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 .bop_bdflush = bufbdflush, 84 }; 85 86 /* 87 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 88 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 89 */ 90 struct buf *buf; /* buffer header pool */ 91 92 static struct proc *bufdaemonproc; 93 94 static int inmem(struct vnode *vp, daddr_t blkno); 95 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 96 vm_offset_t to); 97 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 98 vm_offset_t to); 99 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 100 int pageno, vm_page_t m); 101 static void vfs_clean_pages(struct buf *bp); 102 static void vfs_setdirty(struct buf *bp); 103 static void vfs_setdirty_locked_object(struct buf *bp); 104 static void vfs_vmio_release(struct buf *bp); 105 static int vfs_bio_clcheck(struct vnode *vp, int size, 106 daddr_t lblkno, daddr_t blkno); 107 static int flushbufqueues(int, int); 108 static void buf_daemon(void); 109 static void bremfreel(struct buf *bp); 110 111 int vmiodirenable = TRUE; 112 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 113 "Use the VM system for directory writes"); 114 int runningbufspace; 115 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 116 "Amount of presently outstanding async buffer io"); 117 static int bufspace; 118 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 119 "KVA memory used for bufs"); 120 static int maxbufspace; 121 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 122 "Maximum allowed value of bufspace (including buf_daemon)"); 123 static int bufmallocspace; 124 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 125 "Amount of malloced memory for buffers"); 126 static int maxbufmallocspace; 127 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 128 "Maximum amount of malloced memory for buffers"); 129 static int lobufspace; 130 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 131 "Minimum amount of buffers we want to have"); 132 int hibufspace; 133 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 134 "Maximum allowed value of bufspace (excluding buf_daemon)"); 135 static int bufreusecnt; 136 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 137 "Number of times we have reused a buffer"); 138 static int buffreekvacnt; 139 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 140 "Number of times we have freed the KVA space from some buffer"); 141 static int bufdefragcnt; 142 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 143 "Number of times we have had to repeat buffer allocation to defragment"); 144 static int lorunningspace; 145 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 146 "Minimum preferred space used for in-progress I/O"); 147 static int hirunningspace; 148 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 149 "Maximum amount of space to use for in-progress I/O"); 150 int dirtybufferflushes; 151 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 152 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 153 int bdwriteskip; 154 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 155 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 156 int altbufferflushes; 157 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 158 0, "Number of fsync flushes to limit dirty buffers"); 159 static int recursiveflushes; 160 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 161 0, "Number of flushes skipped due to being recursive"); 162 static int numdirtybuffers; 163 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 164 "Number of buffers that are dirty (has unwritten changes) at the moment"); 165 static int lodirtybuffers; 166 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 167 "How many buffers we want to have free before bufdaemon can sleep"); 168 static int hidirtybuffers; 169 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 170 "When the number of dirty buffers is considered severe"); 171 int dirtybufthresh; 172 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 173 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 174 static int numfreebuffers; 175 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 176 "Number of free buffers"); 177 static int lofreebuffers; 178 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 179 "XXX Unused"); 180 static int hifreebuffers; 181 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 182 "XXX Complicatedly unused"); 183 static int getnewbufcalls; 184 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 185 "Number of calls to getnewbuf"); 186 static int getnewbufrestarts; 187 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 188 "Number of times getnewbuf has had to restart a buffer aquisition"); 189 190 /* 191 * Wakeup point for bufdaemon, as well as indicator of whether it is already 192 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 193 * is idling. 194 */ 195 static int bd_request; 196 197 /* 198 * This lock synchronizes access to bd_request. 199 */ 200 static struct mtx bdlock; 201 202 /* 203 * bogus page -- for I/O to/from partially complete buffers 204 * this is a temporary solution to the problem, but it is not 205 * really that bad. it would be better to split the buffer 206 * for input in the case of buffers partially already in memory, 207 * but the code is intricate enough already. 208 */ 209 vm_page_t bogus_page; 210 211 /* 212 * Synchronization (sleep/wakeup) variable for active buffer space requests. 213 * Set when wait starts, cleared prior to wakeup(). 214 * Used in runningbufwakeup() and waitrunningbufspace(). 215 */ 216 static int runningbufreq; 217 218 /* 219 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 220 * waitrunningbufspace(). 221 */ 222 static struct mtx rbreqlock; 223 224 /* 225 * Synchronization (sleep/wakeup) variable for buffer requests. 226 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 227 * by and/or. 228 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 229 * getnewbuf(), and getblk(). 230 */ 231 static int needsbuffer; 232 233 /* 234 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 235 */ 236 static struct mtx nblock; 237 238 /* 239 * Lock that protects against bwait()/bdone()/B_DONE races. 240 */ 241 242 static struct mtx bdonelock; 243 244 /* 245 * Lock that protects against bwait()/bdone()/B_DONE races. 246 */ 247 static struct mtx bpinlock; 248 249 /* 250 * Definitions for the buffer free lists. 251 */ 252 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 253 254 #define QUEUE_NONE 0 /* on no queue */ 255 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 256 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 257 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 258 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 259 #define QUEUE_EMPTY 5 /* empty buffer headers */ 260 261 /* Queues for free buffers with various properties */ 262 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 263 264 /* Lock for the bufqueues */ 265 static struct mtx bqlock; 266 267 /* 268 * Single global constant for BUF_WMESG, to avoid getting multiple references. 269 * buf_wmesg is referred from macros. 270 */ 271 const char *buf_wmesg = BUF_WMESG; 272 273 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 274 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 275 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 276 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 277 278 #ifdef DIRECTIO 279 extern void ffs_rawread_setup(void); 280 #endif /* DIRECTIO */ 281 /* 282 * numdirtywakeup: 283 * 284 * If someone is blocked due to there being too many dirty buffers, 285 * and numdirtybuffers is now reasonable, wake them up. 286 */ 287 288 static __inline void 289 numdirtywakeup(int level) 290 { 291 292 if (numdirtybuffers <= level) { 293 mtx_lock(&nblock); 294 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 295 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 296 wakeup(&needsbuffer); 297 } 298 mtx_unlock(&nblock); 299 } 300 } 301 302 /* 303 * bufspacewakeup: 304 * 305 * Called when buffer space is potentially available for recovery. 306 * getnewbuf() will block on this flag when it is unable to free 307 * sufficient buffer space. Buffer space becomes recoverable when 308 * bp's get placed back in the queues. 309 */ 310 311 static __inline void 312 bufspacewakeup(void) 313 { 314 315 /* 316 * If someone is waiting for BUF space, wake them up. Even 317 * though we haven't freed the kva space yet, the waiting 318 * process will be able to now. 319 */ 320 mtx_lock(&nblock); 321 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 322 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 323 wakeup(&needsbuffer); 324 } 325 mtx_unlock(&nblock); 326 } 327 328 /* 329 * runningbufwakeup() - in-progress I/O accounting. 330 * 331 */ 332 void 333 runningbufwakeup(struct buf *bp) 334 { 335 336 if (bp->b_runningbufspace) { 337 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 338 bp->b_runningbufspace = 0; 339 mtx_lock(&rbreqlock); 340 if (runningbufreq && runningbufspace <= lorunningspace) { 341 runningbufreq = 0; 342 wakeup(&runningbufreq); 343 } 344 mtx_unlock(&rbreqlock); 345 } 346 } 347 348 /* 349 * bufcountwakeup: 350 * 351 * Called when a buffer has been added to one of the free queues to 352 * account for the buffer and to wakeup anyone waiting for free buffers. 353 * This typically occurs when large amounts of metadata are being handled 354 * by the buffer cache ( else buffer space runs out first, usually ). 355 */ 356 357 static __inline void 358 bufcountwakeup(void) 359 { 360 361 atomic_add_int(&numfreebuffers, 1); 362 mtx_lock(&nblock); 363 if (needsbuffer) { 364 needsbuffer &= ~VFS_BIO_NEED_ANY; 365 if (numfreebuffers >= hifreebuffers) 366 needsbuffer &= ~VFS_BIO_NEED_FREE; 367 wakeup(&needsbuffer); 368 } 369 mtx_unlock(&nblock); 370 } 371 372 /* 373 * waitrunningbufspace() 374 * 375 * runningbufspace is a measure of the amount of I/O currently 376 * running. This routine is used in async-write situations to 377 * prevent creating huge backups of pending writes to a device. 378 * Only asynchronous writes are governed by this function. 379 * 380 * Reads will adjust runningbufspace, but will not block based on it. 381 * The read load has a side effect of reducing the allowed write load. 382 * 383 * This does NOT turn an async write into a sync write. It waits 384 * for earlier writes to complete and generally returns before the 385 * caller's write has reached the device. 386 */ 387 void 388 waitrunningbufspace(void) 389 { 390 391 mtx_lock(&rbreqlock); 392 while (runningbufspace > hirunningspace) { 393 ++runningbufreq; 394 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 395 } 396 mtx_unlock(&rbreqlock); 397 } 398 399 400 /* 401 * vfs_buf_test_cache: 402 * 403 * Called when a buffer is extended. This function clears the B_CACHE 404 * bit if the newly extended portion of the buffer does not contain 405 * valid data. 406 */ 407 static __inline 408 void 409 vfs_buf_test_cache(struct buf *bp, 410 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 411 vm_page_t m) 412 { 413 414 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 415 if (bp->b_flags & B_CACHE) { 416 int base = (foff + off) & PAGE_MASK; 417 if (vm_page_is_valid(m, base, size) == 0) 418 bp->b_flags &= ~B_CACHE; 419 } 420 } 421 422 /* Wake up the buffer deamon if necessary */ 423 static __inline 424 void 425 bd_wakeup(int dirtybuflevel) 426 { 427 428 mtx_lock(&bdlock); 429 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 430 bd_request = 1; 431 wakeup(&bd_request); 432 } 433 mtx_unlock(&bdlock); 434 } 435 436 /* 437 * bd_speedup - speedup the buffer cache flushing code 438 */ 439 440 static __inline 441 void 442 bd_speedup(void) 443 { 444 445 bd_wakeup(1); 446 } 447 448 /* 449 * Calculating buffer cache scaling values and reserve space for buffer 450 * headers. This is called during low level kernel initialization and 451 * may be called more then once. We CANNOT write to the memory area 452 * being reserved at this time. 453 */ 454 caddr_t 455 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 456 { 457 458 /* 459 * physmem_est is in pages. Convert it to kilobytes (assumes 460 * PAGE_SIZE is >= 1K) 461 */ 462 physmem_est = physmem_est * (PAGE_SIZE / 1024); 463 464 /* 465 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 466 * For the first 64MB of ram nominally allocate sufficient buffers to 467 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 468 * buffers to cover 1/20 of our ram over 64MB. When auto-sizing 469 * the buffer cache we limit the eventual kva reservation to 470 * maxbcache bytes. 471 * 472 * factor represents the 1/4 x ram conversion. 473 */ 474 if (nbuf == 0) { 475 int factor = 4 * BKVASIZE / 1024; 476 477 nbuf = 50; 478 if (physmem_est > 4096) 479 nbuf += min((physmem_est - 4096) / factor, 480 65536 / factor); 481 if (physmem_est > 65536) 482 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 483 484 if (maxbcache && nbuf > maxbcache / BKVASIZE) 485 nbuf = maxbcache / BKVASIZE; 486 } 487 488 #if 0 489 /* 490 * Do not allow the buffer_map to be more then 1/2 the size of the 491 * kernel_map. 492 */ 493 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 494 (BKVASIZE * 2)) { 495 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 496 (BKVASIZE * 2); 497 printf("Warning: nbufs capped at %d\n", nbuf); 498 } 499 #endif 500 501 /* 502 * swbufs are used as temporary holders for I/O, such as paging I/O. 503 * We have no less then 16 and no more then 256. 504 */ 505 nswbuf = max(min(nbuf/4, 256), 16); 506 #ifdef NSWBUF_MIN 507 if (nswbuf < NSWBUF_MIN) 508 nswbuf = NSWBUF_MIN; 509 #endif 510 #ifdef DIRECTIO 511 ffs_rawread_setup(); 512 #endif 513 514 /* 515 * Reserve space for the buffer cache buffers 516 */ 517 swbuf = (void *)v; 518 v = (caddr_t)(swbuf + nswbuf); 519 buf = (void *)v; 520 v = (caddr_t)(buf + nbuf); 521 522 return(v); 523 } 524 525 /* Initialize the buffer subsystem. Called before use of any buffers. */ 526 void 527 bufinit(void) 528 { 529 struct buf *bp; 530 int i; 531 532 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 533 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 534 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 535 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 536 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 537 mtx_init(&bpinlock, "bpin lock", NULL, MTX_DEF); 538 539 /* next, make a null set of free lists */ 540 for (i = 0; i < BUFFER_QUEUES; i++) 541 TAILQ_INIT(&bufqueues[i]); 542 543 /* finally, initialize each buffer header and stick on empty q */ 544 for (i = 0; i < nbuf; i++) { 545 bp = &buf[i]; 546 bzero(bp, sizeof *bp); 547 bp->b_flags = B_INVAL; /* we're just an empty header */ 548 bp->b_rcred = NOCRED; 549 bp->b_wcred = NOCRED; 550 bp->b_qindex = QUEUE_EMPTY; 551 bp->b_vflags = 0; 552 bp->b_xflags = 0; 553 LIST_INIT(&bp->b_dep); 554 BUF_LOCKINIT(bp); 555 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 556 } 557 558 /* 559 * maxbufspace is the absolute maximum amount of buffer space we are 560 * allowed to reserve in KVM and in real terms. The absolute maximum 561 * is nominally used by buf_daemon. hibufspace is the nominal maximum 562 * used by most other processes. The differential is required to 563 * ensure that buf_daemon is able to run when other processes might 564 * be blocked waiting for buffer space. 565 * 566 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 567 * this may result in KVM fragmentation which is not handled optimally 568 * by the system. 569 */ 570 maxbufspace = nbuf * BKVASIZE; 571 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 572 lobufspace = hibufspace - MAXBSIZE; 573 574 lorunningspace = 512 * 1024; 575 hirunningspace = 1024 * 1024; 576 577 /* 578 * Limit the amount of malloc memory since it is wired permanently into 579 * the kernel space. Even though this is accounted for in the buffer 580 * allocation, we don't want the malloced region to grow uncontrolled. 581 * The malloc scheme improves memory utilization significantly on average 582 * (small) directories. 583 */ 584 maxbufmallocspace = hibufspace / 20; 585 586 /* 587 * Reduce the chance of a deadlock occuring by limiting the number 588 * of delayed-write dirty buffers we allow to stack up. 589 */ 590 hidirtybuffers = nbuf / 4 + 20; 591 dirtybufthresh = hidirtybuffers * 9 / 10; 592 numdirtybuffers = 0; 593 /* 594 * To support extreme low-memory systems, make sure hidirtybuffers cannot 595 * eat up all available buffer space. This occurs when our minimum cannot 596 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 597 * BKVASIZE'd (8K) buffers. 598 */ 599 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 600 hidirtybuffers >>= 1; 601 } 602 lodirtybuffers = hidirtybuffers / 2; 603 604 /* 605 * Try to keep the number of free buffers in the specified range, 606 * and give special processes (e.g. like buf_daemon) access to an 607 * emergency reserve. 608 */ 609 lofreebuffers = nbuf / 18 + 5; 610 hifreebuffers = 2 * lofreebuffers; 611 numfreebuffers = nbuf; 612 613 /* 614 * Maximum number of async ops initiated per buf_daemon loop. This is 615 * somewhat of a hack at the moment, we really need to limit ourselves 616 * based on the number of bytes of I/O in-transit that were initiated 617 * from buf_daemon. 618 */ 619 620 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 621 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 622 } 623 624 /* 625 * bfreekva() - free the kva allocation for a buffer. 626 * 627 * Since this call frees up buffer space, we call bufspacewakeup(). 628 */ 629 static void 630 bfreekva(struct buf *bp) 631 { 632 633 if (bp->b_kvasize) { 634 atomic_add_int(&buffreekvacnt, 1); 635 atomic_subtract_int(&bufspace, bp->b_kvasize); 636 vm_map_lock(buffer_map); 637 vm_map_delete(buffer_map, 638 (vm_offset_t) bp->b_kvabase, 639 (vm_offset_t) bp->b_kvabase + bp->b_kvasize 640 ); 641 vm_map_unlock(buffer_map); 642 bp->b_kvasize = 0; 643 bufspacewakeup(); 644 } 645 } 646 647 /* 648 * bremfree: 649 * 650 * Mark the buffer for removal from the appropriate free list in brelse. 651 * 652 */ 653 void 654 bremfree(struct buf *bp) 655 { 656 657 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 658 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked.")); 659 KASSERT((bp->b_flags & B_REMFREE) == 0, 660 ("bremfree: buffer %p already marked for delayed removal.", bp)); 661 KASSERT(bp->b_qindex != QUEUE_NONE, 662 ("bremfree: buffer %p not on a queue.", bp)); 663 664 bp->b_flags |= B_REMFREE; 665 /* Fixup numfreebuffers count. */ 666 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 667 atomic_subtract_int(&numfreebuffers, 1); 668 } 669 670 /* 671 * bremfreef: 672 * 673 * Force an immediate removal from a free list. Used only in nfs when 674 * it abuses the b_freelist pointer. 675 */ 676 void 677 bremfreef(struct buf *bp) 678 { 679 mtx_lock(&bqlock); 680 bremfreel(bp); 681 mtx_unlock(&bqlock); 682 } 683 684 /* 685 * bremfreel: 686 * 687 * Removes a buffer from the free list, must be called with the 688 * bqlock held. 689 */ 690 static void 691 bremfreel(struct buf *bp) 692 { 693 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 694 bp, bp->b_vp, bp->b_flags); 695 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp)); 696 KASSERT(bp->b_qindex != QUEUE_NONE, 697 ("bremfreel: buffer %p not on a queue.", bp)); 698 mtx_assert(&bqlock, MA_OWNED); 699 700 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 701 bp->b_qindex = QUEUE_NONE; 702 /* 703 * If this was a delayed bremfree() we only need to remove the buffer 704 * from the queue and return the stats are already done. 705 */ 706 if (bp->b_flags & B_REMFREE) { 707 bp->b_flags &= ~B_REMFREE; 708 return; 709 } 710 /* 711 * Fixup numfreebuffers count. If the buffer is invalid or not 712 * delayed-write, the buffer was free and we must decrement 713 * numfreebuffers. 714 */ 715 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 716 atomic_subtract_int(&numfreebuffers, 1); 717 } 718 719 720 /* 721 * Get a buffer with the specified data. Look in the cache first. We 722 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 723 * is set, the buffer is valid and we do not have to do anything ( see 724 * getblk() ). This is really just a special case of breadn(). 725 */ 726 int 727 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 728 struct buf **bpp) 729 { 730 731 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 732 } 733 734 /* 735 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 736 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 737 * the buffer is valid and we do not have to do anything. 738 */ 739 void 740 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 741 int cnt, struct ucred * cred) 742 { 743 struct buf *rabp; 744 int i; 745 746 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 747 if (inmem(vp, *rablkno)) 748 continue; 749 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 750 751 if ((rabp->b_flags & B_CACHE) == 0) { 752 if (curthread != PCPU_GET(idlethread)) 753 curthread->td_proc->p_stats->p_ru.ru_inblock++; 754 rabp->b_flags |= B_ASYNC; 755 rabp->b_flags &= ~B_INVAL; 756 rabp->b_ioflags &= ~BIO_ERROR; 757 rabp->b_iocmd = BIO_READ; 758 if (rabp->b_rcred == NOCRED && cred != NOCRED) 759 rabp->b_rcred = crhold(cred); 760 vfs_busy_pages(rabp, 0); 761 BUF_KERNPROC(rabp); 762 rabp->b_iooffset = dbtob(rabp->b_blkno); 763 bstrategy(rabp); 764 } else { 765 brelse(rabp); 766 } 767 } 768 } 769 770 /* 771 * Operates like bread, but also starts asynchronous I/O on 772 * read-ahead blocks. 773 */ 774 int 775 breadn(struct vnode * vp, daddr_t blkno, int size, 776 daddr_t * rablkno, int *rabsize, 777 int cnt, struct ucred * cred, struct buf **bpp) 778 { 779 struct buf *bp; 780 int rv = 0, readwait = 0; 781 782 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 783 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 784 785 /* if not found in cache, do some I/O */ 786 if ((bp->b_flags & B_CACHE) == 0) { 787 if (curthread != PCPU_GET(idlethread)) 788 curthread->td_proc->p_stats->p_ru.ru_inblock++; 789 bp->b_iocmd = BIO_READ; 790 bp->b_flags &= ~B_INVAL; 791 bp->b_ioflags &= ~BIO_ERROR; 792 if (bp->b_rcred == NOCRED && cred != NOCRED) 793 bp->b_rcred = crhold(cred); 794 vfs_busy_pages(bp, 0); 795 bp->b_iooffset = dbtob(bp->b_blkno); 796 bstrategy(bp); 797 ++readwait; 798 } 799 800 breada(vp, rablkno, rabsize, cnt, cred); 801 802 if (readwait) { 803 rv = bufwait(bp); 804 } 805 return (rv); 806 } 807 808 /* 809 * Write, release buffer on completion. (Done by iodone 810 * if async). Do not bother writing anything if the buffer 811 * is invalid. 812 * 813 * Note that we set B_CACHE here, indicating that buffer is 814 * fully valid and thus cacheable. This is true even of NFS 815 * now so we set it generally. This could be set either here 816 * or in biodone() since the I/O is synchronous. We put it 817 * here. 818 */ 819 int 820 bufwrite(struct buf *bp) 821 { 822 int oldflags; 823 struct vnode *vp; 824 int vp_md; 825 826 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 827 if (bp->b_flags & B_INVAL) { 828 brelse(bp); 829 return (0); 830 } 831 832 oldflags = bp->b_flags; 833 834 if (BUF_REFCNT(bp) == 0) 835 panic("bufwrite: buffer is not busy???"); 836 837 if (bp->b_pin_count > 0) 838 bunpin_wait(bp); 839 840 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 841 ("FFS background buffer should not get here %p", bp)); 842 843 vp = bp->b_vp; 844 if (vp) 845 vp_md = vp->v_vflag & VV_MD; 846 else 847 vp_md = 0; 848 849 /* Mark the buffer clean */ 850 bundirty(bp); 851 852 bp->b_flags &= ~B_DONE; 853 bp->b_ioflags &= ~BIO_ERROR; 854 bp->b_flags |= B_CACHE; 855 bp->b_iocmd = BIO_WRITE; 856 857 bufobj_wref(bp->b_bufobj); 858 vfs_busy_pages(bp, 1); 859 860 /* 861 * Normal bwrites pipeline writes 862 */ 863 bp->b_runningbufspace = bp->b_bufsize; 864 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 865 866 if (curthread != PCPU_GET(idlethread)) 867 curthread->td_proc->p_stats->p_ru.ru_oublock++; 868 if (oldflags & B_ASYNC) 869 BUF_KERNPROC(bp); 870 bp->b_iooffset = dbtob(bp->b_blkno); 871 bstrategy(bp); 872 873 if ((oldflags & B_ASYNC) == 0) { 874 int rtval = bufwait(bp); 875 brelse(bp); 876 return (rtval); 877 } else { 878 /* 879 * don't allow the async write to saturate the I/O 880 * system. We will not deadlock here because 881 * we are blocking waiting for I/O that is already in-progress 882 * to complete. We do not block here if it is the update 883 * or syncer daemon trying to clean up as that can lead 884 * to deadlock. 885 */ 886 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 887 waitrunningbufspace(); 888 } 889 890 return (0); 891 } 892 893 void 894 bufbdflush(struct bufobj *bo, struct buf *bp) 895 { 896 struct buf *nbp; 897 898 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 899 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 900 altbufferflushes++; 901 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 902 BO_LOCK(bo); 903 /* 904 * Try to find a buffer to flush. 905 */ 906 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 907 if ((nbp->b_vflags & BV_BKGRDINPROG) || 908 BUF_LOCK(nbp, 909 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 910 continue; 911 if (bp == nbp) 912 panic("bdwrite: found ourselves"); 913 BO_UNLOCK(bo); 914 /* Don't countdeps with the bo lock held. */ 915 if (buf_countdeps(nbp, 0)) { 916 BO_LOCK(bo); 917 BUF_UNLOCK(nbp); 918 continue; 919 } 920 if (nbp->b_flags & B_CLUSTEROK) { 921 vfs_bio_awrite(nbp); 922 } else { 923 bremfree(nbp); 924 bawrite(nbp); 925 } 926 dirtybufferflushes++; 927 break; 928 } 929 if (nbp == NULL) 930 BO_UNLOCK(bo); 931 } 932 } 933 934 /* 935 * Delayed write. (Buffer is marked dirty). Do not bother writing 936 * anything if the buffer is marked invalid. 937 * 938 * Note that since the buffer must be completely valid, we can safely 939 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 940 * biodone() in order to prevent getblk from writing the buffer 941 * out synchronously. 942 */ 943 void 944 bdwrite(struct buf *bp) 945 { 946 struct thread *td = curthread; 947 struct vnode *vp; 948 struct bufobj *bo; 949 950 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 951 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 952 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy")); 953 954 if (bp->b_flags & B_INVAL) { 955 brelse(bp); 956 return; 957 } 958 959 /* 960 * If we have too many dirty buffers, don't create any more. 961 * If we are wildly over our limit, then force a complete 962 * cleanup. Otherwise, just keep the situation from getting 963 * out of control. Note that we have to avoid a recursive 964 * disaster and not try to clean up after our own cleanup! 965 */ 966 vp = bp->b_vp; 967 bo = bp->b_bufobj; 968 if ((td->td_pflags & TDP_COWINPROGRESS) == 0) 969 BO_BDFLUSH(bo, bp); 970 else 971 recursiveflushes++; 972 973 bdirty(bp); 974 /* 975 * Set B_CACHE, indicating that the buffer is fully valid. This is 976 * true even of NFS now. 977 */ 978 bp->b_flags |= B_CACHE; 979 980 /* 981 * This bmap keeps the system from needing to do the bmap later, 982 * perhaps when the system is attempting to do a sync. Since it 983 * is likely that the indirect block -- or whatever other datastructure 984 * that the filesystem needs is still in memory now, it is a good 985 * thing to do this. Note also, that if the pageout daemon is 986 * requesting a sync -- there might not be enough memory to do 987 * the bmap then... So, this is important to do. 988 */ 989 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 990 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 991 } 992 993 /* 994 * Set the *dirty* buffer range based upon the VM system dirty pages. 995 */ 996 vfs_setdirty(bp); 997 998 /* 999 * We need to do this here to satisfy the vnode_pager and the 1000 * pageout daemon, so that it thinks that the pages have been 1001 * "cleaned". Note that since the pages are in a delayed write 1002 * buffer -- the VFS layer "will" see that the pages get written 1003 * out on the next sync, or perhaps the cluster will be completed. 1004 */ 1005 vfs_clean_pages(bp); 1006 bqrelse(bp); 1007 1008 /* 1009 * Wakeup the buffer flushing daemon if we have a lot of dirty 1010 * buffers (midpoint between our recovery point and our stall 1011 * point). 1012 */ 1013 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1014 1015 /* 1016 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1017 * due to the softdep code. 1018 */ 1019 } 1020 1021 /* 1022 * bdirty: 1023 * 1024 * Turn buffer into delayed write request. We must clear BIO_READ and 1025 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1026 * itself to properly update it in the dirty/clean lists. We mark it 1027 * B_DONE to ensure that any asynchronization of the buffer properly 1028 * clears B_DONE ( else a panic will occur later ). 1029 * 1030 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1031 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1032 * should only be called if the buffer is known-good. 1033 * 1034 * Since the buffer is not on a queue, we do not update the numfreebuffers 1035 * count. 1036 * 1037 * The buffer must be on QUEUE_NONE. 1038 */ 1039 void 1040 bdirty(struct buf *bp) 1041 { 1042 1043 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1044 bp, bp->b_vp, bp->b_flags); 1045 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp)); 1046 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1047 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1048 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1049 bp->b_flags &= ~(B_RELBUF); 1050 bp->b_iocmd = BIO_WRITE; 1051 1052 if ((bp->b_flags & B_DELWRI) == 0) { 1053 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1054 reassignbuf(bp); 1055 atomic_add_int(&numdirtybuffers, 1); 1056 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1057 } 1058 } 1059 1060 /* 1061 * bundirty: 1062 * 1063 * Clear B_DELWRI for buffer. 1064 * 1065 * Since the buffer is not on a queue, we do not update the numfreebuffers 1066 * count. 1067 * 1068 * The buffer must be on QUEUE_NONE. 1069 */ 1070 1071 void 1072 bundirty(struct buf *bp) 1073 { 1074 1075 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1076 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1077 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1078 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1079 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp)); 1080 1081 if (bp->b_flags & B_DELWRI) { 1082 bp->b_flags &= ~B_DELWRI; 1083 reassignbuf(bp); 1084 atomic_subtract_int(&numdirtybuffers, 1); 1085 numdirtywakeup(lodirtybuffers); 1086 } 1087 /* 1088 * Since it is now being written, we can clear its deferred write flag. 1089 */ 1090 bp->b_flags &= ~B_DEFERRED; 1091 } 1092 1093 /* 1094 * bawrite: 1095 * 1096 * Asynchronous write. Start output on a buffer, but do not wait for 1097 * it to complete. The buffer is released when the output completes. 1098 * 1099 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1100 * B_INVAL buffers. Not us. 1101 */ 1102 void 1103 bawrite(struct buf *bp) 1104 { 1105 1106 bp->b_flags |= B_ASYNC; 1107 (void) bwrite(bp); 1108 } 1109 1110 /* 1111 * bwillwrite: 1112 * 1113 * Called prior to the locking of any vnodes when we are expecting to 1114 * write. We do not want to starve the buffer cache with too many 1115 * dirty buffers so we block here. By blocking prior to the locking 1116 * of any vnodes we attempt to avoid the situation where a locked vnode 1117 * prevents the various system daemons from flushing related buffers. 1118 */ 1119 1120 void 1121 bwillwrite(void) 1122 { 1123 1124 if (numdirtybuffers >= hidirtybuffers) { 1125 mtx_lock(&nblock); 1126 while (numdirtybuffers >= hidirtybuffers) { 1127 bd_wakeup(1); 1128 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1129 msleep(&needsbuffer, &nblock, 1130 (PRIBIO + 4), "flswai", 0); 1131 } 1132 mtx_unlock(&nblock); 1133 } 1134 } 1135 1136 /* 1137 * Return true if we have too many dirty buffers. 1138 */ 1139 int 1140 buf_dirty_count_severe(void) 1141 { 1142 1143 return(numdirtybuffers >= hidirtybuffers); 1144 } 1145 1146 /* 1147 * brelse: 1148 * 1149 * Release a busy buffer and, if requested, free its resources. The 1150 * buffer will be stashed in the appropriate bufqueue[] allowing it 1151 * to be accessed later as a cache entity or reused for other purposes. 1152 */ 1153 void 1154 brelse(struct buf *bp) 1155 { 1156 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1157 bp, bp->b_vp, bp->b_flags); 1158 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1159 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1160 1161 if (bp->b_flags & B_MANAGED) { 1162 bqrelse(bp); 1163 return; 1164 } 1165 1166 if (bp->b_iocmd == BIO_WRITE && 1167 (bp->b_ioflags & BIO_ERROR) && 1168 !(bp->b_flags & B_INVAL)) { 1169 /* 1170 * Failed write, redirty. Must clear BIO_ERROR to prevent 1171 * pages from being scrapped. If B_INVAL is set then 1172 * this case is not run and the next case is run to 1173 * destroy the buffer. B_INVAL can occur if the buffer 1174 * is outside the range supported by the underlying device. 1175 */ 1176 bp->b_ioflags &= ~BIO_ERROR; 1177 bdirty(bp); 1178 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1179 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1180 /* 1181 * Either a failed I/O or we were asked to free or not 1182 * cache the buffer. 1183 */ 1184 bp->b_flags |= B_INVAL; 1185 if (LIST_FIRST(&bp->b_dep) != NULL) 1186 buf_deallocate(bp); 1187 if (bp->b_flags & B_DELWRI) { 1188 atomic_subtract_int(&numdirtybuffers, 1); 1189 numdirtywakeup(lodirtybuffers); 1190 } 1191 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1192 if ((bp->b_flags & B_VMIO) == 0) { 1193 if (bp->b_bufsize) 1194 allocbuf(bp, 0); 1195 if (bp->b_vp) 1196 brelvp(bp); 1197 } 1198 } 1199 1200 /* 1201 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1202 * is called with B_DELWRI set, the underlying pages may wind up 1203 * getting freed causing a previous write (bdwrite()) to get 'lost' 1204 * because pages associated with a B_DELWRI bp are marked clean. 1205 * 1206 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1207 * if B_DELWRI is set. 1208 * 1209 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1210 * on pages to return pages to the VM page queues. 1211 */ 1212 if (bp->b_flags & B_DELWRI) 1213 bp->b_flags &= ~B_RELBUF; 1214 else if (vm_page_count_severe()) { 1215 /* 1216 * XXX This lock may not be necessary since BKGRDINPROG 1217 * cannot be set while we hold the buf lock, it can only be 1218 * cleared if it is already pending. 1219 */ 1220 if (bp->b_vp) { 1221 BO_LOCK(bp->b_bufobj); 1222 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1223 bp->b_flags |= B_RELBUF; 1224 BO_UNLOCK(bp->b_bufobj); 1225 } else 1226 bp->b_flags |= B_RELBUF; 1227 } 1228 1229 /* 1230 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1231 * constituted, not even NFS buffers now. Two flags effect this. If 1232 * B_INVAL, the struct buf is invalidated but the VM object is kept 1233 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1234 * 1235 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1236 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1237 * buffer is also B_INVAL because it hits the re-dirtying code above. 1238 * 1239 * Normally we can do this whether a buffer is B_DELWRI or not. If 1240 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1241 * the commit state and we cannot afford to lose the buffer. If the 1242 * buffer has a background write in progress, we need to keep it 1243 * around to prevent it from being reconstituted and starting a second 1244 * background write. 1245 */ 1246 if ((bp->b_flags & B_VMIO) 1247 && !(bp->b_vp->v_mount != NULL && 1248 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1249 !vn_isdisk(bp->b_vp, NULL) && 1250 (bp->b_flags & B_DELWRI)) 1251 ) { 1252 1253 int i, j, resid; 1254 vm_page_t m; 1255 off_t foff; 1256 vm_pindex_t poff; 1257 vm_object_t obj; 1258 1259 obj = bp->b_bufobj->bo_object; 1260 1261 /* 1262 * Get the base offset and length of the buffer. Note that 1263 * in the VMIO case if the buffer block size is not 1264 * page-aligned then b_data pointer may not be page-aligned. 1265 * But our b_pages[] array *IS* page aligned. 1266 * 1267 * block sizes less then DEV_BSIZE (usually 512) are not 1268 * supported due to the page granularity bits (m->valid, 1269 * m->dirty, etc...). 1270 * 1271 * See man buf(9) for more information 1272 */ 1273 resid = bp->b_bufsize; 1274 foff = bp->b_offset; 1275 VM_OBJECT_LOCK(obj); 1276 for (i = 0; i < bp->b_npages; i++) { 1277 int had_bogus = 0; 1278 1279 m = bp->b_pages[i]; 1280 1281 /* 1282 * If we hit a bogus page, fixup *all* the bogus pages 1283 * now. 1284 */ 1285 if (m == bogus_page) { 1286 poff = OFF_TO_IDX(bp->b_offset); 1287 had_bogus = 1; 1288 1289 for (j = i; j < bp->b_npages; j++) { 1290 vm_page_t mtmp; 1291 mtmp = bp->b_pages[j]; 1292 if (mtmp == bogus_page) { 1293 mtmp = vm_page_lookup(obj, poff + j); 1294 if (!mtmp) { 1295 panic("brelse: page missing\n"); 1296 } 1297 bp->b_pages[j] = mtmp; 1298 } 1299 } 1300 1301 if ((bp->b_flags & B_INVAL) == 0) { 1302 pmap_qenter( 1303 trunc_page((vm_offset_t)bp->b_data), 1304 bp->b_pages, bp->b_npages); 1305 } 1306 m = bp->b_pages[i]; 1307 } 1308 if ((bp->b_flags & B_NOCACHE) || 1309 (bp->b_ioflags & BIO_ERROR)) { 1310 int poffset = foff & PAGE_MASK; 1311 int presid = resid > (PAGE_SIZE - poffset) ? 1312 (PAGE_SIZE - poffset) : resid; 1313 1314 KASSERT(presid >= 0, ("brelse: extra page")); 1315 vm_page_lock_queues(); 1316 vm_page_set_invalid(m, poffset, presid); 1317 vm_page_unlock_queues(); 1318 if (had_bogus) 1319 printf("avoided corruption bug in bogus_page/brelse code\n"); 1320 } 1321 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1322 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1323 } 1324 VM_OBJECT_UNLOCK(obj); 1325 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1326 vfs_vmio_release(bp); 1327 1328 } else if (bp->b_flags & B_VMIO) { 1329 1330 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1331 vfs_vmio_release(bp); 1332 } 1333 1334 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1335 if (bp->b_bufsize != 0) 1336 allocbuf(bp, 0); 1337 if (bp->b_vp != NULL) 1338 brelvp(bp); 1339 } 1340 1341 if (BUF_REFCNT(bp) > 1) { 1342 /* do not release to free list */ 1343 BUF_UNLOCK(bp); 1344 return; 1345 } 1346 1347 /* enqueue */ 1348 mtx_lock(&bqlock); 1349 /* Handle delayed bremfree() processing. */ 1350 if (bp->b_flags & B_REMFREE) 1351 bremfreel(bp); 1352 if (bp->b_qindex != QUEUE_NONE) 1353 panic("brelse: free buffer onto another queue???"); 1354 1355 /* buffers with no memory */ 1356 if (bp->b_bufsize == 0) { 1357 bp->b_flags |= B_INVAL; 1358 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1359 if (bp->b_vflags & BV_BKGRDINPROG) 1360 panic("losing buffer 1"); 1361 if (bp->b_kvasize) { 1362 bp->b_qindex = QUEUE_EMPTYKVA; 1363 } else { 1364 bp->b_qindex = QUEUE_EMPTY; 1365 } 1366 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1367 /* buffers with junk contents */ 1368 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1369 (bp->b_ioflags & BIO_ERROR)) { 1370 bp->b_flags |= B_INVAL; 1371 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1372 if (bp->b_vflags & BV_BKGRDINPROG) 1373 panic("losing buffer 2"); 1374 bp->b_qindex = QUEUE_CLEAN; 1375 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1376 /* remaining buffers */ 1377 } else { 1378 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1379 (B_DELWRI|B_NEEDSGIANT)) 1380 bp->b_qindex = QUEUE_DIRTY_GIANT; 1381 if (bp->b_flags & B_DELWRI) 1382 bp->b_qindex = QUEUE_DIRTY; 1383 else 1384 bp->b_qindex = QUEUE_CLEAN; 1385 if (bp->b_flags & B_AGE) 1386 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1387 else 1388 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1389 } 1390 mtx_unlock(&bqlock); 1391 1392 /* 1393 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1394 * placed the buffer on the correct queue. We must also disassociate 1395 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1396 * find it. 1397 */ 1398 if (bp->b_flags & B_INVAL) { 1399 if (bp->b_flags & B_DELWRI) 1400 bundirty(bp); 1401 if (bp->b_vp) 1402 brelvp(bp); 1403 } 1404 1405 /* 1406 * Fixup numfreebuffers count. The bp is on an appropriate queue 1407 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1408 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1409 * if B_INVAL is set ). 1410 */ 1411 1412 if (!(bp->b_flags & B_DELWRI)) 1413 bufcountwakeup(); 1414 1415 /* 1416 * Something we can maybe free or reuse 1417 */ 1418 if (bp->b_bufsize || bp->b_kvasize) 1419 bufspacewakeup(); 1420 1421 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1422 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1423 panic("brelse: not dirty"); 1424 /* unlock */ 1425 BUF_UNLOCK(bp); 1426 } 1427 1428 /* 1429 * Release a buffer back to the appropriate queue but do not try to free 1430 * it. The buffer is expected to be used again soon. 1431 * 1432 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1433 * biodone() to requeue an async I/O on completion. It is also used when 1434 * known good buffers need to be requeued but we think we may need the data 1435 * again soon. 1436 * 1437 * XXX we should be able to leave the B_RELBUF hint set on completion. 1438 */ 1439 void 1440 bqrelse(struct buf *bp) 1441 { 1442 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1443 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1444 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1445 1446 if (BUF_REFCNT(bp) > 1) { 1447 /* do not release to free list */ 1448 BUF_UNLOCK(bp); 1449 return; 1450 } 1451 1452 if (bp->b_flags & B_MANAGED) { 1453 if (bp->b_flags & B_REMFREE) { 1454 mtx_lock(&bqlock); 1455 bremfreel(bp); 1456 mtx_unlock(&bqlock); 1457 } 1458 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1459 BUF_UNLOCK(bp); 1460 return; 1461 } 1462 1463 mtx_lock(&bqlock); 1464 /* Handle delayed bremfree() processing. */ 1465 if (bp->b_flags & B_REMFREE) 1466 bremfreel(bp); 1467 if (bp->b_qindex != QUEUE_NONE) 1468 panic("bqrelse: free buffer onto another queue???"); 1469 /* buffers with stale but valid contents */ 1470 if (bp->b_flags & B_DELWRI) { 1471 if (bp->b_flags & B_NEEDSGIANT) 1472 bp->b_qindex = QUEUE_DIRTY_GIANT; 1473 else 1474 bp->b_qindex = QUEUE_DIRTY; 1475 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1476 } else { 1477 /* 1478 * XXX This lock may not be necessary since BKGRDINPROG 1479 * cannot be set while we hold the buf lock, it can only be 1480 * cleared if it is already pending. 1481 */ 1482 BO_LOCK(bp->b_bufobj); 1483 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1484 BO_UNLOCK(bp->b_bufobj); 1485 bp->b_qindex = QUEUE_CLEAN; 1486 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1487 b_freelist); 1488 } else { 1489 /* 1490 * We are too low on memory, we have to try to free 1491 * the buffer (most importantly: the wired pages 1492 * making up its backing store) *now*. 1493 */ 1494 BO_UNLOCK(bp->b_bufobj); 1495 mtx_unlock(&bqlock); 1496 brelse(bp); 1497 return; 1498 } 1499 } 1500 mtx_unlock(&bqlock); 1501 1502 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1503 bufcountwakeup(); 1504 1505 /* 1506 * Something we can maybe free or reuse. 1507 */ 1508 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1509 bufspacewakeup(); 1510 1511 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1512 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1513 panic("bqrelse: not dirty"); 1514 /* unlock */ 1515 BUF_UNLOCK(bp); 1516 } 1517 1518 /* Give pages used by the bp back to the VM system (where possible) */ 1519 static void 1520 vfs_vmio_release(struct buf *bp) 1521 { 1522 int i; 1523 vm_page_t m; 1524 1525 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1526 vm_page_lock_queues(); 1527 for (i = 0; i < bp->b_npages; i++) { 1528 m = bp->b_pages[i]; 1529 bp->b_pages[i] = NULL; 1530 /* 1531 * In order to keep page LRU ordering consistent, put 1532 * everything on the inactive queue. 1533 */ 1534 vm_page_unwire(m, 0); 1535 /* 1536 * We don't mess with busy pages, it is 1537 * the responsibility of the process that 1538 * busied the pages to deal with them. 1539 */ 1540 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1541 continue; 1542 1543 if (m->wire_count == 0) { 1544 /* 1545 * Might as well free the page if we can and it has 1546 * no valid data. We also free the page if the 1547 * buffer was used for direct I/O 1548 */ 1549 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1550 m->hold_count == 0) { 1551 vm_page_free(m); 1552 } else if (bp->b_flags & B_DIRECT) { 1553 vm_page_try_to_free(m); 1554 } else if (vm_page_count_severe()) { 1555 vm_page_try_to_cache(m); 1556 } 1557 } 1558 } 1559 vm_page_unlock_queues(); 1560 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1561 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1562 1563 if (bp->b_bufsize) { 1564 bufspacewakeup(); 1565 bp->b_bufsize = 0; 1566 } 1567 bp->b_npages = 0; 1568 bp->b_flags &= ~B_VMIO; 1569 if (bp->b_vp) 1570 brelvp(bp); 1571 } 1572 1573 /* 1574 * Check to see if a block at a particular lbn is available for a clustered 1575 * write. 1576 */ 1577 static int 1578 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1579 { 1580 struct buf *bpa; 1581 int match; 1582 1583 match = 0; 1584 1585 /* If the buf isn't in core skip it */ 1586 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1587 return (0); 1588 1589 /* If the buf is busy we don't want to wait for it */ 1590 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1591 return (0); 1592 1593 /* Only cluster with valid clusterable delayed write buffers */ 1594 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1595 (B_DELWRI | B_CLUSTEROK)) 1596 goto done; 1597 1598 if (bpa->b_bufsize != size) 1599 goto done; 1600 1601 /* 1602 * Check to see if it is in the expected place on disk and that the 1603 * block has been mapped. 1604 */ 1605 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1606 match = 1; 1607 done: 1608 BUF_UNLOCK(bpa); 1609 return (match); 1610 } 1611 1612 /* 1613 * vfs_bio_awrite: 1614 * 1615 * Implement clustered async writes for clearing out B_DELWRI buffers. 1616 * This is much better then the old way of writing only one buffer at 1617 * a time. Note that we may not be presented with the buffers in the 1618 * correct order, so we search for the cluster in both directions. 1619 */ 1620 int 1621 vfs_bio_awrite(struct buf *bp) 1622 { 1623 int i; 1624 int j; 1625 daddr_t lblkno = bp->b_lblkno; 1626 struct vnode *vp = bp->b_vp; 1627 int ncl; 1628 int nwritten; 1629 int size; 1630 int maxcl; 1631 1632 /* 1633 * right now we support clustered writing only to regular files. If 1634 * we find a clusterable block we could be in the middle of a cluster 1635 * rather then at the beginning. 1636 */ 1637 if ((vp->v_type == VREG) && 1638 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1639 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1640 1641 size = vp->v_mount->mnt_stat.f_iosize; 1642 maxcl = MAXPHYS / size; 1643 1644 VI_LOCK(vp); 1645 for (i = 1; i < maxcl; i++) 1646 if (vfs_bio_clcheck(vp, size, lblkno + i, 1647 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1648 break; 1649 1650 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1651 if (vfs_bio_clcheck(vp, size, lblkno - j, 1652 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1653 break; 1654 1655 VI_UNLOCK(vp); 1656 --j; 1657 ncl = i + j; 1658 /* 1659 * this is a possible cluster write 1660 */ 1661 if (ncl != 1) { 1662 BUF_UNLOCK(bp); 1663 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1664 return nwritten; 1665 } 1666 } 1667 bremfree(bp); 1668 bp->b_flags |= B_ASYNC; 1669 /* 1670 * default (old) behavior, writing out only one block 1671 * 1672 * XXX returns b_bufsize instead of b_bcount for nwritten? 1673 */ 1674 nwritten = bp->b_bufsize; 1675 (void) bwrite(bp); 1676 1677 return nwritten; 1678 } 1679 1680 /* 1681 * getnewbuf: 1682 * 1683 * Find and initialize a new buffer header, freeing up existing buffers 1684 * in the bufqueues as necessary. The new buffer is returned locked. 1685 * 1686 * Important: B_INVAL is not set. If the caller wishes to throw the 1687 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1688 * 1689 * We block if: 1690 * We have insufficient buffer headers 1691 * We have insufficient buffer space 1692 * buffer_map is too fragmented ( space reservation fails ) 1693 * If we have to flush dirty buffers ( but we try to avoid this ) 1694 * 1695 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1696 * Instead we ask the buf daemon to do it for us. We attempt to 1697 * avoid piecemeal wakeups of the pageout daemon. 1698 */ 1699 1700 static struct buf * 1701 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1702 { 1703 struct buf *bp; 1704 struct buf *nbp; 1705 int defrag = 0; 1706 int nqindex; 1707 static int flushingbufs; 1708 1709 /* 1710 * We can't afford to block since we might be holding a vnode lock, 1711 * which may prevent system daemons from running. We deal with 1712 * low-memory situations by proactively returning memory and running 1713 * async I/O rather then sync I/O. 1714 */ 1715 1716 atomic_add_int(&getnewbufcalls, 1); 1717 atomic_subtract_int(&getnewbufrestarts, 1); 1718 restart: 1719 atomic_add_int(&getnewbufrestarts, 1); 1720 1721 /* 1722 * Setup for scan. If we do not have enough free buffers, 1723 * we setup a degenerate case that immediately fails. Note 1724 * that if we are specially marked process, we are allowed to 1725 * dip into our reserves. 1726 * 1727 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1728 * 1729 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1730 * However, there are a number of cases (defragging, reusing, ...) 1731 * where we cannot backup. 1732 */ 1733 mtx_lock(&bqlock); 1734 nqindex = QUEUE_EMPTYKVA; 1735 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1736 1737 if (nbp == NULL) { 1738 /* 1739 * If no EMPTYKVA buffers and we are either 1740 * defragging or reusing, locate a CLEAN buffer 1741 * to free or reuse. If bufspace useage is low 1742 * skip this step so we can allocate a new buffer. 1743 */ 1744 if (defrag || bufspace >= lobufspace) { 1745 nqindex = QUEUE_CLEAN; 1746 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1747 } 1748 1749 /* 1750 * If we could not find or were not allowed to reuse a 1751 * CLEAN buffer, check to see if it is ok to use an EMPTY 1752 * buffer. We can only use an EMPTY buffer if allocating 1753 * its KVA would not otherwise run us out of buffer space. 1754 */ 1755 if (nbp == NULL && defrag == 0 && 1756 bufspace + maxsize < hibufspace) { 1757 nqindex = QUEUE_EMPTY; 1758 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1759 } 1760 } 1761 1762 /* 1763 * Run scan, possibly freeing data and/or kva mappings on the fly 1764 * depending. 1765 */ 1766 1767 while ((bp = nbp) != NULL) { 1768 int qindex = nqindex; 1769 1770 /* 1771 * Calculate next bp ( we can only use it if we do not block 1772 * or do other fancy things ). 1773 */ 1774 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1775 switch(qindex) { 1776 case QUEUE_EMPTY: 1777 nqindex = QUEUE_EMPTYKVA; 1778 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1779 break; 1780 /* FALLTHROUGH */ 1781 case QUEUE_EMPTYKVA: 1782 nqindex = QUEUE_CLEAN; 1783 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1784 break; 1785 /* FALLTHROUGH */ 1786 case QUEUE_CLEAN: 1787 /* 1788 * nbp is NULL. 1789 */ 1790 break; 1791 } 1792 } 1793 /* 1794 * If we are defragging then we need a buffer with 1795 * b_kvasize != 0. XXX this situation should no longer 1796 * occur, if defrag is non-zero the buffer's b_kvasize 1797 * should also be non-zero at this point. XXX 1798 */ 1799 if (defrag && bp->b_kvasize == 0) { 1800 printf("Warning: defrag empty buffer %p\n", bp); 1801 continue; 1802 } 1803 1804 /* 1805 * Start freeing the bp. This is somewhat involved. nbp 1806 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1807 */ 1808 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1809 continue; 1810 if (bp->b_vp) { 1811 BO_LOCK(bp->b_bufobj); 1812 if (bp->b_vflags & BV_BKGRDINPROG) { 1813 BO_UNLOCK(bp->b_bufobj); 1814 BUF_UNLOCK(bp); 1815 continue; 1816 } 1817 BO_UNLOCK(bp->b_bufobj); 1818 } 1819 CTR6(KTR_BUF, 1820 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1821 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1822 bp->b_kvasize, bp->b_bufsize, qindex); 1823 1824 /* 1825 * Sanity Checks 1826 */ 1827 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1828 1829 /* 1830 * Note: we no longer distinguish between VMIO and non-VMIO 1831 * buffers. 1832 */ 1833 1834 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1835 1836 bremfreel(bp); 1837 mtx_unlock(&bqlock); 1838 1839 if (qindex == QUEUE_CLEAN) { 1840 if (bp->b_flags & B_VMIO) { 1841 bp->b_flags &= ~B_ASYNC; 1842 vfs_vmio_release(bp); 1843 } 1844 if (bp->b_vp) 1845 brelvp(bp); 1846 } 1847 1848 /* 1849 * NOTE: nbp is now entirely invalid. We can only restart 1850 * the scan from this point on. 1851 * 1852 * Get the rest of the buffer freed up. b_kva* is still 1853 * valid after this operation. 1854 */ 1855 1856 if (bp->b_rcred != NOCRED) { 1857 crfree(bp->b_rcred); 1858 bp->b_rcred = NOCRED; 1859 } 1860 if (bp->b_wcred != NOCRED) { 1861 crfree(bp->b_wcred); 1862 bp->b_wcred = NOCRED; 1863 } 1864 if (LIST_FIRST(&bp->b_dep) != NULL) 1865 buf_deallocate(bp); 1866 if (bp->b_vflags & BV_BKGRDINPROG) 1867 panic("losing buffer 3"); 1868 KASSERT(bp->b_vp == NULL, 1869 ("bp: %p still has vnode %p. qindex: %d", 1870 bp, bp->b_vp, qindex)); 1871 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1872 ("bp: %p still on a buffer list. xflags %X", 1873 bp, bp->b_xflags)); 1874 1875 if (bp->b_bufsize) 1876 allocbuf(bp, 0); 1877 1878 bp->b_flags = 0; 1879 bp->b_ioflags = 0; 1880 bp->b_xflags = 0; 1881 bp->b_vflags = 0; 1882 bp->b_vp = NULL; 1883 bp->b_blkno = bp->b_lblkno = 0; 1884 bp->b_offset = NOOFFSET; 1885 bp->b_iodone = 0; 1886 bp->b_error = 0; 1887 bp->b_resid = 0; 1888 bp->b_bcount = 0; 1889 bp->b_npages = 0; 1890 bp->b_dirtyoff = bp->b_dirtyend = 0; 1891 bp->b_bufobj = NULL; 1892 bp->b_pin_count = 0; 1893 bp->b_fsprivate1 = NULL; 1894 bp->b_fsprivate2 = NULL; 1895 bp->b_fsprivate3 = NULL; 1896 1897 LIST_INIT(&bp->b_dep); 1898 1899 /* 1900 * If we are defragging then free the buffer. 1901 */ 1902 if (defrag) { 1903 bp->b_flags |= B_INVAL; 1904 bfreekva(bp); 1905 brelse(bp); 1906 defrag = 0; 1907 goto restart; 1908 } 1909 1910 /* 1911 * Notify any waiters for the buffer lock about 1912 * identity change by freeing the buffer. 1913 */ 1914 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) { 1915 bp->b_flags |= B_INVAL; 1916 bfreekva(bp); 1917 brelse(bp); 1918 goto restart; 1919 } 1920 1921 /* 1922 * If we are overcomitted then recover the buffer and its 1923 * KVM space. This occurs in rare situations when multiple 1924 * processes are blocked in getnewbuf() or allocbuf(). 1925 */ 1926 if (bufspace >= hibufspace) 1927 flushingbufs = 1; 1928 if (flushingbufs && bp->b_kvasize != 0) { 1929 bp->b_flags |= B_INVAL; 1930 bfreekva(bp); 1931 brelse(bp); 1932 goto restart; 1933 } 1934 if (bufspace < lobufspace) 1935 flushingbufs = 0; 1936 break; 1937 } 1938 1939 /* 1940 * If we exhausted our list, sleep as appropriate. We may have to 1941 * wakeup various daemons and write out some dirty buffers. 1942 * 1943 * Generally we are sleeping due to insufficient buffer space. 1944 */ 1945 1946 if (bp == NULL) { 1947 int flags; 1948 char *waitmsg; 1949 1950 if (defrag) { 1951 flags = VFS_BIO_NEED_BUFSPACE; 1952 waitmsg = "nbufkv"; 1953 } else if (bufspace >= hibufspace) { 1954 waitmsg = "nbufbs"; 1955 flags = VFS_BIO_NEED_BUFSPACE; 1956 } else { 1957 waitmsg = "newbuf"; 1958 flags = VFS_BIO_NEED_ANY; 1959 } 1960 mtx_lock(&nblock); 1961 needsbuffer |= flags; 1962 mtx_unlock(&nblock); 1963 mtx_unlock(&bqlock); 1964 1965 bd_speedup(); /* heeeelp */ 1966 1967 mtx_lock(&nblock); 1968 while (needsbuffer & flags) { 1969 if (msleep(&needsbuffer, &nblock, 1970 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1971 mtx_unlock(&nblock); 1972 return (NULL); 1973 } 1974 } 1975 mtx_unlock(&nblock); 1976 } else { 1977 /* 1978 * We finally have a valid bp. We aren't quite out of the 1979 * woods, we still have to reserve kva space. In order 1980 * to keep fragmentation sane we only allocate kva in 1981 * BKVASIZE chunks. 1982 */ 1983 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1984 1985 if (maxsize != bp->b_kvasize) { 1986 vm_offset_t addr = 0; 1987 1988 bfreekva(bp); 1989 1990 vm_map_lock(buffer_map); 1991 if (vm_map_findspace(buffer_map, 1992 vm_map_min(buffer_map), maxsize, &addr)) { 1993 /* 1994 * Uh oh. Buffer map is to fragmented. We 1995 * must defragment the map. 1996 */ 1997 atomic_add_int(&bufdefragcnt, 1); 1998 vm_map_unlock(buffer_map); 1999 defrag = 1; 2000 bp->b_flags |= B_INVAL; 2001 brelse(bp); 2002 goto restart; 2003 } 2004 if (addr) { 2005 vm_map_insert(buffer_map, NULL, 0, 2006 addr, addr + maxsize, 2007 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2008 2009 bp->b_kvabase = (caddr_t) addr; 2010 bp->b_kvasize = maxsize; 2011 atomic_add_int(&bufspace, bp->b_kvasize); 2012 atomic_add_int(&bufreusecnt, 1); 2013 } 2014 vm_map_unlock(buffer_map); 2015 } 2016 bp->b_saveaddr = bp->b_kvabase; 2017 bp->b_data = bp->b_saveaddr; 2018 } 2019 return(bp); 2020 } 2021 2022 /* 2023 * buf_daemon: 2024 * 2025 * buffer flushing daemon. Buffers are normally flushed by the 2026 * update daemon but if it cannot keep up this process starts to 2027 * take the load in an attempt to prevent getnewbuf() from blocking. 2028 */ 2029 2030 static struct kproc_desc buf_kp = { 2031 "bufdaemon", 2032 buf_daemon, 2033 &bufdaemonproc 2034 }; 2035 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2036 2037 static void 2038 buf_daemon() 2039 { 2040 2041 /* 2042 * This process needs to be suspended prior to shutdown sync. 2043 */ 2044 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2045 SHUTDOWN_PRI_LAST); 2046 2047 /* 2048 * This process is allowed to take the buffer cache to the limit 2049 */ 2050 curthread->td_pflags |= TDP_NORUNNINGBUF; 2051 mtx_lock(&bdlock); 2052 for (;;) { 2053 bd_request = 0; 2054 mtx_unlock(&bdlock); 2055 2056 kthread_suspend_check(bufdaemonproc); 2057 2058 /* 2059 * Do the flush. Limit the amount of in-transit I/O we 2060 * allow to build up, otherwise we would completely saturate 2061 * the I/O system. Wakeup any waiting processes before we 2062 * normally would so they can run in parallel with our drain. 2063 */ 2064 while (numdirtybuffers > lodirtybuffers) { 2065 int flushed; 2066 2067 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2068 /* The list empty check here is slightly racy */ 2069 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2070 mtx_lock(&Giant); 2071 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2072 mtx_unlock(&Giant); 2073 } 2074 if (flushed == 0) { 2075 /* 2076 * Could not find any buffers without rollback 2077 * dependencies, so just write the first one 2078 * in the hopes of eventually making progress. 2079 */ 2080 flushbufqueues(QUEUE_DIRTY, 1); 2081 if (!TAILQ_EMPTY( 2082 &bufqueues[QUEUE_DIRTY_GIANT])) { 2083 mtx_lock(&Giant); 2084 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2085 mtx_unlock(&Giant); 2086 } 2087 break; 2088 } 2089 uio_yield(); 2090 } 2091 2092 /* 2093 * Only clear bd_request if we have reached our low water 2094 * mark. The buf_daemon normally waits 1 second and 2095 * then incrementally flushes any dirty buffers that have 2096 * built up, within reason. 2097 * 2098 * If we were unable to hit our low water mark and couldn't 2099 * find any flushable buffers, we sleep half a second. 2100 * Otherwise we loop immediately. 2101 */ 2102 mtx_lock(&bdlock); 2103 if (numdirtybuffers <= lodirtybuffers) { 2104 /* 2105 * We reached our low water mark, reset the 2106 * request and sleep until we are needed again. 2107 * The sleep is just so the suspend code works. 2108 */ 2109 bd_request = 0; 2110 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2111 } else { 2112 /* 2113 * We couldn't find any flushable dirty buffers but 2114 * still have too many dirty buffers, we 2115 * have to sleep and try again. (rare) 2116 */ 2117 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2118 } 2119 } 2120 } 2121 2122 /* 2123 * flushbufqueues: 2124 * 2125 * Try to flush a buffer in the dirty queue. We must be careful to 2126 * free up B_INVAL buffers instead of write them, which NFS is 2127 * particularly sensitive to. 2128 */ 2129 static int flushwithdeps = 0; 2130 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2131 0, "Number of buffers flushed with dependecies that require rollbacks"); 2132 2133 static int 2134 flushbufqueues(int queue, int flushdeps) 2135 { 2136 struct thread *td = curthread; 2137 struct buf sentinel; 2138 struct vnode *vp; 2139 struct mount *mp; 2140 struct buf *bp; 2141 int hasdeps; 2142 int flushed; 2143 int target; 2144 2145 target = numdirtybuffers - lodirtybuffers; 2146 if (flushdeps && target > 2) 2147 target /= 2; 2148 flushed = 0; 2149 bp = NULL; 2150 mtx_lock(&bqlock); 2151 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2152 while (flushed != target) { 2153 bp = TAILQ_FIRST(&bufqueues[queue]); 2154 if (bp == &sentinel) 2155 break; 2156 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2157 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2158 2159 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2160 continue; 2161 if (bp->b_pin_count > 0) { 2162 BUF_UNLOCK(bp); 2163 continue; 2164 } 2165 BO_LOCK(bp->b_bufobj); 2166 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2167 (bp->b_flags & B_DELWRI) == 0) { 2168 BO_UNLOCK(bp->b_bufobj); 2169 BUF_UNLOCK(bp); 2170 continue; 2171 } 2172 BO_UNLOCK(bp->b_bufobj); 2173 if (bp->b_flags & B_INVAL) { 2174 bremfreel(bp); 2175 mtx_unlock(&bqlock); 2176 brelse(bp); 2177 flushed++; 2178 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2179 mtx_lock(&bqlock); 2180 continue; 2181 } 2182 2183 if (LIST_FIRST(&bp->b_dep) != NULL && buf_countdeps(bp, 0)) { 2184 if (flushdeps == 0) { 2185 BUF_UNLOCK(bp); 2186 continue; 2187 } 2188 hasdeps = 1; 2189 } else 2190 hasdeps = 0; 2191 /* 2192 * We must hold the lock on a vnode before writing 2193 * one of its buffers. Otherwise we may confuse, or 2194 * in the case of a snapshot vnode, deadlock the 2195 * system. 2196 * 2197 * The lock order here is the reverse of the normal 2198 * of vnode followed by buf lock. This is ok because 2199 * the NOWAIT will prevent deadlock. 2200 */ 2201 vp = bp->b_vp; 2202 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2203 BUF_UNLOCK(bp); 2204 continue; 2205 } 2206 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2207 mtx_unlock(&bqlock); 2208 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2209 bp, bp->b_vp, bp->b_flags); 2210 vfs_bio_awrite(bp); 2211 vn_finished_write(mp); 2212 VOP_UNLOCK(vp, 0, td); 2213 flushwithdeps += hasdeps; 2214 flushed++; 2215 waitrunningbufspace(); 2216 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2217 mtx_lock(&bqlock); 2218 continue; 2219 } 2220 vn_finished_write(mp); 2221 BUF_UNLOCK(bp); 2222 } 2223 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2224 mtx_unlock(&bqlock); 2225 return (flushed); 2226 } 2227 2228 /* 2229 * Check to see if a block is currently memory resident. 2230 */ 2231 struct buf * 2232 incore(struct bufobj *bo, daddr_t blkno) 2233 { 2234 struct buf *bp; 2235 2236 BO_LOCK(bo); 2237 bp = gbincore(bo, blkno); 2238 BO_UNLOCK(bo); 2239 return (bp); 2240 } 2241 2242 /* 2243 * Returns true if no I/O is needed to access the 2244 * associated VM object. This is like incore except 2245 * it also hunts around in the VM system for the data. 2246 */ 2247 2248 static int 2249 inmem(struct vnode * vp, daddr_t blkno) 2250 { 2251 vm_object_t obj; 2252 vm_offset_t toff, tinc, size; 2253 vm_page_t m; 2254 vm_ooffset_t off; 2255 2256 ASSERT_VOP_LOCKED(vp, "inmem"); 2257 2258 if (incore(&vp->v_bufobj, blkno)) 2259 return 1; 2260 if (vp->v_mount == NULL) 2261 return 0; 2262 obj = vp->v_object; 2263 if (obj == NULL) 2264 return (0); 2265 2266 size = PAGE_SIZE; 2267 if (size > vp->v_mount->mnt_stat.f_iosize) 2268 size = vp->v_mount->mnt_stat.f_iosize; 2269 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2270 2271 VM_OBJECT_LOCK(obj); 2272 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2273 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2274 if (!m) 2275 goto notinmem; 2276 tinc = size; 2277 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2278 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2279 if (vm_page_is_valid(m, 2280 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2281 goto notinmem; 2282 } 2283 VM_OBJECT_UNLOCK(obj); 2284 return 1; 2285 2286 notinmem: 2287 VM_OBJECT_UNLOCK(obj); 2288 return (0); 2289 } 2290 2291 /* 2292 * vfs_setdirty: 2293 * 2294 * Sets the dirty range for a buffer based on the status of the dirty 2295 * bits in the pages comprising the buffer. 2296 * 2297 * The range is limited to the size of the buffer. 2298 * 2299 * This routine is primarily used by NFS, but is generalized for the 2300 * B_VMIO case. 2301 */ 2302 static void 2303 vfs_setdirty(struct buf *bp) 2304 { 2305 2306 /* 2307 * Degenerate case - empty buffer 2308 */ 2309 2310 if (bp->b_bufsize == 0) 2311 return; 2312 2313 /* 2314 * We qualify the scan for modified pages on whether the 2315 * object has been flushed yet. 2316 */ 2317 2318 if ((bp->b_flags & B_VMIO) == 0) 2319 return; 2320 2321 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2322 vfs_setdirty_locked_object(bp); 2323 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2324 } 2325 2326 static void 2327 vfs_setdirty_locked_object(struct buf *bp) 2328 { 2329 vm_object_t object; 2330 int i; 2331 2332 object = bp->b_bufobj->bo_object; 2333 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2334 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2335 vm_offset_t boffset; 2336 vm_offset_t eoffset; 2337 2338 vm_page_lock_queues(); 2339 /* 2340 * test the pages to see if they have been modified directly 2341 * by users through the VM system. 2342 */ 2343 for (i = 0; i < bp->b_npages; i++) 2344 vm_page_test_dirty(bp->b_pages[i]); 2345 2346 /* 2347 * Calculate the encompassing dirty range, boffset and eoffset, 2348 * (eoffset - boffset) bytes. 2349 */ 2350 2351 for (i = 0; i < bp->b_npages; i++) { 2352 if (bp->b_pages[i]->dirty) 2353 break; 2354 } 2355 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2356 2357 for (i = bp->b_npages - 1; i >= 0; --i) { 2358 if (bp->b_pages[i]->dirty) { 2359 break; 2360 } 2361 } 2362 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2363 2364 vm_page_unlock_queues(); 2365 /* 2366 * Fit it to the buffer. 2367 */ 2368 2369 if (eoffset > bp->b_bcount) 2370 eoffset = bp->b_bcount; 2371 2372 /* 2373 * If we have a good dirty range, merge with the existing 2374 * dirty range. 2375 */ 2376 2377 if (boffset < eoffset) { 2378 if (bp->b_dirtyoff > boffset) 2379 bp->b_dirtyoff = boffset; 2380 if (bp->b_dirtyend < eoffset) 2381 bp->b_dirtyend = eoffset; 2382 } 2383 } 2384 } 2385 2386 /* 2387 * getblk: 2388 * 2389 * Get a block given a specified block and offset into a file/device. 2390 * The buffers B_DONE bit will be cleared on return, making it almost 2391 * ready for an I/O initiation. B_INVAL may or may not be set on 2392 * return. The caller should clear B_INVAL prior to initiating a 2393 * READ. 2394 * 2395 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2396 * an existing buffer. 2397 * 2398 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2399 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2400 * and then cleared based on the backing VM. If the previous buffer is 2401 * non-0-sized but invalid, B_CACHE will be cleared. 2402 * 2403 * If getblk() must create a new buffer, the new buffer is returned with 2404 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2405 * case it is returned with B_INVAL clear and B_CACHE set based on the 2406 * backing VM. 2407 * 2408 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2409 * B_CACHE bit is clear. 2410 * 2411 * What this means, basically, is that the caller should use B_CACHE to 2412 * determine whether the buffer is fully valid or not and should clear 2413 * B_INVAL prior to issuing a read. If the caller intends to validate 2414 * the buffer by loading its data area with something, the caller needs 2415 * to clear B_INVAL. If the caller does this without issuing an I/O, 2416 * the caller should set B_CACHE ( as an optimization ), else the caller 2417 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2418 * a write attempt or if it was a successfull read. If the caller 2419 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2420 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2421 */ 2422 struct buf * 2423 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2424 int flags) 2425 { 2426 struct buf *bp; 2427 struct bufobj *bo; 2428 int error; 2429 2430 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2431 ASSERT_VOP_LOCKED(vp, "getblk"); 2432 if (size > MAXBSIZE) 2433 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2434 2435 bo = &vp->v_bufobj; 2436 loop: 2437 /* 2438 * Block if we are low on buffers. Certain processes are allowed 2439 * to completely exhaust the buffer cache. 2440 * 2441 * If this check ever becomes a bottleneck it may be better to 2442 * move it into the else, when gbincore() fails. At the moment 2443 * it isn't a problem. 2444 * 2445 * XXX remove if 0 sections (clean this up after its proven) 2446 */ 2447 if (numfreebuffers == 0) { 2448 if (curthread == PCPU_GET(idlethread)) 2449 return NULL; 2450 mtx_lock(&nblock); 2451 needsbuffer |= VFS_BIO_NEED_ANY; 2452 mtx_unlock(&nblock); 2453 } 2454 2455 VI_LOCK(vp); 2456 bp = gbincore(bo, blkno); 2457 if (bp != NULL) { 2458 int lockflags; 2459 /* 2460 * Buffer is in-core. If the buffer is not busy, it must 2461 * be on a queue. 2462 */ 2463 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2464 2465 if (flags & GB_LOCK_NOWAIT) 2466 lockflags |= LK_NOWAIT; 2467 2468 error = BUF_TIMELOCK(bp, lockflags, 2469 VI_MTX(vp), "getblk", slpflag, slptimeo); 2470 2471 /* 2472 * If we slept and got the lock we have to restart in case 2473 * the buffer changed identities. 2474 */ 2475 if (error == ENOLCK) 2476 goto loop; 2477 /* We timed out or were interrupted. */ 2478 else if (error) 2479 return (NULL); 2480 2481 /* 2482 * The buffer is locked. B_CACHE is cleared if the buffer is 2483 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2484 * and for a VMIO buffer B_CACHE is adjusted according to the 2485 * backing VM cache. 2486 */ 2487 if (bp->b_flags & B_INVAL) 2488 bp->b_flags &= ~B_CACHE; 2489 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2490 bp->b_flags |= B_CACHE; 2491 bremfree(bp); 2492 2493 /* 2494 * check for size inconsistancies for non-VMIO case. 2495 */ 2496 2497 if (bp->b_bcount != size) { 2498 if ((bp->b_flags & B_VMIO) == 0 || 2499 (size > bp->b_kvasize)) { 2500 if (bp->b_flags & B_DELWRI) { 2501 /* 2502 * If buffer is pinned and caller does 2503 * not want sleep waiting for it to be 2504 * unpinned, bail out 2505 * */ 2506 if (bp->b_pin_count > 0) { 2507 if (flags & GB_LOCK_NOWAIT) { 2508 bqrelse(bp); 2509 return (NULL); 2510 } else { 2511 bunpin_wait(bp); 2512 } 2513 } 2514 bp->b_flags |= B_NOCACHE; 2515 bwrite(bp); 2516 } else { 2517 if (LIST_FIRST(&bp->b_dep) == NULL) { 2518 bp->b_flags |= B_RELBUF; 2519 brelse(bp); 2520 } else { 2521 bp->b_flags |= B_NOCACHE; 2522 bwrite(bp); 2523 } 2524 } 2525 goto loop; 2526 } 2527 } 2528 2529 /* 2530 * If the size is inconsistant in the VMIO case, we can resize 2531 * the buffer. This might lead to B_CACHE getting set or 2532 * cleared. If the size has not changed, B_CACHE remains 2533 * unchanged from its previous state. 2534 */ 2535 2536 if (bp->b_bcount != size) 2537 allocbuf(bp, size); 2538 2539 KASSERT(bp->b_offset != NOOFFSET, 2540 ("getblk: no buffer offset")); 2541 2542 /* 2543 * A buffer with B_DELWRI set and B_CACHE clear must 2544 * be committed before we can return the buffer in 2545 * order to prevent the caller from issuing a read 2546 * ( due to B_CACHE not being set ) and overwriting 2547 * it. 2548 * 2549 * Most callers, including NFS and FFS, need this to 2550 * operate properly either because they assume they 2551 * can issue a read if B_CACHE is not set, or because 2552 * ( for example ) an uncached B_DELWRI might loop due 2553 * to softupdates re-dirtying the buffer. In the latter 2554 * case, B_CACHE is set after the first write completes, 2555 * preventing further loops. 2556 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2557 * above while extending the buffer, we cannot allow the 2558 * buffer to remain with B_CACHE set after the write 2559 * completes or it will represent a corrupt state. To 2560 * deal with this we set B_NOCACHE to scrap the buffer 2561 * after the write. 2562 * 2563 * We might be able to do something fancy, like setting 2564 * B_CACHE in bwrite() except if B_DELWRI is already set, 2565 * so the below call doesn't set B_CACHE, but that gets real 2566 * confusing. This is much easier. 2567 */ 2568 2569 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2570 bp->b_flags |= B_NOCACHE; 2571 bwrite(bp); 2572 goto loop; 2573 } 2574 bp->b_flags &= ~B_DONE; 2575 } else { 2576 int bsize, maxsize, vmio; 2577 off_t offset; 2578 2579 /* 2580 * Buffer is not in-core, create new buffer. The buffer 2581 * returned by getnewbuf() is locked. Note that the returned 2582 * buffer is also considered valid (not marked B_INVAL). 2583 */ 2584 VI_UNLOCK(vp); 2585 /* 2586 * If the user does not want us to create the buffer, bail out 2587 * here. 2588 */ 2589 if (flags & GB_NOCREAT) 2590 return NULL; 2591 bsize = bo->bo_bsize; 2592 offset = blkno * bsize; 2593 vmio = vp->v_object != NULL; 2594 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2595 maxsize = imax(maxsize, bsize); 2596 2597 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2598 if (bp == NULL) { 2599 if (slpflag || slptimeo) 2600 return NULL; 2601 goto loop; 2602 } 2603 2604 /* 2605 * This code is used to make sure that a buffer is not 2606 * created while the getnewbuf routine is blocked. 2607 * This can be a problem whether the vnode is locked or not. 2608 * If the buffer is created out from under us, we have to 2609 * throw away the one we just created. 2610 * 2611 * Note: this must occur before we associate the buffer 2612 * with the vp especially considering limitations in 2613 * the splay tree implementation when dealing with duplicate 2614 * lblkno's. 2615 */ 2616 BO_LOCK(bo); 2617 if (gbincore(bo, blkno)) { 2618 BO_UNLOCK(bo); 2619 bp->b_flags |= B_INVAL; 2620 brelse(bp); 2621 goto loop; 2622 } 2623 2624 /* 2625 * Insert the buffer into the hash, so that it can 2626 * be found by incore. 2627 */ 2628 bp->b_blkno = bp->b_lblkno = blkno; 2629 bp->b_offset = offset; 2630 bgetvp(vp, bp); 2631 BO_UNLOCK(bo); 2632 2633 /* 2634 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2635 * buffer size starts out as 0, B_CACHE will be set by 2636 * allocbuf() for the VMIO case prior to it testing the 2637 * backing store for validity. 2638 */ 2639 2640 if (vmio) { 2641 bp->b_flags |= B_VMIO; 2642 #if defined(VFS_BIO_DEBUG) 2643 if (vn_canvmio(vp) != TRUE) 2644 printf("getblk: VMIO on vnode type %d\n", 2645 vp->v_type); 2646 #endif 2647 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2648 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2649 bp, vp->v_object, bp->b_bufobj->bo_object)); 2650 } else { 2651 bp->b_flags &= ~B_VMIO; 2652 KASSERT(bp->b_bufobj->bo_object == NULL, 2653 ("ARGH! has b_bufobj->bo_object %p %p\n", 2654 bp, bp->b_bufobj->bo_object)); 2655 } 2656 2657 allocbuf(bp, size); 2658 bp->b_flags &= ~B_DONE; 2659 } 2660 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2661 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2662 KASSERT(bp->b_bufobj == bo, 2663 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2664 return (bp); 2665 } 2666 2667 /* 2668 * Get an empty, disassociated buffer of given size. The buffer is initially 2669 * set to B_INVAL. 2670 */ 2671 struct buf * 2672 geteblk(int size) 2673 { 2674 struct buf *bp; 2675 int maxsize; 2676 2677 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2678 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2679 continue; 2680 allocbuf(bp, size); 2681 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2682 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2683 return (bp); 2684 } 2685 2686 2687 /* 2688 * This code constitutes the buffer memory from either anonymous system 2689 * memory (in the case of non-VMIO operations) or from an associated 2690 * VM object (in the case of VMIO operations). This code is able to 2691 * resize a buffer up or down. 2692 * 2693 * Note that this code is tricky, and has many complications to resolve 2694 * deadlock or inconsistant data situations. Tread lightly!!! 2695 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2696 * the caller. Calling this code willy nilly can result in the loss of data. 2697 * 2698 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2699 * B_CACHE for the non-VMIO case. 2700 */ 2701 2702 int 2703 allocbuf(struct buf *bp, int size) 2704 { 2705 int newbsize, mbsize; 2706 int i; 2707 2708 if (BUF_REFCNT(bp) == 0) 2709 panic("allocbuf: buffer not busy"); 2710 2711 if (bp->b_kvasize < size) 2712 panic("allocbuf: buffer too small"); 2713 2714 if ((bp->b_flags & B_VMIO) == 0) { 2715 caddr_t origbuf; 2716 int origbufsize; 2717 /* 2718 * Just get anonymous memory from the kernel. Don't 2719 * mess with B_CACHE. 2720 */ 2721 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2722 if (bp->b_flags & B_MALLOC) 2723 newbsize = mbsize; 2724 else 2725 newbsize = round_page(size); 2726 2727 if (newbsize < bp->b_bufsize) { 2728 /* 2729 * malloced buffers are not shrunk 2730 */ 2731 if (bp->b_flags & B_MALLOC) { 2732 if (newbsize) { 2733 bp->b_bcount = size; 2734 } else { 2735 free(bp->b_data, M_BIOBUF); 2736 if (bp->b_bufsize) { 2737 atomic_subtract_int( 2738 &bufmallocspace, 2739 bp->b_bufsize); 2740 bufspacewakeup(); 2741 bp->b_bufsize = 0; 2742 } 2743 bp->b_saveaddr = bp->b_kvabase; 2744 bp->b_data = bp->b_saveaddr; 2745 bp->b_bcount = 0; 2746 bp->b_flags &= ~B_MALLOC; 2747 } 2748 return 1; 2749 } 2750 vm_hold_free_pages( 2751 bp, 2752 (vm_offset_t) bp->b_data + newbsize, 2753 (vm_offset_t) bp->b_data + bp->b_bufsize); 2754 } else if (newbsize > bp->b_bufsize) { 2755 /* 2756 * We only use malloced memory on the first allocation. 2757 * and revert to page-allocated memory when the buffer 2758 * grows. 2759 */ 2760 /* 2761 * There is a potential smp race here that could lead 2762 * to bufmallocspace slightly passing the max. It 2763 * is probably extremely rare and not worth worrying 2764 * over. 2765 */ 2766 if ( (bufmallocspace < maxbufmallocspace) && 2767 (bp->b_bufsize == 0) && 2768 (mbsize <= PAGE_SIZE/2)) { 2769 2770 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2771 bp->b_bufsize = mbsize; 2772 bp->b_bcount = size; 2773 bp->b_flags |= B_MALLOC; 2774 atomic_add_int(&bufmallocspace, mbsize); 2775 return 1; 2776 } 2777 origbuf = NULL; 2778 origbufsize = 0; 2779 /* 2780 * If the buffer is growing on its other-than-first allocation, 2781 * then we revert to the page-allocation scheme. 2782 */ 2783 if (bp->b_flags & B_MALLOC) { 2784 origbuf = bp->b_data; 2785 origbufsize = bp->b_bufsize; 2786 bp->b_data = bp->b_kvabase; 2787 if (bp->b_bufsize) { 2788 atomic_subtract_int(&bufmallocspace, 2789 bp->b_bufsize); 2790 bufspacewakeup(); 2791 bp->b_bufsize = 0; 2792 } 2793 bp->b_flags &= ~B_MALLOC; 2794 newbsize = round_page(newbsize); 2795 } 2796 vm_hold_load_pages( 2797 bp, 2798 (vm_offset_t) bp->b_data + bp->b_bufsize, 2799 (vm_offset_t) bp->b_data + newbsize); 2800 if (origbuf) { 2801 bcopy(origbuf, bp->b_data, origbufsize); 2802 free(origbuf, M_BIOBUF); 2803 } 2804 } 2805 } else { 2806 int desiredpages; 2807 2808 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2809 desiredpages = (size == 0) ? 0 : 2810 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2811 2812 if (bp->b_flags & B_MALLOC) 2813 panic("allocbuf: VMIO buffer can't be malloced"); 2814 /* 2815 * Set B_CACHE initially if buffer is 0 length or will become 2816 * 0-length. 2817 */ 2818 if (size == 0 || bp->b_bufsize == 0) 2819 bp->b_flags |= B_CACHE; 2820 2821 if (newbsize < bp->b_bufsize) { 2822 /* 2823 * DEV_BSIZE aligned new buffer size is less then the 2824 * DEV_BSIZE aligned existing buffer size. Figure out 2825 * if we have to remove any pages. 2826 */ 2827 if (desiredpages < bp->b_npages) { 2828 vm_page_t m; 2829 2830 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2831 vm_page_lock_queues(); 2832 for (i = desiredpages; i < bp->b_npages; i++) { 2833 /* 2834 * the page is not freed here -- it 2835 * is the responsibility of 2836 * vnode_pager_setsize 2837 */ 2838 m = bp->b_pages[i]; 2839 KASSERT(m != bogus_page, 2840 ("allocbuf: bogus page found")); 2841 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2842 vm_page_lock_queues(); 2843 2844 bp->b_pages[i] = NULL; 2845 vm_page_unwire(m, 0); 2846 } 2847 vm_page_unlock_queues(); 2848 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2849 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2850 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2851 bp->b_npages = desiredpages; 2852 } 2853 } else if (size > bp->b_bcount) { 2854 /* 2855 * We are growing the buffer, possibly in a 2856 * byte-granular fashion. 2857 */ 2858 struct vnode *vp; 2859 vm_object_t obj; 2860 vm_offset_t toff; 2861 vm_offset_t tinc; 2862 2863 /* 2864 * Step 1, bring in the VM pages from the object, 2865 * allocating them if necessary. We must clear 2866 * B_CACHE if these pages are not valid for the 2867 * range covered by the buffer. 2868 */ 2869 2870 vp = bp->b_vp; 2871 obj = bp->b_bufobj->bo_object; 2872 2873 VM_OBJECT_LOCK(obj); 2874 while (bp->b_npages < desiredpages) { 2875 vm_page_t m; 2876 vm_pindex_t pi; 2877 2878 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2879 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2880 /* 2881 * note: must allocate system pages 2882 * since blocking here could intefere 2883 * with paging I/O, no matter which 2884 * process we are. 2885 */ 2886 m = vm_page_alloc(obj, pi, 2887 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2888 VM_ALLOC_WIRED); 2889 if (m == NULL) { 2890 atomic_add_int(&vm_pageout_deficit, 2891 desiredpages - bp->b_npages); 2892 VM_OBJECT_UNLOCK(obj); 2893 VM_WAIT; 2894 VM_OBJECT_LOCK(obj); 2895 } else { 2896 bp->b_flags &= ~B_CACHE; 2897 bp->b_pages[bp->b_npages] = m; 2898 ++bp->b_npages; 2899 } 2900 continue; 2901 } 2902 2903 /* 2904 * We found a page. If we have to sleep on it, 2905 * retry because it might have gotten freed out 2906 * from under us. 2907 * 2908 * We can only test VPO_BUSY here. Blocking on 2909 * m->busy might lead to a deadlock: 2910 * 2911 * vm_fault->getpages->cluster_read->allocbuf 2912 * 2913 */ 2914 vm_page_lock_queues(); 2915 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2916 continue; 2917 2918 /* 2919 * We have a good page. Should we wakeup the 2920 * page daemon? 2921 */ 2922 if ((curproc != pageproc) && 2923 (VM_PAGE_INQUEUE1(m, PQ_CACHE)) && 2924 ((cnt.v_free_count + cnt.v_cache_count) < 2925 (cnt.v_free_min + cnt.v_cache_min))) { 2926 pagedaemon_wakeup(); 2927 } 2928 vm_page_wire(m); 2929 vm_page_unlock_queues(); 2930 bp->b_pages[bp->b_npages] = m; 2931 ++bp->b_npages; 2932 } 2933 2934 /* 2935 * Step 2. We've loaded the pages into the buffer, 2936 * we have to figure out if we can still have B_CACHE 2937 * set. Note that B_CACHE is set according to the 2938 * byte-granular range ( bcount and size ), new the 2939 * aligned range ( newbsize ). 2940 * 2941 * The VM test is against m->valid, which is DEV_BSIZE 2942 * aligned. Needless to say, the validity of the data 2943 * needs to also be DEV_BSIZE aligned. Note that this 2944 * fails with NFS if the server or some other client 2945 * extends the file's EOF. If our buffer is resized, 2946 * B_CACHE may remain set! XXX 2947 */ 2948 2949 toff = bp->b_bcount; 2950 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2951 2952 while ((bp->b_flags & B_CACHE) && toff < size) { 2953 vm_pindex_t pi; 2954 2955 if (tinc > (size - toff)) 2956 tinc = size - toff; 2957 2958 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2959 PAGE_SHIFT; 2960 2961 vfs_buf_test_cache( 2962 bp, 2963 bp->b_offset, 2964 toff, 2965 tinc, 2966 bp->b_pages[pi] 2967 ); 2968 toff += tinc; 2969 tinc = PAGE_SIZE; 2970 } 2971 VM_OBJECT_UNLOCK(obj); 2972 2973 /* 2974 * Step 3, fixup the KVM pmap. Remember that 2975 * bp->b_data is relative to bp->b_offset, but 2976 * bp->b_offset may be offset into the first page. 2977 */ 2978 2979 bp->b_data = (caddr_t) 2980 trunc_page((vm_offset_t)bp->b_data); 2981 pmap_qenter( 2982 (vm_offset_t)bp->b_data, 2983 bp->b_pages, 2984 bp->b_npages 2985 ); 2986 2987 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2988 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2989 } 2990 } 2991 if (newbsize < bp->b_bufsize) 2992 bufspacewakeup(); 2993 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2994 bp->b_bcount = size; /* requested buffer size */ 2995 return 1; 2996 } 2997 2998 void 2999 biodone(struct bio *bp) 3000 { 3001 void (*done)(struct bio *); 3002 3003 mtx_lock(&bdonelock); 3004 bp->bio_flags |= BIO_DONE; 3005 done = bp->bio_done; 3006 if (done == NULL) 3007 wakeup(bp); 3008 mtx_unlock(&bdonelock); 3009 if (done != NULL) 3010 done(bp); 3011 } 3012 3013 /* 3014 * Wait for a BIO to finish. 3015 * 3016 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3017 * case is not yet clear. 3018 */ 3019 int 3020 biowait(struct bio *bp, const char *wchan) 3021 { 3022 3023 mtx_lock(&bdonelock); 3024 while ((bp->bio_flags & BIO_DONE) == 0) 3025 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3026 mtx_unlock(&bdonelock); 3027 if (bp->bio_error != 0) 3028 return (bp->bio_error); 3029 if (!(bp->bio_flags & BIO_ERROR)) 3030 return (0); 3031 return (EIO); 3032 } 3033 3034 void 3035 biofinish(struct bio *bp, struct devstat *stat, int error) 3036 { 3037 3038 if (error) { 3039 bp->bio_error = error; 3040 bp->bio_flags |= BIO_ERROR; 3041 } 3042 if (stat != NULL) 3043 devstat_end_transaction_bio(stat, bp); 3044 biodone(bp); 3045 } 3046 3047 /* 3048 * bufwait: 3049 * 3050 * Wait for buffer I/O completion, returning error status. The buffer 3051 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3052 * error and cleared. 3053 */ 3054 int 3055 bufwait(struct buf *bp) 3056 { 3057 if (bp->b_iocmd == BIO_READ) 3058 bwait(bp, PRIBIO, "biord"); 3059 else 3060 bwait(bp, PRIBIO, "biowr"); 3061 if (bp->b_flags & B_EINTR) { 3062 bp->b_flags &= ~B_EINTR; 3063 return (EINTR); 3064 } 3065 if (bp->b_ioflags & BIO_ERROR) { 3066 return (bp->b_error ? bp->b_error : EIO); 3067 } else { 3068 return (0); 3069 } 3070 } 3071 3072 /* 3073 * Call back function from struct bio back up to struct buf. 3074 */ 3075 static void 3076 bufdonebio(struct bio *bip) 3077 { 3078 struct buf *bp; 3079 3080 bp = bip->bio_caller2; 3081 bp->b_resid = bp->b_bcount - bip->bio_completed; 3082 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3083 bp->b_ioflags = bip->bio_flags; 3084 bp->b_error = bip->bio_error; 3085 if (bp->b_error) 3086 bp->b_ioflags |= BIO_ERROR; 3087 bufdone(bp); 3088 g_destroy_bio(bip); 3089 } 3090 3091 void 3092 dev_strategy(struct cdev *dev, struct buf *bp) 3093 { 3094 struct cdevsw *csw; 3095 struct bio *bip; 3096 3097 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3098 panic("b_iocmd botch"); 3099 for (;;) { 3100 bip = g_new_bio(); 3101 if (bip != NULL) 3102 break; 3103 /* Try again later */ 3104 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3105 } 3106 bip->bio_cmd = bp->b_iocmd; 3107 bip->bio_offset = bp->b_iooffset; 3108 bip->bio_length = bp->b_bcount; 3109 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3110 bip->bio_data = bp->b_data; 3111 bip->bio_done = bufdonebio; 3112 bip->bio_caller2 = bp; 3113 bip->bio_dev = dev; 3114 KASSERT(dev->si_refcount > 0, 3115 ("dev_strategy on un-referenced struct cdev *(%s)", 3116 devtoname(dev))); 3117 csw = dev_refthread(dev); 3118 if (csw == NULL) { 3119 g_destroy_bio(bip); 3120 bp->b_error = ENXIO; 3121 bp->b_ioflags = BIO_ERROR; 3122 bufdone(bp); 3123 return; 3124 } 3125 (*csw->d_strategy)(bip); 3126 dev_relthread(dev); 3127 } 3128 3129 /* 3130 * bufdone: 3131 * 3132 * Finish I/O on a buffer, optionally calling a completion function. 3133 * This is usually called from an interrupt so process blocking is 3134 * not allowed. 3135 * 3136 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3137 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3138 * assuming B_INVAL is clear. 3139 * 3140 * For the VMIO case, we set B_CACHE if the op was a read and no 3141 * read error occured, or if the op was a write. B_CACHE is never 3142 * set if the buffer is invalid or otherwise uncacheable. 3143 * 3144 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3145 * initiator to leave B_INVAL set to brelse the buffer out of existance 3146 * in the biodone routine. 3147 */ 3148 void 3149 bufdone(struct buf *bp) 3150 { 3151 struct bufobj *dropobj; 3152 void (*biodone)(struct buf *); 3153 3154 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3155 dropobj = NULL; 3156 3157 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3158 BUF_REFCNT(bp))); 3159 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3160 3161 runningbufwakeup(bp); 3162 if (bp->b_iocmd == BIO_WRITE) 3163 dropobj = bp->b_bufobj; 3164 /* call optional completion function if requested */ 3165 if (bp->b_iodone != NULL) { 3166 biodone = bp->b_iodone; 3167 bp->b_iodone = NULL; 3168 (*biodone) (bp); 3169 if (dropobj) 3170 bufobj_wdrop(dropobj); 3171 return; 3172 } 3173 3174 bufdone_finish(bp); 3175 3176 if (dropobj) 3177 bufobj_wdrop(dropobj); 3178 } 3179 3180 void 3181 bufdone_finish(struct buf *bp) 3182 { 3183 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3184 BUF_REFCNT(bp))); 3185 3186 if (LIST_FIRST(&bp->b_dep) != NULL) 3187 buf_complete(bp); 3188 3189 if (bp->b_flags & B_VMIO) { 3190 int i; 3191 vm_ooffset_t foff; 3192 vm_page_t m; 3193 vm_object_t obj; 3194 int iosize; 3195 struct vnode *vp = bp->b_vp; 3196 boolean_t are_queues_locked; 3197 3198 obj = bp->b_bufobj->bo_object; 3199 3200 #if defined(VFS_BIO_DEBUG) 3201 mp_fixme("usecount and vflag accessed without locks."); 3202 if (vp->v_usecount == 0) { 3203 panic("biodone: zero vnode ref count"); 3204 } 3205 3206 KASSERT(vp->v_object != NULL, 3207 ("biodone: vnode %p has no vm_object", vp)); 3208 #endif 3209 3210 foff = bp->b_offset; 3211 KASSERT(bp->b_offset != NOOFFSET, 3212 ("biodone: no buffer offset")); 3213 3214 VM_OBJECT_LOCK(obj); 3215 #if defined(VFS_BIO_DEBUG) 3216 if (obj->paging_in_progress < bp->b_npages) { 3217 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3218 obj->paging_in_progress, bp->b_npages); 3219 } 3220 #endif 3221 3222 /* 3223 * Set B_CACHE if the op was a normal read and no error 3224 * occured. B_CACHE is set for writes in the b*write() 3225 * routines. 3226 */ 3227 iosize = bp->b_bcount - bp->b_resid; 3228 if (bp->b_iocmd == BIO_READ && 3229 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3230 !(bp->b_ioflags & BIO_ERROR)) { 3231 bp->b_flags |= B_CACHE; 3232 } 3233 if (bp->b_iocmd == BIO_READ) { 3234 vm_page_lock_queues(); 3235 are_queues_locked = TRUE; 3236 } else 3237 are_queues_locked = FALSE; 3238 for (i = 0; i < bp->b_npages; i++) { 3239 int bogusflag = 0; 3240 int resid; 3241 3242 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3243 if (resid > iosize) 3244 resid = iosize; 3245 3246 /* 3247 * cleanup bogus pages, restoring the originals 3248 */ 3249 m = bp->b_pages[i]; 3250 if (m == bogus_page) { 3251 bogusflag = 1; 3252 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3253 if (m == NULL) 3254 panic("biodone: page disappeared!"); 3255 bp->b_pages[i] = m; 3256 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3257 bp->b_pages, bp->b_npages); 3258 } 3259 #if defined(VFS_BIO_DEBUG) 3260 if (OFF_TO_IDX(foff) != m->pindex) { 3261 printf( 3262 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3263 (intmax_t)foff, (uintmax_t)m->pindex); 3264 } 3265 #endif 3266 3267 /* 3268 * In the write case, the valid and clean bits are 3269 * already changed correctly ( see bdwrite() ), so we 3270 * only need to do this here in the read case. 3271 */ 3272 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3273 vfs_page_set_valid(bp, foff, i, m); 3274 } 3275 3276 /* 3277 * when debugging new filesystems or buffer I/O methods, this 3278 * is the most common error that pops up. if you see this, you 3279 * have not set the page busy flag correctly!!! 3280 */ 3281 if (m->busy == 0) { 3282 printf("biodone: page busy < 0, " 3283 "pindex: %d, foff: 0x(%x,%x), " 3284 "resid: %d, index: %d\n", 3285 (int) m->pindex, (int)(foff >> 32), 3286 (int) foff & 0xffffffff, resid, i); 3287 if (!vn_isdisk(vp, NULL)) 3288 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3289 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3290 (intmax_t) bp->b_lblkno, 3291 bp->b_flags, bp->b_npages); 3292 else 3293 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3294 (intmax_t) bp->b_lblkno, 3295 bp->b_flags, bp->b_npages); 3296 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3297 (u_long)m->valid, (u_long)m->dirty, 3298 m->wire_count); 3299 panic("biodone: page busy < 0\n"); 3300 } 3301 vm_page_io_finish(m); 3302 vm_object_pip_subtract(obj, 1); 3303 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3304 iosize -= resid; 3305 } 3306 if (are_queues_locked) 3307 vm_page_unlock_queues(); 3308 vm_object_pip_wakeupn(obj, 0); 3309 VM_OBJECT_UNLOCK(obj); 3310 } 3311 3312 /* 3313 * For asynchronous completions, release the buffer now. The brelse 3314 * will do a wakeup there if necessary - so no need to do a wakeup 3315 * here in the async case. The sync case always needs to do a wakeup. 3316 */ 3317 3318 if (bp->b_flags & B_ASYNC) { 3319 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3320 brelse(bp); 3321 else 3322 bqrelse(bp); 3323 } else 3324 bdone(bp); 3325 } 3326 3327 /* 3328 * This routine is called in lieu of iodone in the case of 3329 * incomplete I/O. This keeps the busy status for pages 3330 * consistant. 3331 */ 3332 void 3333 vfs_unbusy_pages(struct buf *bp) 3334 { 3335 int i; 3336 vm_object_t obj; 3337 vm_page_t m; 3338 3339 runningbufwakeup(bp); 3340 if (!(bp->b_flags & B_VMIO)) 3341 return; 3342 3343 obj = bp->b_bufobj->bo_object; 3344 VM_OBJECT_LOCK(obj); 3345 for (i = 0; i < bp->b_npages; i++) { 3346 m = bp->b_pages[i]; 3347 if (m == bogus_page) { 3348 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3349 if (!m) 3350 panic("vfs_unbusy_pages: page missing\n"); 3351 bp->b_pages[i] = m; 3352 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3353 bp->b_pages, bp->b_npages); 3354 } 3355 vm_object_pip_subtract(obj, 1); 3356 vm_page_io_finish(m); 3357 } 3358 vm_object_pip_wakeupn(obj, 0); 3359 VM_OBJECT_UNLOCK(obj); 3360 } 3361 3362 /* 3363 * vfs_page_set_valid: 3364 * 3365 * Set the valid bits in a page based on the supplied offset. The 3366 * range is restricted to the buffer's size. 3367 * 3368 * This routine is typically called after a read completes. 3369 */ 3370 static void 3371 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) 3372 { 3373 vm_ooffset_t soff, eoff; 3374 3375 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3376 /* 3377 * Start and end offsets in buffer. eoff - soff may not cross a 3378 * page boundry or cross the end of the buffer. The end of the 3379 * buffer, in this case, is our file EOF, not the allocation size 3380 * of the buffer. 3381 */ 3382 soff = off; 3383 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3384 if (eoff > bp->b_offset + bp->b_bcount) 3385 eoff = bp->b_offset + bp->b_bcount; 3386 3387 /* 3388 * Set valid range. This is typically the entire buffer and thus the 3389 * entire page. 3390 */ 3391 if (eoff > soff) { 3392 vm_page_set_validclean( 3393 m, 3394 (vm_offset_t) (soff & PAGE_MASK), 3395 (vm_offset_t) (eoff - soff) 3396 ); 3397 } 3398 } 3399 3400 /* 3401 * This routine is called before a device strategy routine. 3402 * It is used to tell the VM system that paging I/O is in 3403 * progress, and treat the pages associated with the buffer 3404 * almost as being VPO_BUSY. Also the object paging_in_progress 3405 * flag is handled to make sure that the object doesn't become 3406 * inconsistant. 3407 * 3408 * Since I/O has not been initiated yet, certain buffer flags 3409 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3410 * and should be ignored. 3411 */ 3412 void 3413 vfs_busy_pages(struct buf *bp, int clear_modify) 3414 { 3415 int i, bogus; 3416 vm_object_t obj; 3417 vm_ooffset_t foff; 3418 vm_page_t m; 3419 3420 if (!(bp->b_flags & B_VMIO)) 3421 return; 3422 3423 obj = bp->b_bufobj->bo_object; 3424 foff = bp->b_offset; 3425 KASSERT(bp->b_offset != NOOFFSET, 3426 ("vfs_busy_pages: no buffer offset")); 3427 VM_OBJECT_LOCK(obj); 3428 if (bp->b_bufsize != 0) 3429 vfs_setdirty_locked_object(bp); 3430 retry: 3431 for (i = 0; i < bp->b_npages; i++) { 3432 m = bp->b_pages[i]; 3433 3434 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3435 goto retry; 3436 } 3437 bogus = 0; 3438 vm_page_lock_queues(); 3439 for (i = 0; i < bp->b_npages; i++) { 3440 m = bp->b_pages[i]; 3441 3442 if ((bp->b_flags & B_CLUSTER) == 0) { 3443 vm_object_pip_add(obj, 1); 3444 vm_page_io_start(m); 3445 } 3446 /* 3447 * When readying a buffer for a read ( i.e 3448 * clear_modify == 0 ), it is important to do 3449 * bogus_page replacement for valid pages in 3450 * partially instantiated buffers. Partially 3451 * instantiated buffers can, in turn, occur when 3452 * reconstituting a buffer from its VM backing store 3453 * base. We only have to do this if B_CACHE is 3454 * clear ( which causes the I/O to occur in the 3455 * first place ). The replacement prevents the read 3456 * I/O from overwriting potentially dirty VM-backed 3457 * pages. XXX bogus page replacement is, uh, bogus. 3458 * It may not work properly with small-block devices. 3459 * We need to find a better way. 3460 */ 3461 pmap_remove_all(m); 3462 if (clear_modify) 3463 vfs_page_set_valid(bp, foff, i, m); 3464 else if (m->valid == VM_PAGE_BITS_ALL && 3465 (bp->b_flags & B_CACHE) == 0) { 3466 bp->b_pages[i] = bogus_page; 3467 bogus++; 3468 } 3469 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3470 } 3471 vm_page_unlock_queues(); 3472 VM_OBJECT_UNLOCK(obj); 3473 if (bogus) 3474 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3475 bp->b_pages, bp->b_npages); 3476 } 3477 3478 /* 3479 * Tell the VM system that the pages associated with this buffer 3480 * are clean. This is used for delayed writes where the data is 3481 * going to go to disk eventually without additional VM intevention. 3482 * 3483 * Note that while we only really need to clean through to b_bcount, we 3484 * just go ahead and clean through to b_bufsize. 3485 */ 3486 static void 3487 vfs_clean_pages(struct buf *bp) 3488 { 3489 int i; 3490 vm_ooffset_t foff, noff, eoff; 3491 vm_page_t m; 3492 3493 if (!(bp->b_flags & B_VMIO)) 3494 return; 3495 3496 foff = bp->b_offset; 3497 KASSERT(bp->b_offset != NOOFFSET, 3498 ("vfs_clean_pages: no buffer offset")); 3499 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3500 vm_page_lock_queues(); 3501 for (i = 0; i < bp->b_npages; i++) { 3502 m = bp->b_pages[i]; 3503 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3504 eoff = noff; 3505 3506 if (eoff > bp->b_offset + bp->b_bufsize) 3507 eoff = bp->b_offset + bp->b_bufsize; 3508 vfs_page_set_valid(bp, foff, i, m); 3509 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3510 foff = noff; 3511 } 3512 vm_page_unlock_queues(); 3513 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3514 } 3515 3516 /* 3517 * vfs_bio_set_validclean: 3518 * 3519 * Set the range within the buffer to valid and clean. The range is 3520 * relative to the beginning of the buffer, b_offset. Note that b_offset 3521 * itself may be offset from the beginning of the first page. 3522 * 3523 */ 3524 3525 void 3526 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3527 { 3528 int i, n; 3529 vm_page_t m; 3530 3531 if (!(bp->b_flags & B_VMIO)) 3532 return; 3533 /* 3534 * Fixup base to be relative to beginning of first page. 3535 * Set initial n to be the maximum number of bytes in the 3536 * first page that can be validated. 3537 */ 3538 3539 base += (bp->b_offset & PAGE_MASK); 3540 n = PAGE_SIZE - (base & PAGE_MASK); 3541 3542 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3543 vm_page_lock_queues(); 3544 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3545 m = bp->b_pages[i]; 3546 if (n > size) 3547 n = size; 3548 vm_page_set_validclean(m, base & PAGE_MASK, n); 3549 base += n; 3550 size -= n; 3551 n = PAGE_SIZE; 3552 } 3553 vm_page_unlock_queues(); 3554 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3555 } 3556 3557 /* 3558 * vfs_bio_clrbuf: 3559 * 3560 * clear a buffer. This routine essentially fakes an I/O, so we need 3561 * to clear BIO_ERROR and B_INVAL. 3562 * 3563 * Note that while we only theoretically need to clear through b_bcount, 3564 * we go ahead and clear through b_bufsize. 3565 */ 3566 3567 void 3568 vfs_bio_clrbuf(struct buf *bp) 3569 { 3570 int i, j, mask = 0; 3571 caddr_t sa, ea; 3572 3573 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3574 clrbuf(bp); 3575 return; 3576 } 3577 3578 bp->b_flags &= ~B_INVAL; 3579 bp->b_ioflags &= ~BIO_ERROR; 3580 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3581 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3582 (bp->b_offset & PAGE_MASK) == 0) { 3583 if (bp->b_pages[0] == bogus_page) 3584 goto unlock; 3585 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3586 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3587 if ((bp->b_pages[0]->valid & mask) == mask) 3588 goto unlock; 3589 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3590 ((bp->b_pages[0]->valid & mask) == 0)) { 3591 bzero(bp->b_data, bp->b_bufsize); 3592 bp->b_pages[0]->valid |= mask; 3593 goto unlock; 3594 } 3595 } 3596 ea = sa = bp->b_data; 3597 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3598 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3599 ea = (caddr_t)(vm_offset_t)ulmin( 3600 (u_long)(vm_offset_t)ea, 3601 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3602 if (bp->b_pages[i] == bogus_page) 3603 continue; 3604 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3605 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3606 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3607 if ((bp->b_pages[i]->valid & mask) == mask) 3608 continue; 3609 if ((bp->b_pages[i]->valid & mask) == 0) { 3610 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3611 bzero(sa, ea - sa); 3612 } else { 3613 for (; sa < ea; sa += DEV_BSIZE, j++) { 3614 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3615 (bp->b_pages[i]->valid & (1 << j)) == 0) 3616 bzero(sa, DEV_BSIZE); 3617 } 3618 } 3619 bp->b_pages[i]->valid |= mask; 3620 } 3621 unlock: 3622 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3623 bp->b_resid = 0; 3624 } 3625 3626 /* 3627 * vm_hold_load_pages and vm_hold_free_pages get pages into 3628 * a buffers address space. The pages are anonymous and are 3629 * not associated with a file object. 3630 */ 3631 static void 3632 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3633 { 3634 vm_offset_t pg; 3635 vm_page_t p; 3636 int index; 3637 3638 to = round_page(to); 3639 from = round_page(from); 3640 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3641 3642 VM_OBJECT_LOCK(kernel_object); 3643 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3644 tryagain: 3645 /* 3646 * note: must allocate system pages since blocking here 3647 * could intefere with paging I/O, no matter which 3648 * process we are. 3649 */ 3650 p = vm_page_alloc(kernel_object, 3651 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3652 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3653 if (!p) { 3654 atomic_add_int(&vm_pageout_deficit, 3655 (to - pg) >> PAGE_SHIFT); 3656 VM_OBJECT_UNLOCK(kernel_object); 3657 VM_WAIT; 3658 VM_OBJECT_LOCK(kernel_object); 3659 goto tryagain; 3660 } 3661 p->valid = VM_PAGE_BITS_ALL; 3662 pmap_qenter(pg, &p, 1); 3663 bp->b_pages[index] = p; 3664 } 3665 VM_OBJECT_UNLOCK(kernel_object); 3666 bp->b_npages = index; 3667 } 3668 3669 /* Return pages associated with this buf to the vm system */ 3670 static void 3671 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3672 { 3673 vm_offset_t pg; 3674 vm_page_t p; 3675 int index, newnpages; 3676 3677 from = round_page(from); 3678 to = round_page(to); 3679 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3680 3681 VM_OBJECT_LOCK(kernel_object); 3682 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3683 p = bp->b_pages[index]; 3684 if (p && (index < bp->b_npages)) { 3685 if (p->busy) { 3686 printf( 3687 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3688 (intmax_t)bp->b_blkno, 3689 (intmax_t)bp->b_lblkno); 3690 } 3691 bp->b_pages[index] = NULL; 3692 pmap_qremove(pg, 1); 3693 vm_page_lock_queues(); 3694 vm_page_unwire(p, 0); 3695 vm_page_free(p); 3696 vm_page_unlock_queues(); 3697 } 3698 } 3699 VM_OBJECT_UNLOCK(kernel_object); 3700 bp->b_npages = newnpages; 3701 } 3702 3703 /* 3704 * Map an IO request into kernel virtual address space. 3705 * 3706 * All requests are (re)mapped into kernel VA space. 3707 * Notice that we use b_bufsize for the size of the buffer 3708 * to be mapped. b_bcount might be modified by the driver. 3709 * 3710 * Note that even if the caller determines that the address space should 3711 * be valid, a race or a smaller-file mapped into a larger space may 3712 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3713 * check the return value. 3714 */ 3715 int 3716 vmapbuf(struct buf *bp) 3717 { 3718 caddr_t addr, kva; 3719 vm_prot_t prot; 3720 int pidx, i; 3721 struct vm_page *m; 3722 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3723 3724 if (bp->b_bufsize < 0) 3725 return (-1); 3726 prot = VM_PROT_READ; 3727 if (bp->b_iocmd == BIO_READ) 3728 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3729 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3730 addr < bp->b_data + bp->b_bufsize; 3731 addr += PAGE_SIZE, pidx++) { 3732 /* 3733 * Do the vm_fault if needed; do the copy-on-write thing 3734 * when reading stuff off device into memory. 3735 * 3736 * NOTE! Must use pmap_extract() because addr may be in 3737 * the userland address space, and kextract is only guarenteed 3738 * to work for the kernland address space (see: sparc64 port). 3739 */ 3740 retry: 3741 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3742 prot) < 0) { 3743 vm_page_lock_queues(); 3744 for (i = 0; i < pidx; ++i) { 3745 vm_page_unhold(bp->b_pages[i]); 3746 bp->b_pages[i] = NULL; 3747 } 3748 vm_page_unlock_queues(); 3749 return(-1); 3750 } 3751 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3752 if (m == NULL) 3753 goto retry; 3754 bp->b_pages[pidx] = m; 3755 } 3756 if (pidx > btoc(MAXPHYS)) 3757 panic("vmapbuf: mapped more than MAXPHYS"); 3758 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3759 3760 kva = bp->b_saveaddr; 3761 bp->b_npages = pidx; 3762 bp->b_saveaddr = bp->b_data; 3763 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3764 return(0); 3765 } 3766 3767 /* 3768 * Free the io map PTEs associated with this IO operation. 3769 * We also invalidate the TLB entries and restore the original b_addr. 3770 */ 3771 void 3772 vunmapbuf(struct buf *bp) 3773 { 3774 int pidx; 3775 int npages; 3776 3777 npages = bp->b_npages; 3778 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3779 vm_page_lock_queues(); 3780 for (pidx = 0; pidx < npages; pidx++) 3781 vm_page_unhold(bp->b_pages[pidx]); 3782 vm_page_unlock_queues(); 3783 3784 bp->b_data = bp->b_saveaddr; 3785 } 3786 3787 void 3788 bdone(struct buf *bp) 3789 { 3790 3791 mtx_lock(&bdonelock); 3792 bp->b_flags |= B_DONE; 3793 wakeup(bp); 3794 mtx_unlock(&bdonelock); 3795 } 3796 3797 void 3798 bwait(struct buf *bp, u_char pri, const char *wchan) 3799 { 3800 3801 mtx_lock(&bdonelock); 3802 while ((bp->b_flags & B_DONE) == 0) 3803 msleep(bp, &bdonelock, pri, wchan, 0); 3804 mtx_unlock(&bdonelock); 3805 } 3806 3807 int 3808 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3809 { 3810 3811 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3812 } 3813 3814 void 3815 bufstrategy(struct bufobj *bo, struct buf *bp) 3816 { 3817 int i = 0; 3818 struct vnode *vp; 3819 3820 vp = bp->b_vp; 3821 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3822 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3823 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3824 i = VOP_STRATEGY(vp, bp); 3825 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3826 } 3827 3828 void 3829 bufobj_wrefl(struct bufobj *bo) 3830 { 3831 3832 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3833 ASSERT_BO_LOCKED(bo); 3834 bo->bo_numoutput++; 3835 } 3836 3837 void 3838 bufobj_wref(struct bufobj *bo) 3839 { 3840 3841 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3842 BO_LOCK(bo); 3843 bo->bo_numoutput++; 3844 BO_UNLOCK(bo); 3845 } 3846 3847 void 3848 bufobj_wdrop(struct bufobj *bo) 3849 { 3850 3851 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3852 BO_LOCK(bo); 3853 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3854 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3855 bo->bo_flag &= ~BO_WWAIT; 3856 wakeup(&bo->bo_numoutput); 3857 } 3858 BO_UNLOCK(bo); 3859 } 3860 3861 int 3862 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3863 { 3864 int error; 3865 3866 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3867 ASSERT_BO_LOCKED(bo); 3868 error = 0; 3869 while (bo->bo_numoutput) { 3870 bo->bo_flag |= BO_WWAIT; 3871 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3872 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3873 if (error) 3874 break; 3875 } 3876 return (error); 3877 } 3878 3879 void 3880 bpin(struct buf *bp) 3881 { 3882 mtx_lock(&bpinlock); 3883 bp->b_pin_count++; 3884 mtx_unlock(&bpinlock); 3885 } 3886 3887 void 3888 bunpin(struct buf *bp) 3889 { 3890 mtx_lock(&bpinlock); 3891 if (--bp->b_pin_count == 0) 3892 wakeup(bp); 3893 mtx_unlock(&bpinlock); 3894 } 3895 3896 void 3897 bunpin_wait(struct buf *bp) 3898 { 3899 mtx_lock(&bpinlock); 3900 while (bp->b_pin_count > 0) 3901 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3902 mtx_unlock(&bpinlock); 3903 } 3904 3905 #include "opt_ddb.h" 3906 #ifdef DDB 3907 #include <ddb/ddb.h> 3908 3909 /* DDB command to show buffer data */ 3910 DB_SHOW_COMMAND(buffer, db_show_buffer) 3911 { 3912 /* get args */ 3913 struct buf *bp = (struct buf *)addr; 3914 3915 if (!have_addr) { 3916 db_printf("usage: show buffer <addr>\n"); 3917 return; 3918 } 3919 3920 db_printf("buf at %p\n", bp); 3921 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3922 db_printf( 3923 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3924 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3925 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3926 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3927 if (bp->b_npages) { 3928 int i; 3929 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3930 for (i = 0; i < bp->b_npages; i++) { 3931 vm_page_t m; 3932 m = bp->b_pages[i]; 3933 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3934 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3935 if ((i + 1) < bp->b_npages) 3936 db_printf(","); 3937 } 3938 db_printf("\n"); 3939 } 3940 lockmgr_printinfo(&bp->b_lock); 3941 } 3942 3943 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3944 { 3945 struct buf *bp; 3946 int i; 3947 3948 for (i = 0; i < nbuf; i++) { 3949 bp = &buf[i]; 3950 if (lockcount(&bp->b_lock)) { 3951 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3952 db_printf("\n"); 3953 } 3954 } 3955 } 3956 #endif /* DDB */ 3957