bfreekva(bp); 1908 brelse(bp); 1909 goto restart; 1910 } 1911 1912 /* 1913 * If we are overcomitted then recover the buffer and its 1914 * KVM space. This occurs in rare situations when multiple 1915 * processes are blocked in getnewbuf() or allocbuf(). 1916 */ 1917 if (bufspace >= hibufspace) 1918 flushingbufs = 1; 1919 if (flushingbufs && bp->b_kvasize != 0) { 1920 bp->b_flags |= B_INVAL; 1921 bfreekva(bp); 1922 brelse(bp); 1923 goto restart; 1924 } 1925 if (bufspace < lobufspace) 1926 flushingbufs = 0; 1927 break; 1928 } 1929 1930 /* 1931 * If we exhausted our list, sleep as appropriate. We may have to 1932 * wakeup various daemons and write out some dirty buffers. 1933 * 1934 * Generally we are sleeping due to insufficient buffer space. 1935 */ 1936 1937 if (bp == NULL) { 1938 int flags; 1939 char *waitmsg; 1940 1941 if (defrag) { 1942 flags = VFS_BIO_NEED_BUFSPACE; 1943 waitmsg = "nbufkv"; 1944 } else if (bufspace >= hibufspace) { 1945 waitmsg = "nbufbs"; 1946 flags = VFS_BIO_NEED_BUFSPACE; 1947 } else { 1948 waitmsg = "newbuf"; 1949 flags = VFS_BIO_NEED_ANY; 1950 } 1951 mtx_lock(&nblock); 1952 needsbuffer |= flags; 1953 mtx_unlock(&nblock); 1954 mtx_unlock(&bqlock); 1955 1956 bd_speedup(); /* heeeelp */ 1957 1958 mtx_lock(&nblock); 1959 while (needsbuffer & flags) { 1960 if (msleep(&needsbuffer, &nblock, 1961 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1962 mtx_unlock(&nblock); 1963 return (NULL); 1964 } 1965 } 1966 mtx_unlock(&nblock); 1967 } else { 1968 /* 1969 * We finally have a valid bp. We aren't quite out of the 1970 * woods, we still have to reserve kva space. In order 1971 * to keep fragmentation sane we only allocate kva in 1972 * BKVASIZE chunks. 1973 */ 1974 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1975 1976 if (maxsize != bp->b_kvasize) { 1977 vm_offset_t addr = 0; 1978 1979 bfreekva(bp); 1980 1981 vm_map_lock(buffer_map); 1982 if (vm_map_findspace(buffer_map, 1983 vm_map_min(buffer_map), maxsize, &addr)) { 1984 /* 1985 * Uh oh. Buffer map is to fragmented. We 1986 * must defragment the map. 1987 */ 1988 atomic_add_int(&bufdefragcnt, 1); 1989 vm_map_unlock(buffer_map); 1990 defrag = 1; 1991 bp->b_flags |= B_INVAL; 1992 brelse(bp); 1993 goto restart; 1994 } 1995 if (addr) { 1996 vm_map_insert(buffer_map, NULL, 0, 1997 addr, addr + maxsize, 1998 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 1999 2000 bp->b_kvabase = (caddr_t) addr; 2001 bp->b_kvasize = maxsize; 2002 atomic_add_int(&bufspace, bp->b_kvasize); 2003 atomic_add_int(&bufreusecnt, 1); 2004 } 2005 vm_map_unlock(buffer_map); 2006 } 2007 bp->b_saveaddr = bp->b_kvabase; 2008 bp->b_data = bp->b_saveaddr; 2009 } 2010 return(bp); 2011 } 2012 2013 /* 2014 * buf_daemon: 2015 * 2016 * buffer flushing daemon. Buffers are normally flushed by the 2017 * update daemon but if it cannot keep up this process starts to 2018 * take the load in an attempt to prevent getnewbuf() from blocking. 2019 */ 2020 2021 static struct kproc_desc buf_kp = { 2022 "bufdaemon", 2023 buf_daemon, 2024 &bufdaemonproc 2025 }; 2026 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2027 2028 static void 2029 buf_daemon() 2030 { 2031 2032 /* 2033 * This process needs to be suspended prior to shutdown sync. 2034 */ 2035 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2036 SHUTDOWN_PRI_LAST); 2037 2038 /* 2039 * This process is allowed to take the buffer cache to the limit 2040 */ 2041 curthread->td_pflags |= TDP_NORUNNINGBUF; 2042 mtx_lock(&bdlock); 2043 for (;;) { 2044 bd_request = 0; 2045 mtx_unlock(&bdlock); 2046 2047 kthread_suspend_check(bufdaemonproc); 2048 2049 /* 2050 * Do the flush. Limit the amount of in-transit I/O we 2051 * allow to build up, otherwise we would completely saturate 2052 * the I/O system. Wakeup any waiting processes before we 2053 * normally would so they can run in parallel with our drain. 2054 */ 2055 while (numdirtybuffers > lodirtybuffers) { 2056 int flushed; 2057 2058 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2059 /* The list empty check here is slightly racy */ 2060 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2061 mtx_lock(&Giant); 2062 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2063 mtx_unlock(&Giant); 2064 } 2065 if (flushed == 0) { 2066 /* 2067 * Could not find any buffers without rollback 2068 * dependencies, so just write the first one 2069 * in the hopes of eventually making progress. 2070 */ 2071 flushbufqueues(QUEUE_DIRTY, 1); 2072 if (!TAILQ_EMPTY( 2073 &bufqueues[QUEUE_DIRTY_GIANT])) { 2074 mtx_lock(&Giant); 2075 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2076 mtx_unlock(&Giant); 2077 } 2078 break; 2079 } 2080 uio_yield(); 2081 } 2082 2083 /* 2084 * Only clear bd_request if we have reached our low water 2085 * mark. The buf_daemon normally waits 1 second and 2086 * then incrementally flushes any dirty buffers that have 2087 * built up, within reason. 2088 * 2089 * If we were unable to hit our low water mark and couldn't 2090 * find any flushable buffers, we sleep half a second. 2091 * Otherwise we loop immediately. 2092 */ 2093 mtx_lock(&bdlock); 2094 if (numdirtybuffers <= lodirtybuffers) { 2095 /* 2096 * We reached our low water mark, reset the 2097 * request and sleep until we are needed again. 2098 * The sleep is just so the suspend code works. 2099 */ 2100 bd_request = 0; 2101 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2102 } else { 2103 /* 2104 * We couldn't find any flushable dirty buffers but 2105 * still have too many dirty buffers, we 2106 * have to sleep and try again. (rare) 2107 */ 2108 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2109 } 2110 } 2111 } 2112 2113 /* 2114 * flushbufqueues: 2115 * 2116 * Try to flush a buffer in the dirty queue. We must be careful to 2117 * free up B_INVAL buffers instead of write them, which NFS is 2118 * particularly sensitive to. 2119 */ 2120 static int flushwithdeps = 0; 2121 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2122 0, "Number of buffers flushed with dependecies that require rollbacks"); 2123 2124 static int 2125 flushbufqueues(int queue, int flushdeps) 2126 { 2127 struct thread *td = curthread; 2128 struct buf sentinel; 2129 struct vnode *vp; 2130 struct mount *mp; 2131 struct buf *bp; 2132 int hasdeps; 2133 int flushed; 2134 int target; 2135 2136 target = numdirtybuffers - lodirtybuffers; 2137 if (flushdeps && target > 2) 2138 target /= 2; 2139 flushed = 0; 2140 bp = NULL; 2141 mtx_lock(&bqlock); 2142 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2143 while (flushed != target) { 2144 bp = TAILQ_FIRST(&bufqueues[queue]); 2145 if (bp == &sentinel) 2146 break; 2147 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2148 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2149 2150 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2151 continue; 2152 if (bp->b_pin_count > 0) { 2153 BUF_UNLOCK(bp); 2154 continue; 2155 } 2156 BO_LOCK(bp->b_bufobj); 2157 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2158 (bp->b_flags & B_DELWRI) == 0) { 2159 BO_UNLOCK(bp->b_bufobj); 2160 BUF_UNLOCK(bp); 2161 continue; 2162 } 2163 BO_UNLOCK(bp->b_bufobj); 2164 if (bp->b_flags & B_INVAL) { 2165 bremfreel(bp); 2166 mtx_unlock(&bqlock); 2167 brelse(bp); 2168 flushed++; 2169 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2170 mtx_lock(&bqlock); 2171 continue; 2172 } 2173 2174 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2175 if (flushdeps == 0) { 2176 BUF_UNLOCK(bp); 2177 continue; 2178 } 2179 hasdeps = 1; 2180 } else 2181 hasdeps = 0; 2182 /* 2183 * We must hold the lock on a vnode before writing 2184 * one of its buffers. Otherwise we may confuse, or 2185 * in the case of a snapshot vnode, deadlock the 2186 * system. 2187 * 2188 * The lock order here is the reverse of the normal 2189 * of vnode followed by buf lock. This is ok because 2190 * the NOWAIT will prevent deadlock. 2191 */ 2192 vp = bp->b_vp; 2193 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2194 BUF_UNLOCK(bp); 2195 continue; 2196 } 2197 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2198 mtx_unlock(&bqlock); 2199 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2200 bp, bp->b_vp, bp->b_flags); 2201 vfs_bio_awrite(bp); 2202 vn_finished_write(mp); 2203 VOP_UNLOCK(vp, 0, td); 2204 flushwithdeps += hasdeps; 2205 flushed++; 2206 waitrunningbufspace(); 2207 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2208 mtx_lock(&bqlock); 2209 continue; 2210 } 2211 vn_finished_write(mp); 2212 BUF_UNLOCK(bp); 2213 } 2214 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2215 mtx_unlock(&bqlock); 2216 return (flushed); 2217 } 2218 2219 /* 2220 * Check to see if a block is currently memory resident. 2221 */ 2222 struct buf * 2223 incore(struct bufobj *bo, daddr_t blkno) 2224 { 2225 struct buf *bp; 2226 2227 BO_LOCK(bo); 2228 bp = gbincore(bo, blkno); 2229 BO_UNLOCK(bo); 2230 return (bp); 2231 } 2232 2233 /* 2234 * Returns true if no I/O is needed to access the 2235 * associated VM object. This is like incore except 2236 * it also hunts around in the VM system for the data. 2237 */ 2238 2239 static int 2240 inmem(struct vnode * vp, daddr_t blkno) 2241 { 2242 vm_object_t obj; 2243 vm_offset_t toff, tinc, size; 2244 vm_page_t m; 2245 vm_ooffset_t off; 2246 2247 ASSERT_VOP_LOCKED(vp, "inmem"); 2248 2249 if (incore(&vp->v_bufobj, blkno)) 2250 return 1; 2251 if (vp->v_mount == NULL) 2252 return 0; 2253 obj = vp->v_object; 2254 if (obj == NULL) 2255 return (0); 2256 2257 size = PAGE_SIZE; 2258 if (size > vp->v_mount->mnt_stat.f_iosize) 2259 size = vp->v_mount->mnt_stat.f_iosize; 2260 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2261 2262 VM_OBJECT_LOCK(obj); 2263 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2264 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2265 if (!m) 2266 goto notinmem; 2267 tinc = size; 2268 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2269 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2270 if (vm_page_is_valid(m, 2271 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2272 goto notinmem; 2273 } 2274 VM_OBJECT_UNLOCK(obj); 2275 return 1; 2276 2277 notinmem: 2278 VM_OBJECT_UNLOCK(obj); 2279 return (0); 2280 } 2281 2282 /* 2283 * vfs_setdirty: 2284 * 2285 * Sets the dirty range for a buffer based on the status of the dirty 2286 * bits in the pages comprising the buffer. 2287 * 2288 * The range is limited to the size of the buffer. 2289 * 2290 * This routine is primarily used by NFS, but is generalized for the 2291 * B_VMIO case. 2292 */ 2293 static void 2294 vfs_setdirty(struct buf *bp) 2295 { 2296 2297 /* 2298 * Degenerate case - empty buffer 2299 */ 2300 2301 if (bp->b_bufsize == 0) 2302 return; 2303 2304 /* 2305 * We qualify the scan for modified pages on whether the 2306 * object has been flushed yet. 2307 */ 2308 2309 if ((bp->b_flags & B_VMIO) == 0) 2310 return; 2311 2312 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2313 vfs_setdirty_locked_object(bp); 2314 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2315 } 2316 2317 static void 2318 vfs_setdirty_locked_object(struct buf *bp) 2319 { 2320 vm_object_t object; 2321 int i; 2322 2323 object = bp->b_bufobj->bo_object; 2324 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2325 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2326 vm_offset_t boffset; 2327 vm_offset_t eoffset; 2328 2329 vm_page_lock_queues(); 2330 /* 2331 * test the pages to see if they have been modified directly 2332 * by users through the VM system. 2333 */ 2334 for (i = 0; i < bp->b_npages; i++) 2335 vm_page_test_dirty(bp->b_pages[i]); 2336 2337 /* 2338 * Calculate the encompassing dirty range, boffset and eoffset, 2339 * (eoffset - boffset) bytes. 2340 */ 2341 2342 for (i = 0; i < bp->b_npages; i++) { 2343 if (bp->b_pages[i]->dirty) 2344 break; 2345 } 2346 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2347 2348 for (i = bp->b_npages - 1; i >= 0; --i) { 2349 if (bp->b_pages[i]->dirty) { 2350 break; 2351 } 2352 } 2353 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2354 2355 vm_page_unlock_queues(); 2356 /* 2357 * Fit it to the buffer. 2358 */ 2359 2360 if (eoffset > bp->b_bcount) 2361 eoffset = bp->b_bcount; 2362 2363 /* 2364 * If we have a good dirty range, merge with the existing 2365 * dirty range. 2366 */ 2367 2368 if (boffset < eoffset) { 2369 if (bp->b_dirtyoff > boffset) 2370 bp->b_dirtyoff = boffset; 2371 if (bp->b_dirtyend < eoffset) 2372 bp->b_dirtyend = eoffset; 2373 } 2374 } 2375 } 2376 2377 /* 2378 * getblk: 2379 * 2380 * Get a block given a specified block and offset into a file/device. 2381 * The buffers B_DONE bit will be cleared on return, making it almost 2382 * ready for an I/O initiation. B_INVAL may or may not be set on 2383 * return. The caller should clear B_INVAL prior to initiating a 2384 * READ. 2385 * 2386 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2387 * an existing buffer. 2388 * 2389 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2390 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2391 * and then cleared based on the backing VM. If the previous buffer is 2392 * non-0-sized but invalid, B_CACHE will be cleared. 2393 * 2394 * If getblk() must create a new buffer, the new buffer is returned with 2395 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2396 * case it is returned with B_INVAL clear and B_CACHE set based on the 2397 * backing VM. 2398 * 2399 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2400 * B_CACHE bit is clear. 2401 * 2402 * What this means, basically, is that the caller should use B_CACHE to 2403 * determine whether the buffer is fully valid or not and should clear 2404 * B_INVAL prior to issuing a read. If the caller intends to validate 2405 * the buffer by loading its data area with something, the caller needs 2406 * to clear B_INVAL. If the caller does this without issuing an I/O, 2407 * the caller should set B_CACHE ( as an optimization ), else the caller 2408 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2409 * a write attempt or if it was a successfull read. If the caller 2410 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2411 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2412 */ 2413 struct buf * 2414 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2415 int flags) 2416 { 2417 struct buf *bp; 2418 struct bufobj *bo; 2419 int error; 2420 2421 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2422 ASSERT_VOP_LOCKED(vp, "getblk"); 2423 if (size > MAXBSIZE) 2424 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2425 2426 bo = &vp->v_bufobj; 2427 loop: 2428 /* 2429 * Block if we are low on buffers. Certain processes are allowed 2430 * to completely exhaust the buffer cache. 2431 * 2432 * If this check ever becomes a bottleneck it may be better to 2433 * move it into the else, when gbincore() fails. At the moment 2434 * it isn't a problem. 2435 * 2436 * XXX remove if 0 sections (clean this up after its proven) 2437 */ 2438 if (numfreebuffers == 0) { 2439 if (curthread == PCPU_GET(idlethread)) 2440 return NULL; 2441 mtx_lock(&nblock); 2442 needsbuffer |= VFS_BIO_NEED_ANY; 2443 mtx_unlock(&nblock); 2444 } 2445 2446 VI_LOCK(vp); 2447 bp = gbincore(bo, blkno); 2448 if (bp != NULL) { 2449 int lockflags; 2450 /* 2451 * Buffer is in-core. If the buffer is not busy, it must 2452 * be on a queue. 2453 */ 2454 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2455 2456 if (flags & GB_LOCK_NOWAIT) 2457 lockflags |= LK_NOWAIT; 2458 2459 error = BUF_TIMELOCK(bp, lockflags, 2460 VI_MTX(vp), "getblk", slpflag, slptimeo); 2461 2462 /* 2463 * If we slept and got the lock we have to restart in case 2464 * the buffer changed identities. 2465 */ 2466 if (error == ENOLCK) 2467 goto loop; 2468 /* We timed out or were interrupted. */ 2469 else if (error) 2470 return (NULL); 2471 2472 /* 2473 * The buffer is locked. B_CACHE is cleared if the buffer is 2474 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2475 * and for a VMIO buffer B_CACHE is adjusted according to the 2476 * backing VM cache. 2477 */ 2478 if (bp->b_flags & B_INVAL) 2479 bp->b_flags &= ~B_CACHE; 2480 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2481 bp->b_flags |= B_CACHE; 2482 bremfree(bp); 2483 2484 /* 2485 * check for size inconsistancies for non-VMIO case. 2486 */ 2487 2488 if (bp->b_bcount != size) { 2489 if ((bp->b_flags & B_VMIO) == 0 || 2490 (size > bp->b_kvasize)) { 2491 if (bp->b_flags & B_DELWRI) { 2492 /* 2493 * If buffer is pinned and caller does 2494 * not want sleep waiting for it to be 2495 * unpinned, bail out 2496 * */ 2497 if (bp->b_pin_count > 0) { 2498 if (flags & GB_LOCK_NOWAIT) { 2499 bqrelse(bp); 2500 return (NULL); 2501 } else { 2502 bunpin_wait(bp); 2503 } 2504 } 2505 bp->b_flags |= B_NOCACHE; 2506 bwrite(bp); 2507 } else { 2508 if (LIST_FIRST(&bp->b_dep) == NULL) { 2509 bp->b_flags |= B_RELBUF; 2510 brelse(bp); 2511 } else { 2512 bp->b_flags |= B_NOCACHE; 2513 bwrite(bp); 2514 } 2515 } 2516 goto loop; 2517 } 2518 } 2519 2520 /* 2521 * If the size is inconsistant in the VMIO case, we can resize 2522 * the buffer. This might lead to B_CACHE getting set or 2523 * cleared. If the size has not changed, B_CACHE remains 2524 * unchanged from its previous state. 2525 */ 2526 2527 if (bp->b_bcount != size) 2528 allocbuf(bp, size); 2529 2530 KASSERT(bp->b_offset != NOOFFSET, 2531 ("getblk: no buffer offset")); 2532 2533 /* 2534 * A buffer with B_DELWRI set and B_CACHE clear must 2535 * be committed before we can return the buffer in 2536 * order to prevent the caller from issuing a read 2537 * ( due to B_CACHE not being set ) and overwriting 2538 * it. 2539 * 2540 * Most callers, including NFS and FFS, need this to 2541 * operate properly either because they assume they 2542 * can issue a read if B_CACHE is not set, or because 2543 * ( for example ) an uncached B_DELWRI might loop due 2544 * to softupdates re-dirtying the buffer. In the latter 2545 * case, B_CACHE is set after the first write completes, 2546 * preventing further loops. 2547 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2548 * above while extending the buffer, we cannot allow the 2549 * buffer to remain with B_CACHE set after the write 2550 * completes or it will represent a corrupt state. To 2551 * deal with this we set B_NOCACHE to scrap the buffer 2552 * after the write. 2553 * 2554 * We might be able to do something fancy, like setting 2555 * B_CACHE in bwrite() except if B_DELWRI is already set, 2556 * so the below call doesn't set B_CACHE, but that gets real 2557 * confusing. This is much easier. 2558 */ 2559 2560 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2561 bp->b_flags |= B_NOCACHE; 2562 bwrite(bp); 2563 goto loop; 2564 } 2565 bp->b_flags &= ~B_DONE; 2566 } else { 2567 int bsize, maxsize, vmio; 2568 off_t offset; 2569 2570 /* 2571 * Buffer is not in-core, create new buffer. The buffer 2572 * returned by getnewbuf() is locked. Note that the returned 2573 * buffer is also considered valid (not marked B_INVAL). 2574 */ 2575 VI_UNLOCK(vp); 2576 /* 2577 * If the user does not want us to create the buffer, bail out 2578 * here. 2579 */ 2580 if (flags & GB_NOCREAT) 2581 return NULL; 2582 bsize = bo->bo_bsize; 2583 offset = blkno * bsize; 2584 vmio = vp->v_object != NULL; 2585 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2586 maxsize = imax(maxsize, bsize); 2587 2588 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2589 if (bp == NULL) { 2590 if (slpflag || slptimeo) 2591 return NULL; 2592 goto loop; 2593 } 2594 2595 /* 2596 * This code is used to make sure that a buffer is not 2597 * created while the getnewbuf routine is blocked. 2598 * This can be a problem whether the vnode is locked or not. 2599 * If the buffer is created out from under us, we have to 2600 * throw away the one we just created. 2601 * 2602 * Note: this must occur before we associate the buffer 2603 * with the vp especially considering limitations in 2604 * the splay tree implementation when dealing with duplicate 2605 * lblkno's. 2606 */ 2607 BO_LOCK(bo); 2608 if (gbincore(bo, blkno)) { 2609 BO_UNLOCK(bo); 2610 bp->b_flags |= B_INVAL; 2611 brelse(bp); 2612 goto loop; 2613 } 2614 2615 /* 2616 * Insert the buffer into the hash, so that it can 2617 * be found by incore. 2618 */ 2619 bp->b_blkno = bp->b_lblkno = blkno; 2620 bp->b_offset = offset; 2621 bgetvp(vp, bp); 2622 BO_UNLOCK(bo); 2623 2624 /* 2625 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2626 * buffer size starts out as 0, B_CACHE will be set by 2627 * allocbuf() for the VMIO case prior to it testing the 2628 * backing store for validity. 2629 */ 2630 2631 if (vmio) { 2632 bp->b_flags |= B_VMIO; 2633 #if defined(VFS_BIO_DEBUG) 2634 if (vn_canvmio(vp) != TRUE) 2635 printf("getblk: VMIO on vnode type %d\n", 2636 vp->v_type); 2637 #endif 2638 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2639 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2640 bp, vp->v_object, bp->b_bufobj->bo_object)); 2641 } else { 2642 bp->b_flags &= ~B_VMIO; 2643 KASSERT(bp->b_bufobj->bo_object == NULL, 2644 ("ARGH! has b_bufobj->bo_object %p %p\n", 2645 bp, bp->b_bufobj->bo_object)); 2646 } 2647 2648 allocbuf(bp, size); 2649 bp->b_flags &= ~B_DONE; 2650 } 2651 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2652 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2653 KASSERT(bp->b_bufobj == bo, 2654 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2655 return (bp); 2656 } 2657 2658 /* 2659 * Get an empty, disassociated buffer of given size. The buffer is initially 2660 * set to B_INVAL. 2661 */ 2662 struct buf * 2663 geteblk(int size) 2664 { 2665 struct buf *bp; 2666 int maxsize; 2667 2668 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2669 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2670 continue; 2671 allocbuf(bp, size); 2672 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2673 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2674 return (bp); 2675 } 2676 2677 2678 /* 2679 * This code constitutes the buffer memory from either anonymous system 2680 * memory (in the case of non-VMIO operations) or from an associated 2681 * VM object (in the case of VMIO operations). This code is able to 2682 * resize a buffer up or down. 2683 * 2684 * Note that this code is tricky, and has many complications to resolve 2685 * deadlock or inconsistant data situations. Tread lightly!!! 2686 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2687 * the caller. Calling this code willy nilly can result in the loss of data. 2688 * 2689 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2690 * B_CACHE for the non-VMIO case. 2691 */ 2692 2693 int 2694 allocbuf(struct buf *bp, int size) 2695 { 2696 int newbsize, mbsize; 2697 int i; 2698 2699 if (BUF_REFCNT(bp) == 0) 2700 panic("allocbuf: buffer not busy"); 2701 2702 if (bp->b_kvasize < size) 2703 panic("allocbuf: buffer too small"); 2704 2705 if ((bp->b_flags & B_VMIO) == 0) { 2706 caddr_t origbuf; 2707 int origbufsize; 2708 /* 2709 * Just get anonymous memory from the kernel. Don't 2710 * mess with B_CACHE. 2711 */ 2712 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2713 if (bp->b_flags & B_MALLOC) 2714 newbsize = mbsize; 2715 else 2716 newbsize = round_page(size); 2717 2718 if (newbsize < bp->b_bufsize) { 2719 /* 2720 * malloced buffers are not shrunk 2721 */ 2722 if (bp->b_flags & B_MALLOC) { 2723 if (newbsize) { 2724 bp->b_bcount = size; 2725 } else { 2726 free(bp->b_data, M_BIOBUF); 2727 if (bp->b_bufsize) { 2728 atomic_subtract_int( 2729 &bufmallocspace, 2730 bp->b_bufsize); 2731 bufspacewakeup(); 2732 bp->b_bufsize = 0; 2733 } 2734 bp->b_saveaddr = bp->b_kvabase; 2735 bp->b_data = bp->b_saveaddr; 2736 bp->b_bcount = 0; 2737 bp->b_flags &= ~B_MALLOC; 2738 } 2739 return 1; 2740 } 2741 vm_hold_free_pages( 2742 bp, 2743 (vm_offset_t) bp->b_data + newbsize, 2744 (vm_offset_t) bp->b_data + bp->b_bufsize); 2745 } else if (newbsize > bp->b_bufsize) { 2746 /* 2747 * We only use malloced memory on the first allocation. 2748 * and revert to page-allocated memory when the buffer 2749 * grows. 2750 */ 2751 /* 2752 * There is a potential smp race here that could lead 2753 * to bufmallocspace slightly passing the max. It 2754 * is probably extremely rare and not worth worrying 2755 * over. 2756 */ 2757 if ( (bufmallocspace < maxbufmallocspace) && 2758 (bp->b_bufsize == 0) && 2759 (mbsize <= PAGE_SIZE/2)) { 2760 2761 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2762 bp->b_bufsize = mbsize; 2763 bp->b_bcount = size; 2764 bp->b_flags |= B_MALLOC; 2765 atomic_add_int(&bufmallocspace, mbsize); 2766 return 1; 2767 } 2768 origbuf = NULL; 2769 origbufsize = 0; 2770 /* 2771 * If the buffer is growing on its other-than-first allocation, 2772 * then we revert to the page-allocation scheme. 2773 */ 2774 if (bp->b_flags & B_MALLOC) { 2775 origbuf = bp->b_data; 2776 origbufsize = bp->b_bufsize; 2777 bp->b_data = bp->b_kvabase; 2778 if (bp->b_bufsize) { 2779 atomic_subtract_int(&bufmallocspace, 2780 bp->b_bufsize); 2781 bufspacewakeup(); 2782 bp->b_bufsize = 0; 2783 } 2784 bp->b_flags &= ~B_MALLOC; 2785 newbsize = round_page(newbsize); 2786 } 2787 vm_hold_load_pages( 2788 bp, 2789 (vm_offset_t) bp->b_data + bp->b_bufsize, 2790 (vm_offset_t) bp->b_data + newbsize); 2791 if (origbuf) { 2792 bcopy(origbuf, bp->b_data, origbufsize); 2793 free(origbuf, M_BIOBUF); 2794 } 2795 } 2796 } else { 2797 int desiredpages; 2798 2799 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2800 desiredpages = (size == 0) ? 0 : 2801 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2802 2803 if (bp->b_flags & B_MALLOC) 2804 panic("allocbuf: VMIO buffer can't be malloced"); 2805 /* 2806 * Set B_CACHE initially if buffer is 0 length or will become 2807 * 0-length. 2808 */ 2809 if (size == 0 || bp->b_bufsize == 0) 2810 bp->b_flags |= B_CACHE; 2811 2812 if (newbsize < bp->b_bufsize) { 2813 /* 2814 * DEV_BSIZE aligned new buffer size is less then the 2815 * DEV_BSIZE aligned existing buffer size. Figure out 2816 * if we have to remove any pages. 2817 */ 2818 if (desiredpages < bp->b_npages) { 2819 vm_page_t m; 2820 2821 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2822 vm_page_lock_queues(); 2823 for (i = desiredpages; i < bp->b_npages; i++) { 2824 /* 2825 * the page is not freed here -- it 2826 * is the responsibility of 2827 * vnode_pager_setsize 2828 */ 2829 m = bp->b_pages[i]; 2830 KASSERT(m != bogus_page, 2831 ("allocbuf: bogus page found")); 2832 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2833 vm_page_lock_queues(); 2834 2835 bp->b_pages[i] = NULL; 2836 vm_page_unwire(m, 0); 2837 } 2838 vm_page_unlock_queues(); 2839 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2840 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2841 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2842 bp->b_npages = desiredpages; 2843 } 2844 } else if (size > bp->b_bcount) { 2845 /* 2846 * We are growing the buffer, possibly in a 2847 * byte-granular fashion. 2848 */ 2849 struct vnode *vp; 2850 vm_object_t obj; 2851 vm_offset_t toff; 2852 vm_offset_t tinc; 2853 2854 /* 2855 * Step 1, bring in the VM pages from the object, 2856 * allocating them if necessary. We must clear 2857 * B_CACHE if these pages are not valid for the 2858 * range covered by the buffer. 2859 */ 2860 2861 vp = bp->b_vp; 2862 obj = bp->b_bufobj->bo_object; 2863 2864 VM_OBJECT_LOCK(obj); 2865 while (bp->b_npages < desiredpages) { 2866 vm_page_t m; 2867 vm_pindex_t pi; 2868 2869 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2870 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2871 /* 2872 * note: must allocate system pages 2873 * since blocking here could intefere 2874 * with paging I/O, no matter which 2875 * process we are. 2876 */ 2877 m = vm_page_alloc(obj, pi, 2878 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2879 VM_ALLOC_WIRED); 2880 if (m == NULL) { 2881 atomic_add_int(&vm_pageout_deficit, 2882 desiredpages - bp->b_npages); 2883 VM_OBJECT_UNLOCK(obj); 2884 VM_WAIT; 2885 VM_OBJECT_LOCK(obj); 2886 } else { 2887 bp->b_flags &= ~B_CACHE; 2888 bp->b_pages[bp->b_npages] = m; 2889 ++bp->b_npages; 2890 } 2891 continue; 2892 } 2893 2894 /* 2895 * We found a page. If we have to sleep on it, 2896 * retry because it might have gotten freed out 2897 * from under us. 2898 * 2899 * We can only test VPO_BUSY here. Blocking on 2900 * m->busy might lead to a deadlock: 2901 * 2902 * vm_fault->getpages->cluster_read->allocbuf 2903 * 2904 */ 2905 vm_page_lock_queues(); 2906 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2907 continue; 2908 2909 /* 2910 * We have a good page. Should we wakeup the 2911 * page daemon? 2912 */ 2913 if ((curproc != pageproc) && 2914 (VM_PAGE_INQUEUE1(m, PQ_CACHE)) && 2915 ((cnt.v_free_count + cnt.v_cache_count) < 2916 (cnt.v_free_min + cnt.v_cache_min))) { 2917 pagedaemon_wakeup(); 2918 } 2919 vm_page_wire(m); 2920 vm_page_unlock_queues(); 2921 bp->b_pages[bp->b_npages] = m; 2922 ++bp->b_npages; 2923 } 2924 2925 /* 2926 * Step 2. We've loaded the pages into the buffer, 2927 * we have to figure out if we can still have B_CACHE 2928 * set. Note that B_CACHE is set according to the 2929 * byte-granular range ( bcount and size ), new the 2930 * aligned range ( newbsize ). 2931 * 2932 * The VM test is against m->valid, which is DEV_BSIZE 2933 * aligned. Needless to say, the validity of the data 2934 * needs to also be DEV_BSIZE aligned. Note that this 2935 * fails with NFS if the server or some other client 2936 * extends the file's EOF. If our buffer is resized, 2937 * B_CACHE may remain set! XXX 2938 */ 2939 2940 toff = bp->b_bcount; 2941 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2942 2943 while ((bp->b_flags & B_CACHE) && toff < size) { 2944 vm_pindex_t pi; 2945 2946 if (tinc > (size - toff)) 2947 tinc = size - toff; 2948 2949 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2950 PAGE_SHIFT; 2951 2952 vfs_buf_test_cache( 2953 bp, 2954 bp->b_offset, 2955 toff, 2956 tinc, 2957 bp->b_pages[pi] 2958 ); 2959 toff += tinc; 2960 tinc = PAGE_SIZE; 2961 } 2962 VM_OBJECT_UNLOCK(obj); 2963 2964 /* 2965 * Step 3, fixup the KVM pmap. Remember that 2966 * bp->b_data is relative to bp->b_offset, but 2967 * bp->b_offset may be offset into the first page. 2968 */ 2969 2970 bp->b_data = (caddr_t) 2971 trunc_page((vm_offset_t)bp->b_data); 2972 pmap_qenter( 2973 (vm_offset_t)bp->b_data, 2974 bp->b_pages, 2975 bp->b_npages 2976 ); 2977 2978 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2979 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2980 } 2981 } 2982 if (newbsize < bp->b_bufsize) 2983 bufspacewakeup(); 2984 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2985 bp->b_bcount = size; /* requested buffer size */ 2986 return 1; 2987 } 2988 2989 void 2990 biodone(struct bio *bp) 2991 { 2992 void (*done)(struct bio *); 2993 2994 mtx_lock(&bdonelock); 2995 bp->bio_flags |= BIO_DONE; 2996 done = bp->bio_done; 2997 if (done == NULL) 2998 wakeup(bp); 2999 mtx_unlock(&bdonelock); 3000 if (done != NULL) 3001 done(bp); 3002 } 3003 3004 /* 3005 * Wait for a BIO to finish. 3006 * 3007 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3008 * case is not yet clear. 3009 */ 3010 int 3011 biowait(struct bio *bp, const char *wchan) 3012 { 3013 3014 mtx_lock(&bdonelock); 3015 while ((bp->bio_flags & BIO_DONE) == 0) 3016 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3017 mtx_unlock(&bdonelock); 3018 if (bp->bio_error != 0) 3019 return (bp->bio_error); 3020 if (!(bp->bio_flags & BIO_ERROR)) 3021 return (0); 3022 return (EIO); 3023 } 3024 3025 void 3026 biofinish(struct bio *bp, struct devstat *stat, int error) 3027 { 3028 3029 if (error) { 3030 bp->bio_error = error; 3031 bp->bio_flags |= BIO_ERROR; 3032 } 3033 if (stat != NULL) 3034 devstat_end_transaction_bio(stat, bp); 3035 biodone(bp); 3036 } 3037 3038 /* 3039 * bufwait: 3040 * 3041 * Wait for buffer I/O completion, returning error status. The buffer 3042 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3043 * error and cleared. 3044 */ 3045 int 3046 bufwait(struct buf *bp) 3047 { 3048 if (bp->b_iocmd == BIO_READ) 3049 bwait(bp, PRIBIO, "biord"); 3050 else 3051 bwait(bp, PRIBIO, "biowr"); 3052 if (bp->b_flags & B_EINTR) { 3053 bp->b_flags &= ~B_EINTR; 3054 return (EINTR); 3055 } 3056 if (bp->b_ioflags & BIO_ERROR) { 3057 return (bp->b_error ? bp->b_error : EIO); 3058 } else { 3059 return (0); 3060 } 3061 } 3062 3063 /* 3064 * Call back function from struct bio back up to struct buf. 3065 */ 3066 static void 3067 bufdonebio(struct bio *bip) 3068 { 3069 struct buf *bp; 3070 3071 bp = bip->bio_caller2; 3072 bp->b_resid = bp->b_bcount - bip->bio_completed; 3073 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3074 bp->b_ioflags = bip->bio_flags; 3075 bp->b_error = bip->bio_error; 3076 if (bp->b_error) 3077 bp->b_ioflags |= BIO_ERROR; 3078 bufdone(bp); 3079 g_destroy_bio(bip); 3080 } 3081 3082 void 3083 dev_strategy(struct cdev *dev, struct buf *bp) 3084 { 3085 struct cdevsw *csw; 3086 struct bio *bip; 3087 3088 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3089 panic("b_iocmd botch"); 3090 for (;;) { 3091 bip = g_new_bio(); 3092 if (bip != NULL) 3093 break; 3094 /* Try again later */ 3095 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3096 } 3097 bip->bio_cmd = bp->b_iocmd; 3098 bip->bio_offset = bp->b_iooffset; 3099 bip->bio_length = bp->b_bcount; 3100 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3101 bip->bio_data = bp->b_data; 3102 bip->bio_done = bufdonebio; 3103 bip->bio_caller2 = bp; 3104 bip->bio_dev = dev; 3105 KASSERT(dev->si_refcount > 0, 3106 ("dev_strategy on un-referenced struct cdev *(%s)", 3107 devtoname(dev))); 3108 csw = dev_refthread(dev); 3109 if (csw == NULL) { 3110 g_destroy_bio(bip); 3111 bp->b_error = ENXIO; 3112 bp->b_ioflags = BIO_ERROR; 3113 bufdone(bp); 3114 return; 3115 } 3116 (*csw->d_strategy)(bip); 3117 dev_relthread(dev); 3118 } 3119 3120 /* 3121 * bufdone: 3122 * 3123 * Finish I/O on a buffer, optionally calling a completion function. 3124 * This is usually called from an interrupt so process blocking is 3125 * not allowed. 3126 * 3127 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3128 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3129 * assuming B_INVAL is clear. 3130 * 3131 * For the VMIO case, we set B_CACHE if the op was a read and no 3132 * read error occured, or if the op was a write. B_CACHE is never 3133 * set if the buffer is invalid or otherwise uncacheable. 3134 * 3135 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3136 * initiator to leave B_INVAL set to brelse the buffer out of existance 3137 * in the biodone routine. 3138 */ 3139 void 3140 bufdone(struct buf *bp) 3141 { 3142 struct bufobj *dropobj; 3143 void (*biodone)(struct buf *); 3144 3145 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3146 dropobj = NULL; 3147 3148 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3149 BUF_REFCNT(bp))); 3150 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3151 3152 runningbufwakeup(bp); 3153 if (bp->b_iocmd == BIO_WRITE) 3154 dropobj = bp->b_bufobj; 3155 /* call optional completion function if requested */ 3156 if (bp->b_iodone != NULL) { 3157 biodone = bp->b_iodone; 3158 bp->b_iodone = NULL; 3159 (*biodone) (bp); 3160 if (dropobj) 3161 bufobj_wdrop(dropobj); 3162 return; 3163 } 3164 3165 bufdone_finish(bp); 3166 3167 if (dropobj) 3168 bufobj_wdrop(dropobj); 3169 } 3170 3171 void 3172 bufdone_finish(struct buf *bp) 3173 { 3174 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3175 BUF_REFCNT(bp))); 3176 3177 if (LIST_FIRST(&bp->b_dep) != NULL) 3178 buf_complete(bp); 3179 3180 if (bp->b_flags & B_VMIO) { 3181 int i; 3182 vm_ooffset_t foff; 3183 vm_page_t m; 3184 vm_object_t obj; 3185 int iosize; 3186 struct vnode *vp = bp->b_vp; 3187 boolean_t are_queues_locked; 3188 3189 obj = bp->b_bufobj->bo_object; 3190 3191 #if defined(VFS_BIO_DEBUG) 3192 mp_fixme("usecount and vflag accessed without locks."); 3193 if (vp->v_usecount == 0) { 3194 panic("biodone: zero vnode ref count"); 3195 } 3196 3197 KASSERT(vp->v_object != NULL, 3198 ("biodone: vnode %p has no vm_object", vp)); 3199 #endif 3200 3201 foff = bp->b_offset; 3202 KASSERT(bp->b_offset != NOOFFSET, 3203 ("biodone: no buffer offset")); 3204 3205 VM_OBJECT_LOCK(obj); 3206 #if defined(VFS_BIO_DEBUG) 3207 if (obj->paging_in_progress < bp->b_npages) { 3208 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3209 obj->paging_in_progress, bp->b_npages); 3210 } 3211 #endif 3212 3213 /* 3214 * Set B_CACHE if the op was a normal read and no error 3215 * occured. B_CACHE is set for writes in the b*write() 3216 * routines. 3217 */ 3218 iosize = bp->b_bcount - bp->b_resid; 3219 if (bp->b_iocmd == BIO_READ && 3220 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3221 !(bp->b_ioflags & BIO_ERROR)) { 3222 bp->b_flags |= B_CACHE; 3223 } 3224 if (bp->b_iocmd == BIO_READ) { 3225 vm_page_lock_queues(); 3226 are_queues_locked = TRUE; 3227 } else 3228 are_queues_locked = FALSE; 3229 for (i = 0; i < bp->b_npages; i++) { 3230 int bogusflag = 0; 3231 int resid; 3232 3233 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3234 if (resid > iosize) 3235 resid = iosize; 3236 3237 /* 3238 * cleanup bogus pages, restoring the originals 3239 */ 3240 m = bp->b_pages[i]; 3241 if (m == bogus_page) { 3242 bogusflag = 1; 3243 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3244 if (m == NULL) 3245 panic("biodone: page disappeared!"); 3246 bp->b_pages[i] = m; 3247 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3248 bp->b_pages, bp->b_npages); 3249 } 3250 #if defined(VFS_BIO_DEBUG) 3251 if (OFF_TO_IDX(foff) != m->pindex) { 3252 printf( 3253 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3254 (intmax_t)foff, (uintmax_t)m->pindex); 3255 } 3256 #endif 3257 3258 /* 3259 * In the write case, the valid and clean bits are 3260 * already changed correctly ( see bdwrite() ), so we 3261 * only need to do this here in the read case. 3262 */ 3263 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3264 vfs_page_set_valid(bp, foff, i, m); 3265 } 3266 3267 /* 3268 * when debugging new filesystems or buffer I/O methods, this 3269 * is the most common error that pops up. if you see this, you 3270 * have not set the page busy flag correctly!!! 3271 */ 3272 if (m->busy == 0) { 3273 printf("biodone: page busy < 0, " 3274 "pindex: %d, foff: 0x(%x,%x), " 3275 "resid: %d, index: %d\n", 3276 (int) m->pindex, (int)(foff >> 32), 3277 (int) foff & 0xffffffff, resid, i); 3278 if (!vn_isdisk(vp, NULL)) 3279 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3280 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3281 (intmax_t) bp->b_lblkno, 3282 bp->b_flags, bp->b_npages); 3283 else 3284 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3285 (intmax_t) bp->b_lblkno, 3286 bp->b_flags, bp->b_npages); 3287 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3288 (u_long)m->valid, (u_long)m->dirty, 3289 m->wire_count); 3290 panic("biodone: page busy < 0\n"); 3291 } 3292 vm_page_io_finish(m); 3293 vm_object_pip_subtract(obj, 1); 3294 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3295 iosize -= resid; 3296 } 3297 if (are_queues_locked) 3298 vm_page_unlock_queues(); 3299 vm_object_pip_wakeupn(obj, 0); 3300 VM_OBJECT_UNLOCK(obj); 3301 } 3302 3303 /* 3304 * For asynchronous completions, release the buffer now. The brelse 3305 * will do a wakeup there if necessary - so no need to do a wakeup 3306 * here in the async case. The sync case always needs to do a wakeup. 3307 */ 3308 3309 if (bp->b_flags & B_ASYNC) { 3310 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3311 brelse(bp); 3312 else 3313 bqrelse(bp); 3314 } else 3315 bdone(bp); 3316 } 3317 3318 /* 3319 * This routine is called in lieu of iodone in the case of 3320 * incomplete I/O. This keeps the busy status for pages 3321 * consistant. 3322 */ 3323 void 3324 vfs_unbusy_pages(struct buf *bp) 3325 { 3326 int i; 3327 vm_object_t obj; 3328 vm_page_t m; 3329 3330 runningbufwakeup(bp); 3331 if (!(bp->b_flags & B_VMIO)) 3332 return; 3333 3334 obj = bp->b_bufobj->bo_object; 3335 VM_OBJECT_LOCK(obj); 3336 for (i = 0; i < bp->b_npages; i++) { 3337 m = bp->b_pages[i]; 3338 if (m == bogus_page) { 3339 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3340 if (!m) 3341 panic("vfs_unbusy_pages: page missing\n"); 3342 bp->b_pages[i] = m; 3343 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3344 bp->b_pages, bp->b_npages); 3345 } 3346 vm_object_pip_subtract(obj, 1); 3347 vm_page_io_finish(m); 3348 } 3349 vm_object_pip_wakeupn(obj, 0); 3350 VM_OBJECT_UNLOCK(obj); 3351 } 3352 3353 /* 3354 * vfs_page_set_valid: 3355 * 3356 * Set the valid bits in a page based on the supplied offset. The 3357 * range is restricted to the buffer's size. 3358 * 3359 * This routine is typically called after a read completes. 3360 */ 3361 static void 3362 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3363 { 3364 vm_ooffset_t soff, eoff; 3365 3366 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3367 /* 3368 * Start and end offsets in buffer. eoff - soff may not cross a 3369 * page boundry or cross the end of the buffer. The end of the 3370 * buffer, in this case, is our file EOF, not the allocation size 3371 * of the buffer. 3372 */ 3373 soff = off; 3374 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3375 if (eoff > bp->b_offset + bp->b_bcount) 3376 eoff = bp->b_offset + bp->b_bcount; 3377 3378 /* 3379 * Set valid range. This is typically the entire buffer and thus the 3380 * entire page. 3381 */ 3382 if (eoff > soff) { 3383 vm_page_set_validclean( 3384 m, 3385 (vm_offset_t) (soff & PAGE_MASK), 3386 (vm_offset_t) (eoff - soff) 3387 ); 3388 } 3389 } 3390 3391 /* 3392 * This routine is called before a device strategy routine. 3393 * It is used to tell the VM system that paging I/O is in 3394 * progress, and treat the pages associated with the buffer 3395 * almost as being VPO_BUSY. Also the object paging_in_progress 3396 * flag is handled to make sure that the object doesn't become 3397 * inconsistant. 3398 * 3399 * Since I/O has not been initiated yet, certain buffer flags 3400 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3401 * and should be ignored. 3402 */ 3403 void 3404 vfs_busy_pages(struct buf *bp, int clear_modify) 3405 { 3406 int i, bogus; 3407 vm_object_t obj; 3408 vm_ooffset_t foff; 3409 vm_page_t m; 3410 3411 if (!(bp->b_flags & B_VMIO)) 3412 return; 3413 3414 obj = bp->b_bufobj->bo_object; 3415 foff = bp->b_offset; 3416 KASSERT(bp->b_offset != NOOFFSET, 3417 ("vfs_busy_pages: no buffer offset")); 3418 VM_OBJECT_LOCK(obj); 3419 if (bp->b_bufsize != 0) 3420 vfs_setdirty_locked_object(bp); 3421 retry: 3422 for (i = 0; i < bp->b_npages; i++) { 3423 m = bp->b_pages[i]; 3424 3425 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3426 goto retry; 3427 } 3428 bogus = 0; 3429 vm_page_lock_queues(); 3430 for (i = 0; i < bp->b_npages; i++) { 3431 m = bp->b_pages[i]; 3432 3433 if ((bp->b_flags & B_CLUSTER) == 0) { 3434 vm_object_pip_add(obj, 1); 3435 vm_page_io_start(m); 3436 } 3437 /* 3438 * When readying a buffer for a read ( i.e 3439 * clear_modify == 0 ), it is important to do 3440 * bogus_page replacement for valid pages in 3441 * partially instantiated buffers. Partially 3442 * instantiated buffers can, in turn, occur when 3443 * reconstituting a buffer from its VM backing store 3444 * base. We only have to do this if B_CACHE is 3445 * clear ( which causes the I/O to occur in the 3446 * first place ). The replacement prevents the read 3447 * I/O from overwriting potentially dirty VM-backed 3448 * pages. XXX bogus page replacement is, uh, bogus. 3449 * It may not work properly with small-block devices. 3450 * We need to find a better way. 3451 */ 3452 pmap_remove_all(m); 3453 if (clear_modify) 3454 vfs_page_set_valid(bp, foff, i, m); 3455 else if (m->valid == VM_PAGE_BITS_ALL && 3456 (bp->b_flags & B_CACHE) == 0) { 3457 bp->b_pages[i] = bogus_page; 3458 bogus++; 3459 } 3460 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3461 } 3462 vm_page_unlock_queues(); 3463 VM_OBJECT_UNLOCK(obj); 3464 if (bogus) 3465 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3466 bp->b_pages, bp->b_npages); 3467 } 3468 3469 /* 3470 * Tell the VM system that the pages associated with this buffer 3471 * are clean. This is used for delayed writes where the data is 3472 * going to go to disk eventually without additional VM intevention. 3473 * 3474 * Note that while we only really need to clean through to b_bcount, we 3475 * just go ahead and clean through to b_bufsize. 3476 */ 3477 static void 3478 vfs_clean_pages(struct buf *bp) 3479 { 3480 int i; 3481 vm_ooffset_t foff, noff, eoff; 3482 vm_page_t m; 3483 3484 if (!(bp->b_flags & B_VMIO)) 3485 return; 3486 3487 foff = bp->b_offset; 3488 KASSERT(bp->b_offset != NOOFFSET, 3489 ("vfs_clean_pages: no buffer offset")); 3490 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3491 vm_page_lock_queues(); 3492 for (i = 0; i < bp->b_npages; i++) { 3493 m = bp->b_pages[i]; 3494 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3495 eoff = noff; 3496 3497 if (eoff > bp->b_offset + bp->b_bufsize) 3498 eoff = bp->b_offset + bp->b_bufsize; 3499 vfs_page_set_valid(bp, foff, i, m); 3500 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3501 foff = noff; 3502 } 3503 vm_page_unlock_queues(); 3504 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3505 } 3506 3507 /* 3508 * vfs_bio_set_validclean: 3509 * 3510 * Set the range within the buffer to valid and clean. The range is 3511 * relative to the beginning of the buffer, b_offset. Note that b_offset 3512 * itself may be offset from the beginning of the first page. 3513 * 3514 */ 3515 3516 void 3517 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3518 { 3519 int i, n; 3520 vm_page_t m; 3521 3522 if (!(bp->b_flags & B_VMIO)) 3523 return; 3524 /* 3525 * Fixup base to be relative to beginning of first page. 3526 * Set initial n to be the maximum number of bytes in the 3527 * first page that can be validated. 3528 */ 3529 3530 base += (bp->b_offset & PAGE_MASK); 3531 n = PAGE_SIZE - (base & PAGE_MASK); 3532 3533 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3534 vm_page_lock_queues(); 3535 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3536 m = bp->b_pages[i]; 3537 if (n > size) 3538 n = size; 3539 vm_page_set_validclean(m, base & PAGE_MASK, n); 3540 base += n; 3541 size -= n; 3542 n = PAGE_SIZE; 3543 } 3544 vm_page_unlock_queues(); 3545 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3546 } 3547 3548 /* 3549 * vfs_bio_clrbuf: 3550 * 3551 * clear a buffer. This routine essentially fakes an I/O, so we need 3552 * to clear BIO_ERROR and B_INVAL. 3553 * 3554 * Note that while we only theoretically need to clear through b_bcount, 3555 * we go ahead and clear through b_bufsize. 3556 */ 3557 3558 void 3559 vfs_bio_clrbuf(struct buf *bp) 3560 { 3561 int i, j, mask = 0; 3562 caddr_t sa, ea; 3563 3564 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3565 clrbuf(bp); 3566 return; 3567 } 3568 3569 bp->b_flags &= ~B_INVAL; 3570 bp->b_ioflags &= ~BIO_ERROR; 3571 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3572 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3573 (bp->b_offset & PAGE_MASK) == 0) { 3574 if (bp->b_pages[0] == bogus_page) 3575 goto unlock; 3576 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3577 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3578 if ((bp->b_pages[0]->valid & mask) == mask) 3579 goto unlock; 3580 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3581 ((bp->b_pages[0]->valid & mask) == 0)) { 3582 bzero(bp->b_data, bp->b_bufsize); 3583 bp->b_pages[0]->valid |= mask; 3584 goto unlock; 3585 } 3586 } 3587 ea = sa = bp->b_data; 3588 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3589 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3590 ea = (caddr_t)(vm_offset_t)ulmin( 3591 (u_long)(vm_offset_t)ea, 3592 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3593 if (bp->b_pages[i] == bogus_page) 3594 continue; 3595 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3596 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3597 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3598 if ((bp->b_pages[i]->valid & mask) == mask) 3599 continue; 3600 if ((bp->b_pages[i]->valid & mask) == 0) { 3601 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3602 bzero(sa, ea - sa); 3603 } else { 3604 for (; sa < ea; sa += DEV_BSIZE, j++) { 3605 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3606 (bp->b_pages[i]->valid & (1 << j)) == 0) 3607 bzero(sa, DEV_BSIZE); 3608 } 3609 } 3610 bp->b_pages[i]->valid |= mask; 3611 } 3612 unlock: 3613 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3614 bp->b_resid = 0; 3615 } 3616 3617 /* 3618 * vm_hold_load_pages and vm_hold_free_pages get pages into 3619 * a buffers address space. The pages are anonymous and are 3620 * not associated with a file object. 3621 */ 3622 static void 3623 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3624 { 3625 vm_offset_t pg; 3626 vm_page_t p; 3627 int index; 3628 3629 to = round_page(to); 3630 from = round_page(from); 3631 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3632 3633 VM_OBJECT_LOCK(kernel_object); 3634 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3635 tryagain: 3636 /* 3637 * note: must allocate system pages since blocking here 3638 * could intefere with paging I/O, no matter which 3639 * process we are. 3640 */ 3641 p = vm_page_alloc(kernel_object, 3642 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3643 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3644 if (!p) { 3645 atomic_add_int(&vm_pageout_deficit, 3646 (to - pg) >> PAGE_SHIFT); 3647 VM_OBJECT_UNLOCK(kernel_object); 3648 VM_WAIT; 3649 VM_OBJECT_LOCK(kernel_object); 3650 goto tryagain; 3651 } 3652 p->valid = VM_PAGE_BITS_ALL; 3653 pmap_qenter(pg, &p, 1); 3654 bp->b_pages[index] = p; 3655 } 3656 VM_OBJECT_UNLOCK(kernel_object); 3657 bp->b_npages = index; 3658 } 3659 3660 /* Return pages associated with this buf to the vm system */ 3661 static void 3662 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3663 { 3664 vm_offset_t pg; 3665 vm_page_t p; 3666 int index, newnpages; 3667 3668 from = round_page(from); 3669 to = round_page(to); 3670 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3671 3672 VM_OBJECT_LOCK(kernel_object); 3673 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3674 p = bp->b_pages[index]; 3675 if (p && (index < bp->b_npages)) { 3676 if (p->busy) { 3677 printf( 3678 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3679 (intmax_t)bp->b_blkno, 3680 (intmax_t)bp->b_lblkno); 3681 } 3682 bp->b_pages[index] = NULL; 3683 pmap_qremove(pg, 1); 3684 vm_page_lock_queues(); 3685 vm_page_unwire(p, 0); 3686 vm_page_free(p); 3687 vm_page_unlock_queues(); 3688 } 3689 } 3690 VM_OBJECT_UNLOCK(kernel_object); 3691 bp->b_npages = newnpages; 3692 } 3693 3694 /* 3695 * Map an IO request into kernel virtual address space. 3696 * 3697 * All requests are (re)mapped into kernel VA space. 3698 * Notice that we use b_bufsize for the size of the buffer 3699 * to be mapped. b_bcount might be modified by the driver. 3700 * 3701 * Note that even if the caller determines that the address space should 3702 * be valid, a race or a smaller-file mapped into a larger space may 3703 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3704 * check the return value. 3705 */ 3706 int 3707 vmapbuf(struct buf *bp) 3708 { 3709 caddr_t addr, kva; 3710 vm_prot_t prot; 3711 int pidx, i; 3712 struct vm_page *m; 3713 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3714 3715 if (bp->b_bufsize < 0) 3716 return (-1); 3717 prot = VM_PROT_READ; 3718 if (bp->b_iocmd == BIO_READ) 3719 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3720 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3721 addr < bp->b_data + bp->b_bufsize; 3722 addr += PAGE_SIZE, pidx++) { 3723 /* 3724 * Do the vm_fault if needed; do the copy-on-write thing 3725 * when reading stuff off device into memory. 3726 * 3727 * NOTE! Must use pmap_extract() because addr may be in 3728 * the userland address space, and kextract is only guarenteed 3729 * to work for the kernland address space (see: sparc64 port). 3730 */ 3731 retry: 3732 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3733 prot) < 0) { 3734 vm_page_lock_queues(); 3735 for (i = 0; i < pidx; ++i) { 3736 vm_page_unhold(bp->b_pages[i]); 3737 bp->b_pages[i] = NULL; 3738 } 3739 vm_page_unlock_queues(); 3740 return(-1); 3741 } 3742 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3743 if (m == NULL) 3744 goto retry; 3745 bp->b_pages[pidx] = m; 3746 } 3747 if (pidx > btoc(MAXPHYS)) 3748 panic("vmapbuf: mapped more than MAXPHYS"); 3749 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3750 3751 kva = bp->b_saveaddr; 3752 bp->b_npages = pidx; 3753 bp->b_saveaddr = bp->b_data; 3754 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3755 return(0); 3756 } 3757 3758 /* 3759 * Free the io map PTEs associated with this IO operation. 3760 * We also invalidate the TLB entries and restore the original b_addr. 3761 */ 3762 void 3763 vunmapbuf(struct buf *bp) 3764 { 3765 int pidx; 3766 int npages; 3767 3768 npages = bp->b_npages; 3769 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3770 vm_page_lock_queues(); 3771 for (pidx = 0; pidx < npages; pidx++) 3772 vm_page_unhold(bp->b_pages[pidx]); 3773 vm_page_unlock_queues(); 3774 3775 bp->b_data = bp->b_saveaddr; 3776 } 3777 3778 void 3779 bdone(struct buf *bp) 3780 { 3781 3782 mtx_lock(&bdonelock); 3783 bp->b_flags |= B_DONE; 3784 wakeup(bp); 3785 mtx_unlock(&bdonelock); 3786 } 3787 3788 void 3789 bwait(struct buf *bp, u_char pri, const char *wchan) 3790 { 3791 3792 mtx_lock(&bdonelock); 3793 while ((bp->b_flags & B_DONE) == 0) 3794 msleep(bp, &bdonelock, pri, wchan, 0); 3795 mtx_unlock(&bdonelock); 3796 } 3797 3798 int 3799 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3800 { 3801 3802 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3803 } 3804 3805 void 3806 bufstrategy(struct bufobj *bo, struct buf *bp) 3807 { 3808 int i = 0; 3809 struct vnode *vp; 3810 3811 vp = bp->b_vp; 3812 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3813 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3814 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3815 i = VOP_STRATEGY(vp, bp); 3816 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3817 } 3818 3819 void 3820 bufobj_wrefl(struct bufobj *bo) 3821 { 3822 3823 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3824 ASSERT_BO_LOCKED(bo); 3825 bo->bo_numoutput++; 3826 } 3827 3828 void 3829 bufobj_wref(struct bufobj *bo) 3830 { 3831 3832 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3833 BO_LOCK(bo); 3834 bo->bo_numoutput++; 3835 BO_UNLOCK(bo); 3836 } 3837 3838 void 3839 bufobj_wdrop(struct bufobj *bo) 3840 { 3841 3842 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3843 BO_LOCK(bo); 3844 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3845 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3846 bo->bo_flag &= ~BO_WWAIT; 3847 wakeup(&bo->bo_numoutput); 3848 } 3849 BO_UNLOCK(bo); 3850 } 3851 3852 int 3853 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3854 { 3855 int error; 3856 3857 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3858 ASSERT_BO_LOCKED(bo); 3859 error = 0; 3860 while (bo->bo_numoutput) { 3861 bo->bo_flag |= BO_WWAIT; 3862 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3863 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3864 if (error) 3865 break; 3866 } 3867 return (error); 3868 } 3869 3870 void 3871 bpin(struct buf *bp) 3872 { 3873 mtx_lock(&bpinlock); 3874 bp->b_pin_count++; 3875 mtx_unlock(&bpinlock); 3876 } 3877 3878 void 3879 bunpin(struct buf *bp) 3880 { 3881 mtx_lock(&bpinlock); 3882 if (--bp->b_pin_count == 0) 3883 wakeup(bp); 3884 mtx_unlock(&bpinlock); 3885 } 3886 3887 void 3888 bunpin_wait(struct buf *bp) 3889 { 3890 mtx_lock(&bpinlock); 3891 while (bp->b_pin_count > 0) 3892 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3893 mtx_unlock(&bpinlock); 3894 } 3895 3896 #include "opt_ddb.h" 3897 #ifdef DDB 3898 #include <ddb/ddb.h> 3899 3900 /* DDB command to show buffer data */ 3901 DB_SHOW_COMMAND(buffer, db_show_buffer) 3902 { 3903 /* get args */ 3904 struct buf *bp = (struct buf *)addr; 3905 3906 if (!have_addr) { 3907 db_printf("usage: show buffer <addr>\n"); 3908 return; 3909 } 3910 3911 db_printf("buf at %p\n", bp); 3912 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3913 db_printf( 3914 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3915 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3916 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3917 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3918 if (bp->b_npages) { 3919 int i; 3920 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3921 for (i = 0; i < bp->b_npages; i++) { 3922 vm_page_t m; 3923 m = bp->b_pages[i]; 3924 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3925 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3926 if ((i + 1) < bp->b_npages) 3927 db_printf(","); 3928 } 3929 db_printf("\n"); 3930 } 3931 lockmgr_printinfo(&bp->b_lock); 3932 } 3933 3934 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3935 { 3936 struct buf *bp; 3937 int i; 3938 3939 for (i = 0; i < nbuf; i++) { 3940 bp = &buf[i]; 3941 if (lockcount(&bp->b_lock)) { 3942 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3943 db_printf("\n"); 3944 } 3945 } 3946 } 3947 #endif /* DDB */ 3948