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 && 1172 (bp->b_ioflags & BIO_ERROR) && 1173 bp->b_error != ENXIO && 1174 !(bp->b_flags & B_INVAL)) { 1175 /* 1176 * Failed write, redirty. Must clear BIO_ERROR to prevent 1177 * pages from being scrapped. If B_INVAL is set then 1178 * this case is not run and the next case is run to 1179 * destroy the buffer. B_INVAL can occur if the buffer 1180 * is outside the range supported by the underlying device. 1181 * If the error is that the device went away (ENXIO), we 1182 * shouldn't redirty the buffer either, but discard the 1183 * data too. 1184 */ 1185 bp->b_ioflags &= ~BIO_ERROR; 1186 bdirty(bp); 1187 } else if ((bp->b_flags & (B_NOCACHE | B_INVAL)) || 1188 (bp->b_ioflags & BIO_ERROR) || (bp->b_bufsize <= 0)) { 1189 /* 1190 * Either a failed I/O or we were asked to free or not 1191 * cache the buffer. 1192 */ 1193 bp->b_flags |= B_INVAL; 1194 if (!LIST_EMPTY(&bp->b_dep)) 1195 buf_deallocate(bp); 1196 if (bp->b_flags & B_DELWRI) { 1197 atomic_subtract_int(&numdirtybuffers, 1); 1198 numdirtywakeup(lodirtybuffers); 1199 } 1200 bp->b_flags &= ~(B_DELWRI | B_CACHE); 1201 if ((bp->b_flags & B_VMIO) == 0) { 1202 if (bp->b_bufsize) 1203 allocbuf(bp, 0); 1204 if (bp->b_vp) 1205 brelvp(bp); 1206 } 1207 } 1208 1209 /* 1210 * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() 1211 * is called with B_DELWRI set, the underlying pages may wind up 1212 * getting freed causing a previous write (bdwrite()) to get 'lost' 1213 * because pages associated with a B_DELWRI bp are marked clean. 1214 * 1215 * We still allow the B_INVAL case to call vfs_vmio_release(), even 1216 * if B_DELWRI is set. 1217 * 1218 * If B_DELWRI is not set we may have to set B_RELBUF if we are low 1219 * on pages to return pages to the VM page queues. 1220 */ 1221 if (bp->b_flags & B_DELWRI) 1222 bp->b_flags &= ~B_RELBUF; 1223 else if (vm_page_count_severe()) { 1224 /* 1225 * XXX This lock may not be necessary since BKGRDINPROG 1226 * cannot be set while we hold the buf lock, it can only be 1227 * cleared if it is already pending. 1228 */ 1229 if (bp->b_vp) { 1230 BO_LOCK(bp->b_bufobj); 1231 if (!(bp->b_vflags & BV_BKGRDINPROG)) 1232 bp->b_flags |= B_RELBUF; 1233 BO_UNLOCK(bp->b_bufobj); 1234 } else 1235 bp->b_flags |= B_RELBUF; 1236 } 1237 1238 /* 1239 * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer 1240 * constituted, not even NFS buffers now. Two flags effect this. If 1241 * B_INVAL, the struct buf is invalidated but the VM object is kept 1242 * around ( i.e. so it is trivial to reconstitute the buffer later ). 1243 * 1244 * If BIO_ERROR or B_NOCACHE is set, pages in the VM object will be 1245 * invalidated. BIO_ERROR cannot be set for a failed write unless the 1246 * buffer is also B_INVAL because it hits the re-dirtying code above. 1247 * 1248 * Normally we can do this whether a buffer is B_DELWRI or not. If 1249 * the buffer is an NFS buffer, it is tracking piecemeal writes or 1250 * the commit state and we cannot afford to lose the buffer. If the 1251 * buffer has a background write in progress, we need to keep it 1252 * around to prevent it from being reconstituted and starting a second 1253 * background write. 1254 */ 1255 if ((bp->b_flags & B_VMIO) 1256 && !(bp->b_vp->v_mount != NULL && 1257 (bp->b_vp->v_mount->mnt_vfc->vfc_flags & VFCF_NETWORK) != 0 && 1258 !vn_isdisk(bp->b_vp, NULL) && 1259 (bp->b_flags & B_DELWRI)) 1260 ) { 1261 1262 int i, j, resid; 1263 vm_page_t m; 1264 off_t foff; 1265 vm_pindex_t poff; 1266 vm_object_t obj; 1267 1268 obj = bp->b_bufobj->bo_object; 1269 1270 /* 1271 * Get the base offset and length of the buffer. Note that 1272 * in the VMIO case if the buffer block size is not 1273 * page-aligned then b_data pointer may not be page-aligned. 1274 * But our b_pages[] array *IS* page aligned. 1275 * 1276 * block sizes less then DEV_BSIZE (usually 512) are not 1277 * supported due to the page granularity bits (m->valid, 1278 * m->dirty, etc...). 1279 * 1280 * See man buf(9) for more information 1281 */ 1282 resid = bp->b_bufsize; 1283 foff = bp->b_offset; 1284 VM_OBJECT_LOCK(obj); 1285 for (i = 0; i < bp->b_npages; i++) { 1286 int had_bogus = 0; 1287 1288 m = bp->b_pages[i]; 1289 1290 /* 1291 * If we hit a bogus page, fixup *all* the bogus pages 1292 * now. 1293 */ 1294 if (m == bogus_page) { 1295 poff = OFF_TO_IDX(bp->b_offset); 1296 had_bogus = 1; 1297 1298 for (j = i; j < bp->b_npages; j++) { 1299 vm_page_t mtmp; 1300 mtmp = bp->b_pages[j]; 1301 if (mtmp == bogus_page) { 1302 mtmp = vm_page_lookup(obj, poff + j); 1303 if (!mtmp) { 1304 panic("brelse: page missing\n"); 1305 } 1306 bp->b_pages[j] = mtmp; 1307 } 1308 } 1309 1310 if ((bp->b_flags & B_INVAL) == 0) { 1311 pmap_qenter( 1312 trunc_page((vm_offset_t)bp->b_data), 1313 bp->b_pages, bp->b_npages); 1314 } 1315 m = bp->b_pages[i]; 1316 } 1317 if ((bp->b_flags & B_NOCACHE) || 1318 (bp->b_ioflags & BIO_ERROR)) { 1319 int poffset = foff & PAGE_MASK; 1320 int presid = resid > (PAGE_SIZE - poffset) ? 1321 (PAGE_SIZE - poffset) : resid; 1322 1323 KASSERT(presid >= 0, ("brelse: extra page")); 1324 vm_page_lock_queues(); 1325 vm_page_set_invalid(m, poffset, presid); 1326 vm_page_unlock_queues(); 1327 if (had_bogus) 1328 printf("avoided corruption bug in bogus_page/brelse code\n"); 1329 } 1330 resid -= PAGE_SIZE - (foff & PAGE_MASK); 1331 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 1332 } 1333 VM_OBJECT_UNLOCK(obj); 1334 if (bp->b_flags & (B_INVAL | B_RELBUF)) 1335 vfs_vmio_release(bp); 1336 1337 } else if (bp->b_flags & B_VMIO) { 1338 1339 if (bp->b_flags & (B_INVAL | B_RELBUF)) { 1340 vfs_vmio_release(bp); 1341 } 1342 1343 } else if ((bp->b_flags & (B_INVAL | B_RELBUF)) != 0) { 1344 if (bp->b_bufsize != 0) 1345 allocbuf(bp, 0); 1346 if (bp->b_vp != NULL) 1347 brelvp(bp); 1348 } 1349 1350 if (BUF_REFCNT(bp) > 1) { 1351 /* do not release to free list */ 1352 BUF_UNLOCK(bp); 1353 return; 1354 } 1355 1356 /* enqueue */ 1357 mtx_lock(&bqlock); 1358 /* Handle delayed bremfree() processing. */ 1359 if (bp->b_flags & B_REMFREE) 1360 bremfreel(bp); 1361 if (bp->b_qindex != QUEUE_NONE) 1362 panic("brelse: free buffer onto another queue???"); 1363 1364 /* buffers with no memory */ 1365 if (bp->b_bufsize == 0) { 1366 bp->b_flags |= B_INVAL; 1367 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1368 if (bp->b_vflags & BV_BKGRDINPROG) 1369 panic("losing buffer 1"); 1370 if (bp->b_kvasize) { 1371 bp->b_qindex = QUEUE_EMPTYKVA; 1372 } else { 1373 bp->b_qindex = QUEUE_EMPTY; 1374 } 1375 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1376 /* buffers with junk contents */ 1377 } else if (bp->b_flags & (B_INVAL | B_NOCACHE | B_RELBUF) || 1378 (bp->b_ioflags & BIO_ERROR)) { 1379 bp->b_flags |= B_INVAL; 1380 bp->b_xflags &= ~(BX_BKGRDWRITE | BX_ALTDATA); 1381 if (bp->b_vflags & BV_BKGRDINPROG) 1382 panic("losing buffer 2"); 1383 bp->b_qindex = QUEUE_CLEAN; 1384 TAILQ_INSERT_HEAD(&bufqueues[QUEUE_CLEAN], bp, b_freelist); 1385 /* remaining buffers */ 1386 } else { 1387 if ((bp->b_flags & (B_DELWRI|B_NEEDSGIANT)) == 1388 (B_DELWRI|B_NEEDSGIANT)) 1389 bp->b_qindex = QUEUE_DIRTY_GIANT; 1390 if (bp->b_flags & B_DELWRI) 1391 bp->b_qindex = QUEUE_DIRTY; 1392 else 1393 bp->b_qindex = QUEUE_CLEAN; 1394 if (bp->b_flags & B_AGE) 1395 TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); 1396 else 1397 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1398 } 1399 mtx_unlock(&bqlock); 1400 1401 /* 1402 * If B_INVAL and B_DELWRI is set, clear B_DELWRI. We have already 1403 * placed the buffer on the correct queue. We must also disassociate 1404 * the device and vnode for a B_INVAL buffer so gbincore() doesn't 1405 * find it. 1406 */ 1407 if (bp->b_flags & B_INVAL) { 1408 if (bp->b_flags & B_DELWRI) 1409 bundirty(bp); 1410 if (bp->b_vp) 1411 brelvp(bp); 1412 } 1413 1414 /* 1415 * Fixup numfreebuffers count. The bp is on an appropriate queue 1416 * unless locked. We then bump numfreebuffers if it is not B_DELWRI. 1417 * We've already handled the B_INVAL case ( B_DELWRI will be clear 1418 * if B_INVAL is set ). 1419 */ 1420 1421 if (!(bp->b_flags & B_DELWRI)) 1422 bufcountwakeup(); 1423 1424 /* 1425 * Something we can maybe free or reuse 1426 */ 1427 if (bp->b_bufsize || bp->b_kvasize) 1428 bufspacewakeup(); 1429 1430 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT); 1431 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1432 panic("brelse: not dirty"); 1433 /* unlock */ 1434 BUF_UNLOCK(bp); 1435 } 1436 1437 /* 1438 * Release a buffer back to the appropriate queue but do not try to free 1439 * it. The buffer is expected to be used again soon. 1440 * 1441 * bqrelse() is used by bdwrite() to requeue a delayed write, and used by 1442 * biodone() to requeue an async I/O on completion. It is also used when 1443 * known good buffers need to be requeued but we think we may need the data 1444 * again soon. 1445 * 1446 * XXX we should be able to leave the B_RELBUF hint set on completion. 1447 */ 1448 void 1449 bqrelse(struct buf *bp) 1450 { 1451 CTR3(KTR_BUF, "bqrelse(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 1452 KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), 1453 ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); 1454 1455 if (BUF_REFCNT(bp) > 1) { 1456 /* do not release to free list */ 1457 BUF_UNLOCK(bp); 1458 return; 1459 } 1460 1461 if (bp->b_flags & B_MANAGED) { 1462 if (bp->b_flags & B_REMFREE) { 1463 mtx_lock(&bqlock); 1464 bremfreel(bp); 1465 mtx_unlock(&bqlock); 1466 } 1467 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1468 BUF_UNLOCK(bp); 1469 return; 1470 } 1471 1472 mtx_lock(&bqlock); 1473 /* Handle delayed bremfree() processing. */ 1474 if (bp->b_flags & B_REMFREE) 1475 bremfreel(bp); 1476 if (bp->b_qindex != QUEUE_NONE) 1477 panic("bqrelse: free buffer onto another queue???"); 1478 /* buffers with stale but valid contents */ 1479 if (bp->b_flags & B_DELWRI) { 1480 if (bp->b_flags & B_NEEDSGIANT) 1481 bp->b_qindex = QUEUE_DIRTY_GIANT; 1482 else 1483 bp->b_qindex = QUEUE_DIRTY; 1484 TAILQ_INSERT_TAIL(&bufqueues[bp->b_qindex], bp, b_freelist); 1485 } else { 1486 /* 1487 * XXX This lock may not be necessary since BKGRDINPROG 1488 * cannot be set while we hold the buf lock, it can only be 1489 * cleared if it is already pending. 1490 */ 1491 BO_LOCK(bp->b_bufobj); 1492 if (!vm_page_count_severe() || bp->b_vflags & BV_BKGRDINPROG) { 1493 BO_UNLOCK(bp->b_bufobj); 1494 bp->b_qindex = QUEUE_CLEAN; 1495 TAILQ_INSERT_TAIL(&bufqueues[QUEUE_CLEAN], bp, 1496 b_freelist); 1497 } else { 1498 /* 1499 * We are too low on memory, we have to try to free 1500 * the buffer (most importantly: the wired pages 1501 * making up its backing store) *now*. 1502 */ 1503 BO_UNLOCK(bp->b_bufobj); 1504 mtx_unlock(&bqlock); 1505 brelse(bp); 1506 return; 1507 } 1508 } 1509 mtx_unlock(&bqlock); 1510 1511 if ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI)) 1512 bufcountwakeup(); 1513 1514 /* 1515 * Something we can maybe free or reuse. 1516 */ 1517 if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) 1518 bufspacewakeup(); 1519 1520 bp->b_flags &= ~(B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); 1521 if ((bp->b_flags & B_DELWRI) == 0 && (bp->b_xflags & BX_VNDIRTY)) 1522 panic("bqrelse: not dirty"); 1523 /* unlock */ 1524 BUF_UNLOCK(bp); 1525 } 1526 1527 /* Give pages used by the bp back to the VM system (where possible) */ 1528 static void 1529 vfs_vmio_release(struct buf *bp) 1530 { 1531 int i; 1532 vm_page_t m; 1533 1534 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 1535 vm_page_lock_queues(); 1536 for (i = 0; i < bp->b_npages; i++) { 1537 m = bp->b_pages[i]; 1538 bp->b_pages[i] = NULL; 1539 /* 1540 * In order to keep page LRU ordering consistent, put 1541 * everything on the inactive queue. 1542 */ 1543 vm_page_unwire(m, 0); 1544 /* 1545 * We don't mess with busy pages, it is 1546 * the responsibility of the process that 1547 * busied the pages to deal with them. 1548 */ 1549 if ((m->oflags & VPO_BUSY) || (m->busy != 0)) 1550 continue; 1551 1552 if (m->wire_count == 0) { 1553 /* 1554 * Might as well free the page if we can and it has 1555 * no valid data. We also free the page if the 1556 * buffer was used for direct I/O 1557 */ 1558 if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && 1559 m->hold_count == 0) { 1560 vm_page_free(m); 1561 } else if (bp->b_flags & B_DIRECT) { 1562 vm_page_try_to_free(m); 1563 } else if (vm_page_count_severe()) { 1564 vm_page_try_to_cache(m); 1565 } 1566 } 1567 } 1568 vm_page_unlock_queues(); 1569 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 1570 pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_npages); 1571 1572 if (bp->b_bufsize) { 1573 bufspacewakeup(); 1574 bp->b_bufsize = 0; 1575 } 1576 bp->b_npages = 0; 1577 bp->b_flags &= ~B_VMIO; 1578 if (bp->b_vp) 1579 brelvp(bp); 1580 } 1581 1582 /* 1583 * Check to see if a block at a particular lbn is available for a clustered 1584 * write. 1585 */ 1586 static int 1587 vfs_bio_clcheck(struct vnode *vp, int size, daddr_t lblkno, daddr_t blkno) 1588 { 1589 struct buf *bpa; 1590 int match; 1591 1592 match = 0; 1593 1594 /* If the buf isn't in core skip it */ 1595 if ((bpa = gbincore(&vp->v_bufobj, lblkno)) == NULL) 1596 return (0); 1597 1598 /* If the buf is busy we don't want to wait for it */ 1599 if (BUF_LOCK(bpa, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1600 return (0); 1601 1602 /* Only cluster with valid clusterable delayed write buffers */ 1603 if ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) != 1604 (B_DELWRI | B_CLUSTEROK)) 1605 goto done; 1606 1607 if (bpa->b_bufsize != size) 1608 goto done; 1609 1610 /* 1611 * Check to see if it is in the expected place on disk and that the 1612 * block has been mapped. 1613 */ 1614 if ((bpa->b_blkno != bpa->b_lblkno) && (bpa->b_blkno == blkno)) 1615 match = 1; 1616 done: 1617 BUF_UNLOCK(bpa); 1618 return (match); 1619 } 1620 1621 /* 1622 * vfs_bio_awrite: 1623 * 1624 * Implement clustered async writes for clearing out B_DELWRI buffers. 1625 * This is much better then the old way of writing only one buffer at 1626 * a time. Note that we may not be presented with the buffers in the 1627 * correct order, so we search for the cluster in both directions. 1628 */ 1629 int 1630 vfs_bio_awrite(struct buf *bp) 1631 { 1632 int i; 1633 int j; 1634 daddr_t lblkno = bp->b_lblkno; 1635 struct vnode *vp = bp->b_vp; 1636 int ncl; 1637 int nwritten; 1638 int size; 1639 int maxcl; 1640 1641 /* 1642 * right now we support clustered writing only to regular files. If 1643 * we find a clusterable block we could be in the middle of a cluster 1644 * rather then at the beginning. 1645 */ 1646 if ((vp->v_type == VREG) && 1647 (vp->v_mount != 0) && /* Only on nodes that have the size info */ 1648 (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { 1649 1650 size = vp->v_mount->mnt_stat.f_iosize; 1651 maxcl = MAXPHYS / size; 1652 1653 VI_LOCK(vp); 1654 for (i = 1; i < maxcl; i++) 1655 if (vfs_bio_clcheck(vp, size, lblkno + i, 1656 bp->b_blkno + ((i * size) >> DEV_BSHIFT)) == 0) 1657 break; 1658 1659 for (j = 1; i + j <= maxcl && j <= lblkno; j++) 1660 if (vfs_bio_clcheck(vp, size, lblkno - j, 1661 bp->b_blkno - ((j * size) >> DEV_BSHIFT)) == 0) 1662 break; 1663 1664 VI_UNLOCK(vp); 1665 --j; 1666 ncl = i + j; 1667 /* 1668 * this is a possible cluster write 1669 */ 1670 if (ncl != 1) { 1671 BUF_UNLOCK(bp); 1672 nwritten = cluster_wbuild(vp, size, lblkno - j, ncl); 1673 return nwritten; 1674 } 1675 } 1676 bremfree(bp); 1677 bp->b_flags |= B_ASYNC; 1678 /* 1679 * default (old) behavior, writing out only one block 1680 * 1681 * XXX returns b_bufsize instead of b_bcount for nwritten? 1682 */ 1683 nwritten = bp->b_bufsize; 1684 (void) bwrite(bp); 1685 1686 return nwritten; 1687 } 1688 1689 /* 1690 * getnewbuf: 1691 * 1692 * Find and initialize a new buffer header, freeing up existing buffers 1693 * in the bufqueues as necessary. The new buffer is returned locked. 1694 * 1695 * Important: B_INVAL is not set. If the caller wishes to throw the 1696 * buffer away, the caller must set B_INVAL prior to calling brelse(). 1697 * 1698 * We block if: 1699 * We have insufficient buffer headers 1700 * We have insufficient buffer space 1701 * buffer_map is too fragmented ( space reservation fails ) 1702 * If we have to flush dirty buffers ( but we try to avoid this ) 1703 * 1704 * To avoid VFS layer recursion we do not flush dirty buffers ourselves. 1705 * Instead we ask the buf daemon to do it for us. We attempt to 1706 * avoid piecemeal wakeups of the pageout daemon. 1707 */ 1708 1709 static struct buf * 1710 getnewbuf(int slpflag, int slptimeo, int size, int maxsize) 1711 { 1712 struct buf *bp; 1713 struct buf *nbp; 1714 int defrag = 0; 1715 int nqindex; 1716 static int flushingbufs; 1717 1718 /* 1719 * We can't afford to block since we might be holding a vnode lock, 1720 * which may prevent system daemons from running. We deal with 1721 * low-memory situations by proactively returning memory and running 1722 * async I/O rather then sync I/O. 1723 */ 1724 1725 atomic_add_int(&getnewbufcalls, 1); 1726 atomic_subtract_int(&getnewbufrestarts, 1); 1727 restart: 1728 atomic_add_int(&getnewbufrestarts, 1); 1729 1730 /* 1731 * Setup for scan. If we do not have enough free buffers, 1732 * we setup a degenerate case that immediately fails. Note 1733 * that if we are specially marked process, we are allowed to 1734 * dip into our reserves. 1735 * 1736 * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN 1737 * 1738 * We start with EMPTYKVA. If the list is empty we backup to EMPTY. 1739 * However, there are a number of cases (defragging, reusing, ...) 1740 * where we cannot backup. 1741 */ 1742 mtx_lock(&bqlock); 1743 nqindex = QUEUE_EMPTYKVA; 1744 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]); 1745 1746 if (nbp == NULL) { 1747 /* 1748 * If no EMPTYKVA buffers and we are either 1749 * defragging or reusing, locate a CLEAN buffer 1750 * to free or reuse. If bufspace useage is low 1751 * skip this step so we can allocate a new buffer. 1752 */ 1753 if (defrag || bufspace >= lobufspace) { 1754 nqindex = QUEUE_CLEAN; 1755 nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]); 1756 } 1757 1758 /* 1759 * If we could not find or were not allowed to reuse a 1760 * CLEAN buffer, check to see if it is ok to use an EMPTY 1761 * buffer. We can only use an EMPTY buffer if allocating 1762 * its KVA would not otherwise run us out of buffer space. 1763 */ 1764 if (nbp == NULL && defrag == 0 && 1765 bufspace + maxsize < hibufspace) { 1766 nqindex = QUEUE_EMPTY; 1767 nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTY]); 1768 } 1769 } 1770 1771 /* 1772 * Run scan, possibly freeing data and/or kva mappings on the fly 1773 * depending. 1774 */ 1775 1776 while ((bp = nbp) != NULL) { 1777 int qindex = nqindex; 1778 1779 /* 1780 * Calculate next bp ( we can only use it if we do not block 1781 * or do other fancy things ). 1782 */ 1783 if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { 1784 switch(qindex) { 1785 case QUEUE_EMPTY: 1786 nqindex = QUEUE_EMPTYKVA; 1787 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_EMPTYKVA]))) 1788 break; 1789 /* FALLTHROUGH */ 1790 case QUEUE_EMPTYKVA: 1791 nqindex = QUEUE_CLEAN; 1792 if ((nbp = TAILQ_FIRST(&bufqueues[QUEUE_CLEAN]))) 1793 break; 1794 /* FALLTHROUGH */ 1795 case QUEUE_CLEAN: 1796 /* 1797 * nbp is NULL. 1798 */ 1799 break; 1800 } 1801 } 1802 /* 1803 * If we are defragging then we need a buffer with 1804 * b_kvasize != 0. XXX this situation should no longer 1805 * occur, if defrag is non-zero the buffer's b_kvasize 1806 * should also be non-zero at this point. XXX 1807 */ 1808 if (defrag && bp->b_kvasize == 0) { 1809 printf("Warning: defrag empty buffer %p\n", bp); 1810 continue; 1811 } 1812 1813 /* 1814 * Start freeing the bp. This is somewhat involved. nbp 1815 * remains valid only for QUEUE_EMPTY[KVA] bp's. 1816 */ 1817 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 1818 continue; 1819 if (bp->b_vp) { 1820 BO_LOCK(bp->b_bufobj); 1821 if (bp->b_vflags & BV_BKGRDINPROG) { 1822 BO_UNLOCK(bp->b_bufobj); 1823 BUF_UNLOCK(bp); 1824 continue; 1825 } 1826 BO_UNLOCK(bp->b_bufobj); 1827 } 1828 CTR6(KTR_BUF, 1829 "getnewbuf(%p) vp %p flags %X kvasize %d bufsize %d " 1830 "queue %d (recycling)", bp, bp->b_vp, bp->b_flags, 1831 bp->b_kvasize, bp->b_bufsize, qindex); 1832 1833 /* 1834 * Sanity Checks 1835 */ 1836 KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); 1837 1838 /* 1839 * Note: we no longer distinguish between VMIO and non-VMIO 1840 * buffers. 1841 */ 1842 1843 KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); 1844 1845 bremfreel(bp); 1846 mtx_unlock(&bqlock); 1847 1848 if (qindex == QUEUE_CLEAN) { 1849 if (bp->b_flags & B_VMIO) { 1850 bp->b_flags &= ~B_ASYNC; 1851 vfs_vmio_release(bp); 1852 } 1853 if (bp->b_vp) 1854 brelvp(bp); 1855 } 1856 1857 /* 1858 * NOTE: nbp is now entirely invalid. We can only restart 1859 * the scan from this point on. 1860 * 1861 * Get the rest of the buffer freed up. b_kva* is still 1862 * valid after this operation. 1863 */ 1864 1865 if (bp->b_rcred != NOCRED) { 1866 crfree(bp->b_rcred); 1867 bp->b_rcred = NOCRED; 1868 } 1869 if (bp->b_wcred != NOCRED) { 1870 crfree(bp->b_wcred); 1871 bp->b_wcred = NOCRED; 1872 } 1873 if (!LIST_EMPTY(&bp->b_dep)) 1874 buf_deallocate(bp); 1875 if (bp->b_vflags & BV_BKGRDINPROG) 1876 panic("losing buffer 3"); 1877 KASSERT(bp->b_vp == NULL, 1878 ("bp: %p still has vnode %p. qindex: %d", 1879 bp, bp->b_vp, qindex)); 1880 KASSERT((bp->b_xflags & (BX_VNCLEAN|BX_VNDIRTY)) == 0, 1881 ("bp: %p still on a buffer list. xflags %X", 1882 bp, bp->b_xflags)); 1883 1884 if (bp->b_bufsize) 1885 allocbuf(bp, 0); 1886 1887 bp->b_flags = 0; 1888 bp->b_ioflags = 0; 1889 bp->b_xflags = 0; 1890 bp->b_vflags = 0; 1891 bp->b_vp = NULL; 1892 bp->b_blkno = bp->b_lblkno = 0; 1893 bp->b_offset = NOOFFSET; 1894 bp->b_iodone = 0; 1895 bp->b_error = 0; 1896 bp->b_resid = 0; 1897 bp->b_bcount = 0; 1898 bp->b_npages = 0; 1899 bp->b_dirtyoff = bp->b_dirtyend = 0; 1900 bp->b_bufobj = NULL; 1901 bp->b_pin_count = 0; 1902 bp->b_fsprivate1 = NULL; 1903 bp->b_fsprivate2 = NULL; 1904 bp->b_fsprivate3 = NULL; 1905 1906 LIST_INIT(&bp->b_dep); 1907 1908 /* 1909 * If we are defragging then free the buffer. 1910 */ 1911 if (defrag) { 1912 bp->b_flags |= B_INVAL; 1913 bfreekva(bp); 1914 brelse(bp); 1915 defrag = 0; 1916 goto restart; 1917 } 1918 1919 /* 1920 * Notify any waiters for the buffer lock about 1921 * identity change by freeing the buffer. 1922 */ 1923 if (qindex == QUEUE_CLEAN && BUF_LOCKWAITERS(bp) > 0) { 1924 bp->b_flags |= B_INVAL; 1925 bfreekva(bp); 1926 brelse(bp); 1927 goto restart; 1928 } 1929 1930 /* 1931 * If we are overcomitted then recover the buffer and its 1932 * KVM space. This occurs in rare situations when multiple 1933 * processes are blocked in getnewbuf() or allocbuf(). 1934 */ 1935 if (bufspace >= hibufspace) 1936 flushingbufs = 1; 1937 if (flushingbufs && bp->b_kvasize != 0) { 1938 bp->b_flags |= B_INVAL; 1939 bfreekva(bp); 1940 brelse(bp); 1941 goto restart; 1942 } 1943 if (bufspace < lobufspace) 1944 flushingbufs = 0; 1945 break; 1946 } 1947 1948 /* 1949 * If we exhausted our list, sleep as appropriate. We may have to 1950 * wakeup various daemons and write out some dirty buffers. 1951 * 1952 * Generally we are sleeping due to insufficient buffer space. 1953 */ 1954 1955 if (bp == NULL) { 1956 int flags; 1957 char *waitmsg; 1958 1959 if (defrag) { 1960 flags = VFS_BIO_NEED_BUFSPACE; 1961 waitmsg = "nbufkv"; 1962 } else if (bufspace >= hibufspace) { 1963 waitmsg = "nbufbs"; 1964 flags = VFS_BIO_NEED_BUFSPACE; 1965 } else { 1966 waitmsg = "newbuf"; 1967 flags = VFS_BIO_NEED_ANY; 1968 } 1969 mtx_lock(&nblock); 1970 needsbuffer |= flags; 1971 mtx_unlock(&nblock); 1972 mtx_unlock(&bqlock); 1973 1974 bd_speedup(); /* heeeelp */ 1975 1976 mtx_lock(&nblock); 1977 while (needsbuffer & flags) { 1978 if (msleep(&needsbuffer, &nblock, 1979 (PRIBIO + 4) | slpflag, waitmsg, slptimeo)) { 1980 mtx_unlock(&nblock); 1981 return (NULL); 1982 } 1983 } 1984 mtx_unlock(&nblock); 1985 } else { 1986 /* 1987 * We finally have a valid bp. We aren't quite out of the 1988 * woods, we still have to reserve kva space. In order 1989 * to keep fragmentation sane we only allocate kva in 1990 * BKVASIZE chunks. 1991 */ 1992 maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; 1993 1994 if (maxsize != bp->b_kvasize) { 1995 vm_offset_t addr = 0; 1996 1997 bfreekva(bp); 1998 1999 vm_map_lock(buffer_map); 2000 if (vm_map_findspace(buffer_map, 2001 vm_map_min(buffer_map), maxsize, &addr)) { 2002 /* 2003 * Uh oh. Buffer map is to fragmented. We 2004 * must defragment the map. 2005 */ 2006 atomic_add_int(&bufdefragcnt, 1); 2007 vm_map_unlock(buffer_map); 2008 defrag = 1; 2009 bp->b_flags |= B_INVAL; 2010 brelse(bp); 2011 goto restart; 2012 } 2013 if (addr) { 2014 vm_map_insert(buffer_map, NULL, 0, 2015 addr, addr + maxsize, 2016 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 2017 2018 bp->b_kvabase = (caddr_t) addr; 2019 bp->b_kvasize = maxsize; 2020 atomic_add_int(&bufspace, bp->b_kvasize); 2021 atomic_add_int(&bufreusecnt, 1); 2022 } 2023 vm_map_unlock(buffer_map); 2024 } 2025 bp->b_saveaddr = bp->b_kvabase; 2026 bp->b_data = bp->b_saveaddr; 2027 } 2028 return(bp); 2029 } 2030 2031 /* 2032 * buf_daemon: 2033 * 2034 * buffer flushing daemon. Buffers are normally flushed by the 2035 * update daemon but if it cannot keep up this process starts to 2036 * take the load in an attempt to prevent getnewbuf() from blocking. 2037 */ 2038 2039 static struct kproc_desc buf_kp = { 2040 "bufdaemon", 2041 buf_daemon, 2042 &bufdaemonproc 2043 }; 2044 SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) 2045 2046 static void 2047 buf_daemon() 2048 { 2049 2050 /* 2051 * This process needs to be suspended prior to shutdown sync. 2052 */ 2053 EVENTHANDLER_REGISTER(shutdown_pre_sync, kproc_shutdown, bufdaemonproc, 2054 SHUTDOWN_PRI_LAST); 2055 2056 /* 2057 * This process is allowed to take the buffer cache to the limit 2058 */ 2059 curthread->td_pflags |= TDP_NORUNNINGBUF; 2060 mtx_lock(&bdlock); 2061 for (;;) { 2062 bd_request = 0; 2063 mtx_unlock(&bdlock); 2064 2065 kproc_suspend_check(bufdaemonproc); 2066 2067 /* 2068 * Do the flush. Limit the amount of in-transit I/O we 2069 * allow to build up, otherwise we would completely saturate 2070 * the I/O system. Wakeup any waiting processes before we 2071 * normally would so they can run in parallel with our drain. 2072 */ 2073 while (numdirtybuffers > lodirtybuffers) { 2074 int flushed; 2075 2076 flushed = flushbufqueues(QUEUE_DIRTY, 0); 2077 /* The list empty check here is slightly racy */ 2078 if (!TAILQ_EMPTY(&bufqueues[QUEUE_DIRTY_GIANT])) { 2079 mtx_lock(&Giant); 2080 flushed += flushbufqueues(QUEUE_DIRTY_GIANT, 0); 2081 mtx_unlock(&Giant); 2082 } 2083 if (flushed == 0) { 2084 /* 2085 * Could not find any buffers without rollback 2086 * dependencies, so just write the first one 2087 * in the hopes of eventually making progress. 2088 */ 2089 flushbufqueues(QUEUE_DIRTY, 1); 2090 if (!TAILQ_EMPTY( 2091 &bufqueues[QUEUE_DIRTY_GIANT])) { 2092 mtx_lock(&Giant); 2093 flushbufqueues(QUEUE_DIRTY_GIANT, 1); 2094 mtx_unlock(&Giant); 2095 } 2096 break; 2097 } 2098 uio_yield(); 2099 } 2100 2101 /* 2102 * Only clear bd_request if we have reached our low water 2103 * mark. The buf_daemon normally waits 1 second and 2104 * then incrementally flushes any dirty buffers that have 2105 * built up, within reason. 2106 * 2107 * If we were unable to hit our low water mark and couldn't 2108 * find any flushable buffers, we sleep half a second. 2109 * Otherwise we loop immediately. 2110 */ 2111 mtx_lock(&bdlock); 2112 if (numdirtybuffers <= lodirtybuffers) { 2113 /* 2114 * We reached our low water mark, reset the 2115 * request and sleep until we are needed again. 2116 * The sleep is just so the suspend code works. 2117 */ 2118 bd_request = 0; 2119 msleep(&bd_request, &bdlock, PVM, "psleep", hz); 2120 } else { 2121 /* 2122 * We couldn't find any flushable dirty buffers but 2123 * still have too many dirty buffers, we 2124 * have to sleep and try again. (rare) 2125 */ 2126 msleep(&bd_request, &bdlock, PVM, "qsleep", hz / 10); 2127 } 2128 } 2129 } 2130 2131 /* 2132 * flushbufqueues: 2133 * 2134 * Try to flush a buffer in the dirty queue. We must be careful to 2135 * free up B_INVAL buffers instead of write them, which NFS is 2136 * particularly sensitive to. 2137 */ 2138 static int flushwithdeps = 0; 2139 SYSCTL_INT(_vfs, OID_AUTO, flushwithdeps, CTLFLAG_RW, &flushwithdeps, 2140 0, "Number of buffers flushed with dependecies that require rollbacks"); 2141 2142 static int 2143 flushbufqueues(int queue, int flushdeps) 2144 { 2145 struct thread *td = curthread; 2146 struct buf sentinel; 2147 struct vnode *vp; 2148 struct mount *mp; 2149 struct buf *bp; 2150 int hasdeps; 2151 int flushed; 2152 int target; 2153 2154 target = numdirtybuffers - lodirtybuffers; 2155 if (flushdeps && target > 2) 2156 target /= 2; 2157 flushed = 0; 2158 bp = NULL; 2159 mtx_lock(&bqlock); 2160 TAILQ_INSERT_TAIL(&bufqueues[queue], &sentinel, b_freelist); 2161 while (flushed != target) { 2162 bp = TAILQ_FIRST(&bufqueues[queue]); 2163 if (bp == &sentinel) 2164 break; 2165 TAILQ_REMOVE(&bufqueues[queue], bp, b_freelist); 2166 TAILQ_INSERT_TAIL(&bufqueues[queue], bp, b_freelist); 2167 2168 if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) 2169 continue; 2170 if (bp->b_pin_count > 0) { 2171 BUF_UNLOCK(bp); 2172 continue; 2173 } 2174 BO_LOCK(bp->b_bufobj); 2175 if ((bp->b_vflags & BV_BKGRDINPROG) != 0 || 2176 (bp->b_flags & B_DELWRI) == 0) { 2177 BO_UNLOCK(bp->b_bufobj); 2178 BUF_UNLOCK(bp); 2179 continue; 2180 } 2181 BO_UNLOCK(bp->b_bufobj); 2182 if (bp->b_flags & B_INVAL) { 2183 bremfreel(bp); 2184 mtx_unlock(&bqlock); 2185 brelse(bp); 2186 flushed++; 2187 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2188 mtx_lock(&bqlock); 2189 continue; 2190 } 2191 2192 if (!LIST_EMPTY(&bp->b_dep) && buf_countdeps(bp, 0)) { 2193 if (flushdeps == 0) { 2194 BUF_UNLOCK(bp); 2195 continue; 2196 } 2197 hasdeps = 1; 2198 } else 2199 hasdeps = 0; 2200 /* 2201 * We must hold the lock on a vnode before writing 2202 * one of its buffers. Otherwise we may confuse, or 2203 * in the case of a snapshot vnode, deadlock the 2204 * system. 2205 * 2206 * The lock order here is the reverse of the normal 2207 * of vnode followed by buf lock. This is ok because 2208 * the NOWAIT will prevent deadlock. 2209 */ 2210 vp = bp->b_vp; 2211 if (vn_start_write(vp, &mp, V_NOWAIT) != 0) { 2212 BUF_UNLOCK(bp); 2213 continue; 2214 } 2215 if (vn_lock(vp, LK_EXCLUSIVE | LK_NOWAIT, td) == 0) { 2216 mtx_unlock(&bqlock); 2217 CTR3(KTR_BUF, "flushbufqueue(%p) vp %p flags %X", 2218 bp, bp->b_vp, bp->b_flags); 2219 vfs_bio_awrite(bp); 2220 vn_finished_write(mp); 2221 VOP_UNLOCK(vp, 0, td); 2222 flushwithdeps += hasdeps; 2223 flushed++; 2224 waitrunningbufspace(); 2225 numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); 2226 mtx_lock(&bqlock); 2227 continue; 2228 } 2229 vn_finished_write(mp); 2230 BUF_UNLOCK(bp); 2231 } 2232 TAILQ_REMOVE(&bufqueues[queue], &sentinel, b_freelist); 2233 mtx_unlock(&bqlock); 2234 return (flushed); 2235 } 2236 2237 /* 2238 * Check to see if a block is currently memory resident. 2239 */ 2240 struct buf * 2241 incore(struct bufobj *bo, daddr_t blkno) 2242 { 2243 struct buf *bp; 2244 2245 BO_LOCK(bo); 2246 bp = gbincore(bo, blkno); 2247 BO_UNLOCK(bo); 2248 return (bp); 2249 } 2250 2251 /* 2252 * Returns true if no I/O is needed to access the 2253 * associated VM object. This is like incore except 2254 * it also hunts around in the VM system for the data. 2255 */ 2256 2257 static int 2258 inmem(struct vnode * vp, daddr_t blkno) 2259 { 2260 vm_object_t obj; 2261 vm_offset_t toff, tinc, size; 2262 vm_page_t m; 2263 vm_ooffset_t off; 2264 2265 ASSERT_VOP_LOCKED(vp, "inmem"); 2266 2267 if (incore(&vp->v_bufobj, blkno)) 2268 return 1; 2269 if (vp->v_mount == NULL) 2270 return 0; 2271 obj = vp->v_object; 2272 if (obj == NULL) 2273 return (0); 2274 2275 size = PAGE_SIZE; 2276 if (size > vp->v_mount->mnt_stat.f_iosize) 2277 size = vp->v_mount->mnt_stat.f_iosize; 2278 off = (vm_ooffset_t)blkno * (vm_ooffset_t)vp->v_mount->mnt_stat.f_iosize; 2279 2280 VM_OBJECT_LOCK(obj); 2281 for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { 2282 m = vm_page_lookup(obj, OFF_TO_IDX(off + toff)); 2283 if (!m) 2284 goto notinmem; 2285 tinc = size; 2286 if (tinc > PAGE_SIZE - ((toff + off) & PAGE_MASK)) 2287 tinc = PAGE_SIZE - ((toff + off) & PAGE_MASK); 2288 if (vm_page_is_valid(m, 2289 (vm_offset_t) ((toff + off) & PAGE_MASK), tinc) == 0) 2290 goto notinmem; 2291 } 2292 VM_OBJECT_UNLOCK(obj); 2293 return 1; 2294 2295 notinmem: 2296 VM_OBJECT_UNLOCK(obj); 2297 return (0); 2298 } 2299 2300 /* 2301 * vfs_setdirty: 2302 * 2303 * Sets the dirty range for a buffer based on the status of the dirty 2304 * bits in the pages comprising the buffer. 2305 * 2306 * The range is limited to the size of the buffer. 2307 * 2308 * This routine is primarily used by NFS, but is generalized for the 2309 * B_VMIO case. 2310 */ 2311 static void 2312 vfs_setdirty(struct buf *bp) 2313 { 2314 2315 /* 2316 * Degenerate case - empty buffer 2317 */ 2318 2319 if (bp->b_bufsize == 0) 2320 return; 2321 2322 /* 2323 * We qualify the scan for modified pages on whether the 2324 * object has been flushed yet. 2325 */ 2326 2327 if ((bp->b_flags & B_VMIO) == 0) 2328 return; 2329 2330 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2331 vfs_setdirty_locked_object(bp); 2332 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2333 } 2334 2335 static void 2336 vfs_setdirty_locked_object(struct buf *bp) 2337 { 2338 vm_object_t object; 2339 int i; 2340 2341 object = bp->b_bufobj->bo_object; 2342 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 2343 if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { 2344 vm_offset_t boffset; 2345 vm_offset_t eoffset; 2346 2347 vm_page_lock_queues(); 2348 /* 2349 * test the pages to see if they have been modified directly 2350 * by users through the VM system. 2351 */ 2352 for (i = 0; i < bp->b_npages; i++) 2353 vm_page_test_dirty(bp->b_pages[i]); 2354 2355 /* 2356 * Calculate the encompassing dirty range, boffset and eoffset, 2357 * (eoffset - boffset) bytes. 2358 */ 2359 2360 for (i = 0; i < bp->b_npages; i++) { 2361 if (bp->b_pages[i]->dirty) 2362 break; 2363 } 2364 boffset = (i << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2365 2366 for (i = bp->b_npages - 1; i >= 0; --i) { 2367 if (bp->b_pages[i]->dirty) { 2368 break; 2369 } 2370 } 2371 eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_offset & PAGE_MASK); 2372 2373 vm_page_unlock_queues(); 2374 /* 2375 * Fit it to the buffer. 2376 */ 2377 2378 if (eoffset > bp->b_bcount) 2379 eoffset = bp->b_bcount; 2380 2381 /* 2382 * If we have a good dirty range, merge with the existing 2383 * dirty range. 2384 */ 2385 2386 if (boffset < eoffset) { 2387 if (bp->b_dirtyoff > boffset) 2388 bp->b_dirtyoff = boffset; 2389 if (bp->b_dirtyend < eoffset) 2390 bp->b_dirtyend = eoffset; 2391 } 2392 } 2393 } 2394 2395 /* 2396 * getblk: 2397 * 2398 * Get a block given a specified block and offset into a file/device. 2399 * The buffers B_DONE bit will be cleared on return, making it almost 2400 * ready for an I/O initiation. B_INVAL may or may not be set on 2401 * return. The caller should clear B_INVAL prior to initiating a 2402 * READ. 2403 * 2404 * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for 2405 * an existing buffer. 2406 * 2407 * For a VMIO buffer, B_CACHE is modified according to the backing VM. 2408 * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set 2409 * and then cleared based on the backing VM. If the previous buffer is 2410 * non-0-sized but invalid, B_CACHE will be cleared. 2411 * 2412 * If getblk() must create a new buffer, the new buffer is returned with 2413 * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which 2414 * case it is returned with B_INVAL clear and B_CACHE set based on the 2415 * backing VM. 2416 * 2417 * getblk() also forces a bwrite() for any B_DELWRI buffer whos 2418 * B_CACHE bit is clear. 2419 * 2420 * What this means, basically, is that the caller should use B_CACHE to 2421 * determine whether the buffer is fully valid or not and should clear 2422 * B_INVAL prior to issuing a read. If the caller intends to validate 2423 * the buffer by loading its data area with something, the caller needs 2424 * to clear B_INVAL. If the caller does this without issuing an I/O, 2425 * the caller should set B_CACHE ( as an optimization ), else the caller 2426 * should issue the I/O and biodone() will set B_CACHE if the I/O was 2427 * a write attempt or if it was a successfull read. If the caller 2428 * intends to issue a READ, the caller must clear B_INVAL and BIO_ERROR 2429 * prior to issuing the READ. biodone() will *not* clear B_INVAL. 2430 */ 2431 struct buf * 2432 getblk(struct vnode * vp, daddr_t blkno, int size, int slpflag, int slptimeo, 2433 int flags) 2434 { 2435 struct buf *bp; 2436 struct bufobj *bo; 2437 int error; 2438 2439 CTR3(KTR_BUF, "getblk(%p, %ld, %d)", vp, (long)blkno, size); 2440 ASSERT_VOP_LOCKED(vp, "getblk"); 2441 if (size > MAXBSIZE) 2442 panic("getblk: size(%d) > MAXBSIZE(%d)\n", size, MAXBSIZE); 2443 2444 bo = &vp->v_bufobj; 2445 loop: 2446 /* 2447 * Block if we are low on buffers. Certain processes are allowed 2448 * to completely exhaust the buffer cache. 2449 * 2450 * If this check ever becomes a bottleneck it may be better to 2451 * move it into the else, when gbincore() fails. At the moment 2452 * it isn't a problem. 2453 * 2454 * XXX remove if 0 sections (clean this up after its proven) 2455 */ 2456 if (numfreebuffers == 0) { 2457 if (TD_IS_IDLETHREAD(curthread)) 2458 return NULL; 2459 mtx_lock(&nblock); 2460 needsbuffer |= VFS_BIO_NEED_ANY; 2461 mtx_unlock(&nblock); 2462 } 2463 2464 BO_LOCK(bo); 2465 bp = gbincore(bo, blkno); 2466 if (bp != NULL) { 2467 int lockflags; 2468 /* 2469 * Buffer is in-core. If the buffer is not busy, it must 2470 * be on a queue. 2471 */ 2472 lockflags = LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK; 2473 2474 if (flags & GB_LOCK_NOWAIT) 2475 lockflags |= LK_NOWAIT; 2476 2477 error = BUF_TIMELOCK(bp, lockflags, 2478 VI_MTX(vp), "getblk", slpflag, slptimeo); 2479 2480 /* 2481 * If we slept and got the lock we have to restart in case 2482 * the buffer changed identities. 2483 */ 2484 if (error == ENOLCK) 2485 goto loop; 2486 /* We timed out or were interrupted. */ 2487 else if (error) 2488 return (NULL); 2489 2490 /* 2491 * The buffer is locked. B_CACHE is cleared if the buffer is 2492 * invalid. Otherwise, for a non-VMIO buffer, B_CACHE is set 2493 * and for a VMIO buffer B_CACHE is adjusted according to the 2494 * backing VM cache. 2495 */ 2496 if (bp->b_flags & B_INVAL) 2497 bp->b_flags &= ~B_CACHE; 2498 else if ((bp->b_flags & (B_VMIO | B_INVAL)) == 0) 2499 bp->b_flags |= B_CACHE; 2500 bremfree(bp); 2501 2502 /* 2503 * check for size inconsistancies for non-VMIO case. 2504 */ 2505 2506 if (bp->b_bcount != size) { 2507 if ((bp->b_flags & B_VMIO) == 0 || 2508 (size > bp->b_kvasize)) { 2509 if (bp->b_flags & B_DELWRI) { 2510 /* 2511 * If buffer is pinned and caller does 2512 * not want sleep waiting for it to be 2513 * unpinned, bail out 2514 * */ 2515 if (bp->b_pin_count > 0) { 2516 if (flags & GB_LOCK_NOWAIT) { 2517 bqrelse(bp); 2518 return (NULL); 2519 } else { 2520 bunpin_wait(bp); 2521 } 2522 } 2523 bp->b_flags |= B_NOCACHE; 2524 bwrite(bp); 2525 } else { 2526 if (LIST_EMPTY(&bp->b_dep)) { 2527 bp->b_flags |= B_RELBUF; 2528 brelse(bp); 2529 } else { 2530 bp->b_flags |= B_NOCACHE; 2531 bwrite(bp); 2532 } 2533 } 2534 goto loop; 2535 } 2536 } 2537 2538 /* 2539 * If the size is inconsistant in the VMIO case, we can resize 2540 * the buffer. This might lead to B_CACHE getting set or 2541 * cleared. If the size has not changed, B_CACHE remains 2542 * unchanged from its previous state. 2543 */ 2544 2545 if (bp->b_bcount != size) 2546 allocbuf(bp, size); 2547 2548 KASSERT(bp->b_offset != NOOFFSET, 2549 ("getblk: no buffer offset")); 2550 2551 /* 2552 * A buffer with B_DELWRI set and B_CACHE clear must 2553 * be committed before we can return the buffer in 2554 * order to prevent the caller from issuing a read 2555 * ( due to B_CACHE not being set ) and overwriting 2556 * it. 2557 * 2558 * Most callers, including NFS and FFS, need this to 2559 * operate properly either because they assume they 2560 * can issue a read if B_CACHE is not set, or because 2561 * ( for example ) an uncached B_DELWRI might loop due 2562 * to softupdates re-dirtying the buffer. In the latter 2563 * case, B_CACHE is set after the first write completes, 2564 * preventing further loops. 2565 * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE 2566 * above while extending the buffer, we cannot allow the 2567 * buffer to remain with B_CACHE set after the write 2568 * completes or it will represent a corrupt state. To 2569 * deal with this we set B_NOCACHE to scrap the buffer 2570 * after the write. 2571 * 2572 * We might be able to do something fancy, like setting 2573 * B_CACHE in bwrite() except if B_DELWRI is already set, 2574 * so the below call doesn't set B_CACHE, but that gets real 2575 * confusing. This is much easier. 2576 */ 2577 2578 if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { 2579 bp->b_flags |= B_NOCACHE; 2580 bwrite(bp); 2581 goto loop; 2582 } 2583 bp->b_flags &= ~B_DONE; 2584 } else { 2585 int bsize, maxsize, vmio; 2586 off_t offset; 2587 2588 /* 2589 * Buffer is not in-core, create new buffer. The buffer 2590 * returned by getnewbuf() is locked. Note that the returned 2591 * buffer is also considered valid (not marked B_INVAL). 2592 */ 2593 BO_UNLOCK(bo); 2594 /* 2595 * If the user does not want us to create the buffer, bail out 2596 * here. 2597 */ 2598 if (flags & GB_NOCREAT) 2599 return NULL; 2600 bsize = bo->bo_bsize; 2601 offset = blkno * bsize; 2602 vmio = vp->v_object != NULL; 2603 maxsize = vmio ? size + (offset & PAGE_MASK) : size; 2604 maxsize = imax(maxsize, bsize); 2605 2606 bp = getnewbuf(slpflag, slptimeo, size, maxsize); 2607 if (bp == NULL) { 2608 if (slpflag || slptimeo) 2609 return NULL; 2610 goto loop; 2611 } 2612 2613 /* 2614 * This code is used to make sure that a buffer is not 2615 * created while the getnewbuf routine is blocked. 2616 * This can be a problem whether the vnode is locked or not. 2617 * If the buffer is created out from under us, we have to 2618 * throw away the one we just created. 2619 * 2620 * Note: this must occur before we associate the buffer 2621 * with the vp especially considering limitations in 2622 * the splay tree implementation when dealing with duplicate 2623 * lblkno's. 2624 */ 2625 BO_LOCK(bo); 2626 if (gbincore(bo, blkno)) { 2627 BO_UNLOCK(bo); 2628 bp->b_flags |= B_INVAL; 2629 brelse(bp); 2630 goto loop; 2631 } 2632 2633 /* 2634 * Insert the buffer into the hash, so that it can 2635 * be found by incore. 2636 */ 2637 bp->b_blkno = bp->b_lblkno = blkno; 2638 bp->b_offset = offset; 2639 bgetvp(vp, bp); 2640 BO_UNLOCK(bo); 2641 2642 /* 2643 * set B_VMIO bit. allocbuf() the buffer bigger. Since the 2644 * buffer size starts out as 0, B_CACHE will be set by 2645 * allocbuf() for the VMIO case prior to it testing the 2646 * backing store for validity. 2647 */ 2648 2649 if (vmio) { 2650 bp->b_flags |= B_VMIO; 2651 #if defined(VFS_BIO_DEBUG) 2652 if (vn_canvmio(vp) != TRUE) 2653 printf("getblk: VMIO on vnode type %d\n", 2654 vp->v_type); 2655 #endif 2656 KASSERT(vp->v_object == bp->b_bufobj->bo_object, 2657 ("ARGH! different b_bufobj->bo_object %p %p %p\n", 2658 bp, vp->v_object, bp->b_bufobj->bo_object)); 2659 } else { 2660 bp->b_flags &= ~B_VMIO; 2661 KASSERT(bp->b_bufobj->bo_object == NULL, 2662 ("ARGH! has b_bufobj->bo_object %p %p\n", 2663 bp, bp->b_bufobj->bo_object)); 2664 } 2665 2666 allocbuf(bp, size); 2667 bp->b_flags &= ~B_DONE; 2668 } 2669 CTR4(KTR_BUF, "getblk(%p, %ld, %d) = %p", vp, (long)blkno, size, bp); 2670 KASSERT(BUF_REFCNT(bp) == 1, ("getblk: bp %p not locked",bp)); 2671 KASSERT(bp->b_bufobj == bo, 2672 ("bp %p wrong b_bufobj %p should be %p", bp, bp->b_bufobj, bo)); 2673 return (bp); 2674 } 2675 2676 /* 2677 * Get an empty, disassociated buffer of given size. The buffer is initially 2678 * set to B_INVAL. 2679 */ 2680 struct buf * 2681 geteblk(int size) 2682 { 2683 struct buf *bp; 2684 int maxsize; 2685 2686 maxsize = (size + BKVAMASK) & ~BKVAMASK; 2687 while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) 2688 continue; 2689 allocbuf(bp, size); 2690 bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ 2691 KASSERT(BUF_REFCNT(bp) == 1, ("geteblk: bp %p not locked",bp)); 2692 return (bp); 2693 } 2694 2695 2696 /* 2697 * This code constitutes the buffer memory from either anonymous system 2698 * memory (in the case of non-VMIO operations) or from an associated 2699 * VM object (in the case of VMIO operations). This code is able to 2700 * resize a buffer up or down. 2701 * 2702 * Note that this code is tricky, and has many complications to resolve 2703 * deadlock or inconsistant data situations. Tread lightly!!! 2704 * There are B_CACHE and B_DELWRI interactions that must be dealt with by 2705 * the caller. Calling this code willy nilly can result in the loss of data. 2706 * 2707 * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with 2708 * B_CACHE for the non-VMIO case. 2709 */ 2710 2711 int 2712 allocbuf(struct buf *bp, int size) 2713 { 2714 int newbsize, mbsize; 2715 int i; 2716 2717 if (BUF_REFCNT(bp) == 0) 2718 panic("allocbuf: buffer not busy"); 2719 2720 if (bp->b_kvasize < size) 2721 panic("allocbuf: buffer too small"); 2722 2723 if ((bp->b_flags & B_VMIO) == 0) { 2724 caddr_t origbuf; 2725 int origbufsize; 2726 /* 2727 * Just get anonymous memory from the kernel. Don't 2728 * mess with B_CACHE. 2729 */ 2730 mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2731 if (bp->b_flags & B_MALLOC) 2732 newbsize = mbsize; 2733 else 2734 newbsize = round_page(size); 2735 2736 if (newbsize < bp->b_bufsize) { 2737 /* 2738 * malloced buffers are not shrunk 2739 */ 2740 if (bp->b_flags & B_MALLOC) { 2741 if (newbsize) { 2742 bp->b_bcount = size; 2743 } else { 2744 free(bp->b_data, M_BIOBUF); 2745 if (bp->b_bufsize) { 2746 atomic_subtract_int( 2747 &bufmallocspace, 2748 bp->b_bufsize); 2749 bufspacewakeup(); 2750 bp->b_bufsize = 0; 2751 } 2752 bp->b_saveaddr = bp->b_kvabase; 2753 bp->b_data = bp->b_saveaddr; 2754 bp->b_bcount = 0; 2755 bp->b_flags &= ~B_MALLOC; 2756 } 2757 return 1; 2758 } 2759 vm_hold_free_pages( 2760 bp, 2761 (vm_offset_t) bp->b_data + newbsize, 2762 (vm_offset_t) bp->b_data + bp->b_bufsize); 2763 } else if (newbsize > bp->b_bufsize) { 2764 /* 2765 * We only use malloced memory on the first allocation. 2766 * and revert to page-allocated memory when the buffer 2767 * grows. 2768 */ 2769 /* 2770 * There is a potential smp race here that could lead 2771 * to bufmallocspace slightly passing the max. It 2772 * is probably extremely rare and not worth worrying 2773 * over. 2774 */ 2775 if ( (bufmallocspace < maxbufmallocspace) && 2776 (bp->b_bufsize == 0) && 2777 (mbsize <= PAGE_SIZE/2)) { 2778 2779 bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); 2780 bp->b_bufsize = mbsize; 2781 bp->b_bcount = size; 2782 bp->b_flags |= B_MALLOC; 2783 atomic_add_int(&bufmallocspace, mbsize); 2784 return 1; 2785 } 2786 origbuf = NULL; 2787 origbufsize = 0; 2788 /* 2789 * If the buffer is growing on its other-than-first allocation, 2790 * then we revert to the page-allocation scheme. 2791 */ 2792 if (bp->b_flags & B_MALLOC) { 2793 origbuf = bp->b_data; 2794 origbufsize = bp->b_bufsize; 2795 bp->b_data = bp->b_kvabase; 2796 if (bp->b_bufsize) { 2797 atomic_subtract_int(&bufmallocspace, 2798 bp->b_bufsize); 2799 bufspacewakeup(); 2800 bp->b_bufsize = 0; 2801 } 2802 bp->b_flags &= ~B_MALLOC; 2803 newbsize = round_page(newbsize); 2804 } 2805 vm_hold_load_pages( 2806 bp, 2807 (vm_offset_t) bp->b_data + bp->b_bufsize, 2808 (vm_offset_t) bp->b_data + newbsize); 2809 if (origbuf) { 2810 bcopy(origbuf, bp->b_data, origbufsize); 2811 free(origbuf, M_BIOBUF); 2812 } 2813 } 2814 } else { 2815 int desiredpages; 2816 2817 newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); 2818 desiredpages = (size == 0) ? 0 : 2819 num_pages((bp->b_offset & PAGE_MASK) + newbsize); 2820 2821 if (bp->b_flags & B_MALLOC) 2822 panic("allocbuf: VMIO buffer can't be malloced"); 2823 /* 2824 * Set B_CACHE initially if buffer is 0 length or will become 2825 * 0-length. 2826 */ 2827 if (size == 0 || bp->b_bufsize == 0) 2828 bp->b_flags |= B_CACHE; 2829 2830 if (newbsize < bp->b_bufsize) { 2831 /* 2832 * DEV_BSIZE aligned new buffer size is less then the 2833 * DEV_BSIZE aligned existing buffer size. Figure out 2834 * if we have to remove any pages. 2835 */ 2836 if (desiredpages < bp->b_npages) { 2837 vm_page_t m; 2838 2839 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 2840 vm_page_lock_queues(); 2841 for (i = desiredpages; i < bp->b_npages; i++) { 2842 /* 2843 * the page is not freed here -- it 2844 * is the responsibility of 2845 * vnode_pager_setsize 2846 */ 2847 m = bp->b_pages[i]; 2848 KASSERT(m != bogus_page, 2849 ("allocbuf: bogus page found")); 2850 while (vm_page_sleep_if_busy(m, TRUE, "biodep")) 2851 vm_page_lock_queues(); 2852 2853 bp->b_pages[i] = NULL; 2854 vm_page_unwire(m, 0); 2855 } 2856 vm_page_unlock_queues(); 2857 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 2858 pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + 2859 (desiredpages << PAGE_SHIFT), (bp->b_npages - desiredpages)); 2860 bp->b_npages = desiredpages; 2861 } 2862 } else if (size > bp->b_bcount) { 2863 /* 2864 * We are growing the buffer, possibly in a 2865 * byte-granular fashion. 2866 */ 2867 struct vnode *vp; 2868 vm_object_t obj; 2869 vm_offset_t toff; 2870 vm_offset_t tinc; 2871 2872 /* 2873 * Step 1, bring in the VM pages from the object, 2874 * allocating them if necessary. We must clear 2875 * B_CACHE if these pages are not valid for the 2876 * range covered by the buffer. 2877 */ 2878 2879 vp = bp->b_vp; 2880 obj = bp->b_bufobj->bo_object; 2881 2882 VM_OBJECT_LOCK(obj); 2883 while (bp->b_npages < desiredpages) { 2884 vm_page_t m; 2885 vm_pindex_t pi; 2886 2887 pi = OFF_TO_IDX(bp->b_offset) + bp->b_npages; 2888 if ((m = vm_page_lookup(obj, pi)) == NULL) { 2889 /* 2890 * note: must allocate system pages 2891 * since blocking here could intefere 2892 * with paging I/O, no matter which 2893 * process we are. 2894 */ 2895 m = vm_page_alloc(obj, pi, 2896 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | 2897 VM_ALLOC_WIRED); 2898 if (m == NULL) { 2899 atomic_add_int(&vm_pageout_deficit, 2900 desiredpages - bp->b_npages); 2901 VM_OBJECT_UNLOCK(obj); 2902 VM_WAIT; 2903 VM_OBJECT_LOCK(obj); 2904 } else { 2905 if (m->valid == 0) 2906 bp->b_flags &= ~B_CACHE; 2907 bp->b_pages[bp->b_npages] = m; 2908 ++bp->b_npages; 2909 } 2910 continue; 2911 } 2912 2913 /* 2914 * We found a page. If we have to sleep on it, 2915 * retry because it might have gotten freed out 2916 * from under us. 2917 * 2918 * We can only test VPO_BUSY here. Blocking on 2919 * m->busy might lead to a deadlock: 2920 * 2921 * vm_fault->getpages->cluster_read->allocbuf 2922 * 2923 */ 2924 if (vm_page_sleep_if_busy(m, FALSE, "pgtblk")) 2925 continue; 2926 2927 /* 2928 * We have a good page. 2929 */ 2930 vm_page_lock_queues(); 2931 vm_page_wire(m); 2932 vm_page_unlock_queues(); 2933 bp->b_pages[bp->b_npages] = m; 2934 ++bp->b_npages; 2935 } 2936 2937 /* 2938 * Step 2. We've loaded the pages into the buffer, 2939 * we have to figure out if we can still have B_CACHE 2940 * set. Note that B_CACHE is set according to the 2941 * byte-granular range ( bcount and size ), new the 2942 * aligned range ( newbsize ). 2943 * 2944 * The VM test is against m->valid, which is DEV_BSIZE 2945 * aligned. Needless to say, the validity of the data 2946 * needs to also be DEV_BSIZE aligned. Note that this 2947 * fails with NFS if the server or some other client 2948 * extends the file's EOF. If our buffer is resized, 2949 * B_CACHE may remain set! XXX 2950 */ 2951 2952 toff = bp->b_bcount; 2953 tinc = PAGE_SIZE - ((bp->b_offset + toff) & PAGE_MASK); 2954 2955 while ((bp->b_flags & B_CACHE) && toff < size) { 2956 vm_pindex_t pi; 2957 2958 if (tinc > (size - toff)) 2959 tinc = size - toff; 2960 2961 pi = ((bp->b_offset & PAGE_MASK) + toff) >> 2962 PAGE_SHIFT; 2963 2964 vfs_buf_test_cache( 2965 bp, 2966 bp->b_offset, 2967 toff, 2968 tinc, 2969 bp->b_pages[pi] 2970 ); 2971 toff += tinc; 2972 tinc = PAGE_SIZE; 2973 } 2974 VM_OBJECT_UNLOCK(obj); 2975 2976 /* 2977 * Step 3, fixup the KVM pmap. Remember that 2978 * bp->b_data is relative to bp->b_offset, but 2979 * bp->b_offset may be offset into the first page. 2980 */ 2981 2982 bp->b_data = (caddr_t) 2983 trunc_page((vm_offset_t)bp->b_data); 2984 pmap_qenter( 2985 (vm_offset_t)bp->b_data, 2986 bp->b_pages, 2987 bp->b_npages 2988 ); 2989 2990 bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | 2991 (vm_offset_t)(bp->b_offset & PAGE_MASK)); 2992 } 2993 } 2994 if (newbsize < bp->b_bufsize) 2995 bufspacewakeup(); 2996 bp->b_bufsize = newbsize; /* actual buffer allocation */ 2997 bp->b_bcount = size; /* requested buffer size */ 2998 return 1; 2999 } 3000 3001 void 3002 biodone(struct bio *bp) 3003 { 3004 void (*done)(struct bio *); 3005 3006 mtx_lock(&bdonelock); 3007 bp->bio_flags |= BIO_DONE; 3008 done = bp->bio_done; 3009 if (done == NULL) 3010 wakeup(bp); 3011 mtx_unlock(&bdonelock); 3012 if (done != NULL) 3013 done(bp); 3014 } 3015 3016 /* 3017 * Wait for a BIO to finish. 3018 * 3019 * XXX: resort to a timeout for now. The optimal locking (if any) for this 3020 * case is not yet clear. 3021 */ 3022 int 3023 biowait(struct bio *bp, const char *wchan) 3024 { 3025 3026 mtx_lock(&bdonelock); 3027 while ((bp->bio_flags & BIO_DONE) == 0) 3028 msleep(bp, &bdonelock, PRIBIO, wchan, hz / 10); 3029 mtx_unlock(&bdonelock); 3030 if (bp->bio_error != 0) 3031 return (bp->bio_error); 3032 if (!(bp->bio_flags & BIO_ERROR)) 3033 return (0); 3034 return (EIO); 3035 } 3036 3037 void 3038 biofinish(struct bio *bp, struct devstat *stat, int error) 3039 { 3040 3041 if (error) { 3042 bp->bio_error = error; 3043 bp->bio_flags |= BIO_ERROR; 3044 } 3045 if (stat != NULL) 3046 devstat_end_transaction_bio(stat, bp); 3047 biodone(bp); 3048 } 3049 3050 /* 3051 * bufwait: 3052 * 3053 * Wait for buffer I/O completion, returning error status. The buffer 3054 * is left locked and B_DONE on return. B_EINTR is converted into an EINTR 3055 * error and cleared. 3056 */ 3057 int 3058 bufwait(struct buf *bp) 3059 { 3060 if (bp->b_iocmd == BIO_READ) 3061 bwait(bp, PRIBIO, "biord"); 3062 else 3063 bwait(bp, PRIBIO, "biowr"); 3064 if (bp->b_flags & B_EINTR) { 3065 bp->b_flags &= ~B_EINTR; 3066 return (EINTR); 3067 } 3068 if (bp->b_ioflags & BIO_ERROR) { 3069 return (bp->b_error ? bp->b_error : EIO); 3070 } else { 3071 return (0); 3072 } 3073 } 3074 3075 /* 3076 * Call back function from struct bio back up to struct buf. 3077 */ 3078 static void 3079 bufdonebio(struct bio *bip) 3080 { 3081 struct buf *bp; 3082 3083 bp = bip->bio_caller2; 3084 bp->b_resid = bp->b_bcount - bip->bio_completed; 3085 bp->b_resid = bip->bio_resid; /* XXX: remove */ 3086 bp->b_ioflags = bip->bio_flags; 3087 bp->b_error = bip->bio_error; 3088 if (bp->b_error) 3089 bp->b_ioflags |= BIO_ERROR; 3090 bufdone(bp); 3091 g_destroy_bio(bip); 3092 } 3093 3094 void 3095 dev_strategy(struct cdev *dev, struct buf *bp) 3096 { 3097 struct cdevsw *csw; 3098 struct bio *bip; 3099 3100 if ((!bp->b_iocmd) || (bp->b_iocmd & (bp->b_iocmd - 1))) 3101 panic("b_iocmd botch"); 3102 for (;;) { 3103 bip = g_new_bio(); 3104 if (bip != NULL) 3105 break; 3106 /* Try again later */ 3107 tsleep(&bp, PRIBIO, "dev_strat", hz/10); 3108 } 3109 bip->bio_cmd = bp->b_iocmd; 3110 bip->bio_offset = bp->b_iooffset; 3111 bip->bio_length = bp->b_bcount; 3112 bip->bio_bcount = bp->b_bcount; /* XXX: remove */ 3113 bip->bio_data = bp->b_data; 3114 bip->bio_done = bufdonebio; 3115 bip->bio_caller2 = bp; 3116 bip->bio_dev = dev; 3117 KASSERT(dev->si_refcount > 0, 3118 ("dev_strategy on un-referenced struct cdev *(%s)", 3119 devtoname(dev))); 3120 csw = dev_refthread(dev); 3121 if (csw == NULL) { 3122 g_destroy_bio(bip); 3123 bp->b_error = ENXIO; 3124 bp->b_ioflags = BIO_ERROR; 3125 bufdone(bp); 3126 return; 3127 } 3128 (*csw->d_strategy)(bip); 3129 dev_relthread(dev); 3130 } 3131 3132 /* 3133 * bufdone: 3134 * 3135 * Finish I/O on a buffer, optionally calling a completion function. 3136 * This is usually called from an interrupt so process blocking is 3137 * not allowed. 3138 * 3139 * biodone is also responsible for setting B_CACHE in a B_VMIO bp. 3140 * In a non-VMIO bp, B_CACHE will be set on the next getblk() 3141 * assuming B_INVAL is clear. 3142 * 3143 * For the VMIO case, we set B_CACHE if the op was a read and no 3144 * read error occured, or if the op was a write. B_CACHE is never 3145 * set if the buffer is invalid or otherwise uncacheable. 3146 * 3147 * biodone does not mess with B_INVAL, allowing the I/O routine or the 3148 * initiator to leave B_INVAL set to brelse the buffer out of existance 3149 * in the biodone routine. 3150 */ 3151 void 3152 bufdone(struct buf *bp) 3153 { 3154 struct bufobj *dropobj; 3155 void (*biodone)(struct buf *); 3156 3157 CTR3(KTR_BUF, "bufdone(%p) vp %p flags %X", bp, bp->b_vp, bp->b_flags); 3158 dropobj = NULL; 3159 3160 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3161 BUF_REFCNT(bp))); 3162 KASSERT(!(bp->b_flags & B_DONE), ("biodone: bp %p already done", bp)); 3163 3164 runningbufwakeup(bp); 3165 if (bp->b_iocmd == BIO_WRITE) 3166 dropobj = bp->b_bufobj; 3167 /* call optional completion function if requested */ 3168 if (bp->b_iodone != NULL) { 3169 biodone = bp->b_iodone; 3170 bp->b_iodone = NULL; 3171 (*biodone) (bp); 3172 if (dropobj) 3173 bufobj_wdrop(dropobj); 3174 return; 3175 } 3176 3177 bufdone_finish(bp); 3178 3179 if (dropobj) 3180 bufobj_wdrop(dropobj); 3181 } 3182 3183 void 3184 bufdone_finish(struct buf *bp) 3185 { 3186 KASSERT(BUF_REFCNT(bp) > 0, ("biodone: bp %p not busy %d", bp, 3187 BUF_REFCNT(bp))); 3188 3189 if (!LIST_EMPTY(&bp->b_dep)) 3190 buf_complete(bp); 3191 3192 if (bp->b_flags & B_VMIO) { 3193 int i; 3194 vm_ooffset_t foff; 3195 vm_page_t m; 3196 vm_object_t obj; 3197 int iosize; 3198 struct vnode *vp = bp->b_vp; 3199 boolean_t are_queues_locked; 3200 3201 obj = bp->b_bufobj->bo_object; 3202 3203 #if defined(VFS_BIO_DEBUG) 3204 mp_fixme("usecount and vflag accessed without locks."); 3205 if (vp->v_usecount == 0) { 3206 panic("biodone: zero vnode ref count"); 3207 } 3208 3209 KASSERT(vp->v_object != NULL, 3210 ("biodone: vnode %p has no vm_object", vp)); 3211 #endif 3212 3213 foff = bp->b_offset; 3214 KASSERT(bp->b_offset != NOOFFSET, 3215 ("biodone: no buffer offset")); 3216 3217 VM_OBJECT_LOCK(obj); 3218 #if defined(VFS_BIO_DEBUG) 3219 if (obj->paging_in_progress < bp->b_npages) { 3220 printf("biodone: paging in progress(%d) < bp->b_npages(%d)\n", 3221 obj->paging_in_progress, bp->b_npages); 3222 } 3223 #endif 3224 3225 /* 3226 * Set B_CACHE if the op was a normal read and no error 3227 * occured. B_CACHE is set for writes in the b*write() 3228 * routines. 3229 */ 3230 iosize = bp->b_bcount - bp->b_resid; 3231 if (bp->b_iocmd == BIO_READ && 3232 !(bp->b_flags & (B_INVAL|B_NOCACHE)) && 3233 !(bp->b_ioflags & BIO_ERROR)) { 3234 bp->b_flags |= B_CACHE; 3235 } 3236 if (bp->b_iocmd == BIO_READ) { 3237 vm_page_lock_queues(); 3238 are_queues_locked = TRUE; 3239 } else 3240 are_queues_locked = FALSE; 3241 for (i = 0; i < bp->b_npages; i++) { 3242 int bogusflag = 0; 3243 int resid; 3244 3245 resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; 3246 if (resid > iosize) 3247 resid = iosize; 3248 3249 /* 3250 * cleanup bogus pages, restoring the originals 3251 */ 3252 m = bp->b_pages[i]; 3253 if (m == bogus_page) { 3254 bogusflag = 1; 3255 m = vm_page_lookup(obj, OFF_TO_IDX(foff)); 3256 if (m == NULL) 3257 panic("biodone: page disappeared!"); 3258 bp->b_pages[i] = m; 3259 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3260 bp->b_pages, bp->b_npages); 3261 } 3262 #if defined(VFS_BIO_DEBUG) 3263 if (OFF_TO_IDX(foff) != m->pindex) { 3264 printf( 3265 "biodone: foff(%jd)/m->pindex(%ju) mismatch\n", 3266 (intmax_t)foff, (uintmax_t)m->pindex); 3267 } 3268 #endif 3269 3270 /* 3271 * In the write case, the valid and clean bits are 3272 * already changed correctly ( see bdwrite() ), so we 3273 * only need to do this here in the read case. 3274 */ 3275 if ((bp->b_iocmd == BIO_READ) && !bogusflag && resid > 0) { 3276 vfs_page_set_valid(bp, foff, m); 3277 } 3278 3279 /* 3280 * when debugging new filesystems or buffer I/O methods, this 3281 * is the most common error that pops up. if you see this, you 3282 * have not set the page busy flag correctly!!! 3283 */ 3284 if (m->busy == 0) { 3285 printf("biodone: page busy < 0, " 3286 "pindex: %d, foff: 0x(%x,%x), " 3287 "resid: %d, index: %d\n", 3288 (int) m->pindex, (int)(foff >> 32), 3289 (int) foff & 0xffffffff, resid, i); 3290 if (!vn_isdisk(vp, NULL)) 3291 printf(" iosize: %jd, lblkno: %jd, flags: 0x%x, npages: %d\n", 3292 (intmax_t)bp->b_vp->v_mount->mnt_stat.f_iosize, 3293 (intmax_t) bp->b_lblkno, 3294 bp->b_flags, bp->b_npages); 3295 else 3296 printf(" VDEV, lblkno: %jd, flags: 0x%x, npages: %d\n", 3297 (intmax_t) bp->b_lblkno, 3298 bp->b_flags, bp->b_npages); 3299 printf(" valid: 0x%lx, dirty: 0x%lx, wired: %d\n", 3300 (u_long)m->valid, (u_long)m->dirty, 3301 m->wire_count); 3302 panic("biodone: page busy < 0\n"); 3303 } 3304 vm_page_io_finish(m); 3305 vm_object_pip_subtract(obj, 1); 3306 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3307 iosize -= resid; 3308 } 3309 if (are_queues_locked) 3310 vm_page_unlock_queues(); 3311 vm_object_pip_wakeupn(obj, 0); 3312 VM_OBJECT_UNLOCK(obj); 3313 } 3314 3315 /* 3316 * For asynchronous completions, release the buffer now. The brelse 3317 * will do a wakeup there if necessary - so no need to do a wakeup 3318 * here in the async case. The sync case always needs to do a wakeup. 3319 */ 3320 3321 if (bp->b_flags & B_ASYNC) { 3322 if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_RELBUF)) || (bp->b_ioflags & BIO_ERROR)) 3323 brelse(bp); 3324 else 3325 bqrelse(bp); 3326 } else 3327 bdone(bp); 3328 } 3329 3330 /* 3331 * This routine is called in lieu of iodone in the case of 3332 * incomplete I/O. This keeps the busy status for pages 3333 * consistant. 3334 */ 3335 void 3336 vfs_unbusy_pages(struct buf *bp) 3337 { 3338 int i; 3339 vm_object_t obj; 3340 vm_page_t m; 3341 3342 runningbufwakeup(bp); 3343 if (!(bp->b_flags & B_VMIO)) 3344 return; 3345 3346 obj = bp->b_bufobj->bo_object; 3347 VM_OBJECT_LOCK(obj); 3348 for (i = 0; i < bp->b_npages; i++) { 3349 m = bp->b_pages[i]; 3350 if (m == bogus_page) { 3351 m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_offset) + i); 3352 if (!m) 3353 panic("vfs_unbusy_pages: page missing\n"); 3354 bp->b_pages[i] = m; 3355 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3356 bp->b_pages, bp->b_npages); 3357 } 3358 vm_object_pip_subtract(obj, 1); 3359 vm_page_io_finish(m); 3360 } 3361 vm_object_pip_wakeupn(obj, 0); 3362 VM_OBJECT_UNLOCK(obj); 3363 } 3364 3365 /* 3366 * vfs_page_set_valid: 3367 * 3368 * Set the valid bits in a page based on the supplied offset. The 3369 * range is restricted to the buffer's size. 3370 * 3371 * This routine is typically called after a read completes. 3372 */ 3373 static void 3374 vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, vm_page_t m) 3375 { 3376 vm_ooffset_t soff, eoff; 3377 3378 mtx_assert(&vm_page_queue_mtx, MA_OWNED); 3379 /* 3380 * Start and end offsets in buffer. eoff - soff may not cross a 3381 * page boundry or cross the end of the buffer. The end of the 3382 * buffer, in this case, is our file EOF, not the allocation size 3383 * of the buffer. 3384 */ 3385 soff = off; 3386 eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3387 if (eoff > bp->b_offset + bp->b_bcount) 3388 eoff = bp->b_offset + bp->b_bcount; 3389 3390 /* 3391 * Set valid range. This is typically the entire buffer and thus the 3392 * entire page. 3393 */ 3394 if (eoff > soff) { 3395 vm_page_set_validclean( 3396 m, 3397 (vm_offset_t) (soff & PAGE_MASK), 3398 (vm_offset_t) (eoff - soff) 3399 ); 3400 } 3401 } 3402 3403 /* 3404 * This routine is called before a device strategy routine. 3405 * It is used to tell the VM system that paging I/O is in 3406 * progress, and treat the pages associated with the buffer 3407 * almost as being VPO_BUSY. Also the object paging_in_progress 3408 * flag is handled to make sure that the object doesn't become 3409 * inconsistant. 3410 * 3411 * Since I/O has not been initiated yet, certain buffer flags 3412 * such as BIO_ERROR or B_INVAL may be in an inconsistant state 3413 * and should be ignored. 3414 */ 3415 void 3416 vfs_busy_pages(struct buf *bp, int clear_modify) 3417 { 3418 int i, bogus; 3419 vm_object_t obj; 3420 vm_ooffset_t foff; 3421 vm_page_t m; 3422 3423 if (!(bp->b_flags & B_VMIO)) 3424 return; 3425 3426 obj = bp->b_bufobj->bo_object; 3427 foff = bp->b_offset; 3428 KASSERT(bp->b_offset != NOOFFSET, 3429 ("vfs_busy_pages: no buffer offset")); 3430 VM_OBJECT_LOCK(obj); 3431 if (bp->b_bufsize != 0) 3432 vfs_setdirty_locked_object(bp); 3433 retry: 3434 for (i = 0; i < bp->b_npages; i++) { 3435 m = bp->b_pages[i]; 3436 3437 if (vm_page_sleep_if_busy(m, FALSE, "vbpage")) 3438 goto retry; 3439 } 3440 bogus = 0; 3441 vm_page_lock_queues(); 3442 for (i = 0; i < bp->b_npages; i++) { 3443 m = bp->b_pages[i]; 3444 3445 if ((bp->b_flags & B_CLUSTER) == 0) { 3446 vm_object_pip_add(obj, 1); 3447 vm_page_io_start(m); 3448 } 3449 /* 3450 * When readying a buffer for a read ( i.e 3451 * clear_modify == 0 ), it is important to do 3452 * bogus_page replacement for valid pages in 3453 * partially instantiated buffers. Partially 3454 * instantiated buffers can, in turn, occur when 3455 * reconstituting a buffer from its VM backing store 3456 * base. We only have to do this if B_CACHE is 3457 * clear ( which causes the I/O to occur in the 3458 * first place ). The replacement prevents the read 3459 * I/O from overwriting potentially dirty VM-backed 3460 * pages. XXX bogus page replacement is, uh, bogus. 3461 * It may not work properly with small-block devices. 3462 * We need to find a better way. 3463 */ 3464 pmap_remove_all(m); 3465 if (clear_modify) 3466 vfs_page_set_valid(bp, foff, m); 3467 else if (m->valid == VM_PAGE_BITS_ALL && 3468 (bp->b_flags & B_CACHE) == 0) { 3469 bp->b_pages[i] = bogus_page; 3470 bogus++; 3471 } 3472 foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3473 } 3474 vm_page_unlock_queues(); 3475 VM_OBJECT_UNLOCK(obj); 3476 if (bogus) 3477 pmap_qenter(trunc_page((vm_offset_t)bp->b_data), 3478 bp->b_pages, bp->b_npages); 3479 } 3480 3481 /* 3482 * Tell the VM system that the pages associated with this buffer 3483 * are clean. This is used for delayed writes where the data is 3484 * going to go to disk eventually without additional VM intevention. 3485 * 3486 * Note that while we only really need to clean through to b_bcount, we 3487 * just go ahead and clean through to b_bufsize. 3488 */ 3489 static void 3490 vfs_clean_pages(struct buf *bp) 3491 { 3492 int i; 3493 vm_ooffset_t foff, noff, eoff; 3494 vm_page_t m; 3495 3496 if (!(bp->b_flags & B_VMIO)) 3497 return; 3498 3499 foff = bp->b_offset; 3500 KASSERT(bp->b_offset != NOOFFSET, 3501 ("vfs_clean_pages: no buffer offset")); 3502 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3503 vm_page_lock_queues(); 3504 for (i = 0; i < bp->b_npages; i++) { 3505 m = bp->b_pages[i]; 3506 noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; 3507 eoff = noff; 3508 3509 if (eoff > bp->b_offset + bp->b_bufsize) 3510 eoff = bp->b_offset + bp->b_bufsize; 3511 vfs_page_set_valid(bp, foff, m); 3512 /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ 3513 foff = noff; 3514 } 3515 vm_page_unlock_queues(); 3516 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3517 } 3518 3519 /* 3520 * vfs_bio_set_validclean: 3521 * 3522 * Set the range within the buffer to valid and clean. The range is 3523 * relative to the beginning of the buffer, b_offset. Note that b_offset 3524 * itself may be offset from the beginning of the first page. 3525 * 3526 */ 3527 3528 void 3529 vfs_bio_set_validclean(struct buf *bp, int base, int size) 3530 { 3531 int i, n; 3532 vm_page_t m; 3533 3534 if (!(bp->b_flags & B_VMIO)) 3535 return; 3536 /* 3537 * Fixup base to be relative to beginning of first page. 3538 * Set initial n to be the maximum number of bytes in the 3539 * first page that can be validated. 3540 */ 3541 3542 base += (bp->b_offset & PAGE_MASK); 3543 n = PAGE_SIZE - (base & PAGE_MASK); 3544 3545 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3546 vm_page_lock_queues(); 3547 for (i = base / PAGE_SIZE; size > 0 && i < bp->b_npages; ++i) { 3548 m = bp->b_pages[i]; 3549 if (n > size) 3550 n = size; 3551 vm_page_set_validclean(m, base & PAGE_MASK, n); 3552 base += n; 3553 size -= n; 3554 n = PAGE_SIZE; 3555 } 3556 vm_page_unlock_queues(); 3557 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3558 } 3559 3560 /* 3561 * vfs_bio_clrbuf: 3562 * 3563 * clear a buffer. This routine essentially fakes an I/O, so we need 3564 * to clear BIO_ERROR and B_INVAL. 3565 * 3566 * Note that while we only theoretically need to clear through b_bcount, 3567 * we go ahead and clear through b_bufsize. 3568 */ 3569 3570 void 3571 vfs_bio_clrbuf(struct buf *bp) 3572 { 3573 int i, j, mask = 0; 3574 caddr_t sa, ea; 3575 3576 if ((bp->b_flags & (B_VMIO | B_MALLOC)) != B_VMIO) { 3577 clrbuf(bp); 3578 return; 3579 } 3580 3581 bp->b_flags &= ~B_INVAL; 3582 bp->b_ioflags &= ~BIO_ERROR; 3583 VM_OBJECT_LOCK(bp->b_bufobj->bo_object); 3584 if ((bp->b_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && 3585 (bp->b_offset & PAGE_MASK) == 0) { 3586 if (bp->b_pages[0] == bogus_page) 3587 goto unlock; 3588 mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; 3589 VM_OBJECT_LOCK_ASSERT(bp->b_pages[0]->object, MA_OWNED); 3590 if ((bp->b_pages[0]->valid & mask) == mask) 3591 goto unlock; 3592 if (((bp->b_pages[0]->flags & PG_ZERO) == 0) && 3593 ((bp->b_pages[0]->valid & mask) == 0)) { 3594 bzero(bp->b_data, bp->b_bufsize); 3595 bp->b_pages[0]->valid |= mask; 3596 goto unlock; 3597 } 3598 } 3599 ea = sa = bp->b_data; 3600 for(i = 0; i < bp->b_npages; i++, sa = ea) { 3601 ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); 3602 ea = (caddr_t)(vm_offset_t)ulmin( 3603 (u_long)(vm_offset_t)ea, 3604 (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); 3605 if (bp->b_pages[i] == bogus_page) 3606 continue; 3607 j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; 3608 mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; 3609 VM_OBJECT_LOCK_ASSERT(bp->b_pages[i]->object, MA_OWNED); 3610 if ((bp->b_pages[i]->valid & mask) == mask) 3611 continue; 3612 if ((bp->b_pages[i]->valid & mask) == 0) { 3613 if ((bp->b_pages[i]->flags & PG_ZERO) == 0) 3614 bzero(sa, ea - sa); 3615 } else { 3616 for (; sa < ea; sa += DEV_BSIZE, j++) { 3617 if (((bp->b_pages[i]->flags & PG_ZERO) == 0) && 3618 (bp->b_pages[i]->valid & (1 << j)) == 0) 3619 bzero(sa, DEV_BSIZE); 3620 } 3621 } 3622 bp->b_pages[i]->valid |= mask; 3623 } 3624 unlock: 3625 VM_OBJECT_UNLOCK(bp->b_bufobj->bo_object); 3626 bp->b_resid = 0; 3627 } 3628 3629 /* 3630 * vm_hold_load_pages and vm_hold_free_pages get pages into 3631 * a buffers address space. The pages are anonymous and are 3632 * not associated with a file object. 3633 */ 3634 static void 3635 vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3636 { 3637 vm_offset_t pg; 3638 vm_page_t p; 3639 int index; 3640 3641 to = round_page(to); 3642 from = round_page(from); 3643 index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3644 3645 VM_OBJECT_LOCK(kernel_object); 3646 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3647 tryagain: 3648 /* 3649 * note: must allocate system pages since blocking here 3650 * could intefere with paging I/O, no matter which 3651 * process we are. 3652 */ 3653 p = vm_page_alloc(kernel_object, 3654 ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), 3655 VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED); 3656 if (!p) { 3657 atomic_add_int(&vm_pageout_deficit, 3658 (to - pg) >> PAGE_SHIFT); 3659 VM_OBJECT_UNLOCK(kernel_object); 3660 VM_WAIT; 3661 VM_OBJECT_LOCK(kernel_object); 3662 goto tryagain; 3663 } 3664 p->valid = VM_PAGE_BITS_ALL; 3665 pmap_qenter(pg, &p, 1); 3666 bp->b_pages[index] = p; 3667 } 3668 VM_OBJECT_UNLOCK(kernel_object); 3669 bp->b_npages = index; 3670 } 3671 3672 /* Return pages associated with this buf to the vm system */ 3673 static void 3674 vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) 3675 { 3676 vm_offset_t pg; 3677 vm_page_t p; 3678 int index, newnpages; 3679 3680 from = round_page(from); 3681 to = round_page(to); 3682 newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; 3683 3684 VM_OBJECT_LOCK(kernel_object); 3685 for (pg = from; pg < to; pg += PAGE_SIZE, index++) { 3686 p = bp->b_pages[index]; 3687 if (p && (index < bp->b_npages)) { 3688 if (p->busy) { 3689 printf( 3690 "vm_hold_free_pages: blkno: %jd, lblkno: %jd\n", 3691 (intmax_t)bp->b_blkno, 3692 (intmax_t)bp->b_lblkno); 3693 } 3694 bp->b_pages[index] = NULL; 3695 pmap_qremove(pg, 1); 3696 vm_page_lock_queues(); 3697 vm_page_unwire(p, 0); 3698 vm_page_free(p); 3699 vm_page_unlock_queues(); 3700 } 3701 } 3702 VM_OBJECT_UNLOCK(kernel_object); 3703 bp->b_npages = newnpages; 3704 } 3705 3706 /* 3707 * Map an IO request into kernel virtual address space. 3708 * 3709 * All requests are (re)mapped into kernel VA space. 3710 * Notice that we use b_bufsize for the size of the buffer 3711 * to be mapped. b_bcount might be modified by the driver. 3712 * 3713 * Note that even if the caller determines that the address space should 3714 * be valid, a race or a smaller-file mapped into a larger space may 3715 * actually cause vmapbuf() to fail, so all callers of vmapbuf() MUST 3716 * check the return value. 3717 */ 3718 int 3719 vmapbuf(struct buf *bp) 3720 { 3721 caddr_t addr, kva; 3722 vm_prot_t prot; 3723 int pidx, i; 3724 struct vm_page *m; 3725 struct pmap *pmap = &curproc->p_vmspace->vm_pmap; 3726 3727 if (bp->b_bufsize < 0) 3728 return (-1); 3729 prot = VM_PROT_READ; 3730 if (bp->b_iocmd == BIO_READ) 3731 prot |= VM_PROT_WRITE; /* Less backwards than it looks */ 3732 for (addr = (caddr_t)trunc_page((vm_offset_t)bp->b_data), pidx = 0; 3733 addr < bp->b_data + bp->b_bufsize; 3734 addr += PAGE_SIZE, pidx++) { 3735 /* 3736 * Do the vm_fault if needed; do the copy-on-write thing 3737 * when reading stuff off device into memory. 3738 * 3739 * NOTE! Must use pmap_extract() because addr may be in 3740 * the userland address space, and kextract is only guarenteed 3741 * to work for the kernland address space (see: sparc64 port). 3742 */ 3743 retry: 3744 if (vm_fault_quick(addr >= bp->b_data ? addr : bp->b_data, 3745 prot) < 0) { 3746 vm_page_lock_queues(); 3747 for (i = 0; i < pidx; ++i) { 3748 vm_page_unhold(bp->b_pages[i]); 3749 bp->b_pages[i] = NULL; 3750 } 3751 vm_page_unlock_queues(); 3752 return(-1); 3753 } 3754 m = pmap_extract_and_hold(pmap, (vm_offset_t)addr, prot); 3755 if (m == NULL) 3756 goto retry; 3757 bp->b_pages[pidx] = m; 3758 } 3759 if (pidx > btoc(MAXPHYS)) 3760 panic("vmapbuf: mapped more than MAXPHYS"); 3761 pmap_qenter((vm_offset_t)bp->b_saveaddr, bp->b_pages, pidx); 3762 3763 kva = bp->b_saveaddr; 3764 bp->b_npages = pidx; 3765 bp->b_saveaddr = bp->b_data; 3766 bp->b_data = kva + (((vm_offset_t) bp->b_data) & PAGE_MASK); 3767 return(0); 3768 } 3769 3770 /* 3771 * Free the io map PTEs associated with this IO operation. 3772 * We also invalidate the TLB entries and restore the original b_addr. 3773 */ 3774 void 3775 vunmapbuf(struct buf *bp) 3776 { 3777 int pidx; 3778 int npages; 3779 3780 npages = bp->b_npages; 3781 pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); 3782 vm_page_lock_queues(); 3783 for (pidx = 0; pidx < npages; pidx++) 3784 vm_page_unhold(bp->b_pages[pidx]); 3785 vm_page_unlock_queues(); 3786 3787 bp->b_data = bp->b_saveaddr; 3788 } 3789 3790 void 3791 bdone(struct buf *bp) 3792 { 3793 3794 mtx_lock(&bdonelock); 3795 bp->b_flags |= B_DONE; 3796 wakeup(bp); 3797 mtx_unlock(&bdonelock); 3798 } 3799 3800 void 3801 bwait(struct buf *bp, u_char pri, const char *wchan) 3802 { 3803 3804 mtx_lock(&bdonelock); 3805 while ((bp->b_flags & B_DONE) == 0) 3806 msleep(bp, &bdonelock, pri, wchan, 0); 3807 mtx_unlock(&bdonelock); 3808 } 3809 3810 int 3811 bufsync(struct bufobj *bo, int waitfor, struct thread *td) 3812 { 3813 3814 return (VOP_FSYNC(bo->__bo_vnode, waitfor, td)); 3815 } 3816 3817 void 3818 bufstrategy(struct bufobj *bo, struct buf *bp) 3819 { 3820 int i = 0; 3821 struct vnode *vp; 3822 3823 vp = bp->b_vp; 3824 KASSERT(vp == bo->bo_private, ("Inconsistent vnode bufstrategy")); 3825 KASSERT(vp->v_type != VCHR && vp->v_type != VBLK, 3826 ("Wrong vnode in bufstrategy(bp=%p, vp=%p)", bp, vp)); 3827 i = VOP_STRATEGY(vp, bp); 3828 KASSERT(i == 0, ("VOP_STRATEGY failed bp=%p vp=%p", bp, bp->b_vp)); 3829 } 3830 3831 void 3832 bufobj_wrefl(struct bufobj *bo) 3833 { 3834 3835 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3836 ASSERT_BO_LOCKED(bo); 3837 bo->bo_numoutput++; 3838 } 3839 3840 void 3841 bufobj_wref(struct bufobj *bo) 3842 { 3843 3844 KASSERT(bo != NULL, ("NULL bo in bufobj_wref")); 3845 BO_LOCK(bo); 3846 bo->bo_numoutput++; 3847 BO_UNLOCK(bo); 3848 } 3849 3850 void 3851 bufobj_wdrop(struct bufobj *bo) 3852 { 3853 3854 KASSERT(bo != NULL, ("NULL bo in bufobj_wdrop")); 3855 BO_LOCK(bo); 3856 KASSERT(bo->bo_numoutput > 0, ("bufobj_wdrop non-positive count")); 3857 if ((--bo->bo_numoutput == 0) && (bo->bo_flag & BO_WWAIT)) { 3858 bo->bo_flag &= ~BO_WWAIT; 3859 wakeup(&bo->bo_numoutput); 3860 } 3861 BO_UNLOCK(bo); 3862 } 3863 3864 int 3865 bufobj_wwait(struct bufobj *bo, int slpflag, int timeo) 3866 { 3867 int error; 3868 3869 KASSERT(bo != NULL, ("NULL bo in bufobj_wwait")); 3870 ASSERT_BO_LOCKED(bo); 3871 error = 0; 3872 while (bo->bo_numoutput) { 3873 bo->bo_flag |= BO_WWAIT; 3874 error = msleep(&bo->bo_numoutput, BO_MTX(bo), 3875 slpflag | (PRIBIO + 1), "bo_wwait", timeo); 3876 if (error) 3877 break; 3878 } 3879 return (error); 3880 } 3881 3882 void 3883 bpin(struct buf *bp) 3884 { 3885 mtx_lock(&bpinlock); 3886 bp->b_pin_count++; 3887 mtx_unlock(&bpinlock); 3888 } 3889 3890 void 3891 bunpin(struct buf *bp) 3892 { 3893 mtx_lock(&bpinlock); 3894 if (--bp->b_pin_count == 0) 3895 wakeup(bp); 3896 mtx_unlock(&bpinlock); 3897 } 3898 3899 void 3900 bunpin_wait(struct buf *bp) 3901 { 3902 mtx_lock(&bpinlock); 3903 while (bp->b_pin_count > 0) 3904 msleep(bp, &bpinlock, PRIBIO, "bwunpin", 0); 3905 mtx_unlock(&bpinlock); 3906 } 3907 3908 #include "opt_ddb.h" 3909 #ifdef DDB 3910 #include <ddb/ddb.h> 3911 3912 /* DDB command to show buffer data */ 3913 DB_SHOW_COMMAND(buffer, db_show_buffer) 3914 { 3915 /* get args */ 3916 struct buf *bp = (struct buf *)addr; 3917 3918 if (!have_addr) { 3919 db_printf("usage: show buffer <addr>\n"); 3920 return; 3921 } 3922 3923 db_printf("buf at %p\n", bp); 3924 db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); 3925 db_printf( 3926 "b_error = %d, b_bufsize = %ld, b_bcount = %ld, b_resid = %ld\n" 3927 "b_bufobj = (%p), b_data = %p, b_blkno = %jd\n", 3928 bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, 3929 bp->b_bufobj, bp->b_data, (intmax_t)bp->b_blkno); 3930 if (bp->b_npages) { 3931 int i; 3932 db_printf("b_npages = %d, pages(OBJ, IDX, PA): ", bp->b_npages); 3933 for (i = 0; i < bp->b_npages; i++) { 3934 vm_page_t m; 3935 m = bp->b_pages[i]; 3936 db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, 3937 (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); 3938 if ((i + 1) < bp->b_npages) 3939 db_printf(","); 3940 } 3941 db_printf("\n"); 3942 } 3943 lockmgr_printinfo(&bp->b_lock); 3944 } 3945 3946 DB_SHOW_COMMAND(lockedbufs, lockedbufs) 3947 { 3948 struct buf *bp; 3949 int i; 3950 3951 for (i = 0; i < nbuf; i++) { 3952 bp = &buf[i]; 3953 if (lockcount(&bp->b_lock)) { 3954 db_show_buffer((uintptr_t)bp, 1, 0, NULL); 3955 db_printf("\n"); 3956 } 3957 } 3958 } 3959 #endif /* DDB */ 3960