1 /*- 2 * Copyright (c) 2004 Poul-Henning Kamp 3 * Copyright (c) 1994,1997 John S. Dyson 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 /* 29 * this file contains a new buffer I/O scheme implementing a coherent 30 * VM object and buffer cache scheme. Pains have been taken to make 31 * sure that the performance degradation associated with schemes such 32 * as this is not realized. 33 * 34 * Author: John S. Dyson 35 * Significant help during the development and debugging phases 36 * had been provided by David Greenman, also of the FreeBSD core team. 37 * 38 * see man buf(9) for more info. 39 */ 40 41 #include <sys/cdefs.h> 42 __FBSDID("$FreeBSD$"); 43 44 #include <sys/param.h> 45 #include <sys/systm.h> 46 #include <sys/bio.h> 47 #include <sys/conf.h> 48 #include <sys/buf.h> 49 #include <sys/devicestat.h> 50 #include <sys/eventhandler.h> 51 #include <sys/limits.h> 52 #include <sys/lock.h> 53 #include <sys/malloc.h> 54 #include <sys/mount.h> 55 #include <sys/mutex.h> 56 #include <sys/kernel.h> 57 #include <sys/kthread.h> 58 #include <sys/proc.h> 59 #include <sys/resourcevar.h> 60 #include <sys/sysctl.h> 61 #include <sys/vmmeter.h> 62 #include <sys/vnode.h> 63 #include <geom/geom.h> 64 #include <vm/vm.h> 65 #include <vm/vm_param.h> 66 #include <vm/vm_kern.h> 67 #include <vm/vm_pageout.h> 68 #include <vm/vm_page.h> 69 #include <vm/vm_object.h> 70 #include <vm/vm_extern.h> 71 #include <vm/vm_map.h> 72 #include "opt_directio.h" 73 #include "opt_swap.h" 74 75 static MALLOC_DEFINE(M_BIOBUF, "biobuf", "BIO buffer"); 76 77 struct bio_ops bioops; /* I/O operation notification */ 78 79 struct buf_ops buf_ops_bio = { 80 .bop_name = "buf_ops_bio", 81 .bop_write = bufwrite, 82 .bop_strategy = bufstrategy, 83 .bop_sync = bufsync, 84 .bop_bdflush = bufbdflush, 85 }; 86 87 /* 88 * XXX buf is global because kern_shutdown.c and ffs_checkoverlap has 89 * carnal knowledge of buffers. This knowledge should be moved to vfs_bio.c. 90 */ 91 struct buf *buf; /* buffer header pool */ 92 93 static struct proc *bufdaemonproc; 94 95 static int inmem(struct vnode *vp, daddr_t blkno); 96 static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, 97 vm_offset_t to); 98 static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, 99 vm_offset_t to); 100 static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, 101 vm_page_t m); 102 static void vfs_clean_pages(struct buf *bp); 103 static void vfs_setdirty(struct buf *bp); 104 static void vfs_setdirty_locked_object(struct buf *bp); 105 static void vfs_vmio_release(struct buf *bp); 106 static int vfs_bio_clcheck(struct vnode *vp, int size, 107 daddr_t lblkno, daddr_t blkno); 108 static int flushbufqueues(int, int); 109 static void buf_daemon(void); 110 static void bremfreel(struct buf *bp); 111 112 int vmiodirenable = TRUE; 113 SYSCTL_INT(_vfs, OID_AUTO, vmiodirenable, CTLFLAG_RW, &vmiodirenable, 0, 114 "Use the VM system for directory writes"); 115 int runningbufspace; 116 SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, 117 "Amount of presently outstanding async buffer io"); 118 static int bufspace; 119 SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, 120 "KVA memory used for bufs"); 121 static int maxbufspace; 122 SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, 123 "Maximum allowed value of bufspace (including buf_daemon)"); 124 static int bufmallocspace; 125 SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, 126 "Amount of malloced memory for buffers"); 127 static int maxbufmallocspace; 128 SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RW, &maxbufmallocspace, 0, 129 "Maximum amount of malloced memory for buffers"); 130 static int lobufspace; 131 SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, 132 "Minimum amount of buffers we want to have"); 133 int hibufspace; 134 SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, 135 "Maximum allowed value of bufspace (excluding buf_daemon)"); 136 static int bufreusecnt; 137 SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RW, &bufreusecnt, 0, 138 "Number of times we have reused a buffer"); 139 static int buffreekvacnt; 140 SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RW, &buffreekvacnt, 0, 141 "Number of times we have freed the KVA space from some buffer"); 142 static int bufdefragcnt; 143 SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RW, &bufdefragcnt, 0, 144 "Number of times we have had to repeat buffer allocation to defragment"); 145 static int lorunningspace; 146 SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, 147 "Minimum preferred space used for in-progress I/O"); 148 static int hirunningspace; 149 SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, 150 "Maximum amount of space to use for in-progress I/O"); 151 int dirtybufferflushes; 152 SYSCTL_INT(_vfs, OID_AUTO, dirtybufferflushes, CTLFLAG_RW, &dirtybufferflushes, 153 0, "Number of bdwrite to bawrite conversions to limit dirty buffers"); 154 int bdwriteskip; 155 SYSCTL_INT(_vfs, OID_AUTO, bdwriteskip, CTLFLAG_RW, &bdwriteskip, 156 0, "Number of buffers supplied to bdwrite with snapshot deadlock risk"); 157 int altbufferflushes; 158 SYSCTL_INT(_vfs, OID_AUTO, altbufferflushes, CTLFLAG_RW, &altbufferflushes, 159 0, "Number of fsync flushes to limit dirty buffers"); 160 static int recursiveflushes; 161 SYSCTL_INT(_vfs, OID_AUTO, recursiveflushes, CTLFLAG_RW, &recursiveflushes, 162 0, "Number of flushes skipped due to being recursive"); 163 static int numdirtybuffers; 164 SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, 165 "Number of buffers that are dirty (has unwritten changes) at the moment"); 166 static int lodirtybuffers; 167 SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, 168 "How many buffers we want to have free before bufdaemon can sleep"); 169 static int hidirtybuffers; 170 SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, 171 "When the number of dirty buffers is considered severe"); 172 int dirtybufthresh; 173 SYSCTL_INT(_vfs, OID_AUTO, dirtybufthresh, CTLFLAG_RW, &dirtybufthresh, 174 0, "Number of bdwrite to bawrite conversions to clear dirty buffers"); 175 static int numfreebuffers; 176 SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, 177 "Number of free buffers"); 178 static int lofreebuffers; 179 SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, 180 "XXX Unused"); 181 static int hifreebuffers; 182 SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, 183 "XXX Complicatedly unused"); 184 static int getnewbufcalls; 185 SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RW, &getnewbufcalls, 0, 186 "Number of calls to getnewbuf"); 187 static int getnewbufrestarts; 188 SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RW, &getnewbufrestarts, 0, 189 "Number of times getnewbuf has had to restart a buffer aquisition"); 190 191 /* 192 * Wakeup point for bufdaemon, as well as indicator of whether it is already 193 * active. Set to 1 when the bufdaemon is already "on" the queue, 0 when it 194 * is idling. 195 */ 196 static int bd_request; 197 198 /* 199 * This lock synchronizes access to bd_request. 200 */ 201 static struct mtx bdlock; 202 203 /* 204 * bogus page -- for I/O to/from partially complete buffers 205 * this is a temporary solution to the problem, but it is not 206 * really that bad. it would be better to split the buffer 207 * for input in the case of buffers partially already in memory, 208 * but the code is intricate enough already. 209 */ 210 vm_page_t bogus_page; 211 212 /* 213 * Synchronization (sleep/wakeup) variable for active buffer space requests. 214 * Set when wait starts, cleared prior to wakeup(). 215 * Used in runningbufwakeup() and waitrunningbufspace(). 216 */ 217 static int runningbufreq; 218 219 /* 220 * This lock protects the runningbufreq and synchronizes runningbufwakeup and 221 * waitrunningbufspace(). 222 */ 223 static struct mtx rbreqlock; 224 225 /* 226 * Synchronization (sleep/wakeup) variable for buffer requests. 227 * Can contain the VFS_BIO_NEED flags defined below; setting/clearing is done 228 * by and/or. 229 * Used in numdirtywakeup(), bufspacewakeup(), bufcountwakeup(), bwillwrite(), 230 * getnewbuf(), and getblk(). 231 */ 232 static int needsbuffer; 233 234 /* 235 * Lock that protects needsbuffer and the sleeps/wakeups surrounding it. 236 */ 237 static struct mtx nblock; 238 239 /* 240 * Lock that protects against bwait()/bdone()/B_DONE races. 241 */ 242 243 static struct mtx bdonelock; 244 245 /* 246 * Lock that protects against bwait()/bdone()/B_DONE races. 247 */ 248 static struct mtx bpinlock; 249 250 /* 251 * Definitions for the buffer free lists. 252 */ 253 #define BUFFER_QUEUES 6 /* number of free buffer queues */ 254 255 #define QUEUE_NONE 0 /* on no queue */ 256 #define QUEUE_CLEAN 1 /* non-B_DELWRI buffers */ 257 #define QUEUE_DIRTY 2 /* B_DELWRI buffers */ 258 #define QUEUE_DIRTY_GIANT 3 /* B_DELWRI buffers that need giant */ 259 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */ 260 #define QUEUE_EMPTY 5 /* empty buffer headers */ 261 262 /* Queues for free buffers with various properties */ 263 static TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES] = { { 0 } }; 264 265 /* Lock for the bufqueues */ 266 static struct mtx bqlock; 267 268 /* 269 * Single global constant for BUF_WMESG, to avoid getting multiple references. 270 * buf_wmesg is referred from macros. 271 */ 272 const char *buf_wmesg = BUF_WMESG; 273 274 #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ 275 #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ 276 #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ 277 #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ 278 279 #ifdef DIRECTIO 280 extern void ffs_rawread_setup(void); 281 #endif /* DIRECTIO */ 282 /* 283 * numdirtywakeup: 284 * 285 * If someone is blocked due to there being too many dirty buffers, 286 * and numdirtybuffers is now reasonable, wake them up. 287 */ 288 289 static __inline void 290 numdirtywakeup(int level) 291 { 292 293 if (numdirtybuffers <= level) { 294 mtx_lock(&nblock); 295 if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { 296 needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; 297 wakeup(&needsbuffer); 298 } 299 mtx_unlock(&nblock); 300 } 301 } 302 303 /* 304 * bufspacewakeup: 305 * 306 * Called when buffer space is potentially available for recovery. 307 * getnewbuf() will block on this flag when it is unable to free 308 * sufficient buffer space. Buffer space becomes recoverable when 309 * bp's get placed back in the queues. 310 */ 311 312 static __inline void 313 bufspacewakeup(void) 314 { 315 316 /* 317 * If someone is waiting for BUF space, wake them up. Even 318 * though we haven't freed the kva space yet, the waiting 319 * process will be able to now. 320 */ 321 mtx_lock(&nblock); 322 if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { 323 needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; 324 wakeup(&needsbuffer); 325 } 326 mtx_unlock(&nblock); 327 } 328 329 /* 330 * runningbufwakeup() - in-progress I/O accounting. 331 * 332 */ 333 void 334 runningbufwakeup(struct buf *bp) 335 { 336 337 if (bp->b_runningbufspace) { 338 atomic_subtract_int(&runningbufspace, bp->b_runningbufspace); 339 bp->b_runningbufspace = 0; 340 mtx_lock(&rbreqlock); 341 if (runningbufreq && runningbufspace <= lorunningspace) { 342 runningbufreq = 0; 343 wakeup(&runningbufreq); 344 } 345 mtx_unlock(&rbreqlock); 346 } 347 } 348 349 /* 350 * bufcountwakeup: 351 * 352 * Called when a buffer has been added to one of the free queues to 353 * account for the buffer and to wakeup anyone waiting for free buffers. 354 * This typically occurs when large amounts of metadata are being handled 355 * by the buffer cache ( else buffer space runs out first, usually ). 356 */ 357 358 static __inline void 359 bufcountwakeup(void) 360 { 361 362 atomic_add_int(&numfreebuffers, 1); 363 mtx_lock(&nblock); 364 if (needsbuffer) { 365 needsbuffer &= ~VFS_BIO_NEED_ANY; 366 if (numfreebuffers >= hifreebuffers) 367 needsbuffer &= ~VFS_BIO_NEED_FREE; 368 wakeup(&needsbuffer); 369 } 370 mtx_unlock(&nblock); 371 } 372 373 /* 374 * waitrunningbufspace() 375 * 376 * runningbufspace is a measure of the amount of I/O currently 377 * running. This routine is used in async-write situations to 378 * prevent creating huge backups of pending writes to a device. 379 * Only asynchronous writes are governed by this function. 380 * 381 * Reads will adjust runningbufspace, but will not block based on it. 382 * The read load has a side effect of reducing the allowed write load. 383 * 384 * This does NOT turn an async write into a sync write. It waits 385 * for earlier writes to complete and generally returns before the 386 * caller's write has reached the device. 387 */ 388 void 389 waitrunningbufspace(void) 390 { 391 392 mtx_lock(&rbreqlock); 393 while (runningbufspace > hirunningspace) { 394 ++runningbufreq; 395 msleep(&runningbufreq, &rbreqlock, PVM, "wdrain", 0); 396 } 397 mtx_unlock(&rbreqlock); 398 } 399 400 401 /* 402 * vfs_buf_test_cache: 403 * 404 * Called when a buffer is extended. This function clears the B_CACHE 405 * bit if the newly extended portion of the buffer does not contain 406 * valid data. 407 */ 408 static __inline 409 void 410 vfs_buf_test_cache(struct buf *bp, 411 vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, 412 vm_page_t m) 413 { 414 415 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 416 if (bp->b_flags & B_CACHE) { 417 int base = (foff + off) & PAGE_MASK; 418 if (vm_page_is_valid(m, base, size) == 0) 419 bp->b_flags &= ~B_CACHE; 420 } 421 } 422 423 /* Wake up the buffer daemon if necessary */ 424 static __inline 425 void 426 bd_wakeup(int dirtybuflevel) 427 { 428 429 mtx_lock(&bdlock); 430 if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { 431 bd_request = 1; 432 wakeup(&bd_request); 433 } 434 mtx_unlock(&bdlock); 435 } 436 437 /* 438 * bd_speedup - speedup the buffer cache flushing code 439 */ 440 441 static __inline 442 void 443 bd_speedup(void) 444 { 445 446 bd_wakeup(1); 447 } 448 449 /* 450 * Calculating buffer cache scaling values and reserve space for buffer 451 * headers. This is called during low level kernel initialization and 452 * may be called more then once. We CANNOT write to the memory area 453 * being reserved at this time. 454 */ 455 caddr_t 456 kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est) 457 { 458 int maxbuf; 459 460 /* 461 * physmem_est is in pages. Convert it to kilobytes (assumes 462 * PAGE_SIZE is >= 1K) 463 */ 464 physmem_est = physmem_est * (PAGE_SIZE / 1024); 465 466 /* 467 * The nominal buffer size (and minimum KVA allocation) is BKVASIZE. 468 * For the first 64MB of ram nominally allocate sufficient buffers to 469 * cover 1/4 of our ram. Beyond the first 64MB allocate additional 470 * buffers to cover 1/10 of our ram over 64MB. When auto-sizing 471 * the buffer cache we limit the eventual kva reservation to 472 * maxbcache bytes. 473 * 474 * factor represents the 1/4 x ram conversion. 475 */ 476 if (nbuf == 0) { 477 int factor = 4 * BKVASIZE / 1024; 478 479 nbuf = 50; 480 if (physmem_est > 4096) 481 nbuf += min((physmem_est - 4096) / factor, 482 65536 / factor); 483 if (physmem_est > 65536) 484 nbuf += (physmem_est - 65536) * 2 / (factor * 5); 485 486 if (maxbcache && nbuf > maxbcache / BKVASIZE) 487 nbuf = maxbcache / BKVASIZE; 488 489 /* XXX Avoid integer overflows later on with maxbufspace. */ 490 maxbuf = (INT_MAX / 3) / BKVASIZE; 491 if (nbuf > maxbuf) 492 nbuf = maxbuf; 493 } 494 495 #if 0 496 /* 497 * Do not allow the buffer_map to be more then 1/2 the size of the 498 * kernel_map. 499 */ 500 if (nbuf > (kernel_map->max_offset - kernel_map->min_offset) / 501 (BKVASIZE * 2)) { 502 nbuf = (kernel_map->max_offset - kernel_map->min_offset) / 503 (BKVASIZE * 2); 504 printf("Warning: nbufs capped at %d\n", nbuf); 505 } 506 #endif 507 508 /* 509 * swbufs are used as temporary holders for I/O, such as paging I/O. 510 * We have no less then 16 and no more then 256. 511 */ 512 nswbuf = max(min(nbuf/4, 256), 16); 513 #ifdef NSWBUF_MIN 514 if (nswbuf < NSWBUF_MIN) 515 nswbuf = NSWBUF_MIN; 516 #endif 517 #ifdef DIRECTIO 518 ffs_rawread_setup(); 519 #endif 520 521 /* 522 * Reserve space for the buffer cache buffers 523 */ 524 swbuf = (void *)v; 525 v = (caddr_t)(swbuf + nswbuf); 526 buf = (void *)v; 527 v = (caddr_t)(buf + nbuf); 528 529 return(v); 530 } 531 532 /* Initialize the buffer subsystem. Called before use of any buffers. */ 533 void 534 bufinit(void) 535 { 536 struct buf *bp; 537 int i; 538 539 mtx_init(&bqlock, "buf queue lock", NULL, MTX_DEF); 540 mtx_init(&rbreqlock, "runningbufspace lock", NULL, MTX_DEF); 541 mtx_init(&nblock, "needsbuffer lock", NULL, MTX_DEF); 542 mtx_init(&bdlock, "buffer daemon lock", NULL, MTX_DEF); 543 mtx_init(&bdonelock, "bdone lock", NULL, MTX_DEF); 544 mtx_init(&bpinlock, "bpin lock", NULL, MTX_DEF); 545 546 /* next, make a null set of free lists */ 547 for (i = 0; i < BUFFER_QUEUES; i++) 548 TAILQ_INIT(&bufqueues[i]); 549 550 /* finally, initialize each buffer header and stick on empty q */ 551 for (i = 0; i < nbuf; i++) { 552 bp = &buf[i]; 553 bzero(bp, sizeof *bp); 554 bp->b_flags = B_INVAL; /* we're just an empty header */ 555 bp->b_rcred = NOCRED; 556 bp->b_wcred = NOCRED; 557 bp->b_qindex = QUEUE_EMPTY; 558 bp->b_vflags = 0; 559 bp->b_xflags = 0; 560 LIST_INIT(&bp->b_dep); 561 BUF_LOCKINIT(bp); 562 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_EMPTY], bp, b_freelist); 563 } 564 565 /* 566 * maxbufspace is the absolute maximum amount of buffer space we are 567 * allowed to reserve in KVM and in real terms. The absolute maximum 568 * is nominally used by buf_daemon. hibufspace is the nominal maximum 569 * used by most other processes. The differential is required to 570 * ensure that buf_daemon is able to run when other processes might 571 * be blocked waiting for buffer space. 572 * 573 * maxbufspace is based on BKVASIZE. Allocating buffers larger then 574 * this may result in KVM fragmentation which is not handled optimally 575 * by the system. 576 */ 577 maxbufspace = nbuf * BKVASIZE; 578 hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); 579 lobufspace = hibufspace - MAXBSIZE; 580 581 lorunningspace = 512 * 1024; 582 hirunningspace = 1024 * 1024; 583 584 /* 585 * Limit the amount of malloc memory since it is wired permanently into 586 * the kernel space. Even though this is accounted for in the buffer 587 * allocation, we don't want the malloced region to grow uncontrolled. 588 * The malloc scheme improves memory utilization significantly on average 589 * (small) directories. 590 */ 591 maxbufmallocspace = hibufspace / 20; 592 593 /* 594 * Reduce the chance of a deadlock occuring by limiting the number 595 * of delayed-write dirty buffers we allow to stack up. 596 */ 597 hidirtybuffers = nbuf / 4 + 20; 598 dirtybufthresh = hidirtybuffers * 9 / 10; 599 numdirtybuffers = 0; 600 /* 601 * To support extreme low-memory systems, make sure hidirtybuffers cannot 602 * eat up all available buffer space. This occurs when our minimum cannot 603 * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming 604 * BKVASIZE'd (8K) buffers. 605 */ 606 while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { 607 hidirtybuffers >>= 1; 608 } 609 lodirtybuffers = hidirtybuffers / 2; 610 611 /* 612 * Try to keep the number of free buffers in the specified range, 613 * and give special processes (e.g. like buf_daemon) access to an 614 * emergency reserve. 615 */ 616 lofreebuffers = nbuf / 18 + 5; 617 hifreebuffers = 2 * lofreebuffers; 618 numfreebuffers = nbuf; 619 620 /* 621 * Maximum number of async ops initiated per buf_daemon loop. This is 622 * somewhat of a hack at the moment, we really need to limit ourselves 623 * based on the number of bytes of I/O in-transit that were initiated 624 * from buf_daemon. 625 */ 626 627 bogus_page = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | 628 VM_ALLOC_NORMAL | VM_ALLOC_WIRED); 629 } 630 631 /* 632 * bfreekva() - free the kva allocation for a buffer. 633 * 634 * Since this call frees up buffer space, we call bufspacewakeup(). 635 */ 636 static void 637 bfreekva(struct buf *bp) 638 { 639 640 if (bp->b_kvasize) { 641 atomic_add_int(&buffreekvacnt, 1); 642 atomic_subtract_int(&bufspace, bp->b_kvasize); 643 vm_map_remove(buffer_map, (vm_offset_t) bp->b_kvabase, 644 (vm_offset_t) bp->b_kvabase + bp->b_kvasize); 645 bp->b_kvasize = 0; 646 bufspacewakeup(); 647 } 648 } 649 650 /* 651 * bremfree: 652 * 653 * Mark the buffer for removal from the appropriate free list in brelse. 654 * 655 */ 656 void 657 bremfree(struct buf *bp) 658 { 659 660 CTR3(KTR_BUF, "bremfree(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 661 KASSERT(BUF_REFCNT(bp), ("bremfree: buf must be locked.")); 662 KASSERT((bp->b_flags & B_REMFREE) == 0, 663 ("bremfree: buffer %p already marked for delayed removal.", bp)); 664 KASSERT(bp->b_qindex != QUEUE_NONE, 665 ("bremfree: buffer %p not on a queue.", bp)); 666 667 bp->b_flags |= B_REMFREE; 668 /* Fixup numfreebuffers count. */ 669 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 670 atomic_subtract_int(&numfreebuffers, 1); 671 } 672 673 /* 674 * bremfreef: 675 * 676 * Force an immediate removal from a free list. Used only in nfs when 677 * it abuses the b_freelist pointer. 678 */ 679 void 680 bremfreef(struct buf *bp) 681 { 682 mtx_lock(&bqlock); 683 bremfreel(bp); 684 mtx_unlock(&bqlock); 685 } 686 687 /* 688 * bremfreel: 689 * 690 * Removes a buffer from the free list, must be called with the 691 * bqlock held. 692 */ 693 static void 694 bremfreel(struct buf *bp) 695 { 696 CTR3(KTR_BUF, "bremfreel(%p) vp %p flags %X", 697 bp, bp->b_vp, bp->b_flags); 698 KASSERT(BUF_REFCNT(bp), ("bremfreel: buffer %p not locked.", bp)); 699 KASSERT(bp->b_qindex != QUEUE_NONE, 700 ("bremfreel: buffer %p not on a queue.", bp)); 701 mtx_assert(&bqlock, MA_OWNED); 702 703 TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); 704 bp->b_qindex = QUEUE_NONE; 705 /* 706 * If this was a delayed bremfree() we only need to remove the buffer 707 * from the queue and return the stats are already done. 708 */ 709 if (bp->b_flags & B_REMFREE) { 710 bp->b_flags &= ~B_REMFREE; 711 return; 712 } 713 /* 714 * Fixup numfreebuffers count. If the buffer is invalid or not 715 * delayed-write, the buffer was free and we must decrement 716 * numfreebuffers. 717 */ 718 if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) 719 atomic_subtract_int(&numfreebuffers, 1); 720 } 721 722 723 /* 724 * Get a buffer with the specified data. Look in the cache first. We 725 * must clear BIO_ERROR and B_INVAL prior to initiating I/O. If B_CACHE 726 * is set, the buffer is valid and we do not have to do anything ( see 727 * getblk() ). This is really just a special case of breadn(). 728 */ 729 int 730 bread(struct vnode * vp, daddr_t blkno, int size, struct ucred * cred, 731 struct buf **bpp) 732 { 733 734 return (breadn(vp, blkno, size, 0, 0, 0, cred, bpp)); 735 } 736 737 /* 738 * Attempt to initiate asynchronous I/O on read-ahead blocks. We must 739 * clear BIO_ERROR and B_INVAL prior to initiating I/O . If B_CACHE is set, 740 * the buffer is valid and we do not have to do anything. 741 */ 742 void 743 breada(struct vnode * vp, daddr_t * rablkno, int * rabsize, 744 int cnt, struct ucred * cred) 745 { 746 struct buf *rabp; 747 int i; 748 749 for (i = 0; i < cnt; i++, rablkno++, rabsize++) { 750 if (inmem(vp, *rablkno)) 751 continue; 752 rabp = getblk(vp, *rablkno, *rabsize, 0, 0, 0); 753 754 if ((rabp->b_flags & B_CACHE) == 0) { 755 if (!TD_IS_IDLETHREAD(curthread)) 756 curthread->td_ru.ru_inblock++; 757 rabp->b_flags |= B_ASYNC; 758 rabp->b_flags &= ~B_INVAL; 759 rabp->b_ioflags &= ~BIO_ERROR; 760 rabp->b_iocmd = BIO_READ; 761 if (rabp->b_rcred == NOCRED && cred != NOCRED) 762 rabp->b_rcred = crhold(cred); 763 vfs_busy_pages(rabp, 0); 764 BUF_KERNPROC(rabp); 765 rabp->b_iooffset = dbtob(rabp->b_blkno); 766 bstrategy(rabp); 767 } else { 768 brelse(rabp); 769 } 770 } 771 } 772 773 /* 774 * Operates like bread, but also starts asynchronous I/O on 775 * read-ahead blocks. 776 */ 777 int 778 breadn(struct vnode * vp, daddr_t blkno, int size, 779 daddr_t * rablkno, int *rabsize, 780 int cnt, struct ucred * cred, struct buf **bpp) 781 { 782 struct buf *bp; 783 int rv = 0, readwait = 0; 784 785 CTR3(KTR_BUF, "breadn(%p, %jd, %d)", vp, blkno, size); 786 *bpp = bp = getblk(vp, blkno, size, 0, 0, 0); 787 788 /* if not found in cache, do some I/O */ 789 if ((bp->b_flags & B_CACHE) == 0) { 790 if (!TD_IS_IDLETHREAD(curthread)) 791 curthread->td_ru.ru_inblock++; 792 bp->b_iocmd = BIO_READ; 793 bp->b_flags &= ~B_INVAL; 794 bp->b_ioflags &= ~BIO_ERROR; 795 if (bp->b_rcred == NOCRED && cred != NOCRED) 796 bp->b_rcred = crhold(cred); 797 vfs_busy_pages(bp, 0); 798 bp->b_iooffset = dbtob(bp->b_blkno); 799 bstrategy(bp); 800 ++readwait; 801 } 802 803 breada(vp, rablkno, rabsize, cnt, cred); 804 805 if (readwait) { 806 rv = bufwait(bp); 807 } 808 return (rv); 809 } 810 811 /* 812 * Write, release buffer on completion. (Done by iodone 813 * if async). Do not bother writing anything if the buffer 814 * is invalid. 815 * 816 * Note that we set B_CACHE here, indicating that buffer is 817 * fully valid and thus cacheable. This is true even of NFS 818 * now so we set it generally. This could be set either here 819 * or in biodone() since the I/O is synchronous. We put it 820 * here. 821 */ 822 int 823 bufwrite(struct buf *bp) 824 { 825 int oldflags; 826 struct vnode *vp; 827 int vp_md; 828 829 CTR3(KTR_BUF, "bufwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 830 if (bp->b_flags & B_INVAL) { 831 brelse(bp); 832 return (0); 833 } 834 835 oldflags = bp->b_flags; 836 837 if (BUF_REFCNT(bp) == 0) 838 panic("bufwrite: buffer is not busy???"); 839 840 if (bp->b_pin_count > 0) 841 bunpin_wait(bp); 842 843 KASSERT(!(bp->b_vflags & BV_BKGRDINPROG), 844 ("FFS background buffer should not get here %p", bp)); 845 846 vp = bp->b_vp; 847 if (vp) 848 vp_md = vp->v_vflag & VV_MD; 849 else 850 vp_md = 0; 851 852 /* Mark the buffer clean */ 853 bundirty(bp); 854 855 bp->b_flags &= ~B_DONE; 856 bp->b_ioflags &= ~BIO_ERROR; 857 bp->b_flags |= B_CACHE; 858 bp->b_iocmd = BIO_WRITE; 859 860 bufobj_wref(bp->b_bufobj); 861 vfs_busy_pages(bp, 1); 862 863 /* 864 * Normal bwrites pipeline writes 865 */ 866 bp->b_runningbufspace = bp->b_bufsize; 867 atomic_add_int(&runningbufspace, bp->b_runningbufspace); 868 869 if (!TD_IS_IDLETHREAD(curthread)) 870 curthread->td_ru.ru_oublock++; 871 if (oldflags & B_ASYNC) 872 BUF_KERNPROC(bp); 873 bp->b_iooffset = dbtob(bp->b_blkno); 874 bstrategy(bp); 875 876 if ((oldflags & B_ASYNC) == 0) { 877 int rtval = bufwait(bp); 878 brelse(bp); 879 return (rtval); 880 } else { 881 /* 882 * don't allow the async write to saturate the I/O 883 * system. We will not deadlock here because 884 * we are blocking waiting for I/O that is already in-progress 885 * to complete. We do not block here if it is the update 886 * or syncer daemon trying to clean up as that can lead 887 * to deadlock. 888 */ 889 if ((curthread->td_pflags & TDP_NORUNNINGBUF) == 0 && !vp_md) 890 waitrunningbufspace(); 891 } 892 893 return (0); 894 } 895 896 void 897 bufbdflush(struct bufobj *bo, struct buf *bp) 898 { 899 struct buf *nbp; 900 901 if (bo->bo_dirty.bv_cnt > dirtybufthresh + 10) { 902 (void) VOP_FSYNC(bp->b_vp, MNT_NOWAIT, curthread); 903 altbufferflushes++; 904 } else if (bo->bo_dirty.bv_cnt > dirtybufthresh) { 905 BO_LOCK(bo); 906 /* 907 * Try to find a buffer to flush. 908 */ 909 TAILQ_FOREACH(nbp, &bo->bo_dirty.bv_hd, b_bobufs) { 910 if ((nbp->b_vflags & BV_BKGRDINPROG) || 911 BUF_LOCK(nbp, 912 LK_EXCLUSIVE | LK_NOWAIT, NULL)) 913 continue; 914 if (bp == nbp) 915 panic("bdwrite: found ourselves"); 916 BO_UNLOCK(bo); 917 /* Don't countdeps with the bo lock held. */ 918 if (buf_countdeps(nbp, 0)) { 919 BO_LOCK(bo); 920 BUF_UNLOCK(nbp); 921 continue; 922 } 923 if (nbp->b_flags & B_CLUSTEROK) { 924 vfs_bio_awrite(nbp); 925 } else { 926 bremfree(nbp); 927 bawrite(nbp); 928 } 929 dirtybufferflushes++; 930 break; 931 } 932 if (nbp == NULL) 933 BO_UNLOCK(bo); 934 } 935 } 936 937 /* 938 * Delayed write. (Buffer is marked dirty). Do not bother writing 939 * anything if the buffer is marked invalid. 940 * 941 * Note that since the buffer must be completely valid, we can safely 942 * set B_CACHE. In fact, we have to set B_CACHE here rather then in 943 * biodone() in order to prevent getblk from writing the buffer 944 * out synchronously. 945 */ 946 void 947 bdwrite(struct buf *bp) 948 { 949 struct thread *td = curthread; 950 struct vnode *vp; 951 struct bufobj *bo; 952 953 CTR3(KTR_BUF, "bdwrite(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 954 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 955 KASSERT(BUF_REFCNT(bp) != 0, ("bdwrite: buffer is not busy")); 956 957 if (bp->b_flags & B_INVAL) { 958 brelse(bp); 959 return; 960 } 961 962 /* 963 * If we have too many dirty buffers, don't create any more. 964 * If we are wildly over our limit, then force a complete 965 * cleanup. Otherwise, just keep the situation from getting 966 * out of control. Note that we have to avoid a recursive 967 * disaster and not try to clean up after our own cleanup! 968 */ 969 vp = bp->b_vp; 970 bo = bp->b_bufobj; 971 if ((td->td_pflags & (TDP_COWINPROGRESS|TDP_INBDFLUSH)) == 0) { 972 td->td_pflags |= TDP_INBDFLUSH; 973 BO_BDFLUSH(bo, bp); 974 td->td_pflags &= ~TDP_INBDFLUSH; 975 } else 976 recursiveflushes++; 977 978 bdirty(bp); 979 /* 980 * Set B_CACHE, indicating that the buffer is fully valid. This is 981 * true even of NFS now. 982 */ 983 bp->b_flags |= B_CACHE; 984 985 /* 986 * This bmap keeps the system from needing to do the bmap later, 987 * perhaps when the system is attempting to do a sync. Since it 988 * is likely that the indirect block -- or whatever other datastructure 989 * that the filesystem needs is still in memory now, it is a good 990 * thing to do this. Note also, that if the pageout daemon is 991 * requesting a sync -- there might not be enough memory to do 992 * the bmap then... So, this is important to do. 993 */ 994 if (vp->v_type != VCHR && bp->b_lblkno == bp->b_blkno) { 995 VOP_BMAP(vp, bp->b_lblkno, NULL, &bp->b_blkno, NULL, NULL); 996 } 997 998 /* 999 * Set the *dirty* buffer range based upon the VM system dirty pages. 1000 */ 1001 vfs_setdirty(bp); 1002 1003 /* 1004 * We need to do this here to satisfy the vnode_pager and the 1005 * pageout daemon, so that it thinks that the pages have been 1006 * "cleaned". Note that since the pages are in a delayed write 1007 * buffer -- the VFS layer "will" see that the pages get written 1008 * out on the next sync, or perhaps the cluster will be completed. 1009 */ 1010 vfs_clean_pages(bp); 1011 bqrelse(bp); 1012 1013 /* 1014 * Wakeup the buffer flushing daemon if we have a lot of dirty 1015 * buffers (midpoint between our recovery point and our stall 1016 * point). 1017 */ 1018 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1019 1020 /* 1021 * note: we cannot initiate I/O from a bdwrite even if we wanted to, 1022 * due to the softdep code. 1023 */ 1024 } 1025 1026 /* 1027 * bdirty: 1028 * 1029 * Turn buffer into delayed write request. We must clear BIO_READ and 1030 * B_RELBUF, and we must set B_DELWRI. We reassign the buffer to 1031 * itself to properly update it in the dirty/clean lists. We mark it 1032 * B_DONE to ensure that any asynchronization of the buffer properly 1033 * clears B_DONE ( else a panic will occur later ). 1034 * 1035 * bdirty() is kinda like bdwrite() - we have to clear B_INVAL which 1036 * might have been set pre-getblk(). Unlike bwrite/bdwrite, bdirty() 1037 * should only be called if the buffer is known-good. 1038 * 1039 * Since the buffer is not on a queue, we do not update the numfreebuffers 1040 * count. 1041 * 1042 * The buffer must be on QUEUE_NONE. 1043 */ 1044 void 1045 bdirty(struct buf *bp) 1046 { 1047 1048 CTR3(KTR_BUF, "bdirty(%p) vp %p flags %X", 1049 bp, bp->b_vp, bp->b_flags); 1050 KASSERT(BUF_REFCNT(bp) == 1, ("bdirty: bp %p not locked",bp)); 1051 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1052 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1053 ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1054 bp->b_flags &= ~(B_RELBUF); 1055 bp->b_iocmd = BIO_WRITE; 1056 1057 if ((bp->b_flags & B_DELWRI) == 0) { 1058 bp->b_flags |= /* XXX B_DONE | */ B_DELWRI; 1059 reassignbuf(bp); 1060 atomic_add_int(&numdirtybuffers, 1); 1061 bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); 1062 } 1063 } 1064 1065 /* 1066 * bundirty: 1067 * 1068 * Clear B_DELWRI for buffer. 1069 * 1070 * Since the buffer is not on a queue, we do not update the numfreebuffers 1071 * count. 1072 * 1073 * The buffer must be on QUEUE_NONE. 1074 */ 1075 1076 void 1077 bundirty(struct buf *bp) 1078 { 1079 1080 CTR3(KTR_BUF, "bundirty(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1081 KASSERT(bp->b_bufobj != NULL, ("No b_bufobj %p", bp)); 1082 KASSERT(bp->b_flags & B_REMFREE || bp->b_qindex == QUEUE_NONE, 1083 ("bundirty: buffer %p still on queue %d", bp, bp->b_qindex)); 1084 KASSERT(BUF_REFCNT(bp) == 1, ("bundirty: bp %p not locked",bp)); 1085 1086 if (bp->b_flags & B_DELWRI) { 1087 bp->b_flags &= ~B_DELWRI; 1088 reassignbuf(bp); 1089 atomic_subtract_int(&numdirtybuffers, 1); 1090 numdirtywakeup(lodirtybuffers); 1091 } 1092 /* 1093 * Since it is now being written, we can clear its deferred write flag. 1094 */ 1095 bp->b_flags &= ~B_DEFERRED; 1096 } 1097 1098 /* 1099 * bawrite: 1100 * 1101 * Asynchronous write. Start output on a buffer, but do not wait for 1102 * it to complete. The buffer is released when the output completes. 1103 * 1104 * bwrite() ( or the VOP routine anyway ) is responsible for handling 1105 * B_INVAL buffers. Not us. 1106 */ 1107 void 1108 bawrite(struct buf *bp) 1109 { 1110 1111 bp->b_flags |= B_ASYNC; 1112 (void) bwrite(bp); 1113 } 1114 1115 /* 1116 * bwillwrite: 1117 * 1118 * Called prior to the locking of any vnodes when we are expecting to 1119 * write. We do not want to starve the buffer cache with too many 1120 * dirty buffers so we block here. By blocking prior to the locking 1121 * of any vnodes we attempt to avoid the situation where a locked vnode 1122 * prevents the various system daemons from flushing related buffers. 1123 */ 1124 1125 void 1126 bwillwrite(void) 1127 { 1128 1129 if (numdirtybuffers >= hidirtybuffers) { 1130 mtx_lock(&nblock); 1131 while (numdirtybuffers >= hidirtybuffers) { 1132 bd_wakeup(1); 1133 needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; 1134 msleep(&needsbuffer, &nblock, 1135 (PRIBIO + 4), "flswai", 0); 1136 } 1137 mtx_unlock(&nblock); 1138 } 1139 } 1140 1141 /* 1142 * Return true if we have too many dirty buffers. 1143 */ 1144 int 1145 buf_dirty_count_severe(void) 1146 { 1147 1148 return(numdirtybuffers >= hidirtybuffers); 1149 } 1150 1151 /* 1152 * brelse: 1153 * 1154 * Release a busy buffer and, if requested, free its resources. The 1155 * buffer will be stashed in the appropriate bufqueue[] allowing it 1156 * to be accessed later as a cache entity or reused for other purposes. 1157 */ 1158 void 1159 brelse(struct buf *bp) 1160 { 1161 CTR3(KTR_BUF, "brelse(%p) vp %p flags %X", 1162 bp, bp->b_vp, bp->b_flags); 1163 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1164 ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1165 1166 if (bp->b_flags & B_MANAGED) { 1167 bqrelse(bp); 1168 return; 1169 } 1170 1171 if (bp->b_iocmd == BIO_WRITE && (bp->b_ioflags & BIO_ERROR) && 1172 bp->b_error == EIO && !(bp->b_flags & B_INVAL)) { 1173 /* 1174 * Failed write, redirty. Must clear BIO_ERROR to prevent 1175 * pages from being scrapped. If the error is anything 1176 * other than an I/O error (EIO), assume that retryingi 1177 * is futile. 1178 */ 1179 bp->b_ioflags &= ~BIO_ERROR; 1180 bdirty(bp); 1181 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1182 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1183 /* 1184 * Either a failed I/O or we were asked to free or not 1185 * cache the buffer. 1186 */ 1187 bp->b_flags |= B_INVAL; 1188 if (!LIST_EMPTY(&bp->b_dep)) 1189 buf_deallocate(bp); 1190 if (bp->b_flags & B_DELWRI) { 1191 atomic_subtract_int(&numdirtybuffers, 1); 1192 numdirtywakeup(lodirtybuffers); 1193 } 1194 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1195 if ((bp->b_flags & B_VMIO) == 0) { 1196 if (bp->b_bufsize) 1197 allocbuf(bp, 0); 1198 if (bp->b_vp) 1199 brelvp(bp); 1200 } 1201 } 1202 1203 /* 1204 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1205 * is called with B_DELWRI set, the underlying pages may wind up 1206 * getting freed causing a previous write (bdwrite()) to get 'lost' 1207 * because pages associated with a B_DELWRI bp are marked clean. 1208 * 1209 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1210 * if B_DELWRI is set. 1211 * 1212 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1213 * on pages to return pages to the VM page queues. 1214 */ 1215 if (bp->b_flags & B_DELWRI) 1216 bp->b_flags &= ~B_RELBUF; 1217 else if (vm_page_count_severe()) { 1218 /* 1219 * XXX This lock may not be necessary since BKGRDINPROG 1220 * cannot be set while we hold the buf lock, it can only be 1221 * cleared if it is already pending. 1222 */ 1223 if (bp->b_vp) { 1224 BO_LOCK(bp->b_bufobj); 1225 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1226 bp->b_flags |= B_RELBUF; 1227 BO_UNLOCK(bp->b_bufobj); 1228 } else 1229 bp->b_flags |= B_RELBUF; 1230 } 1231 1232 /* 1233 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1234 * constituted, not even NFS buffers now. Two flags effect this. If 1235 * B_INVAL, the struct buf is invalidated but the VM object is kept 1236 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1237 * 1238 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1239 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1240 * buffer is also B_INVAL because it hits the re-dirtying code above. 1241 * 1242 * Normally we can do this whether a buffer is B_DELWRI or not. If 1243 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1244 * the commit state and we cannot afford to lose the buffer. If the 1245 * buffer has a background write in progress, we need to keep it 1246 * around to prevent it from being reconstituted and starting a second 1247 * background write. 1248 */ 1249 if ((bp->b_flags & B_VMIO) 1250 && !(bp->b_vp->v_mount != NULL && 1251 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1252 !vn_isdisk(bp->b_vp, NULL) && 1253 (bp->b_flags & B_DELWRI)) 1254 ) { 1255 1256 int i, j, resid; 1257 vm_page_t m; 1258 off_t foff; 1259 vm_pindex_t poff; 1260 vm_object_t obj; 1261 1262 obj = bp->b_bufobj->bo_object; 1263 1264 /* 1265 * Get the base offset and length of the buffer. Note that 1266 * in the VMIO case if the buffer block size is not 1267 * page-aligned then b_data pointer may not be page-aligned. 1268 * But our b_pages[] array *IS* page aligned. 1269 * 1270 * block sizes less then DEV_BSIZE (usually 512) are not 1271 * supported due to the page granularity bits (m->valid, 1272 * m->dirty, etc...). 1273 * 1274 * See man buf(9) for more information 1275 */ 1276 resid = bp->b_bufsize; 1277 foff = bp->b_offset; 1278 VM_OBJECT_LOCK(obj); 1279 for (i = 0; i < bp->b_npages; i++) { 1280 int had_bogus = 0; 1281 1282 m = bp->b_pages[i]; 1283 1284 /* 1285 * If we hit a bogus page, fixup *all* the bogus pages 1286 * now. 1287 */ 1288 if (m == bogus_page) { 1289 poff = OFF_TO_IDX(bp->b_offset); 1290 had_bogus = 1; 1291 1292 for (j = i; j < bp->b_npages; j++) { 1293 vm_page_t mtmp; 1294 mtmp = bp->b_pages[j]; 1295 if (mtmp == bogus_page) { 1296 mtmp = vm_page_lookup(obj, poff + j); 1297 if (!mtmp) { 1298 panic("brelse: page missing\n"); 1299 } 1300 bp->b_pages[j] = mtmp; 1301 } 1302 } 1303 1304 if ((bp->b_flags & B_INVAL) == 0) { 1305 pmap_qenter( 1306 trunc_page((vm_offset_t)bp->b_data), 1307 bp->b_pages, bp->b_npages); 1308 } 1309 m = bp->b_pages[i]; 1310 } 1311 if ((bp->b_flags & B_NOCACHE) || 1312 (bp->b_ioflags & BIO_ERROR)) { 1313 int poffset = foff & PAGE_MASK; 1314 int presid = resid > (PAGE_SIZE - poffset) ? 1315 (PAGE_SIZE - poffset) : resid; 1316 1317 KASSERT(presid >= 0, ("brelse: extra page")); 1318 vm_page_lock_queues(); 1319 vm_page_set_invalid(m, poffset, presid); 1320 vm_page_unlock_queues(); 1321 if (had_bogus) 1322 printf("avoided corruption bug in bogus_page/brelse code\n"); 1323 } 1324 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1325 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1326 } 1327 VM_OBJECT_UNLOCK(obj); 1328 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1329 vfs_vmio_release(bp); 1330 1331 } else if (bp->b_flags & B_VMIO) { 1332 1333 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1334 vfs_vmio_release(bp); 1335 } 1336 1337 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1338 if (bp->b_bufsize != 0) 1339 allocbuf(bp, 0); 1340 if (bp->b_vp != NULL) 1341 brelvp(bp); 1342 } 1343 1344 if (BUF_REFCNT(bp) > 1) { 1345 /* do not release to free list */ 1346 BUF_UNLOCK(bp); 1347 return; 1348 } 1349 1350 /* enqueue */ 1351 mtx_lock(&bqlock); 1352 /* Handle delayed bremfree() processing. */ 1353 if (bp->b_flags & B_REMFREE) 1354 bremfreel(bp); 1355 if (bp->b_qindex != QUEUE_NONE) 1356 panic("brelse: free buffer onto another queue???"); 1357 1358 /* buffers with no memory */ 1359 if (bp->b_bufsize == 0) { 1360 bp->b_flags |= B_INVAL; 1361 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1362 if (bp->b_vflags & BV_BKGRDINPROG) 1363 panic("losing buffer 1"); 1364 if (bp->b_kvasize) { 1365 bp->b_qindex = QUEUE_EMPTYKVA; 1366 } else { 1367 bp->b_qindex = QUEUE_EMPTY; 1368 } 1369 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1370 /* buffers with junk contents */ 1371 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1372 (bp->b_ioflags & BIO_ERROR)) { 1373 bp->b_flags |= B_INVAL; 1374 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1375 if (bp->b_vflags & BV_BKGRDINPROG) 1376 panic("losing buffer 2"); 1377 bp->b_qindex = QUEUE_CLEAN; 1378 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1379 /* remaining buffers */ 1380 } else { 1381 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1382 (B_DELWRI|B_NEEDSGIANT)) 1383 bp->b_qindex = QUEUE_DIRTY_GIANT; 1384 if (bp->b_flags & B_DELWRI) 1385 bp->b_qindex = QUEUE_DIRTY; 1386 else 1387 bp->b_qindex = QUEUE_CLEAN; 1388 if (bp->b_flags & B_AGE) 1389 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1390 else 1391 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1392 } 1393 mtx_unlock(&bqlock); 1394 1395 /* 1396 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1397 * placed the buffer on the correct queue. We must also disassociate 1398 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1399 * find it. 1400 */ 1401 if (bp->b_flags & B_INVAL) { 1402 if (bp->b_flags & B_DELWRI) 1403 bundirty(bp); 1404 if (bp->b_vp) 1405 brelvp(bp); 1406 } 1407 1408 /* 1409 * Fixup numfreebuffers count. The bp is on an appropriate queue 1410 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1411 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1412 * if B_INVAL is set ). 1413 */ 1414 1415 if (!(bp->b_flags & B_DELWRI)) 1416 bufcountwakeup(); 1417 1418 /* 1419 * Something we can maybe free or reuse 1420 */ 1421 if (bp->b_bufsize || bp->b_kvasize) 1422 bufspacewakeup(); 1423 1424 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1425 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1426 panic("brelse: not dirty"); 1427 /* unlock */ 1428 BUF_UNLOCK(bp); 1429 } 1430 1431 /* 1432 * Release a buffer back to the appropriate queue but do not try to free 1433 * it. The buffer is expected to be used again soon. 1434 * 1435 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1436 * biodone() to requeue an async I/O on completion. It is also used when 1437 * known good buffers need to be requeued but we think we may need the data 1438 * again soon. 1439 * 1440 * XXX we should be able to leave the B_RELBUF hint set on completion. 1441 */ 1442 void 1443 bqrelse(struct buf *bp) 1444 { 1445 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1446 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1447 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1448 1449 if (BUF_REFCNT(bp) > 1) { 1450 /* do not release to free list */ 1451 BUF_UNLOCK(bp); 1452 return; 1453 } 1454 1455 if (bp->b_flags & B_MANAGED) { 1456 if (bp->b_flags & B_REMFREE) { 1457 mtx_lock(&bqlock); 1458 bremfreel(bp); 1459 mtx_unlock(&bqlock); 1460 } 1461 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1462 BUF_UNLOCK(bp); 1463 return; 1464 } 1465 1466 mtx_lock(&bqlock); 1467 /* Handle delayed bremfree() processing. */ 1468 if (bp->b_flags & B_REMFREE) 1469 bremfreel(bp); 1470 if (bp->b_qindex != QUEUE_NONE) 1471 panic("bqrelse: free buffer onto another queue???"); 1472 /* buffers with stale but valid contents */ 1473 if (bp->b_flags & B_DELWRI) { 1474 if (bp->b_flags & B_NEEDSGIANT) 1475 bp->b_qindex = QUEUE_DIRTY_GIANT; 1476 else 1477 bp->b_qindex = QUEUE_DIRTY; 1478 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1479 } else { 1480 /* 1481 * XXX This lock may not be necessary since BKGRDINPROG 1482 * cannot be set while we hold the buf lock, it can only be 1483 * cleared if it is already pending. 1484 */ 1485 BO_LOCK(bp->b_bufobj); 1486 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1487 BO_UNLOCK(bp->b_bufobj); 1488 bp->b_qindex = QUEUE_CLEAN; 1489 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1490 b_freelist); 1491 } else { 1492 /* 1493 * We are too low on memory, we have to try to free 1494 * the buffer (most importantly: the wired pages 1495 * making up its backing store) *now*. 1496 */ 1497 BO_UNLOCK(bp->b_bufobj); 1498 mtx_unlock(&bqlock); 1499 brelse(bp); 1500 return; 1501 } 1502 } 1503 mtx_unlock(&bqlock); 1504 1505 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1506 bufcountwakeup(); 1507 1508 /* 1509 * Something we can maybe free or reuse. 1510 */ 1511 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1512 bufspacewakeup(); 1513 1514 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1515 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1516 panic("bqrelse: not dirty"); 1517 /* unlock */ 1518 BUF_UNLOCK(bp); 1519 } 1520 1521 /* Give pages used by the bp back to the VM system (where possible) */ 1522 static void 1523 vfs_vmio_release(struct buf *bp) 1524 { 1525 int i; 1526 vm_page_t m; 1527 1528 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1529 vm_page_lock_queues(); 1530 for (i = 0; i < bp->b_npages; i++) { 1531 m = bp->b_pages[i]; 1532 bp->b_pages[i] = NULL; 1533 /* 1534 * In order to keep page LRU ordering consistent, put 1535 * everything on the inactive queue. 1536 */ 1537 vm_page_unwire(m, 0); 1538 /* 1539 * We don't mess with busy pages, it is 1540 * the responsibility of the process that 1541 * busied the pages to deal with them. 1542 */ 1543 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1544 continue; 1545 1546 if (m->wire_count == 0) { 1547 /* 1548 * Might as well free the page if we can and it has 1549 * no valid data. We also free the page if the 1550 * buffer was used for direct I/O 1551 */ 1552 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1553 m->hold_count == 0) { 1554 vm_page_free(m); 1555 } else if (bp->b_flags & B_DIRECT) { 1556 vm_page_try_to_free(m); 1557 } else if (vm_page_count_severe()) { 1558 vm_page_try_to_cache(m); 1559 } 1560 } 1561 } 1562 vm_page_unlock_queues(); 1563 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1564 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1565 1566 if (bp->b_bufsize) { 1567 bufspacewakeup(); 1568 bp->b_bufsize = 0; 1569 } 1570 bp->b_npages = 0; 1571 bp->b_flags &= ~B_VMIO; 1572 if (bp->b_vp) 1573 brelvp(bp); 1574 } 1575 1576 /* 1577 * Check to see if a block at a particular lbn is available for a clustered 1578 * write. 1579 */ 1580 static int 1581 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1582 { 1583 struct buf *bpa; 1584 int match; 1585 1586 match = 0; 1587 1588 /* If the buf isn't in core skip it */ 1589 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1590 return (0); 1591 1592 /* If the buf is busy we don't want to wait for it */ 1593 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1594 return (0); 1595 1596 /* Only cluster with valid clusterable delayed write buffers */ 1597 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1598 (B_DELWRI | B_CLUSTEROK)) 1599 goto done; 1600 1601 if (bpa->b_bufsize != size) 1602 goto done; 1603 1604 /* 1605 * Check to see if it is in the expected place on disk and that the 1606 * block has been mapped. 1607 */ 1608 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1609 match = 1; 1610 done: 1611 BUF_UNLOCK(bpa); 1612 return (match); 1613 } 1614 1615 /* 1616 * vfs_bio_awrite: 1617 * 1618 * Implement clustered async writes for clearing out B_DELWRI buffers. 1619 * This is much better then the old way of writing only one buffer at 1620 * a time. Note that we may not be presented with the buffers in the 1621 * correct order, so we search for the cluster in both directions. 1622 */ 1623 int 1624 vfs_bio_awrite(struct buf *bp) 1625 { 1626 int i; 1627 int j; 1628 daddr_t lblkno = bp->b_lblkno; 1629 struct vnode *vp = bp->b_vp; 1630 int ncl; 1631 int nwritten; 1632 int size; 1633 int maxcl; 1634 1635 /* 1636 * right now we support clustered writing only to regular files. If 1637 * we find a clusterable block we could be in the middle of a cluster 1638 * rather then at the beginning. 1639 */ 1640 if ((vp->v_type == VREG) && 1641 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1642 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1643 1644 size = vp->v_mount->mnt_stat.f_iosize; 1645 maxcl = MAXPHYS / size; 1646 1647 VI_LOCK(vp); 1648 for (i = 1; i < maxcl; i++) 1649 if (vfs_bio_clcheck(vp, size, lblkno + i, 1650 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1651 break; 1652 1653 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1654 if (vfs_bio_clcheck(vp, size, lblkno - j, 1655 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1656 break; 1657 1658 VI_UNLOCK(vp); 1659 --j; 1660 ncl = i + j; 1661 /* 1662 * this is a possible cluster write 1663 */ 1664 if (ncl != 1) { 1665 BUF_UNLOCK(bp); 1666 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1667 return nwritten; 1668 } 1669 } 1670 bremfree(bp); 1671 bp->b_flags |= B_ASYNC; 1672 /* 1673 * default (old) behavior, writing out only one block 1674 * 1675 * XXX returns b_bufsize instead of b_bcount for nwritten? 1676 */ 1677 nwritten = bp->b_bufsize; 1678 (void) bwrite(bp); 1679 1680 return nwritten; 1681 } 1682 1683 /* 1684 * getnewbuf: 1685 * 1686 * Find and initialize a new buffer header, freeing up existing buffers 1687 * in the bufqueues as necessary. The new buffer is returned locked. 1688 * 1689 * Important: B_INVAL is not set. If the caller wishes to throw the 1690 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1691 * 1692 * We block if: 1693 * We have insufficient buffer headers 1694 * We have insufficient buffer space 1695 * buffer_map is too fragmented ( space reservation fails ) 1696 * If we have to flush dirty buffers ( but we try to avoid this ) 1697 * 1698 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1699 * Instead we ask the buf daemon to do it for us. We attempt to 1700 * avoid piecemeal wakeups of the pageout daemon. 1701 */ 1702 1703 static struct buf * 1704 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1705 { 1706 struct buf *bp; 1707 struct buf *nbp; 1708 int defrag = 0; 1709 int nqindex; 1710 static int flushingbufs; 1711 1712 /* 1713 * We can't afford to block since we might be holding a vnode lock, 1714 * which may prevent system daemons from running. We deal with 1715 * low-memory situations by proactively returning memory and running 1716 * async I/O rather then sync I/O. 1717 */ 1718 1719 atomic_add_int(&getnewbufcalls, 1); 1720 atomic_subtract_int(&getnewbufrestarts, 1); 1721 restart: 1722 atomic_add_int(&getnewbufrestarts, 1); 1723 1724 /* 1725 * Setup for scan. If we do not have enough free buffers, 1726 * we setup a degenerate case that immediately fails. Note 1727 * that if we are specially marked process, we are allowed to 1728 * dip into our reserves. 1729 * 1730 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1731 * 1732 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1733 * However, there are a number of cases (defragging, reusing, ...) 1734 * where we cannot backup. 1735 */ 1736 mtx_lock(&bqlock); 1737 nqindex = QUEUE_EMPTYKVA; 1738 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1739 1740 if (nbp == NULL) { 1741 /* 1742 * If no EMPTYKVA buffers and we are either 1743 * defragging or reusing, locate a CLEAN buffer 1744 * to free or reuse. If bufspace useage is low 1745 * skip this step so we can allocate a new buffer. 1746 */ 1747 if (defrag || bufspace >= lobufspace) { 1748 nqindex = QUEUE_CLEAN; 1749 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1750 } 1751 1752 /* 1753 * If we could not find or were not allowed to reuse a 1754 * CLEAN buffer, check to see if it is ok to use an EMPTY 1755 * buffer. We can only use an EMPTY buffer if allocating 1756 * its KVA would not otherwise run us out of buffer space. 1757 */ 1758 if (nbp == NULL && defrag == 0 && 1759 bufspace + maxsize < hibufspace) { 1760 nqindex = QUEUE_EMPTY; 1761 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1762 } 1763 } 1764 1765 /* 1766 * Run scan, possibly freeing data and/or kva mappings on the fly 1767 * depending. 1768 */ 1769 1770 while ((bp = nbp) != NULL) { 1771 int qindex = nqindex; 1772 1773 /* 1774 * Calculate next bp ( we can only use it if we do not block 1775 * or do other fancy things ). 1776 */ 1777 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1778 switch(qindex) { 1779 case QUEUE_EMPTY: 1780 nqindex = QUEUE_EMPTYKVA; 1781 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1782 break; 1783 /* FALLTHROUGH */ 1784 case QUEUE_EMPTYKVA: 1785 nqindex = QUEUE_CLEAN; 1786 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1787 break; 1788 /* FALLTHROUGH */ 1789 case QUEUE_CLEAN: 1790 /* 1791 * nbp is NULL. 1792 */ 1793 break; 1794 } 1795 } 1796 /* 1797 * If we are defragging then we need a buffer with 1798 * b_kvasize != 0. XXX this situation should no longer 1799 * occur, if defrag is non-zero the buffer's b_kvasize 1800 * should also be non-zero at this point. XXX 1801 */ 1802 if (defrag && bp->b_kvasize == 0) { 1803 printf("Warning: defrag empty buffer %p\n", bp); 1804 continue; 1805 } 1806 1807 /* 1808 * Start freeing the bp. This is somewhat involved. nbp 1809 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1810 */ 1811 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1812 continue; 1813 if (bp->b_vp) { 1814 BO_LOCK(bp->b_bufobj); 1815 if (bp->b_vflags & BV_BKGRDINPROG) { 1816 BO_UNLOCK(bp->b_bufobj); 1817 BUF_UNLOCK(bp); 1818 continue; 1819 } 1820 BO_UNLOCK(bp->b_bufobj); 1821 } 1822 CTR6(KTR_BUF, 1823 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1824 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1825 bp->b_kvasize, bp->b_bufsize, qindex); 1826 1827 /* 1828 * Sanity Checks 1829 */ 1830 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1831 1832 /* 1833 * Note: we no longer distinguish between VMIO and non-VMIO 1834 * buffers. 1835 */ 1836 1837 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1838 1839 bremfreel(bp); 1840 mtx_unlock(&bqlock); 1841 1842 if (qindex == QUEUE_CLEAN) { 1843 if (bp->b_flags & B_VMIO) { 1844 bp->b_flags &= ~B_ASYNC; 1845 vfs_vmio_release(bp); 1846 } 1847 if (bp->b_vp) 1848 brelvp(bp); 1849 } 1850 1851 /* 1852 * NOTE: nbp is now entirely invalid. We can only restart 1853 * the scan from this point on. 1854 * 1855 * Get the rest of the buffer freed up. b_kva* is still 1856 * valid after this operation. 1857 */ 1858 1859 if (bp->b_rcred != NOCRED) { 1860 crfree(bp->b_rcred); 1861 bp->b_rcred = NOCRED; 1862 } 1863 if (bp->b_wcred != NOCRED) { 1864 crfree(bp->b_wcred); 1865 bp->b_wcred = NOCRED; 1866 } 1867 if (!LIST_EMPTY(&bp->b_dep)) 1868 buf_deallocate(bp); 1869 if (bp->b_vflags & BV_BKGRDINPROG) 1870 panic("losing buffer 3"); 1871 KASSERT(bp->b_vp == NULL, 1872 ("bp: %p still has vnode %p. qindex: %d", 1873 bp, bp->b_vp, qindex)); 1874 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1875 ("bp: %p still on a buffer list. xflags %X", 1876 bp, bp->b_xflags)); 1877 1878 if (bp->b_bufsize) 1879 allocbuf(bp, 0); 1880 1881 bp->b_flags = 0; 1882 bp->b_ioflags = 0; 1883 bp->b_xflags = 0; 1884 bp->b_vflags = 0; 1885 bp->b_vp = NULL; 1886 bp->b_blkno = bp->b_lblkno = 0; 1887 bp->b_offset = NOOFFSET; 1888 bp->b_iodone = 0; 1889 bp->b_error = 0; 1890 bp->b_resid = 0; 1891 bp->b_bcount = 0; 1892 bp->b_npages = 0; 1893 bp->b_dirtyoff = bp->b_dirtyend = 0; 1894 bp->b_bufobj = NULL; 1895 bp->b_pin_count = 0; 1896 bp->b_fsprivate1 = NULL; 1897 bp->b_fsprivate2 = NULL; 1898 bp->b_fsprivate3 = NULL; 1899 1900 LIST_INIT(&bp->b_dep); 1901 1902 /* 1903 * If we are defragging then free the buffer. 1904 */ 1905 if (defrag) { 1906 bp->b_flags |= B_INVAL; 1907 bfreekva(bp); 1908 brelse(bp); 1909 defrag = 0; 1910 goto restart; 1911 } 1912 1913 /* 1914 * Notify any waiters for the buffer lock about 1915 * identity change by freeing the buffer. 1916 */ 1917 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) { 1918 bp->b_flags |= B_INVAL; 1919 bfreekva(bp); 1920 brelse(bp); 1921 goto restart; 1922 } 1923 1924 /* 1925 * If we are overcomitted then recover the buffer and its 1926 * KVM space. This occurs in rare situations when multiple 1927 * processes are blocked in getnewbuf() or allocbuf(). 1928 */ 1929 if (bufspace >= hibufspace) 1930 flushingbufs = 1; 1931 if (flushingbufs && bp->b_kvasize != 0) { 1932 bp->b_flags |= B_INVAL; 1933 bfreekva(bp); 1934 brelse(bp); 1935 goto restart; 1936 } 1937 if (bufspace < lobufspace) 1938 flushingbufs = 0; 1939 break; 1940 } 1941 1942 /* 1943 * If we exhausted our list, sleep as appropriate. We may have to 1944 * wakeup various daemons and write out some dirty buffers. 1945 * 1946 * Generally we are sleeping due to insufficient buffer space. 1947 */ 1948 1949 if (bp == NULL) { 1950 int flags; 1951 char *waitmsg; 1952 1953 if (defrag) { 1954 flags = VFS_BIO_NEED_BUFSPACE; 1955 waitmsg = "nbufkv"; 1956 } else if (bufspace >= hibufspace) { 1957 waitmsg = "nbufbs"; 1958 flags = VFS_BIO_NEED_BUFSPACE; 1959 } else { 1960 waitmsg = "newbuf"; 1961 flags = VFS_BIO_NEED_ANY; 1962 } 1963 mtx_lock(&nblock); 1964 needsbuffer |= flags; 1965 mtx_unlock(&nblock); 1966 mtx_unlock(&bqlock); 1967 1968 bd_speedup(); /* heeeelp */ 1969 1970 mtx_lock(&nblock); 1971 while (needsbuffer & flags) { 1972 if (msleep(&needsbuffer, &nblock, 1973 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1974 mtx_unlock(&nblock); 1975 return (NULL); 1976 } 1977 } 1978 mtx_unlock(&nblock); 1979 } else { 1980 /* 1981 * We finally have a valid bp. We aren't quite out of the 1982 * woods, we still have to reserve kva space. In order 1983 * to keep fragmentation sane we only allocate kva in 1984 * BKVASIZE chunks. 1985 */ 1986 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1987 1988 if (maxsize != bp->b_kvasize) { 1989 vm_offset_t addr = 0; 1990 1991 bfreekva(bp); 1992 1993 vm_map_lock(buffer_map); 1994 if (vm_map_findspace(buffer_map, 1995 vm_map_min(buffer_map), maxsize, &addr)) { 1996 /* 1997 * Uh oh. Buffer map is to fragmented. We 1998 * must defragment the map. 1999 */ 2000 atomic_add_int(&bufdefragcnt, 1); 2001 vm_map_unlock(buffer_map); 2002 defrag = 1; 2003 bp->b_flags |= B_INVAL; 2004 brelse(bp); 2005 goto restart; 2006 } 2007 if (addr) { 2008 vm_map_insert(buffer_map, NULL, 0, 2009 addr, addr + maxsize, 2010 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2011 2012 bp->b_kvabase = (caddr_t) addr; 2013 bp->b_kvasize = maxsize; 2014 atomic_add_int(&bufspace, bp->b_kvasize); 2015 atomic_add_int(&bufreusecnt, 1); 2016 } 2017 vm_map_unlock(buffer_map); 2018 } 2019 bp->b_saveaddr = bp->b_kvabase; 2020 bp->b_data = bp->b_saveaddr; 2021 } 2022 return(bp); 2023 } 2024 2025 /* 2026 * buf_daemon: 2027 * 2028 * buffer flushing daemon. Buffers are normally flushed by the 2029 * update daemon but if it cannot keep up this process starts to 2030 * take the load in an attempt to prevent getnewbuf() from blocking. 2031 */ 2032 2033 static struct kproc_desc buf_kp = { 2034 "bufdaemon", 2035 buf_daemon, 2036 &bufdaemonproc 2037 }; 2038 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2039 2040 static void 2041 buf_daemon() 2042 { 2043 2044 /* 2045 * This process needs to be suspended prior to shutdown sync. 2046 */ 2047 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2048 SHUTDOWN_PRI_LAST); 2049 2050 /* 2051 * This process is allowed to take the buffer cache to the limit 2052 */ 2053 curthread->td_pflags |= TDP_NORUNNINGBUF; 2054 mtx_lock(&bdlock); 2055 for (;;) { 2056 bd_request = 0; 2057 mtx_unlock(&bdlock); 2058 2059 kproc_suspend_check(bufdaemonproc); 2060 2061 /* 2062 * Do the flush. Limit the amount of in-transit I/O we 2063 * allow to build up, otherwise we would completely saturate 2064 * the I/O system. Wakeup any waiting processes before we 2065 * normally would so they can run in parallel with our drain. 2066 */ 2067 while (numdirtybuffers > lodirtybuffers) { 2068 int flushed; 2069 2070 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2071 /* The list empty check here is slightly racy */ 2072 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2073 mtx_lock(&Giant); 2074 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2075 mtx_unlock(&Giant); 2076 } 2077 if (flushed == 0) { 2078 /* 2079 * Could not find any buffers without rollback 2080 * dependencies, so just write the first one 2081 * in the hopes of eventually making progress. 2082 */ 2083 flushbufqueues(QUEUE_DIRTY, 1); 2084 if (!TAILQ_EMPTY( 2085 &bufqueues[QUEUE_DIRTY_GIANT])) { 2086 mtx_lock(&Giant); 2087 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2088 mtx_unlock(&Giant); 2089 } 2090 break; 2091 } 2092 uio_yield(); 2093 } 2094 2095 /* 2096 * Only clear bd_request if we have reached our low water 2097 * mark. The buf_daemon normally waits 1 second and 2098 * then incrementally flushes any dirty buffers that have 2099 * built up, within reason. 2100 * 2101 * If we were unable to hit our low water mark and couldn't 2102 * find any flushable buffers, we sleep half a second. 2103 * Otherwise we loop immediately. 2104 */ 2105 mtx_lock(&bdlock); 2106 if (numdirtybuffers <= lodirtybuffers) { 2107 /* 2108 * We reached our low water mark, reset the 2109 * request and sleep until we are needed again. 2110 * The sleep is just so the suspend code works. 2111 */ 2112 bd_request = 0; 2113 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2114 } else { 2115 /* 2116 * We couldn't find any flushable dirty buffers but 2117 * still have too many dirty buffers, we 2118 * have to sleep and try again. (rare) 2119 */ 2120 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2121 } 2122 } 2123 } 2124 2125 /* 2126 * flushbufqueues: 2127 * 2128 * Try to flush a buffer in the dirty queue. We must be careful to 2129 * free up B_INVAL buffers instead of write them, which NFS is 2130 * particularly sensitive to. 2131 */ 2132 static int flushwithdeps = 0; 2133 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2134 0, "Number of buffers flushed with dependecies that require rollbacks"); 2135 2136 static int 2137 flushbufqueues(int queue, int flushdeps) 2138 { 2139 struct buf sentinel; 2140 struct vnode *vp; 2141 struct mount *mp; 2142 struct buf *bp; 2143 int hasdeps; 2144 int flushed; 2145 int target; 2146 2147 target = numdirtybuffers - lodirtybuffers; 2148 if (flushdeps && target > 2) 2149 target /= 2; 2150 flushed = 0; 2151 bp = NULL; 2152 mtx_lock(&bqlock); 2153 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2154 while (flushed != target) { 2155 bp = TAILQ_FIRST(&bufqueues[queue]); 2156 if (bp == &sentinel) 2157 break; 2158 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2159 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2160 2161 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2162 continue; 2163 if (bp->b_pin_count > 0) { 2164 BUF_UNLOCK(bp); 2165 continue; 2166 } 2167 BO_LOCK(bp->b_bufobj); 2168 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2169 (bp->b_flags & B_DELWRI) == 0) { 2170 BO_UNLOCK(bp->b_bufobj); 2171 BUF_UNLOCK(bp); 2172 continue; 2173 } 2174 BO_UNLOCK(bp->b_bufobj); 2175 if (bp->b_flags & B_INVAL) { 2176 bremfreel(bp); 2177 mtx_unlock(&bqlock); 2178 brelse(bp); 2179 flushed++; 2180 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2181 mtx_lock(&bqlock); 2182 continue; 2183 } 2184 2185 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2186 if (flushdeps == 0) { 2187 BUF_UNLOCK(bp); 2188 continue; 2189 } 2190 hasdeps = 1; 2191 } else 2192 hasdeps = 0; 2193 /* 2194 * We must hold the lock on a vnode before writing 2195 * one of its buffers. Otherwise we may confuse, or 2196 * in the case of a snapshot vnode, deadlock the 2197 * system. 2198 * 2199 * The lock order here is the reverse of the normal 2200 * of vnode followed by buf lock. This is ok because 2201 * the NOWAIT will prevent deadlock. 2202 */ 2203 vp = bp->b_vp; 2204 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2205 BUF_UNLOCK(bp); 2206 continue; 2207 } 2208 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { 2209 mtx_unlock(&bqlock); 2210 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2211 bp, bp->b_vp, bp->b_flags); 2212 vfs_bio_awrite(bp); 2213 vn_finished_write(mp); 2214 VOP_UNLOCK(vp, 0); 2215 flushwithdeps += hasdeps; 2216 flushed++; 2217 waitrunningbufspace(); 2218 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2219 mtx_lock(&bqlock); 2220 continue; 2221 } 2222 vn_finished_write(mp); 2223 BUF_UNLOCK(bp); 2224 } 2225 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2226 mtx_unlock(&bqlock); 2227 return (flushed); 2228 } 2229 2230 /* 2231 * Check to see if a block is currently memory resident. 2232 */ 2233 struct buf * 2234 incore(struct bufobj *bo, daddr_t blkno) 2235 { 2236 struct buf *bp; 2237 2238 BO_LOCK(bo); 2239 bp = gbincore(bo, blkno); 2240 BO_UNLOCK(bo); 2241 return (bp); 2242 } 2243 2244 /* 2245 * Returns true if no I/O is needed to access the 2246 * associated VM object. This is like incore except 2247 * it also hunts around in the VM system for the data. 2248 */ 2249 2250 static int 2251 inmem(struct vnode * vp, daddr_t blkno) 2252 { 2253 vm_object_t obj; 2254 vm_offset_t toff, tinc, size; 2255 vm_page_t m; 2256 vm_ooffset_t off; 2257 2258 ASSERT_VOP_LOCKED(vp, "inmem"); 2259 2260 if (incore(&vp->v_bufobj, blkno)) 2261 return 1; 2262 if (vp->v_mount == NULL) 2263 return 0; 2264 obj = vp->v_object; 2265 if (obj == NULL) 2266 return (0); 2267 2268 size = PAGE_SIZE; 2269 if (size > vp->v_mount->mnt_stat.f_iosize) 2270 size = vp->v_mount->mnt_stat.f_iosize; 2271 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2272 2273 VM_OBJECT_LOCK(obj); 2274 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2275 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2276 if (!m) 2277 goto notinmem; 2278 tinc = size; 2279 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2280 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2281 if (vm_page_is_valid(m, 2282 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2283 goto notinmem; 2284 } 2285 VM_OBJECT_UNLOCK(obj); 2286 return 1; 2287 2288 notinmem: 2289 VM_OBJECT_UNLOCK(obj); 2290 return (0); 2291 } 2292 2293 /* 2294 * vfs_setdirty: 2295 * 2296 * Sets the dirty range for a buffer based on the status of the dirty 2297 * bits in the pages comprising the buffer. 2298 * 2299 * The range is limited to the size of the buffer. 2300 * 2301 * This routine is primarily used by NFS, but is generalized for the 2302 * B_VMIO case. 2303 */ 2304 static void 2305 vfs_setdirty(struct buf *bp) 2306 { 2307 2308 /* 2309 * Degenerate case - empty buffer 2310 */ 2311 2312 if (bp->b_bufsize == 0) 2313 return; 2314 2315 /* 2316 * We qualify the scan for modified pages on whether the 2317 * object has been flushed yet. 2318 */ 2319 2320 if ((bp->b_flags & B_VMIO) == 0) 2321 return; 2322 2323 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2324 vfs_setdirty_locked_object(bp); 2325 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2326 } 2327 2328 static void 2329 vfs_setdirty_locked_object(struct buf *bp) 2330 { 2331 vm_object_t object; 2332 int i; 2333 2334 object = bp->b_bufobj->bo_object; 2335 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2336 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2337 vm_offset_t boffset; 2338 vm_offset_t eoffset; 2339 2340 vm_page_lock_queues(); 2341 /* 2342 * test the pages to see if they have been modified directly 2343 * by users through the VM system. 2344 */ 2345 for (i = 0; i < bp->b_npages; i++) 2346 vm_page_test_dirty(bp->b_pages[i]); 2347 2348 /* 2349 * Calculate the encompassing dirty range, boffset and eoffset, 2350 * (eoffset - boffset) bytes. 2351 */ 2352 2353 for (i = 0; i < bp->b_npages; i++) { 2354 if (bp->b_pages[i]->dirty) 2355 break; 2356 } 2357 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2358 2359 for (i = bp->b_npages - 1; i >= 0; --i) { 2360 if (bp->b_pages[i]->dirty) { 2361 break; 2362 } 2363 } 2364 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2365 2366 vm_page_unlock_queues(); 2367 /* 2368 * Fit it to the buffer. 2369 */ 2370 2371 if (eoffset > bp->b_bcount) 2372 eoffset = bp->b_bcount; 2373 2374 /* 2375 * If we have a good dirty range, merge with the existing 2376 * dirty range. 2377 */ 2378 2379 if (boffset < eoffset) { 2380 if (bp->b_dirtyoff > boffset) 2381 bp->b_dirtyoff = boffset; 2382 if (bp->b_dirtyend < eoffset) 2383 bp->b_dirtyend = eoffset; 2384 } 2385 } 2386 } 2387 2388 /* 2389 * getblk: 2390 * 2391 * Get a block given a specified block and offset into a file/device. 2392 * The buffers B_DONE bit will be cleared on return, making it almost 2393 * ready for an I/O initiation. B_INVAL may or may not be set on 2394 * return. The caller should clear B_INVAL prior to initiating a 2395 * READ. 2396 * 2397 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2398 * an existing buffer. 2399 * 2400 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2401 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2402 * and then cleared based on the backing VM. If the previous buffer is 2403 * non-0-sized but invalid, B_CACHE will be cleared. 2404 * 2405 * If getblk() must create a new buffer, the new buffer is returned with 2406 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2407 * case it is returned with B_INVAL clear and B_CACHE set based on the 2408 * backing VM. 2409 * 2410 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2411 * B_CACHE bit is clear. 2412 * 2413 * What this means, basically, is that the caller should use B_CACHE to 2414 * determine whether the buffer is fully valid or not and should clear 2415 * B_INVAL prior to issuing a read. If the caller intends to validate 2416 * the buffer by loading its data area with something, the caller needs 2417 * to clear B_INVAL. If the caller does this without issuing an I/O, 2418 * the caller should set B_CACHE ( as an optimization ), else the caller 2419 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2420 * a write attempt or if it was a successfull read. If the caller 2421 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2422 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2423 */ 2424 struct buf * 2425 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2426 int flags) 2427 { 2428 struct buf *bp; 2429 struct bufobj *bo; 2430 int error; 2431 2432 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2433 ASSERT_VOP_LOCKED(vp, "getblk"); 2434 if (size > MAXBSIZE) 2435 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2436 2437 bo = &vp->v_bufobj; 2438 loop: 2439 /* 2440 * Block if we are low on buffers. Certain processes are allowed 2441 * to completely exhaust the buffer cache. 2442 * 2443 * If this check ever becomes a bottleneck it may be better to 2444 * move it into the else, when gbincore() fails. At the moment 2445 * it isn't a problem. 2446 * 2447 * XXX remove if 0 sections (clean this up after its proven) 2448 */ 2449 if (numfreebuffers == 0) { 2450 if (TD_IS_IDLETHREAD(curthread)) 2451 return NULL; 2452 mtx_lock(&nblock); 2453 needsbuffer |= VFS_BIO_NEED_ANY; 2454 mtx_unlock(&nblock); 2455 } 2456 2457 BO_LOCK(bo); 2458 bp = gbincore(bo, blkno); 2459 if (bp != NULL) { 2460 int lockflags; 2461 /* 2462 * Buffer is in-core. If the buffer is not busy, it must 2463 * be on a queue. 2464 */ 2465 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2466 2467 if (flags & GB_LOCK_NOWAIT) 2468 lockflags |= LK_NOWAIT; 2469 2470 error = BUF_TIMELOCK(bp, lockflags, 2471 VI_MTX(vp), "getblk", slpflag, slptimeo); 2472 2473 /* 2474 * If we slept and got the lock we have to restart in case 2475 * the buffer changed identities. 2476 */ 2477 if (error == ENOLCK) 2478 goto loop; 2479 /* We timed out or were interrupted. */ 2480 else if (error) 2481 return (NULL); 2482 2483 /* 2484 * The buffer is locked. B_CACHE is cleared if the buffer is 2485 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2486 * and for a VMIO buffer B_CACHE is adjusted according to the 2487 * backing VM cache. 2488 */ 2489 if (bp->b_flags & B_INVAL) 2490 bp->b_flags &= ~B_CACHE; 2491 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2492 bp->b_flags |= B_CACHE; 2493 bremfree(bp); 2494 2495 /* 2496 * check for size inconsistancies for non-VMIO case. 2497 */ 2498 2499 if (bp->b_bcount != size) { 2500 if ((bp->b_flags & B_VMIO) == 0 || 2501 (size > bp->b_kvasize)) { 2502 if (bp->b_flags & B_DELWRI) { 2503 /* 2504 * If buffer is pinned and caller does 2505 * not want sleep waiting for it to be 2506 * unpinned, bail out 2507 * */ 2508 if (bp->b_pin_count > 0) { 2509 if (flags & GB_LOCK_NOWAIT) { 2510 bqrelse(bp); 2511 return (NULL); 2512 } else { 2513 bunpin_wait(bp); 2514 } 2515 } 2516 bp->b_flags |= B_NOCACHE; 2517 bwrite(bp); 2518 } else { 2519 if (LIST_EMPTY(&bp->b_dep)) { 2520 bp->b_flags |= B_RELBUF; 2521 brelse(bp); 2522 } else { 2523 bp->b_flags |= B_NOCACHE; 2524 bwrite(bp); 2525 } 2526 } 2527 goto loop; 2528 } 2529 } 2530 2531 /* 2532 * If the size is inconsistant in the VMIO case, we can resize 2533 * the buffer. This might lead to B_CACHE getting set or 2534 * cleared. If the size has not changed, B_CACHE remains 2535 * unchanged from its previous state. 2536 */ 2537 2538 if (bp->b_bcount != size) 2539 allocbuf(bp, size); 2540 2541 KASSERT(bp->b_offset != NOOFFSET, 2542 ("getblk: no buffer offset")); 2543 2544 /* 2545 * A buffer with B_DELWRI set and B_CACHE clear must 2546 * be committed before we can return the buffer in 2547 * order to prevent the caller from issuing a read 2548 * ( due to B_CACHE not being set ) and overwriting 2549 * it. 2550 * 2551 * Most callers, including NFS and FFS, need this to 2552 * operate properly either because they assume they 2553 * can issue a read if B_CACHE is not set, or because 2554 * ( for example ) an uncached B_DELWRI might loop due 2555 * to softupdates re-dirtying the buffer. In the latter 2556 * case, B_CACHE is set after the first write completes, 2557 * preventing further loops. 2558 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2559 * above while extending the buffer, we cannot allow the 2560 * buffer to remain with B_CACHE set after the write 2561 * completes or it will represent a corrupt state. To 2562 * deal with this we set B_NOCACHE to scrap the buffer 2563 * after the write. 2564 * 2565 * We might be able to do something fancy, like setting 2566 * B_CACHE in bwrite() except if B_DELWRI is already set, 2567 * so the below call doesn't set B_CACHE, but that gets real 2568 * confusing. This is much easier. 2569 */ 2570 2571 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2572 bp->b_flags |= B_NOCACHE; 2573 bwrite(bp); 2574 goto loop; 2575 } 2576 bp->b_flags &= ~B_DONE; 2577 } else { 2578 int bsize, maxsize, vmio; 2579 off_t offset; 2580 2581 /* 2582 * Buffer is not in-core, create new buffer. The buffer 2583 * returned by getnewbuf() is locked. Note that the returned 2584 * buffer is also considered valid (not marked B_INVAL). 2585 */ 2586 BO_UNLOCK(bo); 2587 /* 2588 * If the user does not want us to create the buffer, bail out 2589 * here. 2590 */ 2591 if (flags & GB_NOCREAT) 2592 return NULL; 2593 bsize = bo->bo_bsize; 2594 offset = blkno * bsize; 2595 vmio = vp->v_object != NULL; 2596 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2597 maxsize = imax(maxsize, bsize); 2598 2599 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2600 if (bp == NULL) { 2601 if (slpflag || slptimeo) 2602 return NULL; 2603 goto loop; 2604 } 2605 2606 /* 2607 * This code is used to make sure that a buffer is not 2608 * created while the getnewbuf routine is blocked. 2609 * This can be a problem whether the vnode is locked or not. 2610 * If the buffer is created out from under us, we have to 2611 * throw away the one we just created. 2612 * 2613 * Note: this must occur before we associate the buffer 2614 * with the vp especially considering limitations in 2615 * the splay tree implementation when dealing with duplicate 2616 * lblkno's. 2617 */ 2618 BO_LOCK(bo); 2619 if (gbincore(bo, blkno)) { 2620 BO_UNLOCK(bo); 2621 bp->b_flags |= B_INVAL; 2622 brelse(bp); 2623 goto loop; 2624 } 2625 2626 /* 2627 * Insert the buffer into the hash, so that it can 2628 * be found by incore. 2629 */ 2630 bp->b_blkno = bp->b_lblkno = blkno; 2631 bp->b_offset = offset; 2632 bgetvp(vp, bp); 2633 BO_UNLOCK(bo); 2634 2635 /* 2636 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2637 * buffer size starts out as 0, B_CACHE will be set by 2638 * allocbuf() for the VMIO case prior to it testing the 2639 * backing store for validity. 2640 */ 2641 2642 if (vmio) { 2643 bp->b_flags |= B_VMIO; 2644 #if defined(VFS_BIO_DEBUG) 2645 if (vn_canvmio(vp) != TRUE) 2646 printf("getblk: VMIO on vnode type %d\n", 2647 vp->v_type); 2648 #endif 2649 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2650 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2651 bp, vp->v_object, bp->b_bufobj->bo_object)); 2652 } else { 2653 bp->b_flags &= ~B_VMIO; 2654 KASSERT(bp->b_bufobj->bo_object == NULL, 2655 ("ARGH! has b_bufobj->bo_object %p %p\n", 2656 bp, bp->b_bufobj->bo_object)); 2657 } 2658 2659 allocbuf(bp, size); 2660 bp->b_flags &= ~B_DONE; 2661 } 2662 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2663 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2664 KASSERT(bp->b_bufobj == bo, 2665 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2666 return (bp); 2667 } 2668 2669 /* 2670 * Get an empty, disassociated buffer of given size. The buffer is initially 2671 * set to B_INVAL. 2672 */ 2673 struct buf * 2674 geteblk(int size) 2675 { 2676 struct buf *bp; 2677 int maxsize; 2678 2679 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2680 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2681 continue; 2682 allocbuf(bp, size); 2683 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2684 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2685 return (bp); 2686 } 2687 2688 2689 /* 2690 * This code constitutes the buffer memory from either anonymous system 2691 * memory (in the case of non-VMIO operations) or from an associated 2692 * VM object (in the case of VMIO operations). This code is able to 2693 * resize a buffer up or down. 2694 * 2695 * Note that this code is tricky, and has many complications to resolve 2696 * deadlock or inconsistant data situations. Tread lightly!!! 2697 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2698 * the caller. Calling this code willy nilly can result in the loss of data. 2699 * 2700 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2701 * B_CACHE for the non-VMIO case. 2702 */ 2703 2704 int 2705 allocbuf(struct buf *bp, int size) 2706 { 2707 int newbsize, mbsize; 2708 int i; 2709 2710 if (BUF_REFCNT(bp) == 0) 2711 panic("allocbuf: buffer not busy"); 2712 2713 if (bp->b_kvasize < size) 2714 panic("allocbuf: buffer too small"); 2715 2716 if ((bp->b_flags & B_VMIO) == 0) { 2717 caddr_t origbuf; 2718 int origbufsize; 2719 /* 2720 * Just get anonymous memory from the kernel. Don't 2721 * mess with B_CACHE. 2722 */ 2723 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2724 if (bp->b_flags & B_MALLOC) 2725 newbsize = mbsize; 2726 else 2727 newbsize = round_page(size); 2728 2729 if (newbsize < bp->b_bufsize) { 2730 /* 2731 * malloced buffers are not shrunk 2732 */ 2733 if (bp->b_flags & B_MALLOC) { 2734 if (newbsize) { 2735 bp->b_bcount = size; 2736 } else { 2737 free(bp->b_data, M_BIOBUF); 2738 if (bp->b_bufsize) { 2739 atomic_subtract_int( 2740 &bufmallocspace, 2741 bp->b_bufsize); 2742 bufspacewakeup(); 2743 bp->b_bufsize = 0; 2744 } 2745 bp->b_saveaddr = bp->b_kvabase; 2746 bp->b_data = bp->b_saveaddr; 2747 bp->b_bcount = 0; 2748 bp->b_flags &= ~B_MALLOC; 2749 } 2750 return 1; 2751 } 2752 vm_hold_free_pages( 2753 bp, 2754 (vm_offset_t) bp->b_data + newbsize, 2755 (vm_offset_t) bp->b_data + bp->b_bufsize); 2756 } else if (newbsize > bp->b_bufsize) { 2757 /* 2758 * We only use malloced memory on the first allocation. 2759 * and revert to page-allocated memory when the buffer 2760 * grows. 2761 */ 2762 /* 2763 * There is a potential smp race here that could lead 2764 * to bufmallocspace slightly passing the max. It 2765 * is probably extremely rare and not worth worrying 2766 * over. 2767 */ 2768 if ( (bufmallocspace < maxbufmallocspace) && 2769 (bp->b_bufsize == 0) && 2770 (mbsize <= PAGE_SIZE/2)) { 2771 2772 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2773 bp->b_bufsize = mbsize; 2774 bp->b_bcount = size; 2775 bp->b_flags |= B_MALLOC; 2776 atomic_add_int(&bufmallocspace, mbsize); 2777 return 1; 2778 } 2779 origbuf = NULL; 2780 origbufsize = 0; 2781 /* 2782 * If the buffer is growing on its other-than-first allocation, 2783 * then we revert to the page-allocation scheme. 2784 */ 2785 if (bp->b_flags & B_MALLOC) { 2786 origbuf = bp->b_data; 2787 origbufsize = bp->b_bufsize; 2788 bp->b_data = bp->b_kvabase; 2789 if (bp->b_bufsize) { 2790 atomic_subtract_int(&bufmallocspace, 2791 bp->b_bufsize); 2792 bufspacewakeup(); 2793 bp->b_bufsize = 0; 2794 } 2795 bp->b_flags &= ~B_MALLOC; 2796 newbsize = round_page(newbsize); 2797 } 2798 vm_hold_load_pages( 2799 bp, 2800 (vm_offset_t) bp->b_data + bp->b_bufsize, 2801 (vm_offset_t) bp->b_data + newbsize); 2802 if (origbuf) { 2803 bcopy(origbuf, bp->b_data, origbufsize); 2804 free(origbuf, M_BIOBUF); 2805 } 2806 } 2807 } else { 2808 int desiredpages; 2809 2810 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2811 desiredpages = (size == 0) ? 0 : 2812 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2813 2814 if (bp->b_flags & B_MALLOC) 2815 panic("allocbuf: VMIO buffer can't be malloced"); 2816 /* 2817 * Set B_CACHE initially if buffer is 0 length or will become 2818 * 0-length. 2819 */ 2820 if (size == 0 || bp->b_bufsize == 0) 2821 bp->b_flags |= B_CACHE; 2822 2823 if (newbsize < bp->b_bufsize) { 2824 /* 2825 * DEV_BSIZE aligned new buffer size is less then the 2826 * DEV_BSIZE aligned existing buffer size. Figure out 2827 * if we have to remove any pages. 2828 */ 2829 if (desiredpages < bp->b_npages) { 2830 vm_page_t m; 2831 2832 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2833 vm_page_lock_queues(); 2834 for (i = desiredpages; i < bp->b_npages; i++) { 2835 /* 2836 * the page is not freed here -- it 2837 * is the responsibility of 2838 * vnode_pager_setsize 2839 */ 2840 m = bp->b_pages[i]; 2841 KASSERT(m != bogus_page, 2842 ("allocbuf: bogus page found")); 2843 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2844 vm_page_lock_queues(); 2845 2846 bp->b_pages[i] = NULL; 2847 vm_page_unwire(m, 0); 2848 } 2849 vm_page_unlock_queues(); 2850 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2851 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2852 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2853 bp->b_npages = desiredpages; 2854 } 2855 } else if (size > bp->b_bcount) { 2856 /* 2857 * We are growing the buffer, possibly in a 2858 * byte-granular fashion. 2859 */ 2860 struct vnode *vp; 2861 vm_object_t obj; 2862 vm_offset_t toff; 2863 vm_offset_t tinc; 2864 2865 /* 2866 * Step 1, bring in the VM pages from the object, 2867 * allocating them if necessary. We must clear 2868 * B_CACHE if these pages are not valid for the 2869 * range covered by the buffer. 2870 */ 2871 2872 vp = bp->b_vp; 2873 obj = bp->b_bufobj->bo_object; 2874 2875 VM_OBJECT_LOCK(obj); 2876 while (bp->b_npages < desiredpages) { 2877 vm_page_t m; 2878 vm_pindex_t pi; 2879 2880 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2881 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2882 /* 2883 * note: must allocate system pages 2884 * since blocking here could intefere 2885 * with paging I/O, no matter which 2886 * process we are. 2887 */ 2888 m = vm_page_alloc(obj, pi, 2889 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2890 VM_ALLOC_WIRED); 2891 if (m == NULL) { 2892 atomic_add_int(&vm_pageout_deficit, 2893 desiredpages - bp->b_npages); 2894 VM_OBJECT_UNLOCK(obj); 2895 VM_WAIT; 2896 VM_OBJECT_LOCK(obj); 2897 } else { 2898 if (m->valid == 0) 2899 bp->b_flags &= ~B_CACHE; 2900 bp->b_pages[bp->b_npages] = m; 2901 ++bp->b_npages; 2902 } 2903 continue; 2904 } 2905 2906 /* 2907 * We found a page. If we have to sleep on it, 2908 * retry because it might have gotten freed out 2909 * from under us. 2910 * 2911 * We can only test VPO_BUSY here. Blocking on 2912 * m->busy might lead to a deadlock: 2913 * 2914 * vm_fault->getpages->cluster_read->allocbuf 2915 * 2916 */ 2917 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2918 continue; 2919 2920 /* 2921 * We have a good page. 2922 */ 2923 vm_page_lock_queues(); 2924 vm_page_wire(m); 2925 vm_page_unlock_queues(); 2926 bp->b_pages[bp->b_npages] = m; 2927 ++bp->b_npages; 2928 } 2929 2930 /* 2931 * Step 2. We've loaded the pages into the buffer, 2932 * we have to figure out if we can still have B_CACHE 2933 * set. Note that B_CACHE is set according to the 2934 * byte-granular range ( bcount and size ), new the 2935 * aligned range ( newbsize ). 2936 * 2937 * The VM test is against m->valid, which is DEV_BSIZE 2938 * aligned. Needless to say, the validity of the data 2939 * needs to also be DEV_BSIZE aligned. Note that this 2940 * fails with NFS if the server or some other client 2941 * extends the file's EOF. If our buffer is resized, 2942 * B_CACHE may remain set! XXX 2943 */ 2944 2945 toff = bp->b_bcount; 2946 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2947 2948 while ((bp->b_flags & B_CACHE) && toff < size) { 2949 vm_pindex_t pi; 2950 2951 if (tinc > (size - toff)) 2952 tinc = size - toff; 2953 2954 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2955 PAGE_SHIFT; 2956 2957 vfs_buf_test_cache( 2958 bp, 2959 bp->b_offset, 2960 toff, 2961 tinc, 2962 bp->b_pages[pi] 2963 ); 2964 toff += tinc; 2965 tinc = PAGE_SIZE; 2966 } 2967 VM_OBJECT_UNLOCK(obj); 2968 2969 /* 2970 * Step 3, fixup the KVM pmap. Remember that 2971 * bp->b_data is relative to bp->b_offset, but 2972 * bp->b_offset may be offset into the first page. 2973 */ 2974 2975 bp->b_data = (caddr_t) 2976 trunc_page((vm_offset_t)bp->b_data); 2977 pmap_qenter( 2978 (vm_offset_t)bp->b_data, 2979 bp->b_pages, 2980 bp->b_npages 2981 ); 2982 2983 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2984 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2985 } 2986 } 2987 if (newbsize < bp->b_bufsize) 2988 bufspacewakeup(); 2989 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2990 bp->b_bcount = size; /* requested buffer size */ 2991 return 1; 2992 } 2993 2994 void 2995 biodone(struct bio *bp) 2996 { 2997 void (*done)(struct bio *); 2998 2999 mtx_lock(&bdonelock); 3000 bp->bio_flags |= BIO_DONE; 3001 done = bp->bio_done; 3002 if (done == NULL) 3003 wakeup(bp); 3004 mtx_unlock(&bdonelock); 3005 if (done != NULL) 3006 done(bp); 3007 } 3008 3009 /* 3010 * Wait for a BIO to finish. 3011 * 3012 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3013 * case is not yet clear. 3014 */ 3015 int 3016 biowait(struct bio *bp, const char *wchan) 3017 { 3018 3019 mtx_lock(&bdonelock); 3020 while ((bp->bio_flags & BIO_DONE) == 0) 3021 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3022 mtx_unlock(&bdonelock); 3023 if (bp->bio_error != 0) 3024 return (bp->bio_error); 3025 if (!(bp->bio_flags & BIO_ERROR)) 3026 return (0); 3027 return (EIO); 3028 } 3029 3030 void 3031 biofinish(struct bio *bp, struct devstat *stat, int error) 3032 { 3033 3034 if (error) { 3035 bp->bio_error = error; 3036 bp->bio_flags |= BIO_ERROR; 3037 } 3038 if (stat != NULL) 3039 devstat_end_transaction_bio(stat, bp); 3040 biodone(bp); 3041 } 3042 3043 /* 3044 * bufwait: 3045 * 3046 * Wait for buffer I/O completion, returning error status. The buffer 3047 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3048 * error and cleared. 3049 */ 3050 int 3051 bufwait(struct buf *bp) 3052 { 3053 if (bp->b_iocmd == BIO_READ) 3054 bwait(bp, PRIBIO, "biord"); 3055 else 3056 bwait(bp, PRIBIO, "biowr"); 3057 if (bp->b_flags & B_EINTR) { 3058 bp->b_flags &= ~B_EINTR; 3059 return (EINTR); 3060 } 3061 if (bp->b_ioflags & BIO_ERROR) { 3062 return (bp->b_error ? bp->b_error : EIO); 3063 } else { 3064 return (0); 3065 } 3066 } 3067 3068 /* 3069 * Call back function from struct bio back up to struct buf. 3070 */ 3071 static void 3072 bufdonebio(struct bio *bip) 3073 { 3074 struct buf *bp; 3075 3076 bp = bip->bio_caller2; 3077 bp->b_resid = bp->b_bcount - bip->bio_completed; 3078 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3079 bp->b_ioflags = bip->bio_flags; 3080 bp->b_error = bip->bio_error; 3081 if (bp->b_error) 3082 bp->b_ioflags |= BIO_ERROR; 3083 bufdone(bp); 3084 g_destroy_bio(bip); 3085 } 3086 3087 void 3088 dev_strategy(struct cdev *dev, struct buf *bp) 3089 { 3090 struct cdevsw *csw; 3091 struct bio *bip; 3092 3093 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3094 panic("b_iocmd botch"); 3095 for (;;) { 3096 bip = g_new_bio(); 3097 if (bip != NULL) 3098 break; 3099 /* Try again later */ 3100 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3101 } 3102 bip->bio_cmd = bp->b_iocmd; 3103 bip->bio_offset = bp->b_iooffset; 3104 bip->bio_length = bp->b_bcount; 3105 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3106 bip->bio_data = bp->b_data; 3107 bip->bio_done = bufdonebio; 3108 bip->bio_caller2 = bp; 3109 bip->bio_dev = dev; 3110 KASSERT(dev->si_refcount > 0, 3111 ("dev_strategy on un-referenced struct cdev *(%s)", 3112 devtoname(dev))); 3113 csw = dev_refthread(dev); 3114 if (csw == NULL) { 3115 g_destroy_bio(bip); 3116 bp->b_error = ENXIO; 3117 bp->b_ioflags = BIO_ERROR; 3118 bufdone(bp); 3119 return; 3120 } 3121 (*csw->d_strategy)(bip); 3122 dev_relthread(dev); 3123 } 3124 3125 /* 3126 * bufdone: 3127 * 3128 * Finish I/O on a buffer, optionally calling a completion function. 3129 * This is usually called from an interrupt so process blocking is 3130 * not allowed. 3131 * 3132 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3133 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3134 * assuming B_INVAL is clear. 3135 * 3136 * For the VMIO case, we set B_CACHE if the op was a read and no 3137 * read error occured, or if the op was a write. B_CACHE is never 3138 * set if the buffer is invalid or otherwise uncacheable. 3139 * 3140 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3141 * initiator to leave B_INVAL set to brelse the buffer out of existance 3142 * in the biodone routine. 3143 */ 3144 void 3145 bufdone(struct buf *bp) 3146 { 3147 struct bufobj *dropobj; 3148 void (*biodone)(struct buf *); 3149 3150 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3151 dropobj = NULL; 3152 3153 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3154 BUF_REFCNT(bp))); 3155 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3156 3157 runningbufwakeup(bp); 3158 if (bp->b_iocmd == BIO_WRITE) 3159 dropobj = bp->b_bufobj; 3160 /* call optional completion function if requested */ 3161 if (bp->b_iodone != NULL) { 3162 biodone = bp->b_iodone; 3163 bp->b_iodone = NULL; 3164 (*biodone) (bp); 3165 if (dropobj) 3166 bufobj_wdrop(dropobj); 3167 return; 3168 } 3169 3170 bufdone_finish(bp); 3171 3172 if (dropobj) 3173 bufobj_wdrop(dropobj); 3174 } 3175 3176 void 3177 bufdone_finish(struct buf *bp) 3178 { 3179 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3180 BUF_REFCNT(bp))); 3181 3182 if (!LIST_EMPTY(&bp->b_dep)) 3183 buf_complete(bp); 3184 3185 if (bp->b_flags & B_VMIO) { 3186 int i; 3187 vm_ooffset_t foff; 3188 vm_page_t m; 3189 vm_object_t obj; 3190 int iosize; 3191 struct vnode *vp = bp->b_vp; 3192 boolean_t are_queues_locked; 3193 3194 obj = bp->b_bufobj->bo_object; 3195 3196 #if defined(VFS_BIO_DEBUG) 3197 mp_fixme("usecount and vflag accessed without locks."); 3198 if (vp->v_usecount == 0) { 3199 panic("biodone: zero vnode ref count"); 3200 } 3201 3202 KASSERT(vp->v_object != NULL, 3203 ("biodone: vnode %p has no vm_object", vp)); 3204 #endif 3205 3206 foff = bp->b_offset; 3207 KASSERT(bp->b_offset != NOOFFSET, 3208 ("biodone: no buffer offset")); 3209 3210 VM_OBJECT_LOCK(obj); 3211 #if defined(VFS_BIO_DEBUG) 3212 if (obj->paging_in_progress < bp->b_npages) { 3213 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3214 obj->paging_in_progress, bp->b_npages); 3215 } 3216 #endif 3217 3218 /* 3219 * Set B_CACHE if the op was a normal read and no error 3220 * occured. B_CACHE is set for writes in the b*write() 3221 * routines. 3222 */ 3223 iosize = bp->b_bcount - bp->b_resid; 3224 if (bp->b_iocmd == BIO_READ && 3225 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3226 !(bp->b_ioflags & BIO_ERROR)) { 3227 bp->b_flags |= B_CACHE; 3228 } 3229 if (bp->b_iocmd == BIO_READ) { 3230 vm_page_lock_queues(); 3231 are_queues_locked = TRUE; 3232 } else 3233 are_queues_locked = FALSE; 3234 for (i = 0; i < bp->b_npages; i++) { 3235 int bogusflag = 0; 3236 int resid; 3237 3238 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3239 if (resid > iosize) 3240 resid = iosize; 3241 3242 /* 3243 * cleanup bogus pages, restoring the originals 3244 */ 3245 m = bp->b_pages[i]; 3246 if (m == bogus_page) { 3247 bogusflag = 1; 3248 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3249 if (m == NULL) 3250 panic("biodone: page disappeared!"); 3251 bp->b_pages[i] = m; 3252 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3253 bp->b_pages, bp->b_npages); 3254 } 3255 #if defined(VFS_BIO_DEBUG) 3256 if (OFF_TO_IDX(foff) != m->pindex) { 3257 printf( 3258 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3259 (intmax_t)foff, (uintmax_t)m->pindex); 3260 } 3261 #endif 3262 3263 /* 3264 * In the write case, the valid and clean bits are 3265 * already changed correctly ( see bdwrite() ), so we 3266 * only need to do this here in the read case. 3267 */ 3268 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3269 vfs_page_set_valid(bp, foff, m); 3270 } 3271 3272 /* 3273 * when debugging new filesystems or buffer I/O methods, this 3274 * is the most common error that pops up. if you see this, you 3275 * have not set the page busy flag correctly!!! 3276 */ 3277 if (m->busy == 0) { 3278 printf("biodone: page busy < 0, " 3279 "pindex: %d, foff: 0x(%x,%x), " 3280 "resid: %d, index: %d\n", 3281 (int) m->pindex, (int)(foff >> 32), 3282 (int) foff & 0xffffffff, resid, i); 3283 if (!vn_isdisk(vp, NULL)) 3284 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3285 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3286 (intmax_t) bp->b_lblkno, 3287 bp->b_flags, bp->b_npages); 3288 else 3289 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3290 (intmax_t) bp->b_lblkno, 3291 bp->b_flags, bp->b_npages); 3292 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3293 (u_long)m->valid, (u_long)m->dirty, 3294 m->wire_count); 3295 panic("biodone: page busy < 0\n"); 3296 } 3297 vm_page_io_finish(m); 3298 vm_object_pip_subtract(obj, 1); 3299 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3300 iosize -= resid; 3301 } 3302 if (are_queues_locked) 3303 vm_page_unlock_queues(); 3304 vm_object_pip_wakeupn(obj, 0); 3305 VM_OBJECT_UNLOCK(obj); 3306 } 3307 3308 /* 3309 * For asynchronous completions, release the buffer now. The brelse 3310 * will do a wakeup there if necessary - so no need to do a wakeup 3311 * here in the async case. The sync case always needs to do a wakeup. 3312 */ 3313 3314 if (bp->b_flags & B_ASYNC) { 3315 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3316 brelse(bp); 3317 else 3318 bqrelse(bp); 3319 } else 3320 bdone(bp); 3321 } 3322 3323 /* 3324 * This routine is called in lieu of iodone in the case of 3325 * incomplete I/O. This keeps the busy status for pages 3326 * consistant. 3327 */ 3328 void 3329 vfs_unbusy_pages(struct buf *bp) 3330 { 3331 int i; 3332 vm_object_t obj; 3333 vm_page_t m; 3334 3335 runningbufwakeup(bp); 3336 if (!(bp->b_flags & B_VMIO)) 3337 return; 3338 3339 obj = bp->b_bufobj->bo_object; 3340 VM_OBJECT_LOCK(obj); 3341 for (i = 0; i < bp->b_npages; i++) { 3342 m = bp->b_pages[i]; 3343 if (m == bogus_page) { 3344 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3345 if (!m) 3346 panic("vfs_unbusy_pages: page missing\n"); 3347 bp->b_pages[i] = m; 3348 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3349 bp->b_pages, bp->b_npages); 3350 } 3351 vm_object_pip_subtract(obj, 1); 3352 vm_page_io_finish(m); 3353 } 3354 vm_object_pip_wakeupn(obj, 0); 3355 VM_OBJECT_UNLOCK(obj); 3356 } 3357 3358 /* 3359 * vfs_page_set_valid: 3360 * 3361 * Set the valid bits in a page based on the supplied offset. The 3362 * range is restricted to the buffer's size. 3363 * 3364 * This routine is typically called after a read completes. 3365 */ 3366 static void 3367 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3368 { 3369 vm_ooffset_t soff, eoff; 3370 3371 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3372 /* 3373 * Start and end offsets in buffer. eoff - soff may not cross a 3374 * page boundry or cross the end of the buffer. The end of the 3375 * buffer, in this case, is our file EOF, not the allocation size 3376 * of the buffer. 3377 */ 3378 soff = off; 3379 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3380 if (eoff > bp->b_offset + bp->b_bcount) 3381 eoff = bp->b_offset + bp->b_bcount; 3382 3383 /* 3384 * Set valid range. This is typically the entire buffer and thus the 3385 * entire page. 3386 */ 3387 if (eoff > soff) { 3388 vm_page_set_validclean( 3389 m, 3390 (vm_offset_t) (soff & PAGE_MASK), 3391 (vm_offset_t) (eoff - soff) 3392 ); 3393 } 3394 } 3395 3396 /* 3397 * This routine is called before a device strategy routine. 3398 * It is used to tell the VM system that paging I/O is in 3399 * progress, and treat the pages associated with the buffer 3400 * almost as being VPO_BUSY. Also the object paging_in_progress 3401 * flag is handled to make sure that the object doesn't become 3402 * inconsistant. 3403 * 3404 * Since I/O has not been initiated yet, certain buffer flags 3405 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3406 * and should be ignored. 3407 */ 3408 void 3409 vfs_busy_pages(struct buf *bp, int clear_modify) 3410 { 3411 int i, bogus; 3412 vm_object_t obj; 3413 vm_ooffset_t foff; 3414 vm_page_t m; 3415 3416 if (!(bp->b_flags & B_VMIO)) 3417 return; 3418 3419 obj = bp->b_bufobj->bo_object; 3420 foff = bp->b_offset; 3421 KASSERT(bp->b_offset != NOOFFSET, 3422 ("vfs_busy_pages: no buffer offset")); 3423 VM_OBJECT_LOCK(obj); 3424 if (bp->b_bufsize != 0) 3425 vfs_setdirty_locked_object(bp); 3426 retry: 3427 for (i = 0; i < bp->b_npages; i++) { 3428 m = bp->b_pages[i]; 3429 3430 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3431 goto retry; 3432 } 3433 bogus = 0; 3434 vm_page_lock_queues(); 3435 for (i = 0; i < bp->b_npages; i++) { 3436 m = bp->b_pages[i]; 3437 3438 if ((bp->b_flags & B_CLUSTER) == 0) { 3439 vm_object_pip_add(obj, 1); 3440 vm_page_io_start(m); 3441 } 3442 /* 3443 * When readying a buffer for a read ( i.e 3444 * clear_modify == 0 ), it is important to do 3445 * bogus_page replacement for valid pages in 3446 * partially instantiated buffers. Partially 3447 * instantiated buffers can, in turn, occur when 3448 * reconstituting a buffer from its VM backing store 3449 * base. We only have to do this if B_CACHE is 3450 * clear ( which causes the I/O to occur in the 3451 * first place ). The replacement prevents the read 3452 * I/O from overwriting potentially dirty VM-backed 3453 * pages. XXX bogus page replacement is, uh, bogus. 3454 * It may not work properly with small-block devices. 3455 * We need to find a better way. 3456 */ 3457 pmap_remove_all(m); 3458 if (clear_modify) 3459 vfs_page_set_valid(bp, foff, m); 3460 else if (m->valid == VM_PAGE_BITS_ALL && 3461 (bp->b_flags & B_CACHE) == 0) { 3462 bp->b_pages[i] = bogus_page; 3463 bogus++; 3464 } 3465 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3466 } 3467 vm_page_unlock_queues(); 3468 VM_OBJECT_UNLOCK(obj); 3469 if (bogus) 3470 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3471 bp->b_pages, bp->b_npages); 3472 } 3473 3474 /* 3475 * Tell the VM system that the pages associated with this buffer 3476 * are clean. This is used for delayed writes where the data is 3477 * going to go to disk eventually without additional VM intevention. 3478 * 3479 * Note that while we only really need to clean through to b_bcount, we 3480 * just go ahead and clean through to b_bufsize. 3481 */ 3482 static void 3483 vfs_clean_pages(struct buf *bp) 3484 { 3485 int i; 3486 vm_ooffset_t foff, noff, eoff; 3487 vm_page_t m; 3488 3489 if (!(bp->b_flags & B_VMIO)) 3490 return; 3491 3492 foff = bp->b_offset; 3493 KASSERT(bp->b_offset != NOOFFSET, 3494 ("vfs_clean_pages: no buffer offset")); 3495 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3496 vm_page_lock_queues(); 3497 for (i = 0; i < bp->b_npages; i++) { 3498 m = bp->b_pages[i]; 3499 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3500 eoff = noff; 3501 3502 if (eoff > bp->b_offset + bp->b_bufsize) 3503 eoff = bp->b_offset + bp->b_bufsize; 3504 vfs_page_set_valid(bp, foff, m); 3505 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3506 foff = noff; 3507 } 3508 vm_page_unlock_queues(); 3509 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3510 } 3511 3512 /* 3513 * vfs_bio_set_validclean: 3514 * 3515 * Set the range within the buffer to valid and clean. The range is 3516 * relative to the beginning of the buffer, b_offset. Note that b_offset 3517 * itself may be offset from the beginning of the first page. 3518 * 3519 */ 3520 3521 void 3522 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3523 { 3524 int i, n; 3525 vm_page_t m; 3526 3527 if (!(bp->b_flags & B_VMIO)) 3528 return; 3529 /* 3530 * Fixup base to be relative to beginning of first page. 3531 * Set initial n to be the maximum number of bytes in the 3532 * first page that can be validated. 3533 */ 3534 3535 base += (bp->b_offset & PAGE_MASK); 3536 n = PAGE_SIZE - (base & PAGE_MASK); 3537 3538 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3539 vm_page_lock_queues(); 3540 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3541 m = bp->b_pages[i]; 3542 if (n > size) 3543 n = size; 3544 vm_page_set_validclean(m, base & PAGE_MASK, n); 3545 base += n; 3546 size -= n; 3547 n = PAGE_SIZE; 3548 } 3549 vm_page_unlock_queues(); 3550 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3551 } 3552 3553 /* 3554 * vfs_bio_clrbuf: 3555 * 3556 * clear a buffer. This routine essentially fakes an I/O, so we need 3557 * to clear BIO_ERROR and B_INVAL. 3558 * 3559 * Note that while we only theoretically need to clear through b_bcount, 3560 * we go ahead and clear through b_bufsize. 3561 */ 3562 3563 void 3564 vfs_bio_clrbuf(struct buf *bp) 3565 { 3566 int i, j, mask = 0; 3567 caddr_t sa, ea; 3568 3569 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3570 clrbuf(bp); 3571 return; 3572 } 3573 3574 bp->b_flags &= ~B_INVAL; 3575 bp->b_ioflags &= ~BIO_ERROR; 3576 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3577 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3578 (bp->b_offset & PAGE_MASK) == 0) { 3579 if (bp->b_pages[0] == bogus_page) 3580 goto unlock; 3581 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3582 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3583 if ((bp->b_pages[0]->valid & mask) == mask) 3584 goto unlock; 3585 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3586 ((bp->b_pages[0]->valid & mask) == 0)) { 3587 bzero(bp->b_data, bp->b_bufsize); 3588 bp->b_pages[0]->valid |= mask; 3589 goto unlock; 3590 } 3591 } 3592 ea = sa = bp->b_data; 3593 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3594 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3595 ea = (caddr_t)(vm_offset_t)ulmin( 3596 (u_long)(vm_offset_t)ea, 3597 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3598 if (bp->b_pages[i] == bogus_page) 3599 continue; 3600 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3601 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3602 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3603 if ((bp->b_pages[i]->valid & mask) == mask) 3604 continue; 3605 if ((bp->b_pages[i]->valid & mask) == 0) { 3606 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3607 bzero(sa, ea - sa); 3608 } else { 3609 for (; sa < ea; sa += DEV_BSIZE, j++) { 3610 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3611 (bp->b_pages[i]->valid & (1 << j)) == 0) 3612 bzero(sa, DEV_BSIZE); 3613 } 3614 } 3615 bp->b_pages[i]->valid |= mask; 3616 } 3617 unlock: 3618 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3619 bp->b_resid = 0; 3620 } 3621 3622 /* 3623 * vm_hold_load_pages and vm_hold_free_pages get pages into 3624 * a buffers address space. The pages are anonymous and are 3625 * not associated with a file object. 3626 */ 3627 static void 3628 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3629 { 3630 vm_offset_t pg; 3631 vm_page_t p; 3632 int index; 3633 3634 to = round_page(to); 3635 from = round_page(from); 3636 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3637 3638 VM_OBJECT_LOCK(kernel_object); 3639 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3640 tryagain: 3641 /* 3642 * note: must allocate system pages since blocking here 3643 * could intefere with paging I/O, no matter which 3644 * process we are. 3645 */ 3646 p = vm_page_alloc(kernel_object, 3647 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3648 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3649 if (!p) { 3650 atomic_add_int(&vm_pageout_deficit, 3651 (to - pg) >> PAGE_SHIFT); 3652 VM_OBJECT_UNLOCK(kernel_object); 3653 VM_WAIT; 3654 VM_OBJECT_LOCK(kernel_object); 3655 goto tryagain; 3656 } 3657 p->valid = VM_PAGE_BITS_ALL; 3658 pmap_qenter(pg, &p, 1); 3659 bp->b_pages[index] = p; 3660 } 3661 VM_OBJECT_UNLOCK(kernel_object); 3662 bp->b_npages = index; 3663 } 3664 3665 /* Return pages associated with this buf to the vm system */ 3666 static void 3667 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3668 { 3669 vm_offset_t pg; 3670 vm_page_t p; 3671 int index, newnpages; 3672 3673 from = round_page(from); 3674 to = round_page(to); 3675 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3676 3677 VM_OBJECT_LOCK(kernel_object); 3678 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3679 p = bp->b_pages[index]; 3680 if (p && (index < bp->b_npages)) { 3681 if (p->busy) { 3682 printf( 3683 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3684 (intmax_t)bp->b_blkno, 3685 (intmax_t)bp->b_lblkno); 3686 } 3687 bp->b_pages[index] = NULL; 3688 pmap_qremove(pg, 1); 3689 vm_page_lock_queues(); 3690 vm_page_unwire(p, 0); 3691 vm_page_free(p); 3692 vm_page_unlock_queues(); 3693 } 3694 } 3695 VM_OBJECT_UNLOCK(kernel_object); 3696 bp->b_npages = newnpages; 3697 } 3698 3699 /* 3700 * Map an IO request into kernel virtual address space. 3701 * 3702 * All requests are (re)mapped into kernel VA space. 3703 * Notice that we use b_bufsize for the size of the buffer 3704 * to be mapped. b_bcount might be modified by the driver. 3705 * 3706 * Note that even if the caller determines that the address space should 3707 * be valid, a race or a smaller-file mapped into a larger space may 3708 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3709 * check the return value. 3710 */ 3711 int 3712 vmapbuf(struct buf *bp) 3713 { 3714 caddr_t addr, kva; 3715 vm_prot_t prot; 3716 int pidx, i; 3717 struct vm_page *m; 3718 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3719 3720 if (bp->b_bufsize < 0) 3721 return (-1); 3722 prot = VM_PROT_READ; 3723 if (bp->b_iocmd == BIO_READ) 3724 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3725 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3726 addr < bp->b_data + bp->b_bufsize; 3727 addr += PAGE_SIZE, pidx++) { 3728 /* 3729 * Do the vm_fault if needed; do the copy-on-write thing 3730 * when reading stuff off device into memory. 3731 * 3732 * NOTE! Must use pmap_extract() because addr may be in 3733 * the userland address space, and kextract is only guarenteed 3734 * to work for the kernland address space (see: sparc64 port). 3735 */ 3736 retry: 3737 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3738 prot) < 0) { 3739 vm_page_lock_queues(); 3740 for (i = 0; i < pidx; ++i) { 3741 vm_page_unhold(bp->b_pages[i]); 3742 bp->b_pages[i] = NULL; 3743 } 3744 vm_page_unlock_queues(); 3745 return(-1); 3746 } 3747 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3748 if (m == NULL) 3749 goto retry; 3750 bp->b_pages[pidx] = m; 3751 } 3752 if (pidx > btoc(MAXPHYS)) 3753 panic("vmapbuf: mapped more than MAXPHYS"); 3754 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3755 3756 kva = bp->b_saveaddr; 3757 bp->b_npages = pidx; 3758 bp->b_saveaddr = bp->b_data; 3759 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3760 return(0); 3761 } 3762 3763 /* 3764 * Free the io map PTEs associated with this IO operation. 3765 * We also invalidate the TLB entries and restore the original b_addr. 3766 */ 3767 void 3768 vunmapbuf(struct buf *bp) 3769 { 3770 int pidx; 3771 int npages; 3772 3773 npages = bp->b_npages; 3774 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3775 vm_page_lock_queues(); 3776 for (pidx = 0; pidx < npages; pidx++) 3777 vm_page_unhold(bp->b_pages[pidx]); 3778 vm_page_unlock_queues(); 3779 3780 bp->b_data = bp->b_saveaddr; 3781 } 3782 3783 void 3784 bdone(struct buf *bp) 3785 { 3786 3787 mtx_lock(&bdonelock); 3788 bp->b_flags |= B_DONE; 3789 wakeup(bp); 3790 mtx_unlock(&bdonelock); 3791 } 3792 3793 void 3794 bwait(struct buf *bp, u_char pri, const char *wchan) 3795 { 3796 3797 mtx_lock(&bdonelock); 3798 while ((bp->b_flags & B_DONE) == 0) 3799 msleep(bp, &bdonelock, pri, wchan, 0); 3800 mtx_unlock(&bdonelock); 3801 } 3802 3803 int 3804 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3805 { 3806 3807 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3808 } 3809 3810 void 3811 bufstrategy(struct bufobj *bo, struct buf *bp) 3812 { 3813 int i = 0; 3814 struct vnode *vp; 3815 3816 vp = bp->b_vp; 3817 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3818 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3819 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3820 i = VOP_STRATEGY(vp, bp); 3821 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3822 } 3823 3824 void 3825 bufobj_wrefl(struct bufobj *bo) 3826 { 3827 3828 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3829 ASSERT_BO_LOCKED(bo); 3830 bo->bo_numoutput++; 3831 } 3832 3833 void 3834 bufobj_wref(struct bufobj *bo) 3835 { 3836 3837 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3838 BO_LOCK(bo); 3839 bo->bo_numoutput++; 3840 BO_UNLOCK(bo); 3841 } 3842 3843 void 3844 bufobj_wdrop(struct bufobj *bo) 3845 { 3846 3847 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3848 BO_LOCK(bo); 3849 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3850 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3851 bo->bo_flag &= ~BO_WWAIT; 3852 wakeup(&bo->bo_numoutput); 3853 } 3854 BO_UNLOCK(bo); 3855 } 3856 3857 int 3858 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3859 { 3860 int error; 3861 3862 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3863 ASSERT_BO_LOCKED(bo); 3864 error = 0; 3865 while (bo->bo_numoutput) { 3866 bo->bo_flag |= BO_WWAIT; 3867 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3868 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3869 if (error) 3870 break; 3871 } 3872 return (error); 3873 } 3874 3875 void 3876 bpin(struct buf *bp) 3877 { 3878 mtx_lock(&bpinlock); 3879 bp->b_pin_count++; 3880 mtx_unlock(&bpinlock); 3881 } 3882 3883 void 3884 bunpin(struct buf *bp) 3885 { 3886 mtx_lock(&bpinlock); 3887 if (--bp->b_pin_count == 0) 3888 wakeup(bp); 3889 mtx_unlock(&bpinlock); 3890 } 3891 3892 void 3893 bunpin_wait(struct buf *bp) 3894 { 3895 mtx_lock(&bpinlock); 3896 while (bp->b_pin_count > 0) 3897 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3898 mtx_unlock(&bpinlock); 3899 } 3900 3901 #include "opt_ddb.h" 3902 #ifdef DDB 3903 #include <ddb/ddb.h> 3904 3905 /* DDB command to show buffer data */ 3906 DB_SHOW_COMMAND(buffer, db_show_buffer) 3907 { 3908 /* get args */ 3909 struct buf *bp = (struct buf *)addr; 3910 3911 if (!have_addr) { 3912 db_printf("usage: show buffer <addr>\n"); 3913 return; 3914 } 3915 3916 db_printf("buf at %p\n", bp); 3917 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3918 db_printf( 3919 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3920 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3921 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3922 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3923 if (bp->b_npages) { 3924 int i; 3925 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3926 for (i = 0; i < bp->b_npages; i++) { 3927 vm_page_t m; 3928 m = bp->b_pages[i]; 3929 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3930 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3931 if ((i + 1) < bp->b_npages) 3932 db_printf(","); 3933 } 3934 db_printf("\n"); 3935 } 3936 lockmgr_printinfo(&bp->b_lock); 3937 } 3938 3939 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3940 { 3941 struct buf *bp; 3942 int i; 3943 3944 for (i = 0; i < nbuf; i++) { 3945 bp = &buf[i]; 3946 if (lockcount(&bp->b_lock)) { 3947 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3948 db_printf("\n"); 3949 } 3950 } 3951 } 3952 #endif /* DDB */ 3953